CT Attenuation Research Articles

Coronary perivascular inflammation in type 2 diabetes mellitus patients: the missing piece in the puzzle of their increased cardiovascular risk?

Abstract Background Coronary atherosclerosis is a frequent complication of type 2 diabetes mellitus (DM2). Considering the contiguity with the vascular wall, perivascular adipose tissue (PVAT) could play a crucial role in the pathogenic microenvironment of atherosclerosis. The PVAT attenuation index (p-FAI) is a non-invasive marker that reveals the change in peri-coronary adipose tissue (PCAT). High values of p-FAI are associated with increased cardiovascular mortality and poor prognosis. Emerging as an indication, contributor to, and therapeutic target for atherosclerosis, PCAT warrants further investigation in DM2. Purpose We aimed to characterize the association of PCAT by p-FAI and DM2, and to compare coronary inflammation in DM2 versus non DM2 patients with coronary artery disease (CAD), and versus healthy controls. Methods 15 consecutive DM2 patients (9 male, age 63±10 years) without symptoms/signs of cardiovascular disease were included in the study and compared to 8 non DM2 patients with CAD and 13 healthy volunteers without cardiovascular diseases, matched for age and sex. All patients and controls underwent coronary computed tomography angiography (CCTA) for the evaluation of coronary arteries and p-FAI. All scans were performed using a 320-slice multidetector computed tomography (Toshiba Aquilion) and a prospective ECG-triggered sequential acquisition. p-FAI analysis was performed using a dedicated workstation (Aquarius iNtuition Edition version 4.4.13. P3; TeraRecon Inc., Foster City, CA, USA). The proximal 40-mm segment of the right coronary artery (RCA) was identified and the inner and the outer wall were automatically traced, excluding the 10 mm from the ostium. The adipose tissue localized within a radial distance from the outer wall equal to a medium diameter of the RCA was evaluated. Voxel histograms of CT attenuation were traced and included between −190 to −30 HU within the PCAT volume. p-FAI was calculated as the median CT attenuation value of PCAT of the proximal 40-mm segment of the RCA (Figure 1). Results CAD was present in 10 DM2 patients (5 males, aged 63.1±10.5 years); in 5 DM2 patients (4 males, aged 63±11 years) epicardial coronary arteries were normal. p-FAI was higher in DM2 patients than in healthy controls (p=0.004). The presence of CAD did not impact on p-FAI in DM2 patients, presenting a comparable value (p=0.37). p-FAI was higher in DM2 patients with CAD than in non DM2 patients with CAD (p=0.04). Moreover, p-FAI was higher in DM2 patients without CAD than in non DM2 patients with CAD (p=0.002, Figure 2). Finally, p-FAI was not different in non DM2 patients with CAD compared to healthy controls (p=0.65), suggesting the limited role of CAD in the progression of peri-coronary inflammation when compared to DM2. Conclusions Coronary inflammation evaluated by p-FAI measurement was higher in DM2 patients, also without CAD. Therefore, our results suggest that DM2 is a determinant of coronary inflammation stronger than CAD. Funding Acknowledgement Type of funding sources: None. Figure 1Figure 2

Needle insertion planning for obstacle avoidance in robotic biopsy

Abstract Understanding the underlying pathology in different tissues and organs is crucial when fighting pandemics like COVID-19. During conventional autopsy, large tissue sample sets of multiple organs can be collected from cadavers. However, direct contact with an infectious corpse is associated with the risk of disease transmission and relatives of the deceased might object to a conventional autopsy. To overcome these drawbacks, we consider minimally invasive autopsies with robotic needle placement as a practical alternative. One challenge in needle based biopsies is avoidance of dense obstacles, including bones or embedded medical devices such as pacemakers. We demonstrate an approach for automated planning and visualising suitable needle insertion points based on computed tomography (CT) scans. Needle paths are modeled by a line between insertion and target point and needle insertion path occlusion from obstacles is determined by using central projections from the biopsy target to the surface of the skin. We project the maximum and minimum CT attenuation, insertion depth, and standard deviation of CT attenuation along the needle path and create two-dimensional intensity-maps projected on the skin. A cost function considering these metrics is introduced and minimized to find an optimal biopsy needle path. Furthermore, we disregard insertion points without sufficient room for needle placement. For visualisation, we display the color-coded cost function so that suitable points for needle insertion become visible. We evaluate our system on 10 post mortem CTs with six biopsy targets in abdomen and thorax annotated by medical experts. For all patients and targets an optimal insertion path is found. The mean distance to the target ranges from (49.9 ± 12.9)mm for the spleen to (90.1 ± 25.8)mm for the pancreas.

