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Featured researches published by Youichi Machida.


Ejso | 2013

Diagnostic performance of fluorodeoxyglucose-positron emission tomography/computed tomography combined with ultrasonography-guided fine needle aspiration cytology for identifying axillary lymph node status in patients with breast cancer

Youichi Machida; Kazunori Kubota; Takashi Katayama; Akira Toriihara; Hitoshi Shibuya

AIM The aim of this study was to assess the diagnostic performance of fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT) in combination with ultrasonography-guided fine needle aspiration cytology (US-guided FNAC) for the preoperative diagnosis of axillary lymph node (ALN) metastases in patients with breast cancer. MATERIALS AND METHODS A total of 318 patients with breast cancer were recruited retrospectively. Some of the cases that underwent neoadjuvant chemotherapy (NAC) were included. The sensitivity and specificity of FDG-PET/CT were calculated. We assessed the relationship between the combined results for US-guided FNAC with FDG-PET/CT and the pathological ALN status. RESULTS A total of 271 patients underwent FDG-PET/CT. Of these patients, 41 underwent US-guided FNAC. The sensitivity and the specificity of FDG-PET/CT for the cases without NAC were 18.5%, 97.1%, respectively. The sensitivity in cases with NAC was 68.2%. As a whole, the sensitivity was 40.8%. ALN metastasis was detected using US-guided FNAC in a case with a negative FDG uptake in the ALN. The T stage was T2 in the case and the FDG uptake at the primary site was poor. CONCLUSION FDG-PET/CT has a good specificity for ALN metastasis, although its sensitivity is limited, especially in early-stage cases. In cases with a negative FDG uptake in the ALN, US-guided FNAC may play a role in the detection of lymph node metastasis when the primary tumor size is large and the FDG uptake in the primary tumor is low.


Breast Cancer | 2015

Breast density: the trend in breast cancer screening

Youichi Machida; Mitsuhiro Tozaki; Akiko Shimauchi; Tamiko Yoshida

The primary modality for breast cancer screening is mammography. Recent investigations, however, have indicated that an insufficient number of life-threatening cases have been detected by mammography while mammography can often results in a large number of overdiagnoses. To make breast cancer screening more effective, potential factors that influence screening efficacy need to be elucidated. Breast density is one of limiting factors for breast cancer detection using mammography. In this article, influence of breast density on breast screening is explained. Current topics related to breast density, objective assessment of breast density using applications, revision of breast composition classification in Breast Imaging-Reporting and Data System Mammography fifth edition, and legislative movement regarding breast density in the United States, are also mentioned in this review article.


Nuclear Medicine Communications | 2014

Long-term follow-up using 18F-FDG PET/CT for postoperative olfactory neuroblastoma.

Tomoyuki Fujioka; Akira Toriihara; Kazunori Kubota; Youichi Machida; Shin Nakamura; Seiji Kishimoto; Isamu Ohashi; Hitoshi Shibuya

PurposeThe present study evaluated the usefulness of postoperative fluorine-18 fluorodeoxyglucose (18F-FDG) PET/computed tomography (CT) in the management of olfactory neuroblastoma (ONB). Materials and methodsTen patients (eight men and two women; mean age, 48.5 years) with histologically confirmed ONB who underwent craniofacial resection were retrospectively included in this study. A total of 42 whole-body 18F-FDG PET/CT scans for postoperative surveillance or restaging were reviewed. The mean time from operation until the PET/CT scan was 42.1 months. We evaluated the 18F-FDG uptake and the presence of recurrent lesions during the follow-up period and compared the PET/CT results with the results of MRI and clinical examination (endoscopy). ResultsSeven of the 10 patients had 24 recurrent lesions, and 18 of these recurrent lesions (seven local recurrences, eight cervical lymph node metastases, one intracranial metastasis, and two distant metastases) were 18F-FDG positive (75.0%). Three local recurrences and three intracranial metastases were false negative and were detected by endoscopy and MRI, respectively. The mean time from operation until recurrence was 51.4 months, and 17 lesions (70.8%) occurred more than 2 years after the initial operation. ConclusionAlthough 18F-FDG PET/CT is useful for the detection of postoperative recurrences of ONB, long-term follow-up combined with endoscopy and MRI is mandatory.


