Quantitative assessment of myocardial fibrosis in an age-related rat model by ex vivo late gadolinium enhancement magnetic resonance imaging with histopathological correlation

Abstract

Late gadolinium enhanced (LGE) cardiac magnetic resonance (CMR) imaging can detect the presence of myocardial infarction from ischemic cardiomyopathies (ICM). However, it is more challenging to detect diffuse myocardial fibrosis from non-ischemic cardiomyopathy (NICM) with this technique due to more subtle and heterogeneous enhancement of the myocardium. This study investigates whether high-resolution LGE CMR can detect age-related myocardial fibrosis using quantitative texture analysis with histological validation. LGE CMR of twenty-four rat hearts (twelve 6-week-old and twelve 2-year-old) was performed using a 7 Tesla MRI scanner. Picrosirius red was used as the histopathology reference for collagen staining. Fibrosis in the myocardium was quantified with standard deviation (SD) threshold methods from the LGE CMR images and 3D contrast texture maps that were computed from grey level co-occurrence matrix of the CMR images. There was a significant increase of collagen fibers in the aged compared to the young rat histology slices (2.60±0.27 %LV vs. 1.24±0.29 %LV, p<0.01). Both LGE CMR and texture images showed a significant increase of myocardial fibrosis in the elderly compared to the young rats. Fibrosis in the LGE CMR images correlated strongly with histology with the 3 SD threshold (r=0.84, y=0.99x+0.00). Similarly, fibrosis in the contrast texture maps correlated with the histology using the 4 SD threshold (r=0.89, y=1.01x+0.00). High resolution ex-vivo LGE CMR can detect the presence of diffuse fibrosis that naturally developed in elderly rat hearts. Our results suggest that texture analysis may improve the assessment of myocardial fibrosis in LGE CMR images.

Association between myocardial extracellular volume and strain analysis through cardiovascular magnetic resonance with histological myocardial fibrosis in patients awaiting heart transplantation

“…The LGE was quantified using a threshold of 4 standard deviations (SD) above the mean signal intensity of the remote normal myocardium within the same slice [ 32 ]. The LGE images were assessed by an independent observer who was blinded to mapping and histological data.…”

Assessment of Remote Myocardium Heterogeneity in Patients with Ventricular Tachycardia Using Texture Analysis of Late Iodine Enhancement (LIE) Cardiac Computed Tomography (cCT) Images

“…Texture features extracted from biomedical images are extensively explored for “radiomic-phenotypization” of different solid tumors [ 22 ]. Moreover, some studies have suggested that a texture analysis may extract quantitative information about liver fibrosis from conventional CT images [ 23 ], as well as interstitial myocardial fibrosis from late gadolinium enhancement (LGE) magnetic resonance images [ 24 ].…”

Relationship between Extension or Texture Features of Late Gadolinium Enhancement and Ventricular Tachyarrhythmias in Hypertrophic Cardiomyopathy

“…Further study with a fast and powerful computer will be necessary to determine whether some of 100 texture features provide a higher AUC than the extension of LGE for identifying the patients with HCM and ventricular tachyarrhythmia. In addition, the threshold of entropy LL or texture features discriminating the HCM patients with and without ventricular tachyarrhythmias may differ from that of the present study if other software is used for texture analysis of LGE images [ 25 ]. Finally, we did not compare between the LGE showing low or high values of entropy LL and the histological findings.…”