Diagnostic value of minimum-intensity projection computed tomography chest in diagnosis of endobronchial lesions

Background Fiberoptic bronchoscopy (FOB) is used to directly visualize the lumen of the trachea, as well as proximal and distal airways. It can be used to diagnose or treat abnormalities within or adjacent to these airways. However, it is an invasive procedure that may lead to several complications. Minimum-intensity projection (MinIP) in high-resolution computed tomography (CT) of the lungs is particularly useful because multiple lung diseases may present with reduced CT attenuation values. Patients and methods In this study, we included 115 patients admitted to the Chest Department, Mansoura University, Egypt. All patients were subjected to complete history taking, thorough physical examination, routine laboratory investigations, in addition to chest radiograph. CT and FOB were ordered for all cases. Results CT examination of the studied cases revealed mass in 43.5%, delayed resolved pneumonia in 30.4%, and collapse in 13% of cases. Furthermore, either of cavity, narrowing, or collapse was present in 4.3% of cases. Lesions were detected in the left lung in 43.5%, right lung in was 30.4%, and both lungs in 13% of cases. The sensitivity and specificity of MinIP was 69.4 and 100%, respectively, compared with FOB. The positive predictive value was 100%, whereas the negative predictive value was 71.4%, with an accuracy of 82.6%. The sensitivity of MinIP in the diagnosis was different according to the nature of the lesion. We found significant differences when comparing conventional CT with MinIP, especially in collapse, nodules, delayed resolved pneumonia, cavity, and narrowing. However, such a significant difference was not detected in the diagnosis of mass lesions. Conclusion We conclude that MinIP CT is a very important technique for detection of endobronchial lesion compared with conventional CT, and we recommend use of this technique when an endobronchial lesion is suspected.

Application of 70 kVp in abdominal CT angiography to reduce both radiation and contrast dosage and improve patient comfort for children.

Low-tube voltage scanning improves CT attenuation value of contrast medium (CM). Thus, we hypothesized that 70 kVp in pediatric abdominal CT angiography (CTA) could be used to reduce both radiation and CM dose and improve patient comfort at the same time. To evaluate the feasibility of using 70 kVp in pediatric abdominal CTA to reduce radiation dose and CM dose and improve patient care for children. Forty-six children needing abdominal CTA were enrolled in the study group using low-dose scanning protocol with 70 kVp and 0.7-1.1 ml/kg contrast dose, and reconstructed with 50%ASIR-V. They were compared with other 46 children in control group with matching body weight and underwent conventional CT scans with 100 kVp, 1.2-1.8 ml/kg contrast dose and reconstructed using 50%ASIR. Image quality of large vessels was evaluated using a 5-point scale. CT value and standard deviation of descending aorta (Ao) was measured, and signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. Radiation dose, contrast dose, the maximum injection pressure between the two groups were also compared. Score for displaying large vessels by 70 kVp images was 3.91±0.28, lower than that (4.17±0.38) of the control group (p < 0.05), but fully met the diagnostic requirements. CT value of Ao was 390.87±86.79HU in study group, which is higher than 343.93±49.94HU in control group, while there was no difference in SNR and CNR between two groups; the radiation dose, contrast dosage and injection pressure of the study group were 1.23±0.39mGy, 12.67±7.27 ml and 43.83±17.16psi, respectively, which are significantly lower than the 1.95±0.37mGy, 22.67±7.39 ml, and 77.59±19.68psi of control group. Use of 70 kVp in pediatric abdominal CTA provides diagnostic quality images while significantly reduce radiation and contrast dose, as well as injection pressure to improve patient comfort for children.

Potential of Gold Nanoparticles for Noninvasive Imaging and Therapy for Vascular Inflammation

PurposeMacrophages contribute to the progression of vascular inflammation, making them useful targets for imaging and treatment of vascular diseases. Gold nanoparticles (GNPs) are useful as computed tomography (CT) contrast agents and light absorbers in photothermal therapy. In this study, we aimed to assess the viability of macrophages incubated with GNPs after near-infrared (NIR) laser light exposure and to evaluate the utility of intravenously injected GNPs for in vivo imaging of vascular inflammation in mice using micro-CT.ProceduresMouse macrophage cells (RAW 264.7) were incubated with GNPs and assessed for GNP cellular uptake and cell viability before and after exposure to NIR laser light. For in vivo imaging, macrophage-rich atherosclerotic lesions were induced by carotid ligation in hyperlipidemic and diabetic FVB mice (n = 9). Abdominal aortic aneurysms (AAAs) were created by angiotensin II infusion in ApoE-deficient mice (n = 9). These mice were scanned with a micro-CT imaging system before and after the intravenous injection of GNPs.ResultsThe CT attenuation values of macrophages incubated with GNPs were significantly higher than those of cells incubated without GNPs (p < 0.04). Macrophages incubated with and without GNPs showed similar viability. The viability of macrophages incubated with GNPs (100 μg/ml or 200 μg/ml) was decreased by high-intensity NIR laser exposure but not by low-intensity NIR laser exposure. In vivo CT images showed higher CT attenuation values in diseased carotid arteries than in non-diseased contralateral arteries, although the difference was not statistically significant. The CT attenuation values of the perivascular area in AAAs of mice injected with GNPs were significantly higher than those of mice without injection (p = 0.0001).ConclusionsMacrophages with GNPs had reduced viability upon NIR laser exposure. GNPs intravenously injected into mice accumulated in sites of vascular inflammation, allowing detection of carotid atherosclerosis and AAAs in CT imaging. Thus, GNPs have potential as multifunctional biologically compatible particles for the detection and therapy of vascular inflammation.

