Pertussis toxin blocks the effects of alpha 2-agonists and antagonists on locus coeruleus activity in vivo.

This study assessed the effects of pertussis toxin, which is known to inactivate G proteins and therefore to block receptors linked to G proteins, on electrophysiological activity of the locus coeruleus in vivo. Pertussis toxin was injected into the lateral cerebral ventricle of rats, and locus coeruleus activity was then recorded. Compared to vehicle-injected control animals, pretreatment with pertussis toxin markedly increased the spontaneous firing rate of locus coeruleus neurons. In addition, the alpha 2-antagonist idazoxan was no longer able to augment either spontaneous or evoked locus coeruleus activity after pretreatment with pertussis toxin. Finally, pretreatment with pertussis toxin made locus coeruleus neurons resistant to inhibition by the alpha 2-agonist clonidine. These results are consistent with the view that pertussis toxin blocks alpha 2-receptors, receptors linked to G proteins, in vivo.

Pulmonary embolism: comparison of gadolinium-enhanced MR angiography with contrast-enhanced spiral CT in a porcine model.

RATIONALE AND OBJECTIVES: The purpose of this study was to compare gadolinium-enhanced magnetic resonance (MR) angiography with contrast material-enhanced computed tomography (CT) for the detection of small (4-5-mm) pulmonary emboli (PE), with a methacrylate cast of the porcine pulmonary vasculature used as the diagnostic standard. MATERIALS AND METHODS: In 15 anesthetized juvenile pigs, colored methacrylate beads (5.2 and 3.8 mm diameter-the size of segmental and subsegmental emboli in humans) were injected via the left external jugular vein. After embolization, MR angiographic and CT images were obtained. The pigs were killed, and the pulmonary arterial tree was cast in clear methacrylate, allowing direct visualization of emboli. Three readers reviewed CT and MR angiographic images independently and in random order. RESULTS: Forty-nine separate embolic sites were included in the statistical analysis. The mean sensitivity (and 95% confidence intervals) for CT and MR angiography, respectively, were 76% (68%-82%) and 82% (75%-88%) (P > .05); the mean positive predictive values, 92% (85%-96%) and 94% (88%-97%) (P > .05). In this porcine model, PE were usually seen as parenchymal perfusion defects (98%) with MR angiography and as occlusive emboli (100%) with CT. CONCLUSION: MR angiography is as sensitive as CT for the detection of small PE in a porcine model.

Pulmonary nodules in early fat embolism syndrome: a case report.

The radiologic abnormalities in a patient with mild clinical manifestations of fat embolism are reported. The findings consisted of small nodular opacities, which were shown on computed tomography (CT) scans to be located predominantly in the centrilobular and subpleural regions. The nodules presumably represented alveolar edema or hemorrhage secondary to the fat embolism syndrome.

Inflammatory pseudotumour of the post-bulbar duodenum.

The cases of five patients with upper gastrointestinal barium examination findings suggestive of a post-bulbar duodenal tumour are presented. Further investigations failed to confirm evidence of a neoplasm, but instead identified post-bulbar duodenal ulceration or scarring. Possible causes for these findings, technical considerations for avoiding this pitfall, and the importance of appropriate further investigations are discussed.

Pulmonary leukemic infiltrates: high-resolution CT findings in 10 patients.

OBJECTIVE: We assessed the high-resolution CT findings of pulmonary leukemic infiltrates. CONCLUSION: High-resolution CT findings of pulmonary leukemic infiltrates reflect the predilection of leukemic cells to involve the perilymphatic pulmonary interstitium.

Congenital unilateral pulmonary vein atresia: radiologic findings in three adult patients.

OBJECTIVE: The purpose of our study is to describe the radiologic findings of adult patients presenting with congenital unilateral pulmonary vein atresia. CONCLUSION: Chest radiography in affected patients typically reveals a small hemithorax and ipsilateral pulmonary artery as well as ipsilateral septal thickening. CT shows, in addition, ground-glass attenuation, the absence of a pulmonary vein connection to the left atrium, and abundant mediastinal venous collateral vessels. MR imaging is helpful in further characterizing the vascular abnormalities. Angiography may help to confirm the diagnosis.

MR features of soft-tissue abnormalities due to acute marrow infarction in five children with sickle cell disease.

