Faculty Bibliography

Recent technologic advances in multidetector computed tomography have allowed the performance of simultaneous acquisition dual-energy computed tomography (DECT). The advantages of this new technique include simultaneous visualization of lower voltage tube images with improved iodine conspicuity and the performance of material specific imaging, which attempts to differentiate specific materials in the generated images. In this article, we review the concepts and physical principles of DECT using congenital thoracic abnormalities as a substrate for depicting the versatility of DECT

Pulmonary nodule characterization is currently being redefined as new clinical, radiologic, and pathologic data are reported, necessitating a reevaluation of the clinical management, especially of subsolid nodules. These are now known to frequently, although not invariably, fall into the spectrum of peripheral adenocarcinomas of the lung. Strong correlation between the Noguchi histologic classification and computed tomographic (CT) appearances of these lesions, in particular, has been reported. Serial CT findings have further documented that stepwise progression of lesions with ground-glass opacity, manifested as an increase in size or the appearance and/or subsequent increase of solid components, does occur in a select subset of patients. As a consequence, recognition of the potential association between subsolid nodules and peripheral adenocarcinomas requires a review of current guidelines for the management of these lesions, further necessitated by a differential diagnosis that includes benign lesions such as focal inflammation, focal fibrosis, and organizing pneumonia. Specific issues that need to be addressed are the need for consensus regarding an appropriate CT classification, methods for precise measurement of subsolid nodules, including the extent of both ground-glass and solid components, as well as accurate assessment of the growth rates as means for predicting malignancy and prognosis. It is anticipated that interim guidelines may serve to standardize our current management of these lesions, pending further clarification of their natural history. (c) RSNA, 2009

Sarcoidosis is a multisystem granulomatous disease of unknown etiology that usually affects the lungs. Although flexible fiberoptic bronchoscopy with transbronchial lung biopsy (TBBx) has a high diagnostic yield in patients with pulmonary sarcoidosis, variously ranging from 40 to 90%, more invasive procedures often prove necessary. We report two cases of successful diagnosis of pulmonary sarcoidosis using a new technique that may increase the accuracy of TBBx. Previously described for diagnosis of peripheral lung cancer, this technique relies on real-time virtual bronchoscopic guidance to biopsy preselected peripheral areas of the lung preferentially affected by the disease using a pediatric bronchoscope. In each case, while procedures were performed under direct CT guidance allowing precise confirmation of the tip of the biopsy catheter, it is anticipated that this technique will be primarily used as a guide to bronchoscopic biopsies without the need for direct CT guidance, thus increasing routine utilization of multidetector low-dose high-resolution CT to improve histologic diagnosis.

PURPOSE: To describe computed tomography (CT) findings of transient pulmonary eosinophilia (TPE) incidentally found on low-dose CT (LDCT) and to identify suggestive CT features helpful in initial diagnosis. MATERIALS AND METHODS: We retrospectively reviewed LDCT scans in 40 individuals who met criteria for having TPE. There were 35 men and 5 women (age range, 32-62 years; mean, 48.5 +/- 9 years). Initial LDCT scans were assessed as either (a) nodules, further characterized as either solid, solid associated with a halo of ground-glass attenuation, or pure ground-glass lesions as well as by number, size, and location or (b) ill-defined foci of parenchymal consolidation. RESULTS: A range of focal parenchymal abnormalities (n = 78) were identified-both single (48%) and multiple (52%). Most of these proved to be either solid nodules with discrete ground-glass halos (72%), or poorly defined solid nodules exhibiting a variety of differing morphologies (24%). Ill-defined foci of consolidation were noted in 3 cases (4%). The lesions were predominantly located in the lower lung zone (73%) with peripheral distribution (92%). CONCLUSIONS: Transient pulmonary eosinophilia most often manifests as solid nodules with associated ground-glass halos. Awareness of TPE should serve to limit the number of mistaken diagnoses of early lung cancer

Although to date, the major impetus for the development of computer-assisted diagnosis (CAD) has been the detection of pulmonary nodules, CAD should properly be viewed as a potential tool for assisting radiologic interpretation of the entire gamut of chest diseases, including not just enhanced detection of disease but also characterization and quantification, ideally leading to improved patient management. The use of CAD to improve visualization of the airways using advanced computer techniques, including sophisticated methods for obtaining 3-dimensional segmentation of the central airways and, in particular, the development of virtual bronchoscopy has been recently studied. In this paper, the authors review the development of a specific series of CAD applications enabling automated identification and characterization of chronically inflamed airways. The advantages to the use of computer methodologies to quantify peripheral airway disease include reproducible visualization methods to display the location, severity, and extent of airway dilatation, bronchial wall thickening, and the presence of mucoid impacted airways. Currently, a number of semiquantitative global scoring systems have been proposed to assess disease extent and severity in patients with bronchiectasis. Unfortunately, with the exception of patients with cystic fibrosis, these are rarely if ever employed, largely owing to the considerable inconvenience of measuring individual airway dimensions and computing a global score. It is apparent that for this specific purpose, CAD may be ideally suited. Automated staging allows for more complete assessment of the entire bronchial tree while providing improved standardization and eliminating an otherwise tedious and time-consuming task

PURPOSE OF REVIEW: The management of asthma is guided by clinical symptoms, physiological measurements, and response to therapy. Recent advances in computed tomography imaging promise to add a new dimension to our diagnostic armamentarium. Accurate representation of airway pathology, visualized by high-resolution chest computed tomography scan, helps to improve the understanding of the pathophysiology of asthma. In addition, findings on computed tomography may help to guide therapies for asthma. As radiologists provide us with sophisticated modalities that may also have a bearing on treatment, clinicians should stay abreast of this evolving noninvasive technology. RECENT FINDINGS: This review focuses on the findings seen on computed tomography imaging as related to asthma. Airway wall thickness is discussed and how it relates to disease progression and pulmonary function test. In addition, indirect findings such as bronchial dilatation and mosaic attenuation, both consequences of air-trapping, are discussed. Other investigational tools, such as endobronchial ultrasound and positron emission tomography, are described. SUMMARY: New modalities in radiology hold promise to aid in the understanding and treatment of small-airway disease. Although still considered investigational modalities, research evidence is fast accumulating. It behooves the clinician to have a heightened awareness regarding further advancements in this field.

