Details of a Researcher - HATAKENAKA Masamitsu

Papers - HATAKENAKA Masamitsu

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Apparent diffusion coefficient is a prognostic factor of head and neck squamous cell carcinoma treated with radiotherapy

Masamitsu Hatakenaka, Katsumasa Nakamura, Hidetake Yabuuchi, Yoshiyuki Shioyama, Yoshio Matsuo, Takeshi Kamitani, Masato Yonezawa, Takashi Yoshiura, Torahiko Nakashima, Mitsuru Mori, Hiroshi Honda

JAPANESE JOURNAL OF RADIOLOGY ( SPRINGER ) 32 ( 2 ) 80 - 89 2014.02 [Refereed]

To evaluate the correlation between apparent diffusion coefficient (ADC) and prognosis in head and neck squamous cell carcinoma (HNSCC) treated with radiotherapy. We retrospectively studied 41 patients (38 male and 3 female, ages 37-85 years) diagnosed with HNSCC (14 oropharynx, 22 hypopharynx, 4 larynx, 1 oral cavity) and treated with radiotherapy, with radiation dose to gross tumor volume over 60 Gy. The association between age, gender, performance status, tumor location, T stage, N stage, stage, dose, overall treatment time, treatment method, adjuvant therapy, or ADC and prognosis was analyzed using a Cox proportional hazard test. ADC calculated with b-values of 300, 500, 750, and 1,000 s/mm(2) (ADC 300-1,000) alone showed a significant correlation with all of the analyses (p = 0.022 for local control, p = 0.0109 for regional control, p = 0.0041 for disease-free survival, and p = 0.0014 for overall survival). ADC calculated with b-values of 0, 100, and 200 s/mm(2) (ADC 0-200) showed a significant correlation with overall survival (p = 0.0012). N stage showed a significant correlation with regional control (p = 0.0241). Performance status showed significant association with local control (p = 0.0459), disease-free survival (p = 0.023), and overall survival (p = 0.0151), respectively. ADC is an independent predictor of prognosis in HNSCC treated with radiotherapy.

PARP阻害剤オラパリブの放射線増感効果のメカニズム

染谷正則, 三浦勝利, 坂田耕一, 中田健生, 堀正和, 畠中正光

Japanese Journal of Radiology ( (公社)日本医学放射線学会 ) 32 ( Suppl. ) 5 - 5 2014.02

Feasibility of low-radiation-dose CT for abdominal examinations with hybrid iterative reconstruction algorithm: Low-contrast phantom study

Masatoshi Kondo, Masamitsu Hatakenaka, Ko Higuchi, Taisuke Fujioka, Takashi Shirasaka, Yasuhiko Nakamura, Katsumasa Nakamura, Takashi Yoshiura, Hiroshi Honda

Radiological Physics and Technology ( 2 ) 6 ( 2 ) 287 - 292 2013.07 [Refereed]

Our purpose in this study was to evaluate the image quality of low-radiation-dose CT using hybrid iterative reconstruction (HIR), and to compare the results with those of filtered back projection (FBP) at routine doses. We measured the mean values and standard deviation of the CT numbers within and outside a 15-mm low-contrast object cylinder at 1.0 % contrast level. The noise reduction levels of the HIR were 1 (weak) to 7 (strong). Visual inspection of the low-contrast detectability was done by six radiologic technologists. The low-contrast detectability of the cylinder at the 1.0 % contrast level with HIR at all mAs levels was equal to that obtained with FBP, and thus the use of HIR did not result in any improvement of low-contrast detectability. © 2013 Japanese Society of Radiological Technology and Japan Society of Medical Physics.

[Optimized magnetic resonance sequences and parameters with operative assisted images for radical prostatectomy at 3 tesla-magnetic resonance image].

