# Quantitative coronary flow capacity with low-dose CT for ischemia but no obstructive coronary artery disease

> **NIH NIH R01** · UNIVERSITY OF CALIFORNIA-IRVINE · 2024 · $723,396

## Abstract

Abstract
Ischemic coronary heart disease is the world’s leading cause of mortality and morbidity. Within this complex
disease entity, many patients suffer from myocardial ischemia but are found to have no obstructed coronary
arteries (INOCA). These patients have a high risk of cardiovascular events. Yet current methods for accurately
diagnosing and assessing the physiological effects of INOCA are limited. Catheter-based approaches are
invasive, with added risk, procedural time, and cost. Positron-emission tomography (PET) and cardiac magnetic
resonance (CMR), both noninvasive techniques for clinically assessing INOCA, have limitations such as
claustrophobia (CMR), cost and radiation dose (PET), and local expertise and availability (both). None of these
noninvasive tests accurately yields both anatomical information on the extent of coronary atherosclerosis and its
pathophysiological consequences. We have developed a noninvasive, low-dose dynamic CT perfusion
technique that can accurately measure myocardial perfusion in mL/min/g. This procedure combines patho-
anatomical assessment using CT calcium and CT angiography, as well as pathophysiologic assessment using
CT-derived stress flow (in mL/min/g) and coronary flow reserve (CFR), which are combined to calculate coronary
flow capacity. The current study seeks to test this novel cardiac CT method for assessing patients with INOCA.
Our technique’s accuracy in measuring stress flow and CFR has been validated in preclinical models, and its
preliminary validation, safety, and feasibility shown in patients. We propose to study prospectively its accuracy
for assessing INOCA. The study aims to (1) test the hypothesis that rest flow, stress flow, and CFR measured
by noninvasive dynamic CT perfusion highly correlate with that by invasive measurement in patients with INOCA;
(2) establish a stress flow and CFR reference range determined by noninvasive dynamic CT perfusion that could
be used to set the minimum normal thresholds for stress flow and CFR; and (3) test the hypothesis that
comprehensive cardiac CT can be used to differentiate between patients with and without physiologically
significant coronary artery disease (CAD) in patients with suspected INOCA. Aim 1 will enroll 150 patients with
positive stress test and INOCA. Patients will undergo our comprehensive cardiac CT followed by invasive stress
flow and CFR tests. Aim 2 will enroll 50 patients with negative stress test and measured invasive stress perfusion
greater than 1.21 mL/min/g and CFR > 2.0 to establish the normative range of CT-based stress flow and CFR.
Aim 3 will discriminate between patients with and without physiologically significant CAD with dynamic CT
perfusion, using invasive stress perfusion and CFR as the reference standard. The study’s successful completion
invasive tool that allows comprehensive concurrent evaluation of coronary anatomyand physiology in
symptomatic patients with INOCA.

## Key facts

- **NIH application ID:** 10873256
- **Project number:** 5R01HL170149-02
- **Recipient organization:** UNIVERSITY OF CALIFORNIA-IRVINE
- **Principal Investigator:** SABEE MOLLOI
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $723,396
- **Award type:** 5
- **Project period:** 2023-07-01 → 2028-04-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10873256

## Citation

> US National Institutes of Health, RePORTER application 10873256, Quantitative coronary flow capacity with low-dose CT for ischemia but no obstructive coronary artery disease (5R01HL170149-02). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10873256. Licensed CC0.

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