Mean Attenuation Research Articles

Improved Diagnosis of Adjacent Organ Invasion of Extrahepatic Cholangiocarcinoma by Adding Arterial and Delayed Phases.

To clarify the role of dynamic computed tomography (CT) in diagnosing extrahepatic cholangiocarcinoma (eCCA) involving adjacent organs. We retrospectively analyzed patients diagnosed with eCCA in Iwate Medical University Hospital (Morioka, Japan) during January 2011-December 2021 who underwent dynamic contrast-enhanced CT before biliary intervention, surgery, or chemotherapy. For surgical cases, two radiologists independently reviewed CT images in the portal, dual (adding arterial phase), and triple (adding delayed phase) phases. The mean attenuations of the abdominal aorta, portal vein (PV), hepatic parenchyma, pancreatic parenchyma, and eCCA were measured. The biliary segment-wise longitudinal tumour extent, arterial and PV invasion, organ invasion (liver, pancreas, and duodenum), and regional lymph node metastasis were assessed on a five-point scale. Imageperformances were compared using the sensitivity, specificity, and area under the curve (AUC). We included 120 patients (mean age, 71.7 ± 8.9; 84 males). The PV and liver differed most from the bile duct tumour in the portal phase. The abdominal aorta and pancreas differed most from eCCA in the arterial phase. For 80 patients evaluated on the five-point scale, adding phases increased the AUC for pancreatic, duodenal, and arterial invasion for each observer (observer 1, 0.79-0.93, p<0.01, 0.71-0.86, p = 0.04, 0.74-0.99, p = 0.02; observer 2, 0.88-0.96, p = 0.01, 0.73-0.94, p<0.01, 0.80-0.99 p = 0.04; respectively). The AUC for biliary segment-wise longitudinal tumor extent, hepatic, and PV invasion remained unchanged with additional phases. Portal-phase information is sufficient to evaluate the segmental extent of bile duct and liver/PV invasion. Arterial- and delayed-phase information can help evaluate pancreatic, duodenal, and arterial invasion.

Optical properties of melon tissues and Monte Carlo simulation of light propagation through melon fruit

Visible/near-infrared (Vis/NIR) spectroscopy has been authenticated for quality evaluation of melon fruit. However, since melon is a multi-layered fruit with large size, the optical properties (OPs) of different tissue layers can influence the performance of the quality evaluation. Therefore, the OPs of different tissue layers (exocarp, green mesocarp and pulp) among different fruit positions (stem, equator and calyx) of 36 ‘Huanghemi’ melons were measured using single integrating sphere measurements and the light propagation through melon fruit was investigated by the Monte Carlo (MC) simulation based on the OPs. Moreover, the relationship of the OPs with microstructure and internal quality properties (soluble solids content (SSC) and moisture content) was explored. In the absorption coefficient (μa) spectra, five obvious absorption peaks for carotenoids (481 nm), chlorophyll (675 nm) and water (984, 1195 and 1423 nm) were observed. The exocarp had the highest μa values at 481 nm owing to its orange-yellow peel and the lowest μa values at 1423 nm, while the μa values of green mesocarp and pulp had no significant differences at all absorption peaks. The differences in reduced scattering coefficient (μs') spectra were obvious with a decreasing trend from the outermost (exocarp) to the innermost (pulp) layer and the stem to the calyx position in pulp layer, which mainly related to the different tissue structure. The MC simulation results indicated that the energy along the wavelength was mainly absorbed by the exocarp and green mesocarp, with a ‘diagnostic window’ appearing in 700–850 nm. As the source-detector distance increased, the mean optical pathlength and attenuation of detected photons in each tissue layer increased, while the contribution fraction to the detected diffuse reflectance signals by the exocarp, green mesocarp and pulp respectively decreased, increased and increased. To acquire more information about the pulp and ensure a good signal-to-noise ratio of the spectral signal, a source-detector distance of 7 mm with a suitable light source power would be a good choice. Furthermore, the best prediction models with good performance for SSC and moisture content were built based on the μa spectra, with the correlation coefficient of prediction (Rp) of 0.78–0.80, 0.76–0.88 and the root mean square error of prediction (RMSEP) of 0.83–0.92%, 0.70–0.93%. This study was the first attempt to measure the OPs of melon tissues and investigate the light propagation through melon fruit, which would provide a reference to develop nondestructive testing techniques or instruments for melon fruit based on Vis/NIR spectroscopy.

