Caitlin Vink

148 Chapter 7 Localisers Cine (LAX) StressAIF Stress perfusion Cine (SAX) Rest AIF Rest perfusion 2D LGE 3 minutes 10 minutes Start i.v. adenosine 140 μg/kg/min 1st pre-bolus of contrast 0.0075 mmol/kg Stopi.v. adenosine 140 μg/kg/min 1st main bolus of contrast 0.075 mmol/kg 2nd pre-bolus of contrast 0.0075 mmol/kg 2nd main bolus of contrast 0.075 mmol/kg 1 3 5 7 2 4 6 8 Figure 1. Proposed adenosine stress perfusion dual-bolus CMR scanning protocol Abbreviations: AIF: arterial input function. CMR image post-processing and analysis QP CMR analysis was performed using cvi42 software (prototype version 5.13.8.2774, Circle Cardiovascular Imaging Inc., Calgary, Canada) equipped with a newly updated, fully automated pixel-wise QP module, described in detail elsewhere.19 Briefly, the module automatically corrected in-plane respiratory motion of the heart and the surface coilinduced signal inhomogeneities using the proton density images.26,29 Next, the AIF and myocardial ROIs were detected to derive time-SI curves and identify key time points during first-pass contrast enhancement.28 The basis for MBF quantification was based on the central volume principle described by Zierler for indicator-dilution experiments, where the SI observed in the myocardium at each pixel is modeled as the convolution of the AIF and a residual function, for which its amplitude is the scalar MBF value. The MBF at each pixel can thus be derived through a reverse process of deconvolution of a pixel’s myocardium SI curves and the AIF curve.3,12,19,30 Inappropriate automatic delineation of myocardial of AIF ROIs was corrected by the operator and care was taken to prevent inclusion of blood pool into myocardial ROIs. Assessment of image quality and diagnostic accuracy First, blinded to ICA and FFR results, the two independent CMR level 3 experts (M.G. > 10 years of experience, A.D. > 6 years of experience) were asked to allocate each case to the obstructive or no obstructive CAD group based on the QP CMR and LGE images.

RkJQdWJsaXNoZXIy MTk4NDMw