Pseudomonas aeruginosa Infections Are Associated with Infection Recurrence in Arteriovenous Grafts Treated with Revision.

Background and Objectives: This study was conducted to investigate whether Pseudomonas aeruginosa (PA) infections of arteriovenous grafts (AVGs) recur more frequently than other bacterial infections following treatment with revision. Materials and Methods: Operative procedures, including total excision, subtotal excision, and revision, were performed on 60 patients to treat 65 AVG infections. Final outcomes were classified as no infection recurrence, infection recurrence, and death without prior recurrence. In the competing risk setting, the cumulative incidence was estimated using the cumulative incidence function and Gray's test, and the associations between outcomes and different variables were estimated using a subdistribution hazard (SDH) model. Results: Comparing AVG infections with and without recurrence, PA infection was not associated with a higher risk of infection recurrence (p = 0.13); however, the first operative procedure type was associated with infection recurrence (p = 0.04). AVGs with PA infection were associated with a higher total number of surgical interventions (p < 0.05) than AVGs without PA infection. Regarding the cumulative incidences of outcomes, for AVGs treated with subtotal excision or revision, the cumulative incidence of recurrent infection was 3.3-fold higher for those with PA infection than without one year after the first surgery. However, when AVGs were treated with revision alone, the cumulative incidence was 4.1-fold. After excluding AVGs treated with total excision, the SDH model was applied, obtaining a hazard ratio for infection recurrence of 16.05 (p = 0.02) for AVGs with PA infection compared with AVGs without PA infection. No other variables were significantly associated with infection recurrence. Conclusions: For subtotal resection and revision, AVGs infected with PA had a higher recurrence rate than those infected with other species. However, revision surgery may aggravate the recurrence rate.

Molecular Characteristics and Distribution of Virulence Genes among Staphylococcus aureus Complex Isolates Derived from Vascular Access Infections.

Staphylococcus aureus is a major human pathogen that produces various virulence factors which promote the binding of bacteria to tissues and medical devices such as vascular access devices, thereby developing a wide range of invasive infections. Vascular access serves as an entry site for S. aureus and elevates the risk of infection in the hemodialysis population. Nevertheless, the distribution of virulence genes in Staphylococcus spp. associated with vascular access infections (VAIs) has not been studied previously. In this study, we determined the relationship between the molecular characteristics and virulence profiles of S. aureus isolates obtained from VAIs. We collected isolates from patients with VAIs between August 2017 and December 2020 and further analyzed the molecular characteristics, antimicrobial resistance profiles, and virulence gene distribution in the isolates. Overall, 15 sequence types (STs), including a new ST (ST6892) and 19 spa types, were identified among the 56 isolates. Of the 53 S. aureus isolates, ST8, ST239, ST45, and ST59 were the predominant STs, whereas ST2250 was the only ST in 3 S. argenteus isolates. ST45-SCCmecIV-t026 (abbreviated as ST45-IV-t026), ST59-V-t437, and ST8-IV-t008 were the predominant clones that belonged to agr type I. All isolates harbored clfB and eno, whereas all S. aureus isolates harbored clfA. In addition, 10 Panton-Valentine leucocidin-positive isolates belonged to ST8 and ST59, with ST8-IV-t008 and ST59-V-t437 being the predominant clones. In brief, the distribution of virulence genes associated with STs may assist in the spread of molecular types of Staphylococcus spp.

Reduced External Iliac Venous Blood Flow Rate Is Associated with Asymptomatic Compression of the Common Iliac Veins.

Background and Objectives: Compression of the common iliac veins (CIV) is not always associated with lower extremity symptoms. This study analyzed this issue from the perspective of patient venous blood flow changes using quantitative flow magnetic resonance imaging. Materials and Methods: After we excluded patients with active deep vein thrombosis, the mean flux (MF) and mean velocity (MV) of the popliteal vein, femoral vein, and external iliac vein (EIV) were compared between the left and right sides. Results: Overall, 26 of the patients had unilateral CIV compression, of which 16 patients had symptoms. No significant differences were noted in the MF or MV of the veins between the two sides. However, for the 10 patients without symptoms, the EIV MF of the compression side was significantly lower than the EIV MF of the non-compression side (p = 0.04). The receiver operating characteristic curve and chi-squared analyses showed that when the percentage difference of EIV MF between the compression and non-compression sides was ≤-18.5%, the relative risk of associated lower extremity symptoms was 0.44 (p = 0.016). Conclusions: If a person has compression of the CIV, a decrease in EIV blood flow rate on the compression side reduces the rate of symptom occurrence.

