Accuracy of whole-body dual-modality fluorine-18-2-fluoro-2-deoxy-D-glucose positron emission tomography and computed tomography (FDG-PET/CT) for tumor staging in solid tumors: comparison with CT and PET

Clinical value of (18)F-FDG PET/CT in postoperative monitoring for patients with colorectal carcinoma

OBJECTIVE

To evaluate the clinical value of (18)F-FDG PET/CT in postoperative monitoring for patients with colorectal carcinoma.

METHODS

66 postoperative patients with colorectal carcinoma underwent whole-body FDG PET/CT. The final histopathological and formal clinical follow-up findings were used as gold standard to determine the sensitivity and specificity of FDG PET/CT and enhanced CT of the same periods.

RESULTS

The sensitivity and specificity of FDG PET/CT in detecting recurrence are 96.30%, 94.87% (while enhanced CT are 70.37% and 87.18% respectively). The sensitivity and specificity in detecting metastasis are 95.35%, 82.61% (enhanced CT are 61.90%, 75.00%). SUVmax was significantly higher in malignant lesions [range 4.16-22.00, mean±standard deviation (x±s) 8.06±4.30] than in benign ones (range 1.18-6.25, x±s 2.82±1.02).

CONCLUSION

At present, whole-body (18)F-FDG PET/CT is an advanced diagnostic imaging technique in detecting loco-regional recurrence and metastasis in postoperative patients with colorectal carcinoma for its higher sensitivity and specificity.

Incidental thyroid carcinoma by FDG-PET/CT: a study of clinicopathological characteristics

BACKGROUND

The rising incidence of incidental thyroid carcinoma (ITC) detected during fluoro-2-deoxy-D: -glucose (FDG)-positron emission tomography (PET)/computed tomography (CT) scanning poses a challenge to clinicians. The present study aims to critically evaluate the clinicopathological characteristics of ITC detected by FDG-PET/CT.

METHODS

Among the 557 patients managed at our institution, 40 (7.2%) patients were identified as having ITC. Of these, 22 patients had their tumor detected by FDG-PET/CT (PET group) and 11 by ultrasonography (USG group). Additional bedside ultrasonography ± fine-needle aspiration (FNA) was done in all patients at their clinic visit. The clinicopathological characteristics were compared between the PET and USG groups.

RESULTS

The PET group had significantly more patients with history of nonthyroidal malignancy (P < 0.001). Papillary carcinoma was the most common histological type in both groups. Despite having similar histological and prognostic features including tumor size, tumor multifocality, capsular invasion, extrathyroidal extension, and lymph node metastases, tumor bilaterality (or presence of contralateral tumor focus) was significantly more frequent in the PET than the USG group (P = 0.04). The tumors were also more advanced by the tumor-node-metastasis (TNM) staging system in the PET group (P = 0.021). None of the contralateral tumor foci were evident preoperatively. One patient in the USG group developed metastatic thyroid carcinoma in neck lymph nodes 28 months after thyroid resection.

CONCLUSION

ITC by FDG-PET/CT had higher incidence of tumor bilaterality than those detected by ultrasonography. Total thyroidectomy should be considered for ITC detected by FDG-PET/CT even for tumor size <10 mm.

Preoperative lymph-node staging of invasive urothelial bladder cancer with 18F-fluorodeoxyglucose positron emission tomography/computed axial tomography and magnetic resonance imaging: correlation with histopathology

OBJECTIVE

The treatment and prognosis of bladder cancer are based on the depth of primary tumour invasion and the presence of metastases. A highly accurate preoperative tumour, node, metastasis (TNM) staging is critical to proper patient management and treatment. This study retrospectively investigated the value of ¹⁸F-fluorodeoxyglucose (FDG) positron emission tomography/computed axial tomography (¹⁸F-FDG PET/CT) and magnetic resonance imaging (MRI) for preoperative N staging of bladder cancer. Material and methods. From June 2006 to January 2008, 48 consecutive patients diagnosed with bladder cancer were referred to preoperative staging including MRI and ¹⁸F-FDG PET/CT. Eighteen out of 48 patients underwent radical cystoprostatectomy including removal of lymph nodes for histology, and were included in the study. Values of ¹⁸F-FDG PET/CT and MRI for regional N staging were compared to histopathology findings, the gold standard. Results. ¹⁸F-FDG PET/CT and MRI were performed in 18 patients. The specificities for detection of lymph-node metastases for MRI and ¹⁸F-FDG PET/CT were 80% (n = 15) and 93.33% (n = 15), respectively. The negative predictive values were 80% (n = 15) and 87.5% (n = 16) for MRI and ¹⁸F-FDG PET/CT, respectively. The differences in specificity and negative predictive values were not statistically significant. Conclusions. No significant statistical difference between ¹⁸F-FDG PET/CT and MRI for preoperative N staging of urothelial bladder cancer was found in the study. However, the trend of the data indicates an advantage of ¹⁸F-FDG PET/CT over MRI. Larger prospective studies are needed to elucidate the role of ¹⁸F-FDG PET/CT in N staging of bladder cancer.

