Li Yi, Casula Victor, Huhta Tarja, Mailhiot Sarah, Tolkkinen Katja, Karjalainen Jouni, Liimatainen Timo
Research Unit of Health Sciences and Technology, University of Oulu, Oulu, Finland.
Research Unit of Biomedicine and Internal Medicine, University of Oulu, Oulu, Finland.
NMR Biomed. 2025 Aug;38(8):e70083. doi: 10.1002/nbm.70083.
Late gadolinium-enhanced cardiovascular magnetic resonance (LGE-CMR) has been used to visualize the sinoatrial node (SAN) structure. In this study, we aimed to investigate the rotating frame relaxation (RAFF2 and T) time mapping to characterize the SAN structure in the heart ex vivo without a contrast agent. Ex vivo swine heart tissues were scanned on a 7 T vertical bore preclinical and a 3 T clinical MRI system. The contrast between the SAN and the surrounding atria was assessed using T, T, T, and T relaxation time mappings, as well as magnetization transfer (MT) imaging. Masson's trichrome stained histological sections were prepared to validate the location of the SAN. Relative relaxation time difference (RRTD) and MT contrast (MTC) were calculated for the SAN and remote myocardium areas. Significant differences between the SAN and myocardium were observed in all endogenous MRI contrasts. T and T showed the highest contrast between the SAN and myocardium, although the differences in contrast among T, T and T were not significant at 3 T. Furthermore, SAN sizes determined based on T and T maps were highly correlated with the corresponding fibrous structures in the histological sections. The 3D reconstruction of 2D T maps revealed the SAN region with increased relaxation time compared to the surrounding myocardium, located lateral to the crista terminalis. This study demonstrates the potential of T and T for visualizing the SAN in the swine heart without the use of contrast agents. Detection of the SAN location using T and T relaxation time mapping could offer a non-invasive alternative to LGE-CMR.
延迟钆增强心血管磁共振成像（LGE-CMR）已被用于观察窦房结（SAN）结构。在本研究中，我们旨在研究旋转框架弛豫（RAFF2和T）时间映射，以在无需造影剂的情况下对离体心脏中的SAN结构进行表征。对离体猪心脏组织在7T垂直孔径临床前MRI系统和3T临床MRI系统上进行扫描。使用T、T、T和T弛豫时间映射以及磁化传递（MT）成像来评估SAN与周围心房之间的对比度。制备Masson三色染色组织切片以验证SAN的位置。计算SAN和远隔心肌区域的相对弛豫时间差（RRTD）和MT对比度（MTC）。在所有内源性MRI对比度中均观察到SAN与心肌之间存在显著差异。T和T在SAN与心肌之间显示出最高的对比度，尽管在3T时T、T和T之间的对比度差异不显著。此外，基于T和T图确定的SAN大小与组织切片中的相应纤维结构高度相关。二维T图的三维重建显示，与周围心肌相比，SAN区域的弛豫时间增加，位于终末嵴外侧。本研究证明了T和T在不使用造影剂的情况下可视化猪心脏中SAN的潜力。使用T和T弛豫时间映射检测SAN位置可为LGE-CMR提供一种非侵入性替代方法。
