Evaluation of 99Tcm-HL91 hypoxic imaging in post-therapeutic patients with cancers

Objective: 99Tcm-4, 9-diaza-3, 3, 10, 10-tetramethyldodecan-2, 11-dione dioxime (HL91) is a new hypoxia imaging agent that demonstrates increased uptake and retention in tumor hypoxic tissues in vivo. The objective of this study was to evaluate the clinical value of 99Tcm-HL91 hypoxia imaging in post-therapeutic patients with cancers. Methods: Thirty-seven patients with primary cancers at head and neck and upper aerodigestive region who were suspected to have residual, recurrent, or metastatic disease at either clinical follow-up or by regular CT follow-up, were included. All underwent 99Tcm-HL91 imaging. The radioactivity ratios of tumor to normal tissues (T/NT) were calculated using the region of interest (ROI) technique. A t-test was used for data analysis. The 'gold standard' of diagnostic accuracy was based on histopathology or clinical follow-up. Results were compared between 99Tcm-HL91 and CT. Results: Of the 37 patients, 11 had either residual or recurrent lesions and 7 had distant disease. (1) A significantly higher 99Tcm-HL91 uptake were noted in residual or recurrent lesions than benign lesions (1.58 ± 0. 16 vs 1.18 ± 0.14, t =4. 87, P <0.001). (2) The sensitivity, specificity, and accuracy for residual or recur-rent lesions were 72. 73% (8/11), 63.64% (7/11), 4/4; 89.47% (17/19), 84. 21% (16/19), 94. 12% (16/17), and 83.33% (25/30), 76.67% (23/30), 95.24% (20/21) in 99Tcm-HL91, CT, and combined 99Tcm-HL91 and CT, respectively. (3) For distant sites detection (n = 7), CT detected all but 99Tcm-HL91 missed three. Conclusions: A combination of 99Tcm-HL91 and CT in detection either residu-al, recurrent, or metastatic disease would have the highest benefit in patients with cancers at head and neck and upper aerodigestive region. (authors)