Hounsfield Unit Ratio Research Articles

Profile of vascular markers and CT enhancement of hyaline vascular type Castleman's disease.

Blood vessels in lymph nodes (LNs) are unique in comprising both capillaries and high endothelial venules (HEVs). Hyaline vascular type Castleman's disease accompanies robust angiogenesis, but it is unclear how the capillaries and HEVs respond. We retrospectively examined surgical specimens of hyaline vascular type unicentric Castleman's disease patients (n=24) and control LNs (n=9). We performed immunohistochemistry of CD 31 for capillaries and MECA-79 for HEVs and calculated their microvascular density. We measured CT enhancement as the ratio of Hounsfield Units (HUs) of the target lesion against muscle compared with microvascular density. The microvascular density of Castleman's disease specimen were (CD 31+) 169.7±77.6, (MECA-79+) 203.5±96.7, and the microvascular density of control LNs were (CD 31+) 80.7±20.1, (MECA-79+) 67.4±23.7, respectively. The microvascular density of both CD 31+ (P<0.001) and MECA-79+ (P<0.001) was higher in Castleman's disease. A positive correlation existed between CT HU ratio and microvascular density for both markers (CD 31: r=0.517, P=0.002; MECA-79: r=0.521, P=0.002). Intra-nodal angiogenesis of Castleman's disease involves robust proliferation of not only CD 31+ capillaries, but also MECA-79+ HVEs, which each correlated with degree of CT enhancement.

Hounsfield units: A promising non-invasive tool for diagnosing benign prostatic hyperplasia

ObjectiveThe clinical symptoms in benign prostatic hyperplasia (BPH) are directly proportional to prostate volume. We aimed to show whom and when to intervene in a noninvasive way, correlating the patient's subjective symptoms with objective diagnostic tools. Material and methodInternational Prostate Symptom Score (IPSS) was evaluated in patients who consulted the urology outpatient clinic for the first time with lower urinary tract symptoms (LUTS). Subsequently, PSA, urea, creatinine, complete urinalysis, uroflowmetry, urinary tract ultrasound and non-contrast lower abdominal computed tomography (CT) examinations were requested. Prostate central (transitional zone) zone and peripheral zone HU scores, prostatic urethral length and bladder wall Hounsfield units (HU) scores were recorded by using computed tomography (CT). The ellipsoid formula was used for ultrasonographic and tomographic measurements of prostate size (anteroposterior diameter × transverse diameter × longitudinal diameter × 0.52). ResultsA statistically significant negative correlation was found between the prostate peripheral zone/central zone HU ratio and the maximum flow rate measured in the uroflowmetry test. ConclusionThis is the first study in the literature to evaluate the correlation between voiding parameters such as Qmax, Qave and IPSS scores, and prostate and bladder wall HU scores obtained by computed tomography examination in BPH patients. A significant relationship has been detected between the peripheral zone/central zone HU ratio and Q max. Additional studies with larger patient populations could better clarify the contribution of HU in the diagnosis of BPH and treatment decision making of these patients.

Unidades Hounsfield: una herramienta no invasiva prometedora para el diagnóstico de la hiperplasia benigna de próstata

ObjectiveThe clinical symptoms in benign prostatic hyperplasia (BPH) are directly proportional to prostate volume. We aimed to show whom and when to intervene in a noninvasive way, correlating the patient's subjective symptoms with objective diagnostic tools. Material and methodInternational Prostate Symptom Score (IPSS) was evaluated in patients who consulted the urology outpatient clinic for the first time with lower urinary tract symptoms (LUTS). Subsequently, PSA, urea, creatinine, complete urinalysis, uroflowmetry, urinary tract ultrasound and non-contrast lower abdominal computed tomography (CT) examinations were requested. Prostate central (transitional zone) zone and peripheral zone HU scores, prostatic urethral length and bladder wall Hounsfield units (HU) scores were recorded by using computed tomography (CT). The ellipsoid formula was used for ultrasonographic and tomographic measurements of prostate size (anteroposterior diameter × transverse diameter × longitudinal diameter × 0.52). ResultsA statistically significant negative correlation was found between the prostate peripheral zone/central zone HU ratio and the maximum flow rate measured in the uroflowmetry test. ConclusionThis is the first study in the literature to evaluate the correlation between voiding parameters such as Qmax, Qave and IPSS scores, and prostate and bladder wall HU scores obtained by computed tomography examination in BPH patients. A significant relationship has been detected between the peripheral zone/central zone HU ratio and Q max. Additional studies with larger patient populations could better clarify the contribution of HU in the diagnosis of BPH and treatment decision making of these patients.

