The effects of flip angle and gadolinium contrast agent on single breath-hold compressed sensing cardiac magnetic resonance cine for biventricular global strain assessment

Abstract

Background: Due to its potential to significantly reduce scanning time while delivering accurate results for cardiac volume function, compressed sensing (CS) has gained traction in cardiovascular magnetic resonance (CMR) cine. However, further investigation is necessary to explore its feasibility and impact on myocardial strain results.

Materials and methods: A total of 102 participants [75 men, 46.5 ± 17.1 (SD) years] were included in this study. Each patient underwent four consecutive cine sequences with the same slice localization, including the reference multi-breath-hold balanced steady-state free precession (bSSFP_ref) cine, the CS cine with the same flip angle as bSSFP_ref before (CS₄₅) and after (eCS₄₅) contrast enhancement, and the CS cine (eCS₇₀₎ with a 70-degree flip angle after contrast enhancement. Biventricular strain parameters were derived from cine images. Two-tailed paired t-tests were used for data analysis.

Results: Global radial strain (GRS), global circumferential strain (GCS), and global longitudinal strain (GLS) were observed to be significantly lower in comparison to those obtained from bSSFP_ref sequences for both the right and left ventricles (all p < 0.001). No significant difference was observed on biventricular GRS-LAX (long-axis) and GLS values derived from enhanced and unenhanced CS cine sequences with the same flip angle, but remarkable reductions were noted in GRS-SAX (short-axis) and GCS values (p < 0.001). After contrast injection, a larger flip angle caused a significant elevation in left ventricular strain results (p < 0.001) but did not affect the right ventricle. The increase in flip angle appeared to compensate for contrast agent affection on left ventricular GRS-SAX, GCS values, and right ventricular GRS-LAX, GLS values.

Conclusion: Despite incorporating gadolinium contrast agents and applying larger flip angles, single breath-hold CS cine sequences consistently yielded diminished strain values for both ventricles when compared with conventional cine sequences. Prior to employing this single breath-hold CS cine sequence to refine the clinical CMR examination procedure, it is crucial to consider its impact on myocardial strain results.

Keywords: cardiovascular magnetic resonance; cine; compressed sensing; feature tracking; strain.

Figure 1

Enrollment flowchart of the participants. CS, compressed sensing.

Figure 2

CMR scanning procedure. CS, compressed sensing; bSSFP, balanced free steady state precession.

Figure 3

Strain analysis was performed using feature tracking on a stack of short-axis views. The global circumferential strain (GCS, %) graph of the left ventricular (slice 4) showed distinct results among the different cine sequences: referenced bSSFP_ref cine displayed the highest GCS peak value (−21.1), while eCS₄₅ cine exhibited the lowest value (−10.5). CS₄₅ and eCS₇₀ cine sequences displayed almost identical GCS values. CS, compressed sensing; bSSFP, balanced steady-state free precession.

Figure 4

A set of box plots is used to summarize the strain results for the conventional bSSFP_ref cine and three CS cine (CS₄₅, eCS₄₅, eCS₇₀) sequences. Non-significant comparisons between each pair of cine sequences are denoted as “ns”. LV, left ventricle; RV, right ventricle; GRS-SAX, global radial strain measured on short-axis slices; GRS-LAX, global radial strain measured on long-axis slices; GCS, global circumferential strain; GLS, global longitudinal strain; CS, compressed sensing; bSSFP, balanced free steady state precession. The symbol “+” denotes the mean value.