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Dive into the research topics where Yoshiko Yamashita is active.

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Featured researches published by Yoshiko Yamashita.


European Journal of Radiology | 2012

Frequency and significance of pulmonary nodules on thin-section CT in patients with extrapulmonary malignant neoplasms

Mai Hanamiya; Takatoshi Aoki; Yoshiko Yamashita; Satoshi Kawanami; Yukunori Korogi

PURPOSE To determine the frequency and significance of pulmonary nodules detected on thin-section CT in patients with extrapulmonary malignant neoplasms. MATERIALS AND METHODS The institutional review board approved this study. This study retrospectively evaluated 308 patients with extrapulmonary carcinomas or sarcomas and had undergone thin-section chest CT (2mm slice thickness) for staging. Three radiologists identified non-calcified nodules and evaluated the size, the growth and the distance from the nearest pleural surface. The characteristics of the nodules were defined based on the results of either a diagnostic biopsy or nodule growth. RESULTS One or more non-calcified pulmonary nodules were detected in 75% of the patients (233/308). One hundred and thirty-seven of these patients had nodules that met the criteria of either benign or malignant nodules. Nodules smaller than 10mm were more likely to be benign, whereas those 10mm or greater were more likely to be malignant (22/26, 85%; P<.0001). Most nodules less than 10mm from the pleura were benign (91%), whereas approximately half of the nodules 10mm or more away from the pleura were malignant (20/43, 47%; P<.0001). Patients with melanoma, sarcoma, or testicular carcinoma were more likely to have malignant nodules. A multivariable analysis demonstrated the nodule size (P<.0001) and distance from the pleura were predictive of malignancy. CONCLUSION The nodule detection rate on thin-section CT in patients with extrapulmonary malignancy is high. Most of the nodules smaller than 10mm or less than 10mm from the pleura are benign.


Radiology | 2012

Adenocarcinomas with predominant ground-glass opacity: correlation of morphology and molecular biomarkers.

Takatoshi Aoki; Mai Hanamiya; Hidetaka Uramoto; Masanori Hisaoka; Yoshiko Yamashita; Yukunori Korogi

PURPOSE To retrospectively identify successive changes in peripheral lung adenocarcinoma that feature dominant ground-glass opacity (GGO) at computed tomography (CT) and correlate with biomolecular markers. MATERIALS AND METHODS The institutional review board approved this retrospective study, and all 25 patients provided informed consent. Patients with lung adenocarcinomas smaller than 3 cm in diameter in whom tumor growth could be evaluated with CT before surgery were included. Two thoracic radiologists evaluated tumor growth by analyzing GGO type (pure or mixed) and size increases. Immunohistochemistry of the p53 protein and molecular analysis of the epidermal growth factor receptor (EGFR) and K-ras genes were performed. The Fisher exact test was used to assess statistical significance. RESULTS Tumor size increased in 19 of 25 patients (76%) during the observation period. The CT changes in 19 patients were classified into four patterns: persistent pure GGO (n = 8), change from pure to mixed GGO (n = 3), mixed GGO with growth of solid component (n = 4), and mixed GGO with growth of GGO component (n = 4). The remaining six patients (24%) had pure GGO without any interval changes. Staining for p53 was negative in all 14 patients with pure GGO and positive in six of 11 patients (55%) with mixed GGO (P < .01). In these six patients appearance or growth of the solid component was seen. EGFR mutations were found in both pure (36%) and mixed (45%) GGO lesions (P = .70). CONCLUSION Lung adenocarcinomas with a dominant GGO often possess EGFR mutations. Interval changes in the solid component may be related to p53 inactivation.


American Journal of Roentgenology | 2014

Tomosynthesis of the Wrist and Hand in Patients With Rheumatoid Arthritis: Comparison With Radiography and MRI

Takatoshi Aoki; Masami Fujii; Yoshiko Yamashita; Hiroyuki Takahashi; Hodaka Oki; Yoshiko Hayashida; Kazuyoshi Saito; Yoshiya Tanaka; Yukunori Korogi

