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Biomedical subjects

G Gamsu

Publications and source records attributed to G Gamsu.

At least 73 records · Page 4Linked to original sources
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↗
PubMed1988

MR imaging of the transverse sinus of the pericardium.

On MR images of the chest, a low-signal-intensity band is often seen between the ascending aorta and left atrium in the transverse plane, and between the right pulmonary artery and left atrium in the coronal and sagittal planes. CT and MR of cadavers, with injection of contrast media into the pericardial space, confirmed that this structure was the transverse sinus of the pericardium. Retrospective review of MR studies in 45 patients without evidence of pericardial disease showed the transverse sinus of the pericardium in 80% (32/40) of transverse ECG-gated images, 78% (7/9) of sagittal ECG-gated images, and 67% (14/21) of coronal ECG-gated images. Nongated studies showed the sinus infrequently. Knowledge of the three-dimensional anatomy of the transverse sinus of the pericardium and of its typical MR appearance should allow its recognition and preclude misinterpretation.

Adolescent↗
PubMed1988

High-resolution CT of benign asbestos-related diseases: clinical and radiographic correlation.

We prospectively analyzed benign asbestos-related pleural and parenchymal abnormalities on high-resolution CT scans and correlated them with clinical diagnoses in 100 asbestos-exposed workers. All subjects had high-resolution CT scans in conjunction with conventional CT at the time of clinical evaluation. To evaluate for asbestosis, we ranked high-resolution CT scans as high, intermediate, or low probability of asbestosis on the basis of the multiplicity and extent of observed parenchymal changes. By linear regression analysis, the most distinctive high-resolution CT features of asbestosis included thickened nondependent interstitial short lines and parenchymal bands. In 45 subjects satisfying clinical criteria of asbestosis, high-resolution CT probability of asbestosis was high in 38 (84%), intermediate in five (11%), and low in two (4%). In 20 (36%) of 55 subjects without clinical asbestosis, parenchymal abnormalities indicative of a high probability of asbestosis were observed on high-resolution CT. High-resolution CT probability scores had a strong positive correlation with chest radiographic profusion scores (p less than .0001) and asbestos-related pleural thickening (p less than .0001). Significant inverse correlations were seen with forced vital capacity (p less than .006) and single-breath diffusing capacity (p less than .03), both functional measures of restrictive interstitial lung disease. Neither clubbing nor rales were sufficiently prevalent to have statistical correlation with high-resolution CT scores. High-resolution CT is sensitive in detecting both pleural and parenchymal abnormalities in the asbestos-exposed subject. Asbestos-related pleural changes are observed more frequently on high-resolution CT than on conventional CT or chest radiography. The probability of asbestosis based on high-resolution CT parenchymal features has a significant correlation with existing clinical determinants of disease, and high-resolution CT can detect abnormality when other methods are not diagnostic.

Adult↗
PubMed1987

Carcinoids associated with multiple endocrine neoplasia syndromes.

Carcinoids occur in association with MEN types 1 and 2. To determine the relationship between carcinoids and MEN, we reviewed nine patients with carcinoids and other endocrine tumors. Analyzing these 9 patients and 56 other patients previously described in the literature, we found several clinically important relationships. In contrast to the usual midgut and hindgut origin, most carcinoids associated with MEN (69 percent) are of foregut origin (thymus 24 percent, bronchus 27 percent, stomach 3 percent, and duodenum 14 percent). Carcinoids are more commonly associated with MEN type 1 than MEN type 2 (59 patients and 6 patients, respectively). Thymic carcinoids associated with MEN are more common in men (15 versus 2), and most (82 percent) are malignant. Bronchial carcinoids associated with MEN are more common in women (15 versus 4), and most (74 percent) are benign. There is a strong association between thymic carcinoids and parathyroid tumors and between bronchial carcinoids and pituitary tumors. Most patients with carcinoids and hyperparathyroidism (82 percent) have had parathyroid hyperplasia or multiple parathyroid adenomas. Thus, carcinoids may occur in association with both MEN type I and MEN type II. MEN should be suspected in patients with foregut carcinoids. Patients with MEN and ectopic ACTH production should be considered to have bronchial carcinoids if they are female and thymic carcinoid if they are male. The thymus should be routinely removed in patients with MEN type I because of the possible presence of an ectopic parathyroid gland in this tissue and to prevent subsequent development of a carcinoid tumor.