Differences in Aortic Intramural Hematoma Contrast Attenuation on Multi-Phase CTA Predict Long-Term Aortic Morphologic Change

Evolution of aortic intramural hematoma (IMH) over time may range from resolution to degeneration and is difficult to predict. We sought to measure differences in contrast attenuation between arterial and delayed phase computed tomography angiography (CTA) images within the IMH as a surrogate of hematoma blood flow to predict resolution versus aortic growth and/or adverse outcomes. IMH institutional data were gathered from 2005-2020. Hounsfield unit ratio (HUR) was measured as hematoma Hounsfield unit (HU), on delayed phase images divided by HU on arterial phase images on CTA. Aortic growth and effect of HUR was determined using a linear mixed effects model. Freedom from adverse aortic event, defined as the composite of intervention, recurrence of symptoms, radiographic progression, and rupture, was determined using Kaplan-Meier analysis. IMH occurred in 73 patients, of which 27 met the inclusion criteria. HUR ranged from 0.38-1.92 (mean: 0.98). Baseline aortic diameter growth independent of HUR measurement was 0.49mm/year (95% confidence interval CI: -1.23 to 2.2). With the HUR was introduced into the model, the beta coefficient for time was -5.83mm/year (95% CI: -10.4 to -1.28mm/year) and the beta coefficient for the HUR was 5.05mm/year per one-unit HUR (95% CI: 0.56 to 9.56mm/year). Thus, an HUR>1.15 would correspond to aortic growth while an HUR<1.15 would correspond to reduction in aortic diameter, consistent with IMH resolution. Aortic adverse events occurred in 13 (48%) patients, 7 (26%) patients had recurrence of symptoms, 8 (30%) required intervention, 5 (18%) progressed to dissection, and 1(4%) had aortic rupture. There was a trend towards an association between higher HUR and composite adverse aortic events (HR 3.2 per 1-unit HUR; 95% CI: 0.6-17.3; P=0.18). Increased HUR is associated with increased aortic growth and a trend toward adverse aortic events. Diminished delayed phase enhancement may predict partial or complete IMH resolution. HUR can be used to guide IMH surveillance and treatment.

Hepatic steatosis changes after early gastric cancer surgery

Background: Nonalcoholic fatty liver disease dramatically improves after bariatric surgery, primarily due to improvements in hepatic insulin sensitivity. Since the procedure for gastric cancer surgery is very similar to that for bariatric surgery, we investigated changes in fatty liver following gastrectomy for gastric cancer according to the type of surgery.Methods: We evaluated hepatic steatosis in 212 early gastric cancer patients using Hounsfield units (HUs) on non-contrast computed tomography preoperatively and 6, 12, and 24 months after surgery. We compared the preoperative and postoperative liver-to-spleen HU ratio according to the type of surgery: Billroth I, Billroth II, and total gastrectomy with Roux-en-Y reconstruction. Results: The initial results (liver/spleen HUs and the liver-to-spleen HU ratio) did not significantly differ according to surgical group. After surgery, only patients who underwent total gastrectomy with Roux-en-Y exhibited significant changes in the liver-to-spleen HU ratio at 6 months. In 26 patients who had higher initial HU levels of the spleen than the liver, the liver-to-spleen HU ratio significantly increased from 0.836 to 1.115 at 6 months, 1.109 at 12 months, and 1.102 at 24 months (P&lt;0.01). Conclusion: Significant changes in hepatic steatosis were found in even normal patients (with higher liver than spleen HU values) who underwent total gastrectomy with Roux-en-Y. Patients who initially had fatty liver also showed a significant increase in the liver-to-spleen HU ratio. These results suggest that total gastrectomy with Roux-en-Y reconstruction can have a positive effect on the improvement of hepatic steatosis.

Distinct atrial remodeling in patients with subclinical atrial fibrillation: Lessons from computed tomographic images.

AimsCardiac implanted electronic devices (CIEDs) can detect atrial high‐rate episodes (AHREs) and challenge current management of subclinical atrial fibrillation (AF).MethodsTo characterize the anatomic and functional remodeling of cardiac structures between patients with subclinical AF (SCAF) and clinical AF. The predictors for AHREs ≥6 min were also investigated.ResultsWe compared the atrial volume, dynamic function, and peri‐atrial fat between 104 CIEDs (AHREs = 0, n = 12; SCAF, n = 66; CIEDs with AF, n = 26) and 40 paroxysmal AF patients who were planning for catheter ablation (AF for ablation) using 256‐slice multidetector computed tomography for the duration of the AHREs. The maximal volume of the left atrium (LA) and LA appendage (LAA) were significantly smaller; the total emptying fraction (EF) and active EF of the LA and LAA were significantly better in the patients with SCAF than in those with clinical AF. Less peri‐atrial fat (p < 0.001) and a greater LAA/ascending aorta (AA) Hounsfield unit (HU) ratio (p < 0.05) were noted in the patients with SCAF. Significantly increased volume reduced the total EF of LA and LAA and a reduced LAA/AA HU ratio (0.91 ± 0.18 vs 0.98 ± 0.03 vs 0.97 ± 0.05, p < 0.05) were demonstrated in patients with AHREs ≥6 min compared to those with AHREs <6 min and without AHRE. Multivariate analysis showed the reduced LAA/AA HU ratio is an independent predictor for the development of AHREs ≥6 min.ConclusionAs compared to clinical AF, patients with SCAF show a more favorable LA remodeling process. Among the patients with device‐detected AHREs, worse LA remodeling and a reduced LAA/AA HU ratio were associated with the occurrence of AHREs ≥6 min. These findings may provide an incremental value for understanding SCAF.

