3D Rotational Angiography Research Articles

3D Deep Learning Angiography (3D-DLA) from C-arm Conebeam CT.

Deep learning is a branch of artificial intelligence that has demonstrated unprecedented performance in many medical imaging applications. Our purpose was to develop a deep learning angiography method to generate 3D cerebral angiograms from a single contrast-enhanced C-arm conebeam CT acquisition in order to reduce image artifacts and radiation dose. A set of 105 3D rotational angiography examinations were randomly selected from an internal data base. All were acquired using a clinical system in conjunction with a standard injection protocol. More than 150 million labeled voxels from 35 subjects were used for training. A deep convolutional neural network was trained to classify each image voxel into 3 tissue types (vasculature, bone, and soft tissue). The trained deep learning angiography model was then applied for tissue classification into a validation cohort of 8 subjects and a final testing cohort of the remaining 62 subjects. The final vasculature tissue class was used to generate the 3D deep learning angiography images. To quantify the generalization error of the trained model, we calculated the accuracy, sensitivity, precision, and Dice similarity coefficients for vasculature classification in relevant anatomy. The 3D deep learning angiography and clinical 3D rotational angiography images were subjected to a qualitative assessment for the presence of intersweep motion artifacts. Vasculature classification accuracy and 95% CI in the testing dataset were 98.7% (98.3%-99.1%). No residual signal from osseous structures was observed for any 3D deep learning angiography testing cases except for small regions in the otic capsule and nasal cavity compared with 37% (23/62) of the 3D rotational angiographies. Deep learning angiography accurately recreated the vascular anatomy of the 3D rotational angiography reconstructions without a mask. Deep learning angiography reduced misregistration artifacts induced by intersweep motion, and it reduced radiation exposure required to obtain clinically useful 3D rotational angiography.

Impact of Intraoperative 3-Dimensional Volume-Rendering Rotational Angiography on Clip Repositioning Rates in Aneurysmal Surgery.

Three-dimensional (3D) rotational angiography (RA), a gold standard imaging tool for the evaluation of cerebral aneurysms after clipping, can currently be performed intraoperatively in a hybrid operating room (OR). However, its role in intraoperative aneurysmal surgery is unclear. We aimed to study the value of intraoperative 2-dimensional digital subtraction angiography (2D-DSA) and 3D-RA for the evaluation of aneurysms after clipping, in terms of clip repositioning. We included patients with cerebral aneurysms who were treated with microsurgical clipping in a hybrid OR. After aneurysmal clipping and indocyanine green video angiography assessment, intraoperative 2D-DSA and 3D-RA with volume-rendering (VR) images of the clipped aneurysm were obtained. The incidence rate of clip repositioning was determined, and aneurysm-related factors associated with suboptimal clipping that required clip revision after intraoperative angiography evaluation were analyzed. Between September 2016 and August 2017, 24 consecutive patients with 35 aneurysms were treated with microsurgical clipping. A clip repositioning rate of 17.1% was revealed after intraoperative 3D-VR imaging and initial indocyanine green-video angiography. 3D-VR was able to demonstrate all aneurysmal remnants, whereas 2D-DSA helped confirm flow stagnation in compromised vessels. Challenging aneurysms of size >7 mm (P= 0.043) and neck width >4 mm (P= 0.012) were significantly associated with a higher incidence of suboptimal aneurysmal clipping. A hybrid OR, with angiography facilities for high-resolution 2D-DSA and 3D-VR images, allows neurosurgeons to perform high-quality surgery. The routine use of intraoperative 3D-RA may not be necessary; however, it is invaluable for treating challenging aneurysms.

Radiation Dosimetry of 3D Rotational Neuroangiography and 2D-DSA in Children.

