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Biomedical subjects

M G Stein

Publications and source records attributed to M G Stein.

18 recordsLinked to original sources
PubMed1988

Normal and diseased isolated lungs: high-resolution CT.

High-resolution computed tomography (CT) scans of 12 isolated, inflated, fresh lungs obtained at autopsy were compared with thin, paper-mounted lung sections obtained at the same levels. In six lungs considered intrinsically normal, high-resolution CT showed normal interlobular septa and pulmonary arteries in the lobular core, but lobular bronchioles were not visible. Edematous fluid resulted in thickening and increased visibility of interlobular septa. In three emphysematous lungs, high-resolution CT accurately demonstrated the degree of emphysema and suggested its centrilobular nature. In two lungs with honeycombing, cysts lined by fibrosis were easily seen on high-resolution CT scans. In less severely involved areas, septal thickening and intralobular fibrosis were seen on high-resolution CT scans, but small (1 mm) cysts were invisible. High-resolution CT was able to demonstrate some features of the normal secondary pulmonary lobule and structural alterations produced by various diseases.

Humans↗
PubMed1988

Computed tomography: pathologic correlation in lung disease due to tocainide.

High resolution computed tomography (CT) was used to demonstrate the active lung phase of a patient with tocainide pulmonary toxicity. Gallium uptake in the lungs, an interstitial pneumonitis with alveolar macrophages on transbronchial biopsy, and reversal of process with discontinuation of the drug indicate a pulmonary drug reaction. The high resolution CT scan defined alveolar and interstitial components to the lung abnormality and correlated closely with the pathologic findings. High resolution CT is a useful method for demonstration of fine lung morphology.

Aged↗
PubMed1988

CT densitometry of pulmonary nodules in a frozen human thorax.

The influence of (1) calcium concentration, (2) exposure technique, (3) reconstruction algorithm, (4) nodule size, and (5) nodule location on the CT attenuation values (CT density) of pulmonary nodules was examined in a frozen human thorax. Nodules with calcium concentrations of 0-310 mg/ml and diameters of either 0.95 or 1.59 cm were inserted into a frozen, unembalmed human thorax. The nodules were placed either at the lung apex or 4 cm below the tracheal carina. Each nodule was scanned on a GE CT 9800 scanner; five different exposure techniques were used. The slice thickness was uniformly 1.5 mm. As expected, increasing the kilovoltage caused a significant decrease in CT nodule density in all nodules with calcium concentrations greater than 80 mg/ml. The inverse relationship between kilovoltage and nodule density was exaggerated with increasing calcium concentration. A high-resolution (bone) algorithm gave a significantly higher CT number than did a smoothed (standard) algorithm, regardless of nodule size and location, but this difference could be attributed almost entirely to the edge-enhancement effect of the bone algorithm. The CT density of the larger nodules was significantly higher than that of the smaller nodules at calcium concentrations greater than 65 mg/ml for both standard and bone algorithms. Densities were significantly higher in the mid lung than in the apex with a standard algorithm, but this was not the case with a bone algorithm. The GE CT 9800 scanner had a linear response between CT density and increasing calcium concentration within the confines of a human thorax. A high-resolution (bone) reconstruction algorithm has higher spatial resolution but does show an edge-enhancing effect not found with the smoothed algorithm. Two major variables in CT densitometry for pulmonary nodules are the kilo electron voltage of the X-ray beam and the reconstruction algorithm used; these two parameters should be standardized, with a high kilovoltage and high-resolution algorithm favored on the GE CT 9800 scanner.

Absorptiometry, Photon↗
PubMed1987

Pulmonary lymphangitic spread of carcinoma: appearance on CT scans.

Chest computed tomography (CT), including high-resolution CT with thin (1.5-mm) sections was used to evaluate proved (pathologically or clinically) lymphangitic spread (LS) of tumor in 12 patients. These appearances were compared with thin-section scans obtained in 11 healthy subjects. Thin-section CT demonstrated findings consistent with thickening of the normal lung interstitium. In all patients, thin sections showed an increase in the number of peripheral lines (1-2 cm in length) that were diffuse in generalized disease and localized in focal disease. Normal peripheral arcades were not increased in number, but the limbs forming the arcades were thickened in all patients. A diffuse increase in linear and curvilinear structures (reticular pattern) was seen toward the center of the lung. Polygonal structures 1-2 cm in diameter were seen in seven patients with LS but not in healthy subjects. Fissures were thickened in nine patients. Selected 1.5-mm-thick CT sections are recommended through abnormal areas (seen at CT or on chest radiographs) or if these are normal at three levels (midapex, hilus, and 3 cm above the diaphragm) when scanning patients with tumors known to cause LS.

