Low Attenuation Area Research Articles

Early thrombus formation including hypo-attenuated leaflet thrombosis after surgical bioprosthetic aortic valve replacement.

To assess the occurrence, predictors, and outcomes of hypo-attenuated leaflet thickening (HALT) and thrombus outside the prosthetic valve following surgical aortic valve replacement. A total of 118 patients underwent surgical aortic valve replacement with bioprosthetic valves between July 2020 and June 2022. Sixty-two (52.5%) patients, which is a fairly high number of patients, underwent cardiac computed tomography and transthoracic echocardiography one week after surgery. Patients were divided into two groups, those with HALT (n = 14) and those without HALT (n = 48). Of the 62 patients who underwent cardiac computed tomography, HALT was observed in 14 (22.5%) patients during the very early postoperative phase. Reduced leaflet motion was observed in two of the 14 patients. The low-attenuation areas were located outside the prosthetic valve in 10 cases (71.4%) in the HALT group and in 14 cases (29.2%) in the non-HALT group. More than 50% of patients (57.1%) with HALT and 79.2% without HALT were administered warfarin. Neither in-hospital deaths nor postoperative thromboembolic events were observed during hospitalization. No patient had a mean pressure gradient > 20mmHg in either group. HALT was observed in one-fifth of the cases after surgical aortic valve replacement during the very early postoperative phase in an institution wherein administration of continuous heparin infusion after surgery is a standard practice. HALT did not affect the early prognosis or incidence of cerebral infarction.

A systematic assessment and optimization of photon-counting CT for lung density quantifications.

Photon-counting computed tomography (PCCT) has recently emerged into clinical use; however, its optimum imaging protocols and added benefits remains unknown in terms of providing more accurate lung density quantification compared to energy-integrating computed tomography (EICT) scanners. To systematically assess the performance of a clinical PCCT scanner for lung density quantifications and compare it against EICT. This cross-sectional study involved a retrospective analysis of subjects scanned (August-December 2021) using a clinical PCCT system. The influence of altering reconstruction parameters was studied (reconstruction kernel, pixel size, slice thickness). A virtual CT dataset of anthropomorphic virtual subjects was acquired to demonstrate the correspondence of findings to clinical dataset, and to perform systematic imaging experiments, not possible using human subjects. The virtual subjects were imaged using a validated, scanner-specific CT simulator of a PCCT and two EICT (defined as EICT A and B) scanners. The images were evaluated using mean absolute error (MAE) of lung and emphysema density against their corresponding ground truth. Clinical and virtual PCCT datasets showed similar trends, with sharper kernels and smaller voxel sizes increasing percentage of low-attenuation areas below -950 HU (LAA-950) by up to 15.7±6.9% and 11.8±5.5%, respectively. Under the conditions studied, higher doses, thinner slices, smaller pixel sizes, iterative reconstructions, and quantitative kernels with medium sharpness resulted in lower lung MAE values. While using these settings for PCCT, changes in the dose level (13 to 1.3 mGy), slice thickness (0.4 to 1.5mm), pixel size (0.49 to 0.98mm), reconstruction technique (70keV-VMI to wFBP), and kernel (Qr48 to Qr60) increased lung MAE by 15.3±2.0, 1.4±0.6, 2.2±0.3, 4.2±0.8, and 9.1±1.6 HU, respectively. At the optimum settings identified per scanner, PCCT images exhibited lower lung and emphysema MAE than those of EICT scanners (by 2.6±1.0 and 9.6±3.4 HU, compared to EICT A, and by 4.8±0.8 and 7.4±2.3 HU, compared to EICT B). The accuracy of lung density measurements was correlated with subjects' mean lung density (p<0.05), measured by PCCT at optimum setting under the conditions studied. Photon-counting CT demonstrated superior performance in density quantifications, with its influences of imaging parameters in line with energy-integrating CT scanners. The technology offers improvement in lung quantifications, thus demonstrating potential toward more objective assessment of respiratory conditions.

