A mouse model of autoimmune inner ear disease without endolymphatic hydrops.

Autoimmune inner ear disease (AIED) is an organ-specific disease characterized by irreversible, prolonged, and progressive hearing and equilibrium dysfunctions. The primary symptoms of AIED include asymmetric sensorineural hearing loss accompanied by vertigo, aural fullness, and tinnitus. AIED is divided into primary and secondary types. Research has been conducted using animal models of rheumatoid arthritis (RA), a cause of secondary AIED. However, current models are insufficient to accurately analyze vestibular function, and the mechanism underlying the onset of AIED has not yet been fully elucidated. Elucidation of the mechanism of AIED onset is urgently needed to develop effective treatments. In the present study, we analyzed the pathogenesis of vertigo in autoimmune diseases using a mouse model of type II collagen-induced RA. Auditory brain stem response analysis demonstrated that the RA mouse models exhibited hearing loss, which is the primary symptom of AIED. In addition, our vestibulo-oculomotor reflex analysis, which is an excellent vestibular function test, accurately captured vertigo symptoms in the RA mouse models. Moreover, our results revealed that the cause of hearing loss and vestibular dysfunction was not endolymphatic hydrops, but rather structural destruction of the organ of Corti and the lateral semicircular canal ampulla due to an autoimmune reaction against type II collagen. Overall, we were able to establish a mouse model of AIED without endolymphatic hydrops. Our findings will help elucidate the mechanisms of hearing loss and vertigo associated with AIED and facilitate the development of new therapeutic methods.

Transplantation of Human Embryonic Stem Cell-Derived Pericyte-Like Cells Transduced with Basic Fibroblast Growth Factor Promotes Angiogenic Recovery in Mice with Severe Chronic Hindlimb Ischemia.

Critical limb ischemia (CLI) is a state of severe peripheral artery disease, with no effective treatment. Cell therapy has been investigated as a therapeutic tool for CLI, and pericytes are promising therapeutic candidates based on their angiogenic properties. We firstly generated highly proliferative and immunosuppressive pericyte-like cells from embryonic stem (ES) cells. In order to enhance the angiogenic potential, we transduced the basic fibroblast growth factor (bFGF) gene into the pericyte-like cells and found a significant enhancement of angiogenesis in a Matrigel plug assay. Furthermore, we evaluated the bFGF-expressing pericyte-like cells in the previously established chronic hindlimb ischemia model in which bone marrow-derived MSCs were not effective. As a result, bFGF-expressing pericyte-like cells significantly improved blood flow in both laser Doppler perfusion imaging (LDPI) and dynamic contrast-enhanced MRI (DCE-MRI). These findings suggest that bFGF-expressing pericyte-like cells differentiated from ES cells may be a therapeutic candidate for CLI.

Feasibility of Diffusion-weighted Imaging (DWI) for Assessing Cerebrospinal Fluid Dynamics: DWI-fluidography in the Brains of Healthy Subjects.

PURPOSE: The present study aimed to investigate whether diffusion-weighted imaging (DWI) can qualify and quantify cerebrospinal fluid (CSF) dynamics in the brains of healthy subjects. For this purpose, we developed new DWI-based fluidography and compared the CSF dynamics seen on the fluidography with two apparent diffusion coefficients obtained with different DWI signal models at anatomical spaces filled by CSF. METHODS: DWI with multiple b values was performed for 10 subjects using a 7T MRI scanner. DWI-fluidography based on the DWI signal variations in different motion probing gradient directions was developed for visualizing the CSF dynamics voxel-by-voxel. DWI signals were measured using an ROI in the representative CSF-filled anatomical spaces in the brain. For the multiple DWI signals, the mono-exponential and kurtosis models were fitted and two kinds of apparent diffusion coefficients (ADCC and ADCK) were estimated in each space using the Gaussian and non-Gaussian diffusion models, respectively. RESULTS: DWI-fluidography could qualitatively represent the features of CSF dynamics in each anatomical space. ADCs indicated that the motions at the foramen of Monro, the cistern of the velum interpositum, the quadrigeminal cistern, the Sylvian cisterns, and the fourth ventricle were more drastic than those at the subarachnoid space and anterior horns of the lateral ventricle. Those results seen in ADCs were identical to the findings on DWI-fluidography. CONCLUSION: DWI-fluidography based on the features of DWI signals could show differences of CSF dynamics among anatomical spaces.

