Added Value of Including Entire Brain on Body Imaging With FDG PET/MRI.

OBJECTIVE: FDG PET/MRI examination of the body is routinely performed from the skull base to the mid thigh. Many types of brain abnormalities potentially could be detected on PET/MRI if the head was included. The objective of this study was therefore to identify and characterize brain findings incidentally detected on PET/MRI of the body with the head included. MATERIALS AND METHODS: We retrospectively identified 269 patients with FDG PET/MRI whole-body scans that included the head. PET/MR images of the brain were reviewed by a nuclear medicine physician and neuroradiologist, first individually and then concurrently. Both PET and MRI findings were identified, including abnormal FDG uptake, standardized uptake value, lesion size, and MRI signal characteristics. For each patient, relevant medical history and prior imaging were reviewed. RESULTS: Of the 269 subjects, 173 were women and 96 were men (mean age, 57.4 years). Only the initial PET/MR image of each patient was reviewed. A total of 37 of the 269 patients (13.8%) had abnormal brain findings noted on the PET/MRI whole-body scan. Sixteen patients (5.9%) had vascular disease, nine patients (3.3%) had posttherapy changes, and two (0.7%) had benign cystic lesions in the brain. Twelve patients (4.5%) had serious nonvascular brain abnormalities, including cerebral metastasis in five patients and pituitary adenomas in two patients. Only nine subjects (3.3%) had a new neurologic or cognitive symptom suggestive of a brain abnormality. CONCLUSION: Routine body imaging with FDG PET/MRI of the area from the skull base to the mid thigh may miss important brain abnormalities when the head is not included. The additional brain abnormalities identified on whole-body imaging may provide added clinical value to the management of oncology patients.

18F-FDG PET-CT: predicting recurrence in patients following percutaneous cryoablation treatment for stage I primary non-small-cell lung cancer.

PURPOSE: The aim of this study was to understand the imaging features of fluorine-18 fluorodeoxyglucose ((18)F-FDG) PET-computed tomography (CT) in postcryoablation lung cancer patients that could help predict recurrence. METHODS: We identified 28 patients with 30 lesions treated by means of percutaneous cryoablation for stage I non-small-cell lung cancer. Two experienced nuclear radiologists blindly reviewed baseline images and follow-up (18)F-FDG PET-CT scans for a minimum of 24 months, with discrepancy in interpretation resolved by consensus. Nineteen lesions had undergone baseline PET-CT studies, whereas 11 lesions had undergone only baseline CT studies. Follow-up PET-CT studies were analyzed for up to 24 months, whereas the recurrence-free survival analysis was performed for 36 months. RESULTS: The average maximum standardized uptake value (SUV(max)) at baseline (n = 19) was 5.2 ± 3.9 and the average CT area at baseline was 2.2 ± 1.6 cm(2). Only the CT area was significantly different between recurring and nonrecurring lesions at baseline (P = 0.0028). The Kaplan-Meier survival analysis showed that dichotomizing lesions around 2 cm on CT did not result in a statistically significant survival difference (hazard ratio = 1.42, 95% confidence interval: 0.63-2.21). The average SUV(max) at first follow-up was 1.9 ± 1.8 for 27 lesions, whereas the average SUV(max) of recurrent lesions was 2.2 ± 2.2 and that of nonrecurrent lesions was 1.5 ± 0.3 (P = 0.17). Six lesions had SUV(max) more than or equal to 2.5 within 24 months, all of which recurred in the ablation zone. CONCLUSION: (18)F-FDG PET-CT is a valuable tool for determining treatment response and for distinguishing benign from malignant lesions after cryoablation. The CT area was most predictive of future recurrence at baseline, whereas SUV(max) more than or equal to 2.5 was most predictive of future recurrence at first follow-up.

Fluorodeoxyglucose PET-CT Findings Following Bone Marrow Harvesting.

Two patients demonstrated an unusual pattern of intense bone and surrounding soft tissue hypermetabolic uptake in the posterior pelvis on fluorodeoxyglucose positron emission tomography with computed tomography PET-CT scans. After further investigation, we found that both patients underwent uncomplicated autologous bone marrow harvesting several weeks before imaging. These two cases illustrate a distinctive PET-CT appearance following bone marrow harvesting that the radiologist needs to recognize to not confuse the findings with metastatic disease.

Head and neck cancers: post-therapy changes in muscles with FDG PET-CT.

BACKGROUND: FDG PET-CT plays a critical role in the management of head and neck cancer patients. After therapy, many patterns of altered physiologic FDG uptake have been recognized. In our institution, we noticed patterns of head and neck muscle uptake that were unique in the post-therapy scans of head and neck cancer patients. MATERIALS AND METHODS: A total of 32 patients with head and neck cancers who had both pretherapy and posttherapy FDG PET-CT scans were retrospectively analyzed. Regional anatomic muscle groups that had increased PET uptake on either pretherapy or post-therapy scans were identified. RESULTS: On the pretherapy scans, the majority of patients (24/32 patients) did not have increased PET activity in the predefined muscle groups. On the post-therapy scans, the majority of patients (25/32 patients) demonstrated increased uptake in at least 1 head and neck muscle group, with an average of 3 muscle groups per patient. The muscle groups with the greatest frequencies were the prevertebral (50%), the accessory neck (47%), the posterior paravertebral (47%), and the scalene muscles (38%). Relative to pretherapy scans, the mean intensity of the post-therapy elevations corresponded to greater SUVs. CONCLUSION: FDG PET-CT scan commonly depicts an elevated FDG muscle uptake in all regional anatomic muscle groups in the post-therapy head and neck cancer patient. This uptake should be considered as a consequence of treatment and perhaps changes in altered biomechanics, and not be confused with residual or recurrent neoplastic activity.