Jeffrey S. Klein

High-resolution computed tomography of the chest in children with cystic fibrosis: support for use as an outcome surrogate.

Background. Outcome surrogates are indicators that reflect, rather than directly measure, patient benefit. In order to provide useful results, however, outcome surrogates must be carefully chosen and must meet specific criteria. Objective. To support development of high-resolution computed tomography (HRCT) as an outcome surrogate in cystic fibrosis (CF) by demonstrating the ability of HRCT to show short-term improvement in the appearance of the lungs in children with CF. Materials and methods. HRCT was performed at admission and after discharge on 8 children during 15 admissions for acute pulmonary exacerbation of CF. Three radiologists scored each study separately, then compared admission and discharge pairs. Results. HRCT scores improved in 13/15 admissions. Mean score decreased from 25 to 22. The decrease was significant (P = 0.014). Comparison of admission and discharge scans showed improvement in peribronchial thickening (P = 0.007), mucous plugging (P = 0.002), and overall appearance (P = 0.025). Conclusion. HRCT has the potential to be a useful outcome surrogate in CF. A necessary attribute of an outcome surrogate is that it improves rapidly with effective therapy. Despite widespread belief among radiologists and pulmonologists that HRCT meets this criterion, no previous report has demonstrated this ability in children. These findings support further development of HRCT as an outcome surrogate in children with CF.

TRANSTHORACIC NEEDLE BIOPSY

Transthoracic needle biopsy (TNB) has emerged as the semi-invasive technique of choice for the diagnosis of localized intrathoracic lesions. Using CT, fluoroscopic, or sonographic guidance, TNB is highly accurate and safe when combined with expert pathologic interpretation of the aspirated specimen. This article details the preprocedural evaluation of the patient referred for TNB and discusses the technical aspects of performing the biopsy and processing and interpreting the material obtained. The reported results and complications of TNB are reviewed and followed by a brief description of the cost effectiveness of the technique and a comparison with alternative semi-invasive diagnostic techniques including bronchoscopic and video-assisted thoracoscopic biopsy.

The solitary pulmonary nodule

The radiologic evaluation of the solitary pulmonary nodule (SPN) is a common diagnostic dilemma. Although available clinical data and findings on conventional radiographs are important components in determining the imaging approach to the SPN, evaluation with CT often is necessary for detailed evaluation. This article reviews the radiologists approach to the evaluation of the SPN, with a particular focus on the role of thin-section CT for morphologic and density analysis. The relative use of contrast-enhanced CT and nuclear medicine, particularly positron emission tomography, in detecting nodule enhancement is discussed. If the use of low-dose helical CT for screening for early lung cancer in the form of a SPN becomes widespread practice, it is likely that radiologists will encounter an increasing number of smaller SPNs in the near future.

Diagnostic Utility and Clinical Application of Imaging for Pleural Space Infections

Timely diagnosis of pleural space infections and rapid initiation of effective pleural drainage for those patients with complicated parapneumonic effusions or empyema represent keystone principles for managing patients with pneumonia. Advances in chest imaging provide opportunities to detect parapneumonic effusions with high sensitivity in patients hospitalized for pneumonia and to guide interventional therapy. Standard radiographs retain their primary role for screening patients with pneumonia for the presence of an effusion to determine the need for thoracentesis. Ultrasonography and CT scanning, however, have greater sensitivity for fluid detection and provide additional information for determining the extent and nature of pleural infection. MRI and PET scan can image pleural disease, but their role in managing parapneumonic effusions is not yet clearly defined. Effective application of chest images for patients at risk for pleural infection, however, requires a comprehensive understanding of the unique features of each modality and relative value. This review presents the diagnostic usefulness and clinical application of chest imaging studies for evaluating and managing pleural space infections in patients hospitalized for pneumonia.

Interventional Management of Pleural Infections

Pleural infections represent an important group of disorders that is characterized by the invasion of pathogens into the pleural space and the potential for rapid progression to frank empyema. Previous epidemiologic studies have indicated that empyema is increasing in prevalence, which underscores the importance of urgent diagnosis and effective drainage to improve clinical outcomes. Unfortunately, limited evidence exists to guide clinicians in selecting the ideal drainage intervention for a specific patient because of the broad variation that exists in the intrapleural extent of infection, presence of locules, comorbid features, respiratory status, and virulence of the underlying pathogen. Moreover, many patients experience delays in both the recognition of infected pleural fluid and the initiation of appropriate measures to drain the pleural space. The present review provides an update on the pathogenesis and interventional therapy of pleural infections with an emphasis on the unique role of image-guided drainage with small-bore catheters.

