Biomedical subjects
Publications and source records attributed to D P Naidich.
The authors describe the radiographic appearance of the left atrial catheter, a widely used postsurgical intracardiac device. Recognition of the characteristic appearance of this catheter should be of value in detection of potential complications, including line fracture with resultant retention and/or embolization, infection, prosthetic valve dysfunction, and even cardiac tamponade.
Thoracic disease in the HIV negative immunocompromised host is most frequently caused by infection. Patterns of involvement produced on the chest radiograph include (1) lobar or segmental consolidation, (2) nodules with rapid growth and/or cavitation, and (3) diffuse lung disease. The lung also may be directly involved by lymphoma, metastases, drug reactions, radiation pneumonitis, or nonspecific interstitial pneumonitis. The lung is a frequent target organ for opportunistic infections in AIDS patients, particularly of Pneumocystis carinii pneumonia and tuberculosis. Computed tomography may be particularly helpful in these patients in the detection of early disease and in the characterization of patterns and extent of involvement as well as complications.
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The progression of lung disease in patients with cystic fibrosis (CF) was evaluated with chest radiography. The severity and extent of the various radiographic changes were scored with the Chrispin or the Birmingham method, which involves the use of imprecise and subjective terms, such as line shadows, large pulmonary shadows, and nodular cystic lesions. Although computed tomography (CT) has been shown to be helpful in the evaluation of lung disease in CF, no scoring system or other objective criteria have been developed for the evaluation of the wide range of pulmonary changes in these patients. A CT scoring system was devised that incorporates all of the changes seen in the lungs of patients with CF. Such a scoring system may facilitate objective evaluation of existing and newly developed therapeutic regimens and may be a valuable tool in the preoperative evaluation of patients being considered for lobectomy or bullectomy and in the selection of patients for lung transplantation.
To date, few reports have attempted to correlate plain radiographic findings with computed tomography (CT) in assessing pulmonary disease in patients who have acquired immunodeficiency syndrome (AIDS). This report focuses on the most common pulmonary manifestations, with particular emphasis placed on those entities for which there is a potential role for CT. This includes identification of occult disease, especially the early diagnosis of Pneumocystis carinii pneumonia, as well as identification of unsuspected lung abscesses and cavities; characterization of diffuse parenchymal disease in patients who have abnormal radiographs; identification and characterization of mediastinal lymphadenopathy, especially in differentiating between neoplastic and non-neoplastic causes; and finally, use of CT to perform CT-guided transthoracic needle biopsies.
In our experience, MR has served largely as a problem-solving device, especially in those cases in which CT has proved equivocal. Magnetic resonance has been especially efficacious in evaluating cardiovascular pathology. Virtually the entire spectrum of aortic disease can be assessed accurately, making MR a reasonable alternative to CT or angiography in most cases. Indications for the use of MR in patients with thoracic neoplasia have also emerged. Magnetic resonance is more accurate than CT in assessing invasion of the chest wall and mediastinum. As a consequence, MR should be considered the imaging procedure of choice in patients with suspected Pancoast tumors. In some patients with lymphoma, MR can make a unique contribution by evaluating the response to therapy. Magnetic resonance also can be of value in assessing patients with signs of venous obstruction, especially when there is a contraindication to the use of intravenous contrast medium. Magnetic resonance is as accurate as CT in assessing most benign mediastinal pathology. The former study can easily differentiate atherosclerotic vessels or aneurysms from enlarged lymph nodes or masses, frequently obviating a more invasive study. It is especially efficacious in evaluating patients with cystic lesions, especially those with complex cysts not clearly of water density. In the hilum, MR can differentiate prominent hilar vessels from adenopathy or masses as reliably as CT. Again, in patients with renal failure or those who have documented allergies to iodinated contrast medium, MR should be the imaging procedure of choice to evaluate suspicious hila identified on plain chest radiographs. Magnetic resonance also can be used to differentiate central obstructing hilar tumors from peripheral collapsed lung. In certain cases, these findings may help determine resectability by demonstrating encasement of hilar and mediastinal vessels as well as the central airways. It should be anticipated that as technologic improvements continue to be made, MR will assume an increasingly important role in the imaging of thoracic disease.
