Estimating the Clinical Impact of Photon-Counting-Detector CT in Diagnosing Usual Interstitial Pneumonia.

OBJECTIVE: The aim of this study was to evaluate the clinical impact of a higher spatial resolution, full field-of-view investigational photon-counting detector computed tomography (PCD-CT) on radiologist confidence in imaging findings and diagnosis of usual interstitial pneumonia (UIP) compared with conventional energy-integrating detector CT (EID-CT). MATERIALS AND METHODS: Patients suspected of interstitial lung disease were scanned on a PCD-CT system after informed consent and a clinically indicated EID-CT. In 2 sessions, 3 thoracic radiologists blinded to clinical history and scanner type evaluated CT images of the right and left lungs separately on EID- or PCD-CT, reviewing each lung once/session, rating confidence in imaging findings of reticulation, traction bronchiectasis, honeycombing, ground-glass opacities (GGOs), mosaic pattern, and lower lobe predominance (100-point scale: 0-33, likely absent; 34-66, indeterminate; 67-100, likely present). Radiologists also rated confidence for the probability of UIP (0-20, normal; 21-40, inconsistent with UIP; 41-60, indeterminate UIP; 61-81; probable UIP; 81-100, definite UIP) and graded image quality. Because a confidence scale of 50 represented completely equivocal findings, magnitude score (the absolute value of confidence scores from 50) was used for analysis (higher scores were more confident). Image noise was measured for each modality. The magnitude score was compared using linear mixed effects regression. The consistency of findings and diagnosis between 2 scanners were evaluated using McNemar test and weighted κ statistics, respectively. RESULTS: A total of 30 patients (mean age, 68.8 ± 11.0 years; M:F = 18:12) underwent conventional EID-CT (median CTDI vol , 7.88 mGy) and research PCD-CT (median CTDI vol , 6.49 mGy). The magnitude scores in PCD-CT were significantly higher than EID-CT for imaging findings of reticulation (40.7 vs 38.3; P = 0.023), GGO (34.4 vs 31.7; P = 0.019), and mosaic pattern (38.6 vs 35.9; P = 0.013), but not for other imaging findings ( P ≥ 0.130) or confidence in UIP (34.1 vs 22.2; P < 0.059). Magnitude score of probability of UIP in PCD-CT was significantly higher than EID-CT in one reader (26.0 vs 21.5; P = 0.009). Photon-counting detector CT demonstrated a decreased number of indeterminate GGO (17 vs 26), an increased number of unlikely GGO (74 vs 50), and an increased number of likely reticulations (140 vs 130) relative to EID-CT. Interobserver agreements among 3 readers for imaging findings and probability of UIP were similar between PCD-CT and EID-CT (intraclass coefficient: 0.507-0.818 vs 0.601-0.848). Photon-counting detector CT had higher scores in overall image quality (4.84 ± 0.38) than those in EID-CT (4.02 ± 0.40; P < 0.001) despite increased image noise (mean 85.5 vs 36.1 HU). CONCLUSIONS: Photon-counting detector CT provided better image quality and improved the reader confidence for presence or absence of imaging findings of reticulation, GGO, and mosaic pattern with idiosyncratic improvement in confidence in UIP presence.

Derivation and validation of a prediction model for histopathologic fibrotic hypersensitivity pneumonitis.

