Darin White

The use of pretest probability increases the value of high-resolution CT in diagnosing usual interstitial pneumonia

Background Recent studies have suggested that non-definitive patterns on high-resolution CT (HRCT) scan provide sufficient diagnostic specificity to forgo surgical lung biopsy in the diagnosis of idiopathic pulmonary fibrosis (IPF). The objective of this study was to determine test characteristics of non-definitive HRCT patterns for identifying histopathological usual interstitial pneumonia (UIP). Methods Patients with biopsy-proven interstitial lung disease (ILD) and non-definitive HRCT scans were identified from two academic ILD centres. Test characteristics for HRCT patterns as predictors of UIP on surgical lung biopsy were derived and validated in independent cohorts. Results In the derivation cohort, 64/385 (17%) had possible UIP pattern on HRCT; 321/385 (83%) had inconsistent with UIP pattern. 113/385 (29%) patients had histopathological UIP pattern in the derivation cohort. Possible UIP pattern had a specificity of 91.2% (95% CI 87.2% to 94.3%) and a positive predictive value (PPV) of 62.5% (95% CI 49.5% to 74.3%) for UIP pattern on surgical lung biopsy. The addition of age, sex and total traction bronchiectasis score improved the PPV. Inconsistent with UIP pattern demonstrated poor PPV (22.7%, 95% CI 18.3% to 27.7%). HRCT pattern specificity was nearly identical in the validation cohort (92.7%, 95% CI 82.4% to 98.0%). The substantially higher prevalence of UIP pattern in the validation cohort improved the PPV of HRCT patterns. Conclusions A possible UIP pattern on HRCT has high specificity for UIP on surgical lung biopsy, but PPV is highly dependent on underlying prevalence. Adding clinical and radiographic features to possible UIP pattern on HRCT may provide sufficient probability of histopathological UIP across prevalence ranges to change clinical decision-making.

Pulmonary nodule characterization, including computer analysis and quantitative features

Pulmonary nodules are commonly detected in computed tomography (CT) chest screening of a high-risk population. The specific visual or quantitative features on CT or other modalities can be used to characterize the likelihood that a nodule is benign or malignant. Visual features on CT such as size, attenuation, location, morphology, edge characteristics, and other distinctive “signs” can be highly suggestive of a specific diagnosis and, in general, be used to determine the probability that a specific nodule is benign or malignant. Change in size, attenuation, and morphology on serial follow-up CT, or features on other modalities such as nuclear medicine studies or MRI, can also contribute to the characterization of lung nodules. Imaging analytics can objectively and reproducibly quantify nodule features on CT, nuclear medicine, and magnetic resonance imaging. Some quantitative techniques show great promise in helping to differentiate benign from malignant lesions or to stratify the risk of aggressive versus indolent neoplasm. In this article, we (1) summarize the visual characteristics, descriptors, and signs that may be helpful in management of nodules identified on screening CT, (2) discuss current quantitative and multimodality techniques that aid in the differentiation of nodules, and (3) highlight the power, pitfalls, and limitations of these various techniques.

Establishing a Chest MRI Practice and its Clinical Applications: Our Insight and Protocols

Despite its nonionizing technique and exquisite soft tissue characterization, noncardiovascular, and nonmusculoskeletal magnetic resonance imaging (MRI) of the chest has been considered impractical due to various challenges such as respiratory motion, cardiac motion, vascular pulsatility, air susceptibility, and paucity of signal in the lung. With advances in MRI, it is now possible to perform diagnostically useful and good quality MRIs of the chest, but literature on subspecialized chest MRI practices is limited. The purpose of this manuscript is to describe the rationale, nuances, and logistics that went into developing such a practice in the Division of Thoracic Radiology at our institution. The topics addressed include technical and clinical considerations, support at administrative and clinical levels, protocol development, and economic considerations compared with conventional practices. Various MRI techniques are also specifically discussed to facilitate chest MRI at other sites. Although chest MRI is used in a relatively small number of patients at this point, in certain patients, chest MRI can provide additional information to optimize medical management. A few clinical cases illustrate the quality and clinical utility of chest MRI. Given recent advances in MRI techniques, it is now an opportune time to develop a chest MRI practice.

Emphysematous changes in hypersensitivity pneumonitis: A retrospective analysis of 12 patients

Introduction Emphysema is most commonly associated with smoking but also occurs in hypersensitivity pneumonitis (HP). The aim of this study was to further explore this relationship. Methods A retrospective, computer-assisted search was performed to identify patients with HP seen at Mayo Clinic in Rochester, Minnesota, from January 1997 through February 2014. Demographic, clinical, and imaging features were analyzed. Patients were excluded if they had a smoking history of 10 pack-years or more. Results Twelve patients (9 males) with HP and computed tomographic evidence of emphysema were identified. Ten were never smokers and 2 were ex-smokers. The median age at diagnosis was 47 (range, 29–77) years; median symptom duration was 2.2 (range, 0.2–13.4) years. The most common presenting symptoms were dyspnea (83%) and cough (67%). On pulmonary function testing, 6 patients (50%) had a restrictive defect, 2 (17%) had airflow obstruction, and 4 (33%) had an isolated reduction in diffusing capacity of lung for carbon monoxide. The severity of emphysema ranged from mild to severe to focal bullae. All patients had chronic hypersensitivity pneumonitis (CHP). Centrilobular emphysema was most commonly seen with coexistent paraseptal emphysema in 5 patients. Emphysema was most frequent in the upper lung but could be seen in any lobe. Conclusion Emphysema can occur in patients with CHP independently of smoking history and exposure to specific types of antigens. Emphysematous changes seem to progress at a slower pace compare to reticulations/fibrosis.

