Kohei TOKUYAMA

Dr. Kohei TOKUYAMA


Research Focus & Metrics

Academic Career Length

13Years (2014-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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1 April 2017 in British Journal of Radiology
Verified
Journal Article
Closed access
KTKohei TOKUYAMA
Kohei TOKUYAMA
FOFumito Okada
Fumito Okada
HSHaruka Sato
Haruka Sato
SMShunro Matsumoto
Shunro Matsumoto
AMAkira Matsumoto
Akira Matsumoto
HMHiromu Mori
Hiromu Mori
Objective:This study aimed to compare CT findings in patients with Epstein–Barr virus positive (EBV+) diffuse large B-cell lymphoma (DLBCL) of the elderly with CT findings in patients with Epstein–Barr virus negative (EBV−) DLBCL.Methods:We retrospectively identified 9 consecutive patients with EBV+ DLBCL (6 males and 3 females; aged 72–83 years, mean: 76.2 years) and 39 consecutive patients with EBV− DLBCL (19 males and 20 females; aged 53–91 years, mean: 71.3 years) who had undergone CT examinations between September 2007 and August 2016. In each type of disease, clinical and CT findings were evaluated.Results:No significant differences in B symptom incidence or serum lactate dehydrogenase levels were found between the two diseases. However, the prognosis of patients with EBV+ DLBCL was significantly poorer than that of those with EBV− DLBCL (p < 0.05). Nodal and extranodal necrosis was found in 6 (66.7%) of 9 patients with EBV+ DLBCL and in 6 (15.4%) of 39 patients with EBV− DLBCL (p < 0.005).Conclusio...

19 December 2019 in Interventional Neuroradiology
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Journal Article
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KTKohei TOKUYAMA
Kohei TOKUYAMA
HKHiro Kiyosue
Hiro Kiyosue
YHYuzo Hori
Yuzo Hori
HNHirofumi Nagatomi
Hirofumi Nagatomi
Diploic arteriovenous fistulas are rare arteriovenous shunts involving the skull, which often drain antegradely into the internal or external jugular veins. Diploic arteriovenous fistulas with marked cortical venous reflux are extremely rare. Here, we present the case of a patient with diploic arteriovenous fistulas with marked cortical venous reflux and a literature review. A 73-year-old woman presented with headache. Magnetic resonance angiography revealed abnormal signal intensity in the diploic layer of the left frontal bone. Digital subtraction angiography demonstrated a diploic arteriovenous fistulas located in the left frontal bone. The arteriovenous fistulas were fed by multiple branches of the left external carotid artery, mainly from the middle meningeal artery, branches of the ophthalmic artery, and the inferolateral trunk. The fistulas drained into the cerebral cortical veins surrounding the frontal lobe via an emissary vein of the frontal bone. With the femoral arterial approach, transarterial catheterization into the shunted diploic vein was performed with a small tapered microcatheter, and the arteriovenous fistulas were completely embolized with N-butyl-2-cyanoacrylate. The patient was discharged without complications. No recurrent arteriovenous fistulas were observed during the 12-month follow-up period. Endovascular treatment is an effective technique for the curative treatment of diploic arteriovenous fistulas.

8 August 2023 in Clinical Neuroradiology
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Journal Article
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MHMasafumi Hiramatsu
Masafumi Hiramatsu
TOTomohiko Ozaki
Tomohiko Ozaki
STShuichi Tanoue
Shuichi Tanoue
KMKatsuhiro Mizutani
Katsuhiro Mizutani
HNHajime Nakamura
Hajime Nakamura
HKHiro Kiyosue
Hiro Kiyosue
Background and Purpose: There has been limited literature regarding the bridging veins (BVs) of the medulla oblongata around the foramen magnum (FM). The present study aims to analyze the normal angioarchitecture of the BVs around the FM using slab MIP images of three-dimensional (3D) angiography. Methods: We collected 3D angiography data of posterior fossa veins and analyzed the BVs around the FM using slab MIP images. We analyzed the course, outlet, and number of BVs around the FM. We also examined the detection rate and mean diameter of each BV. Results: Of 57 patients, 55 patients (96%) had any BV. The median number of BVs was two (range: 0–5). The BVs originate from the perimedullary veins and run anterolaterally to join the anterior condylar vein (ACV), inferior petrosal sinus, sigmoid sinus, or jugular bulb, inferolaterally to join the suboccipital cavernous sinus (SCS), laterally or posterolaterally to join the marginal sinus (MS), and posteriorly to join the MS or occipital sinus. We classified BVs into five subtypes according to the draining location: ACV, jugular foramen (JF), MS, SCS, and cerebellomedullary cistern (CMC). ACV, JF, MS, SCS, and CMC BVs were detected in 11 (19%), 18 (32%), 32 (56%), 20 (35%), and 16 (28%) patients, respectively. The mean diameter of the BVs other than CMC was 0.6 mm, and that of CMC BV was 0.8 mm. Conclusion: Using venous data from 3D angiography, we detected FM BVs in most cases, and the BVs were connected in various directions.

