Ultrasonographic assessment of pulmonary and Central venous congestion in experimental heart failure.

Pulmonary and systemic congestion as a consequence of heart failure are clinically recognized as alarm signals for clinical outcome and mortality. Although signs and symptoms of congestion are well detectable in patients, monitoring of congestion in small animals with heart failure lacks adequate noninvasive methodology yet. Here, we developed a novel ultrasonography-based scoring system to assess pulmonary and systemic congestion in experimental heart failure, by using lung ultrasound (LUS) and imaging of the inferior vena cava (Cava), termed CavaLUS. CavaLUS was established and tested in a rat model of supracoronary aortic banding and a mouse model of myocardial infarction, providing high sensitivity and specificity while correlating to numerous parameters of cardiac performance and disease severity. CavaLUS, therefore, provides a novel comprehensive tool for experimental heart failure in small animals to noninvasively assess congestion.NEW & NOTEWORTHY As thorough, noninvasive assessment of congestion is not available in small animals, we developed and validated an ultrasonography-based research tool to evaluate pulmonary and central venous congestion in experimental heart failure models.

Reliability and reproducibility of the venous excess ultrasound (VExUS) score, a multi-site prospective study: validating a novel ultrasound technique for comprehensive assessment of venous congestion.

Though the novel venous excess ultrasound (VExUS) score is increasingly used as a noninvasive means of venous congestion measurement, the inter-rater reliability (IRR), inter-user reproducibility (IUR), and utility of concurrent ECG have not been evaluated. We conducted a multicenter study of the IRR, IUR, and utility of ECG for VExUS interpretation between four attending physicians of diverse specialties, reporting the Kappa statistic (KS) and Intraclass Correlation Coefficient (ICC) for IRR and IUR for scans with and without ECG. Eighty-four paired VExUS exams from 42 patients, 60 of which had a concurrent ECG tracing, were interpreted. They showed substantial IRR, with a KS of 0.71 and ICC of 0.83 for the overall VExUS grade (p < 0.001), and IUR, with a KS 0.63 and ICC of 0.8. There was greater agreement among images with an ECG tracing. These results suggest that ECG-augmented VExUS may be a reliable and reproducible measure interpretable by clinicians with diverse backgrounds.

Venous congestion in septic shock quantified with point-of-care ultrasound: a pilot prospective multicentre cohort study.

PURPOSE: Venous congestion is a pathophysiologic state that can result in organ dysfunction, particularly acute kidney injury (AKI). We sought to evaluate the feasibility of performing a definitive observational study to determine the impact of venous congestion quantified using point-of-care ultrasound (POCUS) in patients with septic shock. METHODS: We conducted a prospective observational feasibility study at two intensive care units (ICUs). We recruited adult patients with septic shock within 12 hr of ICU admission. Using the validated Venous Excess Ultrasound Score (VEXUS), we quantified venous congestion on day 1 and day 3 of ICU admission. The primary feasibility outcome was successful completion rate of the two VEXUS scores. We performed a survival analysis to quantify the hazard of renal replacement therapy (RRT). RESULTS: We enrolled 75 patients from January 2022 to January 2023. The success rate of completion for VEXUS scans was 94.5% (95% confidence interval [CI], 89.5 to 97.6). Severe venous congestion was present in 19% (14/75) of patients on ICU admission day 1 and in 16% (10/61) of patients on day 3. Venous congestion on ICU admission may be associated with a higher risk of requiring RRT (unadjusted hazard ratio, 3.35; 95% CI, 0.94 to 11.88; P = 0.06). CONCLUSIONS: It is feasible to conduct a definitive observational study exploring the association between venous congestion quantified with POCUS and clinical outcomes in patients with septic shock. We hypothesize that venous congestion may be associated with an increased hazard of receiving RRT.

