Treatment of cerebral aneurysms aims to prevent possible aneurysm rupture or re-bleeding. Endovascular embolization is now considered the first line of treatment owing to its minimal invasiveness with reduced mortality and morbidity rates as compared with the surgical intervention [1].
Following endovascular treatment (EVT) of a cerebral aneurysm in about 20% of patients, reopening of the aneurysm or its neck occurs which necessitates retreatment in approximately half of them to ensure long-term protection from bleeding [2]. In addition, the appearance of de novo aneurysms is another concern for all patients with intracranial aneurysm which occurs in about 5 to 10% of patients. Some of these carry enough risk for bleeding despite their small size [3]. Hence, imaging follow-up is crucial for detection and preventive treatment of recurrent or of newly developed aneurysms after EVT [4].
Ideally, the first imaging follow-up should be scheduled 3–6 months after the EVT with further follow-up studies in varying time intervals according to the department’s regimen and the characteristics of the patient and the aneurysm [4].
Although CT angiography (CTA) and MR angiography (MRA) are routinely used to initially diagnose cerebral aneurysms, their use for evaluation of aneurysms following EVT is much more challenging [5]. The high attenuation of the endovascular coil mass causes marked streaky beam hardening artifact on CT and CTA, which typically obscures the aneurysm, the adjacent parent, and branch vessels as well as the surrounding brain parenchyma [6]. In MRA, the coil-induced susceptibility artifacts, slow and complex flow within the residual aneurysm (resulting in spin saturation and de-phasing respectively) coupled with the long acquisition time and the risk of gadolinium-induced nephrogenic systemic fibrosis in patients with renal impairment, are all major limitations in imaging of coiled aneurysms [5].
For the above reasons, digital subtraction angiography (DSA) is considered the gold standard for the assessment of occluded aneurysms by EVT. Three-dimensional (3D) reconstruction of rotational angiography significantly improved the performance of DSA. It requires a flat-panel angiographic system with a motorized rotating C-arm. The acquisition comprised of two rotational scans. The first one collects subtraction masks, while the second scan acquires images during the passage of contrast medium. Software reconstructions then enable extraction of bony structures, deletion of unnecessary vessels, and rotation and zooming of the image, as well as differentiation between vascular contrast filling and vascular devices [7].
In clinical practice, 3D DSA is more sensitive than 2D DSA to small aneurysms and aneurysm remnants [8]. Therefore, 3D DSA was proposed to become a new gold standard of interventional cerebral vascular imaging due to its high spatial resolution with 3D imaging and dynamic information [9]. However, in 3D DSA with single-volume reconstruction, the image quality is degraded by device-related artifacts making recanalization difficult to detect and with difficulty in planning further intervention [7]. The dual-volume reconstruction technique was developed to reduce artifacts and provide more details regarding the aneurysm, parent vessel, and side branches as well as the used endovascular devices [10]. It is derived from the 3D DSA 3 volume data sets which are native (mask), fill, and subtracted-fill. The mask and the subtracted-fill data sets are optimized separately by choosing the best contrast, widowing and color coding, and then fusing them into a single dual-volume image. These images are particularly helpful to differentiate vessels from medical devices and appreciate their relationship with bone structures increasing the accuracy for depicting residual lesions [11].
To the best of our knowledge, few data are available in the literature addressing the advantage of the dual-volume reconstruction technique over the single-volume 3D DSA.
The purpose of this study was to assess the added value of the dual-volume technique when used with the routine single-volume 3D DSA in the follow-up of endovascularly treated aneurysms.