Effect of carvedilol on arteriovenous graft primary patency.

BACKGROUND: The major mechanisms of arteriovenous graft (AVG) failure due to intimal hyperplasia (IH) are smooth muscle cell proliferation and inflammation. Therefore, carvedilol may improve AVG primary patency because of its anti-proliferative and anti-inflammatory activities. METHODS: The data of end-stage renal disease patients receiving regular hemodialysis were collected from the National Health Insurance Research database. The end point was the first percutaneous transluminal angioplasty (PTA) for AVG failure or death during a follow-up period of two years or the end of 2013. The analysis was calculated with Cox proportional hazard model. RESULTS: There were 3028 patients treated with carvedilol and 13,704 patients not treated with carvedilol. According to a univariate analysis, the carvedilol group was younger, received more anti-hypertensive medications and platelet aggregation inhibitors, and had higher rates of diabetes mellitus and hyperlipidemia but had lower rates of hypotension and smoking. According to a multivariate analysis, after controlling for covariates, the use of carvedilol for more than 84 days reduced the probability of a first PTA for AVG failure by 9% compared with no use of carvedilol (p = 0.021), but the use of carvedilol for 1 to 84 days did not. CONCLUSION: The results of this study indicate that the use of carvedilol for more than 84 days improves the primary patency of AVGs, but the use of carvedilol for less than 84 days does not.

The Influence of Diffuse Left Anterior Descending Artery Lesions on Outcomes of Coronary Artery Bypass Grafting.

BACKGROUND: Diffuse coronary lesions adversely influence the outcomes of coronary artery bypass grafting (CABG). This study aimed to investigate the influence of diffuse left anterior descending artery (LAD) lesions on the outcomes of CABG. METHODS: The data of 123 patients, who received elective isolated CABG with the left internal mammary artery bypassed to the LAD from January 2011 to June 2017, were collected. According to their lesions (≥50% diameter stenoses) ≤2cm or >2cm in the middle and distal segment of LAD, the patients were classified into a No Diffuse Lesion (NDL) group (69 patients) and a Diffuse Lesion (DL) group (54 patients). The rates of in-hospital mortality, 5-year all-cause mortality, and major cardiac events (MCEs) (i.e. myocardial infarction, angina, acute heart failure, and atrial fibrillation) were analyzed. RESULTS: According to the univariate analyses, the NDL group had fewer diffuse left circumflex artery (LCX) lesions (P = .001) and higher ventricular fibrillation (Vf) after aortic de-clamping (P = .03) than the DL group. According to the multivariate analyses, the in-hospital and 5-year all-cause mortality rates of the two groups did not significantly differ (P = .80 and P = .59). Otherwise, the DL group had a trend toward more MCEs (hazard ratio = 2.07, P = .061), but the difference clearly was insignificant after adjusting for diffuse LCX lesions and Vf after aortic de-clamping (P = .104). CONCLUSIONS: The results demonstrated that diffuse LAD lesions did not influence the risks of in-hospital mortality, 5-year all-cause mortality, or MCEs after CABG.

Do the Paths of Sequential Vein Grafts Influence the Outcomes of Coronary Artery Bypass Surgeries?