18F-FDG PET/CT of patients with cancer: comparison of whole-body and limited whole-body technique

OBJECTIVE

Use of the routine field of view for whole-body (18)F-FDG PET/CT can lead to underestimation of the true extent of the disease because metastasis outside the typical base of skull to upper thigh field of view can be missed. The purpose of this study was to evaluate the incremental added value of true whole-body as opposed to this limited whole-body PET/CT of cancer patients.

MATERIALS AND METHODS

True whole-body FDG PET/CT, from the top of the skull to the bottom of the feet, was performed on 500 consecutively registered patients. A log was kept of cases of suspected malignancy outside the typical limited whole-body field of view. Suspected lesions in the brain, skull, and extremities were verified by correlation with surgical pathologic or clinical follow-up findings.

RESULTS

Fifty-nine of 500 patients had PET/CT findings suggestive of malignancy outside the limited whole-body field of view. Thirty-one of those patients had known or suspected malignancy outside the limited whole-body field of view at the time of the true whole-body study. Among the other 28 patients, follow-up data were not available for two, six had false-positive findings, and new cancerous involvement was confirmed in 20. Detection of malignancy outside the limited whole-body field of view resulted in a change in management in 65% and in staging in 55% of the 20 cases.

CONCLUSION

Our study showed that 20 of 500 (4.0%) of patients had previously unsuspected malignancy outside the typical limited whole-body field of view. Detection of such malignancy resulted in a change in management in 13 of 500 cases (2.6%). We propose that adopting a true whole-body field of view in the imaging of cancer patients may lead to more accurate staging and restaging than achieved with the routinely used limited whole-body field of view.

PET/CT today and tomorrow in veterinary cancer diagnosis and monitoring: fundamentals, early results and future perspectives

Functional imaging using positron emission tomography (PET) plays an important role in the diagnosis, staging, image-guided treatment planning and monitoring of malignant diseases. PET imaging complements conventional anatomical imaging such as computed tomography (CT) and magnetic resonance imaging (MRI). The strength of CT scanning lies in its high spatial resolution, allowing for anatomical characterization of disease. PET imaging, however, moves beyond anatomy and characterizes tissue based on functions such as metabolic rate. Combined PET/CT scanners were introduced commercially in 2001 and a number of technological advancements have since occurred. Radiolabelled tracers such as (18)F-fluorodeoxyglucose (FDG) and (18)F-fluorothymidine (FLT) allow visualization of various metabolic processes within cancer cells. Many studies in human oncology evaluating the utility of PET/CT have demonstrated clinical benefits. Few veterinary studies have been performed, but initial studies show promise for improved detection of malignancy, more thorough staging of canine cancer and determination of early response and disease recrudescence.

Tumor survivin is downregulated by the antisense oligonucleotide LY2181308: a proof-of-concept, first-in-human dose study

PURPOSE

Enhanced tumor cell survival through expression of inhibitors of apoptosis (IAP) is a hallmark of cancer. Survivin, an IAP absent from most normal tissues, is overexpressed in many malignancies and associated with a poorer prognosis. We report the first-in-human dose study of LY2181308, a second-generation antisense oligonucleotide (ASO) directed against survivin mRNA.

PATIENTS AND METHODS

A dose-escalation study evaluating the safety, pharmacokinetics, and pharmacodynamics of LY2181308 administered intravenously for 3 hours as a loading dose on 3 consecutive days and followed by weekly maintenance doses. Patients were eligible after signing informed consent, had exhausted approved anticancer therapies and agreed to undergo pre- and posttreatment tumor biopsies to evaluate reduction of survivin protein and gene expression.

RESULTS

A total of 40 patients were treated with LY2181308 at doses of 100 to 1,000 mg. Twenty-six patients were evaluated at the recommended phase 2 dose of 750 mg, at which level serial tumor sampling and [(11)C]LY2183108 PET (positron emission tomography) imaging demonstrated that ASO accumulated within tumor tissue, reduced survivin gene and protein expression by 20% and restored apoptotic signaling in tumor cells in vivo. Pharmacokinetics were consistent with preclinical modeling, exhibiting rapid tissue distribution, and terminal half-life of 31 days.

CONCLUSIONS

The tumor-specific, molecularly targeted effects demonstrated by this ASO in man underpin confirmatory studies evaluating its therapeutic efficacy in cancer.

Detection of occult melanoma by preoperative positron emission tomography-computed tomography and intraoperative ultrasonography

BACKGROUND

18F-Fluorodeoxyglucose positron emission tomography-computed tomography (PET-CT) has become a common imaging modality for detecting metastatic melanoma. However, the identification of lesions intraoperatively can be difficult.

OBJECTIVE/METHODS

We describe an innovative multimodality approach to tumor localization using preoperative PET-CT and intraoperative ultrasonography and describe cases in which this technique was used.

RESULTS

The use of these two modalities together enabled resection of multiple occult metastatic lesions in the patients presented.

CONCLUSION

The use of this multimodality approach will be important in ensuring that all known metastatic disease sites are resected and represents an important concept in the setting of metastatic melanoma resection.