Relationships of pericoronary and epicardial fat measurements in male and female patients with and without coronary artery disease

IntroductionAlthough pericoronary adipose tissue (PCAT) is a component of the epicardial adipose tissue (EAT) depot, they may have different associations to coronary artery disease (CAD). We explored relationships between pericoronary adipose tissue mean attenuation (PCATMA) and EAT measurements in coronary CT angiography (CCTA) in patients with and without CAD. Material and MethodsCCTA scans of 185 non-CAD and 81 CAD patients (86.4% >50% stenosis) were included and retrospectively analyzed. PCATMA and EAT density/volume were measured and analyzed by sex, including associations with age, risk factors and tube voltage using linear regression models. ResultsIn non-CAD and CAD, mean PCATMA and EAT volume were higher in men than in women (non-CAD: −92.5 ± 10.6HU vs −96.2 ± 8.4HU, and 174.4 ± 69.1 cm3 vs 124.1 ± 57.3 cm3; CAD: −92.2 ± 9.0HU vs −97.4 ± 9.7HU, and 193.6 ± 62.5 cm3 vs 148.5 ± 50.5 cm3 (p < 0.05)). EAT density was slightly lower in men than women in non-CAD (−96.4 ± 6.3HU vs −94.4 ± 5.5HU (p < 0.05)), and similar in CAD (−98.2 ± 5.2HU vs 98.2 ± 6.4HU). There was strong correlation between PCATMA and EAT density (non-CAD: r = 0.725, p < 0.001, CAD: r = 0.686, p < 0.001) but no correlation between PCATMA and EAT volume (non-CAD: r = 0.018, p = 0.81, CAD: r = −0.055, p = 0.63). A weak inverse association was found between EAT density and EAT volume (non-CAD: r = −0.244, p < 0.001, CAD: r = −0.263, p = 0.02). In linear regression models, EAT density was significantly associated with PCATMA in both non-CAD and CAD patients independent of risk factors and tube voltage. ConclusionIn CAD and non-CAD patients, EAT density, but not EAT volume, showed significant associations with PCATMA. Compared to women, men had higher PCATMA and EAT volume independently of disease status, but similar or slightly lower EAT density. Differences in trends and relations of PCATMA and EAT by sex could indicate that personalized interpretation and thresholding is needed.

Detection of Moderate Hepatic Steatosis on Portal Venous Phase Contrast-Enhanced CT: Evaluation Using an Automated Artificial Intelligence Tool.

BACKGROUND. Precontrast CT is an established means of evaluating for hepatic steatosis; postcontrast CT has historically been limited for this purpose. OBJECTIVE. The purpose of this study was to evaluate the diagnostic performance of portal venous phase postcontrast CT in detecting at least moderate hepatic steatosis using liver and spleen attenuation measurements determined by an automated artificial intelligence (AI) tool. METHODS. This retrospective study included 2917 patients (1381 men, 1536 women; mean age, 56.8 years) who underwent a CT examination that included at least two series through the liver. Examinations were obtained from an AI vendor's data lake of data from 24 centers in one U.S. health care network and 29 centers in one Israeli health care network. An automated deep learning tool extracted liver and spleen attenuation measurements. The reference for at least moderate steatosis was precontrast liver attenuation of less than 40 HU (i.e., estimated liver fat > 15%). A radiologist manually reviewed examinations with outlier AI results to confirm portal venous timing and identify issues impacting attenuation measurements. RESULTS. After outlier review, analysis included 2777 patients with portal venous phase images. Prevalence of at least moderate steatosis was 13.9% (387/2777). Patients without and with at least moderate steatosis, respectively, had mean postcontrast liver attenuation of 104.5 ± 18.1 (SD) HU and 67.1 ± 18.6 HU (p < .001); a mean difference in postcontrast attenuation between the liver and the spleen (hereafter, postcontrast liver-spleen attenuation difference) of -7.6 ± 16.4 (SD) HU and -31.8 ± 20.3 HU (p < .001); and mean liver enhancement of 49.3 ± 15.9 (SD) HU versus 38.6 ± 13.6 HU (p < .001). Diagnostic performance for the detection of at least moderate steatosis was higher for postcontrast liver attenuation (AUC = 0.938) than for the postcontrast liver-spleen attenuation difference (AUC = 0.832) (p < .001). For detection of at least moderate steatosis, postcontrast liver attenuation had sensitivity and specificity of 77.8% and 93.2%, respectively, at less than 80 HU and 90.5% and 78.4%, respectively, at less than 90 HU; the postcontrast liver-spleen attenuation difference had sensitivity and specificity of 71.4% and 79.3%, respectively, at less than -20 HU and 87.0% and 62.1%, respectively, at less than -10 HU. CONCLUSION. Postcontrast liver attenuation outperformed the postcontrast liver-spleen attenuation difference for detecting at least moderate steatosis in a heterogeneous patient sample, as evaluated using an automated AI tool. Splenic attenuation likely is not needed to assess for at least moderate steatosis on postcontrast images. CLINICAL IMPACT. The technique could promote early detection of clinically significant nonalcoholic fatty liver disease through individualized or large-scale opportunistic evaluation.

Computed tomography and magnetic resonance imaging are potential noninvasive methods for evaluating the cisterna chyli in cats.

