Real-time Perfusion Research Articles

Real-Time Quantitative Measurements of Foot Perfusion in Patients With Critical Limb Ischemia.

Current methods of evaluating adequacy of endovascular procedures are imperfect and do not always predict which patients will do well. The purpose of this study was to evaluate the role of real-time quantitative measurements of perfusion among patients with critical limb ischemia. Thirty-four patients with critical limb ischemia undergoing endovascular treatment were recruited. Perfusion Images of the foot were obtained pre and post successful angioplasty using an SPY Elite System (Novadaq Technologies, Ontario, Canada). Patients were followed for 6 months. Subsequently a logistic regression was performed to determine whether intraprocedural perfusion parameters predicted the odds of wound healing. Twenty-nine patients had successful angioplasty. Median age was 69.5% ± 8.3; 75% were men and 64% were diabetic. Rutherford stages were (4%-39%, 5%-57%, 6%-4%), and the average target limb ankle-brachial index (ABI) was 0.58 (SD 2.24). There was no significant correlation between the ABI and perfusion parameters. Inflow perfusion rate correlated significantly with Rutherford stage (Spearman rho 0.398, P = .036). After successful angioplasty 39% had a decrease in inflow rate and 57% had a decreased total inflow. In all, 25 patients completed 6 months of follow-up. Resolution of rest pain and/or healing of the ischemic wound occurred in 10 (40%) patients at 1 month, 4 (16%) at 3 months, and 2 (8%) at 6 months. One patient underwent a major amputation at 2 months. Eight (32%) patients never healed or had persistent rest pain. None of the real-time perfusion variables were significant predictors of wound healing. Many patients experience a paradoxical decrease in perfusion following successful angioplasty suggesting perfusion may not correlate with angiographic outcome, possibly due to microemboli, microvascular disease, or vasospasm. Real-time perfusion imaging following intra-arterial infusion of indocyanine green does not predict the odds of wound healing.

Fast High-Precision Electrical Impedance Tomography System for Real-Time Perfusion Imaging

Periodical changes in bioimpedance caused by blood perfusion are relatively fast and weak; therefore, a fast, high-precision imaging system is required. A novel electrical impedance tomography (EIT) system is proposed for real-time perfusion imaging. Synchronous parallel sampling is combined with timely excitation switching control to achieve fast acquisition and maintain high sampling accuracy. To further improve the overall precision of the system, a bipolar-mirror feedback voltage controlled current source and an internal calibration unit was used to improve the current precision and measurement accuracy, respectively. Test results of the resistor model show that the system has a signal-to-noise ratio of 81 dB at 50 kHz and achieves an imaging rate of 100 frames/ s. A preliminary test shows that the reconstructed EIT images reveal a complete cycle of blood exchange between the heart and lungs. Our system may provide a useful research platform for real-time and non-invasive blood perfusion imaging, which could be used in in vivo studies.

Diagnosis of gallbladder polypoid lesions using contrast enhanced ultrasound

Purpose Effectiveness of differential diagnosis of gallbladder polypoid lesions using contrast enhanced ultrasound (CEUS) examination by perflubutane (Sonazoid®:Daiichi-Sankyo, Tokyo). Material & Methods CEUS was performed on 183 patients with gallbladder polypoid lesions.It consists of 10 adenocarcinomas, 2 adenomas, 129 benign polyps and 42 adenomyomatosis (fundal type). For benigndiseases, we examined cases where the size was 6 mm or more and could be observed for more than one year. Ultrasound was performed using TUS-A500 (Aplio 500) (Canon MedicalSystems. Tokyo) and prosound alpha10 (Hitachi Aloka Medical,Ltd.Tokyo). First, the largest cross section of a lesion was visualized using B-mode and infusion of Sonazoid. The characteristics and behavior of blood flow in the lesion in the early vascular phase were examined over approximately 30 sec. Thereafter, observation was continued accordingly for about 3 min. Sonazoid infusion using contrast harmonic imaging and real-time perfusion Imaging. Results Gallbladder carcinoma showed hypervascular staining and “eruption sign” was apparent in 60%. The “eruption sign” showed an image of a vigorously boiling water that was splashing up from the entire lesion. Blood flow imaging revealed irregular size and buckling, including tortuous vessels and erratic blood flow in 70%. Gallbladder adenoma showed “eruption sign” was apparent in 50%. The irregular size, tortuous vessels and eruption signs of blood flow imaging were 83.3% as an index of neoplastic. Gallbladder benign polyp, staining was scattered within them, and “flicker sign” was observed in 93.8%. The “flicker sign” showed an image of bubbling pre-boiled hot water. Five cases (3.9%) showed a diffused and hypervascular staining pattern. The staining time was shorter than gallbladder carcinoma. Blood flow image showed normal vessels without buckling. Linear blood flow of the stalk of gallbladder polyp was also characteristic. Gallbladder adenomyomatosis (fundal type), staining was scattered and mild flicker signs were observed in 85.7%. Blood flow at the surface of the prominence and internal Rokitansky-Aschoff sinus was observed clearity. Conclusions CEUS can clarify the hemodynamics and blood flow images and are useful for the differential diagnosis of gallbladder polypoid lesions.

