Quality assessment of cardiovascular magnetic resonance in the setting of the European CMR registry: description and validation of standardized criteria

Background: Cardiovascular magnetic resonance (CMR) has become an
important diagnostic imaging modality in cardiovascular medicine.
However, insufficient image quality may compromise its diagnostic
accuracy. We aimed to describe and validate standardized criteria
to evaluate a) cine steady-state free precession (SSFP), b) late
gadolinium enhancement (LGE), and c) stress first-pass perfusion
images. These criteria will serve for quality assessment in the
setting of the Euro-CMR registry. Methods: Thirty-five qualitative
criteria were defined (scores 0-3) with lower scores indicating
better image quality. In addition, quantitative parameters were
measured yielding 2 additional quality criteria, i.e.
signal-to-noise ratio (SNR) of non-infarcted myocardium (as a
measure of correct signal nulling of healthy myocardium) for LGE
and \% signal increase during contrast medium first-pass for
perfusion images. These qualitative and quantitative criteria were
assessed in a total of 90 patients (60 patients scanned at our own
institution at 1.5T (n=30) and 3T (n=30) and in 30 patients
randomly chosen from the Euro-CMR registry examined at 1.5T).
Analyses were performed by 2 SCMR level-3 experts, 1 trained study
nurse, and 1 trained medical student. Results: The global quality
score was 6.7 +/- 4.6 (n=90, mean of 4 observers, maximum possible
score 64), range 6.4-6.9 (p=0.76 between observers). It ranged from
4.0-4.3 for 1.5T (p=0.96 between observers), from 5.9-6.9 for 3T
(p=0.33 between observers), and from 8.6-10.3 for the Euro-CMR
cases (p=0.40 between observers). The inter- (n=4) and
intra-observer (n=2) agreement for the global quality score, i.e.
the percentage of assignments to the same quality tertile ranged
from 80\% to 88\% and from 90\% to 98\%, respectively. The
agreement for the quantitative assessment for LGE images (scores
0-2 for SNR 5, respectively) ranged from 78-84\%
for the entire population, and 70-93\% at 1.5T, 64-88\% at 3T, and
72-90\% for the Euro-CMR cases. The agreement for perfusion images
(scores 0-2 for \% SI increase >200\%, 100\%-200\%,