Physiological significance of pericoronary inflammation in epicardial functional stenosis and global coronary flow reserve

Both fractional flow reserve (FFR) and global coronary flow reserve (g-CFR) provide prognostic information in patients with stable coronary artery disease (CAD). Inflammation plays a vital role in impaired endothelial dysfunction and atherosclerotic progression, potentially predicting cardiovascular mortality. This study aimed to evaluate the physiological significance of pericoronary adipose tissue inflammation assessed by CT attenuation (PCATA) in epicardial functional stenosis severity and g-CFR in patients with CAD. A total of 131 CAD patients with a single de novo epicardial coronary stenosis who underwent coronary CT-angiography (CCTA), phase-contrast cine-magnetic resonance imaging (PC-CMR) and FFR measurement were studied. PCATA was assessed using the mean CT attenuation value. G-CFR was obtained by quantifying absolute coronary sinus flow (ml/min/g) by PC-CMR at rest and during maximum hyperemia. Median FFR, g-CFR, and PCATA values were 0.75, 2.59, and − 71.3, respectively. Serum creatinine, NT-proBNP, left ventricular end-diastolic volume, and PCATA were independently associated with g-CFR. PCATA showed a significant incremental predictive efficacy for impaired g-CFR (< 2.0) when added to the clinical risk model. PCATA was significantly associated with g-CFR, independent of FFR. Our results suggest the pathophysiological mechanisms linking perivascular inflammation with g-CFR in CAD patients.

Association between pericoronary adipose tissue attenuation and outcome after second-generation cryoballoon ablation for atrial fibrillation.

Previous studies reported the association between inflammation and atrial fibrillation (AF). Pericoronary adipose tissue (PCAT) attenuation, PCATA, on cardiac CT angiography (CTA) reflects pericoronary inflammation. We hypothesized that the PCATA predicts AF recurrence after cryoballoon ablation (CBA) for paroxysmal and persistent AF. We studied 364 patients (median age, 65 years) with persistent (n = 41) and paroxysmal (n = 323) AF undergoing successful first-session second-generation CBA with pre-ablation cardiac CTA. Three-vessel (3V)-PCATA was defined as the mean CT attenuation value of PCAT of all three major coronary arteries. Predictors of AF recurrence during follow-up were evaluated. AF recurrence after the 3-month blanking period was detected in 90 patients (24.7%) during the median follow-up of 26 (interquartile range, 19-42) months. AF recurrence was associated with prior stroke and statin use, NT-proBNP and high-sensitivity cardiac troponin-I levels, left ventricular dimension, left atrial volume index (LAVI), 3V-PCATA, and early AF recurrence during the blanking period. On multivariable Cox proportional hazard analysis, prior stroke (hazard ratio [HR], 2.208, 95% confidence interval [CI], 1.166-4.180, p = 0.015), LAVI (HR, 1.030, 95% CI, 1.010-1.051, p = 0.003), 3V-PCATA (HR, 1.034, 95% CI, 1.001-1.069, p = 0.046), and early AF recurrence (HR, 2.858, 95% CI, 1.855-4.405, p < 0.001) remained statistically significant. Pre-ablation CTA-derived 3V-PCATA, representing pericoronary inflammation, was an independent predictor of recurrence after first-session AF ablation using a second-generation cryoballoon. Assessment of 3V-PCATA may identify patients at high risk of AF recurrence after CBA for AF.

Changes in the Mean Intrahepatic Target Computed Tomography Attenuation Value During Treatment May Be a Useful New Predictor of the Post-progression Survival Associated with Lenvatinib Treatment.