The benefit-risk assessment concerning radiation use in pediatric neuroangiography requires an extensive understanding of the doses delivered. This work evaluated the effective dose of 3D rotational angiography in a cohort of pediatric patients with complex neurovascular lesions and directly compared it with conventional 2D-biplane DSA. Thirty-three 3D rotational angiography acquisitions were acquired in 24 pediatric patients (mean age, 10.4 years). When clinically indicated, following 2D-biplane DSA, 3D rotational angiography was performed with 1 of 3 technical protocols (2 subtracted, 1 unsubtracted). The protocols consisted of 1 factory and 2 customized techniques, with images subsequently reconstructed into CT volumes for clinical management. Raw projections and quantitative dose metrics were evaluated, and the effective dose was calculated. All 3D rotational angiography acquisitions were of diagnostic quality and assisted in patient management. The mean effective doses were 0.5, 0.12, and 0.06 mSv for the factory-subtracted, customized-subtracted, and customized-unsubtracted protocols, respectively. The mean effective dose for 2D-biplane DSA was 0.9 mSv. A direct intraprocedural comparison between 3D and 2D acquisitions indicated that customized 3D rotational angiography protocols delivered mean relative doses of 9% and 15% in unsubtracted and subtracted acquisitions, respectively, compared with biplane DSA, whereas the factory subtracted protocol delivered 68%. In pediatric neuroangiography, the effective dose for 3D rotational angiography can be significantly lower than for 2D-biplane DSA and can be an essential adjunct in the evaluation of neurovascular lesions. Additionally, available 3D rotational angiography protocols have significant room to be tailored for effectiveness and dose optimization, depending on the clinical question.

TECHNIQUE AND UTILITY OF CT GUIDED TRANSCATHETER STENTING OF AORTIC COARCTATIONS IN ADULTS

3D rotational angiography (3DRA) and CT-fluoro image fusion can enhance fluoroscopy by optimizing C-arm angles and allowing real-time overlay of 3D regions of interest on 2D fluoroscopy. This case series demonstrates the techniques and utility of 3DRA and CT-fluoro image fusion during transcatheter

Preoperative 3-Dimensional Angiography Data and Intraoperative Real-Time Vascular Data Integrated in Microscope-Based Navigation by Automatic Patient Registration Applying Intraoperative Computed Tomography.

To establish a workflow integrating preoperative 3-dimensional (3D) angiography data and intraoperative real-time vascular information in microscope-based navigation for aneurysm and arteriovenous malformation (AVM) surgery. In 7 patients (3 with AVMs and 4 with aneurysms), preoperative 3D rotational angiography or computed tomography (CT) or magnetic resonance angiography data were navigated applying a 32-slice movable CT scanner for low-dose registration scanning. The 3D vasculature was segmented and visualized by microscope-based navigation along with navigated intraoperative real-time imaging data from indocyanin green angiography and duplex ultrasonography. Automatic registration applying intraoperative CT resulted in high accuracy (registration error, 0.80 ± 0.79mm). The effective radiation dose of the registration CT scans (0.28-0.42 mSv) was only approximately one-sixth of a standard diagnostic head CT scan. The 3D vessel architecture could be visualized accurately in the operating microscope heads-up display and on the navigation screens in the same projection as the view angle of the surgeon, both facilitating orientation in 3D space, providing a better understanding of anatomy. In addition, intraoperative real-time modalities could be coregistered with high precision, providing further information during the course of the vascular procedure. Registration CT imaging facilitates integrating preoperative and intraoperative vascular image data with a low registration error and low radiation exposure for the patient, improving the understanding of 3D vascular anatomy during surgery with easier identification of feeding vessels in AVMs, and of the projection and configuration of aneurysms.

