Perfusion Volume Research Articles

025 The utility of nerve blood flow in the assessment of peripheral neuropathy

IntroductionAnimal and human studies of diabetes have shown significant alterations in nerve blood flow (NBF), which may also play a role in the development of neuropathy. However, the non-invasive assessment of NBF in human subjects has remained elusive until the recent technological advancements in ultrasound (US) technology. We undertook sonographic assessment of NBF in 75 patients with type 2 diabetes and correlated the findings with neuropathy severity scores and electrophysiological parameters.MethodsBlinded median and tibial nerve ultrasound scans were performed at non-entrapment sites using a high-resolution linear probe. NBF was quantified using power Doppler techniques to obtain the vessel score (VSc) and maximum perfusion intensity (MPI). Routine nerve conduction studies were performed, and neuropathy severity was assessed using the total neuropathy score (TNS). Aged- and gender-matched controls were enrolled.ResultsDiabetic nerves had higher rates of NBF detection (28%) compared to the control group (p<0.0001). Significant correlations were found between NBF parameters and nerve size (p<0.001), reported sensory symptoms (p<0.05) and neuropathy severity scores (p<0.001). The cohort with diabetes had significantly larger median (8.5 ± 0.3 mm2 vs. 7.2 ± 0.1 mm2, p<0.05) and tibial (18.0 ± 0.9 mm2 vs. 12. 8 ±0.5 mm2, p<0.05) nerves compared to controls.ConclusionsPeripheral nerve hypervascularity is detectable by US in moderate to severe diabetic neuropathy with prominent sensory dysfunction. Consistent with previous studies, the sonographic detection of NBF is a pathological finding.

THE ROLE OF HYPOVOLEMIA AND HEMOREOLOGICAL CHANGES IN THE PATHOGENESIS OF SYSTEMIC CIRCULATION DISEASES IN THE POSTRESUSCITATION PERIOD OF ACUTE MYOCARDIAL INFARCTION

Aim. To determine the role of volume imbalance and alterations in the rheological properties of blood in the pathogenesis of postresuscitation hemocirculatory disorders in dogs after clinical death due to acute myocardial infarction.Methods. Changes in systemic hemodynamics, volume and dynamic viscosity of circulating blood within a 5-minute period after clinical death due to myocardial infarction were evaluated in a dog model. 152 dogs received pentobarbital anesthesia.Results. In the early postresuscitation period after myocardial infarction dogs developed phase changes in systemic hemodynamics, volume and dynamic viscosity of circulating blood with an increase in the target indicators, followed by their decrease and final normalization as compared to the baseline. The development of postresuscitation systemic hyperperperfusion (1–3 min) was associated with significantly increased blood volume and its components. The subsequently decreased perfusion volume (5–30 min) was caused by depressed contractile function of the heart. The further progression (1–9 hours) of the hypoperfusion syndrome was mainly attributed to hypovolemia, increased dynamic viscosity of the blood and the viscoelastic properties of the red blood cells. The contribution of heart rhythm disturbances (polytopic ventricular extrasystoles) to the development of circulatory failure 4–5 hours after the successful resuscitation was determined. The subsequent hemodynamic improvements were associated with the normalization of the circulating plasma volume and hemorheological properties of the blood.Conclusion. Staged disorders of the systemic circulation formed in the recovery period after clinical death following acute myocardial infarction. They were accompanied by the alterations in the volume and dynamic viscosity of the circulating blood. Immediately after the revival, elevated values of the hemodynamic parameters were attributed to the increased blood flow as well as to the increased in plasma and globular components. The initial (5–30 min) decrease in the cardiac output was caused by impaired myocardial contractility. After a recovery period of 1–9 hours, a progressive decrease in the perfusion volume demonstrated a direct linear relationship with a deficit of blood flow and its plasma component. Heart rhythm disturbances contributed to the development of insufficient blood circulation in the 4–5-hour recovery period. Thus, hypovolemia and the hyperviscous syndrome associated with it significantly contributed to the development of insufficient systemic circulation within the 1–9-hour recovery period after clinical death provoked by myocardial infarction.

