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Yuji Baba

Publications and source records attributed to Yuji Baba.

9 recordsLinked to original sources
PubMed2006

Spinel-to-CaFe2O4-type structural transformation in LiMn2O4 under high pressure.

A new form of LiMn2O4 is reported. The structure is the CaFe2O4-type and 6% denser than the spinel. The structure transformation was achieved by heating at 6 GPa. Analysis of the neutron diffraction pattern confirmed an average of the structure; the unit cell was orthorhombic at a = 8.8336(5) angstroms, b = 2.83387(18) angstroms, and c = 10.6535(7) angstroms (Pnma). Electron diffraction patterns indicated an order of superstructure 3a x b x c, which might be initiated by Li vacancies. The exact composition is estimated at Li(0.92)Mn2O4 from the structure analysis and quantity of intercalated Li. The polycrystalline CaFe2O4-type compound showed semiconducting-like characters over the studied range above 5 K. The activation energy was reduced to approximately 0.27 eV from approximately 0.40 eV at the spinel form, suggesting a possible enhancement of hopping mobility. Magnetic and specific-heat data indicated a magnetically glassy transition at approximately 10 K. As the CaFe2O4-type transition was observed for the mineral MgAl2O4, hence the new form of the lithium manganese oxide would provide valuable opportunities to study not only the magnetism of strongly correlated electrons but also the thermodynamics of the phase transition in the mantle.

Journal Article↗
PubMed2006

Concurrent chemoradiation therapy with low-dose CDDP and UFT for glottic carcinomas: evaluation using the sixth edition of the UICC TNM staging system.

We evaluated whether low-dose chemotherapy could improve effects of radiation therapy for glottic carcinoma with different prognostic factor based on the UICC 6th edition. Fifty-one patients with T2N0 glottic carcinoma classified by the UICC 5th edition underwent chemoradiation therapy with low-dose CDDP (4 mg/m(2)) and oral UFT (450 mg of tegafur) continuing for four weeks (CRT group). The historical control consisted of 49 patients treated with radiation therapy alone (RT group). Forty-six tumors with the adjacent sign, i.e. tumors located adjacent to the thyroid cartilage on radiological examinations, were classified as T3 according to the 6(th) edition. The 5-year local control and laryngeal preservation rates of the T2 (n=54) vs. T3 (n=46) lesions were 87% vs. 50% (p<0.0001) and 94% vs. 61% (p<0.0001), respectively. Among the T3 lesions, CRT (n=24) yielded significantly higher laryngeal preservation rates than did RT alone (n=22) (83% vs. 40%, p=0.0063), and the local control rates were higher in the CRT- than the RT group (62% vs. 36%, p=0.0882). While such benefits of CRT were not observed in patients with T2 lesions.

Adult↗
PubMed2005

Prognostic factors of glottic carcinomas treated with radiation therapy: value of the adjacent sign on radiological examinations in the sixth edition of the UICC TNM staging system.

PURPOSE: To evaluate the predictive value of the adjacent sign, the tumor adjacent to the thyroid cartilage on radiologic examinations, in the new sixth edition of the International Union Against Cancer (UICC) staging system of glottic carcinoma. METHODS AND MATERIALS: Between 1989 and 1998, 130 patients with T1-2N0 glottic squamous cell carcinoma, classified according to the fifth edition of the UICC staging system and evaluated by computed tomography or magnetic resonance imaging, were treated with radiation therapy (RT). Factor analysis included clinical, radiologic, and treatment characteristics. Tumors with the adjacent sign, considered representative of paraglottic space invasion with or without minor thyroid cartilage erosion, were retrospectively classified as T3-stage tumors by the UICC sixth edition. RESULTS: The 5-year local control rate after RT was 76%. Univariate analysis showed that the T stage according to the UICC fifth edition, supraglottic extension, subglottic extension, tumor size, adjacent sign, total dose, fraction size, field size, and overall treatment time were significant factors for the local control rate. Multivariate analysis confirmed the adjacent sign as the only independent predictor. According to the UICC sixth edition, the 5-year local control, laryngeal preservation, cause-specific survival, and overall survival rates of the T3 (adjacent sign-positive) vs. T1 and T2 (adjacent sign-negative) lesions were 37% vs. 87% (p < 0.0001), 47% vs. 95% (p < 0.0001), 75% vs. 99% (p < 0.0001), and 54% vs. 81% (p = 0.0180), respectively. CONCLUSION: Factor analysis confirmed the adjacent sign as an independent prognostic factor. The UICC sixth edition appears to identify correctly patients with T3 lesions as a high-risk group.

Adult↗
PubMed2004

[Survival of glottic carcinoma patients treated with definitive radiation therapy: value of the Sixth edition of the UICC TNM staging system].

