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BACKGROUND When determining treatment strategies for male infertility, it is important to evaluate spermatogenesis and its spatial distribution in the testes. PURPOSE To investigate the usefulness of creatine chemical exchange saturation transfer (CrCEST) imaging for evaluating spermatogenesis and its spatial distribution. STUDY TYPE Prospective. ANIMAL MODEL C57BL/6 control mice (n = 5) and model mice of male infertility induced by whole testis X-ray irradiation (n = 11) or localized X-ray irradiation to lower regions of testes (n = 3). FIELD STRENGTH/SEQUENCE A 11.7-T vertical-bore magnetic resonance imaging (MRI)/segmented fast low-angle shot acquisition for CEST. ASSESSMENT The magnetization transfer ratio for the CrCEST effect (MTRCr* ) was calculated in each testis of the control mice and X-ray irradiation model mice at 10, 15, 20, and 30 days after irradiation. Correlation analysis was performed between MTRCr* and Johnsen's score, a histological score for spermatogenesis. In the localized X-ray irradiation model, regional MTRCr* and Johnsen's score were calculated for correlation analysis. STATISTICAL TESTS Unpaired t-test, one-way analysis of variance with Tukey's HSD test and Pearson's correlation analysis. A P value

BACKGROUND Creatine chemical exchange saturation transfer (CrCEST) imaging is expected to be a novel evaluation method of muscular energy metabolism. PURPOSE To develop CrCEST imaging of mouse skeletal muscle and to validate this technique by measuring changes in Cr concentration of ischemic hindlimbs. STUDY TYPE Prospective. ANIMAL MODEL C57BL/6 mice (n = 6), mild hindlimb ischemic mice (n = 6), and severe hindlimb ischemic mice (n = 6). FIELD STRENGTH/SEQUENCE Magnetic resonance angiography (MRA), CrCEST imaging, and phosphorus magnetic resonance spectroscopy (31 P MRS) obtained at 11.7T. ASSESSMENT MRA and 31 P MRS were performed to confirm the presence of ischemia following the compression by rubber tourniquet. CrCEST imaging was performed and magnetization transfer ratio asymmetry (MTRasym ), which reflects Cr concentration, and was calculated in severe ischemia models, mild ischemia models, and control mice. Follow-up CrCEST imaging was performed after the release of ischemia in the mild ischemia models. STATISTICAL TESTS Mean ± SD, one-way analysis of variance (ANOVA) with Tukey's HSD test, unpaired or paired t-test. RESULTS MRA revealed the loss of blood flow of the femoral artery in the ischemic hindlimb. 31 P MRS revealed different degrees of PCr decrease in severe and mild ischemic hindlimb (n = 3 per group, normal hindlimb: 1.0 ± 0, mild ischemic hindlimb: 0.77 ± 0.13, severe ischemic hindlimb: 0 ± 0). CrCEST imaging inversely revealed a significant stepwise increase in the MTRasym ratio of ischemic hindlimbs compared with controls (control, mild ischemia, and severe ischemia; 0.99 ± 0.04, 1.36 ± 0.08, and 1.59 ± 0.23, respectively, P < 0.0001). In addition, follow-up CrCEST imaging after the release of ischemia revealed normalization of the MTRasym ratios (recovered hindlimb: 1.01 ± 0.05). DATA CONCLUSION We demonstrated an increase in the MTRasym of ischemic hindlimbs, along with a decrease of PCr. We demonstrated the normalization of MTRasym after the release of ischemia and developed CrCEST imaging of mouse skeletal muscle. LEVEL OF EVIDENCE 2 Technical Efficacy: Stage 2 J. Magn. Reson. Imaging 2020;51:563-570.

The present study aimed to quantitatively characterize changes in the whole brain and arterial morphology in response to prenatal ionizing irradiation. Magnetic resonance imaging (MRI) and angiography (MRA) were used to evaluate brain and arterial abnormalities in 8-week-old male mice prenatally exposed to X-ray radiation at a dose of 0.5 or 1.0 Gy on embryonic day (E) 13. Irradiated mice demonstrated decreased brain volume, increased ventricular volume, and arterial malformation. Additionally, MRA signal intensity and arterial thickness in the anterior cerebral artery, middle cerebral artery, and basilar artery were lower in radiation-exposed mice than in control mice. MRI and MRA are useful tools for assessing brain and arterial abnormalities after prenatal exposure to radiation.

Pharmacological magnetic resonance imaging (phMRI) is a powerful tool for imaging the effects of drugs on brain activity. In preclinical phMRI studies, general anesthesia used for minimizing head movements is thought to influence the phMRI responses to drugs. In this study we investigated the phMRI responses to a selective dopamine transporter (DAT) inhibitor, GBR12909, and a dopamine (DA) releaser, d-amphetamine (AMPH), in the isoflurane anesthetized and awake rats using a relative cerebral blood volume (rCBV) method. AMPH (1 mg/kg i.p.) caused an increase in rCBV in the dopaminergic circuitry in the both anesthetized and awake rats. The striatal rCBV change was correlated with the change of the striatal DA concentration induced by AMPH in the both anesthetized and awake rats. GBR12909 (10 mg/kg i.p.) caused a positive rCBV response and showed a similar regional pattern of rCBV response to AMPH in the awake rats, and the correlation between the change of the striatal rCBV and the striatal DA concentration was observed. However, in the anesthetized rats, GBR12909 induced a widespread negative rCBV response, whereas an increase in striatal DA concentration was observed. These findings indicate that phMRI responses to activation of DA neurotransmission by GBR12909 or AMPH are overall identical in the awake state, while the phMRI response to a DAT inhibitor, GBR12909 but not to AMPH was changed by isoflurane anesthesia. For the evaluation of neuroactive drugs using phMRI, isoflurane anesthesia might be complicated the interpretation of pharmacodynamic effects of drugs in preclinical studies. Synapse, 69:203–212, 2015. © 2015 Wiley Periodicals, Inc.

