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Reynoso-Mejia CA, Troville J, Wagner MG, Hoppel B, Lee FT, Szczykutowicz TP. Needle artifact reduction during interventional CT procedures using a silver filter. BMC Biomed Eng 2024; 6:2. [PMID: 38468322 PMCID: PMC10926571 DOI: 10.1186/s42490-024-00076-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 02/27/2024] [Indexed: 03/13/2024] Open
Abstract
BACKGROUND MAR algorithms have not been productized in interventional imaging because they are too time-consuming. Application of a beam hardening filter can mitigate metal artifacts and doesn't increase computational burden. We evaluate the ability to reduce metal artifacts of a 0.5 mm silver (Ag) additional filter in a Multidetector Computed Tomography (MDCT) scanner during CT-guided biopsy procedures. METHODS A biopsy needle was positioned inside the lung field of an anthropomorphic phantom (Lungman, Kyoto Kagaku, Kyoto, Japan). CT acquisitions were performed with beam energies of 100 kV, 120 kV, 135 kV, and 120 kV with the Ag filter and reconstructed using a filtered back projection algorithm. For each measurement, the CTDIvol was kept constant at 1 mGy. Quantitative profiles placed in three regions of the artifact (needle, needle tip, and trajectory artifacts) were used to obtain metrics (FWHM, FWTM, width at - 100 HU, and absolute error in HU) to evaluate the blooming artifact, artifact width, change in CT number, and artifact range. An image quality analysis was carried out through image noise measurement. A one-way analysis of variance (ANOVA) test was used to find significant differences between the conventional CT beam energies and the Ag filtered 120 kV beam. RESULTS The 120 kV-Ag is shown to have the shortest range of artifacts compared to the other beam energies. For needle tip and trajectory artifacts, a significant reduction of - 53.6% (p < 0.001) and - 48.7% (p < 0.001) in the drop of the CT number was found, respectively, in comparison with the reference beam of 120 kV as well as a significant decrease of up to - 34.7% in the artifact width (width at - 100 HU, p < 0.001). Also, a significant reduction in the blooming artifact of - 14.2% (FWHM, p < 0.001) and - 53.3% (FWTM, p < 0.001) was found in the needle artifact. No significant changes (p > 0.05) in image noise between the conventional energies and the 120 kV-Ag were found. CONCLUSIONS A 0.5 mm Ag additional MDCT filter demonstrated consistent metal artifact reduction generated by the biopsy needle. This reduction may lead to a better depiction of the target and surrounding structures while maintaining image quality.
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Affiliation(s)
| | - Jonathan Troville
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - Martin G Wagner
- Department of Radiology, University of Wisconsin-Madison, Madison, WI, 53705, USA
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | | | - Fred T Lee
- Department of Radiology, University of Wisconsin-Madison, Madison, WI, 53705, USA
- Department of Urology, University of Wisconsin-Madison, Madison, WI, 53705, USA
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, 53705, USA
| | - Timothy P Szczykutowicz
- Department of Radiology, University of Wisconsin-Madison, Madison, WI, 53705, USA.
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI, 53705, USA.
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, 53705, USA.
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Zhang J, Liu M, Liu D, Li X, Lin M, Tan Y, Luo Y, Zeng X, Yu H, Shen H, Wang X, Liu L, Tan Y, Zhang J. Low-dose CT with tin filter combined with iterative metal artefact reduction for guiding lung biopsy. Quant Imaging Med Surg 2022; 12:1359-1371. [PMID: 35111630 DOI: 10.21037/qims-21-555] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 10/08/2021] [Indexed: 12/24/2022]
Abstract
Background Computed tomography (CT) is currently the imaging modality of choice for guiding pulmonary percutaneous procedures. The use of a tin filter allows low-energy photons to be absorbed which contribute little to image quality but increases the radiation dose that a patient receives. Iterative metal artefact reduction (iMAR) was developed to diminish metal artefacts. This study investigated the impact of using tin filtration combined with an iMAR algorithm on dose reduction and image quality in CT-guided lung biopsy. Methods Ninety-nine consecutive patients undergoing CT-guided lung biopsy were randomly assigned to routine-dose CT protocols (groups A and B; without and with iMAR, respectively) or tin filter CT protocols (groups C and D; without or with iMAR, respectively). Subjective image quality was analysed using a 5-point Likert scale. Objective image quality was assessed, and the noise, contrast-to-noise ratio, and figure of merit were compared among the four groups. Metal artefacts were quantified using CT number reduction and metal diameter blurring. The radiation doses, diagnostic performance, and complication rates were also estimated. Results The subjective image quality of the two scan types was compared. Images with iMAR reconstruction were superior to those without iMAR reconstruction (group A: 3.49±0.65 vs. group B: 4.63±0.57; P<0.001, and group C: 3.88±0.66 vs. group D: 4.82±0.39; P<0.001). Images taken with a tin filter were found to have a significantly higher figure-of-merit than those taken without a tin filter (group A: 14,041±7,230 vs. group C: 21,866±10,656; P=0.001, and group B: 13,836±6,849 vs. group D: 21,639±9,964; P=0.001). In terms of metal artefact reduction, tin filtration combined with iMAR showed the lowest CT number reduction (116.62±103.48 HU) and metal diameter blurring (0.85±0.30) among the protocols. The effective radiation dose in the tin filter groups was 73.2% lower than that in the routine-dose groups. The complication rate and diagnostic performance (sensitivity, specificity, and overall accuracy) did not differ significantly between the tin filter and routine-dose groups (all P>0.05). Conclusions Tin filtration combined with an iMAR algorithm may reduce the radiation dose compared to the routine-dose CT protocol, while maintaining comparable diagnostic accuracy and image quality and producing fewer metal artefacts.
