MRA Images Research Articles

EICAB: A novel deep learning pipeline for Circle of Willis multiclass segmentation and analysis

BackgroundThe accurate segmentation, labeling and quantification of cerebral blood vessels on MR imaging is important for basic and clinical research, yet results are not generalizable, and often require user intervention. New methods are needed to automate this process. PurposeTo automatically segment, label and quantify Circle of Willis (CW) arteries on Magnetic Resonance Angiography images using deep convolutional neural networks. Materials and methodsMRA images were pooled from three public and private databases. A total of 116 subjects (mean age 56 years ± 21 [standard deviation]; 72 women) were used to make up the training set (N=101) and the testing set (N=15). In each image, fourteen arterial segments making up or surrounding the CW were manually annotated and validated by a clinical expert. Convolutional neural network (CNN) models were trained on a training set to be finally combined in an ensemble to develop eICAB. Model performances were evaluated using (1) quantitative analysis (dice score on test set) and (2) qualitative analysis (external datasets, N=121). The reliability was assessed using multiple MRAs of healthy participants (ICC of vessel diameters and volumes on test-retest). ResultsQualitative analysis showed that eICAB correctly predicted the large, medium and small arteries in 99±0.4%, 97±1% and 88±7% of all images, respectively. For quantitative assessment, the average dice score coefficients for the large (ICAs, BA), medium (ACAs, MCAs, PCAs-P2), and small (AComm, PComm, PCAs-P1) vessels were 0.76±0.07, 0.76±0.08 and 0.41±0.27, respectively. These results were similar and, in some cases, statistically better (p<0.05) than inter-expert annotation variability and robust to image SNR. Finally, test-retest analysis showed that the model yielded high diameter and volume reliability (ICC=0.99). ConclusionWe have developed a quick and reliable open-source CNN-based method capable of accurately segmenting and labeling the CW in MRA images. This method is largely independent of image quality. In the future, we foresee this approach as a critical step towards fully automated analysis of MRA databases in basic and clinical research.

Poster 195: Inverse Relationship of Hip Capsular Thickness on Magentic Resonance Imaging and Increased Axial Distraction Under Anesthesia: Further Characterization of Hip Laxity

Objectives:The hip joint derives its stability from several biomechanical and anatomic factors, including the ligaments of the hip capsule. Recent research has implicated the hip capsule in the pathogenesis of hip instability, which is especially important when considering the inherent violation of the hip capsule with arthroscopic procedures. The purpose of this study was to characterize the relationship between quantitative axial hip distraction and capsular thickness on magnetic resonance imaging (MRI). We hypothesized that thinner hip capsules would be associated with increased axial distraction distances at maximal traction force.Methods:A retrospective review of the senior author’s primary hip arthroscopic procedures was conducted from November 2018 to June 2021. Inclusion criteria were 1) diagnosis of FAI, 2) pre-operative MRI, 3) and intra-operative fluoroscopic imaging conducted at 0 and 100 pounds (lbs) of axial distraction. Intra-operative, fluoroscopic images were obtained at the beginning of the procedure prior to any instrumentation at 0 lbs and 100 lbs of axial traction force. Distraction distance was calculated by comparing the difference of the initial joint space to the total joint space at 100 lbs and measured using a picture archiving and communication system (PACS). Hip capsule thickness was measured on pre-operative MRI or MRA imaging. Anterior and posterior capsular thickness was measured in the axial plane, while superior and inferior capsule thickness was measured in the coronal plane. Anterior and superior measurements approximated the iliofemoral ligament, with posterior and inferior measurements approximating the ischiofemoral and pubofemoral ligaments. Three measurements were taken in each region of the hip capsule and averaged to produce an accurate estimate of hip capsule thickness in each region. Statistical analysis was conducted using multiple linear regression and independent samples t-tests with an alpha of <0.05.Results:Eighty patients were included from 121 charts reviewed, with 41 patients being excluded for lack of appropriate preoperative imaging to evaluate joint distraction or capsular thickness. Bivariable regression demonstrated increased distraction associated with female sex (B = -4.303, p <0.001). Axial distraction was also shown to be increased in relation to decreased capsular thickness in the anterior axial (B = -1.291, p < 0.001), superior coronal (B = -1.433, p <0.001), and posterior axial regions (B = -1.293, p = 0.028). Multivariable regression of the hip capsular measurements demonstrated increased axial distraction associated with decreased superior coronal capsular thickness (B = -1.402, p < 0.001). Independent samples t-tests showed females had significantly decreased hip capsular thickness in the superior coronal, anterior axial, and posterior axial regions (p = <0.05).Conclusions:Our results show several significant associations with hip capsular thickness and hip axial distraction. Patients with thinner hip capsules in the anterior axial, posterior axial, and superior coronal regions were found to have increased axial distraction distances at 100 lbs of force. These findings are in line with previous descriptions of the importance of the iliofemoral ligament and hip stability, which was approximated in this study using the anterior axial and superior coronal measurements. While female sex was observed to be associated with increased axial distraction, this may potentially be secondary to females having statistically thinner hip capsules as shown by our findings. This observation provides a more nuanced anatomic explanation for this association that has been previously reported regarding patient sex and hip laxity. Our findings further demonstrate the importance of the hip capsule as it pertains to hip joint stability, providing a quantitative method to evaluate hip capsular thickness and joint distraction. Clinically, these results are important to consider in the evaluation of hip instability and capsular insufficiency.Table 1.Multivariable regression results with axial distraction at 100 1bs of force as the independent variable

