4D flow MRI may improve automated valve tracking in congenital heart patients

Researchers from the Netherlands demonstrated in a study published Oct. 30 in Radiology that four-dimensional (4D) flow MRI with automated cardiac valve tracking reduces analysis time and improves reliability of valvular flow quantification compared to manual valve tracking in patients with congenital heart disease.  

Overall, 4D flow MRI—or “time-resolved, three-dimensional, three-directional velocity-encoded MRI”—allows for the direct quantification of blood flow through all four valves of the heart derived from one acquisition, according to the study.

The method has proven to be more accurate than conventional MRI, however various factors have halted it from becoming more commonly used in clinical practice. 

“Widespread use of this approach into clinical practice is hindered because manual placement and tracking of multiplanar reformatting planes in every cardiac phase for each valve is a time-consuming procedure with observer-dependent variation,” wrote Vivian P. Kamphuis, MD, of the Leiden University Medical Center in Leiden, Netherlands, and colleagues.  

For the study, the researchers collected data from 114 patients and 46 healthy volunteers who underwent flow MRI at 1.5T or 3T from 2006 through 2017.  

Of the 114 patients (average age 17 years, 55 percent men), 33 had acquired congenital heart disease and 81 already had the disease. Among the 46 volunteers, the average age was 28 years and 59 percent of volunteers were men. The researchers then used two orthogonal cine views of each valve for tracking.  

Automated tracking had a shorter analysis time than manual tracking—14 minutes versus 25 minutes, according to the researchers.  

“Although overall differences in net forward volume (NFV) and regurgitant fraction were comparable between both methods, NFV variation over four valves was smaller for automated versus manual tracking,” Kamphuis et al. wrote.

“Regurgitation severity was discordant for seven pulmonary valves, 22 mitral valves and 21 tricuspid valves; intra- and interobserver agreement for automated tracking was excellent for NFV assessment and strong to excellent for regurgitant fraction assessment” the authors added.