Lifeng Yu PhD, Presenter: Nothing to Disclose

Jon Camp PhD, Abstract Co-Author: Nothing to Disclose

Michael Robert Bruesewitz, Abstract Co-Author: Nothing to Disclose

Margaret Holets, Abstract Co-Author: Nothing to Disclose

Elizabeth Atkinson, Abstract Co-Author: Nothing to Disclose

L. Joseph Melton MD, Abstract Co-Author: Nothing to Disclose

Cynthia H. McCollough PhD, Abstract Co-Author: Research grant, Siemens AG

Louise K. McCready RN, Abstract Co-Author: Nothing to Disclose

B Lawrence Riggs MD, Abstract Co-Author: Nothing to Disclose

Sundeep Khosla MD, Abstract Co-Author: Nothing to Disclose

Dual-energy quantitative CT (DEQCT) was developed in the1980s for bone mineral density (BMD) measurement. It can reduce the influence of bone marrow fat and improve the accuracy over single-energy quantitative CT (SEQCT). However, limited by the old technology, DEQCT was not clinically adopted due to its poor precision. With the recent development of more advanced dual-energy CT technology, many previous limitations have been eliminated. The purpose of this study was to re-evaluate the precision of BMD measurement on a dual-source scanner using a phantom study and a pilot prospective patient study.

An error analysis was first performed to predict the precision of DEQCT for given variations in each of the single-energy images. A standard quality control phantom (European Spine Phantom) was scanned on a dual-source scanner (Definition, Siemens) with a DEQCT protocol, repeated 9 times in 5 days. A calibration phantom (Mindways) was placed underneath the spine phantom during the scans. The total CTDIvol of the two energy scans in the DEQCT protocol was 12 mGy, which was twice of that in our routine SEQCT protocol. Twelve patients (6 older women: mean age 73.5; 6 younger women: mean age 27.5) were then enrolled. The older group was scanned twice in a one-month interval, which was used for repeatability test. The younger group was scanned only once, which was used as a reference.

In the phantom study, the precisions of DEQCT, 140 kV, and 80 kV were 2.0%, 1.0%, 0.84%, respectively. The 140 kV and 80 kV SEQCT were 2-3 times better than DEQCT, which agreed with the results in theoretical error analysis. In the patient study, the percentage difference of BMD averaged over L1-L3 between the two visits of older group was 2.4%, 0.9%, and 1.3% for DEQCT, 140 kV, and 80 kV, respectively. Compared to DEQCT, the BMDs obtained from 140 kV and 80 kV SEQCT were 11.4% and 7.9% lower for older women, but only 0.4% and 1.9% lower for younger women.

The precision of DEQCT on a dual-source CT scanner reaches 2.0% in phantom study and 2.4% in patient study. Compared to SEQCT, DEQCT is a less precise but more accurate method for BMD measurement.

DEQCT, which is a more accurate method for BMD measurement compared to SEQCT, may become clinically feasible due to the improved precision obtainable using dual-source CT scanners.

Yu, L, Camp, J, Bruesewitz, M, Holets, M, Atkinson, E, Melton, L, McCollough, C, McCready, L, Riggs, B, Khosla, S, Dual-Energy Quantitative CT Revisited with a Dual-Source Scanner: A Phantom and Pilot Patient Study.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9008425.html