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Affiliation(s)
- Jing Zhang
- Department of Radiology, Chongqing University Cancer Hospital, Chongqing, China
| | - Meiling Liu
- Department of Radiology, Chongqing University Cancer Hospital, Chongqing, China
| | - Daihong Liu
- Department of Radiology, Chongqing University Cancer Hospital, Chongqing, China
| | - Xiaoqin Li
- Department of Radiology, Chongqing University Cancer Hospital, Chongqing, China
| | - Meng Lin
- Department of Radiology, Chongqing University Cancer Hospital, Chongqing, China
| | - Yong Tan
- Department of Radiology, Chongqing University Cancer Hospital, Chongqing, China
| | - Yuesheng Luo
- Department of Radiology, Chongqing University Cancer Hospital, Chongqing, China
| | - Xiangfei Zeng
- Department of Radiology, Chongqing University Cancer Hospital, Chongqing, China
| | - Hong Yu
- Department of Radiology, Chongqing University Cancer Hospital, Chongqing, China
| | - Hesong Shen
- Department of Radiology, Chongqing University Cancer Hospital, Chongqing, China
| | - Xiaoxia Wang
- Department of Radiology, Chongqing University Cancer Hospital, Chongqing, China
| | - Leilei Liu
- Department of Radiology, Chongqing University Cancer Hospital, Chongqing, China
| | - Yuchuan Tan
- Department of Radiology, Chongqing University Cancer Hospital, Chongqing, China
| | - Jiuquan Zhang
- Department of Radiology, Chongqing University Cancer Hospital, Chongqing, China
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Hübner F, Schreiner R, Panahi B, Vogl TJ. Evaluation of the thermal sensitivity of porcine liver in CT-guided cryoablation: an initial study. Med Phys 2020; 47:4997-5005. [PMID: 32748398 DOI: 10.1002/mp.14432] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 06/19/2020] [Accepted: 07/24/2020] [Indexed: 11/12/2022] Open
Abstract
PURPOSE To evaluate computed tomography (CT)-based thermometry in cryoablation, the thermal sensitivity of an ex-vivo porcine liver was determined in an initial study design. METHODS The CT-guided cryoablation was performed in three porcine liver samples over a period of 10 min. Fiber optic temperature probes were positioned parallel to the shaft of the cryoprobe in an axial slice orientation. During ablation, temperature measurements were performed simultaneously with CT imaging at 5 s intervals. On the CT images, the average CT number was calculated for a region of interest of 3 × 3 pixels just below the tip of each temperature probe. A linear regression analysis was performed using eleven data sets to determine the dependence of the CT number on the temperature. RESULTS With decreasing temperature, an increasing hypodense area around the tip of the cryoprobe was observed on the CT images and decreasing values of the CT number were determined. Starting at a temperature of - 40°C a linear relation between the CT number and the temperature was determined and a thermal sensitivity of 0.95 HU/°C (R2 = 0.73) was obtained. The thermal sensitivity was used to calculate color-coded temperature maps. The calculated temperature distribution corresponds quantitatively to the increasing hypodense area. CONCLUSIONS A noninvasive CT-based temperature determination during cryoablation in a normal ex vivo porcine liver is feasible. A thermal sensitivity of 0.95 HU/°C was determined by linear regression analysis. A color-coded map of the temperature distribution was presented.
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Affiliation(s)
- Frank Hübner
- Institute of Diagnostic and Interventional Radiology, University Hospital, Theodor-Stern-Kai 7, Frankfurt, 60590, Germany
| | - Roland Schreiner
- Institute of Diagnostic and Interventional Radiology, University Hospital, Theodor-Stern-Kai 7, Frankfurt, 60590, Germany
| | - Bita Panahi
- Institute of Diagnostic and Interventional Radiology, University Hospital, Theodor-Stern-Kai 7, Frankfurt, 60590, Germany
| | - Thomas Josef Vogl
- Institute of Diagnostic and Interventional Radiology, University Hospital, Theodor-Stern-Kai 7, Frankfurt, 60590, Germany
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