Phillip M. Boiselle

Multidetector CT Evaluation of Congenital Lung Anomalies

Congenital lung anomalies vary widely in their clinical manifestation and imaging appearance. Although radiographs play a role in the incidental detection and initial imaging evaluation in patients with clinical suspicion of congenital lung anomalies, cross-sectional imaging such as computer tomography (CT) is frequently required for confirmation of diagnosis, further characterization, and preoperative evaluation in the case of surgical lesions. Recently, with the development and widespread availability of multidetector CT scanners, CT has assumed a greater role in the noninvasive evaluation of congenital lung anomalies. The combination of fast speed, high spatial resolution, and enhanced quality of multiplanar reformation and three-dimensional reconstructions makes multidetector CT an ideal noninvasive method for evaluating congenital lung anomalies. In this article, the authors review the multidetector CT technique for evaluation of congenital lung anomalies. Important clinical aspects, characteristic imaging features, and key points that allow differentiation among various anomalies are highlighted for a variety of common and uncommon conditions.

CT and MRI in Diseases of the Aorta

OBJECTIVE This review focuses on the role of CT and MRI in the diagnosis, follow-up, and surgical planning of aortic aneurysms and acute aortic syndromes, including aortic dissection, intramural hematoma, and penetrating aortic ulcer. It also provides a systematic approach to the definition, causes, natural history, and imaging principles of these diseases. CONCLUSION An understanding of the pathophysiology, natural history, and imaging features is the key to successful diagnosis and appropriate management of patients with these aortic diseases.

An Official American Thoracic Society/Society of Thoracic Radiology Clinical Practice Guideline: Evaluation of Suspected Pulmonary Embolism In Pregnancy

BACKGROUND Pulmonary embolism (PE) is a leading cause of maternal mortality in the developed world. Along with appropriate prophylaxis and therapy, prevention of death from PE in pregnancy requires a high index of clinical suspicion followed by a timely and accurate diagnostic approach. METHODS To provide guidance on this important health issue, a multidisciplinary panel of major medical stakeholders was convened to develop evidence-based guidelines for evaluation of suspected pulmonary embolism in pregnancy using the Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) system. In formulation of the recommended diagnostic algorithm, the important outcomes were defined to be diagnostic accuracy and diagnostic yield; the panel placed a high value on minimizing cumulative radiation dose when determining the recommended sequence of tests. RESULTS Overall, the quality of the underlying evidence for all recommendations was rated as very low or low, with some of the evidence considered for recommendations extrapolated from studies of the general population. Despite the low-quality evidence, strong recommendations were made for three specific scenarios: performance of chest radiography (CXR) as the first radiation-associated procedure; use of lung scintigraphy as the preferred test in the setting of a normal CXR; and performance of computed-tomographic pulmonary angiography (CTPA) rather than digital subtraction angiography (DSA) in a pregnant woman with a nondiagnostic ventilation-perfusion (V/Q) result. DISCUSSION The recommendations presented in this guideline are based upon the currently available evidence; availability of new clinical research data and development and dissemination of new technologies will necessitate a revision and update.

Tracheobronchomalacia: Evolving role of dynamic multislice helical CT

Paired inspiratory and dynamic expiratory multislice CT imaging is a promising method for diagnosing TBM. A low-dose technique should be considered for the dynamic portion to reduce radiation exposure. Visual and quantitative analysis of the central airways provide a comprehensive assessment by allowing for the accurate diagnosis of TBM, determining its extent, assessing for predisposing conditions, and aiding selection of candidates for stent placement or tracheoplasty procedures. This technique can also be helpful for assessing response of airway dynamics following therapeutic intervention.

Tracheal Collapsibility in Healthy Volunteers during Forced Expiration: Assessment with Multidetector CT

PURPOSE To assess forced expiratory tracheal collapsibility in healthy volunteers by using multidetector computed tomography and to compare the results with the current diagnostic criterion for tracheomalacia. MATERIALS AND METHODS An institutional review board approved this HIPAA-compliant study. After informed consent was obtained, 51 healthy volunteers (age range, 25-75 years) with normal spirometry results and no history of smoking or risk factors for tracheomalacia were prospectively studied. Volunteers were imaged with a 64-detector row scanner, with spirometric monitoring at total lung capacity and during forced exhalation, with 40 mAs, 120 kVp, and 0.625-mm detector collimation. Cross-sectional area and sagittal and coronal diameters of the trachea were measured 1 cm above the aortic arch and 1 cm above the carina. The percentage of expiratory collapse, the reduction in sagittal and coronal diameters, and the number of participants exceeding the current diagnostic criterion (>50% expiratory reduction in cross-sectional area) for tracheomalacia were calculated. RESULTS The final study population included 25 men and 26 women (mean age, 50 years). The mean percentage of expiratory reduction in tracheal lumen cross-sectional area was 54.34% +/- 18.6 (standard deviation) in the upper trachea and 56.14% +/- 19.3 in the lower trachea. Forty (78%) participants exceeded the current diagnostic criterion for tracheomalacia in the upper and/or lower trachea. Decreases in cross-sectional area of the upper and lower trachea correlated well with decreases in sagittal (r = 0.807 and 0.688, respectively) and coronal (r = 0.779 and 0.751, respectively) diameters (P < .001 for each correlation). CONCLUSION Healthy volunteers demonstrate a wide range of forced expiratory tracheal collapse, frequently exceeding the current diagnostic criterion for tracheomalacia.

