Predicting early chemotherapy response with technetium-99m methoxyisobutylisonitrile SPECT/CT in advanced non-small cell lung cancer.

Purpose: The purpose of this study is to examine the prognostic value of prechemotherapy technetium-99m methoxyisobutylisonitrile ((99m)Tc-MIBI) uptake with single photon emission computed tomography/computed tomography (SPECT/CT) in relation to tumor size change measured by CT.

Methods: Eleven patients with stage IIIB/IV non-small cell lung cancer (NSCLC) underwent (99m)Tc-MIBI SPECT/CT within 24 h before starting platinum-containing chemotherapy. Following the Response Evaluation Criteria in Solid Tumors guidelines, 20 lesions from the 11 patients were available for evaluation. Maximum (C (max)) and mean (C (mean)) MIBI counts were calculated for each lesion. One-dimensional (1D; longest diameter) and two-dimensional (2D; area of the largest transverse surface) tumor measurements were assessed by two observers on the diagnostic CT and the response assessment CT after two cycles of chemotherapy.

Results: Bland-Altman analysis demonstrated no clinically significant bias between the observers. A solid correlation was found between (99m)Tc-MIBI C (mean) and change in the longest diameter (1D change) of the target lesion (rho = -0.62) using Spearman's rank correlation test. C (mean) also correlated negatively with change in the area of the largest transverse surface (2D change) of the target lesion (rho = -0.53). Furthermore, a correlation was established between (99m)Tc-MIBI C (max) and 1D change (rho = -0.56) in tumor size as well, though less strongly when compared to its C (mean) counterpart.

Conclusions: Our series demonstrated solid, negative correlations between prechemotherapy (99m)Tc-MIBI uptake and tumor size change measured by CT for advanced NSCLC, particularly with C (mean) and 1D change.