Hiroki Haradome

Efficacy of distortion correction on diffusion imaging: comparison of FSL eddy and eddy_correct using 30 and 60 directions diffusion encoding.

Diffusion imaging is a unique noninvasive tool to detect brain white matter trajectory and integrity in vivo. However, this technique suffers from spatial distortion and signal pileup or dropout originating from local susceptibility gradients and eddy currents. Although there are several methods to mitigate these problems, most techniques can be applicable either to susceptibility or eddy-current induced distortion alone with a few exceptions. The present study compared the correction efficiency of FSL tools, “eddy_correct” and the combination of “eddy” and “topup” in terms of diffusion-derived fractional anisotropy (FA). The brain diffusion images were acquired from 10 healthy subjects using 30 and 60 directions encoding schemes based on the electrostatic repulsive forces. For the 30 directions encoding, 2 sets of diffusion images were acquired with the same parameters, except for the phase-encode blips which had opposing polarities along the anteroposterior direction. For the 60 directions encoding, non–diffusion-weighted and diffusion-weighted images were obtained with forward phase-encoding blips and non–diffusion-weighted images with the same parameter, except for the phase-encode blips, which had opposing polarities. FA images without and with distortion correction were compared in a voxel-wise manner with tract-based spatial statistics. We showed that images corrected with eddy and topup possessed higher FA values than images uncorrected and corrected with eddy_correct with trilinear (FSL default setting) or spline interpolation in most white matter skeletons, using both encoding schemes. Furthermore, the 60 directions encoding scheme was superior as measured by increased FA values to the 30 directions encoding scheme, despite comparable acquisition time. This study supports the combination of eddy and topup as a superior correction tool in diffusion imaging rather than the eddy_correct tool, especially with trilinear interpolation, using 60 directions encoding scheme.

Predicting postoperative outcomes of liver resection by magnetic resonance elastography

Background. Cirrhosis is associated with blood loss during liver resection and postoperative complications. The liver stiffness measurement has recently become available for assessment of liver fibrosis. Methods. This prospective study was performed to predict postoperative outcomes of liver resection. The liver stiffness measurement was measured prospectively using magnetic resonance elastography for patients who had undergone liver resection for malignancy. We investigated whether the liver stiffness measurement by magnetic resonance elastography is correlated with liver fibrosis and postoperative outcomes. Results. The median liver stiffness measurement by magnetic resonance elastography in 175 patients was 3.4 (range: 1.5–11.3) kPa, and the pathologic grade of liver fibrosis was significantly correlated with the liver stiffness measurement (r = 0.68, P < .001). The median blood loss during transection per unit area was 4.1 mL/cm2 (range: 0.1–37.0 mL/cm2), and the frequency of major complications was 16.0%. The liver stiffness measurement was the only independent prognostic factor for both blood loss (regression coefficient: 1.14, 95% confidence interval: 0.45–1.83, P = .001) and major complications (odds ratio: 2.14, 95% confidence interval: 1.63–2.93, P < .001). Receiver operating characteristic curve analysis indicated a significant correlation between the liver stiffness measurement and major complications with calculated area under the curve of 0.81 (P < .001), and the sensitivity and specificity for prediction of major complications (cutoff value: 5.3 kPa) were 64.3% and 87.8%, respectively. On the other hand, the amount of blood loss was significantly correlated with the frequency of major complications (P = .003). Conclusion. The liver stiffness measurement by magnetic resonance elastography could be used as a predictive marker for the risk of major complications due to blood loss during liver resection.

Altered structural connectivity of pain-related brain network in burning mouth syndrome—investigation by graph analysis of probabilistic tractography

PurposeBurning mouth syndrome (BMS) is a chronic intraoral pain syndrome featuring idiopathic oral pain and burning discomfort despite clinically normal oral mucosa. The etiology of chronic pain syndrome is unclear, but preliminary neuroimaging research has suggested the alteration of volume, metabolism, blood flow, and diffusion at multiple brain regions. According to the neuromatrix theory of Melzack, pain sense is generated in the brain by the network of multiple pain-related brain regions. Therefore, the alteration of pain-related network is also assumed as an etiology of chronic pain. In this study, we investigated the brain network of BMS brain by using probabilistic tractography and graph analysis.MethodsFourteen BMS patients and 14 age-matched healthy controls underwent 1.5T MRI. Structural connectivity was calculated in 83 anatomically defined regions with probabilistic tractography of 60-axis diffusion tensor imaging and 3D T1-weighted imaging. Graph theory network analysis was used to evaluate the brain network at local and global connectivity.ResultsIn BMS brain, a significant difference of local brain connectivity was recognized at the bilateral rostral anterior cingulate cortex, right medial orbitofrontal cortex, and left pars orbitalis which belong to the medial pain system; however, no significant difference was recognized at the lateral system including the somatic sensory cortex. A strengthened connection of the anterior cingulate cortex and medial prefrontal cortex with the basal ganglia, thalamus, and brain stem was revealed.ConclusionStructural brain network analysis revealed the alteration of the medial system of the pain-related brain network in chronic pain syndrome.