BACKGROUND: The use of a sequential vein graft (SVG) in coronary artery bypass grafting (CABG) in multi-vessel coronary disease is common. This study aimed to investigate the influence of the paths of SVGs on the outcomes of CABG. METHODS: From January 2011 to June 2017, 126 patients underwent elective isolated CABG. If the path of the SVG was from the aorta to the right coronary artery (RCA)/ posterior descending artery (PDA) to the left circumflex artery (LCX)/obtuse marginal artery (OM), the patients were included in Group R. If the path was from the aorta to the LCX/OM to the RCA/PDA, the patients were included in Group L. The in-hospital and follow-up outcomes were analyzed. RESULTS: Group R had 69 patients, and Group L had 57 patients. Univariate analysis showed that Group L had a higher number of grafts (P < .001) and less aortic cross-clamping time (P < .001) and total bypass time (P = .001). Otherwise, Group L had 14 patients (19.3%), who received first diagonal branch (D1) bypass grafting, while Group R had none (P < .001). In the multivariate analysis, in- hospital mortality from heart failure, postoperative acute kidney injury, medium-term mortality, and readmission for cardiac incidents were not associated with the SVG path. CONCLUSION: The SVG path from the aorta to the LCX/OM to the RCA/PDA facilitated the additional D1 bypass grafting, but the outcomes for this approach were not significantly different from those for the other path.

Using Wireless Near-Infrared Spectroscopy to Predict Wound Prognosis in Diabetic Foot Ulcers.

OBJECTIVE: To use wearable near-infrared spectroscopy (NIRS) to determine the effect of Buerger exercises on diabetic foot ulcer (DFU) healing. METHODS: Study authors enrolled 50 consecutive patients in a 1-year prospective observational study of DFUs. The patients were divided into groups by their arterial statuses: group A (no peripheral arterial disease [PAD]), group B (PAD without angioplasty), and group C (PAD with angioplasty). Tissue perfusion was assessed through wireless wearable NIRS to determine the effects of Buerger exercises on wound healing. MAIN RESULTS: The patients in group C were older, were more likely to have had an amputation, and had more severe wounds than did the patients in other groups. The requirements of insulin injection for diabetes mellitus control differed significantly (P = .024) among the three groups. At the end of the survey, 19 patients (38%) had unhealed DFUs. The NIRS revealed that most nonhealed patients in groups B and C shared higher resting hemoglobin levels and tissue blood volume and lower tissue oxygen concentration, which indicated inflammation accompanied by higher blood flow and oxygen consumption. Notably, the nonhealed patients in group C showed paradoxically reduced hemoglobin and tissue blood volume after the exercises. CONCLUSIONS: Although DFUs remain a challenge to treat, NIRS may prove valuable in predicting wound healing by identifying risk factors for poor wound prognosis, such as reduced hemoglobin and tissue blood volume after exercise.

Evaluation of venous pathology of the lower extremities with triggered angiography non-contrast-enhanced magnetic resonance imaging.

BACKGROUND: To explore the diagnostic performance of triggered angiography non-contrast-enhanced magnetic resonance imaging (TRANCE-MRI) for the evaluation of venous pathology of the lower extremity. METHODS: This was a single-centre prospective cohort study of 25 patients with suspected venous disease in the lower extremities. Each patient received Doppler ultrasonography (for venous evaluation) before the scheduled TRANCE-MRI (for venous and arterial evaluations) on a 1.5 T MR scanner (Philips Ingenia, Philips Healthcare, Best, the Netherlands), followed by lymphography and computed tomography angiography that were arranged according to the diagnostic indications. RESULTS: The sensitivity, specificity and accuracy of TRANCE-MRI were 85.7%, 88/9 and 88%, respectively. The inter-rater agreement for deep vein thrombosis (DVT) of the thigh between the ultrasonography and TRANCE-MRI results was substantial agreement (Cohen's kappa κ, 0.72). In ultrasonography-negative cases, TRANCE-MRI detected four additional cases (16%, 4/25) of DVT; three cases (12%, 3/25) of venous compression caused by pelvic lymphadenopathy, hip prosthesis or knee joint effusion; one case (4%, 1/25) of vena cava anomaly; two cases (8%, 2/25) of occult peripheral artery disease (PAD); and one case (4%, 1/25) of an occluded bypass graft. CONCLUSION: TRANCE-MRI can be used as an alternative and objective tool for assessing lower extremity diseases, especially suspected venous pathology. Compared with ultrasonography, TRANCE-MRI plays a better role in assessing varicose veins of the lower extremities and deep veins of the pelvis and abdomen. However, false-positive results may occur in the left common iliac vein of elderly patients. Finally, occult PAD rarely occurs in patients with suspected lower extremity venous disease. Therefore, we recommend performing the TRANCE-MRV protocol instead of the full protocol (MRV + MRA) in the clinical setting in patients with venous scenarios.

