CT angiography + scaling power laws could ease diffuse CAD diagnosis

CT-determined morphometric parameters could offer insights into the diagnosis of diffuse coronary artery disease (CAD), according to a study published April 24 in Radiology.

“The major finding of this study is that patients with metabolic syndrome who have a higher predilection to diffuse CAD had significantly increased KLV values of the length-volume scaling power law,” wrote Yunlong Huo, PhD, of Indiana University-Purdue University Indianapolis, and colleagues.

Diffuse CAD is difficult to diagnose with angiography because there’s no “normal” reference vessel, explained the authors. Intravascular ultrasonography is an option, but it requires an invasive procedure.

In evaluating a non-invasive alternative to quantifying diffuse CAD, Huo and colleagues focused on morphometric data from the epicardial coronary artery tree, determined with CT angiography and analyzed on the basis of the scaling power law.

The scaling power laws, based on the principle of minimum energy, address the relationship between myocardial structure sizes and weights, and the authors hypothesized that the length-volume scaling power law can provide a signature of a “normal” vasculature. Any deviations could be used to quantify the extent of diffuse CAD, they added.

To test this hypothesis, CT angiographic data were retrospectively collected in 120 subjects, 89 of whom had metabolic syndrome and 31 matched control subjects.

Results showed the mean lumen cross-sectional area and sum of intravascular volume in patients with metabolic syndrome were significantly less than those in control subjects, reported the authors. Scaling analysis showed that more than 65 percent of patients with metabolic syndrome had a coefficient of at least 23 for the coronary vascular length-volume scaling power law, while for 90 percent of the control subjects the coefficient was less than 23.

“The results of this retrospective study suggest that an increase of coefficient of the coronary vascular length-volume scaling power law (≥23) can be a CT-based diagnostic index of diffuse coronary artery disease,” wrote Huo and colleagues.

The authors noted that the study only showed a proof of concept that the scaling power law could be used to confirm a greater probability of disease in a cohort of patients with a higher risk of diffuse CAD than a control cohort, and that future studies need to be conducted to fully investigate the relationship between the length-volume scaling power law and diffuse CAD progression.