Risk of Branch Occlusion and Ischemic Complications with the Pipeline Embolization Device in the Treatment of Posterior Circulation Aneurysms

BACKGROUND AND PURPOSE

Flow diversion with the Pipeline Embolization Device is increasingly used for endovascular treatment of intracranial aneurysms due to high reported obliteration rates and low associated morbidity. While obliteration of covered branches in the anterior circulation is generally asymptomatic, this has not been studied within the posterior circulation. The aim of this study was to evaluate the association between branch coverage and occlusion, as well as associated ischemic events in a cohort of patients with posterior circulation aneurysms treated with the Pipeline Embolization Device.

MATERIALS AND METHODS

A retrospective review of prospectively maintained databases at 8 academic institutions from 2009 to 2016 was performed to identify patients with posterior circulation aneurysms treated with the Pipeline Embolization Device. Branch coverage following placement was evaluated, including the posterior inferior cerebellar artery, anterior inferior cerebellar artery, superior cerebellar artery, and posterior cerebral artery. If the Pipeline Embolization Device crossed the ostia of the contralateral vertebral artery, its long-term patency was assessed as well.

RESULTS

A cohort of 129 consecutive patients underwent treatment of 131 posterior circulation aneurysms with the Pipeline Embolization Device. Adjunctive coiling was used in 40 (31.0%) procedures. One or more branches were covered in 103 (79.8%) procedures. At a median follow-up of 11 months, 11% were occluded, most frequently the vertebral artery (34.8%). Branch obliteration was most common among asymptomatic aneurysms (P < .001). Ischemic complications occurred in 29 (22.5%) procedures. On multivariable analysis, there was no significant difference in ischemic complications in cases in which a branch was covered (P = .24) or occluded (P = .16).

CONCLUSIONS

There was a low occlusion incidence in end arteries following branch coverage at last follow-up. The incidence was higher in the posterior cerebral artery and vertebral artery where collateral supply is high. Branch occlusion was not associated with a significant increase in ischemic complications.

Treatment of Tandem Internal Carotid Artery Aneurysms Using a Single Pipeline Embolization Device: Evaluation of Safety and Efficacy

BACKGROUND AND PURPOSE

Tandem aneurysms are defined as multiple aneurysms located in close proximity on the same parent vessel. Endovascular treatment of these aneurysms has rarely been reported. Our aim was to evaluate the safety and efficacy of a single Pipeline Embolization Device for the treatment of tandem aneurysms of the internal carotid artery.

MATERIALS AND METHODS

A retrospective analysis of consecutive aneurysms treated with the Pipeline Embolization Device between 2009 and 2016 at 3 institutions in the United States was performed. Cases included aneurysms of the ICA treated with a single Pipeline Embolization Device, and they were divided into tandem versus solitary. Angiographic and clinical outcomes were compared.

RESULTS

The solitary group (median age, 58 years) underwent 184 Pipeline Embolization Device procedures for 184 aneurysms. The tandem group (median age, 50.5 years) underwent 34 procedures for 78 aneurysms. Aneurysms were primarily located along the paraophthalmic segment of the ICA in both the single and tandem groups (72.3% versus 78.2%, respectively, P = .53). The median maximal diameters in the solitary and tandem groups were 6.2 and 6.7 mm, respectively. Complete occlusion on the last angiographic follow-up was achieved in 75.1% of aneurysms in the single compared with 88.6%% in the tandem group (P = .06). Symptomatic thromboembolic complications were encountered in 2.7% and 8.8% of procedures in the single and tandem groups, respectively (P = .08).

CONCLUSIONS

Tandem aneurysms of the ICA can be treated with a single Pipeline Embolization Device with high rates of complete occlusion. While there appeared to be a trend toward higher thromboembolic complication rates, this did not reach statistical significance.

Inner ear volumetric measurements using high-resolution 3D T2-weighted fast spin-echo MR imaging: initial experience in healthy subjects

BACKGROUND AND PURPOSE

Adult size is achieved in the inner ear labyrinth by approximately 25 weeks' gestation, and minimal variability in age, sex, side, and race is found after birth. In this study, we opted to determine the reproducibility of inner ear volumetric measurements generated from high-resolution heavily T2-weighted 3D fast spin-echo MR images.

METHODS

The temporal bones of 23 volunteers were imaged using a heavily T2-weighted 3D fast spin-echo MR imaging technique. The images were assessed by a neuroradiologist for the presence of inner ear configurational anomalies and, most important, for complete coverage of the inner ear labyrinth. Subsequently, the volume of the fluid in the inner ear was determined by two observers using a semiautomated segmentation algorithm. The mean, SD, range, and coefficient of variation of fluid volume in the inner ear were calculated. Age-, sex-, and side-related differences in the inner ear volumetric measurements were evaluated using analysis of variance. Interrater consistency in the inner ear volumetric measurements was evaluated by comparing the calculated coefficients of reliability.

RESULTS

Volumetric measurements were available from 46 inner ears in 23 volunteers. The mean volume was 227.8 mm3 (SD, 24.4 mm3), and the coefficient of variation was 10.7%. No age-, sex-, or side-related differences in the inner ear volumetric measurements were found (F ratios were 4.33, 5.04, and 0.26, respectively). Interrater consistency, as assessed by the coefficient of reliability, was 5.3%.

CONCLUSION

Reproducible volumetric measurements of the inner ear labyrinth can be obtained by applying a semiautomated segmentation algorithm to a heavily T2-weighted 3D fast spin-echo MR imaging data set. These volumetric measurements may help identify patients with congenital sensorineural hearing loss and normal inner ear configuration.

Fast inversion-recovery MR: the effect of hybrid RARE readout on the null points of fat and cerebrospinal fluid

PURPOSE

To evaluate the effect of the hybrid RARE (rapid acquisition with relaxation enhancement) readout, commonly coupled to inversion-recovery pulse sequences, on the null inversiton time (TI) of fluid and fat using both phantoms and human volunteers.

METHODS

Two phantoms, simulating fat (phantom A) and cerebrospinal fluid (phantom B), respectively, were imaged using a fast inversion-recovery sequence that coupled an inversion-recovery preparation pulse to a hybrid RARE readout. At repetition times (TRs) ranging from 700 to 20,000, the TI necessary to null the signal from each phantom (null TI) was determined for an echo train length of 4, 6, 8, 10, 12, 14, 16, 18, and 20, respectively. Plots of null TI versus echo train length at different TRs were generated for both phantoms. Fast inversion-recovery MR imaging of the cervical spine and brain was performed in healthy volunteers. At a fixed TR and TI, the adequacy of signal suppression from bone marrow and cerebrospinal fluid was assessed as a function of echo train length.

RESULTS

There was a gradual decrease of null TI for both phantoms with echo train length. This decrease persisted at longer TRs for phantom B (T1 = 3175 +/- 70 milliseconds) than for phantom A (T1 = 218 +/- 5 milliseconds). In the human volunteers, there was a gradual loss of suppression of signal from bone marrow and cerebrospinal fluid, with changes in the hybrid RARE readout.

CONCLUSION

To optimize specific tissue suppression, radiologists implementing fast inversion-recovery MR imaging should be aware of the effects of the hybrid RARE readout on null TI.