Diagnostic Pitfalls of the Bleeding Origin after a Percutaneous Renal Biopsy: A Report of Two Cases.

A percutaneous renal biopsy (PRB) is a standard procedure for diagnosing renal disease, but can cause bleeding complications. Bleeding after a PRB can be classified as early- or late-onset, depending on the timing of the onset of the bleeding symptoms (<24 h or ≥24 h). We herein report two patients who experienced bleeding complications: one experienced early-onset bleeding from the 12th subcostal artery, and the other experienced late-onset bleeding from an arteriovenous fistula between a branch of the renal artery and renal vein. In both cases, the origin of the bleeding vessel was misjudged during the first examination. We discuss the diagnostic pitfalls of the origin of bleeding after a PRB and propose measures to avoid falling such pitfalls.

Analysis of angiographic findings and short-term recurrence factors in patients presenting with hemoptysis.

OBJECTIVES: The abnormal anatomical alterations of blood vessels during DSA angiography in patients with hematological disorders were retrospectively examined, and the influencing factors of short-term (≤ 6 months) recurrent hemoptysis were statistically analyzed, and the consistency between admission diagnosis and intraoperative diagnosis was evaluated. METHODS: The intraoperative angiography data of patients who underwent selective bronchial artery embolization for hemoptysis in our hospital from January 2022 to December 2022 were reviewed. They were divided into the observation group and the control group based on whether there was recurrent hemoptysis. The Logistic regression model and forest map were employed to analyze the factors influencing the recurrence rate. RESULTS: A total of 104 patients were encompassed in this study (12 cases of tuberculosis, 35 cases of infection, 4 cases of lung cancer, 8 cases of bronchiectasis, 22 cases of arteriovenous fistula, 16 cases of aneurysm, and 7 cases of pulmonary hypertension). The coincidence rate of preoperative and intraoperative diagnoses was 73.1%. Pulmonary arteriovenous fistula and aneurysm were the predominant types of diseases that were misdiagnosed. The short-term recurrence rate was 16.3%, mainly attributed to the reopening of responsible vessels related to embolization, angiography leakage, and leaky embolization of specific types of vessels. The recurrence rate of only patients with arteriovenous fistula and aneurysm accounted for 47% of the total recurrence rate. The right bronchial artery, right internal thoracic artery, right thyroid neck trunk, and age were the independent factors influencing the recurrence of hemoptysis (p < 0.05). CONCLUSIONS: The main reason for angiographic leakage and embolization leakage in cases of hemoptysis is the lack of understanding of the anatomic variations of the vessels responsible. Careful examination of the specific types and locations of the vessels is the principal approach to reducing secondary operations.

Robotic spinal angiography: A single-center experience.

BACKGROUND AND OBJECTIVES: Robotic neurointervention enhances procedural precision, reduces radiation risk, and improves care access. Originally for interventional cardiology, the CorPath GRX platform has been used in neurointerventions. Recent studies highlight robotic cerebral angiography benefits, but information on spinal angiography is limited. While a new generation of robotic solutions is on the horizon, this series evaluates our experience with the CorPath GRX in spinal angiographic procedures, addressing a key gap in neurointerventional research. METHODS: In this single-center retrospective case series, we analyzed 11 patients who underwent robotic-assisted diagnostic procedures with the CorPath GRX system from February 2022 to March 2023 at our institution. A descriptive synthesis was performed on the demographic, baseline, surgical, and postoperative data collected. RESULTS: The average age of the 11 patients was 54 ± 20.34 years, with six (54.55%) female. The mean body mass index was 29.58 ± 7.86, and 7 (63.64%) were non-smokers. Of the 11 procedures using the CorPath GRX system, four (36.36%) were partially converted to manual technique. General anesthesia was used in nine cases (81.82%), and right-side femoral access in ten (90.91%) patients. Mean fluoroscopy time was 24.81 ± 10.19 min, contrast dose 174.09 ± 57.31 mL, dose area product 472.23 ± 437.57 Gy·cm², and air kerma 2438.84 ± 2107.06 mGy. No robot-related complications and minimal procedure-related complications were reported. CONCLUSION: The CorPath GRX system, a robotic-assisted platform, has proven reliable and safe in spinal angiography, evidenced by its enhanced procedural accuracy and reduced radiation exposure for operators.

