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Biomedical subjects

J A Shepard

Publications and source records attributed to J A Shepard.

51 records · Page 3Linked to original sources
PubMed1985

Computed tomography of localized pleural mesothelioma.

The computed tomographic (CT) features of six pathologically proven cases of fibrous mesothelioma were reviewed. There were no pathognomonic CT characteristics, but in all cases CT suggested or supported the preoperative diagnosis. CT findings included well delineated, often lobulated, noncalcified soft-tissue masses in close relation to a pleural surface, associated crural thickening, and absence of chest wall invasion. An obtuse angle of the mass with respect to the pleural surface was not particularly useful. Rather, a smoothly tapering margin was more characteristic of a pleural lesion.

Aged↗
PubMedDate not supplied

Pseudometastases secondary to film static artifact.

Low density areas in the liver on computed tomography (CT) may be produced by cysts, abscesses, or tumors. A case is reported in which film static resulted in multiple focal low density areas in the liver in a patient with lymphoma. This potential pitfall in CT interpretation can be avoided by taking proper measures to avoid film artifacts and by reviewing all cases on the cathode ray tube (CRT) display as well as the hard copy film.

Adult↗
PubMedDate not supplied

Computed tomography of the tracheal bronchus.

Tracheal bronchus is an uncommon anomaly in which an ectopic bronchus arises from the trachea above the carina. It occurs on the right side and two types are described: "supernumerary," which is associated with a normal trifurcating right upper lobe bronchus, and "displaced," in which instance the ectopic bronchus supplies the apical segment of the upper lobe. The CT appearance of this anomaly is described in two cases. Findings include identification of a bronchus arising from the trachea in a section more cephalad than the carina and the presence of only two segmental bronchi arising from the anatomic right upper lobe bronchus when the anomaly is of the "displaced" type. Thin axial sections and coronal imaging display the tracheal bronchus to best advantage.

Aged↗
PubMedDate not supplied

CT findings in localized fibrous mesothelioma of the pleural fissure.

Three patients with fibrous mesothelioma of a pleural fissure are presented. Although the appearance of lung surrounding a mass is typical of an intraparenchymal lesion, attention to the position of the mass in relationship to the fissure may suggest the possibility of a pleural mass. Localized fibrous mesothelioma should be included in the differential diagnosis of an apparent solitary lung mass located in the region of a fissure.

Diagnosis, Differential↗
PubMedDate not supplied

MR imaging of superior sulcus carcinoma.

Magnetic resonance (MR) imaging was performed in 10 patients with biopsy proven superior sulcus carcinomas to determine the extent of local tumor invasion. Chest wall invasion or extension into the base of the neck was demonstrated in five patients. This finding was facilitated by the contrast between the bright signal intensity of tumor and the low signal intensity of muscle on T2-weighted images. In three patients, MR clearly depicted direct invasion of the mediastinum. This finding was facilitated on the MR image because of inherent contrast between the mediastinal fat and tumor. Coronal and sagittal images showed the relationship of tumor to the subclavian artery and brachial plexus in all cases. Encasement of the artery was confirmed in two cases and brachial plexus involvement in three. However, MR failed to detect evidence of rib destruction in five patients in whom rib involvement was confirmed by other studies. Magnetic resonance appears to be a useful imaging modality in determining the extent of local disease and, therefore, the selection of patients for surgical resection. Multiplanar imaging and contrast between tumor and muscle and tumor and fat allow assessment of invasion of the mediastinum and base of the neck, subclavian artery, and brachial plexus.

Adult↗
PubMedDate not supplied

Normal position of trachea and anterior junction line on CT.

OBJECTIVE AND METHODS: In unilateral diseases of the chest accompanied by either volume loss or expansion there is mediastinal shift and mediastinal "herniation" of one lung into the opposite hemithorax. This may also be accompanied by changes in the size of the hemithoraces. Although early detection of these changes may be difficult on chest radiography, one can detect all these changes on CT with greater ease. Since the normal range of position of the mediastinal structures on CT and the symmetry of the hemithoraces have not been studied before, we conducted a prospective study of normal chest CT to define the range of position of the trachea and the anterior junction line, as well as the normal range of differences in the parasagittal diameters of the two hemithoraces. RESULTS: The trachea was < or = 1.6 cm to the right and 0.7 cm to the left of midline; the anterior junction line was < or = 1 cm to the right and 2 cm to the left. The hemithoraces were asymmetric in 84%, with the difference in the parasagittal diameters of the two hemithoraces < or = 1.5 cm. CONCLUSION: These data may help radiologists detect subtle mediastinal shifts and asymmetry in patients with unilateral pleural or pulmonary disease.

