Optimizing scan times in clinical neuroimaging: the potential of synthetic MRI

Synthetic Magnetic Resonance Imaging (SI) generates images from parametric maps of tissue properties and derives contrast weightings from the same acquisition. We aimed to evaluate the potential for scan time reduction using SI in patients with neurological indications in a tertiary care cantonal hospital. We searched our hospital database for head imaging performed between March 2020 and August 2022. Sequences were categorized as either fully replaceable (Scenario A) or potentially replaceable (Scenario B) if replacement would lead to limitations, such as resolution or contrast. We calculated the time used and potentially saved if all replaceable sequences and their respective planning were replaced by a 3-dimensional (3D) SI sequence lasting 3 or 5 min. We identified 4,320 head examinations. Total examination time for replaceable sequence imaging in Scenario A was 656 h 54 min (minimum: 506 h 26 min; maximum: 982 h 53 min) and 778 h 38 min (minimum: 602 h 34 min; maximum: 1,223 h 34 min) for Scenario A & B. If 3D SI had been used, the estimated time required would have been 216 h for a 3-minute 3D SI and 360 h for a 5-minute 3D SI. The application of SI would have yielded an estimated reduction of 440 h 54 min (minimum: 290 h 26 min; maximum: 766 h 53 min) for Scenario A, and 562 h 38 min (minimum: 386 h 34 min; maximum: 907 h 34 min) for Scenario A & B. Reducing scan time with 3D SI is feasible and depends on the scan time of 3D SI, the type and frequency of performed protocols, and its ability to meet high-quality requirements. The effectiveness is most pronounced when 3D SI can replace traditional weighted images while maintaining diagnostic standards.

合成磁共振成像（Synthetic Magnetic Resonance Imaging，SI）可通过组织属性参数图生成影像，并基于同一采集流程获取对比加权参数。本研究旨在评估在某州立三级医院中，针对神经科就诊患者应用合成磁共振成像以缩短扫描时长的可行性。我们检索了本院数据库中2020年3月至2022年8月期间的头部影像检查数据，将所采用的扫描序列分为两类：完全可替代序列（场景A）与潜在可替代序列（场景B）——后者若被替代可能会引发分辨率或对比效果受限等问题。我们模拟了将所有可替代序列及其对应的扫描规划步骤替换为时长3分钟或5分钟的三维（3D）合成磁共振成像序列的场景，并计算了实际使用时长与潜在节省时长。本次研究共纳入4320例头部检查病例。场景A中，可替代序列成像的总检查时长为656小时54分钟（最小值：506小时26分钟，最大值：982小时53分钟）；场景A与B合并时，总检查时长则为778小时38分钟（最小值：602小时34分钟，最大值：1223小时34分钟）。若采用三维合成磁共振成像序列，假设单序列时长为3分钟时，总预估所需时长为216小时；单序列时长为5分钟时，总预估所需时长则为360小时。应用合成磁共振成像可实现的预估扫描时长节省量，在场景A中为440小时54分钟（最小值：290小时26分钟，最大值：766小时53分钟），在场景A与B合并时则为562小时38分钟（最小值：386小时34分钟，最大值：907小时34分钟）。采用三维合成磁共振成像缩短扫描时长具备可行性，其效果取决于三维合成磁共振成像的单序列时长、所使用扫描方案的类型与频次，以及其能否满足高质量成像要求。当三维合成磁共振成像可在维持诊断标准的前提下替代传统加权成像序列时，时长缩减效果最为显著。