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Chen S, Fraum TJ, Eldeniz C, Mhlanga J, Gan W, Vahle T, Krishnamurthy UB, Faul D, Gach HM, Binkley MM, Kamilov US, Laforest R, An H. MR-assisted PET respiratory motion correction using deep-learning based short-scan motion fields. Magn Reson Med 2022; 88:676-690. [PMID: 35344592 DOI: 10.1002/mrm.29233] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Revised: 02/03/2022] [Accepted: 02/23/2022] [Indexed: 11/11/2022]
Abstract
PURPOSE We evaluated the impact of PET respiratory motion correction (MoCo) in a phantom and patients. Moreover, we proposed and examined a PET MoCo approach using motion vector fields (MVFs) from a deep-learning reconstructed short MRI scan. METHODS The evaluation of PET MoCo was performed in a respiratory motion phantom study with varying lesion sizes and tumor to background ratios (TBRs) using a static scan as the ground truth. MRI-based MVFs were derived from either 2000 spokes (MoCo2000 , 5-6 min acquisition time) using a Fourier transform reconstruction or 200 spokes (MoCoP2P200 , 30-40 s acquisition time) using a deep-learning Phase2Phase (P2P) reconstruction and then incorporated into PET MoCo reconstruction. For six patients with hepatic lesions, the performance of PET MoCo was evaluated using quantitative metrics (SUVmax , SUVpeak , SUVmean , lesion volume) and a blinded radiological review on lesion conspicuity. RESULTS MRI-assisted PET MoCo methods provided similar results to static scans across most lesions with varying TBRs in the phantom. Both MoCo2000 and MoCoP2P200 PET images had significantly higher SUVmax , SUVpeak , SUVmean and significantly lower lesion volume than non-motion-corrected (non-MoCo) PET images. There was no statistical difference between MoCo2000 and MoCoP2P200 PET images for SUVmax , SUVpeak , SUVmean or lesion volume. Both radiological reviewers found that MoCo2000 and MoCoP2P200 PET significantly improved lesion conspicuity. CONCLUSION An MRI-assisted PET MoCo method was evaluated using the ground truth in a phantom study. In patients with hepatic lesions, PET MoCo images improved quantitative and qualitative metrics based on only 30-40 s of MRI motion modeling data.
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Affiliation(s)
- Sihao Chen
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Tyler J Fraum
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, MO, USA
| | - Cihat Eldeniz
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, MO, USA
| | - Joyce Mhlanga
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, MO, USA
| | - Weijie Gan
- Department of Computer Science & Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | | | | | - David Faul
- Siemens Medical Solutions USA, Inc., Malvern, PA, USA
| | - H Michael Gach
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA.,Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, MO, USA.,Department of Radiation Oncology, Washington University in St. Louis, St. Louis, MO, USA
| | - Michael M Binkley
- Department of Neurology, Washington University in St. Louis, St. Louis, MO, USA
| | - Ulugbek S Kamilov
- Department of Computer Science & Engineering, Washington University in St. Louis, St. Louis, MO, USA.,Department of Electrical & Systems Engineering, Washington University in St. Louis, St. Louis, MO, USA
| | - Richard Laforest
- Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, MO, USA
| | - Hongyu An
- Department of Biomedical Engineering, Washington University in St. Louis, St. Louis, MO, USA.,Mallinckrodt Institute of Radiology, Washington University in St. Louis, St. Louis, MO, USA.,Department of Neurology, Washington University in St. Louis, St. Louis, MO, USA.,Department of Electrical & Systems Engineering, Washington University in St. Louis, St. Louis, MO, USA
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Cheung AHY, Wu VWC, Cheung ALY, Cai J. Respiratory 4D-Gating F-18 FDG PET/CT Scan for Liver Malignancies: Feasibility in Liver Cancer Patient and Tumor Quantitative Analysis. Front Oncol 2022; 12:789506. [PMID: 35223472 PMCID: PMC8864173 DOI: 10.3389/fonc.2022.789506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Accepted: 01/12/2022] [Indexed: 11/18/2022] Open
Abstract
Purpose To evaluate the potential clinical role and effectiveness of respiratory 4D-gating F-18 FDG PET/CT scan for liver malignancies, relative to routine (3D) F-18 FDG PET/CT scan. Materials and Methods This study presented a prospective clinical study of 16 patients who received F-18 FDG PET/CT scan for known or suspected malignant liver lesions. Ethics approvals were obtained from the ethics committees of the Hong Kong Baptist Hospital and The Hong Kong Polytechnic University. Liver lesions were compared between the gated and ungated image sets, in terms of 1) volume measurement of PET image, 2) accuracy of maximum standardized uptake value (SUVmax), mean standardized uptake value (SUVmean), and 3) accuracy of total lesion glycoses (TLG). Statistical analysis was performed by using a two-tailed paired Student t-test and Pearson correlation test. Results The study population consisted of 16 patients (9 males and 7 females; mean age of 65) with a total number of 89 lesions. The SUVmax and SUVmean measurement of the gated PET images was more accurate than that of the ungated PET images, compared to the static reference images. An average of 21.48% (p < 0.001) reduction of the tumor volume was also observed. The SUVmax and SUVmean of the gated PET images were improved by 19.81% (p < 0.001) and 25.53% (p < 0.001), compared to the ungated PET images. Conclusions We have demonstrated the feasibility of implementing 4D PET/CT scan for liver malignancies in a prospective clinical study. The 4D PET/CT scan for liver malignancies could improve the quality of PET image by improving the SUV accuracy of the lesions and reducing image blurring. The improved accuracy in the classification and identification of liver tumors with 4D PET image would potentially lead to its increased utilization in target delineation of GTV, ITV, and PTV for liver radiotherapy treatment planning in the future.
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Affiliation(s)
- Anson H Y Cheung
- Department of Health Technology & Informatics, The Hong Kong Polytechnic University, Hong Kong, Hong Kong SAR, China.,Radiotherapy and Oncology Department, Hong Kong Baptist Hospital, Hong Kong, Hong Kong SAR, China
| | - Vincent W C Wu
- Department of Health Technology & Informatics, The Hong Kong Polytechnic University, Hong Kong, Hong Kong SAR, China
| | - Andy L Y Cheung
- Department of Health Technology & Informatics, The Hong Kong Polytechnic University, Hong Kong, Hong Kong SAR, China.,Department of Clinical Oncology, Queen Mary Hospital, Hong Kong, Hong Kong SAR, China
| | - Jing Cai
- Department of Health Technology & Informatics, The Hong Kong Polytechnic University, Hong Kong, Hong Kong SAR, China
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Vergalasova I, Cai J. A modern review of the uncertainties in volumetric imaging of respiratory-induced target motion in lung radiotherapy. Med Phys 2020; 47:e988-e1008. [PMID: 32506452 DOI: 10.1002/mp.14312] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 05/15/2020] [Accepted: 05/26/2020] [Indexed: 12/25/2022] Open
Abstract
Radiotherapy has become a critical component for the treatment of all stages and types of lung cancer, often times being the primary gateway to a cure. However, given that radiation can cause harmful side effects depending on how much surrounding healthy tissue is exposed, treatment of the lung can be particularly challenging due to the presence of moving targets. Careful implementation of every step in the radiotherapy process is absolutely integral for attaining optimal clinical outcomes. With the advent and now widespread use of stereotactic body radiation therapy (SBRT), where extremely large doses are delivered, accurate, and precise dose targeting is especially vital to achieve an optimal risk to benefit ratio. This has largely become possible due to the rapid development of image-guided technology. Although imaging is critical to the success of radiotherapy, it can often be plagued with uncertainties due to respiratory-induced target motion. There has and continues to be an immense research effort aimed at acknowledging and addressing these uncertainties to further our abilities to more precisely target radiation treatment. Thus, the goal of this article is to provide a detailed review of the prevailing uncertainties that remain to be investigated across the different imaging modalities, as well as to highlight the more modern solutions to imaging motion and their role in addressing the current challenges.
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Affiliation(s)
- Irina Vergalasova
- Department of Radiation Oncology, Rutgers Cancer Institute of New Jersey, Rutgers University, New Brunswick, NJ, USA
| | - Jing Cai
- Department of Health Technology and Informatics, The Hong Kong Polytechnic University, Kowloon, Hong Kong
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4
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Ichikawa Y, Tomita Y, Ishida M, Kobayashi S, Takeda K, Sakuma H. Usefulness of abdominal belt for restricting respiratory cardiac motion and improving image quality in myocardial perfusion PET. J Nucl Cardiol 2018; 25:407-415. [PMID: 27535413 DOI: 10.1007/s12350-016-0623-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 07/12/2016] [Indexed: 10/21/2022]
Abstract
BACKGROUND The current study evaluated the usefulness of a belt technique for restricting respiratory motion of the heart and for improving image quality of 13N-ammonia myocardial PET/CT, and it assessed the tolerability of the belt technique in the clinical setting. METHODS Myocardial 13N-ammonia PET/CT scanning was performed in 8 volunteers on Discovery PET/CT 690 with an optical respiratory motion tracking system. Emission scans were performed with and without an abdominal belt. The amplitude of left ventricular (LV) respiratory motion was measured on respiratory-gated PET images. The degree of erroneous decreases in regional myocardial uptake was visually assessed on ungated PET images using a 5-point scale (0 = normal, 1/2/3 = mild/moderate/severe decrease, 4 = defect). The tolerability of the belt technique was evaluated in 53 patients. RESULTS All subjects tolerated the belt procedure. The amplitude of the LV respiratory motion decreased significantly with the belt (8.1 ± 7.1 vs 12.1 ± 6.1 mm, P = .0078). The belt significantly improved the image quality scores in the anterior (0.29 ± 0.81 vs 0.71 ± 1.04, P = .015) and inferior (0.33 ± 0.92 vs 1.04 ± 1.04, P < .0001) wall. No adverse events related to the belt technique were observed. CONCLUSIONS The belt technique restricts LV respiratory motion and improves the image quality of myocardial PET/CT, and it is well tolerated by patients.