Clinical Outcome of Patients With Inducible Capillary Blood Flow Abnormalities During Demand Stress in the Presence or Absence of Angiographic Coronary Disease.

Our aim was to determine the cardiovascular outcome of patients with capillary blood flow (CBF) abnormalities detected during demand stress in the absence of obstructive coronary artery disease. We identified 380 consecutive patients referred for coronary angiography (CA) after dobutamine or exercise stress echocardiography (SE) between 2008 and 2013 performed with real-time perfusion imaging to examine myocardial CBF with a continuous ultrasound contrast infusion. Patients with left ventricular ejection fraction <40% were excluded. There were 3 groups based on results: positive SE/negative CA, patients who had abnormal regional CBF but no significant angiographic disease; positive SE/positive CA, those with abnormal CBF and significant disease on subsequent CA; and negative SE/negative CA, patients with normal CBF and negative CA. Event-free survival examining death and nonfatal myocardial infarction was compared. Median follow-up was 4 years. There were 91 positive SE/negative CA, 189 positive SE/positive CA, and 100 negative SE/negative CA patients over the study period. The positive SE/negative CA patients were more frequently women and had a lower prevalence of hypertension and hyperlipidemia (all P<0.001). Analysis of event-free survival with Cox regression demonstrated that death/nonfatal myocardial infarction rates were higher in the positive SE/positive CA (hazard ratio, 2.10; CI, 1.02-4.29) and positive SE/negative CA (hazard ratio, 2.02; CI, 0.99-4.31) groups when compared with negative SE/negative CA groups. Patients with inducible CBF abnormalities in the absence of significant obstructive disease at CA still have similar death/nonfatal myocardial infarction rates as those with significant disease at CA.

Quantifying and Trending the Thermal Signal as an Index of Perfusion in Patients Sedated with Propofol.

We examined the feasibility of a thermal imager smart phone attachment as a potential proxy of skin perfusion by assessing shifts in skin temperature following administration of the vasodilatory anesthetic propofol. Four limb distal extremity thermal images were taken before propofol administration and at 5-min intervals thereafter during monitored anesthesia. The study enrolled 60 patients with ages ranging from 1.3 to 18 years (mean 10.7 years old) from April 2016 to January 2017. Five minutes following propofol administration, the median temperature differential (delta temperature) between the core and extremity skin significantly decreased in both upper and lower extremities, 7.9 to 3.6 °C (p < 0.0001) and 12.1 to 6.9 °C (p < 0.0001), respectively. By 10 min, the median delta temperatures further decreased significantly in the upper (p = 0.0068) and lower extremities (p = 0.0018). There was a concordant decrease in mean blood pressure (MBP). These trends reverted back when the subject awoke. There was no significant difference between the four operators who used the camera (p = 0.0831). Blood pressure and time temperature change was the only value of significance. Mobil thermal imaging represents a non-invasive modality to assess perfusion in real time. Further studies are required to validate the clinical utility.

Mesenteric ischemia in acute aortic dissection.

