Clinical Importance of Myocardial T₂ Mapping and Texture Analysis

Abstract

Late gadolinium enhancement (LGE) magnetic resonance imaging (MRI) is valuable for diagnosis and assessment of the severity of various myocardial diseases owing to its potential to visualize myocardial scars. T 1 mapping is complementary to LGE because it can quantify the degree of myocardial fibrosis or edema. As such, T 1 -weighted imaging techniques, including LGE using an inversion recovery sequence, contribute to cardiac MRI. T 2 -weighted imaging is widely used to characterize the tissue of many organs. T 2 -weighted imaging is used in cardiac MRI to identify myocardial edema related to chest pain, acute myocardial diseases, or severe myocardial injuries. However, it is difficult to determine the presence and extent of myocardial edema because of the low contrast between normal and diseased myocardium and image artifacts of T 2 -weighted images and the lack of an established method to quantify the images. T 2 mapping quantifies myocardial T 2 values and help identify myocardial edema. The T 2 values are significantly related to the clinical symptoms or severity of nonischemic cardiomyopathy. Texture analysis is a postprocessing method to quantify tissue alterations that are reflected in the T 2 -weighted images. Texture analysis provides a variety of parameters, such as skewness, entropy, and grey-scale non-uniformity, without the need for additional sequences. The abnormal signal intensity on T 2 -weighted images or T 2 values may correspond to not only myocardial edema but also other tissue alterations. In this review, the techniques of cardiac T 2 mapping and texture analysis and their clinical relevance are described.

Image resampling and discretization effect on the estimate of myocardial radiomic features from T1 and T2 mapping in hypertrophic cardiomyopathy

“…However, T2 maps are considered the gold standard for the evaluation of myocardial edema, which is a well-known negative prognostic factor in HCM 15 , 16 . Moreover, although T2 mapping is not per se capable of evaluating myocardial fibrosis, texture analyses might theoretically overcome this limitation, unveiling myocardial structural heterogeneity due to myofibrillar disarray and fibrosis 18 , 27 . Therefore, given also that, overall, radiomic features from T2 maps have proven to be characterized by a lower sensitivity to image resampling and discretization than radiomic features from T1 maps (especially when varying bin width), radiomics from T2 mapping might be exploited to obtain a complementary characterization of HCM, albeit this lower sensitivity does not necessarily imply higher discriminative or predictive power.…”

Image Preprocessing and Filtering Effect on the Estimate of Myocardial Radiomic Features From T1 and T2 Mapping in Hypertrophic Cardiomyopathy

“…However, T2 maps are considered the gold standard for the evaluation of myocardial edema, which is a well-known negative prognostic factor in HCM 15,16 . Moreover, although T2 mapping is not per se capable of evaluating myocardial brosis, texture analyses might theoretically overcome this limitation, unveiling myocardial structural heterogeneity due to myo brillar disarray and brosis 18,27 . Therefore, given also that, overall, radiomic features from T2 maps have proven to be characterized by a lower sensitivity to image preprocessing than radiomic features from T1 maps (especially when varying bin width), radiomics from T2 mapping might be exploited to obtain a complementary characterization of HCM, albeit this lower sensitivity does not necessarily imply higher discriminative or predictive power.…”

“…While radiomic analysis has been mainly applied in the eld of oncology, there is a growing interest in improving the diagnostic accuracy and prognostic value of CMR imaging by exploiting radiomic techniques [25][26][27][28][29][30] . Recently, radiomics has aroused as a useful tool for unveiling myocardial tissue characteristics in HCM patients [18][19][20][21][31][32][33][34][35][36] .…”

Cardiac magnetic resonance assessment of cardiac involvement in autoimmune diseases

“…Extracellular volume (ECV) estimates the expansion of the extracellular space due to edema or fibrosis ( 26 , 27 ). In both acute and chronic myocarditis, the most characteristic location of myocardial edema on CMR is at the subepicardial basal to mid inferolateral segment in a noncoronary distribution on T2w and LGE images ( 28 ). In our clinical experience, myocardial edema in ARD affects the myocardium globally and changes are much more subtle than in classic myocarditis.…”