Akio Hiwatashi

Kyushu University, Hukuoka, Fukuoka, Japan

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Publications (98)167.62 Total impact

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    ABSTRACT: Volume isotropic simultaneous interleaved bright- and black-blood examination (VISIBLE) is a recently developed 3D MR sequence that provides simultaneous acquisitions of images with blood vessel suppression (Black) and images without it (Bright). Our purpose was to evaluate the usefulness of VISIBLE in detecting brain metastases. This prospective study included patients with suspected brain metastasis imaged with both VISIBLE and MPRAGE. From a data set, we compared the number of visualized blood vessels and the lesion-to-normal contrast-to-noise ratio (CNR) in 60 patients. We also performed an observer test to compare their diagnostic performance with VISIBLE, MPRAGE and only Black in 34 patients. Diagnostic performance was evaluated using a figure of merit (FOM), sensitivity, false-positive results per case (FPs/case) and reading time. The number of vessels was significantly fewer in Black compared to MPRAGE and Bright (P < 0.0001). CNR was significantly higher with both Black and Bright than with MPRAGE (P < 0.005). In the observer test, significantly higher sensitivity (P < 0.0001) and FOM (P < 0.0001), significantly shorter reading time (P = 0.0001) and similar FPs/case were achieved with VISIBLE compared to MPRAGE. Compared to only Black, VISIBLE resulted in comparable sensitivity, but significantly fewer FPs/case (P = 0.0008). VISIBLE can improve radiologists' diagnostic performance for brain metastasis. • VISIBLE can achieve higher sensitivity and shorter reading time than MPRAGE. • VISIBLE can achieve lower false-positive rates than blood vessel suppressed images. • Compared to MPRAGE, VISIBLE can improve diagnostic performance for brain metastasis.
    European radiology. 11/2014;
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    ABSTRACT: Objective We report the clinical application of intravoxel incoherent motion (IVIM) magnetic resonance (MR) imaging to diagnose a case of mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) in the acute phase.ResultsOn IVIM MR Images of this patient, higher perfusion (f) and diffusion (D) values in the left occipital and temporal lobes were found compared to the contralateral areas.Conclusion These findings imply a breakdown of autoregulation with hyperperfusion and vasogenic edema during the acute phase of MELAS, as described in previous reports. IVIM imaging is a valuable, noninvasive tool that simultaneously quantifies perfusion and diffusion parameters.
    Brain and Behavior. 09/2014;
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    ABSTRACT: To reveal angiographic findings to predict the result of balloon test occlusion (BTO).
    World journal of radiology. 08/2014; 6(8):619-24.
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    ABSTRACT: To evaluate the diagnostic performance of a double-dose administration of gadolinium for brain metastases at 3 T in a systematic observer test.
    Japanese journal of radiology 06/2014; · 0.73 Impact Factor
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    ABSTRACT: Bone density measurements using high-resolution CT have been reported to be useful to diagnose fenestral otosclerosis. However, small region of interest (ROI) chosen by less-experienced radiologists may result in false-negative findings. Semi-automatic analysis such as CT histogram analysis may offer improved assessment. The aim of this study was to evaluate the utility of CT histogram analysis in diagnosing fenestral otosclerosis. Temporal bone CT of consecutive patients with otosclerosis and normal controls was retrospectively analyzed. The control group consisted of the normal-hearing contralateral ears of patients with otitis media, cholesteatoma, trauma, facial nerve palsy, or tinnitus. All CT images were obtained using a 64-detector-row CT scanner with 0.5-mm collimation. AROI encompassing 10 × 10 pixels was placed in the bony labyrinth located anterior to the oval window. The mean CT value, variance and entropy were compared between otosclerosis patients and normal controls using Student's t test. The number of pixels below mean minus SD in the control (%Lowcont) and total subjects (%Lowtotal) were also compared. In addition, the area under the receiver operating characteristic curves (AUC) value for the discrimination between otosclerosis patients and normal controls was calculated. 51 temporal bones of 38 patients with otosclerosis and 30 temporal bones of 30 control subjects were included. The mean CT value was significantly lower in otosclerosis cases than in normal controls (p < 0.01). In addition, variance, entropy, %Lowcont and %Lowtotal were significantly higher in otosclerosis cases than in normal controls (p < 0.01, respectively). The AUC values for the mean CT value, %Lowcont and %Lowtotal were 0.751, 0.760 and 0.765, respectively. In conclusion, our results demonstrated that histogram analysis of CT image may be of clinical value in diagnosing otosclerosis.
