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W A Hall

Publications and source records attributed to W A Hall.

At least 37 records · Page 2Linked to original sources
PubMed2001

Brain biopsy sampling by using prospective stereotaxis and a trajectory guide.

OBJECT: The authors describe their initial results obtained using a skull-mounted trajectory guide for intraoperative magnetic resonance (MR) imaging-guided brain biopsy sampling. The device was used in conjunction with a new methodology known as prospective stereotaxis for surgical trajectory alignment. METHODS: Between January 1999 and March 2000, 38 patients underwent 40 brain biopsy procedures in which prospective stereotaxis was performed with the trajectory guide in a short-bore 1.5-tesla MR imager. In most cases, orthogonal T2-weighted half-Fourier acquisition single-shot turbo spin-echo (HASTE) images were used to determine the desired trajectory and align the device. The surgical trajectory was defined as a line connecting three points: the target, pivot, and alignment stem points. In all cases, surgical specimens were submitted for frozen section and pathological examination. Postoperative turbofluid-attenuated inversion-recovery and gradient-echo images were obtained to exclude the presence of hemorrhage. Trajectory determination and alignment was simple and efficient, requiring less than 5 minutes. Confirmatory HASTE images were obtained along the biopsy needle as it was being advanced or after reaching the target. All biopsy procedures yielded diagnostic tissue. One patient with a lesion near the motor strip experienced a transient hemiparesis of the hand related to passage of the biopsy needle, and another sustained a fatal postoperative myocardial infarction. No patient suffered a clinically significant or radiologically visible hemorrhage. CONCLUSIONS: In combination with prospective stereotaxis, the trajectory guide provided a safe and accurate way to perform brain biopsy procedures.

Adolescent↗
PubMed2001

Preliminary assessment of turbo spectroscopic imaging for targeting in brain biopsy.

BACKGROUND AND PURPOSE: Brain biopsy remains an integral and necessary component in the diagnosis of brain lesions. We assessed the ability of turbo spectroscopic imaging (TSI) to provide a physiologically based target for tissue sampling. METHODS: TSI was performed in 26 anesthetized patients immediately before MR-guided brain biopsy. In 10 patients, single-voxel spectroscopy was performed on the TSI-indicated target and correlated with the TSI findings. Biopsy samples were taken from the imaging and spectroscopically defined target(s) under MR guidance, and pathologic findings were compared with preoperative spectra. RESULTS: TSI alone provided a definitive target based on a region of elevated choline in 17 of 21 patients in whom a neoplasm was confirmed. The remaining four neoplasms exhibited relatively low metabolic levels and were difficult to distinguish from the five cases of radiation necrosis seen in this study. TSI findings were in qualitative agreement with those obtained at single-voxel spectroscopy, although TSI spectra exhibited more contamination. Quantitative spectral analysis of TSI data is limited by low spectral resolution. CONCLUSION: TSI is helpful for determining an appropriate biopsy target in heterogeneous lesions. Coupling TSI targeting with conventional imaging and intraoperative confirmation of needle positioning resulted in a 100% diagnostic success rate and increased the clinician's confidence in the histologic findings.

Adolescent↗
PubMed2001

Intraoperative MR systems. High-field approaches.

Since the introduction of MR-guided neurosurgery, the field has evolved considerably. As it has been convincingly demonstrated, MR-guided therapy seems to be feasible and safe at all clinical field strengths up to 1.5 T. This article discusses the technology of MR-guided therapy at 1.5 T, and in particular, the multiple approaches that have been advanced to date.

Brain↗
PubMed2001

Optimizing brain tumor resection. High-field interventional MR imaging.

