Authors: Roberto Sciagrà Alessandro Passeri Fabrizio Cipollini Helga Castagnoli Iacopo Olivotto Cyrill Burger Franco Cecchi Alberto Pupi
Publish Date: 2015/06/27
Volume: 42, Issue: 10, Pages: 1581-1588
Abstract
Transmural abnormalities in myocardial blood flow MBF are important causes of ischaemia in patients with left ventricular LV hypertrophy The study aimed to test whether pixelwise parametric mapping of 13NH3 MBF can reveal transmural abnormalities in patients with hypertrophic cardiomyopathy HCMWe submitted 11 HCM patients and 9 agematched controls with physiological LV hypertrophy to rest and stress dipyridamole 13NH3 PET We measured MBF using a compartmental model and obtained rest and stress parametric maps Pixel MBF values were reorganized to obtain subendocardial and subepicardial MBF of LV segmentsMBF at rest was higher in the subendocardial than in the subepicardial layer 078 ± 019 vs 060 ± 018 mL/min/g in HCM patients 092 ± 024 vs 075 ± 024 mL/min/g in controls both p 00001 Transmural perfusion gradient TPG = subendocardial MBF/subepicardial MBF at rest was similar 135 ± 031 in HCM patients 128 ± 027 in controls NS During stress controls maintained higher subendocardial MBF 244 ± 054 vs 196 ± 067 mL/min/g tissue p 00001 with a TPG of 133 ± 035 NS vs rest In HCM patients the difference between subendocardial and subepicardial MBF was reduced 146 ± 048 vs 136 ± 048 mL/min/g tissue p 001 and TPG decreased to 111 ± 034 p 00001 vs rest and vs controls In HCM patients 8 of 176 segments had subendocardial MBF less than −2 × SD of the mean versus none of 144 segments in controls p 001All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standardsThe data analysis methodology then consists of the following two steps As a preprocessing step the basis functions are calculated for a set of k 2 values which span the physiologically relevant range In each pixel the TAC is fitted by solving the operational equation for all basis functions and selecting the solution that best fits the measurement From the resulting parameters θ 1 V LV and V RV the MBF = K 1 can readily be calculated If the blood contribution in a pixel is too high V LV + V RV 075 the MBF result is discarded
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