18F-Choline PET/CT, MRI, and Software-Based Image Fusion Analysis in Patients With Primary Hyperparathyroidism.

PURPOSE: The aim of this study was to evaluate the diagnostic performance of 18F-choline PET and MRI in patients with primary hyperparathyroidism. Furthermore, the additional value of software-based PET/MRI scan fusion was analyzed. PATIENTS AND METHODS: This retrospective study includes 42 patients (38 women) with an age between 32.5 and 79.1 years. PET/CT scans were performed on a dedicated system after injection of 250 to 350 MBq 18F-choline. For the MRI examination, T1-weighted images of the cervical region were used. The image fusion was made by anatomical coregistration using an automated algorithm based on mutual information. RESULTS: A total of 46 lesions were discovered and histologically confirmed in 42 patients. Histopathological examination revealed 38 adenomas and 8 hyperplasias. This means that, in 4 of these 42 patients, 2 lesions per patient were discovered. PET/CT also detected 46 abnormal findings, but only 43 were correctly recognized, whereas the other 3 were false-positive (FP). Six lesions could not be detected correctly: 3 were FP and 3 false-negative, which resulted in a sensitivity of 93.5% and a specificity of 97.5%. The site-specific evaluation showed 18 true-positive enlarged parathyroid glands with MRI, but also produced 13 FP findings and failed to detect 28 lesions; the sensitivity and specificity are thus 39.1% and 89.3%, respectively. The difference in detection rate between 18F-choline PET/CT and MRI was statistically significant (P < 0.001). CONCLUSIONS: 18F-choline PET/CT is clearly superior to MRI for localization diagnostics in primary hyperparathyroidism. Image fusion of both modalities can be helpful for more precise anatomical assignment.

SUV as a Possible Predictor of Disease Extent and Therapy Duration in Complex Tuberculosis.

OBJECTIVE: F-FDG PET/CT provides information on disease extension and activity in neoplastic and inflammatory conditions. So far, little is known about whether SUVmax of a reference lesion can allow a prognosis to be given regarding patient-specific outcome parameters in complex cases of tuberculosis (TB). METHODS: We retrospectively identified 37 patients (21 men, 16 women; mean age, 50.4 years) who underwent F-FDG PET/CT for the evaluation of active TB before treatment initiation. The aims were to examine whether the reference lesion SUVmax differed between patients with standard (≤9 months) and long-term (>9 months) therapy and to define an SUVmax cutoff distinguishing those groups. In addition, we analyzed the prognostic value of SUVmax with regard to estimation of initial disease extent and lesion distribution pattern. RESULTS: Median therapy duration was 10 months (interquartile range, 3.25 months), and median SUVmax was 8 (interquartile range, 8.54). SUVmax was significantly (P = 0.036) higher in patients treated longer than 9 months (10.1 vs 5.5). When applying a receiver operating characteristic curve analysis, an SUVmax cutoff value of 10 differentiated the standard and the long-term therapy group with a sensitivity of 50% and a specificity of 78.6% (P = 0.087). Higher SUVmax corresponded with a larger number of affected organ systems (P = 0.012 for ≤/>1). Patients with extrathoracic involvement showed significantly higher SUVmax than did patients with limited intrathoracic disease (P = 0.024) and received significantly longer antimycobacterial therapy (P = 0.011). CONCLUSIONS: Reference lesion SUVmax from pretherapy F-FDG PET/CT may have prognostic properties in complicated cases of TB, especially regarding therapy duration and disease extent.

18F-FDG PET/CT in the Initial Assessment and for Follow-up in Patients With Tuberculosis.

PURPOSE: The aim of this retrospective study was to assess the value of 18F-FDG PET/CT in the initial evaluation and follow-up of patients with tuberculosis (TB). PATIENTS AND METHODS: Thirty-five patients (18 men) with pulmonary or extrapulmonary TB were included. Diagnosis of TB was based either on histology or microbiological assessment in 32 patients and was based on typical morphological features of TB in CT and improvement on antimycobacterial medication in 3 patients. Eighty-eight 18F-FDG PET/CT scans were performed at initial assessment and during treatment, on a Siemens Biograph PET/CT. Diagnostic contrast-enhanced CT scans were performed on the 40-slice multidetector CT of the PET/CT scanner. Mean (SD) anti-TB treatment duration was 16.1 (8.9) months. RESULTS: The initial 18F-FDG PET identified 64 affected regions in 34 among 35 patients, whereas CT identified 34 affected organs in 23 patients. Matching image results between PET and CT were observed at first visit in 11 patients (31.4%), with relevant differences in 23 (65.7%). In 1 patient, both modalities remained negative. During follow-up 18F-FDG PET scans, we recorded 15 cases with remission of disease, 16 with residual disease (2 patients with multidrug-resistant infection), and 4 cases with progressive disease or delayed onset of adequate immunological response. In only 3 patients, both modalities, PET and CT, showed completely equivalent results. CONCLUSIONS: Both components of 18F-FDG PET/CT provide complementary information at initial evaluation and during follow-up; however, 18F-FDG showed more abnormal findings than CT. 18F-FDG PET/CT might be useful for the establishment of individualized treatment regimes, but this requires further prospective studies.

Malignant disease as an incidental finding at ¹8F-FDG-PET/CT scanning in patients with granulomatous lung disease.

PURPOSE: Fluorine-18 fluorodeoxyglucose (¹8F-FDG)-PET/computed tomography (CT) is used for assessment of the extent and activity of disease in patients with inflammatory granulomatous lung disease, in particular sarcoidosis and tuberculosis. The aim of this retrospective analysis was to assess the value of ¹8F-FDG-PET/CT in the identification of previously unknown malignant disease during routine investigation of granulomatous lung disease. MATERIALS AND METHODS: From July 2008 to December 2013, a total of 122 patients with tuberculosis (76 male and 46 female patients; age range 19.6-88.6 years, mean 52.8±16.6 years) and 85 patients with sarcoidosis (46 male and 39 female patients; age range 17.8-76.5 years, mean 48.6±13.8 years) underwent ¹8F-FDG-PET/CT. Reports were generated in consensus by both a nuclear medicine physician and a radiologist. Possibly malignant findings underwent biopsies and/or follow-up. Quantitative parameters (maximum standardized uptake value) were pooled and compared from reference lesions in each group. RESULTS: Malignant disease was suspected in 18 of 122 tuberculosis patients and in eight of 85 sarcoidosis patients. Malignancy was finally confirmed in six patients with tuberculosis and in two patients with sarcoidosis. In one single case a malignant lung tumour had been overlooked on PET/CT. Patients were also analysed according to their age. In the patient group older than 60 years, four malignancies were confirmed in 44 tuberculosis patients and in one in 20 sarcoidosis patients, whereas in patients aged between 30 and 60 years only three of 63 tuberculosis and one of 58 sarcoidosis cases showed malignancy compared with the 18 false-positive findings on a total patient basis. The most common site of malignant disease was the chest. Besides the intrathoracic findings, two cases of malignancy were detected outside the thorax. Quantitative evaluation did not reveal any statistically significant difference between the tuberculosis and sarcoidosis groups. CONCLUSION: Differentiation between granulomatous inflammation and malignancy is challenging with ¹8F-FDG-PET/CT because of a large number of false-positive findings. The highest probability of detecting coexistent malignant disease was seen in patients older than 60 years who were suffering from tuberculosis. An important feature for identification of malignant disease, especially in the assessment of intrathoracic findings, has turned out to be the CT pattern; quantitative evaluation, in contrast, seems to have little clinical value.