Assessment of Hepatic Perfusion Using GRASP MRI: Bringing Liver MRI on a New Level.

The aim of this study was to demonstrate the feasibility of hepatic perfusion imaging using dynamic contrast-enhanced (DCE) golden-angle radial sparse parallel (GRASP) magnetic resonance imaging (MRI) for characterizing liver parenchyma and hepatocellular carcinoma (HCC) before and after transarterial chemoembolization (TACE) as a potential alternative to volume perfusion computed tomography (VPCT). Between November 2017 and September 2018, 10 patients (male = 8; mean age, 66.5 ± 8.6 years) with HCC were included in this prospective, institutional review board-approved study. All patients underwent DCE GRASP MRI with high spatiotemporal resolution after injection of liver-specific MR contrast agent before and after TACE. In addition, VPCT was acquired before TACE serving as standard of reference. From the dynamic imaging data of DCE MRI and VPCT, perfusion maps (arterial liver perfusion [mL/100 mL/min], portal liver perfusion [mL/100 mL/min], hepatic perfusion index [%]) were calculated using a dual-input maximum slope model and compared with assess perfusion measures, lesion characteristics, and treatment response using Wilcoxon signed-rank test. To evaluate interreader agreement for measurement repeatability, the interclass correlation coefficient (ICC) was calculated. Perfusion maps could be successfully generated from all DCE MRI and VPCT data. The ICC was excellent for all perfusion maps (ICC ≥ 0.88; P ≤ 0.001). Image analyses revealed perfusion parameters for DCE MRI and VPCT within the same absolute range for tumor and liver tissue. Dynamic contrast-enhanced MRI further enabled quantitative assessment of treatment response showing a significant decrease (P ≤ 0.01) of arterial liver perfusion and hepatic perfusion index in the target lesion after TACE. Dynamic contrast-enhanced GRASP MRI allows for a reliable and robust assessment of hepatic perfusion parameters providing quantitative results comparable to VPCT and enables characterization of HCC before and after TACE, thus posing the potential to serve as an alternative to VPCT.

Artifact Reduction in the Diagnosis of Vasospasm in Computed Tomographic Perfusion: Potential of Iterative Metal Artifact Reduction.

This study aimed to analyze the possibility of artifact reduction using a new iterative metal artifact reduction algorithm (iMAR) in the diagnosis of perfusion deficits due to vasospasms and to evaluate its clinical relevance. Sixty-one volume perfusion computed tomographies of 24 patients after coiling or aneurysm clipping were reconstructed using standard-filtered back-projection and iMAR retrospectively. The degree of artifacts was evaluated as well as the size of the nonevaluable area. Diagnostic performance was evaluated compared with digital subtraction angiography. Artifacts were present in 39 of 61 volume perfusion computed tomography examinations. Image quality (score, 1.0 vs 1.6; P < 0.01) was higher and the size of the signal loss was reduced significantly by iMAR (intracranial metal artifacts, 887 mm vs 359 mm [P < 0.01]; cranial bolt, 3008 mm vs 837 mm [P < 0.01]). Digital subtraction angiography confirmed vasospasms in 11 (92%) of 12 patients. The iMAR yields higher image quality by reducing artifacts compared with filtered back-projection.

Application of venous return curve in hemodynamic intervention of shock patients

In the cardiac output (CO) and venous return (VR) balance theory proposed by Guyton in the 1950s, the right atrial pressure (Pra) was used as the dependent variable, and the VR and right cardiac function curves were recorded simultaneously. The intersection of the two curves is the current circulating blood flow under the Pra at this moment. In patients with hemodynamically unstable shock, the primary treatment goal is to restore circulating blood volume and tissue perfusion with primary methods including fluid resuscitation and the use of vasoactive drugs. This review described the dynamic evolution of VR curve in hemodynamic intervention of shock patients and the changes in physiological indicators such as mean systemic filling pressure (Pmsf), venous resistance (Rv), and stressed volume (Vs), in order to more accurately interpret changes in hemodynamic parameters and guide the clinical treatment of shock from a goal-oriented perspective.

