99mTc-aprotinin scintigraphy in amyloidosis.

Changes in the amount and distribution of amyloid lesions have been difficult to monitor because they can usually be demonstrated only by evident symptoms or from a biopsy. The recent progress in the treatment of amyloidosis stresses the need for an early diagnosis and the need for noninvasive monitoring during the course of treatment. To validate (99m)Tc-aprotinin scintigraphy, we studied 23 consecutive patients with known or suspected amyloidosis. METHODS: (99m)Tc-Aprotinin (500-700 MBq) was injected intravenously and whole-body scans, regional images, and SPECT tomograms were obtained 90 min after tracer injection. RESULTS: Focal accumulations of (99m)Tc-aprotinin were seen in different organs of 22 patients with a total of 90 lesions, of which 20 were confirmed by biopsy or autopsy. Scintigraphy revealed "silent" amyloid deposits in at least 5 patients who later developed clinical symptoms. Physiologic uptake or excretion in liver and kidneys could not be differentiated from pathologic lesions in those organs. CONCLUSION: (99m)Tc-Aprotinin scintigraphy appears to be a fairly sensitive and specific diagnostic modality in patients with suspected amyloidosis. The technique is noninvasive, and it entails a minimal stress to the patient and is useful for detection of a wide range of lesions.