High-Resolution 3D QP and QS Models of the Middle Eastern Boundary of the Sichuan–Yunnan Rhombic Block: New Insight into Implication for Seismogenesis

Abstract The eastern boundary of the Sichuan–Yunnan rhombic block (EB-SYRB) has complex structures and strong seismicity. Although multiple 3D high-resolution velocity models have been constructed for this region, its seismogenic environment has been controversial. Seismic wave attenuation (inversely proportional to Q) describes the anelastic properties of the Earth’s medium, and is more sensitive to changes in subsurface fluid and temperature than seismic wave velocity. Based on the data of a long-term dense array in downstream of the Jinsha River, this article uses local earthquake tomography to obtain 3D QP and QS models of the middle EB-SYRB with the highest resolution to date, improving the lateral resolution of the Q model from 100 km to 5–10 km and the depth resolution from 10 to 2 km. Combined with the existing high-resolution velocity and resistivity models and geochemical observation results, we can comprehensively understand the medium structure and the seismogenesis in the study area. The results show that the high-attenuation characteristics in the shallow layer of the Xiaojiang fault zone and the Zemuhe fault zone (within a depth of ∼5 km) are consistent with the topographic relief and the distribution of hot springs, which reveals the Quaternary sedimentary characteristics of the basins and the presence of shallow fluids in the fault zone. The columnar high-attenuation anomaly beneath Huize reveals the fluid channel created by deep melting. The Ludian earthquake sequence occurred in a prominent low-attenuation area, which is favorable for stress accumulation and has a seismogenic environment for strong earthquakes. The high attenuation near the southwest end of the Huize fault is closely related to the Huize earthquake cluster, which is driven by fluids in the upper crust.

Thyroid abscess associated with thyrotoxicosis caused by Yersinia enterocolitica subsp. palearctica in a patient with follicular adenoma of the thyroid gland

BackgroundYersinia enterocolitica is a gram-negative zoonotic bacterial pathogen that is typically transmitted via the fecal-oral route. The most common clinical manifestation of a Y. enterocolitica infection is self-limited gastroenteritis. Although various extraintestinal manifestations of Y. enterocolitica infection have been reported, there are no reports of thyroid abscesses.Case presentationAn 89-year-old Japanese man with follicular adenoma of the left thyroid gland was admitted to our hospital with a 2-day history of fever and left neck pain. Laboratory tests revealed low levels of thyroid stimulating hormone and elevated levels of free thyroxine 4. Contrast-enhanced computed tomography showed low-attenuation areas with peripheral enhancement in the left thyroid gland. He was diagnosed with thyroid abscess and thyrotoxicosis, and treatment with intravenous piperacillin-tazobactam was initiated after collecting blood, drainage fluid, and stool samples. The isolated Gram-negative rod bacteria from blood and drainage fluid cultures was confirmed to be Y. enterocolitica. He was diagnosed with thyroid abscess and thyrotoxicosis due to be Y. enterocolitica subsp. palearctica. The piperacillin-tazobactam was replaced with levofloxacin.ConclusionWe report a novel case of a thyroid abscess associated with thyrotoxicosis caused by Y. enterocolitica subsp. palearctica in a patient with a follicular thyroid adenoma.

Quantification of diffuse parenchymal lung disease in non-small cell lung cancer patients with definitive concurrent chemoradiation therapy for predicting radiation pneumonitis.

We sought to quantify diffuse parenchymal lung disease (DPLD) extent using quantitative computed tomography (CT) analysis and to investigate its association with radiation pneumonitis (RP) development in non-small cell lung cancer (NSCLC) patients receiving definitive concurrent chemoradiation therapy (CCRT). A total of 82 NSCLC patients undergoing definitive CCRT were included in this prospective cohort study. Pretreatment CT scans were analyzed using quantitative CT analysis software. Low-attenuation area (LAA) features based on lung density and texture features reflecting interstitial lung disease (ILD) were extracted from the whole lung. Clinical and dosimetric factors were also evaluated. RP development was assessed using the Common Terminology Criteria for Adverse Events version 5.0. Univariable and multivariable logistic regression analyses were performed to identify independent risk factors for grade ≥3 (≥GR3) RP. RP was identified in 68 patients (73.9%), with nine patients (10.9%) experiencing ≥GR3 RP. Univariable logistic regression analysis identified excess kurtosis and high-attenuation area (HAA)_volume (cc) as significantly associated with ≥GR3 RP. Multivariable logistic regression analysis showed that the combined use of imaging features and clinical factors (forced expiratory volume in 1 second [FEV1], forced vital capacity [FVC], and CHEMO regimen) demonstrated the best performance (area under the receiver operating characteristic curve = 0.924) in predicting ≥GR3 RP. Quantified imaging features of DPLD obtained from pretreatment CT scans would predict the occurrence of RP in NSCLC patients undergoing definitive CCRT. Combining imaging features with clinical factors could improve the accuracy of the predictive model for severe RP.

Quantitative CT at Follow-Up of COVID-19 Pneumonia: Relationship with Pulmonary Function Tests.