OBJECTIVE The purpose of this article is to compare tomosynthesis with radiography and MRI of the wrist and hand for evaluating bone erosion in patients with rheumatoid arthritis (RA). MATERIALS AND METHODS Twenty consecutive patients with an established diagnosis of RA and five control patients were included in this study. They underwent radiography, tomosynthesis, and MRI of the bilateral hand and wrist within a week. The mean total dose of radiography and tomosynthesis was 0.13 and 0.25 mGy, respectively. MRI evaluation was performed according to the Outcome Measures in Rheumatology Clinical Trials recommendations. Bone erosion on images from the three modalities was independently reviewed by two certificated radiologists with a 4-point scale (0, normal; 1, discrete erosion; 2, < 50% of the joint surface; and 3, ≥ 50% of the joint surface). RESULTS The detection rates of bone erosion for radiography, tomosynthesis, and MRI were 26.5%, 36.1%, and 36.7%, respectively. Significantly more bone erosions were revealed with tomosynthesis and MRI than with radiography (p < 0.01). When MRI was used as the reference standard, the sensitivity, specificity, and accuracy were 68.1%, 97.5%, and 86.7%, respectively, for radiography and 94.8%, 97.8%, and 96.7%, respectively, for tomosynthesis. Interobserver agreement (kappa value) for bone erosion was good to excellent on tomosynthesis and MRI for all joints (0.65-1.00 and 0.68-1.00, respectively), whereas it was slight to fair on radiography for some carpal bones and bases of metacarpal bones (0.22-0.56). CONCLUSION Tomosynthesis is superior to radiography and almost comparable to MRI for the detection of bone erosion in patients with RA.


European Journal of Radiology | 2013

Computer-aided detection of lung nodules on multidetector CT in concurrent-reader and second-reader modes: A comparative study

Sumiaki Matsumoto; Yoshiharu Ohno; Takatoshi Aoki; Hitoshi Yamagata; Munenobu Nogami; Keiko Matsumoto; Yoshiko Yamashita; Kazuro Sugimura

PURPOSE To compare the reading times and detection performances of radiologists in concurrent-reader and second-reader modes of computer-aided detection (CAD) for lung nodules on multidetector computed tomography (CT). MATERIALS AND METHODS Fifty clinical multidetector CT datasets containing nodules up to 20mm in diameter were retrospectively collected. For the detection and rating of non-calcified nodules larger than 4mm in diameter, 6 radiologists (3 experienced radiologists and 3 resident radiologists) independently interpreted these datasets twice, once with concurrent-reader CAD and once with second-reader CAD. The reference standard of nodules in the datasets was determined by the consensus of two experienced chest radiologists. The reading times and detection performances in the two modes of CAD were statistically compared, where jackknife free-response receiver operating characteristic (JAFROC) analysis was used for the comparison of detection performances. RESULTS Two hundreds and seven nodules constituted the reference standard. Reading time was significantly shorter in the concurrent-reader mode than in the second-reader mode, with the mean reading time for the 6 radiologists being 132s with concurrent-reader CAD and 210s with second-reader CAD (p<0.01). JAFROC analysis revealed no significant difference between the detection performances in the two modes, with the average figure-of-merit value for the 6 radiologists being 0.70 with concurrent-reader CAD and 0.72 with second-reader CAD (p=0.35). CONCLUSION In CAD for lung nodules on multidetector CT, the concurrent-reader mode is more time-efficient than the second-reader mode, and there can be no significant difference between the two modes in terms of detection performance of radiologists.


Skeletal Radiology | 2012

Osteosclerotic lesions in patients treated with gefitinib for lung adenocarcinomas: a sign of favorable therapeutic response

Yoshiko Yamashita; Takatoshi Aoki; Takeshi Hanagiri; Chiharu Yoshii; Hiroshi Mukae; Hidetaka Uramoto; Yukunori Korogi

ObjectiveTo assess the frequency of osteosclerotic changes on CT that appeared after treatment with gefitinib in patients with lung adenocarcinoma and the relationship between the osteosclerotic changes and the response to the therapy.Materials and methodsOur study included 41 patients with lung adenocarcinoma who underwent chest CT both before (CTpre) and after (CTpost) starting treatment with gefitinib. The presence or absence of bone metastases was assessed on the CTpre, and the interval bony change after the therapy was classified as lytic, sclerotic, or no changes on the CTpost. The relationship between treatment results of primary lung cancer and interval bony changes was evaluated.ResultsOsteosclerotic lesions were identified in 11 patients (27%) on CTpost; in 6 of 11 patients osteosclerotic lesions newly appeared where the CTpre showed no bone metastasis before the gefitinib therapy. There were significant differences in the therapeutic response of the primary cancers (P < 0.001) and in the survival rate (P < 0.01) in patients with osteosclerotic changes versus those without osteosclerotic changes.ConclusionOsteosclerotic changes on CT, observed after gefitinib treatment in patients with lung adenocarcinomas, may be an indicator of a good therapeutic response.