Differences in Aortic Intramural Hematoma Contrast Attenuation On Multi-Phase CTA Predict Long-term Aortic Morphologic Change

INTRODUCTION Evolution of aortic intramural hematoma (IMH) over time ranges from resolution to degeneration and is difficult to predict. We sought to measure differences in contrast attenuation between arterial and delayed phase computed tomographic angiography (CTA) METHODS IMH institutional data were gathered for 2005-2020. Hounsfield unit ratio (HUR) was measured as hematoma Hounsfield unit (HU) on delayed phase divided by arterial phase on CTA. Aortic growth and effect of HUR were determined using a linear mixed effects model. Freedom from adverse aortic event, defined as the composite of intervention, recurrence of symptoms, and rupture, was determined using Kaplan-Meier analysis. RESULTS IMH occurred in 73 patients; 27 met the inclusion criteria (Table). HUR ranged from 0.38-1.92 (mean:0.98). Baseline aortic diameter growth independent of HUR measurement was 0.49mm/yr (95%CI:-1.23-2.2), however, in patients with HUR > 1 (increased enhancement on delays) aortic diameter grew 5.05mm/yr per HUR unit (95%CI:0.56-9.56;p=0.028). Conversely, in patients with HUR < 1 (diminished enhancement on delays), the aorta shrank consistent with IMH resolution. Aortic adverse events occurred in 14(51.9%) patients at a median of 19 days (IQR:1-95 days); 7(25.9%) patients had recurrence of symptoms, 8(29.6%) required intervention, 5(18.5%) progressed to dissection, and 1(3.7%) had aortic rupture. There was a trend toward an association between higher HUR and composite adverse aortic events (HR 3.21 per 1-unit HUR;95%CI:0.60-17.3;p=0.18). CONCLUSION Increased HUR is associated with increased aortic growth and a trend toward adverse aortic events. Diminished delayed phase enhancement may predict partial or complete IMH resolution. HUR can be used to guide IMH surveillance and treatment. Evolution of aortic intramural hematoma (IMH) over time ranges from resolution to degeneration and is difficult to predict. We sought to measure differences in contrast attenuation between arterial and delayed phase computed tomographic angiography (CTA) IMH institutional data were gathered for 2005-2020. Hounsfield unit ratio (HUR) was measured as hematoma Hounsfield unit (HU) on delayed phase divided by arterial phase on CTA. Aortic growth and effect of HUR were determined using a linear mixed effects model. Freedom from adverse aortic event, defined as the composite of intervention, recurrence of symptoms, and rupture, was determined using Kaplan-Meier analysis. IMH occurred in 73 patients; 27 met the inclusion criteria (Table). HUR ranged from 0.38-1.92 (mean:0.98). Baseline aortic diameter growth independent of HUR measurement was 0.49mm/yr (95%CI:-1.23-2.2), however, in patients with HUR > 1 (increased enhancement on delays) aortic diameter grew 5.05mm/yr per HUR unit (95%CI:0.56-9.56;p=0.028). Conversely, in patients with HUR < 1 (diminished enhancement on delays), the aorta shrank consistent with IMH resolution. Aortic adverse events occurred in 14(51.9%) patients at a median of 19 days (IQR:1-95 days); 7(25.9%) patients had recurrence of symptoms, 8(29.6%) required intervention, 5(18.5%) progressed to dissection, and 1(3.7%) had aortic rupture. There was a trend toward an association between higher HUR and composite adverse aortic events (HR 3.21 per 1-unit HUR;95%CI:0.60-17.3;p=0.18). Increased HUR is associated with increased aortic growth and a trend toward adverse aortic events. Diminished delayed phase enhancement may predict partial or complete IMH resolution. HUR can be used to guide IMH surveillance and treatment.

Computed tomography (CT) and magnetic resonance imaging (MRI) of diffuse liver disease: a multiparametric predictive modelling algorithm can aid categorization of liver parenchyma.