    Archives of Oto-Rhino-Laryngology 02/2014; · 1.29 Impact Factor
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    ABSTRACT: PURPOSE To evaluate the utility of the histogram-based analysis of multidetector row CT images in diagnosing otosclerosis. METHOD AND MATERIALS Temporal bone CT of consecutive patients with otosclerosis and normal controls were retrospectively analyzed. The diagnosis of otosclerosis was confirmed during surgery in all cases. The control group consisted of the normal-hearing contralateral ears in patients with otitis media, cholesteatoma, trauma, facial nerve paralysis, or tinnitus. All CT images were obtained using a 64-detector-row CT scanner with 0.5-mm collimation, 80 mm FOV, and a 512 × 512 matrix. A region-of- interest (ROI) encompassing 10 × 10 pixels was placed in the bony labyrinth located anterior to oval window. For each ROI, histogram-based metrics including the mean CT value, variance, kurtosis, skewness were measured. In addition, the energy, contrast, and entropy were derived from the texture analysis. Each metric was compared between the otosclerosis and normal controls groups using Student’s t-test. In addition, the area under the ROC curves (AUC) value for the discrimination between otosclerosis and normal controls was calculated. RESULTS Fifty one temporal bones of 38 patients with otosclerosis (mean age: 49.0 ± 12.4 years old) and 30 control subjects (mean age: 44.6 ± 17.0 years old) were included. The mean CT value, contrast, and energy were significant lower in otosclerosis cases than normal controls (p<0.01, respectively). In addition, the variance and entropy were significant higher in otosclerosis cases than normal controls (p<0.01, respectively). The AUC values for the mean CT value, variance, energy, contrast, and entropy were 0.754, 0.688, 0.669, 0.745 and 0.664, respectively. CONCLUSION Our results demonstrated that the histogram-based analysis of CT images is useful to diagnose otosclerosis. In particular, the mean CT value and the contrast showed higher diagnostic values. CLINICAL RELEVANCE/APPLICATION The histogram-based analysis of multidetector row CT images can be an effective and operator independent tool for diagnosis of fenestral otosclerosis.
    Radiological Society of North America 2013 Scientific Assembly and Annual Meeting; 12/2013
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    ABSTRACT: PURPOSE To assess the feasibility of high–resolution three dimensional diffusion–weighted images (HR3D–DWI) / multi–detector row CT (MDCT) images data fusion for surgical planning for cholesteatoma. METHOD AND MATERIALS A total of 14 patients (M/F= 7/7, age 11 to 72 years, mean 42.5 years) with acquired cholesteatoma underwent preoperative MRI using a 3.0 T clinical unit and an 8-channel head coil. For each subject, HR3D–DWIs were obtained using a turbo field–echo with diffusion–sensitized driven-equilibrium preparation with following parameters: TR/TE = 6.2/3ms, FA = 10°, ETL = 75, b factor = 800s/mm2, voxel size = 1.5×1.5×1.5mm3, NEX = 2, SENSE factor = 2, and acquisition time = 5min19s. These patients also underwent MDCT with a slice thickness of 0.5mm. Fusion of the HR3D–DWIs and MDCT images was performed using a landmark rigid registration method by a board–certified neuroradiologist on a workstation. The location and extent of cholesteatomas on the fused images was compared with the intraoperative findings. RESULTS On the fused images, the extent of the cholesteatoma, which was depicted as a conspicuous high intensity lesion could be easily evaluated with background bony structures. In all patients, the location and extent of the cholesteatoma on the fused images corresponded well with the intraoperative findings. CONCLUSION Image fusion between HR3D–DWI and MDCT images is feasible, and provides valuable preoperative information for surgical planning to otorhinolaryngologists. CLINICAL RELEVANCE/APPLICATION Our HR 3D–DWI has isotropic voxel dimensions that enables reformation in any arbitrary plane. It makes easier anatomical registration with CT images and leads to advantages of preoperative planning.
