A new method to study changes in microvascular blood volume in muscle and adipose tissue: real-time imaging in humans and rat

2011 ◽  
Vol 301 (2) ◽  
pp. H450-H458 ◽  
Author(s):  
Kim A. Sjøberg ◽  
Stephen Rattigan ◽  
Natalie Hiscock ◽  
Erik A. Richter ◽  
Bente Kiens
Keyword(s):  
Adipose Tissue ◽  
Steady State ◽  
Real Time ◽  
Blood Volume ◽  
Subcutaneous Adipose Tissue ◽  
Contrast Enhanced Ultrasound ◽  
Perfusion Rate ◽  
Real Time Imaging ◽  
Contrast Enhanced ◽  
Subcutaneous Adipose

We employed and evaluated a new application of contrast-enhanced ultrasound for real-time imaging of changes in microvascular blood volume (MBV) in tissues in females, males, and rat. Continuous real-time imaging was performed using contrast-enhanced ultrasound to quantify infused gas-filled microbubbles in the microcirculation. It was necessary to infuse microbubbles for a minimum of 5–7 min to obtain steady-state bubble concentration, a prerequisite for making comparisons between different physiological states. Insulin clamped at a submaximal concentration (∼75 μU/ml) increased MBV by 27 and 39% in females and males, respectively, and by 30% in female subcutaneous adipose tissue. There was no difference in the ability of insulin to increase muscle MBV in females and males, and microvascular perfusion rate was not increased significantly by insulin. However, perfusion rate of the microvascular space was higher in females compared with males. In rats, insulin clamped at a maximal concentration increased muscle MBV by 60%. Large increases in microvascular volume and perfusion rate were detected during electrical stimulation of muscle in rats and immediately after exercise in humans. We have demonstrated that real-time imaging of changes in MBV is possible in human and rat muscle and in subcutaneous adipose tissue and that the method is sensitive enough to pick up relatively small changes in MBV when performed with due consideration of steady-state microbubble concentration. Because of real-time imaging, the method has wide applications for determining MBV in different organs during various physiological or pathophysiological conditions.

scholarly journals Subcutaneous, Paracardiac, and Epicardial Fat CT Density Before/After Contrast Injection: Any Correlation with CAD?

2021 ◽  
Vol 10 (4) ◽  
pp. 735
Author(s):  
Caterina Beatrice Monti ◽  
Davide Capra ◽  
Alexis Malavazos ◽  
Giorgia Florini ◽  
Carlo Parietti ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Subcutaneous Adipose Tissue ◽  
Epicardial Adipose Tissue ◽  
Tissue Density ◽  
Contrast Enhanced ◽  
Potential Biomarker ◽  
Artery Disease ◽  
Ct Density ◽  
Enhanced Computed Tomography ◽  
Subcutaneous Adipose

Adipose tissue, in particular epicardial adipose tissue, has been identified as a potential biomarker of cardiovascular pathologies such as coronary artery disease (CAD) in the light of its metabolic activity and close anatomic and pathophysiologic relationship to the heart. Our purpose was to evaluate epicardial adipose tissue density at both unenhanced and contrast-enhanced computed tomography (CT), along with CT densities of paracardiac and subcutaneous adipose tissue, as well as the relations of such densities with CAD. We retrospectively reviewed patients who underwent cardiac CT at our institution for CAD assessment. We segmented regions of interest on epicardial, paracardiac, and subcutaneous adipose tissue on unenhanced and contrast-enhanced scans. A total of 480 patients were included, 164 of them presenting with CAD. Median epicardial adipose tissue density measured on contrast-enhanced scans (−81.5 HU; interquartile range −84.9 to −78.0) was higher than that measured on unenhanced scans (−73.4 HU; −76.9 to −69.4) (p < 0.001), whereas paracardiac and subcutaneous adipose tissue densities were not (p ≥ 0.055). Patients with or without CAD, did not show significant differences in density of epicardial, paracardiac, and subcutaneous adipose tissue either on unenhanced or contrast-enhanced scans (p ≥ 0.092). CAD patients may experience different phenomena (inflammation, fibrosis, increase in adipose depots) leading to rises or drops in epicardial adipose tissue density, resulting in variations that are difficult to detect.

