Fig 2 - uploaded by Michel Piotin
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A, Volume determination with the 3D-RA software of the 50-mm-diameter iron ball displayed with surface- shaded display. The software is giving a volume of 67.875 mm 3 , whereas the ellipsoid calculation is giving 65.45 mm 3 .
Source publication
The purpose of this study was to compare the volumetric results of intracranial aneurysms obtained by calculation of the volume of an ellipsoid with those obtained with 3D rotational angiography (3D-RA).
First, the precision of 3D-RA in the assessment of volumetric measurement of intracranial aneurysm had to be established. The 3D-RA gave an overes...
Context in source publication
Context 1
... a start, our system was tested with 2 iron balls of 5 and 50 mm in diameter (Fig 1), which were imaged by using the same acquisition parameters routinely used in the clinical setting (Integris 3D-RA; Philips, Best, the Netherlands). The 3D-RA tech- nique overestimated the volume of the 50-mm ball by 4% and that of the 5-mm ball by 5.5% (Fig 2). This small discrepancy between the actual volumes and those obtained with the 3D-RA system software therefore raised concerns and called into question the validity of the latter method. ...
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Knowledge of brain aneurysm dimensions is essential in min- imally invasive surgical interventions using Guglielmi Detachable Coils. These parameters are obtained in clinical routine using 2D maximum intensity projection images. Automated quantification of the three di- mensional structure of aneurysms directly from the 3D data set may be used to p...
Citations
... These days, we can employ three-dimensional rotational angiography (3DRA) to identify the actual aneurysm configuration. 3DRA also enables for the determination of aneurysm size [7]. Sharif et al. [8] employed computational fluid dynamics (CFD) for the first time to investigate hemodynamic characteristics for saccular aneurysms treated with Woven EndoBridge (WEB). ...
... Nonetheless, it has been widely used in studies and applied to commercial software for calculating coil packing density. Other AVQ methods have been introduced and improved upon with 3-dimensional (3D) angiographic data, but these also have limitations related to imaging modality, angiography equipment (workstations), and the particular software utilized 2,5,6,8,9,23,26) . Therefore, the applicability of these methods to clinical use and research is https://doi.org/10.3340/jkns.2020.0255 ...
Objective:
Aneurysm volume quantification (AVQ) using the equation of ellipsoid volume is widely used although it is inaccurate. Furthermore, AVQ with 3-dimensional (3D) rendered data has limitations in general use. A novel universal method for AVQ is introduced for any diagnostic modality and application to any shape of aneurysms.
Methods:
Relevant AVQ studies published from January 1997 to June 2019 were identified to determine common methods of AVQ. The basic idea is to eliminate the normal artery volume from 3D model with the aneurysm. After Digital Imaging and Communications in Medicine (DICOM) data is converted and exported to stereolithography (STL) file format, the 3D STL model is modified to remove the aneurysm and the volume difference between the 3D model with/without the aneurysm is defined as the aneurysm volume. Fifty randomly selected aneurysms from DICOM database were used to validate the different AVQ methods.
Results:
We reviewed and categorized AVQ methods in 121 studies. Approximately 60% used the ellipsoid method, while 24% used the 3D model. For 50 randomly selected aneurysms, volumes were measured using 3D Slicer, RadiAnt, and ellipsoid method. Using 3D Slicer as the reference, the ratios of mean difference to mean volume obtained by RadiAnt and ellipsoid method were -1.21±7.46% and 4.04±30.54%, respectively. The deviations between RadiAnt and 3D Slicer were small despite of aneurysm shapes, but those of ellipsoid method and 3D Slicer were large.
Conclusion:
In spite of inaccuracy, ellipsoid method is still mostly used. We propose a novel universal method for AVQ that is valid, low cost, and easy to use.
... Aneurysm volumes calculation is important to choose endovascular treatment modalities and to plan the optimal number of coils to be inserted for AAA SE. Many authors have previously reported the difficulty of determining true aneurysm volume [20][21][22][23]. As noted by Piotin et al. [21] and Sluzewski et al. [22], volume calculations based on 2-dimensional images can be adversely affected by the lack of a fiduciary marker and irregular aneurysm shapes, as well as simplistic spherical or elliptical geometric models can be inaccurate. ...
... Many authors have previously reported the difficulty of determining true aneurysm volume [20][21][22][23]. As noted by Piotin et al. [21] and Sluzewski et al. [22], volume calculations based on 2-dimensional images can be adversely affected by the lack of a fiduciary marker and irregular aneurysm shapes, as well as simplistic spherical or elliptical geometric models can be inaccurate. ...
