Chest CT features and functional correlates of COVID-19 at 3 months and 12 months follow-up.

Long-term pulmonary sequelae of Coronavirus 2019 (COVID-19) remain unclear. Thus, we aimed to establish post-COVID-19 temporal changes in chest computed tomography (CT) features of pulmonary fibrosis and to investigate associations with respiratory symptoms and physiological parameters at 3 and 12 months' follow-up. Adult patients who attended our initial COVID-19 follow-up service and developed chest CT features of interstitial lung disease, in addition to cases identified using British Society of Thoracic Imaging codes, were evaluated retrospectively. Clinical data were gathered on respiratory symptoms and physiological parameters at baseline, 3 months, and 12 months. Corresponding chest CT scans were reviewed by two thoracic radiologists. Associations between CT features and functional correlates were estimated using random effects logistic or linear regression adjusted for age, sex and body mass index. In total, 58 patients were assessed. No changes in reticular pattern, honeycombing, traction bronchiectasis/bronchiolectasis index or pulmonary distortion were observed. Subpleural curvilinear lines were associated with lower odds of breathlessness over time. Parenchymal bands were not associated with breathlessness or impaired lung function overall. Based on our results, we conclude that post-COVID-19 chest CT features of irreversible pulmonary fibrosis remain static over time; other features either resolve or remain unchanged. Subpleural curvilinear lines do not correlate with breathlessness. Parenchymal bands are not functionally significant. An awareness of the different potential functional implications of post-COVID-19 chest CT changes is important in the assessment of patients who present with multi-systemic sequelae of COVID-19 infection.

The green and sustainable radiology department.

As manmade climate change threatens the health of the planet, it is important that we understand and address the contribution of healthcare to global emissions. Medical imaging is a significant contributor to overall emissions. This article aims to highlight key issues and examples of sustainable practices, in order to empower radiologists to make a change within their department.

Impact of radiographer immediate reporting of X-rays of the chest from general practice on the lung cancer pathway (radioX): a randomised controlled trial.

The National Optimal Lung Cancer Pathway recommends rapid progression from abnormal chest X-rays (CXRs) to CT. The impact of the more rapid reporting on the whole pathway is unknown. The aim of this study was to determine the impact of immediate reporting of CXRs requested by primary care by radiographers on the time to diagnosis of lung cancer. METHOD: People referred for CXR from primary care to a single acute district general hospital in London attended sessions that were prerandomised to either immediate radiographer (IR) reporting or standard radiographer (SR) reporting within 24 hours. CXRs were subsequently reported by radiologists blind to the radiographer reports to test the reliability of the radiographer report. Radiographer and local radiologist discordant cases were reviewed by thoracic radiologists, blinded to reporter. RESULTS: 8682 CXRs were performed between 21 June 2017 and 4 August 2018, 4096 (47.2%) for IR and 4586 (52.8%) for SR. Lung cancer was diagnosed in 49, with 27 (55.1%) for IR. The median time from CXR to diagnosis of lung cancer for IR was 32 days (IQR 19, 70) compared with 63 days (IQR 29, 78) for SR (p=0.03).8258 CXRs (95.1%) were reported by both radiographers and local radiologists. In the 1361 (16.5%) with discordance, the reviewing thoracic radiologists were equally likely to agree with local radiologist and radiographer reports. CONCLUSIONS: Immediate reporting of CXRs from primary care reduces time to diagnosis of lung cancer by half, likely due to rapid progress to CT. Radiographer reports are comparable to local radiologist reports for accuracy. TRIAL REGISTRATION: International Standard Randomised Controlled Trial Number ISRCTN21818068. Registered on 20 June 2017.

Vascular and Parenchymal Enhancement Assessment by Dual-Phase Dual-Energy CT in the Diagnostic Investigation of Pulmonary Hypertension.

PURPOSE: To evaluate pulmonary hypertension (PH) determination by dual-phase dual-energy CT pulmonary angiography vascular enhancement and perfused blood volume (PBV) quantification. MATERIALS AND METHODS: In this prospective study, consecutive participants who underwent both right heart catheterization and dual-phase dual-energy CT pulmonary angiography were included between 2012 and 2014. CT evaluation comprised a standard pulmonary arterial phase dual-energy CT pulmonary angiography acquisition (termed series 1) followed 7 seconds after series 1 completion by a second dual-energy CT pulmonary angiography acquisition limited to the central 10 cm of the pulmonary vasculature (termed series 2). In both series, enhancement in the main pulmonary artery (PAenh), the descending aorta (DAenh), and whole-lung PBV (WLenh) was calculated from dual-energy CT pulmonary angiography iodine images. Dual-energy CT pulmonary angiography and standard cardiovascular metrics were correlated to mean pulmonary artery pressure (mPAP) and pulmonary vascular resistance (PVR) with additional receiver operating characteristic curve analysis. RESULTS: A total of 102 participants (median age, 70; range, 58-78 years; 60 women) were included. Sixty-five participants had PH defined by mPAP of greater than or equal to 25 mm Hg, and 51 participants had PH defined by PVR of greater than 3 Wood units. By either definition, participants with PH had higher PAenh/WLenh ratio and lower WLenh and DAenh in series 1 (P < .05) and higher PAenh and WLenh in series 2 (P < .05). Change in WLenh determined highest diagnostic accuracy to define disease by mPAP (area under the receiver operating characteristic curve [AUC], 0.78) and PVR (AUC, 0.79) and the best mPAP correlation (r = 0.62). PAenh series 2 correlated best with PVR (r = 0.49). Multiple linear regression analysis incorporating WLenh and series 1 DAenh improved PVR correlation (r = 0.56). Combining these dual-energy CT pulmonary angiography metrics with main pulmonary artery size and right-to-left ventricular ratio achieved the highest correlations (mPAP, r = 0.71; PVR, r = 0.64). CONCLUSION: Dual-phase dual-energy CT pulmonary angiography enhancement quantification appears to improve mPAP and PVR prediction in noninvasive PH evaluation.Supplemental material is available for this article.See also the commentary by Kay in this issue.© RSNA, 2020.