Diagnostic accuracy of fused positron emission tomography/magnetic resonance mammography: initial results

OBJECTIVES

The aim of this study was to evaluate the diagnostic accuracy of fused fluoro-deoxy-D-glucose positron emission tomography/magnetic resonance mammography (FDG-PET/MRM) in breast cancer patients and to compare FDG-PET/MRM with MRM.

METHODS

27 breast cancer patients (mean age 58.9±9.9 years) underwent MRM and prone FDG-PET. Images were fused software-based to FDG-PET/MRM images. Histopathology served as the reference standard to define the following parameters for both MRM and FDG-PET/MRM: sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy for the detection of breast cancer lesions. Furthermore, the number of patients with correctly determined lesion focality was assessed. Differences between both modalities were assessed by McNemaŕs test (p<0.05). The number of patients in whom FDG-PET/MRM would have changed the surgical approach was determined.

RESULTS

58 breast lesions were evaluated. The sensitivity, specificity, PPV, NPV and accuracy were 93%, 60%, 87%, 75% and 85% for MRM, respectively. For FDG-PET/MRM they were 88%, 73%, 90%, 69% and 92%, respectively. FDG-PET/MRM was as accurate for lesion detection (p = 1) and determination of the lesions' focality (p = 0.7722) as MRM. In only 1 patient FDG-PET/MRM would have changed the surgical treatment.

CONCLUSION

FDG-PET/MRM is as accurate as MRM for the evaluation of local breast cancer. FDG-PET/MRM defines the tumours' focality as accurately as MRM and may have an impact on the surgical treatment in only a small portion of patients. Based on these results, FDG-PET/MRM cannot be recommended as an adjunct or alternative to MRM.

Diagnostic accuracy of whole-body MRI/DWI image fusion for detection of malignant tumours: a comparison with PET/CT

OBJECTIVE

To prospectively evaluate the diagnostic accuracy of whole-body T2-weighted (wbT2), whole-body diffusion-weighted imaging (wbDWI) and wbT2/wbDWI image fusion for malignant tumour detection compared with PET/CT.

METHODS

Sixty-eight patients (44 men; 60 ± 14 years) underwent PET/CT for staging of malignancy and were consecutively examined by 1.5-Tesla MRI including wbT2 and wbDWI. Two radiologists independently assessed wbDWI, wbT2, wbT2 + wbDWI (side-by-side) and wbT2 + wbDWI + wbT2/wbDWI image fusion for the presence of malignancy. PET/CT served as a reference standard.

RESULTS

PET/CT revealed 374 malignant lesions in 48/64 (75%) patients. Detection rates and positive predictive value (PPV) of wbT2 and wbDWI alone were 64% and 84%, and 57% and 93%, respectively. Detection rates and PPV of wbT2 and wbDWI for side-by-side analysis without and with fused images were 72% and 89%, and 74% and 91%, respectively. The detection rate was significantly higher with side-by-side analysis and fused image analysis compared with wbT2 and wbDWI alone (p = .0159; p < .0001). There was no significant difference between fused image interpretation and side-by-side analysis.

CONCLUSIONS

WbDWI allows detection of malignant lesions with a similar detection rate to wbT2. Side-by-side analysis of wbT2 and wbDWI significantly improves the overall detection rate and fused image data provides no added value.

PET/CT (and CT) instrumentation, image reconstruction and data transfer for radiotherapy planning

The positron emission tomography in combination with CT in hybrid, cross-modality imaging systems (PET/CT) gains more and more importance as a part of the treatment-planning procedure in radiotherapy. Positron emission tomography (PET), as a integral part of nuclear medicine imaging and non-invasive imaging technique, offers the visualization and quantification of pre-selected tracer metabolism. In combination with the structural information from CT, this molecular imaging technique has great potential to support and improve the outcome of the treatment-planning procedure prior to radiotherapy. By the choice of the PET-Tracer, a variety of different metabolic processes can be visualized. First and foremost, this is the glucose metabolism of a tissue as well as for instance hypoxia or cell proliferation. This paper comprises the system characteristics of hybrid PET/CT systems. Acquisition and processing protocols are described in general and modifications to cope with the special needs in radiooncology. This starts with the different position of the patient on a special table top, continues with the use of the same fixation material as used for positioning of the patient in radiooncology while simulation and irradiation and leads to special processing protocols that include the delineation of the volumes that are subject to treatment planning and irradiation (PTV, GTV, CTV, etc.). General CT acquisition and processing parameters as well as the use of contrast enhancement of the CT are described. The possible risks and pitfalls the investigator could face during the hybrid-imaging procedure are explained and listed. The interdisciplinary use of different imaging modalities implies a increase of the volume of data created. These data need to be stored and communicated fast, safe and correct. Therefore, the DICOM-Standard provides objects and classes for this purpose (DICOM RT). Furthermore, the standard DICOM objects and classes for nuclear medicine (NM, PT) and computed tomography (CT) are used to communicate the actual image data created by the modalities. Care must be taken for data security, especially when transferring data across the (network-) borders of different hospitals. Overall, the most important precondition for successful integration of functional imaging in RT treatment planning is the goal orientated as well as close and thorough communication between nuclear medicine and radiotherapy departments on all levels of interaction (personnel, imaging protocols, GTV delineation, and selection of the data transfer method).