Three‐dimensional multicontrast blood imaging with a single acquisition: Simultaneous non‐contrast‐enhanced MRA and vessel wall imaging in the thoracic aorta

Three‐dimensional multicontrast blood imaging with a single acquisition: Simultaneous non‐contrast‐enhanced MRA and vessel wall imaging in the thoracic aorta

GVC-Net: Global Vascular Context Network for Cerebrovascular Segmentation Using Sparse Labels

ObjectivesCerebrovascular disease is a serious threat to human health. Because of its high mortality and disability rate, early diagnosis and prevention are very important. The performance of existing cerebrovascular segmentation methods based on deep learning depends on the integrity of labels. However, manual labels are usually of low quality and poor connectivity at small blood vessels, which directly affects the cerebrovascular segmentation results. Material and methodIn this paper, we propose a new segmentation network to segment cerebral vessels from MRA images by using sparse labels. The long-distance dependence between vascular structures is captured by the global vascular context module, and the topology is constrained by the hybrid loss function to segment the cerebral vessels with good connectivity. ResultExperiments show that our method performed with a sensitivity, precision, dice similarity coefficient, intersection over union and centerline dice similarity coefficient of 61.24%, 75.58%, 67.66%, 51.13% and 83.79% respectively. ConclusionThe obtained results reveal that the proposed cerebrovascular segmentation network has better segmentation performance for cerebrovascular segmentation under sparse labels, and can suppress the noise of background to a certain extent.

Studying the Role of Cerebrovascular Changes in Different Compartments in Human Brains in Hypertension Prediction

Hypertension is a major cause of mortality of millions of people worldwide. Cerebral vascular changes are clinically observed to precede the onset of hypertension. The early detection and quantification of these cerebral changes would help greatly in the early prediction of the disease. Hence, preparing appropriate medical plans to avoid the disease and mitigate any adverse events. This study aims to investigate whether studying the cerebral changes in specific regions of human brains (specifically, the anterior, and the posterior compartments) separately, would increase the accuracy of hypertension prediction compared to studying the vascular changes occurring over the entire brain’s vasculature. This was achieved by proposing a computer-aided diagnosis system (CAD) to predict hypertension based on cerebral vascular changes that occur at the anterior compartment, the posterior compartment, and the whole brain separately, and comparing corresponding prediction accuracy. The proposed CAD system works in the following sequence: (1) an MRA dataset of 72 subjects was preprocessed to enhance MRA image quality, increase homogeneity, and remove noise artifacts. (2) each MRA scan was then segmented using an automatic adaptive local segmentation algorithm. (3) the segmented vascular tree was then processed to extract and quantify hypertension descriptive vascular features (blood vessels’ diameters and tortuosity indices) the change of which has been recorded over the time span of the 2-year study. (4) a classification module used these descriptive features along with corresponding differences in blood pressure readings for each subject, to analyze the accuracy of predicting hypertension by examining vascular changes in the anterior, the posterior, and the whole brain separately. Experimental results presented evidence that studying the vascular changes that take place in specific regions of the brain, specifically the anterior compartment reported promising accuracy percentages of up to 90%. However, studying the vascular changes occurring over the entire brain still achieve the best accuracy (of up to 100%) in hypertension prediction compared to studying specific compartments.

Three-dimensional multicontrast blood imaging with a single acquisition: Simultaneous non-contrast-enhanced MRA and vessel wall imaging in the thoracic aorta.

