Kumar Kiran A, Peck Kyung K, Karimi Sasan, Lis Eric, Holodny Andrei I, Bilsky Mark H, Yamada Yoshiya
Department of Radiation Oncology, Stanford University, Stanford, CA, USA.
Department of Radiology, Memorial Sloan Kettering Cancer Center, New York, NY, USA.
Technol Cancer Res Treat. 2017 Dec;16(6):857-865. doi: 10.1177/1533034617705715. Epub 2017 Apr 28.
Dynamic contrast-enhanced magnetic resonance imaging offers noninvasive characterization of the vascular microenvironment and hemodynamics. Stereotactic radiosurgery, or stereotactic body radiation therapy, engages a vascular component of the tumor response which may be detectable using dynamic contrast-enhanced magnetic resonance imaging. The purpose of this study is to examine whether dynamic contrast-enhanced magnetic resonance imaging can be used to predict local tumor recurrence in patients with spinal bone metastases who undergo high-dose radiotherapy with stereotactic radiosurgery.
We conducted a study of 30 patients with spinal metastases who underwent dynamic contrast-enhanced magnetic resonance imaging before and after radiotherapy. Twenty patients received single-fraction stereotactic radiosurgery (24 Gy), while 10 received hypofractionated stereotactic radiosurgery (3-5 fractions, 27-30 Gy total). Kaplan-Meier analysis was used to estimate the actuarial local recurrence rates. Two perfusion parameters (K: permeability and V: plasma volume) were measured for each metastasis. Percentage change in parameter values from pre- to posttreatment was calculated and compared.
At 20-month median follow-up, 5 of the 30 patients had pathological evidence of local recurrence. One- and 3-year actuarial local recurrence rates were 24% and 44% for the hypofractionated stereotactic radiosurgery cohort versus 5% and 16% for the single-fraction stereotactic radiosurgery cohort ( = .20). The average change in V and K for patients without local recurrence versus those with local recurrence was -76% and -66% versus +28% and -14% ( < .01 for both). With a cutoff point of -20%, V had a sensitivity, specificity, positive predictive value, and negative predictive value of 100%, 98%, 91%, and 100%, respectively, for the detection of local recurrence following high-dose radiotherapy. Using this definition, dynamic contrast-enhanced magnetic resonance imaging identified local recurrence up to 18 months (mean [standard deviation], 6.6 [6.8] months) earlier than standard magnetic resonance imaging.
We demonstrated that changes in perfusion parameters, particularly V, after high-dose radiotherapy to spinal bone metastases were predictive of local tumor recurrence. These changes predicted local recurrence on average >6 months earlier than standard imaging did.
动态对比增强磁共振成像可对血管微环境和血流动力学进行无创性特征分析。立体定向放射外科治疗或立体定向体部放射治疗会涉及肿瘤反应的血管成分，这可以通过动态对比增强磁共振成像检测到。本研究的目的是探讨动态对比增强磁共振成像是否可用于预测接受立体定向放射外科高剂量放疗的脊柱骨转移患者的局部肿瘤复发情况。
我们对30例脊柱转移患者进行了研究，这些患者在放疗前后均接受了动态对比增强磁共振成像检查。20例患者接受单次分割立体定向放射外科治疗（24 Gy），10例患者接受大分割立体定向放射外科治疗（3 - 5次分割，总量27 - 30 Gy）。采用Kaplan - Meier分析来估计实际局部复发率。对每个转移灶测量两个灌注参数（K：通透性和V：血容量）。计算并比较治疗前后参数值的百分比变化。
在20个月的中位随访期内，30例患者中有5例有局部复发的病理证据。大分割立体定向放射外科治疗组1年和3年的实际局部复发率分别为24%和44%，而单次分割立体定向放射外科治疗组分别为5%和16%（P = 0.20）。无局部复发患者与有局部复发患者的V和K的平均变化分别为-76%和-66%，而有局部复发患者为+28%和-14%（两者均P < 0.01）。以-20%为界值，V对高剂量放疗后局部复发检测的敏感性、特异性、阳性预测值和阴性预测值分别为100%、98%、91%和100%。采用此定义，动态对比增强磁共振成像比标准磁共振成像提前多达18个月（平均[标准差]，6.6[6.6]）发现局部复发。
我们证明，脊柱骨转移高剂量放疗后灌注参数的变化，尤其是V，可预测局部肿瘤复发。这些变化比标准成像平均提前>6个月预测局部复发。
