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Biomedical subjects

G Gamsu

Publications and source records attributed to G Gamsu.

At least 181 records · Page 10Linked to original sources
PubMedDate not supplied

Temporal image database design for outcome analysis of lung nodule.

This paper presents the design of a temporal image database system and its application in thoracic imaging. The design of this information system is based on the client/server architecture. The system consists of a chest imaging database server, a library of image processing modules, a link to the picture archiving and communication system (PACS) archive, and a low end client workstation with motif-based graphic user interface (GUI). The database system can be used to aid the radiologists in quantitating solitary or multiple long nodules and in assessing effectiveness of therapeutic procedures for these lung cancers. The GUI allows a user to retrieve any patient study from PACS. After a nodule is visually identified, it will be segmented automatically to obtain relevant features, such as the center of mass, volume, and surface area. Such 3D nodule information, together with the patient textual information, is subsequently organized in the chest imaging database to facilitate outcome analysis.

Breast Neoplasms↗
PubMedDate not supplied

Radiographically determined lung volumes at full inspiration and during dynamic forced expiration in normal subjects.

Posteroanterior and lateral radiographs of the lungs of 30 normal adults were obtained at total lung capacity (TLC) and 1 sec after initiation of forced expiration from ttlc. simultaneous spirographic recording of the volume expired (FEV-1) and independent plethysmographic recording of TLC were obtained. Two types of measurements were made from the radiographs: 1) surface areas of the lung fields, measured planimetrically; and 2) combinations of linear distances between selected points. These radiographic measurements and the measured lung volumes were subjected to computer analysis to develop reliable formulas for determining lung volumes solely from radiographs. Formulas derived using planimetry produced multiple correlation coefficients of 0.95 for TLC and 0.89 for volume during forced expiration. Use of linear measurements produced multiple correlation coefficients of 0.92 for TLC and 0.84 for dynamic volume. Thus, in normal subjects, static lung volumes and lung volumes during dynamic forced expiration can be determined from radiographs.

Adult↗
PubMedDate not supplied

The effect of acute pulmonary edema on pulmonary vascular resistance: significance for the interpretation of dilated upper lobe vessels on chest radiographs.

Dilation of upper lobe pulmonary vessels is an important radiographic sign of acute, left heart failure. A prominent theory is that perivascular edema causes increased resistance at the lung bases and inverts the normal perfusion gradient such that upper lobe blood flow exceeds lower lobe flow. This theoretical increase in flow is thought to cause dilatation of upper lobe vessels. Previous experimental studies determined indirectly changes in resistance from changes in the perfusion gradient: Results were contradictory. We measured directly the effect of edema on resistance in isolated canine lungs. Resistance increased linearly with edema. The magnitude of increase was small, however, and insufficient to cause inversion of the perfusion gradient. Our data indicate that interstitial pulmonary edema does not cause significant redistribution of blood flow. We suggest that dilated upper lobe vessels are veins acting as pulmonary venous manometers, reflecting elevated left atrial pressure, not increased blood flow.

Acute Disease↗
PubMedDate not supplied

Absolute lung density in experimental canine pulmonary edema.

The noninvasive quantification of pulmonary edema could be of importance in patient management. We have developed a portable Compton-scatter densitometer capable of measuring density in the range of 0.1-1 g/cm3 independently of the chest wall. Change in lung density was investigated in 19 dogs with pulmonary edema induced by a combination of raised left atrial pressure and hemodilution. The increase in lung density correlated with the postmortem assessment of lung water (r = 0.862, p less than 0.01) and with hemodynamic indicators of pulmonary edema (r = 0.749, p less than 0.01). Subtracting the intravascular component of lung density did not improve the correlation with postmortem lung water (r = 0.850, p less than 0.01). The measurement of absolute lung density by a Compton-scatter technique may be a potentially useful method of quantifying pulmonary edema.

Absorptiometry, Photon↗
PubMedDate not supplied

Accelerated atherosclerosis during maintenance hemodialysis: detection from chest radiographs.

Evidence of accelerated atherosclerosis was studied from chest radiographs of 26 patients on maintenance hemodialysis. The aortic knob was observed for presence of and increase in calcified plaques. At the initiation of hemodialysis, the degree of aortic calcification was no different from that seen in the control group. After periods ranging from one and a half to eight years, the patients on hemodialysis showed a significantly greater amount of aortic calcification and a significantly higher rate of calcification. The degree of calcification correlated with the severity of cardiovascular disease as determined clinically. For patients on maintenance hemodialysis, close scrutiny of serial chest-radiographs may help to identify those who are at greater risk for life-threatening cardiovascular disease.