Optimal clinical management of patients with focal lung pathology necessitates thorough familiarity with basic concepts in imaging. Over the past decade, radiologic evaluation has undergone rapid change, reflecting considerable growth in imaging technology. As this article discusses and illustrates at length, improvements in computed tomography technology in particular have resulted in a significant alteration in our approach to both the diagnosis and treatment of patients with focal lung disease.
Recent reports have emphasized the potential for dual-energy computed radiographic applications. An improved method for single-exposure material-selective imaging with a photostimulable phosphor computed radiography system was investigated. The essential elements of the technique are (a) prefiltration with gadolinium, which divides the incident broad-beam x-ray spectrum into low-energy and high-energy peaks; (b) a cassette consisting of four photostimulable phosphor plates that record images of increasing mean energies, with a computed energy separation of 23 keV from the front to the rear plate; (c) spatially dependent scatter and beam-hardening corrections; and (d) a noise-reduction algorithm based on noise correlations between bone-selective and soft-tissue-selective dual-energy images. These elements result in improved material cancellation and signal-to-noise ratio throughout the image.
The potential of low-dose computed tomography (CT) of the lungs was critically evaluated in two patients with normal-appearing lungs and 10 patients with a wide diversity of underlying parenchymal abnormalities. At each of five levels, in addition to routine scans obtained at 120 kVp and 140 mA, a scan at 10 mA and a half scan at 10 mA were obtained, with all other parameters held constant. Each scan was evaluated visually to assess anatomic clarity as well as the presence of artifacts and the extent of graininess. At all levels of the thorax, visualization of parenchymal structures was not affected by decreasing the milliamperage. It appears that high-quality, diagnostic images of the lung can be obtained with a very low radiation dose. Although further evaluation is necessary, the potential of low-dose CT for use in the pediatric population in particular, as well as for screening in patients at high risk for developing lung cancer, is apparent.
Computed tomographic (CT) and chest radiographic findings were retrospectively correlated with those found at fiberoptic bronchoscopy (FOB) in 58 patients presenting with hemoptysis. Abnormalities involving the airways were depicted by CT in a total of 28 cases (48%). In 18 of these (31% of the total group of 58), focal abnormalities involving the central airways were identified (17 were subsequently proved to be malignant) and in 10 (17% of the total), CT showed bronchiectasis. Focal airway abnormality was shown by FOB in 18 cases (31%); all of these were depicted with CT. Malignancy was diagnosed in 24 patients, including three in whom results of FOB were normal but malignant cells were identified at transbronchial biopsy. CT abnormalities were identified in all cases of malignancy. In 10 of 21 cases (48%) of non-small cell lung cancer, CT allowed definitive staging by documenting either direct mediastinal invasion and/or metastatic disease, while FOB allowed definitive staging in only three cases. CT studies provided no false-negative results. It is concluded that when carefully performed, CT may be an effective modality for evaluating patients presenting with hemoptysis.
Lung hernia is an abnormal protrusion of the lung beyond the confines of the thoracic cage. Hernias are classified as cervical, intercostal, or diaphragmatic. Each of these types can be either congenital or acquired. Acquired hernias can be spontaneous, posttraumatic, or pathologic as a result of a neoplastic or inflammatory process. This report describes five cases of lung hernias. Two were congenital cervical hernias, detected as incidental findings on chest radiographs of infants. One was a posttraumatic intercostal hernia detected on a chest radiograph and confirmed with CT. The remaining two were acquired intercostal hernias at the site of prior chest-tube drainage of tuberculous empyemas. Although both of these were clearly shown on CT scans, only one was visible on chest radiographs.
In patients with tumors of tracheobronchial origin, computed tomography (CT) provides detailed information critical to accurate tumor staging. By precisely delineating the intra- and extraluminal extent of disease, CT has proved complementary to fiberoptic bronchoscopy, both for initial screening and as an aid in determining appropriate candidates for either transbronchial needle aspiration and biopsy or endoscopic laser therapy. CT has proved especially valuable as a guide to patients with radiographic evidence of lobar or segmental collapse. The advantages and limitations of CT as well as magnetic resonance (MR) in the evaluation of tracheobronchial neoplasia are discussed and illustrated.
