MRI T2 mapping has been proven to be sensitive to the level of blood oxygenation. We hypothesized that impaired exercise capacity in chronic heart failure is associated with a greater difference between right (RV) to left ventricular (LV) blood pool T2 relaxation times due to a higher level of peripheral blood desaturation, compared to patients with preserved exercise capacity and to healthy controls. Patients with chronic heart failure (n = 70) who had undergone both cardiac MRI (CMR) and a 6-min walk test (6MWT) were retrospectively identified. Propensity score matched healthy individuals (n = 35) served as control group. CMR analyses included cine acquisitions and T2 mapping to obtain blood pool T2 relaxation times of the RV and LV. Following common practice, age- and gender-adjusted nominal distances and respective percentiles were calculated for the 6MWT. The relationship between the RV/LV T2 blood pool ratio and the results from 6MWT were evaluated by Spearman’s correlation coefficients and regression analyses. Inter-group differences were assessed by independent t-tests and univariate analysis of variance. The RV/LV T2 ratio moderately correlated with the percentiles of nominal distances in the 6MWT (r = 0.66) while ejection fraction, end-diastolic and end-systolic volumes showed no correlation (r = 0.09, 0.07 and − 0.01, respectively). In addition, there were significant differences in the RV/LV T2 ratio between patients with and without significant post-exercise dyspnea (p = 0.001). Regression analyses showed that RV/LV T2 ratio was an independent predictor of the distance walked and the presence of post-exercise dyspnea (p < 0.001). The proposed RV/LV T2 ratio, obtained by two simple measurements on a routinely acquired four-chamber T2 map, was superior to established parameters of cardiac function to predict exercise capacity and the presence of post-exercise dyspnea in patients with chronic heart failure.

中文翻译：

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基于心脏 MRI 的右心室与左心室血池 T2 舒张时间比与慢性心力衰竭患者的运动能力相关

MRI T2 映射已被证明对血氧水平敏感。我们假设，与运动能力保留的患者相比，慢性心力衰竭患者的运动能力受损与右心室 (RV) 与左心室 (LV) 血池 T2 弛豫时间之间的较大差异相关，这是由于外周血去饱和度较高。到健康的控制。回顾性鉴定了接受过心脏 MRI (CMR) 和 6 分钟步行测试 (6MWT) 的慢性心力衰竭患者 (n = 70)。倾向评分匹配的健康个体（n = 35）作为对照组。CMR 分析包括电影采集和 T2 映射，以获得 RV 和 LV 的血池 T2 弛豫时间。按照惯例，计算了 6MWT 的年龄和性别调整后的标称距离和各自的百分位数。通过 Spearman 相关系数和回归分析评估 RV/LV T2 血池比值与 6MWT 结果之间的关系。通过独立 t 检验和单变量方差分析评估组间差异。RV/LV T2 比值与 6MWT 中标称距离的百分位数中度相关（r = 0.66），而射血分数、舒张末期和收缩末期容积则没有相关性（分别为 r = 0.09、0.07 和 − 0.01）。此外，有和没有明显运动后呼吸困难的患者之间的 RV/LV T2 比值存在显着差异 (p = 0.001)。回归分析显示，RV/LV T2 比值是步行距离和运动后呼吸困难存在的独立预测因子 (p < 0.001)。所提出的 RV/LV T2 比值是通过对常规采集的四腔 T2 图进行两次简单测量而获得的，优于既定的心脏功能参数，可以预测慢性心力衰竭患者的运动能力和运动后呼吸困难的情况。