RéSUMé: OBJECTIF: La congestion veineuse est un état physiopathologique qui peut entraîner un dysfonctionnement des organes, en particulier une insuffisance rénale aiguë (IRA). Nous avons cherché à évaluer la faisabilité de la réalisation d'une étude observationnelle définitive pour déterminer l'impact de la congestion veineuse quantifiée à l'aide de l'échographie ciblée (POCUS) chez des patient·es en choc septique. MéTHODE: Nous avons réalisé une étude de faisabilité observationnelle prospective dans deux unités de soins intensifs (USI). Nous avons recruté des patient·es adultes souffrant d'un choc septique dans les 12 heures suivant leur admission aux soins intensifs. À l'aide du score VEXUS (score d'échographie de l'excès veineux) validé, nous avons quantifié la congestion veineuse au jour 1 et au jour 3 de leur admission aux soins intensifs. Le principal critère de faisabilité était le taux de réussite des deux scores VEXUS. Nous avons réalisé une analyse de survie pour quantifier le risque de thérapie de substitution rénale (TSR). RéSULTATS: Nous avons recruté 75 patient·es de janvier 2022 à janvier 2023. Le taux de réussite des scores VEXUS était de 94,5 % (intervalle de confiance [IC] à 95 %, 89,5 à 97,6). Une congestion veineuse sévère était présente chez 19 % (14/75) des patient·es au jour 1 d'admission aux soins intensifs et chez 16 % (10/61) des patient·es au jour 3. La congestion veineuse lors de l'admission aux soins intensifs peut être associée à un risque plus élevé de nécessiter une TSR (rapport de risque non ajusté, 3,35; IC 95 %, 0,94 à 11,88; P = 0,06). CONCLUSION: Il est possible de mener une étude observationnelle définitive explorant l'association entre la congestion veineuse quantifiée par POCUS et les devenirs cliniques chez les patient·es en choc septique. Nous émettons l'hypothèse que la congestion veineuse peut être associée à un risque accru de recevoir une thérapie de substitution rénale.

Pulsatile Femoral Vein Doppler Pattern is a Parameter of Venous Congestion in ICU Patients.

OBJECTIVES: The aim of this study was to evaluate if the presence of a pulsatile femoral vein pattern is an indicator of venous congestion in the intensive care unit (ICU). DESIGN: Retrospective observational study. SETTING: Three medico-surgical university-affiliated ICUs. PARTICIPANTS: Adult patients who had an ultrasound evaluation at several time points during their ICU stay: at baseline (within 24 hours of admission to ICU), daily during their ICU stay, and within 24 hours before ICU discharge. INTERVENTIONS: At each time point, the hemodynamic, respiratory, and cardiac ultrasound parameters were recorded. The common femoral vein was studied with pulsed-wave Doppler at the level of the femoral trigonum, with high frequency (5-13 MHz) linear array vascular probe and venous vascular mode, in supine patients. MEASUREMENTS AND MAIN RESULTS: One hundred eight patients who underwent 400 ultrasound evaluations (3.7 ± 1 ultrasound evaluations per patient) during their ICU stay were included. Seventy-nine of 108 patients (73%) had a pulsatile femoral vein pattern at least at 1 time point. The multivariable mixed effects logistic regression model demonstrated an association among pulsatile femoral vein pattern, body mass index (OR: 0.91[95% CI 0.85-0.96], p = 0.002), inferior vena cava mean diameter (OR: 2.35 [95% CI 1.18-4.66], p = 0.014), portal vein pulsatility (OR: 2.3 [95% CI 1.2-4.4], p = 0.012), and congestive renal vein flow pattern (OR: 4.02 [95% CI 2.01-8.03], p < 0.001). The results were confirmed by principal component analysis. CONCLUSION: In the ICU, a pulsatile femoral vein pattern is associated with parameters of venous congestion, independently of the patient's volume status, and ventilatory treatment. These results suggest the femoral vein Doppler pulsatility as a parameter of congestion in ICU patients.

Carotid-cavernous fistula: A potential treatable cause of bilateral abducens palsy and conjunctival hyperemia.

OBJECTIVE: Carotid cavernous fistulas (CCFs) represent uncommon and anomalous communications between the carotid artery and the cavernous sinus. MATERIALS AND METHODS: Case report RESULTS: We present the clinical details and successful management of a previously healthy 44-year-old patient who presented with one-month worsening headache, bilateral abducens palsy and conjunctival injection. Imaging modalities including magnetic resonance imaging (MRI) with contrast and digital subtraction angiography (DSA) facilitated the diagnosis of CCF. The patient underwent endovascular coiling of the CCF, leading to neurological recovery and symptom remission. CONCLUSION: This case highlights the importance of promptly CCF diagnosis in patients with multiple cranial nerve palsies and conjunctival hyperemia. Moreover, it emphasizes the efficacy of endovascular coiling in achieving symptom remission.

Pulmonary blood volume assessment from a standard cardiac rubidium-82 imaging protocol: impact of adenosine-induced hyperemia.

