磁振造影具優異的組織間信號對比、高解析度、不受高密度之骨骼組織的干擾，且有多方位成像的能力及利用非游離輻射線成像等特性。對死亡率極高的主動脈剝離與肺栓塞，可給予較好的病灶鑑別及侵犯的範圍、程度評估，進而提供迅速確實之診治。本研究選取1999年至2001年間15名疑似主動脈剝離或肺栓塞的胸腔疾病患者（男性5名，女性10名，年齡分佈爲28歲至82歲，平均年齡58.6歲），以0.3T低磁場強度磁振造影儀(HITACHI MRP-7000 AD MR IMAGING SYSTEM; Version 5.0 software)搭配體線圈(body coil)進行掃描。結果指出罹主動脈剝離、肺栓塞者共11名，診斷率達73.3%；檢出主動脈剝離者5名，確診率33.3%，且有3名之剝離範圍已擴致腹主動脈，確診率20.0%；肺栓塞者6名，確診率40.0%。此設備進行掃描耗時較長，平均每組T1，約需14分鐘。躁動且不宜注射鎮靜劑之患者，選擇不設定cardiac gating的條件，以縮短檢查時間，所呈現之影像品質雖差，尚可清楚診斷，耗時8分19秒。低磁場強度磁振造影儀之檢查效率雖略遜於高磁場強度設備，但仍有其診斷胸部疾病之價值。偏遠或中小型醫院受限於病人數、資本額不足等原因，造價、維護費均合理的低磁場設備，無疑是合乎經濟又可提高醫療品質之利器。

To evaluate the usefulness of a 0.3 Tesla permanent magnet on the imaging of chest aortic dissection and pulmonary embolism. Materials and Methods: MR images of 15 patients suspected of chest aortic dissection or pulmonary embolism were reviewed at our institution. MR images were evaluated with T1 weighted spin echo sequence in axial, with or without coronal; sagital or LAO views. Inter-observer variations showed no statistical significance. The overall sensitivity was 80% with a specificity of 100%. The accuracy rate was 85%. The positive predictive value was 100% and negative predictive value was 60%. Conclusion: Low-mid field MR imaging can provided another affordable alternate for chest imaging.