Shirase R, Sakurai Y, Nagahama H, Harada K, Takashima H, Nakanishi M, Harada K, Shishido H, Imamura R, Sakata M, Hatakenaka M

Nihon Hoshasen Gijutsu Gakkai zasshi ( 5 ) 69 ( 5 ) 529 - 534 2013.05 [Refereed] [Domestic journal]

The objective of our study was to optimize magnetic resonance image (MRI) sequences and parameters using operative assisted images (three-dimensional images) for radical prostatectomy at 3 tesla (T) MRI. Five healthy volunteers underwent MRI on the 3.0 T scanner. Various sequences and parameters [Cube (TE/TR = 18, 50, 90 ms/2000 ms), FIESTA (TE/TR/FA = 2.4 ms/5 ms/40 degrees, 90 degrees), fSPGR (TE/TR/FA = 2.3 ms/11.2 ms/20 degrees), slice thickness = 1.2 mm, matrix = 192 x 160] were respectively compared. Several structures of the pelvis (the central zones and transition zones of the prostate, the peripheral zones of the prostate, seminal vesicles, rectum wall, bladder, muscle and fat) were determined. The signal intensities of these structures were measured on reformatted axial images and compared against several structures of the pelvis. Correlation with various sequences and parameters was based on the signal-to-noise ratio (SNR), the contrast ratio (CR) and the presence of artifacts. Student's t-test was used for statistical analysis. With Cube (TE/TR = 50 ms/2000 ms), the average value of visual evaluation with artifacts was high, and SNR and CR were higher than for other sequence and parameters. Optimized MRI sequences and parameters were Cube (TE/TR = 50 ms/2000 ms) which provides improved SNR and CR and the presence of artifacts with operative assisted images for radical prostatectomy. These operative assisted images obtained from Cube (TE/TR = 50 ms/2000 ms) are likely to be useful for surgery.

3T-MR装置を用いた根治的前立腺全摘除術における手術支援用3D画像作成のための適切なMR撮像シーケンスと撮像条件の検討

白勢竜二, 櫻井佑樹, 長濱宏史, 原田邦明, 高島弘幸, 中西光広, 原田耕平, 宍戸博紀, 今村塁, 坂田元道, 畠中正光

日本放射線技術学会雑誌 ( (公社)日本放射線技術学会 ) 69 ( 5 ) 529 - 534 2013.05 [Refereed]

3T-MR装置を用い、根治的前立腺全摘除術に対する支援画像(3D画像)に適した撮像方法について検討した。シーケンスはfast spin-echo sequence-Cube、three-dimensional fast imaging employing steady state acquisition(FIESTA)、three-dimensional fast spoiled gradient recalled acquisition in the steady state(fSPGR)を用い、Cubeではeco time(TE)を変化させて3通り、FIESTAではflip angle(FA)を変えて2通りの計6通りの撮像条件とし、健常者5名(平均48.4歳)を対象に10ヶ所の領域でアーチファクト、signal-to-noise ratio(SNR)、コントラスト比を評価した。その結果、アーチファクトのスコアはFIESTA群が1.8以上、CubeおよびfSPGRは0〜0.8であった。SNRが最も高値を示したのはFIEST(FA 40°)であったが、アーチファクトのスコアは2.0であった。最終結果として、最も適切な撮像方法はCube(TE 50ms/TR 2000ms)であった。

Differences in Tibiotalar Joint Alignment During Non-loaded and Axial Loaded Condition in Intact Male Feet

Nozaki Shuhei, Taniguchi Keigo, Takashima Hiroyuki, Watanabe Kota, Hatakenaka Masamitsu, Katayose Masaki

MEDICINE AND SCIENCE IN SPORTS AND EXERCISE ( LIPPINCOTT WILLIAMS & WILKINS ) 45 ( 5 ) 55 - 56 2013.05 [Refereed]

T1 rho is superior to T2 mapping for the evaluation of articular cartilage denaturalization with osteoarthritis: Radiological-pathological correlation after total knee arthroplasty

Yukihisa Takayama, Masamitsu Hatakenaka, Hidetoshi Tsushima, Ken Okazaki, Takashi Yoshiura, Masato Yonezawa, Kei Nishikawa, Yukihide Iwamoto, Hiroshi Honda

EUROPEAN JOURNAL OF RADIOLOGY ( ELSEVIER IRELAND LTD ) 82 ( 4 ) E192 - E198 2013.04 [Refereed]