BACKGROUND: This study aimed to assess the feasibility of estimating the pulmonary blood volume noninvasively using standard Rubidium-82 myocardial perfusion imaging (MPI) and characterize the changes during adenosine-induced hyperemia. METHODS: This study comprised 33 healthy volunteers (15 female, median age = 23 years), of which 25 underwent serial rest/adenosine stress Rubidium-82 MPI sessions. Mean bolus transit times (MBTT) were obtained by calculating the time delay from the Rubidium-82 bolus arrival in the pulmonary trunk to the arrival in the left myocardial atrium. Using the MBTT, in combination with stroke volume (SV) and heart rate (HR), we estimated pulmonary blood volume (PBV = (SV × HR) × MBTT). We report the empirically measured MBTT, HR, SV, and PBV, all stratified by sex [male (M) vs female (F)] as mean (SD). In addition, we report grouped repeatability measures using the within-subject repeatability coefficient. RESULTS: Mean bolus transit times was shortened during adenosine stressing with sex-specific differences [(seconds); Rest: Female (F) = 12.4 (1.5), Male (M) = 14.8 (2.8); stress: F = 8.8 (1.7), M = 11.2 (3.0), all P ≤ 0.01]. HR and SV increased during stress MPI, with a concomitant increase in the PBV [mL]; Rest: F = 544 (98), M = 926 (105); Stress: F = 914 (182), M = 1458 (338), all P < 0.001. The following test-retest repeatability measures were observed for MBTT (Rest = 17.2%, Stress = 17.9%), HR (Rest = 9.1%, Stress = 7.5%), SV (Rest = 8.9%, Stress = 5.6%), and for PBV measures (Rest = 20.7%, Stress = 19.5%) CONCLUSION: Pulmonary blood volume can be extracted by cardiac rubidium-82 MPI with excellent test-retest reliability, both at rest and during adenosine-induced hyperemia.

Arterial occlusion duration affects the cuff-induced hyperemic response in skeletal muscle BOLD perfusion imaging as shown in young healthy subjects.

OBJECTIVE: Dynamic BOLD MRI with cuff compression, inducing ischemia and post-occlusive hyperemia in skeletal muscle, has been pointed out as a potential diagnostic tool to assess peripheral limb perfusion. The objective was to explore the robustness of this technique and its sensitivity to the occlusion duration. MATERIALS AND METHODS: BOLD images were acquired at 3 T in 14 healthy volunteers. [Formula: see text]-imaging with 5- and 1.5-min occlusions were acquired and several semi-quantitative BOLD parameters were derived from ROI-based [Formula: see text]-time curves. Differences in parameters from the two different occlusion durations were evaluated in the gastrocnemius and soleus muscles using non-parametrical tests. Intra- and inter-scan repeatability were evaluated with coefficient of variation. RESULTS: Longer occlusion duration resulted in an increased hyperemic signal effect yielding significantly different values (p < 0.05) in gastrocnemius for all parameters describing the hyperemic response, and in soleus for two of these parameters. Specifically, 5-min occlusion yielded steeper hyperemic upslope in gastrocnemius (41.0%; p < 0.05) and soleus (59.7%; p = 0.03), shorter time to half peak in gastrocnemius (46.9%; p = 0.00008) and soleus (33.5%; p = 0.0003), and shorter time to peak in gastrocnemius (13.5%; p = 0.02). Coefficients of variation were lower than percentage differences that were found significant. DISCUSSION: Findings show that the occlusion duration indeed influences the hyperemic response and thus should play a part in future methodological developments.

Spectral analysis of laser speckle contrast imaging and infrared thermography to assess skin microvascular reactive hyperemia.

BACKGROUND: Post-occlusive reactive hyperemia (PORH) test with signal spectral analysis coupled provides potential indicators for the assessment of microvascular functions. OBJECTIVE: The objective of this study is to investigate the variations of skin blood flow and temperature spectra in the PORH test. Furthermore, to quantify the oscillation amplitude response to occlusion within different frequency ranges. MATERIALS AND METHODS: Ten healthy volunteers participated in the PORH test and their hand skin temperature and blood flow images were captured by infrared thermography (IRT) and laser speckle contrast imaging (LSCI) system, respectively. Extracted signals from selected areas were then transformed into the time-frequency space by continuous wavelet transform for cross-correlation analysis and oscillation amplitude response comparisons. RESULTS: The LSCI and IRT signals extracted from fingertips showed stronger hyperemia response and larger oscillation amplitude compared with other areas, and their spectral cross-correlations decreased with frequency. According to statistical analysis, their oscillation amplitudes in the PORH stage were obviously larger than the baseline stage within endothelial, neurogenic, and myogenic frequency ranges (p < 0.05), and their quantitative indicators of oscillation amplitude response had high linear correlations within endothelial and neurogenic frequency ranges. CONCLUSION: Comparisons of IRT and LSCI techniques in recording the reaction to the PORH test were made in both temporal and spectral domains. The larger oscillation amplitudes suggested enhanced endothelial, neurogenic, and myogenic activities in the PORH test. We hope this study is also significant for investigations of response to the PORH test by other non-invasive techniques.

