Biomedical subjects
Publications and source records attributed to N L Müller.
The role of chest radiography and computed tomography in the evaluation of pulmonary emphysema and chronic bronchitis is reviewed.
The aims of this paper are to summarize the current recommendations for the use of computed tomography (CT) and magnetic resonance imaging (MRI) in the chest and to suggest some possible future developments. The main developments of CT in the chest have been the introduction of high-resolution CT (HRCT), spiral CT and, more recently, multidetector spiral CT. HRCT is defined as thin-section CT (1- to 2-mm collimation scans), optimized by using a high-spatial resolution (edge-enhancing) algorithm. Several studies have shown that HRCT closely reflects macroscopic (gross) pathological findings. HRCT currently has the best sensitivity and specificity of any imaging method used for the assessment of focal and diffuse lung diseases. The advent of spiral CT and, more recently, multidetector CT scanners, has allowed for major improvements in the imaging of airways, pulmonary and systemic vessels, and lung nodules. Spiral CT facilitates multiplanar and three-dimensional display of structures and visualization of pulmonary and systemic vessels, with a level of detail that is comparable to that of conventional angiography. With the use of graphics-based software programs, spiral CT enables depiction of the luminal surface of the airways with images that resemble those of bronchoscopy (virtual bronchoscopy) or bronchography (virtual bronchography). Several studies have shown a high sensitivity and specificity for spiral CT in the diagnosis of acute pulmonary embolism. Therefore, spiral CT is rapidly becoming the imaging modality of choice in the diagnosis of pulmonary embolism. Like the radiograph, signal intensity on computed tomography is mainly due to a single parameter: electron density. The signal intensity of the magnetic resonance image depends on four parameters: nuclear density, two relaxation times called T1 and T2, and motion of the nuclei within the imaged lung volume. Abnormal soft tissue can be identified more easily through measurement of these four parameters than through use of computed tomography. Furthermore, because the spatial orientation of the image is determined by manipulation of magnetic fields, scans can be performed in any plane. The main indications for magnetic resonance in the chest have been in the evaluation of the heart, major vessels, mediastinum, and hilar structures because of the natural contrast provided by flowing blood. Of particular interest for the respirologist has been the recent development of magnetic resonance angiography. This technique consists of three-dimensional single breath-hold images obtained using gadolinium-based contrast agents. This is a promising technique for the diagnosis of acute and chronic pulmonary embolism.
The immunocompromised host is an individual with a decreased defense mechanism or immunity. Pulmonary complications commonly seen in these patients include infections, neoplasms, drug-induced lung disease, and pulmonary hemorrhage. High-resolution CT plays an invaluable role in confirming the presence of pulmonary disease and narrowing down the differential diagnosis in this group of patients. It also is helpful as a guide to the optimal type and site of biopsy. The pattern and prevalence of disease varies considerably between the AIDS and the non-AIDS group, and therefore, these two groups are considered separately.
The high-resolution CT findings of silicoproteinosis consist of numerous bilateral centrilobular nodular opacities, focal ground glass opacities, and patchy areas of consolidation. These findings reflect the presence of intra-alveolar accumulation of proteinaceous material.
PURPOSE: To determine the frequency and computed tomographic (CT) findings of recurrence of the primary disease after lung transplantation at six North American lung transplantation centers. MATERIALS AND METHODS: Medical records of 1,394 lung transplant recipients were reviewed to identify patients with recurrent primary disease. Their CT scans and pathologic specimens were reviewed. RESULTS: The frequency of disease recurrence in the six transplantation centers was 1% (15 of 1,394 patients), including six previously reported cases. Sarcoidosis recurred in nine (35%) of 26 transplants and was the most common disease to recur. Three (33%) of nine patients with recurrent sarcoidosis had correlative findings at CT. When present, CT findings were usually different at recurrence compared with pretransplantation CT findings. CONCLUSION: A relatively small percentage of patients are at risk for recurrence of primary disease following lung transplantation. Sarcoidosis is the most common disease to recur.
In recent years there have been major advances in chest imaging. These include significant refinements in previously available techniques such as computed tomography (CT) and magnetic resonance (MR) imaging and the introduction of new techniques into the clinical armamentarium, particularly positron emission tomography (PET) imaging. These advances have led to changes in the diagnostic approach to a number of conditions, particularly pulmonary embolism, lung cancer, diseases of the large and small airways, and diffuse lung disease. They have also brought new insights into the pathophysiology of lung disease. State of the art CT and MR imaging now allow objective quantification of lung disease and assessment of regional changes in ventilation and perfusion caused by airway and parenchymal abnormalities. The aim of this article is to summarize the most important clinical applications of the recent advances in imaging and to emphasize the topics of imaging research likely to attract particular attention from radiologists and clinicians in the near future.
Chest radiography allows detection of moderate and severe emphysema but does not allow quantitation of severity of disease or detection of mild emphysema. Chest radiography is helpful in assessing complications of emphysema such as pneumothorax or secondary infection of a bulla. HRCT provides a detailed image of emphysematous lung disease comparable to that of macroscopic pathologic appearance. The main role of HRCT in patients with COPD is in the preoperative assessment of patients being considered for bullectomy or LVRS.
