1/134. Integration of preoperative and intraoperative functional brain mapping in a frameless stereotactic environment for lesions near eloquent cortex. Technical note.The authors present a method of incorporating preoperative noninvasive functional brain mapping data into the frameless stereotactic magnetic resonance (MR) imaging dataset used for image-guided resection of brain lesions located near eloquent cortex. They report the use of functional (f)MR imaging and magnetic source (MS) imaging for preoperative mapping of eloquent cortex in difficult cases of brain tumor resection such as those in which there are large expansive masses or in which reoperations are required and the anatomy is distorted from prior treatments. To correlate methods of preoperative and intraoperative mapping localization directly, the authors have developed techniques of importing preoperative MS and fMR imaging data into an image-guided frameless stereotactic computer workstation. The data appear as a seamless overlay on the same preoperative volumetric MR imaging dataset used for stereotactic guidance during the operation. Intraoperatively identified functional locations mapped by cortical stimulation are recorded as digitally registered points. This approach should prove useful in assessing the accuracy and reliability of various preoperative functional brain mapping techniques.- - - - - - - - - - ranking = 1keywords = volume (Clic here for more details about this article) |
2/134. Interstitial laserthermia in neurosurgery.Deep-seated brain tumor is difficult to treat surgically. Hyperthermia using various energy sources has been tried, but has failed to gain wide use because of equipment problems and poor temperature control. It is possible now to use Nd:YAG laser with a stable low-energy supply as an energy source for laser hyperthermia (laserthermia). Animal study and clinical study were done using SLT CL50, Computer-control Laserthermia System to treat deep-seated brain tumors. Experimental study revealed that laserthermia produced minimal edema, temperature control was satisfactory, and blood-brain barrier opened up for 6 days following laserthermia. Five patients with brain tumors were treated with laserthermia. Follow-up CT scan revealed disappearance of tumor in 4 patients and decrease in volume in 1 patient. Long-term neurological follow up revealed no deterioration. Laserthermia using Nd:YAG laser is safe and easy to use and it is beneficial to treat deep-seated brain tumors.- - - - - - - - - - ranking = 1keywords = volume (Clic here for more details about this article) |
3/134. blood-brain barrier and blood volume imaging of cerebral glioma using functional CT: a pictorial review.We present five cases of cerebral glioma that illustrate the benefit of functional CT imaging of blood-brain barrier permeability and cerebral blood volume. Functional CT uses Patlak analysis of a single location dynamic sequence to extract physiological information that is useful clinically in the assessment of cerebral gliomas. Functional CT offers distinct advantages over other functional modalities, including clearer delineation of tumour, tumour grading, measurement of tumour activity and monitoring response to therapy.- - - - - - - - - - ranking = 5keywords = volume (Clic here for more details about this article) |
4/134. The stereotactic volumetric information: its role in two-step resection of brainstem and thalamic giant tumor. Report of three cases and technical note.BACKGROUND: A compact intracerebral tumoral lesion is usually considered to be completely resectable. Nevertheless, radical resection of a huge lesion located in a critical area may damage the surrounding compressed brain tissue. In cases with a good prognosis, a two-step removal appears to be a safer strategy. methods: In three cases, two with huge brain stem lesions and one with a thalamic lesion, a two-step volumetric stereotactic resection was planned. This strategy allowed us to evaluate the amount of tumor to be removed during the first procedure and to have, during the second operation, an exact definition of the reduced mass with regard to the scar tissue and postoperative adhesions. Furthermore, we avoided significant shifting of the cerebral structures during both procedures. RESULTS: There was a very good final recovery in the cases with brain stem lesions and a minimal deficit in the patient with the thalamic lesion. The patient with a mesencephalic lesion remained comatose for almost 2 days after the first procedure, confirming our fears about too radical a one-step resection. CONCLUSIONS: We think that by using current techniques, it is possible to remove a well circumscribed lesion regardless of its position. This is probably easier with giant lesions where a safe trajectory can be planned. In these cases, with lesions located in very critical areas but with a good prognosis, a two-step resection appears to be a good option.- - - - - - - - - - ranking = 5keywords = volume (Clic here for more details about this article) |