Doppler tissue perfusion measurement is a sensitive and specific tool for a differentiation between malignant and inflammatory pancreatic tumors.

Differentiation between pancreatic malignant and inflammatory tumors presents an important diagnostic problem. The ability to recognize pancreatic malignant tumors using Doppler evaluation of tissue perfusion has been recently demonstrated. The aim of the study was to assess the diagnostic value of Dynamic Tissue Perfusion Measurement (DTPM) in the differentiation between malignant and inflammatory pancreatic tumors. The study included 60 patients (35M, 25F, age 60.9 ± 2.3 years) with a malignant (Group 1, n = 30) or inflammatory (Group 2, n = 30) pancreatic tumor undergoing endoscopic ultrasound with the evaluation of tissue perfusion by Color Doppler and a simultaneous biopsy of lesions for cytological evaluation. In 20 patients the diagnosis was verified in the postoperative histopathological examination. Flow velocity (FV) and percentiles of the distribution of perfusion intensity (PR) evaluated by DTPM were analyzed with regard to receiver-operator-characteristics. FV as well as PR were significantly higher in Group 2 compared to Group 1. A threshold of 2.0 cm/sec for FV identified patients with malignancies with a sensitivity of 83% and specificity of 86%. In multivariable regression analysis, the best PR parameter for differentiating between malignant and inflammatory tumors was 97.5% percentile, whose value of 0.922 allowed for the recognition of pancreatic malignant tumors with a sensitivity of 62% and specificity of 83% (p < 0.001). In conclusion, Color Doppler ultrasound tissue perfusion parameters are a sensitive and specific tool in the differentiation between malignant and inflammatory pancreatic tumors.

The measurement of endometrial volume and sub-endometrial vascularity to replace the traditional endometrial thickness as predictors of in-vitro fertilization success

To assess the value of endometrial thickness, volume, and sub-endometrial perfusion in women undergoing IVF. In 82 women candidate for ICSI, endometrial thickness and sub-endometrial perfusion were measured with a trans-vaginal 2 D ultrasound and 3 D power Doppler respectively on day of hCG trigger and Embryo transfer (ET). The primary outcome was the clinical pregnancy rate. Endometrial volume showing a statistically significant difference between pregnant and nonpregnant women (4.11 ± 1.19 vs. 3.4 ± 1.1 p = .019) on day of triggering and at ET (4.02 ± 1.15 vs. 3.45 ± 0.90, p = .022). VFI was significantly higher in pregnant group at both days of triggering and ET (0.54 ± 0.48 vs. 0.33 ± 0.31 and 0.47 ± 0.22 vs. 0.34 ± 0.2, p = .02). At cutoff values of 3.265 and 2.95 cm3 (70 & 80% sensitivity, specificity 64.5 & 51.6%, a positive predictive value 38.9 & 34.8%, and negative predictive value 87.0 & 88.9%) to predict pregnancy on the day of hCG trigger & ET respectively. Cutoff value for Endometrial VFI on the day of ET was 0.674 (sensitivity of 70%, specificity of 80.6%, PPV 53.8%, and NPV 89.3%). Higher endometrial volume and VFI were associated with pregnancy.

Diagnostic value of hepatic artery perfusion fraction combined with TGF-β in patients with hepatocellular carcinoma

