Superiority of SPET to planar imaging in the detection of colorectal carcinomas with 111In monoclonal antibodies.

Abstract

The aim of this study was to assess the contribution of single photon emission tomography (SPET) to planar imaging of colorectal carcinoma in patients being evaluated with 111In-labelled monoclonal antibodies CYT-103 (OncoScint CR/OV) or IVP ZCE 025. Planar and SPET scans from 110 colorectal carcinoma patients were scored individually as follows: 1=negative, 2=equivocal, 3=positive. The planar and SPET images identified 67 and 93 of 113 documented lesions, respectively. The planar and SPET findings were concordant in 55 patients. SPET converted planar findings from 1 to 3 in 11 patients and from 2 to 3 in 21 patients. SPET provided a better definition of the extent of the tumour in 21 patients. Both imaging tests were true-negative in five patients, and failed to detect tumours in six patients. We strongly recommended SPET in all patients undergoing immunoscintigraphy, since it identified tumours missed on planar scans in 35% of patients and provided additional information regarding tumour burden in 23% of patients.