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C L Truwit

Publications and source records attributed to C L Truwit.

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

Perfusion MR neuroimaging in patients undergoing balloon test occlusion of the internal carotid artery.

BACKGROUND AND PURPOSE: We sought to investigate whether the combination of conventional, diffusion-weighted, and perfusion-weighted MR imaging increases the diagnostic accuracy of balloon test occlusion of the internal carotid artery. We describe perfusion anomalies and patterns of enhancement seen in areas of altered brain perfusion during MR-monitored temporary balloon occlusion of the internal carotid artery. METHODS: Nine patients underwent balloon occlusion testing under standard angiographic conditions with continuous clinical and EEG monitoring. One patient who failed the test by clinical criteria underwent an external carotid to internal carotid bypass operation, followed by a repeat balloon test occlusion, thereby bringing the total number of procedures to 10. Patients were further imaged at 1.5 T with perfusion- and diffusion-weighted imaging as well as with conventional noncontrast and contrast-enhanced turbo fluid-attenuated inversion recovery (FLAIR) and T1-weighted sequences. RESULTS: Seven of 10 patients who tolerated unilateral carotid test occlusion without adverse clinical neurologic or EEG changes exhibited delayed first-pass transit of contrast material through the affected cerebral hemisphere, indicative of altered perfusion without significant concurrent cerebral blood flow or blood volume changes. Four of these patients and both symptomatic patients showed pial or subarachnoid contrast staining in areas of altered perfusion without abnormalities on diffusion-weighted images. CONCLUSION: Our findings indicate that MR perfusion-weighted imaging is safe and easily accomplished in a high-field-strength magnet and that contrast-enhanced turboFLAIR imaging may provide clinically useful MR imaging evidence of abnormal cerebral blood flow and subclinical ischemia.

Adult↗
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

Minimally invasive procedures. Interventional MR image-guided functional neurosurgery.

Intraoperative MR imaging techniques have the potential to greatly improve the stereotactic methods used for functional neurosurgery. No longer are neurosurgeons and patients always constrained by uncomfortable head frames and conventional stereotaxy. Accuracy and complication avoidance are improved by intraoperative imaging. Safety of operative machinery and equipment in an MR imaging operative suite is attainable, even with deep brain stimulating electrodes in depth electrodes for epilepsy. Although cost-effectiveness remains to be determined (see article by Kucharczyk et al in this issue), the minor inconveniences of operating within an iMRI environment seem to be significantly outweighed by the benefits.

Brain↗
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

Functional neuroanatomy of spatial working memory in children.

Functional magnetic resonance imaging (fMRI) was used to examine spatial working memory in 8- to 11-year-old children tested under three conditions. In the visual condition, children were asked to examine the location of a dot on a screen. In the motor condition, children were instructed to push a button that corresponded to the location of a dot presented on a screen. In the memory condition, children were asked to remember the location of a dot presented 1 or 2 trials previously. Subtracting the activation of the motor condition from the memory condition revealed activity in the dorsal aspects of the prefrontal cortex and in the posterior parietal and anterior cingulate cortex. These findings were also obtained in the analysis of the memory minus visual conditions except that motor cortex activation was also observed. These findings parallel those reported in comparable studies of adults and suggest that fMRI may be a useful means of examining function-structure relations in developmental populations.

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

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↗
PubMed2000

Posterior reversible encephalopathy syndrome: utility of fluid-attenuated inversion recovery MR imaging in the detection of cortical and subcortical lesions.

BACKGROUND AND PURPOSE: Posterior reversible encephalopathy syndrome (PRES) is typically characterized by headache, altered mental functioning, seizures, and visual loss associated with imaging findings of bilateral subcortical and cortical edema with a predominantly posterior distribution. Our goal was to determine whether fluid-attenuated inversion recovery (FLAIR) imaging improves the ability to detect subtle peripheral lesions of PRES, as compared with conventional MR techniques. METHODS: Sixteen patients with clinical and imaging findings consistent with PRES were studied. Thirteen patients had undergone transplantation and had cyclosporin A neurotoxicity. Fast-FLAIR images were compared with spin-echo proton density- and T2-weighted images. RESULTS: FLAIR imaging improved diagnostic confidence and conspicuity of the T2 hyperintense lesions of PRES, typically in the subcortical white matter of the parietooccipital regions bilaterally. On all 23 abnormal MR studies, FLAIR was judged superior to proton density- and T2-weighted images for the detection of PRES in the supratentorial brain. In a mean of 6.7 of 23 studies, FLAIR findings prompted a raise in the grade of disease severity. FLAIR also showed cortical involvement in 94% of patients with PRES and in a mean of 46% of the total lesion burden. In four cases, subtle lesions were virtually undetectable without FLAIR. Brain stem or cerebellar disease was encountered in 56% of patients. CONCLUSION: FLAIR improves the ability to diagnose and detect subcortical and cortical lesions in PRES as compared with proton density- and T2-weighted spin-echo images. We therefore believe that FLAIR should be performed in patients with suspected PRES to allow more confident recognition of the often subtle imaging abnormalities.

Adolescent↗
PubMed1999

Differences in the gyral pattern distinguish chromosome 17-linked and X-linked lissencephaly.

BACKGROUND: Classical lissencephaly or "smooth brain" is a human brain malformation that consists of diffuse agyria and pachygyria. Two genes associated with classical lissencephaly have recently been cloned-LIS1 from chromosome 17p13.3 and XLIS (also called DCX) from Xq22.3-q23. OBJECTIVE: We performed genotype-phenotype analysis in children with lissencephaly associated with mutations of different genes. METHODS: We compared the phenotype, especially brain imaging studies, in a series of 48 children with lissencephaly, including 12 with Miller-Dieker syndrome (MDS), which is associated with large deletions of LIS1 and other genes in the region, 24 with isolated lissencephaly sequence caused by smaller LIS1 deletions or mutations, and 12 with isolated lissencephaly sequence caused by XLIS mutations. RESULTS: We found consistent differences in the gyral patterns, with the malformation more severe posteriorly in individuals with LIS1 mutations and more severe anteriorly in individuals with XLIS mutations. Thus, mutations of LIS1 are associated with a posterior-to-anterior gradient of lissencephaly, whereas mutations of XLIS are associated with an anterior-to-posterior gradient. We also confirmed differences in severity between MDS and ILS17. Hypoplasia of the cerebellar vermis proved to be more common with XLIS mutations. CONCLUSION: It is often possible to predict the gene mutation from careful review of brain imaging studies.

Brain↗
PubMed1999

MRI compatibility and visibility assessment of implantable medical devices.

We have developed a protocol to evaluate the magnetic resonance (MR) compatibility of implantable medical devices. The testing protocol consists of the evaluation of magnetic field-induced movement, electric current, heating, image distortion, and device operation. In addition, current induction is evaluated with a finite element analysis simulation technique that models the effect of radiofrequency fields on each device. The protocol has been applied to several implantable infusion pumps and neurostimulators with associated attachments. Experiments were performed using a 1.5-T whole-body MR system with parameters selected to approximate the intended clinical and worst case configuration. The devices exhibited moderate magnetic field-induced deflection and torque but had significant image artifacts. No heating was detected for any of the devices. Pump operation was halted in the magnetic field, but resumed after removed. Exposure to the magnetic field activated some of the neurostimulators.

Artifacts↗