Liver steatosis is common and tracking disease evolution to steatohepatitis and cirrhosis is essential for risk stratification and resultant patient management. Consequently, diagnostic tools allowing categorization of liver parenchyma based on routine imaging are desirable. The study objective was to compare established mono-factorial, dynamic single parameter and iterative multiparametric routine computed tomography (CT) and magnetic resonance imaging (MRI) analyses to distinguish between liver steatosis, steatohepatitis, cirrhosis and normal liver parenchyma. A total of 285 multi-phase contrast enhanced CT and 122 MRI studies with histopathological correlation of underlying parenchymal condition were retrospectively included. Parenchymal conditions were characterized based on CT Hounsfield units (HU) or MRI signal intensity (SI) measurements and calculated HU or SI ratios between non-contrast and contrast enhanced imaging time points. First, the diagnostic accuracy of mono-factorial analyses using established, static non-contrast HU and in- to opposed phase SI change cut-offs to distinguish between parenchymal conditions was established. Second, single dynamic discriminator analyses, with optimized non-contrast and enhancement HU and SI ratio cut-off values derived from the data, employing receiver operating characteristic (ROC) curve areas under the curve (AUCs) and the Youden index for maximum accuracy, were used for disease diagnosis. Third, multifactorial analyses, employing multiple non-contrast and contrast enhanced HU and SI ratio cut-offs in a nested, predictive-modelling algorithm were performed to distinguish between normal parenchyma, liver steatosis, steatohepatitis and cirrhosis. CT and MRI analyses were performed separately. No single CT or MRI parameter showed significant difference between all four parenchymal conditions (each P>0.05). Mono-factorial static-CT-discriminator analyses identified liver steatosis with 75% accuracy. Mono-factorial MRI analyses identified steatosis with 89% accuracy. Single-dynamic CT parameter analyses identified normal parenchyma with 72% accuracy and cirrhosis with 75% accuracy. Single-dynamic MRI parameter analyses identified fatty parenchyma with 90% accuracy. Multifactorial CT analyzes identified normal parenchyma with 84%, liver steatosis with 95%, steatohepatitis with 95% and cirrhosis with 80% accuracy. Multifactorial predictive modelling of MRI parameters identified normal parenchyma with 79%, liver steatosis with 89%, steatohepatitis with 92% and cirrhosis with 89% accuracy. Multiparametric analyses of quantitative measurements derived from routine CT and MRI, utilizing a predictive modelling algorithm, can help to distinguish between normal liver parenchyma, liver steatosis, steatohepatitis and cirrhosis.

Distribution of Bone Mineral Density in the Ankle Joint: Correlation with Hindfoot Alignment

Category:Ankle; Basic Sciences/Biologics; HindfootIntroduction/Purpose:Abnormal Hindfoot Alignment (HA) has been correlated with increased failure rates in ankle fusion or replacement for osteoarthritis (OA). An altered stress distribution in the surrounding bone and abnormal Bone Mineral Density (BMD) around the native ankle may be predisposing factors for those unwanted outcomes. Cone Beam Weight Bearing CT (WBCT) has recently been used to investigate BMD and to correlate the localization of periprosthetic cysts and alignment in ankle arthroplasty. The objective of this study was to assess the spatial distribution of BMD around the ankle joint in patients with normal or abnormal HA. We hypothesized that BMD would be evenly distributed in normally-aligned ankles whilst increased medially in varus and laterally in valgus configurations.Methods:In this retrospective comparative Level III study, 60 ankles (41 adults),without any trauma or surgery affecting HA, with WBCT datasets (PedCat, Curvebeam LLC, PA-USA) were allocated to 3 groups (comparable by age, p=0.79; BMI, p=0.24; and side, p=0.93), based on the Foot Ankle Offset (FAO) values: 20 normal (0%-2), 20 varus (FAO< 0%; 35% female, age 48.8+-13 years, BMI 26.2+-2.9 kg.m-2), and 20 valgus (FAO>5%; 40% female, age 58.9+-14.6 years, BMI 28.6+-4.2 kg.m-2). Semi-Automatic Segmentation (BoneLogic, Disior Oy, Helsinki-Finland) was applied to identify bones of interest. The tibia and talus were digitally compartmented in medial (M) and lateral (L) volumes relative to the median sagittal plane. Mean Hounsfield Unit (HU) value per compartment was used to assess BMD. The primary outcome measure was the Medial over Lateral HU ratio (M/L-HU). Comparisons were performed using one-way ANOVA, Kruskal-Wallis and Chi2 tests.Results:All values of BMD were normally distributed but M/L-HU ratios were not. Mean +- standard deviation HU values in the compartments in normal cases were 523+-103 (medial tibia), 519+-115 (lateral tibia) 421+-81 (medial talus), 470+-92 (lateral talus) and 725+-109 (fibula). The mean BMD was significantly lower in all compartments in valgus cases compared to normal (all p<0.05). It was decreased in valgus vs varus in the talus (p<0.04), specifically in the medial compartment (p<0.01). The tibia M/L- HU ratio was decreased in valgus vs normal (0.87+-0.16 vs 1.01+-0.07; p=0.001) and vs varus (1.04+-0.09; p<0.001). The talus M/L-HU ratio was increased in varus cases vs normal (1+-0.22 vs 0.83+-0.09; p<0.01) and valgus (0.07+-0.19; p<0.001).Conclusion:We found that BMD in distal tibia, fibula and the talus varies with hindfoot alignment. In valgus configuration, all bone compartments were less dense compared to normal and varus. The medio-lateral ratio increased in the tibia and in the talus in varus cases, suggesting medial concentration of bone, and decreased in valgus cases, suggesting a more lateral concentration. This data supports the role of WBCT in analyzing BMD distribution. This method could be clinically useful in ankle OA to evaluate bone quality for such considerations as surgical indications or implant positioning.