Despite improved outcomes in acute aortic dissection in Japan, mesenteric ischemia remains a problem. This is largely due to difficulties in early diagnosis and treatment. To address this problem, this article will review several diagnostic modalities such as ultrasound and near-infrared spectroscopy, as well as surgical treatments. Ultrasound is useful for assessing mesenteric ischemia because it can be performed at bedside and it provides information on both morphology and perfusion in real time without exposure to radiation or contrast media. Malperfusion can be assessed at four sites between the aorta and intestine. Two causes of malperfusion, aortic type and branch type, can be assessed. Lack of intestinal movement can also indicate ischemia. Near-infrared light assesses regional oxygen saturation in the tissue, while fluorescent visualization using indocyanin green demonstrates vessels and tissue perfusion. Information provided by these imaging modalities can help guide treatment strategies. Future treatments include endovascular interventions combined with conventional surgical procedures. The hybrid OR may be helpful for such sophisticated treatments.

Long-Term Association of Dipyridamole Stress Myocardial Contrast Echocardiography versus Single-Photon Emission Computed Tomography with Clinical Outcomes in Patients with Known or Suspected Coronary Artery Disease

Single-photon emission computed tomography (SPECT) is a well-established method to evaluate patients with coronary artery disease. Myocardial contrast echocardiography (MCE) is an imaging technique that allows the assessment of myocardial perfusion in real time. Previous research has shown that vasodilator MCE is superior to SPECT for the prediction of hard events. The aim of this study was to investigate the long-term association of SPECT and MCE with clinical outcomes in patients with known or suspected coronary artery disease. Accordingly, 258 patients who underwent MCE and SPECT as part of multicenter studies performed prospectively were followed up for hard events (all-cause mortality and nonfatal myocardial infarction). The mean age was 63.4±5.5years, 186 (72.1%) were men, and 32 (12.4%) had left ventricular systolic dysfunction. We calculated the ratio of the number of abnormal segments (at rest and/or stress) to the total number of segments expressed as MCE and SPECT indices. Over a mean follow-up period of 80.4±6.1months, 46 patients had hard events. MCE and SPECT indices were associated with all-cause mortality on univariate analysis (P=.008 and P=.035, respectively) but only MCE index was independently associated with hard events (hazard ratio, 4.24; 95% CI, 1.27-14.15; P=.019), beyond clinical data and left ventricular function, and independently associated with hard cardiac events (hazard ratio, 4.78; 95% CI, 1.06-21.59; P=.042). MCE but not SPECT showed a long-term association with outcome. These results thus favor the routine use of MCE in the long-term assessment of patients with known or suspected coronary artery disease.

Optical techniques for perfusion monitoring of the gastric tube after esophagectomy: a review of technologies and thresholds.

Anastomotic leakage is one of the most severe complications after esophageal resection with gastric tube reconstruction. Impaired perfusion of the gastric fundus is seen as the main contributing factor for this complication. Optical modalities show potential in recognizing compromised perfusion in real time, when ischemia is still reversible. This review provides an overview of optical techniques with the aim to evaluate the (1) quantitative measurement of change in perfusion in gastric tube reconstruction and (2) to test which parameters are the most predictive for anastomotic leakage.A Pubmed, MEDLINE, and Embase search was performed and articles on laser Doppler flowmetry (LDF), near-infrared spectroscopy (NIRS), laser speckle contrast imaging (LSCI), fluorescence imaging (FI), sidestream darkfield microscopy (SDF), and optical coherence tomography (OCT) regarding blood flow in gastric tube surgery were reviewed. Two independent reviewers critically appraised articles and extracted the data: Primary outcome was quantitative measure of perfusion change; secondary outcome was successful prediction of necrosis or anastomotic leakage by measured perfusion parameters.Thirty-three articles (including 973 patients and 73 animals) were selected for data extraction, quality assessment, and risk of bias (QUADAS-2). LDF, NIRS, LSCI, and FI were investigated in gastric tube surgery; all had a medium level of evidence. IDEAL stage ranges from 1 to 3. Most articles were found on LDF (n=12), which is able to measure perfusion in arbitrary perfusion units with a significant lower amount in tissue with necrosis development and on FI (n=12). With FI blood flow routes could be observed and flow was qualitative evaluated in rapid, slow, or low flow. NIRS uses mucosal oxygen saturation and hemoglobin concentration as perfusion parameters. With LSCI, a decrease of perfusion units is observed toward the gastric fundus intraoperatively. The perfusion units (LDF, LSCI), although arbitrary and not absolute values, and low flow or length of demarcation to the anastomosis (FI) both seem predictive values for necrosis intraoperatively. SDF and OCT are able to measure microvascular flow, intraoperative prediction of necrosis is not yet described.Optical techniques aim to improve perfusion monitoring by real-time, high-resolution, and high-contrast measurements and could therefore be valuable in intraoperative perfusion mapping. LDF and LSCI use perfusion units, and are therefore subjective in interpretation. FI visualizes influx directly, but needs a quantitative parameter for interpretation during surgery.

