UNASSIGNED: OBJECTIVE Gamma Knife surgery (GKS) is a promising treatment modality for @entity1 with @entity5513 ( @entity5513 ), but a small percentage of @entity1 have persistent postradiosurgical @entity5 growth. The aim of this study was to determine the clinical and quantitative MRI features of VS as predictors of long-term @entity5 control after GKS. METHODS The authors performed a retrospective study of all @entity1 with VS treated with GKS using the Leksell Gamma Knife Unit between 2005 and 2013 at their institution. A total of 187 @entity1 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 @entity5 removal before and after GKS were excluded. Study @entity1 comprised 85 (45.5%) males and 102 (54.5%) females, with a median age of 52.2 years (range 20.4-82.3 years). @entity5 volumes, enhancing patterns, and apparent diffusion coefficient (ADC) values were measured by region of interest (ROI) analysis of the whole @entity5 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 @entity5 volume was 3.54 cm(3) (0.1-16.2 cm(3)). At last follow-up, imaging studies indicated that 150 @entity5 (80.2%) showed decreased @entity5 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. @entity5 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 @entity5513 , cystic @entity5513 were more likely to regress or stabilize in the initial postradiosurgical 6-12-month period and during extended follow-up. Cystic @entity5513 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 @entity5513 were significantly higher for those with @entity5 regression or stabilization at last follow-up compared with those with progression (2.391 vs 1.826 * 10(-3) mm(2)/sec; p = 0.010). CONCLUSIONS Loss of central enhancement after radiosurgery was a common phenomenon, but it did not correlate with @entity5 volume outcome. Preradiosurgical MRI features including cystic components and ADCmax values can be helpful as predictors of treatment outcome.

Magnetic resonance imaging characteristics and the prediction of outcome of XXXX following Gamma Knife radiosurgery.

@entity1 :: ('9606', 'Species') :: ['patients'] @entity5513 :: ('MESH:D009464', 'Disease') :: ['VSs', 'vestibular schwannomas'] @entity5 :: ('MESH:D009369', 'Disease') :: ['tumor', 'Tumors', 'Tumor', 'tumors']
@entity5513 :: (MESH:D009464,Disease) :: ['vestibular schwannomas']
