Reduction of iodine load in CT imaging of pancreas acquired with low tube voltage and an adaptive statistical iterative reconstruction technique

Purpose: To prospectively assess the contrast enhancement, image quality, radiation dose, and detectability of malignant pancreatic tumors with pancreatic computed tomography (CT) obtained at an 80-kilovolt (peak) (kV[p]) tube voltage setting and reduced iodine dose.

Methods: Institutional review board approval and written informed consent were obtained. During a recent 10-month period, 136 patients (66 men and 70 women; age range, 21-86 years; mean ± SD age, 65.9 ± 11.0 years) with suspected pancreatic diseasewere randomized into 3 groups according to the following iodine-load and tube-voltage protocols: 600mg of iodine per kilogram body weight (mg/kg) and 120 kV(p) (600-120 group), 500 mg/kg and 80 kV(p) (500-80 group), and 400 mg/kg and 80 kV(p) (400-80 group). Analysis of variance was conducted to evaluate differences in CT number, background noise, signal-to-noise ratio, effective dose, lesion-to-pancreas contrast-to-noise ratio, and figure of merit. Sensitivity, specificity, and area under the receiver-operating-characteristic curve were compared to assess the detectability of malignant pancreatic tumors.

Results: The signal-to-noise ratios in vessels were greater (P < 0.05) in the 400-80 and 500-80 groups than in the 600-120 group, and those in pancreas were comparable between the 400-80 and 600-120 groups. No significant difference was found in effective dose, image quality, lesion-to-pancreas contrast-to-noise ratio, or figure of merit between the groups. Sensitivity, specificity, and area under the receiver-operatingcharacteristic curve for detecting malignant pancreatic tumors were comparable between the groups.

Conclusions: Pancreatic CTwith an 80-kV(p) setting and 400-mg iodine per kilogram contrast material load facilitates the reduction of iodine dose while maintaining image quality and the detectability of malignant pancreatic tumors.