The role of quantitative chest computed tomography (CT) is controversial in the follow-up of patients with COVID-19 pneumonia. The aim of this study was to test during the follow-up of COVID-19 pneumonia the association between pulmonary function tests (PFTs) and quantitative parameters extrapolated from follow-up (FU) CT scans performed at least 6 months after COVID-19 onset. The study included patients older than 18 years old, admitted to the emergency department of our institution between 29 February 2020 and 31 December 2020, with a diagnosis of COVID-19 pneumonia, who underwent chest CT at admission and FU CT at least 6 months later; PFTs were performed within 6 months of FU CT. At FU CT, quantitative parameters of well-aerated lung and pneumonia extent were identified both visually and by software using CT density thresholds. The association between PFTs and quantitative parameters was tested by the calculation of the Spearman's coefficient of rank correlation (rho). The study included 40 patients (38% females; median age 63 years old, IQR, 56-71 years old). A significant correlation was identified between low attenuation areas% (%LAAs) <950 Hounsfield units (HU) and both forced expiratory volume in 1s/forced vital capacity (FEV1/FVC) ratio (rho -0.410, 95% CIs -0.639--0.112, p = 0.008) and %DLCO (rho -0.426, 95% CIs -0.678--0.084, p = 0.017). The remaining quantitative parameters failed to demonstrate a significant association with PFTs (p > 0.05). At follow-up, CT scans performed at least 6 months after COVID-19 pneumonia onset showed %LAAs that were inversely associated with %DLCO and could be considered a marker of irreversible lung damage.

Computer-assisted evaluation of small airway disease in CT scans of Iran-Iraq war victims of chemical warfare by a locally developed software: comparison between different quantitative methods

ObjectiveDiagnosis of small airway disease on computed tomography (CT) scans is challenging in patients with a history of chemical warfare exposure. We developed a software package based on different methodologies to identify and quantify small airway disease in CT images. The primary aim was to identify the best automatic methodology for detecting small airway disease in CT scans of Iran-Iraq War victims of chemical warfare.MethodsThis retrospective case–control study enrolled 46 patients with a history of chemical warfare exposure and 27 controls with inspiratory/expiratory (I/E) CT scans and spirometry tests. Image data were automatically segmented, and inspiratory images were registered into the expiratory images' frame using the locally developed software. Parametric response mapping (PRM) and air trapping index (ATI) mapping were performed on the CT images. Conventional QCT methods, including expiratory/inspiratory mean lung attenuation (E/I MLA) ratio, normal density E/I (ND E/I) MLA ratio, attenuation volume Index (AVI), %low attenuation areas (LAA) < -856 in exhale scans, and %LAA < -950 in inhale scans were also computed. QCT measurements were correlated with spirometry results and compared across the two study groups.ResultsThe correlation analysis showed a significant negative relationship between three air trapping (AT) measurements (PRM, ATI, and %LAAExp < -856) and spirometry parameters (Fev1, Fvc, Fev1/Fvc, and MMEF). Moreover, %LAAExp < -856 had the highest significant negative correlation with Fev1/Fvc (r = -0.643, P-value < 0.001). Three AT measurements demonstrated a significant difference between the study groups. The E/I ratio was also significantly different between the two groups (P-value < 0.001). Binary logistic regression models showed PRMFsad, %LAAExp < -856, and ATI as significant and strong predictors of the study outcome. Optimal cut-points for PRMFsad = 19%, %LAAExp < -856 = 23%, and ATI = 27% were identified to classify the participants into two groups with high accuracy.ConclusionQCT methods, including PRM, ATI, and %LAAExp < -856 can greatly advance the identification and quantification of SAD in chemical warfare victims. The results should be verified in well-designed prospective studies involving a large population.

Quantitative emphysema on computed tomography imaging of chest is a risk factor for prognosis of esophagectomy: A retrospective cohort study.