Platelet function is disturbed by the angiogenesis inhibitors sunitinib and sorafenib, but unaffected by bevacizumab

IntroductionAt the clinical introduction of antiangiogenic agents as anticancer agents, no major toxicities were expected as merely just endothelial cells (ECs) in tumors would be affected. However, several (serious) toxicities became apparent, of which underlying mechanisms are largely unknown. We investigated to what extent sunitinib (multitargeted antiangiogenic tyrosine kinase inhibitor (TKI)), sorafenib (TKI) and bevacizumab [specific antibody against vascular endothelial growth factor (VEGF)] may impair platelet function, which might explain treatment-related bleedings.Materials and methodsIn vitro, the influence of sunitinib, sorafenib, and bevacizumab on platelet aggregation, P-selectin expression and fibrinogen binding, platelet–EC interaction, and tyrosine phosphorylation of c-Src was studied by optical aggregation, flow cytometry, real-time perfusion, and western blotting. Ex vivo, platelet aggregation was analyzed in 25 patients upon sunitinib or bevacizumab treatment. Concentrations of sunitinib, VEGF, and platelet and EC activation markers were measured by LC–MS/MS and ELISA.ResultsIn vitro, sunitinib and sorafenib significantly inhibited platelet aggregation (20 μM sunitinib: 71.3%, p < 0.001; 25 μM sorafenib: 55.8%, p = 0.042). Sorafenib and sunitinib significantly inhibited P-selectin expression on platelets. Exposure to both TKIs resulted in a reduced tyrosine phosphorylation of c-Src. Ex vivo, within 24 h sunitinib impaired platelet aggregation (83.0%, p = 0.001, N = 8). Plasma concentrations of sunitinib, VEGF, and platelet/EC activation markers were not correlated with disturbed aggregation. In contrast, bevacizumab only significantly impaired platelet aggregation in vitro at high concentrations, but not ex vivo.ConclusionSunitinib significantly inhibits platelet aggregation in patients already after 24 h of first administration, whereas bevacizumab had no effect on aggregation. These findings may explain the clinically observed bleedings during treatment with antiangiogenic TKIs.

Magnetic Particle Imaging for Real-Time Perfusion Imaging in Acute Stroke.

The fast and accurate assessment of cerebral perfusion is fundamental for the diagnosis and successful treatment of stroke patients. Magnetic particle imaging (MPI) is a new radiation-free tomographic imaging method with a superior temporal resolution, compared to other conventional imaging methods. In addition, MPI scanners can be built as prehospital mobile devices, which require less complex infrastructure than computed tomography (CT) and magnetic resonance imaging (MRI). With these advantages, MPI could accelerate the stroke diagnosis and treatment, thereby improving outcomes. Our objective was to investigate the capabilities of MPI to detect perfusion deficits in a murine model of ischemic stroke. Cerebral ischemia was induced by inserting of a microfilament in the internal carotid artery in C57BL/6 mice, thereby blocking the blood flow into the medial cerebral artery. After the injection of a contrast agent (superparamagnetic iron oxide nanoparticles) specifically tailored for MPI, cerebral perfusion and vascular anatomy were assessed by the MPI scanner within seconds. To validate and compare our MPI data, we performed perfusion imaging with a small animal MRI scanner. MPI detected the perfusion deficits in the ischemic brain, which were comparable to those with MRI but in real-time. For the first time, we showed that MPI could be used as a diagnostic tool for relevant diseases in vivo, such as an ischemic stroke. Due to its shorter image acquisition times and increased temporal resolution compared to that of MRI or CT, we expect that MPI offers the potential to improve stroke imaging and treatment.