BACKGROUND: Clinical differentiation of fibrotic hypersensitivity pneumonitis (f-HP) remains challenging given variable and overlapping presentations with other fibrotic interstitial lung disease (f-ILD). OBJECTIVE: We derived a multivariable model for predicting histopathologic f-HP to better inform multidisciplinary team discussion (MDD) diagnosis, particularly when biopsy may be unsafe or cannot be achieved. METHODS: Patients with histopathologically-defined f-HP and other overlapping f-ILD were reviewed for distinguishing clinical and radiological variables. Using elastic net logistic regression, a penalized regression approach to minimize overfitting, a clinical model built on non-invasive assessments was derived for the prediction of histopathologic f-HP. This model was then validated in an independently derived external cohort from three sites. RESULTS: The derivation and validation cohorts consisted of 248 (84 cHP and 164 other f-ILD) and 157 (82 f-HP and 75 other f-ILD) histopathologically-defined patients, respectively (total study N = 405). Variables retained from the elastic net model included age in years (regression coefficient 0.033), male sex (-1.109), positive exposure history (1.318), percent predicted forced vital capacity (-0.021), radiologic peribronchovascular axial ILD distribution (0.199), mid (-0.22) or lower lobe (-0.839) craniocaudal or patchy (0.287) ILD distribution, upper (1.188) or equivalent upper and lower lobe (0.237) traction bronchiectasis, mosaic attenuation (1.164), and centrilobular nodules (2.045). Bias corrected AUC was 0.84 (standard error = 0.02) for the derivation cohort and 0.80 (CI 0.73-0.87) for the validation cohort. CONCLUSIONS: This multivariable model demonstrated good predictive performance for delineating histopathologically-defined f-HP from other f-ILD as a means of avoiding or justifying biopsy and supporting MDD diagnostic confidence.

A Case Series of Long-Term Surgical Outcomes of Primary Pulmonary Artery Sarcomas With Opportunities for 3D-Printed Models in Surgical Planning.

There are limited data regarding the surgical management of primary pulmonary artery sarcomas (PPAS) because of their rarity and complicated diagnostic history. The objective of this study was to analyze our institution's long-term surgical management outcomes for PPAS in the absence of a care pathway. From May 1997 to June 2013, 8 patients (mean age 60.6 ± 11.8 years; range, 40-73 years; 5 women and 3 men) underwent surgical intervention for PPAS at our institution. The most common computed tomography finding was a luminal filling defect obstructing the pulmonary artery (PA), without evidence of extraluminal extension. Three patients underwent debulking/pulmonary endarterectomy alone and 5 patients underwent a more radical resection with PA patch angioplasty, PA resection and reconstruction, pulmonary valve replacement, and unilateral pneumonectomy. The mean postoperative survival in this series was 3.8 ± 3.6 years (range, 1-11.9 years), with 2 radical surgical resection patients alive at 4.9 and 11.9 years, respectively. For those patients with incomplete resection, 3-dimensional (3D) models were created to demonstrate the advantage of a preoperative guide for a more complete resection and what it would entail. Six patients had local recurrences with mean disease-free interval of 14 ± 10.9 months (range, 2 months-2.5 years), and 2 patients with re-resections had an overall postoperative survival of 2.8 and 11.9 years, respectively. In our small cohort of PPAS, patients treated with radical surgical resection had better survival. The small number of PPAS cases in this series makes proving this association unlikely but warrants consideration.

Observer Performance for Detection of Pulmonary Nodules at Chest CT over a Large Range of Radiation Dose Levels.

