TY - JOUR
T1 - Magnetic resonance imaging characteristics and the prediction of outcome of vestibular schwannomas following Gamma Knife radiosurgery
AU - Wu, Chih Chun
AU - Guo, Wan Yuo
AU - Chung, Wen Yuh
AU - Wu, Hisu Mei
AU - Lin, Chung Jung
AU - Lee, Cheng Chia
AU - Liu, Kang Du
AU - Yang, Huai Che
N1 - Publisher Copyright:
© AANS, 2017.
PY - 2017/12
Y1 - 2017/12
N2 - OBJECTIVE Gamma Knife surgery (GKS) is a promising treatment modality for patients with vestibular schwannomas (VSs), but a small percentage of patients have persistent postradiosurgical tumor growth. The aim of this study was to determine the clinical and quantitative MRI features of VS as predictors of long-term tumor control after GKS. METHODS The authors performed a retrospective study of all patients with VS treated with GKS using the Leksell Gamma Knife Unit between 2005 and 2013 at their institution. A total of 187 patients who had a minimum of 24 months of clinical and radiological assessment after radiosurgery were included in this study. Those who underwent a craniotomy with tumor removal before and after GKS were excluded. Study patients comprised 85 (45.5%) males and 102 (54.5%) females, with a median age of 52.2 years (range 20.4-82.3 years). Tumor volumes, enhancing patterns, and apparent diffusion coefficient (ADC) values were measured by region of interest (ROI) analysis of the whole tumor by serial MRI before and after GKS. RESULTS The median follow-up period was 60.8 months (range 24-128.9 months), and the median treated tumor volume was 3.54 cm3 (0.1-16.2 cm3). At last follow-up, imaging studies indicated that 150 tumors (80.2%) showed decreased tumor volume, 20 (10.7%) had stabilized, and 17 (9.1%) continued to grow following radiosurgery. The postradiosurgical outcome was not significantly correlated with pretreatment volumes or postradiosurgical enhancing patterns. Tumors that showed regression within the initial 12 months following radiosurgery were more likely to have a larger volume reduction ratio at last follow-up than those that did not (volume reduction ratio 55% vs 23.6%, respectively; p < 0.001). Compared with solid VSs, cystic VSs were more likely to regress or stabilize in the initial postradiosurgical 6-12-month period and during extended follow-up. Cystic VSs exhibited a greater volume reduction ratio at last follow-up (cystic vs solid: 67.6% ± 24.1% vs 31.8% ± 51.9%; p < 0.001). The mean preradiosurgical maximum ADC (ADCmax) values of all VSs were significantly higher for those with tumor regression or stabilization at last follow-up compared with those with progression (2.391 vs 1.826 × 10-3 mm2/sec; p = 0.010). CONCLUSIONS Loss of central enhancement after radiosurgery was a common phenomenon, but it did not correlate with tumor volume outcome. Preradiosurgical MRI features including cystic components and ADCmax values can be helpful as predictors of treatment outcome.
AB - OBJECTIVE Gamma Knife surgery (GKS) is a promising treatment modality for patients with vestibular schwannomas (VSs), but a small percentage of patients have persistent postradiosurgical tumor growth. The aim of this study was to determine the clinical and quantitative MRI features of VS as predictors of long-term tumor control after GKS. METHODS The authors performed a retrospective study of all patients with VS treated with GKS using the Leksell Gamma Knife Unit between 2005 and 2013 at their institution. A total of 187 patients who had a minimum of 24 months of clinical and radiological assessment after radiosurgery were included in this study. Those who underwent a craniotomy with tumor removal before and after GKS were excluded. Study patients comprised 85 (45.5%) males and 102 (54.5%) females, with a median age of 52.2 years (range 20.4-82.3 years). Tumor volumes, enhancing patterns, and apparent diffusion coefficient (ADC) values were measured by region of interest (ROI) analysis of the whole tumor by serial MRI before and after GKS. RESULTS The median follow-up period was 60.8 months (range 24-128.9 months), and the median treated tumor volume was 3.54 cm3 (0.1-16.2 cm3). At last follow-up, imaging studies indicated that 150 tumors (80.2%) showed decreased tumor volume, 20 (10.7%) had stabilized, and 17 (9.1%) continued to grow following radiosurgery. The postradiosurgical outcome was not significantly correlated with pretreatment volumes or postradiosurgical enhancing patterns. Tumors that showed regression within the initial 12 months following radiosurgery were more likely to have a larger volume reduction ratio at last follow-up than those that did not (volume reduction ratio 55% vs 23.6%, respectively; p < 0.001). Compared with solid VSs, cystic VSs were more likely to regress or stabilize in the initial postradiosurgical 6-12-month period and during extended follow-up. Cystic VSs exhibited a greater volume reduction ratio at last follow-up (cystic vs solid: 67.6% ± 24.1% vs 31.8% ± 51.9%; p < 0.001). The mean preradiosurgical maximum ADC (ADCmax) values of all VSs were significantly higher for those with tumor regression or stabilization at last follow-up compared with those with progression (2.391 vs 1.826 × 10-3 mm2/sec; p = 0.010). CONCLUSIONS Loss of central enhancement after radiosurgery was a common phenomenon, but it did not correlate with tumor volume outcome. Preradiosurgical MRI features including cystic components and ADCmax values can be helpful as predictors of treatment outcome.
KW - Cystic vestibular schwannoma
KW - Gamma Knife radiosurgery
KW - Magnetic resonance imaging
KW - Stereotactic radiosurgery
KW - Vestibular schwannoma
UR - http://www.scopus.com/inward/record.url?scp=85036627900&partnerID=8YFLogxK
U2 - 10.3171/2016.9.JNS161510
DO - 10.3171/2016.9.JNS161510
M3 - Article
C2 - 28186452
AN - SCOPUS:85036627900
SN - 0022-3085
VL - 127
SP - 1384
EP - 1391
JO - Journal of Neurosurgery
JF - Journal of Neurosurgery
IS - 6
ER -