A novel FLCN gene mutation causing Birt-Hogg-Dubé syndrome in a Korean family.

Spontaneous pneumothorax is a common manifestation of Birt-Hogg-Dubé (BHD) syndrome, an inherited disorder caused by mutation of the folliculin (FLCN) gene. A 44-year-old female with a history of breast cancer was diagnosed with recurrent pneumothorax. Chest CT showed multiple cysts with left lung pneumothorax, and she received surgery for the diagnosis. Because the patient also had a family history of spontaneous pneumothorax, a FLCN genetic examination was conducted. A novel heterozygous, likely pathogenic variant (NM_144997.5:c.779+2T > C) was detected in the proband, her mother, and aunt. This is the first report of a new mutation of FLCN gene in a BHD syndrome patient.

CT findings of acute radiation-induced pneumonitis in breast cancer.

OBJECTIVES: To evaluate the CT findings of acute radiation pneumonitis (RP) in breast cancer patients undergoing post-operative radiotherapy, and to analyze clinicodosimetric factors associated with acute RP. METHODS: Between 2015 and 2017, 61 patients with breast cancer who underwent follow-up chest CT at 3 months after radiotherapy were analyzed. The degree of acute RP on CT was evaluated by the change of extent and scoring system (grade 0, no RP; Grade 1, ground-glass opacities (GGOs); Grade 2, GGOs and/or consolidations; Grade 3, clear focal consolidation; Grade 4, dense consolidation). The dosimetric parameters were calculated from the dose-volume histogram of RT. RESULTS: The acute RP on CT was scored as follows: Grade 0, in 37.7%, Grade 1 in 13.1%, Grade 2 in 44.3%, and Grade 3 in 4.9%. The median extent of RP in patients with Grades 1 to 3 was 6.2 ml (range, 0.2-95.9). There were no clinicodosimetric factors significantly associated with the presence of RP or its severity. One patient developed symptomatic RP. CONCLUSION: This study showed no correlation between acute RP and clinicodosimetric factors, and acute RP based on CT findings were much more common than symptomatic RP. ADVANCES IN KNOWLEDGE: CT findings of acute RP or extent of RP were not significantly related to clinicodosimetric factors in breast cancer patients.

Imaging Features of Various Benign and Malignant Tumors and Tumorlike Conditions of the Pleura: A Pictorial Review.

Pleural masses may be caused by various conditions, including benign and malignant neoplasms and non-neoplastic tumorlike conditions. Primary pleural neoplasms include solitary fibrous tumor, malignant mesothelioma, and primary pleural non-Hodgkin's lymphoma. Metastatic disease is the most common neoplasm of the pleura and may uncommonly occur in patients with hematologic malignancy, including lymphoma, leukemia, and multiple myeloma. Pleural effusion is usually associated with pleural malignancy. Rarely, pleural malignancy may arise from chronic empyema, and the most common cell type is non-Hodgkin's lymphoma (pyothorax-associated lymphoma). Non-neoplastic pleural masses may be observed in several benign conditions, including tuberculosis, pleural plaques caused by asbestos exposure, and pleural loose body. Herein, we present a review of benign and malignant pleural neoplasms and tumorlike conditions with illustrations of their computed tomographic images.

Clinical features and outcomes in patients with pulmonary complications during pregnancy and peripartum.

