Daniele Marin MD, Presenter: Fellowship funded, Bracco Group

Rendon C. Nelson MD, Abstract Co-Author: Consultant, General Electric Company Research support, Bracco Group Research support, Covidien AG Speakers Bureau, Siemens AG

Erik K. Paulson MD, Abstract Co-Author: Research Consultant, Siemens AG Stockholder, ZONARE Medical Systems, Inc

Lisa Diane Hooper-Gore MD, Abstract Co-Author: Nothing to Disclose

Daniel Tobias Boll MD, Abstract Co-Author: Nothing to Disclose

David Delong, Abstract Co-Author: Nothing to Disclose

Sebastian Tobias Schindera MD, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

To compare a low energy (80 kVp) technique with a standard high energy (140 kVp) technique for the detection of hypervascular liver tumors on multidetector computed tomography (MDCT) during the late hepatic arterial phase.

The study cohort comprised 48 patients (31 men, 17 women; age range, 35-77 years) with 69 hypervascular liver tumors (mean diameter, 20±16 mm): metastases from renal cell carcinoma (n=15), metastases from neuroendocrine tumor (n=13), metastases from breast cancer (n=6), and hepatocellular carcinoma (n=35). Subjects underwent a dual energy, 64-slice MDCT scan (LightSpeed VCT; GE Healthcare) during the late hepatic arterial phase. The following two imaging parameters were compared using a vendor-provided software (Volume Dual Energy; GE Healthcare): 80 kVp / 540 mAs vs. 140 kVp / 308 mAs. Tumor-to-liver contrast (TLC) and contrast-to-noise ratio (CNR) were measured for each lesion at each kVp, and compared between 80 and 140 kVp datasets. Mean image noise levels were also compared between the two datasets. Additionally, 3 readers independently reviewed the 80 and 140 kVp datasets in a blinded fashion. Lesion detection, characterization, and reader confidence levels were recorded, as well as readers’ subjective evaluation of image quality. Wilcoxon-Mann-Whitney statistics were performed.

Image noise increased from 5.7 to 11.3 HU when tube voltage decreased from 140 to 80 kVp (P < 0.001).This was also reflected by a significantly lower score (2.9 vs 4.0) of image quality at 80 kVp images by all readers (P < 0.001). At the same time, there was a substantial increase of TLC and CNR at 80 (85.8 ± 11.6 and 8.1 ± 0.9) compared with 140 kVp images (36.9 ± 5.6 and 6.4 ± 0.9) (P < 0.001). This resulted in significantly improved tumor detection rate on 80 kVp images for all readers (P < 0.001). Varying the tube voltage did not alter readers’ capability to characterize hypervascular liver lesions.

By substantially increasing the TLC and CNR, a low tube voltage MDCT technique at 80 kVp with high mAs significantly improved detection of hypervascular liver tumors during the late hepatic arterial phase.

A low tube voltage MDCT technique at 80 kVp with high mAs increases detection of hypervascular liver lesions, although this improvement comes at the price of a poorer image quality.

Marin, D, Nelson, R, Paulson, E, Hooper-Gore, L, Boll, D, Delong, D, Schindera, S, et al, , Dual Energy, 64-Slice Multidetector CT: Comparison of 80- and 140-kVp for Detection of Hypervascular Liver Tumors during the Late Hepatic Arterial Phase.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6018534.html