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Affiliation(s)
- Yasutaka Ichikawa
- Department of Radiology, Mie University Hospital, 2-174 Edobashi, Tsu, Mie, 514-8507, Japan.
| | - Yoya Tomita
- Department of Radiology, Mie University Hospital, 2-174 Edobashi, Tsu, Mie, 514-8507, Japan
| | - Masaki Ishida
- Department of Radiology, Mie University Hospital, 2-174 Edobashi, Tsu, Mie, 514-8507, Japan
| | - Shigeki Kobayashi
- Department of Radiology, Mie University Hospital, 2-174 Edobashi, Tsu, Mie, 514-8507, Japan
| | - Kan Takeda
- Department of Radiology, Mie University Hospital, 2-174 Edobashi, Tsu, Mie, 514-8507, Japan
| | - Hajime Sakuma
- Department of Radiology, Mie University Hospital, 2-174 Edobashi, Tsu, Mie, 514-8507, Japan
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Frood R, McDermott G, Scarsbrook A. Respiratory-gated PET/CT for pulmonary lesion characterisation-promises and problems. Br J Radiol 2018; 91:20170640. [PMID: 29338327 DOI: 10.1259/bjr.20170640] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
2-deoxy-2-(18Fluorine)-fluoro-D-glucose (FDG) PET/CT is an integral part of lung carcinoma staging and frequently used in the assessment of solitary pulmonary nodules. However, a limitation of conventional three-dimensional PET/CT when imaging the thorax is its susceptibility to motion artefact, which blurs the signal from the lesion resulting in inaccurate representation of size and metabolic activity. Respiratory gated (four-dimensional) PET/CT aims to negate the effects of motion artefact and provide a more accurate interpretation of pulmonary nodules and lymphadenopathy. There have been recent advances in technology and a shift from traditional hardware to more streamlined software methods for respiratory gating which should allow more widespread use of respiratory-gating in the future. The purpose of this article is to review the evidence surrounding four-dimensional PET/CT in pulmonary lesion characterisation.
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Affiliation(s)
- Russell Frood
- 1 Department of Nuclear Medicine, Leeds Teaching Hospitals NHS Trust , Leeds , United Kingdom
| | - Garry McDermott
- 2 Department of Medical Physics & Engineering, Leeds Teaching Hospitals NHS Trust , Leeds , United Kingdom
| | - Andrew Scarsbrook
- 1 Department of Nuclear Medicine, Leeds Teaching Hospitals NHS Trust , Leeds , United Kingdom.,3 Leeds Institute of Cancer and Pathology, University of Leeds , Leeds , United Kingdom
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Abstract
PURPOSE OF REVIEW Cardiac positron emission tomography (PET) images often contain errors due to cardiac, respiratory, and patient motion during relatively long image acquisition. Advanced motion compensation techniques may improve PET spatial resolution, eliminate potential artifacts, and ultimately improve the research and clinical capabilities of PET. RECENT FINDINGS Combined cardiac and respiratory gating has only recently been implemented in clinical PET systems. Considering that the gated image bins contain much lower counts than the original PET data, they need to be summed after correcting for motion, forming motion-corrected, high-count image volume. Furthermore, automated image registration techniques can be used to correct for motion between CT attenuation scan and PET acquisition. While motion correction methods are not yet widely used in clinical practice, approaches including dual-gated non-rigid motion correction and the incorporation of motion correction information into the reconstruction process have the potential to markedly improve cardiac PET imaging.
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Affiliation(s)
- Mathieu Rubeaux
- Cedars-Sinai Medical Center, 8700 Beverly Blvd Taper A238, Los Angeles, CA, 90048, USA
| | - Mhairi K Doris
- Cedars-Sinai Medical Center, 8700 Beverly Blvd Taper A238, Los Angeles, CA, 90048, USA.,Centre for Cardiovascular Science, University of Edinburgh, 49 Little France Crescent, Edinburgh EH16 4SB, Scotland, UK
| | - Adam Alessio
- Department of Radiology, University of Washington, Old Fisheries Center, Room 222, 4000 15th Avenue NE, Box 357987, Seattle, WA, 98195-7987, USA
| | - Piotr J Slomka
- Cedars-Sinai Medical Center, 8700 Beverly Blvd Taper A238, Los Angeles, CA, 90048, USA. .,David Geffen School of Medicine, University of California, Los Angeles, CA, USA. .,Cedars-Sinai Medical Center, 8700 Beverly Blvd Ste. A047N, Los Angeles, CA, 90048, USA.
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Shimizu A, Terakawa Y, Morita N, Koshino K, Iida H. The Effects of Misalignment between PET and CT Scans on Brain PET Study Using CT-based Attenuation Correction: A Phantom Study. Nihon Hoshasen Gijutsu Gakkai Zasshi 2016; 72:1216-1221. [PMID: 28003608 DOI: 10.6009/jjrt.2016_jsrt_72.12.1216] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE The aim of this study was to evaluate the effects of inaccurate attenuation correction due to the misalignment between the computed tomography (CT)-based μ-map and the positron emission tomography (PET) data on a brain PET. METHODS CT and PET scans were performed on a 3-dimension (3D) brain phantom, in which the grey matter region was filled with 18F-fluorodeoxyglucose (18F-FDG), and the skull region was filled with/without the bone-equivalent solution. The shifted PET images relative to the CT image were generated by the software-based translation of PET data in the cephalad/caudal and right directions, with a magnitude of the shift up to 30 mm and a step size of 5 mm. The regions of interest (ROIs) were drawn on the areas of the temporal lobes, parietal lobes, thalami, and cerebellums in the no-shifted image (reference). For each ROI, the radioactivity concentrations in the shifted images were compared with those of the reference. RESULTS The errors in the radioactivity concentrations were increased with the increasing magnitude of the shift in all brain regions except for thalamus. For a 5 mm shift in the right direction, ± 10% errors were observed in the left/right temporal lobes. The accuracy of the radioactivity concentration in the temporal lobe was very sensitive to misalignment in the right directions. CONCLUSION The misalignment between CT-based μ-map and PET data had larger effects on the surface regions of the brain rather than on deep brain structures.
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Affiliation(s)
- Akihide Shimizu
- Department of Radiology, National Cerebral and Cardiovascular Center
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Cui Y, Bowsher J, Cai J, Yin FF. Impact of moving target on measurement accuracy in 3D and 4D PET imaging-a phantom study. Adv Radiat Oncol 2016; 2:94-100. [PMID: 28740918 PMCID: PMC5514228 DOI: 10.1016/j.adro.2016.12.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Revised: 11/28/2016] [Accepted: 12/02/2016] [Indexed: 12/25/2022] Open
Abstract
PURPOSE The purpose of this study was to evaluate the impact of tumor motion on maximum standardized uptake value (SUVmax) and metabolic tumor volume (MTV) measurements in both 3-dimensional and respiratory-correlated, 4-dimensional positron emission tomography (PET) imaging. We also evaluated the effect of implementing different attenuation correction methods in 4-dimensional PET image reconstruction on SUVmax and MTV. METHODS AND MATERIALS An anthropomorphic thorax phantom with a spherical ball as a surrogate for a tumor was used. Different types of motion were imposed on the ball to mimic a patient's breathing motion. Three-dimensional PET imaging of the phantom without tumor motion was performed and used as the reference. The ball was then set in motion with different breathing motion traces and imaged with both 3- and 4-dimensional PET methods. The clinical 4-dimensional PET imaging protocol was modified so that 3 different types of attenuation correction images were used for reconstructions: the same free-breathing computed tomography (CT) for all PET phases, the same average intensity projection CT for all PET phases, and 4-dimensional CT for phase-matched attenuation correction. Tumor SUVmax and MTV values that were measured from the moving phantom were compared with the reference values. RESULTS SUVmax that was measured in 3-dimensional PET imaging was different from the reference value by 20.4% on average for the motions that were investigated; this difference decreased to 2.6% with 4-dimensional PET imaging. The measurement of MTV in 4-dimensional PET also showed a similar magnitude of reduction of deviation compared with 3-dimensional PET. Four-dimensional PET with use of phase-matched 4-dimensional CT for attenuation correction showed less variation in SUVmax and MTV among phases compared with 4-dimensional PET with free-breathing CT or average intensity projection CT for attenuation correction. CONCLUSIONS Four-dimensional PET imaging reduces the impact of motion on measured SUVmax and MTV when compared with 3-dimensional PET imaging. Clinical 4-dimensional PET imaging protocols should consider phase-matched 4-dimensional CT imaging for attenuation correction to achieve more accurate measurements.
