Evaluation of post-procedure changes in aneurysmal lumen following detachable coil-placement using multi-planar reconstruction of high-field (3.0T) magnetic resonance angiography

Calvarial diploic venous channels: delineation with maximal intensity projection technique

PURPOSE

To date, very few studies have explored the three-dimensional architecture of calvarial diploic venous channels (CDVCs). This study aimed to characterize the three-dimensional architecture of CDVCs using maximum intensity projection (MIP) images based on contrast-enhanced magnetic resonance imaging (MRI).

METHODS

A total of 77 patients with intact calvarial hemispheres and underlying dura mater and dural sinuses underwent contrast-enhanced MRI. Among them, we extracted the data of 49 with at least a part of the major CDVC pathways identified on the MIP images for analysis.

RESULTS

On serial contrast-enhanced MRI images, the CDVCs were commonly detected as curvilinear structures with inhomogeneous diameters and tributaries, while the MIP images delineated the three-dimensional architecture of the developed CDVC pathways. More than such CDVC pathway was entirely delineated on the right in 67.3% and on the left in 71.4%, most frequently in the frontal and temporal regions, with their connecting sites to the sphenoparietal and superior sagittal sinuses. The morphology, distribution, and course of the identified CDVCs were highly variable. In 55.1%, the CDVCs formed fenestrations that were variable in size, shape, and number.

CONCLUSIONS

The developed CDVC pathways may be characterized by morphological variability and fenestrations. Thin-sliced, contrast-enhanced MRI is useful to depict diploic veins, while MIP images allow for better appreciation of the entire course of the developed CDVC pathways. Traumatic and intraoperative disconnection between the dura mater overlying the dural sinuses and the adjacent inner table of the skull can cause epidural venous bleeding.

Inferior sagittal sinus: magnetic resonance imaging study

PURPOSE

To date, no study has explored the inferior sagittal sinus (ISS) using neuroimaging modalities. This investigation aimed to characterize it using magnetic resonance imaging (MRI).

METHODS

A total of 77 patients with intact cerebral hemispheres and covering meninges underwent thin-sliced, contrast-enhanced MRI.

RESULTS

The ISS was well delineated as a linear structure with a constant diameter in 97% of the patients. The maximum intensity projection (MIP) images well delineated the three-dimensional architecture of the ISS and relevant veins. The identified ISSs could be classified into three different types, with the underdeveloped type being the most frequent at 47%. In addition, the ISSs showed considerable variability both in the original site and course along the lower margin of the falx cerebri. Furthermore, in 22% of the cases, fenestrations were identified in the falx cerebri adjacent to or near the ISS. More than 70% of them were located in the middle third of the falx, followed by the anterior and middle thirds of the falx.

CONCLUSIONS

The ISS is a constant venous structure characterized by morphological variability and may function as an adjunctive or assistive venous drainage route. Thin-sliced, post-contrast-enhanced sagittal MRI combined with MIP imaging is useful for exploring the ISS.

Concurrent use of the Pipeline Embolization Device and coils for intracranial aneurysms: technique, safety, and efficacy

OBJECT

The use of the Pipeline Embolization Device (PED) as a sole endovascular modality has been described for the treatment of brain aneurysms. The benefit of using coils concurrently with a limited number of PEDs is not well documented. The authors describe their experience with this technique as well as their midterm clinical and angiographic results.

METHODS

This is a retrospective review of patients treated between 2011 and 2014. The authors placed a minimal number of PEDs with the addition of coils using a "jailed" microcatheter technique. A partially dense coil mass was obtained. Immediate and midterm clinical and angiographic results are reviewed.

RESULTS

The authors treated 27 patients harboring 28 aneurysms using this technique. The mean aneurysm size was 11.9 mm, and the mean neck size was 5.4 mm. A mean of 1.48 PEDs were placed per patient, and a mean of 1.33 PEDs per aneurysm were placed. The Raymond score immediately after PED placement was 2 or 3 in 82.1% of the patients. There were no intraprocedural or postprocedural complications. All PEDs were successfully deployed. No clinical or technical adverse effects related to the coil mass were observed. There were no clinical or radiographic signs of ischemia in this group. At follow-up imaging, complete aneurysm occlusion was demonstrated on the first MR angiogram (3-5 months) in all patients who reached this milestone. Follow-up digital subtraction angiography (5-13 months) confirmed complete occlusion in all patients who reached this milestone. All patients maintained their baseline clinical status.

CONCLUSIONS

The deployment of PEDs with concurrent partially dense coiling is safe and efficacious. This technique achieved early complete occlusion and endovascular reconstruction of the parent vessel, without inducing mass effect. Favorable midterm clinical results were observed in all patients.

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.

Follow-up after embolization of ruptured intracranial aneurysms: a prospective comparison of two-dimensional digital subtraction angiography, three-dimensional digital subtraction angiography, and time-of-flight magnetic resonance angiography

INTRODUCTION

To prospectively compare of the diagnostic value of digital subtraction angiography (DSA) and time-of-flight magnetic resonance angiography (TOF-MRA) in the follow-up of intracranial aneurysms after endovascular treatment.

METHODS

Seventy-two consecutive patients were examined 3 months after the embolization. The index tests included: two-dimensional DSA (2D-DSA), three-dimensional DSA (3D-DSA), and TOF-MRA. The reference test was a retrospective consensus between 2D-DSA images, 3D-DSA images, and source rotational DSA images. The evaluation included: detection of the residual flow, quantification of the flow, and validity of the decision regarding retreatment. Intraobserver agreement and interobserver agreement were determined.

RESULTS

The sensitivity and specificity of residual flow detection ranged from 84.6 % (2D-DSA and TOF-MRA) to 92.3 % (3D-DSA) and from 91.3 % (TOF-MRA) to 97.8 % (3D-DSA), respectively. The accuracy of occlusion degree evaluation ranged from 0.78 (2D-DSA) to 0.92 (3D-DSA, Cohen's kappa). The 2D-DSA method presented lower performance in the decision on retreatment than 3D-DSA (P < 0.05, ROC analysis). The intraobserver agreement was very good for all techniques (κ = 0.80-0.97). The interobserver agreement was moderate for TOF-MRA and very good for 2D-DSA and 3D-DSA (κ = 0.72-0.94).

CONCLUSION

Considering the invasiveness of DSA and the minor difference in the diagnostic performance between 3D-DSA and TOF-MRA, the latter method should be the first-line modality for follow-up after aneurysm embolization.