(19)F magnetic resonance imaging (MRI) probes that can detect biological phenomena such as cell dynamics, ion concentrations, and enzymatic activity have attracted significant attention. Although perfluorocarbon (PFC) encapsulated nanoparticles are of interest in molecular imaging owing to their high sensitivity, activatable PFC nanoparticles have not been developed. In this study, we showed for the first time that the paramagnetic relaxation enhancement (PRE) effect can efficiently decrease the (19)F NMR/MRI signals of PFCs in silica nanoparticles. On the basis of the PRE effect, we developed a reduction-responsive PFC-encapsulated nanoparticle probe, FLAME-SS-Gd(3+) (FSG). This is the first example of an activatable PFC-encapsulated nanoparticle that can be used for in vivo imaging. Calculations revealed that the ratio of fluorine atoms to Gd(3+) complexes per nanoparticle was more than approximately 5.0×10(2), resulting in the high signal augmentation.

Ratiometric MRI sensors consist of paramagnetic cores and pH-sensitive polymer shells. The core-shell nanostructure enables the coexistence of two incompatible NMR relaxation properties in one particle. The sensors show pH sensitivity in transverse relaxivity (r2 ), but not in longitudinal relaxivity (r1 ). Quantitative pH imaging is achieved by measuring the r2 /r1 value with a clinical 3 T MRI scanner.

19F magnetic resonance imaging (19F MRI) is useful for monitoring particular signals from biological samples, cells, and target tissues, because background signals are missing in animal bodies. Therefore, highly sensitive 19F MRI contrast agents are in great demand for their practical applications. However, we have faced the following challenges: 1) increasing the number of fluorine atoms decreases the solubility of the molecular probes, and 2) the restriction of the molecular mobility attenuates the 19F MRI signals. Herein, we developed novel multifunctional core–shell nanoparticles to solve these issues. They are composed of a core micelle filled with liquid perfluorocarbon and a robust silica shell. These core–shell nanoparticles have superior properties such as high sensitivity, modifiability of the surface, biocompatibility, and sufficient in vivo stability. By the adequate surface modifications, gene expression in living cells and tumor tissue in living mice were successfully detected by 19F MRI.

Cerebellar abnormalities in 4-week-old rats with a single whole body X-irradiation at a dose of 0.5, 1.0, or 1.5 Gy on embryonic day (ED) 15 were examined by magnetic resonance imaging (MRI) volumetry. A 3D T2W-MRI anatomical sequence with high-spatial resolution at 11.7-tesla was acquired from the fixed rat heads. By MRI volumetry, whole cerebellar volumes decreased dose-dependently. Multiple linear regression analysis revealed that the cortical volume (standardized β = 0.901; P

Aim: Carnosic acid (CA) inhibits adipogenesis in vitro. The present study evaluated the therapeutic effects of CA in ob/ob mice. Methods: The experimental animals were given a standard chow diet with or without CA for 5 weeks. Bodyweight gain and food intake were measured during this period. Magnetic resonance imaging analysis, histological examination, serum chemistry analysis and intraperitoneal glucose tolerance test (IPGTT) were all performed. Results: The mice fed CA experienced significant weight loss and reduced visceral adiposity, in addition to significantly reduced serum triglyceride (TG) and cholesterol levels. Importantly, CA had a dramatic effect on the liver by reducing the hepatic TG content, thus decreasing serum alanine aminotransferase levels. In addition, IPGTT revealed that CA significantly improved glucose tolerance. Conclusion: These data suggest that CA is a novel therapeutic agent for obesity-related non-alcoholic fatty liver disease.

In vivo molecular imaging is a rapidly growing research area both for basic and clinical science. Non-invasive imaging of in vivo conditions at the molecular level increases understanding of the biological characteristics of normal and diseased tissues without the need for invasive surgical procedures. Among the various imaging modalities, magnetic resonance imaging (MRI) has garnered interest as a molecular imaging modality due to its high spatial resolution. Here, we have demonstrated that the combined use of HER-2 targeting affibody, a small 7 kDa molecule that behaves similarly to antibodies, and superparamagnetic iron oxide (SPIO) can non-invasively image HER-2 expressing cells or tissues both in vitro and in vivo by MRI. This preliminary study demonstrates that affibody-SPIO is a feasible, target-specific contrast agent for in vivo MR molecular imaging.

Trichloroacetic acid petachlorophenyl ester (TCA-O-PCP) was found to form a 2:i adduct with benzene. It showed an eight line 35Cl NQR spectrum in the range 77 ≦ T/K ≦ 312 (decomposition temperature of the adduct). TCA-O-PCP was proved to have three crystalline phases. Phase I is stable in the range 77 ≦ T/K ≦ 403 (melting point of phase I). It exhibited also an eight line 35Cl NQR spectrum. A metastable phase (phase III) was obtained by quenching the liquid TCA-O-PCP to 77 K and on heating it was transformed into another metastable phase (phase II) at ca. 310 K. The transition III ⇄ II was enantiotropic and of higher order. At T/K ≧ ca. 360 a gradual, monotropic transition of II I was observed. A 35Cl NQR spectrum having poor signal to noise ratio was found for phase III. A pronounced rise of the NQR frequency due to steric effect was observed for phase I of TCA-O-PCP. Remarkable differences in the characteristics of the NQR spectrum of -CCl3 group were found between the spectrum of the adduct and that of phase I. Some conformational change of TCA-O-PCP molecule accompanied by the adduct formation is thought to be responsible for the differences in the NQR spectrum.