Introduction: The aim of this study was to investigate clinical features and identify maternal factors contributing to prognosis in women with pulmonary complications during pregnancy and the peripartum period.Materials and methods: Following a retrospective review of clinical data and radiographic findings between January 2006 and January 2016, 126 women diagnosed with pulmonary complications during pregnancy (N = 79) and peripartum within the first 4 weeks after delivery (N = 47) were enrolled in this study.Results: Of the 126 patients, 113 (89.7%) required hospitalization. The median age was 32 years, and the percentage of primiparous women was 49.2%. The most common respiratory complaint was dyspnea, followed by cough and fever. Pneumonia developed in 50 patients (39.6%), pulmonary edema in 31 (24.6%), pleural effusion in 28 (22.2%), active pulmonary tuberculosis in 13 (10.3%), and asthma exacerbation in 4 (3.1%). Among the 79 antenatal patients with pulmonary complications, 31 (39.2%) experienced pregnancy-related complications, 21 (26.6%) had an emergency C-section, and 29 (36.7%) had an adverse fetal outcome. Eleven patients (8.7%) developed acute respiratory failure requiring mechanical ventilation, and the overall mortality was 1.6% (2/126) with no pulmonary complication-related deaths. Multiple regression analysis revealed that presence of pregnancy-related complications and younger fetal gestational age at the diagnosis were independent predictive factors for adverse fetal outcomes.Discussion: Pulmonary complications during pregnancy and the peripartum period resulted in poor outcomes, and the risk of adverse fetal outcomes was high, particularly in patients with pregnancy-related complications and younger gestational age at the diagnosis.

Hemoptysis requiring bronchial artery embolization in patients with nontuberculous mycobacterial lung disease.

BACKGROUND: Although infections caused by nontuberculous mycobacteria (NTM) are increasing in prevalence, there are few data about hemoptysis in patients with NTM lung disease. This study investigated the characteristics and prognosis of hemoptysis secondary to NTM infection. METHODS: Following a retrospective review of cases managed between 2006 and 2016, 183 patients with NTM lung disease were enrolled and analyzed. RESULTS: Among 183 patients with NTM lung disease, Mycobacterium intracellulare (n = 64, 35%) was the major cause of NTM infection, followed by M. avium (n = 59, 32.2%) and M. abscessus complex (n = 40, 21.9%). Hemoptysis developed in 78 patients (42.6%), among whom 33 (42.3%) required bronchial artery embolization (BAE). Between patients with and without hemoptysis, there were no significant differences with respect to sex, radiographic manifestations, distribution over 3 lobes on chest computed tomography, history of pulmonary tuberculosis, antiplatelet or anticoagulation therapy, and species of NTM. However, mean age at diagnosis was significantly lower in the hemoptysis group in univariate and multivariate analyses (65.7 ± 12.8 vs. 59.7 ± 11.8, P = 0.002, odds ratio: 0.969, 95% confidence interval: 0.944-0.996). Among patients with hemoptysis, those requiring medical therapy and those requiring BAE were not significantly different in terms of demographic characteristics, radiographic manifestations, and distribution over 3 lobes. All patients who received BAE showed immediate clinical improvement, no procedure-related complications, and none of them died during the period under review. CONCLUSIONS: NTM lung disease patients commonly experienced hemoptysis without specific risk factors except for relatively young age. Although some patients with hemoptysis needed BAE, the success rate of BAE was high, and there were no serious complications associated with BAE.

Long-Term Mortality and Prognostic Factors in Aspiration Pneumonia.

OBJECTIVES: Aspiration pneumonia is a leading cause of death among older patients; however, little is known about the long-term mortality in aspiration pneumonia. The purpose of this study was to evaluate long-term mortality and its associated factors in patients with aspiration pneumonia. DESIGN: Retrospective cohort study. SETTING AND PARTICIPANTS: In total, 550 patients with aspiration pneumonia (median age: 78.0 years, 66.4% male) with compatible clinical symptoms and chest computed tomography images were enrolled at a single tertiary center from 2006 to 2016. MEASURES: The 1-, 3-, and 5-year mortality rates were evaluated for all patients. The prognostic factors for 1-year and 5-year mortality were also evaluated using Cox proportional hazard models. RESULTS: A total of 441 (80.2%) patients died during a median follow-up of 50.7 weeks. The 1-, 3-, and 5-year mortality rates were 49.0%, 67.1%, and 76.9%, respectively. Multivariate analysis identified 5 risk factors for 1-year mortality of male sex [hazard ratio (HR) 1.533, P = .003], low body mass index (HR 0.934, P = .002), hypoalbuminemia, anemia (0.973, P = .032), and mechanical ventilation (HR 2.052, P < .001), which were also independent prognostic factors for 5-year mortality. During the follow-up period, 133 (24.2%) patients experienced recurrent aspiration pneumonia. However, Kaplan-Meier analysis showed no significant differences in survival curves between patients with single and recurrent aspiration pneumonia (P = .371). CONCLUSIONS/IMPLICATIONS: Long-term prognosis of aspiration pneumonia was poor as a result of underlying morbidity instead of the aspiration pneumonia itself. Our findings suggest that prognostic indices for patients with aspiration pneumonia including the patient's underlying conditions should be devised.