Diagnostic value of hepatic artery perfusion fraction (HAF) combined with transforming growth factor-β (TGF-β) in the diagnosis of primary liver carcinoma (PLC) was evaluated. The clinical data of 128 PLC patients undergoing radical hepatectomy in Affiliated Hospital of Jining Medical University were regarded as the study group. Seventy-four healthy volunteers examined in Affiliated Hospital of Jining Medical University were collected as the control group. Double-antibody sandwich enzyme-linked immunosorbent assay was used to detect the expression level of serum TGF-β. The upper abdomen of the subjects was scanned by a 64-slice spiral CT, and the perfusion parameters were analyzed and calculated. According to the HAF and the expression level of TGF-β in the two groups, single and combined detection of TGF-β and HAF parameters were detected, respectively, by ROC curve. The expression of TGF-β in serum of the study group was higher than that of the control group (P<0.05). The expression level of serum TGF-β was closely related to total bilirubin, ascites, TNM stage, prothrombin time and tumor diameter. Blood flow (BF), blood volume (BV), permeability surface (PS), HAF and other perfusion parameters in the study group were higher than those in the control group (P<0.05). The specificity and sensitivity of TGF-β expression level in diagnosing PLC were 73 and 93%, respectively; the specificity and sensitivity of HAF parameter in diagnosing PLC were 73 and 100%, respectively; the specificity and sensitivity of HAF parameter combined with TGF-β expression level were 84 and 100%, respectively. TGF-β is highly expressed in serum of PLC patients; HAF parameter combined with TGF-β expression level can improve the specificity and has an important value in the diagnosis of PLC, which is worthy of clinical promotion.

Volumetric abdominal perfusion measurement using a pseudo-randomly sampled 3D fast-spin-echo (FSE) arterial spin labeling (ASL) sequence and compressed sensing reconstruction.

To improve image quality and spatial coverage for abdominal perfusion imaging by implementing an arterial spin labeling (ASL) sequence that combines variable-density 3D fast-spin-echo (FSE) with Cartesian trajectory and compressed-sensing (CS) reconstruction. A volumetric FSE sequence was modified to include background-suppressed pseudo-continuous ASL labeling and to support variable-density (VD) Poisson-disk sampling for acceleration. We additionally explored the benefits of center oversampling and variable outer k-space sampling. Fourteen healthy volunteers were scanned on a 3T scanner to test acceleration factors as well as the various sampling schemes described under synchronized-breathing to limit motion issues. A CS reconstruction was implemented using the BART toolbox to reconstruct perfusion-weighted ASL volumes, assessing the impact of acceleration, different reconstruction, and sampling strategies on image quality. CS acceleration is feasible with ASL, and a strong renal perfusion signal could be observed even at very high acceleration rates (≈15). We have shown that ASL k-space complex subtraction was desirable before CS reconstruction. Although averaging of multiple highly accelerated images helped to reduce artifacts from physiologic fluctuations, superior image quality was achieved by interleaving of different highly undersampled pseudo-random spatial sampling patterns and using 4D-CS reconstruction. Combination of these enhancements produces high-quality ASL volumes in under 5 min. High-quality isotropic ASL abdominal perfusion volumes can be obtained in healthy volunteers with a VD-FSE and CS reconstruction. This lays the groundwork for future developments toward whole abdomen free-breathing non-contrast perfusion imaging.

The dynamics of endothelial changes in vivo following standardized skin injury.

Vascular changes, that is, functional and cellular endothelial changes, are of essential importance in healing. Alongside these vascular changes, inflammatory factors and hypoxia may play an important role in recovery. To investigate the dynamics of functional and cellular endothelial changes and hypoxia in vivo following standardized skin damage caused by tape stripping. Vascular changes (endothelial cell proliferation, vascular network size, vessel diameter) and hypoxia-inducible factor-1α were examined immunohistochemically using a CD31/Ki67 double staining and HIF-1α single staining. Cutaneous perfusion was evaluated using the Twente Optical Perfusion Camera (TOPCam). The initial phase is seen to be dominated by endothelial cell proliferation, HIF-1α expression, and vasodilatation. Cutaneous perfusion intensity is particularly increased in the first 16hours. The late phase of recovery (after 72hours) is characterized by a peak of expansion of the vascular network and a second peak of endothelial cell proliferation and HIF-1α expression. Endothelial cell proliferation and HIF-1α expression appear to be (strongly) related, having maximum levels at 16hours and 72hours. Angiogenesis and HIF-1α expression are not continuous processes, but rather occur intermittently.

Glioma grading using a machine-learning framework based on optimized features obtained from T1 perfusion MRI and volumes of tumor components.

