Jan D. Soyka

Accuracy of 64-slice CT angiography for the detection of functionally relevant coronary stenoses as assessed with myocardial perfusion SPECT

PurposeCT angiography (CTA) offers a valuable alternative for the diagnosis of CAD but its value in the detection of functionally relevant coronary stenoses remains uncertain. We prospectively compared the accuracy of 64-slice CTA with that of myocardial perfusion imaging (MPI) using 99mTc-tetrofosmin-SPECT as the gold standard for the detection of functionally relevant coronary artery disease (CAD).MethodsMPI and 64-slice CT were performed in 100 consecutive patients. CTA lesions were analysed quantitatively and area stenoses ≥50% and ≥75% were compared with the MPI findings.ResultsIn 23 patients, MPI perfusion defects were found (12 reversible, 13 fixed). A total of 399 coronary arteries and 1,386 segments was analysed. Eighty-four segments (6.1%) in 23 coronary arteries (5.8%) of nine patients (9.0%) were excluded owing to insufficient image quality. In the remaining 1,302 segments, quantitative CTA revealed stenoses ≥50% in 57 of 376 coronary arteries (15.2%) and stenoses ≥75% in 32 (8.5%) coronary arteries. Using a cut-off at ≥75% area stenosis, CTA yielded the following sensitivity, specificity, negative (NPV) and positive predictive value (PPV), and accuracy for the detection of any (fixed and reversible) MPI defect: by patient, 75%, 90%, 93%, 68% and 87%, respectively; by artery, 76%, 95%, 99%, 50% and 94%, respectively.ConclusionSixty-four-slice CTA is a reliable tool to rule out functionally relevant CAD in a non-selected population with an intermediate pretest likelihood of disease. However, an abnormal CTA is a poor predictor of ischaemia.

Contrast-Enhanced 18F-FDG PET/CT: 1-Stop-Shop Imaging for Assessing the Resectability of Pancreatic Cancer

Patients with pancreatic cancer continue to have a poor prognosis, with a 5-y survival rate of less than 5%. Surgery is the only treatment that offers a potential cure. Determining resectability is the principal goal of staging in pancreatic cancer patients. Our objective was to evaluate the value of combined contrast-enhanced 18F-FDG PET/CT in assessing the resectability of pancreatic cancer and to compare enhanced PET/CT with the performance of PET alone and unenhanced PET/CT. Methods: Fifty patients (25 women and 25 men; mean age, 64.3 y; range, 39–84 y) with biopsy-proven pancreatic adenocarcinoma underwent enhanced 18F-FDG PET/CT for the evaluation of resectability. Criteria for unresectability were distant metastases, peritoneal carcinomatosis, arterial infiltration, or invasion of neighboring organs other than the duodenum. The performance of enhanced PET/CT regarding resectability was compared with that of PET alone and unenhanced PET/CT. Histology, intraoperative findings, and follow-up CT with clinical investigations were used as the reference standard. Results: According to the reference standard, 27 patients had disease that was not resectable because of distant metastases (n = 17), peritoneal carcinomatosis (n = 5), or local infiltration (n = 5). In the assessment of resectability, PET alone had a sensitivity of 100%, specificity of 44%, accuracy of 70%, positive predictive value of 61%, and negative predictive value of 100%; unenhanced PET/CT had respective values of 100%, 56%, 76%, 66%, and 100%; and enhanced PET/CT, 96%, 82%, 88%, 82%, and 96%. In 5 patients, unresectability was missed by all imaging methods and was diagnosed intraoperatively. Enhanced PET/CT was significantly superior to PET alone (P = 0.035), and there was a trend for enhanced PET/CT to be superior to unenhanced PET/CT (P = 0.070). Conclusion: The use of enhanced PET/CT as a 1-stop-shop imaging protocol for assessing the resectability of pancreatic cancer is feasible and accurate. Enhanced PET/CT is significantly superior to PET alone.

