Serial hypoxia imaging with 99mTc-HL91 SPECT to predict radiotherapy response in nonsmall cell lung cancer

Objective: To evaluate the relationship between Tc-99m-HL91 (Tc-99m labeled 4,9-diaza-3,3,10,10-tetramethyl dodecan-2,11-dione dioxime) SPECT (single photon emission computed tomography) hypoxia imaging and the treatment outcome and also to assess changes in tumor oxygenation during the course of radiotherapy. Methods: There were 32 patients enrolled in the study with pathologically proven nonsmall cell lung cancer that received 3-dimensional conformal radiotherapy. A Tc-99m-HL91 SPECT scan was performed in all patients 1 or 2 days before radiotherapy and repeated during and after radiotherapy completion in 18 patients. The radioactivity ratios of tumor to normal tissue (T/N) were calculated. Results: The relationship between T/N ratios at 4 hours images after injection that was shown as the best of 3 acquired images before radiotherapy and tumor response and over survival were analyzed for all 32 patients. The results of Tc-99m-HL91 imaging of 32 patients correlate well with tumor response (P = 0.002) and also patient survival (P = 0.043). The T/N ratios of 18 patients were decreased before, during and after radiotherapy and there was significant statistic difference (P = 0.000...). Conclusions: HL91 SPECT imaging identified the hypoxia status and changes during radiotherapy in lung cancer. It was confirmed that hypoxia imaging with HL91 SPECT before radiotherapy may predict tumor response and patient survival.