OBJECTIVE: The purpose of this investigation was to illustrate a variety of soft-tissue abnormalities on MR imaging encountered in connection with acute marrow infarction in children with sickle cell disease. CONCLUSION: Extraosseous abnormalities on MR imaging preclude differentiation of acute marrow infarction from osteomyelitis in children with sickle cell disease.

Stage distribution in patients with a small (< or = 3 cm) primary nonsmall cell lung carcinoma. Implication for lung carcinoma screening.

BACKGROUND: Recently, there has been increased interest in the use of computed tomography (CT) for lung carcinoma screening. For this technique to be effective, small tumors must be detected at an earlier stage than large lesions. However, to the authors's knowledge, the relationship between the size of small primary (< or = 3 cm) neoplasms and disease stage at presentation has never been established clearly. The current study was performed to determine whether smaller lesions indeed have an earlier stage distribution compared with larger tumors. METHODS: The Duke University Medical Center Tumor Registry identified 620 patients (261 women and 359 men, with a mean age of 67 years) who presented with pathologically proven primary nonsmall cell lung carcinomas measuring < or = 3 cm between 1980-1999. Surgical, pathologic, and imaging information was reviewed retrospectively to confirm the size of the lesion and the disease stage at the time of presentation. The distribution of tumor size within each stage and the distribution of disease stage according to tumor size were determined. RESULTS: Tumors occurring in patients with TNM Stage IIIB disease were slightly larger than those found in patients with either more advanced or less advanced disease. However, there was no apparent statistically significant relation between the stage distribution and the size of the primary lesion. CONCLUSIONS: The current study data did not find a statistically significant relation between the size of small primary lung tumors and the distribution of disease stage at the time of presentation. This finding suggests that the detection of small tumors using screening CT may not result in a shift to an earlier disease stage distribution. A reduction in mortality needs to be demonstrated by appropriate clinical trials prior to the initiation of mass CT screening programs.

Helical CT cholangiography with three-dimensional volume rendering using an oral biliary contrast agent: feasibility of a novel technique.

OBJECTIVE: We evaluated the feasibility and image quality of a new noninvasive biliary imaging technique: helical CT cholangiography with three-dimensional volume rendering using an oral biliary contrast agent. SUBJECTS AND METHODS: Nineteen subjects including five healthy volunteers and 14 patients underwent helical CT cholangiography. Subjects ingested 6.0 g of iopanoic acid 6-10 hr before undergoing imaging. Axial data were used to construct three-dimensional volume-rendered cholangiograms. Two radiologists, an endoscopist, and a laparoscopic surgeon reviewed the images and evaluated overall image quality. In the 14 patients, findings from CT cholangiography were compared with those from ERCP, surgery, and intraoperative cholangiography. RESULTS: All segments of the biliary tree were opacified in all volunteers except one, in whom the intrahepatic ducts were not opacified. Image quality was good to excellent in all volunteers. Anomalous cystic duct insertions were seen in two volunteers. Opacification of the biliary tree was rated as acceptable to excellent in nine patients and suboptimal in five. In five patients with good or excellent opacification, the biliary anatomy correlated with findings on intraoperative cholangiography or ERCP. CT cholangiography revealed additional conditions (gallbladder varices and acute pancreatitis) and variant anatomy in three patients. CONCLUSION: Results of this pilot project suggest that obtaining CT cholangiograms using an oral biliary contrast agent is a feasible, noninvasive method for revealing biliary anatomy. However, visualization of the biliary tree was suboptimal in 36% of the patients, which represents a limitation of this technique.

Bronchocentric granulomatosis: computed tomographic findings in five patients.

AIM: The aim of this study was to assess the CT manifestations of bronchocentric granulomatosis. SUBJECTS AND METHODS: The CT results of five patients with bronchocentric granulomatosis were retrospectively analysed. The patients ranged from 20 to 72 years of age and included three men and two women. The diagnosis of bronchocentric granulomatosis was made at lobectomy (n = 2), open lung biopsy (n = 2), and transbronchial biopsy (n = 1). Only one of the five patients had asthma. RESULTS: The main findings consisted of a spiculated mass lesion (n = 3) or lobar consolidation with associated mild volume loss (n = 2). One of the two patients with consolidation had extensive mucoid impaction. The abnormalities involved predominantly an upper lobe in four patients and a lower lobe in one patient. In the four resected specimens, the macroscopic pathological appearance was consolidation (n = 2) and mass lesion (n = 2). Microscopically, the typical histology of airway-centred necrotizing granulomata was present in all cases. Aspergillus hyphae were identified in two cases. Nocardia sp. was cultured from the biopsy specimen in one case. CONCLUSION: The CT manifestations of bronchocentric granulomatosis consist of a focal mass or lobar consolidation with atelectasis. These reflect the presence of granuloma formation with or without associated bronchial obstruction.

