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3D rotational fluoroscopy for intraoperative clip control in patients with intracranial aneurysms--assessment of feasibility and image quality.

Westermaier T, Linsenmann T, Homola GA, Loehr M, Stetter C, Willner N, Ernestus RI, Solymosi L, Vince GH - BMC Med Imaging (2016)

Bottom Line: Image acquisition and contrast administration caused no adverse effects.Precise image subtraction and post-processing can reduce metal artifacts and make the clip-site assessable and depict larger neck-remnants.Further technical developments are likely to result in improved image quality.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurosurgery, University of Wuerzburg, Josef-Schneider-Str. 11, 97080, Wuerzburg, Germany. Westermaie_T@ukw.de.

ABSTRACT

Background: Mobile 3D fluoroscopes have become increasingly available in neurosurgical operating rooms. In this series, the image quality and value of intraoperative 3D fluoroscopy with intravenous contrast agent for the evaluation of aneurysm occlusion and vessel patency after clip placement was assessed in patients who underwent surgery for intracranial aneurysms.

Materials and methods: Twelve patients were included in this retrospective analysis. Prior to surgery, a 360° rotational fluoroscopy scan was performed without contrast agent followed by another scan with 50 ml of intravenous iodine contrast agent. The image files of both scans were transferred to an Apple PowerMac® workstation, subtracted and reconstructed using OsiriX® free software. The procedure was repeated after clip placement. Both image sets were compared for assessment of aneurysm occlusion and vessel patency.

Results: Image acquisition and contrast administration caused no adverse effects. Image quality was sufficient to follow the patency of the vessels distal to the clip. Metal artifacts reduce the assessability of the immediate vicinity of the clip. Precise image subtraction and post-processing can reduce metal artifacts and make the clip-site assessable and depict larger neck-remnants.

Conclusion: This technique quickly supplies images at adequate quality to evaluate distal vessel patency after aneurysm clipping. Significant aneurysm remnants may be depicted as well. As it does not require visual control of all vessels that are supposed to be evaluated intraoperatively, this technique may be complementary to other intraoperative tools like indocyanine green videoangiography and micro-Doppler, especially for the assessment of larger aneurysms. At the momentary state of this technology, it cannot replace postoperative conventional angiography. However, 3D fluoroscopy and image post-processing are young technologies. Further technical developments are likely to result in improved image quality.

No MeSH data available.


Related in: MedlinePlus

Preoperative DSA (a) with 3D reconstruction (b) and intraoperative 3D fluoroscopy after subtraction and reconstruction (c) before clip placement in a patient with a carotid artery aneurysm (case 2). d-f depict the respective projections after surgery. Postoperative DSA confirms a slight clip-induced narrowing of the ICA depicted by intraoperative 3D fluoroscopy
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Fig1: Preoperative DSA (a) with 3D reconstruction (b) and intraoperative 3D fluoroscopy after subtraction and reconstruction (c) before clip placement in a patient with a carotid artery aneurysm (case 2). d-f depict the respective projections after surgery. Postoperative DSA confirms a slight clip-induced narrowing of the ICA depicted by intraoperative 3D fluoroscopy

Mentions: The observers’ ratings for preoperative visibility of aneurysms by 3D fluoroscopy and post-clip control of distal vessel patency and complete aneurysm occlusion is depicted in Table 1. In case 1, previous endovascular therapy of an aneurysm of the anterior communicating artery made the 4 mm neck remnant invisible to 3D fluoroscopy. Similarly, the occlusion of the aneurysm and the originating proximal anterior cerebral artery (ACA) branches could not be assessed. In contrast, the patency of the distal ACA, including a small (3 mm) aneurysm of the left pericallosal artery could be readily visualized. In all other patients of this series, the aneurysms were well assessable before clipping. It was observed that small vessels, especially close to the skull base, may not be visualized due to the occurrence of minor beam hardening artifacts and due to the limited image resolution of the original O-arm® images generated by the given image acquisition parameters. (see Fig. 1a-c). The patency of larger-aneurysm-carrying-vessels and their main branches (Fig. 2) was clearly visible after placement of the clip. Subsequently, a slight clip-induced narrowing of the internal carotid artery was visualized by intraoperative 3D fluoroscopy (Fig. 1f) and verified by postoperative digital subtraction angiography (DSA) (Fig. 1d and e). Similarly, the vasospasm-induced narrowing of the distal MCA trunk in case 11 which was most distinct close to the MCA bifurcation was depicted by DSA (Fig. 3a–c) and by intraoperative 3D fluoroscopy (Fig. 3d). After positioning of the clip, vessel patency distal to the clip was generally verifiable. In general, the exclusion of the aneurysm dome after clipping was also assessable. However, metal artifacts immediately surrounding the clip branches may remain in some cases in spite of image subtraction and made the verification of complete aneurysm occlusion not possible in most cases of this series. The presence of neck remnants may, therefore, remain undetected (Table 1). However, with precise image subtraction and post-processing, it is possible to depict larger aneurysm remnants (Fig. 3d).Fig. 1


3D rotational fluoroscopy for intraoperative clip control in patients with intracranial aneurysms--assessment of feasibility and image quality.