Adolescent↗
PubMed1987

A preliminary study of MRI quantification of simulated calcified pulmonary nodules.

The potential of magnetic resonance imaging (MRI) quantification of calcium for the evaluation of pulmonary nodules was investigated in simulated nodules. Calcium salts do not contain mobile protons and thus have no signal on MR proton images. To determine whether the absence of signal from partially calcified nodules could be quantified, we studied simulated nodules containing known quantities of calcium salts. The soft tissue equivalent material was an agar-gelatin mixture (T1:1100-1500 msec; T2: 59-62 msec). In the first experiments, glass tubes were filled with the mixture, which contained suspensions of calcium carbonate (CaCO3) or silica dioxide (Si02), and were subjected to computed tomography (CT) scanning and MR imaging. In a second series of studies CaCO3 particles of various sizes (and therefore different surface-to-volume ratios) were similarly suspended and subjected to CT scanning and MR imaging. In a third series hydroxyapatite (HA) suspensions of different sizes were similarly studied. CaCO3 produced a significant reduction in MR hydrogen density and signal intensity of the agar-gelatin mixture. Reduction in T1 and T2 relaxation times was inconsistent and not related to particle size. CaCO3 produced its effect by soft-tissue displacement. HA (and Si02) caused a more marked fall in MR hydrogen density, signal intensity, and T1 and T2 relaxation times. The degree of the T1 and T2 effects was related to particle size, indicating a hydrophilic surface effect. The authors conclude that MRI quantification of calcium within pulmonary nodules (or other tissues) will be complex and will relate to the precise composition of the calcium salt and to the particle size of the aggregates.

Calcinosis↗
PubMed1987

Mediastinal distortions from focal masses: a CT and radiographic study.

Fifty-seven mediastinal masses were studied by computed tomography (CT) and chest radiographs to determine how their specific site of origin affected their direction of expansion and the distortion of contiguous structures. Forty-four masses arose anterior to the heart and great vessels (precardiovascular compartment). When these masses arose on the right, they extended posteriorly only as far as the coronal plane of the trachea. Left-sided masses were not similarly limited in their posterior extension. Thirteen masses arose around the trachea and esophagus or in the subcarinal space (tracheoesophageal compartment). Masses in the upper part of this compartment caused tracheal and great-vessel displacement. The mobile superior vena cava (SVC) was more often distorted than was the aortic arch. Subcarinal masses always expanded to the right, displacing the right lower lobe. The heart and great arteries were more resistant to displacement and distortion than were the systemic veins. The trachea and mediastinal bronchi were intermediate in their displacement. The hila were effective barriers to the expansion of mediastinal masses.

Adolescent↗
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

Fatal systemic arterial air embolism following lung needle aspiration.

Fatal systemic arterial air embolism occurred as a complication of percutaneous fine-needle aspiration of the lung, immediately following cytologic sampling of a vasculitic lesion of Wegener granulomatosis. This complication is extremely rare, and it may have been caused by the biopsy of abnormal veins, in which transmural inflammation prevented the normal vasoconstrictive responses to injury.

Biopsy, Needle↗
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↗
PubMed1987

Determination of obstructive site in obstructive sleep apnea.

