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D M Pelz

Publications and source records attributed to D M Pelz.

54 records · Page 3Linked to original sources
PubMed1986

Results of the international extracranial/intracranial bypass study. Implications for neuroradiologists.

A randomized trial to determine whether bypass surgery would benefit patients with appropriate atherosclerotic lesions followed 1377 patients for almost five years, and found no benefit from surgery. This negative result has a number of potential implications for neuroradiologists including the expectation for other randomized trials to be carried out, such as for carotid endarterectomy, and the need for neuroradiologists to carry out trials for embolization of cerebral arteriovenous malformations and angioplasty of stenotic cervical or cranial vessels. We are reminded that, ultimately, the clinical outcome is the real measure of procedures, not pretty pictures.

Cerebral Revascularization↗
PubMed1985

CT of multiple sclerosis: reassessment of delayed scanning with high doses of contrast material.

A prospective study involving 87 patients was carried out to evaluate the necessity for a high dose of contrast material in addition to delayed computed tomographic (CT) scanning for optimal detection of the lesions of multiple sclerosis in the brain. In patients with either clinically definite multiple sclerosis or laboratory-supported definite multiple sclerosis, CT scans were obtained with a uniform protocol. Lesions consistent with multiple sclerosis were demonstrated on the second scan in 54 patients. In 36 of these 54 patients, the high-dose delayed scan added information. These results are quite similar to those of a previous study from this institution using different patients, in whom the second scan was obtained immediately after the bolus injection of contrast material containing 40 g of organically bound iodine. The lack of real difference in the results of the two studies indicates that the increased dose, not just the delay in scanning, is necessary for a proper study.

Brain Diseases↗
PubMed1985

Stenotic and occlusive disease of the venous drainage system of deep brain AVM's.

Angiograms obtained prior to treatment in 53 cases of deep-seated cerebral arteriovenous malformations (AVM's) were retrospectively analyzed with particular attention to the topography of the AVM nidus and the venous drainage. The location of the lesion was determined by a combination of angiography and computerized tomography. Twenty-seven AVM's involved the basal ganglia and thalamus, 12 were located in the corpus callosum, six were intraventricular, and eight involved the mesencephalon and brain stem. Forty-one patients (77.3%) presented with intracranial hemorrhage. Vessel wall irregularities and/or stenosis of the system of the vein of Galen were observed in 14 cases, and occlusion of the deep venous system was present in seven cases. These AVM's showed numerous collateral venous pathways through enlarged medullary and cortical regional veins. There was dominant participation of the basal vein of Rosenthal in all cases. Unique local hemodynamic factors produced by the convergence of the draining veins of the AVM's into the vein of Galen and straight sinus may lead to a higher incidence of stenosis and/or occlusion of the venous drainage. The relatively high incidence of intracranial hemorrhage in these deep-seated AVM's may suggest a relationship between an increased incidence of intracranial bleeding and impaired venous outlets.

Adolescent↗
PubMed1985

Subependymal metastases of an extracranial malignancy.

We report a patient in whom subependymal metastases from a primary lung cancer were demonstrated by computed tomography of the head and in whom tissue correlation became available. To our knowledge, no such patient has previously been reported.

Aged↗
PubMed1985

A comparison of angiography, intravenous digital subtraction angiography and duplex ultrasound in the diagnosis of carotid artery atherosclerosis.

Duplex ultrasonography and intravenous digital subtraction angiography (IV-DSA) were used as the initial diagnostic studies in 124 patients referred for evaluation of neurological disorders possibly related to carotid bifurcation disease in the neck. Conventional angiograms were subsequently performed in 29 patients. Diagnostic images were obtained in 100% of the angiograms, 94% of the duplex ultrasonograms and 89% of the IV-DSA studies. Using the angiogram as the reference standard for plaque detection, duplex ultrasonography had a sensitivity of 0.93 and specificity of 0.83. Doppler velocity ratio alone was used to detect all patients with angiographically demonstrated disease but demonstrated a specificity of only 0.35. IV-DSA showed a sensitivity of 0.93 and specificity of 0.91. IV-DSA and duplex ultrasonography agreed in the assessment of degree stenosis in over 90% of cases and we conclude that these two modalities have approximately the same sensitivity and specificity for detecting atherosclerotic disease at the carotid bifurcations.

Adult↗
PubMed1984

Vertebrobasilar occlusion therapy of giant aneurysms. Significance of angiographic morphology of the posterior communicating arteries.

