Spirometrically controlled quantitative CT for assessing diffuse parenchymal lung disease

OBJECTIVE: Assessment of lung attenuation by CT reflects changes in the air-to-tissue ratio of the lung. We have analyzed the interdependence of intrathoracic gas volume, lung morphology, and functional disorder by high resolution CT (HRCT) to assess quantitative disease threshold in obstructive and restrictive diffuse lung disease. MATERIALS AND METHODS: Pulmonary HRCT was performed on 24 healthy volunteers, 11 patients with chronic obstructive pulmonary disease (COPD), and 16 patients with idiopathic lung fibrosis (IPF). HRCT measurement was standardized by taking three scans at the carina +/- 5 cm and by defining inspiration levels by percent vital capacity (VC) via spirometrically gating to the scanner. RESULTS: The mean lung density at 50% VC (DL50) for healthy subjects was -819 +/- 3.8 (mean +/- SEM) HU. In contrast, COPD DL50 was lower, averaging -861 +/- 6.4 HU, and the IPF DL50 was considerably higher (-731 +/- 17.7 HU), both significantly different (p < 0.001) compared with the control group. The accuracy of quantitative HRCT at different inspiration levels was evaluated by scanning the basal layer at 20, 50, and 80% VC. The control values were -747 +/- 5.6, -816 +/- 3.6, and -855 +/- 3.0 HU, respectively, which were significantly higher (p < 0.001) than those seen in COPD patients at 20 and 50% VC. Again, the IPF patients exhibited increased lung density (p < 0.001) at all inspiratory levels. Discrimination power was best among all cohorts at 20 and 50% VC. Position-dependent artifacts on lung density were quantified by the anteroposterior density gradient (APG). Irrespective of the underlying disease, APG at 50 and 80% VC was similar, but was up to twofold higher at 20% VC, indicating that quantitative estimates near RV may misrepresent mean lung density. CONCLUSION: Our data indicate that quantitative HRCT measurements should be performed not near full inspiration or expiration, but at an intermediate degree of lung inflation, e.g., 50% VC, for reasons of accuracy, intra- and intersubjective comparability, and feasibility. We conclude quantitative HRCT to be a sensitive tool for the evaluation of diffuse parenchymal lung disease.     

Bounds on null functions of linear digital imaging systems

OBJECTIVE: The purpose of this investigation was to quantitatively assess abnormally low attenuation of the lung by use of three-dimensional volumetric reconstructions from routine helical CT and to assess their correlation with pulmonary function tests. MATERIALS AND METHODS: Helical CT was performed in 100 patients in full inspiration. Examination was also performed in full expiration in 53 of these patients. Three-dimensional volumetric reconstructions were performed for total lung volumes at inspiration and at expiration, with a threshold of -896 H on inspiratory CT and -790 H on expiratory CT, to quantify emphysematous change. Correlation was made with pulmonary function tests in 79 patients. RESULTS: CT volumetric assessments of abnormally low attenuation of the lung at inspiration and expiration had a high correlation (r2 = .84, p < or = .0001). In comparison with pulmonary function tests, both inspiratory low attenuation of the lung and expiratory low attenuation of the lung correlated well with the logarithm of the ratio of the forced expiratory volume in 1 sec (FEV1) to the forced vital capacity (r2 = .74, p < or = .0001 and r2 = .74, p < or = .0001, respectively) and with the percentage of predicted ratio of the FEV1 to the forced vital capacity (r2 = .69, p < or = .0001 and r2 = .69, p < or = .0001, respectively). Linear correlations were also seen with FEV1, residual volume, and forced residual capacity. CONCLUSION: Three-dimensional volumetric reconstructions of hypoattenuating lung correlate well with pulmonary function tests. In addition, inspiratory and expiratory data are also correlative, suggesting that a dedicated expiratory examination is not needed. This easily obtainable information will prove useful for patients with obstructive lung disease from emphysema, providing a measure of pulmonary function status in this population.     