High resolution computed tomography (HRCT) scans are increasingly used in hypersensitivity pneumonitis (HP). This study looked at HRCT findings at different phases of farmer's lung (FL), a common form of HP. A cross sectional analysis of 95 HRCT scans of FL cases (20 acute, 75 with a history of FL, 48 still in contact (Ex +) (dairy farm), and 27 who had ceased contact (Ex-)) was made. All scans were read independently by two, and if needed by three, radiologists blinded to the category. The lungs were divided into six regions (fives lobes + lingula), and read for attenuation/mosaic, ground-glass, micronodules, fibrosis, and emphysema. A score of 0-3 was given for each region and each variable: 0 = absence, 1 =<25% of the surface, 2 = 25-50%, 3 =>50%. Mediastinal lymphadenopathy was also noted. Ground glass, predominating in the lower lobes, was the most frequent feature in the acute and Ex+ cases. Other abnormalities had no preferential distribution. Ex+ had more ground-glass than the Ex- (p=0.0025). Emphysema was more frequently seen than interstitial fibrosis (p=0.004). Mediastinal lymphadenopathy was present in 26 cases (9 acute, 10 Ex+ and 7 Ex-). In conclusion, in farmer's lung: 1) ground-glass predominates in the lower lobes while the other abnormalities have no anatomic predilection; 2) contact avoidance allows a better resolution of computed tomography abnormalities than continued exposure; 3) emphysema is a more frequent finding than interstitial fibrosis; and 4) the presence of mediastinal lymphadenopathy has no negative diagnostic value.
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.
Lung transplantation has become an accepted procedure for the treatment of end-stage lung disease, being successful in improving the quality and length of life of many patients. The recognition and early treatment of complications is important for long-term survival of lung transplant recipients. The radiologist frequently plays a central role in investigation. The radiological appearance of pulmonary complications arising in the immediate, early (within 2 months) and late (after 2 months) stages post-transplantation are reviewed.
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.
PURPOSE: To test the hypothesis that absence of statistically significant lung nodule enhancement (< or =15 HU) at computed tomography (CT) is strongly predictive of benignity. MATERIALS AND METHODS: Five hundred fifty lung nodules were studied. Of these, 356 met all entrance criteria and had a diagnosis. On nonenhanced, thin-section CT scans, the nodules were solid, 5-40 mm in diameter, relatively spherical, homogeneous, and without calcification or fat. All patients were examined with 3-mm-collimation CT before and after intravenous injection of contrast material. CT scans through the nodule were obtained at 1, 2, 3, and 4 minutes after the onset of injection. Peak net nodule enhancement and time-attenuation curves were analyzed. Seven centers participated. RESULTS: The prevalence of malignancy was 48% (171 of 356 nodules). Malignant neoplasms enhanced (median, 38.1 HU; range, 14.0-165.3 HU) significantly more than granulomas and benign neoplasms (median, 10.0 HU; range, -20.0 to 96.0 HU; P < .001). With 15 HU as the threshold, the sensitivity was 98% (167 of 171 malignant nodules), the specificity was 58% (107 of 185 benign nodules), and the accuracy was 77% (274 of 356 nodules). CONCLUSION: Absence of significant lung nodule enhancement (< or = 15 HU) at CT is strongly predictive of benignity.
PURPOSE: To determine whether lung abnormalities at thin-section computed tomography (CT) in experimental hyperoxic lung injury correlate with the pathologic phases of diffuse alveolar damage (DAD). MATERIALS AND METHODS: Eighteen juvenile pigs were exposed to more than 80% oxygen-for 24, 48, 72, 96, or 120 hours-or room air in sealed cages. Their removed lungs were inflated with air infused through the trachea and examined with thin-section CT. Two independent observers, without knowledge of the exposure times, compared 63 areas selected on the CT scans with the corresponding pathologic and histologic findings, which were evaluated independently by two pathologists. RESULTS: CT findings correlated well with histologic findings (rho = 0.86, P <.001), which corresponded to the pathologic phases of DAD. All areas of normal CT attenuation, eight of nine spared regions within areas of opacity, and two of 15 areas of ground-glass opacity corresponded to the early exudative pathologic phase of DAD. All areas that showed traction bronchiolectasis at CT corresponded to the early proliferative pathologic phase. There was good observer agreement regarding the interpretation of CT findings (kappa statistic, >0.60) and histologic results (>/=0.70). CONCLUSION: Thin-section CT findings reflect the pathologic phases of DAD, although the early exudative phase cannot be specifically depicted by thin-section CT. Traction bronchiolectasis on a CT scan suggests progression to the proliferative phase.
