Chronic Chest CT Findings following COVID-19 pneumonia.

Respiratory symptoms are a frequent manifestation of patients with post-acute sequela of SARS-CoV-2 (PASC), also known as long-COVID. Many cohorts of predominantly hospitalized patients have shown that a significant subset may have persistent chest CT findings for more than 12 months after the acute infection. Proper understanding of the evolving long-term imaging findings and terminology is crucial for accurate imaging interpretation and patient care. The goal of this article is to review the chronic chest CT findings of patients with PASC and common pitfalls.

Evaluating Acute Pulmonary Changes in Coronavirus Disease 2019: A Comparative Analysis of Computed Tomography, Chest Radiography, Lung Ultrasound, Magnetic Resonance Imaging, and Positron Emission Tomography with Fluorodeoxyglucose Modalities.

This review explores imaging's crucial role in acute Coronavirus Disease 2019 (COVID-19) assessment. High Resolution Computer Tomography is especially effective in detection of lung abnormalities. Chest radiography has limited utility in the initial stages of COVID-19 infection. Lung Ultrasound has emerged as a valuable, radiation-free tool in critical care, and Magnetic Resonance Imaging shows promise as a Computed Tomography alternative. Typical and atypical findings of COVID-19 by each of these modalities are discussed with emphasis on their prognostic value. Considerations for pediatric and immunocompromised cases are outlined. A comprehensive diagnostic approach is recommended, as radiological diagnosis remains challenging in the acute phase.

Developing a Late-Career Roadmap to Continued Career Engagement.

Professional development needs span the entirety of a radiologist's career. Great strides have been made in the creation of an infrastructure for early career development. Work is ongoing to develop such resources for mid-career radiologists, given the recent recognition of the needs of this group. Unfortunately, even less attention has been paid to late-career radiologist development needs as a bridge to retirement. As part of the Career Conversations series, this article will highlight the needs and currently available resources for this group.

Narrowing the Differential Diagnosis of Cystic Lesions in Smokers with Expiratory CT Acquisition Using the Cyst-Airway Communication Hypothesis.

The aim of this study was to assess percentage respiratory changes (δ) in the size of pulmonary cysts of different smoking-related etiologies. Retrospectively, we measured the cystic lesions due to histopathological-confirmed honeycombing from interstitial pulmonary fibrosis, pulmonary Langerhans cell histiocytosis (PLCH), and paraseptal emphysema, using paired inspiratory and expiratory CT scans. In a sample of 72 patients and 216 lesions, the mean diameter of PLCH and honeycombing decreased during expiration (PLCH, δ = 60.9%; p = 0.001; honeycombing, δ = 47.5%; p = 0.014). Conversely, paraseptal emphysema did not show any changes (δ = 5.2%; p = 0.34). In summary, our results demonstrated that cysts in smokers with PLCH and honeycombing fibrosis get smaller during expiratory CT scans, whereas the size of cystic-like lesions due to paraseptal emphysema and bullae tend to remain constant during respiratory cycles. These results support the hypothesis of cyst-airway communication in some cystic diseases, which could assist in the differential diagnosis in smoking-related lung diseases.

The diagnostic value of magnetic resonance imaging compared to computed tomography in the evaluation of fat-containing thoracic lesions.

Intrathoracic fat-containing lesions may arise in the mediastinum, lungs, pleura, or chest wall. While CT can be helpful in the detection and diagnosis of these lesions, it can only do so if the lesions contain macroscopic fat. Furthermore, because CT cannot demonstrate microscopic or intravoxel fat, it can fail to identify and diagnose microscopic fat-containing lesions. MRI, employing spectral and chemical shift fat suppression techniques, can identify both macroscopic and microscopic fat, with resultant enhanced capability to diagnose these intrathoracic lesions non-invasively and without ionizing radiation. This paper aims to review the CT and MRI findings of fat-containing lesions of the chest and describes the fat-suppression techniques utilized in their assessment.

Computed tomography on lung cancer screening is useful for adjuvant comorbidity diagnosis in developing countries.