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Affiliation(s)
- Yunfeng Cui
- Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina
| | - James Bowsher
- Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina
| | - Jing Cai
- Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina
| | - Fang-Fang Yin
- Department of Radiation Oncology, Duke University Medical Center, Durham, North Carolina
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Sindoni A, Minutoli F, Pontoriero A, Iatì G, Baldari S, Pergolizzi S. Usefulness of four dimensional (4D) PET/CT imaging in the evaluation of thoracic lesions and in radiotherapy planning: Review of the literature. Lung Cancer 2016; 96:78-86. [DOI: 10.1016/j.lungcan.2016.03.019] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 03/31/2016] [Indexed: 11/30/2022]
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10
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Interpolated average CT for PET attenuation correction in different lesion characteristics. Nucl Med Commun 2016; 37:297-306. [DOI: 10.1097/mnm.0000000000000435] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
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Nyflot MJ, Lee TC, Alessio AM, Wollenweber SD, Stearns CW, Bowen SR, Kinahan PE. Impact of CT attenuation correction method on quantitative respiratory-correlated (4D) PET/CT imaging. Med Phys 2015; 42:110-20. [PMID: 25563252 DOI: 10.1118/1.4903282] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Respiratory-correlated positron emission tomography (PET/CT) 4D PET/CT is used to mitigate errors from respiratory motion; however, the optimal CT attenuation correction (CTAC) method for 4D PET/CT is unknown. The authors performed a phantom study to evaluate the quantitative performance of CTAC methods for 4D PET/CT in the ground truth setting. METHODS A programmable respiratory motion phantom with a custom movable insert designed to emulate a lung lesion and lung tissue was used for this study. The insert was driven by one of five waveforms: two sinusoidal waveforms or three patient-specific respiratory waveforms. 3DPET and 4DPET images of the phantom under motion were acquired and reconstructed with six CTAC methods: helical breath-hold (3DHEL), helical free-breathing (3DMOT), 4D phase-averaged (4DAVG), 4D maximum intensity projection (4DMIP), 4D phase-matched (4DMATCH), and 4D end-exhale (4DEXH) CTAC. Recovery of SUV(max), SUV(mean), SUV(peak), and segmented tumor volume was evaluated as RC(max), RC(mean), RC(peak), and RC(vol), representing percent difference relative to the static ground truth case. Paired Wilcoxon tests and Kruskal-Wallis ANOVA were used to test for significant differences. RESULTS For 4DPET imaging, the maximum intensity projection CTAC produced significantly more accurate recovery coefficients than all other CTAC methods (p < 0.0001 over all metrics). Over all motion waveforms, ratios of 4DMIP CTAC recovery were 0.2 ± 5.4, -1.8 ± 6.5, -3.2 ± 5.0, and 3.0 ± 5.9 for RC(max), RC(peak), RC(mean), and RC(vol). In comparison, recovery coefficients for phase-matched CTAC were -8.4 ± 5.3, -10.5 ± 6.2, -7.6 ± 5.0, and -13.0 ± 7.7 for RC(max), RC(peak), RC(mean), and RC(vol). When testing differences between phases over all CTAC methods and waveforms, end-exhale phases were significantly more accurate (p = 0.005). However, these differences were driven by the patient-specific respiratory waveforms; when testing patient and sinusoidal waveforms separately, patient waveforms were significantly different between phases (p < 0.0001) while the sinusoidal waveforms were not significantly different (p = 0.98). When considering only the subset of 4DMATCH images that corresponded to the end-exhale image phase, 4DEXH, mean and interquartile range were similar to 4DMATCH but variability was considerably reduced. CONCLUSIONS Comparative advantages in accuracy and precision of SUV metrics and segmented volumes were demonstrated with the use of the maximum intensity projection and end-exhale CT attenuation correction. While respiratory phase-matched CTAC should in theory provide optimal corrections, image artifacts and differences in implementation of 4DCT and 4DPET sorting can degrade the benefit of this approach. These results may be useful to guide the implementation, analysis, and development of respiratory-correlated thoracic PET/CT in the radiation oncology and diagnostic settings.
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Affiliation(s)
- Matthew J Nyflot
- Department of Radiation Oncology, University of Washington, Seattle, Washington 98195-6043
| | - Tzu-Cheng Lee
- Department of Bioengineering, University of Washington, Seattle, Washington 98195-6043
| | - Adam M Alessio
- Department of Radiology, University of Washington, Seattle, Washington 98195-6043
| | | | | | - Stephen R Bowen
- Department of Radiation Oncology, University of Washington, Seattle, Washington 98195-6043 and Department of Radiology, University of Washington, Seattle, Washington 98195-6043
| | - Paul E Kinahan
- Department of Radiology, University of Washington, Seattle, Washington 98195-6043
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12
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Utility of respiratory-gated small-animal PET/CT in the chronologic evaluation of an orthotopic lung cancer transplantation mouse model. Radiol Phys Technol 2015; 8:266-77. [PMID: 25921487 DOI: 10.1007/s12194-015-0316-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2014] [Revised: 04/16/2015] [Accepted: 04/20/2015] [Indexed: 01/07/2023]
Abstract
Our aim in this study was to clarify the effects of respiratory-gated PET in the evaluation of lung cancer according to the (18)F-FDG uptake in an orthotopic transplantation mouse model. We created such a model, and we performed PET/CT. The mice were divided into two groups according to tumor volume: a small-tumor group (<20 mm(3)) and a large-tumor group (>20 mm(3)). We reconstructed the following conditions based on list-mode data: non-gated (3D) images and gated (4D) images, divided based on the respiratory cycle (expiration phase, stable phase, and inspiration phase). We calculated the maximum standardized uptake values (SUVmax) in each phase. We used the % difference [= (4D SUVmax - 3D SUVmax)/3D PET SUVmax × 100 (%)] to evaluate the differences in the 4D SUVmax and 3D SUVmax. The 4D SUVmax values were significantly higher than the 3D SUVmax, regardless of the tumor size. The % difference for the small tumors was greater than that for the large tumors, and it was highest in the stable phase. We conclude that the SUVmax in the stable phase under respiratory-gated PET are the most reliable. The SUVmax observed under non-gated PET are considered to be more frequently underestimated in cases involving small tumors than in those involving large tumors. In the chronologic study evaluating the time course of tumor development, the size of the tumor is small in early stage, and respiratory-gated PET is effective in reducing the underestimation of such tumors caused by respiratory motion.
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13
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Kruis MF, van de Kamer JB, Vogel WV, Belderbos JS, Sonke JJ, van Herk M. Clinical evaluation of respiration-induced attenuation uncertainties in pulmonary 3D PET/CT. EJNMMI Phys 2015; 2:4. [PMID: 26501806 PMCID: PMC4545225 DOI: 10.1186/s40658-014-0107-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Accepted: 12/30/2014] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND In contemporary positron emission tomography (PET)/computed tomography (CT) scanners, PET attenuation correction is performed by means of a CT-based attenuation map. Respiratory motion can however induce offsets between the PET and CT data. Studies have demonstrated that these offsets can cause errors in quantitative PET measures. The purpose of this study is to quantify the effects of respiration-induced CT differences on the attenuation correction of pulmonary 18-fluordeoxyglucose (FDG) 3D PET/CT in a patient population and to investigate contributing factors. METHODS For 32 lung cancer patients, 3D-CT, 4D-PET and 4D-CT data were acquired. The 4D FDG PET data were attenuation corrected (AC) using a free-breathing 3D-CT (3D-AC), the end-inspiration CT (EI-AC), the end-expiration CT (EE-AC) or phase-by-phase (P-AC). After reconstruction and AC, the 4D-PET data were averaged. In the 4Davg data, we measured maximum tumour standardised uptake value (SUV)max in the tumour, SUVmean in a lung volume of interest (VOI) and average SUV (SUVmean) in a muscle VOI. On the 4D-CT, we measured the lung volume differences and CT number changes between inhale and exhale in the lung VOI. RESULTS Compared to P-AC, we found -2.3% (range -9.7% to 1.2%) lower tumour SUVmax in EI-AC and 2.0% (range -0.9% to 9.5%) higher SUVmax in EE-AC. No differences in the muscle SUV were found. The use of 3D-AC led to respiration-induced SUVmax differences up to 20% compared to the use of P-AC. SUVmean differences in the lung VOI between EI-AC and EE-AC correlated to average CT differences in this region (ρ = 0.83). SUVmax differences in the tumour correlated to the volume changes of the lungs (ρ = -0.55) and the motion amplitude of the tumour (ρ = 0.53), both as measured on the 4D-CT. CONCLUSIONS Respiration-induced CT variations in clinical data can in extreme cases lead to SUV effects larger than 10% on PET attenuation correction. These differences were case specific and correlated to differences in CT number in the lungs.
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Affiliation(s)
- Matthijs F Kruis
- Department of Radiation Oncology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands.
| | - Jeroen B van de Kamer
- Department of Radiation Oncology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands.
| | - Wouter V Vogel
- Department of Radiation Oncology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands. .,Department of Nuclear Medicine, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands.
| | - José Sa Belderbos
- Department of Radiation Oncology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands.
| | - Jan-Jakob Sonke
- Department of Radiation Oncology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands.
| | - Marcel van Herk
- Department of Radiation Oncology, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX, Amsterdam, The Netherlands.
