Contrast-enhanced Magnetic Resonance Angiography Research Articles

Long-term safety and efficacy of stenting on correcting internal jugular vein and cerebral venous sinus stenosis.

To compare the long-term safety and efficacy of stenting in correcting cerebral venous sinus stenosis (CVSS) and internal jugular venous stenosis (IJVS). Patients confirmed with CVSS or IJVS by imaging were enrolled in this real-world study from 2014 through 2021. Clinical characteristics and long-term outcomes of these two diseases entities post-stenting were followed up and compared. Three hundred and nineteen patients were enrolled in this study, with a mean age of 48.83 years and a BMI of 25.08 on average. In which, 144 patients underwent stenting, the stenotic segments were corrected and the venous blood flow was restored immediately post-stenting. At 6.15 ± 1.67 days follow-up, significant improvement was observed in headache, tinnitus, insomnia, ICP, and mean pressure gradient in both groups (all p < 0.05). At 30.53 ± 4.41 months follow-up post-stenting, the headache, tinnitus, visual loss, papilledema, and insomnia were attenuated remarkably or even completely disappeared. The Frisen papilledema grade scores declined from 2 (0-4) to 1 (0-3) in IJVS group and from 4 (1-5) to 1 (0-4) in CVSS group compared to the baseline. One hundred and twenty-seven out of the 144 patients (95.5%) maintained sufficient blood flow verified by followed up computed tomographic venography or contrast-enhanced magnetic resonance angiography. Adverse events related to stenting included three cases of intraluminal restenosis and three cases of in-stent thrombosis, no intracranial hemorrhage, venous thromboembolisms, stent-adjacent stenosis, and stent displacement occurred. Using stents to correct IH and related neurological issues has shown to be a safe and effective approach for both IJVS and CVSS.

Advances in Management of the Stroke Etiology One-Percenters.

Uncommon causes of stroke merit specific attention; when clinicians have less common etiologies of stoke in mind, the diagnosis may come more easily. This is key, as optimal management will in many cases differs significantly from "standard" care. Randomized controlled trials (RCT) on the best medical therapy in the treatment of cervical artery dissection (CeAD) have demonstrated low rates of ischemia with both antiplatelet and vitamin K antagonism. RCT evidence supports the use of anticoagulation with vitamin K antagonism in "high-risk" patients with antiphospholipid antibody syndrome (APLAS), and there is new evidence supporting the utilization of direct oral anticoagulation in malignancy-associated thrombosis. Migraine with aura has been more conclusively linked not only with increased risk of ischemic and hemorrhagic stroke, but also with cardiovascular mortality. Recent literature has surprisingly not provided support the utilization of L-arginine in the treatment of patients with mitochondrial encephalopathy, lactic acidosis, and stroke-like episodes (MELAS); however, there is evidence at this time that support use of enzyme replacement in patients with Fabry disease. Additional triggers for reversible cerebral vasoconstriction syndrome (RCVS) have been identified, such as capsaicin. Imaging of cerebral blood vessel walls utilizing contrast-enhanced MRA is an emerging modality that may ultimately prove to be very useful in the evaluation of patients with uncommon causes of stroke. A plethora of associations between cerebrovascular disease and COVID-19 have been described. Where pertinent, authors provide additional tips and guidance. Less commonly encountered conditions with updates in diagnosis, and management along with clinical tips are reviewed.

Value of contrast-enhanced MR angiography for the follow-up of treated brain arteriovenous malformations: systematic review and meta-analysis.

