Comparison between ultra-high-resolution computed tomographic angiography and conventional computed tomographic angiography in the visualization of the subcallosal artery
- Department of Neurosurgery, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan.
- Department of Neurosurgical Engineering and Translational Neuroscience, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan.
- Department of Radiological Technology, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan.
- Diagnostic Radiology, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan.
- Department of Neurosurgical Engineering and Translational Neuroscience, Tohoku University Graduate School of Biomedical Engineering, Sendai, Miyagi, Japan.
Toshiki Endo, Department of Neurosurgery, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan.
DOI:10.25259/SNI_887_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: Yoshimichi Sato1, Toshiki Endo1,2, Shingo Kayano3, Hitoshi Nemoto3, Kazuki Shimada3, Akira Ito1, Hidenori Endo1, Shunji Mugikura4, Kuniyasu Niizuma1,2,5, Teiji Tominaga1. Comparison between ultra-high-resolution computed tomographic angiography and conventional computed tomographic angiography in the visualization of the subcallosal artery. 19-Oct-2021;12:528
How to cite this URL: Yoshimichi Sato1, Toshiki Endo1,2, Shingo Kayano3, Hitoshi Nemoto3, Kazuki Shimada3, Akira Ito1, Hidenori Endo1, Shunji Mugikura4, Kuniyasu Niizuma1,2,5, Teiji Tominaga1. Comparison between ultra-high-resolution computed tomographic angiography and conventional computed tomographic angiography in the visualization of the subcallosal artery. 19-Oct-2021;12:528. Available from: https://surgicalneurologyint.com/?post_type=surgicalint_articles&p=11184
Background: The subcallosal artery (ScA) is a single dominant artery arising from the anterior communicating artery. Its injury causes amnesia and cognitive disturbance. The conventional computed tomographic angiography (C-CTA) is a common evaluation method of the intracranial artery. However, to image tinny perforating arteries such as the ScA is technically demanding for C-CTA. The purpose of this study is to investigate whether the ultra-high-resolution CTA (UHR-CTA) could image the ScA better than C-CTA. UHR-CTA became available in clinical practice in 2017. Its novel features are the improvement of the detector system and a small X-ray focus.
Methods: Between April 2019 and May 2020, 77 and 49 patients who underwent intracranial UHR-CTA and C-CTA, respectively, were enrolled in this study. Two board-certified neurosurgeons participated as observers to identify the ScA based on UHR-CTA and C-CTA images.
Results: UHR-CTA and C-CTA detected the ScA in 56–58% and 30–40% of the patients, respectively. In visualization of the ScA, UHR-CTA was better than C-CTA (P
Conclusions: UHR-CTA is a simple and accessible method to evaluate intracranial vasculature. Visualization of the ScA with UHR-CTA was better than that with C-CTA. The high quality of UHR-CTA could provide useful information in the neurosurgery field.
Keywords: Anterior communicating artery, Conventional detector computed tomographic angiography, Subcallosal artery, Ultra-high-resolution computed tomographic angiography
In the surgical treatments for the anterior communicating artery (ACoA) aneurysms or the parachiasmatic tumors, patients may suffer amnesia and cognitive disturbance in after the surgery.[
Perforating arteries arising from the ACoA are responsible for these neurological deficits. Yasargil et al. named these perforating arteries as hypothalamic arteries in 1984.[
The common evaluation method of the intracranial artery is conventional computed tomographic angiography (C-CTA). However, a diameter of the ScA was 0.5 ± 0.1 mm or lesser, which is technically demanding for C-CTA to visualize.[
In 2017, the ultra-high-resolution CTA (UHR-CTA) newly became available in clinical practice. The latest UHR-CTA (Aquilion PrecisionTM; Canon Medical Systems, Tokyo, Japan) provides slice collimation of 0.25 × 160 mm and a matrix size of 1024 × 1024 mm or 2048 × 2048 mm. Its features include an improved detector system and a smaller X-ray focus.[
From our medical records, we retrospectively retrieved the data of 115 patients who underwent intracranial UHR-CTA and 94 patients who underwent intracranial C-CTA, between April 2019 and May 2020. There were no overlaps between the two groups. We excluded 38 and 45 patients who underwent intracranial UHR-CTA and intracranial C-CTA, respectively, for the following reasons: unavailable datasets, scanning parameters different from those defined in the protocol, and tumors near the ScA. Therefore, 77 patients who underwent intracranial UHR-CTA (37 men and 40 women; age range, 14–74 years; mean age, 51.6 years) and 49 patients who underwent intracranial C-CTA (20 men and 29 women; age range, 3–82 years; mean age, 48.7 years) were enrolled in this study. In the enrolled cases, we included 4 patients who underwent the clipping surgery of the ACoA aneurysms. Three and one patients underwent UHR-CTA and C-CTA, respectively. This study was approved by the Ethical Review Board of Tohoku University Hospital (2020-1-413). We obtained written informed consent from all the patients regarding CTA examinations. For this retrospective study, our ethical review board did not require written informed consents from each individual regarding the participation of this study. The clinical characteristics of the patients enrolled in this study are summarized in [
UHR-CTA was performed using a 160-detector row UHRCT scanner system. The helical scanning parameters were as follows: tube voltage =120 kV, tube current = 240 mA, collimation = 0.25 mm × 160, beam pitch factor = 0.569, rotation speed = 0.75 s, slice thickness = 0.25 mm, slice interval = 0.25 mm, scan coverage = 160 mm, reconstruction kernel = forward-projected model-based iterative reconstruction solution algorithm by Canon Medical Systems, and scanning field of view (FOV) = 320 mm. The scan coverage was set for whole brain, with 1024 × 1024 matrix, and display FOV of 200–220 mm. The mean CT dose index volume (CTDIvol) and dose-length product (DLP) were 41.7 mGy and 879.4 mGy cm, respectively.
