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Biomedical subjects

W Pavlicek

Publications and source records attributed to W Pavlicek.

32 records · Page 2Linked to original sources
PubMed1983

Anatomic and functional imaging of congenital heart disease with digital subtraction angiography.

Digital subtraction angiography (DSA) of the heart was performed in 54 patients for the evaluation of congenital heart disorders. DSA produced high-quality diagnostic images and accurate physiologic shunt data that compared favorably with catheter angiography and nuclear medicine studies. Retrospective analysis of this series of patients indicated that DSA studies contributed sufficient information to shorten significantly or modify cardiac catheterization in 85% (79/93) of the defects that were identified. Interatrial septal defects were particularly well diagnosed, with identification occurring in 10 of 10 cases, whereas intraventricular septal defects were identified in only 6 of 9 patients. Evaluation of postsurgical patients was accurate in 19 of 20 cases.

Adolescent↗
PubMed1983

Intravenous digital subtraction angiography: peripheral versus central injection of contrast material.

Central and peripheral intravenous injections of contrast material for digital subtraction angiography were compared in 30 patients. With 40 ml of contrast material, visualization of the carotid bifurcations was as good with the peripheral as with the central injection. A more consistently high-quality examination of the small intracranial vessels was obtained with the central injection.

Arm↗
PubMed1983

Nuclear magnetic resonance imaging of the spine.

Forty subjects were examined to determine the accuracy and clinical usefulness of nuclear magnetic resonance (NMR) examination of the spine. The NMR images were compared with plain radiographs, high-resolution computed tomograms, and myelograms. The study included 15 patients with normal spinal cord anatomy and 25 patients whose pathological conditions included canal stenosis, herniated discs, metastatic tumors, primary cord tumor, trauma, Chiari malformations, syringomyelia, and developmental disorders. Saturation recovery images were best in differentiating between soft tissue and cerebrospinal fluid. NMR was excellent for the evaluation of the foramen magnum region and is presently the modality of choice for the diagnosis of syringomyelia and Chiari malformation. NMR was accurate in diagnosing spinal cord trauma and spinal canal block. The normal disc was seen, but with rare exceptions bulging of the annulus and herniation of the nucleus pulposus were not visualized.

Adolescent↗
PubMed1983

Magnetic resonance imaging of the cervical spine: technical and clinical observations.

Seventy-two patients were examined to determine the clinical potential for magnetic resonance imaging (MRI) of the spine. MRI using different pulse sequences was compared with plain radiography, high-resolution computed tomography, and myelography. There were 35 normal patients; pathologic conditions studied included canal stenosis, herniated disk, metastatic tumor, neurofibroma, trauma, Chiari malformation, syringomyelia, arteriovenous malformation, and rheumatoid arthritis. MRI provided sharply defined anatomic delineation and tissue characterization. It was diagnostic in syringomyelia and Chiari malformation and was useful in the evaluation of trauma and spinal canal block from any cause. MRI was sensitive to degenerative disk disease and infection. The spin-echo technique, with three pulse sequence variations, seems very promising. A short echo time (TE) produces the best signal-to-noise ratio and spatial resolution. Lengthening the TE enhances differentiation of various tissues by their signal intensity, while the combined increase of TE and recovery time (TR) produces selective enhancement of the cerebrospinal fluid signal intensity.

Arnold-Chiari Malformation↗
PubMed1983

NMR imaging of the abdomen: technical considerations.

Evaluation of nuclear magnetic resonance (NMR) imaging of the abdomen was done in 41 patients with focal and diffuse disorders of the liver and retroperitoneal and vascular abnormalities. Spin-echo technique was used in each situation with varying time to echo (TE) and repetition rates (TR). No single pulsing technique was optimal in all situations. Three false-negative NMR studies of 22 patients with focal lesions of the liver were attributed to incomplete coverage of the involved area or inappropriate pulsing technique. When appropriate technique was achieved, NMR was equal to computed tomography (CT) in detecting abdominal disorders, except in fatty infiltration of the liver. NMR was superior to CT in imaging vascular anatomy because of the inherent increased contrast produced by the absence of signal from flowing blood and the flexibility of imaging planes.