Purpose: We compared the diagnostic performance of T1 rho and T2 mappings in the evaluation of denatured articular cartilage with osteoarthritis of the knee. Materials and methods: 2D-Sagittal T1 rho and T2 mappings of the knee were obtained from 16 patients before total knee arthroplasty. After surgery, specimens of the femur and tibia were regionally segmented according to a 5-point scale of the severity of denaturalization. The T1 rho and T2 values in the full thickness of the articular cartilage in each region were measured by two observers. The two mappings were compared for their ability to differentiate between normal and denatured articular cartilage and also for their usefulness in grading the severity of the denaturalization using the area under receiver operating characteristic curves (Az). A p < 0.05 was considered significant for each analysis. Results: The T1 rho mapping showed a significantly higher Az value than the T2 mapping for the differentiation between normal and denatured articular cartilage (p < 0.05). Regarding the assessment of the severity of denaturalization, T1 rho mapping could differentiate between normal and mild denaturalization (p < 0.05), but T2 mapping could not. However, there were no significant differences between the two mappings in the discrimination of mild versus moderate denaturalization or of moderate versus severe denaturalization. The two observers showed good agreement in the results (intraclass correlation coefficient = 0.81 for T1 rho and 0.92 for T2). Conclusion: T1 rho mapping is superior to T2 mapping for the evaluation of denatured articular cartilage with osteoarthritis of the knee. (C) 2012 Elsevier Ireland Ltd. All rights reserved.

Diffusion-weighted imaging (b value = 1500 s/mm2) is useful to decrease false-positive breast cancer cases due to fibrocystic changes

Miho Ochi, Toshiro Kuroiwa, Shunya Sunami, Junji Murakami, Shinichiro Miyahara, Takashi Nagaie, Masafumi Oya, Hidetake Yabuuchi, Masamitsu Hatakenaka

Breast Cancer ( 2 ) 20 ( 2 ) 137 - 144 2013.04 [Refereed]

Background: We aimed to evaluate the application of apparent diffusion coefficient (ADC) values calculated from diffusion-weighted imaging (DWI) (b value = 1500 s/mm2) in the breast imaging reporting and data system (BI-RADS). Methods: For 104 cases of breast lesions with definitive histology diagnosis (45 benign cases, 59 malignant cases) in which breast magnetic resonance imaging was performed, ADC values were compared between benign and malignant cases, between ductal carcinoma in situ (DCIS) and fibrocystic changes, and between DCIS and ductal hyperplasia (one type of fibrocystic change). Diagnostic accuracy was compared for a total of 101 images and for 34 images including only nine DCIS and 25 fibrocystic changes between BI-RADS alone (with categories 4a, 4b, and 5 defined as malignancies) and BI-RADS plus ADC. Results: There were significant differences in mean ADC values between malignant and benign cases (p < 0.0001) and between DCIS and fibrocystic changes (p < 0.002), but not between DCIS and ductal hyperplasia. Positive predictive values were significantly greater for BI-RADS plus ADC than for BI-RADS alone in all cases (70.5% for BI-RADS alone, 81.3% for BI-RADS plus ADC) and in cases of DCIS versus fibrocystic changes (40.9% for BI-RADS alone, 64.3% for BI-RADS plus ADC), resulting in a significant improvement in diagnostic accuracy with the addition of ADC. Conclusion: Adding ADC values calculated from DWI (b value = 1500 s/mm2) to BI-RADS is a useful way to improve differential diagnostic accuracy for malignant tumors and benign lesions, especially for DCIS versus fibrocystic changes, except in cases of ductal hyperplasia. © 2011 The Japanese Breast Cancer Society.

Detection of axillary node metastasis using diffusion-weighted MRI in breast cancer

Takeshi Kamitani, Masamitsu Hatakenaka, Hidetake Yabuuchi, Yoshio Matsuo, Nobuhiro Fujita, Mikako Jinnouchi, Michinobu Nagao, Kengo Shirahane, Eriko Tokunaga, Hiroshi Honda

Clinical Imaging ( 1 ) 37 ( 1 ) 56 - 61 2013.01 [Refereed]

Breast magnetic resonance imagings (MRIs) including diffusion-weighted MRI (DWI) of 110 breast cancers (26 with pathologically proven axillary node metastasis and 84 without metastasis) were retrospectively studied. Axillary nodes were detected as high-signal-intensity areas on DWI in 71 cancers (24 with metastasis and 47 without) and not detected in 39 cancers (2 with metastasis and 37 without). The ADC of metastatic nodes was significantly greater than that of the benign ones (1.08±0.18×10-3 mm2/s vs. 0.92±0.22×10-3 mm2/s, P=004). When detectability of axillary nodes on DWI and ADC over 1.05×10-3 mm2/s was applied as a threshold, 53.8% sensitivity, 86.9% specificity, and 79.1% accuracy were provided. © 2013 Elsevier Inc.

