McDannold Nathan, Tempany Clare M, Fennessy Fiona M, So Minna J, Rybicki Frank J, Stewart Elizabeth A, Jolesz Ferenc A, Hynynen Kullervo
Department of Radiology, Harvard Medical School, Brigham and Women's Hospital, 221 Longwood Ave (LMRC, 007c), Boston, MA 02115, USA.
Radiology. 2006 Jul;240(1):263-72. doi: 10.1148/radiol.2401050717.
To retrospectively evaluate magnetic resonance (MR) imaging-based thermometry and thermal dosimetry during focused ultrasound treatments of uterine leiomyomas (ie, fibroids).
All patients gave written informed consent for the focused ultrasound treatments and the current HIPAA-compliant retrospective study, both of which were institutional review board approved. Thermometry performed during the treatments of 64 fibroids in 50 women (mean age, 46.6 years +/- 4.5 [standard deviation]) was used to create thermal dose maps. The areas that reached dose values of 240 and 18 equivalent minutes at 43 degrees C were compared with the nonperfused regions measured on contrast material-enhanced MR images by using the Bland-Altman method. Volume changes in treated fibroids after 6 months were compared with volume changes in nontreated fibroids and with MR-based thermal dose estimates.
While the thermal dose estimates were shown to have a clear relationship with resulting nonperfused regions, the nonperfused areas were, on average, larger than the dose estimates (means of 1.9 +/- 0.7 and 1.2 +/- 0.4 times as large for areas that reached 240- and 18-minute threshold dose values, respectively). Good correlation was observed for smaller treatment volumes at the lower dose threshold (mean ratio, 1.0 +/- 0.3), but for larger treatment volumes, the nonperfused region extended to locations within the fibroid that clearly were not heated. Variations in peak temperature increase were as large as a factor of two, both between patients and within individual treatments. On average, the fibroid volume reduction at 6 months increased as the ablated volume estimated by using the thermal dose increased.
Study results showed good correlation between thermal dose estimates and resulting nonperfused areas for smaller ablated volumes. For larger treatment volumes, nonperfused areas could extend within the fibroid to unheated areas.
回顾性评估子宫平滑肌瘤（即纤维瘤）聚焦超声治疗期间基于磁共振（MR）成像的温度测量和热剂量测定。
所有患者均签署了聚焦超声治疗及当前符合健康保险流通与责任法案（HIPAA）的回顾性研究的书面知情同意书，这两项研究均获机构审查委员会批准。对50名女性（平均年龄46.6岁±4.5[标准差]）的64个纤维瘤进行治疗期间的温度测量，用于创建热剂量图。使用Bland-Altman方法，将在43℃达到240和18等效分钟剂量值的区域与对比剂增强MR图像上测量的无灌注区域进行比较。比较6个月后治疗的纤维瘤的体积变化与未治疗的纤维瘤的体积变化以及基于MR的热剂量估计值。
虽然热剂量估计值与产生的无灌注区域有明确关系，但无灌注区域平均大于剂量估计值（分别达到240分钟和18分钟阈值剂量值的区域平均分别大1.9±0.7倍和1.2±0.4倍）。在较低剂量阈值下，较小治疗体积观察到良好的相关性（平均比值，1.0±0.3），但对于较大治疗体积，无灌注区域延伸至纤维瘤内明显未受热的位置。患者之间以及个体治疗过程中，峰值温度升高的变化高达两倍。平均而言，随着使用热剂量估计的消融体积增加，6个月时纤维瘤体积缩小增加。
研究结果表明，对于较小的消融体积，热剂量估计值与产生的无灌注区域之间具有良好的相关性。对于较大的治疗体积，无灌注区域可能在纤维瘤内延伸至未受热区域。
