Journal of neurosurgery
-
Journal of neurosurgery · Jan 2005
Does new magnetic resonance imaging technology provide better geometrical accuracy during stereotactic imaging?
The authors sought to compare the accuracy of stereotactic target imaging using the Siemens 1T EXPERT and 1.5T SYMPHONY magnetic resonance (MR) units. ⋯ Larger distortions were observed when using the SYMPHONY 1.5T unit than those with the EXPERT 1T unit. Typical average distortion in EXPERT 1T was not more than 0.6 mm and 0.9 mm for axial and coronal images, respectively. Typical mean distortion for SYMPHONY 1.5T was not more than 1 mm and 1.3 mm for axial and coronal images, respectively. The image sequence affected the distortions in both units. Coronal T2-weighted spin-echo images performed in subthalamic imaging produced the largest distortions of 2.6 mm and 3 mm in the EXPERT 1T and SYMPHONY 1.5T, respectively. Larger distortions were observed in coronal slices than in axial slices in both units, and this effect was more pronounced in SYMPHONY 1.5T. Noncentrally located slice positions in the investigated volume of the phantom were associated with larger distortions.
-
Journal of neurosurgery · Jan 2005
Increased preservation of functional hearing after gamma knife surgery for vestibular schwannoma.
Gamma knife surgery (GKS) for vestibular schwannoma is still associated with an additional hearing loss of approximately 30%. The purpose of this study was to record the effect on hearing preservation of maintaining a margin dose of 13 Gy while reducing the maximum dose to 20 Gy. ⋯ Reducing the maximum dose to 20 Gy seems to be an effective treatment, which probably increases preservation of functional hearing without sacrificing the high tumor control rates achieved in radiosurgery. Post-radiosurgery tumor swelling occurred in 25% of the cases and was not correlated with hearing deterioration.
-
Journal of neurosurgery · Jan 2005
Case ReportsMechanisms of edema after gamma knife surgery for meningiomas. Report of two cases.
The authors describe two patients in whom tumor swelling and brain swelling (and possible tumor swelling), respectively, developed after undergoing gamma knife surgery. One had a skull defect with a palpable parasagittal tumor. One had neurofibromatosis Type 2 with multiple tumors, one of which was parasagittal.
-
Journal of neurosurgery · Jan 2005
Ultrastructural changes in arteriovenous malformations after gamma knife surgery: an electron microscopic study.
The authors analyzed morphological alterations at the subcellular level by undertaking transmission electron microscopy in arteriovenous malformations (AVMs) after gamma knife surgery (GKS). ⋯ The ultrastructural and histological characteristics of the spindle cell population in the GKS-treated AVMs are similar to those designated as myofibroblasts in wound healing processes and pathological fibromatoses. Because similar cell modifications have not been demonstrated in control nonirradiated AVM specimens, these myofibroblasts may contribute to the shrinking process and final occlusion of AVMs after radiosurgery.
-
Journal of neurosurgery · Jan 2005
Comparative StudyStereotactic noninvasive volume measurement compared with geometric measurement for indications and evaluation of gamma knife treatment.
Volume estimation is one of the most important criteria in the evaluation and follow up of radiosurgical treatments and outcomes; however, several limitations are involved in the calculation estimation of target volumes. ⋯ The use of stereotactic volume calculation is highly recommended in planning, follow up, and determination of the outcome in patients participating in radiosurgical treatment and should lead to more uniform reports of the response to treatment.