Abdomen↗
PubMed1982

Digital subtraction angiography of the intracranial vascular system: comparative study in 55 patients.

Intracranial vessels were examined in 55 patients with both conventional selective catheterization and intravenous digital subtraction angiography using a prototype digital subtraction unit. In 65% of the patients, the digital subtraction angiogram was diagnostic, but the overall quality was inferior to conventional selective angiography. In 22%, the digital subtraction angiogram provided diagnostic information, but there was a significant chance of misinterpreting the results of the study. In 13% of cases, the subtraction angiogram was not diagnostic. As now developed, digital subtraction angiography can replace conventional cerebral angiography for preoperative evaluation of the juxtasellar carotid artery prior to transphenoidal surgery because the large intracerebral vessels are consistently well visualized with digital subtraction. The dural sinuses are better visualized with digital subtraction than with conventional angiography because with digital subtraction all the vessels of the brain are opacified, whereas with conventional angiography, there is a mixture of opacified and unopacified blood in the sinuses. Combined with computed tomography, digital subtraction angiography can replace conventional angiography for determining the preoperative extent and vascularity of tumors. It can be used for postoperative evaluation of aneurysms, arteriovenous malformations, extracranial to intracranial bypasses, and after the embolization of vascular lesions.

Adult↗
PubMed1981

Digital subtraction angiography of the abdominal aorta and renal arteries. Comparison with conventional aortography.

Digital subtraction angiography (DSA) was used to study the cardiovascular system in more than 400 patients and was specifically compared with conventional angiography of the aorta and renal arteries in 30 patients. For the renal arteries, the overall accuracy of DSA was 71% (50/70). Excluding 11 cases of inadequate visualization of the renal arteries on DSA, the sensitivity of the new technique was 93% (55/59) and the specificity 91.5% (54/59). Aortic disease, including intravascular clots and occlusions, was faithfully delineated by DSA.

Angiography↗
PubMed1981

Imaging capability of an experimental digital subtraction angiography unit.

We evaluated an experimental digital subtraction unit in terms of field uniformity, linearity of signal response to x-radiation, response of the log amplifier, and imaging capability as measured with the Rose phantom. For comparison, conventional film subtraction phantom measurements were made. Our results indicate that this unit exhibits greater sensitivity to contrast media than conventional film subtraction units.

Angiography↗
PubMed1980

Digital subtraction angiography of the human cardiovascular system.

Initial clinical application of a system for digital subtraction angiography (DSA) to the human cardiovascular system in 88 patients is reported. The equipment consisted of a specially designed computer system integrated with a fluoroscopic and radiographic apparatus for digitization, manipulation, and display of data. After intravenous injection of contrast material, adequate visualization of the heart and carotid, thoracic, abdominal, and femoral arteries was obtained with sufficient quality to obviate conventional angiography in many clinical settings. In this mode, nonselective opacification is obtained. However, DSA was also used to extend the capability of selective angiography. The availability of quantitative information permitted the determination of rates of transit of contrast material in various organs which may give insights of their physiologic performance.

Aneurysm↗
PubMedDate not supplied

The special environmental needs of magnetic resonance.

The addition of a magnetic resonance (MR) unit to a hospital radiology environmental poses many unique considerations. Large magnetic fields present health and safety considerations as well as a hostile environment for data recorded magnetically. Radio-frequency shielding is necessary to eliminate a source of background signal that interferes with patient examinations. Magnetic shielding may be necessary in some instances to prevent low-level magnetic field exposure of persons with artificial cardiac pacemakers. Superconducting magnets are heavy and large and may give off large amounts of helium which can temporarily replace the air in the magnet room. Possible solutions to these environmental requirements are presented.

Environment, Controlled↗