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Biomedical subjects

G V O'Reilly

Publications and source records attributed to G V O'Reilly.

At least 19 recordsLinked to original sources

Stereoscopic display of MR angiograms.

Recent developments in magnetic resonance (MR) allow high resolution imaging of flowing blood. To overcome the tomographic nature of conventional MR acquisitions, projection angiograms can be produced. These angiograms are similar in their display of blood vessels to plain film or digital subtraction angiograms. However, the three-dimensional information inherent in them is partly lost when single projections are viewed. We describe a method of three-dimensional display consisting of stereo pairs of the MR angiograms. With these an examiner experienced in stereo viewing can recover depth perception.

Carotid Artery, Internal↗

Magnetic resonance imaging of flow dynamics in the circle of Willis.

Magnetic resonance angiography was applied to the study of blood flow dynamics in the circle of Willis in nine patients with cerebrovascular disease and two normal volunteers. In conjunction with two-dimensional or three-dimensional gradient-echo acquisitions, selective presaturation of individual vessels was used to determine the direction of blood flow and the origin of the vascular supply. Presaturation causes signal loss within the territory supplied by the presaturated artery, without affecting vessels not crossing the presaturation slab. The results were correlated with those from transcranial Doppler sonography and conventional angiography. Magnetic resonance angiography was able to demonstrate the direction of blood flow, the presence or absence of collateral blood flow, and the blood supply to the pericallosal arteries, as well as the presence of a fetal posterior circulation. Magnetic resonance angiography is a noninvasive means for imaging the blood supply of the major intracranial arteries.

Adult↗

Embolization of solitary spinal metastases from renal cell carcinoma: alternative therapy for spinal cord or nerve root compression.

Four patients with a solitary vertebral metastasis from a renal cell carcinoma presented with acute spinal cord or nerve root compression. Because of the markedly hypervascular nature of the metastases it was decided to palliate the lesions by transarterial catheter embolization. The embolization reduced the venous blood pool within the tumors, resulting in progressive neurological improvement often lasting for 12 weeks or more. With such palliation, surgical decompression may be obviated, postponed, or at least made manageable.

Aged↗

Laser-induced thermal occlusion of berry aneurysms: initial experimental results.

An intravascular laser-catheter technique was used to occlude 12 experimental berry aneurysms, ranging in size from 4 X 3 mm to 8 X 6 mm (length X width), while the patency of adjacent arteries was preserved. A small steel cap on the end of an optical fiber was fluoroscopically positioned within the aneurysm. The cap was rapidly heated by the optical transmission of laser energy. This produced a thermal tissue reaction within the aneurysm, resulting in its occlusion. After treatment, the steel cap was detached atraumatically from the fiber and left as a permanent implant within the occluded aneurysm. This method has an advantage over the use of a bare-ended intravascular optical fiber because the steel cap provides a uniform distribution of thermal energy, thereby reducing the risk of unexpected perforation during treatment. The radiologic and histologic results of using this laser-catheter system were evaluated 1-21 weeks after treatment.

Animals↗

Intracerebral arteriovenous malformations: evaluation with selective MR angiography and venography.

Magnetic resonance (MR) angiography and spin-echo methods were used to evaluate intracerebral arteriovenous malformations (AVMs) in 10 patients. Spin-echo images obtained with flow presaturation demonstrated the nidus of the AVM in all cases, but it was difficult to determine feeding vessels. These vessels were directly visualized with three-dimensional MR angiography; their presence could be indirectly determined by means of selective presaturation of individual vessels, which resulted in a marked decrease in signal within the portion of the AVM supplied by that vessel. Vascular supplies from the internal carotid artery and anterior, middle, or posterior cerebral arteries were detected in all cases, but in three large malformations it was not possible to demonstrate small feeding vessels. MR angiograms were also helpful for further defining the nidus. The combination of MR angiographic and spin-echo methods provides information useful for therapeutic planning not provided by either technique alone.

Adult↗

Focal occlusion of the rabbit carotid artery by endovascular laser therapy.