Objective The relationship between the prognosis and magnitude of a decrease in tumor blood flow according to estimated tumor differentiation remains unclear. This study investigated the relationship between reductions in the rate of mean computed tomography (CT) attenuation values and the clinical prognosis. Methods We evaluated 63 consecutive patients who received lenvatinib treatment for unresectable hepatocellular carcinoma (HCC). The oncological aggressiveness of the tumors was estimated using classification by dynamic CT enhancement patterns. The utility of changes in mean CT attenuation values of intra-hepatic targets during treatment to estimate the prognosis was investigated by calculating the progression-free survival (PFS) and post-progression survival (PPS). A multivariate analysis was used to identify potential confounders for the survival after progression during lenvatinib therapy. Results The rate of decrease in the mean CT attenuation value gradually increased according to the degree of deterioration in estimated tumor differentiation, and the rate of a decrease in attenuation ≥40% showed a tendency to increase (p=0.064). This trend was reflected by a better objective response in oncological aggressiveness heterogeneous enhancement patterns (Type-3 and Type-4) than a homogeneous enhancement pattern (Type-2) (83% vs. 56% of modified Response Evaluation Criteria in Solid Tumors). This resulted in a similar PFS between the groups (p=0.773), whereas the PPS was significantly worse when the rate of decrease in the attenuation value was ≥40% (p=0.012). A multivariate analysis confirmed that a rate of decease in attenuation value ≥40% was a poor prognostic factor for the PPS (hazard ratio, 2.993; 95% confidence interval, 1.196-7.490; p=0.019). Conclusion A rate of decrease in attenuation ≥40% may reflect a good response of a highly malignant tumor to lenvatinib. Therefore, this value may have utility as a surrogate marker for estimating the oncological aggressiveness of tumors and their associated prognosis.

Abdominal Muscles and Metabolic Syndrome According to Patient Sex: A Retrospective Cross-Sectional Study.

Computed tomography (CT) is a reference method for measuring skeletal muscle mass, and the amount of fat in the skeletal muscle can be calculated based on CT attenuation. This study aimed to comprehensively investigate the effect of muscle quality and quantity on metabolic syndrome (MetS) according to sex. This retrospective cross-sectional study enrolled 8081 individuals aged ≥20 years who underwent self-referral abdominopelvic CT at our hospital. The total abdominal muscle area (TAMA), low-attenuation abdominal muscle area (LAMA), normal-attenuation abdominal muscle area (NAMA), and extramyocellular lipid area (EMCLA) were measured using cross-sectional CT data of the L3 lumbar vertebrae. The TAMA and NAMA showed negative correlations with risk factors for MetS and a positive correlation with high-density lipoprotein cholesterol, whereas the LAMA and EMCLA showed an inverse trend in both the sexes (p < 0.001). After adjusting for various factors, a higher LAMA index and the ratio of LAMA to TAMA were associated with a higher prevalence of MetS. High TAMA indices were associated with a lower prevalence of MetS. Furthermore, muscle quality and quantity were associated with the prevalence of MetS in both males and females. However, the LAMA showed a stronger association with MetS in males than in females.

Relative Enhancement Ratio of Portal Venous Phase to Unenhanced CT in the Diagnosis of Lipid-poor Adrenal Adenomas.

Background The development of an accurate, practical, noninvasive, and widely available diagnostic approach to characterize lipid-poor adrenal lesions (greater than 10 HU at unenhanced CT) remains an ongoing demand. Purpose To investigate whether combined assessment of unenhanced and portal venous phase CT allows for the differentiation of lipid-poor adrenal adenomas from nonadenomas. Materials and Methods Patients with lipid-poor adrenal lesions who underwent unenhanced and portal venous phase CT with a single-energy scanner between January 2016 and March 2020 were identified retrospectively. For each lesion, the unenhanced and contrast-enhanced attenuation were measured; the absolute enhancement (contrast-enhanced minus unenhanced attenuation [HU]) and relative enhancement ratio ([absolute enhancement divided by unenhanced attenuation] × 100%) were calculated. The sensitivity achieved at 95% specificity to distinguish adenomas from nonadenomas was determined with receiver operating characteristic curve analysis and compared among parameters with use of the McNemar test. Results A total of 220 patients (mean age ± standard deviation, 66 years ± 12; 134 men) with 131 lipid-poor adenomas and 89 nonadenomas were analyzed. The sensitivity (achieved at 95% specificity) of the relative enhancement ratio (86% [113 of 131 adenomas; 95% CI: 79, 92] at a threshold of >210%) was higher than that of unenhanced attenuation (50% [66 of 131 adenomas; 95% CI: 42, 59] at a threshold of ≤21 HU), contrast-enhanced attenuation (3% [four of 131 adenomas; 95% CI: 1, 8] at a threshold of >120 HU), and absolute enhancement (24% [32 of 131 adenomas; 95% CI: 17, 33] at a threshold of >74 HU; all P < .001). The sensitivities of the relative enhancement ratio were 100% (58 of 58 adenomas; 95% CI: 94, 100), 83% (52 of 63 adenomas; 95% CI: 71, 91), and 30% (three of 10 adenomas; 95% CI: 7, 65) for adenomas measuring unenhanced attenuation of more than 10 HU up to 20 HU, 21-30 HU, and more than 30 HU, respectively. Conclusion A relative enhancement ratio threshold of greater than 210%, measured at unenhanced and portal venous phase CT, accurately differentiated lipid-poor adenomas from nonadenomas, particularly for lesions with unenhanced attenuation of 10-30 HU. © RSNA, 2021 Online supplemental material is available for this article.

