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Charles L Truwit

Publications and source records attributed to Charles L Truwit.

17 recordsLinked to original sources
PubMed2006

Intraoperative magnetic resonance imaging-guided neurosurgery at 3-T.

OBJECTIVE: Between 1997 and 2004, more than 700 neurosurgical procedures were performed in a 1.5-T magnetic resonance-guided therapy suite. During this period, the concept of high-field intraoperative magnetic resonance imaging (MRI) was validated, as was a new surgical guidance tool, the Navigus (Image-guided Neurologics, Melbourne, FL), and its methodology, prospective stereotaxy. Clinical protocols were refined to optimize surgical techniques. That implementation, the "Minnesota suite," has recently been revised, and a new suite with a 3-T MRI scanner has been developed. METHODS: On the basis of experience at the initial 1.5-T suite, a new suite was designed to house a 3-T MRI scanner with wide surgical access at the rear of the scanner (opposite the patient couch). Use of electrocautery, a fiberoptic headlamp, a power drill, and MRI-compatible neurosurgical cutlery was anticipated by inclusion of waveguides and radiofrequency filter panels that penetrate the MRI suite's radiofrequency shield. An MRI-compatible head holder was adapted for use on the scanner table. A few items exhibiting limited ferromagnetism were used within the magnetic field, taking strict precautions. RESULTS: During the initial procedures (all magnetic resonance-guided neurobiopsies), the new suite functioned as anticipated. Although metallic artifact related to titanium needles is more challenging at 3 T than at 1.5 T, it can be contained even at 3 T. Similar to 1.5 T, such artifact is best contained when the device is oriented along B0, the main magnetic field. Surgical needles, disposable scalpels, and disposable razors, despite being minimally ferromagnetic, were easily controlled by the surgeon. CONCLUSION: An intraoperative magnetic resonance-guided neurosurgical theater has been developed with a 3-T MRI scanner. Intraoperative imaging is feasible at this field strength, and concerns regarding specific absorption rate can be allayed. Infection control procedures can be designed to permit neurosurgery within this environment. Despite the increase in magnetic field strength, safety can be maintained.

Brain Diseases↗
PubMed2005

3-Tesla intraoperative MR imaging for neurosurgery.

Intraoperative magnetic resonance (MR) image-guided neurosurgery has been performed since 1994. Using a 1.5-Tesla (T) intraoperative MR imaging system, we have performed more than 750 interventional procedures. Having validated the safety and efficacy of this surgical technique that is relatively amenable to nearly all new in-hospital MR suites, we sought to adapt this approach at our sister hospital where a new short-bore 3-T MR suite was being installed. Using many of the lessons learned from our initial experience at 1.5-T, we designed a new interventional suite that would enable surgery to be performed entirely within a 3-T MR environment. All surgical instrumentation including electrocautery, fiberoptic headlamp, power drill, and ultrasonic aspirator was entirely MR-compatible. A few items with limited ferromagnetism were utilized within the magnetic field under strict precaution. From 2/04 to 7/05, those cases initially performed within the 3-T surgical suite included one drainage and reservoir placement for a cystic craniopharyngioma, five brain biopsies and two craniotomies; one for open brain biopsy and another for lesion resection. The craniopharyngioma was successfully aspirated and had the reservoir catheter placed within the cyst. All five brain biopsies yielded diagnostic tissue. The craniotomy for mass resection demonstrated radiation necrosis. Although the metallic artifact from the biopsy needle was more prominent than at 1.5-T, accurate image interpretation was possible. Surgical needles, disposable scalpel, disposable razor, and surgical stapler were minimally ferromagnetic and safely controlled by the surgeon. There were no adverse events associated with any procedure. MR-guided neurosurgery can be safely and effectively performed at 3-T. The surgical environment at 3-T is comparable to that present at 1.5-T.

Adult↗
PubMed2005

Carotid bifurcation calcium and correlation with percent stenosis of the internal carotid artery on CT angiography.

