Effect of slice acquisition direction on image quality in thoracic MRI

We tested the basic observation that imaging the heart and pericardium in systole improves image quality compared with that in diastole.

Twenty consecutive patients and two volunteers underwent sequential ECG-gated short TE transaxial prospective multislice SE MRI with both caudocranially and craniocaudally directed slice prescriptions, keeping other imaging parameters constant. Images of the heart and pericardium were obtained in systole and diastole and examined by three independent reviewers for image quality.

In the lower mediastinum, cardiac structures and the pericardium were better seen in 49 of 57 individual evaluations when imaged in systole, 15 of which were judged markedly better. Vascular structures and the pericardium in the upper mediastinum were imaged equally well with both prescriptions.

The findings suggest that in systole, the more mobile heart can maintain a more consistent shape during the acquisition of successive phase-encoding steps and preserve luminal flow void, factors critical to optimizing image quality in the transaxial plane.