Evaluation of patients undergoing lung volume reduction surgery: ancillary information available from computed tomography

AIM

A number of imaging techniques have been used for the pre-operative assessment of patients for lung volume reduction surgery (LVRS). We evaluated whether data currently acquired from perfusion scintigrams and cine MR of the diaphragm are obtainable from high resolution CT (HRCT) of the thorax.

MATERIALS AND METHODS

Thirty patients taking part in a randomized controlled trial of LVRS against maximal medical therapy were evaluated. HRCT examinations (n= 30) were scored for (i) the extent and distribution of emphysema; (ii) the extent of normal pulmonary vasculature; and (iii) diaphragmatic contour, apparent defects and herniation. On scintigraphy, (n= 28), perfusion of the lower thirds of both lungs, as a proportion of total lung perfusion (LZ/T(PERF)), was expressed as a percentage of predicted values (derived from 10 normal control subjects). On cine MR (n= 25) hemidiaphragmatic excursion and coordination were recorded.

RESULTS

Extensive emphysema was present on HRCT (60% +/- 13.2%). There was strong correlation between the extent of normal pulmonary vasculature on HRCT and on perfusion scanning (r(s)= 0.85, P< 0.00005). Hemidiaphragmatic incoordination on MR was weakly associated with hemidiaphragmatic eventration on HRCT (P= 0.04).

CONCLUSION

The strong correlation between lung perfusion assessed by HRCT and lung perfusion on scintigraphy suggests that perfusion scintigraphy is superfluous in the pre-operative evaluation of patients with emphysema for LVRS.

Retained intrathoracic surgical swab: CT appearances

A retained surgical swab (gossypiboma) is a rare but important complication of intrathoracic surgery. The radiographic and computed tomography (CT) appearances are variable and depend on the chronicity and site of the swab within the chest. Two cases of retained swabs within the chest are reported. In both cases, the swab had become surrounded by lung. The swab within the pleural space acted as a nidus and resulted in infolding of the lung, superficially resembling an intrapulmonary abscess on CT.

Spiral computed tomography for pulmonary embolism

Spiral computed tomography pulmonary angiography is increasingly used in the non-invasive investigation of patients with suspected pulmonary embolism. This review will focus on current techniques and indications with an explanation of the computed tomography signs of pulmonary embolism, possible pitfalls in interpretation and limitations of the technique.

High-resolution computed tomography in the evaluation of fibrosing alveolitis

High-resolution computed tomography (HRCT) is now widely used in the investigation of patients with suspected or known diffuse lung disease. This article reviews some of the technical aspects of HRCT and the pathologic considerations that should be appreciated in the context of diagnosing fibrosing alveolitis. The precise quantitation of disease extent and characterization of disease pattern on HRCT has been used to provide new insights about the prognosis and pathophysiology of fibrosing lung disease.

Clinical significance of respiratory bronchiolitis on open lung biopsy and its relationship to smoking related interstitial lung disease

BACKGROUND

Respiratory bronchiolitis-associated interstitial lung disease (RBILD) is a rare form of interstitial lung disease which may present in similar fashion to other types of chronic interstitial pneumonia. The purpose of this study was to undertake a clinicopathological review of 10 patients with RBILD and to examine the clinical and imaging data related to its histopathological pattern, in particular the relationship of RBILD to smoking.

METHODS

Thirteen out of 168 retrospectively reviewed patients, from whom biopsy specimens were taken for suspected diffuse lung disease, were identified with a histopathological pattern of RBILD. Three cases were rejected as follow up data were unavailable. The 10 remaining cases constituted the study group and both clinical and imaging data were collected from patients' notes and referring physicians.

RESULTS

Histopathologically, four cases of RBILD overlapped with the pattern of desquamative interstitial pneumonitis (DIP) and nine also had microscopic evidence of centrilobular emphysema. Nine patients were smokers, ranging from 3 to 80 pack years. The one non-smoker had an occupational exposure to the fumes of solder flux. The sex distribution was equal with an age range of 32-65 years. Two patients were clubbed. Lung function tests showed both restrictive and obstructive patterns together with severe reductions in carbon monoxide transfer factor in seven patients. Chest radiographs showed reticular or reticulonodular infiltrates in five patients and a ground glass pattern in two. CT scans were consistent with either DIP or RBILD in six of eight patients. Although seven patients remained stable or improved, either with or without treatment, three patients deteriorated.

CONCLUSIONS

This study adds weight to the hypothesis that smoking can cause clinically significant interstitial lung disease, with deterioration in pulmonary function despite treatment. Given the overlapping histopathological patterns of RBILD and DIP and their strong association with smoking, the term "smoking related interstitial lung disease" is suggested for those patients who are smokers.

