The accuracy of computed tomographic perfusion in detecting recurrent nasopharyngeal carcinoma after radiation therapy

To assess the diagnostic accuracy of computed tomographic (CT) perfusion technique in discriminating recurrent nasopharyngeal carcinoma (NPC) after radiation therapy. Forty-eight patients with a pathologic finding as reference standards were divided into 2 groups, recurrent and nonrecurrent NPCs. Perfusion parameters blood flow (BF), blood volume (BV), permeability surface (PS), and mean transit time were statistically analyzed. A receiver operating characteristic curve was used to study whether CT perfusion parameters could aid in detecting recurrent NPC. Blood flow, BV, and PS values between recurrent NPC (n = 27) and nonrecurrent NPC (n = 21) were 526.8 (168.1) versus 312.1 (214.4) mL/100 g per minute, 35.1 (23.6) versus 9.2 (8.0) (ml/100 g), and 53.4 (34.3) versus 17.6 (14.7) mL/100 g per minute, respectively. There was a significant difference between these 2 groups (P < 0.01). Mean transit time values in these 2 groups were 3.5 (2.0) versus 4.3 (2.7) seconds; there was no statistical difference. To optimize sensitivity and specificity, BF, BV, and PS threshold values for differentiating between recurrent and nonrecurrent NPCs were 537.20 mL/100 g per minute, 37.18 (ml/100 g), and 57.34 mL/100 g per minute, respectively. According to threshold values of BF, BV, and PS, sensitivity and specificity for distinguishing recurrent and nonrecurrent NPCs were 92.6% and 76.2%, 96.3% and 81%, and 81.5% and 61.9%, respectively. The CT perfusion technique may be helpful to find patients with recurrent NPC after radiation therapy.