Mechanism of mosaic attenuation of the lungs on computed tomography in induced bronchospasm

The purpose of this study was to investigate whether hypoxic pulmonary vasoconstriction is the major determinant of the computed tomography (CT) pattern of mosaic attenuation in asthmatic patients with induced bronchoconstriction. Thin-section CT was performed at suspended full inspiration immediately and 30 min after methacholine bronchoprovocation in 22 asthmatic subjects, who were randomly assigned to breathe room air (group A, n = 8), oxygen via nasal prongs at 5 l/min (group B, n = 8), and oxygen via face mask at 12 l/min (group C, n = 6). CT changes were quantified in terms of global lung density and density in hypodense and hyperdense areas. Lung parenchymal density increases were greatest in group C and greater in group B than in group A, globally (P = 0.03) and in hypodense regions (P = 0.01). On bivariate analysis, the only change in cross-sectional area was related to change in global density. In hypodense regions, density change was related both to reduction in cross-sectional area (P < 0.0005) and to oxygen administration (P = 0.01). After correction for changes in global lung density, only oxygen was independently related to density increase in hypodense areas (P = 0.02). In induced bronchoconstriction, the CT appearance of mosaic attenuation can be largely ascribed to hypoxic vasoconstriction rather than to changes in lung inflation.     

Three-dimensional display of the bronchi using helical CT

The purpose of this study was to evaluate the clinical usefulness of three-dimensional (3D) images of the bronchi obtained using helical CT. Thirteen patients with lung cancer, one with tracheal diverticulum, and one with bronchial amyloidosis were examined. The CT scanner employed was the Toshiba Xforce. The helical CT scan cycle consisted of 20 continuous rotations, each requiring 1.5 sec, for a total scanning time of 30 sec. Scans were obtained using a 5-mm X-ray beam width, a 5-mm/1.5 sec couchtop sliding speed, and a 2-mm reconstruction interval. 3D images were reconstructed using a CEMAX VIPstation. The optimal lower and upper threshold CT values for 3D images of the bronchi were -650 and -100 HU, respectively, and 3D images clearly depicted endobronchial lesions. Cartilage crescents were also demonstrated, but longitudinal and circular mucosal folds could not be visualized. In conclusion, 3D images of the bronchi acquired using helical CT were useful in evaluating endobronchial lesions.     

6-Hydroxycatecholine, a choline-mimicking analogue of the selective neurotoxin, 6-hydroxydopamine

The purpose of this prospective study was to verify whether the percentage area of lung occupied by lowest attenuation values on high-resolution computed tomography (HRCT) scans reflects microscopic emphysema and to compare this quantification with the information yielded by the most widely used pulmonary function tests (PFT). Preoperative HRCT scans were obtained with 1-cm intervals in 38 subjects. With a semiautomatic evaluation procedure, the percentage areas occupied by attenuation values inferior to thresholds ranging from -900 Hounsfield units (HU) to -970 HU were calculated for the lobe or lung to be resected. Emphysema was microscopically quantified by using a computer-based method, measuring the perimeters and interwall distances of alveoli and alveolar ducts. The strongest correlation was found for -950 HU. As a second step, we evaluated possible correlations between PFT and microscopic measurements. Finally, considering the microscopic measurements as a standard, we tried to investigate their relationships with each of the PFT and with the relative area occupied by attenuation values lower than -950 HU for both lungs. This revealed that the diffusing capacity for carbon monoxide associated with HRCT quantification is sufficient to predict microscopic measurements. We concluded that the percentage area of lung occupied by attenuation values lower than -950 HU is a valid index of pulmonary emphysema.     

Acute interstitial pneumonia: high-resolution CT findings correlated with pathology

OBJECTIVE: The purpose of this study was to evaluate the relation between pathologic phases and high-resolution CT (HRCT) findings in patients with acute interstitial pneumonia (AIP). MATERIALS AND METHODS: Our retrospective review found 14 patients with AIP who were included in this study. Three patients were pathologically diagnosed as having AIP by open lung biopsy, and the other 11 patients were confirmed at autopsy. In eight of the 11 autopsy patients, the postmortem lungs were inflated and fixed by Heitzman's method, and a postmortem HRCT scan was obtained on all 11 autopsy patients. Paying special attention to the disease stage, we selected 27 areas of the lung from antemortem or postmortem HRCT and correlated them with pathologic findings. RESULTS: Nine areas of the lung that showed increased attenuation without traction bronchiectasis were associated with either the exudative (n = 5) or early proliferative (n = 4) phase of AIP. Eleven areas of increased attenuation with traction bronchiectasis were associated with either the proliferative (n = 4) or fibrotic (n = 7) phase of AIP. Honey-combing, observed in one area of the lung, corresponded to restructuring of distal airspaces and dense interstitial fibrosis. Six spared areas, within or adjacent to areas of increased attenuation, showed pathologic findings of the exudative phase. CONCLUSION: HRCT findings were not specific for the pathologic findings in our patients with AIP. Nevertheless, the findings of traction bronchiectasis in areas of increased attenuation suggested the proliferative or fibrotic phase.     