    Radiological Society of North America 2013 Scientific Assembly and Annual Meeting; 12/2013
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    ABSTRACT: Background Amide proton transfer (APT) imaging is a novel molecular MRI technique to detect endogenous mobile proteins and peptides through chemical exchange saturation transfer. We prospectively assessed the usefulness of APT imaging in predicting the histological grade of adult diffuse gliomas.Methods Thirty-six consecutive patients with histopathologically proven diffuse glioma (48.1 ± 14.7 y old, 16 males and 20 females) were included in the study. APT MRI was conducted on a 3T clinical scanner and was obtained with 2 s saturation at 25 saturation frequency offsets ω = -6 to +6 ppm (step 0.5 ppm). δB0 maps were acquired separately for a point-by-point δB0 correction. APT signal intensity (SI) was defined as magnetization transfer asymmetry at 3.5 ppm: magnetization transfer ratio (MTR)asym = (S[-3.5 ppm] - S[+3.5 ppm])/S0. Regions of interest were carefully placed by 2 neuroradiologists in solid parts within brain tumors. The APT SI was compared with World Health Organization grade, Ki-67 labeling index (LI), and cell density.ResultsThe mean APT SI values were 2.1 ± 0.4% in grade II gliomas (n = 8), 3.2 ± 0.9% in grade III gliomas (n = 10), and 4.1 ± 1.0% in grade IV gliomas (n = 18). Significant differences in APT intensity were observed between grades II and III (P < .05) and grades III and IV (P < .05), as well as between grades II and IV (P < .001). There were positive correlations between APT SI and Ki-67 LI (P = .01, R = 0.43) and between APT SI and cell density (P < .05, R = 0.38). The gliomas with microscopic necrosis showed higher APT SI than those without necrosis (P < .001).ConclusionsAPT imaging can predict the histopathological grades of adult diffuse gliomas.
    Neuro-Oncology 12/2013; · 6.18 Impact Factor
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    ABSTRACT: PURPOSE Amide proton transfer (APT) imaging is a specific type of endogenous chemical exchange saturation transfer (CEST) imaging for detection of the amide protons included in mobile proteins and peptides. The purpose of this study was to evaluate the usefulness of APT imaging in grading diffuse gliomas by comparisons with contrast-enhanced and diffusion-weighted imaging (DWI). METHOD AND MATERIALS Consecutive 35 patients with histopathologically proven diffuse glioma (47.7±16.3 year-old, 14 males and 21 females, 6 grade II, 11 grade III and 18 grade IV) were included in the prospective study. MR imaging was conducted on a 3T clinical scanner using an 8-ch head coil for signal reception and 2-channel parallel transmission via the body coil. Saturation pulse: Tsat=2.0s, B1,rms=2.0μT. 2D turbo spin-echo sequences with driven equilibrium refocusing were used for imaging. Other parameters were as follows: TR/TR=5s/6ms, FOV=2302mm2, resolution=1.8×1.8×5mm3, 25 saturation frequency offsets ω=-6..6ppm (step 0.5ppm) and ω = -160ppm, affording 2 minutes scanning time. δB0 maps were acquired separately for a δB0 correction. APT signal intensity (SI) was defined as: MTRasym = (S[-3.5ppm]-S[+3.5ppm])/S0. Regions-of-interest were carefully placed in solid components within brain tumors. In addition, contrast enhancements (CE) in the tumors were visually graded on a 5-point scale, and minimum apparent diffusion coefficients (ADCmin) within the tumors were determined on DWI. RESULTS High-grade gliomas (HGG, grade III or IV) showed significantly stronger contrast enhancement (P<.005), lower ADC (P<.05) and higher APT SI (P<.0001) compared with low-grade gliomas (LGG, grade II). ROC analyses showed that APT imaging provided the best AUC value among these three parameters (CE: 0.88, ADC: 0.81 APT: 0.99) in discriminating HGG from LGG. Excellent sensitivity (97%) and specificity (100%) were achieved by APT imaging, while those of CE were 79% and 83%, and those of ADCmin were 79% and 83%, respectively. CONCLUSION APT imaging can provide better diagnostic performance in differentiating HGG from LGG compared with contrast-enhanced MR imaging and DWI. CLINICAL RELEVANCE/APPLICATION APT imaging can provide better diagnostic performance in discriminating HGG from LGG compared with conventional MR imaging sequences.