Comparative analysis of aneurysm volume by different methods based on angiography and computed tomography angiography

Endovascular treatment and prognosis of intracranial aneurysms are based on size and volume, which demand more accurate neuroimaging techniques. Aneurysm volume calculation is important to choose endovascular treatment modalities and packing density calculation. Of all these methods, it remains unknown which one is the most accurate to calculate aneurysm volume. The objective of this study is to compare the accuracy of three angiography-based versus three tomographic-based methods which calculate aneurysm volume. A retrospective study which included patients with ruptured and unruptured cerebral aneurysms diagnosed by angiogram and computed tomography angiography (CTA) was done. The accuracy of each method was assessed with an ellipsoid glass model of known volume, which helped us to adjust variation in volumetric measurements done with AngioSuite© and AngioCalc© softwares (based on angiographic and tomographic images), 3D-rotational angiography and 3D-CTA (tridimensional computed tomography angiography), based on measurements of diameters such as maximal width and maximal height. Descriptive statistics, ANOVA for repetitive samples and t test were used. We included 89 patients (126 saccular intracraneal aneurysms). AngioSuite© software (angiography-based) showed more accuracy compared to other methods in our control model. The geometric system (AngioCalc) based on CTA images was statistically different from all other methods studied. AngioCalc (CTA-based) demonstrated a significant difference compared with other methods hence, it may overestimate volume measurements. AngioSuite

Development of three-dimensional brain arteriovenous malformation model for patient communication and young neurosurgeon education

Purpose: Rapid prototyping technology is used to fabricate three-dimensional (3D) brain arteriovenous malformation (AVM) models and facilitate presurgical patient communication and medical education for young surgeons.Methods: Two intracranial AVM cases were selected for this study. Using 3D CT angiography or 3D rotational angiography images, the brain AVM models were reconstructed on personal computer and the rapid prototyping process was completed using a 3D printer. The size and morphology of the models were compared to brain digital subtraction arteriography of the same patients. 3D brain AVM models were used for preoperative patient communication and young neurosurgeon education.Results: Two brain AVM models were successfully produced. By neurosurgeons’ evaluation, the printed models have high fidelity with the actual brain AVM structures of the patients. The patient responded positively toward the brain AVM model specific to himself. Twenty surgical residents from residency programs tested the brain AVM models and provided positive feedback on their usefulness as educational tool and resemblance to real brain AVM structures.Conclusions: Patient-specific 3D printed models of brain AVM can be constructed with high fidelity. 3D printed brain AVM models are proved to be helpful in preoperative patient consultation, surgical planning and resident training.

Fundamental Study on the Evaluation of the Vascular Lumen after Carotid Artery Stenting Using 3D-rotational Angiography with Diluted Contrast Medium

Fundamental Study on the Evaluation of the Vascular Lumen after Carotid Artery Stenting Using 3D-rotational Angiography with Diluted Contrast Medium

Evaluation of Plaque Protrusion Following Carotid Artery Stenting Using 3D-rotational Angiography

Evaluation of Plaque Protrusion Following Carotid Artery Stenting Using 3D-rotational Angiography

A new time-resolved 3D angiographic technique (4D DSA): Description, and assessment of its reliability in Spetzler–Martin grading of cerebral arteriovenous malformations

Background and purposeThe Spetzler and Martin (SM) cerebral arteriovenous malformation (AVM) classification is a widely used 5-tier classification. This common language allows specialists to exchange about AVMs and must be reliably characterized by the imaging methods. We presented an agreement study on a new method of digital subtracted 3D rotational angiography resolved in time (four-dimensional DSA: 4D DSA) compared to the gold standard (two-dimensional DSA: 2D DSA) in AVM grading using the SM classification. MethodsTen patients with AVMs were included during one year, they had an angiographic exploration with both 4D DSA and 2D DSA. Three readers assessed the SM classification. One reader conducted a second reading. The inter-, intra-observer and intermodality agreements were calculated by Kappas. Dose to patient was reported. ResultsConsidering the SM grade, the inter-observer agreement between 4D DSA and 2D DSA was equivalent (κ=0.45 and 0.46), and calculated as substantial κ=0.76 between the 2 methods. The agreement between 4D DSA and 2D DSA was calculated as moderate κ=0.46 assessing the size of the nidus, slight κ=0.18 analyzing the drainage and almost perfect κ=0.95 depicting the localization. 4D DSA performed during a standard initial angiographic assessment of AVM represented approximately 6% of the total dose. ConclusionThe addition of this new technique 4D DSA could be performed regularly in addition to the 2D DSA if available, to assess SM grading, with an acceptable exposure to ionizing radiation.