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Kawakami W, Takemura A, Yokoyama K, Nakajima K, Yokoyama S, Koshida K. The use of positron emission tomography/computed tomography imaging in radiation therapy: a phantom study for setting internal target volume of biological target volume. Radiat Oncol 2015; 10:1. [PMID: 25567003 PMCID: PMC4299814 DOI: 10.1186/s13014-014-0315-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 12/18/2014] [Indexed: 12/26/2022] Open
Abstract
BACKGROUND Fluorodeoxyglucose ((18)F-FDG) positron emission tomography/computed tomography (PET/CT) is an important method for detecting tumours, planning radiotherapy treatment, and evaluating treatment responses. However, using the standardized uptake value (SUV) threshold with PET imaging may be suitable not to determine gross tumour volume but to determine biological target volume (BTV). The aim of this study was to extract internal target volume of BTV from PET images. METHODS Three spherical densities of (18)F-FDG were employed in a phantom with an air or water background with repetitive motion amplitudes of 0-30 mm. The PET data were reconstructed with attenuation correction (AC) based on CT images obtained by slow CT scanning (SCS) or helical CT scanning (HCS). The errors in measured SUVmax and volumes calculated using SUV threshold values based on SUVmax (THmax) in experiments performed with varying extents of respiratory motion and AC were analysed. RESULTS A partial volume effect (PVE) was not observed in spheres with diameters of ≥ 28 mm. When calculating SUVmax and THmax, using SCS for AC yielded smaller variance than using HCS (p<0.05). For spheres of 37- and 28-mm diameters in the phantom with either an air or water background, significant differences were observed when mean THmax of 30-, 20-, or 10-mm amplitude were compared with the stationary conditions (p<0.05). The average THmax values for 37-mm and 28-mm spheres with an air background were 0.362 and 0.352 in non-motion, respectively, and the mean THmax values for 37-mm and 28-mm spheres with a water background were 0.404 and 0.387 in non-motion and 0.244 and 0.263 in motion, respectively. When the phantom background was air, regardless of sphere concentration or size, THmax was dependent only on motion amplitude. CONCLUSIONS We found that there was no PVE for spheres with ≥ 28-mm diameters, and differences between SUVmax and THmax were reduced by using SCS for AC. In the head-and-neck and the abdomen, the standard values of THmax were 0.25 and 0.40 with and without respiratory movement, respectively. In the lungs, the value of THmax became the approximate expression depending on motion amplitude.
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Affiliation(s)
- Wataru Kawakami
- Department of Radiological Technology, Public Central Hospital of Matto Ishikawa, 3-8, Kuramitsu, Hakusan City, Ishikawa Pref, 924-8588, Japan.
- Department of Quantum Medical Technology, Division of Health Sciences, Graduate School of Medical Science, Kanazawa University, Ishikawa, Japan.
| | - Akihiro Takemura
- Department of Quantum Medical Technology, Division of Health Sciences, Graduate School of Medical Science, Kanazawa University, Ishikawa, Japan.
| | - Kunihiko Yokoyama
- PET Imaging Center, Public Central Hospital of Matto Ishikawa, Ishikawa, Japan.
| | - Kenichi Nakajima
- Department of Nuclear Medicine, Kanazawa University Hospital, Ishikawa, Japan.
| | - Syoichi Yokoyama
- Department of Radiological Technology, Public Central Hospital of Matto Ishikawa, 3-8, Kuramitsu, Hakusan City, Ishikawa Pref, 924-8588, Japan.
| | - Kichiro Koshida
- Department of Quantum Medical Technology, Division of Health Sciences, Graduate School of Medical Science, Kanazawa University, Ishikawa, Japan.
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Miwa K. [Management of respiratory motion in FDG-PET/CT: respiratory-gated and deep-inspiration breath-hold techniques]. Nihon Hoshasen Gijutsu Gakkai Zasshi 2014; 70:1344-52. [PMID: 25410343 DOI: 10.6009/jjrt.2014_jsrt_70.11.1344] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Yang J, Yamamoto T, Mazin SR, Graves EE, Keall PJ. The potential of positron emission tomography for intratreatment dynamic lung tumor tracking: a phantom study. Med Phys 2014; 41:021718. [PMID: 24506609 DOI: 10.1118/1.4861816] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
PURPOSE This study aims to evaluate the potential and feasibility of positron emission tomography for dynamic lung tumor tracking during radiation treatment. The authors propose a center of mass (CoM) tumor tracking algorithm using gated-PET images combined with a respiratory monitor and investigate the geometric accuracy of the proposed algorithm. METHODS The proposed PET dynamic lung tumor tracking algorithm estimated the target position information through the CoM of the segmented target volume on gated PET images reconstructed from accumulated coincidence events. The information was continuously updated throughout a scan based on the assumption that real-time processing was supported (actual processing time at each frame ≈ 10 s). External respiratory motion and list-mode PET data were acquired from a phantom programmed to move with measured respiratory traces (external respiratory motion and internal target motion) from human subjects, for which the ground truth target position was known as a function of time. The phantom was cylindrical with six hollow sphere targets (10, 13, 17, 22, 28, and 37 mm in diameter). The measured respiratory traces consisted of two sets: (1) 1D-measured motion from ten healthy volunteers and (2) 3D-measured motion from four lung cancer patients. The authors evaluated the geometric accuracy of the proposed algorithm by quantifying estimation errors (Euclidean distance) between the actual motion of targets (1D-motion and 3D-motion traces) and CoM trajectories estimated by the proposed algorithm as a function of time. RESULTS The time-averaged error of 1D-motion traces over all trajectories of all targets was 1.6 mm. The error trajectories decreased with time as coincidence events were accumulated. The overall error trajectory of 1D-motion traces converged to within 2 mm in approximately 90 s. As expected, more accurate results were obtained for larger targets. For example, for the 37 mm target, the average error over all 1D-motion traces was 1.1 mm; and for the 10 mm target, the average error over all 1D-motion traces was 2.8 mm. The overall time-averaged error of 3D-motion traces was 1.6 mm, which was comparable to that of the 1D-motion traces. There were small variations in the errors between the 3D-motion traces, although the motion trajectories were very different. The accuracy of the estimates was consistent for all targets except for the smallest. CONCLUSIONS The authors developed an algorithm for dynamic lung tumor tracking using list-mode PET data and a respiratory motion signal, and demonstrated proof-of-principle for PET-guided lung tumor tracking. The overall tracking error in phantom studies is less than 2 mm.
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Affiliation(s)
- Jaewon Yang
- Department of Electrical Engineering, Stanford University, Stanford, California 94305 and Department of Radiation Oncology, Stanford University, Stanford, California 94305
| | - Tokihiro Yamamoto
- Department of Radiation Oncology, University of California Davis, Sacramento, California 95817
| | | | - Edward E Graves
- Department of Radiation Oncology, Stanford University, Stanford, California 94305
| | - Paul J Keall
- Radiation Physics Laboratory, University of Sydney, Sydney, NSW 2006, Australia
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Abstract
Aim Respiratory motion affects cardiac PET-computed tomography (CT) imaging by reducing attenuation correction (AC) accuracy and by introducing blur. The aim of this study was to compare three approaches for reducing motion-induced AC errors and evaluate the inclusion of respiratory motion correction. Materials and methods AC with a helical CT was compared with averaged cine and gated cine CT, as well as with a pseudo-gated CT, which was produced by applying PET-derived motion fields to the helical CT. Data-driven gating was used to produce respiratory-gated PET and CT images, and 60 NH3 PET scans were attenuation corrected with each of the CTs. Respiratory motion correction was applied to the gated and pseudo-gated attenuation-corrected PET images. Results Anterior and lateral wall intensity measured in attenuation-corrected PET images generally increased when PET-CT alignment improved and decreased when alignment degraded. On average, all methods improved PET-CT liver and cardiac alignment, and increased anterior wall intensity by more than 10% in 36, 33 and 25 cases for the averaged, gated and pseudo-gated CTAC PET images, respectively. However, cases were found where alignment worsened and severe artefacts resulted. This occurred in more cases and to a greater extent for the averaged and gated CT, where the anterior wall intensity reduced by more than 10% in 21 and 24 cases, respectively, compared with six cases for the pseudo-gated CT. Application of respiratory motion correction increased the average anterior and inferior wall intensity, but only 13% of cases increased by more than 10%. Conclusion All methods improved average respiratory-induced AC errors; however, some severe artefacts were produced. The pseudo-gated CT was found to be the most robust method.
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Foster B, Bagci U, Mansoor A, Xu Z, Mollura DJ. A review on segmentation of positron emission tomography images. Comput Biol Med 2014; 50:76-96. [PMID: 24845019 DOI: 10.1016/j.compbiomed.2014.04.014] [Citation(s) in RCA: 219] [Impact Index Per Article: 21.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2013] [Revised: 03/19/2014] [Accepted: 04/16/2014] [Indexed: 11/20/2022]
Abstract
Positron Emission Tomography (PET), a non-invasive functional imaging method at the molecular level, images the distribution of biologically targeted radiotracers with high sensitivity. PET imaging provides detailed quantitative information about many diseases and is often used to evaluate inflammation, infection, and cancer by detecting emitted photons from a radiotracer localized to abnormal cells. In order to differentiate abnormal tissue from surrounding areas in PET images, image segmentation methods play a vital role; therefore, accurate image segmentation is often necessary for proper disease detection, diagnosis, treatment planning, and follow-ups. In this review paper, we present state-of-the-art PET image segmentation methods, as well as the recent advances in image segmentation techniques. In order to make this manuscript self-contained, we also briefly explain the fundamentals of PET imaging, the challenges of diagnostic PET image analysis, and the effects of these challenges on the segmentation results.