5/134. Gamma surgery for intracranial metastases from renal cell carcinoma.OBJECT: The goal of this study was to evaluate the effectiveness and limitations of gamma surgery (GS) in the treatment of renal cell carcinoma that has metastasized to the brain. methods: The authors performed a retrospective analysis of a consecutive series of 21 patients with 37 metastatic brain deposits from renal cell carcinoma who were treated with GS at the University of virginia from 1990 to 1999. Clinical data were available in all patients. No patient died of progression of intracranial disease or deteriorated neurologically following GS. Eight patients clinically improved. Follow-up imaging studies were available for 23 tumors in 12 patients. Nine patients did not undergo follow-up imaging. One patient lived 17 months and succumbed to systemic disease: no brain imaging was performed in this case. Another patient refused further imaging and lived 7 months. Seven patients lived up to 4 months after the procedure; however, their physicians did not require these patients to undergo follow-up imaging examinations because of their general conditions-all had systemic progression of disease. Of the 23 tumors that were observed posttreatment, one remained unchanged in volume, 16 decreased in volume, and six disappeared. No tumor progressed at any time, and there were no radiation-induced changes on follow-up imaging an average of 21 months after GS (range 3-63 months). CONCLUSIONS: Gamma surgery provides an alternative to surgical resection of metastatic brain deposits from renal cell carcinoma. Neurological side effects were seen in only one case; freedom from progression of disease was achieved in all cases.- - - - - - - - - - ranking = 2keywords = volume (Clic here for more details about this article) |
6/134. Gas in the cranium: an unusual case of delayed pneumocephalus following craniotomy.We present the case history of a 23-year-old man who underwent frontal craniotomy followed by radiotherapy for a Grade III anaplastic glioma. magnetic resonance imaging (MRI) at the 3-month follow-up showed significant tumour response. He became unwell some weeks after the MRI with an upper respiratory tract infection, severe headache and mild right-sided weakness. A computed tomographic (CT) scan showed a very large volume of intracranial gas, thought to have entered via a defect in the frontal air sinus after craniotomy and brought to light by blowing his nose. Intracranial air is frequently present after craniotomy, but it is normally absorbed within 34 weeks. The presence of pneumocephalus on a delayed postoperative CT scan should raise the possibility of a cerebrospinal fluid (CSF) fistula, or infection with a gas-forming organism. Many CSF fistulae require surgical closure in order to prevent potentially life-threatening central nervous system infection and tension pneumocephalitis. Immediate neurosurgical review is advisable.- - - - - - - - - - ranking = 1keywords = volume (Clic here for more details about this article) |
7/134. Simultaneous quantitative cerebral perfusion and Gd-DTPA extravasation measurement with dual-echo dynamic susceptibility contrast MRI.Quantification of cerebral perfusion using dynamic susceptibility contrast MRI generally relies on the assumption of an intact blood-brain barrier. The present study proposes a method to correct the tissue response function that does not require this assumption, thus, allowing perfusion studies in, for example, high-grade brain tumors. The correction for contrast extravasation in the tissue during the bolus passage is based on a two-compartment kinetic model. The method separates the intravascular hemodynamic response and the extravascular component and returns the corrected tissue response function for perfusion quantification as well as the extravasation rate constant of the vasculature. Results of simulation experiments with different degrees of contrast extravasation are presented. The clinical potential is illustrated by determination of the perfusion and extravasation of a glioblastoma multiforme. The correction scheme proves to be fast and reliable even in cases of low signal-to-noise ratio. It is applicable whether extravasation occurs or not. When extravasation is present, application of the proposed method is mandatory for accurate cerebral blood volume measurements. Magn Reson Med 43:820-827, 2000.- - - - - - - - - - ranking = 1keywords = volume (Clic here for more details about this article) |
8/134. temporal lobe focal cortical dysplasia: MRI imaging using FLAIR shows lesions consistent with neoplasia.Focal cortical dysplasia (FCD), a form of neuronal migration disorder, is a malformative lesion of the neocortex that occurs during development of the brain. It can cause partial and generalized epilepsy. seizures occur at an early age and are often resistant to medication. Surgical resection has been found to be beneficial in these patients. Dual pathology, in the form of mesial temporal sclerosis, has been associated with FCD. At the Children's Hospital of Eastern ontario, four patients with temporal lobe FCD have recently, been identified. This paper discusses how these children presented and how they were managed, with particular emphasis on their MRI findings and differential diagnoses. In three of the four patients neuroimaging studies showed lesions consistent with a neoplastic process because of the large volume and mass effect. Radiologically, FCD may mimic the MRI appearance of tumors, such as dysembryoplastic neuroepithelial tumors, primitive neuroectodermal tumors, gangliogliomas, oligodendrogliomas, and astrocytomas. These lesions are best visualized on fluid-attenuated inversion recovery (FLAIR) imaging, a technique that has recently become applicable in the clinical setting, as we help demonstrate in this series. With better MRI capability, milder forms of FCD and microdysplasia may be distinguished.- - - - - - - - - - ranking = 1keywords = volume (Clic here for more details about this article) |