Adult↗
PubMed1987

High-resolution CT of the lungs: an optimal approach.

The influences of kilovolt peak, milliamperage, reconstruction algorithm, targeting, and image magnification on thin-section (1.5-mm) computed tomography (CT) of the lung were studied in phantoms and patients. Retrospective targeted reconstruction (25-cm field of view) improved spatial resolution, while magnification did not. The bone reconstruction algorithm improved spatial resolution, compared with the standard algorithm, and in patients, bone algorithm images were considered superior to standard reconstructions. Although using the bone algorithm increases the visible image noise, increasing the kilovolt peak and the milliamperage can reduce this noise. However, in the patients studied, this reduction in noise was not usually judged as significant, except in the posterior, paravertebral part of the lung. An optimal technique for CT of the lung parenchyma should include thin-collimation, targeted scans reconstructed with a high-spatial-frequency algorithm and, in some patients, increased kilovolt peak or milliamperage.

Bone and Bones↗
PubMed1987

Cine CT in obstructive sleep apnea.

The upper airway was evaluated in eight patients with obstructive sleep apnea by using a rapid sequential CT scanner (Imatron C-100). Four patients also had simultaneous polysomnograms to determine the onset of sleep and apnea. The upper airway was scanned while the patient was awake (eight patients), asleep (four patients), and asleep and apneic (eight patients). Measurements of the cross-sectional area of the upper airway were correlated with the findings on sleep studies in four patients. During the awake state the airway was narrowed and showed increased collapsibility in all eight patients. Five of the eight patients had cross-sectional areas of less than or equal to 4 mm2 at one or more sites at some time during the respiratory cycle while awake. During apnea all patients had obstruction at the uvula and oropharynx, but the length of the obstruction varied from one patient to another. In three of the eight patients the obstruction extended inferiorly to the hypopharynx. Cine CT can be used to objectively evaluate patients with sleep apnea and may demonstrate the need to modify surgical treatment.

Adult↗
PubMed1986

Percutaneous biliary drainage: complications of 118 consecutive catheterizations.

We have reviewed our experience with 118 biliary catheterization procedures in 109 patients from 1979 to 1984. Major complications (septic shock, hemorrhage, subphrenic abscess, and formation of an arteriovenous fistula) occurred in five patients (4.2%), three of whom died (2.5%). Minor complications occurred in 41 patients. Our success rate using the procedure was 97%. The complications that occurred are described.

Bile Ducts↗
PubMed1986

MR imaging of pulmonary emboli: an experimental study in dogs.

Experimental pulmonary emboli, consisting of tantalum-labeled autologous blood clots and barium-labeled 3-mm plastic spheres that did not produce an MR signal, were introduced through the femoral vein into each of five dogs. The sensitivity of MR to detect autologous clots of known size was assessed, and the size of the clot on MR was compared with its actual size. Emboli were localized by using chest radiographs made in multiple projections. Cardiac-synchronized MR imaging was performed on a 0.35-T superconducting magnet and was followed by a 99mTc macroaggregated lung scan. All 12 blood clots larger than 3 mm, and three of 20 clots less than 3 mm in transverse diameter were correctly visualized with MR. Five of the 15 clots seen on MR were larger than 150% of the actual size. There were nine false-positive emboli on MR. Two of six plastic spheres resulted in an abnormal signal on MR. MR signal from pulmonary emboli results from the thrombus itself and probably also from slow blood flow proximal to the obstruction. MR may be of value in detecting pulmonary emboli; clinical trials to evaluate its usefulness should be carried out.

Animals↗
PubMed1985

Postperfusion xenon-133 ventilation scintigraphy with a narrow window.

