Kuni Ohtomo

MRI assessment of lung parenchymal motion in normal mice and transgenic mice with sickle cell disease

To test the feasibility of a method to quantify regional pulmonary parenchymal motion via nonrigid registration algorithm at small animal scales.

Impact of hepatocellular carcinoma heterogeneity on computed tomography as a prognostic indicator

We assessed the relationship between the heterogeneity of HCC on preoperative non-contrast-enhanced CT and patient prognosis. The heterogeneity of CT images from 122 patients was assessed and texture feature parameters such as mean, standard deviation (SD), entropy, mean of the positive pixels (MPP), skewness, and kurtosis were obtained using filtration. The relationship between CT texture features and 5-year overall survival (OS) or disease-free survival (DFS) was assessed. Multivariate regression analysis was performed to evaluate the independence of texture feature from clinical or pathological parameters. The Kaplan-Meier curves for OS or DFS was significantly different between patient groups dichotomized by cut-off values for all CT texture parameters with filtration at at least one filter level. Multivariate regression analysis showed the independence of most CT texture parameters on clinical and pathological parameters for OS with filtration at at least one filter level and without filtration except kurtosis. SD, entropy, and MPP with coarse filter, and skewness without filtration showed a significant correlation for DFS. CT texture features of non-contrast-enhanced CT images showed a relationship with HCC prognosis. Multivariate regression analysis showed the possibility of CT texture feature increase the prognostic prediction of HCC by clinical and pathological information.

PEG-poly(L-lysine)-based polymeric micelle MRI contrast agent: Feasibility study of a Gd-micelle contrast agent for MR lymphography: MR Lymphography by Gd-Micelle MRI Agent

To investigate the feasibility of polymeric micelle of poly(ethyleneglycol) (PEG)‐b‐poly(L‐lysine‐DOTA) (Gd‐micelle) as a contrast agent for magnetic resonance lymphography (MRL).

Gadoxetate disodium-induced tachypnoea and the effect of dilution method: a proof-of-concept study in mice

AbstractObjectivesTo directly investigate the rapid respiratory effect of gadoxetate disodium in an experimental study using mice.MethodsAfter confirming the steady respiratory state under general anaesthesia, eight mice were injected with all test agents in the following order: phosphate-buffered saline (A, control group), 1.25 mmol/kg of gadoteridol (B) or gadopentetate dimeglumine (C), or 0.31 mmol/kg of gadoxetate disodium (D, E). The experimenter was not blinded to the agents. The injection dose was fixed as 100 μL for Groups A-D and 50 μL for Group E. We continuously monitored and recorded respiratory rate (RR), peripheral oxygen saturation (SpO2), and heart rate. The time-series changes from 0 to 30 s were compared by the linear mixed methodResultsGroups D and E showed the largest RR increase (20.6 and 20.3 breaths/min, respectively) and were significantly larger compared to Group A (3.36 breaths/min, both P<0.001). RR change of Groups D and E did not differ. RR change of Groups B and C was smaller (0.72 and 12.4 breaths/min, respectively) and did not differ statistically with Group A. Significant bradycardia was observed only in Group C (P<0.001). SpO2 was constant in all groups.ConclusionsGadoxetate disodium causes a rapid tachypnoea without significant change of SpO2 and heart rate regardless of the dilution method.Key Points• Injection of gadoxetate disodium causes tachypnoea.n • Dilution methoddid not alter the rapid respiratory effect of gadoxetate disodium.• The respiratory effect of gadoxetate disodium was larger than other contrast agents.

Imaging prediction of nonalcoholic steatohepatitis using computed tomography texture analysis

ObjectivesTo determine if texture analysis of non-contrast-enhanced CT (NECT) images is able to predict nonalcoholic steatohepatitis (NASH).MethodsNECT images from 88 patients who underwent a liver biopsy for the diagnosis of suspected NASH were assessed and texture feature parameters were obtained without and with filtration. The patient population was divided into a predictive learning dataset and a validation dataset, and further divided into groups according to the prediction of liver fibrosis as assessed by hyaluronic acid levels. The reference standard was the histological result of a liver biopsy. A predictive model for NASH was developed using parameters derived from the learning dataset that demonstrated areas under the receiver operating characteristic curve (AUC) of >0.65. The resulting model was then applied to the validation dataset.ResultsIn patients without suspected fibrosis, the texture parameter mean without filter and skewness with a 2-mm filter were selected for the NASH prediction model. The AUC of the predictive model for the validation dataset was 0.94 and the accuracy was 94%. In patients with suspicion of fibrosis, the mean without filtration and kurtosis with a 4-mm filter were selected for the NASH prediction model. The AUC for the validation dataset was 0.60 and the accuracy was 42%.ConclusionsIn patients without suspicion of fibrosis, NECT texture analysis effectively predicted NASH.Key Points• In patients without suspicion of fibrosis, NECT texture analysis effectively predicted NASH.• The mean without filtration and skewness with a 2-mm filter were modest predictors of NASH in patients without suspicion of liver fibrosis.• Hepatic fibrosis masks the characteristic texture features of NASH.