High-field strength iMRI guidance is an effective tool for brain tumor resection. Although its use lengthens the average time for a craniotomy, the reward is a more extensive tumor excision compared with conventional neurosurgery without an increased risk to the patient (Table 4). Although intraoperative patient transfer into and out of the magnet is cumbersome, the possibility for complete resection, especially for a low-grade glioma, makes the effort worthwhile. The cost and technical support required for this system presently limits its use to only a few sites worldwide. As with any technology, further refinements will make this system less expensive and more attainable. Practical consideration aside, high-field strength iMRI is presently [table: see text] the most effective tool available for brain tumor resection. Because of its novelty, future studies are necessary to determine if this technology lowers the incidence of and extends the duration to tumor recurrence as the preliminary data in children suggests. These are the ultimate measures of efficacy for any brain tumor treatment. Based on the rapid advancement of technology, will today's high-field strength interventional magnet become tomorrow's low-field system? Very high-field strength designs may improve diagnostic capabilities through higher resolution, but their interventional applications may be hindered by increased sensitivity for clinically insignificant abnormalities and decreased specificity for clinically relevant lesions. As new technology is developed, clinicians must continue to explore and refine the existing high-field strength iMRI to make it cost-effective and widely applicable.

Adolescent↗
PubMed2001

Neuronavigation in interventional MR imaging. Prospective stereotaxy.

A practical MR imaging-based guidance/control methodology has been developed successfully and validated for improving the performance of stereotactic neurosurgerical procedures such as brain lesion biopsy. The use of the device and method in 40 routine MR-guided procedures has revealed its potential as an alternative approach. Superior to the traditional stereotactic systems, which rely on the old images, the new method, based on prospective guidance, can provide good and acceptable targeting accuracy in the presence of brain shift. Furthermore, the use of MR monitoring of the overall neurosurgical procedure provides another independent assurance for the success of a complicated surgery. The advantages of the new surgical guidance system and method are simple and compatible with the existing capabilities of conventional MR scanners. More importantly, it allows a more effective surgical guidance in the presence of brain shift during the typical neurosurgery. Another important advantage of the guidance method and device is the performance of a truly MR-guided neurosurgical procedure in a conventional, short bore high field MR scanner. Surgical procedures using the guidance system and method have been accepted by radiologists and neurosurgeons as an attractive MR-based stereotactic approach. It can be expected that this guidance scheme will be a useful addition to the MR-based stereotactic system for neurosurgery, and animal research, in which cumbersome stereotactic frames have been used.

Biopsy, Needle↗
PubMed2001

Cost-efficacy of MR-guided neurointerventions.

This article summarizes the available data on the cost-efficacy of interventional MR imaging and discusses its potential future role in the diagnosis and management of neurologic diseases and disorders.

Humans↗
PubMed2000

In vitro efficacy of recombinant diphtheria toxin-murine interleukin-4 immunoconjugate on mouse glioblastoma and neuroblastoma cell lines and the additive effect of radiation.

OBJECT: The prognosis for patients with primary malignant brain tumors is poor despite aggressive treatment, and tumor recurrence is common regardless of the chosen therapy. Although multimodal treatment does not provide a cure, it is necessary to determine which treatment modalities have the greatest cytotoxic effect and can potentially prolong survival. Immunotoxin therapy is a novel approach for the treatment of tumors, and it has been successfully used in the central nervous system. Because the interleukin (IL)-4 receptor is commonly expressed on brain tumor cells, the purpose of this study was to evaluate the cytotoxic effect of using a modified diphtheria toxin-murine IL-4 (DT390- mIL4) immunoconjugate for the treatment of murine brain tumor cell lines and to determine whether the addition of radiation therapy could potentiate the effect of this agent. METHODS: Spontaneous murine glioblastoma (SMA-560) and two neuroblastoma (Neuro-2a and NB41A3) cell lines were treated using DT390-mIL4 at different concentrations, and the anti-mouse IL-4 monoclonal antibody (11B11) was used for blocking its cytotoxicity. Other SMA-560 and Neuro-2a cell lines were treated using 500 cGy of radiation 3 hours before DT390-mIL4 treatment. Cytotoxity was evaluated using a trypan blue viability assay. The immunoconjugate exhibited a dose-dependent cytotoxic effect with 50% inhibitory concentration values of 0.56 x 10(-9) M in SMA-560, 1.28 x 10(-9) M in Neuro-2a, and 0.95 x (-10) M in NB41A3 cell lines. The cytotoxicity of DT390-mIL4 was specifically blocked by an excess of 11B11. Cytotoxicity was additive when the DT390-mIL4 at 10(-9) M immunoconjugate administration was followed by radiation therapy. CONCLUSIONS: These results indicate that the IL-4 receptor can be a target for diphtheria toxin fusion proteins and that radiation can potentiate the effects of DT390-mIL4. The development of multimodal approaches to treat malignant brain tumors with agents that have different mechanisms of action may be beneficial.