Digital color imaging colposcopy: a matter of choice

PURPOSE: The objective of this study was to correlate the findings of sarcoidosis on high resolution CT (HRCT) with indexes of disease activity as measured with 67Ga scan, bronchoalveolar lavage (BAL), and serum angiotensin-converting enzyme (SACE) assay. METHOD: Twenty-nine patients with proven sarcoidosis underwent HRCT scan, 67Ga scan, BAL, and SACE assay within a 1 month period. The extent of parenchymal involvement by nodules, consolidation, ground-glass attenuation, and linear opacities was quantified to the nearest 10% of surface area affected on the CT examination. Whole-lung gallium uptake was quantified and the percentage of BAL-recovered lymphocytes (BAL-%LC) and SACE levels obtained by chart review. CT scores of disease extent were correlated with measured indexes of activity using the Spearman rank correlation coefficient. RESULTS: The mean extent of nodules, consolidation, ground-glass attenuation, and linear opacities on HRCT images was 15.1 +/- 16.6, 1.6 +/- 4.0, 17.5 +/- 25.4, and 7.6 +/- 9.6%, respectively. The extent of nodules and consolidation correlated with the intensity of lung gallium uptake (r = 0.46, p < 0.02), BAL-%LC (r = 0.50, p < 0.01), and SACE levels (r = 0.38, p < 0.05). No significant correlation was found between extent of ground-glass attenuation or linear opacities with any indexes of disease activity. CONCLUSION: On HRCT scan, nodules and consolidation in sarcoidosis reflect disease activity as measured by 67Ga scan, BAL, and SACE assay.     

Comparison between morphologic changes seen on high-resolution CT and regional pulmonary perfusion seen on SPECT in patients with cystic fibrosis

OBJECTIVE: To evaluate the relationship between morphologic findings seen on high-resolution computed tomography (HRCT) of the lung and regional lung perfusion depicted on single photon-emission computed tomography (SPECT) pulmonary perfusion imaging in patients with cystic fibrosis. MATERIALS AND METHODS: Ten HRCT and 10 technetium-99 m macroaggregated albumin SPECT pulmonary perfusion imaging studies were performed on eight young adult patients who were considered to be clinically well and have mild to moderate cystic fibrosis. HRCT scans of the chest were evaluated using a CT scoring system which included grading of bronchiectasis, peribronchial thickening, hyperlucency, bullae, collapse/consolidation, and mucus plugging. Each lung was divided into six anatomic zones which were independently scored. A lung perfusion score (between 0 and 100), reflecting the percentage of compromised lung, was estimated for each zone. Axial lung perfusion SPECT images were matched anatomically to HRCT images. Lung function was considered compromised when the counts per pixel were less than 25 % of the count level seen in an area of the same patient's lung which was judged to be normal. RESULTS: There was a statistically significant relationship (P = 0.0001) between HRCT total scores and SPECT lung perfusion scores as well as between hyperlucency scores by HRCT and the SPECT lung perfusion scores. However, the HRCT score was a poor predictor of the lung perfusion score in zones with intermediate HRCT scores, which constituted 106 of 120 zones. CONCLUSION: Morphologic changes depicted by HRCT correlate with decreased lung pefusion on SPECT. However, HRCT changes accurately predict regional lung function only in the most normal and severely diseased lung zones.     

Pulmonary infection with Mycobacterium avium-intracellulare leads to air trapping distal to the small airways

To clarify the structure and function of the airways in Mycobacterium avium-intracellulare (MAI) infection, we performed pulmonary function tests and high-resolution computed tomography (HRCT) of the thorax in female patients 61 +/- 9 yr of age (n = 12) with pulmonary MAI infection without predisposing lung disease and compared their data with those of normal female volunteers 54 +/- 8 yr of age (n = 9). We calculated the E/I ratio, i.e., the average ratio of HRCT number at full expiration to that at full inspiration, as an index for the evaluation of air trapping distal to the small airways. Patients showed significant increases in residual volume and slope of phase III (DeltaN2) of the single-breath nitrogen test, and significant decreases in flow at 50 and 25% of FVC, suggesting hyperinflation and obstruction of the small airways. HRCT of patients revealed the small nodules and ectasis of bronchioles and small bronchi located mainly in segments (S) S2, S3, S4, and S5. The E/I ratio was significantly elevated in patients, and especially higher in the upper lung field than in the lower lung field, suggesting air trapping distal to the small airways. The difference of E/I ratio between the upper and lower field is probably related to the segmental distribution of CT abnormalities. These findings suggest that MAI infection can lead to air trapping distal to the small airways.     

