PYP Quantitative Uptake Index (QUI) Calculator

PYP Quantitative Uptake Index (QUI): Explanation and Clinical Context The PYP Quantitative Uptake Index (QUI) is a ratio of the radiotracer counts measured in the myocardial region of interest (ROI) to the contralateral chest ROI during 99mTc-Pyrophosphate (PYP) scintigraphy. It is used to quantify myocardial uptake and improve the diagnostic accuracy for transthyretin cardiac amyloidosis (ATTR-CA). A higher QUI value indicates more significant myocardial radiotracer accumulation.

Typically, a QUI >1.5 is suggestive of clinically relevant myocardial amyloid deposition. This index provides a reproducible, objective metric that can supplement visual scoring (Perugini grading) in clinical practice, enabling better risk stratification, disease monitoring, and follow-up of patients with suspected ATTR-CA.