Animals↗
PubMed2000

The role of radiosurgery for multiple brain metastases.

OBJECT: The authors evaluated the role of stereotactic radiosurgery (SRS) in patients with multiple brain metastases by analyzing prognostic factors that predict survival. METHODS: Between March 1991 and January 1999, 83 patients with multiple brain metastases underwent SRS in which they used a 6 mV linear accelerator. The median radiation dose of 15 Gy (range 6-50 Gy) was delivered to the 40 to 90% (median 87%) isodose line encompassing the target. Actuarial overall survival was calculated from the date of SRS by using the Kaplan-Meier method. Univariate comparisons of survival between different groups were performed using a log-rank test. All 83 patients were included in the calculation of overall survival. Actuarial overall survival was 22% at 1 year and 13% at 2 years, and a median survival of 5.4 months (range, 0.3-28.8 months) was demonstrated. Variables that predicted survival were Karnofsky Performance Scale (KPS) score, extracranial disease status, and the number of intracranial metastases. Median survival in patients with a KPS score greater than as compared with less than 70 was 9.1 and 2.7 months, respectively (p = 0.002). Median survival when comparing absence and presence of extracranial disease was 9.9 and 4.1 months, respectively (p = 0.02). Median survival in patients harboring two, three, or four or more lesions was 6.6 months, 5.4 months, and 2.7 months, respectively (p = 0.02). In patients with a KPS score greater than or equal to 70 and with three or fewer lesions, median survival was 7 months or longer. In patients with four or more lesions median survival was 7.4 months for those with no extracranial disease and 2.4 months for those with extracranial disease. Other variables tested (sex, histological tumor type, previous resection, location of metastases, treatment modality, and tumor status) did not influence outcome. CONCLUSIONS: The absence of extracranial disease, a KPS score greater than or equal to 70, and fewer number of metastases were shown to be significant predictors of longer survival. Stereotactic radiosurgery appears to be a reasonable therapeutic option in patients with up to three lesions when their KPS score is greater than or equal to 70, regardless of extracranial disease status. In those with four or more metastases, however, SRS should be limited to those with no extracranial disease.

Adult↗
PubMed2000

Safety and efficacy of a multicenter study using intraarterial chemotherapy in conjunction with osmotic opening of the blood-brain barrier for the treatment of patients with malignant brain tumors.

BACKGROUND: The aim of this study was to determine the safety and efficacy of intraarterial chemotherapy with osmotic opening of the blood-brain barrier (BBB) for the treatment of malignant brain tumors when administered across multiple centers. METHODS: Patients with primary central nervous system lymphoma (PCNSL), primitive neuroectodermal tumor (PNET), germ cell tumor, cancer metastasis to the brain, or low or high grade glioma were eligible. Prior to entry, magnetic resonance imaging or computed tomography brain scan, medical history, neurologic status, and Karnofsky performance status were reviewed at the coordinating center. Standardized anesthesia and intraarterial catheterization guidelines were followed by a multidisciplinary team at each center. Between March 1994 and November 1997, 5 universities treated 221 adult patients with intraarterial chemotherapy with or without osmotic opening of the BBB (2464 procedures). RESULTS: Of evaluable patients with PCNSL, 40 of 53 (75%) achieved complete response (CR). All evaluable patients with PNET (n = 17), metastatic disease (n = 12), or germ cell tumor (n = 4) achieved stable disease (SD) or better. Of 57 evaluable patients with glioblastoma multiforme, 45 (79%) achieved SD or better. Asymptomatic subintimal tear occurred in 11 of 221 patients (5%), pulmonary embolism in 6 of 221 (2.7%), and renal toxicity in 4 of 221 (1.8%). One patient with extensive glioma expired within 48 hours after treatment. CONCLUSIONS: Using standard guidelines and protocols, intraarterial chemotherapy with or without osmotic opening of the BBB is feasible across multiple centers with a low incidence of catheter-related complications. In patients with chemotherapy-sensitive tumors, such as PCNSL, PNET, germ cell tumor, and cancer metastasis to the central nervous system, enhanced delivery results in a high degree of tumor response, with an efficacy profile that is reproducible across multiple centers.