Background: Endovascular aneurysm repair (EVAR) has become the primary choice of treatment for abdominal aortic aneurysm (AAA) and preventive intraoperative AAA sac embolization (SE) is an effective way to reduce endoleaks after EVAR. Preoperative planning of AAA SE has not been standardized yet, and typically requires a quite long and operator-dependent procedure using standard EVAR planning software. Methods: We introduce ‘EVAR-eaSE’, a software tool that we have developed to help vascular surgeons to plan the optimal SE procedure during EVAR, providing semi-automatic AAA segmentation and 3D modeling starting from patient scans, and then computing the aneurysm volumes. A preliminary accuracy evaluation on radiological phantoms, and a comparison with the commercial 3Mensio software for EVAR planning are carried out. Results: EVAR-eaSE software showed a good level of accuracy in aneurysm volume reconstruction and calculation (mean difference of 2.5% between real and segmented phantom volumes). A strong positive correlation (r = 0.940, r = 0.954, p < 0.001) was found between EVAR-eaSE computation of AAA Lumen and AAA Total volumes and the same measurements obtained with 3Mensio, for a database of 26 AAA cases. Conclusions: EVAR-eaSE demonstrated to be an easy-to-use, objective and accurate tool to assist the vascular surgeons in preoperative planning of SE during EVAR.
... A limitation in this study is that the aneurysms were evaluated with CT or CT angiography. A 3D rotational DSA is considered superior to other imaging modalities especially in aneurysms with irregular shape [18]. The anatomical characteristics of the aneurysm after rupture could also change [20]. ...
In patients with aneurysmal subarachnoid hemorrhage (aSAH) and multiple aneurysms, there is a need to objectively identify the ruptured aneurysm. Additionally, studying the intra-individual rupture risk of multiple aneurysms eliminates extrinsic risk factors and allows a focus on anatomical factors, which could be extrapolated to patients with single aneurysms too. Retrospective bi-center study (Department of Neurosurgery of the University Hospital Duesseldorf and Bern) on patients with multiple aneurysms and subarachnoid hemorrhage caused by the rupture of one of them. Parameters investigated were height, width, neck, shape, inflow angle, diameter of the proximal and distal arteries, width/neck ratio, height/width ratio, height/neck ratio, and localization. Statistical analysis and logistic regressions were performed by the R program, version 3.4.3. N = 186 patients with aSAH and multiple aneurysms were treated in either department from 2008 to 2016 (Bern: 2008–2016, 725 patients and 100 multiple aneurysms, Duesseldorf: 2012–2016, 355 patients, 86 multiple aneurysms). The mean age was 57 years. N = 119 patients had 2 aneurysms, N = 52 patients had 3 aneurysms, N = 14 had 4 aneurysms and N = 1 had 5 aneurysms. Eighty-four percent of ruptured aneurysms were significantly larger than the largest unruptured. Multilobularity of ruptured aneurysms was significantly higher than in unruptured. Metric variables describing the geometry (height, width, etc.) and shape are the most predictive for rupture. One or two of them alone are already reliable predictors. Ratios are completely redundant in saccular aneurysms.
... Accurate and fast predictions of aneurysm volume can have a variety of clinical and research applications. Previous work has found that simplified geometric approximations of aneurysm volume are inherently inferior to voxel summation, particularly for irregularly shaped aneurysms [19,20]. On the other hand, user-performed segmentation for full voxel counting and summation is time-consuming. ...
Aneurysm size correlates with rupture risk and is important for treatment planning. User annotation of aneurysm size is slow and tedious, particularly for large data sets. Geometric shortcuts to compute size have been shown to be inaccurate, particularly for nonstandard aneurysm geometries. To develop and train a convolutional neural network (CNN) to detect and measure cerebral aneurysms from magnetic resonance angiography (MRA) automatically and without geometric shortcuts. In step 1, a CNN based on the U-net architecture was trained on 250 MRA maximum intensity projection (MIP) images, then applied to a testing set. In step 2, the trained CNN was applied to a separate set of 14 basilar tip aneurysms for size prediction. Step 1—the CNN successfully identified aneurysms in 85/86 (98.8% of) testing set cases, with a receiver operating characteristic (ROC) area-under-the-curve of 0.87. Step 2—automated basilar tip aneurysm linear size differed from radiologist-traced aneurysm size on average by 2.01 mm, or 30%. The CNN aneurysm area differed from radiologist-derived area on average by 8.1 mm² or 27%. CNN correctly predicted the area trend for the set of aneurysms. This approach is to our knowledge the first using CNNs to derive aneurysm size. In particular, we demonstrate the clinically pertinent application of computing maximal aneurysm one-dimensional size and two-dimensional area. We propose that future work can apply this to facilitate pre-treatment planning and possibly identify previously missed aneurysms in retrospective assessment.