There is limited information on the normal appearance of the cisterna chyli (CC) in cats on CT and MRI. The aim of this retrospective study was to describe the CT and MRI characteristics of the CC in a group of cats without lymphatic system pathology. A total of 31 CT and 63 MRI images were obtained of client-owned cats between January 2017 and March 2022. The presence, location, shape, maximum width, MRI-signal intensity, mean attenuation, and contrast enhancement of the CC were recorded from CT and MRI scans. The CC was identified in all the CT scans and in 60 MRI studies. The CC was located level with the cranial mesenteric artery in 56 of 91 cases. It was crescent shaped in 34 of 54 cases. On precontrast CT images, the mean attenuation of the CC was 17 HU, and the mean postcontrast attenuation was 28 HU. On T2-weighted sequences, the CC was isointense to CSF and hyperintense to the muscles, while on T1-weighted images, it was isointense to the muscles. Contrast enhancement was variable in both techniques. CT and MRI have the potential for noninvasive evaluation of CC in cats.

Feasibility study of computed tomography texture analysis for evaluation of canine primary adrenal gland tumors.

This study aimed to investigate the feasibility of computed tomography (CT) texture analysis for distinguishing canine adrenal gland tumors and its usefulness in clinical decision-making. The medical records of 25 dogs with primary adrenal masses who underwent contrast CT and a histopathological examination were retrospectively reviewed, of which 12 had adenomas (AAs), 7 had adenocarcinomas (ACCs), and 6 had pheochromocytomas (PHEOs). Conventional CT evaluation of each adrenal gland tumor included the mean, maximum, and minimum attenuation values in Hounsfield units (HU), heterogeneity of the tumor parenchyma, and contrast enhancement (type, pattern, and degree), respectively, in each phase. In CT texture analysis, precontrast and delayed-phase images of 18 adrenal gland tumors, which could be applied for ComBat harmonization were used, and 93 radiomic features (18 first-order and 75 second-order statistics) were extracted. Then, ComBat harmonization was applied to compensate for the batch effect created by the different CT protocols. The area under the receiver operating characteristic curve (AUC) for each significant feature was used to evaluate the diagnostic performance of CT texture analysis. Among the conventional features, PHEO showed significantly higher mean and maximum precontrast HU values than ACC (p < 0.05). Eight second-order features on the precontrast images showed significant differences between the adrenal gland tumors (p < 0.05). However, none of them were significantly different between AA and PHEO, or between precontrast images and delayed-phase images. This result indicates that ACC exhibited more heterogeneous and complex textures and more variable intensities with lower gray-level values than AA and PHEO. The correlation, maximal correlation coefficient, and gray level non-uniformity normalized were significantly different between AA and ACC, and between ACC and PHEO. These features showed high AUCs in discriminating ACC and PHEO, which were comparable or higher than the precontrast mean and maximum HU (AUC = 0.865 and 0.860, respectively). Canine primary adrenal gland tumor differentiation can be achieved with CT texture analysis on precontrast images and may have a potential role in clinical decision-making. Further prospective studies with larger populations and cross-validation are warranted.

Sound speed and attenuation of human pancreas and pancreatic tumors and their influence on focused ultrasound thermal and mechanical therapies.

There is increasing interest in using ultrasound for thermal ablation, histotripsy, and thermal or cavitational enhancement of drug delivery for the treatment of pancreatic cancer. Ultrasonic and thermal modelling conducted as part of the treatment planning process requires acoustic property values for all constituent tissues, but the literature contains no data for the human pancreas. This study presents the first acoustic property measurements of human pancreatic samples and provides examples of how these properties impact a broad range of ultrasound therapies. Data were collected on human pancreatic tissue samples at physiological temperature from 23 consented patients in cooperation with a hospital pathology laboratory. Propagation of ultrasound over the 2.1-4.5MHz frequency range through samples of various thicknesses and pathologies was measured using a set of custom-built ultrasonic calipers, with the data processed to estimate sound speed and attenuation. The results were used in acoustic and thermal simulations to illustrate the impacts on extracorporeal ultrasound therapies for mild hyperthermia, thermal ablation, and histotripsy implemented with a CE-marked clinical system operating at 0.96MHz. The mean sound speed and attenuation coefficient values for human samples were well below the range of values in the literature for non-human pancreata, while the human attenuation power law exponents were substantially higher. The simulated impacts on ultrasound mediated therapies for the pancreas indicated that when using the human data instead of the literature average, there was a 30% reduction in median temperature elevation in the treatment volume for mild hyperthermia and 43% smaller volume within a 60°C contour for thermal ablation, all driven by attenuation. By comparison, impacts on boiling and intrinsic threshold histotripsy were minor, with peak pressures changing by less than 15% (positive) and 1% (negative) as a consequence of the counteracting effects of attenuation and sound speed. This study provides the most complete set of speed of sound and attenuation data available for the human pancreas, and it reiterates the importance of acoustic material properties in the planning and conduct of ultrasound-mediated procedures, particularly thermal therapies.