Adult↗
PubMed2000

Long-term survival with metastatic cancer to the brain.

Metastatic cancer to the brain has a poor prognosis. The focus of this work was to determine the incidence of long-term (> or = 2y) survival for patients with brain metastases from different primary cancers and to identify prognostic variables associated with prolonged survival. A retrospective review of 740 patients with brain metastases treated over a 20 y period identified 51 that survived 2 or more years from the time of diagnosis of the brain metastasis. Prognostic variables that were examined included age, sex, histology, tumor number and location, and treatment. In the 51 patients, 35 (69%) had single lesions and 16 (31%) had multiple tumors. For all tumor types (740 patients), the actuarial survival rate was 8.1% at 2 y, 4.8% at 3 y, and 2.4% at 5 y. At 2 y, patients with ovarian carcinoma had the highest survival rate (23.9%) and patients with small cell lung cancer (SCLC) had the lowest survival rate (1.7%). At 5y, survival rates were 7.8% for ovarian carcinoma, 2.9% for non-SCLC, 2.3% for melanoma and renal cell carcinoma, 1.3% for breast carcinoma and there were no survivors with SCLC, gastrointestinal, bladder, unknown primary, or prostate cancer. Age, sex, histology, location for single tumors, systemic chemotherapy, and stereotactic radiosurgery did not significantly influence survival. The presence of a single lesion (P = 0.001, chi-square test), surgical resection (P= 0.001), and WBRT (P = 0.009) were favorable prognostic variables for extended survival. Multiple bilateral metastases was a poor prognostic indicator (P= 0.001). Multivariate analysis showed younger age (P< 0.05), single metastasis (P < 0.0001), surgical resection (P < 0.0001), whole brain radiation therapy (P < 0.0001), and chemotherapy (P = 0.0288) were associated with prolonged survival. 29 patients (57%) died of systemic disease progression, 9 (18%) died of central nervous system progression, and the cause of death was unknown in 3 (6%). Patients with a single non-SCLC, breast, melanoma, renal cell, and ovarian carcinoma brain metastasis have the best chance for long-term survival if treated with surgical resection and WBRT.

Adult↗
PubMed2000

Intraoperative magnetic resonance imaging.

Intraoperative magnetic resonance imaging (MRI) allows neurosurgeons to perform surgery interactively using magnetic resonance (MR) guidance. Low-field and high-field strength MRI has been developed and implemented for multiple neurosurgical procedures, including brain biopsies, craniotomies for resection of mass lesions, cyst drainages, laminectomies, thermal ablations, functional neurosurgery, and a variety of miscellaneous cases. Both technologies have the advantage over frameless neuronavigational systems of being able to perform near real-time imaging, which allows the surgeon to compensate for intraoperative brain shift. Intraoperative functional techniques such as MR spectroscopy, functional MRI, MR angiography and venography, and diffusion-weighted imaging, which have become routine at some high-field MR units, can significantly influence surgical decision making. The potential complications associated with intraoperative MR-guided neurosurgery are similar in incidence to those seen in the conventional neurosurgical operating room. However, the immediate recognition of such intraoperative complications with MRI should lead to improved outcomes and decreased medical costs. Untoward events associated with performing surgery in an MR environment are uncommon. Intraoperative MR-guided neurosurgery represents a natural progression from framed and frameless stereotactic techniques. Intraoperative MRI is still in its infancy, and the full capabilities of this technology have yet to be determined or implemented.