Molecular imaging agents: impact on diagnosis and therapeutics in oncology

Imaging has become a crucial tool in oncology throughout the course of disease detection and management, and is an integral part of clinical trials. Anatomical and functional imaging led the way, providing valuable information used in the diagnosis of disease, including data regarding the size and location of the tumour and on physiological processes such as blood flow and perfusion. As understanding of cancer pathogenesis has advanced through the identification of genetic, biochemical and cellular alterations in evolving tumours, emphasis has been put on developing methods to detect and serially monitor such alterations. This class of approaches is referred to as molecular imaging. Molecular imaging offers the potential for increasingly sensitive and specific visualisation and quantification of biological processes at the cellular and molecular level. These approaches have become established as essential tools for cancer research, early cancer detection and staging, and monitoring and predicting response to targeted therapies. Here, we discuss recent advances in the development of molecular imaging agents and their implementation in basic cancer research as well as in more rationalised approaches to cancer care.

PET/CT in primary musculoskeletal tumours: a step forward

Hybrid imaging with combined positron emission tomography/computed tomography (PET/CT) plays an important role in the staging and management of a wide variety of solid tumours. However, its use in the evaluation of musculoskeletal malignancy has not yet entered routine clinical practice. Cross-sectional imaging with magnetic resonance imaging (MR) and computed tomography have well-established roles but there is increasing evidence for the selective use of PET/CT in the management of these patients. The aims of this article are to review the current evidence and clinical applications of PET/CT in primary musculoskeletal tumours and discuss potential future developments using novel PET tracers and integrated PET/MR.

Prevalence of positive FDG-PET findings in patients with high CEA levels

OBJECTIVE

The purpose of this study was to evaluate the prevalence of positive findings of positron emission tomography (PET) with 2-deoxy-2-[18F]fluoro-D-glucose (FDG) in patients with high serum CEA levels.

METHODS

A total of 303 patients who had undergone an FDG-PET scan in our institution with high serum CEA levels were analyzed. The prevalence of positive PET findings was evaluated with regard to a previous history of malignancy, absolute value of CEA levels, and the time course of CEA levels (an increasing or decreasing pattern, a change divided by time (DeltaCEA) and doubling time of CEA).

RESULTS

Of 303 patients, 232 were confirmed to have malignancy, and the patient-based sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of PET were 87, 86, 95, 66, and 86%, respectively. There was no statistically significant difference in positive rates according to the history of previous malignancy. The prevalence of PET-positive cases was higher with an increase in absolute CEA levels, and more than 90% of the patients were positive when CEA levels were more than 20 ng/ml. The DeltaCEA was significantly higher and the doubling time was significantly shorter in patients with positive results than those with negative results.

CONCLUSIONS

A high value of serum CEA levels was correlated with a higher prevalence of positive PET findings. FDG-PET scans would be justified in patients with high serum CEA levels, regardless of whether there was or was not a previous history of malignancy.

A systematic review on the role of FDG-PET/CT in tumour delineation and radiotherapy planning in patients with esophageal cancer

PURPOSE

FDG-PET/CT has proven to be useful in the staging process of esophageal tumours. This review analysed the role of FDG-PET/CT in tumour delineation and radiotherapy planning in comparison with CT alone among patients with esophageal cancer. Thereby we focused on the detection of the primary tumour and lymph nodes by FDG-PET/CT, changes in target volume (TV) delineation based on FDG-PET/CT and its validity, changes in inter- and intra-observer variability in TV delineation, consequences for radiotherapy treatment planning with regard to either target volumes or organs at risk and finally on the validation of FDG-PET/CT-based TVs in terms of treatment outcome.

METHODS

A literature search was performed in MEDLINE and Cochrane library databases for studies concerning the current value of FDG-PET/CT in tumour detection and delineation and radiotherapy-planning procedures among patients with esophageal cancer. Both prospective and retrospective studies were included.

RESULTS

Fifty publications met the eligibility criteria, of which 19 were review papers and one was a case report. The remaining 30 publications reported on the results of original studies. FDG-PET was able to identify most primary tumours, with a sensitivity and specificity for the detection of metastatic lymph nodes of 30-93% and 79-100%. The use of FDG-PET/CT resulted in changes of target volumes, and consequently in changes in treatment planning. However, evidence supporting the validity of the use of FDG-PET/CT in the tumour delineation process is very limited. Only three studies reported a significant positive correlation between FDG-PET-based tumour lengths and pathological findings. There were two studies that tested the influence of FDG-PET/CT to the inter- and intra-observer variability. One of them found a significant decrease in inter- and intra-observer variability, while the others did not. Furthermore, there are no studies demonstrating the use of PET/CT in terms of improved locoregional control or survival.

CONCLUSION

Since the literature is very limited standard implementation of FDG-PET/CT into the tumour delineation process for radiation treatment seems unjustified and needs further clinical validation first.

