Nesvick Cody L, Graffeo Christopher S, Brown Paul D, Link Michael J, Stafford Scott L, Foote Robert L, Laack Nadia N, Pollock Bruce E
Department of Neurological Surgery, Mayo Clinic, Rochester, MN.
Department of Radiation Oncology, Mayo Clinic, Rochester, MN.
Mayo Clin Proc. 2021 May;96(5):1157-1164. doi: 10.1016/j.mayocp.2020.09.041.
To determine whether biological effective dose (BED) was predictive of obliteration after stereotactic radiosurgery (SRS) for cerebral arteriovenous malformations (AVMs).
We studied patients undergoing single-session AVM SRS between January 1, 1990, and December 31, 2014, with at least 2 years of imaging follow-up. Excluded were patients with syndromic AVM, previous SRS or embolization, and patients treated with volume-staged SRS. Biological effective dose was calculated using a mono-exponential model described by Jones and Hopewell. The primary outcome was likelihood of total obliteration defined by digital subtraction angiography or magnetic resonance imaging (MRI). Variables were analyzed as continuous and dichotomous variables based on the maximum value of (sensitivity-[1-specificity]).
This study included 352 patients (360 AVM, median follow-up, 5.9 years). The median margin dose prescribed was 18.75 Gy (interquartile range [IQR]: 18 to 20 Gy). Two hundred fifty-nine patients (71.9%) had obliteration shown by angiography (n=176) or MRI (n=83) at a median of 36 months after SRS (IQR: 26 to 44 months). Higher BED was associated with increased likelihood of obliteration in univariate Cox regression analyses, when treated as either a dichotomous (≥133 Gy; hazard ratio [HR],1.52; 95% confidence interval [CI], 1.19 to 1.95; P<.001) or continuous variable (HR, 1.00, 95% CI, 1.0002 to 1.005; P=.04). In multivariable analyses including dichotomized BED and location, BED remained associated with obliteration (P=.001).
Biological effective dose ≥133 Gy was predictive of AVM obliteration after single-session SRS within the prescribed margin dose range 15 to 25 Gy. Further study is warranted to determine whether BED optimization should be considered as well as treatment dose for AVM SRS planning.
确定生物等效剂量（BED）是否可预测立体定向放射外科治疗（SRS）脑动静脉畸形（AVM）后的闭塞情况。
我们研究了1990年1月1日至2014年12月31日期间接受单次AVM SRS治疗且至少有2年影像学随访的患者。排除患有综合征性AVM、既往接受过SRS或栓塞治疗以及接受体积分期SRS治疗的患者。使用Jones和Hopewell描述的单指数模型计算生物等效剂量。主要结局是通过数字减影血管造影或磁共振成像（MRI）定义的完全闭塞的可能性。根据（敏感度-[1-特异度]）的最大值将变量作为连续变量和二分变量进行分析。
本研究纳入352例患者（360个AVM，中位随访时间5.9年）。规定的中位边缘剂量为18.75 Gy（四分位间距[IQR]：18至20 Gy）。259例患者（71.9%）在SRS后中位36个月（IQR：26至44个月）时通过血管造影（n = 176）或MRI（n = 83）显示闭塞。在单变量Cox回归分析中，当将BED视为二分变量（≥133 Gy；风险比[HR]，1.52；95%置信区间[CI]，1.19至1.95；P <.001）或连续变量（HR，1.00，95% CI，1.0002至1.005；P =.04）时，较高的BED与闭塞可能性增加相关。在包括二分法BED和位置的多变量分析中，BED仍与闭塞相关（P =.001）。
在规定的边缘剂量范围15至25 Gy内，生物等效剂量≥133 Gy可预测单次SRS后脑AVM的闭塞情况。有必要进一步研究以确定是否应考虑优化BED以及AVM SRS计划的治疗剂量。