The inhibitory effect of gadoxetate disodium on hepatic transporters: a study using indocyanine green

ObjectivesTo assess the inhibitory effect of gadoxetate disodium on the transporter system using indocyanine green (ICG).Materials and MethodsGroups of six female B6 Albino mice were injected with the test agent (0.62 mmol/kg gadoxetate disodium) or phosphate-buffered saline (control) 10 min before injection of ICG. Identical fluorescence images were subsequently obtained to create time-efficiency curves of liver parenchymal uptake. The study was performed on hypothermic and normothermic mice. The logarithms of the absorption rate constants (logKa values) and of the elimination rate constants (logKe values) were calculated for each experimental condition, and between-group differences were compared using Student’s t-test.ResultsThe logKe values of the test group were lower than those of the control group at both temperatures (-6.52 vs. -5.87 under hypothermic conditions and -4.54 vs. -4.14 under normothermic conditions), and both differences were statistically significant (p = 0.037, 0.015 respectively). In terms of the logKa values, although the difference did not reach statistical significance (p = 0.052), the test group had lower values than the control group under hypothermic conditions (-0.771 vs. -0.376). In normothermic mice, the logKa values for the test and control groups were 0.037 and 0.277 respectively, thus not significantly different (p = 0.404).ConclusionsGadoxetate disodium inhibited ICG excretion. Thus, gadoxetate disodium inhibited the ATP-binding cassette sub-family C member 2 transporter.Key Points• Gadoxetate disodium inhibited ICG excretion.• Gadoxetate disodium tended to inhibit hepatic ICG uptake.• Drug-drug interactions of gadoxetate disodium need further investigation.

Predicting prognosis of resected hepatocellular carcinoma by radiomics analysis with random survival forest

RATIONALE AND OBJECTIVESnTo investigate the impact of random survival forest (RSF) classifier trained by radiomics features over the prediction of the overall survival of patients with resectable hepatocellular carcinoma (HCC).nnnMATERIALS AND METHODSnThe dynamic computed tomography data of 127 patients (97 men, 30 women; mean age, 68 years) newly diagnosed with resectable HCC were retrospectively analyzed. After manually setting the region of interest to include the tumor within the slice at its maximum diameter, texture analyses were performed with or without a Laplacian of Gaussian filter. Using the extracted 96 histogram based texture features, RSFs were trained using 5-fold cross-validation to predict the individual risk for each patient on disease free survival (DFS) and overall survival (OS). The associations between individual risk and DFS or OS were evaluated using Kaplan-Meier analysis. The effects of the predicted individual risk and clinical variables upon OS were analyzed using a multivariate Cox proportional hazards model.nnnRESULTSnAmong the 96 histogram based texture features, RSF extracted 8 of high importance for DFS and 15 for OS. The RSF trained by these features distinguished two patient groups with high and low predicted individual risk (P=1.1×10-4 for DFS, 4.8×10-7 for OS). Based on the multivariate Cox proportional hazards model, high predicted individual risk (hazard ratio=1.06 per 1% increase, P=8.4×10-8) and vascular invasion (hazard ratio=1.74, P=0.039) were the only unfavorable prognostic factors.nnnCONCLUSIONSnThe combination of radiomics analysis and RSF might be useful in predicting the prognosis of patients with resectable HCC.

Imaging Findings of Gastric Carcinoma

Gastric carcinoma is the fourth most common cancer worldwide, behind lung, breast and colorectal carcinomas, and is the second leading cause of death in both sexes worldwide and in Asia [1, 2]. There is about twice male predominance.Gastric carcinoma is particularly common in countries such as Korea (incidence 62.2 per 100,000 males; mortality 22.8 per 100,000 males), Japan (46.8; 20.5), China (41.3; 30.5), Chile (27.3; 23.1), Russia (26.9; 24.0) but not as common in a large part of western societies such as the United States (5.7; 2.7) and United Kingdom (8.0; 4.8) [1].