We also performed a hand-search for publications through the references listed in the selected studies. We also summarised the variations in the technical details used in these studies to provide possible avenues for further research in this field.Ĭomputerised bibliographic search of the online databases was performed using PubMed, EMBASE and the Cochrane Library. Therefore, we conducted a systematic review and meta-analysis to objectively evaluate the performance of T1 mapping for quantitative measurement of myocardial fibrosis using CMR. To date, there have been no quantitative systematic reviews summarising the validation tests. A previous review on T1 mapping also mentioned the need to examine and compare the three frequently used means of interpreting T1 mapping results to provide a more systematic and credible evaluation of the performance of T1 mapping for the assessment of myocardial fibrosis. However, these studies are limited by small subject numbers and vary regarding the technical details, as well as the disease types included. Several studies have been performed to examine the correlation between the T1 mapping results and the collagen measured via biopsies the majority of the validation studies show favorable correlation. To date, three main IR-prepared CMR sequences are used in T1 mapping including standard Look-Locker(LL) sequence, modified Look-Locker MOLLI sequence and shortened-MOLLI (ShMOLLI) sequence, according to the previous reviews over techniques. Pre-contrast T1 and post-T1 are used before and after gadolinium injection respectively, and ECV measures the extracellular volume after gadolinium injection. This quantification includes native or pre-contrast T1, post-contrast T1 and the expansion of the myocardial extracellular volume (ECV). Recently, the establishment of T1 mapping Cardiovascular Magnetic Resonance (CMR), provides a novel and non-invasive method of visualising and quantifying myocardial fibrosis (Fig. Nevertheless, the clinical application of EMB is largely limited by its invasiveness, requirements for skilled operators, the patient factors, and sampling bias. Traditionally, endomyocardial biopsy (EMB) was the only method by which to visualise and measure the collagen volume fraction (CVF) to determine the degree of fibrosis. Therefore, the development of an accurate and convenient way to measure and assess myocardial fibrosis is of clinical significance. Thus, the degree and distribution of the fibrosis can serve as key indicators for disease development, mortality, as well as prognosis. A close relationship between myocardial fibrosis and the development of myocardial dysfunction, including impaired relaxation, precipitation of arrhythmias and impaired contractile ability is associated with a wide range of diseases. Myocardial fibrosis is a common histological characteristic of various heart conditions, from advanced aging to diseases such as myocardial ischemia, aortic stenosis, hypertrophic cardiomyopathy (HCM) and dilated cardiomyopathy (DCM). Further studies are required to determine the calibration of the T1 mapping results for the biopsy findings of different cardiomyopathies. The quantitative measurement of myocardial fibrosis via T1 mapping is associated with a favourable overall correlation with the myocardial biopsy measurements. ResultsĪ total of 15 studies, including 308 patients who had CMR and myocardial biopsy were included and the pooled correlation coefficient between ECV measured by T1 mapping and biopsy for the selected studies was 0.884 (95% CI: 0.854, 0.914) and was not notably heterogeneous chi-squared = 7.44 P = 0.489 for the Q test and I^2 = 0.00%). A pooled correlation coefficient between the CMR and histology measurements was used to evaluate the performance of the T1 mapping. PubMed, EMBASE and the Cochrane Library databases were searched for studies applying T1 mapping to measure myocardial fibrosis and that validated the results via histological analysis. A systematic review and meta-analysis was conducted to objectively and comprehensively evaluate the performance of T1 mapping on the quantification of myocardial fibrosis using cardiovascular magnetic resonance (CMR). Although T1 mapping is a potential alternative for myocardial biopsy, validation studies are limited to small numbers and vary regarding technical facets, and include only a restricted number of disease. Thus, the development of an accurate and convenient method to evaluate myocardial fibrosis is of major importance. Myocardial fibrosis is being increasingly recognised as a common final pathway of a wide range of diseases.