Liver tumor imaging by thallium-201 chloride with high resolution three-headed SPECT

Thallium-201 chloride (Tl) is useful in tumor imaging. The purpose of this study was to evaluate its usefulness in liver tumor imaging with Tl, 99mTc (Tc)-phytate (colloid), and three-headed SPECT. To evaluate the method, we imaged three spherical phantoms with inner/outer diameters of 8/10, 16/20, and 26/30 mm, respectively, in an aqueous solution background of 37 MBq/1 Tl and 74 MBq/1 Tc. All lesions in the phantoms were highlighted by the subtraction. Clinical materials consisted of 44 patients with 102 lesions; 31/73 with hepatocellular carcinoma (HCC), 8/21 with metastatic tumors (Meta), 2/2 with cholangiocarcinoma (CC), and 3/6 with hemangioma (HG). Tl accumulation in HCC was the highest, followed by Meta, CC and HG in that order. Ring type accumulation was observed in 17/21 Meta lesions. Meta tumor/non-tumor ratios were as follows: HHC (non-therapy) 1.45±0.33 (mean±SD), HCC (post-therapy; transcatheter arterial embolization and percutaneous ethanol injection therapy) 0.47±0.22, HCC (recurrence) 1.35±0.52, Meta 1.07±0.25, CC 0.45±0.64, HG 0.48±0.13. Tl, therefore, is useful for liver tumor imaging, and Tc-phytate is essential in discriminating Tl tumor uptake from normal liver accumulation. Image subtraction (Tl-Tc) is helpful in depicting diffuse and small HCC. (author)