Humans↗
PubMedDate not supplied

Dual kV CT to detect calcification in solitary pulmonary nodule.

OBJECTIVE: At the high kVp values used in CT scanning, almost all interactions in soft tissues occur by Compton scattering. By lowering the kVp close to the k-edge of calcium, beam attenuation by calcium will be greater and will be reflected as an increase in density reading (DR). The presence of calcification in solitary pulmonary nodules (SPNs), and thus an implied benign etiology, is currently being diagnosed on CT by using reference phantoms. We explored the possibility of utilizing low kVp (i.e., 80 kVp) to detect the presence of such calcification in SPNs, thus obviating the need for expensive and cumbersome reference phantoms. MATERIALS AND METHODS: We first tested this phenomenon of photoelectric interaction by CT and its effect on DRs by scanning various dilutions of calcium bicarbonate solution at the standard 140 kVp and at a lower, 80 kVp, setting. After confirming the hypothesis, we conducted a prospective clinical study of 27 consecutive SPNs and scanned them at 140 and 80 kVp to detect the presence of calcification by measuring their DRs at both kVp values. RESULTS: All calcium solutions showed an increase in DR on the 80 kVp scan. Of the 27 nodules, 11 (41%) showed an increase in DR, suggesting the presence of calcification: 10 (91%) were benign, and 1 (9%) was malignant. CONCLUSION: Our study demonstrates that dual kVp CT could be reliably used to identify calcifications in SPNs, very similar to the use of the reference phantoms currently being applied for the purpose.

Calcinosis↗
PubMedDate not supplied

CT manifestations of respiratory syncytial virus infection in lung transplant recipients.

PURPOSE: The purpose of our study was to evaluate CT findings during respiratory syncytial virus (RSV) infection in lung transplant recipients and to identify sequelae. METHOD: Thirty-nine CT scans prior to, during, and following acute infection in 10 lung transplant recipients were reviewed. Abnormalities that were new from baseline observations and occurred within 4 weeks of diagnosis were defined as acute. Chronic findings were defined as those present >4 weeks after diagnosis. RESULTS: Findings in nine patients were ground-glass (seven), air-space (five), and tree-in-bud (four) opacities and acute bronchial dilatation (four) and wall thickening (four). Patients lacked pleural effusions or lymph node enlargement. Five of seven patients with follow-up exams had new air trapping (three), persistent bronchial dilatation (three), and thickening (two). Three and 2 of the 10 patients developed bronchiolitis obliterans syndrome and obliterative bronchiolitis, respectively. CONCLUSION: During acute infection, patients commonly had ground-glass opacities but lacked pleural effusions and lymph node enlargement. There can be chronic sequelae after infection.

Acute Disease↗
PubMedDate not supplied

Acquired tracheomalacia: detection by expiratory CT scan.

PURPOSE: The purpose of this work was to determine whether cross-sectional area and coronal and sagittal diameter measurements of the trachea between inspiration and end-expiration on CT are significantly different between patients with acquired tracheomalacia and those without this condition. METHOD: Inspiratory and end-expiratory CT scans of the trachea of 23 normal patients and 10 patients with acquired tracheomalacia were analyzed. Percent changes in cross-sectional area, coronal, and sagittal diameters were calculated. RESULTS: For patients with tracheomalacia, mean percent changes in the upper and middle trachea between inspiration and expiration were 49 and 44%; mean changes in the coronal and sagittal diameters in the upper and middle tracheal were 4 and 10% and 39 and 54%, respectively. Control group mean percent changes in the upper and middle tracheal area were 12 and 14%, respectively, and mean changes in the coronal and sagittal diameters in the upper and middle trachea were 4 and 4% and 11 and 13%, respectively. Significant differences were calculated for changes in cross-sectional area and sagittal diameter between groups (p < 10-5). Based on receiver operator curve analysis, a > 18% change in the upper trachea and 28% change in the midtrachea between inspiration and expiration were observed; the probability of tracheomalacia was 89-100%. The probability of tracheomalacia was > 89%, especially if the change in sagittal diameter was > 28%. CONCLUSION: By measuring changes in tracheal cross-sectional area and sagittal diameters between inspiratory and end-expiratory CT, a significant difference can be identified between normal patients and those with acquired tracheomalacia.

