Kazufumi Kikuchi

Amide proton transfer imaging of adult diffuse gliomas: correlation with histopathological grades.

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. RESULTS The 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). CONCLUSIONS APT imaging can predict the histopathological grades of adult diffuse gliomas.

Differentiation of high-grade and low-grade diffuse gliomas by intravoxel incoherent motion MR imaging

BACKGROUND Our aim was to assess the diagnostic performance of intravoxel incoherent motion (IVIM) MR imaging for differentiating high-grade gliomas (HGGs) from low-grade gliomas (LGGs). METHODS Forty-five patients with diffuse glioma (age 50.9 ± 20.4 y; 26 males, 19 females) were assessed with IVIM imaging using 13 b-values (0-1000 s/mm(2)) at 3T. The perfusion fraction (f), true diffusion coefficient (D), and pseudo-diffusion coefficient (D*) were calculated by fitting the bi-exponential model. The apparent diffusion coefficient (ADC) was obtained with 2 b-values (0 and 1000 s/mm(2)). Relative cerebral blood volume was measured by the dynamic susceptibility contrast method. Two observers independently measured D, ADC, D*, and f, and these measurements were compared between the LGG group (n = 16) and the HGG group (n = 29). RESULTS Both D (1.26 ± 0.37 mm(2)/s in LGG, 0.94 ± 0.19 mm(2)/s in HGG; P < .001) and ADC (1.28 ± 0.35 mm(2)/s in LGG, 1.03 ± 0.19 mm(2)/s in HGG; P < .01) were lower in the HGG group. D was lower than ADC in the LGG (P < .05) and HGG groups (P < .0001). D* was not different between the groups. The f-values were significantly larger in HGG (17.5 ± 6.3%) than in LGG (5.8 ± 3.8%; P < .0001) and correlated with relative cerebral blood volume (r = 0.85; P < .0001). Receiver operating characteristic analyses showed areas under curve of 0.95 with f, 0.78 with D, 0.73 with ADC, and 0.60 with D*. CONCLUSION IVIM imaging is useful in differentiating HGGs from LGGs.

MR Imaging-Based Analysis of Glioblastoma Multiforme: Estimation of IDH1 Mutation Status

BACKGROUND AND PURPOSE: Glioblastoma multiforme is highly aggressive and the most common type of primary malignant brain tumor in adults. Imaging biomarkers may provide prognostic information for patients with this condition. Patients with glioma with isocitrate dehydrogenase 1 (IDH1) mutations have a better clinical outcome than those without such mutations. Our purpose was to investigate whether the IDH1 mutation status in glioblastoma multiforme can be predicted by using MR imaging. MATERIALS AND METHODS: We retrospectively studied 55 patients with glioblastoma multiforme with wild type IDH1 and 11 patients with mutant IDH1. Absolute tumor blood flow and relative tumor blood flow within the enhancing portion of each tumor were measured by using arterial spin-labeling data. In addition, the maximum necrosis area, the percentage of cross-sectional necrosis area inside the enhancing lesions, and the minimum and mean apparent diffusion coefficients were obtained from contrast-enhanced T1-weighted images and diffusion-weighted imaging data. Each of the 6 parameters was compared between patients with wild type IDH1 and mutant IDH1 by using the Mann-Whitney U test. The performance in discriminating between the 2 entities was evaluated by using receiver operating characteristic analysis. RESULTS: Absolute tumor blood flow, relative tumor blood flow, necrosis area, and percentage of cross-sectional necrosis area inside the enhancing lesion were significantly higher in patients with wild type IDH1 than in those with mutant IDH1 (P < .05 each). In contrast, no significant difference was found in the ADCminimum and ADCmean. The area under the curve for absolute tumor blood flow, relative tumor blood flow, percentage of cross-sectional necrosis area inside the enhancing lesion, and necrosis area were 0.850, 0.873, 0.739, and 0.772, respectively. CONCLUSIONS: Tumor blood flow and necrosis area calculated from MR imaging are useful for predicting the IDH1 mutation status.

High-resolution three-dimensional diffusion-weighted imaging of middle ear cholesteatoma at 3.0 T MRI: Usefulness of 3D turbo field-echo with diffusion-sensitized driven-equilibrium preparation (TFE–DSDE) compared to single-shot echo-planar imaging

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 3.0 T 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.

