Could photon-counting computed tomography angiography (PC CTA) provide a viable non-invasive alternative to digital subtraction angiography (DSA) for detection of stenotic lesions in patients with peripheral artery disease (PAD)?
For the retrospective study, recently published in the European Journal of Radiology, researchers evaluated the capability of PC CTA to detect stenotic disease in 109 patients (median age of 74.68) who had PC CTA and subsequent DSA. The study authors also assessed photon-counting (PC) pure lumen reconstructions for 91 patients in the cohort. For the PC CTA evaluation, researchers reviewed data for a total of 933 vascular segments and assessed 780 vascular segments for the PC pure lumen reconstructions, according to the study.
The study authors found that PC CTA offered 91 percent sensitivity, 95 percent specificity and 93 percent accuracy in identifying stenotic disease. For the PC pure lumen reconstructions, researchers noted 85 percent sensitivity, 89 percent specificity and 88 percent accuracy.
“The results of this study demonstrate that PC CTA enables detection of high-grade vascular stenosis with an accuracy above 93% and thus PC CTA is a non-invasive valuable modality for diagnostic and for treatment planning purposes in patients with symptomatic PAD,” wrote lead study author Patrick Ghibes, M.D., who is affiliated with the Department for Diagnostic and Interventional Radiology at University Hospital Tubingen in Tubingen, Germany, and colleagues.
Noting the common dilemma of differentiating between vessel calcifications and true intravascular contrast for small vessel diameters in the arterial vasculature of the calf, the researchers pointed out that photon-counting CT maintained a greater than 90 percent accuracy for stenotic disease in contrast to approximately 70 percent for conventional CT reported in the literature.
Three Key Takeaways
1. High diagnostic accuracy. Photon-counting CTA (PC CTA) demonstrated high diagnostic performance in detecting stenotic disease, with 91 percent sensitivity, 95 percent specificity, and 93 percent accuracy overall, making it a viable non-invasive alternative to digital subtraction angiography (DSA) for patients with peripheral artery disease (PAD).
2. Enhanced accuracy in challenging segments. PC CTA maintained over 90 percent accuracy in detecting stenosis even in small diameter vessels, like those in the calf, where conventional CT accuracy is around 70 percent. This highlights PC CTA’s ability to differentiate between calcifications and true intravascular contrast, especially in difficult to assess vascular segments.
3. Best results in iliac segments. The highest accuracy was achieved in iliac artery segments, with 95 percent sensitivity, 98 percent specificity, and 98 percent accuracy. This suggests that PC CTA may be particularly beneficial for detecting stenosis in larger proximal vessels.
“The diagnostic image quality of PC CTA enables reliable detection of high-grade stenosis even in the challenging to assess calf arterial segments,” emphasized Ghibes and colleagues.
The study authors said the best detection of stenotic disease occurred with iliac segments as PC CTA demonstrated 95 percent sensitivity, 98 percent specificity and 98 percent accuracy. Pure lumen reconstructions with PC CTA achieved a 93 percent sensitivity rate, 94 percent specificity and 93 percent accuracy for iliac segments, according to the study authors.
(Editor’s note: For related content, see “New Study Assesses Benefits of High-Resolution Photon-Counting for Computed Tomography Angiography,” “Study: Photon-Counting CT Improves Accuracy of Coronary Stenosis Assessment” and “Can Polyenergetic Reconstruction Help Resolve Streak Artifacts in Photon Counting CT?”)
In regard to study limitations, the authors conceded possible patient selection bias, noting that the majority of the cohort had a history of PAD and only a small number of patients had less severe PAD. They also pointed to a lack of comparison of photon-counting CTA to multidetector CT and dual-energy CT in this study.