Computed Tomography-Determined Body Composition Abnormalities Usefully Predict Long-term Mortality in Patients With Liver Cirrhosis.

We evaluated the prognostic impacts of body composition components measured by computed tomography (CT) in patients with liver cirrhosis. A total of 160 cirrhotic patients who underwent CT and hepatic venous pressure gradient measurements were retrospectively enrolled. Cross-sectional areas of skeletal muscle, visceral and subcutaneous fat, and mean CT attenuation of trabecular bone of the fourth lumbar vertebral level (L4HU) were measured. Multivariate analysis showed model for end-stage liver disease score [hazard ratio (HR), 1.086; 95% confidence interval (CI), 1.020-1.156; P = 0.010], hepatic venous pressure gradient (HR, 1.076; 95% CI, 1.021-1.135; P = 0.006), sarcopenia (HR, 1.890; 95% CI, 1.032-3.462; P = 0.039), and L4HU (HR, 1.960 for L4HU <145 Hounsfield units; 95% CI, 1.094-3.512; P = 0.024) were independently associated with long-term mortality. In patients with decompensated cirrhosis, subcutaneous adipose tissue index was the only independent predictor (HR, 0.984; 95% CI, 0.969-0.999; P = 0.039). Body composition abnormalities determined by CT are associated with long-term prognosis in cirrhotic patients.

Determining age and sex-specific distribution of pancreatic whole-gland CT attenuation using artificial intelligence aided image segmentation: Associations with body composition and pancreatic cancer risk

Background & aimsIncreased intrapancreatic fat is associated with pancreatic diseases; however, there are no established objective diagnostic criteria for fatty pancreas. On non-contrast computed tomography (CT), adipose tissue shows negative Hounsfield Unit (HU) attenuations (−150 to −30 HU). Using whole organ segmentation on non-contrast CT, we aimed to describe whole gland pancreatic attenuation and establish 5th and 10th percentile thresholds across a spectrum of age and sex. Subsequently, we aimed to evaluate the association between low pancreatic HU and risk of pancreatic ductal adenocarcinoma (PDAC). MethodsThe whole pancreas was segmented in 19,456 images from 469 non-contrast CT scans. A convolutional neural network was trained to assist pancreas segmentation. Mean pancreatic HU, volume, and body composition metrics were calculated. The lower 5th and 10th percentile for mean pancreatic HU were identified, examining the association with age and sex. Pre-diagnostic CT scans from patients who later developed PDAC were compared to cancer-free controls. ResultsLess than 5th percentile mean pancreatic HU was significantly associated with increase in BMI (OR 1.07; 1.03–1.11), visceral fat (OR 1.37; 1.15–1.64), total abdominal fat (OR 1.12; 1.03–1.22), and diabetes mellitus type 1 (OR 6.76; 1.68–27.28). Compared to controls, pre-diagnostic scans in PDAC cases had lower mean whole gland pancreatic HU (−0.2 vs 7.8, p = 0.026). ConclusionIn this study, we report age and sex-specific distribution of pancreatic whole-gland CT attenuation. Compared to controls, mean whole gland pancreatic HU is significantly lower in the pre-diagnostic phase of PDAC.

Effect of Lowering Tube Potential and Increase Iodine Concentration of Contrast Medium on Radiation Dose and Image Quality in Computed Tomography Pulmonary Angiography Procedure: A Phantom Study

The aim of the study was to examine the effect of lowering tube potential and increase iodine concentration on image quality and radiation dose in computed tomography pulmonary angiography procedure. The pulmonary arteries were simulated by three syringes. The syringes were filled with 1:10 diluted solutions of 300 mg, 350 mg and 370 mg of iodine per millilitre concentration in three water-filled phantoms simulating thin, intermediate and thick patients. The phantoms were scanned at 80 kVp, 110 kVp and 130 kVp and 0.6 second rotation time using a 16 slice computed tomography (CT) scanner. The tube current was either fixed at 80, 100, 200, 250 and 300 mA or automatically adjusted with quality reference tube current-time product (mAsQR). In comparison with 130 kVp, images acquired at 80 kVp and 110 kVp, respectively, showed 76.2% to 99% and 19% to 26% enhancement in CT attenuation of iodinated contrast material. A volume CT dose index (CTDIvol) reduction by 35.3% was attained in small phantom with the use of 80 kVp, while in the medium phantom, a CTDIvol reduction by 29.9% was attained with the use of 110 kVp instead of 130 kVp. In light of the above, lowering tube potential and increase iodinated CM could substantially reduce the dose to small-sized adults and children.&#x0D; Keywords: Angiography; Computed tomography; Low tube potential; Iodinated contrast medium; Radiation dose

Computed tomography measured psoas muscle attenuation predicts mortality after transcatheter aortic valve implantation.

