热消融过程中表观扩散系数降低演变监测的可行性研究
A feasibility study on monitoring the evolution of apparent diffusion coefficient decrease during thermal ablation.
作者信息
Plata Juan C, Holbrook Andrew B, Marx Michael, Salgaonkar Vasant, Jones Peter, Pascal-Tenorio Aurea, Bouley Donna, Diederich Chris, Sommer Graham, Pauly Kim Butts
机构信息
Department of Radiology, Stanford University, 1201 Welch Road, Stanford, California 94305.
Department of Radiation Oncology, University of California San Francisco, 1600 Divisadero Street, Suite H-1301, San Francisco, California 94143.
出版信息
Med Phys. 2015 Sep;42(9):5130-7. doi: 10.1118/1.4928155.
PURPOSE
Evaluate whether a decrease in apparent diffusion coefficient (ADC), associated with loss of tissue viability (LOTV), can be observed during the course of thermal ablation of the prostate.
METHODS
Thermal ablation was performed in a healthy in vivo canine prostate model (N = 2, ages: 5 yr healthy, mixed breed, weights: 13-14 kg) using a transurethral high-intensity ultrasound catheter and was monitored using a strategy that interleaves diffusion weighted images and gradient-echo images. The two sequences were used to measure ADC and changes in temperature during the treatment. Changes in temperature were used to compute expected changes in ADC. The difference between expected and measured ADC, ADCDIFF, was analyzed in regions ranging from moderate hyperthermia to heat fixation. A receiver operator characteristic (ROC) curve analysis was used to select a threshold of detection of LOTV. Time of threshold activation, tLOTV, was compared with time to reach CEM43 = 240, tDOSE.
RESULTS
The observed relationship between temperature and ADC in vivo (2.2%/ °C, 1.94%-2.47%/ °C 95% confidence interval) was not significantly different than the previously reported value of 2.4%/ °C in phantom. ADCDIFF changes after correction for temperature showed a mean decrease of 25% in ADC 60 min post-treatment in regions where sufficient thermal dose (CEM43 > 240) was achieved. Following our ROC analysis, a threshold of 2.25% decrease in ADCDIFF for three consecutive time points was chosen as an indicator of LOTV. The ADCDIFF was found to decrease quickly (1-2 min) after reaching CEM43 = 240 in regions associated with heat fixation and more slowly (10-20 min) in regions that received slower heating.
CONCLUSIONS
Simultaneous monitoring of ADC and temperature during treatment might allow for a more complete tissue viability assessment of ablative thermal treatments in the prostate. ADCDIFF decreases during the course of treatment may be interpreted as loss of tissue viability.
目的
评估在前列腺热消融过程中，是否能够观察到与组织活力丧失（LOTV）相关的表观扩散系数（ADC）下降。
方法
使用经尿道高强度超声导管在健康的犬体内前列腺模型（N = 2，年龄：5岁健康，混种，体重：13 - 14 kg）中进行热消融，并采用一种交替采集扩散加权图像和梯度回波图像的策略进行监测。这两个序列用于测量治疗过程中的ADC和温度变化。温度变化用于计算ADC的预期变化。在从中度热疗到热固定的区域分析预期ADC与测量ADC之间的差异ADCDIFF。使用受试者工作特征（ROC）曲线分析来选择LOTV的检测阈值。将阈值激活时间tLOTV与达到CEM43 = 240的时间tDOSE进行比较。
结果
体内观察到的温度与ADC之间的关系（2.2%/°C，95%置信区间为1.94% - 2.47%/°C）与先前在体模中报道的2.4%/°C的值无显著差异。在达到足够热剂量（CEM43 > 240）的区域，温度校正后的ADCDIFF变化显示治疗后60分钟ADC平均下降25%。根据我们的ROC分析，连续三个时间点ADCDIFF下降2.25%的阈值被选为LOTV的指标。发现在与热固定相关的区域达到CEM43 = 240后，ADCDIFF迅速下降（1 - 2分钟），而在加热较慢的区域下降较慢（10 - 20分钟）。
结论
治疗过程中同时监测ADC和温度可能有助于对前列腺消融热疗进行更全面的组织活力评估。治疗过程中ADCDIFF的下降可能被解释为组织活力丧失。
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