Clinical usefulness of 18F-FDG PET-CT for patients with gallbladder cancer and cholangiocarcinoma

BACKGROUND

Reports concerning the clinical usefulness of (18)F 2-fluoro-2-deoxy-D: -glucose integrated positron emission and computed tomography ((18)F-FDG PET-CT) for patients with gallbladder cancer and cholangiocarcinoma are relatively scarce. The purpose of this study was to assess the diagnostic value of PET-CT in relation to a conventional imaging modality, multidetector row CT (MDCT), for patients with gallbladder cancer and cholangiocarcinoma.

METHODS

Ninety-nine patients with suspected gallbladder cancer and cholangiocarcinoma who underwent both PET-CT and MDCT for initial staging were included in our study. The results of these two imaging modalities for evaluating primary tumors, regional lymph nodes and distant metastases were compared with the final diagnoses based on pathological or clinical findings.

RESULTS

A maximum standardized uptake value (SUV(max)) of 3.65 was found to be the best cutoff value for detecting a malignant tumor. The overall values for the sensitivities, specificities, positive predictive values (PPVs), negative predictive values (NPVs) and the accuracies of PET-CT and MDCT for the detection of a primary tumor were 90.2, 70.6, 93.7, 60.0, 86.9% and 84.2, 70.6, 93.2, 48.0, 81.8%, respectively. PET-CT demonstrated no significant advantage over MDCT for the diagnosis of a primary tumor. PET-CT showed a significantly higher PPV (94.1 vs. 77.5%, P = 0.04) than that found for MDCT in the diagnosis of regional lymph node metastasis. Additionally, PET-CT showed a significantly higher sensitivity (94.7 vs. 63.2%, P = 0.02) than that found for MDCT in the diagnosis of distant metastasis.

CONCLUSIONS

PET-CT is valuable for detecting regional lymph node involvement and unsuspected distant metastases that are not diagnosed by MDCT.

PET/CT colonography: a novel non-invasive technique for assessment of extent and activity of ulcerative colitis

PURPOSE

Extent of involvement and activity of ulcerative colitis (UC) is best evaluated by colonoscopy. Colonoscopy however carries risk during acute exacerbation. We investigated the utility of PET/CT colonography for assessment of extent and activity of UC.

METHODS

Within a 1-week window, 15 patients with mild to moderately active UC underwent colonoscopy and PET/CT colonography 60 min after injection of 10 mCi of (18)F-fluorodeoxyglucose (FDG). PET activity score based on the amount of FDG uptake and endoscopic mucosal activity in seven colonic segments of each patient was recorded. The mean maximum standardized uptake value (SUV(max)) of seven segments was compared with activity in liver. A PET activity grade of 0, 1, 2 or 3 was assigned to each region depending upon their SUV(max) ratio (colon segment to liver).

RESULTS

The extent of disease was left-sided colitis in five and pancolitis in ten. The mean Ulcerative Colitis Disease Activity Index (UCDAI) was 7.6. The number of segments involved as per colonoscopic evaluation and PET/CT colonography was 67 and 66, respectively. There was a good correlation for extent evaluation between the two modalities (kappa 55.3%, p = 0.02). One patient had grade 0 PET activity, nine had grade 2 and five had grade 3 PET activity. In six patients, there was one to one correlation between PET activity grades with that of endoscopic grade. One patient showed activity in the sacroiliac joint suggesting active sacroiliitis.

CONCLUSION

PET/CT colonography is a novel non-invasive technique for the assessment of extent and activity of the disease in patients with UC.

Potential role of 18fluorodeoxyglucose-positron emission tomography/computed tomography in differentiating benign neurofibroma from malignant peripheral nerve sheath tumor associated with neurofibromatosis 1

OBJECTIVE

Benign plexiform neurofibromas (PNfib), especially those occurring in patients with neurofibromatosis type 1, are at a significant risk of progressing to a malignant peripheral nerve sheath tumor (MPNST). Early diagnosis, followed by radical surgery and adjuvant radiation to maintain local tumor control, is of critical importance to prevent metastasis and subsequent mortality from MPNSTs. However, early diagnosis is hampered by the sensitivity of current imaging modalities such as computed tomography (CT) or magnetic resonance imaging to reliably detect this malignant transformation, which can occur heterogeneously in a PNfib to a MPNST. 18Fluorodeoxyglucose (18FDG)-positron emission tomography (PET) is linked to metabolism and proliferation of tissues and has been widely used in oncology including PNSTs. 18FDG-PET/CT has the added advantage of fusing metabolic and anatomic imaging data sets.

METHODS

In this prospective study, 9 neurofibromatosis type 1-associated PNfibs suspected to have undergone transformation to an MPNST were preoperatively evaluated by 18FDG-PET/CT and magnetic resonance imaging. A detailed histological evaluation correlated the average and regional standard uptake value (SUV) from the 18FDG-PET/CT to grade of malignancy of the suspected MPNST.