The role of venous pressure variability during hemodialysis in the prediction of impending arteriovenous graft occlusion.

BACKGROUND: Elevated venous pressure during hemodialysis (VPHD) is associated with arteriovenous graft (AVG) stenosis. This study investigated the role of VPHD variations in the prediction of impending AVG occlusion. METHODS: Data were retrieved from 118 operations to treat AVG occlusion (occlusion group) and 149 operations to treat significant AVG stenosis (stenosis group). In addition to analyzing the VPHD values for the three hemodialysis (HD) sessions prior to the intervention, VPHD values were normalized to mean blood pressure (MBP), blood flow rate (BFR), BFR × MBP, and BFR2 × MBP to yield ratios for analysis. The coefficient of variation (CV) was used to measure relative variations. RESULTS: The within-group comparisons for both groups revealed no significant differences in the VPHD mean and CV values among the three HD sessions prior to intervention. However, the CVs for VPHD/MBP, VPHD/(BFR × MBP), and VPHD/(BFR2 × MBP) exhibited significant elevation in the occlusion group during the last HD session prior to intervention compared with both the penultimate and antepenultimate within-group HD data (p < 0.05). In the receiver operating characteristic curve analysis, the CV for VPHD/(BFR2 × MBP) was the only parameter able to discriminate between the last and the penultimate HD outcomes (p < 0.001). According to a multivariate analysis, after controlling for covariates, CV for VPHD/(BFR2 × MBP) >8.76% was associated with a higher risk of AVG thrombosis (odds ratio: 3.17, p < 0.001). CONCLUSIONS: Increasing the variation in VPHD/(BFR2 × MBP) may increase the probability of AVG occlusion.

Appraisal of lung cancer survival in patients with end-stage renal disease.

Introduction: The survival outcome of lung cancer patients with end-stage renal disease has been poorly studied in the literature. In this study, we evaluated the effect of end-stage renal disease on lung cancer survival. Material and methods: A retrospective, multicenter, matched-cohort study of lung cancer patients with end-stage renal disease under renal replacement therapy (WITH-ESRD) and without end-stage renal disease (WITHOUT-ESRD) was performed. One WITH-ESRD patient was matched to four WITHOUT-ESRD patients. Results: Baseline clinical characteristics did not differ statistically significantly after matching between the WITH-ESRD and WITHOUT-ESRD groups. WITH-ESRD included 133 patients and WITHOUT-ESRD included 532 patients. Kaplan-Meier survival analysis demonstrated no significant difference in median overall survival between WITH-ESRD patients and WITHOUT-ESRD patients (7.36 months versus 12.25 months, respectively, p = 0.133). Lung cancer WITH-ESRD patients receiving medical treatment had a median overall survival of 5.98 months (95% CI: 4.34-11.76) compared to 14.13 months (95% CI: 11.30-16.43) for WITHOUT-ESRD patients, p = 0.019. Although patients receiving surgical treatment compared to those receiving medical treatment had an improvement of survival by 46% (HR = 0.54, 95% CI: 0.19-1.53, p = 0.243), the difference did not reach statistical significance. Cox regression analysis revealed that male gender and stage IIIA-IV were independent factors associated with poor outcome for WITH-ESRD patients. Conclusions: In our limited experience, the survival for lung cancer with ESRD is not inferior to lung cancer patients without ESRD. The reasons for poor survival for the WITH-ESRD medical treatment group and late diagnosis despite frequent medical visits merit further investigation.

Noncontrast MRI in assessing venous reflux of legs using QFlow analysis and radial basis function neural network technique.