Control study of low tube voltage computed tomography angiography (CTA) and digital subtraction angiography (DSA) in diagnosing intracranial micro‐aneurysm

AbstractThe aim of this study was to investigate the diagnostic values of low tube voltage cerebral computed tomography (CT) angiography (L‐CTA, 100 kV) of intracranial micro‐aneurysms (IMA, maximum diameter ≤3 mm). The clinical and imaging data of a total of 59 IMA patients confirmed by 3D rotational angiography (3DRA) or surgery were retrospectively analyzed; their L‐CTA data were compared with those of IMA and 3DRA so as to investigate the diagnostic sensitivity, specificity, and accuracy of IMA, as well as to objectively evaluate the related radiation dose. Based on the results of 3DRA, 65 cases of IMA and a total of 70 aneurysms, including 65 micro‐aneurysms, were found in the 59 cases. L‐CTA detected a total of 64 IMA, including six multiple cases of IMA, as well as three false positive cases and four missed cases. Compared with the 3DRA (gold standard), the diagnostic sensitivity, specificity, and accuracy of L‐CTA toward IMA were 93.85%, 99.56%, and 99.08%, respectively, and the associations of aneurysm size measured by L‐CTA and 3DRA were good. Compared with conventional CTA, the effective dose of L‐CTA was reduced by 36.23%. L‐CTA has high diagnostic sensitivity toward IMA, and can effectively reduce the radiation dose, so it is worth implementing.

Vessel calibre and flow splitting relationships at the internal carotid artery terminal bifurcation

Objective: Vessel lumen calibres and flow rates are thought to be related by mathematical power laws, reflecting the optimization of cardiac versus metabolic work. While these laws have been confirmed indirectly via measurement of branch calibres, there is little data confirming power law relationships of flow distribution to branch calibres at individual bifurcations. Approach: Flow rates and diameters of parent and daughter vessels of the internal carotid artery terminal bifurcation were determined, via robust and automated methods, from 4D phase-contrast magnetic resonance imaging and 3D rotational angiography of 31 patients. Main results: Junction exponents were 2.06 ± 0.44 for relating parent to daughter branch diameters (geometrical exponent), and 2.45 ± 0.75 for relating daughter branch diameters to their flow division (flow split exponent). These exponents were not significantly different, but showed large inter- and intra-individual variations, and with confidence intervals excluding the theoretical optimum of 3. Power law fits of flow split versus diameter ratio and pooled flow rates versus diameters showed exponents of 2.17 and 1.96, respectively. A significant negative correlation was found between age and the geometrical exponent (r = −0.55, p = 0.003) but not the flow split exponent. We also found a dependence of our results on how lumen diameter is measured, possibly explaining some of the variability in the literature. Significance: Our study confirms that, on average, division of flow to the middle and anterior cerebral arteries is related to these vessels’ relative calibres via a power law, but it is closer to a square law than a cube law as commonly assumed.

Left atrial volume computed by 3D rotational angiography best predicts atrial fibrillation recurrence after circumferential pulmonary vein isolation.

