Low-dose multislice CT make gains in bone marrow diagnosis

Low-dose, whole-body CT not only provides a very sensitive diagnosis of osteolytic bone lesions, but it can also serve as an alternative to costly MR studies and replace time-consuming x-ray skeletal surveys, according to a presentation Tuesday.

German researchers assessed 40 patients with proven multiple myeloma. Twenty of them (group A) underwent whole-body scanning with an effective dose of 100 mAs. The remaining 20 (group B) underwent whole-body scanning at 50 mAs. The low-dose protocol provided high-quality images, but with a radiation exposure similar to that of x-rays.

"We are moving to use the 50 mAs as our standard dose protocol at our institution," said coauthor Dr. Sonja Buhmann, a resident at the University of Munich's Institute of Clinical Radiology.

The investigators could detect all osteolytic lesions in both groups. Qualitative evaluation scored as nearly excellent for group A and good for group B, according to the four-grade scale used by two experienced readers (1 = excellent, 4 = not sufficient).

The calculated mean radiation dose was 10 mSv and 5 mSv for groups A and B, respectively. Group B recorded significantly higher mean image noise values than the standard protocol (84 HU vs 51 HU). The scanning protocol for both groups included 16-row scanning with 3-mm axial and sagittal slice reconstruction and 1.5 collimation at 120 kVp. Whole-body MRI served as the gold standard for comparison.

A comparison chart showed costs for CT scanning as slightly higher than for x-rays, but more affordable than MR (320, 230, and 590 euros, respectively). Multislice CT scanning, however, could be accomplished at a fraction of the time invested in x-ray and MR image processing, Buhmann said.