Glioma grading between intermediate grades (Grade II vs. III and Grade III vs. IV) as well as multiclass grades (Grade II vs. III vs. IV) is challenging and needs to be addressed. To develop an artificial intelligence-based methodology for glioma grading using T1 perfusion parameters and volume of tumor components, and validate the efficacy of the methodology by grading on a cohort of glioma patients. Retrospective. The development set consisted of 53 glioma patients and validation consisted of 13 glioma patients. Conventional MRI images (2D T1 -W, dual PD-T2 -W, and 3D FLAIR) and 3D T1 perfusion MRI data obtained at 3 T. Enhancing and nonenhancing components of glioma were segmented out and combined to form the region of interest (ROI) for glioma grading. Prominent vessels were removed from the selected ROI. Different T1 perfusion parameters from the ROI were combined with volume of tumor components to form the feature set for glioma grading. Optimization was carried out for selection of the statistic of the T1 perfusion parameters and the features to be used for glioma grading using sequential feature selection and random forest-based feature selection method. An optimized support vector machine (SVM) classifier was used for glioma grading. Mean ± SD, analysis of variance (ANOVA) followed by the Tukey-Kramer test, ROC analysis. Classification error for Grade II vs. III was 3.7%, for Grade III vs. IV was 5.26%, and for Grade II vs. III vs. IV was 9.43% using the proposed methodology. The mean of the values above the 90th percentile value of T1 perfusion parameters provided a maximum area under the curve (AUC) for intermediate grade differentiation. Random forest obtained optimal feature set provided better grading results than other methods using the SVM classifier. It was feasible to achieve low classification error for intermediate as well as multiclass glioma grading using an SVM classifier based on optimized features obtained from T1 perfusion MRI and volumes of tumor components. 4 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2019;50:1295-1306.

Visualization of large vessel occlusion, clot extent, and collateral supply using volume perfusion flat detector computed tomography in acute stroke patients.

Background Flat detector computed tomography angiography (FDCTA) can be reconstructed from volume perfusion flat detector computed tomography (VP-FDCT). Thus, CTA equivalent stroke imaging might be feasible within the angio suite. Purpose To evaluate the diagnostic accuracy of FDCTA in detecting large vessel occlusion (LVO) and collateral supply in acute stroke patients. Material and Methods Sixteen patients with LVO of the anterior circulation were analyzed retrospectively. Each patient underwent a multimodal CT stroke protocol, subsequent VP-FDCT, and digital subtraction angiography (DSA) for endovascular stroke therapy. Angiographic images reconstructed secondarily from VP-FDCT were evaluated with regard to visualization of LVO, Collateral Score (CS), Clot Burden Score (CBS), and image quality. Results Image quality of FDCTA was sufficient for diagnosis with a strong correlation between CTA and FDCTA (median score: CTA = 4 ± 0.447; FDCTA = 4 ± 0.5). Detection of LVO could be achieved with high sensitivity and specificity for FDCTA and CTA (97.9%, 95% confidence interval [CI] = 96.0–99.9; 92.6%, 95% CI = 84.3–100.0 vs. 96.8%, 95% CI = 93.2–100.0; 86.3%, 95% CI = 88.2–95.2). CBS and CS assessment showed no significant difference between FDCTA and CTA for both readers (reader1CBS: P = 0.751, reader1CS: P = 0.718; reader2CBS: P = 0.164; reader2CS: P = 0.582) and an excellent interrater agreement (CTACBSICC = 0.984, FDCTACBSICC = 0.951; CTACSICC = 0.754, FDCTACSICC = 0.789). Conclusion FDCTA, reconstructed from VP-FDCT data, allows reliable detection of ICA or MCA M1 segment occlusion comparable to CTA and may provide information concerning the clot extent with sufficient image quality.

