Myocardial Flow Reserve Calculator

Global MFR from stress and rest myocardial blood flow, with optional rate-pressure-product rest correction and prognostic thresholds

Evidence ABINF#tool#cardiology#pet#quantitation#perfusion

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Computes global myocardial flow reserve (MFR) — the ratio of stress to rest absolute myocardial blood flow (MBF, mL/g/min) from quantitative cardiac PET (rubidium-82, ¹³N-ammonia, or ¹⁵O-water). Because resting flow rises with cardiac workload, resting MBF is often normalized to the rate-pressure product (RPP = heart rate × systolic BP) before the ratio is taken; that correction is optional here and clearly labeled, since the reference RPP is a lab convention. The thresholds shown are widely used prognostic bands for global MFR, not diagnostic cut-offs for a specific vessel — interpret alongside relative perfusion, the clinical context, and your lab's normal values.

Global myocardial flow reserve (MFR)

Stress MBF

mL/g/min

Rest MBF

mL/g/min

Normalize rest to RPP?

Rest heart rate

bpm

Rest systolic BP

mmHg

Reference RPP (convention)

—

myocardial flow reserve

MFR = stress MBF ÷ rest MBF. Optional normalization: corrected rest MBF = rest × (reference RPP ÷ measured RPP), RPP = heart rate × systolic BP. Prognostic bands for global MFR: ≥2.0 preserved · 1.5–2.0 mildly reduced · <1.5 severely reduced / high risk. These are lab- and tracer-dependent (Rb-82, ¹³N-ammonia, ¹⁵O-water) and are not vessel-specific diagnostic cut-offs — read with relative perfusion, clinical context, and your normal database. Educational estimate only.

Evidence & sources

APrognostic value of coronary flow reserve — Murthy VL, et al. Circulation 2011;124:2215–2224: impaired global CFR independently predicted cardiac mortality (lowest tertile, CFR <1.5, ~5.6× higher cardiac death) across the spectrum of relative perfusion. ↗

BASNC/SNMMI quantitative PET MPI — absolute MBF and MFR methodology; global MFR <2.0 flags impaired flow and <1.5 high risk (tracer- and lab-dependent).

INFRest MBF is workload-dependent — RPP normalization uses a lab-convention reference value, and thresholds vary by lab and tracer; interpret with relative perfusion and clinical context.