    Radiological Society of North America 2013 Scientific Assembly and Annual Meeting; 12/2013
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    ABSTRACT: PURPOSE Post-contrast 3D gradient-echo is the standard for brain metastases, but enhancing blood vessel can be a disturbing factor. Recent studies have shown that blood vessel suppression techniques help detect metastases more efficiently. However, incompletely suppressed vessels may closely mimic metastases, hence can result in false positive results. To solve this issue, we developed a novel 3D sequence named volume isotropic simultaneous interleaved bright- and black-blood examination (VISIBLE), which allows for simultaneous acquisitions of images with blood vessel suppression (Black images) and those without (Bright images) in 5 minutes. Our purpose was to evaluate usefulness of VISIBE through an observer study. METHOD AND MATERIALS In VISIBLE, two sequential phases of TFE acquisition are implemented following a motion-sensitized driven-equilibrium preparation for black-blood imaging. Patients with suspected brain metastasis were prospectively imaged using both VISIBLE and conventional MPRAGE. 34 patients including consecutive 17 patients with 1 to 6 metastases and 17 with no metastasis were selected and used for the observer study. 3 radiologists read VISBLE and MPRAGE of the 34 patients in the first and second reading session. In reading VISIBLE, each observer was instructed to use Black images to pick up high signal intensity areas as candidates for metastases and Bright images as a second opinion to reject false positives such as incompletely suppressed enhancing vessels. The observers’ diagnostic performance was evaluated by means of the figure-of-merit (FOM) as an index of diagnostic performance derived from the JAFROC analysis, sensitivity, false-positive per case (FP/case), and reading time. RESULTS Compared to MPRAGE, VISIBLE was associated with significantly higher sensitivity (91.7±4.2% for VISBLE vs. 70.8±11.1% for MPRAGE, P<.05), significantly higher FOM (0.94±0.02 vs. 0.82±0.05, P<.05), and significantly shorter reading time (108.4±57.8 sec vs. 149.5±74.7 sec, P<.05). FP/case was fewer with VISIBLE (0.13±0.12 vs. 0.23±0.22), although it did not reach statistical significance. CONCLUSION VISIBLE can improve radiologists’ diagnostic performance in detecting brain metastases. CLINICAL RELEVANCE/APPLICATION VISIBLE is capable of simultaneous acquisitions with and without blood vessel suppression and can improve radiologists’ diagnostic performance in detecting brain metastases.
    Radiological Society of North America 2013 Scientific Assembly and Annual Meeting; 12/2013
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    ABSTRACT: 3D turbo field echo with diffusion-sensitised driven-equilibrium preparation (DSDE-TFE) is a novel non-echo planar technique for diffusion-weighted (DW) imaging. The purpose of this study was to differentiate intraorbital lymphoma from immunoglobulin G4-related disease (IgG4-RD) using the apparent diffusion coefficient (ADC) derived from DSDE-TFE. Fifteen patients with lymphomas and 8 with IgG4-RDs underwent imaging. ADC and signal intensities compared with normal grey matter on T1-weighted images, fat-suppressed T2-weighted images and fat-suppressed postcontrast T1-weighted images were measured. Statistical analyses were performed using the Mann-Whitney U test and receiver operating characteristic (ROC) analysis. Intraorbital lesions were clearly visualised on DSDE-TFE without obvious geometrical distortion. The ADC of lymphoma (1.25 ± 0.50 × 10(-3) mm(2)/s; mean ± standard deviation) was significantly lower than that of IgG4-RD (1.67 ± 0.84 × 10(-3) mm(2)/s; P < 0.05). Conventional sequences could not separate lymphoma from IgG4-RD (0.93 ± 0.18 vs. 0.94 ± 0.21 on T1-weighted images, 0.92 ± 0.17 vs. 0.95 ± 0.14 on T2-weighted images and 2.03 ± 0.35 vs. 2.30 ± 0.58 on postcontrast T1-weighted images, for lymphoma and IgG4-RD, respectively; P > 0.05). ROC analysis showed the best diagnostic performance with ADC. The apparent diffusion coefficient derived from diffusion-sensitised driven-equilibrium preparation techniques may help to differentiate lymphoma from immunoglobulin G4-related disease. • Distinguishing between orbital lymphoma and immunoglobulin G4-related disease can be difficult • Intraorbital lesions were clearly visualised on diffusion-sensitised driven-equilibrium preparation magnetic resonance techniques. • Variations in field homogeneity do not affect DSDE-TFE techniques all that much. • ADCs derived from DSDE-TFE may help differentiate lymphoma from IgG4-RD.