Vascular measurement changes observed using postmortem computed tomography

Hideki Hyodoh, Taishi Sato, Maki Onodera, Hirokazu Washio, Tadashi Hasegawa, Masamitsu Hatakenaka

JAPANESE JOURNAL OF RADIOLOGY ( SPRINGER ) 30 ( 10 ) 840 - 845 2012.12 [Refereed]

Postmortem vascular changes were quantitatively analyzed in the aorta and vena cava and compared with antemortem findings as a basis for distinguishing between normal postmortem changes and pathological changes. Whole-body computed tomography (CT) was performed on 12 individuals before and after death. The scans, performed at seven levels (five for the aorta, two for the vena cava) within the vasculature, allowed various measurements to be made on the same individual before and after death. Postmortem long-axis diameter, short-axis diameter, and the square of the radius of the aorta were 79.2-85.0 % (mean 81.3 %), 55.6-80.0 % (68.0 %), and 48.5-71.4 % (60.8 %) of the antemortem measurements, respectively. The ante- and postmortem measurements of the long and short axes and the caliber of the aorta were statistically different (p < 0.05). The superior vena cava (SVC) was increased in size: the short-axis diameter and the square of the radius were both statistically different after death. None of the measured parameters of the inferior vena cava (IVC) changed significantly following death. In postmortem images, the aortic diameter decreased and changes in the size and shape of the SVC were noted. The IVC did not exhibit significant postmortem changes.

Evaluation of cartilage degradation in arthritis using T1 rho magnetic resonance imaging mapping

Hidetoshi Tsushima, Ken Okazaki, Yukihisa Takayama, Masamitsu Hatakenaka, Hiroshi Honda, Toshiaki Izawa, Yasuharu Nakashima, Hisakata Yamada, Yukihide Iwamoto

RHEUMATOLOGY INTERNATIONAL ( SPRINGER HEIDELBERG ) 32 ( 9 ) 2867 - 2875 2012.09 [Refereed]

T1 rho magnetic resonance imaging (MRI) can be used to map proteoglycan (PG) loss in cartilage. Here, we used T1 rho MRI to map cartilage degradation in osteoarthritis (OA) and rheumatoid arthritis (RA). Tissue samples were obtained from five RA patients and 14 OA patients following total knee arthroplasty (TKA). Three parameters were measured: First, macroscopic grading of cartilage sample tissues was performed on a 5-grade scale (G0: normal, G1: swelling, G2: superficial fibrillation, G3: deep fibrillation, G4: subchondral bone exposure). Second, semi-quantitative values of PG were assessed by measuring the optical density of Safranin-O-stained paraffin sections that had been digitally photographed. Third, cartilage was divided into superficial and deep layers and the T1 rho values were quantified. T1 rho values of OA and RA in the superficial layers showed significant differences between groups (G0/1 and G0/2 for OA; G0/2 and G1/2 for RA). In the deep layers, T1 rho values of OA and RA also differed significantly between groups. In both the superficial and deep layers, there was a significant correlation between the mean T1 rho values and macroscopic grading (P < 0.01 for OA, P < 0.001 for RA). We found a negative correlation between the score of Safranin-O staining and T1 rho values (r = -0.61 for OA, r = -0.79 for RA). In addition, RA subjects had significantly higher T1 rho values than OA subjects of similar morphologic grade. In conclusion, T1 rho MRI is able to detect and map the early stages of cartilage degradation in OA and RA. This method is reliable and useful for the evaluation of macromolecular changes in arthritic cartilage.

Pharmacokinetic analysis based on dynamic contrast-enhanced MRI for evaluating tumor response to preoperative therapy for oral cancer

Toru Chikui, Erina Kitamoto, Shintaro Kawano, Tsuyoshi Sugiura, Makoto Obara, Arjan W. Simonetti, Masamitsu Hatakenaka, Yoshio Matsuo, Shoichi Koga, Masahiro Ohga, Katsumasa Nakamura, Kazunori Yoshiura

JOURNAL OF MAGNETIC RESONANCE IMAGING ( WILEY-BLACKWELL ) 36 ( 3 ) 589 - 597 2012.09 [Refereed]

