Myocardial T1 mapping at 3.0 tesla using an inversion recovery spoiled gradient echo readout and bloch equation simulation with slice profile correction (BLESSPC) T1 estimation algorithm

Abstract

Purpose To develop an accurate and precise myocardial T1 mapping technique using an inversion recovery spoiled gradient echo readout at 3.0T. Materials and Methods The modified Look-Locker inversion-recovery (MOLLI) sequence was modified to use fast low angle shot (FLASH) readout, incorporating a BLESSPC (Bloch Equation Simulation with Slice Profile Correction) T1 estimation algorithm, for accurate myocardial T1 mapping. The FLASH-MOLLI with BLESSPC fitting was compared to different approaches and sequences with regards to T1 estimation accuracy, precision and image artifact based on simulation, phantom studies, and in vivo studies of 10 healthy volunteers and 3 patients at 3.0T. Results The FLASH-MOLLI with BLESSPC fitting yields accurate T1 estimation (average error = −5.4±15.1 ms, percentage error = −0.5%±1.2%) for T1 from 236–1852 ms and heart rate from 40–100 bpm in phantom studies. The FLASH-MOLLI sequence prevented off-resonance artifacts in all 10 healthy volunteers at 3.0T. In vivo, there was no significant difference between FLASH-MOLLI-derived myocardial T1 values and “ShMOLLI+IE” derived values (1458.9±20.9 ms vs. 1464.1±6.8 ms, p=0.50); However, the average precision by FLASH-MOLLI was significantly better than that generated by “ShMOLLI+IE” (1.84±0.36% variance vs. 3.57±0.94%, p<0.001). Conclusion The FLASH-MOLLI with BLESSPC fitting yields accurate and precise T1 estimation, and eliminates banding artifacts associated with bSSFP at 3.0T.

Accuracy, precision, and reproducibility of myocardial T1 mapping: A comparison of four T1 estimation algorithms for modified look‐locker inversion recovery (MOLLI)

“…A similar reduction of inversion factor in vivo has been found in previous studies . The greatly reduced inversion factor in vivo was not due to the body size of the volunteer, as the in vivo inversion factor had a very narrow range of 0.87–0.89 despite the wide range of body weight of the subjects (50–102 kg).…”

FASt single‐breathhold 2D multislice myocardial T1 mapping (FAST1) at 1.5T for full left ventricular coverage in three breathholds

“…Due to the longer native myocardial T 1 times at 3T, a longer T RD may be necessary to achieve nearly full recovery of the longitudinal magnetization. The combination of FAST1 with a gradient recalled echo (GRE) readout could also be beneficial to reduce off‐resonance artifacts at higher fields …”

“…First, the approximation of the slice profile was approximated by one flip angle only. More advanced modeling could be considered in future work to better represent the nonlinear signal response to the flip angle . Second, postcontrast myocardial T 1 mapping using FAST1 was not characterized in healthy volunteers.…”

A novel profile/view ordering with a non-convex star shutter for high-resolution 3D volumetric T1 mapping under multiple breath-holds

“…To minimize TR and subsequently acquire as many k‐space lines during the acquisition window as possible, a Shinnar‐Le Roux optimized short 0.5‐ms RF excitation pulse was used during acquisition, whose spatial selectivity corresponds approximately to a Gaussian profile with additional side lobes as shown in the http://onlinelibrary.wiley.com/store/10.1002/mrm.26303/asset/supinfo/mrm26303-sup-0001-suppfig1.mp4?v=1&s=755f108bc7f3aaa4b46c417bf36798463a56c8db. Unlike the 2D acquisition, which superimposes all slab excitation imperfections from the Gaussian‐like profile into a single slice , the 3D approach can encode the slab‐direction variation into different slices. Therefore, the regions near the middle of the excited slab would yield higher signal, which drops slightly in the trophs between the side lobes, and the edge slices suffered from more noticeable SNR loss, which also affects the T 1 map calculation.…”

“…The scope of this initial feasibility study was therefore constrained to simple and direct comparison of the clinically diagnostic T 1 AHA segment analysis against the 2D state‐of‐the‐art reference. Nonetheless, we additionally gained insights regarding the contribution of RF excitation slab to the underestimation of myocardial T 1 for 2D versus 3D‐MOLLI , while other contributing factors such as T 2 and heart rate were kept invariant.…”