Clinical Value of Contrast-Enhanced Harmonic Endoscopic Ultrasonography in the Differential Diagnosis of Pancreatic and Gallbladder Masses.

Background/AimsRecent studies have revealed that contrast-enhanced harmonic endoscopic ultrasonography (CEH-EUS) is beneficial in the differential diagnosis of malignant neoplasms of the pancreas and gallbladder from benign masses, in terms of the evaluation of microvasculature and real-time perfusion. In this study, we aimed to prove the clinical value of CEH-EUS in the differential diagnosis of pancreatic and gallbladder masses by direct comparison with that of conventional EUS. MethodsWe reviewed the sonographic images and medical information of 471 patients who underwent conventional EUS and CEH-EUS for the diagnosis of pancreatic and gallbladder masses at a single medical center (Severance Hospital, Seoul, Korea) between March 2010 and March 2016. ResultsThe enhancement pattern of CEH-EUS of the pancreatic solid masses showed higher sensitivity and specificity in differentiating pancreatic adenocarcinoma and neuroendocrine tumors (82.0% and 87.9% for pancreatic adenocarcinoma and 81.1% and 90.9% for neuroendocrine tumors, respectively), and the area under the receiver operating characteristic curves was higher than that of conventional EUS. The enhancement texture of CEH-EUS of the gallbladder masses showed a higher sensitivity in differentiating malignant masses than that of conventional EUS; however, the difference between the areas under the receiver operating characteristic curves was not statistically significant. ConclusionsCEH-EUS can complement conventional EUS in the diagnosis of pancreatic and gallbladder masses, in terms of the limitations of the latter.

Characterizing tissue perfusion after lower extremity intervention using two-dimensional color-coded digital subtraction angiography

ObjectiveDigital subtraction angiography (DSA) of the peripheral arterial vasculature provides lumenographic information but only a qualitative assessment of blood flow. The ability to quantify adequate tissue perfusion of the lower extremities would enable real-time perfusion assessment during DSA of patients with peripheral arterial disease (PAD). In this study, we used a novel real-time imaging software to delineate tissue perfusion parameters in the foot in PAD patients. MethodsBetween March 2015 and June 2016, patients (N = 31) underwent lower extremity angiography using a two-dimensional perfusion (2DP) imaging protocol (Philips Healthcare, Andover, Mass). Of the 31 enrolled patients, 16 patients received preintervention and postintervention DSA images (18 angiograms), while contrast agent injection settings and the position of the foot, catheter, and C-arm were kept constant. The region of interest for perfusion measurements was taken at the level of the medial malleolus. Perfusion parameters included arrival time (AT) of contrast material, wash-in rate (WIR), time to peak (TTP) contrast intensity, and area under the curve (AUC). ResultsPatients (mean age, 67 years; male, 61%) undergoing 2DP had limbs classified as Rutherford class 3 (n = 9 limbs), class 4 (n = 11), and class 5 (n = 14) ischemia with a mean ankle-brachial index of 0.63. For the whole cohort, median (interquartile range) AT measured 5.20 (3.10-7.25) seconds; WIR, 61.95 (43.53-86.43) signal intensity (SI)/s; TTP, 3.80 (2.88-4.50) seconds; peak intensity, 725.00 (613.75-1138.00) SI; and AUC, 12,084.00 (6742.80-17,059.70) SI*s. A subset of patients had 2DP performed before and after intervention (n = 18 cases). A detectable improvement in SI and two-dimensional flow parameters was seen after intervention. Average AT of contrast material to the region of interest shortened after intervention with percentage decrease of 30.1% ± 49.1%, corresponding decrease in TTP of 17.6% ± 24.7%, increase in WIR of 68.8% ± 94.2% and in AUC of 10.5% ± 37.6%, decrease in mean transit time of 18.7% ± 28.1%, and increase in peak of 34.4% ± 42.2%. ConclusionsThe 2DP imaging allows measurement of blood flow in real time as an adjunct to DSA. The AT may be the most sensitive marker of perfusion change in the lower extremity. Quantitative thresholds based on 2DP hold promise for immediate treatment effectiveness assessment in patients with PAD.