Gadoxetic acid disodium-enhanced MR imaging of cholangiolocellular carcinoma of the liver: imaging characteristics and histopathological correlations

ObjectivesTo review the gadoxetic acid disodium (EOB)-enhanced magnetic resonance (MR) imaging features of cholangiolocellular carcinoma (CoCC) of the liver and compare them with those of hepatocellular carcinoma (HCC) and intrahepatic cholangiocarcinoma (ICC).MethodsEOB-enhanced MR images of 19 patients with CoCC, 23 with ICC, and 51 with HCC were retrospectively evaluated qualitatively and quantitatively. Univariate and multivariate analyses were performed to determine the characteristic MR features of CoCC with histopathological–imaging correlation.ResultsMultivariate logistic regression analysis showed that dot-/band-shaped internal enhancement during the arterial and portal phases (P < 0.001), and larger arterial ring enhancement ratio (CoCC, 0.13 ± 0.04; ICC, 0.074 ± 0.04; P = 0.013) were significantly independently associated with CoCC in contrast to ICC, whereas several MR features including progressive enhancement during the portal and late phases (P < 0.001), target appearance in the hepatocyte phase (P = 0.004), and vessel penetration (P = 0.013) were significantly more frequently associated with CoCC than HCC. The dot-/band-like internal enhancement (78.9% of CoCCs) histopathologically corresponded to the tumour cell nest with vascular proliferations and retained Glissons sheath structure.ConclusionsEOB-enhanced MR features of CoCC largely differ from those of HCC but are similar to those of ICC. However, the finding of thicker arterial ring enhancement with dot-/band-like internal enhancement could help differentiate CoCC from ICC.Key Points• Gadoxetic acid-enhanced MR features of cholangiolocellular carcinoma (CoCC) resembled those of intrahepatic cholangiocarcinoma (ICC).• Gadoxetic acid-enhanced MR features of CoCC largely differed from those of hepatocellular carcinoma.• Dot-/band-like internal enhancement of CoCC may be helpful for differentiating from ICC.• Arterial ring enhancement of CoCC was larger than that of ICC.

A case of kaposiform hemangioendothelioma at the sigmoid colon

We report a case of kaposiform hemangioendothelioma (KHE) occurring at the sigmoid colon in an 8-year-old male. He had experienced lower abdominal pain and fever for several days. Contrast-enhanced CT images revealed a well-enhanced mass involving several large and small cystic parts with thin, enhanced walls at the sigmoid colon. The diagnosis was made histopathologically after surgical resection; the cystic parts corresponded to dilated lymphatic vessels. KHE is a rare, locally aggressive, vascular tumor that usually occurs in the soft tissues of the extremities. However, a case occurring in the bowel is extremely rare, and usually appears as bowel wall thickening. This is a unique case of KHE appearing as a mass-shaped hypervascular lesion in the bowel. Dilated lymphatic vessels in KHE may appear as a cystic part of the lesion.

Cost-effectiveness of EOB-MRI for Hepatocellular Carcinoma in Japan

PURPOSE The objective of the study was to evaluate the cost-effectiveness of gadoxetic acid-enhanced magnetic resonance imaging (EOB-MRI) in the diagnosis and treatment of hepatocellular carcinoma (HCC) in Japan compared with extracellular contrast media-enhanced MRI (ECCM-MRI) and contrast media-enhanced computed tomography (CE-CT) scanning. METHODS A 6-stage Markov model was developed to estimate lifetime direct costs and clinical outcomes associated with EOB-MRI. Diagnostic sensitivity and specificity, along with clinical data on HCC survival, recurrence, treatment patterns, costs, and health state utility values, were derived from predominantly Japanese publications. Parameters unavailable from publications were estimated in a Delphi panel of Japanese clinical experts who also confirmed the structure and overall approach of the model. Sensitivity analyses, including one-way, probabilistic, and scenario analyses, were conducted to account for uncertainty in the results. FINDINGS Over a lifetime horizon, EOB-MRI was associated with lower direct costs (¥2,174,869) and generated a greater number of quality-adjusted life years (QALYs) (9.502) than either ECCM-MRI (¥2,365,421, 9.303 QALYs) or CE-CT (¥2,482,608, 9.215 QALYs). EOB-MRI was superior to the other diagnostic strategies considered, and this finding was robust over sensitivity and scenario analyses. A majority of the direct costs associated with HCC in Japan were found to be costs of treatment. The model results revealed the superior cost-effectiveness of the EOB-MRI diagnostic strategy compared with ECCM-MRI and CE-CT. IMPLICATIONS EOB-MRI could be the first-choice imaging modality for medical care of HCC among patients with hepatitis or liver cirrhosis in Japan. Widespread implementation of EOB-MRI could reduce health care expenditures, particularly downstream treatment costs, associated with HCC.

Characteristics of Hepatic Schwannoma Presenting as an Unusual Multi-cystic Mass on Gadoxetic Acid Disodium-enhanced MR Imaging

Hepatic schwannoma is a very rare hepatic tumor, usually appearing as a hypervascular solid mass with or without various degrees of cystic changes; however, to the best of our knowledge, only the two cases of hepatic schwannoma showing a multi-cystic appearance have previously been reported. We report herein a benign hepatic schwannoma presenting as an unusually large multi-cystic mass. The gadoxetic acid disodium-enhanced magnetic resonance imaging features are described with the histopathologic correlation and briefly review the literature. The solid-like areas showing the early/progressive enhancement, reflecting remnants of the Antoni A/B portion, during the dynamic phases may be helpful imaging features for the differentiation of other multi-cystic hepatic lesions, but pathological evaluation remains essential for diagnosis.