TotalSegmentator: Robust Segmentation of 104 Anatomic Structures in CT Images.

To present a deep learning segmentation model that can automatically and robustly segment all major anatomic structures on body CT images. In this retrospective study, 1204 CT examinations (from 2012, 2016, and 2020) were used to segment 104 anatomic structures (27 organs, 59 bones, 10 muscles, and eight vessels) relevant for use cases such as organ volumetry, disease characterization, and surgical or radiation therapy planning. The CT images were randomly sampled from routine clinical studies and thus represent a real-world dataset (different ages, abnormalities, scanners, body parts, sequences, and sites). The authors trained an nnU-Net segmentation algorithm on this dataset and calculated Dice similarity coefficients to evaluate the model's performance. The trained algorithm was applied to a second dataset of 4004 whole-body CT examinations to investigate age-dependent volume and attenuation changes. The proposed model showed a high Dice score (0.943) on the test set, which included a wide range of clinical data with major abnormalities. The model significantly outperformed another publicly available segmentation model on a separate dataset (Dice score, 0.932 vs 0.871; P < .001). The aging study demonstrated significant correlations between age and volume and mean attenuation for a variety of organ groups (eg, age and aortic volume [rs = 0.64; P < .001]; age and mean attenuation of the autochthonous dorsal musculature [rs = -0.74; P < .001]). The developed model enables robust and accurate segmentation of 104 anatomic structures. The annotated dataset (https://doi.org/10.5281/zenodo.6802613) and toolkit (https://www.github.com/wasserth/TotalSegmentator) are publicly available.Keywords: CT, Segmentation, Neural Networks Supplemental material is available for this article. © RSNA, 2023See also commentary by Sebro and Mongan in this issue.

Semaglutide therapy decreases epicardial fat inflammation and improves psoriasis severity in patients affected by abdominal obesity and type-2 diabetes.

Psoriasis is often associated with abdominal obesity and type-2 diabetes (T2D). The inflammatory process in psoriasis can target adipose tissue depots, especially those surrounding the heart and coronary arteries, exposing to an increased risk of cardiovascular diseases. A 50-year-old female patient referred to us for abdominal obesity and T2D, which were not controlled with lifestyle modifications. She had suffered from psoriasis for some years and was treated with guselkumab, without success. Epicardial adipose tissue (EAT) attenuation and pericoronary adipose tissue (PCAT) attenuation for each coronary, defined as mean attenuation expressed in Hounsfield unit (HU), were assessed by routine coronary computed tomography angiography. At baseline, EAT attenuation was -80 HU and PCAT attenuation of the right coronary artery (RCA) was -68 HU, values associated with an increased cardiac mortality risk. Psoriasis area and severity index (PASI) was 12.0, indicating severe psoriasis, while dermatology life quality index (DLQI) was 20, indicating a negative effect on the patient's life. Semaglutide (starting with 0.25 mg/week for 4 weeks, increased to 0.50 mg/week for 16 weeks, and then to 1 mg/week) was started. After 10 months, semaglutide treatment normalized glycated hemoglobin and induced weight loss, particularly at abdominal level, also followed by a reduction in computed tomography-measured EAT volume. EAT attenuation and PCAT attenuation of RCA decreased, showing an important reduction of 17.5 and 5.9% respectively, compared with baseline. PASI and DLQI decreased by 98.3 and 95% respectively, indicating an improvement in psoriasis skin lesions and an important amelioration of the patient's quality of life, compared with baseline. Psoriasis patients affected by obesity and type-2 diabetes (T2D) are often resistant to biologic therapies. Psoriasis is often associated with abdominal obesity, T2D, and cardiovascular diseases (CVD), given their shared inflammatory properties and pathogenic similarities. Epicardial adipose tissue (EAT) inflammation can cause the distinctive pattern of CVD seen in psoriasis. EAT and pericoronary adipose tissue (PCAT) attenuation, assessed by routine coronary computed tomography angiography (CCTA), can be used as biomarkers of inflammation and allow monitoring of medical anti-inflammatory therapies. The actions of semaglutide to reduce energy intake, improve glycemic control, and produce effective weight loss, particularly at the visceral fat depot level, can diminish adipose tissue dysfunction, reduce EAT attenuation and PCAT attenuation of the right coronary artery (RCA) and concomitantly ameliorate the clinical severity of psoriasis. Semaglutide therapy may be considered in psoriasis patients affected by T2D and abdominal obesity, despite low cardiovascular risk by traditional risk scores, who are resistant to biologic therapies.