Purpose: The aim of this study was to analyse and quantify the prevalence of six comorbidities from lung cancer screening (LCS) on computed tomography (CT) scans of patients from developing countries. Methods: For this retrospective study, low-dose CT scans (n=775) were examined from patients who underwent LCS in a tertiary hospital between 2016 and 2020. An age- and sex-matched control group was obtained for comparison (n=370). Using the software, coronary artery calcification (CAC), the skeletal muscle area, interstitial lung abnormalities, emphysema, osteoporosis and hepatic steatosis were accessed. Clinical characteristics of each participant were identified. A t-test and Chi-squared test were used to examine differences between these values. Interclass correlation coefficients (ICCs) and interobserver agreement (assessed by calculating kappa coefficients) were calculated to assess the correlation of measures interpreted by two observers. p-values <0.05 were considered significant. Results: One or more comorbidities were identified in 86.6% of the patients and in 40% of the controls. The most prevalent comorbidity was osteoporosis, present in 44.2% of patients and in 24.8% of controls. New diagnoses of cardiovascular disease, emphysema and osteoporosis were made in 25%, 7% and 46% of cases, respectively. The kappa coefficient for CAC was 0.906 (p<0.001). ICCs for measures of liver, spleen and bone density were 0.88, 0.93 and 0.96, respectively (p<0.001). Conclusions: CT data acquired during LCS led to the identification of previously undiagnosed comorbidities. The LCS is useful to facilitate comorbidity diagnosis in developing countries, providing opportunities for its prevention and treatment.

Expiratory CT scanning in COVID-19 patients: can we add useful data?

OBJECTIVE: To evaluate small airway disease in COVID-19 patients using the prevalence of air trapping (AT) and correlating it with clinical outcomes. The relationship between CT-based opacities in small blood vessels and ventilation in patients with SARS-CoV-2 pneumonia was also assessed. METHODS: We retrospectively included 53 patients with positive RT-PCR results for SARS-CoV-2 between March and April of 2020. All subjects underwent HRCT scanning, including inspiratory and expiratory acquisitions. Subjects were divided into two groups based on visual identification of AT. Small blood vessel volumes were estimated by means of cross-sectional areas < 5 mm2 (BV5) derived from automated segmentation algorithms. Mixed-effect models were obtained to represent the BV5 as a function of CT-based lobar opacities and lobar ventilation. RESULTS: Of the 53 participants, AT was identified in 23 (43.4%). The presence of AT was associated with increased SpO2 at admission (OR = 1.25; 95% CI, 1.07-1.45; p = 0.004) and reduced D-dimer levels (OR = 0.99; 95% CI, 0.99-0.99; p = 0.039). Patients with AT were less likely to be hospitalized (OR = 0.27; 95% CI, 0.08-0.89; p = 0.032). There was a significant but weak inverse correlation between BV5 and CT-based lobar opacities (R2 = 0.19; p = 0.03), as well as a nonsignificant and weak direct correlation between BV5 and lobar ventilation (R2 = 0.08; p = 0.54). CONCLUSIONS: AT is a common finding in patients with COVID-19 that undergo expiratory CT scanning. The presence of AT may correlate with higher SpO2 at admission, lower D-dimer levels, and fewer hospitalizations when compared with absence of AT. Also, the volume of small pulmonary vessels may negatively correlate with CT opacities but not with lobar ventilation.

Chest MRI with CT in the assessment of interstitial lung disease progression in patients with systemic sclerosis.

OBJECTIVE: To describe the performance of CT and MRI in the assessment of the progression of interstitial lung disease (ILD) associated with SSc and demonstrate the correlations of MRI with pulmonary function test (PFT) and CT scores. METHODS: This prospective single-centre observational study included patients with SSc diagnoses, and magnetic resonance (MR) images were assessed visually using the Scleroderma Lung Study (SLS) I system. Differences in the median scores were assessed with Student's t-test and the Wilcoxon rank-sum test. Pearson's and Spearman's rank correlation coefficients were calculated to correlate imaging scores and PFT results. Using disease progression as the gold standard, we calculated the area under the curve (AUC) of the CT and MRI scores with Harrel's c-index. The best thresholds for the prediction of disease progression were determined by receiver operating characteristic curve analysis with maximum Youden's Index (P < 0.05). The sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of the scores were calculated. RESULTS: The AUCs for MRI and CT scores were 0.86 (0.72-0.98; P = 0.04) and 0.83 (0.70-0.99; P = 0.05), respectively. CT and MRI scores correlated with Forced vital capacity (%FVC) (MRI: r = -0.54, P = 0.0045; CT: r = -0.44; P = 0.137) and diffusing capacity of the lung for carbon monoxide (MRI: r = -0.39, P = 0.007; CT r = -0.36, P = 0.006). The sensitivity, specificity, PPV and NPV were 85%, 87.5%, 88.34% and 86.11% (MRI score) and 84.21%, 82.35%, 84.14% and 82.4% (CT score), respectively. CONCLUSIONS: MRI scores from patients with SSc may be an alternative modality for the assessment of ILD progression in patients with SSc.