C-CTA studies were performed using a 320-detector row CT system (Aquilion ONE Vision; Canon Medical Systems, Otawara, Japan). The volume scanning parameters were as follows: tube voltage = 120 kV, automatic exposure control tube current standard deviation = 7, collimation = 0.5 mm × 320, rotation speed = 1.5 s, slice thickness = 0.5 mm; slice interval = 0.25 mm, scan coverage = 160 mm, reconstruction kernel = FC44, iterative and noise-reduction filters = adaptive iterative dose reduction algorithm by Canon Medical Systems, and scanning FOV = 240 mm. The scan coverage was set for the whole brain, with a display FOV of 200– 220 mm. The mean CTDIvol and mean DLP were 54.29 ± 9.1 mGy and 866.6 ± 144.5 mGy cm, respectively.
Nonionic contrast medium with an iodine concentration between 300 and 370 mgI/mL was used selectively according to body weight (iomeprol [Iomeron300; Eisai Co., Ltd., Tokyo, Japan], ioversol [Optiray320; Guerbet Japan Co., Ltd., Tokyo, Japan], iohexol [OMNIPAQUE350; GE Healthcare Pharma Co., Ltd., Tokyo, Japan], and iopamidol [Iopamiron370; Bayer Yakuhin, Ltd., Osaka, Japan]). Contrast medium was delivered via a 20-gauge catheter inserted into the antecubital vein with an injection flow rate based on the patient’s body weight in kilograms (main bolus injection: UHR-CTA, 27.5 mgI/kg/s; C-CTA, 26 mgI/kg/s). The injection time was 12 s for C-CTA and 14 s for UHR-CTA.
Image postprocessing and data analysis
To evaluate the ScA and the MdCA, sagittal maximum intensity projection (MIP) images with 2 mm thickness were reconstructed from UHR-CTA and C-CTA images. These MIP images were generated using a commercially available workstation (Ziostation2; Ziosoft, Tokyo, Japan). Patients with a surgical clip were evaluated with the same method. The ScA was defined as an artery arising from the posterior/ posterosuperior surface of the ACoA and running to the pericallosal cistern but not extending beyond the genu of the corpus callosum.[
From the generated UHR-CTA and C-CTA images, the ScA and the MdCA were visually assessed. Two independent experienced neurosurgeons (YS and TE) participated as observers. The concordance between the two observers was evaluated based on Cohen’s kappa coefficient interpreted as follows: ≤0, no agreement; 0.01–0.20, none to slight agreement; 0.21–0.40, fair agreement; 0.41–0.60, moderate agreement; 0.61–0.80, substantial agreement; and 0.81–1.00, almost perfect agreement.[
Number of subcallosal arteries recognized in the UHR-CTA and C-CTA images
The first observer (YS) identified the ScA in 45 patients (58%) and 15 patients (30%) on the UHR-CTA and C-CTA images, respectively. The second observer (TE) detected the ScA in 43 patients (56%) and 18 patients (40%) on the UHR-CTA and C-CTA images, respectively. Both of the two observers identified the MdCA in 3 (3.9%) and 1 case (2.3%) in UHRCTA and C-CTA, respectively.
