Taro Takahara

Magnetic Resonance Imaging Technique for Visualization of Irregular Cerebrospinal Fluid Motion in the Ventricular System and Subarachnoid Space

BACKGROUNDnMany studies have shown that cerebrospinal fluid (CSF) behaves irregularly, rather than with laminar flow, in the various CSF spaces. We adapted a modified previously known magnetic resonance imaging technique to visualize irregular CSF motion. Subsequently, we assessed the usefulness and clinical significance of the present method.nnnMATERIALS AND METHODSnNormal CSF motion in 10 healthy volunteers was visualized with the dynamic improved, motion-sensitized, driven-equilibrium steady-state free precession technique. Subsequently, CSF motion visualization with a modified sequence was applied to 3 patients.nnnRESULTSnIn healthy volunteers, we achieved visualization of the irregularity of CSF flow in the ventricles and spinal canal, whereas CSF motion was diminished in the peripheral part of the intracranial subarachnoid space. In one case, we confirmed the patency of the patients third ventriculostomy fenestration site. In the other, we verified the usefulness of the proposed sequence for determining the communication between the ventricle or subarachnoid space and the cyst.nnnCONCLUSIONSnUsing the present sequence, we obtained images that accentuated CSF motion, which is largely composed of irregular motion. This method does not require pulse triggering or complex post-processing of images and allows visualization of CSF motion in a short period of time in selected whole imaging planes. It can therefore be applied clinically to diagnose various diseases that cause abnormalities in the CSF space.

Utility of computed diffusion-weighted MRI for predicting aggressiveness of prostate cancer

To investigate the value of computed (c) diffusion‐weighted imaging (DWI) in assessing prostate cancer aggressiveness.

DWI as an Imaging Biomarker for Bladder Cancer

OBJECTIVEnDWI has been increasingly applied in the management of bladder cancer. In this article, we discuss the role of DWI as an imaging biomarker for bladder cancer.nnnCONCLUSIONnThe DWI signal is derived from the motion of water molecules, which represents the physiologic characteristics of the tissue of interest. The emerging evidence highlights the utility of DWI for bladder cancer detection and characterization. DWI is a potentially useful tool to individualize treatment strategies.

Optimization and clinical feasibility of free-breathing diffusion-weighted imaging of the liver: Comparison with respiratory-triggered diffusion-weighted imaging

PURPOSEnWe compared the image quality of free-breathing diffusion-weighted imaging (FB-DWI) to that of respiratory-triggered DWI (RT-DWI) after proper optimization.nnnMATERIALS AND METHODSnThree healthy subjects were scanned to optimize magnetic resonance (MR) parameters of FB-DWI to improve image quality, including spatial resolution, image noise, and chemical shift artifacts. After this optimization, we scanned 32 patients with liver disease to assess the clinical feasibility of the optimized FB-DWI. Of the 32 patients, 14 had a total of 28 hepatocellular carcinomas (HCCs), four had a total of 15 metastatic liver tumors, and the other 14 had no tumor. Qualitatively, we compared the image quality scores of FB-DWI with those of RT-DWI with the Wilcoxon signed-rank test. Quantitatively, we compared the signal-to-noise ratios (SNRs) of the liver parenchyma, lesion-to-nonlesion contrast-to-noise ratios (CNRs) and apparent diffusion coefficient (ADC) values of the liver parenchyma and liver tumor by the paired t-test.nnnRESULTSnThe average scores of image quality for sharpness of liver contour, image noise, and chemical shift artifacts were significantly higher for FB-DWI than RT-DWI (P < 0.05). SNRs, CNRs, and ADC values of the liver parenchyma and tumors did not differ significantly between the 2 DWI methods.nnnCONCLUSIONnCompared with RT-DWI, the optimized FB-DWI provided better spatial resolution, fewer artifacts, and comparable SNRs, lesion-to-nonlesion CNRs, and ADC values.