Adult↗
PubMedDate not supplied

CT-determined pulmonary artery diameters in predicting pulmonary hypertension.

This study was to determine if the diameters of pulmonary arteries measured from computed tomographic (CT) scans could be used 1) as indicators of pulmonary artery hypertension and 2) as a reliable base for calculating mean pulmonary artery pressure. The diameters of the main, left, proximal right, distal right, interlobar, and left descending pulmonary arteries were measured from CT scans in 32 patients with cardiopulmonary disease and in 26 age- and sex-matched control subjects. Diameters were measured using a special computer program that could display a CT density profile of the artery and its adjacent tissues. The upper limit of normal diameter for the main pulmonary artery was found to be 28.6 mm (mean + 2 SD). In the patient group, the diameters were correlated with data from cardiac catheterization. In these patients, a diameter of the main pulmonary artery above 28.6 mm readily predicted the presence of pulmonary hypertension. The calculated cross-sectional areas of the main and interlobar pulmonary arteries (normalized for body surface area [BAS]) were found to give the best estimates of mean pulmonary artery pressure (r = 0.89, P less than 0.001 and r = 0.66, P less than 0.001). Multiple regression analysis gave the useful equation: mean pulmonary artery pressure = -10.92 + 0.07646 X area of main pulmonary artery/BSA + 0.08084 X area of the right interlobar pulmonary artery/BSA (r = 0.93, P less than 0.0001). Because CT allows precise, noninvasive measurement of the diameter of pulmonary arteries, it can be of value in detecting pulmonary hypertension and estimating mean pulmonary artery pressure.

Adolescent↗
PubMedDate not supplied

CT of a bronchial phantom. Factors affecting appearance and size measurements.

In order to determine the most appropriate window settings for viewing CT of the bronchial tree, we performed CT of a bronchial phantom consisting of air-filled tubes measuring from 3.1 to 12.7 mm, oriented at varying angles relative to the scan plane, surrounded by water or air, and with scan collimation of 10 mm, 5 mm, and 1.5 mm. Using a computer program to graphically display CT number relative to the distance across the tube's lumen, it was found that a window mean of -150 H accurately estimated the internal diameter of tubes surrounded by water, at all angles, when collimation was 5 mm or 1.5 mm. With 10-mm collimation, tube diameter was slightly underestimated for tubes 9.5 mm or less when oriented 30 degrees or more from perpendicular to the plane of scan. At lower window settings and window widths of 500 H or less, all tube's diameters were significantly underestimated. At -150 H, with tubes parallel to and centered in the scan plane, 5-mm and 1.5-mm collimation were most accurate; with decentering of 4 mm, 10-mm collimation better showed the tube's lumen. When surrounded by air, tube wall thickness was best estimated using a window mean of -450 H.

Bronchi↗
PubMedDate not supplied

Sagittal MR imaging of the chest: normal and abnormal.

To determine the value of sagittal magnetic resonance (MR) in diagnosing thoracic abnormality, we reviewed the multisection sagittal spin-echo MR images of 13 normal subjects and 23 patients with a variety of thoracic abnormalities. In the abnormal subjects sagittal images were compared with transaxial MR performed with repetition time values of both 0.5 and 2.0 s. Sagittal images were most helpful in the evaluation of structures lying in the sagittal plane such as the thoracic aorta. Mediastinal masses in most locations were better seen and evaluated in the transaxial plane. However, the relationship of subcarinal masses to the trachea, left atrium, and pulmonary artery was better appreciated in the sagittal plane. The relationship of hilar masses to hilar vessels, bronchi, and the mediastinum was usually better seen on transaxial images. Also, the relationship of paramediastinal masses to the mediastinum was difficult to evaluate with sagittal scans.

Adolescent↗
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↗
PubMedDate not supplied

Pulmonary function abnormalities in patients with CT-determined emphysema.

The CT quantification of both the extent and severity of emphysema was undertaken in 30 subjects. The CT scans at five preselected anatomic levels were analyzed using two methods. Correlation of the results of the CT methods were with pulmonary function results of airway obstruction and alveolar diffusion for carbon monoxide. Analysis by direct observation of the CT scans gave insignificantly different results for a complex grid method of analysis. The emphysema score with the observational method had a positive correlation with airflow obstruction (r = -0.817) as did the score with the grid method (r = -0.873). The diffusing capacity for carbon monoxide also correlated with both emphysema scores. The CT methods for quantifying emphysema correlate closely with functional abnormalities. As previously demonstrated with pathological assessment of lung slices for emphysema, direct observation of CT scans is as precise as a more complex grid method.