    European Radiology 11/2013; · 4.34 Impact Factor
  • Clinical neuroradiology. 08/2013;
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    ABSTRACT: We are the first to report a case that showed spontaneous resolution of epidural hematoma which was related to a steroid-induced osteoporotic compression fracture. The patient had a painful fracture with an intravertebral cleft at L1 accompanying an epidural hematoma posteriorly. Immediate pain relief was achieved after percutaneous vertebroplasty. Complete resolution of hematoma was noted three months after procedure. We theorized that intravertebral stability after treatment might have played a role in this patient.
    World journal of radiology. 08/2013; 5(8):325-7.
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    ABSTRACT: BACKGROUND AND PURPOSE:3D turbo field echo with diffusion-sensitized driven-equilibrium preparation is a non-echo-planar technique for DWI, which enables high-resolution DWI without field inhomogeneity-related image distortion. The purpose of this study was to evaluate the feasibility of diffusion-sensitized driven-equilibrium turbo field echo in evaluating diffusivity in the normal pituitary gland.MATERIALS AND METHODS:First, validation of diffusion-sensitized driven-equilibrium turbo field echo was attempted by comparing it with echo-planar DWI. Five healthy volunteers were imaged by using diffusion-sensitized driven-equilibrium turbo field echo and echo-planar DWI. The imaging voxel size was 1.5 × 1.5 × 1.5 mm(3) for diffusion-sensitized driven-equilibrium turbo field echo and 1.5 × 1.9 × 3.0 mm(3) for echo-planar DWI. ADCs measured by the 2 methods in 15 regions of interests (6 in gray matter and 9 in white matter) were compared by using the Pearson correlation coefficient. The ADC in the pituitary anterior lobe was then measured in 10 volunteers by using diffusion-sensitized driven-equilibrium turbo field echo, and the results were compared with those in the pons and vermis by using a paired t test.RESULTS:The ADCs from the 2 methods showed a strong correlation (r = 0.79; P < .0001), confirming the accuracy of the ADC measurement with the diffusion-sensitized driven-equilibrium sequence. The ADCs in the normal pituitary gland were 1.37 ± 0.13 ×10(-3) mm(2)/s, which were significantly higher than those in the pons (1.01 ± 0.24 ×10(-3) mm(2)/s) and the vermis (0.89 ± 0.25 ×10(-3) mm(2)/s, P < .01).CONCLUSIONS:We demonstrated that diffusion-sensitized driven-equilibrium turbo field echo is feasible in assessing ADC in the pituitary gland.
    American Journal of Neuroradiology 07/2013; · 3.17 Impact Factor
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    ABSTRACT: OBJECTIVE: To prospectively evaluate the usefulness of a newly developed high-resolution three-dimensional diffusion-weighted imaging method, turbo field-echo with diffusion-sensitized driven-equilibrium (TFE-DSDE) in diagnosing middle-ear cholesteatoma by comparing it to conventional single-shot echo-planar diffusion-weighted imaging (SS-EP DWI). MATERIALS AND METHODS: Institutional review board approval and informed consent from all participants were obtained. We studied 30 patients with preoperatively suspected acquired cholesteatoma. Each patient underwent an MR examination including both SS-EP DWI and DSDE-TFE using a 3.0T MR scanner. Images of the 30 patients (60 temporal bones including 30 with and 30 without cholesteatoma) were reviewed by two independent neuroradiologists. The confidence level for the presence of cholesteatoma was graded on a scale of 0-2 (0=definite absence, 1=equivocal, 2=definite presence). Interobserver agreement as well as sensitivity, specificity, and accuracy for detection were assessed for the two reviewers. RESULTS: Excellent interobserver agreement was shown for TFE-DSDE (κ=0.821) whereas fair agreement was obtained for SS-EP DWI (κ=0.416). TFE-DSDE was associated with significantly higher sensitivity (83.3%) and accuracy (90.0%) compared to SS-EP DWI (sensitivity=35.0%, accuracy=66.7%; p<0.05). No significant difference was found in specificity (96.7% for TFE-DSDE, 98.3% for SS-EP DWI) CONCLUSION: With increased spatial resolution and reduced susceptibility artifacts, TFE-DSDE improves the accuracy in diagnosing acquired middle ear cholesteatomas compared to SS-EP DWI.