Impact of supervised exercise on skeletal muscle blood flow and vascular function measured with MRI in patients with peripheral artery disease.

Supervised exercise is a common therapeutic intervention for patients with peripheral artery disease (PAD), however, the mechanism underlying the improvement in claudication symptomatology is not completely understood. The hypothesis that exercise improves microvascular blood flow is herein tested via temporally resolved magnetic resonance imaging (MRI) measurement of blood flow and oxygenation dynamics during reactive hyperemia in the leg with the lower ankle-brachial index. One hundred and forty-eight subjects with PAD were prospectively assigned to standard medical care or 3 mo of supervised exercise therapy. Before and after the intervention period, subjects performed a graded treadmill walking test, and MRI data were collected with Perfusion, Intravascular Venous Oxygen saturation, and T2* (PIVOT), a method that simultaneously quantifies microvascular perfusion, as well as relative oxygenation changes in skeletal muscle and venous oxygen saturation in a large draining vein. The 3-mo exercise intervention was associated with an improvement in peak walking time (64% greater in those randomized to the exercise group at follow-up, P < 0.001). Significant differences were not observed in the MRI measures between the subjects randomized to exercise therapy versus standard medical care based on an intention-to-treat analysis. However, the peak postischemia perfusion averaged across the leg between baseline and follow-up visits increased by 10% (P = 0.021) in participants that were adherent to the exercise protocol (completed >80% of prescribed exercise visits). In this cohort of adherent exercisers, there was no difference in the time to peak perfusion or oxygenation metrics, suggesting that there was no improvement in microvascular function nor changes in tissue metabolism in response to the 3-mo exercise intervention.NEW & NOTEWORTHY Supervised exercise interventions can improve symptomatology in patients with peripheral artery disease, but the underlying mechanism remains unclear. Here, MRI was used to evaluate perfusion, relative tissue oxygenation, and venous oxygen saturation in response to cuff-induced ischemia. Reactive hyperemia responses were measured before and after 3 mo of randomized supervised exercise therapy or standard medical care. Those participants who were adherent to the exercise regimen had a significant improvement in peak perfusion.

Myocardial blood flow is the dominant factor influencing cardiac magnetic resonance adenosine stress T2.

Stress imaging identifies ischemic myocardium by comparing hemodynamics during rest and hyperemic stress. Hyperemia affects multiple hemodynamic parameters in myocardium, including myocardial blood flow (MBF), myocardial blood volume (MBV), and venous blood oxygen levels (PvO2 ). Cardiac T2 is sensitive to these changes and therefore is a promising non-contrast option for stress imaging; however, the impact of individual hemodynamic factors on T2 is poorly understood, making the connection from altered T2 to changes within the tissue difficult. To better understand this interplay, we performed T2 mapping and measured various hemodynamic factors independently in healthy pigs at multiple levels of hyperemic stress, induced by different doses of adenosine (0.14-0.56 mg/kg/min). T1 mapping quantified changes in MBV. MBF was assessed with microspheres, and oxygen consumption was determined by the rate pressure product (RPP). Simulations were also run to better characterize individual contributions to T2. Myocardial T2, MBF, oxygen consumption, and MBV all changed to varying extents between each level of adenosine stress (T2 = 37.6-41.8 ms; MBF = 0.48-1.32 mL/min/g; RPP = 6507-4001 bmp*mmHg; maximum percent change in MBV = 1.31%). Multivariable analyses revealed MBF as the dominant influence on T2 during hyperemia (significant ß-values >7). Myocardial oxygen consumption had almost no effect on T2 (ß-values <0.002); since PvO2 is influenced by both oxygen consumption and MBF, PvO2 changes detected by T2 during adenosine stress can be attributed to MBF. Simulations varying PvO2 and MBV confirmed that PvO2 had the strongest influence on T2, but MBV became important at high PvO2 . Together, these data suggest a model where, during adenosine stress, myocardial T2 responds predominantly to changes in MBF, but at high hyperemia MBV is also influential. Thus, changes in adenosine stress T2 can now be interpreted in terms of the physiological changes that led to it, enabling T2 mapping to become a viable non-contrast option to detect ischemic myocardial tissue.

Regadenoson versus dipyridamole: Evaluation of stress myocardial blood flow response on a CZT-SPECT camera.