Minimizing Contrast Media Dose in CT Pulmonary Angiography with Clinical Photon Counting Using High Pitch Technique

To evaluate the potential to reduce the amount of iodinated contrast media (CM) for computer tomographic pulmonary angiography (CTPA) with a novel photon-counting-detector CT (PCCT). Overall, 105 patients referred for CTPA were retrospectively included in this study. CTPA was performed using bolus tracking and high-pitch dual-source scanning (FLASH mode) on a novel PCCT (Naeotom Alpha, Siemens Healthineers). CM (Accupaque 300, GE Healthcare) dose was lowered stepwise following the introduction of the new CT scanner. Thus, patients could be divided into 3 groups as follows: group 1, n=29, 35ml of CM; group 2, n=62, 45ml of CM and group 3, n=14, 60ml of CM. Four readers independently assessed the image quality (Likert-scale 1-5) and adequate assessment of the segmental pulmonary arteries. Additionally, the pulmonary arterial contrast opacification was measured. The subjective image quality was rated highest in group 1 with 4.6 compared to 4.5 (group 2) and 4.1 (group 3) with a significant difference between groups 1 and 3 (p<0.001) and between groups 2 and 3 (p=0.003). In all groups, almost all segmental pulmonary arteries could be assessed adequately without significant differences (18.5 vs. 18.7 vs. 18.4). Mean attenuation in the pulmonary trunk did not differ significantly between groups 321±92 HU versus 345±93 HU versus 347±88 HU (p=0.69). Significant CM dose reduction is possible without a reduction in image quality. PCCT enables diagnostic CTPA with 35ml of CM.

Comparison of true non-contrast and virtual non-contrast images in the characterization of renal lesions using detector-based spectral CT.

Renal lesions are sometimes incidentally detected during computed tomography (CT) examinations in which an unenhanced series is not included, preventing the lesions from being fully characterized. The aim of this study was to investigate the feasibility to use virtual non-contrast (VNC) images, acquired using a detector-based dual-energy CT, for the characterization of renal lesions. Twenty-seven patients (12 women) underwent a renal CT scan, including a non-contrast, an arterial, and a venous phase contrast-enhanced series, using a detector-based dual-energy CT scanner. VNC images were reconstructed from the venous contrast-enhanced series. The mean attenuation values of 65 renal lesions in both the VNC and true non-contrast (TNC) images were measured and compared quantitatively. Three radiologists blindly assessed all lesions using either VNC or TNC images in combination with contrast-enhanced images. Sixteen patients had cystic lesions, five had angiomyolipoma (AML), and six had suspected renal cell carcinomas (RCC). Attenuation values in VNC and TNC images were strongly correlated (ρ = 0.7, mean difference -6.0 ± 13 HU). The largest differences were found for unenhanced high-attenuation lesions. Radiologists classified 86% of the lesions correctly using VNC images. In 70% of the patients, incidentally detected renal lesions could be accurately characterized using VNC images, resulting in less patient burden and a reduction in radiation exposure. This study shows that renal lesions can be accurately characterized using VNC images acquired by detector-based dual-energy CT, which is in agreement with previous studies using dual-source and rapid X-ray tube potential switching technique.

Inter-software and inter-scan variability in measurement of epicardial adipose tissue: a three-way comparison of a research-specific, a freeware and a coronary application software platform

ObjectivesEpicardial adipose tissue (EAT) is a proposed marker of cardiovascular risk; however, clinical application may be limited by variability in post-processing software platforms. We assessed inter-vendor agreement of EAT volume (EATv) and attenuation on both contrast-enhanced (CE) and non-contrast CT (NCT) using a standard coronary CT reporting software (Vitrea), an EAT research-specific software (QFAT) and a freeware imaging software (OsiriX).MethodsSeventy-six consecutive patients undergoing simultaneous CE and NCT had complete volumetric EAT measurement. Between-software, within-software NCT vs. CE, and inter- and intra-observer agreement were evaluated with analysis by ANOVA (with post hoc adjustment), Bland-Altman with 95% levels of agreement (LoA) and intraclass correlation coefficient (ICC).ResultsMean EATv (freeware 53 ± 31 mL vs. research 93 ± 43 mL vs. coronary 157 ± 64 mL) and attenuation (freeware − 72 ± 25 HU vs. research − 75 ± 3 HU vs. coronary − 61 ± 10 HU) were significantly different between all vendors (ANOVA p < 0.001). EATv was consistently higher in NCT vs. CE for all software packages, with most reproducibility found in research software (bias 26 mL, 95% LoA: 2 to 56 mL), compared to freeware (bias 11 mL 95% LoA: − 46 mL to 69 mL) and coronary software (bias 10 mL 95% LoA: − 127 to 147 mL). Research software had more comparable NCT vs. CE attenuation (− 75 vs. − 72 HU) compared to freeware (− 72 vs. − 57 HU) and coronary (− 61 vs. − 39 HU). Excellent inter-observer agreement was seen with research (ICC 0.98) compared to freeware (ICC 0.73) and coronary software (ICC 0.75) with narrow LoA on Bland-Altman analysis.ConclusionThere are significant inter-vendor differences in EAT assessment. Our study suggests that research-specific software has better agreement and reproducibility compared to freeware or coronary software platforms.Key Points• There are significant differences between EAT volume and attenuation values between software platforms, regardless of scan type.• Non-contrast scans routinely have higher mean EAT volume and attenuation; however, this finding is only consistently seen with research-specific software.• Of the three analyzed packages, research-specific software demonstrates the highest reproducibility, agreement, and reliability for both inter-scan and inter-observer agreement.

