Taro Matsushita

Inflammatory imaging with ultrasmall superparamagnetic iron oxide

The purpose of this study was to investigate the usefulness and feasibility of magnetic resonance imaging (MRI) with ultrasmall superparamagnetic iron oxide (USPIO) (USPIO-enhanced MRI) for imaging inflammatory tissues. First, we investigated the relationship between the apparent transverse relaxation rate (R2*) and the concentration of USPIO by phantom studies and measured the apparent transverse relaxivity (r2*) of USPIO. Second, we performed animal experiments using a total of 30 mice. The mice were divided into five groups [A (n=6), B (n=6), C (n=6), sham control (n=6), and control (n=6)]. The mice in Groups A, B, C and control were subcutaneously injected with 0.1 ml of turpentine oil on Day 0, while those in the sham control group were subcutaneously injected with 0.1 ml of saline. The mice in Groups A, B, C and sham control were intraperitoneally injected with 200 μmol Fe per kilogram body weight of USPIO (28 nm in diameter) immediately after the first MRI study on Days 3, 5, 7 and 7, respectively, and those in the control group were not injected with USPIO. The second and third MRI studies were performed at 24 and 48 h after USPIO administration, respectively. The maps of R2* were generated from the apparent transverse relaxation time (T2*)-weighted images with six different echo times. The phantom studies showed that there was a linear relationship between R2* and the concentration of USPIO (r=0.99) and the r2* value of USPIO was 105.7 mM(-1) s(-1). There was a significant increase of R2* in inflammatory tissues in Group C at 24 h after USPIO administration compared with the precontrast R2* value. Our results suggest that USPIO-enhanced MRI combined with R2* measurement is useful for detecting inflammatory tissues.

Investigation of protective effect of hydrogen-rich water against cisplatin- induced nephrotoxicity in rats using blood oxygenation level-dependent magnetic resonance imaging

PurposeThe aim of this study was to assess the mechanism of the protective effect of hydrogen-rich water (HW) against cisplatin (CP)-induced nephrotoxicity in rats using blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI).Materials and methodsApparent transverse relaxation time-weighted images (T2*WI) were acquired in 28 rats. The control group (n = 7) had free access to standard water (SW) and no CP injection. The CP group (n = 7) had free access to SW and was given a CP injection on day 0. The CP+HW group (n = 7) had free access to HW and had a CP injection. The HW group (n = 7) had free access to HW and no CP injection. The apparent transverse relaxation rate (R2*) was estimated from T2*WI.ResultsIn the CP+HW group, the R2* value in the medulla normalized by the value of the day 0 was significantly greater than that in the CP group on days 4 and 7. The creatinine and blood urea nitrogen levels in the CP group were significantly higher than those in the control, CP+HW, and HW groups.ConclusionBOLD MRI may be useful for demonstrating the change in R2* in CP-induced nephrotoxicity in rats. The changes in the CP+HW group were suspected to be due to a reduction of cytotoxic oxygen radicals.

Assessment of liver function in thioacetamide-induced rat acute liver injury using an empirical mathematical model and dynamic contrast-enhanced MRI with Gd-EOB-DTPA.

To evaluate thioacetamide (TAA)‐induced acute liver injury in rats using an empirical mathematical model (EMM) and dynamic contrast‐enhanced magnetic resonance imaging (DCE‐MRI) with gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd‐EOB‐DTPA).