Aged↗
PubMedDate not supplied

MR imaging of low signal intensity pulmonary lesions using flow-sensitive techniques.

Various spin echo techniques can be used to define the nature of low signal intensity lesions of the lung. A pulmonary arteriovenous malformation and a chronic pulmonary hematoma had a similar appearance on standard spin echo magnetic resonance (MR) images. Both lesions demonstrated central absence of signal surrounded by a thin rim of tissue, suggesting a vascular lesion. For further characterization of these lesions, a rotating gated MR technique was used in which images are obtained at different points in the cardiac cycle, such that pulsatile flow alters signal intensity with velocity changes during the cardiac cycle. Phase images also discriminated flowing blood in the arteriovenous malformation from stationary lung tissues, whereas the hematoma was not distinguished from lung parenchyma. Rotating gated sequences and reconstructed phase images may be useful in determining the etiology of low signal intensity pulmonary lesions.

Adult↗
PubMedDate not supplied

Computed tomography in pulmonary sarcoidosis.

We studied the high resolution CT (HRCT) scans of 15 patients with biopsy-proven sarcoidosis and correlated the findings with pulmonary function tests (12 patients), 67Ga scans (10 patients), bronchoalveolar lavage (five patients), recent transbronchial biopsy (six patients), and recent open lung biopsy (three patients). The HRCT features included small nodules, thickened interlobular septa, patchy focal increase in lung density, honeycombing, and central conglomeration of vessels and bronchi. Active alveolitis was present by gallium scanning criteria in 5 of 10 cases. By bronchoalveolar lavage criteria, activity was present in three of five cases. Patchy increase in density may correlate with active alveolitis as seen on 67Ga scanning. High resolution CT was better than chest X-radiography for demonstration of patchy increase in density and for distinguishing nodules from septal thickening. Both nodules and patchy density were partly reversible following therapy. Nodular densities seen on CT correlated with the presence of granulomata on histology. Resting pulmonary function tests correlated poorly with presence and extent of lung disease on HRCT. The presence on HRCT of focal fine nodules, patchy focal increase in lung density, and central crowding of bronchi and vessels should suggest the diagnosis of sarcoidosis. In some patients, HRCT can identify unsuspected parenchymal lung disease and document the reversible components of sarcoid lung disease.

Bronchoalveolar Lavage Fluid↗
PubMedDate not supplied

MR imaging of the larynx at 1.5 T.

The normal magnetic resonance (MR) anatomy of the larynx at high field strength (1.5 T) was studied in 2 normal excised larynges and 62 subjects without laryngopharyngeal disease. The two normal excised larynges were imaged using a 1.5 T MR scanner with a 3 in diameter circular surface coil and a GE 9800 CT scanner. The larynges were sectioned transversely and the MR and CT images compared to gross and histologic sections. Unossified hyaline cartilage was intermediate in signal intensity on T1-weighted and proton density images and low in intensity on T2-weighted images. The signal intensity from ossified cartilage was determined by the amount of fatty marrow and was high in intensity on T1-weighted and proton density images and low to intermediate in intensity on T2-weighted images. A chemical shift artifact from high intensity fatty marrow obscured the calcified or ossified cortex of the major laryngeal cartilages along the frequency encoding axis. The epiglottic cartilage demonstrated an intermediate signal intensity on T1-weighted images and higher intensity on proton density and T2-weighted images. The intralaryngeal muscles were well demonstrated as low intensity structures. The conus elasticus and the vocal ligaments were not recognized as distinct structures. However, the quadrangular membrane and a previously undescribed membrane separating the preepiglottic and paralaryngeal spaces were shown on MR as low intensity linear structures. In the 62 subjects, MR at 1.5 T proved excellent for demonstrating the anatomical details of the major laryngeal cartilages, extra- and intralaryngeal muscles, ligaments, and soft tissues including the vocal cords, false vocal cords, laryngeal ventricles, aryepiglottic folds, preepiglottic space, and paralaryngeal spaces. Visibility and intensity of muscles, ligaments, and soft tissues did not depend on age or sex. The intensity pattern of the thyroid and cricoid cartilages demonstrated wide variations in the same sex and age groups, depending on the degree of ossification. However, they did show more high intensity foci in older men than in younger women. Magnetic resonance showed better contrast resolution and finer detail than CT scans in the same subjects. Magnetic resonance imaging at 1.5 T, with either a saddle-shaped neck surface coil or a 3 in diameter circular surface coil, provides high contrast and high spatial resolution images and could be useful for the diagnosis of lesions of the larynx.(ABSTRACT TRUNCATED AT 400 WORDS)

Female↗
PubMedDate not supplied

Pulmonary artery dissection: MR findings.