Purpose: To evaluate whether a pharmacokinetic analysis is useful for monitoring the response of oral cancer to chemoradiotherapy (CRT). Materials and Methods: Twenty-nine patients were included. They underwent dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) before and after CRT. The DCE-MRI data were analyzed using a Tofts and Kermode (TK) model. The histological evaluation of the effects of CRT was performed according to Ohboshi and Shimosato's classification. Results: None of the pre-CRT parameters were significantly different between the responders and nonresponders. The post-CRT volume of the extravascular extracellular space (EES) per unit volume of tissue (ve) of responders (0.397 +/- 0.080) was higher than that of nonresponders (0.281 +/- 0.076) (P = 0.01). The change of the ve between the pre- and post-CRT of the responders (0.154 +/- 0.093) was larger than that of the nonresponders (0.033 +/- 0.073) (P = 0.001). Therefore, the increase in the ve strongly suggested a good tumor response to CRT, which reflected an increase of the EES secondary to the destruction of the cancer nest. The changes in the volume transfer constant (Ktrans) were significantly different between the responders and nonresponders (P = 0.018). Conclusion: Both the increase of the ve and the elevation of permeability (Ktrans) were indicative of a good tumor response to CRT. The pharmacokinetic analysis had potential for monitoring the histopathological response to CRT. J. Magn. Reson. Imaging 2012;36:589597. (C) 2012 Wiley Periodicals, Inc.

Acute Cardiac Impairment Associated With Concurrent Chemoradiotherapy for Esophageal Cancer: Magnetic Resonance Evaluation

Masamitsu Hatakenaka, Masato Yonezawa, Takeshi Nonoshita, Katsumasa Nakamura, Hidetake Yabuuchi, Yoshiyuki Shioyama, Michinobu Nagao, Yoshio Matsuo, Takeshi Kamitani, Taiki Higo, Kei Nishikawa, Taro Setoguchi, Hiroshi Honda

INTERNATIONAL JOURNAL OF RADIATION ONCOLOGY BIOLOGY PHYSICS ( ELSEVIER SCIENCE INC ) 83 ( 1 ) E67 - E73 2012.05 [Refereed]

Purpose: To evaluate acute cardiac effects of concurrent chemoradiotherapy (CCRT) for esophageal cancer. Methods and Materials: This prospective study was approved by the institutional review board, and written informed consent was obtained from all participants. The left ventricular function (LVF) of 31 patients with esophageal cancer who received cisplatin and 5-fluorouracil-based CCRT was evaluated using cardiac cine magnetic resonance imaging. The patients were classified into two groups according to mean LV dose. The parameters related to LVF were compared between before and during (40 Gy) or between before and after CCRT using a Wilcoxon matched-pairs single rank test, and parameter ratios (during/before CCRT, after/before CCRT) were also compared between the groups with a t test. Data were expressed as mean +/- SE. Results: In the low LV-dose group (n = 10; mean LV dose <0.6 Gy), LV ejection fraction decreased significantly (before vs. during vs. after CCRT; 62.7% +/- 2.98% vs. 59.8% +/- 2.56% vs. 60.6% +/- 3.89%; p < 0.05). In the high LV-dose group (n = 21; mean LV dose of 3.6-41.2 Gy), LV end-diastolic volume index (before vs. after CCRT; 69.1 +/- 2.93 vs. 57.0 +/- 3.23 mL/m(2)), LV stroke volume index (38.6 +/- 1.56 vs. 29.9 +/- 1.60 mL/m(2)), and LV ejection fraction (56.9% +/- 1.79% vs. 52.8% +/- 1.15%) decreased significantly (p < 0.05) after CCRT. Heart rate increased significantly (before vs. during vs. after CCRT; 66.8 +/- 3.05 vs. 72.4 +/- 4.04 vs. 85.4 +/- 3.75 beats per minute, p < 0.01). Left ventricle wall motion decreased significantly (p < 0.05) in segments 8 (before vs. during vs. after CCRT; 6.64 +/- 0.54 vs. 4.78 +/- 0.43 vs. 4.79 +/- 0.50 mm), 9 (6.88 +/- 0.45 vs. 5.04 +/- 0.38 vs. 5.27 +/- 0.47 mm), and 10 (9.22 +/- 0.48 vs. 8.08 +/- 0.34 vs. 8.19 +/- 0.56 mm). The parameter ratios of LV end-diastolic volume index, stroke volume index, wall motion in segment 9, and heart rate showed significant difference (p < 0.05) after CCRT between the groups. Conclusions: Concurrent chemoradiotherapy for esophageal cancer impairs LVF from an early treatment stage. This impairment is prominent in patients with high LV dose. (C) 2012 Elsevier Inc.

