Comparison of cerebral aneurysm volumes as determined by digitally measured 3D rotational angiography and approximation from three diameters

Three-Dimensional Morphometric Analysis of Anterior Cerebral Circulation Aneurysms

This article assesses the association between anterior circulation morphometry and the presence of intracranial aneurysm using three-dimensional rotational angiography (3DRA). A retrospective analysis at a Peruvian academic medical center between December 2018 and February 2020 identified 206 patients with unruptured intracranial aneurysms and matched controls who underwent 3DRA. Angiographic images were obtained per standard of care, and measurements of the vasculature were performed using 3DRA vascular automated software. A total of 163 aneurysms and 43 control angiograms were evaluated. Women represented 82.5% of the cases and the mean age was 55.9 years (standard deviation ± 14.2). In multivariate analysis, five specific features were found to be statistically significant predictors for presence of an anterior circulation aneurysm: female sex (odds ratio [OR] = 2.71; p  = 0.048), C-shape of the middle cerebral artery (MCA) (OR = 2.73; p  = 0.018), distal internal carotid artery (ICA) diameter (OR = 3.42; p  = 0.012), ICA bifurcation angle (OR = 1.02; p  = 0.036), and length of the carotid siphon (OR = 1.08; p  = 0.047). Features detected on 3DRA suggest morphological characteristics of the ICA and MCA may be predictive for intracranial aneurysm. Our findings build from prior reports by demonstrating five specific patient and imaging features associated with anterior circulation aneurysms. While 3DRA is the standard of care in many settings, medical centers with resource limitations may not have access to this technique. The demographic and morphological features identified in our study may have correlates that if detected on contrast computed tomography or magnetic resonance imaging studies, may be used to help screen for a higher level of care in select patients.

Unruptured untreated intracranial aneurysms: a retrospective analysis of outcomes of 445 aneurysms managed conservatively

BACKGROUND

Factors predicting the growth or rupture of unruptured intracranial aneurysms (UIAs) remain under debate. Increased availability of neuro-imaging has led to increasing incidental findings, therefore understanding the natural history is vital to make appropriate management and follow-up decisions. We analysed a large dataset of UIAs to better identify patients at increased risk, therefore requiring enhanced monitoring and/or prophylactic intervention.

METHODS

Electronic patient records were reviewed from consecutive patients regarding the following data: baseline demographics; past medical and smoking history; indication for imaging detecting the UIA(s); size, location and morphology of UIA(s), duration of imaging follow-up, detection of growth and rupture. Logistic regression was used to identify risk factors for UIA growth or rupture. Subgroup analysis was performed for 'small' aneurysms (<7mm).

RESULTS

445 UIAs in 274 patients were analysed. Total imaging follow-up was 2268 aneurysm-years (median 3.8 years/UIA). 27 UIAs grew (1.2% annually), and 15 ruptured (0.46%). 70.1% of UIAs were detected incidentally. Mean aneurysm diameter was 4.1mm.Logistic regression identified age < 50, autosomal dominant polycystic kidney disease (ADPKD), hypertension and diameter > 7mm as significant risk factors for growth/rupture. Additionally, previous smoking compared to current smoking was a protective factor against growth or rupture, but no significant difference was seen when comparing current- with non-smokers. Small aneurysm subgroup analysis identified diameter > 5mm, age < 50, ADPKD, and ongoing smoking as risk factors. No significant difference was observed in risk between those with and without previous SAH.

CONCLUSIONS

This study underlines the need for imaging surveillance of even small UIAs. Smoking is a modifiable risk factor for growth/rupture of pre-existing aneurysms, while ADPKD is a particularly strong risk factor.

Optimal Woven EndoBridge (WEB) Device Size Selection Using Automated Volumetric Software

INTRODUCTION

Selecting the appropriate Woven EndoBridge (WEB) device sizing for the treatment of wide-neck bifurcation aneurysms (WNBAs) remains challenging. The aim of this study was to evaluate different volumetric-based imaging methodologies to predict an accurate WEB device size selection to result in a successful implantation.

METHODS

All consecutive patients treated with WEB devices for intracranial aneurysms from January 2019 to June 2020 were included. Aneurysm dimensions to calculate aneurysm volumes were measured using three different modalities: automated three-dimensional (3D) digital subtraction angiography (DSA), manual 3D DSA, and two-dimensional (2D) DSA. The device-aneurysm volume (DAV) ratio was defined as device volume divided by the aneurysm volume. WEB volumes and the DAV ratios were used for assessing the device implantation success and follow-up angiographic outcomes at six months. Pearson correlation, Wilcoxon Rank Sum test, and density approximations were used for estimating the WEB volumes and the imaging modality volumes for successful implantation.