BACKGROUND: Regadenoson is a selective adenosine receptor agonist. It is currently unclear if the level of hyperemia differs between stress agents. We compared Myocardial Blood Flow (MBF) and Myocardial Flow Reserve (MFR) response on CZT-SPECT Myocardial Perfusion Imaging (MPI) to evaluate if dipyridamole and regadenoson could induce the same level of hyperemia. METHODS: 228 patients with dynamic CZT-SPECT MPI were retrospectively analyzed (66 patients stressed with regadenoson and 162 with dipyridamole) in terms of MBF and MFR. To rule out confounding factors, two groups of 41 patients were matched for clinical characteristics in a sub-analysis, excluding high cardiovascular risk patients. RESULTS: Overall stress MBF was higher in regadenoson patients (1.71 ± 0.73 vs. 1.44 ± 0.55 mL·min-1·g-1 for regadenoson and dipyridamole, respectively, p < .05). However, when confounding factors were ruled out, stress MBF (1.57 ± 0.56 vs. 1.61 ± 0.62 mL·min-1·g-1 for dipyridamole and regadenoson, respectively, p = .88) and MFR (2.62 ± 0.77 vs. 2.46 ± 0.76 for dipyridamole and regadenoson, respectively, p = .40) were not different between regadenoson and dipyridamole. CONCLUSIONS: Our results suggest that dipyridamole and regadenoson induce equivalent hyperemia in dynamic SPECT with similar stress MBF and MFR in comparable patients.

MR elastography-based staging of liver fibrosis in Fontan procedure associated liver disease is confounded by effects of venous congestion.

AIM: To compare targeted and global liver stiffness measured by magnetic resonance elastography (MRE) with liver biopsy in patients who have undergone the Fontan procedure, and to assess the relationship between liver stiffness and fibrosis stage. MATERIALS AND METHODS: Targeted and global liver stiffness was compared with a quantification of liver fibrosis measured by percentage of Sirius Red (%SR) staining of biopsy samples. MRE values were compared with three other biopsy-scoring methods: Ishak, Scheuer/Ludwig-Batts/Metavir, and congestive hepatic fibrosis score (CHFS). Additionally, in patients who had two or more MRE studies, global liver stiffness was compared for longitudinal assessment. RESULTS: Thirty-four patients were included in the study, with a mean age of 16.2 years. There was no statistically significant correlation between MRE-derived liver stiffness and Ishak score, Metavir score, %SR staining, and CHFS score. Twenty patients had multiple MRE studies, with a mean age of 16.5 years, and these showed a statistically significant increase in mean liver stiffness from 3.72 to 4.68 (26% increase) within an average period of 24 months. CONCLUSIONS: The lack of correlation of liver stiffness with fibrosis stage observed in this study indicates that the effects of venous congestion in Fontan patients can confound the use of liver stiffness as a biomarker for fibrosis as assessed by percentage of SR staining, Ishak score, Metavir score, and CHFS score. These results provide motivation for further development of magnetic resonance imaging-based biomarkers to increase the specificity in the assessment of Fontan-associated liver disease. A steady increase in liver stiffness observed in these patients may be useful for longitudinal follow-up of liver health.

Correlation between endoscopy and intestinal ultrasound for the evaluation of postoperative recurrence of Crohn's disease. / Correlación entre la endoscopia y la ecografía intestinal para la evaluación de la recurrencia posquirúrgica de la enfermedad de Crohn.

OBJECTIVE: Intestinal ultrasound is considered to be a valid alternative for the evaluation of post-operative recurrence (POR) of Crohn's disease. The aim of this study is to assess the correlation between ultrasound and endoscopic findings. METHODS: Patients with Crohn's disease were retrospectively recruited who had undergone ileocecal resection, and for whom a colonoscopy and intestinal ultrasound had been performed for the detection of POR. Recurrence was assessed using the Rutgeerts score (RS). The ultrasound findings analysed were bowel wall thickness (BWT), parietal hyperaemia using power Doppler, loss of layer pattern and mesenteric fat hypertrophy. RESULTS: A total of 31 patients were included, of which 15 (48.4%) had no POR (RS<2b) and 16 (51.6%) had POR (RS≥2b). A statistically significant association was identified between BWT and the presence of endoscopic recurrence (a mean of 2.75mm vs. 5.68mm, P>0.001). There was also a statistically significant difference in hyperaemia between the 2groups (P=0.03). For wall thickness, an area under the ROC curve (AUC) of 92.9% was obtained, and with a cut-off point of 3.4mm, a sensitivity of 100% and specificity of 86.6%. When comparing with the most frequent biomarkers (fecal calprotectin and serum CRP), a higher AUC was obtained for wall thickness (72.3% and 72.3% vs. 92.9%). CONCLUSIONS: In our experience, ultrasound has high diagnostic efficacy in the detection of POR and can be considered a valid non-invasive alternative to endoscopy.

Vascular alterations among young adults with SARS-CoV-2.

