Whole-tumor perfusion CT parameters and glucose metabolism measurements in head and neck squamous cell carcinomas: a pilot study using combined positron-emission tomography/CT imaging.

BACKGROUND AND PURPOSE Previous (separately performed) perfusion CT (PCT) and PET studies have been inconclusive regarding the correlation of functional tumor characteristics. The purpose of this study was to perform dual assessment of head and neck squamous cell carcinomas (SCCAs) to examine the relationship between perfusion measurements derived from PCT and glucose standardized uptake values (SUV). MATERIALS AND METHODS We prospectively evaluated 15 primary and recurrent SCCAs using combined positron-emission tomography (PET) and CT of the head and neck. SUV(mean), SUV(max), blood flow (BF), blood volume (BV), mean transit time (MTT), and permeability (PS) values were calculated with use of manually drawn regions of interest (ROIs) over the lesions and the healthy muscle tissue. Parametric comparison test, correlation coefficients, and regression analysis were performed. RESULTS The mean (+/- SD) SUV(mean), SUV(max), BF, BV, MTT, and PS values in the tumor tissue were 6.26 (+/- 1.48), 15.25 (+/- 3.81), 91.50 (+/- 24.69), 5.08 (+/- 1.17), 7.51 (+/- 2.24), and 23.08 (+/- 8.77), respectively. All PET/CT and PCT parameters of muscle versus tumor tissue were statistically different (.0001 < P < .001). There were significant correlations between BF and SUV(max) as well as SUV(mean) (r = 0.57; P = .02 and r = 0.63; P = .011, respectively) in the tumors. Significant correlation was also found between PS and SUV(mean) (r = 0.53; P = .04) in the tumors. Regression analysis showed: SUV(max) = 0.09 x BF + 7.2 (R(2) = 0.33; P = .02), SUV(mean) = 0.05 x BF + 2.22 (R(2) = 0.45; P = .011), and SUV(mean) = 0.05 x PS + 5.36 (R(2) = 0.35; P = .04). The tumor to nontumor (muscle) SUV(mean) and SUV(max) ratio was 9.45 (+/- 3.55) and 17.58 (+/- 4.32), respectively. BF-ratio SUV(mean) and BF-ratio SUV(max) showed significant correlations (r = 0.64; P = .01 and r = 0.53; P = .04, respectively). Regression analysis showed ratio SUV(mean) = 0.14 x BF-3.48 (R(2) = 0.42; P = .01) and ratio SUV(max) = 0.14 x BF + 4.51 (R(2) = 0.29; P = .04). CONCLUSION Tissue perfusion-metabolic coupling is evident in head and neck SCCAs and may provide additional diagnostic information in patients undergoing PET/CT studies.