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Biomedical subjects

E Kanal

Publications and source records attributed to E Kanal.

At least 37 records · Page 2Linked to original sources
PubMed1998

Yasargil aneurysm clips: evaluation of interactions with a 1.5-T MR system.

PURPOSE: To evaluate the magnetic field interactions with Yasargil aneurysm clips exposed to a 1.5-T MR system. MATERIALS AND METHODS: Sixteen Yasargil aneurysm clips made with Phynox (10 clips returned to the manufacturer due to suspected magnetic field interactions and six clips obtained from the manufacturer in sterile packages) were tested for magnetic field interaction at 1.5 T by using techniques to assess magnetic field-induced translational (deflection angle test) and torque (changes in alignment or rotation) forces. RESULTS: None of the aneurysm clips demonstrated magnetic field interactions; that is, deflection angles were zero and there were no changes in alignment or evidence of rotational forces present. CONCLUSION: It is safe to perform MR procedures at 1.5 T or less in patients with Yasargil aneurysm clips made with nonferromagnetic material.

Alloys↗
PubMed1998

Aneurysm clips: evaluation of MR imaging artifacts at 1.5 T.

Magnetic resonance (MR) imaging-related artifacts associated with five different aneurysm clips made of five different metals (commercially pure titanium, titanium alloy, Phynox, Elgiloy, and cobalt alloy) were evaluated. Aneurysm clips made of commercially pure titanium and titanium alloy produced the smallest artifacts, whereas the aneurysm clip made of Elgiloy produced the largest artifacts. These results have implications for the selection of aneurysm clips in patients who may require MR procedures.

Alloys↗
PubMed1998

Acquired hepatocerebral degeneration: MR and pathologic findings.

Acquired (non-Wilsonian) hepatocerebral degeneration (AHD) is a rare irreversible neurologic syndrome that occurs in patients with chronic liver disease associated with multiple metabolic insults. The pathophysiology and the locations of the cerebral injuries are incompletely understood. We describe a patient with fatal hepatic cirrhosis and AHD in whom MR images showed abnormalities in the brachium pontis bilaterally. Neuropathologic evaluation disclosed multiple regions of subcortical spongiform white matter changes.

Aged↗
PubMed1996

Aneurysm clip testing for ferromagnetic properties: clip variability issues.

To assess ferromagnetic properties of intracranial aneurysm clips reported to be nonferromagnetic, 1,765 Yasargil, 11 Sugita, and 15 Perneczky aneurysm clips were studied for rotation or translation on plate glass in a 1.5-T MR imager. Sixty-three clips (52 Yasargil, 11 Perneczky) weakly reoriented along the static magnetic resonance (MR) field. These results confirm the need for standardized testing for ferromagnetic properties for implantable metallic devices.

Contraindications↗
PubMed1996

MR imaging of the meninges. Part I. Normal anatomic features and nonneoplastic disease.

The structural organization of the dura and leptomeninges is reflected in its magnetic resonance (MR) imaging appearance in normal and disease states. Two distinct enhancement patterns are characterized: dura-arachnoid enhancement and pia-subarachnoid space enhancement. The dura-arachnoid pattern consists of curvilinear enhancement overlying the brain and immediately deep to the inner table of the calvaria, as well as along the falx and tentorium. Pial enhancement closely follows the brain surface into sulci and outlines the basal cisterns. Recognition of these enhancement patterns and other MR imaging characteristics may enhance the role of MR imaging in the detection, diagnosis, and follow-up of neoplastic and nonneoplastic disorders affecting the meninges. The focus of this article (Part I) is the MR appearance of the normal meninges and nonneoplastic causes of meningeal disease. Part II of this series will discuss neoplastic conditions affecting the coverings of the brain and spinal cord with an emphasis on pathways of disease spread.

Cerebrovascular Disorders↗
PubMed1996

T2-weighted MR characteristics of internal auditory canal masses.

PURPOSE: To determine whether masses of the internal auditory canal are hypointense relative to cerebrospinal fluid, and therefore visible, on fast spin-echo T2-weighted MR images. METHODS: Forty-six patients had 50 masses of the internal auditory canal, identified initially on contrast-enhanced MR images, that were evaluated retrospectively for signal intensity of the mass with respect to cerebrospinal fluid and for visibility of the neural elements within the internal auditory canal on T2-weighted images. RESULTS: Forty-seven of 50 masses were clearly identified on T2-weighted images. Three small abnormalities (2 to 4 mm) were not seen with confidence on T2-weighted images. However, on close inspection of these three masses, the small abnormality on contrast-enhanced MR images corresponded to a hypointense focus on T2-weighted images. All 50 masses were hypointense relative to cerebrospinal fluid on T2-weighted images. CONCLUSION: All masses of the internal auditory canal in this study were hypointense relative to cerebrospinal fluid on T-2 weighted images, and were therefore visible.

Cohort Studies↗
PubMed1996

MR findings in listerial rhombencephalitis.

We describe a case of listerial rhombencephalitis in a previously healthy 40-year-old man. The diagnosis was based on the clinical findings, results of cerebrospinal fluid analysis, blood culture, and MR imaging findings. The treatment was started before culture results were available, and the patient had a full clinical recovery.

Adult↗
PubMed1995

Dosage of gadoteridol and adverse reactions relative to gadopentetate.

