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Fractal analysis of dynamic stress myocardial CT perfusion decouples diagnostic accuracy for obstructive coronary
Florian Michallek1,2, Satoshi Nakamura3, Masafumi Takafuji4
1Department of Advanced Diagnostic Imaging, Mie University Graduate School of Medicine, 2-174, Edobashi, Tsu, Mie, 514-8507, Japan. florian-michallek@med.mie-u.ac.jp.
Insights
Fractal analysis improves detection of obstructive coronary artery disease (CAD) on CT perfusion imaging, especially when remote flow is reduced. This method enhances diagnostic accuracy for CAD, outperforming relative myocardial blood flow analysis.
Area of Science:
- Cardiology
- Medical Imaging
- Vascular Disease
Background:
- Dynamic stress CT perfusion imaging (CTP) has limitations in detecting obstructive coronary artery disease (CAD) when remote flow is reduced.
- Fractal analysis offers a novel approach to assess macro- and microvascular ischemia patterns.
Purpose of the Study:
- To compare the diagnostic accuracy of fractal analysis versus relative myocardial blood flow (MBF) for detecting obstructive CAD.
- To evaluate these methods in patients stratified by remote flow levels.
Main Methods:
- Secondary analysis of the AMPLIFiED trial data, including patients with invasive coronary angiography (ICA), fractional flow reserve (FFR), and dynamic stress CTP.
- Obstructive CAD defined by stenosis ≥90% or FFR <0.8.
- Assessment of fractal analysis and relative MBF diagnostic accuracy in high, intermediate, and low remote flow groups.
Main Results:
- Fractal analysis demonstrated superior patient-based sensitivity (94%) and specificity (92%) compared to relative MBF (80% and 64%) for obstructive CAD detection (p<0.005).
- In vessel-based analysis, fractal analysis outperformed relative MBF in intermediate and low remote flow groups (AUCs 0.93 vs 0.77 and 0.92 vs 0.6, respectively).
- Microvascular ischemia prevalence increased with reduced remote flow (9% in high, 37% in intermediate, 70% in low).
Conclusions:
- Fractal analysis enhances the diagnostic accuracy of CTP for obstructive CAD, particularly in patients with reduced remote flow.
- This method reduces reliance on remote flow assessment, improving detection of both obstructive CAD and microvascular ischemia.
Purpose:
In patients with reduced remote flow, dynamic stress CT perfusion imaging (CTP) has limited utility for detecting obstructive coronary artery disease (CAD). We compared fractal analysis, a descriptor of macro- and microvascular ischemia patterns, with relative myocardial blood flow (MBF) for detecting obstructive CAD stratified by remote flow.
Materials And Methods:
This secondary analysis of the prospective multi-center AMPLIFiED trial included patients who underwent invasive coronary angiography (ICA) with fractional flow reserve (FFR) and dynamic stress CTP. Obstructive CAD was defined invasively (stenosis ≥ 90% or FFR < 0.8). We assessed diagnostic accuracy of fractal analysis and relative MBF in patient groups subdivided into high, intermediate, and low remote flow.
Results:
In 148 patients (30% female; 416 vessels), obstructive CAD was present in 71/148 patients (48%), while signs of microvascular ischemia were found in 26/148 patients (prevalence in high, intermediate, low remote flow: 9%, 37%, 70%). Fractal analysis outperformed relative MBF in detecting obstructive CAD (patient-based sensitivity and specificity: 94% and 92% versus 80% and 64%, p < 0.005). In vessel-based subgroup analysis, both methods performed comparably in high remote flow (area under the receiver-operating curve [AUC]: 0.94 versus 0.88, p = 0.45), while fractal analysis outperformed relative MBF in intermediate and low remote flow (AUC: 0.93 versus 0.77, p = 0.004; 0.92 versus 0.6, p < 0.001).
Conclusion:
Fractal analysis eliminates reliance on remote flow for CTP imaging, which improves diagnostic accuracy for obstructive CAD particularly in patients with reduced remote flow or microvascular ischemia.
Trial Registration:
This study reports about data from the prospective, multi-center AMPLIFiED trial (UMIN000016353).
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