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Affiliation(s)
- Brent Foster
- Center for Infectious Disease Imaging, Department of Radiology and Imaging Sciences, National Institutes of Health (NIH), Bethesda, MD 20892, United States
| | - Ulas Bagci
- Center for Infectious Disease Imaging, Department of Radiology and Imaging Sciences, National Institutes of Health (NIH), Bethesda, MD 20892, United States.
| | - Awais Mansoor
- Center for Infectious Disease Imaging, Department of Radiology and Imaging Sciences, National Institutes of Health (NIH), Bethesda, MD 20892, United States
| | - Ziyue Xu
- Center for Infectious Disease Imaging, Department of Radiology and Imaging Sciences, National Institutes of Health (NIH), Bethesda, MD 20892, United States
| | - Daniel J Mollura
- Center for Infectious Disease Imaging, Department of Radiology and Imaging Sciences, National Institutes of Health (NIH), Bethesda, MD 20892, United States
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Zhang Y, Hu J, Lu HJ, Li JP, Wang N, Li WW, Zhou YC, Liu JY, Wang SJ, Wang J, Li X, Ma WL, Wei LC, Shi M. Determination of an optimal standardized uptake value of fluorodeoxyglucose for positron emission tomography imaging to assess pathological volumes of cervical cancer: a prospective study. PLoS One 2013; 8:e75159. [PMID: 24265671 PMCID: PMC3827047 DOI: 10.1371/journal.pone.0075159] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Accepted: 08/12/2013] [Indexed: 12/01/2022] Open
Abstract
Purpose To determine the optimal standardized uptake value (SUV) of 18F-fluorodeoxyglucose (18F-FDG) for positron emission tomography (PET) imaging, at which the PET-defined gross tumor volume (GTVPET) best matches with the pathological volume (GTVPATH) in the cervical cancer. Materials and Methods Ten patients with the cervical cancer who underwent surgery were enrolled in this study. The excised specimens were processed for whole-mount serial sections and H-E staining. The tumor borders were outlined in sections under a microscope, histopathological images were scanned and the GTVPATH calculated. The GTVPET was delineated automatically by using various percentages relative to the maximal SUV and absolute SUV. The optimal threshold SUV was further obtained as the value at which the GTVPET best matched with the GTVPATH. Results An average of 85±10% shrinkage of tissue was observed after the formalin fixation. The GTVPATH was 13.38±2.80 cm3 on average. The optimal threshold on percentile SUV and absolute SUV were 40.50%±3.16% and 7.45±1.10, respectively. The correlation analysis showed that the optimal percentile SUV threshold was inversely correlated with GTVPATH (p<0.05) and tumor diameter (p<0.05). The absolute SUV was also positively correlated with SUVmax (p<0.05). Conclusion The pathological volume could provide the more accurate tumor volume. The optimal SUV of FDG for PET imaging by use of GTVPATH as standard for cervical cancer target volume delineation was thus determined in this study, and more cases are being evaluated to substantiate this conclusion.
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Affiliation(s)
- Ying Zhang
- Department of Radiation Oncology, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Jing Hu
- Department of Radiation Oncology, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Hong-Jun Lu
- Department of Radiation Oncology, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Jian-Ping Li
- Department of Radiation Oncology, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Ning Wang
- Department of Radiation Oncology, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Wei-Wei Li
- Department of Radiation Oncology, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Yong-Chun Zhou
- Department of Radiation Oncology, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Jun-Yue Liu
- Department of Radiation Oncology, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Sheng-Jun Wang
- Department of Nuclear Medicine, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Jing Wang
- Department of Nuclear Medicine, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Xia Li
- Department of Pathology, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Wan-Ling Ma
- Department of Radiology, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Li-Chun Wei
- Department of Radiation Oncology, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
- * E-mail: (LCW); (MS)
| | - Mei Shi
- Department of Radiation Oncology, Xijing Hospital, The Fourth Military Medical University, Xi'an, China
- * E-mail: (LCW); (MS)
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Sun T, Wu TH, Wang SJ, Yang BH, Wu NY, Mok GSP. Low dose interpolated average CT for thoracic PET/CT attenuation correction using an active breathing controller. Med Phys 2013; 40:102507. [DOI: 10.1118/1.4820976] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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21
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Zaidi H, Nkoulou R, Bond S, Baskin A, Schindler T, Ratib O, Declerck J. Computed tomography calcium score scan for attenuation correction of N-13 ammonia cardiac positron emission tomography: effect of respiratory phase and registration method. Int J Cardiovasc Imaging 2013; 29:1351-60. [DOI: 10.1007/s10554-013-0207-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/25/2012] [Accepted: 03/12/2013] [Indexed: 11/24/2022]
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Hugo GD, Rosu M. Advances in 4D radiation therapy for managing respiration: part I - 4D imaging. Z Med Phys 2012; 22:258-71. [PMID: 22784929 PMCID: PMC4153750 DOI: 10.1016/j.zemedi.2012.06.009] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2012] [Revised: 06/14/2012] [Accepted: 06/18/2012] [Indexed: 11/21/2022]
Abstract
Techniques for managing respiration during imaging and planning of radiation therapy are reviewed, concentrating on free-breathing (4D) approaches. First, we focus on detailing the historical development and basic operational principles of currently-available "first generation" 4D imaging modalities: 4D computed tomography, 4D cone beam computed tomography, 4D magnetic resonance imaging, and 4D positron emission tomography. Features and limitations of these first generation systems are described, including necessity of breathing surrogates for 4D image reconstruction, assumptions made in acquisition and reconstruction about the breathing pattern, and commonly-observed artifacts. Both established and developmental methods to deal with these limitations are detailed. Finally, strategies to construct 4D targets and images and, alternatively, to compress 4D information into static targets and images for radiation therapy planning are described.
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Affiliation(s)
- Geoffrey D Hugo
- Department of Radiation Oncology, Virginia Commonwealth University, Richmond, Virginia 23298, USA.
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Pan T, Zaidi H. Attenuation Correction Strategies for Positron Emission Tomography/Computed Tomography and 4-Dimensional Positron Emission Tomography/Computed Tomography. PET Clin 2012; 8:37-50. [PMID: 27157814 DOI: 10.1016/j.cpet.2012.09.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
This article discusses attenuation correction strategies in positron emission tomography/computed tomography (PET/CT) and 4-dimensional PET/CT imaging. Average CT scan derived from averaging the high temporal resolution CT images is effective in improving the registration of the CT and the PET images and quantification of the PET data. It underscores list-mode data acquisition in 4-dimensional PET, and introduces 4-dimensional CT, popular in thoracic treatment planning, to 4-dimensional PET/CT.
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Affiliation(s)
- Tinsu Pan
- Department of Imaging Physics, MD Anderson Cancer Center, The University of Texas, Unit 1352, 1515 Holcome Boulevard, Houston, TX 77030, USA.
| | - Habib Zaidi
- Division of Nuclear Medicine and Molecular Imaging, Geneva University Hospital, CH-1211 Geneva, Switzerland; Geneva Neuroscience Center, Geneva University, CH-1211 Geneva, Switzerland; Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, 9700 RB Groningen, Netherlands
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Four-Dimensional Image Reconstruction Strategies in Cardiac-Gated and Respiratory-Gated PET Imaging. PET Clin 2012; 8:51-67. [PMID: 27157815 DOI: 10.1016/j.cpet.2012.10.005] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Cardiac and respiratory movements pose significant challenges to image quality and quantitative accuracy in PET imaging. Cardiac and/or respiratory gating attempt to address this issue, but instead lead to enhanced noise levels. Direct four-dimensional (4D) PET image reconstruction incorporating motion compensation has the potential to minimize noise amplification while removing considerable motion blur. A wide-ranging choice of such techniques is reviewed in this work. Future opportunities and the challenges facing the adoption of 4D PET reconstruction and its role in basic and clinical research are also discussed.
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25
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Sun T, Mok GSP. Techniques for respiration-induced artifacts reductions in thoracic PET/CT. Quant Imaging Med Surg 2012; 2:46-52. [PMID: 23256058 PMCID: PMC3496495 DOI: 10.3978/j.issn.2223-4292.2012.02.01] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2012] [Accepted: 02/01/2012] [Indexed: 01/25/2023]
Abstract
The advent of positron emission tomography/computed tomography (PET/CT) provides fusion of both anatomical and functional information. CT-based attenuation correction replaced (68)Ge-based attenuation correction for shortening acquisition time, improving image quality and quantitative accuracy. However, due to the temporal difference of PET and CT, mis-registration and motion artifacts are observed in the attenuation-corrected images mainly due to the respiratory motion. Reducing the spatial mismatch of the PET and CT reconstructed image remains a challenge. This review provides an introduction to various respiratory image artifacts reduction techniques especially for thoracic lesions, including breathing instruction based methods, CT protocol based methods and 4-dimensional PET/CT. The advantages and drawbacks of different methods are also discussed.
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Affiliation(s)
- Tao Sun
- Department of Electrical and Computer Engineering, Faculty of Science and Technology, University of Macau, Macau SAR, China
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Nye JA, Faber TL. Current state of hybrid imaging: attenuation correction and fusion. J Nucl Cardiol 2011; 18:729-40. [PMID: 21553160 DOI: 10.1007/s12350-011-9380-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2011] [Accepted: 04/11/2011] [Indexed: 11/30/2022]
Affiliation(s)
- Jonathon A Nye
- Department of Radiology and Imaging Sciences, Emory University, Emory University Hospital, 1364 Clifton Road, NE, Atlanta, GA, 30322, USA.
