Biomedical subjects
Publications and source records attributed to J S Kwong.
The authors report a case of metastatic breast carcinoma that on investigation was shown to have a negative bone scan in spite of multiple densely sclerotic metastases on radiography and CT and a positive bone biopsy. The literature is reviewed with regard to the subject of negative bone scans in this situation.
PURPOSE: To compare prospectively the accuracy of spiral computed tomography (CT) with that of ventilation-perfusion scintigraphy for diagnosing pulmonary embolism. MATERIALS AND METHODS: Within 48 hours of presentation, 142 patients suspected of having pulmonary embolism underwent spiral CT, scintigraphy, and (when indicated) pulmonary angiography. Pulmonary angiography was attempted if interpretations of spiral CT scans and of scintigrams were discordant or indeterminate and intermediate-probability, respectively. RESULTS: In the 139 patients who completed the study, interpretations of spiral CT scans and of scintigrams were concordant in 103 patients (29 with embolism, 74 without). In 20 patients, intermediate-probability scintigrams were interpreted (six with embolism at angiography, 14 without); diagnosis with spiral CT was correct in 16. Interpretations of spiral CT scans and those of scintigrams were discordant in 12 cases; diagnosis with spiral CT was correct in 11 cases and that with scintigraphy was correct in one. Spiral CT and scintigraphic scans of four patients with embolism did not show embolism. Sensitivities, specificities, and kappa values with spiral CT and scintigraphy were 87%, 95%, and 0.85 and 65%, 94%, and 0.61, respectively. CONCLUSION: In cases of pulmonary embolism, sensitivity of spiral CT is greater than that of scintigraphy. Interobserver agreement is better with spiral CT.
OBJECTIVE: To compare the identifiable pulmonary abnormalities on preoperative chest radiographs and CT scans with the histologic findings in patients requiring surgical intervention for recurrent or persistent pneumothoraces. MATERIALS AND METHODS: Chest radiographs were reviewed retrospectively in 116 consecutive patients (aged 16 to 81 years) who had undergone thoracotomy for recurrent or persistent pneumothorax. CT scans were performed in 21 patients. Chest radiographs and CT scans were reviewed by two observers without knowledge of the histologic findings. All specimens were reviewed by a surgical pathologist. RESULTS: Seventy-nine (68%) patients had parenchymal abnormalities and five (4%) had pleural thickening evident on the radiograph. The most common radiographic abnormalities included apical bullae (n = 51), apical scarring (n = 17), and diffuse emphysema (n = 9). Twenty of 21 (95%) CT scans demonstrated either a parenchymal or a pleural abnormality. CT demonstrated emphysema in four patients with normal radiographs, as well as additional findings in six patients with abnormal radiographs. Histologically, 74 patients had focal irregular emphysema, 26 had distal acinar emphysema, six had mixed emphysema, four had isolated bullae or blebs, two had mesothelioma, and one each had the following: metastatic angiosarcoma, subpleural fibrosis, congenital cystic adenomatoid malformation, and tuberculous pleuritis with inactive interstitial fibrosis and honeycombing. CONCLUSION: Most patients with surgically treated pneumothorax have emphysema or an isolated bulla. Although these findings may not be apparent on the radiograph and seen on CT, this probably does not affect patient management. In most cases of pneumothorax related to other causes, findings consistent with the diagnosis can be seen on the radiograph.
OBJECTIVE: The objective of this study was to prospectively evaluate the feasibility and efficacy of single-photon emission computed tomography (SPECT) with 18F-fluorodeoxyglucose (FDG) for differentiating malignant from benign pulmonary nodules. SUBJECTS AND METHODS: Twenty-six patients with 28 radiologically indeterminate focal pulmonary lesions were examined. Fasting patients were injected with 5 MBq/kg of FDG (maximum dose, 370 MBq). Imaging was performed with dual-head SPECT cameras equipped with 511-keV collimators. RESULTS: Seventeen of 21 pathologically malignant nodules showed FDG uptake on SPECT imaging (sensitivity, 81%). None of the seven benign modules showed uptake (specificity, 100%). SPECT imaging with FDG was positive in all 16 malignant nodules that were larger than or equal to 2 cm in diameter. However, only one (20%) of five nodules smaller than 2 cm in diameter showed positive on SPECT imaging. CONCLUSION: Using current technology, we found FDG SPECT imaging useful for distinguishing benign from malignant pulmonary nodules that were larger than or equal to 2 cm in diameter. However, because of the relatively low sensitivity of SPECT, smaller malignant nodules were not adequately revealed.
