Apparent diffusion coefficient mapping for sinonasal diseases: differentiation of benign and malignant lesions.

BACKGROUND AND PURPOSE CT and MR imaging features of benign and malignant sinonasal lesions are often nonspecific. Therefore, we evaluated the ADC-based differentiation of these lesions. MATERIALS AND METHODS We retrospectively assessed ADCs of 61 patients with histologically proved sinonasal tumors and tumorlike lesions: 19 benign lesions, 28 malignant tumors, and 14 inflammatory lesions. Overall ADCs and percentages of total tumor area with extremely low, low, intermediate, or high ADCs (ADC mapping) were determined by using 2 b-values (500 and 1000 s/mm(2)). RESULTS ADCs of malignant tumors (0.87 ± 0.32 × 10(-3) mm(2)/s) were significantly lower than those of benign (1.35 ± 0.29 × 10(-3) mm(2)/s, P < .0001) and inflammatory (1.50 ± 0.50 × 10(-3) mm(2)/s, P = .0002) lesions. On ADC mapping, percentages of total tumor area within malignant tumors having extremely low or low ADCs were significantly (P < .0001) greater than those within benign and inflammatory lesions. Cutoff points for ADC mapping (≥78% of tumor areas having extremely low or low ADCs) effectively differentiated benign or inflammatory lesions and malignant tumors with 75% sensitivity, 94% specificity, 85% accuracy, and 91% positive and 82% negative predictive values, respectively. ADCs also effectively discriminated lymphomas and SCCs from other malignant tumors. CONCLUSIONS ADC mapping may be an effective MR imaging tool for the differentiation of benign/inflammatory lesions from malignant tumors in the sinonasal area.