Non-invasive differentiation of hepatic steatosis and steatohepatitis in a mouse model using nitroxyl radical as an MRI-contrast agent.

Drug-induced steatohepatitis is considered more serious than drug-induced hepatic steatosis, so that differentiating between the two is crucial in drug development. In addition, early detection of drug-induced steatohepatitis is considered important since recovery is possible with drug withdrawal. However, no method has been established to differentiate between the two. In the development of drug-induced steatohepatitis, reactive oxygen species (ROS) is excessively generated in the liver. It has been reported that ROS can be monitored with electron spin resonance (ESR) and dynamic nuclear polarization-magnetic resonance imaging (DNP-MRI) by using nitroxyl radicals, which are known to participate in various in vivo redox reactions. The decay/reduction rate, which is an index for monitoring nitroxyl radicals, has been reported to be increased in tissues with excessive ROS levels other than liver, but decreased in methionine choline deficient (MCD) diet-induced steatohepatitis with excess ROS. Therefore, looking to differentiate between drug-induced hepatic steatosis and steatohepatitis, we examined whether the reduction rate decreases in steatohepatitis other than the MCD-diet induced disease and whether the decrease could be detected by MRI. We used STAM™ mice in which hepatic steatosis and steatohepatitis developed sequentially under diabetic conditions. 3-carbamoyl-PROXYL (CmP), one of the nitroxyl radicals, was injected intravenously during the MRI procedure and the reduction rate was calculated. The reduction rate was significantly higher in early steatohepatitis than in hepatic steatosis and the control. Excess ROS in early steatohepatitis was detected by an immunohistochemical marker for ROS. Therefore, it was indicated that the increase or decrease in the reduction rate in steatohepatitis differs depending on the model, and early steatohepatitis could be noninvasively differentiated from hepatic steatosis using CmP in MRI. Since the change in direction of the reduction rate in steatohepatitis in clinical studies could be predicted by confirming the reduction rate in preclinical studies, the present method, which can be used consistently in clinical and preclinical studies, warrants consideration as a candidate monitoring method for differentiating between early drug-induced steatohepatitis and hepatic steatosis in drug development.

AAV-based gene therapy ameliorated CNS-specific GPI defect in mouse models.

Thirty genes are involved in the biosynthesis and modification of glycosylphosphatidylinositol (GPI)-anchored proteins, and defects in these genes cause inherited GPI deficiency (IGD). PIGA is X-linked and involved in the first step of GPI biosynthesis, and only males are affected by variations in this gene. The main symptoms of IGD are neurological abnormalities, such as developmental delay and seizures. There is no effective treatment at present. We crossed Nestin-Cre mice with Piga-floxed mice to generate CNS-specific Piga knockout (KO) mice. Hemizygous KO male mice died by P10 with severely defective growth. Heterozygous Piga KO female mice are mosaic for Piga expression and showed severe defects in growth and myelination and died by P25. Using these mouse models, we evaluated the effect of gene replacement therapy with adeno-associated virus (AAV). It expressed efficacy within 6 days, and the survival of male mice was extended to up to 3 weeks, whereas 40% of female mice survived for approximately 1 year and the growth defect was improved. However, liver cancer developed in all three treated female mice at 1 year of age, which was probably caused by the AAV vector bearing a strong CAG promoter.

Micro-magnetic resonance imaging of ex vivo mouse embryos with potato starch suspension.

Potato starch suspension (PSS) holds promise as a solution to issues, such as air bubbles and specimen motion, associated with micro-magnetic resonance imaging (micro-MRI) of ex vivo embryos. Here, we present a protocol for using PSS when scanning specimens with micro-MRI. We describe steps for preparing samples and potato starch with phosphate-buffered saline. We then detail steps for specimen immersion and micro-MRI scanning. This protocol will enable micro-MRI of not only embryos but also other specimens, such as insects. For complete details on the use and execution of this protocol, please refer to Tsurugizawa et al.1.

