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PURPOSE: Noninvasive methods are desired to predict the treatment response to Stereotactic Radiosurgery (SRS) to improve individual tumor management. In a previous study, we demonstrated that Diffusion Tensor Imaging (DTI)-derived parameter maps significantly correlate to SRS response. This study aimed to analyze and compare the predictive value of intratumoral ADC and DTI parameters in patients with meningiomas undergoing radiosurgery. METHODS: MR images of 70 patients treated with Gamma Knife SRS for WHO grade I meningiomas were retrospectively reviewed. MR acquisition included pre- and post-treatment DWI and DTI sequences, and subtractions were calculated to assess for radiation-induced changes in the parameter values. RESULTS: After a mean follow-up period (FUP) of 52.7 months, 69 of 70 meningiomas were controlled, with a mean volume reduction of 34.9%. Whereas fractional anisotropy (FA) values of the initial exam showed the highest correlation to tumor volume change at the last FU (CC = - 0.607), followed by the differences between first and second FU values of FA (CC = - 0.404) and the first longitudinal diffusivity (LD) value (CC = - 0.375), the correlation coefficients of all ADC values were comparably low. Nevertheless, all these correlations, except for ADC measured at the first follow-up, reached significance. CONCLUSION: For the first time, the prognostic value of ADC maps measured in meningiomas before and at first follow-up after Gamma Knife SRS, was compared to simultaneously acquired DTI parameter maps. Quantities assessed from ADC maps present significant correlations to the volumetric meningioma response but are less effective than correlations with DTI parameters.
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Neoplasias Meníngeas , Meningioma , Radiocirugia , Humanos , Meningioma/diagnóstico por imagen , Meningioma/radioterapia , Meningioma/cirugía , Imagen de Difusión Tensora/métodos , Radiocirugia/métodos , Estudios Retrospectivos , Neoplasias Meníngeas/diagnóstico por imagen , Neoplasias Meníngeas/radioterapia , Neoplasias Meníngeas/patologíaRESUMEN
PURPOSE: This report presents the first investigation of the radiomics value in predicting the meningioma volumetric response to gamma knife radiosurgery (GKRS). METHODS: The retrospective study included 93 meningioma patients imaged by three Tesla MRI. Tumor morphology was quantified by calculating 337 shape, first- and second-order radiomic features from MRI obtained before GKRS. Analysis was performed on original 3D MR images and after their laplacian of gaussian (LoG), logarithm and exponential filtering. The prediction performance was evaluated by Pearson correlation, linear regression and ROC analysis, with meningioma volume change per month as the outcome. RESULTS: Sixty calculated features significantly correlated with the outcome. The feature selection based on LASSO and multivariate regression started from all available 337 radiomic and 12 non-radiomic features. It selected LoG-sigma-1-0-mm-3D_firstorder_InterquartileRange and logarithm_ngtdm_Busyness as the predictively most robust and non-redundant features. The radiomic score based on these two features produced an AUC = 0.81. Adding the non-radiomic karnofsky performance status (KPS) to the score has increased the AUC to 0.88. Low values of the radiomic score defined a homogeneous subgroup of 50 patients with consistent absence (0%) of tumor progression. CONCLUSION: This is the first report of a strong association between MRI radiomic features and volumetric meningioma response to radiosurgery. The clinical importance of the early and reliable prediction of meningioma responsiveness to radiosurgery is based on its potential to aid individualized therapy decision making.
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Neoplasias Meníngeas , Meningioma , Radiocirugia , Humanos , Imagen por Resonancia Magnética , Estudios Retrospectivos , Resultado del TratamientoRESUMEN
PURPOSE: To investigate if clinically asymptomatic compression of the middle cerebellar tract by extracerebral posterior fossa tumors can produce changes in diffusion tensor imaging (DTI) parameters and if these changes return to normal after Gamma Knife radiosurgery (GKRS). MATERIAL AND METHODS: In 22 patients (12 female, mean age 53.8 years) with posterior fossa tumors (14 schwannomas and 8 meningiomas), the middle cerebellar tract was tracked using DTI data. DTI parameters, such as fractional anisotropy (FA), mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD) within these tracts were determined separately on the tumor side and on the contra-lateral side. As a surrogate parameter of tract compression, we used the distance between a tangential line extending between the anterior, not affected part of the pons and the cerebellum, and the furthest extension of the tumor into the lateral rim of the pons. In a subgroup of 15 patients, DTI parameters were recorded after a follow-up of more than 2 years (mean follow-up time 37.5 months) after GKRS and compared to initial findings. RESULTS: Before GKRS, all DTI parameters within the compressed tract had increased. The increase in MD correlated significantly with the degree of tract compression (c = 0.443, p < 0.05). Follow-up examinations after GKRS showed reduction in FA and AD, whereas MD and RD increased. After correction for time elapsed after treatment and tumor type, the changes of MD and AD following treatment correlated significantly with the reduction of tract compression, but not with radiation dose. CONCLUSION: Although without obvious clinical symptoms, disorders of the middle cerebellar tract, as in the case of posterior fossa tumors, persist after reduction of tumor size. Because of the significant correlation between the change of parameters and the reduction of tract compression, initial compression and consequent relief are regarded as the main factors responsible for persistent disorders of the middle cerebellar tract. Radiosurgery dose did not contribute significantly to changes in DTI parameters.
