Contrast-enhanced helical CT of the head and neck: Improved conspicuity ofsquamous cell carcinoma on delayed scans

OBJECTIVE. We evaluated the impact of delayed scans on the conspicuity of s quamous cell carcinoma in helical CT of the head and neck. SUBJECTS AND METHODS. Twenty-seven patients with biopsy-proven squamous cel l carcinoma of the head and neck underwent dual-phase helical CT examinatio ns using 100 mt of nonionic contrast material. In all patients, the early p hase started 30 sec after the commencement of injection. The patients were assigned to one of two groups in which the delayed phase started either 180 sec (group A, n = 13) or 300 sec (group B, n = 14) after the start of inje ction. The overall image quality, including vascular opacification and the quality of lesion conspicuity, was determined according to a three-point sc oring system. RESULTS. Overall image quality scored better on the early scans (score, 1.4 +/- 0.5) than on the late scans with a 180-sec (score, 1.6 +/- 0.6; p = 0. 03) or a 300-sec delay (score, 2.4 +/- 0.5; p = 0.002). Tumor conspicuity s cored better on scans with a 180-sec delay (score, 1.4 +/- 0.5) than on the scans with a 30-sec delay (score, 2.3 +/- 0.7; p = 0.02) or the scans with a 300-sec delay (score, 2.3 +/- 0.7; p = 0.03). In eight (62%) of 13 patie nts in group A and in six (43%) of 14 patients in group B, the tumor was be tter delineated on the late scans than on the early scans. CONCLUSION. Although early scans provide optimal vascular enhancement and a re therefore necessary for helical CT studies of the head and neck, additio nal delayed scans may improve lesion detection in patients with squamous ce ll carcinoma of the head and neck.