Compliance with an institution's dosage guidelines for gadoteridol was determined, and adverse reactions to gadoteridol and gadopentetate were compared. Departmental policy in March 1993 set the standard dose of gadoteridol at 0.1 mmol/kg. A dose of 0.05 mmol/kg was set for patients with suspected acoustic neurinomas or pituitary microadenomas. Guidelines allowing a high dose of 0.2 or 0.3 mmol/kg were also established for specific indications involving suspected metastatic disease or inadequate contrast enhancement at the standard dose. Data on gadoteridol use were collected concurrently from May 1993 to January 1994 and included the dose, the indication for the dose, and any adverse reactions. Safety data for patients who had received gadopentetate between June 1988 and March 1990 were also collected and reviewed. The subjects in this retrospective analysis represented the same broad population as those involved in the concurrent evaluation of gadoteridol use. The frequency and types of adverse events in the two groups were compared. During the gadoteridol-review period, 8377 patients underwent magnetic resonance imaging studies; 3558 (42.5%) of them received gadoteridol. Of the 3558 doses given, 3375 (94.9%) were 0.1 mmol/kg (the standard dose). Compliance with the guidelines for nonstandard doses was 90% for the 0.3-mmol/kg dose, 74% for the 0.2-mmol/kg dose, and 39% for the 0.05-mmol/kg dose. There were 101 adverse reactions to gadoteridol in 75 (2.1%) of the 3558 recipients. The reactions were mild to moderate and self-limiting. Records for 4892 gadopentetate recipients were analyzed. There were adverse reactions in 62 patients (1.3%). Again, most reactions were mild to moderate. The use of gadoteridol at a medical center generally complied with institutional guidelines. Gadoteridol was well tolerated whether given in standard or high doses. The frequencies and types of adverse reactions to gadoteridol and gadopentetate were similar.

Contrast Media↗
PubMed1994

Post-ECT increases in MRI regional T2 relaxation times and their relationship to cognitive side effects: a pilot study.

This pilot study examined the hypothesis that magnetic resonance imaging T2 relaxation times of specific brain regions increase after electroconvulsive therapy (ECT) and that these increases are related to the cognitive side effects of ECT. Six depressed patients undergoing unilateral ECT were studied. The results demonstrate significant post-ECT T2 increases in the right and left thalamus, and suggest a correlation between regional T2 increase and anterograde memory impairment following ECT. These findings are consistent with a post-ECT increase in brain water content (perhaps secondary to a breakdown of the blood-brain barrier) and suggest that this process may be related to the memory impairment following ECT.

Adult↗
PubMed1994

Physiologic responses to an MR imaging procedure performed at a specific absorption rate of 6.0 W/kg.

PURPOSE: To assess the physiologic responses to a magnetic resonance (MR) procedure performed at a whole-body-averaged specific absorption rate (SAR) of 6.0 W/kg. MATERIALS AND METHODS: Tympanic membrane temperature, skin temperature at seven sites, heart rate, blood pressure, oxygen saturation, and cutaneous blood flow in six volunteers were assessed before, for 16 minutes during, and immediately after MR imaging performed at 1.5 T, 64 MHz. RESULTS: Statistically significant (P < .05) increases in temperature of the tympanic membrane and the skin of the chest, abdomen, upper arm, hand, and thigh and in heart rate and cutaneous blood flow were associated with exposure to high SAR. None of these physiologic changes, however, were considered deleterious to the study subjects. CONCLUSION: MR imaging procedures performed at the high SAR studied can be tolerated by persons with normal thermoregulatory function.

Adult↗
PubMed1994

Firearm safety in the MR imaging environment.

The safety of small-caliber firearms in a 1.5-T magnetic resonance (MR) imaging environment was assessed with six handguns, which were unloaded before testing. Each firearm was withdrawn barrel-first to assess the interaction of the magnetic field with the hammer and/or trigger. Two of the six weapons discharged reproducibly. A firearm in an MR imaging suite should be unloaded before removal or any other manipulation is attempted.

Firearms↗
PubMed1994

Stereotactic magnetic resonance angiography for targeting in arteriovenous malformation radiosurgery.

Because conventional stereotactic angiography provides only two-dimensional information for dose planning, we studied the accuracy and usefulness of stereotactic magnetic resonance angiography (sMRA) for arteriovenous malformation (AVM) radiosurgery in 28 consecutive patients. We hypothesized that the multidimensional data set provided by sMRA and the opportunity to image both blood vessels and brain parenchyma would improve the accuracy of AVM irradiation and improve the safety of radiosurgery. Twenty-eight patients with AVMs in different brain locations and with a variety of AVM sizes (range, 15-31 mm mean diameter) had sMRA followed by stereotactic angiography. The sMRA images only were used to construct an initial radiosurgical plan. This plan was then used to outline the AVM volume defined by conventional angiography. In 24 patients, sMRA information equaled that of conventional angiography. In 3 patients, sMRA was better, because conventional angiography overestimated the size of the AVM nidus. In one patient, the conventional angiogram showed a second separate nidus (10-mm diameter) that was not as well defined on MRA. There were no complications with any procedure. In 16 patients (57%), sMRA provided critical information on AVM shape that was not provided by conventional angiography alone. Stereotactic MRA is a fast, noninvasive, inexpensive, multidimensional imaging method for AVM radiosurgery that provides information on vascular and parenchymal brain anatomy important for optimal dose planning. We believe that it can be used with confidence as the sole imaging method for medium-size, compact-nidus AVMs.

Adolescent↗