RESULTS

Imaging from 18FDG-PET/CT and associated SUV of the suspected MPNSTs demonstrated either a homogeneous or a heterogeneous pattern. Stratification of the maximal SUV to low (<4.0), intermediate (4.0-7.0), or high (>7.0) correlated to the proliferative index (Ki-67) and grade of MPNST. A maximal SUV of more than 7.0 was closely correlated to a focus of malignant transformation.

CONCLUSION

This study, on a limited number of cases, demonstrates the potential use of 18FDG-PET/CT to augment management of PNfibs, especially in the context of neurofibromatosis type 1, which is characterized by multiple tumors. The addition of CT anatomic imaging to 18FGD-PET can facilitate targeting biopsies to metabolic hot spots, to further augment diagnostic sensitivity. Much larger numbers of MPNSTs, which can only be accrued in a collaborative manner among institutions, are required to further assess the specificity and sensitivity of 18FDG-PET/CT in the diagnosis of MPNSTs.

FDG positron emission tomography/computed tomography studies of Wilms' tumor

PURPOSE

The purpose of this analysis was to evaluate the utility of FDG PET/CT scanning in patients with Wilms' tumors.

METHODS

A total of 58 scans were performed in 27 patients (14 male, 13 female; ages: 1.9-23 years, median: 7 years) with proven Wilms' tumor. Twenty-six patients (56 scans) were studied at the time of suspected relapse, progressive disease, persistent disease, or for monitoring of therapy.

RESULTS

In the 27 patients with Wilms' tumor, 34 scans showed areas of abnormal uptake consistent with metabolically active tumors. Of the patients, 8 (24 scans) had pulmonary metastases larger than 10 mm in diameter, 10 (12 scans) had hepatic metastases, 11 (11 scans) had regional nodal involvement, 3 (3 scans) had bone metastases, 1 (1 scan) had chest wall involvement, 2 (2 scans) had pancreatic metastasis, and 5 (5 scans) had abdominal and pelvic soft tissue involvement. Two of eight patients with lung metastases had variable uptakes. Lung lesions 10 mm or smaller were not consistently visualized on PET scans. One patient with a liver metastasis showed no uptake on PET scan after treatment (size decreased from 45 to 15 mm).

CONCLUSION

Most Wilms' tumors concentrate FDG. However, small pulmonary metastases may be better visualized with CT. FDG PET/CT appears useful for defining the extent of involvement and assessing the response to treatment.

Imaging as a surveillance tool in rectal cancer

Despite advances in diagnosis and treatment, half of patients with treated rectal cancer will die owing to recurrent disease. There is no evidence of benefit on survival from an intensive surveillance program, even if presymptomatic recurrent disease is detected. The aim of this article is to review the results described for the different imaging techniques in diagnosing rectal cancer recurrence in different sites and to discuss their relative clinical impact. The sensitivity of imaging techniques is related to the performance of the machines and the site being examined. Computed tomography is the most used technique owing to its availability, speed, panoramic images and ease of use, while MRI of the pelvis and the liver produces the highest resolution, sensitivity and specificity in these anatomical areas. Owing to its high cost, [(18)F] fluorodeoxyglucose-PET should be used as a third-level examination, a 'problem-solving' method when the site of recurrence is unknown or to rule out other possible sites of recurrence before a second surgery, and, finally, because it offers the possibility to investigate the whole body. The follow-up must be designed for individual patients, taking into account a number of factors. In the near future, whole-body imaging, probably by MRI, that is free from radiation will become the method of choice for screening for recurrent disease.

Feasibility of FDG PET/CT to monitor the response of axillary lymph node metastases to neoadjuvant chemotherapy in breast cancer patients

PURPOSE

The aim of this study was to assess the accuracy of (18)F-fluorodeoxyglucose (FDG) positron emission tomography (PET)/CT to visualize lymph node metastases before the start of neoadjuvant chemotherapy and to determine how often the visualization is sufficiently prominent to allow monitoring of the axillary response.

METHODS

Thirty-eight patients with invasive breast cancer of >3 cm and/or lymph node metastasis underwent FDG PET/CT before neoadjuvant chemotherapy. The results of the FDG PET/CT were compared with those from ultrasonography with fine-needle aspiration (FNA) cytology or sentinel node biopsy. Patients suitable for response monitoring of the axilla were defined as having either a maximum standardized uptake value (SUV(max)) >or= 2.5 or a tumour to background ratio >or=5 in the most intense lymph node.

RESULTS

The sensitivity and specificity of FDG PET/CT in detecting axillary involvement were 97 and 100%, respectively. No difference existed between the SUV(max) of the primary tumour and that from the related most intense lymph node metastasis. Moreover, the mean tumour to background ratio was 90% higher in the lymph nodes compared to the primary tumour (p = 0.006). Ninety-three per cent of the patients had sufficient uptake in the lymph nodes to qualify for subsequent response monitoring of the axilla. A considerable distinction in metabolic activity was observed between the different subtypes of breast cancer. The mean SUV(max) in lymph node metastases of oestrogen receptor (ER)-positive, triple-negative and human epidermal growth factor receptor 2 (HER2)-positive tumours was 6.6, 11.6 and 6.6, respectively.

