Identifying problematic arteriovenous fistula with CFD-derived resistance: An exploratory study.

Arteriovenous fistula (AVF) is the optimal form of vascular access for most haemodialysis dependant patients; however, it is prone to the formation of stenoses that compromise utility and longevity. Whilst there are many factors influencing the development of these stenoses, pathological flow-related phenomena may also incite the formation of intimal hyperplasia, and hence a stenosis. Repeated CFD-derived resistance was calculated for six patient who had a radiocephalic AVF, treated with an interwoven nitinol stent around the juxta-anastomotic region to address access dysfunction. A three-dimensional freehand ultrasound system was used to obtain patient-specific flow profiles and geometries, before performing CFD simulations to replicate the flow phenomena in the AVF, which enabled the calculation of CFD-derived resistance. We presented six patient cases who were examined before and after treatment and our results showed a 77% decrease in resistance, recorded after a surgical intervention to address access dysfunction. Problematic AVFs were found to have high resistance, particularly in the venous segment. AVFs with no reported clinical problems, and clinical patency, had low resistance in the venous segment. There did not appear to be any relationship with clinical problems/patency and resistance values in the arterial segment. Identifying changes in resistance along the circuit allowed stenoses to be identified, independent to that determined using standard sonographic criteria. Our exploratory study reveals thatCFD-derived resistance is a promising metric that allows for non-invasive identification of diseased AVFs. The pipeline analysis enabled regular surveillance of AVF to be studied to aid with surgical planning and outcome, further exhibiting its clinical utility.

32-year-old Traumatic Arteriovenous Fistula Presenting With Leg Ulcer and High-output Heart Failure.

Traumatic arteriovenous fistula (AVF) is not a common disorder, and dermatological signs and heart failure caused by AVF are rarely reported. We present the case of a 55-year-old woman who was referred for congestive heart failure symptoms. Echocardiography revealed preserved left ventricular ejection fraction. Due to edema of the right leg with a long-standing leg ulcer and palpable femoral thrill, duplex ultrasonography was performed. It showed an AVF between the right superficial femoral artery (SFA) and the right femoral vein (FV). The patient recalled a 32-year-old gunshot injury that was not medically treated. After the diagnosis of AVF she was referred to a surgeon for an AVF ligation, with subsequent resolution of her symptoms. The differential diagnosis of leg ulcer with leg edema should include the possibility of AVF as a cause.

Traumatic Iliac Arteriovenous Fistula Treated With the Amplatzer Vascular Plug II: A Case Report and Literature Review.

Traumatic iliac arteriovenous fistula is a rare complication of vascular injury. Open surgical repair has an incidence of postoperative complications. In recent years, endovascular treatment has shown better efficacy. We report a 62-year-old female AVF patient with a stab injury history of more than 16 years. Computed tomography angiography (CTA) revealed a large arteriovenous fistula between the right internal iliac artery and the common iliac vein. After considering the patient's relevant conditions, an endovascular approach was satisfactorily performed with the implantation of an Amplatzer Vascular Plug II to interrupt the abnormal vascular communication and maintain arterial and venous patency. The final control images showed closure of the arteriovenous communication.

Arterial Spin Labeling for the Etiological Workup of Intracerebral Hemorrhage in Children.