Radiology | 2015

Two Distinct Types of Linear Distribution in Nonmass Enhancement at Breast MR Imaging: Difference in Positive Predictive Value between Linear and Branching Patterns

Youichi Machida; Mitsuhiro Tozaki; Akiko Shimauchi; Tamiko Yoshida

PURPOSE To compare positive predictive values (PPVs) of linearly distributed nonmass enhancement (NME) with linear and branching patterns and to identify imaging characteristics of NME that would enable classification as Breast Imaging Reporting and Data System category 3 lesions. MATERIALS AND METHODS The institutional review board approved this retrospective study and waived the requirement to obtain informed consent. Reports of breast magnetic resonance (MR) examinations (n = 9453) that described NME were reviewed from examinations performed at the study institution from January 2008 to December 2011. NME with linear distribution was allocated to one of two subtypes: linear pattern (arrayed in a line) or branching pattern (with branches). The χ(2) test, Fisher exact test, or Student t test was performed for univariate analyses. Factors that showed a significant association with outcome at univariate analyses were assessed with multivariate analyses by using a logistic regression model. Interobserver agreement of the two subtypes between initial interpretation and the interpretation by two additional radiologists who were blinded to any clinical or pathologic information was evaluated with κ analysis. RESULTS Within the 156 linearly distributed NME lesions, the PPV of the branching pattern (71 of 95 lesions [75%]; 95% confidence interval [CI]: 66%, 84%) was significantly higher than that of the linear pattern (five of 61 lesions [8%]; 95% CI: 1%, 15%) (P < .0001). The PPV of linear pattern lesions smaller than 1 cm was 0% (0 of 30 lesions; 95% CI: 0%, 0%). At multivariate analysis, branching pattern and NME lesion size of 1 cm or greater were significant predictors of malignancy (P < .0001 [odds ratio: 21.6; 95% CI: 7.5, 62.2] and P = .015 [odds ratio: 5.8; 95% CI: 1.4, 24.0], respectively). Substantial interobserver agreement was obtained for differentiating the two subtypes, with κ values of 0.64 (95% CI: 0.51, 0.76), 0.70 (95% CI: 0.59, 0.82), and 0.64 (95% CI: 0.51, 0.76) between the initial interpreter and reviewer 1, the initial interpreter and reviewer 2, and reviewer 1 and reviewer 2, respectively. CONCLUSION The branching pattern was a significantly stronger predictor of malignancy than was the linear pattern. NME lesions with a linear pattern that are smaller than 1 cm can be managed with follow-up.


Japanese Journal of Radiology | 2013

Adrenal cortical adenoma arising from an adrenohepatic union

Youichi Machida; Akira Takemoto; Daisuke Ban; Takanobu Yoshimoto; Masatomo Mihara; Hitoshi Shibuya

Although the observation of an adrenohepatic union is not a rare occurrence during autopsies, cases associated with this clinical entity are rarely described. We report a case with an adrenal cortical adenoma arising from adrenohepatic union tissue in a patient with a past history of a liver mass.


Plastic and reconstructive surgery. Global open | 2015

Breast Shape Change Associated with Aging: A Study Using Prone Breast Magnetic Resonance Imaging.

Youichi Machida; Masashi Nakadate

Background: Objective assessments of the shapes of various parts of the body can be made using images acquired with multidetector row computed tomography or magnetic resonance imaging. These images can be useful for understanding the changes in body shape that accompany aging. Methods: Data from our previous bilateral prone breast magnetic resonance imaging studies between March and August 2013 were analyzed. Breast size and volume were measured using these images. All the patients included in the study were divided into a younger group (54 years or younger) and an older group (55 years or older). The values were compared between the 2 groups using paired t tests. Regarding variables that were shown to have a significant difference between the 2 groups, the relationships between age and the values of the variables were evaluated using the Pearson correlation coefficient. Results: A total of 90 breasts, 45 breasts in the younger group and 45 breasts in the older group, were used for analysis. There was a significant correlation between age and craniocaudal nipple deviation (R = −0.38; P < 0.001) and between age and the measured breast volume (R = 0.26; P < 0.05). There was also a significant correlation between the measured breast volume and the craniocaudal nipple deviation (R = −0.48; P < 0.001). Conclusions: A caudal deviation of the nipple and an increase in volume were age-related changes in breast shape. These 2 variables were also correlated.