Perioperative acute kidney injury

Acute kidney injury (AKI) is afrequent complication in the perioperative period and is associated with a high morbidity and mortality. AKI is an independent risk factor for adverse outcome. The Kidney Disease: Improving Global Outcome (KDIGO) guidelines define AKI based on increases in serum creatinine and/or urinary output. Since there is no causal therapy available, early detection and timely implementation of preventive measures are of particular importance. This article gives an overview of the disease picture of perioperative AKI. The recommendations on diagnostics, prevention and treatment are presented. The available evidence is summarized based on the currently available literature. New renal biomarkers demonstrate kidney stress and are able to make an early prediction of the development of AKI. The implementation of the KDIGO bundles (discontinuation of all nephrotoxic medications, optimization of the volume status and perfusion pressure, consideration of an extended functional hemodynamic monitoring, close monitoring of serum creatinine concentration and urine output, avoidance of hyperglycemia and consideration of alternatives to radiocontrast agents) and remote ischemic preconditioning have shown a significant reduction in the incidence of AKI in high-risk patients. For timely diagnosis and prevention of AKI the recommendations for action of the KDIGO guidelines should be implemented. High-risk patients should be detected early in the perioperative period in order to be able to initiate preemptive strategies in a timely manner.

Clinical practice guidelines for the provision of renal service in Hong Kong: General Nephrology.

Clinical practice guidelines for the provision of renal service in Hong Kong: General Nephrology.

Ischemic Core and Hypoperfusion Volumes Correlate With Infarct Size 24 Hours After Randomization in DEFUSE 3.

Background and Purpose- Accurate prediction of the subsequent infarct volume early after stroke onset helps determine appropriate interventions and prognosis. In the DEFUSE 3 trial (Endovascular Therapy Following Imaging Evaluation for Ischemic Stroke), we evaluated the accuracy of baseline ischemic core and hypoperfusion volumes for predicting infarct volume 24 hours after randomization to endovascular thrombectomy versus medical management. We also assessed if the union of baseline ischemic core and the volume of persistent hypoperfusion at 24 hours after randomization predicts infarct volume. Methods- Patients in DEFUSE 3 with computed tomography perfusion imaging or magnetic resonance diffusion weighted imaging/perfusion imaging acquired at baseline and at 24 hours after randomization were included. Ischemic core and Tmax >6s hypoperfusion volumes at baseline and follow-up were calculated using RAPID software and compared with the infarct volumes obtained 24 hours after randomization. Patients were stratified by reperfusion status for analyses. Results- Of 125 eligible patients, 59 patients with >90% reperfusion had a strong correlation between baseline ischemic core volume and infarct volume 24 hours postrandomization ( r=0.83; P<0.0001), and 14 patients with <10% reperfusion had a strong correlation between baseline Tmax >6s volume and infarct volume 24 hours postrandomization ( r=0.77; P<0.001). In the 52 patients with 10% to 90% reperfusion, as well as in all 125 patients, the union of the baseline ischemic core and the follow-up Tmax >6s perfusion volume was highly correlated with infarct volume 24 hours postrandomization (for N=125; r=0.83; P<0.0001), with a median absolute difference of 21.3 mL between observed and predicted infarct volumes. Conclusions- The union of the irreversibly injured ischemic core and persistently hypoperfused tissue volumes, as identified by computed tomography perfusion or magnetic resonance diffusion weighted imaging/perfusion, predicted infarct volume at 24 hours after randomization in DEFUSE 3 patients. Clinical Trial Registration- URL: https://www.clinicaltrials.gov . Unique identifier: NCT02586415.

Transarterial Chemoembolization of Hepatocellular Carcinoma Using Radiopaque Drug-Eluting Embolics: How to Pursue Periprocedural Cross-Sectional Imaging?