Background There is a wide variation in radiation dose levels that can be used with chest CT in order to detect indeterminate pulmonary nodules. Purpose To compare the performance of lower-radiation-dose chest CT with that of routine dose in the detection of indeterminate pulmonary nodules 5 mm or greater. Materials and Methods In this retrospective study, CT projection data from 83 routine-dose chest CT examinations performed in 83 patients (120 kV, 70 quality reference mAs [QRM]) were collected between November 2013 and April 2014. Reference indeterminate pulmonary nodules were identified by two nonreader thoracic radiologists. By using validated noise insertion, five lower-dose data sets were reconstructed with filtered back projection (FBP) or iterative reconstruction (IR; 30 QRM with FBP, 10 QRM with IR, 5 QRM with FBP, 5 QRM with IR, and 2.5 QRM with IR). Three thoracic radiologists circled pulmonary nodules, rating confidence that the nodule was a 5-mm-or-greater indeterminate pulmonary nodule, and graded image quality. Analysis was performed on a per-nodule basis by using jackknife alternative free-response receiver operating characteristic figure of merit (FOM) and noninferiority limit of -0.10. Results There were 66 indeterminate pulmonary nodules (mean size, 8.6 mm ± 3.4 [standard deviation]; 21 part-solid nodules) in 42 patients (mean age, 51 years ± 17; 21 men and 21 women). Compared with the FOM for routine-dose CT (size-specific dose estimate, 6.5 mGy ± 1.8; FOM, 0.86 [95% confidence interval: 0.80, 0.91]), FOM was noninferior for all lower-dose configurations except for 2.5 QRM with IR. The sensitivity for subsolid nodules at 70 QRM was 60% (range, 48%-72%) and was significantly worse at a dose of 5 QRM and lower, whether or not IR was used (P < .05). Diagnostic image quality decreased with decreasing dose (P < .001) and was better with IR at 5 QRM (P < .05). Conclusion CT images reconstructed at dose levels down to 10 quality reference mAs (size-specific dose estimate, 0.9 mGy) had noninferior performance compared with routine dose in depicting pulmonary nodules. Iterative reconstruction improved subjective image quality but not performance at low dose levels. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by White and Kazerooni in this issue.

Pulmonary nodular and cystic light chain deposition disease: A retrospective review of 10 cases.

INTRODUCTION: Light chain deposition disease (LCDD) rarely involves the lungs. We report clinical and radiologic findings of pulmonary LCDD. METHODS: We retrospectively identified patients with biopsy-proven pulmonary LCDD seen at Mayo Clinic (Rochester, Minnesota) from January 1997 through December 2018. Demographic, clinical, and imaging features were analyzed. RESULTS: We identified 10 patients with pulmonary LCDD (median age at diagnosis, 55 years; range, 39-77 years). Eight patients were women and 7 were never-smokers. Dyspnea (n = 3) and chest pain (n = 3) were the most common respiratory symptoms. Associated conditions included Sjögren syndrome (n = 6), sarcoidosis (n = 1), and limited scleroderma (n = 1). Eight patients had mucosa-associated lymphoid tissue (MALT) lymphoma. Among the 9 patients with chest computed tomography (CT) images, 8 (89%) had cysts. Cysts were predominantly distributed in the lower lung and were round or oval. All patients had multiple cysts (5 patients had 1-5 cysts, 3 had >20 cysts). The median diameter of the largest cyst was 18 mm (range, 5-68 mm). All 9 patients had solid nodules (3 had >10 nodules). Five patients had subsolid nodules. The median diameter of the largest solid nodules was 13 mm (range, 6-26 mm). Positron emission tomography-CT images were available for 8 patients. The median maximum standardized uptake value of the most avid pulmonary nodule was 2.2 (range, 1.9-6.0). Two patients died during a median follow-up of 2.3 years (range, 0.5-9.9 years). CONCLUSIONS: Pulmonary LCDD is characterized by cysts and nodules. The disease is associated with MALT lymphoma, especially in the setting of Sjögren syndrome.

Distribution of Mediastinal Lesions Across Multi-Institutional, International, Radiology Databases.