To evaluate MRA and vessel wall imaging (VWI) image quality in the thoracic aorta using a novel method named BRIDGE (bright and dark blood images with multishot gradient-echo EPI). The BRIDGE method consists of 3D multishot gradient-echo EPI acquisition using pulse gating, navigator gating, and magnetization preparation with a T2 -preparation pulse and a nonselective inversion-recovery pulse. The BRIDGE and conventional methods (noncontrast MRA based on 3D turbo-field-echo [TFE] and VWI based on 3D turbo spin echo with variable refocusing flip angle [VRFA-TSE]) were performed in 10 healthy volunteers and 10 patients. The SNR, contrast-to-noise ratio (CNR), and sharpness in the thoracic aorta were compared for MRA evaluation. The values of SNRlumen , SNRwall , CNRwall-lumen , contrast ratio (CR)lumen-muscle , coefficient of variation, sharpness, lumen area, and wall area in the thoracic aorta were compared for VWI evaluation. Two radiologists independently performed qualitative image-analysis assessments. When MRA and VWI were acquired, the acquisition time was 26.6% to 27.8% shorter with BRIDGE than the conventional method. In the MRA evaluation, BRIDGE and TFE methods were comparable. In the VWI evaluation, BRIDGE was superior to the VRFA-TSE method in blood suppression and evaluation of the ascending aorta. Because the blood signal suppression of BRIDGE is based on the T1 value of blood, the blood signal can be suppressed more uniformly than with the VRFA-TSE method, regardless of age, blood flow velocity, or vascular anatomy. The BRIDGE method can provide both MRA, to assess vascular anatomy and luminal changes, and VWI, to assess the vessel wall and detect vulnerable plaques, in a single scan.

A Magnetic Resonance Angiography-Based Study Comparing Machine Learning and Clinical Evaluation: Screening Intracranial Regions Associated with the Hemorrhagic Stroke of Adult Moyamoya Disease

ObjectivesMoyamoya disease patients with hemorrhagic stroke usually have a poor prognosis. This study aimed to determine whether hemorrhagic moyamoya disease could be distinguished from MRA images using transfer deep learning and to screen potential regions that contain rich distinguishing information from MRA images in moyamoya disease. Materials and methodsA total of 116 adult patients with bilateral moyamoya diseases suffering from hemorrhagic or ischemia complications were retrospectively screened. Based on original MRA images at the level of the basal cistern, basal ganglia, and centrum semiovale, we adopted the pretrained ResNet18 to build three models for differentiating hemorrhagic moyamoya disease. Grad-CAM was applied to visualize the regions of interest. ResultsFor the test set, the accuracies of model differentiation in the basal cistern, basal ganglia, and centrum semiovale were 93.3%, 91.5%, and 86.4%, respectively. Visualization of the regions of interest demonstrated that the models focused on the deep and periventricular white matter and abnormal collateral vessels in hemorrhagic moyamoya disease. ConclusionA transfer learning model based on MRA images of the basal cistern and basal ganglia showed a good ability to differentiate between patients with hemorrhagic moyamoya disease and those with ischemic moyamoya disease. The deep and periventricular white matter and collateral vessels at the level of the basal cistern and basal ganglia may contain rich distinguishing information.

Non-Contrast-Enhanced and Contrast-Enhanced Magnetic Resonance Angiography in Living Donor Liver Vascular Anatomy.

Background: Since the advent of a new generation of inflow-sensitive inversion recovery (IFIR) technology, three-dimensional non-contrast-enhanced magnetic resonance angiography is being used to obtain hepatic vessel images without applying gadolinium contrast agent. The purpose of this study was to explore the diagnostic efficacy of non-contrast-enhanced magnetic resonance angiography (non-CE MRA), contrast-enhanced magnetic resonance angiography (CMRA), and computed tomography angiography (CTA) in the preoperative evaluation of living liver donors. Methods: A total of 43 liver donor candidates who were evaluated for living donor liver transplantation completed examinations. Donors’ age, gender, renal function (eGFR), and previous CTA and imaging were recorded before non-CE MRA and CMRA. CTA images were used as the standard. Results: Five different classifications of hepatic artery patterns (types I, III, V, VI, VIII) and three different classifications of portal vein patterns (types I, II, and III) were identified among 43 candidates. The pretransplant vascular anatomy was well identified using combined non-CE MRA and CMRA of hepatic arteries (100%), PVs (98%), and hepatic veins (100%) compared with CTA images. Non-CE MRA images had significantly stronger contrast signal intensity of portal veins (p < 0.01) and hepatic veins (p < 0.01) than CMRA. No differences were found in signal intensity of the hepatic artery between non-CE MRA and CMRA. Conclusion: Combined non-CE MRA and CMRA demonstrate comparable diagnostic ability to CTA and provide enhanced biliary anatomy information that assures optimum donor safety.

Association of cerebral infarction with vertebral arterial fenestration using non-Newtonian hemodynamic evaluation