The aim of this paper was to determine the correlation between calcium burden (expressed as a volume) and extent of stenosis of the origin of the internal carotid artery (ICA) by CT angiography (CTA). Previous studies have shown that calcification in the coronary arteries correlates with significant vessel stenosis, and severe calcification (measured by CT) in the carotid siphon correlates with significant (greater than 50% stenosis) as determined angiographically. Sixty-one patients (age range 50-85 years) underwent CT of the neck with intravenous administration of iodinated contrast for a variety of conditions. Images were obtained with a helical multidetector array CT scanner and reviewed on a three-dimensional workstation. A single observer manipulated window and level to segment calcified plaque from vascular enhancement in order to quantify vascular calcium volume (cc) in the region of the bifurcation of the common carotid artery/ICA origin, and to measure the extent of ICA stenosis near the origin. A total of 117 common carotid artery bifurcations were reviewed. A "significant" stenosis was defined arbitrarily as >40% (to detect lesions before they become hemodynamically significant) of luminal diameter on CTA using NASCET-like criteria. All "significant" stenoses (21 out of 117 carotid bifurcations) had measurable calcium. We found a relatively strong correlation between percent stenosis and the calcium volume (Pearson's r = 0.65, P<0.0001). We also found that there was an even stronger correlation between the square root of the calcium volume and the percent stenosis as measured by CTA (r= 0.77, P<0.0001). Calcium volumes of 0.01, 0.03, 0.06, 0.09 and 0.12 cc were used as thresholds to evaluate for a "significant" stenosis. A receiver operating characteristic (ROC) curve demonstrated that thresholds of 0.06 cc (sensitivity 88%, specificity 87%) and 0.03 cc (sensitivity 94%, specificity 76%) generated the best combinations of sensitivity and specificity. Hence, this preliminary study demonstrates a relatively strong relationship between volume of calcium at the carotid bifurcation in the neck (measured by CT) and percent stenosis of the ICA below the skull base (as measured by CTA). Use of calcium volume measurements as a threshold may be both sensitive and specific for the detection of significant ICA stenosis. The significance of the correlation between calcium volume and ICA stenosis is that potentially a "score" can be obtained that will identify those at risk for high grade carotid stenosis.

Aged↗
PubMed2005

Multi-slice CT angiography of small cerebral aneurysms: is the direction of aneurysm important in diagnosis?

PURPOSE: Multi-slice CT (MSCT) has great potential in evaluation of vascular structures. Our purpose was to investigate if there is any difference in detection of superiorly, inferiorly and horizontally directed small cerebral aneurysms (<5 mm) on MSCTA compared to digital subtraction angiography (DSA) or surgery. MATERIALS AND METHODS: One hundred and three consecutive patients who underwent MSCTA and DSA or surgery were included in the study. MSCTA and DSA results were evaluated independently by two different neuroradiologists who performed aneurysm detection, quantitation, and characterization using 2D multiplanar reconstructions, 3D maximum intensity projection and volume-rendered techniques. FINDINGS: MSCTA detected 49 small cerebral aneurysms (<5 mm) in 37 (36%) of 103 patients. The overall sensitivity, specificity, and accuracy of MSCTA for detecting small aneurysms were 0.85, 0.65, and 0.79, respectively. There was moderate agreement between MSCTA and DSA/surgery for detecting small aneurysms (kappa: 0.51). The sensitivity of detecting small aneurysms directed superiorly, inferiorly and horizontally was 0.94, 0.84, and 0.75, respectively. There was no statistically significant difference in detection between small aneurysms directed superiorly, inferiorly and horizontally on MSCTA (P > 0.05). CONCLUSION: The direction of small cerebral aneurysms is not important in diagnosis on multi-slice CT scanners, although the detection of small cerebral aneurysms with superior or inferior direction is slightly easier than the detection of horizontally directed aneurysms.

Adult↗
PubMed2005

Intraoperative MR imaging.

With the rapid evolution of technologic advances in neurosurgery, it is no surprise that the use of MR imaging to guide the performance of safe and effective surgical procedures is at the forefront of development. This article highlights the current capabilities of intraoperative MR-guided surgery for a variety of neurosurgical procedures and traces the evolution of the field to its present level of technical sophistication. The costs of intraoperative MR imaging and its future directions are discussed.

Biopsy↗
PubMed2005

1.5 T: spectroscopy-supported brain biopsy.

The technique for performing brain biopsy has evolved significantly over the last three decades. Intraoperative MRI guidance has enhanced the diagnostic rate for brain biopsy by now allowing neurosurgeons to compensate for brain shift while performing the procedure in near-real time. The development of a trajectory guide enables the neurosurgeon to determine a safe and accurate path for intraoperative MRI-guided brain biopsy and to secure the position of the needle within the target tissue. Magnetic resonance spectroscopy (MRS) has been used to help distinguish recurrent brain tumor from the effect of previous treatments by measuring specific metabolites within the area of concern. Combining the use of a trajectory guide with MRS should enhance the diagnostic yield for MRI-guided brain biopsy.