... CTA computed tomography angiography, 3D Angio tridimensional rotational angiography. 3D-CTA tridimensional computed tomography angiography CTA computed tomography angiography measurements versus tridimensional rotational angiography, revealing more discrepancies done by algebraic approaches [10]. Geometric measurements are simplistic because they reflect inaccuracy secondary to irregular aneurysm shapes and morphology, and they do not take into account adjacent blebs or sacs, however, in important limiting factor in rotational angiography is the dependence of adequate filling in order to achieve full reconstructions, which may be altered by patient's movement, distortions in the acquisition system secondary to vibration, contrast medium dilution during blood flow and a poor image quality [10,11]. ...
... 3D-CTA tridimensional computed tomography angiography CTA computed tomography angiography measurements versus tridimensional rotational angiography, revealing more discrepancies done by algebraic approaches [10]. Geometric measurements are simplistic because they reflect inaccuracy secondary to irregular aneurysm shapes and morphology, and they do not take into account adjacent blebs or sacs, however, in important limiting factor in rotational angiography is the dependence of adequate filling in order to achieve full reconstructions, which may be altered by patient's movement, distortions in the acquisition system secondary to vibration, contrast medium dilution during blood flow and a poor image quality [10,11]. An inherent weakness found in this study was the unawareness of the real volume of each aneurysm, since all the images processed represent indirectly the real vascular anatomy of each patient. ...
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© software measurements (angiography-based) may be the most accurate method to calculate aneurysm volume.
... The assessment of aneurysm volume, coil volume, and packing attenuation Aneurysm volume was calculated by assuming that aneurysms are ellipsoid according to the following equation 12 : aneurysm volume ¼ 4/3p(a/2)(b/2)(a þ b)/ 4, in which a is the largest horizontal diameter and b is the largest vertical diameter, with a and b being perpendicular. The total diameter of each aneurysm was measured on the 3D-RA images. ...
Aims:
Soft and small coils are known to be appropriate for the treatment of small aneurysms. The purpose of this study was to determine whether the new HyperSoft® helical coil, which is softer and smaller than its predecessors, has any effect on the packing performance in a matched-pair study with an old HyperSoft® helical coil.
Materials and methods:
Thirty-six consecutive patients harboring 43 cerebral aneurysms treated with new HyperSofts were included in this study. Forty-one aneurysms treated with old HyperSofts were identified from our database as matched controls based on similar volumes and locations. Packing attenuation, adverse events during the procedures, and angiographic occlusions were observed and compared between the two groups.
Results:
The mean packing density was significantly higher in the new HyperSoft® group compared to the control group (35.5% vs. 26.9%), and a larger proportion of the aneurysms embolized with the 1.5 mm size coil, which has higher packing density. There was no difference in immediate and midterm angiographic outcomes. There was no difference in the rate of intraprocedural perforation, but there was no intraprocedural rupture related to the 1.5 mm coil.
Conclusions:
The use of new HyperSoft® helical coils allows higher packing density comparable with the old technology. New HyperSoft® coils, especially those with 1.5 mm loop diameter, can be expected to fill smaller residual spaces in small aneurysms and may be helpful in preventing recanalization.
... Although the correlations are high, many cases of significant disagreement do exist. This can be attributed to the fact that the ellipsoidal approximation may not be a reliable method for volume calculations from neuroradiologist measurement of three aneurysm dimensions as pointed out by Piotin et al. 15 and not necessarily to the ability of the biplane 3D model to estimate sac volume accurately. ...
The International Study of Unruptured Intracranial Aneurysms (ISUIA) is an epidemiologic international study of the natural history of unruptured intracranial aneurysms that enrolled 4,060 subjects. A conventional biplane cerebral angiogram available for central review was required for enrollment resulting in a large database. Data on aneurysms that ruptured during follow-up of the 1,692 untreated subjects provides an opportunity to investigate the anatomic features that may be predictive of future rupture. The objective of the study is to develop and test a method for three-dimensional (3D) shape reconstruction of aneurysms using biplane angiographic data in the ISUIA for retrospective morphometric assessment. Beginning with the two boundaries of the biplane views, curve morphing techniques were employed to estimate a number of intermediate boundaries around the aneurysm sac resulting in the creation of a 3D sac surface. The method was tested using simulated biplane “angiograms” of pre-reconstructed 3D models of patient-specific aneurysms. An algorithm to perform the image analysis was developed, and the morphometric indices of 150 intracranial aneurysms in the ISUIA database were estimated. Simultaneously, experienced neuroradiologists made manual measurements of key dimensions in the sac from the biplane angiograms for all cases. 3D reconstructions using our proposed method matched well with the original pre-reconstructed 3D geometries and were consistent with manual measurements of the neuroradiologists for the ISUIA aneurysms. A method for reconstructing the 3D geometry of the intracranial aneurysm sac from biplane angiograms in the ISUIA database with reasonable fidelity has been developed.