Assessment of colonic contents in patients with chronic constipation using MRI

Although chronic constipation is common, colonic functional evaluating tests are uncommon. This study examines whether chronic constipation and gastrointestinal symptoms are correlated with the lateral diameter of the colon measured from MRI images. We included chronic constipation patients in a prospective, cross-sectional study using MRI at three centers. We divided 3D MRI colorectal images into 6 segments using with specified sequences and selected the maximum luminal diameter from each segment. We used the GSRS questionnaire to evaluate gastrointestinal symptoms. We evaluated the correlation between luminal diameters and GSRS scores. We found the following positive correlations: descending colon and unsatisfactory defecation symptoms; sigmoid colon and diarrhea; and rectum and constipation. The sum and ratio of the ascending and sigmoid colon diameters correlated with nausea and diarrhea. The sum of the transvers to the sigmoid colon diameter also correlated with nausea and diarrhea. The sum of all segment diameters correlated with nausea and constipation. In conclusion, we showed cross-sectional study of colonic MRI correlate with gastrointestinal symptoms. MRI might be useful for colonic motility evaluations to determine appropriate constipation treatments (Clinical trial registry number UMIN 000021274).

Foreign-body granuloma mimicking post-chemotherapy residual seminoma: A case of true-negative findings using diffusion-weighted whole-body magnetic resonance imaging with background suppression

Diffusion-weighted whole-body magnetic resonance imaging with background suppression (DWIBS) is increasingly used in cancer imaging. However, little is known about its usefulness in the management of metastatic seminoma, in which evaluation of the viability of postchemotherapy residual nodules is pivotal. To date, 2–18fluoro-deoxy-d-glucose positron emission tomography (FDG-PET) has been recommended for post-chemotherapeutic assessment. We describe a case of metastatic seminoma in a 27-year-old man in which the viability of post-chemotherapy residual nodules tested false-positive on FDG-PET, but true-negative on DWIBS. DWIBS may be a good alternative technique to evaluate post-chemotherapy seminoma, although further studies are required to determine its usefulness.

Repeatability analysis of ADC histogram metrics of the uterus

Background Recently, histogram analysis based on voxel-wise apparent diffusion coefficient (ADC) value distribution has been increasingly performed. However, few studies have been reported regarding its repeatability. Purpose To evaluate the repeatability of ADC histogram metrics of the uterus in clinical magnetic resonance imaging (MRI). Material and Methods Thirty-three female patients who underwent pelvic MRI including diffusion-weighted imaging (DWI) were prospectively included after providing informed consent. Two sequential DWI acquisitions with identical parameters and position were obtained. Regions of interest (ROIs) for histologically confirmed uterine lesions (five cervical and three endometrial cancers, and one endometrial hyperplasia) and normal appearing tissues (21 endometrium and 33 myometrium) were assigned on the first DWI dataset and then pasted onto the second DWI dataset. ADC histogram metrics within the ROIs were calculated and repeatability was evaluated by calculating within-subject coefficient of variance (%) (wCV (%)) and Bland–Altman plot (%). Results ADC 10%, 25%, median, 75%, 90%, maximum, mean, and entropy showed high repeatability (wCV (%)u2009<u20097, 95% limit of agreement in Bland–Altman plot (%)u2009<u2009±20), followed by ADC minimum (wCV (%) = 8.12, 95% limit of agreement in Bland–Altman plot (%)u2009<u2009±30). However, ADC skewness and kurtosis showed very low repeatability in all evaluations. Conclusion ADC histogram metrics like ADC 10%, 25%, median, 75%, 90%, maximum, mean, and entropy are robust biomarkers and could be applicable to clinical use. However, ADC skewness and kurtosis lack robustness. Radiologists should keep these characteristics and limitations in mind when interpreting quantitative DWI.

Volume Isotropic Simultaneous Interleaved Black- and Bright-blood Imaging: A Novel Sequence for Contrast-enhanced Screening of Brain Metastasis

We introduced and optimized a novel sequence of fast (about 4 min), volumetric, high resolution, simultaneous bright- and black-blood imaging with sufficient T1 contrast between enhanced metastasis and surrounding brain parenchyma for their differentiation. This proposed sequence can be used for 3-dimensional volumetric T1-weighted bright- and black-blood imaging in contrast-enhanced studies and may be promising for detecting small brain metastases by improving differentiation between blood vessels and small brain metastases.

Spinal Teratoid/Rhabdoid Tumor: Use of Diffusion – Weighted Imaging for Diagnosis

Spinal atypical teratoid/rhabdoid tumor (AT/RT) is a rare, aggressive malignant central nervous system neoplasm usually seen in young children and infants. Conventional magnetic resonance imaging (MRI) findings vary in spinal AT/RT. Diffusion-weighted imaging (DWI) with apparent diffusion coefficient (ADC) measurements may aid in the assessment of intratumoral characteristics. In spinal AT/RT, high signal on DWI and low ADC can correspond to a high cellularity, indicating a highly malignant tumor.