To estimate the diagnostic value of contrast-enhanced MR angiography (CE-MRA) in identifying residual brain arteriovenous malformations (AVMs) after treatment. We retrieved appropriate references from the electronic databases of PubMed, Web of Science, Embase, and Cochrane Library, and then evaluated the methodology quality of included references using the QUADAS-2 tool. We calculated the pooled sensitivity and specificity by applying a bivariate mixed-effects model and detected the publication bias using Deeks' funnel plot. The values of I2 were used to test heterogeneity and meta-regression analyses were performed to search for the causes of heterogeneity. We included 7 eligible studies containing 223 participants. Compared with a gold standard, the overall sensitivity and specificity of CE-MRA in detecting residual brain AVMs were 0.77 (95% CI 0.65-0.86) and 0.97 (95% CI 0.82-1.00), respectively. Based on the summary ROC curve, the AUC was 0.89 (95% CI 0.86-0.92). Heterogeneity could be observed in our study, especially for the specificity (I2 = 74.23%). Furthermore, there was no evidence of publication bias. Our study provides evidence that CE-MRA has good diagnostic value and specificity for the follow-up of treated brain AVMs. Nevertheless, considering the smallsamplesize, heterogeneity, and many factors that may affect the diagnostic accuracy, future large-sample, prospective studies are necessary to validate the results. • The pooled sensitivity and specificity of contrast-enhanced MR angiography (CE-MRA) in detecting residual arteriovenous malformations (AVMs) were 0.77 (95% CI 0.65-0.86) and 0.97 (95% CI 0.82-1.00). • The four-dimensional CE-MRA showed less sensitivity than the three-dimensional CE-MRA for treated AVMs. • CE-MRA is helpful to identify residual AVMs and reduce excessive DSA during follow-up.

MRI characteristics of lumbosacral dural arteriovenous fistulas.

Spinal dural arteriovenous fistulas located in the lumbosacral region are rare and present with nonspecific clinical signs. The purpose of this study was to find out the specific radiologic features of these fistulas. We retrospectively reviewed the clinical and radiological data of 38 patients diagnosed with lumbosacral spinal dural arteriovenous fistulas in our institution from September 2016 to September 2021. All patients underwent time-resolved contrast-enhanced three-dimensional MRA and DSA examinations, and were treated with either endovascular or neurosurgical strategies. Most of the patients (89.5%) had motor or sensory disorders in both lower limbs as the first symptoms. On MRA, the dilated filum terminale vein or radicular vein was seen in 23/30 (76.7%) patients with lumbar spinal dural arteriovenous fistulas and 8/8 (100%) patients with sacral spinal dural arteriovenous fistulas. T2W intramedullary abnormally high signal intensity areas were found in all lumbosacral spinal dural arteriovenous fistula patients, with involvement of the conus present in 35/38 (92.1%) patients. The "missing piece sign" in the intramedullary enhancement area was seen in 29/38 (76.3%) patients. Dilatation of the filum terminale vein or radicular vein is powerful evidence for diagnosis of lumbosacral spinal dural arteriovenous fistulas, especially for sacral spinal dural arteriovenous fistulas. T2W intramedullary hyperintensity in the thoracic spinal cord and conus, and the missing-piece sign could be indicative of lumbosacral spinal dural arteriovenous fistula.

Short- and long-term outcomes after endarterectomy with autologous patching in endurance athletes with iliac artery endofibrosis

ObjectiveEndurance athletes such as cyclists may develop intermittent claudication owing to iliac artery endofibrosis after long-lasting extreme hemodynamic challenges. This study investigated short-term (<1.5 years) and long-term (>5 years) satisfaction and safety after a surgical endarterectomy and autologous patching. MethodsData of endurance athletes who underwent an endarterectomy for flow limitation of the iliac artery owing to endofibrosis between 1997 and 2015 in one center were studied. Maximal cycling exercise tests, ankle-brachial index with flexed hips, echo-Doppler examination (peak systolic velocity), and contrast-enhanced magnetic resonance angiography were performed before and 6 to 18 months after surgery. Short-term and long-term satisfaction were evaluated using questionnaires. Potential patch dilatation was assessed using echo-Doppler. ResultsAnalysis of 68 patients (79 legs; 55.7% males, median age at the time of surgery, 34 years; interquartile range, 26-41 years) demonstrated that cycling workload at symptom onset improved from 226 ± 97 to 333 ± 101 (P < .001) Watts. Peak workload increased from 326 ± 111 to 352 ± 93 Watts (P < .001). Ankle-brachial index with flexed hips increased from 0.34 (interquartile range [IQR], 0.00-0.47) to 0.59 (IQR, 0.51-0.69; P < .001). Peak systolic velocity with extended and flexed hip decreased from 2.04 m·sec−1 (IQR, 1.52-2.56 m·3sec−1) to 1.25 m·sec−1 (IQR, 0.92-1.62 m·sec−1; P < .001) and 2.40 m·sec−1 (IQR, 1.81-2.81 m·sec−1) to 1.15 m·sec−1 (IQR, 0.97-1.60 m·sec−1; P < .001), respectively. Thirty-day major complication rate was 5.1% (hematoma requiring evacuation nLegs = 2, septic bleeding from deep infection nLegs = 1, and iliac occlusion requiring thrombectomy nLegs = 1). In the short term, 91.2% of patients reported symptom reduction with a 93.7% overall satisfaction rate. After a median of 11.1 years (IQR, 7.8-17.6 years), the overall satisfaction was 91.7%; 94.5% of patients reported persistent symptom reduction. Patch dilatation of >20 mm was observed in two patients. Linear mixed model analysis revealed no alarming patch dilatation in the long term. ConclusionsEndarterectomy with an autologous patch for intermittent claudication owing to iliac artery endofibrosis in endurance athletes shows high rates of patient satisfaction and symptom reduction in both the short and long term. The risk of surgical complications or patch dilatation is mild. A surgical intervention for flow limitation of the iliac artery owing to endofibrosis is safe and successful.