Platelets and neutrophil extracellular traps collaborate to promote intravascular coagulation during sepsis in mice

AbstractNeutrophil extracellular traps (NETs; webs of DNA coated in antimicrobial proteins) are released into the vasculature during sepsis where they contribute to host defense, but also cause tissue damage and organ dysfunction. Various components of NETs have also been implicated as activators of coagulation. Using multicolor confocal intravital microscopy in mouse models of sepsis, we observed profound platelet aggregation, thrombin activation, and fibrin clot formation within (and downstream of) NETs in vivo. NETs were critical for the development of sepsis-induced intravascular coagulation regardless of the inciting bacterial stimulus (gram-negative, gram-positive, or bacterial products). Removal of NETs via DNase infusion, or in peptidylarginine deiminase-4–deficient mice (which have impaired NET production), resulted in significantly lower quantities of intravascular thrombin activity, reduced platelet aggregation, and improved microvascular perfusion. NET-induced intravascular coagulation was dependent on a collaborative interaction between histone H4 in NETs, platelets, and the release of inorganic polyphosphate. Real-time perfusion imaging revealed markedly improved microvascular perfusion in response to the blockade of NET-induced coagulation, which correlated with reduced markers of systemic intravascular coagulation and end-organ damage in septic mice. Together, these data demonstrate, for the first time in an in vivo model of infection, a dynamic NET–platelet–thrombin axis that promotes intravascular coagulation and microvascular dysfunction in sepsis.

Rest-Stress Limb Perfusion Imaging in Humans with Contrast Ultrasound Using Intermediate-Power Imaging and Microbubbles Resistant to Inertial Cavitation

Contrast-enhanced ultrasound (CEU) limb perfusion imaging is a promising approach for evaluating peripheral artery disease (PAD). However, low signal enhancement in skeletal muscle has necessitated high-power intermittent imaging algorithms, which are not clinically feasible. We hypothesized that CEU using a combination of intermediate power and a contrast agent resistant to inertial cavitation would allow real-time limb stress perfusion imaging. In normal volunteers, CEU of the calf skeletal muscle was performed on separate days with Sonazoid,Optison, or Definity. Progressive reduction in the ultrasound pulsing interval was used to assess the balance between signal enhancement and agent destruction at escalating mechanical indices (MI, 0.1-0.4). Real-time perfusion imaging at MI 0.1-0.4 using postdestructive replenishment kinetics was performedat rest and during 25W plantar flexion contractile exercise. For Optison, limb perfusion imaging was unreliable at rest due to very low signal enhancement generated at all MIs and was possible during exercise-induced hyperemia only at MI 0.1 due to agent destruction at higher MIs. For Definity, signal intensity progressively increased with MI but was offset by microbubble destruction, which resulted in modest signal enhancement during CEU perfusion imaging and distortion of replenishment curves at MI≥0.2. For Sonazoid, there strong signal enhancement at MI≥0.2, with little destruction detected only at MI 0.4. Accordingly, high signal intensity and nondistorted perfusion imaging was possible at MI 0.2-0.3 and detected an 8.0- ± 5.7-fold flow reserve. Rest-stress limb perfusion imaging in humans with real-time CEU, which requires only seconds to perform, is possible using microbubbles with viscoelastic properties that produce strong nonlinear signal generation without destruction at intermediate acoustic pressures.

A practical approach to remote ischemic preconditioning and ischemic preconditioning against myocardial ischemia/reperfusion injury.

Although urgently needed in clinical practice, a cardioprotective therapeutic approach against myocardial ischemia/reperfusion injury remains to be established. Remote ischemic preconditioning (rIPC) and ischemic preconditioning (IPC) represent promising tools comprising three entities: the generation of a protective signal, the transfer of the signal to the target organ, and the response to the transferred signal resulting in cardioprotection. However, in light of recent scientific advances, many controversies arise regarding the efficacy of the underlying signaling. We here show methods for the generation of the signaling cascade by rIPC as well as IPC in a mouse model for in vivo myocardial ischemia/reperfusion injury using highly reproducible approaches. This is accomplished by taking advantage of easily applicable preconditioning strategies compatible with the clinical setting. We describe methods for using laser Doppler perfusion imaging to monitor the cessation and recovery of perfusion in real time. The effects of preconditioning on cardiac function can also be assessed using ultrasound or magnetic resonance imaging approaches. On a cellular level, we confirm how tissue injury can be monitored using histological assessment of infarct size in conjunction with immunohistochemistry to assess both aspects in a single specimen. Finally, we outline, how the rIPC-associated signaling can be transferred to the target cell via conservation of the signal in the humoral (blood) compartment. This compilation of experimental protocols including a conditioning regimen comparable to the clinical setting should proof useful to both beginners and experts in the field of myocardial infarction, supplying information for the detailed procedures as well as troubleshooting guides.

