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Biomedical subjects

J A Shepard

Publications and source records attributed to J A Shepard.

At least 37 records · Page 2Linked to original sources
PubMed1993

High-resolution CT of the lungs.

High-resolution computed tomography (CT) of the lung provides detailed visualization of the lung parenchyma. The technique involves the use of thin-section axial tomography. High-resolution CT can facilitate the diagnosis of certain pulmonary processes. It is useful in differentiating similar patterns of abnormalities seen on chest radiographs, such as those seen in lymphangitic carcinomatosis and sarcoidosis, and in delineating the extent of co-morbid lung diseases, such as emphysema and asbestosis. In some chronic processes such as idiopathic pulmonary fibrosis, high-resolution CT can be used for biopsy of areas of active inflammation, thus increasing the diagnostic yield. As clinicians and radiologists become more familiar with high-resolution CT, it is likely that its role in the diagnosis and assessment of lung disease will increase.

Algorithms↗
PubMed1993

Acute chest syndrome in sickle cell disease: CT evidence of microvascular occlusion.

Patients with sickle cell disease often develop acute chest syndrome (ACS). Signs of ACS include chest pain, fever, prostration, and pulmonary opacities. Pneumonia and infarction have been implicated in the pathogenesis of this syndrome. Infarction as a result of microvascular occlusion and pneumonia are not easily differentiated with chest radiography or ventilation-perfusion scintigraphy. The authors evaluated the ability of thin section (3-mm) chest computed tomography (CT) to help diagnose microvascular occlusion in ACS and thus help differentiate two of its most likely causes. CT scans of the chest of 10 patients with moderate to severe ACS were retrospectively reviewed by two observers, who listed the number of bronchopulmonary segments showing consolidation; areas of ground-glass attenuation due to early hemorrhagic edema; and paucity or absence of small vessels, arterioles, and venules. In all patients, the degree of hypoxia was out of proportion to the extent of consolidation evident at chest radiography. The CT scans showed microvascular occlusion and areas of ground-glass attenuation in nine patients. Infection was ruled out in eight patients. High-resolution CT may play an important role in the initial evaluation and timely selection of an appropriate treatment regimen aimed at improving tissue perfusion, thus forestalling irreversible organ damage and chronic pulmonary arterial hypertension in patients with sickle cell disease.

Acute Disease↗
PubMed1993

Pulmonary intravascular tumor emboli: dilated and beaded peripheral pulmonary arteries at CT.

The diagnosis of pulmonary intravascular tumor emboli is difficult to establish both clinically and on conventional radiographic studies. Between 1985 and 1991, four cases of pulmonary intravascular metastases were demonstrated on computed tomographic (CT) scans from among 14,000 CT scans of the chest. A retrospective study of these cases was performed, including a review of chest radiographs. All four patients had invasive tumors, including an atrial myxoma, a renal cell carcinoma, an osteosarcoma, and a chondrosarcoma of the pelvis. Three cases had histopathologic documentation of pulmonary artery tumor emboli. At CT, all the patients demonstrated multifocal dilatation and beading of peripheral pulmonary arteries, primarily in a subsegmental distribution involving multiple lobes. Ossification of the pulmonary arteries occurred in one case of metastatic osteosarcoma. In two cases, small, peripheral wedge-shaped opacities distal to some abnormal pulmonary arteries suggested pulmonary infarcts. The finding of dilated and beaded peripheral pulmonary arteries at CT is highly suggestive of metastatic intravascular tumor emboli.

Adolescent↗
PubMed1993

Chest CT in patients with scleroderma: prevalence of asymptomatic esophageal dilatation and mediastinal lymphadenopathy.

