Yoshikazu Kobayashi

Dr. Yoshikazu Kobayashi

orcid

Research Focus & Metrics

Academic Career Length

12Years (2015-Present)

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

Representative Publications

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15 June 2020 in Annals of Nuclear Medicine
Verified
Journal Article
Open access
PDF file
TOTaro Okui
Taro Okui
YKYoshikazu Kobayashi
Yoshikazu Kobayashi
MTMasakazu Tsujimoto
Masakazu Tsujimoto
KSKoji Satoh
Koji Satoh
HTHiroshi Toyama
Hiroshi Toyama
KMKoichiro Matsuo
Koichiro Matsuo
Objective: This study aimed to use quantitative values, calculated from bone single photon emission computed tomography (SPECT) imaging, to estimate the reliability of progression evaluation for anti-resorptive agent-related osteonecrosis of the jaw (ARONJ). Methods: The study population consisted of 21 patients (23 lesions), clinically diagnosed with mandibular ARONJ, who underwent SPECT/CT scanning. Diagnosis and staging of ARONJ were performed according to the American Association of Oral and Maxillofacial Surgeons (AAOMS) definition and the recommendations of the International Task Force on ONJ. Hybrid SPECT/CT imaging quantitative analyses were performed on a workstation. Each volume of interest (VOI) was semi-automatically placed over a lesion with areas of high tracer accumulation, using the GI-BONE® software default threshold method settings. Additionally, control VOI was manually set over an unaffected area. Measured parameters included standardized uptake values (SUV)—maximum (SUVmax) and mean (SUVmean), metabolic bone volume (MBV)—the total volume above the threshold, and total bone uptake (TBU) as calculated by MBV × SUVmean. We also calculated the SUV ratio (rSUV) between the lesion and control area, factoring for differences in individual bone metabolism; the ratios were termed rSUVmax and rSUVmean, accordingly. The product of multiplying the rSUVmean by MBV of a lesion was defined as the ratio of TBU (rTBU). Quantitative values were compared between clinical stages by the Kruskal–Wallis test and subsequent post hoc analysis. Results: MBVs (cm3) were: median, [IQR] Stage 1, 8.28 [5.62–9.49]; Stage 2, 15.28 [10.64–24.78]; and Stage 3, 34.61 [29.50–40.78]. MBV tended to increase with stage increase. Furthermore, only MBV showed a significant difference between clinical stages (p < 0.01). Subsequent post hoc analysis showed no significant difference between stages 1 and 2 (p = 0.12) but a significant difference between stages 2 and 3 (p = 0.048). rSUVmax and rTBU tended to increase with stage increase, but the differences between the stages were not significant (p = 0.10 and p = 0.055, respectively). Conclusion: MBV, which includes the concept of volume, showed significant differences between clinical stages and tended to increase with the stage increase. As an objective and reliable indicator, MBV might be an adjunct diagnostic method for staging ARONJ.

2 March 2016 in Journal of Oral and Maxillofacial Surgery, Medicine, and Pathology
Verified
Journal Article
Closed access
TATakako Aizawa
Takako Aizawa
TOTaro Okui
Taro Okui
KKKen Kitagawa
Ken Kitagawa
YKYoshikazu Kobayashi
Yoshikazu Kobayashi
KSKoji Satoh
Koji Satoh
HMHideki Mizutani
Hideki Mizutani

8 July 2019 in BMC Medical Imaging
Verified
Journal Article
Open access
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YKYoshikazu Kobayashi
Yoshikazu Kobayashi
DKDaisuke Kanamori
Daisuke Kanamori
NFNaoko Fujii
Naoko Fujii
YKYumi Kataoka
Yumi Kataoka
EHEmiko Hirai
Emiko Hirai
KMKoichiro Matsuo
Koichiro Matsuo
Nasopharyngoscopy is a common method to evaluate velopharyngeal closure in patients with cleft palate. However, insertion of a fiberoptic nasopharyngoscope causes discomfort in patients. The aim of this study was to estimate the reliability of short-time exposure images obtained using 320-row area detector computed tomography (320-ADCT) as a novel evaluation method for the assessment of velopharyngeal function. We evaluated five healthy adult volunteers and five postoperative adult patients with cleft palate. During a 3.3-s imaging exposure, the participants were asked to perform two tasks: nasal inspiration and subsequent oral expiration through a catheter into a water-filled cup. The movement of the velopharyngeal structures was recorded during each examination, and the presence of velopharyngeal insufficiency (VPI) and velopharyngeal closure (VPC) patterns were estimated. If VPI was detected, the cross-sectional area was also calculated. Cohen’s kappa and weighted kappa coefficients were used to evaluate the concordance of nasopharyngoscopy and 320-ADCT evaluation. Speech pathology evaluation did not reveal hypernasality in any study participant. Micro-VPI was detected by nasopharyngoscopy in one healthy volunteer and two patients. 320-ADCT detected micro-VPI in two more patients. The cross-sectional area of the VPI in these subjects ranged from 2.53 to 16.28 mm2. Nasopharyngoscopy and 320-ADCT were concordant in detecting VPI in eight participants (κ = 0.6) and in assessing VPC patterns in nine (κ = 0.82). Moreover, images obtained using 320-ADCT allowed for reduced dead angle and, thus, easy detection of micro-VPI and Passavant’s ridges. Although the radiation exposure cannot be ignored, our novel evaluation method using 320-ADCT enables more detailed evaluation of VPC than nasopharyngoscopy. Future studies should investigate the relationship between 320-ADCT findings and speech pathology evaluations.