Comparison of 1H-magnetic resonance spectroscopy and blood biochemistry as methods for monitoring non-diffuse hepatic steatosis in a rat model.

No method of monitoring drug-induced hepatic steatosis has been established, which is a concern in drug development. Hepatic steatosis is divided into diffuse and non-diffuse forms according to the pattern of fat deposition. Diffuse hepatic steatosis was reported as evaluable by 1H-magnetic resonance spectroscopy (1H-MRS), which is used as an adjunct to the MRI examination. Blood biomarkers for hepatic steatosis have been also actively investigated. However, there are few reports to conduct 1H-MRS or blood test in human or animal non-diffuse hepatic steatosis with reference to histopathology. Therefore, to investigate whether non-diffuse hepatic steatosis can be monitored by 1H-MRS and/or blood samples, we compared histopathology to 1H-MRS and blood biochemistry in a non-diffuse hepatic steatosis rat model. Non-diffuse hepatic steatosis was induced by feeding rats the methionine choline deficient diet (MCDD) for 15 days. The evaluation sites of 1H-MRS and histopathological examination were three hepatic lobes in each animal. The hepatic fat fraction (HFF) and the hepatic fat area ratio (HFAR) were calculated from 1H-MRS spectra and digital histopathological images, respectively. Blood biochemistry analyses included triglycerides, total cholesterol, alanine aminotransferase, and aspartate aminotransferase. A strong correlation was found between HFFs and HFARs in each hepatic lobe (r = 0.78, p < 0.0001) in rats fed the MCDD. On the other hand, no correlation was found between blood biochemistry values and HFARs. This study showed that 1H-MRS parameters correlated with histopathological changes but blood biochemistry parameters didn't, so that it is suggested that 1H-MRS has the potential to be a monitoring method for non-diffuse hepatic steatosis in rats fed the MCDD. Given that 1H-MRS is commonly used in preclinical and clinical studies, 1H-MRS should be considered a candidate method for monitoring drug-induced hepatic steatosis.

Ultra-high-field pharmacological functional MRI of dopamine D1 receptor-related interventions in anesthetized rats.

The dopamine D1 receptor (D1R) is associated with schizophrenia, Parkinson's disease, and attention deficit hyperactivity disorder. Although the receptor is considered a therapeutic target for these diseases, its neurophysiological function has not been fully elucidated. Pharmacological functional MRI (phfMRI) has been used to evaluate regional brain hemodynamic changes induced by neurovascular coupling resulting from pharmacological interventions, thus phfMRI studies can be used to help understand the neurophysiological function of specific receptors. Herein, the blood oxygenation level-dependent (BOLD) signal changes associated with D1R action in anesthetized rats was investigated by using a preclinical ultra-high-field 11.7-T MRI scanner. PhfMRI was performed before and after administration of the D1-like receptor agonist (SKF82958), antagonist (SCH39166), or physiological saline subcutaneously. Compared to saline, the D1-agonist induced a BOLD signal increase in the striatum, thalamus, prefrontal cortex, and cerebellum. At the same time, the D1-antagonist reduced the BOLD signal in the striatum, thalamus, and cerebellum by evaluating temporal profiles. PhfMRI detected D1R-related BOLD signal changes in the brain regions associated with high expression of D1R. We also measured the early expression of c-fos at the mRNA level to evaluate the effects of SKF82958 and isoflurane anesthesia on neuronal activity. Regardless of the presence of isoflurane anesthesia, c-fos expression level was increased in the region where positive BOLD responses were observed with administration of SKF82958. These findings demonstrated that phfMRI could be used to identify the effects of direct D1 blockade on physiological brain functions and also for neurophysiological assessment of dopamine receptor functions in living animals.

Evaluation of in vivo MRI for detecting midodrine-induced arteritis in rats.

