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Biomedical subjects

G Duckwiler

Publications and source records attributed to G Duckwiler.

48 records · Page 3Linked to original sources
PubMed1990

Persistent primitive trigeminal artery-cavernous sinus fistulas: report of two cases.

Two cases of persistent primitive trigeminal artery-cavernous sinus fistulas are presented. In one case, the fistula was treated by using a two-balloon tandem technique. This method was accomplished by introducing, inflating, and detaching a silicone balloon into the trigeminal artery, thus preserving the carotid and basilar blood flow. An unusual case of a similar fistula with only contralateral exophthalmos is also reported. The relationship between this type of fistula and the presence of aneurysms on the persistent primitive trigeminal artery and the relationship with traumatic events are discussed.

Adult↗
PubMed1990

Interventional magnetic resonance imaging in the head and neck.

Interventional MRI is clearly in its early stages of development. While the value of MR-guided aspiration cytology and MR evaluation of deep electrode implantation in the brain has already been confirmed with human clinical studies, the future of MR-guided interstitial laser therapy remains to be proven. Despite this, as we look ahead into the 1990s and the millennium, it is possible to imagine dedicated MR laser therapy units for combined radiological and surgical outpatient approaches in what may become the operating rooms of the 21st century.

Biopsy, Needle↗
PubMed1989

Head and neck lesions: MR-guided aspiration biopsy.

Aspiration biopsy guided with computed tomography (CT) has long been a valuable tool in the evaluation of head and neck disease. The ability to obtain diagnoses without the need for surgery has had a significant effect on patient treatment. Magnetic resonance (MR) imaging is now rapidly replacing CT as the primary imaging study for many head and neck diseases. The standard stainless steel needles used for CT-guided biopsy are unsuitable for MR-guided biopsy because significant ferromagnetic artifacts obscure the underlying anatomy. A new needle has recently been designed specifically for use with MR imaging. This needle has far less magnetic susceptibility and therefore does not cause significant image distortion. The authors describe the use of this needle in MR-guided aspiration biopsy of a variety of lesions in the head and neck.

Adult↗
PubMed1989

Cranial arteriovenous malformations in neonates: color Doppler imaging with angiographic correlation.

Five neonates with cranial arteriovenous malformations were studied with color Doppler sonography. Excellent correlation was found between sonography and subsequent angiography. In three patients with vein of Galen aneurysms, sonography showed a cystic structure with rapid or swirling flow. Careful adjustment of the color Doppler system was required to demonstrate flow in another patient with a dural arteriovenous malformation. An arteriovenous fistula in a fifth patient appeared as an area of increased flow. Arterial feeders and major draining veins were visualized in all five patients. Color Doppler imaging also was used to assess the effect of embolic or operative therapy in three of the patients. We conclude that color Doppler sonography is able reliably to characterize flow patterns in neonatal cranial arteriovenous malformations. Color Doppler imaging also is helpful in assessing flow after embolic or surgical therapy.

Cerebral Angiography↗
PubMed1989

MR-directed needle biopsies.

New generation stainless steel alloys have enabled the development of needles which can be used for MR-guided biopsies. Biopsy under MR guidance has the advantages of greater tissue contrast resolution, lack of ionizing radiation, and variable angle oblique imaging planes. The biopsy approaches and imaging techniques are described.

Adult↗
PubMed1987

MR imaging of the knee. Part I. Traumatic disorders.

One hundred thirty patients with a diversity of knee joint injuries were evaluated with a high-resolution magnetic resonance (MR) imaging technique. The authors report the accuracy of this technique in the evaluation of 105 patients with suspected meniscal tears, 26 patients with suspected cruciate ligament tears, and eight patients with suspected patellar tendon injuries. Of those menisci rated as definitely or probably torn on MR imaging, 80% were found to be torn at subsequent arthroscopy. The predictive value of negative MR imaging results was 100%. MR imaging was 92% accurate in predicting the clinical outcome in patients with suspected meniscal tears who did not undergo surgery. MR permitted complete disruption of the patellar tendon to be differentiated from partial tears, ligamentous inflammation, and localized effusion of the infrapatellar bursa. Injuries to the anterior and posterior cruciate ligaments were identified on MR images, and the status of synthetic grafts of the anterior cruciate ligament was ascertained.

Humans↗
PubMedDate not supplied

The MR appearance of endovascular embolic agents in vitro with clinical correlation.