Optimizing contrast enhancement during helical CT of the liver: a comparison of two bolus tracking techniques

OBJECTIVE: The purpose of this study was to evaluate a recently developed hardware and software system for CT scanning that generates images in real time and switches to helical CT scanning by either a visual cue or a region of interest (ROI) amplitude threshold. SUBJECTS AND METHODS: We randomly and prospectively divided 120 abdominal CT examinations into three groups. Two groups received 75 ml of contrast agent at 1.5 ml/sec. Helical CT scanning began after visualization of the contrast bolus arrival in the hepatic veins (visual cue triggering) (39 patients) or after reaching an ROI threshold (automated ROI threshold triggering) (39 patients). A third group served as a control group (42 patients) and received 150 ml of contrast agent at 1 ml/sec. Quality of hepatic enhancement was assessed objectively and subjectively. Comparisons were made after stratifying each group into three weight classes. RESULTS: Errors occurred in 12 (31%) of 39 examinations in the group with automated ROI threshold triggering. In that group, we found a significantly (p < .04) lower mean hepatic enhancement in two of three weight categories, and a significantly (p < .04) lower mean subjective scan quality in one of three weight categories, than we found in the group with visual cue triggering. CONCLUSION: Optimizing portal venous phase helical CT of the liver after a low-volume bolus of contrast agent and an injection rate of 1.5 ml/sec is best achieved by initiating helical CT scanning after visualizing the contrast bolus arrival within the liver rather than after reaching a preset attenuation threshold.     

Assessment of complications in patients with lung transplantation with high resolution computerized tomography

INTRODUCTION: High Resolution Computed Tomography (HRCT) has been used by many authors to study the early complications of lung transplantation. Bronchoscopy, transbronchial biopsy and the clinical parameters are the tools of choice to diagnose such complications; HRCT showed excellent sensitivity (100%) and good specificity (93%) especially in detecting bronchial stenoses. We report the preliminary results of HRCT in detecting early/late complications in lung transplant recipients. MATERIAL AND METHODS: Sixteen lung transplant recipients (5 single and 11 double transplants) were examined with HRCT at the Servizio Speciale Diagnostica V of "La Sapienza" University (Rome, Italy). The CT findings were compared with the results of bronchoscopy and respiratory function tests. The patients (8 men and 8 women; age range: 18-57 years, mean: 37.5) had cystic fibrosis (9), emphysema (3), alpha-1-antitrypsin deficiency (1), idiopathic pulmonary fibrosis (2), and bronchiectasis (1). RESULTS AND DISCUSSION: During the follow-up, one patient died of pulmonary edema. CT findings were normal in 3 patients and mild pleural effusion was seen in 2. The other HRCT findings were: bronchial stenosis in 5 cases (which was bilateral in 1) and bronchial dehiscence in 1 patient; four cases of infection (1 CMV, 1 aspecific bacterial pneumonia, 1 Chlamydia psittacea and 1 Aspergillosis) and one of brochiolitis obliterans. A patient was treated for acute and one for chronic rejection. A CMV infection involved only the native lung in a patient. CT is easy to perform and a repeatable and well-tolerated tool with high sensitivity (100%) and good specificity (93%) in the early diagnosis of complications, particularly bronchial stenoses, which complications are often missed at bronchoscopy or clinically silent. CT should be always performed before bronchoscopy because it can provide valuable information for bronchoscopy targeting. CONCLUSIONS: In agreement with other authors we consider HRCT a very useful tool in the early diagnosis of the complications following lung transplantation.     