Relapsing Polychondritis and Airway Involvement

OBJECTIVE To assess the prevalence and characteristics of airway involvement in relapsing polychondritis (RP). METHODS Retrospective chart review and data analysis of RP patients seen in the Rheumatology Clinic and the Complex Airway Center at Beth Israel Deaconess Medical Center from January 2004 through February 2008. RESULTS RP was diagnosed in 145 patients. Thirty-one patients had airway involvement, a prevalence of 21%. Twenty-two patients were women (70%), and they were between 11 and 61 years of age (median age, 42 years) at the time of first symptoms. Airway symptoms were the first manifestation of disease in 17 patients (54%). Dyspnea was the most common symptom in 20 patients (64%), followed by cough, stridor, and hoarseness. Airway problems included the following: subglottic stenosis (n = 8; 26%); focal and diffuse malacia (n = 15; 48%); and focal stenosis in different areas of the bronchial tree in the rest of the patients. Twelve patients (40%) required and underwent intervention including balloon dilatation, stent placement, tracheotomy, or a combination of the above with good success. The majority of patients experienced improvement in airway symptoms after intervention. One patient died during the follow-up period from the progression of airway disease. The rest of the patients continue to undergo periodic evaluation and intervention. CONCLUSION In this largest cohort described in the English language literature, we found symptomatic airway involvement in RP to be common and at times severe. The nature of airway problems is diverse, with tracheomalacia being the most common. Airway intervention is frequently required and in experienced hands results in symptom improvement.

Dynamic expiratory volumetric CT imaging of the central airways: Comparison of standard-dose and low-dose techniques

RATIONALE AND OBJECTIVES Investigators in this study compared standard-dose and low-dose inspiratory and expiratory computed tomographic (CT) images with regard to their usefulness for measuring the tracheal lumen in patients with or without tracheobronchomalacia (TBM). MATERIALS AND METHODS; Hospital records were reviewed to identify 10 consecutive patients with bronchoscopically proved TBM and 10 control subjects without TBM who underwent paired volumetric inspiratory and dynamic expiratory examinations with multisection CT. A low-dose (40-80 mA) technique was used for dynamic expiratory CT in 14 (70%) of the 20 subjects, and a standard dose (240-280 mA) was used in the remaining six (30%). All images were reviewed in a randomized, blinded fashion by two observers, who measured the tracheal lumen to determine the presence of TBM by consensus. The degree of confidence in measuring the tracheal lumen was graded on a four-point scale from 0(no confidence) to 3 (highest level of confidence), also by consensus of the two observers. Statistical analysis for differences in confidence level was performed with the Mann-Whitney U test. The image noise level was assessed by measuring the standard deviation of the presternal soft tissue, and statistical analysis for differences in noise level was performed with the t test. RESULTS The level of confidence in tracheal lumen measurement was high, regardless of respiratory phase and dose (inspiratory mean, 2.9; median, 3; range, 2-3; expiratory low-dose mean, 2.6; median, 3; range, 2-3; expiratory standard-dose mean, 2.8; median, 3; range, 2-3). There was no significant difference in confidence level between standard- and low-dose techniques (P = .53). Excessive central airway collapse (expiratory reduction in cross-sectional diameter, > 50%) was seen in all 10 patients with TBM and in none of the control subjects. CONCLUSION The acquisition of paired inspiratory and dynamic expiratory images with multisection helical CT is a promising method for diagnosing TBM. The low-dose technique performs as well as the standard-dose technique for the dynamic expiratory phase, with a similar degree of confidence for measuring the tracheal lumen.

Tracheobronchoplasty for Severe Tracheobronchomalacia: A Prospective Outcome Analysis

RATIONALE Central airway stabilization with silicone stents can improve respiratory symptoms in patients with severe symptomatic tracheobronchomalacia (TBM) but is associated with a relatively high rate of complications. Surgery with posterior tracheobronchial splinting using a polypropylene mesh has also been used for this condition but to date has not been evaluated prospectively and objectively for patient outcomes. OBJECTIVES To evaluate the effect of surgical tracheobronchoplasty on symptoms, functional status, quality of life, lung function, and exercise capacity in patients with severe and symptomatic TBM. METHODS A prospective observational study in which baseline measurements were compared to those obtained 3 months after surgical tracheobronchoplasty. MEASUREMENTS AND MAIN RESULTS Of 104 referred patients to our complex airway center for severe TBM, 77 had baseline measurements. Of this group, 57 patients had severe malacia and underwent stent placement for central airway stabilization. Of those, 37 patients reported improvement in respiratory symptoms and 35 were considered for surgical tracheobronchoplasty. Two patients were excluded from surgery for medical reasons. Median age was 61 years (range, 39 to 83 years), 20 patients were men, 11 patients (31%) had COPD, 9 patients (26%) had asthma, and 4 patients (11%) had Mounier-Kuhn syndrome. Thirty-three patients (94%) presented with severe dyspnea, 26 patients (74%) with uncontrollable cough, and 18 patients (51%) reported recurrent pulmonary infections. Two patients (3%) presented with respiratory failure requiring mechanical ventilation. After surgery, quality of life scores improved in 25 of 31 patients (p < 0.0001), dyspnea scores improved in 19 of 26 patients (p = 0.007), functional status scores improved in 20 of 31 patients (p = 0.003), and mean exercise capacity improved in 10 patients (p = 0.012). CONCLUSIONS In experienced hands, surgical central airway stabilization with posterior tracheobronchial splinting using a polypropylene mesh improves respiratory symptoms, health-related quality of life, and functional status in highly selected patients with severe symptomatic TBM.