Exploring pericoronary adipose tissue differences between calcified and non-calcified plaques on coronary CT angiography with fat attenuation index and radiomics analysis

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Ministry of Science and Technology. Introduction Coronary CT angiography (CCTA)-derived pericoronary adipose tissue (PCAT) is a novel marker for coronary inflammation. The relationship between the extravascular PCAT and the vascular lesion itself is particularly important to establish its use in monitoring the disease status. Past studies investigated lesion-level PCAT differences in vessels with acute myocardial infarction. However, lesion-level PCAT differences between calcified and non-calcified plaques in patients with stable coronary artery disease were not well understood. Purpose To investigate the differences between PCAT adjacent to calcified and PCAT adjacent to non-calcified plaques using fat attenuation index (FAI) and radiomics analysis. Material and Methods In a cohort of 100 consecutive patients who underwent CCTA, 446 plaques were identified in 89 patients. Among these plaques, 213 were calcified plaques and 49 were non-calcified plaques, with the rest classified as mixed by our expert cardiologist and radiologist. The PCAT of these 262 plaques were then extracted. Following prior literature, adipose tissue was defined as voxels with attenuation ranging −190 to −30 HU. PCAT was extracted within 3 mm distance from the vessel wall, along the middle 10 mm of each plaque. FAI was defined as the mean attenuation of the PCAT volume. For radiomics analysis, we used PyRadiomics to calculate the radiomic features and the random forest classifier from Scikit-Learn to distinguish PCAT volumes of calcified and non-calcified plaques. Patient-level 5-fold cross validation was used to develop the classifier. Result FAI were higher in PCAT adjacent to non-calcified plaques compared to PCAT adjacent to calcified plaques (−81.4 [IQR: −91.8 to −73.5] vs −86.7 [IQR: −94.1 to −78.4], p = 0.008). The classifier using radiomics features achieved better discrimination (AUROC=0.738 [0.715–0.761]) than FAI alone (AUROC=0.607 [0.605–0.609]). Conclusion Significant differences in PCAT characteristics were found between calcified and non-calcified plaques either with direct comparison of FAI or radiomics analysis. Radiomics analysis revealed further discrimination between PCAT characteristics other than FAI may exist between calcified and non-calcified plaques. It is also important to note that the FAI of calcified plaques could be affected by beam hardening. Further investigation is needed to explore the underlying cause of such differences and their clinical implications.

True Non-Contrast Phase versus Virtual-Non Contrast: “Lights and Shadows” of Dual Energy CT Angiography in Peripheral Arterial Disease

(1) Background: The value of dual-energy CT angiography (DE-CTA) in the detection of peripheral arterial disease (PAD) has been widely recognized. We aim to evaluate the diagnostic accuracy of virtual non-contrast (VNC) imaging of DE-CTA compared to true non-contrast phase (TNC). (2) Methods: Our Internal Review Board (IRB) approved prospective study enrolled 40 patients (28 men, 12 women; median age 69 y, range 41–93 y) who underwent lower extremity DE-CTA for symptomatic PAD. Mean attenuation values of TNC and VNC were obtained by placing circular regions of interest (ROI) at five levels from the aortic to the popliteal arterial lumen, reported in Hounsfield units (HU), and compared using a two-sample t-test. The subjective quality of VNC images was assessed by two independent radiologists with 10 and 4 years of CTA-imaging experience according to a 4-point scale and verified by the intra-class correlation coefficient (ICC). Dose Length Product (DLP) values of each DE-CTA examination were also considered. (3) Results: Except for the external iliac artery, VNC attenuation values were significantly lower than the corresponding TNC values at all levels, with a mean difference ranging from 14.1 and 8.7 HU. At qualitative analysis, VNC images were considered excellent to diagnose in 40%, good in 50%, and sufficient in 10% of cases. No cases of non-diagnostic VNC imaging were reported. Avoiding the TNC phase, a mean reduction in DLP of 54% for each DE-CTA was estimated. (4) Conclusions: TNC and VNC images showed comparable reliability and diagnostic accuracy in the detection of PAD. VNC may be considered a promising substitute for TNC from the perspectives of dose reduction and workflow optimization.