The low attenuation area percentage (LAA%) is gaining popularity. LAA% is an index of quantitative emphysema on computed tomography (CT) imaging of the chest. This study aims to retrospectively investigate whether preoperative LAA% is associated with postoperative prognosis in patients with esophageal cancer who were scheduled for esophagectomy. From January 2016 to March 2020, 105 patients with esophageal cancer underwent esophagectomy via right thoracotomy and neoadjuvant chemotherapy. A Synapse Vincent volume analyzer (Fujifilm Medical, Tokyo, Japan) was used for measurement. The software automatically quantified LAA% using a threshold of less than - 950 Hounsfield units on CT images of lung regions. Cox proportional hazard analyses were performed in univariable and multivariable forms. Estimates of the receiver operating curve are used to determine the cutoff value for death of LAA%, and the binary value is then inserted into Cox proportional hazard analyses. The preoperative LAA% cutoff value was ≥ 6.3%. Patients with a preoperative LAA% ≥6.3% had a significantly worse prognosis than those with a preoperative LAA% of < 6.3%. LAA% ≥6.3% (hazard ratio: 6.76; 95% confidence interval: 2.56-17.90, P < .001) was the most influential preoperative factor for overall survival after esophagectomy in multivariate Cox proportional hazard analyses. LAA% is one of the preoperative risk factors for survival after esophagectomy and an indicator of lung condition using routinely performed preoperative CT images. We quantified the extent of preoperative emphysema in patients with esophageal cancer, who were scheduled for surgery, and for the first time, reported LAA% as one of the preoperative risk factors for survival after esophagectomy.

Evaluating Tissue Heterogeneity in the Radiologically Normal-Appearing Tissue in IPF Compared to Healthy Controls

Idiopathic Pulmonary Fibrosis (IPF) is a progressive interstitial lung disease characterised by heterogeneously distributed fibrotic lesions. The inter- and intra-patient heterogeneity of the disease has meant that useful biomarkers of severity and progression have been elusive. Previous quantitative computed tomography (CT) based studies have focussed on characterising the pathological tissue. However, we hypothesised that the remaining lung tissue, which appears radiologically normal, may show important differences from controls in tissue characteristics. Quantitative metrics were derived from CT scans in IPF patients (N=20) and healthy controls with a similar age (N=59). An automated quantitative software (CALIPER, Computer-Aided Lung Informatics for Pathology Evaluation and Rating) was used to classify tissue as normal-appearing, fibrosis, or low attenuation area. Densitometry metrics were calculated for all lung tissue and for only the normal-appearing tissue. Heterogeneity of lung tissue density was quantified as coefficient of variation and by quadtree. Associations between measured lung function and quantitative metrics were assessed and compared between the two cohorts. All metrics were significantly different between controls and IPF (p<0.05), including when only the normal tissue was evaluated (p<0.04). Density in the normal tissue was 14% higher in the IPF participants than controls (p<0.001). The normal-appearing tissue in IPF had heterogeneity metrics that exhibited significant positive relationships with the percent predicted diffusion capacity for carbon monoxide. We provide quantitative assessment of IPF lung tissue characteristics compared toa healthy control group of similar age. Tissue that appears visually normal in IPF exhibits subtle but quantifiable differences that are associated with lung function and gas exchange.

The association of chest computed tomography-defined visual emphysema and prognosis in patients with nonsmall cell lung cancer.

Although computed tomography (CT)-defined emphysema is considered a predictor of lung cancer risk, it is not fully clear whether CT-defined emphysema is associated with the prognosis of lung cancer. We aimed to assess the clinical impact of CT-defined emphysema on the survival of lung cancer. In the prospective cohort study of nonsmall cell lung cancer (NSCLC), the correlation between CT-defined emphysema and clinical variables was analysed. A multivariable Cox regression model was built to assess the association between CT-defined emphysema and overall survival (OS) for up to 8.8 years. The differences in survival analyses were derived by Kaplan-Meier analysis and log-rank testing. Low attenuation area (LAA%) was defined as the per cent of voxels below -950 HU. 854 patients were included and CT-defined emphysema was present in 300 (35.1%) at diagnosis. Epidermal growth factor receptor (EGFR) wild-type (OR 1.998; p<0.001) and anaplastic lymphoma kinase (ALK) wild-type (OR 2.277; p=0.004) were associated with CT-defined emphysema. CT-defined emphysema remained a significant predictor of prognosis adjusting for age, sex, smoking history, tumour histology and Eastern Cooperative Oncology Group Performance Status (ECOG PS), whether in I-IIIA stage (adjusted hazard ratio (HR) 1.745; p=0.017) or in IIIB-IV stage (adjusted HR 1.291; p=0.022). Stratified analyses showed that OS rate among the driver oncogene groups with different CT-defined emphysema status differed significantly (log-rank p<0.001). Furthermore, patients with centrilobular emphysema (CLE) with LAA% >17% displayed poorer survival than those with LAA% ≤17% (median 432 versus 670 days; HR 1.564; p=0.020). CT-defined emphysema, especially CLE with LAA%>17%, is an independent predictor of NSCLC prognosis. Moreover, prospective studies are needed to further explore this association.

