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Biomedical subjects

R R Edelman

Publications and source records attributed to R R Edelman.

At least 19 recordsLinked to original sources
PubMed1992

[Cerebral angiography using proton spin tomography].

In only a few years magnetic resonance angiography has evolved to a clinically useful tool. In many situations it can resolve questions which used to be addressed by conventional contrast angiography, such as carotid stenoses, aneurysms, arteriovenous malformations, and venous and sinus disorders. In addition, selective magnetic resonance angiography provides information on direction and origin of flow and circulation in vessels serving as collaterals.

Carotid Artery Diseases↗
PubMed1992

Portal vein thrombosis: a review.

Portal vein thrombosis (PVT) is a rare condition that affects both children and adults. This article reviews the existing literature on PVT, with an emphasis on recent developments. A comprehensive description of etiologic factors and clinical aspects is presented. Treatment issues that remain unresolved are addressed and a framework for the diagnostic work-up and management of patients with PVT is provided.

Humans↗
PubMed1992

[Magnetic resonance tomography of the liver with TurboFLASH and segmented acquisition. Fast imaging with flexible image contrast].

The value of a fast imaging sequence in diagnosing focal liver lesions was assessed in 43 patients. The sequence (TurboFLASH with segmented acquisition) allows the acquisition of T1- and T2-weighted images within a breath-hold interval. Lesion-liver contrast was compared with T2-weighted spin-echo, T1-weighted gradient-echo, and single shot TurboFLASH sequences. All lesions that were seen with the latter sequences were also visible on the segmented TurboFLASH images. Contrast on the segmented TurboFLASH images was similar to that of T2-weighted spin-echo sequences and superior to T1-weighted gradient-echo sequences. Signal of fat could be nulled at an inversion time of 10 ms, signal from liver tissue could be nulled at an inversion time of 300 ms. By minimising the liver signal, the lesions could be "highlighted". This was not possible with the other imaging sequences. The segmented TurboFLASH technique allows breath-hold imaging of the liver with arbitrary image contrast. The lesion-liver contrast is comparable to time-consuming T2-weighted spin-echo sequences.

Biopsy, Needle↗
PubMed1992

[Magnetic resonance angiography of the renal veins and the vena cava inferior for the staging of renal cell carcinoma].

The staging of renal cell carcinoma (RCC) comprises exclusion of tumour expansion into the renal veins and the inferior vena cava (IVC). In 44 patients with RCC these vessels were examined using MRA on the basis of "time-of-flight" technique (coronal/axial 2D GE-flash-sequence, MIP-algorithm). The method was evaluated against contrast-enhanced CT and DSA in normal conditions and tumour-involved IVC (n = 12) and renal veins (n = 32) respectively. Following analysis of projection-angiograms (PA) and individual slices the results of MRA without contrast material included an information on vascular tumour extension that was identically safe as CT and DSA. In coronal slice orientation tumour extension into the vena cava was proven in 100%, and into the renal veins in 84%. Additional axial slices were necessary to demonstrate tumour extension into the renal veins in unclear cases. Single slices showed to be superior to PA for a correct identification of the size of the tumour thrombus.

Adult↗
PubMed1992

Cerebral magnetic resonance angiography.

Magnetic resonance angiography (MRA) is an accurate non-invasive tool for imaging the cerebral vessels. It provides morphologic information about the cerebral vessels relying on blood flow as the physical basis for generating contrast between stationary tissues and moving spins. 'Selective' MRA gives functional information about the cerebrovascular system such as flow direction, origin of flow, and presence or absence of collaterals. Arteries and veins can be imaged selectively due to their usually opposite flow directions. Although at a relatively early stage of development, MRA has already become a widely used tool for the study of the cerebrovascular system.

Arteriovenous Malformations↗
PubMed1992

Measurement of visceral blood flow with magnetic resonance imaging.

With the increasing application of magnetic resonance imaging (MRI) and MR angiography in parenchymal liver disease, methods are becoming more widely available for noninvasive measurement of visceral blood flow. Amplitude-based (time-of-flight) and phase-based techniques have proved effective for measurement of portal blood flow, and phase-sensitive methods are applicable to arterial flow measurements. Because respiratory motion degrades the quality of examinations in the abdomen, it is desirable to use methods that can generate flow information in a breath-hold period. Although substantial technical difficulties persist for quantitative arterial flow measurements in the abdomen, the technical requirements for venous flow are less stringent, and important clinical information can be derived using straightforward techniques. The authors describe the principles of flow measurement using time-of-flight and phase methods in visceral arteries and veins, and discuss their practical implementation. Clinical applications are discussed, based on the experience of the authors and others working in the field.