Neutrophil extracellular traps (NETs) promote disseminated intravascular coagulation in sepsis.

Abstract Neutrophil extracellular traps (NETs; webs of DNA coated in anti-microbial proteins) are released into the vasculature during sepsis and contribute to organ damage. Various components of NETs have been shown to modulate the coagulation cascade in vitro. We hypothesized that NETs released into the vasculature during sepsis activate intravascular coagulation, leading to microvascular hypoperfusion and end-organ damage. Multi-color confocal intravital microscopy was used in mouse models of sepsis (endotoxemia and E. coli peritonitis) to visualize and quantify neutrophil and platelet trafficking, NETs production, real-time perfusion analysis, and intravascular thrombin activity (using novel in vivo zymography). In vivo imaging of the liver microcirculation in septic mice revealed spatial co-localization between NETs and intravascular coagulation (thrombin activity, fibrin deposition, and platelet aggregation). Inhibition of NETs using i.v. DNase infusion (to digest NETs), or PAD4-deficient mice (that have impaired NETs production) resulted in significantly lower quantities of intravascular thrombin activity, and improved microvascular perfusion. In a model of Gram-negative sepsis (E. coli peritonitis), PAD4-deficient mice had reduced markers of disseminated intravascular coagulation (intravascular thrombin, PAI-1), and end-organ damage (serum lactate, ALT) compared to wild-type controls. Together, these data demonstrate that NETs activate coagulation in vivo, and promote disseminated intravascular coagulation in sepsis. Inhibition of NETs in septic animals reduces intravascular coagulation, improves microvascular perfusion, and attenuates end-organ damage.

Abstract TMP56: Mapping the Dynamics of Brain Perfusion During and Following Transient Middle Cerebral Artery Occlusion (tMCAo) in the Rat Using Functional Ultrasound (fUS)

Introduction: Following MCAo, tissue outcome varies depending on depth and duration of hypoperfusion and efficiency of reperfusion. However, the precise time-course of these events in relation to tissue and behavioral outcome remains unsettled due to lack of a wide field-of-view quantitative imaging technique able to map perfusion in the rodent brain at high spatiotemporal resolution. Here we used fUS, a novel approach to map cerebral blood volume (CBV) without contrast agent. Hypothesis: fUS will allow quantitative, near real-time mapping of CVB during and after tMCAo. Methods: 45min filament tMCAo was induced in adult SD rats; sham rats were also used. fUS was used to map the penetrating arterioles and venules of the ipsi- and contra-lateral motor (M1-2) and somatosensory (S1) cortex in coronal sections across the MCA territory at 80μm resolution. Three-min coronal scans were taken at different levels before, during and immediately after MCAo, and at 3 and 6 days thanks to a thinned-skull preparation. CBV was expressed relative to mirror ROI. In addition, a 1-hr movie (one frame/5s) was taken starting a few mins after reperfusion. Serial Neuroscore and 2 sensorimotor tasks were given over 3w post-MCAo, and then NeuN, IBa1 and GFAP immunofluorescence (IF) at post-mortem. Results: fUS showed a ∼80% CBV reduction in S1 during occlusion (p&lt;0.001; n=7), with partial (∼60%, p&lt;0.001) return of CBV on reperfusion, followed by a full return at days 3 and 6. As expected for this model, similar but less conspicuous CBV changes prevailed in M1-2. Continuous reperfusion was depicted in 5/7 rats (slope range: 8-25%/hr relative to prior CBV), but not in 2 rats. There were no significant changes in behavior relative to the sham group (n=4), and IF showed no infarction but marked selective neuronal loss (SNL) in the striatum in 5/7 rats and milder cortical SNL in 4/7 rats. Conclusions: fUS efficiently mapped the acute changes in CBV during occlusion and following reperfusion with high spatio-temporal resolution, allowing the charting of fine tissue reperfusion dynamics in the individual rat. fUS is ideal to longitudinally map real-time cerebral perfusion in experimental stroke from the hyper-acute through to the chronic stage.

