Accuracy, Precision, and Reproducibility of Four T1 Mapping Sequences: A Head-to-Head Comparison of MOLLI, ShMOLLI, SASHA, and SAPPHIRE

Abstract

To compare accuracy, precision, and reproducibility of four commonly used myocardial T1 mapping sequences: modified Look-Locker inversion recovery (MOLLI), shortened MOLLI (ShMOLLI), saturation recovery single-shot acquisition (SASHA), and saturation pulse prepared heart rate independent inversion recovery (SAPPHIRE). Materials andMethods:This HIPAA-compliant study was approved by the institutional review board. All subjects provided written informed consent. Accuracy, precision, and reproducibility of the four T1 mapping sequences were first compared in phantom experiments. In vivo analysis was performed in seven healthy subjects (mean age 6 standard deviation, 38 years 6 19; four men, three women) who were imaged twice on two separate days. In vivo reproducibility of native T1 mapping and extracellular volume (ECV) were measured. Differences between the sequences were assessed by using Kruskal-Wallis and Wilcoxon rank sum tests (phantom data) and mixed-effect models (in vivo data). Results:T1 mapping accuracy in phantoms was lower with ShMOLLI (62 msec) and MOLLI (44 msec) than with SASHA (13 msec; P , .05) and SAPPHIRE (12 msec; P , .05). MOLLI had similar precision to ShMOLLI (4.0 msec vs 5.6 msec; P = .07) but higher precision than SAPPHIRE (6.8 msec; P = .002) and SASHA (8.7 msec; P , .001). All sequences had similar reproducibility in phantoms (P = .1). The four sequences had similar in vivo reproducibility for native T1 mapping (~25-50 msec; P . .05) and ECV quantification (~0.01-0.02; P . .05). Conclusion:SASHA and SAPPHIRE yield higher accuracy, lower precision, and similar reproducibility compared with MOLLI and ShMOLLI for T1 measurement. Different sequences yield different ECV values; however, all sequences have similar reproducibility for ECV quantification.q RSNA, 2014

T1 Mapping in Characterizing Myocardial Disease

“…123,124 The most recently introduced approach is a combined IR-SR preparation scheme (Saturation pulse prepared heart rate-independent inversion recovery, SAPPHIRE). 125 In T1 or longitudinal magnetization, the magnitude is measured as a vector component in z direction (head-feet), whereas in T2 (discussed later), the vector component is measured in transverse or x-y plane. T1 accuracy of a sequence is defined by proximity/distance of a sequence-specific T1 value (T1 estimate) from the true T1 value, obtained by T1-TSE sequence.…”

Myocardial Fibrosis in Congenital Heart Disease

“…A technical review of the strengths and weaknesses of these techniques can be found elsewhere. 20 The Look-Locker technique and its modifications have higher reproducibility and precision, whereas SASHA and SAPPHIRE have improved accuracy. 20 In most of the published studies in CHD either the Look-Locker or MOLLI approach has been used.…”

“…20 The Look-Locker technique and its modifications have higher reproducibility and precision, whereas SASHA and SAPPHIRE have improved accuracy. 20 In most of the published studies in CHD either the Look-Locker or MOLLI approach has been used. 21-24 Native T1 time refers to the T1 relaxation time without the administration of a gadolinium-based contrast agent.…”

Myocardial T1 Mapping in Pediatric and Congenital Heart Disease

“…26 A recent comparison of the 4 most widely applied T1 mapping sequences demonstrated superior precision (ie, reproducibility) for the inversion recovery sequences MOLLI 20 and ShMOLLI, 22 while SASHA 24 and SAPPHIRE 26 were more accurate (ie, closer to the true T1). 27 The accuracy of the MOLLI sequence for postcontrast T1 times can be improved by using a different acquisition scheme which accounts for shorter T1 times. This scheme ensures that the majority of data points are positioned into the shortened upslope of the longitudinal relaxation curves of blood and myocardium.…”