Biopsy↗
PubMed2005

Functional magnetic resonance imaging-guided resection of low-grade gliomas.

BACKGROUND: We sought to determine the safety and efficacy of using functional magnetic resonance imaging (fMRI) to guide the resection of low-grade gliomas (LGG). METHODS: From September 1997 to February 2003, fMRI was performed in 16 patients (age, 15-43 years) before an attempted surgical resection of LGG. Functional imaging was used to identify and coregister eloquent cortices pertinent to motor (10), speech (3), motor and speech (2), and short-term memory and speech (1) activation with respect to the tumor using a 1.5-T interventional MRI system. Intraoperatively acquired T(2)-weighted and turbo-fluid attenuated inversion recovery images were used to assess the completeness of surgical resection. RESULTS: Tumors included 10 oligodendrogliomas, 4 astrocytomas, 1 dysembryoplastic neuroepithelial tumor, and 1 pleomorphic xanthoastrocytoma. In every case, the preoperative brain activation study accurately determined the location of neurologic function. After surgery, one patient had a transient hemiparesis and another had a temporary apraxia. Ten patients had radiographically complete resections and 5 with oligodendrogliomas had incomplete resections because of the proximity of their tumors to functional areas. Only one patient with an astrocytoma in the motor strip received postoperative radiation therapy. To date, radiographic tumor progression has not been seen in any patient with either a partial or a complete resection with a median follow-up of 25 months (range, 12-87 months). CONCLUSIONS: Functional MRI was accurate for identifying areas of neurologic function before surgical resection of LGG. Patients with complete radiographic resections or with incompletely resected oligodendrogliomas can be safely followed radiographically after surgery. Radiation therapy was reserved for infiltrating astrocytomas that were not completely resectable.

Adolescent↗
PubMed2005

Transalar encephalocele associated with Wegener granulomatosis and meningeal enhancement: case report.

Transalar encephaloceles are rare lesions that do not fit the standard classification of basal encephaloceles. Typically, these lesions present in adulthood, with nonspecific symptoms. We report here a case of a patient with Wegener disease in whom a large transalar encephalocele posterior to the sinus was noted when he was preoperative for left maxillary sinus surgery. The encephalocele demonstrated irregular peripheral enhancement along the margin--a very uncommon finding--as well as contrast enhancement of the basal meninges, which can be seen occasionally with Wegener granulomatosis.

Encephalocele↗
PubMed2004

Multi-slice CT angiography in evaluation of extracranial-intracranial bypass.

Multi-slice CT (MSCT) scanners provided significant improvement in vascular applications. In this study, our purpose was to determine the clinical utility of MSCTA in evaluation of extracranial-intracranial (EC-IC) bypass patency. Eleven (4 men and 7 women; mean age, 46 years; age range, 19-68 years) consecutive patients who underwent MSCTA and DSA after EC-IC bypass surgery were evaluated retrospectively. All patients underwent DSA within 3 weeks of MSCTA. The indications for EC-IC bypass were severe stenosis or occlusion of intracranial arteries in seven patients and therapeutic occlusion of intracranial artery for unclippable giant aneurysm in four patients. Ten patients underwent superficial temporal artery (STA)-middle cerebral artery (MCA) bypass and one patient underwent occipital artery-posterior cerebral artery (PCA) bypass. Eight STA-MCA bypasses in six patients were patent on MSCTA which were confirmed on DSA. Two STA-MCA bypasses and one occipital artery-posterior cerebral artery (PCA) bypass were occluded in three patients on MSCTA and DSA. In one patient, minimal stenosis of the STA-MCA bypass was identified on MSCTA and DSA. In 1 patient, STA-MCA bypass was not well seen on MSCTA and suspected for occlusion. DSA identified the occlusion of bypass on this patient. MSCTA seems to be a very promising noninvasive technique in evaluation of EC-IC bypass.

Adult↗
PubMed2004

Multi-section CT angiography for detection of cerebral aneurysms.