While SARS-CoV-2 primarily affects the lungs, the virus may be inflicting detriments to the cardiovascular system, both directly through angiotensin-converting enzyme 2 receptor and initiating systemic inflammation. Persistent systemic inflammation may be provoking vascular dysfunction, an early indication of cardiovascular disease risk. To establish the potential effects of SARS-CoV-2 on the systemic vasculature in the arms and legs, we performed a cross-sectional analysis of young healthy adults (control: 5 M/15 F, 23.0 ± 1.3 y, 167 ± 9 cm, 63.0 ± 7.4 kg) and young adults who, 3-4 wk prior to testing, had tested positive for SARS-CoV-2 (SARS-CoV-2: 4 M/7 F, 20.2 ± 1.1 y, 172 ± 12 cm, 69.5 ± 12.4 kg) (means ± SD). Using Doppler ultrasound, brachial artery flow-mediated dilation (FMD) in the arm and single passive limb movement (sPLM) in the leg were assessed as markers of vascular function. Carotid-femoral pulse wave velocity (PWVcf) was asvsessed as a marker of arterial stiffness. FMD was lower in the SARS-CoV-2 group (2.71 ± 1.21%) compared with the control group (8.81 ± 2.96%) (P < 0.01) and when made relative to the shear stimulus (SARS-CoV-2: 0.04 ± 0.02 AU, control: 0.13 ± 0.06 AU, P < 0.01). The femoral artery blood flow response, as evidenced by the area under the curve, from the sPLM was lower in the SARS-CoV-2 group (-3 ± 91 mL) compared with the control group (118 ± 114 mL) (P < 0.01). PWVcf was higher in the SARS-CoV-2 group (5.83 ± 0.62 m/s) compared with the control group (5.17 ± 0.66 m/s) (P < 0.01). Significantly lower systemic vascular function and higher arterial stiffness are evident weeks after testing positive for SARS-CoV-2 among young adults compared with controls.NEW & NOTEWORTHY This study was the first to investigate the vascular implications of contracting SARS-CoV-2 among young, otherwise healthy adults. Using a cross-sectional design, this study assessed vascular function 3-4 wk after young adults tested positive for SARS-CoV-2. The main findings from this study were a strikingly lower vascular function and a higher arterial stiffness compared with healthy controls. Together, these results suggest rampant vascular effects seen weeks after contracting SARS-CoV-2 in young adults.

Visualizing and quantifying cutaneous microvascular reactivity in humans by use of optical coherence tomography: impaired dilator function in diabetes.

The pathophysiology and time course of impairment in cutaneous microcirculatory function and structure remain poorly understood in people with diabetes, partly due to the lack of investigational tools capable of directly imaging and quantifying the microvasculature in vivo. We applied a new optical coherence tomography (OCT) technique, at rest and during reactive hyperemia (RH), to assess the skin microvasculature in people with diabetes with foot ulcers (DFU, n = 13), those with diabetes without ulcers (DNU, n = 9), and matched healthy controls (CON, n = 13). OCT images were obtained from the dorsal part of the foot at rest and following 5 min of local ischemia induced by inflating a cuff around the thigh at suprasystolic level (220 mmHg). One-way ANOVA was used to compare the OCT-derived parameters (diameter, speed, flow rate, and density) at rest and in response to RH, with repeated-measures two-way ANOVA performed to analyze main and interaction effects between groups. Data are means ± SD. At rest, microvascular diameter in the DFU (84.89 ± 14.84 µm) group was higher than CON (71.25 ± 7.6 µm, P = 0.012) and DNU (71.33 ± 12.04 µm, P = 0.019) group. Speed in DFU (65.56 ± 4.80 µm/s, P = 0.002) and DNU (63.22 ± 4.35 µm/s, P = 0.050) were higher than CON (59.58 ± 3.02 µm/s). Microvascular density in DFU (22.23 ± 13.8%) was higher than in CON (9.83 ± 2.94%, P = 0.008), but not than in the DNU group (14.8 ± 10.98%, P = 0.119). All OCT-derived parameters were significantly increased in response to RH in the CON group (all P < 0.01) and DNU group (all P < 0.05). Significant increase in the DFU group was observed in speed (P = 0.031) and density (P = 0.018). The change in density was lowest in the DFU group (44 ± 34.1%) compared with CON (199.2 ± 117.5%, P = 0.005) and DNU (148.1 ± 98.4, P = 0.054). This study proves that noninvasive OCT microvascular imaging is feasible in people with diabetes, provides powerful new physiological insights, and can distinguish between healthy individuals and patients with diabetes with distinct disease severity.

Early T1 Myocardial MRI Mapping: Value in Detecting Myocardial Hyperemia in Acute Myocarditis.