Xenon-133 postperfusion lung scintigraphy using 10% windows was compared with standard posterior preperfusion 133Xe ventilation scanning in 33 patients. The postperfusion 133Xe study identified all major defects and washout abnormalities. In five patients, the assessment of match or mismatch of defects was improved because of optimal positioning of the postperfusion ventilation study. Computer subtraction of background technetium-99m macroaggregated albumin activity improved detection of mild washout abnormalities in eight patients but did not change the diagnostic category in any case. Postperfusion ventilation scanning using 10% windows (with or without background computer subtraction) is an alternative to preperfusion ventilation scanning for major V/Q abnormalities.

Adult↗
PubMed1982

Asymptomatic isolated left subclavian artery with right aortic arch. A case report.

An isolated left subclavian artery with a right-sided aorta was discovered during autopsy of a 34-year-old Black woman who had died of pulmonary tuberculosis. The left subclavian artery arose from the end of a 5 cm long, fibrous cord attached to the pulmonary trunk, and received blood by retrograde flow in the left vertebral and supreme intercostal arteries. Isolated subclavian artery with right-sided aorta may be accounted for by abnormal development and degeneration of the embryonic aortic arches.

Adult↗
PubMed1982

High-quality imaging of a left atrial tumour using real-time two-dimensional echocardiography.

A patient with a large left atrial mass is described in whom real-time two-dimensional (2-D) echocardiography provided images of exceptionally high quality. The mass was pedunculated, attached to the lower interatrial septum, appeared jelly-like in consistency and prolapsed into the mitral orifice during diastole. These features are characteristic of a left atrial myxoma. The importance of real-time 2-D echocardiography in the diagnosis of atrial tumours, and especially that of the subxiphoid view, is discussed.

Echocardiography↗
PubMed1976

Effects of hypertensive plasma on the responses of an isolated artery preparation to noradrenaline.

The effect of hypertensive plasma on the responses of an isolated artery preparation to noradrenaline were studied. In addition, because of the association between hypercholesterolaemia and hypertension, the effect of pure cholesterol and low density lipoprotein on the arterial responses to noradrenaline was also investigated. Both hypertensive plasma and low density lipoprotein potentiated the responses of the arterial preparation to noradrenaline.

Animals↗
PubMed1976

Noradrenaline sensitivity of an isolated perfused artery: effects of normal and hypertensive plasma.

1. The noradrenaline sensitivity of the isolated perfused rabbit artery was studied, during perfusion with Krebs solution, normal plasma, hypertensive plasma and a low-density lipoprotein (LDL) extract of normal plasma. 2. There was no difference in noradrenaline sensitivity between arteries perfused with Krebs and normal plasma. 3. Both hypertensive plasma and LDL potentiated the noradrenaline-induced vasoconstriction. 4. This potentiation was associated with increases in both the intrinsic activity of the drug-receptor complex and the drug-receptor affinity. 5. There is a circulating factor in the plasma of hypertensive patients which sensitizes arteries to noradrenaline, and this factor may be LDL.

Animals↗
PubMedDate not supplied

The medial acetabular wall: normal measurements in different population groups.

Measurements of the acetabulum and particularly the medial acetabular wall were done on 90 skeletons. Mean and standard deviations for different population groups are presented. The purpose of this study was to establish the normal range of values for the thickness of the medial wall of the acetabulum. This information is of value for the radiologist and the orthopaedic surgeon in the pre- and intraoperative assessment of the bone reserve of the acetabular fossa in hip surgery.

Acetabulum↗
PubMedDate not supplied

Computed tomography of diffuse tracheal stenosis in Wegener granulomatosis.

A patient with Wegener granulomatosis presented with diffuse tracheal narrowing and was evaluated using CT and cine-CT. The CT findings included severe laryngeal and tracheal airway narrowing, due to abnormal soft tissue within the laryngeal cartilages and tracheal rings, and enlarged abnormally calcified tracheal cartilages. Computed tomography precisely confirmed the site, level, and submucosal extent of tracheal narrowing, not obtainable on physical or bronchoscopic examination, and assisted in choosing a site for tracheostomy. Wegener granulomatosis should be considered in patients with diffuse tracheal narrowing even when the typical histology is not present.

Adult↗