Pictorial Summary of Congenital Gallbladder and Biliary Duct Anomalies Presentation on HIDA Imaging.

Hepatobiliary iminodiacetic acid (HIDA) scan is one of the principal imaging modalities for the evaluation of the gallbladder and biliary tree. Congenital biliary anomalies are rare and can be difficult to recognize on HIDA scan. They may also mimic other biliary pathology. The purpose of this article is to review the spectrum of congenital gallbladder and biliary anomalies and describe their imaging appearance on HIDA scan. In addition, the diagnostic utility of functional imaging with HIDA when evaluating biliary tract anomalies is described.

Expiratory CT scanning in COVID-19 patients: can we add useful data? / TC expiratória em pacientes com COVID-19: podemos adicionar dados úteis?

ABSTRACT Objective: To evaluate small airway disease in COVID-19 patients using the prevalence of air trapping (AT) and correlating it with clinical outcomes. The relationship between CT-based opacities in small blood vessels and ventilation in patients with SARS-CoV-2 pneumonia was also assessed. Methods: We retrospectively included 53 patients with positive RT-PCR results for SARS-CoV-2 between March and April of 2020. All subjects underwent HRCT scanning, including inspiratory and expiratory acquisitions. Subjects were divided into two groups based on visual identification of AT. Small blood vessel volumes were estimated by means of cross-sectional areas < 5 mm2 (BV5) derived from automated segmentation algorithms. Mixed-effect models were obtained to represent the BV5 as a function of CT-based lobar opacities and lobar ventilation. Results: Of the 53 participants, AT was identified in 23 (43.4%). The presence of AT was associated with increased SpO2 at admission (OR = 1.25; 95% CI, 1.07-1.45; p = 0.004) and reduced D-dimer levels (OR = 0.99; 95% CI, 0.99-0.99; p = 0.039). Patients with AT were less likely to be hospitalized (OR = 0.27; 95% CI, 0.08-0.89; p = 0.032). There was a significant but weak inverse correlation between BV5 and CT-based lobar opacities (R2 = 0.19; p = 0.03), as well as a nonsignificant and weak direct correlation between BV5 and lobar ventilation (R2 = 0.08; p = 0.54). Conclusions: AT is a common finding in patients with COVID-19 that undergo expiratory CT scanning. The presence of AT may correlate with higher SpO2 at admission, lower D-dimer levels, and fewer hospitalizations when compared with absence of AT. Also, the volume of small pulmonary vessels may negatively correlate with CT opacities but not with lobar ventilation.

RESUMO Objetivo: Avaliar a doença das pequenas vias aéreas em pacientes com COVID-19 por meio da prevalência de aprisionamento aéreo (AA) e sua correlação com desfechos clínicos. Também foi avaliada a relação entre opacidades tomográficas nos pequenos vasos sanguíneos e ventilação em pacientes com pneumonia por SARS-CoV-2. Métodos: Foram incluídos, retrospectivamente, 53 pacientes com teste de RT-PCR positivo para SARS-CoV-2 entre março e abril de 2020. Todos os indivíduos foram submetidos à TCAR, incluindo aquisições inspiratórias e expiratórias. Os indivíduos foram divididos em dois grupos com base na identificação visual de AA. Os volumes dos pequenos vasos sanguíneos foram estimados por meio de seções transversais < 5 mm2 (VS5) derivadas de algoritmos automatizados de segmentação. Modelos de efeito misto foram obtidos para representar o VS5 em função das opacidades lobares tomográficas e da ventilação lobar. Resultados: Identificou-se AA em 23 (43,4%) dos 53 participantes. A presença de AA apresentou associação com SpO2 elevada na admissão (OR = 1,25; IC95%: 1,07-1,45; p = 0,004) e níveis reduzidos de dímero D (OR = 0,99; IC95%: 0,99-0,99; p = 0,039). Pacientes com AA apresentaram menor probabilidade de hospitalização (OR = 0,27; IC95%: 0,08-0,89; p = 0,032). Houve correlação inversa significativa, mas fraca, entre VS5 e opacidades lobares tomográficas (R2 = 0,19; p = 0,03) e correlação direta não significativa e fraca entre VS5 e ventilação lobar (R2 = 0,08; p = 0,54). Conclusões: AA é um achado comum em pacientes com COVID-19 submetidos à TC expiratória. A presença de AA pode apresentar correlação com SpO2 elevada na admissão, níveis reduzidos de dímero D e menor probabilidade de hospitalização. Além disso, o volume dos pequenos vasos pulmonares pode apresentar correlação negativa com opacidades tomográficas, mas não com ventilação lobar.