RESULTS

A total of 41 patients with 43 aneurysms were included in the study. WEB device and aneurysm volume correlation coefficient was highest for 3D automatic (r = 0.943), followed by 3D manual (r = 0.919), and 2D DSA (r = 0.882) measurements. Measured median volumes were significantly different for 3D automatic and 2D DSA (p = 0.017). The highest rate of successful implantation (87.5%) was between 0.6 and 0.8 DAV ratio.

CONCLUSION

Pre-procedural assessment of DAV ratios may increase WEB device implantation success. Our results suggest that volumetric measurements, especially using automated 3D volumes of the aneurysms, can assist in accurate WEB device size selection.

An Efficient Method for Aneurysm Volume Quantification Applicable in Any Shape and Modalities

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.

Creating Clinically Relevant Aneurysm Sizes in the Rabbit Surgical Elastase Model

BACKGROUND

Creating aneurysm sizes in animal models that resemble human aneurysms is essential to study and test neuroendovascular devices. The commonly used rabbit surgical elastase model, however, produces saccular aneurysms that are smaller than those typically treated in humans. The goal of this study was to determine whether an increased vessel stump length and the addition of calcium chloride to the incubation solution has an effect on the resulting aneurysm size.

METHODS

Using a modified aneurysm creation method, 32 female New Zealand White rabbits underwent aneurysm creation procedures. Subjects were equally allocated into 4 different groups based on vessel stump length (2 cm controls vs. 3 cm) and incubation solution (elastase alone controls vs. a 1:1 mixture of elastase and calcium chloride). At 4 weeks, all animals underwent angiography to determine the resulting aneurysm size by a neurointerventionalist who was blinded to treatment group.

RESULTS

An increase in stump length from 2 cm to 3 cm resulted in a significant increase in the height of aneurysm (P < 0.05). Compared with control animals, the combination of a 3-cm stump length and the addition of calcium chloride to the incubation solution resulted in a significant increase in aneurysm height, width, and volume (P < 0.05).

CONCLUSIONS

Creating larger aneurysms is necessary for the rabbit model to be more clinically relevant. Our study demonstrated that the utilization of a 3-cm vessel stump as well as both calcium chloride and elastase in the incubation solution results in aneurysm sizes that more closely resemble the population of aneurysms treated in humans.

A Supplemental Technique for Preoperative Evaluation of Giant Intracranial Aneurysm

BACKGROUND

 Preoperative planning mainly relies on digital subtraction angiography (DSA) and computed tomography angiography. However, neither technique can reveal thrombi in giant intracranial aneurysms (GIAs). In this study, we aimed to reconstruct the circulating and noncirculating parts of GIAs with the time-of-flight (TOF) and motion-sensitized driven-equilibrium (MSDE) sequences with 3D Slicer to reveal an integrated presentation of GIAs, compare its accuracy, and validate the usefulness for preoperative planning.

MATERIAL AND METHODS

 Patients with GIAs who were treated with microsurgery in our department were included in this study. Both the TOF and MSDE sequence data for each patient were loaded into 3D Slicer for reconstruction and segmentation. The parameters measured by 3D Slicer were compared with those measured by DSA.

RESULTS

 The mean diameter for all GIAs was 28.7 ± 1.5 mm (range, 25.9-31.9 mm). The mean diameter for all GIAs measured by DSA and 3D Slicer was 24.46 ± 5.25 and 28.66 ± 1.48 mm, respectively (t = 4.948, p < 0.01). When only the nonthrombotic GIAs were included, the mean diameter measured by DSA and 3D Slicer was 28.69 ± 2.03 and 28.97 ± 1.79 mm, respectively (t = 1.023, p = 0.323). The mean aneurysmal volume was 8,292.6 ± 1,175.1 mm³ and the mean thrombotic volume was 3,590.0 ± 1,003.7 mm³.

CONCLUSION

 The MSDE sequence brings diagnostic benefits as a comparison to other MRI sequences. Reconstruction of GIAs with 3D Slicer is a low-cost, dependable, and useful supplemental technique for surgical planning.

Cerebral Aneurysm Morphology Before and After Rupture

Background and Purpose—

Using postrupture morphology to predict rupture risk of an intracranial aneurysm may be inaccurate because of possible morphological changes at or around the time of rupture. The present study aims at comparing morphology from angiograms obtained prior to and just after rupture and to evaluate whether postrupture morphology is an adequate surrogate for rupture risk.