BACKGROUND AND PURPOSE: Pediatric nontraumatic intracerebral hemorrhage accounts for half of stroke in children. Early diagnostic of the causative underlying lesion is the first step toward prevention of hemorrhagic recurrence. We aimed to investigate the performance of arterial spin labeling sequence (ASL) in the acute phase etiological workup for the detection of an arteriovenous shunt (AVS: including malformation and fistula), the most frequent cause of pediatric nontraumatic intracerebral hemorrhage. METHODS: Children with a pediatric nontraumatic intracerebral hemorrhage between 2011 and 2019 enrolled in a prospective registry were retrospectively included if they had undergone ASL-magnetic resonance imaging before any etiological treatment. ASL sequences were reviewed using cerebral blood flow maps by 2 raters for the presence of an AVS. The diagnostic performance of ASL was compared with admission computed tomography angiography, other magnetic resonance imaging sequences including contrast-enhanced sequences and subsequent digital subtraction angiography. RESULTS: A total of 121 patients with pediatric nontraumatic intracerebral hemorrhage were included (median age, 9.9 [interquartile range, 5.8-13]; male sex 48.8%) of whom 76 (63%) had a final diagnosis of AVS. Using digital subtraction angiography as an intermediate reference, visual ASL inspection had a sensitivity and a specificity of, respectively, 95.9% (95% CI, 88.5%-99.1%) and 79.0% (95% CI, 54.4%-94.0%). ASL had a sensitivity, specificity, and accuracy of 90.2%, 97.2%, and 92.5%, respectively for the detection of the presence of an AVS, with near perfect interrater agreement (κ=0.963 [95% CI, 0.912-1.0]). The performance of ASL alone was higher than that of other magnetic resonance imaging sequences, individually or combined, and higher than that of computed tomography angiography. CONCLUSIONS: ASL has strong diagnostic performance for the detection of AVS in the initial workup of intracerebral hemorrhage in children. If our findings are confirmed in other settings, ASL may be a helpful diagnostic imaging modality for patients with pediatric nontraumatic intracerebral hemorrhage. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifiers: 3618210420, 2217698.

Splenic Arteriovenous Fistula Accompanied by Splenic Artery Aneurysm Associated with Acute-onset Portal Hypertension and Gastrointestinal Bleeding: Case Report and Literature Review.

Splenic arteriovenous fistula is an uncommon aetiology of portal hypertension, which has definitive treatment effectiveness and good prognosis. We report a case of portal hypertension and gastrointestinal bleeding in the absence of hepatic parenchymal disease in a 50 year-old woman with multiple pregnancies. Abdominal computed tomography and transabdominal arteriography recorded the presence of tortuous and aneurysmal splenic arteries and the premature filling of enlarged splenic veins, which are highly suggestive of splenic arteriovenous fistula. The above vascular abnormalities were successfully treated by transcatheter embolization. No recurrence or other complications were observed. In addition, a literature review concerning splenic arteriovenous fistula published in recent 30 years was performed to further our understanding of the management strategy on this entity.

Computational modeling of the cephalic arch predicts hemodynamic profiles in patients with brachiocephalic fistula access receiving hemodialysis.

BACKGROUND: The most common configuration for arteriovenous fistula is brachiocephalic which often develop cephalic arch stenosis leading to the need for numerous procedures to maintain access patency. The hemodynamics that contributes to the development of cephalic arch stenosis is incompletely understood given the inability to accurately determine shear stress in the cephalic arch. In the current investigation our aim was to determine pressure, velocity and wall shear stress profiles in the cephalic arch in 3D using computational modeling as tools to understand stenosis. METHODS: Five subjects with brachiocephalic fistula access had protocol labs, Doppler, venogram and intravascular ultrasound imaging performed at 3 and 12 months. 3D reconstructions of the cephalic arch were generated by combining intravascular ultrasounds and venograms. Standard finite element analysis software was used to simulate time dependent blood flow in the cephalic arch with velocity, pressure and wall shear stress profiles generated. RESULTS: Our models generated from imaging and flow measurements at 3 and 12 months offer snapshots of the patient's cephalic arch at a precise time point, although the remodeling of the vessel downstream of an arteriovenous fistula in patients undergoing regular dialysis is a dynamic process that persists over long periods of time (~ 5 years). The velocity and pressure increase at the cephalic bend cause abnormal hemodynamics most prominent along the inner wall of the terminal cephalic arch. The topology of the cephalic arch is highly variable between subjects and predictive of pathologic stenosis at later time points. CONCLUSIONS: Low flow velocity and wall pressure along the inner wall of the bend may provide possible nidus of endothelial activation that leads to stenosis and thrombosis. In addition, 3D modelling of the arch can indicate areas of stenosis that may be missed by venograms alone. Computational modeling reconstructed from 3D radiologic imaging and Doppler flow provides important insights into the hemodynamics of blood flow in arteriovenous fistula. This technique could be used in future studies to determine optimal flow to prevent endothelial damage for patients with arteriovenous fistula access.

