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We evaluated the incidence and potential etiology of tracheobronchial uptake in patients being evaluated by 18 F-DCFPyL PET/CT for prostate cancer (PCa). Methods: The study included a consecutive 100 PCa patients referred for 18 F-DCFPyL PET/CT. The PET/CT scans were retrospectively reviewed. The presence or absence of physiologic tracheobronchial uptake on PET/CT was recorded. To further evaluate tracheal prostate-specific membrane antigen (PSMA) expression, immunohistochemistry was performed on tracheal samples taken from 2 men who had surgical resection of lung cancer. Results: Tracheal uptake was present in 31 of 100 patients (31%). When tracheal uptake was present, the SUV max was significantly higher in the left main bronchus (mean, 2.7) than in the right (mean, 2.3) ( P < 0.001). Histopathologic testing of tracheobronchial samples showed PSMA expression in bronchial submucosal glands. Conclusion: In PCa patients undergoing 18 F-DCFPyL PET/CT, tracheobronchial uptake occurred in 31% of patients. This is attributed to normal physiologic PSMA expression in bronchial submucosal glands., (© 2024 by the Society of Nuclear Medicine and Molecular Imaging.)

We evaluated the incidence of synchronous primary malignancies in patients undergoing 68 Ga-labeled prostate-specific membrane antigen PET/CT for prostate cancer (PC). Methods: Reports for 764 PC patients were reviewed. Incidental lesions atypical for PC metastases and suggestive of a synchronous primary malignancy were identified. Follow-up was obtained to confirm etiology. Results: Lesions atypical for PC metastases were found in 49 (6.4%) of 764 patients, and a synchronous primary malignancy was confirmed in 5 patients (0.7%; 2 lung, 1 lymphoma, 1 thyroid, and 1 base of tongue). In 8 patients (1.0%), lesions were proven to be atypical metastases from PC. In 24 patients (3.1%), lesions had a benign etiology. Follow-up was not available in 12 patients (1.6%). Conclusion: Synchronous 68 Ga-labeled prostate-specific membrane antigen-avid malignancies were rare (0.7%) in PC patients; atypical lesions were more commonly unusual PC metastases (1.0%) or benign (3.1%)., (© 2017 by the Society of Nuclear Medicine and Molecular Imaging.)

Unlabelled: Our objective was to evaluate the incidence of aneurysm and the frequency of thrombus within an aneurysm on unenhanced (18)F-FDG PET/CT studies., Methods: We reviewed 1,540 PET/CT scans from 926 patients. A log recorded whether each case of aneurysm had a suspected thrombus. The maximal standardized uptake value of the patent vessel was compared with the thrombus. Findings were confirmed using all available follow-up data., Results: Aneurysm was found incidentally in 16 (1.7%) of the 926 patients, with 15 occurring in the abdominal aorta and 1 in the internal jugular vein. Seven of these 16 patients had shown suggestions of thrombus on unenhanced PET/CT, and in all 7, thrombi were confirmed on contrast-enhanced CT., Conclusion: In 1.7% of patients, aneurysm was found incidentally on PET/CT, and thrombus was present in 44% of these cases.

Unlabelled: PET/CT technology is in rapid evolution. It remains unclear if the unenhanced CT portion, performed for attenuation correction and lesion localization, provides additional independent diagnostic information not apparent on PET alone. The objective of the current study was to evaluate the incremental added value and frequency of potentially clinically significant incidental findings from the independent reading of the unenhanced CT portion of PET/CT studies by an expert CT radiologist., Methods: PET/CT was performed on 250 patients (123 men and 127 women; mean age, 56.5 y) referred for clinical evaluation of known or suspected cancer. Unenhanced CT studies were read without knowledge of findings from PET and PET/CT fused images. Findings from unenhanced CT were considered clinically significant if they were not detected or explained by PET findings and were considered, after examination of all available clinical data, to clearly require additional work-up. Small pulmonary nodules < 7 mm were not considered to require immediate work-up., Results: Unenhanced CT revealed potentially clinically significant incidental findings in 7 patients. Three patients had indeterminate renal lesions, 1 patient had a solid renal mass, 1 patient had sclerotic bone metastases (albeit inactive on PET), 1 patient had liver cirrhosis with portal hypertension, and 1 patient had a 5 cm abdominal aortic aneurysm. These findings were generally not detected on PET., Conclusion: Clinically significant findings from the unenhanced CT portion of PET/CT are relatively infrequent (3%) but could be serious enough to warrant major alterations in clinical management. Thus, we believe it is most appropriate for the CT portion to be interpreted by a physician skilled in CT interpretation with special attention to the lesions that PET alone can fail to detect.

Unlabelled: Our objective was to demonstrate common patterns of ictal cerebral blood flow changes in a group of patients with mesial temporal lobe epilepsy (MTLE) using the technique of composite subtraction ictal SPECT coregistered to MRI (SISCOM)., Methods: We retrospectively reviewed the video electroencephalography recordings, SPECT studies, and MR images of 32 MTLE patients and of a subgroup of 11 patients with pathologically verified mesial temporal sclerosis (MTS). Composite SISCOM studies were performed as previously described. The patients were grouped for analysis into those with right seizure onset and those with left seizure onset. The images of the right and left MTS subgroups were combined for analysis by rotating right MTS images to show changes on the left side. The SPECT subtractions were segmented to show regions of hyperperfusion at 1 SD above the mean. A rainbow color map was applied to the final composite SISCOM images to assist in the interpretation of results. Binomial probability was calculated to demonstrate the level of significance of perfusion changes., Results: All patients demonstrated typical seizure semiology of MTLE. Seventeen patients had left MTLE and 15 patients had right MTLE. The levels of significance were set at 6 of 17 (P = 0.042) for the left MTLE group, 6 of 15 (P = 0.022) for the right MTLE group, and 5 of 11 (P = 0.021) for the MTS subgroup. Results among all groups were similar. The most-contiguous area of hyperperfusion was the anterior temporal area extending to include the insular cortex and basal ganglia, lateralizing to the side of seizure onset., Conclusion: Composite SISCOM studies in patients with well-localized MTLE most commonly show a region of hyperperfusion in the anterior temporal region, which often also involves the basal ganglia and insula, likely representing the primary regions of seizure propagation. Identifying this pattern of hyperperfusion as typical for mesial temporal onset seizures should assist in clinical interpretation and localization of ictal SPECT studies.

Unlabelled: This study evaluated lesion mislocalization between PET and CT on PET/CT studies when CT instead of germanium is used for attenuation correction (AC)., Methods: PET/CT scans were obtained for 300 clinical patients. Both CT and germanium scans were used to correct PET emission data. Cases were noted of suspected inaccurate localization of lesions on any of the 5 sets of images (PET using germanium AC [GeAC] fused and not fused with CT, PET using CT AC fused and not fused with CT, and PET with no AC [NAC]). Independent CT or MRI was used to determine true lesion locations., Results: Six of 300 patients (2%) had lesion mislocalization when CT was used for AC or fusion. True liver dome lesions were mislocalized to the right lung base on PET/CT, likely because of a respiratory motion difference between PET and CT. No mislocalization was present on NAC PET or non-CT-fused GeAC PET images., Conclusion: Serious lesion mislocalization on PET/CT studies may occur, albeit very infrequently, when CT is used for either AC or fusion.