Westermaier T, Linsenmann T, Homola GA, Loehr M, Stetter C, Willner N, Ernestus RI, Solymosi L, Vince GH - BMC Med Imaging (2016)

Preoperative DSA (a) with 3D reconstruction (b) and intraoperative 3D fluoroscopy after subtraction and reconstruction (c) before clip placement in a patient with a carotid artery aneurysm (case 2). d-f depict the respective projections after surgery. Postoperative DSA confirms a slight clip-induced narrowing of the ICA depicted by intraoperative 3D fluoroscopy
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4837534&req=5

Fig1: Preoperative DSA (a) with 3D reconstruction (b) and intraoperative 3D fluoroscopy after subtraction and reconstruction (c) before clip placement in a patient with a carotid artery aneurysm (case 2). d-f depict the respective projections after surgery. Postoperative DSA confirms a slight clip-induced narrowing of the ICA depicted by intraoperative 3D fluoroscopy
Mentions: The observers’ ratings for preoperative visibility of aneurysms by 3D fluoroscopy and post-clip control of distal vessel patency and complete aneurysm occlusion is depicted in Table 1. In case 1, previous endovascular therapy of an aneurysm of the anterior communicating artery made the 4 mm neck remnant invisible to 3D fluoroscopy. Similarly, the occlusion of the aneurysm and the originating proximal anterior cerebral artery (ACA) branches could not be assessed. In contrast, the patency of the distal ACA, including a small (3 mm) aneurysm of the left pericallosal artery could be readily visualized. In all other patients of this series, the aneurysms were well assessable before clipping. It was observed that small vessels, especially close to the skull base, may not be visualized due to the occurrence of minor beam hardening artifacts and due to the limited image resolution of the original O-arm® images generated by the given image acquisition parameters. (see Fig. 1a-c). The patency of larger-aneurysm-carrying-vessels and their main branches (Fig. 2) was clearly visible after placement of the clip. Subsequently, a slight clip-induced narrowing of the internal carotid artery was visualized by intraoperative 3D fluoroscopy (Fig. 1f) and verified by postoperative digital subtraction angiography (DSA) (Fig. 1d and e). Similarly, the vasospasm-induced narrowing of the distal MCA trunk in case 11 which was most distinct close to the MCA bifurcation was depicted by DSA (Fig. 3a–c) and by intraoperative 3D fluoroscopy (Fig. 3d). After positioning of the clip, vessel patency distal to the clip was generally verifiable. In general, the exclusion of the aneurysm dome after clipping was also assessable. However, metal artifacts immediately surrounding the clip branches may remain in some cases in spite of image subtraction and made the verification of complete aneurysm occlusion not possible in most cases of this series. The presence of neck remnants may, therefore, remain undetected (Table 1). However, with precise image subtraction and post-processing, it is possible to depict larger aneurysm remnants (Fig. 3d).Fig. 1

Bottom Line: Image acquisition and contrast administration caused no adverse effects.Precise image subtraction and post-processing can reduce metal artifacts and make the clip-site assessable and depict larger neck-remnants.Further technical developments are likely to result in improved image quality.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurosurgery, University of Wuerzburg, Josef-Schneider-Str. 11, 97080, Wuerzburg, Germany. Westermaie_T@ukw.de.

ABSTRACT

Background: Mobile 3D fluoroscopes have become increasingly available in neurosurgical operating rooms. In this series, the image quality and value of intraoperative 3D fluoroscopy with intravenous contrast agent for the evaluation of aneurysm occlusion and vessel patency after clip placement was assessed in patients who underwent surgery for intracranial aneurysms.

Materials and methods: Twelve patients were included in this retrospective analysis. Prior to surgery, a 360° rotational fluoroscopy scan was performed without contrast agent followed by another scan with 50 ml of intravenous iodine contrast agent. The image files of both scans were transferred to an Apple PowerMac® workstation, subtracted and reconstructed using OsiriX® free software. The procedure was repeated after clip placement. Both image sets were compared for assessment of aneurysm occlusion and vessel patency.

Results: Image acquisition and contrast administration caused no adverse effects. Image quality was sufficient to follow the patency of the vessels distal to the clip. Metal artifacts reduce the assessability of the immediate vicinity of the clip. Precise image subtraction and post-processing can reduce metal artifacts and make the clip-site assessable and depict larger neck-remnants.

Conclusion: This technique quickly supplies images at adequate quality to evaluate distal vessel patency after aneurysm clipping. Significant aneurysm remnants may be depicted as well. As it does not require visual control of all vessels that are supposed to be evaluated intraoperatively, this technique may be complementary to other intraoperative tools like indocyanine green videoangiography and micro-Doppler, especially for the assessment of larger aneurysms. At the momentary state of this technology, it cannot replace postoperative conventional angiography. However, 3D fluoroscopy and image post-processing are young technologies. Further technical developments are likely to result in improved image quality.

No MeSH data available.


Related in: MedlinePlus