Scan-rescan reproducibility of parallel transmission based amide proton transfer imaging of brain tumors

To evaluate the reproducibility of amide proton transfer (APT) imaging of brain tumors using a parallel transmission‐based technique.

Evaluation of Diffusivity in the Anterior Lobe of the Pituitary Gland: 3D Turbo Field Echo with Diffusion-Sensitized Driven-Equilibrium Preparation

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 mm3 for diffusion-sensitized driven-equilibrium turbo field echo and 1.5 × 1.9 × 3.0 mm3 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 mm2/s, which were significantly higher than those in the pons (1.01 ± 0.24 × 10−3 mm2/s) and the vermis (0.89 ± 0.25 × 10−3 mm2/s, P < .01). CONCLUSIONS: We demonstrated that diffusion-sensitized driven-equilibrium turbo field echo is feasible in assessing ADC in the pituitary gland.

Unusual presentation of an esophageal foreign body granuloma caused by a fish bone: usefulness of multidetector computed tomography

A 68-year-old woman had throat pain while eating fish. The pain gradually disappeared with no treatment. She visited her doctor for a medical checkup 1 year later, and an esophageal tumor was suspected. A double-contrast esophagogram revealed luminal stenosis with a mass-like defect in the middle esophagus. Esophagogastroduodenoscopy (EGD) showed smooth-surface stenosis with a retracted fold. Endoscopic ultrasonography (EUS) showed a hypoechoic mass in the submucosal layer and a well-defined linear hyperechoic structure forming a posterior acoustic shadow within the mass. A computed tomography (CT) examination was then performed using an Aquilion 64-detector row CT scanner, and a high attenuation linear structure was found in the lesion that was visualized as a fish bone-like structure on reconstructed CT images. Endoscopic removal of the fish bone was impossible, and a surgical operation would have been too invasive for a lesion suspected of being benign. The patient had no complaint related to the esophageal lesion itself and no sign of gastrointestinal tract complications. Accordingly, regular follow-up was recommended for the esophageal lesion. Follow-up examination including EGD, esophagography, and CT performed 1 year later showed that the lesion had decreased in size with no fish bone-like structure.

Diagnostic utility of intravoxel incoherent motion mr imaging in differentiating primary central nervous system lymphoma from glioblastoma multiforme

To evaluate the diagnostic performance of intravoxel incoherent motion (IVIM) MR imaging and 18F‐fluorodeoxyglucose positron emission tomography (FDG‐PET) in differentiating primary central nervous system lymphoma (PCNSL) from glioblastoma multiforme (GBM).

Balloon test occlusion of internal carotid artery: Angiographic findings predictive of results

AIM To reveal angiographic findings to predict the result of balloon test occlusion (BTO). METHODS The cerebral angiograms of 42 consecutive patients who underwent cerebral angiography including both the Matas and Allcock maneuvers and BTO were retrospectively analyzed. Visualization of the anterior cerebral artery (ACA) and the middle cerebral artery (MCA) by the cross flow on the tested side during the Matas or Allcock maneuver was graded on a 5-point scale. Circle of Willis (COW) anatomy with respect to the presence/absence of a collateral path to reach the tested internal carotid artery (ICA) was classified into four categories. A univariate logistic analysis was used to analyze the associations between each angiographic finding and the BTO result. Sensitivity, specificity, accuracy, positive predictive value, and negative predictive value for each finding were calculated. RESULTS Five patients (12%) were BTO-positive and the remaining 37 patients (88%) were BTO-negative. Visualizations of the ACA and MCA as well as the COW anatomy were significantly associated with the BTO result (P = 0.0051 for ACA, P = 0.0002 for MCA, and P < 0.0001 for COW anatomy). In particular, good MCA visualization and the presence of an anterior connection (collateral path to the tested ICA from the contralateral ICA via the anterior communicating artery) in the COW were highly predictive for negative BTO (negative predictive value = 100% for both). CONCLUSION A BTO result may be predicted by angiographic findings including ACA/MCA visualization and COW anatomy.

Amide proton transfer imaging of brain tumors using a self‐corrected 3D fast spin‐echo dixon method: Comparison With separate B0 correction

To assess the quantitative performance of three‐dimensional (3D) fast spin‐echo (FSE) Dixon amide proton transfer (APT) imaging of brain tumors compared with B0 correction with separate mapping methods.