A spectrum of embolic agents including PVA, avitene, gelfoam, ethanol, IBCA, silicone microspheres, metal and platinum coils, and balloons containing contrast of HEMA were imaged in vitro at 0.3 Tesla using spin echo, gradient echo, and inversion recovery sequences. Signal intensities associated with these agents and changes created by addition of blood are presented. The in vitro model is also correlated with clinical MR material. Recognition of embolic materials is important to avoid confusion with persistent flow void, hemorrhage, or thrombus.

Adult↗
PubMedDate not supplied

Preembolization functional evaluation in brain arteriovenous malformations: the superselective Amytal test.

PURPOSE: To describe our experience with the use of Amytal injected through a superselective catheter prior to planned embolization of cerebral arteriovenous malformations. MATERIALS AND METHODS: 109 superselective tests were performed with 30-mg injections of Amytal. All patients were evaluated by both clinical examination and EEG. RESULTS: Twenty-three of these tests were positive. There were no prolonged neurologic complications of the Amytal test. We also examined the value of EEG monitoring compared to clinical monitoring during the Amytal test. Of the 23 positive Amytal tests, only 12 showed a change on clinical exam (52%). This meant that almost half of the positive Amytal tests would have been falsely called negative (false negative rate of 10%). There were also three positive Amytal tests with changes on clinical examination without any change on EEG. CONCLUSION: The superselective Amytal test can be done safely as part of the interventional neuroradiologic procedure. Clinical and EEG monitoring of the patient are essential.

Adolescent↗
PubMedDate not supplied

Preembolization functional evaluation in brain arteriovenous malformations: the ability of superselective Amytal test to predict neurologic dysfunction before embolization.

PURPOSE: To describe the incidence of neurologic dysfunction following embolization of supratentorial AVMs, and to correlate findings with results of preembolization Amytal tests. MATERIALS AND METHODS: Data from 147 embolizations of supratentorial AVMs following Amytal tests in 30 awake patients were analyzed retrospectively. RESULTS: Of five embolizations done after a positive Amytal test, two were followed by neurologic complications. Eighty-two embolizations done as single embolizations immediately after a negative Amytal test were associated with no neurologic complications. The remaining embolizations were parts of multiple series of embolizations, each beginning with an Amytal test and followed by a number of embolizations without catheter movement or repeat Amytal testing. Since any prior embolization in the series might reduce the sump effect of the AVM, embolic agent delivered later in the series could potentially reach functional brain tissue not fully tested by the Amytal test. Therefore, repeat embolizations (not immediately preceded by an Amytal test) were considered separately. In 60 repeat embolizations, six (10%) were associated with some neurologic complication. CONCLUSIONS: Repeat Amytal testing might detect the loss of sump effect as the AVM is embolized. We conclude that use of data from superselective Amytal tests adds to the safety of AVM embolizations and that repeat Amytal testing potentially could be valuable when serial embolization of a vessel is planned.

Adolescent↗
PubMedDate not supplied

Intravascular microcatheter pressure monitoring: experimental results and early clinical evaluation.

With the use of Tracker and Balt microcatheter systems, intravascular pressure measurements were obtained in an experimental animal model, establishing the reliability of mean blood pressure measurements from these microcatheter systems. In the experimental model, selective occlusion of branches of the external carotid artery with simultaneous pressure measurements showed significant and reproducible changes in intravascular pressures. Also, pharmacologic manipulation of the blood pressure with simultaneous microcatheter and 6-French catheter recordings demonstrated an accurate and linear response of the microcatheter systems to mean blood pressure as it varied from 30 to 130 mm Hg. Preliminary results in humans with vascular malformations yielded similar results. We studied two cases of brain arteriovenous malformations (AVMs), one sigmoid-transverse sinus dural AVM, and one brain arteriovenous fistula (AVF). In these four cases the pressure dropped substantially, approaching the level of the shunt. In the case of the brain AVF, pressures rose in the same vessel after embolization. In the case of the dural AVM, correlation of the venous pouch pressures and the angiographic appearance indicated that shunting was no longer present when the venous and arterial pressures equalized. This system can be of substantial benefit in the evaluation and therapy of these lesions, and may increase our understanding of the physiology of vascular malformations.

Animals↗
PubMedDate not supplied

MR body stereotaxis: an aid for MR-guided biopsies.

The use of a new body stereotactic system to facilitate magnetic resonance (MR) guided biopsies is described. A skin entry point is first found using a localizer MR scan. The articulating arm of the stereotactic unit is then used to aim the MR needle at the entry point and accurately maintain the needle at the correct angle to intersect the target area. Complex angles may be used to allow needle passes outside the scan plane. This is accomplished by angling the arm out of the plane of the section.

Biopsy↗