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INTRODUCTION: High-resolution computed tomography (HRCT) with iodinated contrast material has been used by many authors to study solitary pulmonary nodules (SPNs). The degree of enhancement was correlated with the nodule malignancy. MATERIAL AND METHODS: Forty adult patients were examined, before and after contrast agent administration, with incremental dynamic CT. We selected 22 patients with SPNs (3-30 mm phi, except one with 40 mm phi). The CT numbers of the inner nodule were calculated before and 1, 2 and 3 minutes after the i.v. administration of a weight-related dose (1.5 mL/kg/min) of nonionic iodinated contrast agent. A dose of 100 mL contrast agent was used in the first 6 patients. The difference in CT numbers between unenhanced images and the images with maximum enhancement (max. attenuation) was also calculated. RESULTS: Histologic diagnoses included 4 tuberculomas, 3 hamartomas and 15 malignant tumors (9 adenocarcinomas, 5 squamous cell carcinomas and 1 non-Hodgkin lymphoma). The CT numbers (in Hounsfield units, HU) of malignant nodules ranged 12-31 HU (mean: 21.5 HU) before contrast agent administration; the "long-standing" tuberculomas ranged 11-22 HU (mean: 16.5 HU) and the hamartomas had a mean density of 10.5 HU. We excluded for the study two "fresh" tuberculomas, one of which was surrounded by a low-attenuation infiltrate (the halo sign). We selected a threshold value of 20 HU on enhanced CT images to distinguish malignant (> or = 20 HU) from benign (< or = 20 HU) nodules. All lung cancers had complete enhancement (mean density: 35.5 HU). With 20 HU as the threshold value for a positive test, sensitivity was 100%, specificity 85.7%, positive predictive value 93.8% and negative predictive value 100%; test bias was 1.067. CONCLUSION: Positron emission tomography (PET) with 2-[fluorine-18] fluoro-2-deoxy-D glucose is reported to be as accurate as enhanced HRCT, but it does not provide accurate morphological information, is not widely available and it is quite expensive: therefore, in our opinion, CT should be preferred. After examining over 100 patients, we may use our results in the decision analysis comparing surgical risk with cancer risk.     

Aspiration after administration of oral contrast material in children undergoing abdominal CT for trauma

OBJECTIVE: The practice of routinely administering oral contrast material to children undergoing abdominal CT for blunt trauma is controversial, primarily because of the increased risk of aspiration. The purpose of this study was to determine how often aspiration occurs in this population of children. MATERIALS AND METHODS: We retrospectively studied 50 children who underwent abdominal CT scans after blunt trauma. All children received diluted 3% water-soluble oral contrast material. The medical record of each child was reviewed for evidence of aspiration pneumonia as many as 48 hr after the CT. In each patient, sections of the CT scan through the lung bases were examined for opacities. When lung opacities were identified, they were classified as atelectasis, confusion, laceration, or nonspecific. We made attenuation measurements of lung opacities larger than 1 cm, and each measurement was compared with the attenuation measurement of contrast material in that patient's stomach. Student's two-tailed t test was used to compare the two measurements. RESULTS: Four patients were febrile after the CT scan, but in none was aspiration pneumonia suspected to be the cause. The remaining 46 patients did not have any clinical evidence of aspiration. Twelve of the 50 patients had pulmonary opacities revealed by CT that were sufficiently large that attenuation measurements could be obtained. The opacity in one of these patients was classified as nonspecific, and the attenuation was as high as that of contrast material in the stomach. CONCLUSION: No clinically symptomatic episodes of aspiration pneumonia were found in 50 pediatric patients with blunt trauma who were given oral contrast material for abdominal CT. Although one of the children had CT findings that suggested clinically silent aspiration of oral contrast material, no evidence was found that administration of oral contrast material was harmful.     

Experimentally induced pulmonary arterial occlusion with detachable balloon in pigs: thin-section CT findings

RATIONALE AND OBJECTIVES: The authors evaluated changes of lung attenuation in pigs, with special attention to the mosaic pattern of low attenuation, at thin-section computed tomography (CT) after obstruction of the proximal pulmonary artery with a detachable balloon. MATERIALS AND METHODS: In seven pigs, nine sites of the descending pulmonary artery were obstructed with detachable balloons. This-section CT scans of the lungs were obtained immediately (n = 9) and at 1 week (n = 5), 2 weeks (n = 1), 3 weeks (n = 2), 4 weeks (n = 1), 6 weeks (n = 1), 8 weeks (n = 1), and 12 weeks (n = 1) after pulmonary artery obstruction. RESULTS: No statistically significant difference was found between the measured lung attenuation of the normal lung and that of the lung distal to the obstruction. Of the nine sites of pulmonary artery obstruction, five (56%) showed an irregular area of increased lung attenuation without lobular architecture. The diameter of the pulmonary artery after obstruction, compared with the diameter before obstruction, decreased by a range of 13%-57% (mean, 35%) and by 0-67% (mean, 44%) at levels 1 cm and 2 cm distal to the obstruction, respectively. CONCLUSION: This experimental study reveals that regional low-attenuation areas do not develop for up to 12 weeks after the obstruction of proximal pulmonary artery, despite a marked decrease in the diameter of the pulmonary artery distal to the obstruction.     

