Introduction

In clinical practice CMR at 3.0T with its increase SNR is a valuable tool for the detection of myocardial scar and potential substrate prior to a planned VT ablation [1]. The development of MRI-conditional ICDs for 3.0T offer this potential of CMR for patients with ICDs but at the same time draws the attention to the image quality due to the increased artifact burden [2-4]. At 1.5T, imaging strategies for artifact reduction in the presence of ICD, e.g. wideband (WB) LGE, have been evaluated [5]. However, at 3.0T the implementation of such techniques for application in humans is lacking. This work presents the first human in vivo experiences with a modified cardiac imaging protocol including wideband LGE for patients with implanted active implants at 3.0T.

Methods

All measurements were performed on a clinical 3T MRI scanner with commercial anterior and posterior body surface coils for signal reception (AchievaDS, dStream Whole body, Philips Healthcare). Phantom measurements with an in-house built cubic phantom and representative ICDs (Ilesto 7 HF-T; Activor 7 HF-T QP, Biotronik) were used to determine the optimal sequence settings for the wideband inversion pulse. 7 healthy volunteers and 4 patients scheduled for an CMR with LGE were examined with an ICD taped externally to their upper left chest. 3 male patients with an ICD (two in the left upper (Rivacor 5VR-T, Iforia 7VR-T), one in the right upper pectoral region (Rivacor 5D-RT)) were examined using the previously established sequences.

Results

Compared to bSSFP Cine imaging, using a spoiled TFE sequence without flow compensation and partial echo allows the suppression of artifacts caused by the ICD. In cases with no visual artifacts within the cardiac region, the bSSFP CINE imaging retains its applicability. The image quality for this sequence improves after application of contrast agent (Fig.1).The best results for scar imaging are achieved with WB-PSIR-LGE at a bandwidth (BW) of 3 kHz and an offset of +750 Hz (Fig. 2). This setting eliminated hyperintense frequency offset artifacts in the myocardium and allowed a clear delineation of scar and fibrosis areas (Fig.1).

Discussion/Conclusion

In Patients with ICDs, the modified imaging protocol with TFE-CINE imaging, ideally run after application of contrast agent for improved myocardium-blood contrast, allows the clinical analysis of wall motion and volumetry. The modified protocol for scar detection with a WB-PSIR-LGE at a bandwidth of 3kHz and an offset of 750 Hz allows a reasonable compromise between homogeneous signal intensities and remaining artifact burden.

References

[1] Mukherjee RK et al. Europace. 2018;20(11):1721-32.

[2] Sommer T et al. Rofo. 2017;189(3):204-17

[3] Mesubi O et al. Pacing Clin Electrophysiol. 2014;37(10):1274-83.

[4] Reiter T et al. Sci Rep. 2022;12(1):6285.

[5] Hilbert S et al. Europace (2018) 20, 801–807

Fig. 1: bSSFP (a), TFE pre- (b) and TFE post-contrast (c) CINE imaging in a patient with ICD.

Fig 2. WB-PSIR-LGE in a patient with an externally taped ICD. The artifact is smaller with A) BW 3kHz, Offset 750 Hz than with B) BW 2kHz, Offset 750 Hz. In both scans the small scar (arrow) on the inferior wall remains visible.

Fig. 3: Patient with ICD. a) LGE, 2CH-view. The anterior wall is covered by an hyperintensiv artifact b) WB-PSIR-LGE suppresses this artifact. c) LGE, 4CH and d) WB-PSIR LGE show comparable image quality. Arrow: myocardial scar. Asterisk: lead artifact. 0: device artifact.