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McQuaid SJ, Lambrou T, Hutton BF. A novel method for incorporating respiratory-matched attenuation correction in the motion correction of cardiac PET–CT studies. Phys Med Biol 2011; 56:2903-15. [DOI: 10.1088/0031-9155/56/10/002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Wahl RL, Herman JM, Ford E. The promise and pitfalls of positron emission tomography and single-photon emission computed tomography molecular imaging-guided radiation therapy. Semin Radiat Oncol 2011; 21:88-100. [PMID: 21356477 PMCID: PMC4337868 DOI: 10.1016/j.semradonc.2010.11.004] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
External beam radiation therapy procedures have, until recently, been planned almost exclusively using anatomic imaging methods. Molecular imaging using hybrid positron emission tomography (PET)/computed tomography scanning or single-photon emission computed tomography (SPECT) imaging has provided new insights into the precise location of tumors (staging) and the extent and character of the biologically active tumor volume (BTV) and has provided differential response information during and after therapy. In addition to the commonly used radiotracer (18)F-fluoro- 2-deoxyD-glucose (FDG), additional radiopharmaceuticals are being explored to image major physiological processes as well as tumor biological properties, such as hypoxia, proliferation, amino acid accumulation, apoptosis, and receptor expression, providing the potential to target or boost the radiation dose to a biologically relevant region within a tumor, such as the most hypoxic or most proliferative area. Imaging using SPECT agents has furthered the possibility of limiting dose to functional normal tissues. PET can also portray the distribution of particle therapy by displaying activated species in situ. With both PET and SPECT imaging, fundamental physical issues of limited spatial resolution relative to the biological process, partial volume effects for quantification of small volumes, image misregistration, motion, and edge delineation must be carefully considered and can differ by agent or the method applied. Molecular imaging-guided radiation therapy (MIGRT) is a rapidly evolving and promising area of investigation and clinical translation. As MIGRT evolves, evidence must continue to be gathered to support improved clinical outcomes using MIGRT versus purely anatomic approaches.
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Affiliation(s)
- Richard L Wahl
- Department of Radiology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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Optimal gating compared to 3D and 4D PET reconstruction for characterization of lung tumours. Eur J Nucl Med Mol Imaging 2011; 38:843-55. [PMID: 21222120 PMCID: PMC3070073 DOI: 10.1007/s00259-010-1716-6] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Accepted: 12/16/2010] [Indexed: 11/01/2022]
Abstract
PURPOSE We investigated the added value of a new respiratory amplitude-based PET reconstruction method called optimal gating (OG) with the aim of providing accurate image quantification in lung cancer. METHODS FDG-PET imaging was performed in 26 lung cancer patients during free breathing using a 24-min list-mode acquisition on a PET/CT scanner. The data were reconstructed using three methods: standard 3D PET, respiratory-correlated 4D PET using a phase-binning algorithm, and OG. These datasets were compared in terms of the maximum SUV (SUVmax) in the primary tumour (main endpoint), noise characteristics, and volumes using thresholded regions of SUV 2.5 and 40% of the SUVmax. RESULTS SUVmax values from the 4D method (13.7 ± 5.6) and the OG method (14.1 ± 6.5) were higher (4.9 ± 4.8%, p < 0.001 and 6.9 ± 8.8%, p < 0.001, respectively) than that from the 3D method (13.1 ± 5.4). SUVmax did not differ between the 4D and OG methods (2.0 ± 8.4%, p = NS). Absolute and relative threshold volumes did not differ between methods, except for the 40% SUVmax volume in which the value from the 3D method was lower than that from the 4D method (-5.3 ± 7.1%, p = 0.007). The OG method exhibited less noise than the 4D method. Variations in volumes and SUVmax of up to 40% and 27%, respectively, of the individual gates of the 4D method were also observed. CONCLUSION The maximum SUVs from the OG and 4D methods were comparable and significantly higher than that from the 3D method, yet the OG method was visibly less noisy than the 4D method. Based on the better quantification of the maximum and the less noisy appearance, we conclude that OG PET is a better alternative to both 3D PET, which suffers from breathing averaging, and the noisy images of a 4D PET.
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Verellen D, Depuydt T, Gevaert T, Linthout N, Tournel K, Duchateau M, Reynders T, Storme G, De Ridder M. Gating and tracking, 4D in thoracic tumours. Cancer Radiother 2010; 14:446-54. [PMID: 20673737 DOI: 10.1016/j.canrad.2010.06.002] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2010] [Accepted: 06/03/2010] [Indexed: 12/25/2022]
Abstract
The limited ability to control for a tumour's location compromises the accuracy with which radiation can be delivered to tumour-bearing tissue. The resultant requirement for larger treatment volumes to accommodate target uncertainty restricts the radiation dose because more surrounding normal tissue is exposed. With image-guided radiation therapy (IGRT), these volumes can be optimized and tumouricidal doses may be delivered, achieving maximum tumour control with minimal complications. Moreover, with the ability of high precision dose delivery and real-time knowledge of the target volume location, IGRT has initiated the exploration of new indications in radiotherapy such as hypofractionated radiotherapy (or stereotactic body radiotherapy), deliberate inhomogeneous dose distributions coping with tumour heterogeneity (dose painting by numbers and biologically conformal radiation therapy), and adaptive radiotherapy. In short: "individualized radiotherapy". Tumour motion management, especially for thoracic tumours, is a particular problem in this context both for the delineation of tumours and organs at risk as well as during the actual treatment delivery. The latter will be covered in this paper with some examples based on the experience of the UZ Brussel. With the introduction of the NOVALIS system (BrainLAB, Feldkirchen, Germany) in 2000 and consecutive prototypes of the ExacTrac IGRT system, gradually a hypofractionation treatment protocol was introduced for the treatment of lung tumours and liver metastases evolving from motion-encompassing techniques towards respiratory-gated radiation therapy with audio-visual feedback and most recently dynamic tracking using the VERO system (BrainLAB, Feldkirchen, Germany). This evolution will be used to illustrate the recent developments in this particular field of research.
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Affiliation(s)
- D Verellen
- Department of Radiotherapy, UZ Brussel, Oncologisch Centrum, Laarbeeklaan 101, 1090 Brussels, Belgium.
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Wells RG, Ruddy TD, DeKemp RA, DaSilva JN, Beanlands RS. Single-Phase CT Aligned to Gated PET for Respiratory Motion Correction in Cardiac PET/CT. J Nucl Med 2010; 51:1182-90. [DOI: 10.2967/jnumed.109.070011] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Importance of gated CT acquisition for the quantitative improvement of the gated PET/CT in moving phantom. Ann Nucl Med 2010; 24:507-14. [PMID: 20549401 DOI: 10.1007/s12149-010-0388-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2010] [Accepted: 04/25/2010] [Indexed: 10/19/2022]
Abstract
OBJECTIVE The aim of this study was to investigate the utility of gated PET/CT and CT attenuation correction (AC) for the quantitation of radioactivity. METHODS An ellipse phantom containing six spheres, ranging from 10 to 37 mm in diameter, was filled with 36.7 kBq/mL of F-18. The respiratory motion was simulated by a motor-driven plastic platform to move the phantom with a displacement of 2 cm in the craniocaudal direction at a frequency of 15/min. With the phantom at rest, PET/CT data were acquired and used as a standard (nonmotion). With the phantom in motion, PET data were acquired in both the static and gated modes (sPET and gPET, respectively). Helical CT (HCT), slow CT (SCT), average CT (ACT), and four-dimensional CT (4DCT) were acquired and used to correct attenuation. On both PET and CT images, the maximum radioactivity, dimensions, and CT numbers were measured on the central slices. RESULTS In nonmotion, recovery coefficients whose spheres were 22 mm or smaller gradually decreased. Regarding motion, the PET counts of the spheres in the static acquisition were lower than those acquired in nonmotion with either type of CTAC (sPET-HCT: -43.8%, sPET-SCT: -51.4%, sPET-ACT: -49.5%). Gated acquisition of PET significantly improved the PET counts (gPET-HCT: -30.1%) (p < 0.05), while additional gated acquisition of CT significantly improved them further (gPET-4DCT: -15.2%) (p < 0.01). The dimensions of sPET were overestimated, but those of gPET were close to the standard values. The SCT significantly overestimated the dimensions, and the water density area decreased (p < 0.01). The 4DCT images were similar to the HCT images. CONCLUSIONS In respiratory motion, PET acquisition in the static mode underestimated the radioactivity and overestimated the dimensions. Neither SCT nor ACT improved these errors. Although PET acquisition in the gated mode improved the quantification of PET/CT images, the additional gated CT acquisition using 4DCT is required for further improvement.