Acta Radiologica | 2017

Single focus on breast magnetic resonance imaging: diagnosis based on kinetic pattern and patient age:

Youichi Machida; Akiko Shimauchi; Yoshifumi Kuroki; Mitsuhiro Tozaki; Yoshiaki Kato; Kazuei Hoshi; Eisuke Fukuma

Background Because of its small size, a focus in breast magnetic resonance imaging (MRI) must be evaluated on the basis of characteristics other than morphologic features. Patient-related factors including patient age, in conjunction with lesion-related factors, could be useful for decision-making. Purpose To assess the probability of malignant foci based on both lesion- and patient-related factors, and to propose a relevant decision-making method. Material and Methods Foci in our breast MRI database dating from April 2006 to June 2013 were retrospectively identified and analyzed. A Fisher’s exact test or a Mann–Whitney U test were performed for univariate analyses, and factors that showed a significant association with outcome in the univariate analyses were subjected to multivariate analysis using a logistic regression model. A decision tree was then drawn using the significant predictors confirmed by multivariate analysis. Results In total, 184 foci (168 benign, 16 malignant) in 184 patients were analyzed in our study. The presence of a washout pattern and older age were found to be significant predictors of malignancy (P < 0.0001; odds ratio [OR], 17.8; P = 0.021; OR, 1.1, respectively). The main decisive node on the decision tree was the presence of a washout pattern, followed by whether the patient’s age was >63 years. Conclusion An enhancing focus showing a washout pattern, especially in older patients, may warrant immediate biopsy rather than short-interval follow-up.


Academic Radiology | 2017

Breast MRI as a Problem-solving Study in the Evaluation of BI-RADS Categories 3 and 4 Microcalcifications: Is it Worth Performing?

Akiko Shimauchi; Youichi Machida; Ichiro Maeda; Eisuke Fukuma; Kazuei Hoshi; Mitsuhiro Tozaki

RATIONALE AND OBJECTIVES We aimed to investigate the utility of problem-solving breast magnetic resonance imaging (MRI) for mammographic Breast Imaging Reporting and Data System (BI-RADS) categories 3 and 4 microcalcifications. MATERIALS AND METHODS Between January 1, 2010 and December 31, 2011, 138 women with 146 areas of categories 3 and 4 microcalcifications without sonographic correlates underwent breast MRI and had a stereotactic core biopsy using an 11-gauge needle or follow-up at least for 24 months. Positive predictive value (PPV), negative predictive value, sensitivity, and specificity were calculated on the basis of BI-RADS category, with categories 1-3 being considered benign and categories 4 and 5 being considered malignant. RESULTS Twenty-four cases (16.4%) were malignant (18 ductal carcinoma in situ, 6 invasive). MRI increased PPV and specificity from 43% to 68% and from 80% to 93% (P = .054 and .005) compared to mammography. Within 102 category 3 microcalcifications, 5 carcinomas were assessed correctly as category 4 by MRI. Within 44 category 4 microcalcifications, a correct diagnosis was made by MRI in 77% (34 of 44) as opposed to 43% (19 of 44) by mammography, and 80% (20 of 25) of unnecessary biopsies could have been avoided. Within the 24 carcinomas, 5 were negative at MRI. MRI-negative carcinomas have a significantly higher possibility of being low grade (ductal carcinoma in situ or invasive) (P = .0362). CONCLUSIONS Breast MRI has the potential to improve the diagnosis of category 3 or 4 microcalcifications and could alter indications for biopsy. Breast MRI could help predict the presence or absence of higher-grade carcinoma for category 3 or 4 microcalcifications.


