July 17, 2015
1 min read

Iterative image reconstruction enables reduced CTA radiation dose, maintains image quality

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Iterative image reconstruction, a feature available on the newest CTA systems, maintained image quality while allowing for a 30% reduction in radiation dose, according to findings from the PROTECTION V study.

New image reduction techniques have been introduced by CT vendors to allow image noise reduction at unchanged radiation dose levels or radiation dose reductions at comparable image noise levels, according to the study background.

The researchers conducted a prospective, multicenter, multivendor noninferiority trial in which they randomly assigned 400 consecutive patients to a control group that received CTA using standard filtered back projection image reconstruction and standard tube current or an interventional group that underwent CTA incorporating iterative image reduction and 30% current tube reduction.

The primary endpoint was noninferiority in image quality in the intervention group. Image quality was quantified on a 4-point scale, with 1 point signifying nondiagnostic image quality and 4 points signifying excellent image quality. Secondary endpoints included estimated total radiation dose and rate of downstream testing over 30 days of follow-up.

Simon Deseive, MD, from Medizinische Klinik und Poliklinik I der Ludwig-Maximilians-Universität München, Munich, and colleagues found that median image quality in the intervention group was noninferior to that of the control group (intervention, 3.5; interquartile range [IQR], 3-4; control, 3.4; IQR, 2.8-4; P for noninferiority < .016).

They also found that radiation exposure was less in the intervention group (median dose-length product, 157 mGy∙cm (IQR, 114-239) vs. 222 mGy∙cm (IQR, 141-319; P < .0001).

In addition, the researchers wrote, the rate of downstream testing was similar between the groups (intervention, 7.7%; control, 7.9%; P = .94).

“[Iterative image reconstruction] should be used whenever available in pursuit of the ultimate goal to obtain diagnostic coronary CTA images with the lowest possible radiation dose,” Deseive and colleagues wrote. “However, it is yet to be determined to what threshold the tube current can be lowered when [iterative image reconstruction] is used.” – by Erik Swain

Disclosure: Deseive reports no relevant financial disclosures. Other researchers report financial ties with Abbott Vascular, GE Healthcare, Philips Medical Systems, Siemens Medical Systems and Toshiba Medical Systems.