24 February 2015 in Journal of Medical Case Reports
Verified
Journal Article
Open access
PDF file
YKYoshikazu Kobayashi
Yoshikazu Kobayashi
KSKoji Satoh
Koji Satoh
TATakako Aizawa
Takako Aizawa
MUMakoto Urano
Makoto Urano
MKMakoto Kuroda
Makoto Kuroda
HMHideki Mizutani
Hideki Mizutani
Sclerosing mucoepidermoid carcinoma with eosinophilia is a rare morphological variant of thyroid carcinoma associated with Hashimoto’s disease. To date, only three such tumors have been reported in the minor salivary glands. We describe the first case, to the best of our knowledge, of recurrent sclerosing mucoepidermoid carcinoma with eosinophilia in the minor salivary glands of the upper lip. A 61-year-old Japanese man was referred to our hospital with a mass in his median upper lip of four years’ duration. An examination of his median upper lip revealed a well-defined tumor measuring 9×12mm in diameter, which was subsequently resected. Three years after the first surgery, the tumor recurred and was resected. Both tumors were confirmed by histopathology to be sclerosing mucoepidermoid carcinoma with eosinophilia. Neither recurrence nor metastasis was observed in three and a half years of follow-up after the second surgery. Our findings indicate that sclerosing mucoepidermoid carcinoma with eosinophilia can originate in the minor salivary glands and may be clinically or pathologically misdiagnosed as other conditions.

16 May 2021 in Annals of Nuclear Medicine
Verified
Journal Article
Closed access
PDF file
YKYoshikazu Kobayashi
Yoshikazu Kobayashi
TOTaro Okui
Taro Okui
MTMasakazu Tsujimoto
Masakazu Tsujimoto
HIHirotaka Ikeda
Hirotaka Ikeda
KSKoji Satoh
Koji Satoh
KMKoichiro Matsuo
Koichiro Matsuo

7 December 2023 in BMC Oral Health
Verified
Journal Article
Open access
PDF file
MKMin Jung Kim
Min Jung Kim
MKMana Kuroda
Mana Kuroda
YKYoshikazu Kobayashi
Yoshikazu Kobayashi
TYTakahisa Yamamoto
Takahisa Yamamoto
TATakako Aizawa
Takako Aizawa
KSKoji Satoh
Koji Satoh
Background: The COVID-19 pandemic led to concerns about the potential airborne transmission of the virus during dental procedures, but evidence of actual transmission in clinical settings was lacking. This study aimed to observe the behavior of dental sprays generated from dental rotary handpieces and to evaluate the effectiveness of high-volume evacuators (HVEs) using laser light sheets and water-sensitive papers. Methods: A dental manikin and jaw model were mounted in a dental treatment unit. Mock cutting procedures were performed on an artificial tooth on the maxillary left central incisor using an air turbine, a contra-angle electric micromotor (EM), and a 1:5 speed-up contra-angle EM (×5EM). Intraoral vacuum and extraoral vacuum (EOV) were used to verify the effectiveness of the HVEs. The dynamics and dispersal range of the dental sprays were visualized using a laser light sheet. In addition, environmental surface pollution was monitored three-dimensionally using water-sensitive papers. Results: Although the HVEs were effective in both the tests, the use of EOV alone increased vertical dispersal and pollution. Conclusions: The use of various types of HVEs to reduce the exposure of operators and assistants to dental sprays when using dental rotary cutting instruments is beneficial. The study findings will be helpful in the event of a future pandemic caused by an emerging or re-emerging infectious disease.