Determining the fractional flow reserve (FFR) from CT conceptually involves four steps, but there is currently no guiding standard for executing the process.
A recent study published in the April 2018 issue of Radiology optimized a four-step approach to accurately detect hemodynamically significant intermediate-stenosis lesions, which outperformed coronary CT angiography. Researchers also found using coronary contrast opacification variations to estimate blood flow distribution may improve CT FFR accuracy.
In this research, a team of scientists applied a four-step CT FFR algorithm to 61 patients with a lesion of intermediate-diameter stenosis at CT angiography who received FFR measurement within 90 days.
Three different approaches were tested to estimate blood flow distribution for CT FFR. The first two—the Murray law and Huo-Kassab rule—both used coronary anatomy. The final relied on contrast material opacification gradients. Stenosis measurements were compared using the area under the receiver operating characteristic curve (AUC) to detect FFRs of .8 or lower.
Results were as follows:
- 41 percent of lesions had FFRs of .8 or lower.
- The AUC of CT FFR determination using contrast material gradients was significantly higher than that of the Huo-Kassab and Murray law models.
- Correlation of CT FFR with FFR was highest for gradients, followed by the Huo-Kassab rule and then Murray law.
“Clinicians can perform CT FFR by using a four-step approach on site to accurately detect hemodynamically significant intermediate-stenosis lesions,” wrote Dimitris Mitsouras, PhD with the Department of Cardiovascular Imaging at Johns Hopkins Medicine, and colleagues. “Estimating blood flow distribution by using coronary contrast opacification variations may improve CT FFR accuracy.”
Matt joined Chicago’s TriMed team in 2018 covering all areas of health imaging after two years reporting on the hospital field. He holds a bachelor’s in English from UIC, and enjoys a good cup of coffee and an interesting documentary.