Background Hyperemia is a key component of acute myocarditis (AM). Early gadolinium uptake because of myocardial hyperemia may be quantified by using T1 mapping. Purpose To evaluate the value of early enhanced T1 shortening for the diagnosis of acute myocarditis. Materials and Methods Study participants suspected of having AM and healthy control (HC) participants were prospectively enrolled from September 2016 to May 2019. Participants underwent 1.5-T cardiac MRI including Lake Louise criteria, T2 mapping, native T1, and extracellular volume, with the addition of early enhanced T1 mapping (2 minutes after intravenous administration of 0.15 mmol/kg gadobutrol). Color-coded maps of the percentage of T1 shortening from precontrast to early postcontrast were generated. Optimal early T1 shortening cut-off value and its diagnostic performance in the identification of acute myocarditis were calculated. Results Forty-five study participants with AM (median age, 40 years; interquartile range [IQR], 20-46 years; 22 women) diagnosed according to multidisciplinary clinical evaluation, electrocardiography, laboratory test, echocardiography, cardiac MRI, and coronary CT and/or invasive angiography. Findings were confirmed by endomyocardial biopsy in 64% (29 of 45) of participants. MRI parameters were compared with 19 HC participants (median age, 39 years; IQR, 28-46 years; seven women). Median early T1 shortening was 75% (IQR, 72%-78%) in participants with AM versus 65% (IQR, 61%-66%) in HC participants (P < .001). Early T1 shortening showed high diagnostic performance (area under the receiver operating characteristic curve [AUC], 0.97; 95% confidence interval [CI]: 0.94, 1.00) and excellent interobserver reproducibility (intraclass correlation coefficient: 0.98; 95% CI: 0.96, 1.00). Early T1 shortening of 70% or greater identified acute myocarditis with 93% sensitivity, 100% specificity, and 95% diagnostic accuracy. Early T1 shortening had better diagnostic performance than late percentage T1 shortening (AUC, 0.97 vs 0.90, respectively; P = .03) and extracellular volume (AUC, 0.97 vs 0.88, respectively; P = .046), and similar to native T1 (AUC, 0.97 vs 0.93, respectively; P = .63) and T2 mapping (AUC, 0.97 vs 0.97, respectively; P > .99). Conclusion In this proof-of-concept study, percentage of T1 shortening at early enhanced T1 mapping showed high accuracy for the diagnosis of acute myocarditis. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by De Cecco and Monti in this issue.

Shear-thinning behaviour of blood in response to active hyperaemia: Implications for the assessment of arterial shear stress-mediated dilatation.

NEW FINDINGS: What is the central question of this study? Quantitative values of shear rate-specific blood viscosity and shear stress in the human macrovasculature in response to exercise hyperaemia are unknown. What is the main finding and its importance? Using the handgrip exercise model, we showed that an increase in brachial artery shear rate led to a decrease in blood viscosity, despite concomitant haemoconcentration. This shear-thinning behaviour of blood, secondary to increased erythrocyte deformability, blunted the expected increase in brachial artery shear stress based on shear rate prediction. Our data yield new insights into the magnitude and regulation of macrovascular blood viscosity and shear stress in physiological conditions of elevated metabolic demand and blood flow in humans. ABSTRACT: Blood viscosity is a well-known determinant of shear stress and vascular resistance; however, accurate quantitative assessments of shear rate-specific blood viscosity in the macrovasculature in conditions of elevated blood flow are inherently difficult, owing to the shear-thinning behaviour of blood. Herein, 12 men performed graded rhythmic handgrip exercise at 20, 40, 60 and 80% of their maximal workload. Brachial artery shear rate and diameter were measured via high-resolution Duplex ultrasound. Blood was sampled serially from an i.v. cannula in the exercising arm for the assessment of blood viscosity (cone-plates viscometer). We measured ex vivo blood viscosity at 10 discrete shear rates within the physiological range documented for the brachial artery in basal and exercise conditions. Subsequently, the blood viscosity data were fitted with a two-phase exponential decay, facilitating interpolation of blood viscosity values corresponding to the ultrasound-derived shear rate. Brachial artery shear rate and shear stress increased in a stepwise manner with increasing exercise intensity, reaching peak values of 940 ± 245 s-1 and 3.68 ± 0.92 Pa, respectively. Conversely, brachial artery shear rate-specific blood viscosity decreased with respect to baseline values throughout all exercise intensities by ∼6-11%, reaching a minimal value of 3.92 ± 0.35 mPa s, despite concomitant haemoconcentration. This shear-thinning behaviour of blood, secondary to increased erythrocyte deformability, blunted the expected increase in shear stress based on shear rate prediction. Consequently, the use of shear stress yielded a higher slope for the brachial artery stimulus versus dilatation relationship than shear rate. Collectively, our data refute the use of shear rate to infer arterial shear stress-mediated processes.