Since venous reflux is difficult to quantify, triggered angiography non-contrast-enhanced (TRANCE)-magnetic resonance imaging (MRI) is a novel tool for objectively evaluating venous diseases in the lower extremities without using contrast media. This study included 26 pre-intervention patients with superficial venous reflux in the lower extremities and 15 healthy volunteers. The quantitative flow (QFlow) analyzed the phase shift information from the pixels within the region of interest from MRI. The fast and simple radial basis function neural network (RBFNN) learning model is constructed by determining the parameters of the radial basis function and the weights of the neural network. The input parameters were the variables generated through QFlow, while the output variables were morbid limbs with venous reflux and normal limb classification. The stroke volume, forward flow volume, absolute stroke volume, mean flux, stroke distance, and mean velocity of greater saphenous veins from QFlow analysis could be used to discriminate the morbid limbs of pre-intervention patients and normal limbs of healthy controls. The neural network successfully classified the morbid and normal limbs with an accuracy of 90.24% in the training stage. The classification of venous reflux using the RBFNN model may assist physicians in clinical settings.

Insight into the Clonal Lineage and Antimicrobial Resistance of Staphylococcus aureus from Vascular Access Infections before and during the COVID-19 Pandemic.

Patients receiving hemodialysis are at risk of vascular access infections (VAIs) and are particularly vulnerable to the opportunistic pathogen Staphylococcus aureus. Hemodialysis patients were also at increased risk of infection during the COVID-19 pandemic. Therefore, this study determined the change in the molecular and antibiotic resistance profiles of S. aureus isolates from VAIs during the pandemic compared with before. A total of 102 S. aureus isolates were collected from VAIs between November 2013 and December 2021. Before the pandemic, 69 isolates were collected, 58%, 39.1%, and 2.9% from arteriovenous grafts (AVGs), tunneled cuffed catheters (TCCs), and arteriovenous fistulas (AVFs), respectively. The prevalence of AVG and TCC isolates changed to 39.4% and 60.6%, respectively, of the 33 isolates during the pandemic. Sequence type (ST)59 was the predominant clone in TCC methicillin-resistant S. aureus (MRSA) and AVG-MRSA before the pandemic, whereas the predominant clone was ST8 in AVG-MRSA during the pandemic. ST59 carrying the ermB gene was resistant to clindamycin and erythromycin. By contrast, ST8 carrying the msrA gene was exclusively resistant to erythromycin. The ST distribution for different VAIs changed from before to during the pandemic. The change in antibiotic resistance rate for different VAIs was closely related to the distribution of specific STs.

Quantitative two-dimensional phase-contrast magnetic resonance imaging characterization of lower extremity venous disease: venous reflux versus venous obstruction.

Background: Lower extremity venous disease (LEVD) is a complex disorder, and determining the etiology of LEVD is paramount for treatment selection. Two-dimensional phase-contrast magnetic resonance imaging (2D PC-MRI) can provide an objective measure of hemodynamic status and may help differentiate between different etiologies of LEVD. A total of 271 participants, including 256 symptomatic patients with venous lower extremity disease and 15 healthy volunteers, were collected in this cohort study. Methods: It is a single-center prospective observational study using 2D PC-MRI analysis to assess the hemodynamic characteristics of patients with LEVD among participants recruited between April 2017 and October 2021 at a tertiary hospital. The approval institutional review board number for this study were 201802137B0, 201901058B0, 202100938B0, and 202102344B0. Participants were classified as venous reflux (VR) and venous obstruction (VO) by standard ultrasonography. 2D PC-MRI by 1.5 T scanner revealed stroke volume (SV), forward flow volume (FFV), absolute stroke volume (ASV), mean flux (MF), velocity time integral (VTI), and mean velocity (MV) for each selected venous segments. Results: 2D PC-MRI assessed 167 diseased legs from the 116 VR patients [mean age ± standard deviation (SD): 57.9±12.8 years; 39 males] and 113 diseased legs from the 95 VO patients (mean age ± SD: 66.4±12.8 years; 42 males). 2D PC-MRI analysis demonstrated discrimination ability to differentiate from VR to VO [SV, FFV, ASV, MF, VTI, and MV in the various venous segments, respectively, P≤0.001; area under the curve (AUC) =62-68.8%, P≤0.001 by Mann-Whitney U test]. The ratio data (morbid limb to normal limb) in the same individual with single-leg disease revealed differences between VR and VO (SV, FFV, ASV, and MF in the various venous segments, respectively; P<0.05; AUC =60.2-68.7%, P≤0.05 by Mann-Whitney U test). The most favorable differentiating variables of ratios were FFV in the great saphenous veins [AUC =68.7%, 95% confidence interval (CI): 59.8-77.6%] and ASV in the external iliac veins (AUC =67.4%, 95% CI: 58.7-76.2%). Conclusions: Quantitative 2D PC-MRI analysis is capable of differentiating VR from VO. It also provides an important diagnostic capability for preoperative evaluation.