Methods—

Case series of 29 aneurysms from a nationwide retrospective data collection. Two neuroradiologists who were blinded to pre- versus postrupture images assessed predefined morphological parameters independently and reached consensus regarding all measurements. Prerupture morphology and respective changes after rupture were quantified and linked to risk factors and to the risk of rupture according to the PHASES (population, hypertension, age, size of aneurysm, earlier subarachnoid hemorrhage from another aneurysm, site of aneurysm) and unruptured intracranial aneurysm treatment (UIAT) scores.

Results—

All 1-dimensional parameter medians were significantly larger after rupture, except neck diameter. Number of aneurysms with daughter sacs was 9 (31%) before and 17 (59%) after rupture ( P =0.005). Aneurysm growth from the images prior to and just after rupture increased with the time elapsed between images. Aneurysms in patients with hypertension were significantly larger at diagnosis. Prerupture morphology did not differ in relation to smoke status. Clinical risk factors were not significantly associated with morphological change.

Conclusions—

The changes in aneurysm morphology observed after rupture reflect the compound effect of time with successive growth and formation of irregularities and the impact of rupture per se. Postrupture morphology should not be considered an adequate surrogate for the prerupture morphology in the evaluation of rupture risk.

Endovascular treatment of aneurysms and platinum coil caliber: Study protocol of a randomized, controlled trial

BACKGROUND

Endovascular coil embolization of cerebral aneurysms is an effective treatment for the prevention of aneurysm rebleeding after subarachnoid hemorrhage. It is also often used in unruptured aneurysms, but it is associated with aneurysm remnants and recurrences in up to 20%-33% of patients. We hypothesized that better aneurysm occlusion rates can be achieved with coils of larger caliber.

METHODS

The Does Embolization with Larger coils lead to better Treatment of Aneurysms (DELTA) trial is an investigator-initiated, multicenter, prospective, randomized, controlled clinical trial. To test the hypothesis that 15-caliber coiling systems are superior to 10-caliber coils, 564 patients with aneurysms measuring 4-12 mm will be randomized 1:1 to embolization with either 10-caliber coils exclusively (control group) or the highest safely achievable proportion of 15-caliber coils (intervention group). The primary efficacy endpoint of the trial is the occurrence of a major recurrence or a residual aneurysm at one year. A pilot phase of 165 patients will be conducted to verify feasibility of the coiling strategy, compliance to treatment allocation, safety of a 15-caliber platinum coil embolization strategy, recruitment rates, and the capacity to improve packing density.

DISCUSSION

The DELTA trial will test the hypothesis that the use of coils of larger caliber can improve angiographic results of endovascular coiling.

Large Residual Volume, Not Low Packing Density, Is the Most Influential Risk Factor for Recanalization after Coil Embolization of Cerebral Aneurysms

Background

Tight coil packing with density of at least 20%–25% is known to be important for preventing recanalization after embolization of cerebral aneurysms. However, large aneurysms sometimes recanalize regardless of the packing density, suggesting that the absolute residual volume which is determined by aneurysm volume and packing density may be more important risk factor for recanalization. To validate this hypothesis, we analyzed the factors affecting the outcomes of treated aneurysms at our institute.

Methods and Findings

We included 355 small and large aneurysms. The following six factors were obtained from every case: aneurysm volume (mL), neck size (mm), packing density (%), residual volume (mL), rupture status at presentation, and stent assistance (with or without stent). The data were then subjected to multivariate logistic regression analysis to identify significant risk factors for recanalization. Recanalization occurred in 61 aneurysms (17.2%). Significant predictors for recanalization were aneurysm volume (odds ratio, 15.3; P < 0.001) and residual volume (odds ratio, 30.9; P < 0.001), but not packing density (odds ratio, 0.98; P = 0.341). These results showed that for each 0.1-mL increase in aneurysm volume and residual volume, the risk of recanalization increased by 1.3 times and 1.4 times, respectively.

Conclusions

The most influential risk factor for recanalization after coil embolization was residual volume, not packing density. The larger the aneurysm volume, the greater the packing density has to be to minimize the residual volume and risk of recanalization. Since tight coil packing has already been aimed, further innovation of coil property or embolization technique may be needed. Otherwise, different treatment modality such as flow diverter or parent artery occlusion may have to be considered.

