Cox, Christian W.

Abstract Objectives To develop a volume of interest (VOI) imaging technique in multi-detector-row helical CT to reduce radiation dose or improve image quality within the VOI. Methods A deep-learning method based on a residual U-Net architecture, named VOI-Net, was developed to correct truncation artifacts in VOI helical CT. Three patient cases, a chest CT of interstitial lung disease and 2 abdominopelvic CT of liver tumour, were used for evaluation through simulation. Results VOI-Net effectively corrected truncation artifacts (root mean square error [RMSE] of 5.97 ± 2.98 Hounsfield Units [HU] for chest, 3.12 ± 1.93 HU, and 3.71 ± 1.87 HU for liver). Radiation dose was reduced by 71% without sacrificing image quality within a 10-cm diameter VOI, compared to a full scan field of view (FOV) of 50 cm. With the same total energy deposited as in a full FOV scan, image quality within the VOI matched that at 350% higher radiation dose. A radiologist confirmed improved lesion conspicuity and visibility of small linear reticulations associated with ground-glass opacity and liver tumour. Conclusions Focusing radiation on the VOI and using VOI-Net in a helical scan, total radiation can be reduced or higher image quality equivalent to those at higher doses in standard full FOV scan can be achieved within the VOI. Advances in knowledge A targeted helical VOI imaging technique enabled by a deep-learning-based artifact correction method improves image quality within the VOI without increasing radiation dose.

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.

We present a case of a woman who had progressive shortness of breath and wheezing with a mild restrictive pulmonary function pattern. She was initially diagnosed with eosinophilic granulomatosis with polyangiitis on the basis of peripheral eosinophilia, bronchoalveolar lavage eosinophilia (47%) and surgical lung biopsy findings. Six months following her diagnosis, the patient returned because of persistent symptoms, and a second review of the lung biopsy revealed thrombotic lesions in the pulmonary vessels with polarisable foreign body materials, associated giant cell reactions and numerous eosinophil infiltrates, consistent with intravenous drug abuse. Further investigation showed that she had a history of intravenous heroin overdose, and the diagnosis of excipient lung disease was made. This case highlights the importance of expert pathological, radiological and clinical review of complex presentations and the need for a thorough medication and drug use history review.

Abstract Langerhans cell histiocytosis (LCH) can affect children and adults with a wide variety of clinical manifestations, including unifocal, single-system multifocal, single-system pulmonary (smoking-associated), or multisystem disease. The existing paradigms in the management of LCH in adults are mostly derived from the pediatric literature. Over the last decade, the discovery of clonality and MAPK-ERK pathway mutations in most cases led to the recognition of LCH as a hematopoietic neoplasm, opening the doors for treatment with targeted therapies. These advances have necessitated an update of the existing recommendations for the diagnosis and treatment of LCH in adults. This document presents consensus recommendations that resulted from the discussions at the annual Histiocyte Society meeting in 2019, encompassing clinical features, classification, diagnostic criteria, treatment algorithm, and response assessment for adults with LCH. The recommendations favor the use of 18F-Fluorodeoxyglucose positron emission tomography-based imaging for staging and response assessment in the majority of cases. Most adults with unifocal disease may be cured by local therapies, while the first-line treatment for single-system pulmonary LCH remains smoking cessation. Among patients not amenable or unresponsive to these treatments and/or have multifocal and multisystem disease, systemic treatments are recommended. Preferred systemic treatments in adults with LCH include cladribine or cytarabine, with the emerging role of targeted (BRAF and MEK inhibitor) therapies. Despite documented responses to treatments, many patients struggle with a high symptom burden from pain, fatigue, and mood disorders that should be acknowledged and managed appropriately.

AbstractLangerhans cell histiocytosis (LCH) is a histiocytic neoplasm that can involve the lungs as single system (LCH‐SSL) or multisystem disease (LCH‐MSL). The role of full‐body radiographic staging to determine whether patients have LCH‐SSL or LCH‐MSL is unclear. Long‐term outcomes of LCH‐SSL versus LCH‐MSL and multisystem without lung involvement (LCH‐MSNL) are unknown. A retrospective study of adult LCH patients seen at our center from January 2000 to 2020 was performed. In Part 1, we addressed utility of whole‐body staging imaging among those presenting with isolated pulmonary signs or symptoms. Staging was defined as fluorodeoxyglucose positron emission tomography‐computed tomography (CT) or whole‐body CT obtained within 3 months of diagnosis. In Part 2, we examined the frequency of developing extra‐pulmonary disease over time and mortality in patients with LCH‐SSL. In Part 3, we compared the overall survival of LCH‐SSL, LCH‐MSL, and LCH‐MSNL. Part 1: 240 patients with LCH were identified. A total of 112 (47%) had pulmonary signs or symptoms at presentation. Thirty‐four (30%) underwent radiographic staging and only one showed evidence of extra‐pulmonary disease. Part 2: 108 (45%) were LCH‐SSL. Median follow‐up duration of 4.5 years (95% confidence interval [CI]: 2.9–6.0). None developed extra‐pulmonary disease. Part 3: 5‐year survival: 94% (95% CI: 84%–98%) for LCH‐SSL, 78% (95% CI: 59%–90%) for LCH‐MSL, and 75% (95% CI: 53%–89%) for LCH‐MSNL. LCH patients presenting with isolated pulmonary signs or symptoms rarely have extra‐pulmonary involvement at the time of diagnosis and generally do not develop extra‐pulmonary progression. LCH‐SSL has the best overall survival, while LCH‐MSL and LCH‐MSNL have similar clinical outcomes.