PURPOSE: To determine whether various eosinophilic lung diseases can be differentiated by means of thin-section computed tomography (CT). MATERIALS AND METHODS: Thin-section CT scans in 111 patients with eosinophilic lung diseases-40 with chronic eosinophilic pneumonia, 16 with Churg-Strauss syndrome, 16 with allergic bronchopulmonary aspergillosis (ABPA), 13 with acute eosinophilic pneumonia, 12 with simple pulmonary eosinophilia, 11 with drug-induced eosinophilic pneumonia, and three with hypereosinophilic syndrome-were assessed independently by two observers. The observers recorded the abnormalities, diagnosis, and degree of confidence in the diagnosis. RESULTS: The two observers made a correct first-choice diagnosis on average in 61% of readings. The correct diagnosis was made in 78% of cases of chronic eosinophilic pneumonia; 81%, acute eosinophilic pneumonia; 44%, Churg-Strauss syndrome; 84%, ABPA; 17%, simple pulmonary eosinophilia; 27%, drug-induced eosinophilic pneumonia; and 33%, hypereosinophilic syndrome. The two observers made a correct diagnosis with a high degree of confidence in 36% of readings. There was moderate agreement between the observers for the correct diagnosis (kappa, 0.47) and for the correct diagnosis with a high degree of confidence (kappa, 0.59). CONCLUSION: Although eosinophilic lung diseases often can be differentiated by means of thin-section CT, correlation between CT findings and careful clinical evaluation are required for a definitive diagnosis.
PURPOSE: To describe the computed tomographic (CT) findings in patients with nonspecific interstitial pneumonia (NSIP) and to compare these with the CT findings of other chronic infiltrative lung diseases. MATERIALS AND METHODS: Findings in 50 patients with biopsy-proved NSIP and a CT scan were reviewed by two thoracic radiologists in consensus. After the findings were described, the observers judged whether the findings were compatible with previously published descriptions of NSIP or whether the findings would support the diagnosis of a different chronic infiltrative lung disease. RESULTS: Eleven (22%) of the 50 patients had CT findings that were compatible with previous descriptions of NSIP. Sixteen (32%) patients had CT findings that were more compatible with usual interstitial pneumonia. The other 23 (46%) patients had findings that were nondiagnostic or most compatible with the diagnosis of another chronic infiltrative lung disease. CONCLUSION: Contrary to previously published articles, there are a wide variety of CT findings in cases of NSIP.
High-resolution computed tomography (HRCT) has been used to examine airway narrowing. We developed an automated computed tomographic image analysis algorithm (computed tomographic airway morphometry; CTAM) to measure airway lumen area (Ai ), airway wall area (Awa), and airway angle of orientation. Tubes of varying size were embedded in Styrofoam and then scanned at angles between 0 degrees and 50 degrees to assess the accuracy of measurements made with CTAM. Two excised pig lungs were fixed in inflation, sectioned, and scanned. Ai and Awa were measured planimetrically from the cut surfaces to optimize CTAM measurement parameters. In CTAM, Ai was defined according to an airway-size-dependent threshold value, and total Awa was determined through a score-guided erosion method. Results were compared with measurements made through a previously validated method (manual method). CTAM provided accurate measurements of the tubes' Ai values at all angles; Awa was overestimated in direct relation to airway size. The manual method underestimated Ai and overestimated Awa in a manner directly related to airway size as well as to airway angle of orientation. In the excised lung, the mean errors of Ai and Awa measurements made with CTAM were 0.52 +/- 0.24 mm(2) and 0.17 +/- 0.32 mm(2) (mean +/- SEM), respectively. Ai errors with the manual method were similar, but Awa was overestimated to a greater degree (6.3 +/- 0.38 mm(2); p < 0.01) and the error was proportional to Awa (r = 0.64; p < 0.01). CTAM allows accurate measurements of airway dimensions and angle of orientation.
The use of spiral computed tomography (CT) for the diagnosis of pulmonary embolism has been compared to angiography, the current gold standard. However, the accuracy of pulmonary angiography has never been evaluated against an independent gold standard. The aim of this study was to compare contrast-enhanced spiral CT to pulmonary angiography for the detection of subsegmental-sized pulmonary emboli by using a methacrylate cast of porcine pulmonary vessels as an independent gold standard. We studied 16 anesthetized, juvenile pigs and injected colored methacrylate beads (3.8 mm, small; 4.2 mm, large) via the jugular vein. After embolization spiral CT (3 mm and 1 mm collimation), and pulmonary angiography were performed. Pigs were killed and the pulmonary arterial tree was cast using methacrylate. Spiral CT and angiography were interpreted independently by two radiologists. Sensitivity and 95% confidence intervals for 3 mm and 1 mm collimation CT and angiography, respectively, were: 82% (73 to 88%), 87% (79 to 93%), 87% (79 to 93%) (p = 0.42). Positive predictive values and 95% confidence intervals for 3 mm and 1 mm collimation CT and angiography, respectively, were: 94% (86 to 94%), 81% (73 to 88%), and 88% (80 to 93%). There was no difference between spiral CT and angiography for detection of subsegmental-sized pulmonary emboli. We conclude that spiral CT is comparable to angiography for detection of pulmonary emboli.
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.