Characterization of Focal Bone Lesions in the Axial Skeleton: Performance of Planar Bone Scintigraphy Compared with SPECT and SPECT Fused with CT

OBJECTIVE The purpose of this study was to evaluate the diagnostic performance of planar 99mTc methylene diphosphonate bone scintigraphy compared with SPECT and SPECT fused with CT in patients with focal bone lesions of the axial skeleton. SUBJECTS AND METHODS Thirty-seven patients with 42 focal lesions of the axial skeleton were included in this prospective study. All patients underwent planar scintigraphy, SPECT through the focal lesions, and SPECT-guided CT. SPECT and CT images then were fused digitally. The three types of images were evaluated separately from one another by two experienced reviewers working to consensus. Visibility of the lesions, diagnostic performance, and certainty in diagnosis were evaluated. Performance for specific diagnoses also was evaluated. Histologic, MRI, and clinical follow-up findings were used as the reference standard. RESULTS Visibility of the lesions was significantly better with SPECT than with planar scintigraphy (p < 0.0001). Sensitivity and specificity for differentiation of benign and malignant bone lesions were 82% and 94% for planar scintigraphy, 91% and 94% for SPECT, and 100% and 100% for SPECT fused with CT. Differences between the three methods of differentiating benign and malignant lesions did not reach statistical significance. Certainty in diagnosis was significantly higher for SPECT fused with CT than for planar scintigraphy (p = 0.004) and SPECT (p = 0.004). A specific diagnosis was made with planar scintigraphy in 64% of cases, with SPECT in 86%, and with SPECT fused with CT in all cases. CONCLUSION Planar scintigraphy may suffice for differentiating benign and malignant lesions of the axial skeleton, but SPECT fused with CT significantly increases certainty in diagnosis and is the best tool for making a specific diagnosis.

Staging Pathways in Recurrent Colorectal Carcinoma: Is Contrast-Enhanced 18F-FDG PET/CT the Diagnostic Tool of Choice?

18F-FDG PET/CT has gained wide acceptance for evaluation of recurrent colorectal carcinoma. However in clinical practice, contrast-enhanced CT (ceCT) is still the first-line restaging tool. The aim of this study was to investigate the value of contrast-enhanced PET/CT (cePET/CT) as a first-line restaging tool with a special focus on the importance of the use of intravenous contrast. Methods: Fifty-four patients (17 women, 37 men; mean age, 60.3 y), referred for restaging of colorectal carcinoma, were examined with cePET/CT. Retrospective analysis was performed by 2 experienced readers by consensus: first, ceCT alone; second, non-cePET/CT; and third, cePET/CT. The number, localization, and diagnostic certainty of lesions were evaluated. Additionally, the therapeutic impact of the findings was determined. In 29 patients, histology, clinical imaging, and clinical follow-up served as the reference standard. In 25 patients, clinical follow-up and imaging served as the reference standard. Results: Overall, non-cePET/CT delivered correct additional information to the ceCT findings in 27 of 54 patients (50%). This occurred in (a) 20 of 30 patients, where ceCT was found to be inconclusive, and in (b) 7 of 24 patients with conclusive ceCT findings, where non-cePET/CT found additional lesions, leading to a therapy modification in 5 patients. Compared with non-cePET/CT, cePET/CT revealed additional information in 39 of 54 patients (72%), with therapeutic relevance in 23 patients. This large number was primarily due to correct segmental localization of liver metastases, which is crucial for surgical therapy planning. Conclusion: On the basis of its higher accuracy and therapeutic impact compared with ceCT, our data suggest that cePET/CT might be considered as the first-line diagnostic tool for restaging in patients with colorectal cancer.

Combined FDG-PET/CT in response evaluation of malignant pleural mesothelioma

PURPOSE Based on the complex growth pattern of MPM, conventional response evaluation in this cancer entity is challenging. Therefore, there is growing interest in therapy response evaluation with FDG-PET/CT. The aim of the study was to evaluate the value of several FDG-PET/CT-parameters in therapy response evaluation concerning prediction of survival at baseline and after three cycles of therapy. PATIENTS AND METHODS The study was performed in accordance with the regulations of the local ethics committee. Forty-one patients with proven MPM and treated with palliative pemetrexed and platinum-based chemotherapy were included. All patients were evaluated by FDG-PET/CT at baseline and after three cycles of chemotherapy. Responders and non-responders were evaluated based on modified RECIST- and EORTC-criteria. Additional PET-parameters (SUVmean, tumor lesion glycolysis (TLG) and tumor volume (PETvol)) were evaluated. Results were evaluated using the COX regression and the Kaplan-Meier method. RESULTS None of the baseline CT-measurements or the initial PET-parameters were predictive for survival. Based on CT, after three cycles of therapy 10 patients were categorized as responders, 30 were classified as stable disease and 1 had progressive disease. Based on PET-evaluation, 14 responders were identified, 23 patients with stable disease and 4 patients were progressive. CT-response after 3 cycles of chemotherapy was significantly related to overall survival (p=0.001). However, neither SUVmax-response (p=0.61) nor SUVmean-response (p=0.68) were related to survival. A decrease of TLG and PETvol, however, was found to be predictive (TLG: p=0.01; PETvol: p=0.002). CONCLUSION Response evaluation based on modified RECIST by CT as well as response evaluation by TLG and PETvol in FDG-PET, but not SUVmax-measurements are predictive for survival in MPM.