9/134. 201Thallium SPECT and 1H-MRS compared with MRI in chemotherapy monitoring of high-grade malignant astrocytomas.PURPOSE: To compare chemotherapy treatment monitoring in astrocytoma by 201thallium single photon emission computed tomography (SPECT) and photon magnetic resonance spectroscopy (1H-MRS) with magnetic resonance imaging (MRI), and to evaluate the influence of morphological tumor changes on cerebral 201thallium uptake and metabolic changes in 1H-MRS. MATERIALS AND methods: Six patients with highly malignant astrocytomas were followed with quantitative 201thallium SPECT, MRI, and 1H-MRS during chemotherapy. Maximum follow-up included six examinations per patient by either method during 18 months. Criteria were set for: (1) regression (> or = 25% tumor reduction), (2) status quo (< 25% reduction and < 25% increase), and (3) progression of disease (> or = 25% tumor increase). Results were compared with the clinical state of disease. Changes of tumor volume, contrast enhancement, necrosis, hemorrhage and edema on MRI were compared to changes in 201thallium uptake volumes and 1H-MRS metabolite ratios. RESULTS: Six patients were followed with a total of twenty-four examinations with 201thallium SPECT, MRI and 1H-MRS, respectively, between February 1997 and October 1998. Five patients developed clinical progression of disease, 4 out of 5 cases showed SPECT progression, 4 out of 5 cases MRI progression, and 1 out of 2 interpretable cases 1H-MRS progression at final assessment before clinical deterioration. During the phase of clinically stable disease; (A) the criterion for regression or status quo was met in 10 out of 13 assessments with SPECT, 11 out of 13 with MRI, and 8 out of 9 interpretable 1H-MRS; (B) the criterion for progression was met in 3 out of 13 with SPECT, 2 out of 13 with MRI, and 1 out of 9 interpretable 1H-MRS. The accuracy of SPECT, MRI, and 1H-MRS in identifying changes of tumor burden concordant with patients' clinical course was 78%, 83%, and 82%, respectively. SPECT regression was associated with MRI decrease of tumor size, contrast enhancement, edema and hemorrhage. SPECT progression was associated with MRI increase of the same parameters and the increase of necrosis. 1H-MRS regression was associated with decrease of edema. 1H-MRS progression was associated with increase of tumor size, hemorrhage, and increase or decrease of contrast enhancement. CONCLUSIONS: Both 201thallium SPECT and 1H-MRS evaluation showed sensitivity for detection of astrocytoma progression. We did not find a higher accuracy of SPECT or MRS than of MRI in astrocytoma chemotherapy monitoring. Treatment induced MRI changes were associated with 201thallium uptake variations. 1H-MRS was difficult to apply for astrocytoma treatment monitoring. Improvements regarding size of measurement area such as multivoxel MRS and fat suppression pulses appeared desirable, and also the use of functional techniques with superior resolution such as dual isotope SPECT. However, our results suggest that 201thallium SPECT and 1H-MRS can provide additional information to MRI for chemotherapy efficacy evaluation in selected cases.- - - - - - - - - - ranking = 2keywords = volume (Clic here for more details about this article) |
10/134. Gamma surgery for hemangiopericytomas.A retrospective analysis of a consecutive series of 12 patients with 15 intracranial hemangiopericytomas treated at the University of virginia using Gamma surgery is presented. Clinical and radiographic follow up of 3 to 56 months is available for 10 patients with 12 tumors. There was one tumor present at the time of initial Gamma surgery in each patient. Two new tumors occurred in patients previously treated. Nine of the tumors decreased in volume and three remained stable. Four of the nine tumors that shrank later progressed at an average of 22 months after treatment. Of the tumors that decreased in volume and have not progressed, the response has been for an average of 11 months. The follow-up for two tumors that remained unchanged was 10 and 34 months (average 22 months). A third tumor was unchanged at 42 months but the patient died of new disease adjacent to the treated area in the anterior skull base. There were no complications and the quality of life following the procedure was maintained or improved in every case. Gamma surgery is effective in palliating the patients by decreasing tumor volume and delaying recurrence.- - - - - - - - - - ranking = 3keywords = volume (Clic here for more details about this article) |
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