Imaging of Myocardial Fibrosis in Patients with End-Stage Renal Disease: Current Limitations and Future Possibilities

Table 3

T1 mapping in myocardial fibrosis caused by different conditions. AS, aortic stenosis; HCM, hypertrophic cardiomyopathy; DCM, dilated cardiomyopathy; LGE, late gadolinium enhancement; LVH, left ventricular hypertrophy; STEMI, ST-elevation myocardial infarction; NSTEMI, non-ST-elevation myocardial infarction; shMOLLI, shortened modified look-locker inversion; MOLLI, modified look-locker inversion.

Condition	Study	Results	Limitations
AS	Bull et al. [63]	Significant correlation between T1 value and histological degree of fibrosis (collagen volume fractions) ,	Due to age matching with patients with AS, older subjects were examined in this study, which could affect the T1 values
Amyloidosis	Karamitsos et al. [64]	Significantly increased mean (±standard deviation) myocardial T1 in patients with AL amyloidosis compared to normal subjects (1140 ± 61 ms versus 958 ± 20 ms: ). T1 mapping could detect cardiac amyloidosis, even when it was thought to be absent when assessed by echocardiography criteria and standard biomarkers	Results compared to echocardiographic criteria of myocardial amyloidosis and not histological data
Hypertrophic cardiomyopathy and dilated cardiomyopathy	Dass et al. [65]	Mean (±standard deviation) T1 relaxation time per subject was significantly elevated in both HCM and DCM in comparison to controls (HCM 1209 ± 28 ms, DCM 1225 ± 42 ms, control 1178 ± 13 ms, ). There was modest correlation between T1 mapping and fibrosis identified by LGE; however T1 values were also increased in segments without LGE suggesting distinct pathologies being measured	Small sample size; Did not study extracellular volume fractions and therefore can only speculate the mechanisms underlying correlations between T1 values and impaired myocardial function. Used LGE to confirm fibrosis rather than histological analysis
Fabry disease	Pica et al. [66]	Mean (±standard deviation) native T1 in patients with Fabry disease with and without LVH was lower compared to healthy volunteers (853 ± 50 ms and 904 ± 46 ms, resp., versus 968 ± 32 ms, ). In patients without LVH, reduced T1 is associated with ECHO parameters of cardiac dysfunction suggesting that a low T1 is detecting early cardiac disease	Small single-centre study. No comparison with biopsy or cardiac magnetic resonance spectroscopy for measuring myocardial lipid storage
Chronic myocardial infarction	Kali et al. [67]	Good agreement between LGE and T1 mapping measuring infarct size ( in STEMI and 0.85 in NSTEMI, ) demonstrating that chronic myocardial infarction size, location, and transmurality can be reliably characterised by T1 mapping	Small sample size and a single-centre study. Did not acquire T2 maps to confirm resolution of acute oedema
Iron overload	Sado et al. [68]	Mean (±standard deviation) myocardial T1 was lower in patients with iron overload than in healthy volunteers (836 ± 138 ms versus 968 ± 32 ms, ). T1 reproducibility was also shown to be significantly superior to T2	Significant interstudy and intraobserver differences between the T2 mapping and either of the T1 mapping methods (shMOLLI versus MOLLI)
Acute myocarditis	Ferreira et al. [69]	Using a threshold of T1 > 990 ms (sensitivity 90%, specificity 88%), they found that T1 mapping detected significantly larger areas of myocardial injury (32%) than T2-weighted and LGE (11% and 5%, resp.) imaging in all patients	Differentiation of myocardial areas affected by acute oedema however with no data on chronic scarring/fibrosis