Subendocardial contractile impairment in chronic ischemic myocardium: assessment by strain analysis of 3T tagged CMR

Michinobu Nagao, Masamitsu Hatakenaka, Yoshio Matsuo, Takeshi Kamitani, Ko Higuchi, Fumiaki Shikata, Mitsugi Nagashima, Teruhito Mochizuki, Hiroshi Honda

JOURNAL OF CARDIOVASCULAR MAGNETIC RESONANCE ( BIOMED CENTRAL LTD ) 14 14 2012.02 [Refereed]

Background: The purpose of this study was to quantify myocardial strain on the subendocardial and epicardial layers of the left ventricle (LV) using tagged cardiovascular magnetic resonance (CMR) and to investigate the transmural degree of contractile impairment in the chronic ischemic myocardium. Methods: 3T tagged CMR was performed at rest in 12 patients with severe coronary artery disease who had been scheduled for coronary artery bypass grafting. Circumferential strain (C-strain) at end-systole on subendocardial and epicardial layers was measured using the short-axis tagged images of the LV and available software (Intag; Osirix). The myocardial segment was divided into stenotic and non-stenotic segments by invasive coronary angiography, and ischemic and non-ischemic segments by stress myocardial perfusion scintigraphy. The difference in C-strain between the two groups was analyzed using the Mann-Whitney U-test. The diagnostic capability of C-strain was analyzed using receiver operating characteristics analysis. Results: The absolute subendocardial C-strain was significantly lower for stenotic (-7.5 +/- 12.6%) than non-stenotic segment (-18.8 +/- 10.2%, p < 0.0001). There was no difference in epicardial C-strain between the two groups. Use of cutoff thresholds for subendocardial C-strain differentiated stenotic segments from non-stenotic segments with a sensitivity of 77%, a specificity of 70%, and areas under the curve (AUC) of 0.76. The absolute subendocardial C-strain was significantly lower for ischemic (-6.7 +/- 13.1%) than non-ischemic segments (-21.6 +/- 7.0%, p < 0.0001). The absolute epicardial C-strain was also significantly lower for ischemic (-5.1 +/- 7.8%) than non-ischemic segments (-9.6 +/- 9.1%, p < 0.05). Use of cutoff thresholds for subendocardial C-strain differentiated ischemic segments from non-ischemic segments with sensitivities of 86%, specificities of 84%, and AUC of 0.86. Conclusions: Analysis of tagged CMR can non-invasively demonstrate predominant impairment of subendocardial strain in the chronic ischemic myocardium at rest.

Exogenous Lipoid Pneumonia Induced by Aspiration of Insecticide

Keisuke Ishimatsu, Takeshi Kamitani, Yoshio Matsuo, Masamitsu Hatakenaka, Shunya Sunami, Mikako Jinnouchi, Michinobu Nagao, Hidetake Yabuuchi, Hiroshi Honda

JOURNAL OF THORACIC IMAGING ( LIPPINCOTT WILLIAMS & WILKINS ) 27 ( 1 ) W18 - W20 2012.01 [Refereed]

Exogenous lipoid pneumonia is a rare disorder caused by inhalation and/or aspiration of oil-based substances. The confirmed diagnosis of exogenous lipoid pneumonia is difficult, especially in cases for which it is impossible to ascertain a history of inhalation or aspiration. We present a case of exogenous lipoid pneumonia due to aspiration of insecticide, for which the computed tomography findings of fat attenuation within the lesion were helpful in reaching a correct diagnosis.