OBJECTIVE: The high-resolution CT findings of chronic diffuse interstitial lung disease associated with scleroderma have been reported previously. This study determined the prevalence of esophageal dilatation and mediastinal adenopathy on high-resolution CT scans in patients with this disease. MATERIALS AND METHODS: We retrospectively reviewed the high-resolution CT scans of 25 patients with scleroderma who had diffuse interstitial lung disease. Esophageal dilatation was diagnosed if the esophagus below the aortic arch had a single, large, nonloculated collection of intraluminal air on four or more consecutive axial images and if the luminal diameter of such an air-filled esophagus exceeded 10 mm in the coronal plane. The presence of fluid or an air-fluid level was also considered abnormal. For mediastinal adenopathy, we used the American Thoracic Society lymph node mapping scheme and the size criteria described previously. RESULTS: Asymptomatic esophageal dilatation was detected in 20 patients (80%) and mediastinal adenopathy was present in 15 (60%). CONCLUSION: Our results suggest that CT is useful in the detection of mediastinal adenopathy and asymptomatic esophageal involvement in patients with scleroderma. These findings can be used to narrow the differential diagnosis in patients in whom CT shows diffuse interstitial lung disease. Furthermore, the early detection of esophageal involvement in these patients shows the need for treatment to forestall the complications of esophageal dysmotility and accompanying chronic gastroesophageal reflux.

Adult↗
PubMed1992

Postpneumonectomy syndrome: diagnosis, management, and results.

Airway obstruction may be caused by extreme mediastinal shift and rotation after right pneumonectomy or after left pneumonectomy in the presence of a right aortic arch. Eleven adults (aged 18 to 58 years) with severe symptoms were treated surgically between 5 months to 17 years after pneumonectomy (7 right, 4 left). An initial patient with only one functional lobe was treated unsuccessfully by aortic division and bypass graft. Ten underwent mediastinal repositioning. After two recurrences prostheses were used to maintain mediastinal position. Five patients who underwent such repositioning are doing well from 5 months to more than 5 years later. One died 1 month after operation probably of pulmonary embolism. One who showed residual airway collapse after operation has some recurrent obstruction. Three other patients who showed severe malacic obstruction of the airway after mediastinal repositioning variously underwent aortic division with bypass graft and tracheal and bronchial resection. One is well almost 6 years later. Two died postoperatively. Occurrence of the syndrome is unpredictable. Where malacic changes have not occurred, mediastinal repositioning may reasonably be expected to correct obstruction. Optimal treatment for concurrent severely malacic airways is unclear.

Adolescent↗
PubMed1992

Bronchogenic carcinoma: analysis of staging in the mediastinum with CT by correlative lymph node mapping and sampling.

One hundred forty-three patients with bronchogenic carcinoma were studied prospectively with computed tomography (CT) to determine the accuracy of CT in the evaluation of mediastinal nodal metastases. Mediastinal lymph nodes were localized according to the lymph node mapping scheme of the American Thoracic Society and were considered abnormal if they exceeded 1 cm in short-axis diameter. All patients underwent surgical staging, which consisted of either mediastinoscopy alone or mediastinoscopy and thoracotomy. At the time of surgical staging, all accessible nodes were either removed or sampled. The sensitivity of CT for mediastinal nodes on a per-patient basis was 64%, with a specificity of 62%. The sensitivity of CT for individual nodal stations involved with tumor was only 44%. The presence of obstructive pneumonitis did not appreciably alter the sensitivity of CT, but the specificity was lower (43%). The likelihood of metastases increased with lymph node size; however, seven of 19 (37%) lymph nodes that measured 2-4 cm in short-axis diameter were hyperplastic and did not contain metastases. The relative insensitivity of CT makes formal nodal sampling at the time of mediastinoscopy or thoracotomy essential to detect lymph node metastases.

Adult↗
PubMed1991

Differentiation of bronchogenic carcinoma from postobstructive pneumonitis by magnetic resonance imaging: histopathologic correlation.

Obstructive pneumonitis frequently occurs distal to hilar bronchogenic carcinomas or in lung adjacent to peripheral tumors. The article evaluates the role of MRI in the differentiation of tumor from pneumonitis. Twelve patients underwent MRI of the thorax before surgery. T1-weighted (SE 310/20) and T2-weighted (SE 2000/60-120) images were obtained through the tumor and presumed areas of pneumonitis. Five histologic types of pneumonitis were identified on pathologic examination of the 12 specimens. Cholesterol pneumonitis, found in 7 patients, was the most common type. Organizing pneumonitis, bronchiectasis with mucus plugs, atelectasis, and abscess were found in 3, 4, 2, and 1 patients, respectively. MRI was able to differentiate tumor from pneumonitis in 5 of 6 patients with a hilar mass and in 5 of 6 patients with a peripheral tumor. This was achieved by a visual difference in signal intensity on heavily T2-weighted (SE 2000/120) images. Cholesterol pneumonitis and bronchiectasis with mucus plugs were always hyperintense relative to tumor, and organizing pneumonitis and atelectasis were isointense and indistinguishable from tumor. MRI can differentiate tumor from pneumonitis provided that pneumonitis is of the cholesterol type or if there are mucus plugs in the collapsed lung.

