Single-energy low-voltage arterial phase MDCT scanning increases conspicuity of adenocarcinoma of the pancreas

Abstract

PurposeTo test a single-energy low-voltage CT protocol for pancreatic adenocarcinoma. Methods and materialsA total of 30 patients with pathology-proven pancreatic adenocarcinoma underwent 64-row MDCT with arterial phase at 80kV and were compared to a similar group of 30 patients scanned with a 120kV protocol. Scans were compared for quantitative image parameters (attenuation and standard deviation in the pancreas, tumor, aorta), CTDI and DLP using an unpaired t-test. Image noise values for each protocol (SD of the psoas) were compared using an unpaired t-test. Effective dose was calculated for each protocol. CNR (=conspicuity/SDnoise) and FOM (CNR2/ED) were calculated. The Catphan600 phantom was used to evaluate image non-uniformity, noise, spatial resolution, and low contrast detectability. ResultsMean patient weight was 68kg in the study group and 73kg in the control group (p=0.0355), while patient diameters at the celiac axis were not significantly different. Mean attenuation was significantly higher at 80kV in the aorta (517.5±116.4 vs 290.3±76.4HU) and normal pancreas (154.0±39.95 vs 90.02±19.01HU) (all p<0.0001), while no significant difference was observed for adenocarcinoma (61.43±35.61 vs 47.45±18.95; p=n.s.). CTDI and DLP were significantly lower at 80kV (6.00±0.90mGy vs 10.24±2.93mGy, and 180.4±35.49mGycm vs 383.8±117mGycm, respectively; all p<0.0001). Tumor conspicuity (HUpancreas−HUtumor) was significantly higher at 80kV (94.2±39.3 vs 39.5±22HU; p<0.0001). Mean image noise was significantly higher at 80kV (28.32±10.06 vs 19.7±7.1HU; p<0.0001). Effective dose was significantly lower at 80kV (1.984±0.39 vs 5.75±1.75mSv; p<0.0001). The total DLP for the exam was 1024±31.86mGycm for the 80kV protocol and 1357±62.60mGycm for the 120kV protocol (p<0.0001).Phantoms showed higher non-uniformity, slightly higher noise, slightly lower MTF (50%) and slightly higher percentage contrast for the 80kV protocol. ConclusionSingle-source 80kV pancreatic phase scanning results in higher conspicuity of pancreatic adenocarcinoma and FOM and in significant dose reduction while maintaining acceptable image quality.