Hodgkin’s lymphoma in remission after first-line therapy: which patients need FDG–PET/CT for follow-up?

BACKGROUND The purpose of the study was to evaluate the impact of 2-[fluorine-18]fluoro-2-deoxy-D-glucose-positron emission tomography (FDG-PET)/computed tomography (CT) during follow-up of patients with Hodgkins lymphoma. PATIENTS AND METHODS Patients in complete remission or an unconfirmed complete remission after first-line therapy who received FDG-PET/CT during their follow-up were analyzed retrospectively. Confirmatory biopsy was mandatory in case of recurrence. RESULTS Overall, 134 patients were analyzed. Forty-two (31.3%) patients had a recurrence. The positive predictive value of FDG-PET/CT was 0.98. Single-factor analysis identified morphological residual mass [P = 0.0005, hazard ratio (HR) 3.4, 95% confidence interval (CI) 1.7-6.6] and symptoms (P < 0.0001, HR 4.9, 95% CI 2.4-9.9) as significant risk factors for relapse. By multivariate analysis, morphological residual mass was the only significant risk factor for early follow-up (<24 months) (P = 0.0019, HR 7.6, 95% CI 2.1-27.3). Advanced stage (P = 0.0426, HR 3.6, 95% CI 1.1-12.3) and the presence of symptoms (P = 0.0009, HR = 14.6, 95% CI 3.0-69.7) were found to be significant risk factors for later follow-up (>24 months). CONCLUSIONS Asymptomatic patients without morphological residues and an early stage of disease do not need a routine FDG-PET/CT for follow-up. Asymptomatic patients with morphological residues should receive routine follow-up FDG-PET/CT for the first 24 months. Only patients with advanced initial stage do need a routine follow-up FDG-PET/CT beyond 24 months.

Risk-adapted FDG–PET/CT-based follow-up in patients with diffuse large B-cell lymphoma after first-line therapy

BACKGROUND The purpose of this study was to evaluate the impact of 2-[fluorine-18]fluoro-2-deoxy-D-glucose-positron emission tomography/computed tomography (FDG-PET/CT) during follow-up of patients with diffuse large B-cell lymphoma (DLBCL) being in complete remission or unconfirmed complete remission after first-line therapy. PATIENTS AND METHODS DLBCL patients receiving FDG-PET/CT during follow-up were analyzed retrospectively. Confirmatory biopsy was mandatory in cases of suspected disease recurrence. RESULTS Seventy-five patients were analyzed and 23 (30%) had disease recurrence. The positive predictive value (PPV) of FDG-PET/CT was 0.85. Patients >60 years [P = 0.036, hazard ratio (HR) = 3.82, 95% confidence interval (CI) 1.02-7.77] and patients with symptoms indicative of a relapse (P = 0.015; HR = 4.1; 95% CI 1.20-14.03) had a significantly higher risk for relapse. A risk score on the basis of signs of relapse, age >60 years, or a combination of these factors identified patients at high risk for recurrence (P = 0.041). CONCLUSIONS FDG-PET/CT detects recurrent DLBCL after first-line therapy with high PPV. However, it should not be used routinely and if only in selected high-risk patients to reduce radiation burden and costs. On the basis of our retrospective data, FDG-PET/CT during follow-up is indicated for patients <60 years with clinical signs of relapse and in patients >60 years with and without clinical signs of relapse.

Continued pemetrexed and platin-based chemotherapy in patients with malignant pleural mesothelioma (MPM): Value of 18F-FDG-PET/CT