PurposeTo compare different imaging techniques (volume perfusion CT, cone-beam CT, and dynamic gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid–enhanced dynamic contrast–enhanced MR imaging with golden-angle radial sparse parallel MR imaging) in evaluation of transarterial chemoembolization of hepatocellular carcinoma (HCC) using radiopaque drug-eluting embolics (DEE). Materials and MethodsMR imaging and CT phantom investigation of radiopaque DEE was performed. In the clinical portion of the study, 13 patients (22 HCCs) were prospectively enrolled. All patients underwent cross-sectional imaging before and after transarterial chemoembolization using 100–300 μm radiopaque DEE. Qualitative assessment of images using a Likert scale was performed. ResultsIn the phantom study, CT-related beam-hardening artifacts were markedly visible at a concentration of 12% (v/v) radiopaque DEE; MR imaging demonstrated no significant detectable signal intensity changes. Imaging obtained before transarterial chemoembolization showed no significant difference regarding tumor depiction. Visualization of tumor feeding arteries was significantly improved with volume perfusion CT (P < .001) and cone-beam CT (P = .002) compared with MR imaging. Radiopaque DEE led to significant decrease in tumor depiction (P = .001) and significant increase of beam-hardening artifacts (P = .012) using volume perfusion CT before versus after transarterial chemoembolization. Greater residual arterial tumor enhancement was detected with MR imaging (10 HCCs) compared with volume perfusion CT (8 HCCs) and cone-beam CT (6 HCCs). ConclusionsUsing radiopaque DEE, the imaging modalities provided comparable early treatment assessment. In HCCs with dense accumulation of radiopaque DEE, treatment assessment using volume perfusion CT or cone-beam CT may be impaired owing to resulting beam-hardening artifacts and contrast stasis. Dynamic contrast–enhanced MR imaging may add value in detection of residual arterial tumor enhancement.

A Cadaveric Study of Cutaneous Vascular Anatomy about the Elbow Using Computed Tomography Angiography.

The posterior approach is a commonly employed exposure of the elbow that provides excellent visualization and efficacy for various orthopedic procedures, including total elbow arthroplasty (TEA) and fracture care. The posterior approach to the elbow has been associated with an increased rate of wound complications, including infection, skin necrosis, and wound dehiscence. Despite an association between these complications and decreased elbow perfusion, data regarding the intrinsic anatomic etiology for preferential complications in this area has been scarcely reported in the literature. This study characterizes the subdermal and cutaneous vascular perfusion about the elbow by describing the predominant direction of circulation, subdermal anastomoses, and volume of perfusion through cadaveric modeling using computed tomography angiography (CTA). Fifteen upper extremity cadaver specimens were prepared with injection of radiographic contrast directly into the axillary artery immediately preceding CTA imaging of each specimen. Sectra IDS7 software for Windows was used for analysis of all images to produce superimposed axial and 3-D reconstructions of each CTA series. From these images it was discerned that the predominant direction of flow in the posterior elbow integument is anterior medial to posterior lateral. Both the posterior medial and posterior lateral subdermal vascular networks emanate from proximally derived medial arterial sources with few anastomoses and minimal collateral perfusion from the anterolateral location. Consequently, it is important to preserve medial subdermal vascular structures to prevent ischemic wound complications. This is especially true in previously incised elbow integuments. Clin. Anat. 32:509-514, 2019. © 2019 Wiley Periodicals, Inc.

Abstract WP61: Union of Ischemic Core and Hypoperfusion Volume Correlates With 24-hour Infarct Size in DEFUSE 3

Background and Purpose: Accurate prediction of 24-hour infarct volume early after stroke onset helps determine appropriate interventions and prognosis. In the Endovascular Therapy Following Imaging Evaluation for Ischemic Stroke (DEFUSE 3) trial, we evaluated the accuracy of early ischemic core and hypoperfusion volumes for predicting infarct volume 24 hours after randomization to endovascular thrombectomy vs. medical management. We also assessed if the volume of persistent hypoperfusion at 24 hours predicts infarct volume. Methods: Patients in DEFUSE 3 with CT or MRI DWI/perfusion imaging acquired at baseline and at 24 hours after randomization were included. Ischemic core and Tmax&gt;6s hypoperfusion volumes at baseline and 24 hours were calculated using RAPID software and compared with the 24-hour infarct volumes. Patients were stratified by reperfusion status for analyses. Results: Of 125 eligible patients, 59 patients with &gt;90% reperfusion had a strong correlation between baseline ischemic core volumes and 24-hour infarct volume (r = 0.83; p &lt; 0.0001), and 14 patients with &lt;10% reperfusion had a strong correlation between baseline Tmax&gt;6s volume and 24-hour infarct volume (r = 0.77; p &lt; 0.001). In the 52 patients with 10-90% reperfusion, as well as in all 125 patients, the union of the baseline ischemic core and the Tmax&gt;6s perfusion volume at 24 hours was highly correlated with 24-hour infarct volume (for N=125, r = 0.83; p &lt; 0.0001), with a median absolute difference of 21.3 ml between observed and predicted infarct volumes. Conclusions: The union of the irreversibly injured ischemic core and critically hypoperfused tissue volumes, as identified by CT perfusion or MR DWI/perfusion, predicted infarct volume at 24 hours in DEFUSE 3 patients. Clinical Trial Registration - URL: http://www.clinicaltrials.gov. Unique identifier: NCT02586415

