OBJECTIVEDiffusion tensor imaging (DTI) parameters are able to differentiate between meningioma subtypes. The hypothesis that there is a correlation between DTI parameters and the change in tumor size after Gamma Knife radiosurgery (GKRS) was analyzed.METHODSDTI parameters were measured using MRI before GKRS in 26 patients with meningiomas. The findings were correlated with the change in tumor size after treatment as measured at the last follow-up (range 12.5–45 months).RESULTSOnly those meningiomas that showed the highest fractional anisotropy (FA), the lowest spherical index of the tensor ellipsoid (Cs), and the lowest radial diffusivity (RD) either increased or remained stable in terms of volume, whereas all other meningiomas decreased in volume. The correlation between the DTI parameters (correlation values of −0.81 for FA, 0.75 for Cs, 0.66 for RD, and 0.66 for mean diffusivity) and the rate of volume change per month was significant (p ≤ 0.001). Other factors, including original tumor size, prescription dose, and patient age, did not correlate significantly.CONCLUSIONSMeningiomas that show high FA values—as well as low Cs, low RD, and low mean diffusivity values—do not respond as well to GKRS in comparison with meningiomas with low FA values. This finding might be due to their higher content level of fibrous tissue. In particular, the meningioma with the highest FA value (0.444) considerably increased in volume (by 32.3% after 37 months), whereas the meningioma with the lowest FA value (0.151) showed the highest rate of reduction (3.3% per month) in this study.
OBJECTIVEThe goal of this study was to identify parameters from routine T1- and T2-weighted MR sequences and diffusion tensor imaging (DTI) that best predict the volumetric changes in a meningioma after treatment with Gamma Knife radiosurgery (GKRS).METHODSIn 32 patients with meningioma, routine MRI and DTI data were measured before GKRS. A total of 78 parameters derived from first-level texture analysis of the pretreatment MR images, including calculation of the mean, SD, 2.5th and 97.5th percentiles, and kurtosis and skewness of data in histograms on a voxel-wise basis, were correlated with lesion volume change after a mean follow-up period of 3 years (range 19.5–63.3 months).RESULTSSeveral DTI-derived parameters correlated significantly with a meningioma volume change. The parameter that best predicted the results of GKRS was the 2.5th percentile value of the smallest eigenvalue (L3) of the diffusion tensor (correlation coefficient 0.739, p ≤ 0.001), whereas among the non-DTI parameters, only the SD of T2-weighted images correlated significantly with a tumor volume change (correlation coefficient 0.505, p ≤ 0.05, after correction for family-wise errors using false-detection-rate correction).CONCLUSIONSDTI-derived data had a higher correlation to shrinkage of meningioma volume after GKRS than data from T1- and T2-weighted image sequences. However, if only routine MR images are available, the SD of T2-weighted images can be used to predict control or possible progression of a meningioma after GKRS.
Analisamos 75 pacientes com lesões do sistema nervoso central submetidos a biópsia estereotáxica no período de março de 1993 a dezembro de 1998 na Universidade Federal de São Paulo - Escola Paulista de Medicina. As três lesões mais frequentes foram: metástase, astrocitoma de baixo grau e glioblastoma multiforme. O índice de morbidade foi 2,66% decorrente de: infecção de ferida operatória em uma paciente portadora de cisto talâmico; e de um paciente com linfoma que apresentou crise convulsiva parcial motora durante a cirurgia. A mortalidade foi 1,33% decorrente de piora intensa de edema perilesional, falecendo o paciente após uma semana. O índice de diagnóstico foi 89,33%.
long-term toxicity. Radiotherapy with proton therapy may improve patient outcomes by reducing radiation dose to surrounding normal tissues. Materials/Methods: Chart review and volumetric MRI-analyses were performed on vestibular schwannoma patients treated with proton radiotherapy (PT) between 2003-2018 at a single institution. Patients with a minimum radiological follow-up of 12 months were included. Tumor control was defined as not requiring salvage treatment. Available toxicity data were collected. Results: Of 276 identified patients, 221 patients met the inclusion criteria. Tumor control was 96% with a median radiological follow-up of 4.4 years. The majority of patients (62%) received single fraction proton stereotactic radiosurgery (PSRS), and the remaining (38%) received standard fractionated therapy. Fractionated radiated patients had larger median tumor volumes and larger extracanalicular tumor diameters at baseline (p < 0.001). Cystic tumors showed an increased shrinkage rate after treatment, although this did not reach significance (p Z 0.084). Facial paresis was seen in 1%, trigeminal neuralgia in 4%, hydrocephalus in 2%, and severe dizziness in 6% of patients receiving proton radiotherapy as primary treatment. Trigeminal neuralgia occurred more often in patients with larger tumor volumes (OR 1.44, p-value 0.005) and in patients that received fractionated therapy (OR 5.0, p Z 0.0496). Cochlear mean doses were 8.8 and 43.4 Gy (RBE) for PSRS and fractionated patients, however with wide ranges (0.3-12.4 and 1.4-53.9 Gy (RBE)). Audiological follow-up was available for 51 patients. Median maximal speech discrimination decreased from 78% to a one-year postirradiation of 54% to last follow-up (median 48 months) of 33%. Conclusion: Proton radiotherapy for vestibular schwannoma achieves high tumor control and reasonably low toxicity rates. Some sequelae of radiation (vestibular functioning, cognitive functioning, quality of life) warrant further evaluation. Patient subgroups that may significantly benefit from proton therapy should be identified to merit its higher costs as compared to photon therapy.
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