Contrast-Enhanced Ultrasound in the Short-Term Evaluation of Hepatocellular Carcinoma after Locoregional Treatment.

BACKGROUND: Contrast-enhanced ultrasound (CEUS) with second-generation contrast agents performed 1 month after hepatocellular carcinoma (HCC) treatment is almost as sensitive as contrast-enhanced computed tomography (CECT) in depicting the residual tumor. However, the efficacy of CEUS performed early after the procedure is still debated. AIM: We evaluated the diagnostic accuracy (DA) of CEUS for the assessment of tumor response shortly after locoregional therapy in patients with unresectable HCC. METHODS: Ninety-four patients with 104 HCC lesions who were scheduled to receive percutaneous ethanol injection, radiofrequency ablation, transcatheter arterial chemoembolization, or combined treatment were enrolled in this study. With CECT at 1-month as the reference standard, the DA of CEUS performed 48-h after the procedure was evaluated. Patients were followed-up to look for tumor or disease progression. RESULTS: Based on CECT findings, 43/104 lesions were diagnosed as having residual viability after 1 month. CEUS performed 48 h after treatment detected residual tumor in 34/43 nodules with treatment failure at CECT with a sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of 79.1, 96.7, 94.4, 86.8, and 89%, respectively. There was a high degree of concordance between CEUS and CECT (kappa coefficient = 0.78). A hyperemic halo was detectable in 35 lesions without a statistically significant difference between concordant and discordant cases. In patients with uninodular disease responders according to 48 h CEUS had a significantly longer mean overall survival and time to progression compared to nonresponders. CONCLUSION: CEUS performed 48 h after treatment can be considered a reliable modality for the evaluation of the real extent of necrosis and has prognostic value in the assessment of HCC.

Focal hyperemia in Wernicke's encephalopathy: a preliminary arterial spin labeling MRI study.

Although a perturbed cerebral blood flow (CBF) has been reported in patients with Wernicke's encephalopathy (WE), its clinical meaning is still elusive. A retrospective analysis of 10 patients (male, 6; mean age, 57.7 years) with WE between October 2012 and May 2018 was performed. Brain imaging was performed using fluid-attenuated inversion recovery (FLAIR), diffusion-weighted imaging (DWI), arterial spin labeling (ASL) perfusion-weighted imaging (PWI), and contrasted enhanced T1-weighted imaging. All patients had symmetric high signal intensity lesions in the vulnerable areas on FLAIR or DWI with focal hyperintensity on ASL-PWI (100% sensitivity). CBFlesion was variable (from 70 mL/100 g/min to 190.0 mL/100 g/min). CBFlesion/CBFwhite matter was elevated, ranging from 2.5 to 5.5. Focal hyperintensity on ASL in the vulnerable areas can be a diagnostic clue for WE.

Effects of aging on coronary flow reserve in patients with no evidence of myocardial perfusion abnormality.

Coronary flow reserve (CFR) reflects the functional capacity of microcirculation to adapt to blood demand during increased cardiac work. We tested the hypothesis that aging had impacts on coronary flow velocities and CFR in patients with no evidence of myocardial perfusion abnormality on single photon emission computed tomography (SPECT). Seventy-six patients undergoing transthoracic Doppler echocardiography with no evidence of myocardial perfusion abnormality on SPECT were enrolled in this study. CFR was defined as the ratio of hyperemic to resting peak diastolic coronary flow velocity. Patients were divided into the three groups based on age: 17 patients aged less than 70 years (Group I), 38 patients aged 70-79 years (Group II), and 21 patients aged 80 years or more (Group III). Compared with Group I, CFR was significantly lower in Group II (p < 0.01) and Group III (p < 0.01). Multivariate linear regression analysis showed that female (ß = - 0.26, p = 0.03), cigarette smoking (ß = - 0.32, p = 0.004), hemoglobin level (ß = - 0.40, p = 0.001) and LV mass index (ß = 0.24, p = 0.03) were determinants for resting coronary flow velocity. On the other hand, age (ß = -0.30, p = 0.008), hemoglobin level (ß = -0.47, p < 0.001) and LV mass index (ß = 0.24, p = 0.04) were determinants for hyperemic coronary flow velocity. Age was only determinant for CFR (ß = -0.48, p < 0.001). Our data suggested that that aging had a decreased effect on hyperemic coronary flow velocity rather than resting coronary flow velocity, and was further associated with impaired CFR in patients with no evidence of myocardial perfusion abnormality.