Regarding the ScA, the Cohen’s kappa coefficient was 0.77 for UHR-CTA and 0.78 for C-CTA. The average results of the two observers are shown in [
Representative images of the ScA obtained from UHR-CTA and C-CTA are shown in [
Representative sagittal maximum intensity projection images from ultra-high-resolution computed tomographic angiography (UHR-CTA) (a) and conventional computed tomographic angiography (C-CTA) (b). In UHR-CTA, the higher image quality permitted the identification of the subcallosal artery (ScA) as an artery arising from the posterior surface of the anterior communicating artery (arrowheads in a). While, in C-CTA, the ScA was not identified.
Subcallosal arteries after the ACoA aneurysmal surgery
Among the 4 patients who underwent the clipping surgery for the ACoA aneurysms, UHR-CTA detected the ScA in 2 out of 3 patients (67%) [
Pre and postoperative images of a 73-year-old woman who underwent the clipping operation for the ruptured anterior communicating artery (ACoA) aneurysm. (a) A three dimensional reconstructed image of the rotational angiography demonstrating ACoA aneurysm (arrow) and the subcallosal artery (ScA, arrowheads). (b) Sagittal maximum intensity projection image of the ultra-high-resolution computed tomographic angiography demonstrate the ScA (arrowheads) even after the clip was applied to the ACoA aneurysm (black arrow).
In this study, the ScAs were detected more frequently on UHR-CTA images. The UHR-CTA detected the ScA in 56–58% of the patients, while the C-CTA could detect the ScA only in 30–40% of the patients. The difference was statistically significant. In our analyses, the MdCA were also identified in 2.3% to 3.9% of the cases. According to the cadaveric study by Marinković et al., the ScA and the MdCA callosum were complementary,[
Since cadaver head dissections found the ScAs in 80% of the specimens,[
ScA and ACoA aneurysmal surgery
The visualization and preservation of the ScA have always been an issue in surgical interventions performed for ACoA aneurysms.[
The current study included four postoperative cases after the clipping surgeries for the ACoA aneurysms. Importantly, the ScA near the surgical clip was successfully imaged in UHR-CTA in 2 out of 3 cases. Our results indicated that the artifacts of the surgical clips were reduced in UHRCTA when compared to those in C-CTA. To explain the low metallic artifacts in UHR-CTA, two hypotheses including the high effective energy and the high spatial resolution were suggested. As the effective energy rises, the beam hardening artifact from the aneurysm clip reduces.[
Magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA)
MRA can be another option to assess intracranial arteries in a non-invasive manner. It does not require any contrast medium and is less invasive than CTA. However, visualization of a small perforating artery, such as the ScA, has not yet been successful with 1.5- or 3-Tesla MRAs. Recently, several studies indicated that 7-Tesla MRA could be useful for studying the microanatomy of perforating arteries. Matsushige et al. reported that branching arteries originating from the ACoA, including the ScA, were visualized on a 7-Tesla MRI in 85.1% of the participants.[
In the current protocol, we could not compare images of these two types of CTA in the same individuals, which is major limitation. Another limitation of this study was that we only analyzed the ScA and the MdCA among other various perforating arteries. As Serizawa et al., reported, the ACoA perforators included hypothalamic and chiasmatic branches[
Furthermore, we could only include the postoperative AcoA aneurysm cases in very limited numbers in this study. The artifacts near the surgical clip might have influenced the image quality of the UHR-CTA; however, this issue was beyond the scope of this study. We are now planning another clinical study to determine whether UHR-CTA could potentially provide high-quality images to evaluate the preservation of the perforating arteries near the surgical clips and whether they could influence surgical results and overall outcomes of the patients.
UHR-CTA considerably improved the visualization of the ScA. UHR-CT is a simple and easily accessible method to evaluate microvasculature, such as the ScA, especially in the neurosurgery field.
Institutional Review Board (IRB) permission obtained for the study. IRB did not require written informed consents from each individual regarding the participation of this study.
This study was supported by JSPS Grant-in-Aid for Scientific Research. No author has personal or institutional financial interest in drugs, materials, or devices described in this paper.
There are no conflicts of interest.
We would like to thank Editage (www.editage.com) for English language editing.
