Noninvasive evaluation of active lower gastrointestinal bleeding: comparison between contrast-enhanced MDCT and 99mTc-labeled RBC scintigraphy.

OBJECTIVE: The purpose of our study was to compare contrast-enhanced MDCT and (99m)Tc-labeled RBC scanning for the evaluation of active lower gastrointestinal bleeding. SUBJECTS AND METHODS: Over 17 months, 55 patients (32 men, 23 women; age range, 21-92 years) were evaluated prospectively with contrast-enhanced MDCT using 100 mL of iopromide 300 mg I/mL. Technetium-99m-labeled RBC scans were obtained on 41 of 55 patients and select patients underwent angiography for attempted embolization. Each imaging technique was reviewed in a blinded fashion for sensitivity for detection of active bleeding as well as the active lower gastrointestinal bleeding location. RESULTS: Findings were positive on both examinations in eight patients and negative on both examinations in 20 patients. Findings were positive on contrast-enhanced MDCT and negative on (99m)Tc-labeled RBC in two patients; findings were negative on contrast-enhanced MDCT and positive on (99m)Tc-labeled RBC in 11 patients. Statistics showed significant disagreement, with simple agreement = 68.3%, kappa = 0.341, and p = 0.014. Sixteen of 60 (26.7%) contrast-enhanced MDCT scans were positive prospectively, with all accurately localizing the site of bleeding and identification of the underlying lesion in eight of 16 (50%). Nineteen of 41 (46.3%) (99m)Tc-labeled RBC scans were positive. Eighteen of 41 matched patients went on to angiography. In four of these 18 (22.2%) patients, the site of bleeding was confirmed by angiography, but in 14 of 18 (77.8%), the findings were negative. CONCLUSION: Contrast-enhanced MDCT and (99m)Tc-labeled RBC scanning show significant disagreement for evaluation of active lower gastrointestinal bleeding. Contrast-enhanced MDCT appears effective for detection and localization in cases of active lower gastrointestinal bleeding in which hemorrhage is active at the time of CT.

B cell lymphoma: a case with localized involvement of the prostate on F-18-FDG examination.

An 80-year-old man had symptoms of urinary retention. Biopsy of the prostate revealed B cell lymphoma. To evaluate the extent of the disease, an F-18 FDG study was performed with positron emission tomography/computed tomography (CT). One hour after intravenous administration of 18.5 mCi F-18 FDG, imaging was carried out from the skull base to the upper thigh. An area of moderately increased activity was noted within the prostate bed. A noncontrast CT, for attenuation correction and anatomic localization, revealed maintenance of fat planes around the prostate, indicating disease localized to that organ. Hence, a B cell lymphoma had been localized to the prostate.

Asymmetric tongue muscle uptake of F-18 FDG: possible marker for cranial nerve XII paralysis.

A 58-year-old woman, with nonsmall cell carcinoma, had multiple metastasis on 2-F-18 FDG positron emission tomography imaging. The right hemitongue had increased activity as compared with the left. This was not the result of the presence of a metastasis to the tongue, as shown by a negative computed tomography scan of the region and failure to demonstrate a lesion over a period of weeks. Uptake was likely related to right hemiglossal muscle activity. This was made more apparent by decreased uptake on the opposite side of the tongue (up to the midline) as a result of left cranial nerve XII paralysis.