ACR Appropriateness Criteria® Noncerebral Vasculitis.

Noncerebral vasculitis is a wide-range noninfectious inflammatory disorder affecting the vessels. Vasculitides have been categorized based on the vessel size, such as large-vessel vasculitis, medium-vessel vasculitis, and small-vessel vasculitis. In this document, we cover large-vessel vasculitis and medium-vessel vasculitis. Due to the challenges of vessel biopsy, imaging plays a crucial role in diagnosing this entity. While CTA and MRA can both provide anatomical details of the vessel wall, including wall thickness and enhancement in large-vessel vasculitis, FDG-PET/CT can show functional assessment based on the glycolytic activity of inflammatory cells in the inflamed vessels. Given the size of the vessel in medium-vessel vasculitis, invasive arteriography is still a choice for imaging. However, high-resolution CTA images can depict small-caliber aneurysms, and thus can be utilized in the diagnosis of medium-vessel vasculitis. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

ACR Appropriateness Criteria® Suspected Retroperitoneal Bleed.

The initial diagnosis of retroperitoneal bleeding can be challenging by physical examination and clinical presentation. Prompt imaging can make the diagnosis and be lifesaving. When selecting appropriate imaging for these patient's, consideration must be made for sensitivity and ability to image the retroperitoneum, as well as speed of imaging.The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

Diffusion-weighted magnetic resonance imaging for differentiating between benign and malignant thoracic lymph nodes: a meta-analysis.

OBJECTIVE: To establish the diagnostic performance of diffusion-weighted magnetic resonance imaging (DWI) in discriminating malignant from non-malignant thoracic lymph nodes. MATERIALS AND METHODS: This was a meta-analysis involving systematic searches of the MEDLINE, EMBASE, and Web of Science databases up through April 2020. Studies reporting thoracic DWI and lymph node evaluation were included. The pooled sensitivity, specificity, diagnostic odds ratio, positive predictive value, negative predictive value, and area under the receiver operating characteristic curve (AUC) were calculated. RESULTS: We evaluated six studies, involving a collective total of 356 mediastinal lymph nodes in 214 patients. Thoracic DWI had a pooled sensitivity and specificity of 92% (95% confidence interval [95% CI]: 71-98%) and 93% (95% CI: 79-98%), respectively. The positive and negative likelihood ratios were 13.2 (95% CI: 4.0-43.8) and 0.09 (95% CI: 0.02-0.36), respectively. The diagnostic odds ratio was 149 (95% CI: 18-1,243), and the AUC was 0.97 (95% CI: 0.95-0.98). CONCLUSION: DWI is a reproducible technique and has demonstrated high accuracy for differentiating between malignant and benign states in thoracic lymph nodes.

OBJETIVO: Uma meta-análise foi realizada para estabelecer o desempenho diagnóstico da ressonância magnética com imagem ponderada em difusão (DWI) na discriminação de linfonodos torácicos malignos de benignos. MATERIAIS E MÉTODOS: MEDLINE, EMBASE e Web of Science foram sistematicamente pesquisados até abril de 2020. Foram incluídos estudos que relatavam o uso de DWI na avaliação de linfonodos torácicos. Sensibilidade, especificidade, razão de chances de diagnóstico, valores preditivos positivos e negativos e área sob a curva (AUC) foram calculados. RESULTADOS: Foram encontrados 356 linfonodos mediastinais de 214 pacientes nos seis estudos incluídos. DWI produziu sensibilidade e especificidade combinadas de 92% (intervalo de confiança 95% [IC 95%]: 71-98%) e 93% (IC 95%: 79-98%), respectivamente. A razão de verossimilhança positiva foi de 13,2 (IC 95%: 4,0-43,8), a razão de verossimilhança negativa foi de 0,09 (IC 95%: 0,02-0,36); A razão de chances de diagnóstico foi de 149 (IC 95%: 18-1.243). A DWI teve uma AUC de 0,97 (IC 95%: 0,95-0,98). CONCLUSÃO: DWI é uma técnica reprodutível que demonstrou alta acurácia na diferenciação de estados malignos e benignos nos linfonodos torácicos.