Lumen area change (Delta Lumen) between inspiratory and expiratory multidetector computed tomography as a measure of severe outcomes in asthmatic patients.

BACKGROUND: Quantitative computed tomographic (QCT) biomarkers of airway morphology hold potential for understanding and monitoring regional airway remodeling in asthmatic patients. OBJECTIVE: We sought to determine whether the change in airway lumen area between total lung capacity (TLC) and functional residual capacity (FRC) lung volumes measured from CT imaging data was correlated with severe outcomes in asthmatic patients. METHODS: We studied 152 asthmatic patients (90 female and 62 male patients) and 33 healthy subjects (12 female and 21 male subjects) using QCT. Postprocessing of airways at generations 1 to 5 (1 = trachea) was performed for wall area percentage, wall thickness percentage (WT%), lumen area at baseline total lung capacity (LATLC), lumen area at baseline functional residual capacity (LAFRC), and low attenuation area at FRC. A new metric (reflecting remodeling, distal air trapping, or both), Delta Lumen, was determined as follows: Percentage difference in lumen area (LATLC - LAFRC)/LATLC × 100. RESULTS: Postprocessing of 4501 airway segments was performed (3681 segments in the 152 patients with asthma and 820 segments in the 33 healthy subjects; range, 17-28 segments per subject). Delta Lumen values were negatively correlated with WT% and low attenuation area (P < .01) in asthmatic patients. Delta Lumen values were significantly lower for airway generations 3 to 5 (segmental airways) in subjects undergoing hospitalization because of exacerbation and in patients with refractory asthma requiring treatment with systemic corticosteroids. WT% and low attenuation area were positively and Delta Lumen values were negatively associated with systemic corticosteroid treatment (P < .05), suggesting that a reduced Delta Lumen value is a potential outcome biomarker in patients with severe asthma. CONCLUSION: Reduced Delta Lumen value in the central airways measured by using QCT is a promising exploratory biomarker of unstable refractory asthma that warrants further study.

Diagnosis of small pulmonary lesions by transbronchial lung biopsy with radial endobronchial ultrasound and virtual bronchoscopic navigation versus CT-guided transthoracic needle biopsy: A systematic review and meta-analysis.

BACKGROUND: Advances in bronchoscopy and CT-guided lung biopsy have improved the evaluation of small pulmonary lesions (PLs), leading to an increase in preoperative histological diagnosis. We aimed to evaluate the efficacy and safety of transbronchial lung biopsy using radial endobronchial ultrasound and virtual bronchoscopic navigation (TBLB-rEBUS&VBN) and CT-guided transthoracic needle biopsy (CT-TNB) for tissue diagnosis of small PLs. METHODS: A systematic search was performed in five electronic databases, including MEDLINE, EMBASE, Cochrane Library Central Register of Controlled Trials, Web of Science, and Scopus, for relevant studies in May 2016; the selected articles were assessed using meta-analysis. The articles were limited to those published after 2000 that studied small PLs ≤ 3 cm in diameter. RESULTS: From 7345 records, 9 articles on the bronchoscopic (BR) approach and 15 articles on the percutaneous (PC) approach were selected. The pooled diagnostic yield was 75% (95% confidence interval [CI], 69-80) using the BR approach and 93% (95% CI, 90-96) using the PC approach. For PLs ≤ 2 cm, the PC approach (pooled diagnostic yield: 92%, 95% CI: 88-95) was superior to the BR approach (66%, 95% CI: 55-76). However, for PLs > 2 cm but ≤ 3 cm, the diagnostic yield using the BR approach was improved to 81% (95% CI, 75-85). Complications of pneumothorax and hemorrhage were rare with the BR approach but common with the PC approach. CONCLUSIONS: CT-TNB was superior to TBLB-rEBUS&VBN for the evaluation of small PLs. However, for lesions greater than 2 cm, the BR approach may be considered considering its diagnostic yield of over 80% and the low risk of procedure-related complications.

