Scientific Publications Database
Article Title: Diagnostic Accuracy of Attenuation Difference and Iodine Concentration Thresholds at Rapid-Kilovoltage-Switching Dual-Energy CT for Detection of Enhancement in Renal MassesAuthors: Sadoughi, Nima; Krishna, Satheesh; Macdonald, David B.; Chatelain, Robert; McInnes, Matthew D. F.; Schieda, Nicola
Journal: AMERICAN JOURNAL OF ROENTGENOLOGY Volume 213 Issue 3
Date of Publication:2019
Abstract:
OBJECTIVE. The objective of our study was to evaluate iodine concentration and attenuation change in Hounsfield unit (Delta HU) thresholds to diagnose enhancement in renal masses at rapid-kilovoltage-switching dual-energy CT (DECT).MATERIALS AND METHODS. We evaluated 30 consecutive histologically confirmed solid renal masses (including nine papillary renal cell carcinomas [RCCs]) and 27 benign cysts (17 simple and 10 hemorrhagic or proteinaceous cysts) with DECT December 2016 and May 2018. A blinded radiologist measured iodine concentration (in milligrams per milliliter) and Delta HU (attenuation on enhanced CT - attenuation on unenhanced CT) using 70-keV corticomedullary (CM) phase virtual monochromatic and 120-kVp nephrographic (NG) phase images. The accuracies of previously described enhancement thresholds were compared by ROC curve analysis.RESULTS. An iodine concentration of >= 2.0 mg/ml, and an iodine concentration of >= 1.2 mg/mL achieved sensitivity, specificity, and the area under the ROC curve (AUC) of 73.3%, 100.0%, and 0.87 and 86.7%, 100.0%, and 0.93, respectively. On 70-keV CM phase images, Delta HU >= 20 HU and Delta HU >= 15 HU yielded sensitivity, specificity, and AUC. of 80.0%, 100.0%, and 0.90 and 90.0%, 100.0%, and 0.95, respectively. The numbers of incorrectly classified papillary RCCs were as follows: iodine concentration of >= 2.0 mg/mL, 77.8% (7/9; range, 0.7-1.6 mg/mL); iodine concentration of >= 1.2 mg/mL, 44.4% (4/9; range, 0.7-0.9 mg/mL); Delta HU >= 20 HU on 70-keV CM phase images, 66.7% (6/9; range, 4-17 HU); and Delta HU >= 15 HU on 70-keV DECT images, 33.3% (3/9; 4-12 HU). No cyst pseudoenhancement occurred on DECT. For 120-kVp NG phase DECT, Delta HU >= 20 HU and Delta HU >= 15 HU yielded sensitivity, specificity, and AIM of 93.3%, 96.3%, and 0.95 and 100.0%, 88.9%, and 0.94, respectively. With Delta HU >= 20 HU, 22.2% (2/9) (range, 15-18 HU) of papillary RCCs were misclassified and there was one pseudoenhancing cyst. With Delta HU >= 15 HU, no papillary RCCs were misclassified but 11.1% (3/27) of cysts showed pseudoenhancement. Only an iodine concentration of >= 2.0 mg/ml, showed significantly lower accuracy than other measures (p = 0.031-0.045).CONCLUSION. DECT applied in the CM phase performed best using an iodine concentration of >= 1.2 mg/mL or a 70-keV Delta HU >= 15 HU; these parameters improved sensitivity for the detection of enhancement in renal masses without instances of cyst pseudoenhancement.