The middle cerebral artery density and ratio for the diagnosis of acute ischaemic stroke in the Emergency Department.

Non-contrast computed tomography (ncCT) is the first-line imaging modality for acute ischaemic stroke diagnosis. Recognition of the early diagnostic signs of a stroke on computed tomography (CT) is crucial. The hyperdense middle cerebral artery (MCA) sign is one of these findings. We investigated the diagnostic utility of absolute MCA density (MCAD) in patients with acute MCA stroke confirmed with diffusion-weighted magnetic resonance imaging (dwMRI). We retrospectively included all patients who presented to the Emergency Department with symptoms related to an acute stroke and confirmed with a dwMRI and ncCT to this diagnostic case-control study. An expert radiologist with more than four years of experience in neuroradiology re-evaluated all ncCT images. The evaluation of MCAD and ratio were measured on axial images in Hounsfield units (HU). We included 407 patients in our study (MCA infarction: 55%, n=225; Control: 45%, n=182). We calculated the threshold for the highest sensitivity (20%) and specificity (94%) as 49 HU with the Youden J index test for MCAD and as 1.1 for MCAD ratio (sensitivity 20% and specificity 95%). MCAD >49 HU or MCAD ratio >1.1 alone or joint use of MCAD >47 HU and MCAD ratio >1.1 are useful markers to confirm the diagnosis of MCA AIS with a specificity of at least 94%. Higher MCAD values are associated with larger infarction volumes. MCAD and MCAD ratio can be used to identify patients who need early treatment, especially in situations where computed tomography angiogram or dwMRI are not readily available.

A novel method to demonstrate thrombus formation of the left atrial appendage in patients with persistent atrial fibrillation by cardiac computed tomography.

Transesophageal echocardiography (TEE) is currently the gold standard technique for diagnosing left atrial appendage (LAA) thrombi. Cardiac computed tomography (CT) has been expected to become an alternative method to TEE; however, a reliable quantitative evaluation method has not been established. We enrolled 177 patients with persistent atrial fibrillation who underwent both cardiac CT and TEE before catheter ablation. The patients were classified into two groups according to the TEE results: the thrombus group (13 patients) and non-thrombus group (164 patients). The Hounsfield unit (HU) density at the proximal LAA (LAAp) and distal LAA (LAAd) was measured on cardiac CT images. The LAAd/LAAp HU ratio and standard deviation of HU density (HU-SD) at the LAAd were evaluated. We created an algorithm by decision tree analysis to predict LAA thrombus formation using the HU ratio and HU-SD. Definite absence of LAA thrombus (Category-I) was diagnosed for 139 patients by combining the first and second branching of the decision tree (Category-Ia: HU ratio of≥0.26, Category-Ib: HU ratio of<0.26, HD-SD of≥26.94). Definite presence of LAA thrombus (Category-Ⅱ) was diagnosed for 3 patients using the third branching of the decision tree (Category-Ⅱ: HU ratio of<0.26 and HU-SD of<13.85). Highly possibility of LAA thrombus (Category-III), but not definite, was diagnosed for the remaining 35 patients; therefore, these patients required diagnostic TEE. The diagnostic accuracy of this algorithm was 0.95. We have proposed a reliable algorithm to diagnose LAA thrombus formation using the HU ratio and HU-SD.

Computed tomography radiomic features hold prognostic utility for canine lung tumors: An analytical study.

Quantitative analysis of computed tomography (CT) radiomic features is an indirect measure of tumor heterogeneity, which has been associated with prognosis in human lung carcinoma. Canine lung tumors share similar features to human lung tumors and serve as a model in which to investigate the utility of radiomic features in differentiating tumor type and prognostication. The purpose of this study was to correlate first-order radiomic features from canine pulmonary tumors to histopathologic characteristics and outcome. Disease-free survival, overall survival time and tumor-specific survival were calculated as days from the date of CT scan. Sixty-seven tumors from 65 dogs were evaluated. Fifty-six tumors were classified as primary pulmonary adenocarcinomas and 11 were non-adenocarcinomas. All dogs were treated with surgical resection; 14 dogs received adjuvant chemotherapy. Second opinion histopathology in 63 tumors confirmed the histologic diagnosis in all dogs and further characterized 53 adenocarcinomas. The median overall survival time was longer (p = 0.004) for adenocarcinomas (339d) compared to non-adenocarcinomas (55d). There was wide variation in first-order radiomic statistics across tumors. Mean Hounsfield units (HU) ratio (p = 0.042) and median mean HU ratio (p = 0.042) were higher in adenocarcinomas than in non-adenocarcinomas. For dogs with adenocarcinoma, completeness of excision was associated with overall survival (p<0.001) while higher mitotic index (p = 0.007) and histologic score (p = 0.037) were associated with shorter disease-free survival. CT-derived tumor variables prognostic for outcome included volume, maximum axial diameter, and four radiomic features: integral total, integral total mean ratio, total HU, and max mean HU ratio. Tumor volume was also significantly associated with tumor invasion (p = 0.044). Further study of radiomic features in canine lung tumors is warranted as a method to non-invasively interrogate CT images for potential predictive and prognostic utility.

