Balloon test occlusion (BTO) of the ICA has been performed to identify patients who are at risk for ischemia and stroke following permanent ICA occlusion as a part of surgical or endovascular treatment of extensive cervical and skull base tumors, inaccessible wide-necked ICA aneurysms and some direct arteriovenous fistulas. BTO has several variations and technical nuances in detecting patients who tolerate permanent ICA occlusion1. In summary, the symmetry of the cortical vein filling, when comparing the vascular territory of occluded ICA and the artery to be tested (contra lateral ICA or dominant VA), has the best angiographic positive predictive value for an uneventful ICA occlusion2,3. Visual estimation of venous filling in angiographic series is subjective. In addition, some patients with mainly collateral flow both through Acom and Pcom have lower opacification of the veins in the occluded ICA territory. The important indicator for negative BTO is the synchronicity, rather than the symmetry of the cortical vein opacification when comparing both hemispheres. syngo iFlow exactly quantifies the time of maximal venous opacification in standard angiographic series including the venous phase. In BTO we use a threshold for the venous time delay > 1 sec between examined and occluded ICA territory to predict a higher risk for ischemic events after permanent ICA occlusion. For BTO the patient received 5000 IU intravenous heparin. For ICA occlusion a Hyperform or Hyperglide balloon (ev3; Neurovascular, Irvine, California, USA) was positioned within the C4 segment. DSA series of the contralateral ICA were obtained in a standard biplane projection using 3 frames per second (Artis zee, biplane angiographic system, Siemens; Erlangen, Germany).
52-year-old male patient presented with severe left eye proptosis and blindness caused by fast growing residual meningioma of the medial sphenoid wing with predominant infiltration of the orbit (fig. 1). After particle embolization of the external tumor feeding arteries extirpation of the meningioma was planned. BTO was performed under general anesthesia and normotensive conditions for potential resection of left ICA (fig. 2). syngo iFlow data showed no delay of the venous phase between occluded left ICA (8,3 s) and right ICA (8,2 s) due to a patent Acom cross-flow (fig. 3).
63-year-old female patient presented with a sinusoidal carcinoma infiltrating the skull base and the left cavernous sinus (fig. 4). BTO was performed for left-sided ICA in preparation of a radical tumor resection (fig. 5). A venous phase delay of 2 sec of the occluded left side ICA territory was observed and predicted a high risk for ischemia in case of ICA sacrifice (fig. 6).
syngo iFlow is a fast and very powerful tool in the detection and quantification of interhemispheric venous phase time delay during balloon test occlusion.
Meningioma of medial sphenoid wing with marked infiltration of the left orbit and cavernous sinus as shown in postcontrast fat-saturated T1w transversal [left] and coronal [right] images. The cavernous and cisternal part of left ICA is surrounded by the tumor.
For BTO the left ICA was occluded at the cavernous segment using a 4 x 7 mm Hyperform balloon [left]. The angiogram of injected contralateral ICA shows a symmetric venous filling in both hemispheres [right].
syngo iFlow clearly quantifies the synchronicity of the cortical vein filling in both hemispheres.
A sinusoidal carcinoma infiltrates the cavernous sinus close to ICA as shown in T1w fatsaturated post-contrast transversal [left] and coronal [middle] images with marked bone erosion of sphenoid part of the carotid channel in CT [right].
BTO was performed using a Hyperglide balloon (4 x 10 mm) positioned in the petrous segment of left ICA [left]. DSA series of the right ICA showed a good Acom cross-flow supplying the left ICA territory [middle], but with delayed venous filling compared to the right ICA territory [right].
By means of syngo iFlow a delay of 2 sec. between the venous phase of the hemispheres was detected and clearly quantified.
Lesley WS, Rangaswarny R. Balloon test occlusion and endosurgical parent artery sacrifice for the evaluation and management of complex intracranial aneurysmal disease. J NeuroIntervent Surg 2009;1:112-120
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Rooij van WJ, Sluzewwski M, Slob MJ, Rinkel GJ. Predictive value of angiographic testing for tolerance to therapeutic occlusion of the carotid artery. AJNR 2005;26:175-178