Comparison of Biplane Area-Length Method and 3D Volume Quantification by Using Cardiac MRI for Assessment of Left Atrial Volume in Atrial Fibrillation

To compare maximum left atrial (LA) volume (LAV) from the routinely used biplane area-length (BAL) method with three-dimensional (3D)-based volumetry from late gadolinium-enhanced MRI (3D LGE MRI) and contrast-enhanced MR angiography (3D CE-MRA) in patients with atrial fibrillation (AF). Sixty-four patients with AF (mean age, 63 years ± 9 [SD]; 40 male patients) were retrospectively included from a prospective cohort acquired between October 2018 and February 2021. All patients underwent a research MRI examination that included standard two- and four-chamber cine acquisitions, 3D CE-MRA, and 3D LGE MRI performed prior to the atrial kick. Contour delineation on cine imaging and LA 3D segmentations were performed by a radiologist. Maximum LAV (BALmax) was extracted from the BAL volume-time curve and compared with LAV from 3D CE-MRA and 3D LGE MRI. The Kruskal-Wallis test was performed, followed by the Dunn post hoc test and Bland-Altman analyses. Interobserver variability was assessed in 10 patients. BALmax underestimated LAV compared with 3D CE-MRA (bias: -23.5 mL ± 46.2, P < .001) and 3D LGE MRI (bias: -31.3 mL ± 58.3, P < .001), whereas 3D LGE MRI volumes showed no evidence of a difference from 3D CE-MRA (bias: 7.8 mL ± 45.7, P = .38). Interobserver variability yielded excellent agreement for each method (intraclass correlation coefficient, 0.96-0.98). BALmax underestimated LAV in patients with AF compared with 3D LGE MRI and 3D CE-MRA, suggesting that the geometric assumption of an ellipsoidal LA shape in BAL does not reflect LA geometry in patients with AF.Keywords: Left Atrial Volume, Biplane Area-Length, Late Gadolinium-enhanced 3D MRI, Contrast-enhanced 3D MR Angiography, Atrial Fibrillation Supplemental material is available for this article. © RSNA, 2023.

Gadolinium(III) Complex-Backboned Branched Polymers as Imaging Probes for Contrast-Enhanced Magnetic Resonance Angiography.

Compared to traditional branched polymers with Gd(III) chelates conjugated on their surface, branched polymers with Gd(III) chelates as the internal skeleton are considered to be a reasonable strategy for preparing efficient magnetic resonance imaging contrast agents. Herein, the Gd(III) ligand DOTA was chosen as the internal skeleton; four different molecular weights (3.5, 5.3, 8.6, and 13.1 kDa) and degrees of branching poly-DOTA branched polymers (P1, P2, P3, and P4) were synthesized by a simple "A2 + B4"-type one-pot polymerization. The Gd(III) chelates of these poly-DOTA branched polymers (P1-Gd, P2-Gd, P3-Gd, and P4-Gd) display excellent kinetic stability, which is significantly higher than those of linear Gd-DTPA and cyclic Gd-DOTA-butrol and slightly lower than that of cyclic Gd-DOTA. The T1 relaxivities of P1-Gd, P2-Gd, P3-Gd, and P4-Gd are 29.4, 38.7, 44.0, and 47.9 Gd mM-1 s-1, respectively, at 0.5 T, which are about 6-11 times higher than that of Gd-DOTA (4.4 Gd mM-1 s-1). P4-Gd was selected for in vivo magnetic resonance angiography (MRA) because of its high kinetic stability, T1 relaxivity, and good biosafety. The results showed excellent MRA effect, sensitive detection of vascular stenosis, and prolonged observation window as compared to Gd-DOTA. Overall, Gd(III) chelates of poly-DOTA branched polymers are good candidates of MRI probes, providing a unique design strategy in which Gd chelation can occur at both the interior and surface of the poly-DOTA branched polymers, resulting in excellent relaxivity enhancement. In vivo animal MRA studies of the probe provide possibilities in discovering small vascular pathologies.