We report a case of pulmonary artery dissection imaged by MR. Dissection of a markedly dilated pulmonary artery is a rare and usually fatal complication of chronic pulmonary arterial hypertension. The diagnosis is made at autopsy, with only two cases having previously been documented (by Doppler echocardiography) during life. The hallmark of an arterial dissection is the finding of an intimal flap and a false lumen. In our case, spin echo MR imaging failed to show either the intimal flap or any intraluminal signal defects. The dissection was presumably obscured by nonhomogeneous intraluminal signal caused by the slow blood flow associated with severe pulmonary arterial hypertension. Cine MR imaging, however, demonstrated different signal intensity within the true and false lumens of the dissection, thereby outlining the intimal flap between the two channels.

Adult↗
PubMedDate not supplied

Enhancement of thoracic masses using nonionic MR contrast agents.

OBJECTIVE: This study evaluated the effect of a new nonionic MR contrast medium, gadodiamide injection (Omniscan; Sanofi-Winthrop), on enhancement of thoracic masses on T1-weighted SE images. MATERIALS AND METHODS: Gadodiamide injection was administered intravenously at a dose of 0.2 mmol/kg to 26 patients with thoracic masses. The T1-weighted images with and without fat suppression and T2-weighted images obtained before contrast medium injection were compared with T1-weighted images obtained at 5, 30, and 45 min and a T1-weighted fat-suppressed image at 10 min after administration of the contrast medium. Enhancement of the thoracic masses and image quality were quantified by measuring signal intensity, signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) using muscle and fat as reference tissues. RESULTS: The SNR of the masses increased significantly (p < 0.001) following contrast material injection both on standard T1-weighted sequences and on T1-weighted fat-suppressed images when compared with the precontrast T1-weighted images with and without fat suppression. The CNR (reference tissue muscle) improved significantly (p < 0.001) after contrast medium injection and persisted for 45 min on T1-weighted images compared with those prior to contrast medium. However, there was no significant difference in CNR between the T2-weighted images obtained before and the T1-weighted images obtained after contrast agent administration. On the other hand, the SNR of contrast-enhanced images was significantly better than that of the T2-weighted images. When fat was used as a reference tissue, CNR of the thoracic masses decreased significantly. CONCLUSION: This study shows that gadodiamide injection caused significant enhancement of thoracic masses on T1-weighted images, which rendered high signal intensity to the masses similar to the appearance on T2-weighted images. In comparison with the T2-weighted images, SNR was significantly improved.

Adolescent↗
PubMedDate not supplied

Tree-in-bud pattern: frequency and significance on thin section CT.

PURPOSE: Our goal was to describe those diseases of the airways that manifest the tree-in-bud (TIB) pattern on CT scan and to establish a differential diagnosis for this CT scan finding. METHOD: We prospectively collected cases with the TIB pattern on CT and reviewed the scans of patients with histories pertaining to small airway disease. CT scans were performed at 1 to 3 mm collimation. RESULTS: Twenty-six of 27 cases with the TIB pattern had associated bronchiectasis or proximal airway wall thickening. One case with normal proximal airways had an acute aspiration. In addition, we reviewed 141 scans of patients with emphysema, respiratory bronchiolitis (RB), bronchiolitis obliterans (BO), bronchiolitis obliterans organizing pneumonia (BOOP), extrinsic allergic alveolitis (EAA), bronchiectasis, bronchitis, and pneumonia. Of the CT scans with bronchiectasis, 25.6% had TIB, and 17.6% of CT scans with acute infectious bronchitis or pneumonia had this pattern. None of the patients with emphysema, BO, BOOP, EAA, or RB had this pattern. CONCLUSION: The TIB pattern on CT scan is mostly associated with pulmonary infections that commonly involve the large airways. This pattern was present in 17.6% of cases with acute bronchitis or pneumonia and 25.6% of cases with bronchiectasis.

Adolescent↗