Blood Flow Analysis of the Great Saphenous Vein in the Su-Pine Position in Clinical Manifestations of Varicose Veins of Different Severities: Application of Phase-Contrast Magnetic Resonance Imaging Data.

The progression of clinical manifestations of lower-limb varicose veins remains unclear. This study investigated changes in lower-limb venous blood flow using phase-contrast magnetic resonance angiography. Data were collected on veins from 141 legs. We compared legs with and without varicose veins and related symptoms and examined varying levels of varicose vein symptom severity. Legs without varicose veins exhibited a lower absolute stroke volume (ASV, p < 0.01) and mean flux (MF, p = 0.03) for the great saphenous vein (GSV) compared with legs with symptomatic varicose veins. Legs with asymptomatic varicose veins exhibited lower MF for the GSV (p = 0.02) compared with legs with symptomatic varicose veins. Among legs with varicose veins, asymptomatic legs exhibited lower ASV (p = 0.03) and MF (p = 0.046) for the GSV compared with legs that exhibited skin changes or ulcers; however, no significant differences were observed between legs presenting with discomfort or edema and legs with skin changes or ulcers, and between legs presenting with discomfort or edema and asymptomatic legs. In conclusion, in the supine position, increased blood flow rate and blood flow volume in the GSV were associated with symptomatic varicose veins and increased symptom severity.

Venous Segmental Flow Changes after Superficial Venous Intervention Demonstrating by Quantitative Phase-Contrast Magnetic Resonance Analysis: Preliminary Data from a Longitudinal Cohort Study.

The effects of superficial venous intervention on hemodynamics can be quantified using two-dimensional phase-contrast magnetic resonance imaging (2D PC-MRI). Twelve patients received pre- and postintervention 2D PC-MRI analysis using quantitative hemodynamic parameters. Fifteen healthy volunteers served as controls. The 2D PC-MRI results of the target limbs (limbs scheduled for intervention for venous reflux) differed from those of the controls in terms of stroke volume (SV), forward flow volume (FFV), absolute stroke volume (ASV), and mean flux (MF) in all venous segments. The velocity time integral (VTI) and mean velocity (MV) of the popliteal vein (PV) segments were similar between the target limbs and controls preoperatively. After intervention, the target limbs exhibited an increase in VTI and MV in the femoral vein (FV) and PV segments. We compared the target and nontreated limbs of the individual patients preoperatively and postoperatively to minimalize individual bias. All QFlow parameter ratios in the FV segment increased after venous intervention (VTI, p = 0.025; MV, p = 0.024). In the PV segment, FFV and ASV increased significantly (p = 0.035 and 0.024, respectively). After interventions, the volume (FFV and ASV) of the PV segment and the efficiency (VTI and MV) of the FV segment significantly increased.

Superficial Venous Reflux Intervention Guided by Triggered Angiography Non-Contrast-Enhanced Sequence Magnetic Resonance Imaging: Different QFlow Pattern from Health Controls.

(1) Background: To assess the effectiveness of triggered angiography non-contrast-enhanced (TRANCE)-magnetic resonance imaging (MRI) in superficial venous reflux and its difference from health controls. (2) Methods: Thirty patients underwent TRANCE MRI before surgical intervention of their superficial venous reflux of the legs. Ten healthy volunteers were included as a control. (3) Results: TRANCE MRI involves the major tributaries, thus enhances the additional ablations in 20% of patients. QFlow pattern of superficial venous reflux (QFlow GSV/PV MF ratio > 1) was compared with the duplex scan (SFJ reflux) using Cohen's kappa coefficient at 0.967. The 30 morbid legs undergoing TRANCE MRI-guide interventions and the healthy volunteers' legs on the same side were compared. The stroke volumes (SV) are higher in EIV (p = 0.021) in the left-leg-intervention group. The mean flux (MF) is higher in the EIV (p = 0.012) and trend of increasing in GSV segment (p = 0.087) in the left-leg-intervention group. The QFlow of 10 patients with right leg intervention are higher in GSV in the right-leg-intervention group (SV p = 0.002; FFV p = 0.001; MF p = 0.001). QFlow data is shown for all legs for superficial venous intervention with GSV/PV (MF) ratio > 1. (4) Conclusions: Typical figures in QFlow (GSV/PV MF ratio > 1) could be observed in the morbid limbs but not in the controls.