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STUDY OBJECTIVE: To assess the efficacy of the chest radiograph in identifying patients with miliary tuberculosis. DESIGN: Retrospective case-controlled review by three independent blinded chest radiologists. SETTING: Provincial tuberculosis control center. PATIENTS: Population-based sample, including all proved cases of miliary tuberculosis diagnosed in the Province of British Columbia, Canada, between November 1982 and November 1992. One hundred cases of miliary tuberculosis were identified, of which 71 had chest radiographs available for review. Forty-four normal chest radiographs and 20 chest radiographs of patients with localized pulmonary tuberculosis were also included as controls. MAIN OUTCOME MEASURES: The primary outcome of measurements was the sensitivity and interobserver variability of the chest radiograph in the diagnosis of miliary tuberculosis. The observers were also asked to describe the pattern and extent of pulmonary abnormalities based on the International Labor Organization (ILO) classification of pneumoconioses. RESULTS: The three independent observers identified 42, 44, and 49 of the 71 cases of miliary tuberculosis, respectively (sensitivity, 59 to 69%). The three observers incorrectly diagnosed miliary tuberculosis in 2, 0, and 2 of the 64 controls, respectively (specificity, 97 to 100%). There was good interobserver agreement (90%, kappa = 0.77). The nodules measured less than 3 mm in diameter in 90% of cases in which miliary tuberculosis was correctly identified. In 10% of cases, the nodules measured greater than 3 mm in diameter. The ILO profusion scores ranged from mild (profusion score 1) in 45% of cases, through moderate (profusion score 2) in 27%, and severe (profusion score 3) in 28%. CONCLUSIONS: The chest radiograph allowed identification of 59 to 69% of cases of miliary tuberculosis with a high specificity and good interobserver agreement.
PURPOSE: To determine the signs of diaphragmatic rupture at computed tomography (CT) and the frequency of preoperative diagnosis with CT. MATERIALS AND METHODS: CT scans in 11 consecutive patients with surgically proved tears of the diaphragm due to blunt trauma were reviewed by two chest radiologists. The observers assessed the presence of discontinuity of the diaphragm, herniation of abdominal viscera or omentum, and waistlike constriction of the herniated stomach or bowel (collar sign). Hospital records were reviewed to confirm surgical findings and ascertain whether the diagnosis has been suggested at CT. RESULTS: In eight of 11 patients, rupture of the diaphragm was on the left, and in three it was on the right. In nine patients, diagnostic findings were identified retrospectively on CT scans; these included discontinuity of the diaphragm (n = 9), herniation of the abdominal organs or bowel (n = 7), and constriction of the stomach (n = 3). CONCLUSION: CT enables detection of most diaphragmatic tears due to blunt trauma.
OBJECTIVE: The purpose of this study was to compare the sensitivities and diagnostic accuracies of chest radiography and CT in the assessment of diseases of the trachea and main bronchi in regard to detection, evaluation of focal vs diffuse disease, separation of benign from malignant disease, and accuracy of diagnosis. MATERIALS AND METHODS: The chest radiographs and CT scans of 35 patients with proved diseases of the trachea and main bronchi and five control subjects were randomly assessed by two independent observers in a blind study. The diagnoses included 25 malignant and 10 benign conditions. The malignant lesions included 24 primary tumors and one metastatic melanoma. The benign lesions included two benign tumors, two tracheal stenoses, one focal amyloidosis, one tracheomalacia, and four miscellaneous diffuse abnormalities. The observers were asked to determine if an abnormality was present, to classify it as focal or diffuse and as benign or malignant, and to list the three most likely diagnoses. Sensitivities were compared by using the McNemar test. RESULTS: The sensitivity of both observers in detecting disease on the chest radiograph was 66%. The sensitivity on the CT scan was 97% for the first observer and 91% for the second observer (p < .01). Both observers were able to correctly classify the detected abnormalities as either focal or diffuse in 91% of cases on the chest radiographs and 97% of cases on the CT scans. The abnormalities were correctly classified as either benign or malignant in 78% of cases by both observers on the chest radiographs and in 85% and 78% of cases on the CT scans by the first observer and the second observer, respectively. The correct diagnosis was included in the list of the three most likely diagnoses in 61% of cases by both observers after reviewing the radiographs and in 56% of cases by one observer and 63% of cases by the other observer after reviewing the CT scans. CONCLUSION: CT is superior to chest radiography in allowing detection of abnormalities of the major airways. Both CT and chest radiography are accurate for differentiating focal from diffuse disease, but neither technique is accurate for distinguishing benign from malignant disease or for establishing a specific diagnosis.