Risk factors associated with treatment refusal in lung cancer.

BACKGROUND: The incidence of lung cancer is increasing with longer life expectancy. Refusal of active treatment for cancer is prone to cause patients to experience more severe symptoms and shorten survival. The purpose of this study was to define the factors related to refusal or abandonment of active therapy in lung cancer. METHODS: We retrospectively reviewed the data of 617 patients from medical records from 2010 to 2014. Two groups were formed: 149 patients who refused anti-cancer treatment and allowed only palliative care were classified into the non-treatment group, while the remaining 468 who received anti-cancer treatment were classified into the treatment group. RESULTS: The groups differed significantly in age, employment, relationship status, number of offspring, educational status, body mass index, presence of chest and systemic symptoms, Charlson Comorbidity Index, Eastern Cooperative Oncology Group score, and tumor node metastasis stage ( P < 0.05). In logistic regression analysis, age (odds ratio [OR] 1.10, 95% confidence interval [CI] 1.07-1.13), educational status lower than high school (OR 1.95, 95% CI 1.2-3.2), no history of surgery (OR 2.29, 95% CI 1.4-3.7), body mass index < 18.5 (OR 2.49, 95% CI 1.3-4.7), and a high Eastern Cooperative Oncology Group score of 3 or 4 (OR 5.02, 95% CI 2.3-10.8) were significant factors for refusal of cancer treatment. CONCLUSION: Individual factors, such as old age, low educational status, low weight, and poor performance status can influence refusal of cancer treatment in patients with lung cancer, and should be considered prior to consultation with patients.

Multiple cavitating pulmonary nodules: rare manifestation of benign metastatic leiomyoma.

Benign metastasizing leiomyoma (BML) is a rare disease of pathologically benign, but the tumor metastasizes to other organs. The most common organ involved in BML is lung. Pulmonary involvement usually manifested as multiple nodules on chest X-ray, however we experienced an interesting case of a 52-year-old premenopausal woman who presented with multiple bilateral lung cavitations and nodules on a chest X-ray without any respiratory symptoms. Chest computed-tomography identified multiple cavitary lesions of 5-12 mm in diameter and well-defined nodules of 5-10 mm in diameter in both lung fields. Transthoracic needle biopsy was performed and the resected lesion consisted of benign spindle cells was positive for estrogen receptor (ER) and progesterone receptor (PR) and was diffuse positive for actin and desmin by immunohistochemical (IHC) staining, suggesting leiomyoma. The final diagnosis was benign pulmonary metastasizing leiomyoma (BPML) and the patient underwent subcutaneous injection of a gonadotrophin releasing hormone (GnRH) agonist for 12 months, follow-up low-dose chest computed tomography (CT) scan at 15 months revealed decreased cavitations and nodular lesions. We should take into consideration the possibility of BPML when we encounter multiple cystic or cavitary lesions on chest X-ray, although the common form of BPML is nodulary lesions on imaging studies.

A Pleural Loose Body Mimicking a Pleural Tumor: A Case Report.

We present a rare case of a pleural loose body, thought to be a pedunculated pleural tumor, found incidentally in a 58-year-old female. Computed tomography showed a non-enhancing mass, which migrated along the mediastinum and paravertebral area. Thoracoscopic surgery revealed a 4 cm, soap-like mass that was found to be a fibrin body consisting of hyalinized collagen histopathologically. Mobility and the lack of contrast enhancement of a pleural mass are important clues to diagnosing this benign condition.