A case of limb shaking transient ischaemic attack due to internal carotid artery dissection: an unusual presentation of fibromuscular dysplasia

BackgroundFibromuscular dysplasia (FMD) has a high prevalence of associated nontraumatic carotid artery dissection, which could further result in transient ischaemic attack (TIA) or stroke. Limb shaking TIA is an unusual form of TIA that is commonly discribed in elderly patients with atherosclerotic backgrounds, while there are limited data about it in patients with FMD. Furthermore, discussions of limb shaking TIA in nonelderly patients are scarce.Case presentationAn Asian 47-year-old female presented with intermittent involuntary movement of the left upper limb accompanied by neck torsion. The episode stopped soon after changing to the supine position. On native source images of time-of-flight magnetic resonance angiography (TOF-MRA), the right internal carotid artery showed a "dual lumen sign" with an intimal flap. On contrast-enhanced magnetic resonance angiography and sagittal black-blood T1WI, an intravascular haematoma with irregular lumen stenosis was observed, which overall indicated right internal carotid artery dissection. Digital subtraction angiography showed the characteristic “string-of-beads” appearance in the left internal carotid artery, and the presence of this sign pointed to the diagnosis of FMD. The patient was finally diagnosed with limb shaking TIA due to internal carotid dissection with fibromuscular dysplasia. The patient was prescribed dual anti-platelet therapy. The limb shaking vanished soon after admission with no reoccurrence in the three-month follow-up.ConclusionsThis case demonstrates that limb shaking TIA can present in patients with FMD. Limb shaking TIA in nonelderly patients can be caused by multiple diseases, and more detailed patient guidance is required in clinical practice.

Strong Contrast Stagnation of Unilateral Vertebral Artery on Three-Dimensional Black Blood-Enhanced MRI Predicts Acute Medulla Infarction.

This study aimed to evaluate angiographic and contrast enhancement (CE) patterns on three-dimensional (3D) black blood (BB) contrast-enhanced MRI in patients with acute medulla infarction. From January 2020 to August 2021, we retrospectively analyzed stroke 3D BB contrast-enhanced magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) findings of patients visiting the emergency room for symptom evaluation of acute medulla infarction. In total, 28 patients with acute medulla infarction were enrolled in this study. Four types of 3D BB contrast-enhanced MRI and MRA were classified as follows: 1=unilateral contrast-enhanced vertebral artery (VA)+no visualization of VA on MRA; 2=unilateral enhanced VA+hypoplastic VA; 3=no enhanced VA+unilateral complete occlusion of VA; 4=no enhanced VA+normal VA (including hypoplasia) on MRA. Of the 28 patients with acute medulla infarction, 7 (25.0%) showed delayed positive findings after 24 hours on diffusion-weighted imaging (DWI). Of these patients, 19 (67.9%) showed CE of the unilateral VA on 3D BB contrast-enhanced MRI (type 1 and 2). Of the 19 patients with CE of VA on 3D BB contrast-enhanced MRI, 18 showed no visualization of enhanced VA on MRA (type 1), and 1 showed hypoplastic VA. Of the 7 patients with delayed positive findings on DWI, 5 showed CE of the unilateral VA and no visualization of the enhanced VA on MRA (type 1). Symptom onset to door time or initial MR check time was significantly shorter in the groups with delayed positive findings on DWI (P<0.05). Unilateral CE on 3D BB contrast-enhanced MRI and no visualization of the VA on MRA are related to the recent occlusion of the distal VA. These findings suggest that the recent occlusion of the distal VA is related to acute medulla infarction, including delayed visualization on DWI.

State of the Art MR Imaging for Lung Cancer TNM Stage Evaluation.