Blood Flow Velocity↗
PubMed1992

Acute cerebral ischemia: evaluation with dynamic contrast-enhanced MR imaging and MR angiography.

Dynamic contrast-enhanced T2-weighted magnetic resonance (MR) imaging and MR angiography (MRA) were used to evaluate cerebral blood volume and the intracranial arterial system in 34 patients within 48 hours after the onset of cerebral ischemia. In 24 of the patients, an abnormality identified on T2-weighted images corresponded to the acute clinical deficit. Intracranial MRA demonstrated occlusions or severe stenoses of major vessels supplying the area of infarction in 16 of these patients, and decreased blood volume correlated well with MRA abnormalities. Infarcts less than 2 cm in diameter were not reliably shown with MRA or blood volume studies. Correlation between lesions seen with MRA and decreased blood volume in acute infarcts was good, and both techniques demonstrated lesions early in the clinical course. By providing information about hemodynamics not available with conventional T1- or T2-weighted images, MRA and dynamic MR imaging could prove helpful in describing the pathophysiologic characteristics of stroke and in guiding early therapeutic intervention.

Adult↗
PubMed1992

Assessment of intracardiac shunts with gadolinium-enhanced ultrafast MR imaging.

Dye dilutional techniques are widely accepted for the assessment of intracardiac shunts, but current techniques require arterial access or radioisotope injection. Ultrafast (less than 500 msec) magnetic resonance (MR) imaging is ideally suited for the evaluation of an indicator during passage through the heart. Twenty patients were studied, including 13 with shunts. Four-chamber, T1-weighted images were obtained during bolus injection of gadopentetate dimeglumine. A single image was obtained in 420 msec, with repetitive images acquired after each QRS complex. After the contrast material was injected, there was pronounced signal intensity enhancement in the right atrium, followed by the right ventricular cavity, left atrium, left ventricular cavity, and descending aorta. Patients with substantial intracardiac shunts demonstrated early recirculation. First-pass contrast material-enhanced MR imaging is a promising new technique for the rapid assessment of intracardiac shunts. Combined with anatomic and functional MR imaging techniques, it can help provide a comprehensive noninvasive evaluation of suspected intracardiac shunts or provide follow-up in patients with known shunts.

Adult↗
PubMed1992

Improved time-of-flight MR angiography of the brain with magnetization transfer contrast.

The authors hypothesized that magnetization transfer contrast (MTC) could be used to improve flow contrast in time-of-flight (TOF) magnetic resonance (MR) angiography. Two- and three-dimensional flow-compensated gradient-echo images were obtained with and without MTC. MTC images were obtained by applying low-power radio-frequency (RF) radiation with a frequency offset from the bulk "free" water resonance frequency before the excitation RF pulse. The signal intensity of stationary tissue decreased as the power applied for the MTC pulse was increased. A smaller decrease occurred in venous signal intensity as measured in the superior sagittal sinus, and less change was seen in the arterial signal intensity as measured in the middle cerebral artery. Cerebrospinal fluid showed no MTC effect. The use of MTC improved small-vessel depiction on maximum-intensity projection images. The authors conclude that use of MTC can substantially enhance the quality of TOF MR angiography of the brain.

Adult↗
PubMed1992

The Simon nitinol filter: evaluation by MR and ultrasound.

In this prospective blinded study of inferior vena caval (IVC) patency, 18 patients underwent 25 duplex ultrasound (US) and magnetic resonance (MR) angiography examinations over an eight-month period following Simon nitinol filter placement. Clinical examination for lower extremity venous stasis and plain abdominal radiography were also performed. Twenty-three of 24 MR examinations and 11 of 24 US examinations were judged technically adequate by the blinded observers. One technically adequate US exam was false positive for intraluminal caval thrombus. Thirteen technically inadequate US examinations missed 3 complete caval occlusions and 2 partial occlusions. MR identified all patients with complete or partial caval occlusion. The authors conclude that duplex US reliably confirms IVC patency only when strict criteria for technical adequacy and interpretation are met (good visualization of filter and IVC above and below filter). MR, although expensive, more reliably identifies nonoccluding intraluminal thrombus and caval occlusion. It should be the noninvasive study of choice in symptomatic patients with venous stasis and patients with recurrent pulmonary emboli.

Adult↗
PubMed1992

Fast magnetic resonance diffusion-weighted imaging of acute human stroke.