This article presents the computed tomographic (CT) features of the most common abnormalities of the trachea and main-stem bronchi and correlates CT and pathologic findings. The abnormalities are classified into focal and diffuse. Focal disease tends to produce a decreased airway diameter, whereas diffuse diseases are divided into those that increase the airway diameter and those that decrease it. Conventional CT with 10-mm collimation was performed in 36 patients to assess their condition. Additional dynamic incremental thin-section (1.5-5.0-mm collimation) CT was performed in patients with focal abnormalities. Findings from conventional CT correlated closely with those from pathologic analysis of specimens from patients with diffuse disease, but dynamic thin-section scans are necessary for optimal assessment of focal abnormalities. CT demonstrates the location and extent of disease; helps characterize abnormal tissues; helps evaluate the thickness of the tracheal and bronchial walls; and helps determine the extent of extraluminal disease, including the presence of mediastinal extension and lymphadenopathy.
The chest radiographs and computed tomographic (CT) scans obtained in eight patients with pathologically proved cases of thoracic actinomycosis were independently reviewed by two observers. All patients were alcoholic men aged 42-62 years. Air-space consolidation, seen on the radiograph and CT scan in each case, was present in the lower lobes in seven patients (88%) and upper lobes in three (38%). Pleural effusion was present in five (62%). Pleural thickening adjacent to the air-space consolidation was identified on the radiograph in four (50%) and CT scan in all eight. Cavitation or central areas of low attenuation not apparent on the radiograph were seen on the CT scan in five cases (62%). Hilar or mediastinal lymphadenopathy was identified on the radiograph in three cases (38%) and on the CT scan in six (75%). Chest-wall invasion occurred in only one case (12%). Thoracic actinomycosis is characterized on CT scans by air-space consolidation with adjacent pleural thickening. CT is superior to radiography in assessing the thoracic manifestations of actinomycosis.
Real-time sonography was evaluated retrospectively in 71 consecutive patients with ocular trauma. A total of 51 vitreous hemorrhages, 20 hemorrhages in the anterior chamber, 22 retinal detachments, seven choroidal detachments, five foreign bodies, and 12 dislocated lenses were identified sonographically. In 10 instances (three choroidal detachments, six retinal detachments, and one lens dislocation), these sonographic findings were not apparent on clinical examination. One hemorrhage of the anterior chamber was missed on sonography. Both sonography and clinical examination failed to visualize one retinal detachment. The results of this study show that real-time sonography is valuable in the assessment of ocular trauma and supplements clinical examination with valuable information.
We present a patient with disseminated MAI osteomyelitis with no evidence of underlying disease or immune failure. Disseminated MAI is rare in the immunocompetent host and closely simulates malignant disease. Delayed cultures are required for precise diagnosis and optimal treatment.
OBJECTIVE: Our goal was to determine the prevalence of mediastinal lymph node enlargement at CT in patients with diffuse infiltrative lung disease. MATERIALS AND METHODS: The study was retrospective and included 175 consecutive patients with diffuse infiltrative lung diseases. Diagnoses included idiopathic pulmonary fibrosis (IPF) (n = 61), usual interstitial pneumonia associated with collagen vascular disease (CVD) (n = 20), idiopathic bronchiolitis obliterans organizing pneumonia (BOOP) (n = 22), extrinsic allergic alveolitis (EAA) (n = 17), and sarcoidosis (n = 55). Fifty-eight age-matched patients with CT of the chest performed for unrelated conditions served as controls. The presence, number, and sites of enlarged nodes (short axis > or = 10 mm in diameter) were recorded. RESULTS: Enlarged mediastinal nodes were present in 118 of 175 patients (67%) with infiltrative lung disease and 3 of 58 controls (5%) (p <0.001). The prevalence of enlarged nodes was 84% (46 of 55) in sarcoidosis, 67% (41 of 61) in IPF, 70% (14 of 20) in CVD, 53% (9 of 17) in EAA, and 36% (8 of 22) in BOOP. The mean number of enlarged nodes was higher in sarcoidosis (mean 3.2) than in the other infiltrative diseases (mean 1.2) (p <0.001). Enlarged nodes were most commonly present in station 10R, followed by 7, 4R, and 5. CONCLUSION: Patients with infiltrative lung disease frequently have enlarged mediastinal lymph nodes. However, in diseases other than sarcoid, usually only one or two nodes are enlarged and their maximal short axis diameter is <15 mm.