Application of dynamic CT for various diseases in the oral and maxillofacial region

Objective: To investigate whether dynamic CT enables quantitative differentiation between inflammation, benign tumors, and malignant tumors in oral and maxillofacial regions. Methods: Sixteen malignant tumors (14 squamous cell Ca, one adenoid cystic Ca, one mucoepidermoid Ca), six benign tumors (one Warthin tumor, two pleomorphic adenomas, one lipoma, one Schwanoma, one hemangioma), and seven inflammation cases (three submandibular adenitis, two osteomyelitis, two perimandibular inflammations) were examined. Contrast agent (0.8 ml/kg) was injected intravenously at 5 ml/s. CT (Toshiba TCT 900S) scanning was performed at the time of the beginning of contrast medium injection. Parameters from the time-density curve were investigated: peak height (PH), relative CT value from the base CT value when the curve reached peak point; peak time (PT), the time when the curve reaches the peak point from contrast medium infusion; transit time (TT), time between two transit points on the time-density curve; and peak time ratio (PR), the ratio of peak time from the lesion to the artery and peak time from the vein to the artery. Results: PH was highest in inflammation, followed by malignant tumors and benign tumors. TT was significantly longer in benign tumor cases compared with malignant tumor and inflammation cases. PR for malignant tumor and inflammation were between the artery and vein phase, and that for benign tumor was beyond the vein phase. Conclusion: Parametrical analysis of a contrast enhanced dynamic CT study may serve to differentiate the lesions in the oral and maxillofacial region.