The prognosis prediction significance of Hounsfield unit value for stroke patients treated by intravenous thrombolysis

BackgroundIntravenous thrombolysis (IVT) is a rapid and effective treatment in the early stage of ischemic stroke patients and the purpose of this work is to explore the significance of Hounsfield unit (HU) value in Alberta Stroke Program Early CT Score (ASPECTS) for predicting the clinical prognosis of stroke patients with middle cerebral artery occlusion (MCAO) treated by IVT.MethodsThe 84 stroke patients with MCAO treated by IVT were divided into good prognosis group (48 cases) and poor prognosis group (36 cases). HU ratio and HU difference calculated from non-contrast computed tomography between groups were analyzed.ResultsThe HU ratio of good prognosis group was higher than that in poor prognosis group and the HU difference of good prognosis group was lower than that in poor prognosis group (P < 0.05). The HU ratio and ASPECTS were negatively correlated with the infarct volume, and the HU difference was positively correlated with the infarct volume (P < 0.05). HU difference was an independent risk factor for prognosis of patients with MCAO treated by IVT. The area under the receiver operating characteristic curve of HU ratio and HU difference for prognosis was 0.743 and 0.833 respectively.ConclusionThe HU value changes are related to the clinical prognosis of stroke patients with MCAO treated by IVT, HU value may be a prognostic indicator for stroke patients with MCAO treated by IVT.

Quantitative Assessment of Hyperdense Sign Measured by Hounsfield Units is Associated with Unsuccessful Mechanical Thrombectomy.

Despite advancement in mechanical thrombectomy (MT) techniques, 10-30% of MT for large vessel occlusions (LVO) are unsuccessful. Current prediction models fail to address the association between patient-specific factors and reperfusion. We aimed to evaluate objective, easily reproducible, admission clinical and radiological biomarkers that predict unsuccessful MT. We analyzed consecutive anterior LVO MT patients at two comprehensive stroke centers. The primary outcome was unsuccessful reperfusion defined by a modified thrombolysis in cerebral infarction (mTICI) score of 0-2a. We quantitatively assessed the hyperdense vessel sign by measuring Hounsfield units (HU) on admission computed tomography (CT). Receiver operating characteristic (ROC) curves were plotted to estimate the predictive value of quantitative hyperdense middle cerebral artery (MCA) measurements (delta and ratio) and of the final model for mTICI scores. We performed multivariable logistic regression to analyze associations with outcomes. Out of 348patients 87 had unsuccessful MT. Smoking, difficult arch, vessel tortuosity, vessel calcification, diminutive vessels, truncal M1 occlusion, delta HU and HU ratio were significantly associated with unsuccessful MT in the univariate analysis. When we fitted two separate multivariate models including all significant variables and aHU measurement; delta HU <6 (odds ratio, OR = 2.07, 95% confidence intervals, CI 1.09-3.92) and HU ratio ≤1.1 (OR = 2.003, 95% CI 1.05-3.81) were independently associated with failed MT after adjustment for smoking, diminutive vessels, vessel tortuosity, and difficult arch. The area under the curve AUC<9 of the final model was 0.717. Novel radiological biomarkers on CT, CT angiography (CTA) and digital subtraction angiography (DSA) may help identify patients refractory to standard MT and prepare interventionalists for using additional alternative methods. Quantitative assessment of HU (delta and ratio) may be important in developing objective prediction tools for unsuccessful MT.

Computed tomography with Hounsfield unit assessment is useful in the diagnosis of liver lobe torsion in pet rabbits (Oryctolagus cuniculus).

Clinical signs of liver lobe torsion in rabbits are often nonspecific and mimic those that are also generally detected with gastrointestinal stasis. Nonspecific clinical signs may result in pursuit of full-body imaging such as computed tomography (CT). The aim of this multicenter, retrospective, case series study was to describe CT findings of liver lobe torsion in a group of rabbits. Computed tomography studies of six rabbits with confirmed liver lobe torsion by surgery or necropsy were evaluated. The caudate liver lobe was affected in six out of six rabbits and was enlarged, rounded, hypoattenuating, heterogeneous, and minimally to noncontrast enhancing, with scant regional peritoneal effusion. Precontrast, mean Hounsfield units (HU) of the torsed liver lobe (39.3 HU [range, 24.4-48.1 HU]) were lower than mean HU of normal liver (55.1 HU [range, 49.6-60.8 HU]), with a mean torsed:normal HU ratio of 0.71 (range, 0.49-0.91). Postcontrast, mean HU of the torsed liver lobe (38.4 HU [range, 19.7-48.9 HU]) were also lower than mean HU of normal liver (108.4 HU [range, 84.5-142.0 HU]), with a lower postcontrast mean torsed:normal HU ratio of 0.35 (range, 0.14-0.48) compared to precontrast. Mean HU of torsed liver lobes had little difference pre- and postcontrast (postcontrast HU 1.0 times the average precontrast HU [range, 0.81-1.1]), and contrast enhancement of the torsed liver lobes was on average 50% lower than in normal liver. Liver lobe torsion should be considered in rabbits with an enlarged, hypoattenuating, heterogeneous, minimally to noncontrast enhancing liver lobe, particularly the caudate lobe, and scant regional peritoneal effusion.

