Johnson, Geoffrey B

Objective Our aim was to determine the radiologic and clinicopathologic characteristics of thyroid nodules with focal 68Ga-DOTATATE activity. Methods In this retrospective study of 1927 consecutive 68Ga-DOTATATE PET scans, 85 patients with incidental and nonincidental focal 68Ga-DOTATATE avid thyroid nodules were identified, of which 31 patients with 33 thyroid nodules underwent fine-needle aspiration (FNA) or surgery. These 33 nodules were reviewed for Krenning score and SUVmax of the thyroid nodule, contralateral thyroid lobe and left atrium. Results Cytology/histopathology included 58% (19/33) with benign findings, 18% (6/33) medullary thyroid carcinoma (MTC), 9% (3/33) atypia or follicular lesion of undetermined significance (AUS/FLUS), 9% (3/33) suspicious for follicular neoplasm and Hurthle cell adenoma (SFN/HCA) and 6% (2/33) nondiagnostic cytology. Median serum calcitonin was 1156 pg/mL (range, 460–1828) in MTC and was <5.0 pg/mL (<5.0–12.5) in patients with benign nodules. Nodules had Krenning score of 1, 2 and 3 in 46% (15/33), 27% (9/33) and 27% (9/33). The majority of MTC and AUS/FLUS nodules had a Krenning score of 3, and there was substantial intragroup variation in Krenning score among the benign nodules. The mean SUVmax for the entire cohort was 5.5 ± 2.9 (mean ± SD), and the range was 2.0–13.0. There was overlap in the nodule/contralateral thyroid SUVmax ratios between groups. The MTC and AUS/FLUS nodules tended to have a higher nodule/blood pool SUVmax ratio than the other pathologic groups. Conclusion There was considerable variation in radiologic characteristics among benign thyroid nodules. The ratio of thyroid nodule SUVmax/blood pool SUVmax may be useful to differentiate pathologic groups, but larger studies are needed to investigate this further. Given the potential for malignancy in thyroid nodules with focal 68Ga-DOTATATE activity, further evaluation with serum calcitonin and FNA may be considered. Video Abstract: http://links.lww.com/NMC/A186

Abstract A previously published model (Atkins) allows for calculation of 131I maximum tolerated activity on the basis of 48-hour whole-body retention of 131I on a pretherapy diagnostic scan. Our practice uses iodine 123I for diagnostic imaging of metastatic thyroid cancer for staging before 131I therapy, with images typically acquired 24 hours after administration of the radiopharmaceutical. We explored the feasibility of an additional 123I whole-body scan and retention measurement at 48 hours, with application of the model to estimate maximum tolerated activity of radioiodine before 131I treatment of metastatic thyroid cancer.

AbstractBackgroundMultiple mononeuropathy is a rare presentation of primary (AL) amyloidosis and nerve biopsy is usually needed for diagnosis. Conventional imaging is useful to identify proximal nerve involvement but may be inadequate. We report a patient with multiple mononeuropathy whose presentation was suggestive of AL amyloid neuropathy and in whom repeated tissue biopsies were negative for amyloid (including two sensory nerves and one muscle).MethodsThe patient underwent magnetic resonance imaging (MRI) and whole body 18F‐florbetapir positron emission tomography (PET)/MRI.ResultsWhole body 18F‐florbetapir PET/MRI revealed abnormal low‐level florbetapir uptake in the right proximal tibial and peroneal nerves, which provided a target for a sciatic bifurcation fascicular nerve biopsy that was diagnostic of AL amyloidosis.Conclusions 18F‐florbetapir PET/MRI imaging is a promising diagnostic tool for patients with suspected peripheral nerve amyloidosis (including multiple mononeuropathy) in whom conventional imaging and nerve and muscle biopsies miss the pathology.