Visual quantitation and observer variation of signs of small airways disease at inspiratory and expiratory CT

Areas of decreased pulmonary attenuation representing small airways disease can be identified on computed tomography (CT). The objective was to quantify differences between inspiratory and expiratory CT for the detection of signs of small airways disease by four observers. Observer variation and the superiority of a fine versus a coarse grading system were also evaluated. Inspiratory and expiratory CT scans of 106 patients with conditions characterized by small airways disease and 19 healthy individuals were assessed by four observers. The extent of decreased attenuation was scored on a fine scale to the nearest 5% and also semiquantitatively on a coarser 5-point scale. Decreased attenuation was more extensive on expiratory CT (median. 6.7%; 0-76.7%) than on inspiratory CT (median, 3.8%; 0-81.7%). The fine scoring system had unacceptable interobserver variation (coefficient of variation, 80% for inspiratory CT, 70% for expiratory CT). The semiquantitative system had acceptable interobserver agreement (inspiratory CT k(w) = 0.64; expiratory CT, k(w) = 0.69) and good intra-observer agreement (inspiratory CT, k(w) = 0.80; expiratory CT, k(w) = 0.64). The major CT sign of small airways disease is more confidently quantified on expiratory CT. A fine scoring system is associated with unacceptable observer variation, and a coarse semiquantitative system is more suitable for quantitative studies of small airways disease.

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.

Follicular bronchiolitis: thin-section CT and histologic findings

PURPOSE

To evaluate the thin-section computed tomographic (CT) findings of follicular bronchiolitis and compare them with the histologic findings.

MATERIALS AND METHODS

Thin-section CT scans obtained in 12 patients (age range, 24-77 years; mean age, 47 years) with follicular bronchiolitis proved at open lung biopsy were reviewed by two observers. Underlying conditions included rheumatoid arthritis (n = 8), mixed collagen vascular disorders (n = 2), autoimmune disorder (n = 1), and acquired immunodeficiency syndrome (n = 1). All patients had thin-section CT scans (1.0-1.5-mm collimation, 11 patients; 3.0-mm collimation, one patient; high-spatial-frequency reconstruction algorithm) obtained at 10-mm intervals through the chest.

RESULTS

The main CT findings included bilateral centrilobular (n = 12) and peribronchial (n = 5) nodules. All 12 patients had nodules smaller than 3 mm in diameter; six patients also had nodules 3-12 mm in diameter. Areas of ground-glass opacity were present in nine (75%) patients. Histologically, all patients had lymphoid hyperplasia along the bronchioles; eight had peribronchiolar lymphocytic infiltration.

CONCLUSION

The cardinal CT feature of follicular bronchiolitis consists of small centrilobular nodules variably associated with peribronchial nodules and areas of ground-glass opacity.

A histologic pattern of nonspecific interstitial pneumonia is associated with a better prognosis than usual interstitial pneumonia in patients with cryptogenic fibrosing alveolitis

This study aimed to investigate whether there was a difference in outcome related to histologic pattern in cryptogenic fibrosing alveolitis (CFA) and to see whether there were correlations between clinical and radiologic findings and histology. One hundred thirteen lung biopsies from consecutive patients taken for the diagnosis of diffuse lung disease were reviewed and reclassified using the Katzenstein and Myers criteria for interstitial pneumonias. Patients lacking full investigational data at presentation and those with conditions predisposing to lung fibrosis were excluded, leaving 15 patients diagnosed with nonspecific interstitial pneumonia (NSIP) and 15 with usual interstitial pneumonia (UIP). Clinical and radiologic findings at presentation and serial lung function information and survival status in November 1998 were compared for the two groups. Survival was found to be significantly greater in the NSIP group compared with the UIP group (p < 0.001). This could not be explained by differences in treatment. Patients with UIP showed a progressive deterioration in lung function whereas those with NSIP remained stable. CT scans of patients with UIP showed more fibrosis than those of patients with NSIP (p < 0.011). A histologic diagnosis of NSIP is associated with a better prognosis than UIP. This subclassification of CFA is clinically useful.

A comparison of methods for enhancing the detection of areas of decreased attenuation on CT caused by airways disease

PURPOSE

The purpose of this work was to investigate thin section CT image enhancement of subtle areas of decreased attenuation of the lung parenchyma in suspected airways disease.

METHOD

Forty-seven consecutive patients with chronic sputum production underwent pulmonary function tests and high resolution CT (HRCT). Single section inspiratory (INSP), expiratory (EXP), and minimum intensity projection (MINIP) images through the lower lobes were acquired. A histogram stretch was applied to the INSP and MINIP images, generating two further image formats. The five image types were compared for the extent of decreased attenuation, observer confidence, and correlations with pulmonary function tests.