Endovascular approaches for the treatment of dural carotid-cavernous fistulas: A systematic review.

INTRODUCTION: Dural carotid-cavernous fistulas (dCCFs), also known as indirect carotid-cavernous fistulas, represent abnormal connections between the arterial and venous systems within the cavernous sinus that are typically treated via endovascular approach. We aim to investigate the clinical characteristics of patients with dCCFs based on the endovascular treatment approach and assess angiographic and clinical outcomes. METHODS: A systematic review of the literature was performed. Data including number of patients, demographics, presenting clinical symptoms, etiology of fistula, Barrow classification, and embolization material were collected and evaluated. Outcome measures collected included degree of fistula occlusion, postoperative symptoms, complications, and mean follow-up time. RESULTS: A total of 52 studies were included examining four primary endovascular approaches for treating dCCFs: transarterial, transfemoral-transvenous (transpetrosal or other), transorbital (percutaneous or via cutdown), and direct transfacial access. Overall data was collected from 736 patients with 817 dCCFs. Transarterial approaches exhibit lower dCCF occlusion rates (75.6%) compared to transvenous techniques via the inferior petrosal sinus (88.1%). The transorbital approach via direct puncture or surgical cutdown offers a more direct path to the cavernous sinus, although with greater complications including risk of orbital hematoma. The direct transfacial vein approach, though limited, shows up to 100% occlusion rates and minimal complications. CONCLUSION: We provide a comprehensive review of four main endovascular approaches for dCCFs. In summary, available endovascular treatment options for dCCFs have expanded and provide effective solutions with generally favorable outcomes. While the choice of approach depends on individual patient factors and technique availability, traditional transvenous procedures have emerged as the first-line endovascular treatment. There is growing, favorable literature on direct transorbital and transfacial approaches; however, more studies directly comparing these general transvenous options are necessary to refine treatment strategies.

Apple Vision Pro Augmented Reality-Assisted Minimally Invasive Surgical Treatment of Spinal Dural Arteriovenous Fistula.

This report outlines the innovative use of augmented reality (AR) in the surgical planning and treatment of a spinal dural arteriovenous fistula (dAVF) via a minimally invasive technique. AR technology by way of an Apple Vision Pro headset was employed to enhance preoperative visualization and understanding of the pathology, leading to successful surgical ligation of the AVF. This case describes a 56-year-old male presenting with progressive weakness and thoracic myelopathy who showed marked improvement postoperatively, highlighting AR's potential to improve surgical approach and outcomes.

Beyond Conventional: A Systematic Review of Non-Conventional Techniques for Radio-Cephalic Arteriovenous Fistula.

BACKGROUND: Radio-cephalic arteriovenous fistulas (RC-AVFs), the preferred vascular access for hemodialysis, have high failure rates. New techniques like the no-touch technique (NTT) and modified no-touch technique (MNTT) have shown promising results. Our objective is to highlight the effectiveness of non-conventional techniques, aiming to address the challenge of AVF failure. METHODS: We searched Medline, Google Scholar, and Clinicaltrials.gov until April 2023, following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Five relevant articles were found, all involving human studies on NTT or MNTT for RC-AVF creation. We focused on primary and secondary patency rates, fistula maturation rates, and complications. RESULTS: We reviewed five studies: two pilot, two prospective, and one retrospective. Three used NTT, and two used MNTT. Among double-arm studies, three out of four showed a significantly improved primary patency with non-conventional techniques. However, one study found no significant difference between non-conventional and conventional methods (90.5% vs. 84.2%; p=0.225). In a single-arm study, non-conventional technique (NTT) displayed 54% primary patency at one year. Secondary patency rates were in three studies. One demonstrated significant secondary patency with non-conventional methods compared to conventional (90% vs. 67.5%; p=0.028), while another found no significant difference (90.5% vs. 84.2%; p=0.803). In the single-arm study, the non-conventional technique (NTT) revealed 80% secondary patency at one year. CONCLUSION: Non-conventional techniques (NTT and MNTT) show promise in improving patency rates, hinting at their potential as alternatives to the conventional technique for RC-AVF creation. Further studies are crucial to confirm their effectiveness and evaluate long-term outcomes.

