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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 CTDIvol, 7.88 mGy) and research PCD-CT (median CTDIvol, 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.

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.

Abstract 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.

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.

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.

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.