Can Single-Energy Low-Voltage Arterial Phase Scanning Be Used to Increase Conspicuity of Hypervascular Lesions of the Liver?

PURPOSETo test a single-energy low-voltage arterial phase protocol for the detection of homogeneous hypervascular focal liver lesions (hFLL). METHOD AND MATERIALS24 patients with chronic liver disease underwent multiphasic MDCT of the abdomen with a 80 kVp and 370 mAs arterial phase scan (test group); 9 of these had hypervascular lesions. This test group was compared to a similar control group of 24 patients with solid hypervascular lesions, scanned on the same scanner with a 120 kVp arterial phase protocol with automatic tube current modulation (control group) All the exams were performed a 64-row MDCT scanner; only tube parameters were different between the two groups, while all other scan parameters were kept constant. Using an unpaired t-test, scans were compared for quantitative imaging parameters (attenuation and standard deviation in the liver, aorta and in the largest hFLL) and for dose parameters (CTDI and DLP). Placing 3 circular ROIs outside the body, image noise values were measured as the standard deviation of the pixel values for each protocol and compared using an unpaired t-test. RESULTSMean attenuation in the test group was significantly higher than in the control group in the three examined regions (aorta: 492.18 ± 143.48 vs 284.05 ± 65.26 HU, p<0.0001; liver 79.35 ± 13.17 vs 59.04 ± 11.21 HU, p<0.0001; hFLL: 149.16 ± 30.02 vs 103.20 ± 18.74 HU, p<0.0001). Lesion conspicuity, calculated as the difference in attenuation between the nodule and the liver, was significantly higher in the test group (72.18 ± 35.31 vs 44.16 ± 16.98 HU; p=0.0026). Radiation dose was significantly lower in the test group than in the control group (CTDI: 6.64 ± 0 vs 12.50 ± 3.96 mGy; DLP: 207.92 ± 24.26 vs 412.57 ± 123.47 mGy x cm; p<0.0001). Mean image noise was significantly higher in the test group than in control group (12.03 ±3.19 vs 9.86 ± 2.52 HU; p<0.0001). CONCLUSIONThe use of a single-energy 80 kVp arterial phase protocol for abdominal CT may increase the conspicuity of hypervascular liver lesions, improving their identification. CLINICAL RELEVANCE/APPLICATIONThe use of a 80 kVp arterial phase protocol for abdominal CT may increase the conspicuity of hypervascular liver lesions, improving their identification.