Patients with obstructive sleep apnea syndrome (OSAS) may have airway obstruction at various levels, including the uvula-soft palate complex, base of tongue, and/or possibly other sites. For patients with tongue base and/or laryngeal obstruction, uvulopalatopharyngoplasty (UPPP, ppp) will not alleviate the obstruction. Prior authors have proposed that the hyoid bone position as determined by cephalometric x-rays can predict which patients have obstruction at a lower site than the soft palate. In this study, patients with obstructive sleep apnea syndrome were evaluated with polysomnographic testing, fiberoptic endoscopy, and cine-CT scans (Imatron Scanner with multiple level rapid sequence scans) in an attempt to determine precisely the site of airway obstruction. Measurements of airway size taken at the time of fiberoptic pharyngoscopy were compared with those determined by the cine-CT studies. Initial results revealed that fiberoptic pharyngoscopy in the sitting and supine positions was helpful in confirming pharyngeal airway sites with smaller diameters in awake patients. However, the cine-CT exam performed in both sleeping and awake states provided more direct data regarding the airway during sleep. We feel that with more clinical experience the cine-CT technique will prove to be the most helpful study for identification of the obstructive airway site in obstructive sleep apnea syndrome.

Airway Obstruction↗
PubMed1986

Mediastinal masses: MR imaging.

Seventy-five patients with mediastinal masses were imaged with magnetic resonance (MR). Results were analyzed with regard to the ability of MR to demonstrate the masses, their morphology, and their encroachment or displacement of blood vessels and airways. T1 values were determined in 53 patients and T2 values in 59. Hydrogen density and percentage of contrast relative to muscle and fat were also obtained in 53 and 59 patients, respectively. MR images were compared with computed tomography (CT) scans, which were available in 45 patients. MR depicted all masses and demonstrated compromise of vessels and cardiac chambers owing to the inherent contrast between the masses and cardiovascular structures. Bronchogenic carcinoma had very long relaxation values for T1 and T2, while chronic inflammatory processes had intermediate values for T1 and T2, thus appearing less intense than bronchogenic carcinoma on T2-weighted images. Other neoplasms demonstrated T1 and T2 values between these two disease groups. Masses appeared less homogeneous on MR images than on CT scans, and vascular compromise was better assessed with MR. Thus, MR imaging is a completely noninvasive technique for the evaluation of mediastinal masses. While the anatomic information is comparable to that produced by CT, MR provides some insight into the composition of the mass.

Adolescent↗
PubMed1986

Normal thymus: assessment with MR and CT.

The magnetic resonance (MR) characteristics of the normal thymus in 18 patients were compared with computed tomographic (CT) findings in 13 of the 18. Patients ranged in age from 5 to 77 years. The thymus was visible in all patients and differed from subcutaneous fat in hydrogen density; the average thymus to fat hydrogen density ratio was 0.60. Although the T1 relaxation times of the thymus (mean = 703 msec) were much longer than those of fat (mean = 287 msec) in patients under 30 years of age, this difference decreased with age. The T2 relaxation times of the thymus were similar to those of fat and did not change with age. The thymus appeared thicker on MR images than on CT scans in patients older than 20 years. MR may be better than CT in distinguishing between thymus replaced by fat and mediastinal fat.

Adolescent↗
PubMed1986

Normal and occluded mediastinal veins: MR imaging.

The potential of magnetic resonance (MR) imaging to demonstrate the mediastinal veins was evaluated retrospectively in 25 patients with no evidence of a venous abnormality, 28 patients who had narrowing or occlusion of a mediastinal vein, and two patients who had a venous anomaly. In patients with venous occlusion, the MR images graphically demonstrated the sites and extent. MR images also demonstrated slow flow within venous structures proximal to the obstruction. Generally, venous collaterals in the mediastinum and chest wall were better seen with contrast material-enhanced computed tomography scans. The marked contrast on MR images between the signal void of normal vascular structures, the moderate signal intensity of tumor, and the high signal intensity of a thrombus or slowly flowing blood allows ready detection of venous occlusion and may suggest the nature of the occlusion.

Adolescent↗