Talcosis associated with IV abuse of oral medications: CT findings.

OBJECTIVE: Our objective was to evaluate the CT appearance of talcosis associated with IV abuse of oral medications and to compare the findings of talcosis related to methylphenidate with those findings seen with other drugs. MATERIALS AND METHODS: The CT scans of 12 patients with talcosis (seven men, five women), 33-54 years old (mean age, 44 years), were analyzed retrospectively. Seven patients had abused methylphenidate; five patients had no history of abuse. The diagnosis of talcosis was made histologically in 11 patients and at funduscopy in one patient. CT was performed with 1- to 1.5-mm collimation (n = 10 patients) or 5- to 10-mm collimation (n = 2). RESULTS: The predominant abnormalities seen on CT consisted of a diffuse fine nodular pattern (n = 2), a combination of nodules and lower lobe panacinar emphysema (n = 3), and ground-glass attenuation (n = 2). Emphysema was the only abnormality seen in the remaining five patients (lower lobe panacinar, n = 4; upper lobe centrilobular, n = 1). No significant difference in the prevalence of nodules and ground-glass attenuation was seen between the methylphenidate and non-methylphenidate groups. Lower lobe panacinar emphysema was more common in methylphenidate abusers (six [86%] of seven patients) than in non-mnethylphenidate drug abusers (one [20%] of five, p<0.05, Fisher's exact test). CONCLUSION: The CT manifestations of talcosis consist of a fine micronodular pattern, ground-glass attenuation, and emphysema. A significantly increased prevalence of lower lobe panacinar emphysema is seen in IV drug addicts who abuse methylphenidate.

Accuracy of CT in the diagnosis of allergic bronchopulmonary aspergillosis in asthmatic patients.

OBJECTIVE: The purpose of this study was to assess the accuracy of high-resolution CT in the diagnosis of allergic bronchopulmonary aspergillosis in asthmatic patients. MATERIALS AND METHODS: The high-resolution CT scans of 44 asthmatic patients with allergic bronchopulmonary aspergillosis and 38 asthmatic patients without allergic bronchopulmonary aspergillosis were analyzed retrospectively and randomly by two independent observers for these features: bronchial wall thickening, bronchiectasis, centrilobular nodules, mucoid impaction, mosaic perfusion, atelectasis, and consolidation. Each observer made a final diagnosis with a stated degree of confidence. The results are expressed as the average number of observations by the two observers. RESULTS: Findings seen more commonly in patients with allergic bronchopulmonary aspergillosis than in patients with asthma alone included bronchiectasis, centrilobular nodules, and mucoid impaction (p < .01, chi-square test). Bronchiectasis was present in 42 (95%) of 44 patients with allergic bronchopulmonary aspergillosis, centrilobular nodules in 41 (93%), and mucoid impaction in 29.5 (67%) (average of two observers). In the asthmatic control group, bronchiectasis was detected in 11 (29%) of 38 patients, centrilobular nodules in 10.5 (28%), and mucoid impaction in 4%. Bronchiectasis was seen in 184 (70%) of 264 lobes of patients with allergic bronchopulmonary aspergillosis compared with 19.5 (9%) of 228 lobes in asthmatic controls (p < .001, chi-square test). CONCLUSION: In asthmatic patients, bronchiectasis affecting three or more lobes, centrilobular nodules, and mucoid impaction are findings on high-resolution CT that are highly suggestive of allergic bronchopulmonary aspergillosis.

Respiratory bronchiolitis, respiratory bronchiolitis-associated interstitial lung disease, and desquamative interstitial pneumonia: different entities or part of the spectrum of the same disease process?

