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Biomedical subjects

G Wesbey

Publications and source records attributed to G Wesbey.

10 recordsLinked to original sources
PubMed1996

Can noninvasive studies replace conventional angiography in the preoperative evaluation of carotid stenosis?

Most articles in 1995 demonstrated a sensitivity of 100% and specificities of 90% to 98% in detecting carotid bifurcation stenosis using a combination of MR angiography and ultrasonography, reserving conventional angiography for cases of disparate stenosis with the noninvasive studies. Multiple reviews concluded that noninvasive studies were less morbid than conventional angiography when taking into account the risks of conventional angiography and surgery as well as the morbidity associated with unnecessary surgery (false-positive noninvasive study) or withholding indicated surgery (false-negative noninvasive study). Thus, the current literature suggests that non-invasive studies have indeed reached a point where they can replace conventional angiography in the preoperative evaluation of carotid bifurcation stenosis. It is paramount that each imaging center review its own sensitivity and specificity in detecting surgically significant carotid stenosis with noninvasive studies. High sensitivity and specificity in diagnosing percent carotid stenosis with noninvasive studies can occur today with routine imaging equipment, but it takes a great deal of effort and dedication on the part of the imaging center.

Angiography↗
PubMed1991

Flow phenomena, classification, and clinical aspects of magnetic resonance angiography.

Both time-of-flight and phase-contrast techniques are currently being employed in producing angiographic MR images of arteries and veins. Both two-dimensional and three-dimensional acquisition methods can be used to display projective vascular images with the maximum intensity projection algorithm, eliminating the need for image subtraction. MR angiography has expanded the armamentarium of MR imaging, especially in the head and neck, and should in some organ systems reduce the need for conventional x-ray catheter angiography.

Blood Flow Velocity↗
PubMed1985

[Contrast agents in magnetic resonance imaging].

The origin of nuclear magnetic resonance signal is reminded in this paper. Different ways of increasing the contrast in magnetic resonance imaging are presented, especially modifications of tissues relaxation times by the use of paramagnetic ions or nitroxides. The potential of these substances is illustrated by several examples of application in the animal.

Animals↗
PubMed1984

Imaging and characterization of acute myocardial infarction in vivo by gated nuclear magnetic resonance.

Imaging by nuclear magnetic resonance (NMR) techniques has been shown to provide high-contrast resolution between soft tissues and characterization of normal and pathologic tissues by differences in magnetic relaxation times. The current study was designed to determine whether electrocardiogram (ECG)-gated NMR imaging of the canine heart in vivo could distinguish normal from infarcted myocardium without the use of intravenous paramagnetic contrast agents. Seven dogs were studied by ECG-gated NMR imaging in vivo (spin-echo technique) with a 0.35 Tesla superconducting magnet at 2 to 7 days after ligation of the left anterior descending coronary artery. In six of the seven dogs, signal intensity was increased in the anterior wall compared with the remainder of the left ventricle; this region of high signal intensity corresponded to the area of myocardial infarction demonstrated at postmortem examination. The signal intensity of the infarcted region was 66 +/- 27% greater than that of normal myocardium (p less than .01). The T2 (spin-spin) relaxation time was 69 +/- 3% longer in the infarcted myocardium as compared with normal myocardium (p less than .01). The NMR images from the seventh dog had uniform signal intensity throughout the myocardium of the left ventricle. An infarct was not evident on postmortem examination in this dog. Thus gated NMR imaging in vivo by the spin-echo technique displays acute myocardial infarctions as regions of high signal intensity without the use of contrast media. The infarct is characterized by a prolonged T2 relaxation time.

Animals↗
PubMed1980

Computed tomographic demonstration of anomalous inferior vena cava with azygos continuation.

A case of anomalous inferior vena cava with azygos continuation first diagnosed by computed tomography (CT) and later confirmed by venography is presented. In addition to identifying the dilated azygos vein in the chest, CT can determine the direction of flow in the vein by means of a bolus contrast medium injection. Once this is established, a search for the etiology of the dilated vein can be directed to the appropriate anatomic area.

Adult↗
PubMedDate not supplied

Clinical experience with routine Gd-DTPA administration for MR imaging of the brain.

A retrospective analysis of intracranial magnetic resonance (MR scans of 514 patients who underwent nonselective Gd-DTPA enhanced MR imaging was performed to determine the efficacy of this protocol for Gd-DTPA administration. This report reviews the frequency and clinical significance of abnormally enhancing areas that were entirely undetectable on precontrast images or would have been missed without the retrospective knowledge of enhancement. Fifty-seven patients (11% of the 514 patients studied) showed enhancing lesions, with 16 (3.1% of the total) of these patients demonstrating one or more lesions identifiable only on postcontrast images. Of those 16 patients, 8 had other focal abnormalities on precontrast studies, whereas the remaining 8 (1.6% of the total) had negative precontrast studies. The new diagnoses affected clinical management directly in five patients and in another nine contributed potentially significant information. Considerations regarding a selective versus nonselective protocol for Gd-DTPA administration for intracranial MR imaging and the use of clinical information to augment these protocols are discussed.

Brain↗