I-131 SPECT/CT is a useful tool to characterize atypical or CF on WBS by differentiating thyroid remnant or cancer from physiologic activity or nonthyroid pathology. In the past, uptake on a WBS that was not explicable as physiologic activity was identified as putative or possible thyroid cancer and generally was treated with I-131. Now, by identifying activity in some possible cancer sites as not thyroid cancer, SPECT/CT can reduce inappropriate treatment with I-131. SPECT/CT of WBS performed after ablative doses of 131-I is useful in determining the nature of CF and therefore likely providing prognostic information.

On the basis of previously unpublished observations, we hypothesized that prolonged use of proton pump inhibitors (PPIs) causes an increase in 99m Tc-sestamibi uptake in the stomach wall, manifested as curvilinear activity surrounding the photopenic fundus of the stomach cavity. We prospectively evaluated the frequency of stomach wall uptake in patients undergoing myocardial perfusion SPECT who were taking PPIs or H 2 antagonists. Methods: Patients (n 5 138) who were scheduled for single-day rest/stress 99m Tc-sestamibi SPECT were randomly selected. Poststress SPECT was performed 30 min after treadmill exercise or 45 min after dipyridamole infusion. The rest scan was obtained 45 min after tracer injection. All patients drank 473 mL of water 5-10 min after both the rest and the stress radiotracer injections. Patients were questioned regarding their use of PPIs and H 2 antagonists. The significant use of either was defined as more than 2 wk of continuous therapy before cardiac SPECT. Masked observers assessed poststress planar projection images in endless-loop cinematic format for the following 3 patterns: stomach cavity uptake, attributable to duodenogastric reflux of tracer; stomach wall uptake; and no stomach uptake. A 2-tailed x 2 test with Yates correction was used to calculate statistically significant associations among variables. Results: Only patients with observed patterns of stomach wall uptake (n 5 30) and no stomach wall uptake (n 5 91) were included. Patients with stomach cavity uptake (n 5 17) were excluded because the assessment of the adjacent stomach wall uptake was not possible. Of the patients included (n 5 121), 30 were men and 91 were women. Sixty-seven patients were older than 60 y; 26 patients were taking PPIs. Of the 95 patients not taking PPIs, 14 were taking H 2 antagonists. No patients were taking both medications. Stomach wall uptake was strongly associated with prolonged use of PPIs (x 2 5 51.9, P , 0.0001). No statistically significant association was noted among age, sex, or use of H 2 antagonists (P 5 NS). Conclusion: Prolonged PPI therapy, but not H 2 antagonist therapy, contributes to a significant increase in stomach wall activity, potentially resulting in Compton scatter or ramp filter artifacts affecting the inferior wall of the left ventricle. Stomach wall activity, unlike the stomach cavity activity, cannot be prevented by the ingestion of water before imaging. Therefore, it is important to elicit a history of prolonged PPI use to better anticipate the possibility of increased stomach wall activity, which can confound the image quality and interpretation.

The risk of malignancy in a "hot" thyroid nodule detected by radioiodine scintigraphy is rare. We report a case of a 63-year-old man with a hyperfunctioning nodule demonstrated by radioiodine scintigraphy and cytology suspicious for follicular variant of papillary thyroid carcinoma (FVPTC). There were no locoregional or distant metastases at initial diagnosis. Histopathologic examination following thyroidectomy confirmed the presence of an encapsulated FVPTC. A year into follow-up, his I-131 whole body scan performed following the withdrawal from exogenous thyroid hormone was negative, whereas his serum thyroglobulin (Tg) levels were intermediate. A subsequent PET/CT scan revealed a small, but stable, metabolically active pretracheal lymph node, which on biopsy was confirmed to be stage III FVPTC. In conclusion, the presence of hyperfunctioning thyroid nodule(s) does not preclude malignancy and, therefore, proper cytohistologic evaluation in such patients may help to exclude a coexistent thyroid carcinoma. Patients treated for localized PTC may benefit from serial PET/CT follow-up in the early detection and management of recurrence or distant metastases.

A62-y-ol d woman was found to have a lung mass and a brain mass. The brain mass was resected, and the histopathologic findings were suggestive of a gastrointestinal primary tumor with neuroendocrine features. She was referred for an 111 In-octreotide SPECT/CT scan to evaluate for somatostatin-avid disease. After injection of 222 MBq (6 mCi) of 111 In-octreotide, planar SPECT images (Fig. 1A) and correlative CT images (Fig. 1B) of the chest were acquired in the anterior and posterior projections at the end of 4 h and 24 h. SPECT of the chest was also performed at the end of 24 h. An 18 F-FDG PET/CT scan (Fig. 1C) had been obtained 2 wk previously. QUESTION 1 On the basis of the 111 In-octreotide scan and correlative CT, what is the best interpretation of this study? A. 111 In-octreotide-avid tumor in the right lung and inflammatory changes bilaterally. B. Inflammatory changes. C. Normal findings. D. None of the above. FIGURE 1. (A) SPECT/CT scan obtained 24 h after injection of 222 MBq of 111 In-octreotide. (B) Correlative CT scan of chest. (C) 18 F-FDG PET/CT scan obtained 2 wk before 111 In-octreotide SPECT/CT scan.