Aged↗
PubMed1991

Effect of patient positioning after needle aspiration lung biopsy.

Fifty-five patients who underwent fluoroscopically guided needle aspiration lung biopsy were randomly assigned to one of two postbiopsy treatment groups: Patients were placed recumbent with puncture site either down (n = 36) or up (n = 19) for at least 1 hour. No significant difference in pneumothorax rate was seen between the two groups. Chest tube placement, however, was required in 21% (four of 19) of the puncture-site-up group versus 3% (one of 36) of the puncture-site-down group, which was a significant difference (P = .04). Puncture-site-down postbiopsy positioning reduces the proportion of patients requiring chest tube placement after lung biopsy.

Biopsy, Needle↗
PubMed1990

Positional precautions in needle aspiration lung biopsy.

The authors performed 308 needle aspiration biopsies of parenchymal lung masses. The patients were then placed with the puncture site down for a period of at least 1 hour or until air leakage stopped. Coughing, talking, and activity were restricted. Complications included pneumothorax, at a rate of 25.0%, and chest tube placement, at a rate of 1.6%. In a subgroup of 262 patients who required only one pleural puncture at biopsy, a pneumothorax rate of 17.9% and a chest tube placement rate of 0.4% were encountered. When compared with a similar series of 143 control patients, significant reductions in both pneumothorax rate (P = .0004) and chest tube placement rate (P = .0001) were demonstrated.

Biopsy, Needle↗
PubMed1989

Coronary artery calcifications: significance of incidental detection on CT scans.

A scoring system was devised for the assessment of coronary artery calcifications apparent on computed tomographic (CT) scans, with width and length used to assess severity. The degree of calcification was compared with the presence of stenoses of 70% or greater at cardiac catheterization in 46 patients who underwent both studies. Although many significantly stenosed vessels showed no calcification, heavy calcifications had a high positive predictive value for significant disease. In a separate branch of the study, the perioperative cardiac morbidity and mortality were compared in 30 age- and sex-matched pairs of patients undergoing thoracotomy who did and did not have coronary calcifications on CT scans obtained before surgery. Patients with calcifications had a higher frequency of cardiac complications, including arrhythmias, ischemia, hypotension, myocardial infarction, and death.

Adult↗
PubMed1988

Transthoracic needle aspiration biopsy: evaluation of the blood patch technique.

A study was undertaken to evaluate the effectiveness of the blood patch technique in the prevention of pneumothorax after transthoracic needle aspiration biopsy. A total of 140 needle biopsies were performed with a coaxial system. Two groups of patients were defined according to whether or not autologous blood was injected into the introducing needle as it was withdrawn after needle aspiration biopsy. Fifty-two biopsies were performed with the blood patch technique (group A), while 88 biopsies were performed without the blood patch technique (group B). The frequency of postbiopsy pneumothorax was 28.8% (15 of 52 patients) in group A and 34.1% (30 of 88 patients) in group B. Chest tube insertion was required in 7.7% (four of 52 patients) in group A and in 9.1% (eight of 88 patients) in group B. There was no statistically significant difference in pneumothorax rate and chest-tube insertion rate between the two groups (P greater than .05). In this series of 140 biopsies, the blood patch technique failed to affect the rate of pneumothorax after transthoracic needle aspiration biopsy.

Biopsy, Needle↗
PubMed1987

Low-dose flying spot digital radiography of the chest: sensitivity studies.