... Knowledge of the exact aneurysm volume is also crucial for an optimized application of coils since Sluzewski et al. showed that coil impaction did not occur in aneurysms filled .24% of their volume, 22 or new endovascular devices such as embolic polymers. 23 Sensitive tools to detect high risk of aneurysm rupture are sought for not only in treatment of cerebral aneurysm but also in the follow-up of primarily untreated aneurysms. Increase in aneurysm size is generally considered an important risk factor, 18 and CE-MRA is studied as a tool to monitor aneurysm growth. ...
... For bilobular aneurysms, it may be the heart-shaped angioarchitecture of the aneurysm, which visually even lacks similarity to a cylinder. These results are supported by studies of Piotin et al. 23 and Sadato and colleagues 25 that compared ellipsoid volume calculation using 2D-DSA and 3D-DSA in human aneurysms. They described the formula as inadequate for irregularly shaped lesions, and the study of Sadato et al. identifies an up to 50% underestimation of aneurysms by this formula. ...
Objectives:
Aneurysm volume is routinely approximated calculating cylindrical volumes. Exact aneurysm volume assessment is crucial for liquid polymer embolization. The aim of this study was to compare simple cylindrical volume approximations with direct multiplanar reconstruction (MPR) segmentational volumetry in a saccular/complex experimental rabbit bifurcation aneurysm model.
Methods:
In 12 female New Zealand white rabbits, saccular, broad-based, bilobular, and bisaccular aneurysms (three of each) were created using the rabbit venous pouch bifurcation model. Contrast-enhanced magnetic resonance angiography (CE-MRA) was performed, and maximal intensity projection (MIP) reconstructions as well as an MPR dataset were acquired. Aneurysm width and length were measured in MIP images, and the volume was approximated calculating cylindrical volumes. Three-dimensional (3D) segmentational volumetry using the MPR dataset was performed in a semi-automated manner.
Results:
Maximal intensity projection cylindrical volumes ranged from 53·6 to 503·5 mm(3) (mean 186·5±118 mm(3)). Multiplanar reconstruction segmentation-based volumes ranged from 74·7 to 581·0 mm(3) (mean 202·2±133 mm(3)). The mean relative difference between MIP cylindrical and MPR segmentation volume calculation was 24·7% (range -77·5 to +50·8%). Only 4 of 12 MPR segmentational volumes were within a 10% range of results calculated for MIP cylindrical volume, and 3 of those were in broad-based aneurysms.
Conclusion:
This descriptive study demonstrates that estimated MIP cylindrical volumes differ from those measured by MPR segmentation volumetry. With the increasing acquisition of 3D data as 3D-MRA and the increasing need for exact volume determination, studies on the accuracy of computational segmentational volumetry of CE-MRA are necessary.
... With respect to the risk of recanalization, Kaplan-Meier curve showed a higher CR for both the second and third categories compared to the first one and HRs of the second and third categories were found to be similar for AGS and 2DPO. Therefore, we should To reduce these errors in measuring aneurysmal volume, a direct measurement function was added to the 3D workstation 14) . However, it is not also free from errors; manual outlining and segmentation of the aneurysm from the parent artery could vary from person to person; and different window settings for appropriate background noise and aneurysm delineation would present different aneurysmal volumes for a single aneurysm. ...
Several scales are currently used to assess occlusion rates of coiled cerebral aneurysms. This study compared these scales as predictors of recanalization.
Clinical data of 827 patients harboring 901 aneurysms treated by coiling were retrospectively reviewed. Occlusion rates were assessed using angiographic grading scale (AGS), two-dimensional percent occlusion (2DPO), and volumetric packing density (vPD). Every scale had 3 categories. Followed patients were dichotomized into either presence or absence of recanalization. Kaplan-Meier analysis was conducted, and Cox proportional hazards analysis was performed to identify surviving probabilities of recanalization. Lastly, the predictive accuracies of three different scales were measured via Harrell's C index.
The cumulative risk of recanalization was 7% at 12-month, 10% at 24-month, and 13% at 36-month of postembolization, and significantly higher for the second and third categories of every scale (p<0.001). Multivariate-adjusted hazard ratios (HRs) of the second and third categories as compared with the first category of AGS (HR : 3.95 and 4.15, p=0.004 and 0.001) and 2DPO (HR : 4.87 and 3.12, p<0.001 and 0.01) were similar. For vPD, there was no association between occlusion rates and recanalization. The validated and optimism-adjusted C-indices were 0.50 [confidence (CI) : -1.09-2.09], 0.47 (CI : -1.10-2.09) and 0.44 (CI : -1.10-2.08) for AGS, 2DPO, and vPD, respectively.
Total occlusion should be reasonably tried in coiling to maximize the benefit of the treatment. AGS may be the best to predict recanalization, whereas vPD should not be used alone.