Lipolysis in human adipose tissue during exercise: comparison of microdialysis and a-v measurements

2002 ◽  
Vol 92 (3) ◽  
pp. 1310-1316 ◽  
Author(s):  
Kai Henrik Wiborg Lange ◽  
Jeanne Lorentsen ◽  
Fredrik Isaksson ◽  
Lene Simonsen ◽  
Jens Bülow ◽  
...  
Keyword(s):  
Adipose Tissue ◽  
Steady State ◽  
Subcutaneous Adipose Tissue ◽  
Human Adipose Tissue ◽  
Glycerol Concentration ◽  
Early Exercise ◽  
Adipose Tissue Lipolysis ◽  
Subcutaneous Abdominal Adipose Tissue ◽  
Subcutaneous Adipose

Subcutaneous adipose tissue lipolysis was studied in vivo by Fick's arteriovenous (a-v) principle using either calculated (microdialysis) or directly measured (catheterization) adipose tissue venous glycerol concentration. We compared results during steady-state (rest and prolonged continuous exercise), as well as during non-steady-state (onset of exercise and early exercise) experimental settings. Fourteen healthy women [age: 74 ± 1 (SE) yr] were studied at rest and during 60-min continuous bicycling at 60% of peak O2 uptake. Calculated and measured subcutaneous abdominal adipose tissue venous glycerol concentrations increased substantially from rest to exercise but were similar both at rest and during later stages of exercise. In contrast, during the initial ∼40 min of exercise, calculated glycerol concentration was significantly lower (∼40%) than measured adipose tissue venous glycerol concentration. Despite several methodological limitations inherent to both techniques, the results strongly suggest that microdialysis and catheterization provide similar estimates of subcutaneous adipose tissue lipolysis in steady-state experimental settings like rest and continuous prolonged exercise. However, during shorter periods of exercise (<40 min), the results from the two techniques may differ quantitatively in the studied subjects. Caution should, therefore, be taken when lipolysis is evaluated, based on results obtained by the two techniques under non-steady-state conditions.

scholarly journals Transcranial contrast-enhanced ultrasound in the rat brain reveals substantial hyperperfusion acutely post-stroke

2020 ◽  
Vol 40 (5) ◽  
pp. 939-953
Author(s):  
Dino Premilovac ◽  
Sarah J Blackwood ◽  
Ciaran J Ramsay ◽  
Michelle A Keske ◽  
David W Howells ◽  
...  
Keyword(s):  
Real Time ◽  
Blood Volume ◽  
Cerebral Perfusion ◽  
Brain Regions ◽  
Artery Occlusion ◽  
Cerebral Hemodynamics ◽  
Stroke Severity ◽  
Contrast Enhanced Ultrasound ◽  
Contrast Enhanced ◽  
Time Assessment

Direct and real-time assessment of cerebral hemodynamics is key to improving our understanding of cerebral blood flow regulation in health and disease states such as stroke. While a number of sophisticated imaging platforms enable assessment of cerebral perfusion, most are limited either spatially or temporally. Here, we applied transcranial contrast-enhanced ultrasound (CEU) to measure cerebral perfusion in real-time through the intact rat skull before, during and after ischemic stroke, induced by intraluminal filament middle cerebral artery occlusion (MCAO). We demonstrate expected decreases in cortical and striatal blood volume, flow velocity and perfusion during MCAO. After filament retraction, blood volume and perfusion increased two-fold above baseline, indicative of acute hyperperfusion. Adjacent brain regions to the ischemic area and the contralateral hemisphere had increased blood volume during MCAO. We assessed our data using wavelet analysis to demonstrate striking vasomotion changes in the ischemic and contralateral cortices during MCAO and reperfusion. In conclusion, we demonstrate the application of CEU for real-time assessment of cerebral hemodynamics and show that the ischemic regions exhibit striking hyperemia post-MCAO. Whether this post-stoke hyperperfusion is sustained long-term and contributes to stroke severity is not known.

scholarly journals GIP-induced vasodilation in human adipose tissue involves capillary recruitment