INTRODUCTION: Mediastinal lesions are uncommon; studies on their distribution are, in general, small and from a single institution. Furthermore, these studies are usually based on pathology or surgical databases and, therefore, miss many lesions that did not undergo biopsy or resection. Our aim was to identify the distribution of lesions in the mediastinum in a large international, multi-institutional cohort. METHODS: At each participating institution, a standardized retrospective radiology database search was performed for interpretations of computed tomography, positron emission tomography-computed tomography, and magnetic resonance imaging scans including any of the following terms: "mediastinal nodule," "mediastinal lesion," "mediastinal mass," or "mediastinal abnormality" (2011-2014). Standardized data were collected. Statistical analysis was performed. RESULTS: Among 3308 cases, thymomas (27.8%), benign mediastinal cysts (20.0%), and lymphomas (16.1%) were most common. The distribution of lesions varied among mediastinal compartments; thymomas (38.3%), benign cysts (16.8%), and neurogenic tumors (53.9%) were the most common lesions in the prevascular, visceral, and paravertebral mediastinum, respectively (p < 0.001). Mediastinal compartment was associated with age; patients with paravertebral lesions were the youngest (p < 0.0001). Mediastinal lesions differed by continent or country, with benign cysts being the most common mediastinal lesions in the People's Republic of China, thymomas in Europe, and lymphomas in North America and Israel (p < 0.001). Benign cysts, thymic carcinomas, and metastases were more often seen in larger hospitals, whereas lymphomas and thymic hyperplasia occurred more often in smaller hospitals (p < 0.01). CONCLUSIONS: Our study confirmed that the spectrum and frequency of mediastinal lesions depend on mediastinal compartment and age. This information provides helpful demographic data and is important when considering the differential diagnosis of a mediastinal lesion.

Efficacy of chest computed tomography prediction of the pathological TNM stage of thymic epithelial tumours.

OBJECTIVES: The aim of this study is to evaluate the efficacy of chest computed tomography (CT) to predict the pathological stage of thymic epithelial tumours (TET) using the recently introduced tumour, node and metastasis (TNM) staging with comparison to the modified Masaoka staging. METHODS: Preoperative chest CT examinations in cases of resected TET with sampled lymph nodes (2006-2016) were retrospectively reviewed by 2 thoracic radiologists and radiologically (r) staged using both staging systems. A thoracic pathologist reviewed all cases for the pathological (p) stage. Concordance between r-staging and p-staging was assessed by % agreement and unweighted kappa statistics. Associations between r-stage and p-stage with outcomes were assessed using the Cox proportional hazards regression. RESULTS: Sixty patients with TET were included (47 thymomas, 12 thymic carcinomas and 1 atypical carcinoid tumour). Sixteen patients (26.7%) had received neoadjuvant therapy. Fifty-four patients (90.0%) had complete resection. The overall agreement between the r-stage and p-stage was 66.7% (κ = 0.46) for TNM staging and 46.7% (κ = 0.30) for modified Masaoka staging. Agreement between r-assessment and p-assessment of the T, N and M components of the TNM stage was 61.7% (κ = 0.28), 86.7% (κ = 0.48) and 98.3% (κ = 0.88), respectively. CT overstaged 12 patients (20.0%) for TNM staging and 12 patients (20.0%) for modified Masaoka staging and understaged 8 (13.3%) and 20 (33.3%) patients for TNM staging modified Masaoka staging, respectively. The r-TNM staging accuracy was lower for patients with neoadjuvant therapy (50.0% with vs 72.7% without). During a median follow-up of 2.6 years (range 0.1-10.5 years), 12 patients had metastases and/or recurrence; 11 patients died (4 of disease). The r-TNM stage and modified Masaoka stage were associated with overall survival and progression-free survival (P < 0.001). CONCLUSIONS: Preoperative chest CT is able to accurately predict p-TNM stage in two-thirds of surgically resected TET, with an agreement between radiological staging and pathological staging superior to the modified Masaoka staging.

Evolution of diagnostic UIP computed tomography patterns in idiopathic pulmonary fibrosis: Disease spectrum and implications for survival.

