Detection of scarred and viable myocardium using a new magnetic resonance imaging technique: blood oxygen level dependent (BOLD) MRI

Abstract

Background: The identification of viable myocardium in patients with impaired left ventricular contraction secondary to coronary heart disease is important clinically as such myocardium is likely to benefit from revascularisation. Blood oxygen level dependent (BOLD) magnetic resonance imaging (MRI) relies on changes in deoxyhaemoglobin concentration under stress for signal generation and could be used for the differentiation between scarred and viable myocardium. Aim: To assess the signal change on BOLD MRI in viable and scarred myocardium as identified by positron emission tomography (PET). Method: 19 patients with impaired left ventricular contraction and at least one akinetic area were enrolled. They underwent rest and dipyridamole stress MRI, using a double breath hold T2* weighted, ECG gated sequence to produce BOLD contrast images, and cine-MRI for wall thickening assessment. Dynamic perfusion and metabolic PET images followed the MRI. Signal change on BOLD MRI and the wall thickening were compared between rest and stress images in hibernating and scarred segments identified by PET on two short axis slices of mid ventricle, with eight segments each. Results: Using PET, 68 segments were identified as hibernating and 42 as scarred. The hibernating segments were found on BOLD MRI to have an average signal change between rest and stress of −9.53%, compared with −2.15% in the scarred segments (p = 0.008). The average wall thickening was 8.7 mm in the hibernating segments compared with 5.9 mm in the scarred segments (p < 0.0001). Conclusions: BOLD MRI with wall thickening may differentiate scarred and viable myocardium and help identify suitable patients for revascularisation. Further larger studies are needed to establish a threshold for detection, sensitivity, and specificity.

Long-term stability of cardiac function in normal and chronically failing mouse hearts in a vertical-bore MR system

“…Studies in humans [15][16][17] and in larger animals [18], and preliminary experiments in mice [19], indicate that MR also allows analysis of cardiac perfusion (arterial spin labeling), oxygenation (BOLD effect), Na content and energy metabolism (MR spectroscopy). Clearly, for many research groups working in this area, establishment of these more demanding techniques will be the next phase of MR development for phenotype characterisation in mice.…”

Three-dimensional contrast-enhanced and non-contrast-enhanced cardiac magnetic resonance imaging for the assessment of myocardial ischemic reactions

“…A direct comparison of metabolic fluorine-18 labeled fluorodeoxyglucose (FDG) PET and BOLD CMR imaging in chronic CAD patients with impaired leftventricular function suggested that BOLD imaging at rest and during vasodilator stress has the potential to differentiate chronically infarcted and viable myocardial segments: myocardial segments being classified as viable due to the presence of a perfusion/metabolism mismatch on PET scans showed a BOLD signal intensity decrease of 10% from rest to stress while infarcted myocardial segments were characterized by a minimal (\2%) or missing decrease of BOLD signal intensities. 52 Consequently, BOLD CMR imaging may play a role in future CMR protocols to assist in identification of patients who are likely to benefit from coronary revascularization.…”

Future prospects in magnetic resonance imaging

“…The ability to duplicate the sensitivity and specificity of positron emission tomography (PET) is a monumental advance, especially considering the scarcity of PET sites and its prohibitive costs [19]. CMR signal intensity is also sensitive to the blood oxygenation levels of myocardium, and studies have demonstrated good correlations with PET discrimination of scarred and viable myocardium [20].…”