Clinical Features and Outcomes of Respiratory Complications in Patients with Thoracic Hyperkyphosis.

INTRODUCTION: There are few data about thoracic hyperkyphosis which focused on respiratory events and prognoses. We investigated the clinical features and outcomes of respiratory complications requiring hospitalization in patients with thoracic hyperkyphosis. METHODS: Following a retrospective review of the medical records between 2002 and 2011, we included 51 patients with thoracic hyperkyphosis who had visited the respiratory department due to respiratory symptoms. RESULTS: Of total 51 patients, 35 patients were hospitalized due to respiratory events. Among 56 total hospitalized events, acute respiratory failure (ARF) (n = 18) and exacerbation of a chronic airway disorder (n = 18) were the most common causes. Respiratory events related mortality was 13.7 % (7/51). The median value of the thoracic kyphosis angle was 89.0°. The ratio of the measured kyphosis angle to the normal value according to age and sex showed the median value of 2.38 (interquartile range 1.61-2.87). This ratio was negatively correlated with both predicted forced vital capacity (γ = -0.647, p < 0.0001) and predicted forced expiratory volume for 1 s (γ = -0.518, p = 0.008). After adjustments for age and sex, hyperkyphosis (angle ≥90°) was not found to influence the development of ARF (hazard ratio 3.2; 95 % confidence interval, 0.86-12.14; p = 0.082). CONCLUSIONS: Patients with thoracic hyperkyphosis presenting to a respiratory department with respiratory issues commonly experienced respiratory events requiring hospitalization and had a poor prognosis. In addition, the severity of the kyphosis angle was correlated with respiratory insufficiency although it was not a risk factor for the development of ARF.

Prognosis and Predictors of Rebleeding After Bronchial Artery Embolization in Patients with Active or Inactive Pulmonary Tuberculosis.

INTRODUCTION: The aim of this study was to characterize the prognosis and identify factors that contribute to rebleeding after bronchial artery embolization (BAE) in patients with active or inactive pulmonary tuberculosis (PTB). METHODS: Following a retrospective review, 190 patients had hemoptysis requiring BAE due to PTB in one hospital between 2006 and 2013. RESULTS: The median age at the time of diagnosis of PTB was 37 years and 54 years at the time of first episode of hemoptysis. Among 47 patients (24.7 %) who experienced rebleeding after BAE during the median follow-up period of 13.9 months [interquartile range (IQR) 2.3-36.0 months], bleeding recurred in 12 patients (6.3 %) within 1 month and in 15 patients (7.9 %) after 1 year. The median non-recurrence time was 8.6 months (IQR 1.2-27.6 months). Independent predictors of rebleeding after BAE were tuberculous-destroyed lung [hazard ratio (HR) 3.0; 95 % confidence interval (CI) 1.5-6.2; p = 0.003], the use of anticoagulant agents and/or antiplatelet agents (HR 2.6; 95 % CI 1.1-5.8; p = 0.022), underlying chronic liver disease (HR 2.7; 95 % CI 1.1-4-6.9; p = 0.033), elevated pre-BAE C-reactive protein (CRP) (mg/dL) (HR 2.4; 95 % CI 1.0-5.5; p = 0.048), and the existence of fungal ball (HR 2.1; 95 % CI 1.0-4.3; p = 0.050). CONCLUSIONS: The risk of rebleeding after BAE in active or inactive PTB was high, particularly in patients with tuberculous-destroyed lung, chronic liver disease, the use of anticoagulant agents and/or antiplatelet agents, elevated pre-BAE CRP, and the existence of fungal ball.

The effectiveness of real-time PCR assay, compared with microbiologic results for the diagnosis of pulmonary tuberculosis.