Discriminating Reflux from Non-Reflux Diseases of Superficial Veins in Legs by Novel Non-Contrast MR with QFlow Technique.

Objectives: To find an objective diagnostic tool for the superficial veins in legs. Methods: This study included 137 patients who underwent TRANCE-MRI from 2017 to 2020 (IRB: 202001570B0). Among them, 53 with unilateral leg venous diseases underwent a QFlow scan and were classified into the reflux and non-reflux groups according to the status of the great saphenous veins. Results: The QFlow, namely stroke volume (SV), forward flow volume (FFV), mean flux (MF), stroke distance (SD), and mean velocity (MV) measured in the external iliac, femoral, popliteal, and great saphenous vein (GSV). The SV, FFV, SD, MF, SD, and MV in the GSV (morbid/non-morbid limbs) demonstrated a favorable ability to discriminate reflux from non-reflux in the ROC curve. The SD in the GSV and GSV/PV ratio (p = 0.049 and 0.047/cutoff = 86 and 117.1) and the MV in the EIV/FV ratio, GSV, and GSV/PV ratio (p = 0.035, 0.034, and 0.025/cutoff = 100.9, 86.1, and 122.9) exhibited the ability to discriminate between reflux and non-reflux group. The SD, MV, and FFV have better ability to discriminate a reflux from non-reflux group than the SV and MF. Conclusions: QFlow may be used to verify the reflux of superficial veins in the legs. An increasing GSV/PV ratio is a hallmark of reflux of superficial veins in the legs.

Aortic dissection assessment by 4D phase-contrast MRI with hemodynamic parameters: the impact of stent type.

BACKGROUND: To explore the diagnostic performance of 4-dimensional phase-contrast magnetic resonance imaging (4D PC-MRI) in evaluating aortic dissection in different clinical scenarios. METHODS: The study group comprised 32 patients with a known aortic dissection who each underwent computed tomography angiography (CTA), and then 4D PC-MRI with a 1.5-T MR scanner. The 4D PC-MRI images were compared with the CTA images to evaluate the aortic size, branch identification, and iliac and femoral arterial access. RESULTS: The patients were divided into three groups: (I) patients diagnosed with Type B aortic dissection but did not undergo intervention (n=8); (II) patients with residual aortic dissection after open repair of Type A dissection (n=7); (III) patients who underwent endovascular aortic repair with or without open surgery (n=17). Without radiation or contrast media injection, 4D PC-MRI provided similar aortic images for patients in Group 1 and most of those in Group 2. In Group 3, stainless steel stents affected image quality in three patients. High-quality 4D PC-MRI images were obtained for the remaining 14 patients in Group 3, who had non-stainless steel stents, and provided major aortic information comparable to that provided by CTA with contrast media. The hemodynamic parameters of true and false lumens were evaluated between three patients with Type B aortic dissections and three patients who underwent thoracic endovascular aortic repair for their aortic dissection. The stroke volume was higher in the true lumen of the patients with stent-grafts than in the patients with Type B aortic dissection without intervention. The regurgitant fraction, an indicator of nonlaminar flow, was higher in the false lumens than in the true lumens. All 32 patients in this study tolerated 4D PC-MRI without adverse events. CONCLUSIONS: 4D PC-MRI is radiation- and contrast media-free option for imaging aortic dissection. It not only provided images comparable in quality to those obtained with CTA but also provided information on hemodynamic parameters, including endoleak detection after thoracic endovascular aortic repair. 4D PC-MRI was safe and accurate in evaluating chronic Type B aortic dissection and residual aortic dissection after surgery for acute Type A aortic dissection. Therefore, it could be a potential tool in treating pathology in aortic dissection, especially for patients with malperfusion syndrome of visceral vessels and in young patients with renal function impairment. However, certain endograft materials, especially stainless steel, may prevent the further application of 4D PC-MRI and should be avoided.