The aim of this study was to determine if computed tomography (CT) psoas muscular attenuation measurements may predict all-cause mortality in patients undergoing TAVI. Ninety-four consecutive patients undergoing TAVI were analysed. The CT axial slice at the level of the fourth lumbar vertebra was selected. The psoas muscle areas were manually contoured. The circumferential surface area (CSA) of both psoas muscles was determined by selecting the voxels with attenuation values, ranging from 0 to 100 Hounsfield Units (HU). The mean CT attenuation coefficient of the psoas muscle (Psoas mean HU) was measured. The muscle was subdivided into a low-density muscle (LDM) (0-29 HU) and high-density muscle (HDM) (30-100 HU) portion. The HDM/LDM ratio was calculated. We searched for a correlation between HDM/LDM, CSA LDM (%), Psoas mean HU and all-cause mortality. The mean age was 81.2 ± 7.5 years. Thirty patients had adverse outcome (all-cause mortality). Compared with patients with the lowest CSA LDM (%), patients in the third and second tertiles had an increased hazard ratio for mortality (2.871; 95% confidence interval 0.880-9.371 and 5.044; 95% confidence interval 1.641-15.795, respectively) in a multivariable model with EuroSCORE II, Barthel frailty index and CSA LDM (%) (P = 0.231, 0.097 and 0.019, respectively). HDM/LDM and Psoas mean HU (as continuous variable) were also independent predictors of all-cause mortality (P = 0.019, P = 0.013, respectively). CSA LDM (%), Psoas mean HU and HDM/LDM are independent and incremental predictors of all-cause mortality in patients undergoing TAVI.

111. Can body composition measures on computed tomography predict mortality in patients with spinal metastases undergoing surgery?

<h3>BACKGROUND CONTEXT</h3> Although survival of patients with spinal metastases has improved in recent decades due to advances in multimodal therapy, there are currently no reliable predictors of mortality. Computed tomography (CT) body composition measurements have been recently proposed as biomarkers for survival in patients with and without cancer. Patients with cancer routinely undergo CT for staging or surveillance of therapy and body composition assessed using opportunistic CTs might be used to determine survival in patients with spinal metastases. <h3>PURPOSE</h3> The purpose of our study was to determine the value of body composition measures obtained on opportunistic abdomen CTs to predict 90-day and 1-year mortality in patients with spinal metastases undergoing surgery. We hypothesized that low muscle and abdominal fat mass were predictors of mortality. <h3>STUDY DESIGN/SETTING</h3> Retrospective cohort. <h3>PATIENT SAMPLE</h3> Between 2001 and 2016, 196 patients who underwent surgery for spinal metastases at a single tertiary center underwent CT of the abdomen within three months prior to surgery. <h3>OUTCOME MEASURES</h3> Ninety-day and 1-year mortality. <h3>Methods</h3> Quantification of cross-sectional areas (CSA) and CT attenuation in Hounsfield units (HU) of abdominal subcutaneous adipose tissue (SAT), visceral adipose tissue (VAT), and paraspinous skeletal muscle were performed on CT images at the level of L4 using an in-house automated algorithm under the supervision of a fellowship-trained musculoskeletal radiologist. Sarcopenia was determined by total muscle area (cm²) divided by height squared (m²) with cutoff values of <52.4 cm²/m² for men and <38.5 cm²/m² for women. Bivariate and multivariate Cox proportional-hazard analyses were used to determine the associations between body compositions and 90-day and 1-year mortality. <h3>Results</h3> The median age was 62 years (interquartile range = 53-70). Mortality rates at 90 days and 1 year were 24% and 54%, respectively. Sarcopenia and decreased muscle attenuation were associated with increased mortality for both timepoints (p=0.04 and p=0.04, respectively) after controlling for sex, age, body mass index, Charlson Comorbidity score, primary tumor type, visceral metastases, and duration between diagnosis of spinal metastases and surgery. Decreased SAT area was associated with increased 90-day mortality after controlling for the same covariates (p<0.01). <h3>Conclusions</h3> Decreased muscle attenuation and sarcopenia are independently associated with an increased risk of 90-day and 1-year mortality for patients surgically treated for spinal metastases, and low SAT CSA is independently associated with increased risk of 90-day mortality. Therefore, body composition measurements could serve as novel biomarkers for prediction of mortality in patients with spinal metastases. <h3>FDA DEVICE/DRUG STATUS</h3> This abstract does not discuss or include any applicable devices or drugs.

High-Pitch Photon-Counting Detector Computed Tomography Angiography of the Aorta: Intraindividual Comparison to Energy-Integrating Detector Computed Tomography at Equal Radiation Dose.

