Right ventricular biopsy represents the gold standard for the assessment of myocardial fibrosis and collagen content. This invasive technique, however, is accompanied by perioperative complications and poor reproducibility. Extracellular volume (ECV) measured through cardiovascular magnetic resonance (CMR) has emerged as a valid surrogate method to assess fibrosis non-invasively. Nonetheless, ECV provides an overestimation of collagen concentration since it also considers interstitial space. Our study aims to investigate the feasibility of estimating total collagen volume (TCV) through CMR by comparing it with the TCV measured at histology. Seven healthy Landrace pigs were acutely instrumented closed-chest and transported to the MRI facility for measurements. For each protocol, CMR imaging at 3T was acquired. MEDIS software was used to analyze T1 mapping and ECV for both the left ventricular myocardium (LVmyo) and left ventricular septum (LVseptum). ECV was then used to estimate TCVCMR at LVmyo and LVseptum following previously published formulas. Tissues were prepared following an established protocol and stained with picrosirius red to analyze the TCVhisto in LVmyo and LVseptum. TCV measured at LVmyo and LVseptum with both histology (8 ± 5 ml and 7 ± 3 ml, respectively) and T1-Mapping (9 ± 5 ml and 8 ± 6 ml, respectively) did not show any regional differences. TCVhisto and TCVCMR showed a good level of data agreement by Bland-Altman analysis. Estimation of TCV through CMR may be a promising way to non-invasively assess myocardial collagen content and may be useful to track disease progression or treatment response.

中文翻译：

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胶原蛋白总体积的估算：健康长白猪的T1作图与组织学比较研究。

右心室活检代表评估心肌纤维化和胶原蛋白含量的金标准。然而，这种侵入性技术伴随着围手术期并发症和可重复性差。通过心血管磁共振（CMR）测量的细胞外体积（ECV）已成为一种有效的替代方法，用于非侵入性评估纤维化。尽管如此，由于ECV还考虑了组织间隙，因此提供了高估的胶原蛋白浓度。我们的研究旨在通过与组织学测量的TCV进行比较，探讨通过CMR估算总胶原蛋白体积（TCV）的可行性。将7头健康的Landrace猪用封闭的胸腔进行急性检查，并运至MRI设施进行测量。对于每种协议，均采集了3T时的CMR成像。使用MEDIS软件分析左心室心肌（LVmyo）和左心室间隔（LVseptum）的T1定位和ECV。然后使用ECV按照先前发布的公式估算LVmyo和LVseptum的TCVCMR。按照既定规程制备组织，并用picrosirius红染色以分析LVmyo和LVseptum中的TCVhisto。LVmyo和LVseptum在两种组织学（分别为8±5 ml和7±3 ml）和T1-Mapping（分别为9±5 ml和8±6 ml）下测量的TCV没有显示任何区域差异。TCVhisto和TCVCMR通过Bland-Altman分析显示出良好的数据一致性。通过CMR估算TCV可能是非侵入性评估心肌胶原含量的一种有前途的方法，并且可能有助于追踪疾病的进展或治疗反应。