We studied 8 adult patients with variable symptoms of cough, dyspnea, stridor, wheezing, or hemoptysis. Fiberoptic bronchoscopy in all showed complete or nearly complete endobronchial obstruction of a main-stem bronchus by neoplasm with a mean bronchial diameter of 1.9 mm +/- 1.6 mm (mean +/- standard deviation). In 4 patients, a lobar bronchus was also completely obstructed. No mass was visible on chest radiographs of any patient; however, computed tomography in each showed main-stem endobronchial obstruction, lobar obstruction (4 instances in 3 patients), and in 6 patients hypoperfusion of the involved lung. Computed tomographic scan showed additional abnormalities that were unsuspected on viewing chest radiographs or at bronchoscopy, including mediastinal adenopathy in 3 patients and an extraluminal tumor component in 4. After therapy with Nd-YAG laser, main-stem airway diameter increased to a mean of 9.6 mm +/- 1.0 mm (P less than .05) and pulmonary functions improved. Results suggest the complementary role of computed tomography and fiberoptic bronchoscopy in the detection and laser-treatment planning of chest radiographically occult severe neoplastic obstruction of the main-stem bronchus.
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The authors retrospectively evaluated radiographs, computed tomographic (CT) scans, and results of pulmonary function tests (when available) for 17 patients with biopsy-proved pulmonary histiocytosis X. In 11 patients, high-resolution CT was used. In 12 patients, CT demonstrated cystic air spaces, usually less than 10 mm in diameter. In three of these 12, cysts were the only abnormality, but in six others, nodules (usually less than 5 mm in diameter) were also present. Two patients had only nodules and one, only emphysema. CT showed that many lesions that appeared reticular on plain radiographs were actually cysts. CT showed no central or peripheral concentration of lesions, but it did reveal that many small nodules were distributed in the centers of secondary lobules around small airways. CT findings correlated better with the diffusing capacity (rho = -0.71) than did the plain radiographic findings (rho = -0.57). Thus, CT was better than radiography at showing the morphology and distribution of lung abnormalities.
The role of CT in the diagnosis of intrathoracic Kaposi's sarcoma (KS) was evaluated retrospectively in 24 patients, in the absence of coexistent opportunistic infections. In all cases the diagnosis of KS was initially established by histologic evaluation of extrathoracic disease: 15 patients had verified parenchymal KS and nine patients endobronchial KS. (Chest roentgenograms were analyzed separately for each group: in 14 patients serial films were available for review. The predominant radiographic findings was the presence of nonspecific, bilateral, perihilar infiltrates in 22 of 24 cases (92 percent). Corresponding CT scans documented the presence of abnormal hilar densities characteristically extending into the adjacent pulmonary parenchyma along distinctly perivascular and peribronchial pathways. Discrete, poorly marginated nodules were identified radiographically in ten cases (42 percent); these proved to be randomly distributed throughout the parenchyma on CT. Radiographic evidence of mediastinal adenopathy was distinctly unusual, seen in only two cases (8 percent). While CT typically demonstrated shotty adenopathy, significantly enlarged nodes (greater than 1 cm) were rarely identified. We concluded that CT is more specific than routine roentgenograms for identifying pulmonary KS. While not pathognomonic, peribronchial and perivascular disease is sufficiently characteristic to obviate more invasive diagnostic procedures, especially in patients with established KS.
Radiographic and CT findings in 15 patients with clinically documented septic pulmonary emboli were compared retrospectively. In most cases, radiographic changes were nonspecific. In comparison, on CT a combination of specific signs could be identified in all patients. These included peripheral nodules with clearly identifiable feeding vessels associated with metastatic lung abscesses (10 [67%] of 15 cases), and subpleural, wedge-shaped densities with and without necrosis caused by septic infarcts (11 [73%] of 15 cases). Ancillary pleural, mediastinal, axillary, and pericardial abnormalities also were more easily identified with CT. We conclude that CT is complementary to other imaging techniques in the recognition of septic pulmonary emboli.
Magnetic resonance imaging utilizing spin echo sequences was used to demonstrate cor triatriatum in an 18-year-old boy. Phase map images aided the diagnosis by demonstrating the presence of slowly flowing blood in the accessory atrial chamber. Magnetic resonance is an excellent modality for the noninvasive diagnosis of cor triatriatum.