CONCLUSION

The high accuracy in visualizing lymph node metastases and the sufficiently high SUV(max) and tumour to background ratio at baseline suggest that it is feasible to monitor the axillary response with FDG PET/CT, especially in triple-negative tumours.

An integrated MR/PET system: prospective applications

Radiology is strongly depending on medical imaging technology and consequently directing technological progress. A novel technology can only be established, however, if improved diagnostic accuracy influence on therapeutic management and/or overall reduced cost can be evidenced. It has been demonstrated recently that Magnetic Resonance Imaging (MRI) and Positron Emission Tomography (PET) can technologically be integrated into one single hybrid system. Some scientific arguments on the benefits are obvious, e.g., that simultaneous imaging of morphological and functional information will improve tissue characterization. However, crossfire of questions still remains: What unmet radiological needs are addressed by the novel system? What level of hardware integration is reasonable, or would software-based image co-registration be sufficient? Will MR/PET achieve higher diagnostic accuracy compared to separate imaging? What is the added value compared to other hybrid imaging modalities like PET/CT? And finally, is the system economically reasonable and has the potential to reduce overall costs for therapy planning and monitoring? This article tries to highlight some perspectives of applying an integrated MR/PET system for simultaneous morphologic and functional imaging.

The role of FDG PET/CT in patients with locoregional breast cancer recurrence: a comparison to conventional imaging techniques

PURPOSE

The aim of this study was to evaluate the impact of (18)F-fluorodeoxyglucose positron-emission tomography/computed tomography (FDG PET/CT) on clinical management in patients with locoregional breast cancer recurrence amenable for locoregional treatment and to compare the PET/CT results with the conventional imaging data.

PATIENTS AND METHODS

From January 2006 to August 2008, all patients with locoregional breast cancer recurrence underwent whole-body PET/CT. PET/CT findings were compared with results of the conventional imaging techniques and final pathology. The impact of PET/CT results on clinical management was evaluated based on clinical decisions obtained from patient files.

RESULTS

56 patients were included. In 32 patients (57%) PET/CT revealed additional tumour localisations. Distant metastases were detected in 11 patients on conventional imaging and in 23 patients on PET/CT images (p < 0.01). In 25 patients (45%), PET/CT detected additional lesions not visible on conventional imaging. PET/CT had an impact on clinical management in 27 patients (48%) by detecting more extensive locoregional disease or distant metastases. In 20 patients (36%) extensive surgery was prevented and treatment was changed to palliative treatment. The sensitivity, specificity, accuracy, positive and negative predictive values of FDG PET/CT were respectively 97%, 92%, 95%, 94% and 96%.

CONCLUSIONS

PET/CT, in addition to conventional imaging techniques, plays an important role in staging patients with locoregional breast cancer recurrence since its result changed the clinical management in almost half of the patients. PET/CT could potentially replace conventional staging imaging in patients with a locoregional breast cancer recurrence.

Performance of integrated FDG-PET/contrast-enhanced CT in the diagnosis of recurrent pancreatic cancer: comparison with integrated FDG-PET/non-contrast-enhanced CT and enhanced CT

PURPOSE

The purpose of this study is to evaluate the accuracy of 2-deoxy-2-[F-18]fluoro-D: -glucose-positron emission tomography (FDG-PET)/computed tomography (CT) with intravenous contrast for depiction of recurrent pancreatic cancer, compared with PET/non-enhanced CT and CT.

PROCEDURE

Forty-five patients previously treated for pancreatic cancer underwent PET/CT for suspected recurrence. Lesion status was determined on the basis of histopathology and radiological imaging follow-up.

RESULTS

Patient-based analysis showed that sensitivity, specificity, and accuracy of PET/contrast-enhanced CT were 91.7%, 95.2%, and 93.3%, respectively, whereas those of PET/non-enhanced CT were 83.3%, 90.5%, and 86.7%, respectively, and those of enhanced CT were 66.7%, 85.7%, and 75.6%, respectively. In 21 patients whom the final diagnosis was obtained from the histopathologic examination, those figures of PET/contrast-enhanced CT were 94.7%, 50.0%, and 90.4%, respectively. The sensitivity of PET/contrast-enhanced CT in detecting local recurrence, abdominal lymph node metastasis, and peritoneal dissemination were 83.3%, 87.5%, and 83.3%, respectively.

CONCLUSION

PET/contrast-enhanced CT is an accurate modality for assessing recurrence of pancreatic cancer.

Detecting recurrence of gastric cancer: the value of FDG PET/CT

PURPOSE

In order to assess the diagnostic performance of Positron emission tomography/Computed tomography (PET/CT) for detecting recurrence in gastric cancer patients with clinical or radiologic suspicion of recurrence after surgical resection.

MATERIALS AND METHODS

Over a 4-year period, 105 post-operative patients with gastric cancer, who underwent PET/CT due to clinical or radiologic suspicion of recurrence during follow-up, were collected after confirming their PET/CT findings. The number and site of positive FDG uptake were retrospectively analyzed, and were correlated with the final diagnosis, by calculating the diagnostic values and assessing the causes of misdiagnosis.