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Okubo M, Nishimura Y, Nakamatsu K, Okumura M, Shibata T, Kanamori S, Hanaoka K, Hosono M. Radiation treatment planning using positron emission and computed tomography for lung and pharyngeal cancers: a multiple-threshold method for [(18)F]fluoro-2-deoxyglucose activity. Int J Radiat Oncol Biol Phys 2010; 77:350-6. [PMID: 20457349 DOI: 10.1016/j.ijrobp.2009.05.025] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2008] [Revised: 02/13/2009] [Accepted: 05/12/2009] [Indexed: 12/09/2022]
Abstract
PURPOSE Clinical applicability of a multiple-threshold method for [(18)F]fluoro-2-deoxyglucose (FDG) activity in radiation treatment planning was evaluated. METHODS AND MATERIALS A total of 32 patients who underwent positron emission and computed tomography (PET/CT) simulation were included; 18 patients had lung cancer, and 14 patients had pharyngeal cancer. For tumors of <or=2 cm, 2 to 5 cm, and >5 cm, thresholds were defined as 2.5 standardized uptake value (SUV), 35%, and 20% of the maximum FDG activity, respectively. The cervical and mediastinal lymph nodes with the shortest axial diameter of >or=10 mm were considered to be metastatic on CT (LNCT). The retropharyngeal lymph nodes with the shortest axial diameter of >or=5 mm on CT and MRI were also defined as metastatic. Lymph nodes showing maximum FDG activity greater than the adopted thresholds for radiation therapy planning were designated LNPET-RTP, and lymph nodes with a maximum FDG activity of >or=2.5 SUV were regarded as malignant and were designated LNPET-2.5 SUV. RESULTS The sizes of gross tumor volumes on PET (GTVPET) with the adopted thresholds in the axial plane were visually well fitted to those of GTV on CT (GTVCT). However, the volumes of GTVPET were larger than those of GTVCT, with significant differences (p < 0.0001) for lung cancer, due to respiratory motion. For lung cancer, the numbers of LNCT, LNPET-RTP, and LNPET-2.5 SUV were 29, 28, and 34, respectively. For pharyngeal cancer, the numbers of LNCT, LNPET-RTP, and LNPET-2.5 SUV were 14, 9, and 15, respectively. CONCLUSIONS Our multiple thresholds were applicable for delineating the primary target on PET/CT simulation. However, these thresholds were inaccurate for depicting malignant lymph nodes.
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Affiliation(s)
- Mitsuru Okubo
- Department of Radiation Oncology, Kinki University School of Medicine, 377-2 Ohno-Higashi, Osaka-Sayama, Osaka 589-8511, Japan
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(18)F-FDG PET-CT respiratory gating in characterization of pulmonary lesions: approximation towards clinical indications. Ann Nucl Med 2010; 24:207-14. [PMID: 20177834 DOI: 10.1007/s12149-010-0345-2] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2009] [Accepted: 01/15/2010] [Indexed: 10/19/2022]
Abstract
AIM To evaluate the effect of the 18F-FDG PET-CT respiratory gating (4D) study in the correct documentation of pulmonary lesions with faint uptake in standard PET-CT. METHODS Forty-two pulmonary lesions with a low or no detectable uptake of FDG (SUV(max) < 2.5) in 3D PET-CT were prospectively evaluated in 28 patients (19 males and 9 females), mean age 66.5 years (41-81). 22 patients had neoplastic background. A conventional PET-CT (3D) total body scan was performed approximately 60 min after iv injection of a mean dose of 370 MBq. Furthermore, a 4D PET-CT (synchronized with respiratory movement) thorax study was acquired. SUV(max) was determined for each lesion in both studies. For the 4D studies, we selected the SUV(max) in respiratory period with the highest uptake ("best bin"). We calculated the SUV(max) percentage difference between 3D and 4D PET-CT (% difference = SUV(max) 4D - SUV(max) 3D/SUV(max) 3D x 100) and the relation of this value with the size and locations of the lesions. In 4D study, any lesion with SUV(max) > or = 2.5 was classified as malignant. We assessed the changes of lesion classification (from benign to malignant) applying the 4D technique. The final diagnosis was obtained by histological assessment or clinical and radiological follow-up longer than 12 months. RESULTS Forty out of 42 lesions showed an increase of SUV(max) in the 4D study with respect to 3D. The mean SUV(max) in the 3D and 4D PET-CT studies were 1.33 (+/-0.59) and 2.26 (+/-0.87), respectively. The SUV(max) percentage difference mean between both techniques was 83.3% (+/-80.81).The smaller the lesion the greater was the SUV(max) percentage difference (P < 0.05). No differences were observed depending on the location of the lesion. In 40% of cases, there was a change in the final classification of lesions from benign to malignant. In the final diagnosis, 24 lesions were malignant. 4D PET-CT diagnosed correctly the 52% of them. CONCLUSIONS The 4D PET-CT study permitted a better characterization of malignant lung lesions compared with the standard PET-CT, because of its higher sensitivity. 4D PET-CT is a recommendable technique in the early diagnosis of malignant lesions.
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Tonkopi E, Chi PCM, Mawlawi O, Riegel AC, Rohren EM, Macapinlac HA, Pan T. Average CT in PET studies of colorectal cancer patients with metastasis in the liver and esophageal cancer patients. J Appl Clin Med Phys 2010. [PMID: 20160693 PMCID: PMC3883558 DOI: 10.1120/jacmp.v11i1.3073] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Average CT (ACT) and PET have a similar temporal resolution and it has been shown to improve registration of the CT and PET data for PET/CT imaging of the thorax. The purpose of this study was to quantify the effect of ACT attenuation correction on PET for gross tumor volume (GTV) delineation with standardized uptake value (SUV) for liver and esophageal lesions. Our study included 48 colorectal cancer patients with metastasis in the liver and 52 esophageal cancer patients. These patients underwent a routine PET/CT scan followed by a cine CT scan of the thoracic region for ACT. Differences between the two PET data sets (PETHCT and PETACT) corrected with the helical CT (HCT) and ACT were quantified by analyzing image alignment, maximum SUV (SUVmax), and GTV. The 67% of the colorectal and 73% of the esophageal studies demonstrated misregistration between the PETHCT and HCT data. ACT was effective in removing misregistration artifacts in 65% of the misregisted colorectal and in 76% of the misregisted esophageal cancer patients. Misregistration between the CT and PET data affected GTVs due to the change in SUVmax with ACT. A change of SUVmax greater than 20% between PETHCT and PETACT was found in 15% of the colorectal and 17% of the esophageal cases. Our results demonstrated a more pronounced effect of misregistration for the smaller lesions (<5cm3) near the diaphragm (<5cm). ACT was effective in improving registration between the CT and PET data in PET/CT for the colorectal and esophageal cancer patients. PACS number: 87.58.Fg
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Affiliation(s)
- Elena Tonkopi
- Department of Imaging Physics, The University of Texas M. D. Anderson Cancer Center, Houston, TX 77030, USA
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Perrin R, Evans PM, Webb S, Partridge M. The use of PET images for radiotherapy treatment planning: An error analysis using radiobiological endpoints. Med Phys 2010; 37:516-31. [DOI: 10.1118/1.3276776] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
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Grotus N, Reader AJ, Stute S, Rosenwald JC, Giraud P, Buvat I. Fully 4D list-mode reconstruction applied to respiratory-gated PET scans. Phys Med Biol 2009; 54:1705-21. [PMID: 19242055 DOI: 10.1088/0031-9155/54/6/020] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
(18)F-fluoro-deoxy-glucose ((18)F-FDG) positron emission tomography (PET) is one of the most sensitive and specific imaging modalities for the diagnosis of non-small cell lung cancer. A drawback of PET is that it requires several minutes of acquisition per bed position, which results in images being affected by respiratory blur. Respiratory gating techniques have been developed to deal with respiratory motion in the PET images. However, these techniques considerably increase the level of noise in the reconstructed images unless the acquisition time is increased. The aim of this paper is to evaluate a four-dimensional (4D) image reconstruction algorithm that combines the acquired events in all the gates whilst preserving the motion deblurring. This algorithm was compared to classic ordered subset expectation maximization (OSEM) reconstruction of gated and non-gated images, and to temporal filtering of gated images reconstructed with OSEM. Two datasets were used for comparing the different reconstruction approaches: one involving the NEMA IEC/2001 body phantom in motion, the other obtained using Monte-Carlo simulations of the NCAT breathing phantom. Results show that 4D reconstruction reaches a similar performance in terms of the signal-to-noise ratio (SNR) as non-gated reconstruction whilst preserving the motion deblurring. In particular, 4D reconstruction improves the SNR compared to respiratory-gated images reconstructed with the OSEM algorithm. Temporal filtering of the OSEM-reconstructed images helps improve the SNR, but does not achieve the same performance as 4D reconstruction. 4D reconstruction of respiratory-gated images thus appears as a promising tool to reach the same performance in terms of the SNR as non-gated acquisitions while reducing the motion blur, without increasing the acquisition time.
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Abstract
PET/CT is an effective tool for the diagnosis, staging and restaging of cancer patients. It combines the complementary information of functional PET images and anatomical CT images in one imaging session. Conventional stand-alone PET has been replaced by PET/CT for improved patient comfort, patient throughput, and most importantly the proven clinical outcome of PET/CT over that of PET and that of separate PET and CT. There are over two thousand PET/CT scanners installed worldwide since 2001. Oncology is the main application for PET/CT. Fluorine-18 deoxyglucose is the choice of radiopharmaceutical in PET for imaging the glucose uptake in tissues, correlated with an increased rate of glycolysis in many tumor cells. New molecular targeted agents are being developed to improve the accuracy of targeting different disease states and assessing therapeutic response. Over 50% of cancer patients receive radiation therapy (RT) in the course of their disease treatment. Clinical data have demonstrated that the information provided by PET/CT often changes patient management of the patient and/or modifies the RT plan from conventional CT simulation. The application of PET/CT in RT is growing and will become increasingly important. Continuing improvement of PET/CT instrumentation will also make it easier for radiation oncologists to integrate PET/CT in RT. The purpose of this article is to provide a review of the current PET/CT technology, to project the future development of PET and CT for PET/CT, and to discuss some issues in adopting PET/CT in RT and potential improvements in PET/CT simulation of the thorax in radiation therapy.