RESULTS

Interobserver variation was lowest with MINIP images (mean weighted K: MINIP 0.70, INSP sections 0.65, other image formats < or =0.48). Observers were most confident with EXP and MINIP images. EXP sections identified more disease than MINIP images (p<0.001). Correlations with pulmonary function tests were similar for each image format.

CONCLUSION

The HRCT changes of small airways disease are enhanced with image postprocessing. MINIP images are associated with increased observer confidence and agreement as compared with HRCT alone.

Imaging of patients with severe emphysema considered for lung volume reduction surgery

Lung volume reduction surgery has recently been reintroduced as a palliative treatment for patients with severe emphysema. Selection criteria vary between centres and imaging is extensively used, but the exact role of individual techniques in the selection process is still emerging.

Spontaneous regression of large-cell carcinoma of the lung--a rare observation in clinical practice

Spontaneous regression of non-small-cell lung carcinoma is extremely rare and there are few documented cases. We report a 59-year-old man with a right upper lobe tumour which showed progressive regression while hilar adenopathy appeared 2 months after the initial tumour detection. At operation, only scar tissue was found in the lung but a hilar lymph node contained large-cell undifferentiated carcinoma. This report indicates that a decrease in size of a pulmonary mass does not exclude the diagnosis of carcinoma and that metastatic disease can occur even if the primary tumour regresses.

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.

Pericardial thickening or effusion in patients with pulmonary artery hypertension: a CT study

OBJECTIVE

The aim of the study was to determine the prevalence of pericardial thickening or effusion revealed by CT in patients with pulmonary artery hypertension.

MATERIALS AND METHODS

Forty-five patients underwent pulmonary artery catheterization and CT of the thorax. On CT, we measured the maximum pericardial thickness, total pericardial score (the sum of four measures of pericardial thickness), and thickness of the anterior pericardial recess. Patients were grouped according to mean pulmonary artery pressure: group 1, less than 21 mm Hg (n = 15); group 2, 21-35 mm Hg (n = 15); and group 3, greater than 35 mm Hg (n = 15).

RESULTS

The prevalence of an increased pericardial score and increased maximum pericardial thickening was higher in group 3 than in group 1 or group 2 (p = .02 and < .001, respectively). Anterior pericardial recess thickening was markedly increased in group 3 (p < .0001). For all patients, significant correlations (Spearman's rank correlation coefficient = .44-.56, p < .005-.0001) were found between mean pulmonary artery pressure and all pericardial measures.

CONCLUSION

On CT, pericardial thickening or effusion is a frequent finding in patients with severe pulmonary hypertension.

Acute respiratory distress syndrome: CT abnormalities at long-term follow-up

PURPOSE

To document abnormalities at computed tomography (CT) in adult survivors of acute respiratory distress syndrome (ARDS), to determine the relationships between CT patients during the acute phase and at follow-up, and to assess the effects of mechanical ventilation on the development of CT abnormalities.

MATERIALS AND METHODS

Thin-section CT scans were obtained during the acute illness and at follow-up in 27 patients with ARDS. The extent and distribution of individual CT patterns were independently analyzed.

RESULTS

At follow-up CT, a reticular pattern was the most prevalent (23 patients [85%]) and extensive CT abnormality, with a striking anterior distribution (more anterior distribution than posterior distribution, P < .001). A reticular pattern at follow-up was inversely correlated with the extent of intense parenchymal opacification on scans obtained during the acute illness (Spearman r = -0.26; P < .001). The extent of a reticular pattern at follow-up CT was independently related to the total duration of mechanical ventilation (P = .02) but was most strongly related to the duration of pressure-controlled inverse-ratio ventilation (P < .001).

CONCLUSION

A reticular pattern, with a striking anterior distribution, is a frequent finding of follow-up CT in ARDS survivors and is most strongly related to the duration of pressure-controlled inverse-ratio ventilation.

Pulmonary sarcoidosis: morphologic associations of airflow obstruction at thin-section CT

PURPOSE

To identify relationships between the obstructive defects of pulmonary sarcoidosis and the computed tomographic (CT) patterns of disease.

MATERIAL AND METHODS

CT scans obtained in 45 patients were scored semiquantitatively for extent of five CT patterns, and the functional importance of each pattern was evaluated.