CT Features of Peripheral Pulmonary Carcinoid Tumors

OBJECTIVE Pulmonary carcinoid tumors are low-grade malignant neoplasms thought to arise primarily within the central airways in 85% of cases. The CT features of pulmonary carcinoid tumors that arise as solitary pulmonary nodules (SPNs) have not been well elucidated. We reviewed our experience with primary pulmonary carcinoid tumors to determine the distribution of lesions within the lung at diagnosis and to identify CT features that might aid in distinguishing these neoplasms from benign pulmonary nodules. MATERIALS AND METHODS CT scans, if available, of all patients with a primary pulmonary carcinoid tumor diagnosed by biopsy or surgical resection over the previous 15 years were reviewed. The CT scans were reviewed for the following features: lesion location; order of bronchus involved; lesion size, contour, and density; contrast enhancement; and the presence of peripheral atelectasis, hyperlucency, and bronchiectasis. We defined central lesions as those involved with a segmental or larger bronchus. Subsegmental bronchial involvement and tumors surrounded by lung parenchyma without direct airway involvement were defined as peripheral lesions. The final pathologic diagnosis for all cases was confirmed by review of cytologic or histologic specimens. RESULTS Twenty-eight carcinoid tumors were identified in 28 patients: 24 typical carcinoids and four atypical carcinoids. The study group was composed of 23 females and five males with a mean age of 52.4 years (range, 14-83 years). Twelve of the 28 lesions (43%) were central (i.e., involved a segmental or larger bronchus), and the remaining 16 lesions (57%) were peripheral. The mean tumor diameter for the 16 peripheral tumors was 14 mm (range, 9-28 mm); the majority (14/16, 88%) had a lobulated contour. Of six peripheral lesions with unenhanced and contrast-enhanced CT nodule enhancement studies, the mean maximal enhancement was 55.2 HU (range, 34-73 HU). Thirteen of the 16 peripheral carcinoid tumors (81%) involved a subsegmental bronchus, with 10 (63%) showing peripheral hyperlucency, bronchiectasis, or atelectasis. CONCLUSION In our series, primary pulmonary carcinoid tumors presenting as peripheral SPNs were more common than central endobronchial lesions in contrast to the published literature. The CT features of peripheral carcinoid tumors presenting as SPNs that suggest the diagnosis include lobulated nodules of high attenuation on contrast-enhanced CT; nodules that densely enhance with contrast administration; the presence of calcification; subsegmental airway involvement on thin-section analysis; and nodules associated with distal hyperlucency, bronchiectasis, or atelectasis.

Imaging Evaluation of the Solitary Pulmonary Nodule

The solitary pulmonary nodule (SPN) is a common diagnostic problem facing the pulmonologist. The incidence of SPNs is increasing primarily because of the increasing use of multidetector CT scanning for the evaluation of chest disease. This article reviews the radiologic assessment of the SPN, with a focus on thin-section CT, positron emission tomography, and CT-guided transthoracic needle biopsy in the characterization of SPNs. The incorporation of clinical factors, local practice patterns and expertise, and access to technology will guide the diagnostic evaluation in a given patient. An evidence-based diagnostic algortihm for SPN evaluation will be proposed.

INTERVENTIONAL TECHNIQUES IN THE THORAX

Transthoracic needle biopsy (TNB) has become the diagnostic procedure of choice in evaluation of focal chest lesions. Both advances in cross-sectional image guidance and cytopathologic techniques allow TNB to accurately diagnose malignancy and characterize a spectrum of benign conditions. Image-guided percutaneous drainage of intrathoracic collections has developed as an extension of similar procedures in the abdomen and pelvis. The ability of CT and ultrasound to accurately detect and characterize parenchymal and pleural collections, and advances in interventional techniques and catheter design, have made percutaneous catheter drainage the treatment of choice for a variety of intrathoracic collections. This article provides an updated review of the spectrum of image-guided diagnostic and therapeutic procedures in the thorax.

CT-guided transthoracic needle biopsy in the diagnosis of sarcoidosis.

Objectives In patients with suspected sarcoidosis requiring pathologic confirmation of the presence of noncaseating granulomatous inflammation and the exclusion of alternative disorders, bronchoscopic transbronchial lung biopsy and more recently transbronchial needle aspiration of mediastinal lymph nodes have been the standard biopsy procedures in most cases. We describe our experience with computed tomography-guided transthoracic needle biopsy (CT-TNB) of mediastinal lymph nodes for the diagnosis of sarcoidosis. Materials and Methods We retrospectively reviewed our single institution experience with coaxial CT-TNB of enlarged mediastinal lymph nodes in the diagnosis of sarcoidosis. Forty-one biopsies were performed in 40 patients over a 10-year period from 1997 to 2007. Final pathologic diagnosis was obtained from record review. The type of biopsy performed (aspiration cytology, core needle biopsy for histology, or both) was recorded. The method of needle approach used was obtained from review of images obtained during biopsy and the radiology report. Complications including pneumothorax, bleeding, and need for chest tube insertion for pneumothorax drainage were recorded. Yield of cytologic versus histologic diagnosis of sarcoidosis was compared using a Fisher exact test. Results Overall diagnostic yield was 93%, with core needle biopsy having a significantly higher yield as compared with fine needle aspiration cytology (96% vs. 78%, P<0.05). Pneumothorax developed in 22%, with 5% requiring overnight catheter drainage. Conclusions CT-TNB is a safe and accurate technique in the pathologic diagnosis of sarcoidosis, particularly when core tissue specimens are obtained.

Diagnosis and management of parapneumonic effusions.

Parapneumonic effusions affect many patients and are associated with considerable morbidity and mortality. It is necessary to differentiate complicated effusions requiring intervention from uncomplicated effusions. Differentiation is achieved using clinical, pleural fluid, and imaging parameters. Intervention takes the form of blind catheter placement and drainage, image-guided catheter placement and drainage, and surgical decortication [video-assisted thoracoscopic surgery (VATS) or open thoracotomy]. Image-guided drainage and management of complicated effusions in adults and pediatric patients are safe and highly effective in select patients. The use of intrapleural fibrinolytic agents to facilitate resolution of complicated effusions is widespread and considered effective by many despite a lack of conclusive data supporting this method. We propose an algorithmic approach to patients with parapneumonic effusions and advocate image-guided drainage and management in patients likely to benefit from this treatment.