Laser energy was fiberoptically transmitted into the carotid artery of a series of rabbits to induce an acute focal arterial occlusion. Temporary interruption of blood flow during the treatment was necessary to achieve an occlusion. The arterial occlusive effects of three wavebands of laser energy were compared and the violet band proved the most effective when using 0.3-0.5 Joules/second for 25-30 seconds. There was always the risk of vascular perforation during treatment when laser energy emission was from a bare-tipped optical fiber.

Animals↗

Biplane stereoscopic magnification cerebral angiography.

An angiographic system capable of simultaneous biplane stereoscopic magnification cerebral angiography was evaluated. Stereoscopic imaging improved the morphologic depiction of aneurysms and of arteriovenous malformations. In a series of 357 patients, procedure time was reduced because the initial biplane stereoscopic series was nearly always diagnostic, obviating the need for additional angiographic views.

Cerebral Angiography↗

Cerebral infarction: shortcomings of angiography in the evaluation of intracranial cerebrovascular disease in 25 cases.

We studied the utility and limitations of conventional cerebral angiography in 25 patients with cerebral infarction unassociated with extracranial cerebrovascular disease during a 7-year period. In only one-third of cases was the angiogram diagnostic, and in a single case it altered the pre-angiogram diagnosis by revealing a previously unsuspected embolus. Among the cases clinically diagnosed as cerebral emboli, the 2 confirmatory angiograms were performed early (within 48 hours), and demonstrated medium-large or large vessel filling defects. Two-thirds of the negative angiograms in the embolic clinical category were delayed, but there was no statistically relevant predilection for specific vessel size involvement. The category, primary cerebral vasculopathy, comprised the largest group, 10 in all, and one-half had angiographic confirmation despite time delays. Angiographic recognition was dependent on a characteristic picture of vascular involvement, and not on timing or vessel size predilection. Mitral valve prolapse figured prominently in the clinical cases of vasculopathy of uncertain etiology, which contained a total of 4 cases. The 3 cases with nondiagnostic angiograms were all delayed and demonstrated nonspecific radiographic changes. Clinically, these cases demonstrated signs or symptoms of autoimmune dysfunction, raising the specter of primary cerebral vasculopathy as a cause of cerebral infarction, in contrast to recurrent cerebral emboli.

Adult↗

Septation and focal dilatation of ventricles associated with cryptococcal meningoencephalitis.

A 35-year-old woman developed temporal lobe seizures. Isolated dilatation of the right temporal horn was demonstrated by computed tomography. She was asymptomatic for the next 10 months while on anticonvulsants before severe headaches, vomiting, and mental confusion prompted hospitalization. Both temporal horns were now dilated, there was marked periventricular edema, and cryptococci were cultured from the ventricular fluid. She succumbed after prolonged systemic and intrathecal antifungal therapy, having developed isolation and dilatation of both frontal horns and third and fourth ventricles. Cryptococcal or other fungal meningoencephalitis should be considered in the differential diagnosis of isolated dilatations of the ventricular chambers as noted in the present case.

Adult↗

Balloon occlusion of a recurrent carotid-cavernous fistula previously treated by carotid ligations.

A carotid-cavernous fistula recurred 16 years after a Hamby procedure. The recurrence was manifested by subarachnoid hemorrhage originating from dilated draining pial veins. The fistula was closed with a balloon catheter introduced through a patent remnant of the cervical carotid artery. Patients who have previously undergone Hamby trapping and embolization should be reassessed for an occult fistula that could predispose them to intracranial bleeding.

Adult↗

Intravascular laser coagulation of experimental aneurysms.

Rebleeding after aneurysmal subarachnoid hemorrhage has a 45 per cent mortality rate. The peak incidence is within 24 hours of the initial bleed. During the ensuing 2 weeks 20 per cent of patients with suffer a second hemorrhage. To avoid this, surgical treatment must be instituted promptly but, logistically, this is often difficult to implement. To this end, we have devised an intravascular laser-catheter technique that may provide expeditious treatment for intracranial aneurysms. We have coagulated experimental aneurysms in the rabbit carotid artery using laser energy transmitted through an intra-arterial optical fiber. The special fiber tip was positioned in the aneurysm by a catheter introduced from the femoral artery. Laser power of 750 mW and an exposure of 15 seconds caused aneurysm ablation leaving the feeding artery patent. To date, 4 experimental aneurysms have been occluded by this technique and long term histologic results are pending in this ongoing study.