&lt;abstract&gt; &lt;sec&gt;&lt;title&gt;Purpose&lt;/title&gt;&lt;p&gt;Cerebral artery fenestration is a rare vascular anomaly, but its existence has been increasingly documented. The association of cerebral infarction and fenestration is of great clinical interest, and the exact underlying mechanism remains unclear. This study aims to identify risk factors contributing to cerebral infarction by computational hemodynamics analysis.&lt;/p&gt; &lt;/sec&gt; &lt;sec&gt;&lt;title&gt;Methods&lt;/title&gt;&lt;p&gt;Eight patients with image findings of fenestration structure were recruited in this research, in which four suffered fenestration-related cerebral infarction (A series) while the other four (B series) were set as control matched by the fenestration size. Three-dimensional models were reconstructed from the MRA images and computational simulations with non-Newtonian flow model were performed to get interested hemodynamic characteristics.&lt;/p&gt; &lt;/sec&gt; &lt;sec&gt;&lt;title&gt;Results&lt;/title&gt;&lt;p&gt;The blood flow pattern was relatively separated along two channels of fenestration in series A compared with series B cases in Group 1-2, however, no significant difference was shown in Group 3-4. Quantitatively, planes were cut in the middle of fenestrations and the ratio of mass flow rate and area was calculated at systolic peak. Results showed that the side of the dominant blood supply was opposite between A and B series, and the dominant side was also opposite between small and large fenestrations. In infarction cases, the basilar top was distributed with larger areas of detrimental hemodynamic indicators and a larger concentrated high viscosity region.&lt;/p&gt; &lt;/sec&gt; &lt;sec&gt;&lt;title&gt;Conclusion&lt;/title&gt;&lt;p&gt;The flow division condition throughout the fenestration structure has a key impact on further flow redistribution and flow pattern. The blood viscosity has the potential to be a useful tool in identifying the risk factors for cerebral infarction and more emphasis should be placed on the hemodynamic environment at superior cerebellar arteries.&lt;/p&gt; &lt;/sec&gt; &lt;/abstract&gt;

MRA of the Supraaortic Vasculature: Comparison of Gadobutrol and Gadoterate Meglumine at 1.5 T.

Gadobutrol (GB) and gadoterate meglumine (GM) are contrast agents used for contrast-enhanced magnetic resonance angiography (CEMRA). Supraaortic vasculature (SAV) CEMRAs are used to evaluate stroke risk and neurologic symptoms. There is a need to compare the SAV CEMRA image quality obtained with GB and GM. To intra-individually compare MRA images obtained with equimolar GB and GM at 1.5T in the SAV. Prospective, crossover. Twenty-eight subjects (54 ± 13 years; 17 female). 1.5 T; three-dimensional (3D) gradient recalled echo. Quantitative image quality was measured by normalized signal intensity (SIn ) [SIn =SI blood/SD blood] and contrast ratio (CR) [CR=SI blood/SI muscle], determined by an observer (JWC) with 1 year of vascular imaging experience. Three radiologists (AS, PA, and MU) with (5, 5, and 6 years of) vascular imaging experience evaluated image quality by Likert-scale ratings (of image impression, wall conspicuity, and artifact absence). SIn and CR were compared with paired t-tests or Wilcoxon signed-rank tests and Bland-Altman plots. Qualitative ratings were compared with Wilcoxon signed-rank test. No significant difference in SIn was found between GB and GM. CRs with GB were significantly higher than GM at the right common carotid (6.9 ± 2.5 vs. 4.8 ± 1), left internal carotid (7.3 ± 2 vs. 4.4 ± 1.2), right internal carotid (7.7 ± 2.2 vs. 5 ± 1.1), and left vertebral (6.6 ± 2.2 vs. 4.5 ± 1.1) arteries. Bland-Altman plots showed relatively greater differences between GB and GM at higher CRs and SIn s. GM showed significantly higher artifact than GB (3.56 ± 0.52 vs. 3.36 ± 0.46) and significantly lower overall image quality (10.73 ± 1.45 vs. 11.26 ± 1.58) at the left vertebral artery. At 1.5T and equimolar demonstration, GB (0.1mL/kg, i.e., 0.1 mmol/kg) showed higher CRs in the SAV compared to GM (0.2mL/kg, i.e., 0.1 mmol/kg) at most vessels. Subjective image quality was not significantly different between the two agents for most vessels. 2 TECHNICAL EFFICACY: Stage 2.

Application of MAGnetic resonance imaging compilation in acute ischemic stroke.