Quantitative CT angiography predicts large artery occlusion types and successful thrombectomy in acute ischemic stroke.

Clinical and radiological outcomes of endovascular thrombectomy (EVT) are related to etiologies of large vessel occlusion (LVO) in acute stroke. However, preprocedural computed tomography angiography (CTA) or CT perfusion imaging can hardly distinguish embolic occlusion from atherosclerotic occlusion. We hypothesized that quantitative multiphase CTA (mCTA) of LVO may predict occlusion types and thrombectomy outcome. We retrospectively evaluated the consecutive stroke patients who had undergone mCTA and EVT <6 hours of onset at two independent medical centers. The intra-arterial radiodensities of Hounsfield unit (HU) were measured to examine the HUdistal/proximal ratio using receiver operating characteristic curve analysis. The derived cut-off value was re-examined in an independent cohort. In the derivation cohort (n = 102), 81 patients (79.4%) were embolic occlusion without severe residual intracranial atherosclerotic stenosis (ICAS[-]) and 21 patients were atherosclerosis-related occlusion (ICAS[+]) based on digital subtraction angiography (DSA). The optimal cut-off to predict embolic occlusion was HU ratio <0.6 measured at 2 mm from the occlusion site (maximum area under the curve = 0.87; sensitivity 96%; specificity 81%). This cut-off also independently predicted successful recanalization using stent-retrievers and/or contact aspiration (modified Treatment in Cerebral Ischemia score ≥2b; p = 0.002) after adjusting for age, atrial fibrillation, and collateral circulation score, but not predicted favorable outcome at 3 months post stroke. Importantly, in the validation cohort (n = 95, 80% embolic occlusion), this HU ratio cut-off similarly predicted occlusion types and recanalization outcome, respectively. The mCTA-based quantitative radiodensities of acute LVO provides preprocedural predictive values of DSA-determined occlusion types and thrombectomy outcomes.

Differentiation of left atrial appendage thrombus from circulatory stasis using cardiac CT radiomics in patients with valvular heart disease.

To determine whether quantitative radiomic features from cardiac CT could differentiate the left atrial appendage (LAA) thrombus from circulatory stasis in patients with valvular heart disease. Ninety-five consecutive patients with valvular heart disease and filling defects in LAA on two-phase cardiac CT from March 2016 to August 2018 were retrospectively enrolled and classified as having thrombus or stasis by transesophageal echocardiography or cardiac surgery. The ratio of Hounsfield units in the filling defects to those in the ascending aorta (AA) was calculated on early- and late-phase CT (LAA/AAE and LAA/AAL, respectively). Radiomic features were extracted from semi-automated three-dimensional segmentation of the filling defect on early-phase CT. The diagnostic ability of radiomic features for differentiating thrombus from stasis was assessed and compared to LAA/AAE and LAA/AAL by comparing the AUC of ROC curves. Diagnostic performances of CT attenuation ratios and radiomic features were validated with an independent validation set. Thrombus was diagnosed in 25 cases and stasis in 70. Sixty-eight radiomic features were extracted. Values of 8 wavelet-transformed features were lower in thrombus than in stasis (p < 0.001). The AUC value of a radiomic feature, wavelet_LHL, for diagnosing thrombus was 0.78, which was higher than that of LAA/AAE (AUC = 0.54, p = 0.025) and similar to that of LAA/AAL (AUC = 0.76, p = 0.773). In the validation set, the AUC of wavelet_LHL was 0.71, which was higher than that of LAA/AAE (AUC = 0.57, p = 0.391) and similar to that of LAA/AAL (AUC = 0.75, p = 0.707). Quantitative radiomic features from the early phase of cardiac CT may help diagnose LAA thrombus in patients with valvular heart disease. • Wavelet-transformed grey-level non-uniformity values from radiomic analysis are significantly lower for LAA thrombus than for circulatory stasis. • Radiomic features may have an additional value for differentiating LAA thrombus from circulatory stasis when interpreting single-phase cardiac CT. • Radiomic features extracted from single-phase images may show similar diagnostic ability as conventional quantitative analysis from two-phase images.

Hounsfield Unit for Assessing Vertebral Bone Quality and Asymmetrical Vertebral Degeneration in Degenerative Lumbar Scoliosis.

