Single-Energy Low-Voltage Arterial Phase Scanning for the Detection of Adenocarcinoma of the Pancreas

PURPOSE: To test a single-energy low-voltage arterial phase protocol for the diagnosis of adenocarcinoma of the pancreas.METHOD AND MATERIALS: 19 patients (10 M, 9 F, mean age 64 years) with pathology proven adenocarcinoma of the adenocarcinoma underwent triphasic abdominal CTwith arterial phase at 80 kVp and 370 mAs (test group) on a 64-row MDCT. These were compared to a similar group of 19 patients (12 M, 7 F, mean age 57 years)scanned on the same scanner with a 120 kVp arterial phase protocol with automatic tube current modulation (control group). Except for tube parameters, all otherscan parameters were kept constant. Scans were compared for quantitative image parameters (attenuation and standard deviation in the liver, pancreas, aorta andadenocarcinoma of the pancreas) and for dose parameters (CTDI and DLP) using an unpaired t-test. Contrast/noise ratio (CNR) was calculated for normalparenchyma and adenocarcinoma in both groups. Image noise was also measured as the standard deviation of the HU from 3 ROIs drawn outside the body.Unpaired t-test was used for statistical analysis.RESULTS: Mean attenuation was significantly higher in the test group than in the control group in the aorta (547.92±140.84 vs 281.90±101.23 HU; p<0.0001),liver (92.63±18.11 vs 78.45±15.48 HU; p=0.0004) and normal pancreas (168.90±45.64 vs 97.86±14.99 HU; p<0.0001), while no significant difference wasobserved for adenocarcinoma attenuation (83.77±41.18 vs 57.77±23.63 HU; p=n.s.). Radiation dose was significantly lower in the test group than in the controlgroup (CTDI 6.64±0 vs 9.41±2.79 mGy, p=0.0016; DLP 196.02±40.94 vs 365.07±138.30 mGy x cm; p=0.0003). CNR was not significantly different between thetest and the control group both for normal parenchyma (8.3±1.3 vs 6.1±0.5; p=n.s.) and carcinoma (3.3±0.5 vs 3.4±0.5; p=n.s.). Tumor conspicuity, calculatedas the difference in attenuation between carcinoma and normal pancreas, was significantly higher in the test group (85.12±41.60 vs 40.10±23.92 HU). Meanimage noise was significantly higher in the test group than in control group (12.14±4.03 vs 10.13±3.23 HU; p=0.0174).CONCLUSION: The use of 80 kVp arterial phase for abdomen CT increases the conspicuity of adenocarcinoma thus potentially improving its identification.CLINICAL RELEVANCE/APPLICATION: The use of a low-voltage scan for the pancreatic phase increases the conspicuity of adenocarcinoma thus potentiallyimproving its identification