Background: Blood oxygen level-dependent (BOLD) MRI relies on changes in deoxyhaemoglobin level in tissues under stress for signal variation and may be used for detection of ischaemic myocardium. Methods: 15 patients with stress induced myocardial ischaemia on PET scanning underwent rest and dypiridamole stress MRI using a double breath-hold T2*-weighted, ECG gated sequence to produce BOLD contrast images and cine-MRI for wall thickening assessment. Signal change on BOLD MRI and wall thickening were compared between rest and stress images in ischaemic and non-ischaemic myocardial segments. Results: Using PET, 156 segments were identified with reversible ischaemia and 324 as non-ischaemic. The ischaemic segments were found on BOLD MRI to have an average signal change between rest and stress of -16.7% compared to -14% in the non-ischaemic segments (p=0.04). The average wall thickening was 7.8 mm in the ischaemic segments compared with 9.5 mm in the non-ischaemic segments (p < 0.0001). Conclusion: BOLD MRI with wall thickening assessment may differentiate ischaemic from non-ischaemic myocardium in patients with stress induced myocardial ischaemia. Larger studies with improved spatial resolution would help define a threshold for detection of ischaemia as well as determine this technique's sensitivity and specificity. (c) 2006 Elsevier Ireland Ltd. All rights reserved.