Nephrectomy as Salvage Treatment After an Unsuccessful Embolization of a Huge Incidental Renal Artery Aneurysm With an Arteriovenous Fistula.

Renal artery aneurysms (RAA) with a concomitant renal arteriovenous fistula (RAVF) are rare entities with a reported incidence of less than 1%. An 86-year-old man was admitted to the urology department after an incidental finding of a left RAA on an abdominal ultrasound. A computed tomography angiography (CTA) revealed a saccular aneurysm measuring 54x42mm in the distal part of the left renal artery, along with a huge arteriovenous fistula measuring 45mm. The patient was asymptomatic at admission. Given the radiologic findings, an unsuccessful attempt at transcatheter arterial embolization was conducted. Therefore, a radical nephrectomy was recommended for the patient, which was performed without major intraoperative or postoperative complications. Microscopic examination depicted arteriosclerotic lesions and arterionephrosclerosis with 30% sclerotic glomeruli. The patient at his last visit remained free of symptoms. This case highlights the role of nephrectomy as a feasible option in cases of endovascular treatment failure.

Evaluation of multiple deep neural networks for detection of intracranial dural arteriovenous fistula on susceptibility weighted angiography imaging.

BACKGROUND: The natural history of intracranial dural arteriovenous fistula (DAVF) is variable and early diagnosis is crucial in order to positively impact the clinical course of aggressive DAVF. Artificial intelligence (AI) based techniques can be promising in this regard, and in this study, we used various deep neural network (DNN) architectures to determine whether DAVF could be reliably identified on susceptibility-weighted angiography images (SWAN). MATERIALS AND METHODS: A total of 3965 SWAN image slices from 30 digital subtraction angiographically proven DAVF patients and 4380 SWAN image slices from 40 age-matched patients with normal MRI findings as control group were included. The images were categorized as either DAVF or normal and the data was trained using various DNN such as VGG-16, EfficientNet-B0, and ResNet-50. RESULTS: Various DNN architectures showed the accuracy of 95.96% (VGG-16), 91.75% (EfficientNet-B0), and 86.23% (ResNet-50) on the SWAN image dataset. ROC analysis yielded an area under the curve of 0.796 (p < .001), best for VGG-16 model. Criterion of seven consecutive positive slices for DAVF diagnosis yielded a sensitivity of 74.68% with a specificity of 69.15%, while setting eight slices improved the sensitivity to above 80.38%, with a decrease of specificity up to 56.38%. Based on seven consecutive positive slices criteria, EfficientNet-B0 yielded a sensitivity of 73.21% with a specificity of 45.92% and ResNet-50 yielded a sensitivity of 72.39% with a specificity of 67.42%. CONCLUSION: This study shows that DNN can extract discriminative features of SWAN for the classification of DAVF from normal with good accuracy, reasonably good sensitivity and specificity.

An arteriovenous fistula model: Carotid artery-posterior facial vein fistula in rats.