Standard film examinations of the chest were compared with low-dose flying spot digital radiographic examinations obtained with a prototype unit in 174 patients. Analysis of pooled data from a double-blind study of 120 patients showed that film was more sensitive than digital images in the detection of pulmonary parenchymal abnormalities, that is, abnormal opacities, atelectasis, scar, and interstitial lung disease (P less than .05). Analysis of pooled data from a side-by-side study of 54 patients showed that the digital images were more sensitive than film in the detection of normal mediastinal and pleural soft-tissue contours, including the azygoesophageal recess, paraspinal line, and vertebral disk spaces (P less than .05). However, film was more sensitive than digital images in the detection of abnormalities of the lung, including scar, interstitial lung disease, septal lines, and the presence of vascular catheters (P less than .05). These findings suggest that low-dose flying spot digital radiography of the chest, as performed with this specific prototype unit, is not adequate to replace film in the detection of abnormalities of the lung parenchyma.

Adolescent↗
PubMed1987

Superior sulcus lung tumors. Results of combined treatment (irradiation and radical resection).

Twenty-one patients underwent combined therapy (irradiation and radical resection) for a Pancoast tumor at the Massachusetts General Hospital between 1976 and 1985. All patients underwent en bloc removal of the apical chest wall and underlying lung. In addition four patients required subclavian artery resection, and in five patients a portion of the vertebral body was resected. There were three operative deaths. Median survival was 24 months and actuarial survival rate was 55% at 3 years and 27% at 5 years. Long-term palliation of pain was achieved in 72% of the patients. Involvement of the subclavian artery, vertebral body, or rib did not preclude long-term survival. Computed tomographic scanning in these patients is often indeterminate regarding invasion of chest wall structures but is more helpful than plain films alone. When compared to recent series in which irradiation alone was used, the combined approach appears to produce better results.

Actuarial Analysis↗
PubMed1986

Right-pneumonectomy syndrome: radiologic findings and CT correlation.

The clinical history and radiographic and bronchoscopic findings were reviewed retrospectively in five patients with right-pneumonectomy syndrome, a rare, delayed complication of pneumonectomy of the right lung. Four patients had undergone pneumonectomy in childhood or adolescence. Presenting symptoms of dyspnea and recurrent pulmonary infections in the left lung were associated with radiographic evidence of marked rightward and posterior deviation of the mediastinum, counterclockwise rotation of the heart and great vessels, and herniation of the left lung into the right, anterior side of the chest. Computed tomography, performed in four patients, best demonstrated resultant compression of the distal trachea and left main bronchus between the aorta and pulmonary artery. Malacia of the major airways (n = 4 cases) and mediastinal shift was visualized only with fluoroscopy and was confirmed by bronchoscopy. Because of the morbidity and mortality associated with dyspnea and recurrent pulmonary infections, proper radiologic evaluation is crucial, and surgical intervention is often necessary.

Adolescent↗
PubMed1986

CT of adenoid cystic carcinoma of the trachea.

The CT features of six cases of adenoid cystic carcinoma of the trachea are presented and compared to the bronchoscopic, surgical, and pathologic findings. CT accurately demonstrated extratracheal extension of tumor, which occurred in all six cases and which was not visible on standard chest radiographs. This information was helpful in planning the surgical approach. However, CT consistently underestimated the longitudinal extension of the lesion because of partial volume averaging and the tendency of adenoid cystic carcinoma to grow submucosally. CT was also a poor predictor of mediastinal organ invasion. Because recent advances in tracheal resection and carinal reconstruction have made many of these lesions resectable, CT is frequently used in the evaluation of the operability of patients with adenoid cystic carcinoma. However, its usefulness in this regard is limited, and conventional techniques such as standard tomography continue to play a role in preoperative assessment.

Adult↗
PubMed1985

Pseudoprominent aorta: radiographic findings and CT correlation.

The presence of a persistent left-sided superior vena cava (LSVC) in the absence of a right-sided superior vena cava (RSVC) may be suspected on a posteroanterior (PA) chest radiograph because of a prominent-appearing ascending aorta, which results from the absence of the RSVC. In the absence of an RSVC, the right upper lobe abuts and outlines the course of the ascending aorta, allowing better demonstration of its profile. This report describes a patient with this finding on a PA chest radiograph. Computed tomographic correlation is presented.

Adult↗