Pooled summary of native T1 value and extracellular volume with MOLLI variant sequences in normal subjects and patients with cardiovascular disease

T1 mapping by cardiac magnetic resonance (CMR) allows detection of abnormal myocardium. A number of myocardial abnormalities affects the signal captured in T1 mapping. We performed a systematic review and meta-analysis of native T1 and extracellular volume (ECV) in subjects with and without cardiac disease (1) to determine the normal ranges of T1 values and ECV by sequences as well as parameters influencing them, and (2) to summarize the differences in T1 values and ECV of the diseases relative to the normal ranges. Three databases (EMBASE, SCOPUS, and MEDLINE) were systematically searched for native T1 time and ECV. Only human studies with a sample size of ≥ 20 subjects were included. A random effect model was used to pool data. The 69 selected articles included 1954 healthy subjects and 3186 with disease. T1 of normal healthy was different among MOLLI variants: in 1.5T sequences, ShMOLLI had the shortest (944 ms [95% confidence interval 925, 963]), followed by MOLLI 3(3)3(3)5 flip-angle 50°, 967 [959, 975] and flip-angle 35°, 969 [951, 988]. 3T had longer T1 than 1.5T by approximately 100-200 ms. ECV of the normal healthy was consistent among the studies (ranging from 25 to 27%), irrespective of subjects' factors, sequences, vendors, and contrast type. Many diseases demonstrated longer native T1 than normal subjects, but T1 was shorter in Fabry disease and iron overload. In contrast, all disease states showed either normal or increased ECV. Diagnostic accuracy of native T1 time was minimally affected by the difference in the sequences. ECV is less influenced by methodology than T1 time among normal subjects. Different myocardial diseases are associated with shorter or longer T1 times, whereas ECV is consistently increased independent of the underlying pathophysiology.