OBJECTIVE: To describe an alternative arteriovenous fistula (AVF) model involving anastomosis of the common carotid artery (CCA) with the posterior facial vein (PFV). METHODS: Twenty-two male Sprague-Dawley rats (age 6-8 weeks) were used to establish the AVF model involving end-to-side anastomosis of PFV and CCA. The peak velocity of the CCA and the diameter of the outflow vein were recorded at 7, 14, and 42 days after the operation using Doppler ultrasound. Pathological examination of the intimal lesions was performed at 14 and 42 days after operation. RESULTS: One rat died within 24 h after surgery related to anesthesia. The patency rates at days 7, 14, and 42 were 85.7%, 81%, and 81%, respectively. The diameter of the carotid artery in rats is approximately 0.8 mm. The diameter of the outflow vein was increased by 1.7-fold and 2.2-fold at 7 days (1.1 ± 0.118 mm) and 14 days (1.4 ± 0.073 mm). At 42 days (1.96 ± 0.101 mm) after operation, the diameter was 3-fold greater compared to the unoperated control rat. The peak systolic flow velocity of the carotid artery at 7 days (593 ± 17.36 mm/s) and 14 days (767 ± 13.64 mm/s) after surgery was significantly greater compared to the control rat (314 ± 15.13 mm/s). The rate of increase was fastest at 7 days and leveled off from 14 to 42 days (875 ± 26 mm/s) after surgery. At 14 days, the intima area showed a nearly 50-fold increase (230 ± 9.93 µm2 × 103) compared to control (area 5 ± 0.37 µm2 × 103). Comparing 6 weeks with 2 weeks (280 ± 10.54 µm2 × 103) after surgery, the intima area increased 1.2 times. CONCLUSION: The CCA-PFV fistula in rats is a viable alternative AVF model.

Convexity dural arteriovenous fistula with Sylvian-Labbé collateral pattern: A case report.

Convexity dural arteriovenous fistula (dAVF) is associated with high-grade dAVF and is usually presented with aggressive clinical presentation. Precise diagnosis and understanding the pathogenesis are important to achieving successful treatment without complications. We report a case of dAVF with Sylvian-Labbé collateral pattern, concerning embryological development that was thought to be involved in the vascular architecture and pathogenesis of dural AVF. Thus, a 60-year-old man was presented with sudden onset of seizure with no history of trauma. Magnetic Resonance Imaging (MRI) showed cortical hemorrhage in the left precentral gyrus. Digital subtraction angiography (DSA) showed the convexity dural arteriovenous fistula (dAVF) involving a vein that appeared to be the vein of Labbé, the drainer was anastomosed with superior middle cerebral vein (SMCV) and formed the varix. With the successful treatment with trans-arterial embolization (TAE), obliteration of dAVF was achieved with no neurological deficits. This case highlights convexity dAVF with the complex relationship between embryological development and the arcade of venous drainage route, wherein the anomaly might be acquired and caused by elevated venous pressure in a vein that appeared to be the vein of Labbé. Gaining knowledge of the embryological basis may aid in a deeper understanding of acquired pathologies.

Construction and validation of a scale to assess knowledge, attitude, and practice regarding vascular protection anticipatory to the creation of an arteriovenous fistula.

BACKGROUND: The possibility of creating an arteriovenous fistula (AVF) depends on the existence of an arterial-venous network that is in good condition, defined by the size and elasticity of the blood vessels. The knowledge, attitudes, and practices (KAP) toward vascular protection play a crucial role in preserving the vascular network for patients with end-stage renal disease (ESRD), it is observed that there is a significant lack of tools to measure these variables. Thus, the aim of this study is to develop and validate a scale to assess KAP regarding vascular protection anticipatory to the creation of an arteriovenous fistula (the KAP-VPAC-AVF Scale). METHODS: Initial item development was guided by a literature review and clinical experience, after which the items were improved and perfected through the Delphi process. The content of the scale was judged by an expert panel for content validity. In a convenience sample of 551 patients with ESRD, exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) were conducted to examine the instrument's factor structure. RESULTS: The KAP-VPAC-AVF Scale encompasses 11 items distributed over three factors: knowledge, attitude, and practice, demonstrated excellent internal consistency (Cronbach's alpha = 0.917) and construct validity, as confirmed by CFA with satisfactory fit indices (χ2/df = 2.394, RMSEA = 0.075, RMR = 0.049, CFI = 0.969, GFI = 0.936, AGFI = 0.892, TLI = 0.957, IFI = 0.970). CONCLUSION: The KAP-VPAC-AVF Scale is a scientific and effective assessment tool that can evaluate the KAP of ESRD patients regarding measures to preserve the vascular network.