Since the Radiology Diagnostic Oncology Group (RDOG) report had been published in 1991, magnetic resonance (MR) imaging had limited clinical availability for thoracic malignancy, as well as pulmonary diseases. However, technical advancements in MR systems, such as sequence and reconstruction methods, and adjustments in the clinical protocol for gadolinium contrast media administration have provided fruitful results and validated the utility of MR imaging (MRI) for lung cancer evaluations. These techniques include: (1) contrast-enhanced MR angiography for T-factor evaluation, (2) short-time inversion recovery turbo spin-echo sequences as well as diffusion-weighted imaging (DWI) for N-factor assessment, and (3) whole-body MRI with and without DWI and with positron emission tomography fused with MRI for M-factor or TNM stage evaluation as well as for postoperative recurrence assessment of lung cancer or other thoracic tumors using 1.5 tesla (T) or 3T systems. According to these fruitful results, the Fleischner Society has changed its position to approve of MRI for lung or thoracic diseases. The purpose of this review is to analyze recent advances in lung MRI with a particular focus on lung cancer evaluation, clinical staging, and recurrence assessment evaluation.

Contrast-enhanced magnetic resonance angiography in the identification of prostatic arterial anatomy in patients with benign prostatic hyperplasia: prospective comparison with digital subtraction angiography

To evaluate the utility of contrast-enhanced magnetic resonance angiography (CE-MRA) for identifying prostatic artery (PA) anatomy in patients with benign prostatic hyperplasia (BPH) before PA embolisation (PAE), using digital subtraction angiography (DSA) as the reference standard. A total of 176 patients underwent pelvic CE-MRA at 3 T. DSA was performed within the following 7 days. Two interventional radiologists compared the CE-MRA findings with DSA findings to assess the anatomy of the PAs. The rates of correct identification of the origins and collaterals of the PAs by CE-MRA were calculated. The utility for predicting the optimal X-ray tube angle obliquity for visualising the origins of the PAs by CE-MRA was evaluated. An exact McNemar's test was used to compare the detection rates of the PAs and the collaterals with DSA versus CE-MRA. A two-sided p-value of <0.05 was considered statistically significant. Of the 376 PAs identified by DSA, CE-MRA correctly identified the origins of 369 vessels (98.1%), with a 1.9% false-negative rate and no false-positive results. Of the 57 total collaterals identified by DSA, CE-MRA identified 50 vessels correctly (87.7%), with a 12.3% false-negative rate and no false-positive results. No significant differences were observed between CE-MRA and DSA in the identification of the PA origins (p=0.824) and the collaterals (p=0.327). The optimal degree for an oblique projection to visualise the origins of the PAs could be predicted accurately (100%) by pre-procedural CE-MRA. CE-MRA before PAE can reliably predict the PA anatomy and facilitate procedural planning.

Evaluation of Peripheral Arterial Disease Using Noncontrast Magnetic Resonance Angiography

Introduction: Peripheral arterial disease is common in older age group. PAD is evaluated using Doppler, contrast CT and MR angiography. Many PAD patients have comorbidities like diabetes, hypertension and renal dysfunction. CT and MR contrast administration is considered risky in patients with impaired renal function. CT contrast agents are nephrotoxic. Gadolinium-based MRI contrast are associated with nephrogenic systemic fibrosis in patients with severe renal dysfunction. Aims: The aim of our study was to evaluate the usefulness of non contrast enhanced MR angiography in imaging of peripheral arteries in patients with impaired renal function. Materials and Method: This prospective study was done using ECG-triggered 2D TOF MR Angiograpgy on 1.5 Tesla MR unit in PAD patients having renal dysfunction. We studied various arterial segments of lower limb for the degree of narrowing on MRA and compared the findings in all patients with duplex scan and in some patients with DSA. We determined accuracy, sensitivity, specificity, PPV and NPV of MRA compared to duplex scan for assessment of arterial luminal narrowing. Results: Our study results have demonstrated that in patients with high grade blockage (&gt;50% diameter reduction or arterial occlusion) NC MRA had almost 100 % accuracy, sensitivity, specificity, PPV and NPV when compared to duplex scan in iliac, femoro-popliteal and tibioperoneal segment. In patients with low grade blockage (&lt;50% diameter reduction) NC MRA had low sensitivity with high specificity and NPV. Conclusion: ECG-triggered non contrast-enhanced MR angiography (NCMRA) is safe and highly accurate in PAD patients having renal dysfunction.