BACKGROUND: The incidence of tuberculosis (TB) in Korea is relatively high compared to the other Organisation for Economic Co-operation and Development (OECD) countries, with a prevalence of 71 per 100,000 in 2012, although the incidence is declining. Real-time polymerase chain reaction (PCR) has been introduced for the rapid diagnosis of TB. Recently, its advantage lies in higher sensitivity and specificity for the diagnosis of TB. This study evaluated the clinical accuracy of real-time PCR using respiratory specimens in a clinical setting. METHODS: Real-time PCR assays using sputum specimens and/or bronchoscopic aspirates from 2,877 subjects were reviewed retrospectively; 2,859 subjects were enrolled. The diagnosis of TB was determined by positive microbiology, pathological findings of TB in the lung and pleura, or clinical suspicion of active TB following anti-TB medication for more than 6 months with a favorable response. RESULTS: Sensitivity, specificity, and accuracy were 44%, 99%, and 86% from sputum, and 65%, 97%, and 87% from bronchoscopic aspirates, respectively. For overall respiratory specimens, sensitivity was 59%, specificity was 98%, and accuracy increased to 89%. CONCLUSION: Positivity in real-time PCR using any respiratory specimens suggests the possibility of active TB in clinically suspected cases, guiding to start anti-TB medication. Real-time PCR from selective bronchoscopic aspirates enhances the diagnostic yield much more when added to sputum examination.

Evaluation of postoperative change in lung volume in adolescent idiopathic scoliosis: Measured by computed tomography.

BACKGROUND: Change in total lung volume after surgical correction in adolescent idiopathic scoliosis (AIS), measured by computed tomography (CT), has not been studied previously. The primary objective of this study was to measure the change in lung volume between pre and postoperative AIS using low-dose CT and secondary objective was to investigate its relationship to postoperative pulmonary complications. MATERIALS AND METHODS: 55 AIS patients underwent surgery for correction and fusion using a posterior only approach and pedicle screws. Pre and postoperative lung volumes were measured using a 3-dimensional (3D) whole spine CT (low dose protocol: Tube current, 60 mA; tube voltage 120 kV). Postoperative low dose CT was undertaken at 4 weeks after operation to evaluate the acute changes of postoperative lung volumes and pulmonary complications. The software that was used recognizes the "air density shade" of the lung and the volume of every section of the lung. The software then automatically calculates total lung volume by summation of all section volumes. The relationships between postoperative pulmonary complications and changes in lung volume on low dose CT as well as preoperative forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) were calculated using logistic regression analysis. RESULTS: There was a decrease of 12% ± 23.2% in total lung volume postoperatively on 3D low dose CT (P < 0.001). Thirteen patients had increased lung volume while 42 had decreased lung volume postoperatively. Pulmonary complications were treated without severe sequale. Lung volume increased by 19.65% ± 19.84% in 13 patients and decreased by 21.85% ± 13.32% in 42 patients (P = 0.647). Lung volume was increased in patients whose preoperative lung volume, FEV1 and FVC were lower than in patients whose values were higher (r = -0.273, -0.291 and - 0.348; P = 0.044, 0.045 and 0.015, respectively). Postoperative lung volume was also increased when intraoperative fluid administration was larger and operative time was longer (r = 0.354, 0.417 and P = 0.008, 0.002, respectively). There was a statistically significant negative correlation in the change of lung volume in female patients when compared with male patients (r = -0.294, P = 0.03). CONCLUSION: Patients with AIS who have preoperative reduced lung volumes or lung functions can achieve further increased lung volume after surgical correction. Pulmonary complications during perioperative period were mostly treated with proper management without severe sequale. Therefore, although surgery for AIS is considered to be a high risk procedure, we can recommend to correct spine deformity in patients with severe AIS in order to improve lung function and long term prognosis.

Standard chest CT using combined automated tube potential selection and iterative reconstruction: image quality and radiation dose reduction.