Journal of Magnetic Resonance Imaging | 2013

Iterative decomposition of water and fat with echo asymmetry and least‐squares estimation (IDEAL) of the wrist and finger at 3T: Comparison with chemical shift selective fat suppression images

Takatoshi Aoki; Yoshiko Yamashita; Hodaka Oki; Hiroyuki Takahashi; Yoshiko Hayashida; Kazuyoshi Saito; Yoshiya Tanaka; Yukunori Korogi

To compare fat‐suppressed magnetic resonance imaging (MRI) quality using iterative decomposition of water and fat with echo asymmetry and least‐squares estimation (IDEAL) with that using chemical shift selective fat‐suppressed T1‐weighted spin‐echo (CHESS) images for evaluating rheumatoid arthritis (RA) lesions of the hand and finger at 3T.


Clinical Imaging | 2013

Diagnosis of early-stage rheumatoid arthritis: usefulness of unenhanced and gadolinium-enhanced MR images at 3 T

Takatoshi Aoki; Yoshiko Yamashita; Kazuyoshi Saito; Yoshiya Tanaka; Yukunori Korogi

Forty-one consecutive unclassified arthritis patients with polyarthralgia including wrist joint were evaluated with 3-T MRI as possible early-stage rheumatoid arthritis (RA). After prospective follow-up, 21 of 41 patients fulfilled the American College of Rheumatology (ACR) criteria. Synovitis was detected in all 21 RA patients (sensitivity=100%) with postcontrast MRI and in 14 patients (67%) with unenhanced MRI when none of them fulfilled ACR diagnostic criteria. Fat-suppressed intermediate-weighted fast spin-echo (FSE) image showed high detection rate of synovitis and bone erosion, whereas FIESTA image clearly delineated joint fluid and bone trabeculae. MRI at 3 T is a potentially powerful tool for discriminating and managing early-stage RA patients.


European Journal of Radiology | 2012

Thin-section chest CT findings in systemic lupus erythematosus with antiphospholipid syndrome: A comparison with systemic lupus erythematosus without antiphospholipid syndrome

Hodaka Oki; Takatoshi Aoki; Kazuyoshi Saito; Yoshiko Yamashita; Mai Hanamiya; Yoshiko Hayashida; Yoshiya Tanaka; Yukunori Korogi

PURPOSE To assess thin-section chest CT findings in systemic lupus erythematosus (SLE) with antiphospholipid syndrome (APS), in comparison with SLE without APS. MATERIALS AND METHODS We retrospectively reviewed the medical records and thin-section CT findings of 17 consecutive patients with an established diagnosis of SLE with APS, comparing with 37 consecutive SLE patients without APS, between 2004 and 2008, and patients who had other autoimmune disease, such as Sjögren syndrome, were excluded. No significant differences were seen between the two groups in age, gender, smoking habits, or history of steroid pulse and biological therapy. CT images of 2mm thickness obtained with a 16- or 64-detector row CT were retrospectively evaluated by two radiologists in consensus on ultra high-resolution gray-scale monitors. RESULTS The frequency of thin-section CT abnormalities was higher in SLE with APS group (82%) than in SLE without APS group (43%). Ground-glass opacity (59%), architectural distortion (47%), reticulation (41%), enlarged peripheral pulmonary artery (29%), and mosaic attenuation (29%) were significantly more common in the SLE with APS group than in the SLE without APS group (Fishers exact test, p<0.01). CONCLUSION SLE patients with APS have increased prevalence of thin-section chest CT abnormalities than those without APS.


European Journal of Radiology | 2012

Usefulness of computerized method for lung nodule detection on digital chest radiographs using similar subtraction images from different patients

Takatoshi Aoki; Nobuhiro Oda; Yoshiko Yamashita; Keiji Yamamoto; Yukunori Korogi


Academic Radiology | 2011

Usefulness of Computerized Method for Lung Nodule Detection in Digital Chest Radiographs Using Temporal Subtraction Images

Takatoshi Aoki; Nobuhiro Oda; Yoshiko Yamashita; Keiji Yamamoto; Yukunori Korogi

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Takatoshi Aoki

University of Occupational and Environmental Health Japan

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Yukunori Korogi

University of Occupational and Environmental Health Japan

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Kazuyoshi Saito

University of Occupational and Environmental Health Japan

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Yoshiya Tanaka

University of Occupational and Environmental Health Japan

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Masanori Hisaoka

University of Occupational and Environmental Health Japan

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Chiharu Yoshii

University of Occupational and Environmental Health Japan

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