CT-pathologic correlation for the alveolar extension of pulmonary adenocarcinoma

Alveolar extension of pulmonary adenocarcinoma is characteristically demonstrated as an area of ground-glass attenuation (GGA). We correlated the CT attenuation value of GGA with the aeration rate of the pathologic specimen measured with a high-resolution image analyzer (OLYMPUS). The CT values of GGA seen in fourteen adeno-carcinomas were measured for helical (slice thickness 10mm) and thin slice CT (slice thickness 1 or 2mm). A positive correlation was found between the CT attenuation value and the aeration rate in the pathologic specimen (Spearman analysis < 1%).     

Diagnostic abilities of high-resolution CT, dynamic CT, and 201T1 SPECT in evaluating of pulmonary masses

The purpose of this study was to evaluate the diagnostic abilities of high-resolution CT (HRCT), dynamic CT (DCT), and T1-201 SPECT (T1) in determinating benignancy and malignancy (b-m) in pulmonary mass lesions. The diagnoses (35 adenocarcinomas, 10 squamous cell carcinomas, 6 other primary lung carcinomas, 8 tuberculomas, 13 other benignancies) were made in 20 patients (pts) by surgery, in 46 pts by biopsy or cytology, and in 6 pts by clinical course. In 72 pts (51 malignancies, 21 benignancies) who underwent DCT, increased attenuation of lesions at 90 seconds after the injection of contrast medium was a discriminative indicator, and the b-m threshold was defined as 22HU and 15HU for lesions of < or = 3cm and 3cm < in maximum diameter. In 56 pts (43 malignancies, 13 benignancies) examined by T1, lesion-to-contralateral normal lung ratios at 15 min (ER) and 3 hr (DR) were calculated, and the retention index (RI) was defined as (DR-ER)/ER 100. The b-m threshold of RI proved to be-6 for lesions of all sizes. In 40 pts (29 malignancies, 11 benignancies) who underwent both DCT and T1, HRCT was read on the basis of morphology by 7 observers (3 experienced, 2 senior, and 2 junior radiologists). Sensitivity and specificity were 88.2% and 71.4%, respectively, for DCT in 72 pts and 83.7% and 84.6% for T1 in 56 pts. A-receiver-operating characteristics (ROC) analysis revealed that only 2 experienced radiologists were superior to DCT and T1 in diagnostic accuracy. Sensitivity and negative predictive value were 100% and 100%, respectively, for the combination of DCT and T1, and 96.6% and 85.7% for the combination of the 2 experienced radiologists. In conclusion, the combination of DCT and T1 has excellent clinical efficacy in assessment b-m in pulmonary mass lesions.     

The arthroscopic appearance of lipoma arborescens of the knee

March, 1991, to June, 1992, five lung transplantations for end-stage lung disease were successfully performed at the Ospedale Maggiore Policlinico in Milan. All patients underwent high-resolution CT (HRCT) of the lung in a complex follow-up program to identify specific abnormalities of acute and chronic rejection (bronchiolitis obliterans) and to monitor the resolution of the bronchial anastomosis. Twenty-two HRCT exams were performed. In patients with acute rejection HRCT failed to identify specific abnormalities of lung parenchyma. In contrast, in one patient with pathological evidence of early bronchiolitis obliterans HRCT showed decreased peripheral vascularization. In the study of the bronchial anastomosis, HRCT showed optimal anastomosis resolution in 4 patients, whereas in one patient with a granuloma demonstrated by fibrobronchoscopy it confirmed the lesion showing also a small pneumomediastinum. Even though the HRCT finding of decreased peripheral vascularization does not appear to be specific for bronchiolitis obliterans, it may be of value in suggesting the diagnosis of early bronchiolitis obliterans in lung transplant. HRCT should be used in all patients with bronchoscopic diagnosis of bronchial complication to study the lesion and its mediastinal spread.     

