Abstract
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Objectives New 18F-labeled myocardial blood flow (MBF) agents are becoming available but the ~ 2 hour half-life of 18F complicates clinical application for rest/stress measurements. The goal of this work is to develop and validate a method for quantitative measurement of absolute flow during a single scan rest/stress cardiac imaging session.
Methods Single-scan rest/stress measurements were made using [18F]flurpiridaz (1). Six pigs were imaged in a Siemens Biograph PET/CT scanner before and again after infarction of the left anterior descending artery (LAD) territory. A two-injection, single-scan protocol was used (2). Adenosine was started 4 minutes after the first injection of [18F]flurpiridaz followed 6 minutes later by a second radiotracer injection. Microsphere flow measurements were made at rest and peak-stress. Dynamic images were reconstructed with filtered back projection (FBP), reoriented into the short axis view, and regions of interest (ROIs) for the left ventricle (LV) chamber and 17 myocardial segments were defined in bullseye fashion (3). PET data were fitted with the kinetic model MGH2 (2), in which flow changes abruptly with the introduction of adenosine. Rest and stress MBF were estimated simultaneously with corrections for spillover.
Results The first 14 minutes of rest/stress PET data were fitted in detail by the MGH2 model, yielding flow estimates having precision better than 10% coefficient of variation. MBF across pigs was found to be 0.62 ± 0.02 mL/min/cc at rest and 1.06 ± 0.07 mL/min/cc at stress in healthy tissue and 0.52 ± 0.08 mL/min/cc at rest and 0.62 ± 0.08 mL/min/cc at stress in infarcted area. Good agreement was found with microsphere measurement.
Conclusions Accurate rest and stress MBF estimation can be obtained in less than 15 min of PET acquisition with the proposed method. This protocol yields quantitative results similar to those published using the same tracer with injections separated by 1 hour and subtraction of residual activity (4).
Research Support R01HL110241