Radiation reduced with flow diversion for treatment of internal carotid artery aneurysms

Geoffrey Colby and Alexander Coon

According to new research, treatment of large and giant proximal internal carotid artery aneurysms using the Pipeline embolisation device (Covidien/Medtronic) requires less radiation, less fluoroscopy time, and less contrast administration than standard coiling techniques. Study authors Geoffrey Colby et al (Johns Hopkins University School of Medicine, Baltimore, USA) say that this further demonstrates the benefits of flow diversion for the treatment of these aneurysms.

The authors explain that since an increasing number of cerebral aneurysms are being treated by endovascular means, there has been a push to reduce radiation exposure to both the patient and the operator.

In this first of its kind study, published in the Journal of NeuroInterventional Surgery, Colby and colleagues retrospectively analysed radiation dose, fluoroscopy time, and contrast dye administration in 55 patients undergoing endovascular treatment of aneurysms ≥10mm from petrous to superior hypophyseal internal carotid aneurysm segments. Thirty-seven patients were treated with the Pipeline device, and 18 patients were treated using traditional coiling techniques.

Colby et al reported a decrease in radiation dose, fluoroscopy time and contrast dye amounts with the Pipeline embolisation device. They write that in the Pipeline device group, average radiation dose was 2840±213mGy, compared with 4010±708mGy in the traditional coiling group (p=0.048; 29% decrease with the Pipeline device). Similarly, mean fluoroscopy time in the Pipeline device group was 56.1±5 minutes versus 85.9±11.9 minutes in the coiling group (p=0.0087; 35% decrease with the Pipeline device). Further, contrast dye amounts were also reduced by 37.5% in the Pipeline group (75±6mL) compared with the coiling group (120±13mL, p=0.0008).

The authors further noted that flow diversion provides additional benefits of decreased radiation exposure as it relates to retreatment.

“This study demonstrated reduced radiation doses when the Pipeline device was used for the initial aneurysm treatment of internal carotid artery aneurysms ≥10mm; however, there are likely extended radiation dose benefits after Pipeline device treatment. Six-month angiographic occlusion rates following Pipeline device treatment range from 81.8% to 94.4%, and there is initial evidence that similar rates can be achieved even sooner in smaller aneurysms. Additionally, once an aneurysm is occluded after Pipeline device embolisation, there has not been a single reported case of recurrence in the literature. Although long-term follow up for these devices in limited, the lack of aneurysm recurrence excludes future radiation exposure from retreatment. In contrast, aneurysms treated by coiling and stent assisted coiling can have recurrence rates of 35.9% and 15.4%, respectively. Retreatment in these cases certainly increases radiation exposure to the patient,” Colby et al write.

They conclude stating that this study “enhances the growing body of literature demonstrating the efficacy and cost effectiveness of flow diversion for the treatment of these difficult aneurysms. Although further studies are necessary, there is a potential health benefit to patients and operators secondary to these lower radiation doses.”

Speaking about the future of radiation dose reduction, Colby told NeuroNews that “Improvements in the devices, the delivery systems for the devices, and the experience of the operator can all expect to further reduce radiation dose/exposure.”

Commenting on the study, co-author, Alexander Coon said, “This is an important analysis that demonstrates the benefit of Pipeline embolisation with regards to the very timely subject of radiation doses to patients and practitioners. I believe that it provides guidance to patients and neuro-interventionalists when selecting a treatment modality for endovascular aneurysm treatment.”