BACKGROUNDSynthetic magnetic resonance imaging (MRI) MAGnetic resonance imaging compilation (MAGiC) is a new MRI technology. Conventional T1, T2, T2-fluid-attenuated inversion recovery (FLAIR) contrast images, quantitative images of T1 and T2 mapping, and MAGiC phase sensitive inversion recovery (PSIR) Vessel cerebrovascular images can be obtained simultaneously through post-processing at the same time after completing a scan. In recent years, studies have reported that MAGiC can be applied to patients with acute ischemic stroke. We hypothesized that the synthetic MRI vascular screening scheme can evaluate the degree of cerebral artery stenosis in patients with acute ischemic stroke.AIMTo explore the application value of vascular images obtained by synthetic MRI in diagnosing acute ischemic stroke.METHODSA total of 64 patients with acute ischemic stroke were selected and examined by MRI in the current retrospective cohort study. The scanning sequences included traditional T1, T2, and T2-FLAIR, three-dimensional time-of-flight magnetic resonance angiography (3D TOF MRA), diffusion-weighted imaging (DWI), and synthetic MRI. Conventional contrast images (T1, T2, and T2-FLAIR) and intracranial vessel images (MAGiC PSIR Vessel] were automatically reconstructed using synthetic MRI raw data. The contrast-to-noise ratio (CNR) values of traditional T1, T2, and T2-FLAIR images and MAGiC reconstructed T1, T2, and T2-FLAIR images in DWI diffusion restriction areas were measured and compared. MAGiC PSIR Vessel and TOF MRA images were used to measure and calculate the stenosis degree of bilateral middle cerebral artery stenosis areas. The consistency of MAGiC PSIR Vessel and TOF MRA in displaying the degree of vascular stenosis with computed tomography angiography (CTA) was compared.RESULTSAmong the 64 patients with acute ischemic stroke, 79 vascular stenosis areas showed that the correlation between MAGiC PSIR Vessel and CTA (r = 0.90, P < 0.01) was higher than that between TOF MRA and CTA (r = 0.84, P < 0.01). With a degree of vascular stenosis > 50% assessed by CTA as a reference, the area under the receiver operating characteristic (ROC) curve of MAGiC PSIR Vessel [area under the curve (AUC) = 0.906, P < 0.01] was higher than that of TOF MRA (AUC = 0.790, P < 0.01). Among the 64 patients with acute ischemic stroke, 39 were scanned for traditional T1, T2, and T2-FLAIR images and MAGiC images simultaneously, and CNR values in DWI diffusion restriction areas were measured, which were: Traditional T2 = 21.2, traditional T1 = -6.7, and traditional T2-FLAIR = 11.9; and MAGiC T2 = 7.1, MAGiC T1 = -3.9, and MAGiC T2-FLAIR = 4.5.CONCLUSIONThe synthetic MRI vascular screening scheme for patients with acute ischemic stroke can accurately evaluate the degree of bilateral middle cerebral artery stenosis, which is of great significance to early thrombolytic interventional therapy and improving patients’ quality of life.

Learning From Mouse CT-Scan Brain Images To Detect MRA-TOF Human Vasculatures.

The earlier studies on brain vasculature semantic segmentation used classical image analysis methods to extract the vascular tree from images. Nowadays, deep learning methods are widely exploited for various image analysis tasks. One of the strong restrictions when dealing with neural networks in the framework of semantic segmentation is the need to dispose of a ground truth segmentation dataset, on which the task will be learned. It may be cumbersome to manually segment the arteries in a 3D volumes (MRA-TOF typically). In this work, we aim to tackle the vascular tree segmentation from a new perspective. Our objective is to build an image dataset from mouse vasculatures acquired using CT-Scans, and enhance these vasculatures in such a way to precisely mimic the statistical properties of the human brain. The segmentation of mouse images is easily automatized thanks to their specific acquisition modality. Thus, such a framework allows to generate the data necessary for the training of a Convolutional Neural Network - i.e. the enhanced mouse images and there corresponding ground truth segmentation - without requiring any manual segmentation procedure. However, in order to generate an image dataset having consistent properties (strong resemblance with MRA images), we have to ensure that the statistical properties of the enhanced mouse images do match correctly the human MRA acquisitions. In this work, we evaluate at length the similarities between the human arteries as acquired on MRA-TOF and the "humanized" mouse arteries produced by our model. Finally, once the model duly validated, we experiment its applicability with a Convolutional Neural Network.

A Unique Volumetric Modulated Arc Stereotactic Radiosurgery (SRS)Treatment Planning Approach for Volume Staged SRS to Large Arteriovenous Malformation