OBJECTIVE: Our objective was to assess high-resolution CT findings of respiratory bronchiolitis, respiratory bronchiolitis-associated interstitial lung disease, and desquamative interstitial pneumonia and to determine whether these three entities could be reliably differentiated by radiologic criteria. MATERIALS AND METHODS: CT scans (1- to 3-mm collimation) were reviewed in 40 patients with pathologically proven respiratory bronchiolitis (n = 16), respiratory bronchiolitis-associated interstitial lung disease (n = 8), or desquamative interstitial pneumonia (n = 16). All patients with respiratory bronchiolitis and respiratory bronchiolitis-associated interstitial lung disease were cigarette smokers, and 85% of the patients with desquamative interstitial pneumonia had a history of smoking. CT scans were independently reviewed by two radiologists who assessed the pattern and distribution of abnormalities. RESULTS: The predominant abnormalities in respiratory bronchiolitis were centrilobular nodules (12 [75%] of 16 patients) and ground-glass attenuation (six [38%] of 16). No single abnormality predominated in the respiratory bronchiolitis-associated interstitial lung disease group; findings included ground-glass attenuation (four [50%] of eight), centrilobular nodules (three [38%] of eight), and mild fibrosis (two [25%] of eight). All patients with desquamative interstitial pneumonia showed ground-glass attenuation, and 10 (63%) of the 16 showed evidence of fibrosis. CONCLUSION: The significant overlap between the CT findings of respiratory bronchiolitis, respiratory bronchiolitis-associated interstitial lung disease, and desquamative interstitial pneumonia is consistent with the concept that they represent different degrees of severity of small airway and parenchymal reaction to cigarette smoke.

Mycoplasma pneumoniae pneumonia: radiographic and high-resolution CT features in 28 patients.

OBJECTIVE: The aim of the study was to compare the radiographic and the high-resolution CT findings of Mycoplasma pneumoniae pneumonia. MATERIALS AND METHODS: The chest radiographs and 1.5-mm collimation CT scans obtained in 28 patients with serologically proven M. pneumoniae pneumonia were retrospectively reviewed. The radiographs and CT scans were analyzed independently by two observers. RESULTS: The most common finding on radiography was the presence of air-space opacification (n = 24), which was patchy and segmental (n = 9) or nonsegmental (n = 15) in distribution. On high-resolution CT, areas of ground-glass attenuation were seen in 24 patients (86%) and air-space consolidation in 22 (79%). In 13 patients (59%), the areas of consolidation had a lobular distribution evident on CT. Nodules were seen more commonly on high-resolution CT (25 of 28 patients, 89%) than on radiography (14 patients, 50%) (p < 0.01, chi-square test). In 24 (86%) of the 28 patients, the nodules had a predominantly centrilobular distribution on CT. Thickening of the bronchovascular bundles was identified more commonly on CT (23 of 28 patients, 82%) than on radiography (five patients, 18%) (p < 0.01, chi-square test). CONCLUSION: The lobular distribution, centrilobular involvement, and interstitial abnormalities in M. pneumoniae pneumonia are often difficult to recognize on radiography but can usually be seen on high-resolution CT.

Pancreatic transplantation using portal venous and enteric drainage: the postoperative appearance of a new surgical procedure.

PURPOSE: To review the normal radiologic appearance of pancreatic transplants that use portal venous and enteric drainage, and to review the appearance of a variety of postoperative complications. METHOD: We retrospectively reviewed the computed tomographic (CT) scans, magnetic resonance (MR) images, and ultrasounds of patients who had undergone pancreatic transplantation using portal venous and enteric drainage. RESULTS: At CT, the normal pancreatic transplant appears as a heterogeneous mass composed of pancreatic parenchyma, vessels, and omental wrap. On MR imaging, a normal transplant demonstrates intermediate signal intensity on T1- and T2-weighted sequences. Sonographic evaluation of a normal transplant reveals a hypoechoic gland that contains readily detectable low-resistance arterial and venous Doppler waveforms. Acute postoperative complications include acute rejection, which has a nonspecific radiologic appearance, and transplant pancreatitis, which is often manifested on CT by stranding of the peritransplant fat. Chronic postoperative complications include small bowel obstructions, graft pancreatitis secondary to obstruction of the Roux loop, and chronic rejection. CONCLUSION: Knowledge of the radiologic appearance of the normal pancreatic transplant is required before transplant-related complications can be detected.