BACKGROUND AND PURPOSE: Multi-section CT has great potential for use in vascular studies. Our purpose was to determine the accuracy of multi-section CT angiography in detecting cerebral aneurysms compared with digital subtraction angiography or surgery. METHODS: One hundred consecutive patients who underwent multi-section CT angiography and either digital subtraction angiography or surgery were included in the study. Multi-section CT angiography and digital subtraction angiography results were evaluated independently by different neuroradiologists who performed aneurysm detection, quantitation, and characterization by using 2D multiplanar reconstructions, 3D maximum intensity projection, and volume-rendered techniques. RESULTS: When using intra-arterial digital subtraction angiography or surgery, 113 aneurysms (true positives and false negatives) were detected in 83 of the 100 patients. A total of 106 aneurysms (true positives) were confirmed by using digital subtraction angiography or surgery, or both. Seven aneurysms were missed when using multi-section CT angiography. Eight aneurysms were not confirmed by digital subtraction angiography and were considered to be false positive evaluations. The sensitivity for detecting aneurysms < 4 mm, 4 to 10 mm, and > 10 mm on a per-aneurysm basis was 0.84 (95% confidence interval: 0.72, 0.92), 0.97 (95% confidence interval: 0.91, 0.99), and 1.00 (95% confidence interval: 0.88, 1.00), respectively. The sensitivity, specificity, and accuracy of multi-section CT angiography for detecting aneurysms on a per-patient basis were 0.99 (95% confidence interval: 0.96, 1.00), 0.88 (95% confidence interval: 0.69, 0.94), and 0.98 (95% confidence interval: 0.95, 1.00), respectively. CONCLUSION: Multi-section CT angiography has a high sensitivity in detecting aneurysms (especially aneurysms > 3 mm). However, CT angiography is currently not sensitive enough to replace digital subtraction angiography.

Adult↗
PubMed2003

Application of diffusion tensor imaging to magnetic-resonance-guided brain tumor resection.

Interventional magnetic resonance imaging (MRI) continues to make a profound impact on the practice of neurosurgery. We describe a new MRI modality, diffusion tensor imaging (DTI), which uses the diffusion energy of water to map white matter fibers. DTI has been established in other disorders such as metabolic, demyelinating and ischemic diseases. We describe the use of DTI in identifying white matter tracts such as optic radiations and avoiding them intraoperatively in 2 children with low-grade glial tumors.

Adolescent↗
PubMed2003

Intraoperative MR-guided instillation of phosphorus-32 for cystic craniopharyngiomas: case report.

Intraoperative magnetic resonance imaging has been applied to a number of neurosurgical disease processes since the late 1990's. The ability to visualize the operative site in near-real time has added a significant degree of safety to the treatment of lesions such as a cystic craniopharyngioma which can be located in regions of the brain where an untoward consequence can result in significant neurological morbidity. Previous surgical techniques, although often successful, did not allow the neurosurgeon to directly visualize whether the goals of surgery had been met or whether there was an inadvertent complication associated with the surgical approach until after the event had occurred. The safe and accurate instillation of radioactive phosphorus into this cystic tumor resulted in clinical improvement and the maintenance of normal pituitary function for this patient. The extreme accuracy and safety of this surgical technique is demonstrated by the imaging examples provided.

Craniopharyngioma↗
PubMed2003

Anatomy and frequency of large pontomesencephalic veins on 3D CT angiograms of the circle of Willis.

BACKGROUND AND PURPOSE: The pontomesencephalic veins (PMVs), especially the anterior PMV, are sometimes large enough that they could potentially affect the interpretation of CT angiograms of the circle of Willis. We investigated the frequency and anatomy of visible PMVs on 3D CT angiograms. METHODS: CT angiograms of 211 consecutive patients who underwent CT angiography for a variety of clinical indications were evaluated retrospectively. Images evaluated by consensus between two neuroradiologists were maximum intensity projection and volume-rendered 3D CT angaiograms. RESULTS: Visible PMVs were present on 3D CT angiograms in 11 (5.2%) of 211 patients. Eight of 11 patients had a visible anterior PMV behind the basilar artery. In four patients, the venous caliber of the anterior PMV was sufficiently large enough to be potentially confused with arterial structures. In one patient, 3D CT angiography revealed a large anterior PMV (approximately 2.6 mm in diameter) in the interpeduncular cistern, which had been mistaken for subarachnoid hemorrhage on a nonenhanced CT scan. Two patients had interpeduncular veins of the anterior PMV draping over the dome of a basilar tip aneurysm. In only one patient was the anterior PMV visible possibly owing to arteriovenous malformation. One patient had visible lateral mesencephalic veins, and four patients had visible transverse pontine veins. In one case, on certain views, the transverse pontine veins appeared to arise from the basilar artery. CONCLUSION: Because of their small size, PMVs were seen only infrequently on 3D CT angiograms, but neuroradiologists should be familiar with the normal variants of large PMVs to avoid diagnostic and anatomic confusion.

Artifacts↗
PubMed2002

Remotely-controlled approach for stereotactic neurobiopsy.