Preoperative CT findings and prognosis of pulmonary sarcomatoid carcinoma: comparison with conventional NSCLC of similar tumor size

BackgroundPulmonary sarcomatoid carcinoma (PSC) is a rare subtype of non-small cell lung cancer (NSCLC) but differs in terms of treatment strategies compared with conventional-NSCLC (c-NSCLC). However, preoperative CT differentiation between PSC and c-NSCLC remains a challenge. This study aimed to explore the CT findings and prognosis of PSC compared with c-NSCLC of similar tumor size.MethodsClinical data and CT findings of 31 patients with PSC and 87 patients with c-NSCLC were retrospectively analyzed. Clinical data included sex, age, and smoking history. CT findings included tumor size, tumor location, calcification, vacuole/cavity, pleural invasion, mean CT value, and low-attenuation area (LAA) ratio. Kaplan‒Meier curves and log-rank tests were used for survival analysis. A Cox regression model was constructed to evaluate prognostic risk factors associated with overall survival (OS). The Spearman correlation among clinicoradiological outcomes were analyzed.ResultsThe mean tumor size of PSC and c-NSCLC were both 5.1 cm. The median survival times of PSC and c-NSCLC were 8 months and 34 months, respectively (P < 0.001). Calcification and vacuoles/cavities were rarely present in PSC. Pleural invasion occurred in both PSC and c-NSCLC (P = 0.285). The mean CT values of PSC and c-NSCLC on plain scan (PS), arterial phase (AP), and venous phase (VP) were 30.48 ± 1.59 vs. 36.25 ± 0.64 Hu (P = 0.002), 43.26 ± 2.96 vs. 58.71 ± 1.65 Hu (P < 0.001) and 50.26 ± 3.28 vs. 64.24 ± 1.86 Hu (P < 0.001), the AUCs were 0.685, 0.757 and 0.710, respectively. Compared to c-NSCLC, PSC had a larger LAA ratio, and the AUC was 0.802, with an optimal cutoff value of 20.6%, and the sensitivity and specificity were 0.645 and 0.862, respectively. Combined with the mean CT value and LAA ratio, AP + VP + LAA yielded the largest AUC of 0.826. The LAA ratio were not independent risk factors for PSC in this study. LAA ratio was negatively correlated with PS (r = -0.29), AP (r = -0.58), and VP (r = -0.66). LAA showed a weak positive correlation with tumor size(r = 0.27).ConclusionsPSC has a poorer prognosis than c-NSCLC of similar tumor size. The mean CT value and LAA ratio contributes to preoperative CT differentiation of PSC and c-NSCLC.

Percentage of low attenuation area on computed tomography detects chronic lung allograft dysfunction, especially bronchiolitis obliterans syndrome, after bilateral lung transplantation.

The percentage of low attenuation area (%LAA) on computed tomography (CT) is useful for evaluating lung emphysema, and higher %LAA was observed in patients with chronic lung allograft dysfunction (CLAD). This study investigated the relationship between the %LAA and the development of CLAD after bilateral lung transplantation (LT). We conducted a single-center retrospective study of 75 recipients who underwent bilateral LT; the recipients were divided into a CLAD group (n=30) and a non-CLAD group (n=45). The %LAA was calculated using CT and compared between the two groups from 4 years before to 4 years after the diagnosis of CLAD. The relationships between the %LAA and the percent baseline values of the pulmonary function test parameters were also calculated. The %LAA was significantly higher in the CLAD group than in the non-CLAD group from 2 years before to 2 years after the diagnosis of CLAD (P<.05). In particular, patients with bronchiolitis obliterans syndrome (BOS) exhibited significant differences even from 4 years before to 4 years after diagnosis (P<.05). Significant negative correlations between the %LAA and the percent baseline values of the forced expiratory volume in 1 s (r=-.36, P=.0031), the forced vital capacity (r=-.27, P=.027), and the total lung capacity (r=-.40, P<.001) were seen at the time of CLAD diagnosis. The %LAA on CT was associated with the development of CLAD and appears to have the potential to predict CLAD, especially BOS, after bilateral LT.

Association Between Insulin Resistance and Myosteatosis Measured by Abdominal Computed Tomography.