Lung cancer screening: nodule identification and characterization.

The accurate identification and characterization of small pulmonary nodules at low-dose CT is an essential requirement for the implementation of effective lung cancer screening. Individual reader detection performance is influenced by nodule characteristics and technical CT parameters but can be improved by training, the application of CT techniques, and by computer-aided techniques. However, the evaluation of nodule detection in lung cancer screening trials differs from the assessment of individual readers as it incorporates multiple readers, their inter-observer variability, reporting thresholds, and reflects the program accuracy in identifying lung cancer. Understanding detection and interpretation errors in screening trials aids in the implementation of lung cancer screening in clinical practice. Indeed, as CT screening moves to ever lower radiation doses, radiologists must be cognisant of new technical challenges in nodule assessment. Screen detected lung cancers demonstrate distinct morphological features from incidentally or symptomatically detected lung cancers. Hence characterization of screen detected nodules requires an awareness of emerging concepts in early lung cancer appearances and their impact on radiological assessment and malignancy prediction models. Ultimately many nodules remain indeterminate, but further imaging evaluation can be appropriate with judicious utilization of contrast enhanced CT or MRI techniques or functional evaluation by PET-CT.

Lung Cancers Associated with Cystic Airspaces: Underrecognized Features of Early Disease.

Early lung cancers associated with cystic airspaces are increasingly being recognized as a cause of delayed diagnoses-owing to data gathered from screening trials and encounters in routine clinical practice as more patients undergo serial imaging. Several morphologic subtypes of cancers associated with cystic airspaces exist and can exhibit variable patterns of progression as the solid elements of the tumor grow. Current understanding of the pathogenesis of these malignancies is limited, and the numbers of cases reported in the literature are small. However, several tumor cell types are represented in these lesions, with adenocarcinoma predominating. The features of cystic airspaces differ among cases and include emphysematous bullae, congenital or fibrotic cysts, subpleural blebs, bronchiectatic airways, and distended distal airspaces. Once identified, these cystic lesions pose management challenges to radiologists in terms of distinguishing them from benign mimics of cancer that are commonly seen in patients who also are at increased risk of lung cancer. Rendering a definitive tissue-based diagnosis can be difficult when the lesions are small, and affected patients tend to be in groups that are at higher risk of requiring biopsy or resection. In addition, the decision to monitor these cases can add to patient anxiety and cause the additional burden of strained departmental resources. The authors have drawn from their experience, emerging evidence from international lung cancer screening trials, and large databases of lung cancer cases from other groups to analyze the prevalence and evolution of lung cancers associated with cystic airspaces and provide guidance for managing these lesions. Although there are insufficient data to support specific management guidelines similar to those for managing small solid and ground-glass lung nodules, these data and guidelines should be the direction for ongoing research on early detection of lung cancer. ©RSNA, 2018.

Iatrogenic peripheral pulmonary air embolism following intravenous contrast administration for CT pulmonary angiography: proposal of the "double bronchus sign".

We present a case of iatrogenic extensive air embolism in the peripheral pulmonary arterial tree following intravenous contrast injection for a CT pulmonary angiogram performed to investigate chest pain in a 25-year-old female patient. Small volumes of iatrogenic air embolism following contrast injection are not infrequently encountered incidentally in the central vasculature (brachiocephalic veins, superior vena cava, right cardiac chambers and main pulmonary arteries). To our knowledge, however, this is the only case of extensive peripheral pulmonary arterial air embolism on CT that has been reported in the literature. Despite the extent of peripheral air, this potentially clinically significant complication was relatively inconspicuous at CT interpretation. A new radiological sign, the "double bronchus sign", is proposed as a useful diagnostic tool. In addition to discussing the imaging features, important safety considerations and principles of immediate management, relevant to all radiologists, are addressed.

Diagnosing acute pulmonary embolism with computed tomography: imaging update.

Acute pulmonary embolism is recognized as a difficult diagnosis to make. It is potentially fatal if undiagnosed, yet increasing referral rates for imaging and falling diagnostic yields are topics which have attracted much attention. For patients in the emergency department with suspected pulmonary embolism, computed tomography pulmonary angiography (CTPA) is the test of choice for most physicians, and hence radiology has a key role to play in the patient pathway. This review will outline key aspects of the recent literature regarding the following issues: patient selection for imaging, the optimization of CTPA image quality and dose, preferred pathways for pregnant patients and other subgroups, and the role of CTPA beyond diagnosis. The role of newer techniques such as dual-energy CT and single-photon emission-CT will also be discussed.

Imaging of acute respiratory distress syndrome.

Chest radiography and computed tomography (CT) have a crucial role to play in the diagnosis and management of acute respiratory distress syndrome (ARDS). The identification of pulmonary opacification is a requirement for the definition of ARDS on the chest radiograph, while CT has a role to play, not only in the diagnosis of ARDS, but also in the identification of complications. This paper reviews the radiological appearances of ARDS that have been documented for some time, and also more recent research that has identified a role for CT in directing ventilation and in prognostication.