组织凝固性坏死对基于纵向弛豫时间的磁共振测温的影响

高强度聚焦超声（High Intensity Focused Ultrasound，HIFU）治疗肿瘤时，为了保证治疗的安全性和有效性，需要对组织温度分布进行实时监测.磁共振成像（Magnetic Resonance Imaging，MRI）具有对温度敏感的成像参数，可以无创检测组织温度.本文结合组织相变对测温的影响，探讨了磁共振测温（Magnetic Resonance Thermometry，MRT）技术能否用于实时监控HIFU治疗.利用两态快速交换模型，提出在组织凝固性坏死的相变前后，MRI的纵向弛豫时间（T₁）参数与组织温度之间具有不同关系.并通过实验验证了上述假设.相对于传统的磁共振测温方法模型，本文考虑了HIFU治疗过程中组织相变对检测温度的影响，对利用磁共振测温引导HIFU治疗具有重要的参考价值.

Effects of Tissue Coagulative Necrosis on Longitudinal Relaxation Time-Based Magnetic Resonance Thermometry

Real-time monitoring of tissue temperature is required during high intensity focused ultrasound (HIFU) tumor treatment to ensure safety and effectiveness. Magnetic resonance imaging (MRI) can be used to measure tissue temperature non-invasively during HIFU treatment. This paper examined the effects of coagulation necrosis-induced tissue phase transition on magnetic resonance thermometry (MRT) during HIFU tumor treatment. With a two-state rapid exchange model, the relationship between tissue longitudinal relaxation time (T₁) and temperature before and after HIFU radiation-induced coagulation necrosis/tissue phase transition were analyzed theoretically. Taking the effects of tissue phase transition into account, the experimental scheme and data processing procedures for MRT were optimized, and better temperature measurements were obtained. The work demonstrated the importance of considering the effects of tissue phase transition in real-time MRT during HIFU treatment.