Ultrasound-guided nitinol stent implantation to treat early restenosis of arteriovenous fistula: A 69-case study with 1-year outcome.

BACKGROUND: To investigate the feasibility, methods and effects of interventional ultrasound in nitinol stent implantation to treat early restenosis after percutaneous transluminal angioplasty (PTA) in autogenous arteriovenous fistula (AVF). METHODS: From April 2018 to December 2021, 69 patients with early restenosis of AVF received ultrasound-guided nitinol stent implantation (UNSI) and were followed-up. Imaging features of the stent and procedure by ultrasound were observed. The technical success rate, clinical success rate and incidence of complications were recorded and counted. Target lesion primary patency (TLPP), access circuit primary patency (ACPP) and access circuit secondary patency (ACSP) were estimated. RESULTS: Ultrasonography can show the structure of the stent and guide the stenting process clearly. Both the technical and clinical success rates were 100%. Thirty-one patients had in-stent restenosis (ISR), which was treated by plain balloon (PB) PTA or drug coated balloon (DCB) PTA. The TLPP at 3, 6, 12 and 24 months were 100.0%, 94.2%, 63.4% and 39.6%, respectively. The ACPP at 3, 6, 12 and 24 months were 98.6%, 91.6%, 60.2% and 35.2%, respectively. The ACSP at 3, 6, 12 and 24 months were 98.6%, 98.6%, 95.6% and 93.8%, respectively. The TLPP of ISR after DCB PTA at 3, 6 and 12 months were 100.0%, 100.0% and 93.6%, respectively. CONCLUSIONS: This pilot study indicates ultrasonography can accurately guide nitinol stent implantation in AVF and this technique is a feasible and minimally invasive treatment for early restenosis after PTA with good short- and medium-term patency. DCB PTA may be used to deal with the ISR and is a way to prolong the patency of nitinol stent.

Grouting technique-combining transvenous Onyx and coils for the embolization of complex non-cavernous intracranial dural arteriovenous fistulas.

Objective: Incomplete occlusion of cerebral dural arteriovenous fistula (DAVF) may lead to fistula recurrence and rebleeding, which may necessitate several embolizations and lead to worse clinical outcomes. Herein, we describe a grouting technique for endovascular embolization and its outcomes in a series of patients with complex intracranial DAVF. Methods: A total of 20 patients with aggressive type or symptomatic intracranial non-cavernous DAVF underwent endovascular transvenous embolization combining detachable coils and Onyx. Two microcatheters were positioned either in the distal segment of the involved sinus or near the draining veins. To achieve tight occlusion of the involved sinus, coils were carefully delivered through the first microcatheter, starting from the distal segment and then to the proximal segment. Next, Onyx was injected through the second microcatheter to reinforce and fill (grout) the interspace of coil mass and gradually refluxed to the mural channels and para-sinus cortical veins until the fistula was completely occluded. Results: Successful embolization was achieved in all 20 patients. The initial angiographic results revealed the achievement of complete occlusion in 19 patients (95%). At the postembolization follow-up, complete obliteration of the fistula was achieved in all patients (100%). No symptom or angiographic recurrence was observed at the 2- to 5-year follow-ups. No patient required additional embolization or stereotactic radiosurgery. Conclusion: The proposed grouting technique combining detachable coils and Onyx appears to be promising for the elimination of complex intracranial non-cavernous DAVFs.

A Case of Traumatic Splenic Arteriovenous Fistula Treated by Transcatheter Arterial Embolization.