Thermoregulatory responses of mesic and xeric rodent species to photoperiod manipulations

PURPOSE: To evaluate hypertrophied bronchial arteries on thin-section computed tomographic (CT) scans in patients with bronchiectasis by using CT angiographic correlation. MATERIALS AND METHODS: Spiral CT angiography was performed prospectively in 14 patients (eight men, six women; age range, 34-71 years) with bronchiectasis who were suspected of having bronchial arterial hypertrophy at thin-section CT (performed without contrast medium). The inclusion criteria were tubular (in six patients) or nodular (in 14 patients) areas of soft-tissue attenuation that had an appearance unlike that of lymph nodes at thin-section CT and that were within the mediastinum and around the central airway. These findings were subsequently correlated with the spiral CT angiographic findings. RESULTS: At comparative analysis of thin-section CT scans and CT angiograms, seven of the eight (88%) tubular lesions and 19 of the 36 (53%) nodular lesions in the mediastinal soft tissue were proved to be hypertrophied bronchial arteries. All of the six (100%) tubular and 19 of the 21 (90%) nodular lesions around the walls of the main (primary) and lobar bronchi were hypertrophied bronchial arteries. In eight (57%) patients, CT angiograms showed 11 intraluminal protrusions caused by hypertrophied bronchial arteries in the main bronchi, lobar bronchi, or both. CONCLUSION: Nodular and tubular structures in the mediastinum and around the central airway on thin-section CT scans in the patients with bronchiectasis are suggestive of hypertrophied bronchial arteries. Recognition of the hypertrophied bronchial artery can be critical for the bronchoscopist.     

Surgical margins and prognostic factors in patients with thick (>4mm) primary melanoma

PURPOSE: The aim of this project was to analyze and validate the diagnostic applications of Volumetric High Resolution CT in the study of focal or diffuse infiltrative lung disease compared with High Resolution CT. To date HRCT is the gold standard in the assessment of infiltrative lung diseases, but it shows some limitations such as artifacts due to both respiratory and cardiac motions, as well as the need for multiple breath-holds. MATERIAL AND METHODS: September, 1996, to September, 1997, anthropomorphic test phantoms and a group of 34 subjects (8 without lung disease and 26 with aspecific lung disease: TBC, BPCO, micronodular conditions, cardiogenic interstitial pulmonary edema) were submitted to both HRCT and VHRCT. VHRCT was carried out with a 3-mm slab thickness and the images were reconstructed with a 1-mm interval and processed with MIP and MinIP reconstructions. With both techniques we compared some physical parameters (slice sensitivity profile, noise, longitudinal resolution) and some radiographic findings (central and peripheral airways lumen, peripheral vessels, nodular and interstitial abnormalities, emphysema foci, focal areas of ground glass pattern and bronchiectasis). We calculated the radiation exposure dose of both HRCT and VHRCT, also testing a low-dose protocol. RESULTS: The analysis of physical parameters showed no major differences between HRCT and VHRCT regarding longitudinal resolution, while minimal advantages were found with HRCT for slice sensitivity profile and image noise. Radiographic analysis showed additional findings in 27% of patients with nodular disease using VHRCT-MIP in 8% of patients with emphysema and 25% of cases with focal areas of ground glass opacities, using VHRCT-MinIP. Relative to HRCT findings, VHRCT better depicted all patterns but subpleural nodules. The surface radiation dose was 2.8 times higher with VHRCT than HRCT. It is possible to halve radiation exposure using a low dose protocol (120 kV, 110-150 mA). CONCLUSIONS: Our study provides conclusive results concerning the use of VHRCT with standard technical parameters because this technique showed some advantages in the study of a wide range of diffuse or focal lung diseases. We suggest that this protocol be applied only in patients with mild forms of lung disease or in the cases of difficult interpretation, such as suspicious abnormal areas at HRCT, because its doses are higher. Out low-dose protocol is currently on trial but we expect promising results.     

Adult-onset disseminated tracheobronchial papillomatosis: CT features

The high resolution CT (HRCT) findings in an adult with disseminated tracheobronchial papillomatosis are discussed. In addition to polypoid masses within the trachea and main bronchi, diffuse ill-defined parenchymal centrilobular opacities were present; these reflect lesions within the small airways. Some of the nodules showed central cavitation. In a patient with centrilobular opacities, some of which cavitate, on HRCT and concomitant endobronchial or endotracheal abnormality, disseminated papillomatosis should be considered in the differential diagnosis, particularly if there is a history of hoarseness or laryngeal disease.