Adult↗
PubMedDate not supplied

The costal cartilages in health and disease.

The costal margin, although imaged in many routine radiologic examinations, has been ignored in the radiology literature. Calcification of the costal cartilages follows gender-related patterns and is generally not evident radiographically until after the age of 30 years. Diffuse enlargement of the costochondral junctions may alert the astute observer to the presence of systemic diseases such as acromegaly and rickets. Focal masses have a subtle appearance on plain radiographs and may be better imaged with computed tomography (CT) or magnetic resonance imaging. Chondrosarcoma of the costal margin typically appears as an expansile mass with coarse calcifications and an associated soft-tissue mass. Radiographic and CT features of costochondritis include chondral enlargement or destruction, low-attenuation cartilage at CT, associated soft-tissue swelling, and localized peripheral cartilage calcification. There appears to be an association between heavy premature costal cartilage calcification and certain systemic conditions, such as malignancy, autoimmune disorders, chronic renal failure, and thyroid disease, particularly Graves disease.

Adult↗
PubMedDate not supplied

Imaging of mediastinal lymph nodes: CT, MR, and FDG PET.

The evaluation of mediastinal lymph nodes is an important aspect of staging in patients with non-small cell lung cancer. Anatomic imaging of lymph nodes with computed tomography (CT) and magnetic resonance (MR) imaging has been limited by the relatively low sensitivity and specificity of these techniques. Advances in physiologic imaging of mediastinal lymph nodes with 2-[fluorine-18] fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) have resulted in improved diagnostic accuracy in the determination of nodal status. Despite the limitations of CT, this technique still plays an important role by aiding in the selection of the most appropriate procedure for staging, by guiding biopsy, and by providing anatomic information for visual correlation with FDG PET images. At present, anatomic MR imaging of lymph nodes is primarily a problem-solving tool for cases with inconclusive CT results. Physiologic MR imaging with iron oxide is an exciting area of investigation, and the accuracy of this technique is being assessed in clinical trials. Anatomic and physiologic imaging techniques should be considered complementary rather than competitive imaging strategies.

Carcinoma, Non-Small-Cell Lung↗
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Tuberculosis from head to toe.

Tuberculosis can affect virtually any organ system in the body and can be devastating if left untreated. The increasing prevalence of tuberculosis in both immunocompetent and immunocompromised individuals in recent years makes this disease a topic of universal concern. Because tuberculosis demonstrates a variety of clinical and radiologic findings and has a known propensity for dissemination from its primary site, it can mimic numerous other disease entities. Primary pulmonary tuberculosis typically manifests radiologically as parenchymal disease, lymphadenopathy, pleural effusion, miliary disease, or lobar or segmental atelectasis. In postprimary tuberculosis, the earliest radiologic finding is the development of patchy, ill-defined segmental consolidation. Both computed tomography (CT) and magnetic resonance (MR) imaging are helpful in diagnosing tuberculous spondylitis and tuberculous arthritis. CT is especially useful in depicting gastrointestinal and genitourinary tuberculosis. In tuberculosis involving the central nervous system, CT and MR imaging findings vary depending on the stage of disease and the character of the lesion. A high degree of clinical suspicion and familiarity with the various radiologic manifestations of tuberculosis allow early diagnosis and timely initiation of appropriate therapy, thereby reducing patient morbidity.

Arthritis, Infectious↗
PubMedDate not supplied

Pulmonary lymphangioleiomyomatosis: CT and pathologic findings.

We present two cases that illustrate the appearance of pulmonary lymphangioleiomyomatosis on high resolution CT. Both patients had numerous thin-walled cystic airspaces of varying sizes distributed diffusely throughout the lungs. Most of the lung parenchyma surrounding the cystic spaces was normal. This pattern correlated closely with the surgical and pathologic findings and is distinct from other diffuse lung diseases.

Adult↗