The aims of this study were to determine the objective and subjective image quality of high-pitch computed tomography (CT) angiography of the aorta in clinical dual-source photon-counting detector CT (PCD-CT) and to compare the image quality to conventional dual-source energy-integrating detector CT (EID-CT) in the same patients at equal radiation dose. Patients with prior CT angiography of the thoracoabdominal aorta acquired on third-generation dual-source EID-CT in the high-pitch mode and with automatic tube voltage selection (ATVS, reference tube voltage 100 kV) were included. Follow-up imaging was performed on a first-generation, clinical dual-source PCD-CT scanner in the high-pitch and multienergy (QuantumPlus) mode at 120 kV using the same contrast media protocol as with EID-CT. Radiation doses between scans were matched by adapting the tube current of PCD-CT. Polychromatic images for both EID-CT and PCD-CT (called T3D) and virtual monoenergetic images at 40, 45, 50, and 55 keV for PCD-CT were reconstructed. Computed tomography attenuation was measured in the aorta; noise was defined as the standard deviation of attenuation; contrast-to-noise ratio (CNR) was calculated. Subjective image quality (noise, vessel attenuation, vessel sharpness, and overall quality) was rated by 2 blinded, independent radiologists. Forty patients were included (mean age, 63 years; 8 women; mean body mass index [BMI], 26 kg/m2). There was no significant difference in BMI, effective diameter, or radiation dose between scans (all P's > 0.05). The ATVS in EID-CT selected 70, 80, 90, 100, 110, and 120 kV in 2, 14, 14, 7, 2, and 1 patients, respectively. Mean CNR was 17 ± 8 for EID-CT and 22 ± 7, 20 ± 6, 18 ± 5, 16 ± 5, and 12 ± 4 for PCD-CT at 40, 45, 50, 55 keV, and T3D, respectively. Contrast-to-noise ratio was significantly higher for 40 and 45 keV of PCD-CT as compared with EID-CT (both P's < 0.05). The linear regression model (adjusted R2, 0.38; P < 0.001) revealed that PCD-CT reconstruction (P < 0.001), BMI group (P = 0.007), and kV of the EID-CT scan (P = 0.01) were significantly associated with CNR difference, with an increase by 34% with PCD-CT for overweight as compared with normal weight patients. Subjective image quality reading revealed slight differences between readers for subjective vessel attenuation and sharpness, whereas subjective noise was rated significantly higher for 40 and 45 keV (P < 0.001) and overall quality similar (P > 0.05) between scans. High-pitch PCD-CT angiography of the aorta with VMI at 40 and 45 keV resulted in significantly increased CNR compared with EID-CT with ATVS at matched radiation dose. The CNR gain of PCD-CT increased in overweight patients. Taking into account the subjective analysis, VMI at 45 to 50 keV is proposed as the best trade-off between objective and subjective image quality.

Investigation of Three-dimensional Printing Materials for Printing Aorta Model Replicating Type B Aortic Dissection.

This study aims to determine a printing material that has both elastic property and radiology equivalence close to the real aorta for simulation of endovascular stent-graft repair of aortic dissection. With the rapid development of Three-Dimensional (3D) printing technology, a patient- specific 3D printed model is able to help surgeons to make a better treatment plan for Type B aortic dissection patients. However, the radiological properties of most 3D printing materials have not been well characterized. This study aims to investigate the appropriate materials for printing human aorta with mechanical and radiological properties similar to the real aortic Computed Tomography (CT) attenuation. Quantitative assessment of CT attenuation of different materials used in 3D printed models of aortic dissection for developing patient-specific 3D printed aorta models to simulate type B aortic dissection. A 25-mm length of aorta model was segmented from a patient's image dataset with a diagnosis of type B aortic dissection. Four different elastic commercial 3D printing materials, namely Agilus A40 and A50, Visijet CE-NT A30 and A70 were selected and printed with different hardness. Totally four models were printed out and CT scanned twice on a 192-slice CT scanner using the standard aortic CT angiography protocol, with and without contrast inside the lumen. Five reference points with the Region Of Interest (ROI) of 1.77 mm2 were selected at the aortic wall, and intimal flap and their Hounsfield units (HU) were measured and compared with the CT attenuation of original CT images. The comparison between the patient's aorta and models was performed through a paired-sample t-test to determine if there is any significant difference. The mean CT attenuation of the aortic wall of the original CT images was 80.7 HU. Analysis of images without using contrast medium showed that the material of Agilus A50 produced the mean CT attenuation of 82.6 HU, which is similar to that of original CT images. The CT attenuation measured at images acquired with the other three materials was significantly lower than that of the original images (p<0.05). After adding contrast medium, Visijet CE-NT A30 had an average CT attenuation of 90.6 HU, which is close to that of the original images without a statistically significant difference (p>0.05). In contrast, the CT attenuation measured at images acquired with other three materials (Agilus A40, A50 and Visiject CE-NT A70) was 129 HU, 135 HU and 129.6 HU, respectively, which is significantly higher than that of original CT images (p<0.05). Both Visijet CE-NT and Agilus have tensile strength and elongation close to actual patient's tissue properties producing similar CT attenuation. Visijet CE-NT A30 is considered the appropriate material for printing aorta to simulate contrast-enhanced CT imaging of type B aortic dissection. Due to the lack of body phantoms in the experiments, further research with the simulation of realistic anatomical body environment should be conducted.