There are no specific and sensitive biomarkers for arteritis, and the occurrence of arteritis in nonclinical toxicological studies of a candidate drug makes development of the drug very difficult. However, we showed in a previous study that the high signal intensity region around the artery on magnetic resonance imaging (MRI) could be a candidate biomarker for detection of arteritis. The present study was conducted to clarify the details of midodrine hydrochloride (MH)-induced arteritis lesions and whether arteritis induced by a mechanism other than the vasodilatory effect, which was evaluated in a previous study, could be detected by MRI. MH is a selective peripherally acting alpha-1 adrenergic receptor agonist, known to induce arteritis due to its vasoconstrictor action, but there is not enough information about MH-induced arteritis. Based on the data obtained under multiple dosing conditions, MH was administered subcutaneously to each rat once daily for 2 days at a dose level of 40 mg/kg/day for MRI assessment. The mesenteric arteries were examined using in vivo MRI at 1 day or 7 days after administration of the final dose and examined histopathologically. On the day after the final dose, high signal intensity region around the artery was observed in animals with minimal perivascular lesions confirmed by histopathology and not observed in an animal without histological changes. On the 7th day after the final dose, no abnormality was observed in histopathological examinations and no high signal intensity regions were observed by MRI in any animal. In conclusion, although further investigation is needed to confirm that high signal intensity is a reliable biomarker for humans, it is suggested that high signal intensity around the artery could be a versatile candidate biomarker with high specificity and sensitivity.

Utilization of potato starch suspension for MR-microimaging in ex vivo mouse embryos.

Magnetic resonance (MR) microimaging of the mouse embryo is a promising tool to noninvasively investigate the microstructure of the brain of a developing mouse. The proton-free fluid is used for the liquid surrounding the specimen in MR microimaging, but the potential issue of image quality remains due to the air bubbles on the specimen and the retained water proton in the curvature of the embryo. Furthermore, the specimen may move during the scanning, resulting in motion artifact. Here, we developed the new concept of the ex vivo microimaging protocol with the robust method using the potato starch-containing biological polymers. Potato starch suspension with PBS significantly reduced T1 and T2 signal intensity of the suspension and strongly suppressed the motion of the embryo. Furthermore, potato starch-PBS suspension is stable for long-time scanning at room temperature. These results indicate the utility of potato starch suspension for MR microimaging in mouse embryos.

Detection of fenoldopam-induced arteritis in rats using ex vivo / in vivo MRI.

A method capable of identifying drug-induced arteritis is highly desirable because no specific and sensitive biomarkers have yet been defined. Although magnetic resonance imaging (MRI) may be used to find a biomarker candidate for drug-induced arteritis, there are no reports on the evaluation of drug-induced arteritis by MRI. The present study was conducted to clarify whether Fenoldopam mesylate (FM)-induced arteritis in rats can be detected by MRI. FM, a dopamine (D1 receptor) agonist, is known to induce arteritis in rats. FM was administered subcutaneously to each rat once daily for 2 days at a dose of 100 mg/kg/day. These arteries were examined with ex vivo high-resolution MRI or postmortem MRI after euthanasia. These arteries were also examined using in vivo MRI on the day after final dosing or 3 days after administration of the final dose. These arteries were examined histopathologically in all experiments. The ex vivo MRI showed low-intensity areas and a high signal intensity region around the artery, and these findings were considered to be erythrocytes infiltrating the arterial wall and perivascular edema, respectively. In the in vivo study, the MRI of the FM-administered group showed a high signal intensity region around the artery. The perivascular edema observed histopathologically was recognized as a high signal intensity region around the artery on the image of MRI. In conclusion, detection of the high signal intensity region around the artery by MRI is considered to be a useful method for identifying arteritis. Although further investigation is needed to be a reliable biomarker, it is suggested that it could be a biomarker candidate.

A new therapy against ulcerative colitis via the intestine and brain using the Si-based agent.

Ulcerative colitis (UC) is a non-specific inflammatory bowel disease that causes ulcers and erosions in the colonic mucosa and becomes chronic with cycles of amelioration and exacerbation. Because its exact etiology remains largely unclear, and the primary therapy is limited to symptomatic treatment, the development of new therapeutic agent for UC is highly desired. Because one of the disease pathogenesis is involvement of oxidative stress, it is likely that an appropriate antioxidant will be an effective therapeutic agent for UC. Our silicon (Si)-based agent, when ingested, allowed for stable and persistent generation of massive amounts of hydrogen in the gastrointestinal tract. We demonstrated the Si-based agent alleviated the mental symptom as well as the gastrointestinal symptoms, inflammation, and oxidation associated with dextran sodium sulfate-induced UC model through Hydrogen and antioxidant sulfur compounds. As the Si-based agent was effective in treating UC in the brain and large intestine of mice, it was considered to be capable of suppressing exacerbations and sustaining remission of UC.