    European journal of radiology 05/2013; · 2.65 Impact Factor
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    ABSTRACT: PURPOSE: The aim of this study was to evaluate the usefulness of three-dimensional T1-weighted spoiled gradient-recalled echo (3D T1-GRE) images for the preoperative anatomical evaluation of lumbosacral lipoma, thick filum terminale, and myelomeningocele as a means of compensating for the drawbacks of 3D heavily T2-weighted (3D hT2-W) images. METHODS: Nine patients with lumbosacral lipomas, one patient with tight filum terminale, and five patients with myelomeningoceles were included in this study. 3D T1-GRE images were compared with 3D hT2-W images or conventional magnetic resonance images in terms of delineation of lipomas and other structures in the patients with lipomas and tight filum terminale. For patients with myelomeningoceles, 3D T1-GRE images were compared with 3D hT2-W images in terms of artifacts in the cerebrospinal fluid (CSF) space. RESULTS: The 3D T1-GRE images demonstrated lipomas with good contrast to the spinal cord and CSF space and more clearly delineated the anatomical relationship between lipomas and these structures than did the 3D hT2-W images. The 3D T1-GRE images delineated dural defects through which extradural lipomas penetrated into the intradural space. The 3D T1-GRE images also demonstrated the presence or absence of lipomas in the filum terminale and the absence of artifact in the myelomeningoceles. Furthermore, they were useful for differentiating artifacts observed on the 3D hT2-W images from nerve elements. CONCLUSIONS: The complementary use of 3D T1-GRE and 3D hT2-W images may compensate for the drawbacks of 3D hT2-W images and may eventually improve lesion visualization and surgical decision making.
    Child s Nervous System 05/2013; · 1.24 Impact Factor
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    ABSTRACT: BACKGROUND: Cognitive impairment is a frequent complication of moyamoya disease (MMD) in adults. Chronic hypoperfusion in frontal lobes can lead to subtle brain injury, resulting in cognitive dysfunctions. Apparent diffusion coefficient (ADC) in normal-appearing white matter on conventional magnetic resonance imaging correlates with cerebral hemodynamics in the frontal lobe. OBJECTIVE: The purpose of this study was to examine the relationship of ADC with executive function in patients with MMD. METHODS: Thirty-one patients (25 women and 6 men; mean age, 32.6 ± 10.4 years) were included in this study. Executive function was evaluated by the Frontal Assessment Battery (FAB) at 21.5 ± 7.5 years after disease onset. ADC was measured in the normal-appearing frontal white matter. RESULTS: ADC was statistically related to the occurrence of executive dysfunction in multivariate analysis (P = .0179). Total FAB score and ADC were negatively correlated (r(2) = .22; P = .0072; Spearman correlation coefficient, -.41; P = .024). Elevated ADC predicted executive dysfunction (area under the receiver operating characteristic curve, .73; 95% confidence interval, .55-.91; P = .029). CONCLUSIONS: The association of ADC with executive function might suggest that ADC is useful in screening for executive dysfunction during follow-up in the outpatient setting.