Evaluation of Computed Tomography Attenuation Value of Proximal Femoral Marrow to Diagnose and Differentiate Hematologic Malignancies, Myelofibrosis, and Aplastic Anemia.

The aim of this study was to diagnose hematologic diseases using computed tomography (CT) number of proximal femoral marrow. The average CT number of marrow in hematologic diseases was measured on the caudal side of the greater trochanter. The CT numbers were -60.3 ± 16.8 in 12 patients with aplastic anemia, -53.2 ± 19.4 in 11 patients with monoclonal gammopathy of undetermined significance, -44.2 ± 21.1 in 10 normal controls, -30.9 ± 42.3 in 9 patients with chronic lymphatic leukemia, -29.8 ± 29.9 in 17 patients with benign anemia, -13.7 ± 40.9 in 33 patients with multiple myeloma, 0.32 ± 44.6 in 17 patients with myelodysplastic syndrome (MDS), 18.7 ± 40.0 in 44 patients with acute myeloid leukemia, 50.3 ± 27.4 in 13 patients with acute lymphatic leukemia, 51.5 ± 16.8 in 8 patients with myelofibrosis, and 56.4 ± 15.6 in 9 patients with chronic myeloid leukemia. Significant differences were observed between acute myeloid leukemia and MDS, between MDS and aplastic anemia, and between multiple myeloma and monoclonal gammopathy of undetermined significance (P < 0.01). The marrow CT numbers may be indicators of hematologic diseases and can be used as a diagnostic tool.

Use of Three-Dimensional Printing in Modelling an Anatomical Structure with a High Computed Tomography Attenuation Value: A Feasibility Study

Introduction: Three-dimensional (3D) printing provides an opportunity to develop anthropomorphic computed tomography (CT) phantoms with anatomical and radiological features mimicking a range of patients’ conditions, thus allowing development of individualised, low dose scanning protocols. However, previous studies of 3D printing in CT phantom development could only create anatomical structures using potassium iodide with attenuation values up to 1200 HU which is insufficient to mimic the radiological features of some high attenuation structures such as cortical bone. This study aimed at investigating the feasibility of using 3D printing in modelling cortical bone with a non-iodinated material. Methods: This study had 2 stages. Stage 1 involved a vat photopolymerisation 3D printer to directly print cube phantoms with different percentage compositions of calcium phosphate (CP) and resin (approach 1), and approach 2 using a material extrusion 3D printer to develop a cube mould for infilling of the CP with hardener as the phantom. The approach able to create the cube phantom with the CT attenuation value close to that of a tibial mid-diaphysis cortex of a real patient, 1475±205 HU was employed to develop a tibial mid-diaphysis phantom. The mean CT numbers of the cube and tibia phantoms were measured and compared with that of the original CT dataset through unpaired t-test. Results: All phantoms were scanned by CT using a lower extremity scanning protocol. The moulding approach was selected to develop the tibia middiaphysis phantom with CT attenuation value, 1434±184 HU which was not statistically significantly different from the one of the original dataset (p = 0.721). Conclusion: This study demonstrates the feasibility to use the material extrusion 3D printer to create a tibial mid-diaphysis mould for infilling of the CP as an anthropomorphic CT phantom and the attenuation value of its cortex matches the real patient’s one.

Diversity of lymphatic flow in patients with lung cancer revealed by computed tomography lymphography

This study was conducted to verify the optimal extent of lymph node dissection or sampling during lung cancer surgery based on the sentinel node (SN) map created by computed tomography (CT) lymphography. From April 2010 to January 2015, patients with clinical stage I non-small-cell lung cancer, who were candidates for lobectomy or segmentectomy with standard hilar and mediastinal lymph node dissection, and in whom bronchus reached the tumour, were enrolled. An ultrathin bronchoscope was inserted to the target bronchus under the guidance of virtual bronchoscopic navigation images. CT images of the chest were obtained 30 s after 2.5 ml of iopamidol was injected. SNs were identified when the maximum CT attenuation value of the lymph nodes on postcontrast CT images increased by 30 Hounsfield units or more compared with the precontrast images. Patients underwent lobectomy with standard lymph node dissection. SNs were identified in 36 (87.8%) of the 41 patients. The average number of SNs was 1.6 (range, 1-4). There was 1 false negative case; therefore, the accuracy of SN identification was 97.2% (35/36). In 5 (13.9%) of 36 patients, SNs were outside the lobe-specific lymph node station range (#11i from right S1, #7 from right S1, #4R from right S8, #12u from right S8, #7 and #12l from left S1 + 2). CT lymphography demonstrated the diversity of lymphatic spreading patterns and there were cases in which lymph flows are found outside the lymph node dissection range.