American Thoracic Society Documents: An Official American Thoracic Society/Society of Thoracic Radiology Clinical Practice Guideline—Evaluation of Suspected Pulmonary Embolism in Pregnancy

BACKGROUND Pulmonary embolism (PE) is a leading cause of maternal mortality in the developed world. Along with appropriate prophylaxis and therapy, prevention of death from PE in pregnancy requires a high index of clinical suspicion followed by a timely and accurate diagnostic approach. METHODS To provide guidance on this important health issue, a multidisciplinary panel of major medical stakeholders was convened to develop evidence-based guidelines for evaluation of suspected pulmonary embolism in pregnancy using the Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) system. In formulation of the recommended diagnostic algorithm, the important outcomes were defined to be diagnostic accuracy and diagnostic yield; the panel placed a high value on minimizing cumulative radiation dose when determining the recommended sequence of tests. RESULTS Overall, the quality of the underlying evidence for all recommendations was rated as very low or low with some of the evidence considered for recommendations extrapolated from studies of the general population. Despite the low quality evidence, strong recommendations were made for three specific scenarios: performance of chest radiography (CXR) as the first radiation-associated procedure; use of lung scintigraphy as the preferred test in the setting of a normal CXR; and performance of computed-tomographic pulmonary angiography (CTPA) rather than digital subtraction angiography (DSA) in a pregnant woman with a nondiagnostic ventilation-perfusion (V/Q) result. DISCUSSION The recommendations presented in this guideline are based upon the currently available evidence; availability of new clinical research data and development and dissemination of new technologies will necessitate a revision and update.

Swine-Origin Influenza A (H1N1) Viral Infection in Children: Initial Chest Radiographic Findings

PURPOSE To evaluate initial chest radiographic findings of swine-origin influenza A (S-OIV) (also known as H1N1) viral infection in children. MATERIALS AND METHODS This was an institutional review board-approved, HIPAA-compliant retrospective study of 108 patients who had microbiologically confirmed S-OIV infection and available initial chest radiographs obtained between April 2009 and October 2009. The final study group was divided on the basis of clinical course (group 1, outpatients without hospitalization [n = 72]; group 2, inpatients with brief hospitalization [n = 22]; group 3, inpatients with intensive care unit admission [n = 14]). Two pediatric radiologists blinded to patient group and lung parenchymal, airway, pleural, hilar, and mediastinal abnormalities systematically reviewed initial chest radiographs. Lung parenchyma and airways were evaluated for pattern (peribronchial markings, consolidation, and ground-glass, nodular, and reticular opacity), distribution, and extent of abnormalities. Radiographs were assessed for presence of pleural effusions or lymphadenopathy. Medical records were reviewed for underlying medical conditions and patient outcomes. Association between frequency of underlying medical conditions and clinical course of S-OIV infection among study groups was evaluated with the Pearson chi(2) test. RESULTS The frequency of normal chest radiographs was significantly higher in group 1 (n = 48) than in groups 2 (n = 1) and 3 (n = 0) (P < .001, Pearson chi(2) test). Among patients with abnormal radiographs, the most common finding in group 1 was prominent peribronchial markings with hyperinflation (n = 17), whereas the most common findings in groups 2 (n = 12) and 3 (n = 12) were bilateral, symmetric, and multifocal areas of consolidation, often associated with ground-glass opacities. Nodular opacities, reticular opacities, pleural effusion, or lymphadenopathy were not observed in any patient. An increased frequency of underlying medical conditions was observed in patients with greater severity of illness due to S-OIV infection (group 3, 71%; group 2, 59%; group 1, 31%) (P = .003, Pearson chi(2) test). All 84 patients with available follow-up information have fully recuperated from S-OIV infection. CONCLUSION Initial chest radiographs in children with a mild and self-limited clinical course of S-OIV infection are often normal, but they may demonstrate prominent peribronchial markings with hyperinflation. Bilateral, symmetric, and multifocal areas of consolidation, often associated with ground-glass opacities, are the predominant radiographic findings in pediatric patients with a more severe clinical course of S-OIV infection. (c) RSNA, 2009.