    Journal of stroke and cerebrovascular diseases: the official journal of National Stroke Association 04/2013;
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    ABSTRACT: PURPOSE Post-contrast 3D T1-weighted images are widely used to detect brain metastases. In those images, signals from enhancing blood vessels can simulate metastases. Suppression of blood vessels would help detect metastases more efficiently. Our purpose was to develop and evaluate a new MR sequence named volume isotropic simultaneous interleaved bright- and black-blood examination (VISIBLE), which allows for simultaneous acquisitions with and without blood vessel suppression. METHOD AND MATERIALS In VISIBLE, two sequential phases of turbo filed-echo acquisition were implemented following a motion-sensitized driven-equilibrium preparation for black-blood imaging. The first and second acquisition phases were for imaging with blood vessel suppression (Black image) and imaging without it (Bright image), respectively. Post-contrast images of patients with suspected brain metastases were obtained on a 3T scanner using both conventional 3D MPRAGE and VISIBLE. The number of visualized blood vessels counted in a single centrum semioval section was compared among 3 types of images (MPRAGE, Black and Bright) in 20 patients with no enhancing lesions. Moreover, the lesion-to-normal contrast-to-noise ratios (CNRs) were compared in 20 metastatic lesions. Statistical comparisons were performed using 2-way ANOVA and least square means Student t test. RESULTS With VISIBLE, Bright and Black images could be obtained simultaneously with a similar imaging time (308s) to MPRAGE (320s). Strong blood vessel suppression was achieved in Black images: the numbers of vessels (mean±SD) were 35.4±9.2 for MPRAGE, 29.5±8.3 for Bright image, and 1.4±1.1 for Black image (P<.05 for all comparisons). The lesion-to-normal CNR was significantly greater with Black (14.3±5.6) and Bright (13.7±5.8) images than with MPRAGE (8.0±3.4) (P<.05). CONCLUSION With strong blood vessel suppression and greater CNR, Black images of VISIBLE should allow for easier detection of metastases than MPRAGE. Bright images may be useful to recognize relationships between lesions and blood vessels and to avoid false detection of lesions created by partially suppressed blood vessels. VISIBLE may improve radiologists’ diagnostic performance in detecting brain metastases. CLINICAL RELEVANCE/APPLICATION VISIBLE is capable of simultaneous acquisitions with and without blood vessel suppression, and should improve radiologists’ diagnostic performance in detecting brain metastases.
    Radiological Society of North America 2012 Scientific Assembly and Annual Meeting; 11/2012
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    ABSTRACT: PURPOSE Amide proton transfer (APT) imaging is a specific type of chemical exchange saturation (CEST) imaging for detecting amide protons (-NH) in endogenous mobile proteins and peptides. The length of RF saturation (Tsat) is a key parameter for sensitivity of the APT contrast. Fast spin-echo based APT imaging has been previously restricted to Tsat<1.0s because of typical RF amplifier hardware constraints in clinical MRI systems. The purpose of this study was to demonstrate the efficacy of long Tsat enabled by a parallel transmission based technique for APT imaging of gliomas. METHOD AND MATERIALS Ten patients with diffuse glioma (2 oligodendrogliomas 2 anaplastic oligodendrogliomas and 4 GBMs) who underwent surgical resection were included in the prospective study. MR imaging was conducted on a 3T clinical scanner (Achieva TX, Philips Healthcare, NL) using an 8-ch head coil and 2-ch parallel transmission via the body coil. Saturation pulse: 50ms sinc-gauss-shaped elements, Tsat=0.5s, 1.0s, 2.0s, B1=2.0μT. 2D fast spin-echo sequences with driven equilibrium refocusing were used for imaging. Other parameters were as follows: TR/TR=5s/6ms, FOV=2302mm, resolution=1.8×1.8×5mm, 25 saturation frequency offsets, ω=-6..6ppm (step 0.5ppm) and ω0 = -160ppm, affording 2 minutes scanning time. δB0 maps were separately acquired for a point-by-point δB0 correction. Regions-of-interest were carefully placed in solid components of tumors as well as in normal white matter. The following 2 parameters were obtained at the three Tsat lengths: 1) MTRasym [3.5ppm] = (S[-3.5ppm]-S[+3.5ppm])/S0, 2) δMTRasym [3.5ppm] = difference in MTRasym [3.5ppm] between tumors and normal white matter. RESULTS The contrast changes with longer pulses are statistically significant (P<0.05). In high-grade gliomas, mean MTRasym [3.5ppm] was 3.3±0.6%, 4.0±0.8%, 4.4±1.5% and mean δMTRasym [3.5ppm] was 1.9±0.6%, 3.0±0.7%, 4.1±1.5% at Tsat of 0.5s, 1s, 2s, respectively. In low-grade gliomas, mean MTRasym [3.5ppm] was 2.2±1.2%, 1.9±1.7%, 1.5±2.4%, and mean δMTRasym [3.5ppm] was 0.3±0.7%, 0.6±0.2%, 1.2±0.2% at Tsat of 0.5s, 1s, 2s, respectively. CONCLUSION APT contrasts in gliomas were enhanced with the long Tsat enabled by the parallel transmission based technique. CLINICAL RELEVANCE/APPLICATION The method can provide accurate quantitative measures for diffuse gliomas, which should be useful for surgical planning or monitoring therapeutic response after chemotherapy or radiation therapy.
