Low-dose CT colonography combined with MBIR cuts radiation exposure by nearly 50 percent

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Model-based iterative reconstruction (MBIR) technology used in conjunction with reduced-dose CT colonography improves image noise and maintains image quality while significantly reducing patient exposure to radiation, according to a study published in the February issue of Academic Radiology.

CT colonography is gaining momentum among clinicians as an effective diagnostic and screening tool for colorectal cancers. Despite the technique’s growing popularity, the stigma of increased radiation exposure from CT scans in symptomatic populations remains. This has led researchers to search for new ways of maintaining image quality without the need for elevated doses of radiation.

“In particular, there has been increasing emphasis on dose reduction strategy using iterative reconstruction techniques and this should be optimized in the context of [CT colonography],” writes lead author Varut Vardhanabhuti, FRCR, of the Plymouth University Peninsula Schools of Medicine and Dentistry in the U.K., and colleagues. “Because of increasing computing power, a newer method of reconstruction from raw CT data is now possible, with more accurate estimation of true image from statistical modeling and more comprehensive assumption of source data.”

For the study, Vardhanabhuti and his team performed standard-dose and low-dose CT colonography scans on 65 symptomatic patients using three distinct methods of reconstruction: traditional filtered-back projection, adaptive statistical iterative reconstruction, and MBIR. They compared the results of each patient, dosage and reconstruction method for objective image noise, subjective image quality and effectiveness of polyp detection.

Their results showed that the MBIR technique combined with low-dose scans caused a significant reduction in image noise, and that image quality and polyp detection remained unchanged, despite a substantial reduction in patient radiation exposure. In fact, Vardhanabhuti and his team reported an attainable average radiation dose reduction of 47 percent. “The capability for improved image noise allows scan acquisition at lower radiation doses,” the researchers wrote. “This study confirms the feasibility of using MBIR in achieving LD scans [CT colonography] in symptomatic population without compromising image quality.”

The application of MBIR is not the only recent advancement in CT colonography research: One study recently found the technique to be an effective and patient-friendly alternative to colonoscopy in patients in remission from ulcerative colitis.