Comparison of Access Route for Endovascular Treatment by Time-Spatial Labeling Inversion Pulse (Time-SLIP) MRA and Contrast-Enhanced MRA.

In endovascular treatment, it is important to evaluate the access route for placing a catheter into the common carotid artery (CCA) promptly and safely prior to the procedure. We examined whether non-contrast MRA using time-spatial labeling inversion pulse (Time-SLIP) can be used in patients prior to endovascular thrombectomy for acute ischemic stroke. We compared Time-SLIP MRA to contrast-enhanced (CE) MRA and evaluated the efficacy in the evaluation of access routes. We retrospectively reviewed 31 patients admitted between October 2018 and December 2018 for cerebral infarction at our hospital. Blood vessels were imaged from the aortic arch to the CCA. A radiologist blindly evaluated quality score, stenosis, shape of the aorta, and degree of tortuosity. There were no "non-diagnostic" images. The sensitivity, specificity, positive predictive value, and negative predictive value for stenosis were 83%, 96%, 83%, and 96%, respectively. The sensitivity for the aorta type classification was 100%. The sensitivity for mild tortuosity was 93%, for moderate was 100%, and for severe was 100%. Time-SLIP MRA can be an alternative to CE MRA in access route assessment for patients with cerebral infarction who are not eligible for acute thrombectomy therapy.

Survey of the American Society of Neuroradiology Membership on the Use and Value of Extracranial Carotid Vessel Wall MRI.

Extracranial vessel wall MRI (EC-VWI) contributes to vasculopathy characterization. This survey study investigated EC-VWI adoption by American Society of Neuroradiology (ASNR) members and indications and barriers to implementation. The ASNR Vessel Wall Imaging Study Group survey on EC-VWI use, frequency, applications, MR imaging systems and field strength used, protocol development approaches, vendor engagement, reasons for not using EC-VWI, ordering provider interest, and impact on clinical care was distributed to the ASNR membership between April 2, 2019, to August 30, 2019. There were 532 responses; 79 were excluded due to minimal, incomplete response and 42 due to redundant institutional responses, leaving 411 responses. Twenty-six percent indicated that their institution performed EC-VWI, with 66.3% performing it ≤1-2 times per month, most frequently on 3T MR imaging, with most using combined 3D and 2D protocols. Protocols most commonly included pre- and postcontrast T1-weighted imaging, TOF-MRA, and contrast-enhanced MRA. Inflammatory vasculopathy (63.3%), plaque vulnerability assessments (61.1%), intraplaque hemorrhage (61.1%), and dissection-detection/characterization (51.1%) were the most frequent applications. For those not performing EC-VWI, the reasons were a lack of ordering provider interest (63.9%), lack of radiologist time/interest (47.5%) or technical support (41.4%) for protocol development, and limited interpretation experience (44.9%) and knowledge of clinical applications (43.7%). Reasons given by 46.9% were that no providers approached radiology with interest in EC-VWI. If barriers were overcome, 51.1% of those not performing EC-VWI indicated they would perform it, and 40.6% were unsure; 48.6% did not think that EC-VWI had impacted patient management at their institution. Only 26% of neuroradiology groups performed EC-VWI, most commonly due to limited clinician interest. Improved provider and radiologist education, protocols, processing techniques, technical support, and validation trials could increase adoption.

Visualisation of lenticulostriate arteries using contrast-enhanced time-of-flight magnetic resonance angiography at 7 Tesla

7 Tesla-field-strength (7 T) Magnetic Resonance Imaging allows the small perforating arteries in the brain to be visualised, and this modality may allow visualisation of the arterial pathology in cerebral small vessel disease. Most studies have used standard Time-of-Flight (ToF) Magnetic Resonance Angiography (MRA). Whether the use of contrast enhancement improves perforating artery visualisation at 7 T remains unclear. In a prospective study, we compared standard ToF MRA with contrast-enhanced (CE) ToF MRA at 7 T for the visualisation of the lenticulostriate arteries (LSAs). Ten patients with symptomatic lacunar stroke were recruited (mean age, SD, 64 ± 9.9 years). Visualisation was assessed using a visual rating scale administered by two independent expert readers and length of the LSAs visible. Visualisation of the LSAs was improved with CE ToF MRA. The mean Visibility and Sharpness Score was higher for CE ToF MRA over standard ToF MRA (2.55 ± 0.64 vs. 1.75 ± 0.68; P = 0.0008). The mean length of LSA visualised was significantly longer with CE ToF MRA compared to standard ToF MRA (24.4 ± 4.5 vs. 21.9 ± 4.0 mm; P = 0.01). CE ToF MRA offers improved visualisation of the LSAs over standard ToF MRA. The addition of contrast may improve the ability to visualise cerebral small vessel disease arterial pathology.