Long-term prognosis of vascular access in hemodialysis patients with systemic lupus erythematosus: a retrospective cohort study.

Patients with systemic lupus erythematosus (SLE) have a higher risk of vascular complications. This retrospective cohort study aimed to analyze the differences in the risk of arteriovenous fistula or graft (AVF/AVG) dysfunction in hemodialysis patients with and without SLE from Taiwan's National Health Insurance Database over a 10-year period. AVF/AVG dysfunction is defined as the occurrence of the first episode of intervention after vascular access creation. A total of 1366 HD patients with SLE had higher incidence rates of AVF/AVG dysfunction than 4098 non-SLE HD patients in the following 4 periods: (1) after 1 year (incidence rates = 15.21% and 13.01%, respectively; subdistribution hazard ratio (SHR) = 1.16; P = 0.007), (2) 1st-to-10th-year period (15.36% and 13.25%; SHR = 1.16; P = 0.007), (3) 5th-to-10th-year period (11.91% and 8.1%; SHR = 1.42; P = 0.003), and (4) overall period (23.53% and 21.66%; SHR = 1.09; P = 0.027). In conclusion, there were significantly higher incidence rates of AVF/AVG dysfunction in SLE patients during the long-term follow-up period. Vascular access function should be monitored regularly by clinical examinations, especially after 1 year and during 5 to 10 years, to improve AVF/AVG patency and dialysis adequacy in SLE patients undergoing maintenance hemodialysis.

Rare Etiology of Ischemic Steal Syndrome in the Left Peroneal Artery.

Ischemic steal syndrome (ISS) secondary to an arteriovenous fistula (AVF) in the lower extremity (LE) is a rare occurrence. Herein, we report a case of symptomatic ISS in an adult male due to an iatrogenic AVF in the left LE, which was surgically repaired by placing an arterial stent across the acquired AVF of the peroneal artery to the peroneal vein.

True Aneurysms of Foot Arteries: A Case Report of a Young Patient.

BACKGROUND: Reports of true aneurysms of the lower leg are rare. Among them, cases involving young patients are all the more rare, and there are many unexplored aspects to this pathological condition. CASE PRESENTATION: This is a case of a 30-year-old woman who was referred by an orthopedic surgeon with a chief complaint of severe pain during walking and landing. Angiography revealed multiple aneurysms and arteriovenous fistulas in the posterior tibial artery and lateral plantar artery. We anastomosed the lateral plantar artery and interposed the posterior tibial artery using the great saphenous vein. CONCLUSIONS: Although aneurysms in the arteries of the feet are rare, multiple true arterial aneurysms were observed in the lower leg of a juvenile patient in the present case. Dilation of arteries other than the aneurysm was also observed, suggesting that arteriovenous fistula and arterial occlusion may have been the causes of the true aneurysm of the lower leg. This is a valuable finding, suggesting a cause of aneurysm other than age-related atherosclerotic changes.

De Novo Dural Arteriovenous Fistula on Draining Veins of Previously Treated Pial Arteriovenous Malformation: a Case Report.

A 71-year-old man, with a pial micro-arteriovenous malformation (pAVM) draining into the confluence of the vein of Trolard and the vein of Labbé was surgically removed, sparing these cortical veins. 4-months MR and angiographic controls showed a de novo dural arteriovenous fistula (dAVF) draining into the previously spared cortical veins. It was removed using intraoperative motor evoked potentials (MEP). This is the first case of iatrogenic dAVF developing on the same draining vein of a previously treated pAVM. De novo dAVFs are generally iatrogenic. This case suggests that the unresected venous drainage of an AVM might be the substratum for neo-angiogenetic processes; moreover inflammation related to surgery might be the trigger factor for the development of the dAVF.