1. Barrett JF, Keat N. Artifacts in CT: Recognition and avoidance. Radiographics. 2004. 24: 1679-91
2. Chenin L, Kaoudi A, Foulon P, Havet E, Peltier J. Microsurgical anatomy of the subcallosal artery. Surg Radiol Anat. 2019. 41: 1037-44
3. Cohen J. A coefficient of agreement for nominal scales. Educ Psychol Meas. 1960. 20: 37-46
4. Kakinuma R, Moriyama N, Muramatsu Y, Gomi S, Suzuki M, Nagasawa H. Ultra-high-resolution computed tomography of the lung: Image quality of a prototype scanner. PLoS One. 2015. 10: e0137165
5. Kannath SK, Malik V, Rajan JE. Isolated subcallosal artery infarction secondary to localized cerebral vasospasm of anterior communicating artery complex following subarachnoid hemorrhage. World Neurosurg. 2017. 107: 1043.e15-8
6. Katsura M, Sato J, Akahane M, Kunimatsu A, Abe O. Current and novel techniques for metal artifact reduction at CT: Practical guide for radiologists. Radiographics. 2018. 38: 450-61
7. Marinković S, Milisavljević M, Marinković Z. Branches of the anterior communicating artery. Microsurgical anatomy. Acta Neurochir (Wien). 1990. 106: 78-85
8. Matsushige T, Chen B, Dammann P, Johst S, Quick HH, Ladd ME. Microanatomy of the subcallosal artery: An in vivo 7 T magnetic resonance angiography study. Eur Radiol. 2016. 26: 2908-14
9. Mortimer AM, Steinfort B, Faulder K, Erho T, Scherman DB, Rao PJ. Rates of local procedural-related structural injury following clipping or coiling of anterior communicating artery aneurysms. J Neurointerv Surg. 2016. 8: 256-64
10. Mugikura S, Kikuchi H, Fujii T, Murata T, Takase K, Mori E. MR imaging of subcallosal artery infarct causing amnesia after surgery for anterior communicating artery aneurysm. AJNR Am J Neuroradiol. 2014. 35: 2293-301
11. Mugikura S, Kikuchi H, Fujimura M, Mori E, Takahashi S, Takase K. Subcallosal and Heubner artery infarcts following surgical repair of an anterior communicating artery aneurysm: A causal relationship with postoperative amnesia and long-term outcome. Jpn J Radiol. 2018. 36: 81-9
12. Mugikura S, Mori N, Kikuchi H, Mori E, Takahashi S, Takase K. Relationship between decreased cerebral blood flow and amnesia after microsurgery for anterior communicating artery aneurysm. Ann Nucl Med. 2020. 34: 220-7
13. Murayama K, Suzuki S, Nagata H, Oda J, Nakahara I, Katada K. Visualization of lenticulostriate arteries on CT angiography using ultra-high-resolution CT compared with conventional-detector CT. AJNR Am J Neuroradiol. 2020. 41: 219-23
14. Nagata H, Murayama K, Suzuki S, Watanabe A, Hayakawa M, Saito Y. Initial clinical experience of a prototype ultra-high-resolution CT for assessment of small intracranial arteries. Jpn J Radiol. 2019. 37: 283-91
15. Najera E, Belo JT, Truong HQ, Gardner PA, Fernandez-Miranda JC. Surgical anatomy of the subcallosal artery: Implications for transcranial and endoscopic endonasal surgery in the suprachiasmatic region. Oper Neurosurg (Hagerstown). 2019. 17: 79-87
16. Norlen G, Barnum AS. Surgical treatment of aneurysms of the anterior communicating artery. J Neurosurg. 1953. 10: 634-50
17. Sakai Y, Kitamoto E, Okamura K, Tatsumi M, Shirasaka T, Mikayama R. Metal artefact reduction in the oral cavity using deep learning reconstruction algorithm in ultra-high-resolution computed tomography: A phantom study. Dentomaxillofac Radiol. 2021. 50: 20200553
18. Serizawa T, Saeki N, Yamaura A. Microsurgical anatomy and clinical significance of the anterior communicating artery and its perforating branches. Neurosurgery. 1997. 40: 1211-6
19. Sutherland RJ, Rodriguez AJ. The role of the fornix/fimbria and some related subcortical structures in place learning and memory. Behav Brain Res. 1989. 32: 265-77
20. Thomas AG, Koumellis P, Dineen RA. The fornix in health and disease: An imaging review. Radiographics. 2011. 31: 1107-21
21. Türe U, Yaşargil MG, Krisht AF. The arteries of the corpus callosum: A microsurgical anatomic study. Neurosurgery. 1996. 39: 1075-1084
22. Yanagawa M, Hata A, Honda O, Kikuchi N, Miyata T, Uranishi A. Subjective and objective comparisons of image quality between ultra-high-resolution CT and conventional area detector CT in phantoms and cadaveric human lungs. Eur Radiol. 2018. 28: 5060-8
23. Yasargil MG, Kasdaglis K, Jain KK, Weber HP. Anatomical observations of the subarachnoid cisterns of the brain during surgery. J Neurosurg. 1976. 44: 298-302