Myocardial Perfusion MR-Imaging at 3 Tesla

Purpose: Myocardial perfusion imaging is increasingly used for the detection of myocardial ischaemia. It enables an assessment of the hemodynamic relevance of coronary artery stenoses. Here, high field perfusion imaging at 3.0T should contribute increased SNR and CNR compared to 1.5T. Due to technical and physical reasons, sequence techniques which perform well at 1.5T may not be implemented for 3.0T without prior modifications. Aim of the study was to investigate the feasibility of myocardial perfusion imaging at 3.0T.

Material and Methods: 16 patients with a history of coronary artery disease were examined at 3.0T (Magnetom Trio, Siemens, Erlangen, Germany). Cine trueFISP sequences (TR 3.4, TE 1.7, flip 50°) were acquired in four chamber view (FCV), two chamber view (TCV) and short axis views (SAV) for assessment of myocardial function. For perfusion imaging, a turbo FLASH 2D sequence (TR 1.9, TE 1.0, flip 12°, matrix 115×192) with 0.05 mmol Gd-DTPA per kg body weight (bw) was performed at rest and at stress after injection of 140µg adenosine/ kg bw/ minute. 3–5 representative slices were acquired in SAV depending on the heart rate of the patient. Delayed enhancement imaging (inversion recovery prepared turbo FLASH, TR 9.9, TE 4.9, flip 30°, matrix 154×256) 15 minutes after contrast injection contributed assessment of myocardial viability. Perfusion analysis was based on least square fit of the signal/time curve (peak signal intensity, slope, area under the curve). Two observers assessed perfusion imaging in a consensus reading and rated image quality on a four point scale (0=poor, 3=excellent). MR perfusion data was compared to coronary catheter angiography (CCA).

Results: All MR examinations yielded high image quality (score 2.7±0.3). In 9 patients, a stress induced perfusion deficit was detected correlating with high grade coronary artery stenoses (>80%) in CCA. Four patients had a perfusion deficit at rest correlating with myocardial infarction in delayed enhancement imaging. In four patients, no perfusion deficit was found (CA stenosis<80%). Delayed enhancement images revealed myocardial infarction in 8 patients.

Conclusion: Our results using myocardial perfusion imaging at 3.0T are already very promising. Cardiac imaging at 3.0T provides high image quality in perfusion imaging and in delayed enhancement imaging enabling an accurate detection of myocardial perfusion deficits.