Perfusion cardiovascular magnetic resonance: Comparison of an advanced, high-resolution and a standard sequence

Background: Technical advances in perfusion cardiovascular magnetic resonance (CMR), particularly accelerated data acquisition methods, allow myocardial perfusion imaging with unprecedented spatial resolution. However, it is not clear how implementation of these recent advances affects perfusion image quality, signal and contrast to noise ratios (SNR & CNR) and the occurrence of important artefacts in routine clinical imaging. The objective of this study was therefore to compare a standard and an advanced, high-resolution perfusion sequence.

Methods: A standard ultrafast gradient echo perfusion sequence (st-GrE) was compared with an advanced kt-accelerated steady state free precession sequence (kt(BLAST)-SSFP) at 1.5 T in healthy volunteers (n = 16) and in patients (n = 32) with known or suspected coronary artery disease. Volunteers were imaged with both sequences at rest and patients underwent stress and rest imaging with either st-GrE or kt(BLAST)-SSFP prior to X-ray coronary angiography. A blinded expert scored image quality and respiratory artefact severity and also classified patients for the presence of CAD. The extent, transmurality and duration of dark rim artefacts (DRA) as well as signal to noise (SNR) and contrast to noise (CNR) were quantified.

Results: In normal hearts kt(BLAST)-SSFP imaging resulted in significantly improved image quality (p = 0.003), SNR (21.0 +/- 6.7 vs. 18.8 +/- 6.6; p = 0.009), CNR (15.4 +/- 6.1 vs. 14.0 +/- 6.0; p = 0.034) and a reduced extent (p = < 0.0001) and transmurality (p = 0.0001) of DRA. In patients kt(BLAST)-SSFP imaging resulted in significantly improved image quality (p = 0.012), and a reduced extent (p = < 0.0001), duration (p = 0.004) and transmurality (p = < 0.0001) of DRA. Sensitivity and specificity for the detection of CAD against X-ray angiography was comparable with both sequences. There was a non-significant trend towards increased respiratory artefacts with kt(BLAST)-SSFP in both patients and volunteers.

Conclusions: Advanced high resolution perfusion CMR using a k-t-accelerated SSFP technique results in significantly improved image quality, SNR and CNR and a reduction in the extent and transmurality of DRA compared to a standard sequence. These findings support the use of advanced perfusion sequences for clinical perfusion imaging however further studies exploring whether this results in improved diagnostic accuracy are required.