    Radiological Society of North America 2012 Scientific Assembly and Annual Meeting; 11/2012
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    ABSTRACT: PURPOSE Previous animal experiments have shown that amide proton transfer (APT) imaging can detect changes in pH during acute ischemia. However, there is no report on a systematic study of ATP imaging in human stroke patients. Our purpose was to examine the feasibility of APT imaging for acute cerebral infarction with a clinical 3T MR scanner. METHOD AND MATERIALS This study enrolled 7 patients with acute infarction (3 males and 4 females; median age=75 years; 5 cardioembolic and 2 thrombotic). All patients were examined using a clinical 3T MR scanner (Achieva TX, Philips Healthcare, NL). The time after onset was within 24 hours in 3 patients, 24 to 48 hours in 2 patients, and 48 hours to 4 days in 2 patients. APT imaging was performed at a single imaging plain using a TSE sequence with driven equilibrium: TR/TE=5000/6 ms; FOV=230 mm; matrix=128x128; slice thickness=5 mm. The strength and duration of the saturation pulse were set at 2μT and 500 ms (10x50ms block-shaped elements), respectively. To obtain the Z-spectra, the saturation pulse was applied at 25 offset frequencies ranging from -6 to 6 ppm with respect to the water resonance frequency. Correction for B0 inhomogeneity was performed in the post-processing using a separate B0 map and Lagrange interpolation among the offset frequencies. Mapping of APT effect was performed by calculating the asymmetry in magnetization transfer ratio (MTRasym) between ±3.5 ppm divided by a reference obtained at -160 ppm. Infarcted regions were determined using simultaneously obtained diffusion-weighted images. MTRasym was compared between normal and infracted areas using paired t-test. The difference in MTRasym between normal and infracted regions (ΔMTRasym) was also reported. RESULTS MTRasym in infracted areas ranged from 0.5 to 1.8 % (mean±SD=1.1±0.5 %), and was significantly lower than that in normal brain parenchyma (1.3-2.9 %, mean±SD=2.1±0.6 %) (P<0.05). ΔMTRasym ranged from 0 to 2.3% (mean±SD=1.0±0.8 %). CONCLUSION Decreased MTRasym in acute infarction was consistent with the results of previous animal experiments. Our study demonstrated the feasibility of APT imaging at a clinical 3T MR scanner, suggesting the possibility of pH-weighted imaging for acute ischemia in patients. CLINICAL RELEVANCE/APPLICATION Amide proton transfer (APT) imaging is sensitive to pH abnormality in acute cerebral infarction, hence may be useful for accurate delineation of ischemic damage.
    Radiological Society of North America 2012 Scientific Assembly and Annual Meeting; 11/2012

Publication Stats

872 Citations
167.62 Total Impact Points

Institutions

  • 2007–2014
    • Kyushu University
      • • Department of Clinical Radiology
      • • Department of Neurosurgery
      Hukuoka, Fukuoka, Japan
  • 2011
    • Saga University
      • Division of Radiology
      Сага Япония, Saga, Japan
  • 2002–2007
    • University Center Rochester
      • • Department of Imaging Sciences
      • • Department of Radiology
      • • Department of Diagnostic Radiology
      Rochester, Minnesota, United States
  • 2006
    • University of Rochester
      • Department of Imaging Sciences
      Rochester, New York, United States