Left atrium (LA) size is a well-studied predictor of atrial fibrillation (AF) recurrence after pulmonary vein isolation (PVI). Yet, there is still little agreement on the best imaging technique to size the LA, and on the most appropriate sizing parameter. Volumetric assessment of LA with three-dimensional rotational angiography (3DRA LA volume index) might be a valid alternative to the commonly used transthoracic echocardiography (TTE LA volume index). The aim of our study was to investigate whether LA volume by 3DRA at the time of PVI is able to predict the risk of atrial fibrillation recurrence. We analysed 352 consecutive patients with symptomatic paroxysmal or persistent atrial fibrillation referred for PVI to our Institution. In all patients, LA volume index (LAVI) was assessed by TTE and by 3DRA. Sinus rhythm was restored after PVI in 348 patients (99%). Average TTE-LAVI and 3DRA-LAVI were 37 ± 12 and 83 ± 18ml/m2, respectively. At a median follow-up of 19 (12, 24) months, 27% of patients had AF recurrence after the first PVI. At the univariate analysis, persistent AF (p < 0.01), use of anti-arrhythmic drugs (AAD) (p < 0.05) and 3DRA-LAVI (p < 0.01) were significantly associated with AF recurrence. In contrast, none of the echocardiographic parameters considered, including TTE-LAVI, was associated with AF recurrence (p = 0.29). At the multivariate analysis, 3DRA-LAVI was the only independent predictor for AF recurrence (HR 1.01 [1.00-1.03], p = 0.017). Left atrial volume measured with 3DRA is superior to TTE assessment and to AF history in predicting atrial fibrillation recurrence after PVI.

Anatomical localization of the cavernous sinus dural fistula by 3D rotational angiography with emphasis on clinical and therapeutic implications

Background and purposeCarotid cavernous sinus dural arteriovenous fistulas (CSDAVFs) are presumed to be located within the walls of the cavernous sinus, however the exact fistulous site has not yet been studied by angiographic or anatomical methods. The present study aimed to localize CSDAVFs with the help of 3D rotational angiography (RA) and correlated the observations with clinical and angiographic findings. Materials and methodsThe CSDAVFs were categorized as dural, extradural or osseous based on the site of convergence of feeders into the venous sac. Extradural CSDAVFs were further subcategorized into posteromedial, posterolateral and anterior subtypes, depending on proximity to a possible venous plexus. This classification was correlated with various clinical presentations and angiographic subtypes. ResultsThirty-seven patients were included in the final analysis. The sac was identified in all the patients and the mean sac size of the fistula was small (<4mm). Dural type was associated with exclusive cortical venous drainage. Extradural anterior CSDAVF showed tendency towards younger age predilection. Extradural posterolateral CSDAVF was more often associated with initial oculomotor nerve palsy and this observation was statistically significant. Discordancy between the location of the fistula and the side of clinical affection was observed in midline fistulas such as osseous CSDAVF and posteromedial type of extradural CSDAVF. ConclusionsCSDAVF is a heterogeneous vascular disorder involving the sphenoclival bone, extradural space and dura, homologous to the epidural-dural shunts of vertebra with a common clinical presentation of orbital manifestations. Preoperative localization of the fistula could explain enigmatic observations and potentially simplify its interventional management.

A computational fluid dynamics (CFD) study of WEB-treated aneurysms: Can CFD predict WEB “compression” during follow-up?

BackgroundRecent reports have revealed a worsening of aneurysm occlusion between WEB treatment baseline and angiographic follow-up due to “compression” of the device. ObjectiveWe utilized computational fluid dynamics (CFD) in order to determine whether the underlying mechanism of this worsening is flow related. MethodsWe included data from all consecutive patients treated in our institution with a WEB for unruptured aneurysms located either at the middle cerebral artery or basilar tip. The CFD study was performed using pre-operative 3D rotational angiography. From digital subtraction follow-up angiographies patients were dichotomized into two groups: one with WEB “compression” and one without. We performed statistical analyses to determine a potential correlation between WEB compression and CFD inflow ratio. ResultsBetween July 2012 and June 2015, a total of 22 unruptured middle cerebral artery or basilar tip aneurysms were treated with a WEB device in our department. Three patients were excluded from the analysis and the mean follow-up period was 17months. Eleven WEBs presented “compression” during follow-up. Interestingly, device “compression” was statistically correlated to the CFD inflow ratio (P=0.018), although not to aneurysm volume, aspect ratio or neck size. ConclusionThe mechanisms underlying the worsening of aneurysm occlusion in WEB-treated patients due to device compression are most likely complex as well as multifactorial. However, it is apparent from our pilot study that a high arterial inflow is, at least, partially involved. Further theoretical and animal research studies are needed to increase our understanding of this phenomenon.