The significant impact of framing coils on long-term outcomes in endovascular coiling for intracranial aneurysms: how to select an appropriate framing coil

OBJECTIVE The importance of a framing coil (FC)-the first coil inserted into an aneurysm during endovascular coiling, also called a lead coil or a first coil-is recognized, but its impact on long-term outcomes, including recanalization and retreatment, is not well established. The purposes of this study were to test the hypothesis that the FC is a significant factor for aneurysmal recurrence and to provide some insights on appropriate FC selection. METHODS The authors retrospectively reviewed endovascular coiling for 280 unruptured intracranial aneurysms and gathered data on age, sex, aneurysm location, aneurysm morphology, maximal size, neck width, adjunctive techniques, recanalization, retreatment, follow-up periods, total volume packing density (VPD), volume packing density of the FC, and framing coil percentage (FCP; the percentage of FC volume in total coil volume) to clarify the associated factors for aneurysmal recurrence. RESULTS Of 236 aneurysms included in this study, 33 (14.0%) had recanalization, and 18 (7.6%) needed retreatment during a mean follow-up period of 37.7 ± 16.1 months. In multivariate analysis, aneurysm size (odds ratio [OR] = 1.29, p < 0.001), FCP < 32% (OR 3.54, p = 0.009), and VPD < 25% (OR 2.96, p = 0.015) were significantly associated with recanalization, while aneurysm size (OR 1.25, p < 0.001) and FCP < 32% (OR 6.91, p = 0.017) were significant predictors of retreatment. VPD as a continuous value or VPD with any cutoff value could not predict retreatment with statistical significance in multivariate analysis. CONCLUSIONS FCP, which is equal to the FC volume as a percentage of the total coil volume and is unaffected by the morphology of the aneurysm or the measurement error in aneurysm length, width, or height, is a novel predictor of recanalization and retreatment and is more significantly predictive of retreatment than VPD. To select FCs large enough to meet the condition of FCP ≥ 32% is a potential relevant factor for better long-term outcomes. These findings support our hypothesis that the FC is a significant factor for aneurysmal recurrence.

Effects of anatomic characteristics of aneurysms on packing density in endovascular coil embolization: analysis of a single center's experience

When embolizing cerebral aneurysms, dense coil packing may prevent recanalization but this may be influenced by the aneurysm morphology. We have analyzed retrospectively the relationship between anatomic features and the volumetric coil packing density. We analyzed 452 aneurysms in 434 patients treated by coil embolization without stenting, expressing packing density as volume embolization ratio (VER, volume of inserted coils/aneurysm volume). Six morphological variables (neck width, height, maximum diameter, dome to neck ratio (DNR), and aspect ratio), aneurysm location, and whether the aneurysm was ruptured or unruptured were analyzed with respect to dense (VER ≥20%) or loose (VER <20%) packing densities, using logistic regression analysis and ROC analysis. Among 452 aneurysms, VERs >20% were achieved for 272 aneurysms, with a mean VER of 24.7%. The mean VER of the remaining 180 aneurysms was 15.6%. In univariate analyses, the predictors for dense packing were having an anterior circulation, DNR, aspect ratio, and neck width. In multivariate analysis, the independent predictors were smaller neck width (odds ratio (OR) 0.8735; 95% confidence interval (CI) 0.7635-0.9993) and larger aspect ratio (OR 1.6679; 95% CI 1.0460-2.6594). ROC analysis showed optimal cutoff values for an aspect ratio of 1.35 (sensitivity 69.5%, specificity 51.7%) and a neck width of 3.13 mm (sensitivity 51.1%, specificity 27.8%). Although dense coil packing is still difficult to achieve in wide-necked aneurysms without the use of stents, packing with VER >20% is expected to be achieved when the height is 1.35 times larger than the neck width.

Use of a new soft and long coil reduces the number of coils to embolize a small aneurysm

BACKGROUND

In embolizing a cerebral aneurysm, achievement of a high-volume embolization ratio (VER: volume of inserted coils / aneurysm volume) is important because it may prevent coil compaction and recanalization. The goal of the study is to examine whether use of softer and longer coils gives an adequate VER with fewer coils, particularly for small aneurysms.

METHODS

Aneurysm volumes, VERs, and numbers of inserted coils were investigated in 23 cases of small aneurysms embolized using Infini coils, a long soft coil with a primary diameter of 0.010 inches (Infini group). An aneurysm volume- and VER-matched control (non-Infini) group of 59 cases was selected from patients treated at our facility. Data were also compared between subgroups of patients (n = 18 and n = 34 in the Infini and non-Infini groups, respectively) who were not treated with thicker coils with primary diameters of 0.0135-0.015 inches (18-type coils), since these coils affect the number of coils by increasing VER rapidly.

RESULTS

Average aneurysm volumes and VERs did not differ significantly between the Infini and non-Infini groups. Significantly fewer coils were used per 0.1 ml aneurysm volume in the Infini group (4.08 coils in average) compared with the non-Infini group (5.67) (p < 0.001). In the non-18-type subgroups, the number of coils used remained significantly smaller in the Infini group (4.49) compared with the non-Infini group (6.72), (p < 0.001).