The management of large Arteriovenous Malformation AVMs (> 10cc) using volume staged Stereotactic Radiosurgery (VS SRS) usually requires more than 2 VS SRS procedures. VS SRS downsizes the treatment volume per stage allowing effective higher dose of SRS to relative smaller volumes of target to reduce risk of SRS induced brain necrosis. It is imperative to maintain the SRS treatment plan quality matrix of conformity and dose gradient at optimal values to minimize the adverse radiation effects to surrounding brain tissues. However, VS SRS plans can present a challenge at treatment planning given the angioarchitecture of staged volumes and total volume, delivery technique and modality limitations.A 37-year-old female patient has history of headaches, intraventricular hemorrhage, and cerebral arteriovenous malformation AVM in the right parietal lobe. This large AVM (16.5cc) scored 4 on Spetzler-Martin grading system. Patient was simulated with large board CT simulator using an SRS mask. 1 mm thickness of CT images with IV contrast per CTA protocol were obtained and imported into the TPS. MRA images data sets and Angio CBCT scans from arteriogram were registered to CT Simulation scans for contouring AMV nidus. The nidus was divided into 3 sub volumes of 8 cc, 4.5cc and 4 cc, respectively. The dose of 20 Gy was prescribed to entire volume of nidus and portions of total dose were delivered to sub volumes with interval of 2-4 weeks. The VMAT inverse treatment plans were generated for each volume/isocenter using non-coplanar arcs. to be delivered on HDMLC. Collimator and arc angles were configured geometrically to minimize dose spillage between staged volumes. Planning objectives including generalized uniform equivalent dose gEUD were assigned to planning volumes and OARs. Normal tissue objective was enabled, structure resolution was set to 1.25mm, and AAA calculation grid was set to 1mm. Individual and composite plans isodoses and DVHs were examined repetitively during the planning and optimization iterations to confirm meeting the acceptable VS SRS plan quality matrix or to adjust if needed. All three individual sub volume plans passed IMRT QA (> 90%, DTA 1mm, %DD 2%) RESULTS: The composite plan maximum dose was 33.3 Gy, minimum dose for total nidus volume was 94%, and 95.2%, 100%, 109% for three sub volumes of nidus, respectively. V95%was > 95% and D95% was > 95% for all three sub volumes and total volume in the composite plan. The mean dose was 27.7 Gy. CI was 0.63, PITV was 1.57, R50 was 4.36 while GI was 2.77, V12 was 52.9cc (3.9%).The proposed unique VMAT VS SRS for large AVM achieves adequate and comparable treatment planning quality parameters when evaluated with published literature covering VS SRS delivery with different treatment modalities such as robotic radiosurgery systems. Our preliminary results from previous treated patients using same planning technique showed good response rate and very low rate of brain necrosis.F. Wang: None. D. Soultan: None. H. Jiang: None. N. Demez: None.

Renal Artery Variations in Patients With Mild-to-Moderate Hypertension From the RADIANCE-HTN SOLO Trial

PurposeTo assess the variability of renal artery (RA) anatomy and presence of RA-pathology in patients with mild-to-moderate hypertension enrolled in the RADIANCE-HTN SOLO trial. BackgroundRADIANCE-HTN SOLO was a multicenter, international, blinded, randomized, sham-controlled trial evaluating ultrasound-based endovascular renal denervation (RDN) in patients with mild-to-moderate hypertension while off antihypertensive medications. MethodsEligible subjects had pre-randomization renal CT- or MR- angiography (CTA, MRA) to confirm anatomic suitability and to define RA ablation sites. All images were sent for independent review for evaluation of RA anatomy and other vascular pathology. ResultsA total of 324 patients underwent RA imaging (282 CTA and 42 MRA). Of those, 178 had simple anatomy with a single left and single right RA with mean diameters of 5.4 ± 0.9 and 5.1 ± 0.8 mm and mean lengths of 40.0 ± 12.9 and 52.0 ± 13.1 mm, respectively. Twenty-seven patients (8.3%) had unilateral or bilateral dual RAs with mean diameters of 4.0 ± 0.9 mm on the left and 3.9 ± 0.9 mm on the right. Forty percent (129/324) of patients had at least 1 accessory RA, with mean accessory diameters of 2.4 ± 0.8 mm on the left and 2.3 ± 0.8 mm on the right. Twenty-eight patients (8.6%) had at least 1 short (<25 mm) main RA. Incidental findings included: 9 patients (2.8%) with atherosclerotic RA stenosis ≥30%, 9 patients (2.8%) with fibromuscular dysplasia of RA and 2 patients (0.6%) with kidney and adrenal gland tumors. ConclusionsPre-procedure CTA or MRA imaging is a valuable aid in assessing RA anatomy prior to RDN because of variable RA anatomy. CTA or MRA may detect RA lesions, and renal or adrenal tumors which may need additional workup prior to consideration of RDN. Clinical trial registrationClinicalTrials.gov NCT02649426.

MULTI-parametric MR imaging with fLEXible design (MULTIPLEX).

To introduce a gradient echo (GRE) -based method, namely MULTIPLEX, for single-scan 3D multi-parametric MRI with high resolution, signal-to-noise ratio (SNR), accuracy, efficiency, and acquisition flexibility. With a comprehensive design with dual-repetition time (TR), dual flip angle (FA), multi-echo, and optional flow modulation features, the MULTIPLEX signals contain information on radiofrequency (RF) B1t fields, proton density, T1 , susceptibility and blood flows, facilitating multiple qualitative images and parametric maps. MULTIPLEX was evaluated on system phantom and human brains, via visual inspection for image contrasts and quality or quantitative evaluation via simulation, phantom scans and literature comparison. Region-of-interest (ROI) analysis was performed on parametric maps of the system phantom and brain scans, extracting the mean and SD of the T1 , , proton density (PD), and/or quantitative susceptibility mapping (QSM) values for comparison with reference values or literature. One MULTIPLEX scan offers multiple sets of images, including but not limited to: composited PDW/T1 W/ W, aT1 W, SWI, MRA (optional), B1t map, T1 map, / maps, PD map, and QSM. The quantitative error of phantom T1 , and PD mapping were <5%, and those in brain scans were in good agreement with literature. MULTIPLEX scan times for high resolution (0.68 × 0.68 × 2 mm3 ) whole brain coverage were about 7.5 min, while processing times were <1 min. With flow modulation, additional MRA images can be obtained without affecting the quality or accuracy of other images. The proposed MUTLIPLEX method possesses great potential for multi-parametric MR imaging.