RESULTS

Of all 105 patients, 75 patients were confirmed to have true recurrence with 108 recurrence sites. The sensitivity, specificity, positive predictive value, negative predictive value and accuracy for diagnosing true recurrence on a per-person basis were 75%, 77%, 89%, 55%, and 75%, respectively. On a per-lesion basis, 75 (69%) of 108 true recurrences showed positive FDG uptake, while 75 (89%) of 84 positive FDG uptake was confirmed to have true recurrence.

CONCLUSION

PET/CT was relatively accurate in detecting recurrence in post-operative patients with gastric cancer. Moreover, PET/CT might be helpful in confirming the presence of recurrence particularly in patients who were highly suspicious of recurrence, because of its high positive predictability.

Screening of Contralateral Breast in Patients with Breast Cancer: Role of MR Imaging and PET/CT Imaging

Breast cancer is one of the most common cancers in women. Contralateral breast carcinoma is the most common second malignancy in patients with breast carcinoma. Bilateral breast carcinomas exist in 2 forms: synchronous, in which both tumors occur at the same time, or metachronous, in which they occur at different times. When breast cancer is diagnosed, the contralateral breast should be carefully evaluated for a synchronous tumor. Screening for occult contralateral breast cancer is very important on initial cancer diagnosis. The detection and treatment of a synchronous tumor allows for informed surgical decision making, especially if tissue reconstruction is being considered. If chemotherapy is necessary, the patient would only need treatment once for bilateral synchronous cancers, not twice, as with metachronous cancers.

Incidental thyroid lesions detected by FDG-PET/CT: prevalence and risk of thyroid cancer

BACKGROUND

Incidentally found thyroid lesions are frequently detected in patients undergoing FDG-PET/CT. The aim of this study was to investigate the prevalence of incidentally found thyroid lesions in patients undergoing FDG-PET/CT and determine the risk for thyroid cancer.

METHODS

FDG-PET/CT was performed on 3,379 patients for evaluation of suspected or known cancer or cancer screening without any history of thyroid cancer between November 2003 and December 2005. Medical records related to the FDG-PET/CT findings including maximum SUV(SUVmax) and pattern of FDG uptake, US findings, FNA, histopathology received by operation were reviewed retrospectively.

RESULTS

Two hundred eighty five patients (8.4%) were identified to have FDG uptake on FDG-PET/CT. 99 patients with focal or diffuse FDG uptake underwent further evaluation. The cancer risk of incidentally found thyroid lesions on FDG-PET/CT was 23.2% (22/99) and the cancer risks associated with focal and diffuse FDG uptake were 30.9% and 6.4%. There was a significant difference in the SUVmax between the benign and malignant nodules (3.35 +/- 1.69 vs. 6.64 +/- 4.12; P < 0.001). There was a significant correlation between the SUVmax and the size of the cancer.

CONCLUSION

The results of this study suggest that incidentally found thyroid lesions by FDG-PET/CT, especially a focal FDG uptake and a high SUV, have a high risk of thyroid malignancy. Further diagnostic work-up is needed in these cases.

In Vivo Measurements of Tumor Metabolism and Growth after Administration of Enzastaurin Using Small Animal FDG Positron Emission Tomography

Background. The use of 2-[(18)F]fluoro-2-deoxy-D-glucose ([(18)F]FDG) may help to establish the antitumor activity of enzastaurin, a novel protein kinase C-beta II (PKC-betaII) inhibitor, in mouse xenografts. Methods. The hematologic cell line RAJI and the solid tumor cell line U87MG were each implanted in NOD/SCID mice. Standard tumor growth measurements and [(18)F]FDG PET imaging were performed weekly for up to three weeks after tumor implantation and growth. Results. Concomitant with caliper measurements, [(18)F]FDG PET imaging was performed to monitor glucose metabolism. Heterogeneity of glucose uptake in various areas of the tumors was observed after vehicle or enzastaurin treatment. This heterogeneity may limit the use of [(18)F]FDG PET imaging to measure enzastaurin-associated changes in xenograft tumors. Conclusion. [(18)F]FDG PET imaging technique does not correlate with standard caliper assessments in xenografts to assess the antitumor activity of enzastaurin. Future studies are needed to determine the use of [(18)F]FDG PET imaging in preclinical models.

Combined PET/MRI: a new dimension in whole-body oncology imaging?

INTRODUCTION

Hybrid imaging systems providing morphological and functional data in a single session have been available for oncological imaging for some time. So far, computed tomography (CT) has been the morphological method-of-choice for inclusion into these hybrid imaging systems. However, recently, research has focused on hardware-based fusion of function with magnetic resonance imaging (MRI) rather than CT.

OBJECTIVES

Now that the first head-only positron emission tomography (PET)/MRI systems have been installed and whole-body systems are to be expected in the near future, potential indications in clinical oncology have to be addressed.

DISCUSSION

This article discusses potential indications of PET/MRI in whole-body oncology imaging. Potential advantages and disadvantages compared with currently available hybrid imaging systems will be reviewed.