Possible Association Between Rupture and Intranidal Microhemodynamics in Arteriovenous Malformations: Phase-Contrast Magnetic Resonance Angiography-Based Flow Quantification.

OBJECTIVE: To examine a potential association between intranidal microhemodynamics and rupture using a phase-contrast magnetic resonance angiography (PCMRA)-based flow quantification technique in arteriovenous malformations (AVMs). METHODS: We retrospectively collected data on 30 consecutive patients with AVMs (23 unruptured and 7 ruptured). Based on PCMRA data, maximal (Vmax) and mean (Vmean) intranidal velocities were calculated. Logistic regression analysis was performed to assess factors associated with previous AVM rupture. RESULTS: All ruptures occurred within 6 months before PCMRA. The mean nidus volume was 4.7 mL. Eleven patients (37%) had deep draining vein(s), and 6 patients (20%) had a deep-seated nidus. The mean ± standard deviation Vmean and Vmax were 9.6 ± 2.8 cm/second and 66.7 ± 26.2 cm/second, respectively. The logistic regression analyses revealed that higher Vmax (P = 0.075, unit odds ratio [OR] = 1.05, 95% confidence interval [95% CI] = 1.00-1.10) was significantly associated with prior hemorrhage. The receiver-operating curve analyses demonstrated that a Vmean of 10.8 cm/second (area under the curve = 0.671) and Vmax of 90.2 cm/second (area under the curve = 0.764) maximized the Youden Index. A Vmax > 90 cm/second was significantly associated with AVM rupture both in the univariate (P = 0.025, OR = 9.0, 95% CI = 1.3-61.1) and multivariate (P = 0.008, OR = 51.7, 95% CI = 2.8-968.3) analyses. CONCLUSIONS: Presence of faster velocities in intranidal vessels may suggest aberrant microhemodynamics and thus be associated with AVM rupture. PCMRA-based velocimetry seems to be a promising tool to predict future AVM rupture.

Angioaccesos para hemodiálisis en el trasplante renal: implicaciones hemodinámicas sobre el corazón izquierdo / Angioaccess for hemodialysis in kidney transplantation: hemodynamic implications for the left heart

Las complicaciones cardiovasculares representan la principal causa de morbilidad y mortalidad en pacientes con enfermedad renal crónica, por lo que el objetivo de este artículo es demostrar la influencia de la permanencia de la fístula arteriovenosa sobre variables eco cardiográficamente mensuradas en el corazón izquierdo. Para ello, se definió un estudio multivariable, longitudinal, prospectivo y controlado de grupos independientes después de una intervención que incluyó 39 pacientes a los que se le cerró el angioacceso (grupo de estudio) y 42 que no fueron expuestos a la cirugía (grupo control). Ambos grupos exhibían trasplante renal funcionante. Los principales resultados surgenal comparar el predominio entre el grupo de estudio con el de control, la edad promedio; 45,6 y 44,1 años, el sexo masculino, 24 (60%) y 23 (53,5%) y el color de la piel blanca; 33 (82,5%) y 32 (74,4%). La etiología de la nefropatía originaria más frecuente fue la nefropatía vascular hipertensiva; 12 (30%) vs 14 (32,6%). Entre las manifestaciones clínicas, en el grupo de estudio se evidenció remisión de las palpitaciones y la disnea de esfuerzo. Respecto a la tensión arterial, para la sistólica oscilaba; de 123 ±13,4 a 120,5 ±9,2 vs de 125,6 ±8,4 a 128 ±8,3 mm Hg (p= 0,000), mientras la diastólica variaba de; 76,8 ±7,5 a 76,3 ±6,2 vs 78,6 ±4,9 a 82,4 ±3,9 mm Hg (p= 0,000). El hematocrito comportaba valores equivalentes; 0,43 ±0,06 y 0,45 ±0,06 vs 0,42 ±0,05 y 0,42 ±0,06 l/l (p= 0,035) y la creatinina sérica mostró descenso en los pacientes intervenidos de; 106,8 ± 26,2 hasta 99,8 ±23,9 µ Mol/l vs 114 ±27,8 a 120,3 ±31 µ Mol/l (p= 0,002). Las variables ecocardiográficas mensuradas comparativamente según la localización de los angioaccesos a nivel del codo izquierdo; diámetro del ventrículo izquierdo: 3,12 ±4,08 vs 1,48 ±3,46 mms (p=0,001), fracción de eyección del ventrículo izquierdo: 2,99 ±5,47 vs -1,98 ±6,23 % (p=0,018) y el volumen telediastólico: -23 ±33,41 vs 10,86 ±36,87 ml (p=0,006). El codo contralateral revelaba; para la fracción de eyección del ventrículo izquierdo: 3,32 ±3,42 vs -2,18 ±4,78 % (p=0,037) y para el gasto cardíaco: -1,29 ±0,88 vs -0,26 ±0,86 l/min (0,020). Las conclusiones demuestran que el cierre del angioacceso a pacientes con trasplante renal funcionante respecto a los no intervenidos, contribuye a la regresión de las alteraciones morfológicas y hemodinámicas constatadas por ecocardiografía transtorácica en el corazón izquierdo a nivel de las diferentes localizaciones de los accesos vasculares.

