Pediatric CT with MBIR reduces rad dose, preserves image quality

CT scans performed with a reduced-dose protocol and model-based iterative reconstruction (MBIR) maintain diagnostic quality and are feasible in pediatric patients, according to a study published online Oct. 29 in Radiology.

The dangers that accompany radiation exposure have led to growing concerns in the medical community, particularly in regards to the pediatric demographic. Children are especially sensitive to ionizing radiation, which has spurred the development of strategies to reduce CT dose.

These new methods, however, come at a price. They reduce radiation output from the scanner, but create greater noise image and diminish image quality. Iterative CT image reconstruction techniques have been conceived to decrease image noise when scanning at lower doses, one of which is MBIR. MBIR differs from other iterative techniques because it accounts for a scanner’s optics, such as focal spot and detector size, and is applied only in one strength.

Ethan A. Smith, MD, of C.S. Mott Children’s Hospital, University of Michigan Health System, and colleagues designed a retrospective study in which image quality and radiation dose were compared between a reduced-dose CT protocol with MBIR and a standard-dose CT protocol that used 30 percent adaptive statistical iterative construction (ASIR) with a filtered back projection.

Clinical CT images of the chest, abdomen, and pelvis of 25 pediatric patients were obtained for a reduced-dose protocol that identified reconstructed images with two algorithms: MBIR and 100 percent ASIR. All subjects had undergone a standard-dose CT within the previous year. The reduced and standard-dose images were evaluated objectively and subjectively. Reduced-dose images were evaluated for lesion detectability, and spatial resolution was assessed in a phantom.

Radiation dose was estimated with a volumetric CT dose index and size-specific dose estimates were calculated.

Results indicated that both subjectively and objectively, reduced-dose MBIR images had less noise and superior spatial resolution in comparison with that of ASIR and a filtered back protection.

“The better spatial resolution offered by MBIR should be especially beneficial in small children, allowing for detection of smaller lesions and improving lesion delineation,” wrote Smith and colleagues.

Additional research is needed to establish more information about MBIR’s capabilities, as well as its weaknesses.

“While a goal of reducing radiation doses in pediatric CT is important, all new dose reduction technologies must be critically assessed to ensure that image quality and diagnostic capability are preserved,” remarked Smith and colleagues.