Rapid MRI of the molecular diffusion of water demonstrated cerebral infarcts in 32 patients. We studied these patients at various times following the onset of ischemic symptoms and found that diffusion-weighted imaging revealed the infarcts sooner than conventional T2-weighted spin-echo imaging did; four hyperacute infarcts were shown only by diffusion-weighted imaging. Acute infarcts had lower apparent diffusion coefficients (ADCs) than noninfarcted regions did. This relative difference in ADC reached a nadir in the first 24 hours and rose progressively thereafter. Chronic infarcts showed a relative increase in diffusion and were readily distinguishable from acute infarcts. The technique takes less than 2 minutes to apply using a standard 1.5-tesla scanner in the clinical setting. Diffusion-weighted imaging has the potential to play a role in improving the early anatomic diagnosis of stroke and therefore in the development and implementation of early stroke interventions.

Adult↗
PubMed1992

Transaqueductal migration of a neurocysticercus cyst. Case report.

The clearly documented transaqueductal migration of a solitary intraventricular neurocysticercus cyst is described. The cyst was fortuitously demonstrated on magnetic resonance imaging during migration through the aqueduct. The radiological appearance and clinical significance of this condition are discussed.

Adult↗
PubMed1992

Magnetic resonance angiography in the body.

Magnetic resonance angiography (MRA) is gaining wide acceptance as a clinical tool for evaluation of the carotid arteries and intracranial circulation. MR angiographic methods are far less widely employed in the body. However, several very powerful techniques have been developed which provide a wealth of clinical information and which may soon replace alternative imaging techniques for a variety of applications. As compared with MRA of the head and neck, these techniques require more interactive involvement by a physician and more familiarity with the imaging machine to derive their full benefit. Based on the experience of the authors and others working in the field, this article outlines strategies for MRA of the abdomen, pelvis and thorax, and reviews the clinical situations in which these techniques have proved useful.

Abdomen↗
PubMed1992

Image artifacts in fast magnetic resonance imaging.

Image artifacts are unwanted, spurious signal intensities that interfere with clinical diagnosis. This article gives an overview of image artifacts in magnetic resonance imaging. We discuss the causes of these artifacts, provide clinical examples, and offer solutions to avoid them.

Artifacts↗
PubMed1991

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↗
PubMed1991

First-pass nuclear magnetic resonance imaging studies using gadolinium-DTPA in patients with coronary artery disease.

Nuclear magnetic resonance (NMR) imaging has been shown to accurately portray cardiac anatomy and function. To investigate the potential of NMR imaging for the assessment of coronary stenosis in patients with chest pain, ultrafast NMR imaging in conjunction with a T1 (longitudinal relaxation time) contrast agent was performed in 17 patients with chest pain who had undergone cardiac catheterization. These included 12 patients with significant coronary artery stenoses and 4 who underwent repeat NMR study after myocardial revascularization. Cardiac images at rest were obtained during rapid intravenous injection of gadolinium-DTPA (0.04 mM/kg). Electrocardiographic-gated images were acquired over 380 ms, with repetitive images obtained every 3 to 4 s. After contrast injection, there was pronounced signal enhancement in the right ventricular cavity, followed by enhancement in the left ventricular cavity and myocardium. Regional myocardium perfused by a diseased vessel demonstrated a lower peak signal intensity (p = 0.001) and lower rate of signal increase (p = 0.001) than did myocardium perfused by coronary arteries without stenosis. Repeat NMR study after revascularization showed an increase in peak signal intensity (p less than 0.002). These results demonstrate the clinical potential of dynamic gadolinium-DTPA-enhanced NMR imaging for the assessment of coronary artery disease in patients with chest pain. In combination with anatomic and functional NMR imaging, this technique has the potential to provide a comprehensive noninvasive cardiac evaluation of patients with suspected coronary artery disease.

Adult↗
PubMed1991

[MR angiography of the abdominal aorta: initial experience].

Flowing blood can be demonstrated as bright signal in MR-imaging resulting in MR-angiography (MRA). This study presents the results of MRA using the "time of flight"-effect in which projection angiograms along the longitudinal axis were established by a row of 2D-gradient echo (GE) images (FLASH) in breath-hold technique. The method was proven in 5 normal volunteers and evaluated against DSA in 21 patients with aortic diseases. The preliminary results demonstrate a satisfactory flow signal in the normally perfused aorta; thus occlusions, stenoses, and aneurysms could be defined clearly. In smaller vessels the signal was still insufficient. Diagnostic problems of vascular overlapping can be solved in most cases by rotating the angiograms, and by additional analysis of individual 2D-GE images. In the present form the quality of MRA is still inferior to that of DSA.

Angiography, Digital Subtraction↗