PURPOSE To prospectively analyze different FDG-PET/CT-parameters (modified RECIST, SUVmax, TLG, PETvol) in patients with malignant pleural mesothelioma (MPM) under continued pemetrexed and platin based treatment. METHODS Patients with biopsy proven MPM undergoing treatment with pemetrexed and platin based treatment were prospectively included in the study. Integrated FDG-PET/CT imaging was performed within 2 weeks before therapy and after every three consecutive cycles of combined chemotherapy. All CT-images were evaluated according to the modified RECIST (modRECIST) criteria. All FDG-PET/CT images were analyzed using SUVmax (maximum Standard Uptake Value) according to the EORTC criteria, change in Total Lesion Glycolysis (TLG) and FDG volume (PETvol). Percent change in all parameters compared to the initial, pre-therapeutic and the previous FDG-PET/CT scan. ModRECIST, EORTC guidelines, increase or decrease in TLG and PETvol was correlated with overall survival (OS) using the Log Rank Test. RESULTS 41 patients with MPM were prospectively included in this study. The median OS of the study population is 439 days (111-1128). 41 patients had initial staging, 41 patients completed 3 cycles, 28 patients completed 6 cycles, 19 patients completed 9 cycles, 11 patients completed 12 cycles, 5 patients completed 15 cycles, 4 patients completed 18 cycles and 1 patient completed 21 cycles of chemotherapy. Chemotherapy was well tolerated up to 21 cycles. SUVmax showed a high variance over time for individual patients and change in SUVmax using EORTC guidelines did not predict OS at any time point. Ongoing morphological response in CT using modRECIST had highest correlation with OS and predicted survival up to the 15th cycle of continued permetrexed and platin based treatment. The correlations of response of the volume based PET parameters (TLG and PETvol) and OS are inferior to the morphological modRECIST parameter. CONCLUSION Permetrexed and platin based treatment in MPM patients can be given over a prolonged time with good tolerance. Therapy response should be assessed by modRECIST in CT but not with SUVmax in FDG-PET. Long term permetrexed and platin therapy should be considered in MPM patients with good tolerance of treatment and ongoing morphological response in CT.

Influence of Bowel Preparation Before 18F-FDG PET/CT on Physiologic 18F-FDG Activity in the Intestine

Our objective was to investigate the use of bowel preparation before 18F-FDG PET/CT to reduce intestinal 18F-FDG uptake. Methods: Sixty-five patients with abdominal neoplasias were assigned either to a bowel-preparation group (n = 26) or to a native group (n = 39). 18F-FDG activity was measured in the small intestine and the colon. Results: In the 26 patients with bowel preparation, average maximal standardized uptake value (SUVmax) was 3.5 in the small intestine and 4.4 in the colon. In the 39 patients without bowel preparation, average SUVmax was 2.6 in the small intestine and 2.7 in the colon. 18F-FDG activity impaired diagnosis in 6 patients (23%) in the bowel-preparation group and 11 patients (28%) in the native group (P = 0.5). SUVmax in the colon was significantly higher in the bowel-preparation group (P = 0.002), but SUVmax in the small intestine did not significantly differ between the 2 groups (P = 0.088). Conclusion: Bowel preparation increases 18F-FDG activity in the large intestine and is therefore not useful before PET/CT.

FDG-positive Warthin's tumors in cervical lymph nodes mimicking metastases in tongue cancer staging with PET/CT

18F-fluorodeoxyglucose-positron emission tomography (FDG-PET/CT) is increasingly used for staging of patients with head and neck squamous cell cancers (HNSCC) with significant impact on therapy decisions. Additional applications are detection of carcinomas of unknown primary (CUP), detection of secondary cancers, and response assessment after therapy. FDG uptake is not specific for malignant tumors. Many nonmalignant tissues and inflammatory or infectious lesions can take up FDG and cause misinterpretations in cancer patients. We present the case of a 42-year-old male smoker with biopsy-proven SCC of the right anterolateral border of the oral tongue. Partial glossectomy was performed one week prior. Large lymph nodes were palpable in the right neck. The contrast-enhanced neck CT demonstrated two ipsilateral large, partially necrotic neck nodes at level II, suspicious for lymph node metastases, and the patient was referred for further staging to our institution. A partial-body PET/CT after injection of 350 Mbq FDG was performed (Fig 1). PET/CT demonstrated intense radiotracer uptake with a maximum standardized uptake value (SUV max. 5.2) at the resection site of the former primary tumor on the right-sided anterior border of the oral tongue representing postoperative changes. Additionally, intense FDG uptake (SUV max. 9.5 and 5.7) in the ipsilateral enlarged lymph nodes of level II was observed. Again, the diagnosis of SCC lymph node metastases was established by FDG-PET/CT. By imaging, the tumor was staged pT2cN2bcM0 according to the UICC staging system. Bilateral elective supraomohyoid neck dissection was carried out subsequently. In pathology three Warthin’s tumors (cystadenolymphomas) in three right-sided lymph nodes, 4.5 cm in greatest dimension, were found. All the other lymph nodes in the neck dissection were free of tumor. Finally, the tumor was classified as pT2pN0cM0. We have Institutional Review Board approval for this study.