PURPOSE The aim of this study was to explore the association of cardiac fibroblast activation with clinical parameters and cardiovascular magnetic resonance (CMR) imaging parameters in patients with chronic thromboembolic pulmonary hypertension (CTEPH). METHODS Thirteen CTEPH patients were prospectively enrolled. All of the patients underwent cardiac 68Gallium-labelled fibroblast activation protein inhibitor (68 Ga-FAPI-04)-positron emission tomography/computed tomography (PET/CT), right heart catheterisation, and echocardiography, and 11 of them additionally underwent CMR. Thirteen control subjects were selected to establish the normal range of cardiac 68 Ga-FAPI-04 uptake. Cardiac 68 Ga-FAPI-04 uptake higher than that in the blood pool was defined as abnormal. The global and segmental maximum standardised uptake values (SUVmax) of the right ventricle (RV) were measured and further expressed as target-to-background ratio (TBRRV) with left ventricular lateral wall activity as background. Late gadolinium enhancement (LGE) was visually evaluated, and native-T1 times, enhanced-T1 times, and extracellular volume (ECV) were quantitatively measured. RESULTS Ten CTEPH patients (77%) had abnormal 68 Ga-FAPI-04 uptake in RV, mainly located in the free wall, which was significantly higher than that in controls (TBRRV: 2.4 ± 0.9 vs 1.0 ± 0.1, P < 0.001). The TBRRV correlated positively with the thickness of RV wall (r = 0.815, P = 0.001) and inversely with RV fraction area change (RVFAC) (r =  - 0.804, P = 0.001) and tricuspid annular plane systolic excursion (TAPSE) (r =  - 0.678, P = 0.011). No correlation was found between 68 Ga-FAPI-04 activity and CMR imaging parameters. CONCLUSION Fibroblast activation in CTEPH, measured by 68 Ga-FAPI-04 imaging, is mainly localised in the RV free wall. Enhanced fibroblast activation reflects the thickening of the RV wall and decreased RV contractile function.

中文翻译：

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慢性血栓栓塞性肺动脉高压患者心脏成纤维细胞活化的成像。

目的 本研究旨在探讨慢性血栓栓塞性肺动脉高压 (CTEPH) 患者心脏成纤维细胞活化与临床参数和心血管磁共振 (CMR) 成像参数之间的关系。方法 前瞻性招募了 13 名 CTEPH 患者。所有患者均接受了心脏68镓标记的成纤维细胞活化蛋白抑制剂（68 Ga-FAPI-04）-正电子发射断层扫描/计算机断层扫描（PET/CT）、右心导管术和超声心动图检查，其中11人还接受了CMR。选择了 13 名对照受试者来建立心脏 68 Ga-FAPI-04 摄取的正常范围。心脏 68 Ga-FAPI-04 摄取高于血池中的摄取被定义为异常。测量右心室 (RV) 的全局和节段最大标准化摄取值 (SUVmax)，并进一步表示为以左心室侧壁活动为背景的目标与背景比 (TBRRV)。视觉评估晚期钆增强（LGE），并定量测量天然T1倍、增强T1倍和细胞外体积（ECV）。结果 10 例 CTEPH 患者（77%）在 RV 中 68 Ga-FAPI-04 摄取异常，主要位于游离壁，明显高于对照组（TBRRV：2.4 ± 0.9 vs 1.0 ± 0.1，P < 0.001） . TBRRV 与 RV 壁厚度呈正相关（r = 0.815，P = 0.001），与 RV 分数面积变化（RVFAC）（r = - 0.804，P = 0.001）和三尖瓣环平面收缩偏移（TAPSE）成反比（r = - 0.678，P = 0.011）。未发现 68 Ga-FAPI-04 活性与 CMR 成像参数之间存在相关性。结论 CTEPH 中的成纤维细胞活化，通过 68 Ga-FAPI-04 成像测量，主要位于 RV 游离壁。增强的成纤维细胞活化反映了 RV 壁的增厚和 RV 收缩功能的降低。