2019 ◽  
Vol 8 (6) ◽  
pp. 806-813 ◽  
Author(s):  
Meena Asmar ◽  
Ali Asmar ◽  
Lene Simonsen ◽  
Flemming Dela ◽  
Jens Juul Holst ◽  
...  
Keyword(s):  
Blood Flow ◽  
Adipose Tissue ◽  
Blood Volume ◽  
Tissue Blood Flow ◽  
Contrast Enhanced Ultrasound ◽  
Lipid Uptake ◽  
Abdominal Adipose Tissue ◽  
Capillary Recruitment ◽  
Contrast Enhanced ◽  
Subcutaneous Abdominal Adipose Tissue

Glucose-dependent insulinotropic polypeptide (GIP) in combination with hyperinsulinemia increase blood flow and triglyceride clearance in subcutaneous abdominal adipose tissue in lean humans. The present experiments were performed to determine whether the increase involves capillary recruitment. Eight lean healthy volunteers were studied before and after 1 h infusion of GIP or saline during a hyperglycemic–hyperinsulinemic clamp, raising plasma glucose and insulin to postprandial levels. Subcutaneous abdominal adipose tissue blood flow (ATBF) was measured by the 133Xenon clearance technique, and microvascular blood volume was determined by contrast-enhanced ultrasound imaging. During infusion of saline and the clamp, both ATBF (2.7 ± 0.5 mL/min 100 g/tissue) and microvascular blood volume remained unchanged throughout the experiments. During GIP infusion and the clamp, ATBF increased ~fourfold to 11.4 ± 1.9 mL/min 100 g/tissue, P < 0.001. Likewise, the contrast-enhanced ultrasound signal intensity, a measure of the microvascular blood volume, increased significantly 1 h after infusion of GIP and the clamp (P = 0.003), but not in the control experiments. In conclusion, the increase in ATBF during GIP infusion involves recruitment of capillaries in healthy lean subjects, which probably increases the interaction of circulating lipoproteins with lipoprotein lipase, thus promoting adipose tissue lipid uptake.

Contrast-enhanced ultrasound of the abdominal aorta – current status and future perspectives

VASA ◽  
2019 ◽  
Vol 48 (2) ◽  
pp. 115-125 ◽  
Author(s):  
Xin Li ◽  
Daniel Staub ◽  
Vasileios Rafailidis ◽  
Mohammed Al-Natour ◽  
Sanjeeva Kalva ◽  
...  
Keyword(s):  
Real Time ◽  
Vascular Diseases ◽  
Aneurysm Rupture ◽  
Vasa Vasorum ◽  
Current Status ◽  
Contrast Enhanced Ultrasound ◽  
Aortic Diseases ◽  
Cross Sectional ◽  
Vascular Abnormalities ◽  
Contrast Enhanced

Abstract. Ultrasound has been established as an important diagnostic tool in assessing vascular abnormalities. Standard B-mode and Doppler techniques have inherent limitations with regards to detection of slow flow and small vasculature. Contrast-enhanced ultrasound (CEUS) is a complementary tool and is useful in assessing both the macro- and microvascular anatomy of the aorta. CEUS can also provide valuable physiological information in real-time scanning sessions due to the physical and safety profiles of the administered microbubbles. From a macrovascular perspective, CEUS has been used to characterize aortic aneurysm rupture, dissection and endoleaks post-EVAR repair. With regard to microvasculature CEUS enables imaging of adventitial vasa vasorum thereby assessing aortic inflammation processes, such as monitoring treatment response in chronic periaortitis. CEUS may have additional clinical utility since adventitial vasa vasorum has important implications in the pathogenesis of aortic diseases. In recent years, there have been an increasing number of studies comparing CEUS to cross-sectional imaging for aortic applications. For endoleak surveillance CEUS has been shown to be equal or in certain cases superior in comparison to CT angiography. The recent advancement of CEUS software along with the ongoing development of drug-eluting contrast microbubbles has allowed improved targeted detection and real-time ultrasound guided therapy for aortic vasa vasorum inflammation and neovascularization in animal models. Therefore, CEUS is uniquely suited to comprehensively assess and potentially treat aortic vascular diseases in the future.

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