Transcatheter arterial embolization (TAE) has increasingly replaced surgery for treating solid organ injuries, including the spleen, due to its minimally invasive approach. Studies show only a 3% splenectomy rate after TAE, despite a 10% incidence of missed vascular injuries in the American Association for the Surgery of Trauma (AAST) grade III splenic injuries on initial computed tomography (CT) scans. However, there's a lack of high-quality studies recommending specific CT follow-up intervals after non-operative management (NOM) of splenic injuries or guidelines for initiating treatment in cases of pseudoaneurysms or arteriovenous fistulas (AVFs). Here, we discuss the case of a 44-year-old man who presented with a splenic injury due to a motor vehicle accident. The splenic injury was AAST-spleen grade III, but because there was no evidence of extravascular leakage or AVF formation, NOM was selected. CT on the fifth day showed a pseudoaneurysm and an AVF, for which TAE was performed on the seventh day, preserving most of the parenchyma of the spleen with no complications. The indications for NOM as a treatment strategy for splenic injury are expanding, but since the 2018 revision of the AAST grading, the grade changes depending on the presence or absence of vascular injury, but in some cases, it is difficult to determine the presence or absence of active bleeding by CT findings. In fact, it has been reported that more than 25% of vascular lesions do not show up on CT, although CT has good sensitivity in detecting active bleeding, and the rate of NOM failure is higher in AAST grade III and above, so early angiography is likely to be useful. Splenic AVF may present with few symptoms in the early stages but may present with extrahepatic portal hypertension in the late stages, and patients may present to the hospital with symptoms such as abdominal pain and diarrhea. TAE is often the treatment of choice in traumatic cases, and the extent of embolization is important in the balance between preserving splenic function and completing treatment. The shift towards conservative management of splenic trauma may increase the occurrence of splenic AVFs. Transcatheter coil embolization of segmental branches has been effective in treating posttraumatic splenic AVFs, preserving splenic immune function and reducing risks linked to surgery and splenectomy.

Endovascular comprehensive treatment of post-traumatic superior mesenteric arteriovenous fistula: case report and literature review.

Background: Superior mesenteric arteriovenous fistula is a rare and difficult complication after abdominal trauma. Utilizing comprehensive endovascular treatment represents an effective approach to managing this condition. Case presentation: We report a case involving a 53-year-old female with a history of trauma who presented with complaints of abdominal pain, malaise, and melena. A computed tomographic scan revealed the presence of a superior mesenteric arteriovenous fistula. The fistula was occluded using four Interlock detachable coils, and a covered stent was positioned over the arteriovenous fistula in the superior mesenteric artery. Following endovascular treatment, the patient's abdominal pain and melena symptoms disappeared. Conclusion: Utilizing covered stents and Interlock detachable coils for endovascular treatment of a superior mesenteric arteriovenous fistula proves to be both feasible and highly effective.

Successful treatment by coil embolization for pediatric brachial arteriovenous fistula: A case report.

Arteriovenous fistulae of the upper limbs are rare in the pediatric population. They can be caused by trauma, needle puncture, or other iatrogenic injuries. A 5-year-old boy presented with progressive swelling of the right hand, which was initially misinterpreted as an arteriovenous malformation based on his noninvasive diagnostic work-up. He was ultimately diagnosed with right brachiocephalic arteriovenous fistula by catheter angiography, and the fistula was then successfully treated with coil embolization. This article describes the relevant imaging findings and potential implications for treatment.

Type 2 diabetes increase the risk of arteriovenous fistula non-maturation, mediated by postoperative vascular hemodynamics.