Diffusion-weighted magnetic resonance imaging for differentiating between benign and malignant thoracic lymph nodes: a meta-analysis / Ressonância magnética ponderada em difusão para a diferenciação entre linfonodos torácicos malignos de benignos: uma meta-análise

Abstract Objective: To establish the diagnostic performance of diffusion-weighted magnetic resonance imaging (DWI) in discriminating malignant from non-malignant thoracic lymph nodes. Materials and Methods: This was a meta-analysis involving systematic searches of the MEDLINE, EMBASE, and Web of Science databases up through April 2020. Studies reporting thoracic DWI and lymph node evaluation were included. The pooled sensitivity, specificity, diagnostic odds ratio, positive predictive value, negative predictive value, and area under the receiver operating characteristic curve (AUC) were calculated. Results: We evaluated six studies, involving a collective total of 356 mediastinal lymph nodes in 214 patients. Thoracic DWI had a pooled sensitivity and specificity of 92% (95% confidence interval [95% CI]: 71-98%) and 93% (95% CI: 79-98%), respectively. The positive and negative likelihood ratios were 13.2 (95% CI: 4.0-43.8) and 0.09 (95% CI: 0.02-0.36), respectively. The diagnostic odds ratio was 149 (95% CI: 18-1,243), and the AUC was 0.97 (95% CI: 0.95-0.98). Conclusion: DWI is a reproducible technique and has demonstrated high accuracy for differentiating between malignant and benign states in thoracic lymph nodes.

Resumo Objetivo: Uma meta-análise foi realizada para estabelecer o desempenho diagnóstico da ressonância magnética com imagem ponderada em difusão (DWI) na discriminação de linfonodos torácicos malignos de benignos. Materiais e Métodos: MEDLINE, EMBASE e Web of Science foram sistematicamente pesquisados até abril de 2020. Foram incluídos estudos que relatavam o uso de DWI na avaliação de linfonodos torácicos. Sensibilidade, especificidade, razão de chances de diagnóstico, valores preditivos positivos e negativos e área sob a curva (AUC) foram calculados. Resultados: Foram encontrados 356 linfonodos mediastinais de 214 pacientes nos seis estudos incluídos. DWI produziu sensibilidade e especificidade combinadas de 92% (intervalo de confiança 95% [IC 95%]: 71-98%) e 93% (IC 95%: 79-98%), respectivamente. A razão de verossimilhança positiva foi de 13,2 (IC 95%: 4,0-43,8), a razão de verossimilhança negativa foi de 0,09 (IC 95%: 0,02-0,36); A razão de chances de diagnóstico foi de 149 (IC 95%: 18-1.243). A DWI teve uma AUC de 0,97 (IC 95%: 0,95-0,98). Conclusão: DWI é uma técnica reprodutível que demonstrou alta acurácia na diferenciação de estados malignos e benignos nos linfonodos torácicos.

Comparison of CT image quality between the AIDR 3D and FIRST iterative reconstruction algorithms: an assessment based on phantom measurements and clinical images.