OBJECTIVE: To evaluate the image quality and radiation dose reduction of chest computed tomography (CT) using combined automated tube potential selection (ATPS) and iterative reconstruction (IR). MATERIALS AND METHODS: Image quality and radiation dose were compared between conventional contrast-enhanced chest CT using 120 kVp and filtered back projection (Protocol A) and CT using ATPS and IR (Protocol B) in 43 patients. RESULTS: The effective radiation dose was 3.6 ± 0.4 mSv for Protocol A and 2.2 ± 0.6 mSv for Protocol B (mean dose reduction, 39.7%). Protocol B showed diagnostic image quality in all patients. CONCLUSION: ATPS and IR allows for radiation dose reduction while maintaining diagnostic image quality.

The impact of low subcutaneous fat in patients with nontuberculous mycobacterial lung disease.

BACKGROUND: Nontuberculous mycobacteria (NTM) are pathogens that cause chronic respiratory disease, even in immunocompetent patients. We hypothesized that low subcutaneous fat is a predisposing factor for NTM lung disease. METHODS: Following a retrospective review of medical records from between 2005 and 2012, a total of 148 patients with NTM lung disease and 142 age- and sex-matched controls were enrolled. We evaluated subcutaneous fat using chest computed tomography (CT) scans at the midpole level of the left kidney. RESULTS: The median age of the patients was 62 years and 60.8 % were female. Approximately 71 % were classified into a nodular bronchiectatic group. The patient group had significantly less subcutaneous fat than the control group (39.3 vs. 53.0 cm(2), p = 0.001). Patients with both localized disease (43.5 vs. 53.0 cm(2), p = 0.042) and extensive disease (35.9 vs. 53.0 cm(2), p < 0.0001) had less subcutaneous fat compared with the control group. No difference in subcutaneous fat was observed with respect to the increasing bacterial load in sputum (p = 0.246). In 20 patients with prominent disease progression during the follow-up period, no significant difference was observed between subcutaneous fat at the initial diagnosis and that at the follow-up CT (36.2 vs. 42.0 cm(2), p = 0.47). CONCLUSION: Our results suggest that lower subcutaneous fat may contribute to host susceptibility to NTM lung disease.

Image quality assessment of ultra low-dose chest CT using sinogram-affirmed iterative reconstruction.

OBJECTIVES: To assess the image quality of ultra-low-dose computed tomography (ULDCT) using sinogram-affirmed iterative reconstruction (SAFIRE) compared to reduced dose CT (RDCT). METHODS: Eighty-one consecutive patients underwent non-enhanced ULDCT using 80 kVp and 30 mAs and contrast-enhanced RDCT using automated tube potential selection and tube current modulation. CT images were reconstructed with SAFIRE. Image noise and subjective image quality of normal structures and various pulmonary lesions were assessed. RESULTS: The mean effective doses were 0.29 ± 0.03 and 2.88 ± 1.11 mSv for ULDCT and RDCT, respectively. ULDCT had significantly higher noise (p < 0.001). Image quality of five normal structures was diagnostic in 91.1 % of ULDCT and 100 % of RDCT. With ULDCT, the frequencies of non-diagnostic image quality were 2.0 (1/50), 4.6 (13/280), 25.5 (14/55), and 40.0 (8/20)% for BMIs of < 20, 20-25, 25-30, and >30. In the assessment of pulmonary lesions, non-diagnostic image quality was observed for 11.2 % of all lesions, 60.9 % of decreased attenuation (significantly more frequent for upper lung lesions), and 23.5 % of ground-glass nodules. CONCLUSION: ULDCT generates diagnostic images in patients with a BMI ≤25, but is of limited use for lesions with decreased attenuation, ground-glass nodules, or those located in the upper lobe. KEY POINTS: • Iterative reconstruction enables ultra-low-dose CT (ULDCT) with very low radiation doses. • Image quality of ULDCT depends on the patient body mass index (BMI). • Selection of kVp and mAs depends on both BMI and lesion type. • Diagnosis of pulmonary emphysema or ground-glass nodules requires higher radiation doses.