Ectopic fat deposition in skeletal muscle, termed myosteatosis, is a key factor in developing insulin resistance. This work aimed to evaluate the association between insulin resistance and myosteatosis in a large Asian population. A total of 18 251 participants who had abdominal computed tomography were included in this cross-sectional study. Patients were categorized into 4 groups according to quartiles of Homeostatic Model Assessment for Insulin Resistance (HOMA-IR). The total abdominal muscle area (TAMA) at the L3 vertebral level was segmented into normal-attenuation muscle area (NAMA), low-attenuation muscle area (LAMA), and intermuscular adipose tissue (IMAT). The absolute values of TAMA, NAMA, LAMA, and IMAT and the ratios of NAMA/BMI, LAMA/BMI, and NAMA/TAMA were used as myosteatosis indices. The absolute values of TAMA, NAMA, LAMA, and IMAT appeared to increase with higher HOMA-IR levels, and LAMA/BMI showed a similar upward trend. Meanwhile, the NAMA/BMI and NAMA/TAMA index showed downward trends. As HOMA-IR levels increased, the odds ratios (ORs) of the highest quartile of NAMA/BMI and NAMA/TAMA index decreased and that of LAMA/BMI increased. Compared with the lowest HOMA-IR group, the adjusted ORs (95% CI) in the highest HOMA-IR group for the lowest NAMA/TAMA quartile were 0.414 (0.364-0.471) in men and 0.464 (0.384-0.562) in women. HOMA-IR showed a negative correlation with NAMA/BMI (r = -0.233 for men and r = -0.265 for women), and NAMA/TAMA index (r = -0.211 for men and r = -0.214 for women), and a positive correlation with LAMA/BMI (r = 0.160 for men and r = 0.119 for women); P was less than .001 for all. In this study, a higher HOMA-IR level was significantly associated with a high risk of myosteatosis.

Differential impacts between fat mass index and fat-free mass index on patients with COPD

BackgroundDifferences in the clinical impacts of fat mass index (FMI) and fat-free mass index (FFMI) remain unclear in patients with chronic obstructive pulmonary disease (COPD). We hypothesized that FMI and FFMI have different impacts on 1) emphysema and 2) pulmonary function and health-related quality of life of COPD patients. MethodsPatients with COPD (n = 228), enrolled in a multicenter prospective 3-year cohort were classified into four groups based on baseline median FMI and FFMI values. Emphysema assessed as the ratio of low attenuation area to total lung volume (LAA%) on computed tomography, pulmonary function, and health-related quality of life assessed using the St. George's Respiratory Questionnaire (SGRQ) were compared. ResultsThe four groups had statistically significant differences in LAA%, pulmonary function, and SGRQ scores. The Low FMI Low FFMI group exhibited the highest LAA%, lowest pulmonary function, and worst SGRQ scores among the four groups. In addition, these differences were consistent over 3 years. Multivariate analysis showed that low FMI was associated with high LAA%, low inspiratory capacity/total lung capacity (IC/TLC), and carbon monoxide transfer coefficient (KCO). In contrast, low FFMI was associated with these factors as well as worse SGRQ scores. ConclusionFMI and FFMI have different effects on the clinical manifestations of COPD. Both low fat and muscle mass contributed to severe emphysema, whereas only low muscle mass contributed to worse health-related quality of life in patients with COPD.

1699-P: Association between Insulin Resistance and Myosteatosis Measured by Abdominal Computed Tomography

Background: Ectopic fat deposition in skeletal muscle, termed myosteatosis, is a key factor in developing insulin resistance. We aimed to evaluate the association between insulin resistance and myosteatosis in a large Asian population. Methods: A total of 18,251 participants who had abdominal computed tomography from 2012 to 2013 were included. The total abdominal muscle area (TAMA) at the L3 vertebral level was segmented into normal-attenuation muscle area (NAMA), low-attenuation muscle area (LAMA), and intramuscular adipose tissue (IMAT). The ratios of NAMA/BMI, LAMA/BMI, and NAMA/TAMA were used as myosteatosis indices. Results: NAMA/BMI and NAMA/TAMA index showed downward trends with higher HOMA-IR levels, while LAMA/BMI showed upward trends. As HOMA-IR levels increased, the odds ratios (ORs) of the highest quartile of NAMA/BMI and NAMA/TAMA index decreased and that of LAMA/BMI increased. Compared with the lowest HOMA-IR group, the adjusted ORs (95% confidence intervals [CI]) in the highest HOMA-IR group for the lowest NAMA/TAMA quartile were 0.414 (0.364-0.471) in males and 0.464 (0.384-0.562) in females. HOMA-IR showed a negative correlation with NAMA/TAMA index (r = -0.211 for men and r = -0.214 for women, p &amp;lt;0.001 for both). Conclusion: A higher HOMA-IR level was significantly associated with a high risk of myosteatosis. Disclosure M.Kim: None. Y.Cho: None. H.Jung: None. C.Jung: None. J.Won: None. J.Park: None. H.Kim: None. W.Lee: None.