RESULTS

The most prevalent CT patterns were decreased attenuation (n = 40), a reticular pattern (n = 37), and a nodular pattern (n = 36). At univariate and multivariate analyses, a reticular pattern was the main determinant of functional impairment, particularly airflow obstruction. The extent of a reticular pattern was independently associated with airflow obstruction, as shown by the inverse relationships with the forced expiratory volume in 1 second (FEV1) (P < .001), FEV1-forced vital capacity ratio (P < .01), maximum expiratory flow at 25% above residual volume (P < .001), and maximum expiratory flow at 50% above residual volume (P < .001) and the positive relationship with the residual volume-total lung capacity ratio (P < .001).

CONCLUSION

In sarcoidosis, CT features compatible with small airways disease are common but contribute little to airflow obstruction, particularly in more advanced disease, which is characterized by an extensive reticular pattern. A reticular pattern at CT is the major morphologic association of airflow obstruction.

Clinical correlates in acute lung injury: response to inhaled nitric oxide

STUDY OBJECTIVES

The use of inhaled nitric oxide (NO) in the management of patients with ARDS has become widespread, although not all patients respond to this form of support. The aim of this study was to examine the relationship of responsiveness to inhaled NO and features of underlying disease.

DESIGN

Prospective observational study.

SETTING

The ICU of a university-affiliated, tertiary referral hospital.

PATIENTS

Twenty-six adult patients with established ARDS.

INTERVENTIONS

Conventional support for multiple organ failure, plus inhaled NO.

MEASUREMENTS AND RESULTS

Response to inhaled NO was assessed, and ARDS was characterized in terms of pulmonary morphology (scoring of high-resolution CT); inflammation (BAL neutrophil count and plasma myeloperoxidase concentration); and markers of lung injury severity (oxygenation deficit and pulmonary vascular resistance [PVR]). Fourteen patients responded to NO and 12 did not. There were no differences between the two groups in terms of CT score, inflammatory status, baseline oxygenation deficit, lung injury score, or PVR. Additionally, there was no difference in survival between responders and nonresponders. Patients who developed ARDS after thoracic surgery were significantly more likely to die than other patients (relative risk 4.1, p < 0.01). The oxygenation deficit and lung injury score correlated better with the extent of ground-glass opacification than with the volume of consolidated lung tissue.

CONCLUSION

We were unable to identify features of disease likely to be associated with a clinically useful response to inhaled NO therapy using the parameters studied.

Systemic markers of inflammation in stable bronchiectasis

Patients with bronchiectasis have an active local and systemic inflammatory response during infective exacerbations. Systemic markers of inflammation were investigated during a stable phase of their illness, because continued inflammation could affect their general health and be involved in disease progression. The relationship between levels of various systemic markers of inflammation and extent of disease on computed tomographic scan, lung function, sputum bacteriology and health related quality of life (HRQoL) was investigated in 87 noncystic fibrosis bronchiectasis patients. Several markers were elevated and correlated with the extent of disease and poor lung function. The total white cell count, neutrophil count and erythrocyte sedimentation rate correlated with both disease measures. Sputum bacteriology did not correlate with inflammation markers and patients with positive and negative cultures were similar. C-reactive protein and total white cell count correlated with some components of a disease-specific HRQoL questionnaire. In conclusion, patients with bronchiectasis in a stable phase have raised systemic markers of inflammation. Some markers, particularly the neutrophil count, correlate with disease severity. This result is in keeping with the hypothesis that the level of inflammation determines disease progression and health status.

Imaging the 'dirty lung'--has high resolution computed tomography cleared the smoke?

The histopathological abnormalities that characterize cigarette smokers' lung damage have been widely studied, but these microscopic changes do not fully explain the radiographic features that have been loosely termed the 'dirty lung'. High resolution computed tomography is not only more sensitive for the detection of early emphysema, it has also provided the imaging correlates of subtle parenchymal changes of smokers, for example, respiratory bronchiolitis - interstitial lung disease. Nevertheless, some aspects of the radiographic 'dirty lung' remain enigmatic.

Image processing and spiral CT of the thorax

The data set of the thorax acquired by spiral CT is volumetric. Such data can be processed so that conventional axial sections are supplemented by reconstructed images, in an attempt to answer specific clinical questions. This review considers three reconstruction techniques: multiplanar reformation, three-dimensional rendering and sliding-thin slab reconstruction. Their relative benefits and limitations are considered, as are the implications of image processing in general.

Enhancement of subtle density differences of the lung parenchyma on CT

Several pulmonary conditions are characterized by the finding of areas of decreased attenuation relative to adjacent normal lung parenchyma on computed tomography. In particular, the identification of areas of the lung affected by small airways disease is difficult as the reduction in lung density is subtle and the regions are poorly marginated. This paper presents a novel wavelet analysis technique which increases the conspicuity of differences between normal and abnormal lung parenchyma.