Surgical shortening of lengthened iliac arteries in endurance athletes: Short-term and long-term satisfaction

ObjectiveEndurance athletes are prone to develop flow limitations in iliac arteries (FLIA). Especially in cyclists and ice speed skaters, excessive hemodynamic loading coupled with hip hyperflexion may cause kinking in lengthened iliac arteries necessitating surgical correction. This study investigated the short-term (≤1.5 years) and long-term (≥5 years) satisfaction of operative shortening of the iliac artery in endurance athletes. MethodsAll patients who were diagnosed and operated for FLIA owing to lengthened and kinked iliac arteries between 1997 and 2015 in one center were analyzed. Short-term follow-up consisted of an incremental maximal cycling test, ankle-brachial index with flexed hips, echo-Doppler examination with peak systolic velocity measurements and contrast-enhanced magnetic resonance angiography before and 6 to 18 months after surgery. Both short- and long-term satisfaction were assessed using questionnaires. ResultsA total of 83 patients (90 operated legs; 96.7% males; median age of 34 years at the time of surgery; interquartile range [IQR], 29-47) were analyzed. In the short-term, 87.5% reported symptom reduction with an 86.4% overall satisfaction rate. Symptom-free cycling improved from 272 ± 84 W to 384 ± 101 W (P < .001), whereas the maximal workload increased from 419 ± 72 W to 428 ± 67 W (P = .01). The ankle-brachial index with flexed hips increased from 0.55 (IQR, 0.45-0.65) to 0.62 (IQR, 0.52-0.74; P = .008), and the peak systolic velocity measured with hips flexed decreased from 2.50 m/s (IQR, 1.77-3.13 m/s) to 1.57 m/s (IQR, 1.20-2.04 m/s; P < .001). After a median of 12 years (IQR, 9.0-15.4 years), symptoms were still decreased in 84.1% of patients with an 81.2% overall satisfaction rate (79.5% response rate). Three patients needed a reintervention (recurrent FLIA, n = 2; failure, n = 1). ConclusionsOperative shortening of a lengthened and kinked iliac artery causing FLIA is successful both in the short- and long-term.

Overview of multimodal MRI of intracranial Dural arteriovenous fistulas

Dural arteriovenous fistulas (DAVFs) include a wide range of pathological conditions that are associated with intracranial vessel abnormalities. While some types of DAVFs present with typical neuroimaging characteristics, others share overlapping pathological and neuroimaging features that can hinder accurate differentiation. Hence, misclassification of the various types of DAVFs is common. Thorough knowledge of DAVF imaging findings is essential to avoid such misinterpretations. Traditional digital subtraction angiography (DSA) is considered the gold standard for diagnosing and evaluating DAVFs. However, angiography cannot detect changes in a patient's brain structure. Conventional magnetic resonance imaging (MRI) sequences, including MR angiography (MRA), allow the evaluation of DAVFs without ionizing radiation or invasiveness. Advanced MRI techniques, such as susceptibility-weighted imaging (SWI) and dynamic contrast-enhanced MRA, provide added value to real-time physio-pathological data regarding the hemodynamics of DAVFs. Beyond these techniques, new insights using high-resolution vascular wall MRI are incorporated for the noninvasive evaluation of DAVFs. This article reviews the pathophysiology of DAVFs, focusing on the specifics of MRI findings that facilitate their classification. The role of conventional and advanced MRI sequences for DAVFs was assessed using insights derived from the data provided by structured reports of multimodal MRIs to evaluate DAVFs.