Retrospective analysis. The aim of this study was to demonstrate the correlation between degenerative lumbar scoliosis (DLS) and osteoporosis based on Hounsfield unit (HU) measurement from computed tomography (CT) scans, and to investigate the asymmetrical vertebral degeneration in DLS. The correlation between DLS and osteoporosis measured by dual-energy x-ray absorptiometry (DEXA) is debated, since T-scores measured by DEXA scan can be overestimated due to abdominal vessel wall calcification, degenerative bony spurs, and facet hypertrophy. The reliability and accuracy of HU to determine osteoporosis are shown in many reports, but it has never been used to assess the vertebral bone quality for DLS patients. Nighty-five DLS patients were retrospectively reviewed. Regions of interest for HU were measured on three coronal images of the lumbar vertebrae. HU measurement of the whole vertebrae from L1 to L5 was obtained, then HU measurement within concave and convex sides were obtained separately in L5, upper and lower end vertebrae, apex vertebrae, neutral vertebrae, stable vertebrae. HU value presented a gradually increasing trend from L1 to L5. No correlation was detected between Cobb angle and mean HU value of the 5 lumbar vertebrae, or between Cobb angle and HU value of every lumbar vertebrae separately. HU value was higher within concavity than that within convexity of the same vertebrae both in major and compensatory curve. Asymmetric HU ratio in apex vertebrae positively correlated with Cobb angle. Stable vertebrae were the first proximal vertebrae that present opposite orientation of asymmetric HU ratio from the other lumbar vertebrae. Progression of degenerative scoliosis presents no correlation with osteoporosis based on HU measurement but could increase the asymmetrical vertebral degeneration, especially in apex vertebrae. Distraction of the pedicle screws at concave side, instead of compression of pedicle screws at convex side, should be a priority to correct lumbosacral curve. 3.

Bone Mineralization Changes in the Subchondral Bone of the Medial Gutter in Chronic Lateral Ankle Instability

Chronic ankle instability (CAI) induces osteoarthritis (OA) by inflicting abnormal stresses on the medial gutter. It is important to detect early OA change and to explore factors likely to induce the OA. The purpose of this study was to evaluate subchondral bone change in the medial gutter of CAI using computed tomography (CT) scans. Thirty-five ankles with CAI (CAI group) and 35 ankles without CAI (control group) were included. The region of interest (ROI) in the subchondral bone of the medial gutter on CT axial images was set on the tibia and talus. The Hounsfield unit (HU) in ROIs was measured and corrected by the HU of the fibula in the same slice. HU ratios were compared between the CAI and control groups. In the CAI group, the relationship between the HU ratio and the talar tilt angle (TTA), OA change, and the anterior talofibular ligament (ATFL) remnant quality were analyzed. The mean HU ratio in the CAI group was significantly higher than that in the control. In the CAI group, HU ratios in ≥10 degrees of TTA were significantly higher than those in <10 degrees. But there was no significant difference in the HU ratios with or without OA change in the medial gutter. A good-quality ATFL remnant showed a low HU ratio compared with that with poor quality. CAI patients exhibited subchondral bone change in the medial gutter, which suggests that the elimination of instability may help to prevent or decrease the development and/or progression of osteoarthritis. Level III, comparative series.

Differentiation of salivary gland tumors through tumor heterogeneity: a comparison between pleomorphic adenoma and Warthin tumor using CT texture analysis

We compared the diagnostic performance of CT texture analysis in single-phase CT scan with that of conventional enhancement pattern analysis in a two-phase CT scan for discrimination of salivary gland tumors, Warthin tumor (WT) from pleomorphic adenoma (PA). One hundred seventy-eight patients with PA and 84 patients with WT were selected and CT texture analysis was separately performed on early (40s) and delayed (180s) phases, after injection of the contrast agent, using commercially available software. The attenuation changes and enhancement patterns were visually and quantitatively assessed with Hounsfield units (HU). Differences between PAs and WTs were analyzed using χ2 test and independent t test. Diagnostic performance of texture parameters in single-phase CT was compared with that of dynamic enhancement pattern in two-phase CT using the McNemar test. Ratio of tumoral HU (delayed phase/early phase) was significantly higher in PAs compared with WTs (p < 0.001). Tumor heterogeneity parameters, standard deviation (SD) and entropy, were significantly lower in WTs regardless of the type of filter used (p ≤ 0.001). Mean with coarse filter (AUC = 0.944) on early phase scan and entropy with medium filter (AUC = 0.901) on delayed scan were best discriminators between PAs and WTs. Diagnostic accuracy of mean (90.5%) on early scan and entropy (84.7%) on delayed scan was not significantly different from the accuracy (89.3%) of conventional wash-out pattern for distinguishing WTs from PAs (p = 0.742, p = 0.088, respectively). Diagnostic performance of texture parameters was similar to that of quantitative enhancement pattern for differentiating WTs from PAs, with the advantage in lower radiation exposure.