PURPOSE: To evaluate the survival of glottic carcinoma patients treated with radiation therapy (RT). The predictive value of the new sixth edition of the UICC staging system was also evaluated. METHODS AND MATERIALS: 193 patients with T1-2N0 glottic squamous cell carcinoma, classified according to the fifth edition of the UICC staging system, were treated with definitive RT. Of them, 130 patients evaluated with pretreatment radiological examinations (CT and/or MR) were retrospectively classified according to the UICC sixth edition. RESULTS: According to the UICC fifth edition, 132 lesions were staged as T1 and 61 as T2. Thirty lesions were categorized as stage T3 according to the UICC sixth edition. Of all patients, 13 died of glottic carcinoma, 25 of second malignancy, and 20 of intercurrent disease. Second primary sites included lung (n=8), esophagus (n=4), liver (n=4), pancreas (n=3), and others (n=6). The 10-year overall survival rate was 66%, and cause-specific survival rates of glottic carcinoma and second malignancy were 91% and 86%, respectively. Multivariate analysis confirmed T-stage in the UICC sixth edition as an independent predictor for death from glottic carcinoma. Although there were no significant factors for second malignancy, there was no death from second malignancy in non-smoking patients. CONCLUSION: Second malignancy was the most frequent cause of death, and an association with smoking was suggested. The UICC sixth edition appears to correctly identify patients with T3 lesions as a high-risk group not only for local failure but also for survival.

Adult↗
PubMed2003

[Clinical evaluation of esophageal cancer complicated with head and neck cancer].

We prospectively investigated endoscopic findings of the upper digestive tract in patients with head and neck (H & N) cancer, from 1992 to 2001. Of 687 patients with H & N cancer, esophageal cancers were found to affect 74 patients (10.8%). The 74 patients consisted of 49 (66.2%) with the superficial type and 25 (33.8%) with the advanced type. Other additional cancers were detected in 32 cases (4.7%), including 21 gastric cancers. The incidence was highest in patients with hypopharyngeal cancer (32.4%), whereas the incidences in those with oral floor cancer and mesopharyngeal cancer were 14.3% and 13.1%, respectively. The incidence of stage I cancers was lower than that of stage II, III, or IV cancers. Therapy for superficial esophageal cancers consisted of trisection for endoscopic mucosal resection (EMR), surgery, and no treatment. Surgery, radiation therapy, or no treatment was selected in advanced type. For double cancers of H & N and esophagus, treatment should be selected in consideration of the prognosis of the disease. These findings suggest that endoscopy with the Lugol-spraying method should be performed in H & N cancers for early detection of esophageal cancers.

Adult↗
PubMed2002

Dynamic MR imaging and radiotherapy.

Dynamic MRI has been used to improve the detection of tumors and to make differential diagnosis. Most malignant lesions show early enhancement and early washout of contrast media on dynamic MRI, but the characterization of the tumor remains unclear. Pharmacokinetic analysis of dynamic MRI can provide information about the permeability of contrast media in the tumor that may reflect the oxygen concentration of the tumor. This information may be useful in the prediction of a tumor's response to radiation therapy.

Algorithms↗
PubMedDate not supplied

Diffusion-weighted imaging of radiation-induced brain injury for differentiation from tumor recurrence.

BACKGROUND AND PURPOSE: Differentiation between tumor recurrence and treatment-related brain injury is often difficult with conventional MRI. We hypothesized that the diffusion-weighted imaging (DWI) could help differentiate these 2 conditions, because water diffusion may be greater for necrotic tissues in the treatment-related brain injury than for tumor tissues in recurrence. Our aim was to analyze whether DWI findings of recurrent tumor are distinct from those of radiation necrosis. METHODS: Seventeen patients were examined prospectively. Two readers assessed the images by consensus for homogeneity and signal intensity of the lesions. Five regions of interest were drawn within the lesions on trace DWI images and apparent diffusion coefficient (ADC) maps. The minimal, maximal, and mean values of each lesion were compared between the 2 groups. Findings in 12 of 17 patients were verified histologically by surgery or biopsy; the diagnoses in the remaining 5 patients were made on the basis of follow-up MRI findings and clinical follow-up. RESULTS: There were a total of 20 lesions; 12 lesions were due to radiation necrosis and 8 lesions to tumor recurrence. In the radiation necrosis group, 8 lesions had marked hypointensity. In the recurrence group, however, no marked hypointensity was seen. The maximal ADC values within each lesion were significantly smaller for the recurrence group than for the necrosis group (P = .039). CONCLUSION: Radiation necrosis usually showed heterogeneity on DWI images and often included spotty, marked hypointensity. Significant difference was found in the maximal ADC values between radiation necrosis and tumor recurrence. DWI was useful in differentiating recurrent neoplasm from radiation necrosis.

Adult↗