Aneurysm↗

Spinal cord or nerve root compression in patients with malignant disease: CT evaluation.

Fifty patients with malignant disease were seen on an emergency basis because they showed clinical signs of spinal cord or nerve root compression. All were studied with high resolution computed tomography (CT) of the spine; in addition, myelography was performed on 10 of the patients. We found that 48 cases (96%) could be accurately diagnosed by CT alone. In two cases (4%) CT was inconclusive, but myelography was diagnostic; one proved to be cerebrospinal fluid seeding with nerve root involvement, and the other showed conus medullaris involvement. In the remaining eight cases studied by both techniques, correlation between CT and myelography was very good.

Adult↗

Transcatheter fiberoptic laser coagulation of blood vessels.

In ten rabbit ears the central auricular artery was percutaneously catheterized and subjected to doses of laser energy transmitted through a flexible optical fiber within the artery. Arterial occlusion was not produced in the initial three ears using energy levels less than 600 mW. Higher levels of laser energy, in the range of 800-1000 mW, caused arterial coagulation in six of the remaining seven rabbit ears. Serial observations by transillumination of the ears, postmortem angiography, and histologic examination demonstrated complete arterial ablation. The experiments showed that segmental arterial ablation is feasible using an intra-arterial optical fiber to direct laser energy to a specific arterial target. Technical refinements and potential therapeutic application are discussed.

Animals↗

Blow-out fractures of the orbit: a comparison of computed tomography and conventional radiography with anatomical correlation.

Orbital blow-out fractures were experimentally created in eight human cadavers. Each orbit underwent conventional radiographic studies, complex motion tomography, and computed tomographic examinations. A comparison of the three modalities was made. Anatomical correlation was obtained by dissecting the orbits. The significance of medial-wall fractures and enophthalmos is discussed. Limitation of inferior rectus muscle mobility is thought to be a result of muscle kinking associated with orbital fat-pad prolapse at the fracture site, rather than muscle incarceration. Blow-out fractures should be evaluated by computed tomographic computer reformations in the oblique sagittal plane.

Cadaver↗

Another look at blow-out fractures of the orbit.

Thirty cases of orbital floor blow-out fractures proven by tomography were retrospectively reviewed to determine the accuracy of the plain films. Using the maximum diameter from the tomograms, the area and volume of the fractures were calculated and correlated with the presence of diplopia and enophthalmos at the time of presentation and at subsequent follow-up. Nine of the 30 cases underwent surgical repair. Orbital floor fractures were recognized in 29 of 30 cases using only the 28 degrees Caldwell and Waters views. Routine tomography is unnecessary and should be reserved as a preoperative evaluation in patients with enophthalmos to establish the presence of a significant associated medial wall prolapse.

Adolescent↗

Experimental arterial aneurysms:modification of the production technique.

Vein pouches obtained from the external jugular vein were used to create experimental aneurysms on the carotid arteries of 13 rabbits and the abdominal aortas of 18 rabbits. Eighteen of these vein pouch aneurysms were grafted onto a linear incision in the artery; 13 of the aneurysms were grafted onto an elliptical incision. In 4 of the rabbits in which the vein pouch was grafted onto an elliptical arteriotomy in the carotid, a new approach for producing an intracranial aneurysm was attempted by relocating the aneurysm segment to the subarachnoid space at the cranial vertex. The results indicate that the aneurysms grafted onto an elliptical arteriotomy had a higher patency rate than the aneurysms grafted onto a linear arteriotomy in both the aortic and carotid models. Also, the attempt to produce an intracranial model demonstrated that short-term patency of the aneurysms could be achieved and that a two-stage approach to creating such aneurysms would be more appropriate than a one-stage approach.

Aneurysm↗