BACKGROUND: Whether current diagnostic computed tomography (CT) patterns in idiopathic pulmonary fibrosis (IPF) represent distinct clinical phenotypes or simply temporal evolution of the same underlying radiologic process is unknown. We studied IPF patients presenting with 'possible' or 'inconsistent' usual interstitial pneumonia (UIP) CT patterns and characterized the frequency and timing of evolution to 'consistent' UIP and its effect on survival. MATERIAL AND METHODS: Consecutive IPF patients seen at our institution from 1/1/2005 through 12/31/2013 were assessed for study inclusion. Presenting and serial CT scans were reviewed by two expert radiologists. Baseline and interval clinical data were collated. RESULTS: Ninety one patients (mean age 67.4 years, 59% male) met study criteria with 'possible' and 'inconsistent' UIP CT patterns present in 58 (64%) and 33 (36%) cases, respectively. Twenty nine (32%) transitioned to a 'consistent' UIP pattern over a median of 57 months (interquartile range 33-78 months). Decline in pulmonary function was statistically significant on interval follow-up for those with or without pattern evolution, but no different between them in terms of degree. Evolution to 'consistent' UIP did not confer worse survival from the date of disease diagnosis or date of first CT with 'consistent' UIP pattern. CONCLUSIONS: A portion of IPF patients with initial 'possible' or 'inconsistent' UIP CT pattern will go on to develop 'consistent' UIP CT pattern over months to years. Despite this, there appeared to be similar risk and cause of death in those with or without pattern evolution, suggesting similar morbidity across the radiologic spectrum in IPF.

Prospective Pilot Evaluation of Radiologists and Computer-aided Pulmonary Nodule Detection on Ultra-low-Dose CT With Tin Filtration.

PURPOSE: The aim of this study was to evaluate the ability of computer-aided detection (CAD) and human readers to detect pulmonary nodules ≥5 mm using 100 kV ultra-low-dose computed tomography (ULDCT) utilizing a tin filter. MATERIALS AND METHODS: After informed consent, 55 patients prospectively underwent standard-dose chest CT (SDCT) using 120 kV followed by ULDCT using 100 kV/tin. Reference nodules ≥5 mm were identified by a thoracic radiologist using SDCT. Four thoracic radiologists marked detected nodules on SDCT and ULDCT examinations using a dedicated computer workstation. After a 6-month memory extinction, readers were shown the same ULDCT cases with all CAD markings as well as their original detections, and characterized CAD detections as true positive or false positive. RESULTS: Volume CT Dose index (CTDIvol) for SDCT and ULDCT were 5.3±2 and 0.4±0.2 mGy (P<0.0001), respectively. Forty-five reference nodules were detected in 30 patients. Reader sensitivity varied widely but similarly for SDCT (ranging from 45% to 87%) and ULDCT (45% to 83%). CAD sensitivity was 76% (34/45) for SDCT and 71% (32/45) for ULDCT. After CAD, reader sensitivity substantially improved by 19% and 18% for 2 readers, and remained nearly unchanged for the other 2 readers (0% and 2%), despite reader perception that many more nodules were identified with CAD. There was a mean of 2 false-positive CAD detections/case. CONCLUSIONS: ULDCT with 100 kV/tin reduced patient dose by over 90% without compromising pulmonary nodule detection sensitivity. CAD can substantially improve nodule detection sensitivity at ULDCT for some readers, maintaining interobserver performance.

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.

The Four Corners Sign: A Specific Imaging Feature in Differentiating Systemic Sclerosis-related Interstitial Lung Disease From Idiopathic Pulmonary Fibrosis.

PURPOSE: Differentiating between systemic sclerosis-related interstitial lung disease (SSc-ILD) and idiopathic pulmonary fibrosis (IPF) is important because of the differences in workup, prognosis, and treatment. However, there is much overlap in the appearance of these 2 entities on high-resolution computed tomography. We propose that inflammation and/or fibrosis focally or disproportionately involving the bilateral anterolateral upper lobes and posterosuperior lower lobes ["Four Corners" Sign (FCS)] is specific for SSc-ILD. MATERIALS AND METHODS: Randomized high-resolution computed tomography studies from 74 IPF and 73 SSc-ILD cases were evaluated by 2 thoracic radiologists blinded to all patient data. For each case the reviewers noted whether the FCS was present and assigned a confidence level on the basis of a 7-point Likert scale. The same process was then performed on a randomized external validation group of 42 SSc-ILD and 42 IPF cases. RESULTS: For Likert scores of 6 or 7 ("mostly agree" or "entirely agree" that the FCS is present, respectively) the sensitivity in SSc was 16.4% (95% confidence interval, 9.7%, 26.6%), specificity 100.0% (95% confidence interval, 95.1%, 100.0%). There was a significant association between a confidently present FCS and SSc compared with a confidently present FCS and IPF (P=0.0003). Analysis on an external validation group of 42 SSc and 42 IPF cases conferred similarly high specificity for SSc in cases characterized as FCS with high confidence. CONCLUSION: The FCS, a pattern of focal or disproportionate inflammation and/or fibrosis involving the bilateral anterolateral upper lobes and posterosuperior lower lobes, is specific for SSc-ILD when readers are confident of its presence.