Time-resolved 3D Rotational Angiography (4D DSA) of the Lenticulostriate Arteries: Display of Normal Anatomic Variants and Collaterals in Cases with Chronic Obstruction of the MCA.

The lenticulostriate arteries (LSA) and other perforators may play arole for collateral supply in cases with ischemia due to stenosis or occlusions of the middle cerebral artery (MCA). Purpose of this case series was to evaluate the potential of time-resolved 3D rotational angiography data sets (4D DSA) for detailed visualization of anatomic variants of LSA feeders and for display of local collaterals involving the LSA in cases with chronic MCA obstruction. Multiplanar and volume rendering reconstructions of 4D DSA data were computed in addition to standard postprocessing in 24patients who had indications for 3D rotational angiography (3DRA) of the internal carotid artery (ICA) without pathologies of the ICA, middle cerebral artery (MCA) and anterior cerebral artery (ACA) main stems (n= 18) or with stenosis or chronic occlusion of the MCA (n= 6). For acquisition of 3DRA, we used amodified digital subtraction angiography (DSA) image acquisition protocol with an extended rotation angle of 260° and aprolonged scan time of 12 s on aSiemens Axiom Artis Zee biplane neuroangiography equipment. The 4D reconstructions of existing 3DRA data were computed on adedicated workstation. Origin and course of LSA and other perforators were analyzed according to coronal multiplanar reconstructions (MPRs) with slice thicknesses between 6 and 28 mm. In all cases 4D reconstructions of the LSA were technically feasible and evaluable. As expected, origin and course of LSA showed awide range of variations: The most common pattern was acommon trunk dividing into multiple ascending branches originating from the proximal M1 (n= 5) or the proximal A1segment (n= 4). Alternatively, 8patients showed several individual branches that directly originated from the proximal M1segment of the MCA and occasionally from the A1segment of the ACA. In patients with M1stenosis or occlusion, 4 out of 6cases had local collaterals with involvement of proximal LSA trunks and anetwork parallel to the obstructed vessel segment. The 4D reconstructions were found to be equivalent (n= 16) or superior to 3D reconstructions (n= 8). The 4D DSA reconstructions provide areliable display of normal LSA variants and connections to local collateral networks in cases with chronic MCA obstruction. The possibility to select acorrect angiographic phase is advantageous compared to 3D DSA.

CT reconstruction and MRI fusion of 3D rotational angiography in the evaluation of pediatric cerebrovascular lesions.

Complex neurovascular lesions in children require precise anatomic understanding for treatment planning. Although 3DRA is commonly employed for volumetric reformation in neurointerventional procedures, the ability to reconstruct this data into CT-like images (3DRA-CT) is not widely utilized. This study demonstrates the feasibility and usefulness of 3DRA-CT and subsequent MRI fusion for problem solving in pediatric neuroangiography. This retrospective study includes 18 3DRA-CT studies in 16 children (age 9.6±3.8years, range 2-16years) over 1year. After biplane 2D-digital subtraction angiography (DSA), 5-second 3DRA was performed with selective vessel injection either with or without subtraction. Images were reconstructed into CT sections which were post-processed to generate multiplanar reformation (MPR) and maximum intensity projection (MIP) images. Fusion was performed with 3D T1 MRI images to precisely demonstrate neurovascular relationships. Quantitative radiation metrics were extracted and compared against those for the entire examination and for corresponding biplane 2D-DSA acquisitions. In all 18 cases, the 3DRA procedure and MRI fusion were technically successful and provided clinically useful information relevant to management. The unsubtracted and subtracted 3DRA acquisitions were measured to deliver 5.9 and 132.2%, respectively, of the mean radiation dose of corresponding biplane 2D-DSA acquisitions and contributed 1.2 and 12.5%, respectively, to the total procedure dose. Lower radiation doses, high spatial resolution, and multiplanar reformatting capability make 3DRA-CT a useful adjunct to evaluate neurovascular lesions in children. Fusing 3DRA-CT data with MRI is an additional capability that can further enhance diagnostic information.