Reference distributions of aortic calcification and association with Framingham risk score

Evidence supporting aortic calcification as a leverageable cardiovascular risk factor is rapidly growing. Given aortic calcification’s potential as a clinical correlate, we assessed granular vertebral-indexed calcification measurements of the abdominal aorta in a well curated reference population. We evaluated the relationship of aortic calcification measurements with Framingham risk scores. After exclusion, 4073 participants from the Reference Analytic Morphomic Population with varying vertebral levels were included. The percent of the aortic wall calcified was used to assess calcification burden at the L1–L4 levels. Descriptive statistics of participants, sex-specific vertebral indexed calcification measurements, relational plots, and relevant associations are reported. Mean aortic attenuation was higher in female than male participants. Overall, mean aortic calcium was higher with reference to inferior abdominal aortic measurements and demonstrated significant differences across all abdominal levels [L3 Area (mm^2): Females 6.34 (sd 16.60), Males 6.23 (sd 17.21); L3 Volume (mm^3): Females 178.90 (sd 474.19), Males 195.80 (sd 547.36); Wall Calcification (%): Females (L4) 6.97 (sd 16.03), Males (L3) 5.46 (13.80)]. Participants with elevated calcification had significantly higher Framingham risk scores compared to participants with normal calcification scores. Opportunistically measuring aortic calcification may inform further cardiovascular risk assessment and enhance cardiovascular event surveillance efforts.

Conventional versus ultra-low dose computed tomogram in Crohn's disease: Do morphomics correlate with clinical data?

BackgroundCross-sectional study to assess the body composition of patients with Crohn's disease (CD) on standard (SDCT) and low dose CT (LDCT) protocols for the abdomen and pelvis (CTAP). We aimed to assess if a low dose CT protocol reconstructed with model-based iterative reconstruction (IR) could evaluate body morphometric data comparable to standard dose examination. MethodsThe CTAP images of 49 patients who underwent a low dose CT scan (20% of standard dose) and a second at standard dose minus 20% were assessed retrospectively. Images were collected from the PACS system, deidentified and analysed using a web-based semi-automated threshold-based segmentation tool (CoreSlicer), capable of identifying tissue type based on differences in attenuation co-efficient. The cross-sectional area (CSA) and Hounsfield units (HU) of each tissue was recorded. ResultsMuscle and fat CSA is well preserved on comparing these derived metrics from low dose and standard dose CT scans of abdomen and pelvic in CD ((LDCT:SDCT mean CSA (cm2); Psoas muscle - 29.00:28.67, total lumbar muscle - 127.45:125.55, visceral fat- 110.44:114.16, subcutaneous fat - 250.88:255.05)). A fixed difference exists when assessing the attenuation of muscle, with higher attenuation on the low dose protocol (LDCT:SDCT mean attenuation (HU); Psoas muscle - 61.67:52.25, total lumbar muscle - 49.29:41.20). ConclusionWe found comparable CSA across all tissues (muscle and fat) on both protocols with a strong positive correlation. A marginally lower muscle attenuation suggestive of less dense muscle was highlighted on SDCT. This study augments previous studies suggesting that comparable and reliable morphomic data may be generated from low dose and standard dose CT images. Implications for practiceThreshold-based segmental tools can be used to quantify body morphomics on standard and low dose computed tomogram protocols.

Pseudoenhancement in Cystic Renal Lesions – Impact of Virtual Monoenergetic Images of Photon-Counting Detector CT on Lesion Classification

To investigate the impact of virtual monoenergetic images (VMI) from photon-counting detector CT (PCD-CT) on the enhancement and classification of renal cysts. Adults with renal cysts (≥7mm) who received a triphasic examination on a clinical PCD-CT (120kVp; IQ level 68) between July 2021 and March 2022 were retrospectively identified. Only non-enhancing cysts (enhancement<10HU between unenhanced and venous phase at 70keV) were included. VMI from 40 to 190keV with increments of 10keV were reconstructed from the venous phase. Enhancement was measured to classify each lesion as non-enhancing (<10HU), equivocally enhancing (10-19HU), and definitely enhancing (≥20HU). Classification changes as a function of VMI were assessed. Pearson correlation coefficient, the Kruskal-Wallis and the Chi-square test were used. A total of 86patients (mean age, 74±9 years; 74 male) with 160 non-enhancing renal cysts (17.6±10mm) were included. CT attenuation of the cysts increased from higher to lower VMI levels with a mean attenuation of 4±11HU at 190keV to 36±17HU at 40keV. Mean attenuation of the renal parenchyma was 43±4HU at 190keV and 414±71HU at 40keV. No cyst exhibited enhancement from 70keV to 190keV. At 40, 50, and 60keV, 35% (56/160), 29% (47/160) and 9% (15/160) of cysts showed equivocal and 46% (74/160), 10% (16/160), and 0% (0/160) definite enhancement, respectively. There was no significant influence of size (P=.13), cyst location (P=.9) and BMI (P=.19) on enhancement classification. VMI has a relevant impact on enhancement and classification of renal cysts with misclassification in a large number of cases at energy levels below 70keV.

