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Abstract
Introduction Functional assessment of cardiac ventricles is an essential aspect of cardiac magnetic resonance. Traditionally, cine images are acquired in the short axis orientation with multiple slices through the ventricles. In this study, we propose to evaluate a 3D cine whole heart balanced steady-state free-precession (SSFP) sequence, which allows ventricular volume assessment in a single breath hold without compromising the accuracy of volumetric analysis. This was achieved using a 32-channel cardiac coil with increased SENSE factors. The loss of myocardial blood pool contrast due to the 3D acquisition is overcome by the administration of a Gd-DTPA contrast agent Magnevist.
3DC, 3D postcontrast; 3DNC, 3D precontrast.
LV-EDV, left ventricular end-diastolic volume; LV-ESV, left ventricular end-systolic volume; LV-SV, left ventricular stroke volume; MRI, magnetic resonance imaging; RV-EDV, right ventricular end-diastolic volume; RV-ESV, right ventricular end-systolic volume; RV-SV, right ventricular stroke volume.
Method 15 patients attending for routine cardiac magnetic resonance imaging were prospectively recruited and scanned using 1.5T MR-scanner (Philips Achieva) with an Invivo 32-channel cardiac coil. All patients underwent standard M2D cine SSFP sequence with multi breath holds for volumetric and functional ventricular assessment. In addition, in each patient a single breath hold 3D cine b-SSFP sequence pre and postadministration of Gd-DTPA was performed. The 3D cine b-SSFP acquisition was accelerated using SENSE in both phase encoding directions. Two independent observers drew endocardial borders manually for the three datasets. Consecutively, end-diastolic volumes (EDV), end-systolic volume (ESV) were calculated, from which the stroke volume and ejection fraction were derived. Bland–Altman analyses were performed to compare parameters from the three groups, M2D, 3D postcontrast (3DC) and 3D precontrast (3DNC). Furthermore, the mean contrast between blood pool and myocardium was calculated for all scans.
Results Data were successfully acquired in all patients. Statistical analysis showed no significant difference for measured left and right ventricular EDV and ESV between the M2D and 3DC. However, Bland–Altman plots showed greater bias and standard deviation when comparing the M2D with 3D images without contrast (3DNC). This was due to less contrast between blood pool and myocardium: M2D 14.66 ± 3.57, 3DC 13.94 ± 5.71, 3DNC 9.18 ± 2.85 and subsequently poorer delineation of endocardial borders. Inter and intraobserver variability show good reproducibility for these techniques (figs 1–2).
Conclusion 3D cine b-SSFP imaging of the cardiac ventricles using a 32-channel cardiac coil results in a single breath hold sequence to assess both ventricle volumes. The 4 × 4 coil configuration allows the utilisation of SENSE in two directions while maintaining good temporal and spatial resolution. Although contrast between blood pool and myocardium is reduced with large SSFP volumes this was significantly improved following the administration of contrast agent and results in better delineation of ventricular endocardial borders. This type of scanning offers a considerable temporal advantage over traditional multi-slice sequences and could prove to be particularly advantageous in less cooperative patients or in stress studies requiring shorter acquisition times.