Humans↗
PubMed2000

Targeted toxin therapy for malignant astrocytoma.

The poor prognosis associated with malignant astrocytoma has led investigators to seek new, innovative methods of treatment. Targeted toxins represent a unique form of therapy that has two components, a carrier molecule with high specificity for tumor-associated antigens and a potent protein toxin. These compounds are extremely cytotoxic to malignant astrocytoma cell lines in vitro. Animal studies have shown prolongation of survival and complete tumor regression when targeted toxins were administered by a variety of routes. The promising results seen in vivo have formed the basis for proceeding with clinical trials in humans with leptomeningeal neoplasia and malignant brain tumors, in which these agents are administered intrathecally or directly into tumor, respectively. To date, in these clinical trials, targeted toxins have been delivered safely without significant neurological toxicity, and cytological analysis of cerebrospinal fluid and radiological findings have shown evidence of a therapeutic response. These studies have confirmed the existence of a therapeutic window between normal brain tissue and malignant cells that can be exploited with targeted therapy directed against the transferrin receptor. The successful delivery of targeted toxins directly into malignant brain tumors has established this route of administration as practical and feasible. Identification of other receptors that are preferentially expressed on brain tumors, such as the interleukin-4 receptor, has resulted in the creation of a fusion protein against this receptor that contains a modified toxin from the bacteria Pseudomonas aeruginosa. This chimeric fusion toxin is currently under investigation in a Phase I clinical trial with patients with recurrent malignant astrocytoma, and other targeted toxins are under development for the treatment of these uniformly fatal tumors. Owing to these recent advances in targeted toxin therapy for malignant primary brain tumors, a review of the development of these agents for practicing neurosurgeons seems timely.

Animals↗
PubMed2000

Safety, efficacy, and functionality of high-field strength interventional magnetic resonance imaging for neurosurgery.

OBJECTIVE: Interventional magnetic resonance imaging (MRI) allows neurosurgeons to interactively perform surgery using MRI guidance. High-field strength (1.5-T) imaging permits exceptional observation of intracranial and spinal pathological features. The development of this technology and its application to a variety of neurosurgical procedures are described. METHODS: We report on the first 101 cases that were treated in the interventional MRI unit (between January 1997 and September 1998). These cases included 39 brain biopsies, 30 tumor resections, 9 functional neurosurgical cases, 8 cyst drainages, 5 laminectomies, and 10 miscellaneous cases. Patients ranged in age from 14 months to 84 years (median, 43 yr); 61 patients were male and 40 were female. Intraoperative functional techniques that were used to influence surgical decision-making included magnetic resonance spectroscopy, functional MRI, magnetic resonance angiography and venography, chemical shift imaging, and diffusion-weighted imaging. All surgery was performed using MRI-compatible instruments within the 5-gauss line and conventional instruments outside that line. RESULTS: All 39 brain biopsies yielded diagnostic tissue. Of the 30 tumor resections, 24 (80%) were considered radiographically complete. The incidence of serious complications was low and was comparable to that associated with conventional operating rooms. One patient developed a Propionibacterium acnes brain abscess 6 weeks after surgery and another patient experienced Staphylococcus aureus scalp cellulitis after a brain biopsy, yielding an infection rate of less than 2%. No clinically significant hemorrhage was observed in immediate postoperative imaging scans, although one patient developed a delayed hematoma after a thalamotomy. One patient experienced a stroke after resection of a hippocampal tumor. No untoward events were associated with MRI-compatible instrumentation or intraoperative patient monitoring. CONCLUSION: High-field (1.5-T) interventional MRI is a safe and effective technology for assisting neurosurgeons in achieving the goals of surgery. Preliminary results suggest that the functional capabilities of this technology can yield data that can significantly influence intraoperative neurosurgical decision-making. The rates of serious complications, such as infection, associated with this new technology were low.