Abstract PurposeTo determine the utility of GLILD CT scoring system for assessment of GLILD in patients with CVID to avoid the need for lung biopsy. MethodsThe CT scoring system was developed as a consensus based on review of literature. Two radiologists, blinded to patient clinical information, retrospectively scored CT scans of selected patients with histopathologic diagnosis of GLILD. Discrepancies were settled by a third radiologist. Inter-observer reproducibility was calculated with intra-class correlation coefficients. ResultsWe identified 25 CVID patients with histologically confirmed GLILD (12 male, 13 female). The median age was 38 years (range 12 – 72 years). Inter-observer reproducibility was 0.76 (95% CI 0.53 – 0.89). Splenomegaly/splenectomy and basilar predominant perilymphatic nodules greater than or equal to 4mm have good interobserver agreement in our CT scoring system. Discrepancy between observers occurred most often in differentiating intermediate versus high confidence diagnosis of GLILD as opposed to differentiating between low versus intermediate confidence. ConclusionGLILD CT scoring system of pulmonary disease in CVID patients can stratify patients into categories that may assist in avoiding lung biopsy for diagnosis in a subset of patients.

Objective The aim of the study was to compare the prevalence of diffuse pulmonary ossification (DPO) in idiopathic pulmonary fibrosis (IPF), systemic sclerosis (SSc)-related interstitial lung disease (ILD), and chronic hypersensitivity pneumonitis (HP). Methods High-resolution computed tomography (HRCT) from 71 IPF, 67 SSc-ILD, and 75 HP cases were independently evaluated by 2 thoracic radiologists blinded to patient data. Studies were assessed for the presence of DPO, HRCT scanning pattern, stigmata of granulomatous infection, and honeycombing. Results The prevalence of DPO was significantly higher in cases of IPF and SSc compared with HP, although there was no significant difference in prevalence between the IPF and SSc groups, even when accounting for the presence of prior granulomatous infection. Interobserver agreement for the presence of DPO was substantial. Conclusions Although prevalence DPO on HRCT varies between some forms of ILD, the use of DPO to influence characterization of ILD should be considered with caution.

BackgroundSpontaneous pneumomediastinum (SP) is an uncommon disorder but has been described in cases with connective tissue diseases (CTDs), most commonly dermatomyositis and polymyositis. We aimed to explore this relationship by analyzing the characteristics of CTD patients with SP.MethodsUsing a computer-assisted search, we identified 25 patients with CTD and SP evaluated between January 1997 and December 2016 at our institution. Clinicoradiologic characteristics, treatment, and outcomes were extracted and chest computed tomography studies analyzed.ResultsWe identified 25 patients with CTD and SP. Median (range) age at SP occurrence was 55 (18–82) years, and 60% of the patients were women. Smoking history was present in 37%. Spontaneous pneumomediastinum was symptomatic in 56% of patients. Eighteen patients (72%) had a known CTD diagnosis, and 20 patients (80%) manifested radiologic evidence of interstitial lung disease. Spontaneous pneumomediastinum diagnosis was achieved with chest radiography in 20% of cases and chest computed tomography in the other cases. Spontaneous pneumomediastinum was managed with expectant observation alone in 22 cases (88%). Four patients (16%) had concomitant pneumothorax, 1 of whom required chest tube drainage. There were no deaths attributable to SP during the median (range) follow-up of 13 (0–174) months. Cumulative survival was 52% at 1 year and 40% at 2 years.ConclusionsSpontaneous pneumomediastinum is an uncommon manifestation of CTD and usually occurs in the presence of interstitial lung disease. Although SP seems to be associated with a relatively benign short-term course, occurrence of SP in CTD patients may be a poor prognostic factor.

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.