Association between Mortality and Lung Low Attenuation Areas in NSCLC Treated by Surgery.

to test the association with overall survival (OS) of low attenuation areas (LAAs) quantified by staging computed tomography (CT) of patients who underwent radical surgery for nonsmall-cell lung cancer (NSCLC). patients who underwent radical surgery for NSCLC at our institution between 1 January 2017 and 30 November 2021 were retrospectively evaluated. Patients who performed staging or follow-up CTs in other institutions, who received lung radiotherapy or chemotherapy, and who underwent previous lung surgery were excluded. At staging and 12-months follow-up CT, LAAs defined as voxels <-950 Hounsfield units, were extracted by software. The percent of LAAs relative to whole-lung volume (%LAAs) and the ratio between LAAs in the lobe to resect and whole-lung LAAs (%LAAs lobe ratio) were calculated. Cox proportional hazards regression analysis was used to test the association between OS and LAAs. the final sample included 75 patients (median age 70 years, IQR 63-75 years; females 29/75, 39%). It identified a significant association with OS for pathological stage III (HR, 6.50; 95%CI, 1.11-37.92; p = 0.038), staging CT %LAAs ≥ 5% (HR, 7.27; 95%CI, 1.60-32.96; p = 0.010), and staging CT %LAA lobe ratio > 10% (HR, 0.24; 95%CI 0.05-0.94; p = 0.046). in patients with NSCLC who underwent radical surgery, a %LAAs ≥ 5% and a %LAA lobe ratio > 10% at staging CT are predictors, respectively, of shorter and longer OS. The LAA ratio to the whole lung at staging CT could be a critical factor to predict the overall survival of the NSCLC patients treated by surgery.

Reverse Platypnea–Orthodeoxia with Atrial Septal Defect and Diffuse Pulmonary Arteriovenous Fistulae in Hepatopulmonary Syndrome

A 69-year-old male with a long-standing diagnosis of interstitial lung disease and on domiciliary oxygen therapy was evaluated by echocardiography. His supine oxygen saturation ranged between 77% and 86% and upright oxygen saturation was 93%–94%. Two-dimensional transthoracic echocardiography showed a secundum atrial septal defect of 15 mm diameter with left-to-right shunting but without dilatation of right-sided chambers. Air bubble contrast echocardiography showed no air bubbles crossing the atrial septum but bubbles appeared in left-sided chambers through pulmonary veins after five cardiac cycles indicating intra-pulmonary shunting. Computed tomography of the chest demonstrated a mosaic pattern of the lung parenchyma, characterized by the presence of alternating geographic areas of low attenuation with regions of relatively increased attenuation typical of diffuse pulmonary arteriovenous fistulae. This is a rare case of reverse platypnea-orthodexia with possible contribution of two different pathophysiologic mechanisms but precise mechanism remains elusive.

Lung Volume Reduction in Patients with Severe Emphysema: Bronchoscopic Lobar versus Surgical Tailored Treatment

Abstract Background Bronchoscopic lung volume reduction (BLVR) with valves excludes one whole lobe while lung volume reduction surgery (LVRS) allows tailored treatment by resection of only heterogeneous, hardly perfused target areas. Aims We hypothesize that by (bilateral) LVRS, more areas of low attenuation (LAA, ≤ - 950 houndsfield units) can be resected more precisely, thus generating more functional improvement than BLVR. Methods Empysema patients treated with BLVR and LVRS at our institution between August 2019 and October 2020 were collected prospectively and analyzed retrospectively. LVRS responders were defined as patients with a postoperative improvement of at least 10% in FEV1 in combination with 10% delta in 6-minute-walking-distance (6MWD) or residual volume (RV) or diffusion capacity (DLCO), within the BLVR group additionally with a chest CT scan proven target lobe atelectasis. We performed LAA measurement in preoperative CT scan and 3 months (LVRS) or 1 month (BLVR) postoperatively. Functional improvement as well as LAA reduction was measured in each group and the groups compared with each other. Results 29 patients underwent LVRS, 19 were responders (5 bilateral LVRS, 14 unilateral), 3 were lost for follow up. Within the BLVR group (n=29), 18 were responders. In bilateral LVRS, improvement of 6MWD and FEV1 was significantly higher than in BLVR, accompanied by a significantly higher LAA-reduction (22.18 vs 9.54, p=0.009). In unilateral LVRS, LAA-reduction was not significantly higher (12.06 vs 9.54, p=0.267), while 6MWD and FEV1 still showed a higher postoperative improvement. RV reduction and DLCO improvement did not differ significantly between the groups. Conclusions LVRS might lead to significantly more functional improvement than BLVR with valves, maybe due to more resected LAA, especially in bilateral surgery. This concept may justify favoring primary bilateral LVRS over BLVR with valves in bilateral heterogeneous emphysema.