Cardiovascular complications represent the main cause of morbidity and mortality in patients with chronic renal disease, so the objective of this article is to demonstrate the influence of the patency of the arteriovenous fistula on echocardiographic variables measured in the left heart. For this, a multivariate study, longitudinal, prospective and controlled study of independent groups after an intervention that included 39 patients who had their angioaccess closed (study group) and 42 who were not exposed to surgery (control group). Both groups exhibited functional kidney transplantation. The main results emerge when comparing the prevalence between the study group and the control group, the average age; 45.6 and 44.1 years, the male sex, 24 (60%) and 23 (53.5%) and the white skin color; 33 (82.5%) and 32 (74.4%). The most frequent etiology of the original nephropathy was hypertensive vascular nephropathy; 12 (30%) vs 14 (32.6%). Among the clinical manifestations, remission of palpitations and dyspnea on exertion were evidenced in the study group. With regard to blood pressure, for the systolic it ranged from 123 ±13.4 to 120.5 ±9.2 vs. 125.6 ±8.4 to 128 ±8.3 mmHg (p= 0.000), while the diastolic varied from; 76.8 ±7.5 to 76.3 ±6.2 vs. 78.6 ±4.9 to 82.4 ±3.9 mmHg (p= 0.000). The hematocrit had equivalent values; 0.43 ±0.06 and 0.45 ±0.06 vs 0.42 ±0.05 and 0.42 ±0.06 l/l (p= 0.035) and the serum creatinine showed decrease in the operated patients from; 106.8 ±26.2 to 99.8 ±23.9 µMol/l vs 114 ±27.8 to 120.3 ±31 µMol/l (p= 0.002). The echocardiographic variables measured comparatively according to the location of the angioaccesses at the left elbow level; diameter of the left ventricle: 3.12 ±4.08 vs 1.48 ±3.46 mms (p=0.001), ejection fraction of the left ventricle: 2.99 ±5.47 vs -1.98 ±6.23 % (p=0.018) and the telediasolic volume: -23 ±33.41 vs 10.86 ±36.87 ml (p=0.006). The contralateral elbow revealed; for the left ventricular ejection fraction: 3.32 ±3.42 vs -2.18 ±4.78 % (p=0.037) and for cardiac output: -1.29 ±0.88 vs -0.26 ±0.86 l/min (0.020). The conclusions show that the our study has shown that closing the angioaccess to patients with functioning renal transplants with respect to those not operated, contributes to the regression of morphological and hemodynamic alterations observed by transthoracic echocardiography in the left heart at the different locations of the vascular accesses.

How to Reduce the Risk of Arteriovenous Fistula Dysfunction by Observing Prepump Arterial Pressure during Hemodialysis: A Multicenter Retrospective Study.