Commentary on: safety of vertical augmentation-mastopexy: prospective evaluation of breast perfusion using laser fluorescence imaging.

As reconstructive or aesthetic surgeons, so much of what we do relies on the ability to maintain appropriate soft tissue perfusion. The consequences of poor tissue perfusion, whether performing a free fibula reconstruction or a facelift, can be devastating. This is why new technologies, such as the SPY Elite Intraoperative perfusion Assessment System (LifeCell Corporation, Branchburg, NJ) are so useful, because they provide us with objective real-time perfusion information. Intraoperative angiography was used in this study to shed some light on an area of much debate: the impact of implant placement to nipple perfusion during augmentation-mastopexy. The major concern that the author wished to address was that of potentially causing nipple ischemia when repositioning the nipple-areolar complex (NAC) and then placing an implant. This is an important concern, since even …

Visualization of Regional Cerebral Blood Flow Dynamics during Cortical Venous Occlusion using Laser Speckle Contrast Imaging in a Rat Model

Cerebral venous ischemia (CVI) is a rare but potentially significant complication of neurosurgical procedures. However, it is still unclear how cerebral venous occlusion (VO) affects regional cerebral blood flow (rCBF) dynamics. To elucidate its pathophysiology in detail, we examined the real-time perfusion dynamics during adjacent vein occlusions using laser speckle contrast imaging (LSCI) in a rat 2-vein occlusion model. Two cortical veins were occluded photochemically using rose Bengal dye in 6 male Wistar rats; rCBF was measured in real time with an LSCI before and after VO. Regions of interest were defined between the 2 veins (A) and on the opposite side of the first occluded vein (B) on semi-quantitative pseudocolor images for off-line analysis. Histopathologic evaluation was performed 3 days after the procedure to assess the extent of infarction. LSCI revealed a stepwise reduction in CBF, with a sudden decrease just after the first vein occlusion (~20%) and a further decrease after the second (~30%). Significant differences were observed between rCBF dynamics within regions of interest A and B (P = .0004). All rats exhibited infarcts in the superficial cerebral cortex histopathologically. This is the first report of LSCI specifically applied to the study of CVI. The extensive real-time measurement with high temporal and spatial resolution revealed the stepwise reduction in rCBF during sequential VO and the ensuing infarcts.

Robot-Assisted Minimally Invasive Ivor Lewis Esophagectomy With Real-Time Perfusion Assessment

Surgical resection is viewed as the most effective way to ensure both locoregional control and long-term survival in esophageal cancer. Although minimally invasive esophagectomy has been widely accepted as an alternative to open surgery, the role of robotic assistance has yet to be elucidated. We report our institutional experience with robotic-assisted Ivor Lewis esophagectomy using real-time perfusion assessment and demonstrate this as a safe and technically feasible alternative to traditional open Ivor Lewis esophagectomy. A retrospective chart review of all patients undergoing robotic-assisted Ivor Lewis esophagectomy at a single institution from 2011 to 2014 was performed. Operative and postoperative outcomes were recorded. Fifty-four patients underwent robotic-assisted Ivor Lewis esophagectomy during the study period. Indication for surgery was cancer in 49 patients, 38 of whom underwent neoadjuvant chemoradiation therapy. The average operative time was 6 hours 2 minutes, and the average blood loss was 74 mL. There was 1 postoperative mortality (1.9%). Three (5.5%) patients experienced an anastomotic leak. The average number of lymph nodes harvested in cancer patients was 16.2 (range, 3 to 35). The average length of stay was 12.9 days. Our study demonstrates that robotic-assisted Ivor Lewis esophagectomy using real-time perfusion assessment is a safe and technically feasible alternative to traditional open Ivor Lewis esophagectomy. It allows for R0 resection with adequate lymph node harvesting and a short hospital stay.