The clinical and angiographic records were reviewed for 71 patients with giant aneurysms of the posterior circulation, who underwent therapeutic occlusion of the basilar artery or both vertebral arteries. This treatment is used when the aneurysm neck cannot be surgically clipped, and occlusion of the parent artery is performed to initiate thrombosis within the lumen. In these cases, collateral blood flow to the brain stem is supplied mainly by the posterior communicating arteries. Consequently, their angiographic morphology (patency, size, and number) is demonstrated as a preoperative indicator of whether the patient will be able to tolerate vertebrobasilar occlusion. Vertebral angiograms with carotid artery compression (the Allcock test) will often be needed to provide this information. The data relating posterior communicating artery morphology to clinical outcome in 71 cases of attempted vertebrobasilar occlusion are presented. The use and accuracy of carotid artery compression studies are also discussed. It is essential for the radiologist to supply the neurosurgeon with this valuable information in every case of giant posterior circulation aneurysm.

Basilar Artery↗
PubMed1981

Alternate bleeding sites in suspected graft-enteric fistula.

Nine cases of suspected aortoenteric fistula in patients with previous aortic reconstructive surgery and gastrointestinal bleeding collected over 5 years were reviewed. Five cases had angiographic evidence of a fistula, later proven at surgery. One patient had a negative angiogram but a fistula was found at surgery. In two cases angiography demonstrated different bleeding sites and in one patient a bleeding source was found by a nonangiographic method. Therefore three (33%) of nine patients had sources of gastrointestinal bleeding other than aortoenteric fistula.

Adult↗
PubMedDate not supplied

Iohexol cerebral angiography. Multicenter clinical trial.

Ionic contrast media currently used in cerebral angiography frequently cause discomfort due to hyperosmolality. This double-blind, multicenter trial compared two ionic media, meglumine iothalamate and meglumine-Na diatrizoate, with the new nonionic agent, iohexol, in 277 patients undergoing cerebral angiography. Vital signs, cardiovascular changes, and neurologic status were evaluated before, during, and after injection. Patients were observed for adverse reactions for up to 24 hours following studies. Patient discomfort and image quality were evaluated. Visualization was good or excellent with all media studied. No significant physiological differences were observed between the ionic and iohexol groups, but fewer iohexol patients experienced large increases (greater than 20 mmHg) in systolic blood pressure. Iohexol patients experienced significantly less discomfort; ionic patients reported severe discomfort 21/2 times more often. This finding was attributed to iohexol's low osmolality. Iohexol may be indicated particularly for use in selective angiograms where discomfort is a factor and for patients suspected of having blood-brain barrier disruption.

Adult↗
PubMedDate not supplied

Digital subtraction angiography: current clinical applications.

The applications of digital subtraction angiography (DSA) in neurologic diagnosis have been evolving as clinical experience with this technology accumulates. Initial enthusiasm with the intravenous contrast material injections has been tempered by often equivocal results. Intravenous DSA (IV-DSA) is still an accurate screening technique for extracranial carotid atherosclerosis, comparable to duplex ultrasound. Intracranial imaging is less satisfying with intravenous injections but reliable information is available in the assessment of the venous sinuses and parasellar internal arteries. The future of DSA lies with intraarterial contrast injections, as this technique substantially decreases the risks and costs of definitive cerebrovascular investigation.

Aged↗
PubMedDate not supplied

MR imaging after surgery for vertebrobasilar aneurysm.

We examined the safety and utility of high-field MR in patients who had surgery for cerebral aneurysms of the vertebrobasilar system. Eighteen posterior (and three coincidental anterior) circulation aneurysms were treated. Twenty-one MR scans were obtained at a mean postoperative interval of 7.2 days. The mean size of the preoperative vertebrobasilar aneurysm was 2.2 cm; six were giant (greater than 2.5 cm) and eight were large (greater than 1.5, less than or equal to 2.5 cm). In 17 patients, Sugita nonmagnetic clips were used. In one other, a Drake tourniquet was used. No ill effects occurred from scanning with a high-field imaging unit at 1.5 T. The MR clip artifact was much less obtrusive than that on CT. In 11 cases, the aneurysm could be partially imaged postoperatively, mainly in very large aneurysms or in those treated by clipping the parent vessel. Of these, two revealed residual lumina on MR and nine looked completely thrombosed. Postoperative angiography showed that in four of the thrombosed-appearing aneurysms a residual lumen with a mean diameter of 1.0 cm had been missed. In the patient imaged after application of a Drake tourniquet, no artifact was seen, and a good assessment of progressive partial thrombosis was obtained. Evolution of the signal intensity of new aneurysm thrombus, in those minimally or not obscured by artifact, coincides with patterns previously described for hemoglobin in intracerebral hematomas. The earliest hyperintensity could be seen in either the periphery or the center of the new thrombus. All 15 patients examined with new postoperative deficits showed appropriate lesions, mainly small brainstem ischemic foci. Postoperative CT (performed in all but four of these patients) missed over 80% of these lesions, mainly owing to artifact from clip or bone. We conclude that MR is better than CT in the postoperative assessment of aneurysm patients, particularly in demonstrating small zones of ischemia. High-field MR scanning is safe if nonmagnetic surgical clips are used. MR is not accurate in assessing residual lumina.