Usefulness of three-dimensional fast imaging employing steady-state acquisition MRI of large vessel occlusion for detecting occluded middle cerebral artery and internal carotid artery before acute mechanical thrombectomy.

Objective Acute mechanical thrombectomy (AMT) in patients with acute ischemic stroke from large vessel occlusion (LVO) is performed without directly identifying the occluded vessels. In this study, we evaluated whether 1.5 T magnetic resonance imaging (MRI) with 3D-fast imaging employing steady-state acquisition (FIESTA) could visualize the occluded intracranial middle cerebral artery (MCA) and internal carotid artery (ICA) before AMT.Methods This retrospective study included 21 consecutive patients who underwent time-of-flight magnetic resonance angiography (TOF MRA) and 3D-FIESTA MRI immediately before AMT. The patients also underwent TOF MRA after AMT and achieved TICI 2b or 3 by AMT at our hospital between February 2018 and April 2019. When LVO in the anterior circulation was detected by TOF MRA, 3D-FIESTA MRI was additionally performed. Then, the occluded intracranial MCA and ICA, including their branches, were constructed on the workstation with volume rendering. The obtained images were fused with the TOF MRA images to create combined 3D images.Results The length and top-to-bottom distance of the affected M1 segment (calculated by the ipsilateral-to-contralateral ratio) were 1.29 and 1.17, respectively, on 3D-FIESTA MRI before AMT and 1.34 and 1.24, respectively, on TOF MRA after AMT. We assessed the number of M2 segments branching from the affected M1/M2 junction and visualized the affected anterior temporal artery. The 3D-FIESTA MRI before AMT and TOF MRA after AMT were consistent in all patients, except for two who moved vigorously during imaging.Conclusions Images acquired by 1.5T 3D-FIESTA MRI can visualize to predict the existing path of the occluded MCA and ICA before AMT in patients with LVO of the anterior circulation.

Radio-carpal wrist MR arthrography: comparison of ultrasound with fluoroscopy and palpation-guided injections.

To compare ultrasound- (US), fluoroscopy- (FL), and palpation-guided contrast injection techniques used for dorsal radio-carpal wrist MRA. Patients with chronic wrist pain were randomized as to which injection technique they underwent into three groups of 50 participants. Dorsal radio-carpal contrast injection was performed under US, FL guidance (one radiologist for each), or palpation guidance by an orthopedic surgeon. The three techniques were compared by procedure time, success rate, number of attempts needed, frequency and grade of extravasation, joint distension, and MRA image quality. Additionally, any change from baseline wrist pain was recorded using the visual analog scale (VAS) at five time points (immediately, 8h, 24h, 48h, and 1week) after injection. One hundred and fifty patients (83 males and 67 females; mean age 29 ± 6.5years) were included. Success rates for US- and FL-guided injections were 100%, while palpation-guided approach was significantly less successful (72%) (P = 0.02) with significantly more frequent extravasation (56%)(P < 0.001). US guidance was the least time-consuming (6.5 ± 1.6min) compared to FL guidance (12.5 ± 1.9min) and palpation guidance (8 ± 1.2min) (all P < 0.001). The mean number of joint puncture attempts was significantly lower with imaging-guided techniques (1.1 ± 0.24 and 1.2 ± 0.4 for US and FL, P = 0.23) compared to palpation-guided one (1.6 ± 0.8) (P = 0.007). The largest increases in baseline-pain were 8-h post-injection, and US guidance was the least painful at all-time points (all P < 0.05). Joint distension and image quality were significantly better with imaging-guided techniques (P < 0.001 and P = 0.003). US-guided radio-carpal injection is a less time-consuming, more tolerable, and successful radiation-free method when compared to FL guidance. Palpation-guided injections require multiple attempts to enter the joint with high failure rates and frequent extravasation.

MRI-Based Investigation of Association Between Cerebrovascular Structural Alteration and White Matter Hyperintensity Induced by High Blood Pressure.