Automatic Respiratory Gating Hepatic DCEUS-based Dual-phase Multi-parametric Functional Perfusion Imaging using a Derivative Principal Component Analysis.

Purpose: Angiogenesis in liver cancers can be characterized by hepatic functional perfusion imaging (FPI) on the basis of dynamic contrast-enhanced ultrasound (DCEUS). However, accuracy is limited by breathing motion which results in out-of-plane image artifacts. Current hepatic FPI studies do not correct for these artifacts and lack the evaluation of correction accuracy. Thus, a hepatic DCEUS-based dual-phase multi-parametric FPI (DM-FPI) scheme using a derivative principal component analysis (PCA) respiratory gating is proposed to overcome these limitations.Materials and Methods: By considering severe 3D out-of-plane respiratory motions, the proposed scheme's accuracy was verified with in vitro DCEUS experiments in a flow model mimicking a hepatic vein. The feasibility was further demonstrated by considering in vivo DCEUS measurements in normal rabbit livers, and hepatic cavernous hemangioma and hepatocellular carcinoma in patients. After respiratory kinetics was extracted through PCA of DCEUS sequences under free-breathing condition, dual-phase respiratory gating microbubble kinetics was identified by using a derivative PCA zero-crossing dual-phase detection, respectively. Six dual-phase hemodynamic parameters were estimated from the dual-phase microbubble kinetics and DM-FPI was then reconstructed via color-coding to quantify 2.5D angiogenic hemodynamic distribution for live tumors.Results: Compared with no respiratory gating, the mean square error of respiratory gating DM-FPI decreased by 1893.9 ± 965.4 (p < 0.05), and mean noise coefficients decreased by 17.5 ± 7.1 (p < 0.05), whereas correlation coefficients improved by 0.4 ± 0.2 (p < 0.01). DM-FPI observably removed severe respiratory motion artifacts on PFI and markedly enhanced the accuracy and robustness both in vitro and in vivo.Conclusions: DM-FPI precisely characterized and distinguished the heterogeneous angiogenic hemodynamics about perfusion volume, blood flow and flow rate within two anatomical sections in the normal liver, and in benign and malignant hepatic tumors. DCEUS-based DM-FPI scheme might be a useful tool to help clinicians diagnose and provide suitable therapies for liver tumors.

Estimation of diffusion, perfusion and fractional volumes using a multi-compartment relaxation-compensated intravoxel incoherent motion (IVIM) signal model

Compartmental diffusion MRI models that account for intravoxel incoherent motion (IVIM) of blood perfusion allow for estimation of the fractional volume of the microvascular compartment. Conventional IVIM models are known to be biased by not accounting for partial volume effects caused by free water and cerebrospinal fluid (CSF), or for tissue-dependent relaxation effects. In this work, a three-compartment model (tissue, free water and blood) that includes relaxation terms is introduced. To estimate the model parameters, in vivo human data were collected with multiple echo times (TE), inversion times (TI) and b-values, which allowed a direct relaxation estimate alongside estimation of perfusion, diffusion and fractional volume parameters. Compared to conventional two-compartment models (with and without relaxation compensation), the three-compartment model showed less effects of CSF contamination. The proposed model yielded significantly different volume fractions of blood and tissue compared to the non-relaxation-compensated model, as well as to the conventional two-compartment model, suggesting that previously reported parameter ranges, using models that do not account for relaxation, should be reconsidered.