Establishment of mouse model of inherited PIGO deficiency and therapeutic potential of AAV-based gene therapy.

Inherited glycosylphosphatidylinositol (GPI) deficiency (IGD) is caused by mutations in GPI biosynthesis genes. The mechanisms of its systemic, especially neurological, symptoms are not clarified and fundamental therapy has not been established. Here, we report establishment of mouse models of IGD caused by PIGO mutations as well as development of effective gene therapy. As the clinical manifestations of IGD are systemic and lifelong lasting, we treated the mice with adeno-associated virus for homology-independent knock-in as well as extra-chromosomal expression of Pigo cDNA. Significant amelioration of neuronal phenotypes and growth defect was achieved, opening a new avenue for curing IGDs.

Visualization of Spatial Distribution of Spermatogenesis in Mouse Testes Using Creatine Chemical Exchange Saturation Transfer Imaging.

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 < 0.05 was considered statistically significant. RESULTS: In the irradiation model, CrCEST imaging revealed a significant linear decrease of MTRCr* after irradiation (control, 8.7 ± 0.6; 10 days, 7.9 ± 0.8; 15 days, 6.5 ± 0.6; 20 days, 5.4 ± 1.0; 30 days, 4.4 ± 0.8). A significant linear correlation was found between MTRCr* and Johnsen's score (Pearson's correlation coefficient (r) = 0.79). In the localized irradiation model, CrCEST imaging visualized a significant regional decrease of MTRCr* in the unshielded region (shielded, 6.9 ± 0.7; unshielded, 4.9 ± 1.0), and a significant linear correlation was found between regional MTRCr* and Johnsen's score (r = 0.78). DATA CONCLUSION: Testicular CrCEST effects correlated well with spermatogenesis. CrCEST imaging was useful for evaluating spermatogenesis and its spatial distribution. EVIDENCE LEVEL: 2 TECHNICAL EFFICACY: Stage 2.

Original experimental rat model of blast-induced mild traumatic brain injury: a pilot study.

OBJECTIVE: Diagnosing blast-induced mild traumatic brain injury (mTBI) is difficult due to minimal imaging findings. This study aimed to establish a rat model of behavioral abnormality caused by blast-induced mTBI and detect new findings for therapeutic intervention. METHODS: We used a bench-top blast wave generator with the blast wave exiting through a 20-mm I.D. nozzle aimed at the focused target. The blast wave was directed at the head of male Wistar rats under general anesthesia positioned prone 2.5 cm below the nozzle. Peak shock wave pressure was 646.2 ± 70.3 kPa. RESULTS: After blast injury, mTBI rats did not show the findings of brain hemorrhage or contusion macroscopically and on hematoxylin-eosin-stained frozen sections but did show anorexia and weight loss in the early post-injury phase. Behavioral experiments revealed short-term memory impairment at 2 weeks and depression-like behavior at 2 and 6 weeks. Diffusion-weighted ex vivo MRI showed high-intensity areas in layers of the bilateral hippocampus. Immunohistochemical analysis revealed accumulation of reactive microglia and GFAP-positive astrocytes in the same region and loss of NeuN-positive neurons in the hippocampal pyramidal cell layer. CONCLUSIONS: This model can reflect the pathophysiology of blast-induced mTBI and could potentially be used to develop therapeutic interventions in the future.

Accurate Estimation of the Duration of Testicular Ischemia Using Creatine Chemical Exchange Saturation Transfer (CrCEST) Imaging.