Modern CT iterative reconstruction algorithms are transitioning from a statistical-based to model-based approach. However, increasing complexity does not ensure improved image quality for all indications, and thorough characterization of new algorithms is important to understand their potential clinical impacts. This study performs both quantitative and qualitative analyses of image quality to compare Canon's statistical-based Adaptive Iterative Dose Reduction 3D (AIDR 3D) algorithm to its model-based algorithm, Forward-projected model-based Iterative Reconstruction SoluTion(FIRST). A phantom was used to measure the task-specific modulation transfer function (MTFTask), the noise power spectrum (NPS), and the low-contrast object-specific CNR (CNRLO) for each algorithm using three dose levels and the convolution algorithm (kernel) appropriate for abdomen, lung, and brain imaging. Additionally, MTFTaskwas measured at four contrast levels, and CNRLOwas measured for two object sizes. Lastly, three radiologists participated in a preference study to compare clinical image quality for three study types: non-contrast abdomen, pulmonary embolism (PE), and lung screening. Nine questions related to the appearance of anatomical features or image quality characteristics were scored for twenty exams of each type. The behavior of both algorithms depended strongly on the kernel selected. Phantom measurements suggest that FIRST should be beneficial over AIDR 3D for abdomen imaging, but do not suggest a clear overall benefit to FIRST for lung or brain imaging; metrics suggest performance may be equivalent to or slightly favor AIDR 3D, depending on the size of the object being imaged and whether spatial resolution or low-contrast resolution is more important for the task at hand. Overall, radiologists strongly preferred AIDR 3D for lung screening, slightly preferred AIDR 3D for non-contrast abdomen, and had no preference for PE. FIRST was superior for the reduction of metal artifacts. Radiologist preference may be influenced by changes to noise texture.

MRI-based differentiation between lymphoma and sarcoidosis in mediastinal lymph nodes.

OBJECTIVE: Evaluation of enlarged mediastinal lymph nodes is crucial for patient management. Malignant lymphoma and sarcoidosis are often difficult to differentiate. Our objective was to determine the diagnostic accuracy of MRI for differentiating between sarcoidosis and malignant lymphoma. METHODS: This was a retrospective study involving 47 patients who underwent chest MRI and were diagnosed with one of the diseases between 2017 and 2019. T1, T2, and diffusion-weighted signal intensity were measured. Apparent diffusion coefficients (ADCs) and T2 ratios were calculated. The diagnostic performance of MRI was determined by ROC analysis. RESULTS: Mean T2 ratio was significantly lower in the sarcoidosis group than in the lymphoma group (p = 0.009). The T2-ratio cutoff value that best differentiated between lymphoma-related and sarcoidosis-related enlarged lymph nodes was 7.1, with a sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 58.3%, 95.6%, 76.5%, 93.3%, and 68.7%, respectively. The mean ADC was significantly lower in the lymphoma group than in the sarcoidosis group (p = 0.002). The ADC cutoff value that best differentiated between lymphoma-related and sarcoidosis-related enlarged lymph nodes was 1.205, with a sensitivity, specificity, positive predictive value, negative predictive value and accuracy of 87.5%, 82.6%, 85.1%, 84.0% and 86.3%, respectively. No significant differences were found between the two groups regarding T1 signal intensity, T2 signal intensity, and lymph node diameter. CONCLUSIONS: MRI parameters such as ADC, diffusion, and T2 ratio can be useful in the differentiation between sarcoidosis and lymphoma in the evaluation of enlarged lymph nodes.

Utilization of Quantitative Computed Tomography Assessment to Identify Bronchiolitis Obliterans Syndrome After Single Lung Transplantation.

OBJECTIVE: To evaluate quantitative chest computed tomography (CT) methods for the detection of air trapping (AT) and to assess its diagnostic performance for the diagnosis of bronchiolitis obliterans syndrome (BOS) in single lung transplant (SLT) patients. METHODS: Adult patients who had a SLT at a single transplant center and underwent CT scan after transplantation were retrospectively included. CT findings of air trapping were measured by three different methods: expiratory air-trapping index (ATIexp), mean lung density on expiratory acquisition (MLDexp) and expiratory to inspiratory ratio of mean lung density (E/I-ratio(MLD). Sensitivity, specificity and diagnostic accuracy of the three methods for the detection of BOS status evaluated by serial routine measures of pulmonary function tests (gold standard) were assessed. RESULTS: Forty-six SLT patients (52.2% females, mean age 58 ± 6 years) were included in the analysis, 12 (26%) patients with a diagnosis of BOS. Quantitative CT diagnosis of AT ranged from 26 to 35%. Sensitivity, specificity and accuracy of each method for the detection of BOS were 85.7%, 84.7% and 85.0% for ATIexp, 78.5%, 93.4% and 90.0% for MLD and 64.2%, 89.1% and 83.3% E/I-ratio(MLD), respectively. CONCLUSION: Quantitative measures of AT obtained from standard CT are feasible and show high specificity and accuracy for the detection of BOS in SLT patients.