Adolescent↗
PubMedDate not supplied

Evaluation of three embolic agents in pig rete.

In ongoing research into potential embolic agents, three substances were evaluated for their effectiveness in occluding the pig rete. Selective injection of these agents produced varying degrees of occlusion, with the most effective a microfibrillar collagen hemostat in a 33% ethanol solution. Angiostat, a collagen particulate, did not produce rete occlusion, and all pigs injected with it developed adverse effects, including coma and apnea. Tisseel, a tissue sealant, produced partial rete occlusion, but was uniformly difficult to manage through long catheters, and its use was discontinued. Microfibrillar collagen hemostat with ethanol appears to have the greatest potential as an embolic agent in low-flow structures.

Animals↗
PubMedDate not supplied

Adjusting the polymerization time of isobutyl-2 cyanoacrylate.

Isobutyl-2 cyanoacrylate (IBCA) polymerizes by an anionic mechanism. The initiation of polymerization depends on an alkaline medium and can be inhibited with the addition of small amounts of acid. Using small amounts of glacial acetic acid (3.7%-7.1% by volume), the polymerization time was prolonged from 2.3 sec to 7.8 sec. In vivo experiments in dogs demonstrated no additional inflammatory reactions to the mixture of IBCA, iophendylate, and tantalum powder when acetic acid was added. Glacial acetic acid offers a safe and effective way, without increase in viscosity, to manipulate the polymerization time of IBCA.

Acetates↗
PubMedDate not supplied

Magnetic resonance imaging of small medullary infarctions.

Small infarctions of the medulla produce typical neurologic deficits and can be clinically recognized fairly reliably. High-field magnetic resonance imaging with a 1.5 T prototype scanner successfully demonstrated very tiny medulla infarctions in three of five patients. These lesions were imaged readily by a fairly rapid (approximately 1-2 min scan time) partial-saturation technique and confirmed on multiple spin-echo images. In addition, in two cases vertebral occlusion ipsilateral to the infarction was suggested by high signal on T2 weighted spin-echo images.

Aged↗
PubMedDate not supplied

Preoperative embolization of brain AVMs with isobutyl-2 cyanoacrylate.

The role of embolization in the management of brain arteriovenous malformations remains controversial. The benefits of embolization alone are not clear and surgical removal may be technically difficult or impossible in many cases. In an attempt to facilitate surgical removal, we performed preoperative embolization in 15 cases using a mixture of isobutyl-2 cyanoacrylate and glacial acetic acid. In one case, a mixture of polyvinyl alcohol particles, microfibrillar collagen, and 30% ethanol was used. In 10 of these cases the surgeon felt that the embolization significantly aided the operative removal by decreasing blood loss, reducing the size of draining veins, and removing portions of the nidus itself. In no patient did the embolization result in an unanticipated significant neurologic deficit. The major role for embolization in the management of brain arteriovenous malformations may be as an aid to surgical removal.

Adult↗
PubMedDate not supplied

A comparison of iopamidol and iohexol in cerebral angiography.

Iopamidol and iohexol, the new nonionic low-osmolality contrast agents, have both been shown to be safe, effective, and better tolerated than conventional ionic agents for cerebral angiography. In this randomized, double-blind study involving 40 patients, these two agents were compared for adverse effects, radiographic quality, and patient tolerance. No significant differences were observed in 220 injections. Because we found iopamidol and iohexol to be equally safe and effective for cerebral angiography, the choice of which contrast agent to use should be based on other considerations.

Adult↗