High blood pressure (BP) is a common risk factor for cerebral small vessel disease including white matter hyperintensity (WMH). Whether increased BP exacerbates WMH by impacting cerebral vascular morphologies remains poorly studied. To determine the relationships among high BP, cerebrovascular morphologies, and WMH in elderly individuals. Cohort. Eight hundred sixty-three participants (54.2% female) from the Taizhou Imaging Study without clinical evidence of neurologic disorders were included in the analyses. 3.0 T; time-of-flight magnetic resonance angiography (TOF MRA); T2 fluid-attenuated inversion recovery (FLAIR); T1 magnetization-prepared rapid gradient-echo; gradient echo T2*-weighted; diffusion tensor imaging; pulsed arterial spin labeling. Cerebrovascular morphologic measurements were quantified based on the TOF MRA images, including vessel density, radius, tortuosity, and branch number. WMH lesion volumes (WMHV) and WMH lesion counts (WMHC) were calculated automatically based on the T2 FLAIR images. Multivariable linear regression analysis and path analysis with a linear single-mediator model were employed. A P value <0.05 was considered statistically significant. Higher BP, especially diastolic BP, was significantly correlated with lower cerebrovascular density (β=-104) and lower branch numbers (β=-0.02). Although decreased tortuosity (β=-1.25) and increased radius (β=93.8) were correlated with BP, no significant relationship of tortuosity (β=-4.6 × 10-4 , P=0.58) or radius (β=0.03, P=0.08) with BP in small vessels was found. The proportion of small vessels decreased as BP increased (SBP: β=-6.6 × 10-4 ; DBP: β=-9.0 × 10-4 ). Similarly, increased WMHV and WMHC were associated with decreased vessel density (volumes: β=-24, counts: β=-127), decreased tortuosity (volumes: β=-0.08, counts: β=-0.53), and increased radius (volumes: β=12.6, counts: β=86.6). Path analyses suggested an association between high BP and WMHs that were mediated by cerebrovascular morphologic changes. Structural alterations of cerebral vessels induced by high BP are correlated with WMH. This result suggested that elevated BP might be one of the pathophysiological mechanisms involving in the co-occurrence of cerebrovascular alteration and small vessel disease. 1 Technical Efficacy Stage: 1.

????The diagnostic performance of the combination of ASL and TOF MRA for the cerebral arteriovenous shunt

Objective: To evaluate the diagnostic performance of the combination of arterial spin labeling (ASL) and time of flight MR angiography (TOF MRA) for intracranial arteriovenous shunt (AVS) detection. Methods: A total of 39 patients with known or suspected with cerebrovascular malformations underwent digital subtraction angiography (DSA) and ASL/TOF MRA imaging in Department of neurosurgery and radiology and nuclear medicine, Xuanwu Hospital from May 1, 2020 to October 31, 2020 were retrospectively analyzed. Patients were divided into either acute cerebral hemorrhage group (n=13) or non-acute cerebral hemorrhage group (n=26) based on the signs of bleeding on imaging findings. According to history of treatment, those patients were divided into treated (n=11) and untreated (n=28) subgroups. The determination of the presence of AVS on images was judged by two radiologists in a blinded and randomized order fashion. The diagnostic performance of ASL or TOF MRA for AVS were evaluated in overall, acute cerebral hemorrhage subgroup and treated subgroup by using the area under receiver operating curve (AUC) with DSA as the reference standard, respectively. The κ coefficients were calculated to determine the interobserver agreement. Results: Among 39 patients, 29 patients were confirmed with AVS by DSA while 10 patients with no AVS. Interobserver agreement was good-excellent (κ=0.83-1.00). In patients with AVM, the detection rates for AVS of ASL or TOF MRA were 93.1% and 86.2% respectively, while the detection rates of the combination of ASL and TOF MRA were 100%. The AUC of ASL, TOF MRA and their combination for diagnosis of AVS in overall were 0.966 (95%CI: 0.909-1.00), 0.914 (95%CI: 0.825-1.00) and 0.983 (95%CI:0.943-1.00), respectively. The AUC of ASL, TOF MRA and their combination for AVS in acute cerebral hemorrhage subgroup were 1(95%CI:1.00-1.00), 0.833(95%CI:0.611-1.00), 1(95%CI:1.00-1.00), respectively. Conclusion: Combination of ASL and TOF MRA can be a non-invasive thchnique for the detection of AVS.

Performance changes due to differences in training data for cerebral aneurysm detection in head MR angiography images

The performance of computer-aided detection (CAD) software depends on the quality and quantity of the dataset used for machine learning. If the data characteristics in development and practical use are different, the performance of CAD software degrades. In this study, we investigated changes in detection performance due to differences in training data for cerebral aneurysm detection software in head magnetic resonance angiography images. We utilized three types of CAD software for cerebral aneurysm detection in MRA images, which were based on 3D local intensity structure analysis, graph-based features, and convolutional neural network. For each type of CAD software, we compared three types of training pattern, which were two types of training using single-site data and one type of training using multisite data. We also carried out internal and external evaluations. In training using single-site data, the performance of CAD software largely and unpredictably fluctuated when the training dataset was changed. Training using multisite data did not show the lowest performance among the three training patterns for any CAD software and dataset. The training of cerebral aneurysm detection software using data collected from multiple sites is desirable to ensure the stable performance of the software.