Low-quality muscle mass rather than normal-quality muscle mass determines fibrosis progression in biopsy-proven NAFLD.

Sarcopaenia is associated with advanced nonalcoholic fatty liver disease (NAFLD). However, the impact of the muscle mass categorised by muscle quality on fibrosis progression remains unclear. A total of 292 patients with biopsy-proven NAFLD who underwent serial vibration-controlled transient elastography assessments at least 1 year from baseline were selected. The skeletal muscle area (SMA) was determined on abdominal computed tomography (CT) at the third lumbar vertebra level and categorised to normal-attenuation muscle area (NAMA), low-attenuation muscle area (LAMA) and intermuscular adipose tissue (IMAT) using a muscle quality map. These SMAs were normalised by the height squared to obtain the skeletal muscle index (SMI). At baseline, as the histological fibrosis stage increased, SMINAMA decreased and SMILAMA increased (p for trend = 0.014 and p for trend <0.001, respectively), which was not significant after adjustment for age, sex and obesity. During a median follow-up of 41 months, fibrosis progression was detected in 48 out of 292 patients, and higher SMILAMA quartiles independently increased the risk of fibrosis progression in a dose-dependent manner (hazard ratio [HR] per quartile: 1.41; 95% confidence interval [CI], 1.04-1.91). The highest quartile of SMILAMA increased the risk of fibrosis progression by 3.25 times compared to the lowest quartile of SMILAMA (95% CI, 1.18-8.90). SMINAMA quartiles were not associated with the risk of fibrosis progression. Increased low-quality muscle mass, but not decreased normal-quality muscle mass, as assessed by a muscle quality map in CT, predicts fibrosis progression in patients with NAFLD.

Progression of pulmonary cysts in Birt-Hogg-Dubé syndrome: longitudinal thoracic computed tomography study with quantitative assessment

BackgroundBirt-Hogg-Dubé (BHD) syndrome is a rare autosomal dominant disorder characterized by fibrofolliculomas, renal tumors, pulmonary cysts, and recurrent pneumothorax. Pulmonary cysts are the cause of recurrent pneumothorax, which is one of the most important factors influencing patient quality of life. It is unknown whether pulmonary cysts progress with time or influence pulmonary function in patients with BHD syndrome. This study investigated whether pulmonary cysts progress during long-term follow-up (FU) by using thoracic computed tomography (CT) and whether pulmonary function declines during FU. We also evaluated risk factors for pneumothorax in patients with BHD during FU.MethodsOur retrospective cohort included 43 patients with BHD (25 women; mean age, 54.2 ± 11.7 years). We evaluated whether cysts progress by visual assessment and quantitative volume analysis using initial and serial thoracic CT. The visual assessment included the size, location, number, shape, distribution, presence of a visible wall, fissural or subpleural cysts, and air-cuff signs. In CT data obtained from a 1-mm section from 17 patients, the quantitative assessment was performed by measuring the volume of the low attenuation area using in-house software. We evaluated whether the pulmonary function declined with time on serial pulmonary function tests (PFT). Risk factors for pneumothorax were analyzed using multiple regression analysis.ResultsOn visual assessment, the largest cyst in the right lung showed a significant interval increase in size (1.0 mm/year, p = 0.0015; 95% confidence interval [CI], 0.42–1.64) between the initial and final CT, and the largest cyst in the left lung also showed significant interval increase in size (0.8 mm/year, p < 0.001, 95% CI; -0.49–1.09). On quantitative assessment, cysts had a tendency to gradually increase in size. In 33 patients with available PFT data, FEV1pred%, FEV1/FVC, and VCpred% showed a statistically significant decrease with time (p < 0.0001 for each). A family history of pneumothorax was a risk factor for the development of pneumothorax.ConclusionsThe size of pulmonary cysts progressed over time in longitudinal follow-up thoracic CT in patients with BHD, and pulmonary function had slightly deteriorated by longitudinal follow-up PFT.