Intraobserver and interobserver variability in CT angiography and MR angiography measurements of the size of cerebral aneurysms.

Accurate and reliable measurement of aneurysm size is important for treatment planning. The purpose of this study was to determine intraobserver and interobserver variability of CTA and MRA for measurement of the size of cerebral aneurysms. Thirty patients with 33 unruptured cerebral aneurysms (saccular, >3mm in their maximal dimension, with no daughter sacs or lobulations) who underwent 256-row multislice CTA, 3-D TOF MRA at 3.0T, and 3D rotational angiography (3DRA) were retrospectively analyzed. Three independent observers measured the neck, height, and width of the aneurysms using the CTA and MRA images. Intraobserver and interobserver variability of CTA and MRA measurements was evaluated using the standardized difference and intraclass correlation coefficient, with 3DRA measurements as the reference standard. In addition, the mean values of the measurements using CTA and MRA were compared with those using 3DRA. The overall intraobserver and interobserver standardized differences in CTA/MRA were 12.83-15.92%/13.48-17.45% and 14.08-17.00%/12.08-17.67%, respectively. The overall intraobserver and interobserver intraclass correlation coefficients of CTA/MRA were 0.88-0.98/0.84-0.96 and 0.86-0.98/0.85-0.95, respectively. Compared to the height and width measurements, measurements of the neck dimensions showed higher intraobserver and interobserver variability. The sizes of the cerebral aneurysms measured by CTA and MRA were 1.13-9.26 and 5.20-9.67% larger than those measured by 3DRA, respectively; however, these differences were not statistically significant. There were no noticeable differences between intraobserver and interobserver variability for both CTA- and MRA-based measurements of the size of cerebral aneurysms.

3D phase contrast MRI: Partial volume correction for robust blood flow quantification in small intracranial vessels.

Recent advances in 3D-PCMRI (phase contrast MRI) sequences allow for measuring the complex hemodynamics in cerebral arteries. However, the small size of these vessels vs spatial resolution can lead to non-negligible partial volume artifacts, which must be taken into account when computing blood flow rates. For this purpose, we combined the velocity information provided by 3D-PCMRI with vessel geometry measured with 3DTOF (time of flight MRI) or 3DRA (3D rotational angiography) to correct the partial volume effects in flow rate assessments. The proposed methodology was first tested in vitro on cylindrical and patient specific vessels subject to fully controlled pulsatile flows. Both 2D- and 3D-PCMRI measurements using various spatial resolutions ranging from 20 to 1.3 voxels per vessel diameter were analyzed and compared with flowmeter baseline. Second, 3DTOF, 2D- and 3D-PCMRI measurements were performed in vivo on 35 patients harboring internal carotid artery (ICA) aneurysms indicated for endovascular treatments requiring 3DRA imaging. The in vitro 2D- and 3D-PCMRI mean flow rates assessed with partial volume correction showed very low sensitivity to the acquisition resolution above ≈2 voxels per vessel diameter while uncorrected flow rates deviated critically when decreasing the spatial resolution. 3D-PCMRI flow rates measured in vivo in ICA agreed very well with 2D-PCMRI data and a good flow conservation was observed at the C7 bifurcation. Globally, partial volume correction led to 10-15% lower flow rates than uncorrected values as those reported in most of the published studies on intracranial flows. Partial volume correction may improve the accuracy of PCMRI flow rate measurements especially in small vessels such as intracranial arteries. Magn Reson Med 79:129-140, 2018. © 2017 International Society for Magnetic Resonance in Medicine.

Comparison of eye-lens doses imparted during interventional and non-interventional neuroimaging techniques for assessment of intracranial aneurysms

BackgroundA neurointerventional examination of intracranial aneurysms often involves the eye lens in the primary beam of radiation.ObjectiveTo assess and compare eye-lens doses imparted during interventional and non-interventional imaging techniques for...