A Novel Tool for a Challenging Disease: Stasis Leg Ulcers Assessed Using QFlow in Triggered Angiography Noncontrast Enhanced Magnetic Resonance Imaging.

Imaging characteristics of stasis leg ulcers (SLUs) are not easily demonstrated through existing diagnostic tools. Early diagnosis and treatment are crucial. This pilot study was conducted to assess the quantitative flow (QFlow) in triggered angiography noncontrast enhanced (TRANCE) magnetic resonance imaging (MRI) to identify the hemodynamics of victims with stasis leg ulcers (SLUs). This study included 33 patients with SLUs and 14 healthy controls (HC). The 33 patients with SLUs were divided into a reflux (15 patients) and a nonreflux group (18 patients). QFlow was done in the reflux, the nonreflux, and the HC. The stroke volume (SV), forward flow volume (FFV), absolute flow volume (AFV), mean flow (MF), and mean velocity (MV) were higher in the reflux than in the HC group in most segments, namely the external iliac vein (EIV), popliteal vein (PV), and great saphenous vein (GSV) (SV, p = 0.008; FFV, p = 0.008; absolute stroke volume (ASV), p = 0.008; MF, p = 0.002; MV, p = 0.009). No differences in the QFlow patterns were found in the GSV segment between the nonreflux group and the HC. Excellent performance in discriminating SLU with superficial venous reflux was reported for SV in the EIV and the PV (area under the curve (AUC) = 0.851 and 0.872), FFV in the EIV and PV (AUC = 0.854 and 0.869), ASV in the EIV and PV (AUC = 0.848 and 0.881), and MF in the EIV and PV (AUC = 0.866 and 0.868). The cutoff levels of SV/FFV/ASV/MF in the EIV/FV/PV/GSV for discriminating the SLU with superficial venous reflux were identified (p < 0.005). In conclusion, SLUs present different QFlow patterns by different etiology. The QFlow parameters of all vessel segments were higher in the morbid limbs of the reflux group than HC. The GSV segment of the nonreflux group displayed a pattern like the HC.

Using Non-Contrast MRA to Discriminate between Obstructive and Nonobstructive Venous Diseases of the Legs.

BACKGROUND: Venous interventions of the legs are less predictable owing to a lock of objective tools. METHODS: One hundred and twenty patients with lower extremity venous disease were evaluated anatomically using TRANCE MRI. Then, a QFlow analysis was performed in 53 patients with only one leg affected for hemodynamic evaluation. Those patients with complete QFlow were classified into obstructive and nonobstructive. RESULTS: The QFlow-namely, stroke volume, forward flow volume, mean flux, stroke distance (SD), and mean velocity (MV) in the external iliac vein (EIV), femoral vein (FV), popliteal vein (PV), and great saphenous vein (GSV). The obstructed group had a shorter SD and lower MV in the EIV, EIV/FV, and GSV/PV (SD: p-values of 0.025, 0.05, and 0.043, respectively; MV: p-values of 0.02, 0.05, and 0.048, respectively). A good performance in discriminating obstructive venous disease was reported for SD in the EIV (area under the curve (AUC) = 67.9%, 95% confidence interval (CI) = 53.2-82.7%), EIV/FV (AUC = 72.4%, 95% CI = 58.2-86.5%), and GSV/PV (AUC = 67.9%, 95% CI = 51.7-84.1%). The SD in the EIV, EIV/FV, and GSV/PV had the ability to discriminate between obstructive and nonobstructive diseases (p-values of 0.025, 0.005, and 0.043). The MV in the EIV, EIV/FV, and GSV/PV had ability to discriminate between obstructive and nonobstructive venous diseases (p-values of 0.02, 0.005, and 0.048). CONCLUSIONS: The SD and MV were lower for obstructive than nonobstructive disease in the EIV.