Adolescent↗
PubMed2000

Brain tumor resection: intraoperative monitoring with high-field-strength MR imaging-initial results.

PURPOSE: To investigate the challenges and benefits of magnetic resonance (MR) imaging during brain tumor resection. MATERIALS AND METHODS: A short-bore 1.5-T MR system equipped with echo-planar-capable gradients was used in resection of brain tumors in 30 patients. MR sequences and need for contrast material enhancement were determined on the basis of the targeted lesion. MR images were acquired before, during, and after surgery. Tissue obtained at biopsy or excised as a result of intraoperative MR findings was examined histopathologically. RESULTS: MR images of enhancing lesions proved to be the most challenging to interpret intraoperatively, and relative enhancement at the resection cavity boundary was not specific for residual tumor. The ability to detect residual tumor intraoperatively resulted in a radiologically complete resection in 24 (80%) of 30 patients. The frequency of complications was low, and no untoward effects related to the MR environment were observed. CONCLUSION: Intraoperative MR imaging provided valuable information on the completeness of resection, and resection progress was well demonstrated during surgery.

Adolescent↗
PubMed1999

Single dose versus fractionated stereotactic radiotherapy for recurrent high-grade gliomas.

PURPOSE: To evaluate the efficacy of stereotactic radiotherapy (SRT) in patients with recurrent high-grade gliomas by comparing two different treatment regimens, single dose or fractionated radiotherapy. METHODS AND MATERIALS: Between April 1991 and January 1998, 71 patients with recurrent high-grade gliomas were treated with SRT. Forty-six patients (65%) were treated with single dose radiosurgery (SRS) and 25 patients (35 %) with fractionated stereotactic radiotherapy (FSRT). For the SRS group, the median radiosurgical dose of 17 Gy was delivered to the median of 50% isodose surface (IDS) encompassing the target. For the FSRT group, the median dose of 37.5 Gy in 15 fractions was delivered to the median of 85% IDS. RESULTS: Actuarial median survival time was 11 months for the SRS group and 12 months for the FSRT group (p = 0.3, log-rank test). Variables predicting longer survival were younger age (p = 0.006), lower grade (p = 0.0006), higher Karnofsky Performance Scale (KPS) (p = 0.0005), and smaller tumor volume (p = 0.02). Patients in the SRS group had more favorable prognostic factors, with median age of 48 years, KPS of 70, and tumor volume of 10 ml versus median age of 53 years, KPS of 60, and tumor volume of 25 ml in the FSRT group. Late complications developed in 14 patients in the SRS group and 2 patients in the FSRT group (p<0.05). CONCLUSION: Given that FSRT patients had comparable survival to SRS patients, despite having poorer pretreatment prognostic factors and a lower risk of late complications, FSRT may be a better option for patients with larger tumors or tumors in eloquent structures. Since this is a nonrandomized study, further investigation is needed to confirm this and to determine an optimal dose/fractionation scheme.

Adolescent↗
PubMed1999

Radiographic incidence of multicentric malignant gliomas.

BACKGROUND: Multicentric malignant gliomas are interesting yet uncommon clinical entities with an unknown rate of occurrence. METHODS: We reviewed the computed tomography (CT) and magnetic resonance (MR) images of 100 consecutive patients with malignant gliomas to determine the incidence of multicentricity in malignant glial neoplasms. RESULTS: Five patients had multiple lesions on their initial radiographic study (synchronous lesions) and in four patients multiplicity developed after initial diagnosis (metachronous lesions). MR imaging demonstrated one lesion not seen on CT. CONCLUSIONS: Because synchronous or metachronous multicentricity was found in 9% of patients with malignant gliomas, treatment delivery should not be based on radiographic imaging without attempting to obtain an accurate diagnosis of the ongoing intracranial process.

Adult↗