The breadth of the diaphragm: Updates in embryogenesis and role of imaging

The diaphragm is an unique skeletal muscle separating the thoracic and abdominal cavities with a primary function of enabling respiration. When abnormal, whether by congenital or acquired means, the consequences for patients can be severe. Abnormalities that affect the diaphragm are often first detected on chest radiographs as an alteration in position or shape. Cross-sectional imaging studies, primarily CT and occasionally MRI, can depict structural defects, intrinsic and adjacent pathology in greater detail. Fluoroscopy is the primary radiologic means of evaluating diaphragmatic motion, though MRI and ultrasound also are capable of this function. This review provides an update on diaphragm embryogenesis and discusses current imaging of various abnormalities, including the emerging role of three-dimensional printing in planning surgical repair of diaphragmatic derangements.

Pulmonary manifestations of Q fever: analysis of 38 patients

Background Lung involvement in both acute and chronic Q fever is not well described with only a few reported cases of pseudotumor or pulmonary fibrosis in chronic Q fever. The aim of this study was to better understand the pulmonary manifestations of Q fever. Methods We conducted a retrospective cohort study of patients with diagnosis of Q fever at Mayo Clinic Rochester. A total of 69 patients were initially identified between 2001 and 2014. Thirty-eight patients were included in this study as 3 were pediatric patients, 20 did not meet serologic criteria for Q fever, and 8 did not have imaging available at time of initial diagnosis. Descriptive analysis was conducted using JMP software. Results The median age was 57 years [interquartile range (IQR) 43, 62], 84% from the Midwest, and 13% worked in an occupation involving animals. The most common presentation was fevers (61%). Respiratory symptoms, such as cough, were noted in only 4 patients (11%). Twelve patients (29%) had abnormal imaging studies attributed to Q fever. Three patients (25%) with acute Q fever had findings of consolidation, lymphadenopathy, pleural effusions, and nonspecific pulmonary nodules. Radiographic findings of chronic Q fever were seen in 9 patients (75%) and included consolidation, ground-glass opacities, pleural effusions, lymphadenopathy, pulmonary edema, and lung pseudotumor. Conclusions Our results demonstrate that pulmonary manifestations are uncommon in Q fever but include cough and consolidation for acute Q fever and radiographic findings of pulmonary edema with pleural effusions, consolidation, and pseudotumor in those with chronic Q fever.

Estimation of Observer Performance for Reduced Radiation Dose Levels in CT. Eliminating Reduced Dose Levels That Are Too Low Is the First Step

RATIONALE AND OBJECTIVES This study aims to estimate observer performance for a range of dose levels for common computed tomography (CT) examinations (detection of liver metastases or pulmonary nodules, and cause of neurologic deficit) to prioritize noninferior dose levels for further analysis. MATERIALS AND METHODS Using CT data from 131 examinations (abdominal CT, 44; chest CT, 44; head CT, 43), CT images corresponding to 4%-100% of the routine clinical dose were reconstructed with filtered back projection or iterative reconstruction. Radiologists evaluated CT images, marking specified targets, providing confidence scores, and grading image quality. Noninferiority was assessed using reference standards, reader agreement rules, and jackknife alternative free-response receiver operating characteristic figures of merit. Reader agreement required that a majority of readers at lower dose identify target lesions seen by the majority of readers at routine dose. RESULTS Reader agreement identified dose levels lower than 50% and 4% to have inadequate performance for detection of hepatic metastases and pulmonary nodules, respectively, but could not exclude any low dose levels for head CT. Estimated differences in jackknife alternative free-response receiver operating characteristic figures of merit between routine and lower dose configurations found that only the lowest dose configurations tested (ie, 30%, 4%, and 10% of routine dose levels for abdominal, chest, and head CT examinations, respectively) did not meet criteria for noninferiority. At lower doses, subjective image quality declined before observer performance. Iterative reconstruction was only beneficial when filtered back projection did not result in noninferior performance. CONCLUSION Opportunity exists for substantial radiation dose reduction using existing CT technology for common diagnostic tasks.

Rapidly Appearing Sclerotic Vertebral Lesions in a Patient With an Infiltrative Mediastinal Mass

A 48-year-old, previously healthy man presented with a 3-month history of worsening cough, 10-poundweight loss, andfatigue.Hisphysicalexaminationwasunremarkable.Chest radiography identifiedapredominantlyanteriormediastinalmass.Contrast-enhancedcomputed tomography (CT)demonstrateda large infiltrativemediastinalmass involving theanterior and middle mediastinum associated with airway narrowing and severe compression of and probable invasionof thesuperiorvenacava (SVC)andcompleteobstruction of the left brachiocephalic vein (BCV). Laboratory studies revealed a normocytic anemia andneutrophilia. The patientwas referred to a pulmonologist and underwent flexible bronchoscopywith endobronchial ultrasound-guided biopsy. Pathologic review demonstrated an adenocarcinomawith signet-ring features. Seventeendays following the initial CT, thepatient presented to theemergencydepartmentwithpleuritic chest pain and shortness of breath. SubsequentCTpulmonary angiographyperformedwith intravenous (IV) contrast injectionvia the left antecubital fossa revealed nopulmonaryembolismbutdemonstrated slightprogressionof themass aswell asmultiple newscleroticvertebral lesions involvingtheposteriorvertebralbodiesandposteriorelements (Figure). Quiz at jamaoncology.com Sagittal view A