OBJECTIVE: Prepump arterial (Pa) pressure indicates the ease or difficulty with which the blood pump can draw blood from the vascular access (VA) during hemodialysis. Some studies have suggested that the absolute value of the Pa pressure to the extracorporeal blood pump flow (Qb) ratio set on the machine (|Pa/Qb|) can reflect the dysfunction of VA. This study was conducted to explore the impact of arteriovenous fistula (AVF) dysfunction and to explore the clinical reference value of |Pa/Qb|. METHODS: We retrospectively identified adults who underwent hemodialysis at 3 hospitals. Data were acquired from electronic health records. We evaluated the pattern of the association between |Pa/Qb| and AVF dysfunction during 1 year using a Cox proportional hazards regression model with restricted cubic splines. Then, the patients were grouped based on the results, and hazard ratios were compared for different intervals of |Pa/Qb|. RESULTS: A total of 490 patients were analyzed, with an average age of 55 (44, 66) years. There were a total of 85 cases of AVF dysfunction, of which 50 cases were stenosis and 35 cases were thrombosis. There was a U-shaped association between |Pa/Qb| and the risk of AVF dysfunction (p for nonlinearity <0.001). |Pa/Qb| values <0.30 and >0.52 increased the risk of AVF dysfunction. Compared with the group with a |Pa/Qb| value between 0.30 and 0.52, the groups with |Pa/Qb| <0.30 and |Pa/Qb| >0.52 had a 4.04-fold (p = 0.002) and 3.41-fold (p < 0.001) greater risk of AVF dysfunction, respectively. CONCLUSIONS: The appropriate range of |Pa/Qb| is between 0.30 and 0.52. When |Pa/Qb| is <0.30 or >0.52, the patient's AVF function or Qb setting should be reevaluated to prevent subsequent failure.

Complete flow control using transient concurrent rapid ventricular pacing or intravenous adenosine and afferent arterial balloon occlusion during transvenous embolization of cerebral arteriovenous malformations: case series.

BACKGROUND: There are no reports that describe complete flow control using concurrent transient rapid ventricular pacing or intravenous (IV) adenosine and afferent arterial balloon flow arrest to aid transvenous embolization of cerebral arteriovenous malformations (AVM). We describe our experience with the use of this technique in patients undergoing transvenous AVM embolization. METHODS: Consecutive patients in whom transvenous embolization was attempted at our institute between January 2017 and July 2019 were included. Anatomical AVM features, number of embolization stages, technique of concurrent transient rapid ventricular pacing and afferent arterial balloon flow arrest, complications, and clinical and radiological outcomes were recorded and tabulated. RESULTS: Transvenous AVM embolization was attempted in 12 patients but abandoned in two patients for technical reasons. Complete embolization was achieved in 10 patients, five of whom had infratentorial AVMs. All 10 had a single primary draining vein. Rapid ventricular pacing was used in nine cases; IV adenosine injection was used in one case to achieve cardiac standstill. Complete AVM nidus obliteration was achieved with excellent neurologic outcome in nine cases, with transvenous embolization alone in two cases, and with staged transarterial followed by transvenous embolization in the others. Two patients developed hemorrhagic complications intraprocedurally. One patient was managed conservatively and the other operatively with AVM excision and hematoma evacuation; both made an excellent recovery without any neurologic deficits at 3 months. CONCLUSION: Complete flow control using concurrent transient rapid ventricular pacing with afferent arterial balloon flow arrest technique is safe and feasible for transvenous embolization of select AVMs.

Hypertension Caused by Renal Arteriovenous Fistula with Multiple Renal Artery Aneurysms.

Renal arteriovenous fistula with renal artery aneurysms and dilated renal veins presents as an infrequent lesion. Endovascular therapy has recently been considered the first-line treatment for these conditions. We report a case of a patient with idiopathic renal arteriovenous fistula concomitant with multiple renal artery aneurysms that was successfully treated by the placement of a covered stent.

The Successful Treatment of an Ilio-Iliac Fistula and Aneurysms Affecting the Abdominal Aortic and Iliac Arteries via Endovascular Stent Graft Repair.