Assessment of the degree of arterial stenosis in intracranial atherosclerosis using 3D high-resolution MRI: comparison with time-of-flight MRA, contrast-enhanced MRA, and DSA

To compare the accuracy of three-dimensional (3D) high-resolution (HR) magnetic resonance imaging (MRI), time-of-flight magnetic resonance angiography (TOF-MRA), contrast-enhanced magnetic resonance angiography (CE-MRA), and digital subtraction angiography (DSA) in measuring the degree of stenosis in intracranial atherosclerosis. All patients with intracranial artery ischaemic events underwent HR-MRI, TOF-MRA, and CE-MRA analysis, and some of these patients underwent DSA examination. The correlation between different methods for measuring the degree of lumen stenosis was analysed. The accuracy of HR-MRI, TOF-MRA, and CE-MRA was evaluated and compared with that of DSA. A total of 189 arterial stenoses were identified in 93 patients. Of these, 72 patients with 142 arterial stenoses underwent DSA examination. A very strong correlation between HR-MRI and CE-MRA measurements was shown (r=0.839, p<0.0001). The correlation between HR-MRI and TOF-MRA measurements was strong (r=0.720, p<0.0001). A very strong correlation between HR-MRI and DSA measurements was found (r=0.864, p<0.0001), and a similar correlation was observed between CE-MRA, and DSA measurements (r=0.843, p<0.0001). The correlation between TOF-MRA and DSA measurements was strong (r=0.686, p<0.0001). There was substantial agreement between HR-MRI and DSA measurements (K=0.772) and between CE-MRA, and DSA measurements (K=0.734) that was slightly higher than the agreement between TOF-MRA and DSA measurements (K=0.636). HR-MRI can accurately measure stenosis (especially for moderate and severe stenosis) in intracranial atherosclerosis by direct visualisation of the vessel lumen and steno-occlusive plaque.

Diagnostic value of contrast-enhanced ultrasound (CEUS) in kidney allografts – 12 years of experience in a tertiary referral center

B-Mode and Doppler ultrasound are standard diagnostic techniques for early postoperative monitoring and long-term follow-up of kidney transplants. In certain cases, contrast-enhanced ultrasound (CEUS) is used to clarify unclear Doppler findings. To investigate the diagnostic performance of CEUS in the workup of renal allograft pathologies. A systematic search for CEUS examinations of renal transplants conducted in our department between 2008 and 2020 was performed using the following inclusion criteria: i) patient age ≥18 years and ii) confirmation of diagnosis by biopsy and histopathology, imaging follow-up by CEUS, contrast-enhanced computed tomography (ceCT), contrast-enhanced magnetic resonance imaging (ceMRI), or angiography, or intraoperative findings. Exclusion criteria were: i) CEUS performed in the setting of a study and ii) CEUS for other indications than dedicated renal transplant examination. Statistical analysis was performed separately for subgroups with different indications (focal vs non-focal). Overall, 78 patients were included in the statistical analysis, which revealed high sensitivity (92.2%, 95% -confidence interval [CI] 81.5-96.9%) and high specificity (88.9%, 95% -CI 71.9-96.1%) of CEUS. The high diagnostic performance demonstrated here and the superficial location of kidney allografts advocate the additional use of CEUS in the follow-up of renal transplant recipients.

Rapid Formation of Methemoglobin via Nitric Oxide Delivery for Potential Use as an MRI Contrast Agent.

Contrast-enhanced magnetic resonance angiography is a vital tool for evaluating vascular pathology. However, concerns about the limitations and safety of gadolinium-based contrast agents have led to an interest in alternative agents. Methemoglobin (metHb) increases the T1-weighted signal intensity of the magnetic resonance image of blood and could provide a safe and effective alternative. MetHb can be produced by the reaction of nitric oxide (NO) gas with oxyhemoglobin followed by natural conversion back to hemoglobin by cytochrome b5 reductase. Since rapid production of metHb via NO has not been studied, the effectiveness of producing metHb via NO delivery to blood was evaluated using a hollow-fiber module. MetHb production began immediately and > 90% conversion was achieved within 10min. MetHb remained stable for at least 90min when NO delivery was removed following metHb formation. Comparison of experimental data for metHb formation with model predictions showed that only a fraction of the NO delivered was utilized for metHb production, suggesting an additional fast reaction of NO with other blood constituents. Directly delivering NO to blood for the rapid formation of metHb provides a potential platform for producing metHb as an alternative contrast agent.