Evaluation of histopathological differentiation in lung adenocarcinoma patients using Tl-201-chloride and Tc-99(m)-MIBI SPET

The purpose of this prospective study was to evaluate the relationship betw een thallium-201 chloride (Tl-201) and technetium-99m hexakis 2-methoxyisob utylisonitrile (Tc-99(m)-MIBI) accumulation and histopathological different iation in primary lung adenocarcinoma. A total of 43 patients with primary lung adenocarcinoma were investigated. The patients were divided into well differentiated (n=17), moderately differentiated (n=14) and poorly differen tiated (n=12) carcinoma groups. Simultaneous dual single photon emission to mography (SPET) images with Tl-201 and Tc-99(m)-MIBI were acquired 15 min ( early) and 2 h (delayed) after injection. Using a region of interest techni que, the tumour-to-normal lung ratio was calculated for both early (early r atio) and delayed (delayed ratio) images. The retention index was calculate d using the formula delayed ratio/early ratio. Uptake of the radionuclides was compared with the classification of tumour differentiation grading. The mean (+/- SD) values of the early ratio, delayed ratio and retention index using Tl-201 were 2.19+/-0.72 2.28+/-0.71 and 1.06+/-0.16, respectively, i n the well differentiated group, 2.38+/-0.83, 2.48+/-0.84 and 1.08+/-0.23 r espectively, in the moderately differentiated group, and 2.87+/-0.75, 3.60/-1.51 and 1.22+/-0.21, respectively, in the poorly differentiated group. B oth the ratios and the retention index using Tl-201 were significantly lowe r in the well differentiated group than in the poorly differentiated group. The delayed ratio using Tl-201 in the moderately differentiated group was also significantly lower than that in the poorly differentiated group. Ther e were no significant differences in either ratio or the retention index am ong the three groups using 99Tcm-MIBI. Tl-201 SPET is superior to Tc-99(m)- MTBI SPET for the grading of histopathological differentiation of primary l ung adenocarcinoma. ((C) 2001 Lippincott Williams & Wilkins).