The objective of this study was to develop, demonstrate, and validate a remotely controlled operation scheme coupled with prospective magnetic resonance imaging (MRI)-based stereotaxy for in vivo neurosurgical applications. The novel concept of the prospective guidance scheme is to employ tomographical imaging feedback, such as MRI or CT, to facilitate prospectively the targeting process of a biopsy needle at near-real-time speed (1 image/s). Because the orientation of a biopsy needle pivoted at an entry point on the patient's skull has 2 degrees of freedom, the alignment of its trajectory to a target point can be guided by two-dimensional (2D) images whose plane is placed perpendicular to the desired trajectory. Using near-real-time 2D visual feedback during the adjustment of the alignment guide, the required trajectory alignment can be translated into a simple targeting task on a computer monitor employing a suitable graphic presentation. Also, both adjustments for the alignment and introduction of the biopsy needle were accomplished remotely with image-based feedback. The use of the method in actual MR-guided brain lesion biopsy procedures at 1.5 T showed an improved tissue yield due to the improved targeting accuracy even in the presence of brain shift. Furthermore, the postalignment trajectory can be validated immediately using near-real-time MRI scans in two orthogonal views before needle insertion. Because the final needle position is always visualized and confirmed, the consequent tissue sampling is performed with greater certainty, even in the case of a negative diagnosis. The actual targeting error was 1.53 +/- 0.17 mm from an intended target location, with the maximum distance error of 1.72 mm at a depth of 85 mm. This remotely controlled surgical approach with intraoperative MRI guidance is feasible at 1.5 T, and has allowed neurosurgeons to perform neurobiopsies comfortably and efficiently in a routine clinical MR scanner. This scheme provides a unique alternative stereotactic procedure that can take full advantage of the prospective guidance potential offered by various modern tomographic imaging systems.

Biopsy, Needle↗
PubMed2002

Radiology of nonaccidental trauma.

The long-term outlook for infants subjected to nonaccidental trauma is bleak. In a retrospective study with a mean 9-year follow-up, Duhaime et al [63] noted the relationship between acute factors on presentation and the long-term outcome. Infants who were unresponsive on presentation remained vegetative or severely impaired at follow-up. Most of the infants who required intubations were severely impaired at follow-up. In those with acute seizures, 60% were severely impaired, and an equal number had moderately severe to good outcome. Less than 6 months of age at the time of insult resulted in severe disability in most infants. CT findings of diffuse hypodensity or loss of gray-white differentiation led to severe disability at follow-up. Focal areas of hypodensity or contusion had an equal probability of good outcome or severe disability. Child abuse unfortunately is prevalent in our society, and as physicians our profession requires that we help our patients. When dealing with one of our most vulnerable group of patients, it is imperative when a child with injury is examined that physicians keep in their differential child abuse. This article has provided information in regards to radiographic studies that assist a physician in diagnosing child abuse. The importance of this not only is in providing appropriate care, but far more importantly in protecting a child or his or her siblings from future abuse.

Brain Injuries↗
PubMedDate not supplied

Diffusion-weighted imaging in the setting of diffuse cortical laminar necrosis and hypoxic-ischemic encephalopathy.

BACKGROUND AND PURPOSE: As is the case for CT scans, MR images may occasionally appear deceptively normal unless proper windowing is used. We sought to illustrate the necessity for proper windowing and for assessing the gray-white matter differentiation on diffusion-weighted (DW) images in the setting of hypoxic-ischemic encephalopathy. METHODS: Six comatose patients (age range, 34-56 years) underwent MR imaging in the early phase (range, 1-5 days) after severe anoxic insult. T2-weighted, turbo fluid-attenuated inversion-recovery, and DW images were obtained in all six patients, with contrast-enhanced T1-weighted images obtained in four and apparent diffusion coefficient (ADC) maps in five of the six patients. RESULTS: At presentation, each of the six patients had symmetric, uniform hyperintensity in the cortex (mean ADC, 0.35 x 10(-3) mm(2)/s) relative to the white matter (mean ADC, 0.91 x 10(-3) mm(2)/s) on DW images. Each also had a poor outcome: brain death in four patients and a permanent vegetative state in two patients. CONCLUSION: The appearance of the MR images in the setting of diffuse cortical laminar necrosis can be deceptive to the unwary radiologist. The key to correct interpretation is proper windowing and the marked gray-white matter differentiation on spin-echo images but best seen on properly windowed DW images in the early subacute phase. This appearance also implies an extremely poor outcome, either a permanent vegetative state or brain death.

Adult↗