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PURPOSE: To demonstrate that lesions of the visual pathways due to suprasellar tumors are accompanied by alterations of the visual cortex and to see if these alterations are reversible after treatment of tumors by gamma knife radiosurgery. MATERIALS AND METHODS: In 36 patients with peri-optic tumors and defects of their visual fields and in an age-matched control group, magnetic resonance imaging was performed before and after treatment. T1 weighted images were evaluated by voxel-based morphometry and correlated to the degree of visual field defects. RESULTS: In patients, grey matter density and cortical thickness were reduced in all parts of the occipital cortex, reaching significance (p < 0.05) in the left superior and middle occipital gyri, with correlation to visual field defects. Follow-up scans showed further reduction in all occipital areas. CONCLUSION: As in other peripheral lesions of the optic system, damage of the optic pathways affects the visual cortex. A prospective follow-up study is needed to determine if these alterations are reversible after successful tumor treatment.
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Adaptación Fisiológica , Neoplasias Encefálicas/diagnóstico por imagen , Neoplasias Encefálicas/radioterapia , Plasticidad Neuronal , Radiocirugia , Corteza Visual/diagnóstico por imagen , Adolescente , Adulto , Anciano , Neoplasias Encefálicas/fisiopatología , Niño , Femenino , Estudios de Seguimiento , Humanos , Imagen por Resonancia Magnética , Masculino , Persona de Mediana Edad , Tamaño de los Órganos , Estudios Retrospectivos , Resultado del Tratamiento , Trastornos de la Visión/diagnóstico por imagen , Trastornos de la Visión/etiología , Trastornos de la Visión/fisiopatología , Corteza Visual/fisiopatología , Campos Visuales/fisiología , Vías Visuales/diagnóstico por imagen , Vías Visuales/fisiopatología , Adulto JovenRESUMEN
INTRODUCTION: In Gamma Knife Radiosurgery (GKRS) of suprasellar lesions, the exact localization of the visual pathways is important to avoid radiation induced optic neuropathy (RION). Reliable identification of the optic nerve, chiasm and tracts can be challenging using routine magnetic resonance imaging, especially in patients with lesions compressing the optic structures or in patients who had prior operation of suprasellar tumors. This study investigates the application of inversion recovery sequences (Fast gray and white matter acquisition T1 inversion recovery, FGATIR) to improve identification of the optic pathway. METHODS: Inversion recovery sequences were performed on 5 healthy volunteers, varying their inversion times between 400 and 500 ms, and between 800 and 1100 ms. Inversion times were optimized to either suppress or to preserve the signal of the optic structures, while increasing or suppressing the signal of processes within the surrounding cisterns. Inversion recovery sequences were performed before radiosurgery on 10 patients with suprasellar tumors that were compressing or displacing the optic structures. Signal intensities of gray and white matter, of CSF and tumors were measured and subtraction images were calculated. RESULTS: Compared to a standard T1-weighted sequence, delineation of the visual pathways was superior on inversion recovery images, both on images with suppression of the optic structures as well on images with suppression of its surrounding tissues, and was rated best on subtraction images. CONCLUSION: For radiosurgery of suprasellar tumors, inversion recovery sequences can be of valuable benefit for accurate delineation of optic pathway and radiosurgical dose planning in order to avoid radiation-induced normal tissue effects.
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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 por cento 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 por cento decorrente de piora intensa de edema perilesional, falecendo o paciente após uma semana. O índice de diagnóstico foi 89,33 por cento.
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Adulto , Niño , Preescolar , Persona de Mediana Edad , Humanos , Masculino , Femenino , Biopsia/métodos , Encéfalo/patología , Técnicas Estereotáxicas , Biopsia/efectos adversos , Técnicas Estereotáxicas/efectos adversos , Tomografía Computarizada por Rayos XRESUMEN
Estudamos o desempenho motor de 50 pacientes com doença de Parkinson submetidos à cirurgia estereotáxica com planejamento computadorizado, sem ventriculografia (talamotomia ventro-lateral e/ou palidotomia póstero-ventral) antes e 1 mês após o procedimento cirúrgico. Foram realizadas 27 talamotomias ventro-laterais (TVL) unilaterais, 10 palidotomias póstero-ventrais (PPV) unilaterais, 6 PPV bilaterais, e 7 TVL associadas à PPV. A avaliaçao motora foi feita com a Escala Unificada para Doença de Parkinson, escore motor, nos períodos on e off. No total, houve melhora do escore motor em todos os grupos. A melhora das discinesias foi observada predominantemente no hemicorpo contralateral à cirurgia, no grupo das palidotomias. Dos 50 pacientes, 16 (32 por cento) apresentaram complicaçoes pós-operatórias, 9 destes (56,25 por cento) se recuperaram totalmente, 6 (37,25 por cento) mostraram melhora parcial, e 1 (6,25 por cento) nao apresentou melhora dentro do primeiro mês. Os resultados foram considerados satisfatórios, e a análise desses dados a longo prazo indicará se os benefícios sao duradouros.