CONCLUSION

To achieve VER ≥20%, use of Infini coils significantly decreased the number of coils required per unit volume of a small aneurysm.

Quantifying unruptured giant intracranial aneurysms by measuring diameter and volume--a comparative analysis of 69 cases

BACKGROUND

Intracranial aneurysms (IA) are usually quantified according to their largest diameter. However, volumetry has recently been increasingly conducted as well, especially in giant intracranial aneurysms (GIAs). Since so far the true value of GIA volumetry is unknown, we designed a trial to examine correlations between GIA diameter and volume with special focus on clinical implications.

METHODS

Magnetic resonance imaging of 69 unruptured GIAs in 66 patients was retrospectively evaluated. The largest diameter and volume were measured. Also, potential associations to the patients' clinical conditions were examined.

RESULTS

Comparing GIA sizes of our patient cohort produced different results depending on whether GIA diameter or volume was measured. Measuring the diameter identified posterior circulation GIAs as the largest ones (39.2 mm, IQR 37.3-48.3), while measuring the volume found GIAs of the MCA to be the largest ones (12.3 cm(3), IQR 7.2-27.8). A correlation of GIA diameter and volume was only found in anterior circulation GIAs, which were predominantly saccular in shape, but not in those of the posterior circulation, of which most were fusiform. Neither GIA diameter nor GIA volume but only GIA location was associated with neurological deficits.

CONCLUSION

Diameter and volume measurements are not interchangeable modes of GIA quantification. Our data suggest that the idea of distinguishing different sizes of GIA may be clinically less relevant than examining their location, shape or mass effect.

Volume measurement of the intracranial aneurysm: a discussion and comparison of the alternatives to manual segmentation

OBJECTIVE

Several modalities are available for volumetric measurement of the intracranial aneurysm. We discuss the challenges involved in manual segmentation, and analyze the application of alternative methods using automatic segmentation and geometric formulae in measurement of aneurysm volumes and coil packing density.

METHODS

The volumes and morphology of 38 aneurysms treated with endovascular coiling at a single center were measured using three-dimensional rotational angiography (3DRA) reconstruction software using automatic segmentation. Aneurysm volumes were also calculated from their height, width, depth, size of neck, and assumed shape in 3DRA images using simple geometric formulae. The aneurysm volumes were dichotomized as "small" or "large" using the median volume of the studied population (54 mm(3)) measured by automatic segmentation as the cut-off value for further statistical analysis.

RESULTS

A greater proportion of aneurysms were categorized as being "small" when geometric formulae were applied. The median aneurysm volumes obtained were 54.5 mm(3) by 3DRA software, and 30.6 mm(3) using mathematical equations. An underestimation of aneurysm volume with a resultant overestimation in the calculated coil packing density (p = 0.002) was observed.

CONCLUSION

Caution must be exercised in the application of simple geometric formulae in the management of intracranial aneurysms as volumes may potentially be underestimated and packing densities falsely elevated. Future research should focus on validation of automatic segmentation in volumetric measurement and improving its accuracy to enhance its application in clinical practice.

Influence of observers, threshold values, and measurement methods on volumetric analysis of cerebral aneurysms with three-dimensional rotational angiography

Introduction

Exact measurements of cerebral aneurysms are important in terms of their treatment. However, there is no definitive way to estimate the exact volume of an aneurysm. Our aim was to compare aneurysm volume measured under different conditions: threshold values, observers, and measurement methods.

Methods

40 aneurysms and 7 phantom models were included in the study. Three-dimensional rotational angiography was used, and volumes were compared based on the following factors: two methods (two-dimensional formula calculation and three-dimensional software measurement); three observers; and three threshold values for imaging. In addition, in the phantom models, measured volumes were compared with real volumes. The consistency of the volume measurements under different conditions was assessed using the intraclass correlation coefficient (ICC).

Results

The consistency of the measured volumes was excellent in both the patient aneurysms (ICC >0.98) and phantom models (ICC >0.95), irrespective of the influencing factors. Median volume differences were small for observers, threshold values, and methods. When the measured and real volumes of the phantom models were compared, the software measurement achieved the highest reproducibility for real volumes compared with the formula calculation (ICC=0.86–0.93 vs 0.71–0.80).

Conclusions

Measurement of aneurysm volume showed high agreement within each influencing factor, such as methods, observers, and threshold values.

Comparison between routine cylindrical cerebral aneurysm volume approximation and three-dimensional volume measurements in experimental aneurysms

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.