Spontaneous ilio-iliac arteriovenous fistula (AVF) associated with aneurysms affecting the abdominal aortic and iliac arteries is a rare condition. The classical clinical symptoms of ilio-iliac AVF include high-output heart failure, abdominal pain, abdominal bruits and thrills, a pulsatile abdominal mass, and venous congestion symptoms (leg edema and hematuria). The prompt repair of AVF is necessary to restore the patient's hemodynamics. We report a case in which a patient with aneurysms affecting the abdominal aortic and iliac arteries and an ilio-iliac AVF presented with high-output heart failure and leg ischemia and was successfully treated via endovascular stent graft repair.

Magnetic Resonance Perfusion Changes of Arteriovenous Malformations Treated with Stereotactic Radiosurgery.

BACKGROUND: The latency period from stereotactic radiosurgery (SRS) to obliteration of arteriovenous malformations (AVM) requires continuous imaging surveillance. Magnetic resonance (MR) perfusion is promising for noninvasive monitoring of AVMs after SRS. We studied longitudinal MR perfusion changes of brain AVMs treated with SRS. METHODS: Consecutive patients treated for brain AVMs using SRS who had MR perfusion imaging studies performed before and at least once after SRS were studied. We estimated ipsilateral/contralateral brain hemisphere ratios of MR perfusion indexes, including regional cerebral blood flow (rCBF) and relative cerebral blood volume (rCBV), in the AVM nidus, perinidal region, and remote anterior and posterior brain regions. RESULTS: Eleven patients (6 women; median age, 21 years) underwent SRS (median prescription dose, 18 Gy; range, 12-20 Gy) for brain AVMs (median Spetzler-Martin grade 2 and median volume 4.6 mL). Before the SRS, rCBV and rCBF ratios were significantly higher in the AVM nidus compared with other investigated brain regions (P < 0.001). Median time from SRS to the first and last post-SRS MR perfusion studies was 8 and 35 months, respectively. There was a statically significant decrease of rCBV (P = 0.043) and rCBF (P = 0.036) ratios in the AVM nidus, but not other brain regions, during post-SRS follow-up. CONCLUSIONS: There is a gradual decrease of rCBV and rCBF in the AVM nidus after SRS. MR perfusion imaging is promising for monitoring of hemodynamic changes of AVMs after SRS. Larger studies investigating clinical value of MR perfusion imaging for AVMs after SRS are warranted.

Altered Brain Structural Networks in Patients with Brain Arteriovenous Malformations Located in Broca's Area.

Focal brain lesions, such as stroke and tumors, can lead to remote structural alterations across the whole-brain networks. Brain arteriovenous malformations (AVMs), usually presumed to be congenital, often result in tissue degeneration and functional displacement of the perifocal areas, but it remains unclear whether AVMs may produce long-range effects upon the whole-brain white matter organization. In this study, we used diffusion tensor imaging and graph theory methods to investigate the alterations of brain structural networks in 14 patients with AVMs in the presumed Broca's area, compared to 27 normal controls. Weighted brain structural networks were constructed based on deterministic tractography. We compared the topological properties and network connectivity between patients and normal controls. Functional magnetic resonance imaging revealed contralateral reorganization of Broca's area in five (35.7%) patients. Compared to normal controls, the patients exhibited preserved small-worldness of brain structural networks. However, AVM patients exhibited significantly decreased global efficiency (p = 0.004) and clustering coefficient (p = 0.014), along with decreased corresponding nodal properties in some remote brain regions (p < 0.05, family-wise error corrected). Furthermore, structural connectivity was reduced in the right perisylvian regions but enhanced in the perifocal areas (p < 0.05). The vulnerability of the left supramarginal gyrus was significantly increased (p = 0.039, corrected), and the bilateral putamina were added as hubs in the AVM patients. These alterations provide evidence for the long-range effects of AVMs on brain white matter networks. Our preliminary findings contribute extra insights into the understanding of brain plasticity and pathological state in patients with AVMs.