BACKGROUND: The progression of atherosclerosis in small and medium-sized vessels has been associated with Type 2 diabetes (T2D). However, the influence of T2D on postoperative vascular remodeling and arteriovenous fistula (AVF) maturation is inconclusive. Besides, hemodynamic changes of postoperative vessel are also associated with AVF maturation. This study is intended to investigate the link between T2D and the occurrence of AVF non-maturation, as well as to delve into the impact of postoperative vascular hemodynamic parameters in this process. METHODS: A total of 477 hemodialysis patients, with or without type 2 diabetes, underwent AVF creation at Beijing Haidian Hospital (Haidian Section of Pecking University Third Hospital) from August 2018 to March 2022 were collected, and were followed for 1-5 years. Logistic regression was applied to analyze the association of T2D, postoperative vascular hemodynamic parameters with the risk of AVF non-maturation. To verify the stability of the results, the sensitivity analyses were performed using propensity scores to match patients. We further investigated the regulatory role of the postoperative vascular hemodynamics. RESULTS: There were 173 patients with T2D and 304 patients without T2D in this study. The maturation rate in T2D and non-T2D group was 47.977% and 63.816%, respectively. The findings of logistic regression analysis suggested that T2D significantly increased the risk of AVF immaturity [OR 1.716 (1.019-2.890), P = 0.042]. Besides, T2D was associated with the restriction of postoperative vascular hemodynamic parameters changes, including with decreased diameter of forearm cephalic radial artery and dilation rate of radial artery. The result of logistic regression analysis indicated that cephalic vein diameter at 1-month [0.402 (0.237-0.681), P = 0.001] and cephalic vein diameter at 2-month [0.501 (0.355-0.708), P < 0.001] were independently correlated with AVF maturation. Besides, the results of sensitivity analysis were consistent with that of logistic regression analysis. Moreover, the mediating effects of cephalic vein diameter were significant. CONCLUSION: Our findings discovered that T2D significantly increased the risk of arteriovenous fistula non-maturation, which was mainly mediated by the changes of cephalic vein diameter.

The "Hypointense Focal Brain" on susceptibility-weighted imaging as a sign of venous congestion in cranial dural arteriovenous fistulas.

BACKGROUND: Cranial dural arteriovenous fistulas (dAVFs) are complex neurovascular malformations accounting for approximately 10%-15% of all intracranial arteriovenous malformations. The objective is to investigate the utility of susceptibility-weighted imaging (SWI) in identifying "hypointense focal brain" as an additional helpful sign of venous congestion in cranial dAVFs. MATERIALS AND METHODS: A retrospective review of patients diagnosed with cranial dAVFs between January 2015 and June 2023 was conducted, and SWI was used to identify the "hypointense focal brain" sign within the venous drainage region of the dAVF. The "hypointense focal brain" on SWI was identified as a low-intensity signal within the venous drainage region, indicative of venous congestion. The presence of this imaging sign was assessed by two neuroradiologists and signal intensity measurements were performed to support the presence of the sign. RESULTS: The study included six patients with cranial dAVFs exhibiting cortical venous retrograde drainage and the "hypointense focal brain" on SWI. Follow-up imaging post-treatment revealed resolution or improvement of the hypointense signal, confirming its association with venous congestion. Signal intensity measurements further supported the presence of this imaging sign in pre-treatment scans. CONCLUSION: The study's findings demonstrate the presence of a reversible "hypointense focal brain" sign on SWI in patients with cranial dAVFs and CVR, which can be useful as an additional imaging sign for venous congestion.

Computational model-based hemodynamic comparisons of traditional and modified idealized models of autologous radiocephalic fistula.

Autologous arteriovenous fistula (AVF) is a commonly used vascular access (VA) for hemodialysis, and hemodynamic changes are one of the main factors for its failure. To explore the effect of geometry on the hemodynamics in the AVF, a modified model is built with a gradual and smooth turn at the anastomosis and is compared with the traditional model, which has an abrupt sharp turn at the anastomisis. Transient computational fluid dynamics (CFD) simulations were performed for the comparison and analysis of the hemodynamic fields of the two models at different stages of the pulse cycle. The results showed that the low shear stress region and high oscillatory shear stress region in the modified AVF model coincided with regions of intimal hyperplasia that have been identified by previous studies. A comparison with the blood flow velocities measured in vivo was performed, and the error between the simulation results and the medical data was reduced by 22% in the modified model, which verifies the rationality and utility of the modified model.