BACKGROUND: Pulmonary nodules are spherical radiographic opacities that measure up to 30 mm in diameter. Nodules are extremely common in clinical practice and challenging to manage, especially small, 'subcentimeter' nodules. Identification of malignant nodules is important because they represent a potentially curable form of lung cancer. METHODS: We developed evidence-based clinical practice guidelines based on a systematic literature review and discussion with a large, multidisciplinary group of clinical experts and other stakeholders. RESULTS: We generated a list of 29 recommendations for managing the solitary pulmonary nodule (SPN) that measures at least 8 to 10 mm in diameter; small, subcentimeter nodules that measure < 8 mm to 10 mm in diameter; and multiple nodules when they are detected incidentally during evaluation of the SPN. Recommendations stress the value of risk factor assessment, the utility of imaging tests (especially old films), the need to weigh the risks and benefits of various management strategies (biopsy, surgery, and observation with serial imaging tests), and the importance of eliciting patient preferences. CONCLUSION: Patients with pulmonary nodules should be evaluated by estimation of the probability of malignancy, performance of imaging tests to characterize the lesion(s) better, evaluation of the risks associated with various management alternatives, and elicitation of patient preferences for treatment

Computed tomography (CT) images of the lungs provide high resolution views of the airways. Quantitative measurements such as lumen diameter and wall thickness help diagnose and localize airway diseases, assist in surgical planning, and determine progress of treatment. Automated quantitative analysis of such images is needed due to the number of airways per patient. We present an approach involving dynamic programming coupled with boundary-specific cost functions that is capable of differentiating inner and outer borders. The method allows for precise delineation of the inner lumen and outer wall. The results are demonstrated on synthetic data, evaluated on human datasets compared to human operators, and verified on phantom CT scans to sub-voxel accuracy

BACKGROUND: S-Adenosylmethionine (AdoMet) is a major methyl donor for transmethylation reactions and propylamine donor for the biosynthesis of polyamines in biological systems, and therefore may play a role in lung cancer development. We hypothesized that AdoMet levels were elevated in patients with lung cancer and may prove useful as a biomarker for early lung cancer. METHODS: High-performance liquid chromatography was used to analyze plasma AdoMet levels in triplicate samples from 68 patients. This included 13 patients with lung cancer, 33 smokers with benign lung disease, and 22 healthy nonsmokers. The three groups of subjects were compared with respect to the distribution of demographic and disease characteristics and AdoMet levels. Distributions were examined using summary statistics and box plots, and nonparametric analysis of variance procedures. RESULTS: Serum AdoMet levels were elevated in patients with lung cancer as compared to smokers with benign lung disorders and healthy nonsmokers. There were no significant correlations between AdoMet levels and tumor cell types, nodule size, or other demographic variables. CONCLUSIONS: Our data demonstrate that plasma levels of AdoMet are significantly elevated in patients with lung cancer. Plasma AdoMet levels may prove to be a useful tool for the diagnosis of early lung cancer, in combination with chest CT. Registered at: clinicaltrials.gov (NCT00301119)

OBJECTIVE: The aim of this study was to determine the benefit of lower extremity CT venography (CTV) with pulmonary CT angiography (CTA) for diagnosing thromboembolic (TE) disease. SUBJECTS AND METHODS: Reports of all CTAs and CTVs over a 3-year interval (Group I) and CTAs, CTVs, and lower extremity Doppler ultrasounds (US) over a 1 1/2-year subset (Group II) were reviewed. Patient population was inpatients and emergency department patients who were assessed for pulmonary embolism (PE) and deep venous thrombosis (DVT) at a tertiary care hospital. Reported results for CTA or CTV were categorized as positive (CTA(P), CTV(P)), negative (CTA(N), CTV(N)), or indeterminate for PE or DVT. When CTV and US results were discrepant, medical records were reviewed for clinical management. Additional benefit of CTV was assessed by chi-square analysis. RESULTS: In Group I, 737 (81.1%) of 909 CTAs from combined CTA/CTV studies were negative. The diagnosis rate of TE disease increased from 13.0% to 17.3% with the addition of CTV(P)s (P=.01). Of the 119 cases in Group II undergoing combined CTA, CTV, and US, CTV and US were both positive in eight and both negative in 88. Of the seven discordant CTVs and USs with clinical follow-up, five CTVs were positive while USs were negative, three of which were treated clinically for TE disease, while two were considered falsely positive. As CTA also proved positive in one of the three, CTV therefore affected management in two of these five cases and increased the rate of thromboembolism diagnosis from 21.0% to 22.6%; however, this was not significant (P>.05). Two CTV(N)s were managed as false negatives. CONCLUSIONS: The combined use of CTA and CTV significantly increases the rate of TE disease over CTA alone. In cases in which ultrasound is performed, however, there is no significant advantage to performing combined CTA/CTV studies