Reduction of the unnecessary dose from the over-range area with a spiral dynamic z-collimator: Comparison of beam pitch and detector coverage with 128-detector row CT

Takashi Shirasaka, Yoshinori Funama, Mutsukazu Hayashi, Shinichi Awamoto, Masatoshi Kondo, Yasuhiko Nakamura, Masamitsu Hatakenaka, Hiroshi Honda

Radiological Physics and Technology ( 1 ) 5 ( 1 ) 53 - 58 2012.01 [Refereed]

Our purpose in this study was to assess the radiation dose reduction and the actual exposed scan length of over-range areas using a spiral dynamic z-collimator at different beam pitches and detector coverage. Using glass rod dosimeters, we measured the unilateral over-range scan dose between the beginning of the planned scan range and the beginning of the actual exposed scan range. Scanning was performed at detector coverage of 80.0 and 40.0 mm, with and without the spiral dynamic z-collimator. The dose-saving ratio was calculated as the ratio of the unnecessary over-range dose, with and without the spiral dynamic z-collimator. In 80.0 mm detector coverage without the spiral dynamic z-collimator, the actual exposed scan length for the over-range area was 108, 120, and 126 mm, corresponding to a beam pitch of 0.60, 0.80, and 0.99, respectively. With the spiral dynamic z-collimator, the actual exposed scan length for the over-range area was 48, 66, and 84 mm with a beam pitch of 0.60, 0.80, and 0.99, respectively. The dose-saving ratios with and without the spiral dynamic z-collimator for a beam pitch of 0.60, 0.80, and 0.99 were 35.07, 24.76, and 13.51%, respectively. With 40.0 mm detector coverage, the dose-saving ratios with and without the spiral dynamic z-collimator had the highest value of 27.23% with a low beam pitch of 0.60. The spiral dynamic z-collimator is important for a reduction in the unnecessary over-range dose and makes it possible to reduce the unnecessary dose by means of a lower beam pitch. © Japanese Society of Radiological Technology and Japan Society of Medical Physics 2011.

Angiomyolipomas of the Mediastinum and the Lung

Koichiro Morita, Yoshitaka Shida, Kenji Shinozaki, Satoru Uehara, Takashi Seto, Kenji Sugio, Yukito Ichinose, Kenichi Nishiyama, Yoshio Matsuo, Masamitsu Hatakenaka, Hiroshi Honda

JOURNAL OF THORACIC IMAGING ( LIPPINCOTT WILLIAMS & WILKINS ) 27 ( 1 ) W21 - W23 2012.01 [Refereed]

Ytterbium-based PARACEST Agent: Feasibility of CEST Imaging on a Clinical MR Scanner

Yukihisa Takayama, Takashi Yoshiura, Akihiro Nishie, Tomohiro Nakayama, Masamitsu Hatakenaka, Naoki Kato, Satoshi Yoshise, Jochen Keupp, Dirk Burdinski, Hiroshi Honda

MAGNETIC RESONANCE IN MEDICAL SCIENCES ( JPN SOC MAGNETIC RESONANCE IN MEDICINE ) 11 ( 1 ) 35 - 41 2012 [Refereed]

Purpose: We investigated the feasibility of performing chemical exchange saturation transfer (CEST) imaging using ytterbium-based paramagnetic CEST (PARACEST) agents on a clinical magnetic resonance (MR) scanner. Materials and Methods: We prepared solutions of 3 different ytterbium-based PARACEST agents at concentrations of 5, 10, 20, and 50 mM at a pH of 7.4 and at a concentration of 50 mM at pHs of 3.0, 5.0, 7.4, and 9.5. We acquired images with a turbo spin echo technique using a quadrature head coil and a clinical 3.0-tesla MR system in accordance with the safety limits of the specific absorption rate (SAR). We acquired CEST images with presaturation offset frequencies from -5,000 Hz (-39.1 ppm) to 5,000 Hz (39.1 ppm) with an interval of 500 Hz (3.9 ppm) for each condition. We repeated each scan 3 times and then calculated the mean and standard deviations of the magnitude of the CEST effect at different concentrations and pH values for each agent. We used one-way analysis of variance and Tukey's honestly significant difference post hoc test to compare mean values of the magnitude of the CEST effect obtained at different concentrations and pH values. P < 0.05 was considered significant. Results: PARACEST agents showed a strong CEST effect at their specific presaturation offset frequencies. For each agent, the CEST effect showed significant concentration dependency (P < 0.05), increasing with agent concentration, and significant pH dependency (P < 0.05), with strong effect near physiological pH. Conclusion: CEST imaging using ytterbium-based PARACEST agents might be feasible on a clinical MR scanner with further modifications, such as adjustments of the presaturation radiofrequency pulse and imaging protocols.

