Biomedical subjects

B Drayer

Publications and source records attributed to B Drayer.

9 recordsLinked to original sources

PubMed1989

Multicenter double-blind placebo-controlled study of gadopentetate dimeglumine as an MR contrast agent: evaluation in patients with cerebral lesions.

A multicenter double-blind randomized study was designed to evaluate and compare the safety and diagnostic efficacy of gadopentetate dimeglumine (Gd-DTPA) (0.1 mmol/kg) against a saline placebo for use as an IV contrast agent for MR. The randomization code provided for a 2:1 ratio of Gd-DTPA and saline patients. Six investigators studied 88 patients with signs and symptoms of a cerebral lesion. Although safety data were complete in all 88 cases, only 83 had valid efficacy data (57 received Gd-DTPA, 26 placebo). Three patients were excluded from efficacy evaluation because of incomplete scans or scans with severe motion artifacts. Two patients were excluded for protocol variations (did not have a mass lesion). The protocol required that spin-echo MR images be acquired both before and after infusion at mode 1, 500/30/2 (TR/TE/excitations), and at a single-echo mode 2 sequence within a selected range, 1500-2000/56-90/2. Additional TEs could also be used at the discretion of each investigator. Efficacy was determined by comparing post- with preinjection images for relative degree of enhancement and improvement of diagnostic ability after injection, and by comparing these results with placebo results. Enhancement was reported in 43 (75%) of 57 Gd-DTPA patients and in none of the 26 placebo patients. Improvement of diagnostic ability was noted in 37 of 57 Gd-DTPA patients and in no placebo patients. Of 17 patients receiving Gd-DTPA for whom no diagnosis could be made before infusion, nine of 17 were diagnosed after infusion. By comparison, none of five patients not diagnosed before infusion of placebo could be diagnosed after infusion. Of 43 patients in whom lesion enhancement was observed after Gd-DTPA infusion, the diagnosis changed after infusion in 16 (37%) and the number of lesions detected after infusion increased in 10 (23%). Safety studies showed no clinically significant abnormal trends. Minor changes in blood pressure, pulse, and serum iron levels were noted in a higher percentage of Gd-DTPA patients. This study confirms that Gd-DTPA is an efficacious contrast agent for use with MR and that it exhibits excellent patient tolerance. Enhancement allows for a decisive diagnosis to be made in selected cases in which such capability had previously been lacking with unenhanced MR.

Adolescent↗

PubMed1987

Reduced signal intensity on MR images of thalamus and putamen in multiple sclerosis: increased iron content?

High-field-strength (1.5-T) MR imaging was used to evaluate 47 patients with definite multiple sclerosis and 42 neurologically normal control patients. Abnormal, multiple foci of increased signal intensity on T2-weighted images, most prominent in the periventricular white matter, were apparent in 43 of 47 MS patients and in two of 42 control patients. A previously undescribed finding of relatively decreased signal intensity most evident in the putamen and thalamus on T2-weighted images was seen in 25 of 42 MS patients and correlated with the degree of white-matter abnormality. In the normal control patients a prominently decreased signal intensity was noted in the globus pallidus, as compared with the putamen or thalamus, correlating closely with the distribution of ferric iron as determined in normal Perls'-stained autopsy brains. The decreased signal intensity (decreased T2) is due to ferritin, which causes local magnetic field inhomogeneities and is proportional to the square of the field strength. The decreased T2 in the thalamus and striatum in MS may be related to abnormally increased iron accumulation in these locales with the underlying mechanism remaining speculative.

Adult↗

PubMed1986

MRI of brain iron.

A prominently decreased signal intensity in the globus pallidum, reticular substantia nigra, red nucleus, and dentate nucleus was routinely noted in 150 consecutive individuals on T2-weighted images (SE 2000/100) using a high field strength (1.5 T)MR system. This MR finding correlated closely with the decreased estimated T2 relaxation times and the sites of preferential accumulation of ferric iron using the Perls staining method on normal postmortem brains. The decreased signal intensity on T2-weighted images thus provides an accurate in vivo map of the normal distribution of brain iron. Perls stain and MR studies in normal brain also confirm an intermediate level of iron distribution in the striatum, and still lower levels in the cerebral gray and white matter. In the white matter, iron concentration is (a) absent in the most posterior portion of the internal capsule and optic radiations, (b) higher in the frontal than occipital regions, and (c) prominent in the subcortical "U" fibers, particularly in the temporal lobe. There is no iron in the brain at birth; it increases progressively with aging. Knowledge of the distribution of brain iron should assist in elucidating normal anatomic structures and in understanding neurodegenerative, demyelinating, and cerebrovascular disorders.

Adolescent↗

PubMed1985

High-resolution computed tomography in multiple sclerosis.

