Dark blood Late Gadolinium Enhancement improves conspicuity of ablation lesions

Background Cardiac MR has begun to be utilized for imaging ablation lesions. Peri-procedural imaging could potentially be used to guide therapy, but this application has unique requirements and limitations. In peri-procedural imaging of acute lesions, subjects are frequently sedated and imaging should be conducted free-breathing. Furthermore, Late Gadolinium Enhancement (LGE) imaging of sub-endocardial lesions has potentially poor contrast with the adjacent bright blood pool. A dark-blood (DB) LGE sequence has previously been proposed [1], but requires a lengthy pre-scan for timing calibration and necessitates breath-holding. We have developed a freebreathing, DB LGE approach for improved blood pool contrast. DB LGE images are acquired using an IR-T2 preparation [1]. We extend this method to be used with single shot PSIR LGE and incorporate respiratory motion corrected averaging to improve image quality. Furthermore, we introduce a Bloch simulation approach to determining sequence delay times, eliminating the lengthy calibration scan. The proposed method was evaluated as part of a research study of peri-procedural cardiac MR imaging in children undergoing catheter ablation for VT.