Non-Small Cell Lung Cancer: Detection of Early Response to Chemotherapy by Using Contrast-enhanced Dynamic and Diffusion-weighted MR Imaging

Hidetake Yabuuchi, Masamitsu Hatakenaka, Koichi Takayama, Yoshio Matsuo, Shunya Sunami, Takeshi Kamitani, Mikako Jinnouchi, Shuji Sakai, Yoichi Nakanishi, Hiroshi Honda

RADIOLOGY ( RADIOLOGICAL SOC NORTH AMERICA ) 261 ( 2 ) 598 - 604 2011.11 [Refereed]

Purpose: To evaluate the ability of dynamic contrast material-enhanced and diffusion-weighted (DW) magnetic resonance (MR) imaging to help detect early response to chemotherapy in patients with non-small cell lung cancer (NSCLC). Materials and Methods: This study was approved by the institutional review board, and written informed consent was obtained from all subjects. Twenty-eight patients with stage IIIB or IV NSCLC (17 women, 11 men; mean age, 64.8 years) who underwent chemotherapy were enrolled. All patients underwent MR imaging before and after the first course of chemotherapy. The time to peak enhancement, maximum enhancement ratio, and washout ratio were determined from the time-signal intensity curves of dynamic contrast-enhanced MR images. The apparent diffusion coefficient (ADC) of each lung carcinoma was calculated from DW MR images. The responses of these parameters to the first course of chemotherapy and the pretreatment ADC itself were compared with final tumor size reduction by using the Pearson correlation coefficient. Kaplan-Meier curves of progression-free survival and overall survival were generated, and comparisons between the group with a good response of the significant parameter (upper 50th percentile) and that with a poor response of the significant parameter (lower 50th percentile) were performed by using a two-sided log-rank test. Results: Significant correlation was found only between early ADC change and final tumor size reduction rate (r(2) = 0.41, P = .00025). The median progression-free survival for the group with a good increase in ADC was 12.1 months, and that for the group with a stable or decreased ADC was 6.67 months (P = .021), while median overall survival was 22.4 and 12.3 months, respectively (P = .048). Conclusion: ADC seems to be a promising tool for monitoring the early response to or predicting prognosis after chemotherapy of NSCLC. (C) RSNA, 2011

Apparent Diffusion Coefficient Calculated with Relatively High b-Values Correlates with Local Failure of Head and Neck Squamous Cell Carcinoma Treated with Radiotherapy

M. Hatakenaka, Y. Shioyama, K. Nakamura, H. Yabuuchi, Y. Matsuo, S. Sunami, T. Kamitani, T. Yoshiura, T. Nakashima, K. Nishikawa, H. Honda

AMERICAN JOURNAL OF NEURORADIOLOGY ( AMER SOC NEURORADIOLOGY ) 32 ( 10 ) 1904 - 1910 2011.11 [Refereed]

BACKGROUND AND PURPOSE: Few studies have investigated the relationship between ADC and clinical outcome in HNSCC. Our hypothesis has that relatively high pretreatment ADC would correlate with local failure of HNSCC treated with radiation therapy. MATERIALS AND METHODS: This includes prospective and validation studies. Seventeen patients treated with radiation therapy for primary HNSCC completed the prospective study. Variables considered to affect local failure including MR imaging-related parameters such as ADC and its change ratio were compared between patients with local failure and controls, and those showing difference or association with local failure were further tested by survival analysis. Furthermore, variables were analyzed in 40 patients enrolled in the validation study. RESULTS: Relatively high ADC calculated with b-values 1300, 500, 750, and 1000 s/mm(2)) before treatment, high ADC increase ratio, and treatment method (chemoradiotherapy versus radiation therapy alone) revealed significant difference between patients with local failure and controls or association with local failure. In Cox proportional hazard testing, high ADC before treatment alone showed significant association with local failure (P = .0186). In the validation study, tumor volume before treatment, high ADC before treatment, T stage (112 versus 134), and treatment method showed significance. Tumor volume before treatment (P = .0217) and high ADC before treatment (P = .0001) revealed significant association with local failure in Cox proportional hazard testing. High ADC before treatment was superior to tumor volume before treatment regarding association with local failure. CONCLUSIONS: These results suggest pretreatment ADC obtained at high b-values as well as tumor volume correlate with local failure of HNSCC treated with radiation therapy.

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