BACKGROUND: In the management of testicular torsion, estimating the duration of testicular ischemia is essential for deciding on an appropriate surgical treatment, but there are currently limited evaluation methods. PURPOSE: To perform testicular creatine chemical exchange saturation transfer (CrCEST) imaging and to evaluate its ability to accurately estimate the duration of testicular ischemia. STUDY TYPE: Prospective. ANIMAL MODEL: C57BL/6 control mice (n = 6) and testicular ischemia models induced by clamping the spermatic cord (n = 14). Eight of testicular ischemia models were serially imaged at two or three timepoints and a total of 26 images of ischemic testis were obtained. The ischemic duration ranged from 6-42 hours. FIELD STRENGTH/SEQUENCE: 11.7T vertical-bore MRI/segment fast low-angle shot acquisition for CEST. ASSESSMENT: CrCEST imaging was performed and the magnetization transfer ratio for the CrCEST effect (MTRCr** ) was calculated in control mice and testicular ischemia models. Correlation analysis between the duration of testicular ischemia and MTRCr** decline was performed. STATISTICAL TESTS: Paired t-test, and Pearson's correlation analysis. RESULTS: In control mice, the CrCEST effect in testes was significantly more than five times higher than that in skeletal muscle. MTRCr** did not differ significantly between the right and left testes (8.6 ± 0.8 vs. 8.3 ± 0.6, P = 0.96). In testicular ischemia models, MTRCr** of ischemic testes was significantly lower than that of controls (4 ± 2 vs. 8.9 ± 0.6, P < 0.001). Correlation analysis revealed a strong linear correlation between MTRCr** decline and the duration of ischemia (r = 0.96, P < 0.001). DATA CONCLUSION: A decreased CrCEST effect in ischemic testes correlated well with ischemic duration. Testicular CrCEST imaging was useful for accurately estimating the duration of testicular ischemia. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY STAGE: 2.

Feasibility of IVIM parameters from diffusion-weighted imaging at 11.7T MRI for detecting ischemic changes in common carotid artery occlusion rats.

This study aimed to investigate whether intravoxel incoherent motion (IVIM) parameters can identify ischemic changes in the rat cerebral cortex using a preclinical ultra-high-field 11.7 Tesla magnetic resonance imaging (11.7TMRI) scanner. In nine female Wistar rats (eight weeks old), diffusion-weighted imaging (DWI) for IVIM analysis was successfully performed before (Pre) and after unilateral (UCCAO) and bilateral (BCCAO) common carotid artery occlusion. From the acquired DWI signals averaged in six regions of interest (ROI) placed on the cortex, volume fraction of perfusion compartment (F), pseudo diffusion coefficient (D*), F × D* and apparent diffusion coefficient (ADC) were determined as IVIM parameters in the following three DWI signal models: the bi-exponential, kurtosis, and tri-exponential model. For a subgroup analysis, four rats that survived two weeks after BCCAO were assigned to the long survival (LS) group, whereas the non-LS group consisted of the remaining five animals. Each IVIM parameter change among three phases (Pre, UCCAO and BCCAO) was statistically examined in each ROI. Then, the change in each rat group was also examined for subgroup analysis. All three models were able to identify cerebral ischemic change and damage as IVIM parameter change among three phases. Furthermore, the kurtosis model could identify the parameter changes in more regions than the other two models. In the subgroup analysis with the kurtosis model, ADC in non-LS group significantly decreased between UCCAO and BCCAO but not in LS group. IVIM parameters at 11.7TMRI may help us to detect the subtle ischemic change; in particular, with the kurtosis model.

Mouse skeletal muscle creatine chemical exchange saturation transfer (CrCEST) imaging at 11.7T MRI.

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.

Female child with hematidrosis of the palm: Case report and published work review.

Hematidrosis is a rare disorder involving spontaneous excretion of sweat contaminated by blood cells. We report the case of a 6-year-old girl with hematidrosis from her palms with no underlying disease or psychotic disorder. Before the onset of this symptom, the patient was given an indoor horizontal exercise bar with which she had been frequently playing. This symptom appeared without apparent triggers and was not associated with subjective symptoms. To examine her hematidrosis, metabolites in the red bodily fluid were analyzed using nuclear magnetic resonance analysis. We found the fluid had a metabolome profile similar to that of eccrine sweat. Pathological analysis revealed no abnormal findings, including expression of the tight junction protein claudin 3. Her symptom decreased after treatment with tap-water iontophoresis. Here, we describe our case and discuss its etiology by reviewing previous reports.