Can visceral fat parameters based on computed tomography be used to predict occult peritoneal metastasis in gastric cancer?

The preoperative prediction of peritoneal metastasis (PM) in gastric cancer would prevent unnecessary surgery and promptly indicate an appropriate treatment plan. To explore the predictive value of visceral fat (VF) parameters obtained from preoperative computed tomography (CT) images for occult PM and to develop an individualized model for predicting occult PM in patients with gastric carcinoma (GC). A total of 128 confirmed GC cases (84 male and 44 female patients) that underwent CT scans were analyzed and categorized into PM-positive (n = 43) and PM-negative (n = 85) groups. The clinical characteristics and VF parameters of two regions of interest (ROIs) were collected. Univariate and stratified analyses based on VF volume were performed to screen for predictive characteristics for occult PM. Prediction models with and without VF parameters were established by multivariable logistic regression analysis. The mean attenuations of VFROI 1 and VFROI 2 varied significantly between the PM-positive and PM-negative groups (P = 0.044 and 0.001, respectively). The areas under the receiver operating characteristic curves (AUCs) of VFROI 1 and VFROI 2 were 0.599 and 0.657, respectively. The mean attenuation of VFROI 2 was included in the final prediction combined model, but not an independent risk factor of PM (P = 0.068). No significant difference was observed between the models with and without mean attenuation of VF (AUC: 0.749 vs 0.730, P = 0.339). The mean attenuation of VF is a potential auxiliary parameter for predicting occult PM in patients with GC.

Associations between adiponectin and leptin levels and skeletal muscle mass and myosteatosis in older adults: The Shimanami Health Promoting Program study

Identifying plasma molecules associated with skeletal muscle properties can elucidate the pathophysiology of sarcopenia. Because adipocytokines are a promising candidate marker, the current study aimed to clarify the possible associations between adiponectin and leptin levels and mid-thigh muscle cross-sectional area and mean attenuation value, which are indices of muscle mass and fat deposition in muscle, respectively. The current study included 1440 older Japanese adults (mean age 69.3 years). Mid-thigh skeletal muscle cross-sectional area and mean attenuation value were evaluated through computed tomography scan. A low attenuation value showed a greater fat deposition in muscle. Circulating adiponectin and leptin levels were assessed using blood specimens collected during the baseline investigation. Plasma leptin level was inversely correlated with muscle cross-sectional area, but not with attenuation value. The association with cross-sectional area was independent of possible confounding factors including body size (Q1: reference; Q2: β = -0.032, P = 0.033; Q3: β = -0.064, P < 0.001; Q4: β = -0.111, P < 0.001). In contrast, adiponectin level was independently and inversely associated with attenuation value (Q1: reference; Q2: β = -0.044, P = 0.122; Q3: β = -0.080, P = 0.006; Q4: β = -0.159, P < 0.001), but not with cross-sectional area. These associations between adipocytokine levels and muscle properties were independent of abdominal fat area and insulin resistance. There were adiposity- and insulin resistance-independent associations between adipocytokines levels and skeletal muscle mass and fat deposition in muscle, suggesting an involvement of adipocytokines in muscle properties. Geriatr Gerontol Int 2023; 23: 444-449.

A comparison of the use of contrast media with different iodine concentrations for enhanced computed tomography.

Objective: In this study, we compared the enhancement of blood vessels and liver parenchyma on enhanced computed tomography (CT) of the upper abdomen with two concentrations of contrast media (400 and 300mg I/mL) based on similar iodine delivery rate (IDR) of 0.88 and 0.9g I/s and iodine load of 450mg I/kg. Methods: We randomly assigned 160 patients into two groups: iomeprol 400mg I/mL (A group) and iohexol 300mg I/mL (B group). The CT attenuation values of the main anatomical structures in the two groups with different scanning phases were measured and the image quality of the two groups was analyzed and compared. The peak pressure and local discomfort (including fever and pain) during contrast medium injection were recorded. Results: The mean attenuation value of the abdominal aorta was 313.6 ± 29.6 in the A group and 322.4 ± 30.1 in the B group during the late arterial phase (p = 0.8). Meanwhile, the mean enhancement values of the portal vein were 176.2 ± 19.3 and 165.9 ± 24.5 in the A and B groups, respectively, during the portal venous phase (p = 0.6). The mean CT values of liver parenchyma were 117.1 ± 15.3 and 108.8 ± 18.7 in the A and B groups, respectively, during the portal venous phase (p = 0.9). There was no statistical difference in image quality, peak injection pressure (psi), and local discomfort between the two groups (p > 0.05). Conclusion: When a similar IDR and the same iodine load are used, CT images with different concentrations of contrast media have the same subjective and objective quality, and can meet the diagnostic needs.