Eighty-five patients were classified as having definite (n = 34), probable (n = 18), or possible (n = 33) multiple sclerosis using the criteria of Poser. Each patient had an enhanced computed tomographic examination, and most had cerebrospinal fluid and evoked response studies at the same time. Abnormalities including focal decreased brain density, abnormal enhancement, and cerebrospinal fluid space enlargement were found in 62% of patients (85% of those with definite, 39% of those with probable, and 52% of those with possible multiple sclerosis), and abnormal enhancing areas were demonstrated in 29% (44% of those with definite, 17% of those with probable, and 21% of those with possible disease). In the subgroup of patients with definite multiple sclerosis and recent clinical exacerbation (within the prior 8 weeks), abnormal enhancement was present in 89%. There was a strong correlation between clinical exacerbation and abnormal contrast enhancement. Cerebrospinal fluid studies (IgG, white blood cell count, total protein) had no correlation with exacerbation or abnormal enhancement. Maps of low-density and enhancing areas were similar to those previously described in postmortem studies. Computed tomography thus provides an in vivo, objective, and anatomically specific map of the brain parenchyma and the integrity of the blood-brain barrier that is useful in research studies evaluating the treatment of multiple sclerosis. It is also useful in patients in whom the diagnosis of multiple sclerosis is suspected but not certain on the basis of clinical and laboratory evaluation.

Adult↗

PubMed1985

Intra-arterial digital subtraction angiography of the spinal cord.

Digital subtraction angiography (DSA) of the spinal cord was performed in 6 patients using selective intra-arterial injections of contrast material. Two arteriovenous malformations of the spinal cord, 1 dural fistula, and 1 case of multiple hemangioblastomas were studied. Contrast and spatial resolution were satisfactory for defining normal and abnormal vascularity while reducing examination time, contrast dosage, patient discomfort, and film cost. The only significant limitation was misregistration artifacts seen on lateral views encompassing the diaphragm.

Adult↗

PubMed1985

Comparative neurotoxicity of angiographic contrast media.

The neurotoxic effects in cerebral angiography of three iodinated ionic contrast media, nonionic iopamidol, 25% mannitol, and saline controls were compared in 25 rabbits. Diatrizoate sodium meglumine was the most toxic agent, followed by diatrizoate and meglumine, iothalamate meglumine, and mannitol in terms of blood-brain barrier (BBB) disruption and coupled perfusion decline. HIPDm distribution was more sensitive than trypan blue extravasation for monitoring brain dysfunction. Iopamidol and saline controls exhibited no visual BBB breakdown or alteration in regional uptake of I-125 HIPDm, confirming the safety of nonionic iopamidol as compared with presently used ionic contrast media.

Animals↗

PubMed1979

Dynamic computed tomography study of the brain.

The dynamic computed tomography (CT) study of the brain consists of the rapid intravenous injection of 49 ml of radiographic contrast material in 7 sec followed by serial 5 sec CT scans with interscan times of only 1 sec. The data from these scans can be reprocessed to create 12 segmented images in 35 sec. When small samples of four to six pixels of cortex are examined by the cursor, sharp rises of 20 to 25 CT units (500 scale) are seen on the time--density curves. Samples of white matter are usually no more than 2 CT units. When larger cursor samples of 220 to 255 pixels including cortex and white matter are examined, the time--density curves represent a combination of these two patterns. Comparison between symmetrical areas in the two hemispheres generally shows parallel curves in controls. The studies provide high resolution cerebral perfusion images. In ischemia secondary to ipsilateral carotid stenosis, there is depression of the up-slope and a depressed and late peak. Infarctions show a flat perfusion curve. Several patterns in brain tumors are illustrated. The study, simple to perform, adds significant perfusion information to the previously static CT examination of the brain.

Adult↗

PubMed1979

Diagnostic approaches to pituitary adenomas.

The utility of diagnostic tests for pituitary adenoma was compared in 12 patients. Endocrine and radiologic studies were always abnormal, even when neuro-ophthalmologic tests were normal. In most cases, both tomography of the sella turcica and CT scan revealed a mass in the region of the sella turcica. For more precise definition of suprasellar extension of the mass, metrizamide CT cisternography or tomographic pneumoencephalography with metrizamide provided similar details, although CT cisternography was much more easily done. Angiography provides a means to exclude an aneurysm or vascular malformation, a vascular tumor, or an aberrant course of the internal carotid artery.

Adenoma↗

PubMedDate not supplied

SAR reduced pulse sequences.

Three techniques were considered for reducing the RF (radiofrequency) power deposition in the body while maintaining scan time efficiency: reducing the RF peak amplitude while increasing the pulse width, substituting gradient echoes for spin echoes, and reducing the flip angle of the phase reversal pulse. The use of gradient echoes was found to be the most efficient means to reduce the power delivered to the patient and to obtain rapid data acquisition. The effect upon SAR (specific absorption rate) and SNR (signal-to-noise ratio) was demonstrated on a phantom when the phase reversal pulse was reduced from the standard 180 degrees to 90 degrees. Data in the body indicated a fairly constant SNR down to a refocusing flip angle between 110 degrees and 135 degrees. An initial clinical evaluation was performed at three institutions using the method of reducing the flip angle of the phase reversal pulse. The scan with theta = 120 degrees was rated by readers in a blinded study as having acceptable diagnostic image quality while the 135 degrees scan had comparable image quality to a conventional 90 degrees - 180 degrees pulse sequence. The use of reduced phase reversal pulses was seen as an efficient protocol to obtain T1-weighted images at rapid data rates while reducing the power delivered to the body by about 40%.

Humans↗