3 September 2021 in Applied Sciences
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Journal Article
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KTKohei TOKUYAMA
Kohei TOKUYAMA
HKHiro Kiyosue
Hiro Kiyosue
HBHiroshi Baba
Hiroshi Baba
YAYoshiki Asayama
Yoshiki Asayama
An anomalous origin of the right vertebral artery (VA) is a rare anomaly that is much rarer than that of the left VA. It can be divided into a few patterns, including aortic origin, right carotid or brachiocephalic arterial origin, and duplicated origin. In embryological development, the VA is made up of a longitudinal anastomosis between cervical segments. The mechanism of the anomalous origin of the right VA can be explained by the persistence of the cervical segmental artery and the regression point of the 4th right aortic arch. Although the anomaly is usually found incidentally on imaging modalities, it can be a potential cause of complication during surgical and interventional procedures. However, there are a lot of reports about the radiomics of the anomaly. Therefore, we discuss the potential relationship between the anomalous origin of the right VA and radiomics. As the take-home message, understanding several patterns of anomalous origin of the right VA with their embryology and imaging findings is important for surgical and endovascular interventions to avoid intraprocedural complications.

1 January 2023 in Journal of Neuroendovascular Therapy
Verified
Journal Article
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KTKohei TOKUYAMA
Kohei TOKUYAMA
HKHiro Kiyosue
Hiro Kiyosue
YHYuzo Hori
Yuzo Hori
MOMika Okahara
Mika Okahara
HNHirofumi Nagatomi
Hirofumi Nagatomi
YAYoshiki Asayama
Yoshiki Asayama
Objective: Selective transvenous embolization (sTVE) is an effective technique for treating dural arteriovenous fistulas (DAVFs); however, selective catheterization into the shunted pouch is often difficult due to the acute angle of the access route between the target pouch and dural sinus. We present our initial experience using a steerable microcatheter (SM) to manually control the tip angle for selective catheterization and sTVE of DAVFs.Methods: Thirteen consecutive cases of DAVFs and 16 procedures that involved sTVE using SM between October 2016 and October 2018 were reviewed. SMs were used for selective catheterization of shunted venous pouches and/or the affected sinus and coil embolization. We evaluated the maneuverability of the SM, the success of selective catheterization into the target lesions, and the results of endovascular treatments.Results: Endovascular procedures were performed in a single session in 10 cases and in two staged sessions in 3 cases. There was no difficulty in maneuverability of the SM. Successful selective catheterization was achieved in 26 of 27 target lesions. Immediately after embolization, angiography showed complete occlusion in 10 cases and marked reduction in 3 cases. During 40.9 months of mean follow-up, 12 cases showed complete occlusion and one case showed a small residual shunt on MRI. Procedure-related complications of spontaneous thrombosis of the affected sinus were observed in one case. There were no cases of recurrence or exacerbation during follow-up.Conclusion: SM is useful for selective catheterization for target lesions during sTVE of DAVFs.

24 July 2023 in Journal of Neurosurgery: Case Lessons
Verified
Journal Article
Open access
PDF file
KTKohei TOKUYAMA
Kohei TOKUYAMA
HKHiro Kiyosue
Hiro Kiyosue
RSRyuichi Shimada
Ryuichi Shimada
SMSatomi Miyamoto
Satomi Miyamoto
AAAyaka Abe
Ayaka Abe
YAYoshiki Asayama
Yoshiki Asayama
BACKGROUND: The present report describes 2 cases of arterial bleeding after removal of the upper third molar that were successfully treated with selective transarterial embolization. OBSERVATIONS: The first patient underwent removal of the left upper third molar. A few hours later, facial swelling and massive bleeding appeared near the extraction socket involving the posterolateral wall of the maxillary sinus. Angiography showed a pseudoaneurysm involving the posterior superior dental artery, and the lesion was selectively embolized with an N-butyl cyanoacrylate (NBCA)-lipidiol mixture. The second patient underwent removal of the left upper third molar, and massive bleeding occurred from the extraction socket involving the greater palatine foramen. Angiography revealed the pseudoaneurysm of the greater palatine artery, and the lesion was selectively embolized with an NBCA-lipiodol mixture. Both patients were discharged uneventfully, and no recurrent bleeding was observed during the 82- and 5-month follow-up periods. LESSONS: Massive arterial bleeding after a third molar extraction occurs from either the posterior superior dental artery or the greater palatine artery, which is associated with the location of the extraction socket. Selective transarterial glue embolization is a useful option for the treatment of arterial bleeding after the removal of the upper third molars.