Image quality and myocardial scar size determined with magnetic resonance imaging in patients with permanent atrial fibrillation: a comparison of two imaging protocols.

BACKGROUND

Magnetic resonance imaging (MRI) of the heart generally requires breath holding and a regular rhythm. Single shot 2D steady-state free precession (SS_SSFP) is a fast sequence insensitive to arrhythmia as well as breath holding. Our purpose was to determine image quality, signal-to-noise (SNR) and contrast-to-noise (CNR) ratios and infarct size with a fast single shot and a standard segmented MRI sequence in patients with permanent atrial fibrillation and chronic myocardial infarction.

METHODS

Twenty patients with chronic myocardial infarction and ongoing atrial fibrillation were examined with inversion recovery SS_SSFP and segmented inversion recovery 2D fast gradient echo (IR_FGRE). Image quality was assessed in four categories: delineation of infarcted and non-infarcted myocardium, occurrence of artefacts and overall image quality. SNR and CNR were calculated. Myocardial volume (ml) and infarct size, expressed as volume (ml) and extent (%), were calculated, and the methodological error was assessed.

RESULTS

SS_SSFP had significantly better quality scores in all categories (P = 0.037, P = 0.014, P = 0.021, P = 0.03). SNR(infarct) and SNR(blood) were significantly better for IR_FGRE than for SS_SSFP (P = 0.048, P = 0.018). No significant difference was found in SNR(myocardium) and CNR. The myocardial volume was significantly larger with SS_SSFP (170.7 versus 159.2 ml, P<0.001), but no significant difference was found in infarct volume and infarct extent.

CONCLUSION

SS_SSFP displayed significantly better image quality than IR_FGRE. The infarct size and the error in its determination were equal for both sequences, and the examination time was shorter with SS_SSFP.