压缩感知PETRA扩展相位编码用于近金属植入物MRI
该研究将压缩感知（CS）与PETRA序列结合，并引入扩展相位编码以减少金属植入物附近的伪影。模拟与体模实验显示，csPETRA较SEMAC-VAT几何畸变减少40%，较高中心单点成像覆盖率使伪影尺寸改善20%，16倍加速使总扫描时间降至8分钟。作者认为csPETRA目前应作为补充研究工具而非独立临床序列。
要点
- csPETRA较SEMAC-VAT几何畸变减少40%，伪影更小。
- 中心SPI覆盖6.5%较3.2%使伪影尺寸改善20%。
- 16倍加速使总扫描时间降至8分钟，SAR较SE技术降低2.5倍。
核心结论
- csPETRA采用较高SPI/径向比例可在不增加扫描时间下较常规PETRA减少20%伪影尺寸。
- csPETRA较基于SE的技术SAR降低2.5倍，目前应视为补充研究工具而非独立临床序列。
研究设计与样本
- 研究采用3D真实骨科植入物模型进行csPETRA模拟，比较常规与扩展相位编码。
- 在含3种全膝关节置换植入物的网格体模上，比较csPETRA（相位编码采样覆盖k空间3.2%至6.5%，总采集时间至7±1分钟）与TSE序列联合VAT和SEMAC。
- 对1例腕部植入物患者和1例膝关节假体患者进行在体测量，定量分析伪影大小并定性比较序列。
关键影像表现/征象
- csPETRA图像几何畸变较SEMAC-VAT图像减少40%。
- 中心SPI覆盖6.5%较3.2%使伪影尺寸改善20%。
诊断标准与关键数值
- 中心单点成像（SPI）覆盖比例6.5%较3.2%使伪影尺寸改善20%，对应16倍加速使总扫描时间降至8分钟。
临床应用与阅片要点
- csPETRA可用于金属植入物附近的高分辨率（0.5 mm各向同性）场图 mapping 和植入物评估。
- 对SAR或声噪声严格受限的患者，csPETRA可作为一种备选方案。
- 目前不应作为独立临床序列常规使用，需结合软组织对比机制进一步验证。
局限性
- csPETRA目前应视为补充研究工具，而非独立临床序列。
- 其临床价值需进一步验证，并需开发与评估合适的软组织对比机制。
- 在体测量仅纳入2例患者（腕部植入物和膝关节假体各1例）。
以上解读依据论文摘要（全文未开放获取或许可不允许翻译转载）。
英文原文（摘要）· 点击展开
OBJECTIVES: To apply compressed sensing (CS) PETRA sequence to MRI near metallic implants, and to investigate the use of an extended phase encoding in csPETRA without significantly increasing the total acquisition time.
MATERIALS AND METHODS: Using a 3D realistic model of an orthopedic implant, csPETRA with regular and extended phase encoding was simulated. csPETRA protocols with phase-encoded samples covering from 3.2% to 6.5% of k-space were prepared with a total acquisition time of up to 7±1 minutes and compared to a TSE sequence with VAT and SEMAC in grid phantoms with 3 different total knee arthroplasty implants. In vivo measurements on a patient with a wrist implant and a patient with a knee prosthesis were performed. Quantitative analysis based on the artifact size and qualitative comparison of the tested sequences are presented.
RESULTS: In the csPETRA images, geometric distortions were reduced by 40% compared to those in the SEMAC-VAT images. A ratio of 6.5% for the central single-point imaging (SPI) coverage yielded a 20% improvement in artifact size compared to 3.2% coverage, and a 16-fold acceleration reduced the total scan time to 8 minutes.
CONCLUSIONS: csPETRA with a higher SPI/radial ratio achieves a 20% reduction in artifact size relative to the minimum SPI/radial ratio, that is, conventional PETRA, without a time penalty. In addition, it reduces SAR by a factor of 2.5 compared to SE-based techniques. csPETRA should currently be regarded as a complementary research tool rather than a standalone clinical sequence, with potential niche applications such as high-resolution (0.5 mm isotropic) field mapping and implant assessment, or imaging patients with strict SAR or acoustic-noise constraints, while its clinical value requires further validation together with the development and evaluation of suitable soft-tissue contrast mechanisms.
引用
- Özen AC, Stepanek T, Liu S, et al. Near-metal MRI Using PETRA With Extended Phase Encoding and Compressed Sensing. Invest Radiol. 2026. PMID: 42050962. doi:10.1097/RLI.0000000000001293
供执业医师工作参考，不替代临床判断；数值与分级以指南原文为准。