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.

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.

Addition of the Fleischner Society Guidelines to Chest CT Examination Interpretive Reports Improves Adherence to Recommended Follow-up Care for Incidental Pulmonary Nodules.

RATIONALE AND OBJECTIVES: The study aimed to determine whether the addition of the Fleischner Society guidelines to chest computed tomography (CT) reports identifying incidental pulmonary nodules affects follow-up care. PATIENTS AND METHODS: Beginning in 2008, a template containing the Fleischner Society guidelines was added at the interpreting radiologist's discretion to chest CT reports describing incidental solid pulmonary nodules at our institution. The records of all medical centers in Olmsted county were used to capture the complete medical history of local patients >35 years old diagnosed with a pulmonary nodule from April 1, 2008 to October 1, 2011. Patients with a history of cancer or previously diagnosed nodule, or who died before follow-up, were excluded. Patients were categorized according to whether they did ("template group") or did not ("control group") have the template added. Nodule size and smoking history were used to determine recommended follow-up care. Differences in follow-up were compared between groups using Pearson's chi-square test. RESULTS: A total of 510 patients (276 in the template group, 234 in the control group) were included in the study. Only 198 patients (39%) received their recommended follow-up care. Template group patients were significantly more likely to receive recommended follow-up care compared to control group patients (45% vs 31%, P = .0014). Most patients whose management did not adhere to Fleischner Society guidelines did not receive a recommended follow-up chest CT (210 out of 312, 67%). CONCLUSIONS: The addition of the Fleischner Society guidelines to chest CT reports significantly increases the likelihood of receiving recommended follow-up care for patients with incidental pulmonary nodules. Additional education is needed to improve appropriate guideline utilization by radiologists and adherence by ordering providers.

Clinical features and outcomes of interstitial lung disease in anti-Jo-1 positive antisynthetase syndrome.

BACKGROUND: Interstitial lung disease (ILD) is a common extra-muscular manifestation of antisynthetase (AS) syndrome. ILD prevalence is higher with anti-Jo-1 antibody positivity. Data on long-term outcomes in these patients are lacking. METHODS: Over 15 years, we identified subjects with anti-Jo-1 positive AS syndrome and ILD. Demographics, pulmonary function testing (PFT), high-resolution computed tomography (HRCT), histopathology, and long-term survival were analyzed. RESULTS: We identified 103 subjects (mean age 49.2 years, female predominance [70%]). The predominant myopathy was polymyositis (64%) followed by dermatomyositis (24%). In approximately half of studied subjects, AS syndrome and ILD were diagnosed within 6 months of each other. The majority had restriction on PFTs (98%). Non-specific interstitial pneumonia (NSIP) was the most common HRCT pattern (52%), followed by NSIP overlapping with organizing pneumonia (OP) (22%). Thirty-nine subjects had biopsy data. Ten-year survival was 68%. Multivariable analysis adjusted for age at ILD diagnosis, gender, FVC and DLCO, revealed that male gender (HR = 2.60, p = 0.04) and DLCO at presentation (HR = 0.94, p = 0.05) significantly predicted mortality. CONCLUSIONS: We present a large cohort of anti-Jo-1 positive AS syndrome with ILD and note good overall survival.