Mayr Simon, Zicha Stefan, Giese Daniel, Kopp Markus, Schmidt Sandy, Arndt Sebastian, Sommerfeld Lisa, Kleiß Joy-Marie, Uder Michael, May Matthias S
Invest Radiol. 2025 Jul 22. doi: 10.1097/RLI.0000000000001225.
This study aimed to compare biventricular cine measurements and quantitative maps of myocardial T1 and T2 relaxation times at field strengths ranging from 0.55T to 1.5T in patients with a clinical indication for cardiac magnetic resonance imaging (CMR). Establishing the feasibility of low-field CMR may improve accessibility due to easier siting and lower cost of the low-field systems.
Thirteen patients underwent same-day comparative CMR at 0.55T and on a commercial scanner at 1.5T. We examined all individuals with breath-held segmented bSSFP cine sequences for volumetric assessment of the left ventricle (LV), right ventricle (RV), and visual assessment of wall motion abnormalities (WMA) and valve pathologies. The quantitative T1 and T2 maps were acquired in 3 short-axis views for tissue characterization. Blinded readers scored the image quality on a 3-point Likert scale. Ten healthy volunteers were additionally examined at 0.55T to obtain reference values for the parametric maps.
Functional analysis of both ventricles at low-field CMR has a reasonable correlation (r=0.94 to 0.99) with conventional 1.5T measurements. LV ejection fraction (EF) (P=0.62) and RV measurements (all P>0.05) were highly reproducible, but LV absolute volumetric measurements were slightly lower at the low-field strength (all P<0.05). T1 and T2 relaxation times correlated strongly between field strengths (r=0.79; P<0.01 and r=0.63; P=0.02). Reference values from the volunteers were 678.6±13.5 ms (T1) and 66.5±4.1 ms (T2). Overall, good image quality was achieved, and visual assessment showed excellent agreement with 1.5T. Trigger artifacts occurred more frequently during 0.55T scans compared with 1.5T. Correct clinical stratification of volumetric parameters, WMA, valve pathologies, and parametric maps was possible in 94% of all cases.
CMR at 0.55T provides a comprehensive assessment of function, structure, and tissue characterization comparable to that of 1.5T. The diagnostic accuracy in this clinical cohort is high. Identification of the specific trigger problems and optimization of the trigger technique could help to overcome the slight inaccuracies in the LV absolute volumetric measurements. Low-field CMR holds promise for expanding access to this valuable diagnostic tool, benefiting patients worldwide and on an individual level.
本研究旨在比较临床有心脏磁共振成像（CMR）指征的患者在0.55T至1.5T场强下双心室电影测量以及心肌T1和T2弛豫时间的定量图谱。由于低场系统选址更容易且成本更低，确定低场CMR的可行性可能会提高其可及性。
13例患者在同一天分别接受了0.55T的CMR检查以及在商用1.5T扫描仪上的检查。我们使用屏气分段bSSFP电影序列对所有个体进行检查，以对左心室（LV）、右心室（RV）进行容积评估，并对室壁运动异常（WMA）和瓣膜病变进行视觉评估。在3个短轴视图中获取定量T1和T2图谱以进行组织特征分析。不知情的阅片者采用3分李克特量表对图像质量进行评分。另外对10名健康志愿者在0.55T下进行检查以获取参数图谱的参考值。
低场CMR对两个心室的功能分析与传统1.5T测量有合理的相关性（r = 0.94至0.99）。左心室射血分数（EF）（P = 0.62）和右心室测量值（所有P>0.05）具有高度可重复性，但在低场强下左心室绝对容积测量值略低（所有P<0.05）。场强之间T1和T2弛豫时间相关性很强（r = 0.79；P<0.01和r = 0.63；P = 0.02）。志愿者的参考值为678.6±13.5毫秒（T1）和66.5±4.1毫秒（T2）。总体而言，图像质量良好，视觉评估显示与1.5T高度一致。与1.5T扫描相比，0.55T扫描期间触发伪影更频繁出现。在所有病例的94%中，对容积参数、WMA、瓣膜病变和参数图谱进行正确的临床分层是可行的。
0.55T下的CMR对功能、结构和组织特征的综合评估与1.5T相当。该临床队列中的诊断准确性很高。识别特定的触发问题并优化触发技术有助于克服左心室绝对容积测量中的轻微不准确。低场CMR有望扩大这种有价值的诊断工具的可及性，使全球患者和个体患者受益。