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Affiliation(s)
- Tinsu Pan
- Department of Imaging Physics, M. D. Anderson Cancer Center, The University of Texas, Houston, Texas 77030, USA.
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Daouk J, Fin L, Bailly P, Meyer ME. Improved attenuation correction via appropriate selection of respiratory-correlated PET data. COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE 2008; 92:90-98. [PMID: 18676054 DOI: 10.1016/j.cmpb.2008.06.014] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2008] [Revised: 05/30/2008] [Accepted: 06/25/2008] [Indexed: 05/26/2023]
Abstract
PURPOSE We propose a respiratory-correlated PET data processing method (called "BH-CT-based") based on breath-hold CT acquisition to reduce the smearing effect and improve the attenuation correction. The resulting images are compared with the ungated PET images acquired using a standard, free-breathing clinical protocol. METHODS The BH-CT-based method consisted of a list-mode acquisition with simultaneous respiratory signal recording. An additional breath-hold CT acquisition was also performed in order to define a tissue position from which PET events can be selected. A phantom study featured a 0.5-ml sphere (filled with 18F-fluorodeoxyglucose ((18)F-FDG) solution) pushed onto a rubber balloon (filled with (18)F-FDG solution and iodinated contrast agent). The feasibility of the BH-CT-based method was also assessed in two patients. RESULTS In the phantom study, the contrast-to-noise ratios (CNRs) were -1.6 for the Ungated volume and 5.1 for the BH-CT-based volume. For patients, CNRs were higher for BH-CT-based volumes than those for Ungated volumes (17.3 vs. 6.3 and 7.3 vs. 3.8, for patients 1 and 2, respectively). Bias-variance measurements were performed and yielded bias reduction of 40% with BH-CT-based. CONCLUSION The application of a BH-CT-based method decreases motion bias in PET images. This method resolves issues related to both PET-to-CT misregistration and erroneous attenuation correction and increases lesion detectability.
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Affiliation(s)
- Joël Daouk
- Nuclear Medicine Department, Amiens University Medical Center, Amiens, France
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Respiratory motion handling is mandatory to accomplish the high-resolution PET destiny. Eur J Nucl Med Mol Imaging 2008; 35:1961-70. [PMID: 18787822 DOI: 10.1007/s00259-008-0931-x] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2008] [Accepted: 08/18/2008] [Indexed: 10/21/2022]
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Okubo M, Nishimura Y, Nakamatsu K, Okumura M, Shibata T, Kanamori S, Hanaoka K, Hosono M. Static and moving phantom studies for radiation treatment planning in a positron emission tomography and computed tomography (PET/CT) system. Ann Nucl Med 2008; 22:579-86. [DOI: 10.1007/s12149-008-0166-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2007] [Accepted: 03/15/2008] [Indexed: 10/21/2022]
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Abstract
Accurate anatomical localization of functional abnormalities obtained with the use of positron emission tomography (PET) is known to be problematic. Although tracers such as (18)F-fluorodeoxyglucose ((18)F-FDG) visualize certain normal anatomical structures, the spatial resolution is generally inadequate for accurate anatomic localization of pathology. Combining PET with a high-resolution anatomical imaging modality such as computed tomography (CT) can resolve the localization issue as long as the images from the two modalities are accurately coregistered. However, software-based registration techniques have difficulty accounting for differences in patient positioning and involuntary movement of internal organs, often necessitating labor-intensive nonlinear mapping that may not converge to a satisfactory result. Acquiring both CT and PET images in the same scanner obviates the need for software registration and routinely provides accurately aligned images of anatomy and function in a single scan. A CT scanner positioned in line with a PET scanner and with a common patient couch and operating console has provided a practical solution to anatomical and functional image registration. Axial translation of the couch between the 2 modalities enables both CT and PET data to be acquired during a single imaging session. In addition, the CT images can be used to generate essentially noiseless attenuation correction factors for the PET emission data. By minimizing patient movement between the CT and PET scans and accounting for the axial separation of the two modalities, accurately registered anatomical and functional images can be obtained. Since the introduction of the first PET/CT prototype more than 6 years ago, numerous patients with cancer have been scanned on commercial PET/CT devices worldwide. The commercial designs feature multidetector spiral CT and high-performance PET components. Experience has demonstrated an increased level of accuracy and confidence in the interpretation of the combined study as compared with studies acquired separately, particularly in distinguishing pathology from normal, physiologic tracer uptake and precisely localizing abnormal foci. Combined PET/CT scanners represent an important evolution in technology that has helped to bring molecular imaging to the forefront in cancer diagnosis, staging and therapy monitoring.
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Affiliation(s)
- David W Townsend
- Department of Medicine, University of Tennessee Medical Center, Knoxville, TN 37920-6999, USA.
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Pönisch F, Richter C, Just U, Enghardt W. Attenuation correction of four dimensional (4D) PET using phase-correlated 4D-computed tomography. Phys Med Biol 2008; 53:N259-68. [DOI: 10.1088/0031-9155/53/13/n03] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Nehmeh SA, Erdi YE. Respiratory Motion in Positron Emission Tomography/Computed Tomography: A Review. Semin Nucl Med 2008; 38:167-76. [DOI: 10.1053/j.semnuclmed.2008.01.002] [Citation(s) in RCA: 244] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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van Loon J, Offermann C, Bosmans G, Wanders R, Dekker A, Borger J, Oellers M, Dingemans AM, van Baardwijk A, Teule J, Snoep G, Hochstenbag M, Houben R, Lambin P, De Ruysscher D. 18FDG-PET based radiation planning of mediastinal lymph nodes in limited disease small cell lung cancer changes radiotherapy fields: A planning study. Radiother Oncol 2008; 87:49-54. [PMID: 18342967 DOI: 10.1016/j.radonc.2008.02.019] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2007] [Revised: 02/12/2008] [Accepted: 02/16/2008] [Indexed: 11/18/2022]
Affiliation(s)
- Judith van Loon
- Department of Radiation Oncology (Maastro Clinic), GROW Research Institute, University Hospital Maastricht, Maastricht, The Netherlands.
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Abstract
Molecular imaging using PET has evolved from a vigorous academic field into the clinical arena. Considerable advances have been made in the design of high-resolution standalone PET and combined PET/CT units dedicated to clinical whole-body scanning. Likewise, much worthwhile research focused on the development of quantitative imaging protocols incorporating accurate data correction techniques and sophisticated image reconstruction algorithms. Since its inception, photon attenuation in biological tissues has been identified as the most important physical degrading factor affecting PET image quality and quantitative accuracy. Various strategies have been devised to determine an accurate attenuation map to enable correction for nonlinear photon attenuation in whole-body PET studies. This article presents the physical and methodological basis of photon attenuation and summarizes state-of-the-art developments in algorithms used to derive the attenuation map aiming at accurate attenuation compensation of PET data. Future prospects, research trends, and challenges are identified, and directions for future research are discussed.
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Affiliation(s)
- Habib Zaidi
- Division of Nuclear Medicine, Geneva University Hospital, CH-1211 Geneva 4, Switzerland.
| | | | - Abass Alavi
- Division of Nuclear Medicine, Department of Radiology, Hospital of the University of Pennsylvania, 3400 Spruce Street, Philadelphia, PA 19104, USA
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Hamill JJ, Bosmans G, Dekker A. Respiratory-gated CT as a tool for the simulation of breathing artifacts in PET and PET/CT. Med Phys 2008; 35:576-85. [DOI: 10.1118/1.2829875] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
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van Dalen JA, Vogel WV, Corstens FHM, Oyen WJG. Multi-modality nuclear medicine imaging: artefacts, pitfalls and recommendations. Cancer Imaging 2007; 7:77-83. [PMID: 17535775 PMCID: PMC1931515 DOI: 10.1102/1470-7330.2007.0014] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
Multi-modality imaging is rapidly becoming an essential tool in oncology. Clinically, the best example of multimodality imaging is seen in the rapid evolution of hybrid positron emission tomography (PET)/computed tomography (CT) and single positron emission computed tomography (SPECT)/CT scanners. However, use of multi-modality imaging is prone to artefacts and pitfalls. Important artefacts that may lead to clinical misinterpretation result from the use of CT data to correct for attenuation and the existence of mismatches between the fused images, for example due to respiratory movement. Furthermore, for institutions who proceed from a standalone PET to a hybrid PET-CT, there is an issue of interchangeability between these systems, especially for quantitative studies. Another issue is visualisation: hospital PACS is not sufficiently capable of adequately viewing integrated images. This article reviews and illustrates the most common artefacts and pitfalls that can be encountered in multi-modality nuclear medicine imaging. For correct management of oncological patients it is essential to be able to detect and correctly interpret these artefacts and pitfalls. Therefore, solutions and recommendations to these problems are provided.
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Affiliation(s)
- Jorn A van Dalen
- Radboud University Medical Centre Nijmegen, Department of Nuclear Medicine, Nijmegen, The Netherlands.
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