Delayed imaging and additional methods to reduce subdiaphragmatic activity in myocardial perfusion SPECT imaging.

Compton scatter from radiotracer in structures close to the heart may partially or completely mask myocardial perfusion defects on SPECT imaging. Previous reports have discussed benefits of additional delayed imaging. We present a case in which additional delayed stress imaging reduced Compton scatter and unveiled clinically significant, stress-induced ischemia.

Varices: A potential pitfall in gastrointestinal bleeding scan interpretation.

Gastrointestinal bleeding scans are extremely useful for localizing the source of gastrointestinal bleeding before interventional radiology procedures. It is essential that physicians understand the numerous possible pitfalls when interpreting these scans. Understanding the potential causes of false-positive scan interpretation eliminates unnecessary procedures for the patient and minimizes costs. We report a case of a patient with cirrhosis who presented with gastrointestinal bleeding to emphasize intra-abdominal varices as a potential cause of false-positive bleeding scan interpretation. In addition, we reinforce the criteria needed for diagnosis of gastrointestinal bleeding on the nuclear bleeding scan.

Follicular variant of papillary thyroid carcinoma presenting as a toxic nodule by I-123 scintigraphy.

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.