World Journal of Radiology | 2016

Tumor characteristics of ductal carcinoma in situ of breast visualized on [F-18] fluorodeoxyglucose-positron emission tomography/computed tomography: Results from a retrospective study

Tomoyuki Fujioka; Kazunori Kubota; Akira Toriihara; Youichi Machida; Kaori Okazawa; Tsuyoshi Nakagawa; Yukihisa Saida; Ukihide Tateishi

AIM To clarify clinicopathological features of ductal carcinoma in situ (DCIS) visualized on [F-18] fluorodeoxyglucose-positron emission tomography/computed tomography (FDG-PET/CT). METHODS This study retrospectively reviewed 52 consecutive tumors in 50 patients with pathologically proven pure DCIS who underwent [F-18] FDG-PET/CT before surgery. [F-18] FDG-PET/CT was performed after biopsy in all patients. The mean interval from biopsy to [F-18] FDG-PET/CT was 29.2 d. [F-18] FDG uptake by visual analysis and maximum standardized uptake value (SUVmax) was compared with clinicopathological characteristics. RESULTS [F-18] FDG uptake was visualized in 28 lesions (53.8%) and the mean and standard deviation of SUVmax was 1.63 and 0.90. On univariate analysis, visual analysis and the SUVmax were associated with symptomatic presentation (P = 0.012 and 0.002, respectively), palpability (P = 0.030 and 0.024, respectively), use of core-needle biopsy (CNB) (P = 0.023 and 0.012, respectively), ultrasound-guided biopsy (P = 0.040 and 0.006, respectively), enhancing lesion ≥ 20 mm on magnetic resonance imaging (MRI) (P = 0.001 and 0.010, respectively), tumor size ≥ 20 mm on histopathology (P = 0.002 and 0.008, respectively). However, [F-18] FDG uptake parameters were not significantly associated with age, presence of calcification on mammography, mass formation on MRI, presence of comedo necrosis, hormone status (estrogen receptor, progesterone receptor and human epidermal growth factor receptor-2), and nuclear grade. The factors significantly associated with visual analysis and SUVmax were symptomatic presentation (P = 0.019 and 0.001, respectively), use of CNB (P = 0.001 and 0.031, respectively), and enhancing lesion ≥ 20 mm on MRI (P = 0.001 and 0.049, respectively) on multivariate analysis. CONCLUSION Although DCIS of breast is generally non-avid tumor, symptomatic and large tumors (≥ 20 mm) tend to be visualized on [F-18] FDG-PET/CT.


Academic Radiology | 2018

Shear Wave Speed of the Lesion in Preoperative Breast Ultrasonography: Association with Disease-free Survival of Patients with Primary Operable Invasive Breast Cancer

Youichi Machida; Akiko Shimauchi; Hidemi Okuma; Mitsuhiro Tozaki; Sachiko Isobe; Eisuke Fukuma

RATIONALE AND OBJECTIVES We aimed to investigate the relationship between shear wave speed (SWS) of the lesion on preoperative breast ultrasonography (US) and disease-free survival of patients with primary operable invasive breast cancer. MATERIALS AND METHODS This retrospective study was approved by our Institutional Review Board. The requirement for informed consent was waived. A total of 195 consecutive newly diagnosed invasive breast cancer patients (age 33-83 years; mean 54.0 years) with preoperative breast US with SWS measurement of the lesion were identified. They underwent surgery between May 2012 and May 2013. SWS was measured at the center and three marginal zones in the main tumors, and the maximum value was used for analyses. For 35 patients who underwent primary systemic therapy (PST), the maximum SWS before PST was used. Cox proportional hazards modeling was used to identify the relationship between clinical-pathologic factors and disease-free survival. RESULTS Fourteen recurrences occurred at 6-47 months (mean 22.3 months) after surgery. On multivariate analysis, a positive history of PST (hazard ratio [HR] = 4.93; 95% confidence interval [CI]: 1.66, 14.70; P = .004), adjuvant chemotherapy (HR = 3.67; 95% CI: 1.11, 12.1; P = .033), and higher maximum SWS (HR = 1.55; 95% CI: 1.07, 2.23; P = .020) were associated with poorer disease-free survival. CONCLUSION Higher maximum SWS on preoperative US, in addition to a positive history of PST and adjuvant chemotherapy, was significantly associated with poorer disease-free survival of patients with invasive breast cancer.

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Mitsuhiro Tozaki

Jikei University School of Medicine

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Akira Toriihara

Tokyo Medical and Dental University

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Kazunori Kubota

Tokyo Medical and Dental University

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Hitoshi Shibuya

Tokyo Medical and Dental University

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Kaori Okazawa

Tokyo Medical and Dental University

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Masashi Nakadate

Tokyo Medical and Dental University

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Takao Igarashi

Jikei University School of Medicine

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Tomoyuki Fujioka

Tokyo Medical and Dental University

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