- Department of Neurosurgery, Gold Coast University Hospital, Southport, Qld, Australia.
DOI:10.25259/SNI_41_2021Copyright: © 2021 Surgical Neurology International This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-Share Alike 4.0 License, which allows others to remix, tweak, and build upon the work non-commercially, as long as the author is credited and the new creations are licensed under the identical terms.
How to cite this article: Mitchell Stanton, Gian Sparti. Use of dual-energy computed tomography post endovascular treatment of cerebral aneurysm. 17-May-2021;12:225
How to cite this URL: Mitchell Stanton, Gian Sparti. Use of dual-energy computed tomography post endovascular treatment of cerebral aneurysm. 17-May-2021;12:225. Available from: https://surgicalneurologyint.com/surgicalint-articles/10814/
Background: Along with surgical clipping, endovascular management is one of the mainstay treatment options for cerebral aneurysms. However, immediate post procedural imaging is often hard to interpret due to the presence of contrast material. Dual-energy computed tomography (CT) allows differentiation between contrast extravasation and intracranial hemorrhage and this case illustrates the importance of this following endovascular treatment of an unruptured cerebral aneurysm.
Case Description: A patient presented with acute ophthalmoplegia secondary to mass effect from an intracavernous ICA fusiform aneurysm. The patient underwent an endovascular flow diverting stent to treat this aneurysm. Post procedure, the patient had a reduced level of consciousness and underwent a conventional CT showing diffuse subarachnoid hyperdensity of the left hemisphere. Dual-energy CT allowed accurate differentiation and illustrated diffuse contrast material extravasation, allowing patient to continue on dual antiplatelets and therapeutic anticoagulation to reduce the risk of ischemic injury post endovascular stent.
Conclusion: Use of dual-energy CT in the setting of endovascular management of intracranial aneurysms allows accurate diagnosis of any postoperative complications. Specifically, differentiating between subarachnoid hemorrhage and contrast extravasation is vital in these patients due to the significant consequences to their ongoing management in regard to continuation or cessation of antiplatelets or anticoagulation. With increasing access to this technology, its use should become standard practice in the post-operative investigation of these patients undergoing endovascular treatment.
Keywords: Aneurysm, Computed tomography, Contrast extravasation, Dual-energy computed tomography, Endovascular, Subarachnoid hemorrhage
The concept of dual-energy computed tomography (CT) was first described in the 1970s, however, it was not until computational power advanced to the point where clinical implementation was possible in the early 2000s.[
The prevalence of cerebral aneurysms is estimated to be around 3.2% of the population, with rate of rupture among all aneurysms to be approximately 1.3% per year.[
On review of the currently available literature, the use of dual-energy CT has been shown to be an accurate method to differentiate between intracranial hemorrhage and contrast medium extravasation in acute stroke patients following intra-arterial revascularization.[
A female presented with acute onset left ophthalmoplegia secondary to mass effect of a newly diagnosed intracavernous left ICA fusiform aneurysm. This unruptured, partially thrombosed aneurysm was confirmed on diagnostic cerebral angiography, [
The patient underwent endovascular pipeline shield flow diverting stent treatment of the 18 mm unruptured aneurysm. The patient had been appropriately loaded preoperatively with dual antiplatelets and given a single-dose IV heparin as per department protocol. Nil intraprocedural concerns were identified, with early flow diversion and good parent vessel reconstruction noted. However, the patient was found to have decreased level of consciousness and dysphasia post procedure.
The patient was subsequently taken for an urgent conventional unenhanced CT, which is standard first-line radiographic assessment to assess for a postoperative complication. CT showed diffuse subarachnoid hyperdensity of the left cerebral hemisphere, shown in [
However, in this clinical setting, the decision was made to repeat imaging using dual-energy CT to help differentiate between contrast medium extravasation and subarachnoid hemorrhage due to the significant impact that correct diagnosis would have on the acute management of this patient. The use of dual-energy CT is illustrated in [
(a) Images from dual-energy CT. Conventional CT images again illustrating diffuse subarachnoid hyperdensity of the left cerebral hemisphere. (b) Iodine map, illustrating the ability to isolate only iodine contrast material as this has a single density that differs to that of hemorrhage. (c) Virtual nonenhanced image, where iodine contrast material identified on iodine map has been removed. Therefore, as showing no residual hyperdensity, this illustrates that it was all contrast material extravasation.
Follow-up conventional CT imaging shown in [
Allowing accurate differentiation in this early post procedure period allowed continuation of antiplatelets and therapeutic anticoagulation, subsequently reducing the risk of ischemia following flow-diverting stent.[
Despite continuation of therapeutic anticoagulation and dual antiplatelet medications, the patient still suffered a left frontal ischemic infarct affecting Broca’s area and causing severe expressive dysphasia. This likely occurred at the time of procedure from an embolic source. Her ongoing inpatient admission was further complicated by gastrointestinal bleeding secondary to diffuse upper gastrointestinal angioectasia in the setting of dual antiplatelet medications, with no surgical or endovascular treatment options. The patient has subsequently recovered but has been left with ongoing speech disturbance.
Endovascular intervention of cerebral aneurysms is a mainstay treatment to prevent the risk of subarachnoid hemorrhage. The decision regarding which aneurysms to treat is quite complex and there are many factors that come into play in this decision process. However, the focus of this case is not to discuss risk factors and patient selection but instead to illustrate the use of dual-energy CT to assist in the management of patients who have undergone endovascular treatment of cerebral aneurysms.
The ability for early differentiation of contrast medium extravasation and intracranial hemorrhage has become possible through the emerging availability of dual-energy CT. Dual-energy CT involves image reconstruction from two different X-ray spectra at different kilovoltages instead of one single kilovoltage as used with conventional CT.[
This differentiation between contrast extravasation and hemorrhage is critical in the acute management of patients following endovascular treatment because the use of an endovascular flow-diverting stent to treat an unruptured aneurysm has a significant risk of cerebral ischemia secondary to in-stent thrombosis or distal thromboembolic events.[
There is limited literature available regarding the use of dual-energy CT in the setting of subarachnoid hemorrhage. Ni et al.[
Karcaaltincaba also discusses other uses of dual-energy CT in the neuroradiology setting.[
The early differentiation between hemorrhage and contrast extravasation illustrated in this case allowed continuation of dual antiplatelets. The same clinical decisions are relevant in the setting of acute stroke patients who have undergone intra-arterial thrombectomy. The utility of dual-energy CT has been well documented in this scenario post intra-arterial thrombectomy for stroke patients, allowing for differentiation between contrast medium extravasation and hemorrhagic transformation.[
Use of dual-energy CT in the setting of endovascular management of intracranial aneurysms allows accurate diagnosis of any post-operative complications through its ability to differentiate between contrast extravasation and intracranial hemorrhage. Differentiating between subarachnoid hemorrhage and contrast extravasation is vital in these patients due to the significant consequences to their ongoing management in regard to continuation or cessation of antiplatelets or anticoagulation. With increasing access to this technology, its use should become standard practice in the postoperative investigation of these patients undergoing endovascular treatment.
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