Isotropic volumetric MRI for displaying cranial perineural spread of cranial nerve in nasopharyngeal carcinoma

Objective To observe the value of isotropic volumetric MRI for displaying perineural spread(PNS)of cranial nerve(CN)in nasopharyngeal carcinoma.Methods Eighty-seven patients with pathologically proven nasopharyngeal carcinoma were prospectively enrolled.MR scanning,including three-dimensional liver acquisition with volume acceleration-flexible(3D LAVA_Flex)image,T2WI with fat suppression(T2WI-FS),T1WI,contrast enhancement(CE)T1WI-FS of nasopharynx and neck region were performed.The displaying rates of CN PNS were evaluated and compared between 3D LAVA_Flex and T2WI-FS,T1WI,CE-T1WI-FS at patient level,CN group level and neural level,respectively.Results The displaying rate of CN PNS in all 87 nasopharyngeal carcinoma patients by 3D LAVA_Flex sequence was 49.43%(43/87),higher than that of conventional MRI(30/87,34.48%,P=0.001).Among 59 patients with advanced nasopharyngeal carcinoma diagnosed with conventional sequences,the displaying rate of CN PNS was 71.19%(42/59)by 3D LAVA-Flex sequence,higher than that of conventional MRI(30/59,50.85%,P=0.001).At both patient level and posterior CN level,significant differences of the displaying rate of CN PNS were found between 3D LAVA-Flex sequence and T2WI-FS,T1WI,CE-T1WI-FS,while at CN level,the displaying rates of mandibular nerve PNS,CNⅨ—ⅪPNS in jugular foramen(P<0.05)and CNⅨ—ⅫPNS in carotid space of 3D LAVA_Flex sequence were all significantly higher than that of T2WI-FS,T1WI and CE-T1WI-FS(all P<0.05),of PNS of CNⅢ—Ⅴin cavernous sinus were higher than that of T2WI-FS(P<0.05),while of PNS of hypoglossal nerve were significantly higher than that of T2WI-FS and T1WI(both P<0.05).Conclusion 3D LAVA_Flex sequence could be used to effectively display CN PNS of nasopharyngeal carcinoma.

砂金带磁现象初探

国内外许多砂金矿中,有的砂金具强磁性、电磁性.主要原因是铁的次生氧化物覆盖在砂金颗粒表面或充填于砂金颗粒的空洞中.

EVALUATION OF NEUROPROTECTIVE EFFECTS OF LONG-TERM LOW DOSE HORMONE REPLACEMENT THERAPY ON POSTMENOPAUSAL WO-MEN BRAIN HIPPOCAMPUS USING MAGNETIC RESONANCE SCANNER

To investigate the effects of long-term low dose hormone replacement therapy （HRT） on postmenopaosal women in homone level, cognition score, hippocampus volume, and magnetic resonance spectroscopy （MRS） parameters. Methods A total of 182 postmenopausal women aged 50-87 years were chosen at Peking Union Medical College Hospital and assigned to HRT group and control group. The volunteers of HRT group had taken low dose hormone [ estradiol （E2 ） 0. 5-1.0 mg and progesterone 0.5-2.0 mg, once a day ] for 4-33 years. The concentrations of E2, progesterone, and testosterone were measured using enzyme-linked immunosorbent assay （ELISA）. The gene types of apolipoprotein E （ApoE） were measured by polymerase chain reaction, and the subjects with susceptible genes （ ApoE ε3/ε4） of Alzheimer＇s disease （AD） were screened. Their hippocampus volumes and MRS parameters were obtained through magnetic resonance imaging （MRI）, and results in two groups were analyzed by statistical method. Results Compared with control group, the concentrations of E2 at each age stage in HRT group were significantly higher （P 〈0. 05） except the 80-89 years old subgroup; yet, there were no statistical differences in the concentrations of progesterone and testosterone between the two groups. There was no obvious difference in ApoE subtypes distribution between the two groups The results of hippocampus MRI for the subjects with susceptible genes ApoE ε3/ε4 （HRT group 14 cases, control group 11 cases） showed that the ratio of bilateral hippocampus volume to whole brain volume in HRT group （0. 406 ± 0.028） was signiticantlyhigher than control gronp （0.369±0.031, P〈0.05）. Theresults of ^1H MRS for the subjects with susceptible genes ApoE ε3/ε4 （ HRT group 12 cases, control group 11 cases） showed that the N-acetylaspartate/total creatine at the area of hippocampus in HRT group （ 1.54±0. 08 ） were significantly higher than control group （ 1.45±0. 13, P 〈 0. 05）. Conclusions For postmenopausal women, long-term low dose HRT can maintain the physiological concentration of E2 in plasma. Furthermore, the hippocampus MRI performed on those with ApoE ε3/ε3 genes shows that long-term low dose HRT can prevent hippocampus atrophy, which is beneficial to maintain the brain function and prevent AD.

Application of New Type BP Neural Networks for Magnetic Measurement

Magnetic measurement is a typical inverse problem in Biomedical field. In this kind of problem we always need to locate the positions and moments of one or more magnetic dipoles. Although using the traditional methods to solve this kind of inverse problem has all kinds of shortcomings, BPNN (Back Propagation Neural Networks) method can be used to solve this typical inverse problem fast enough for real time measurement. In the traditional BPNN method, gradient descent search method is performed for error propagation. In this paper the authors propose a new algorithm that Newton method is performed for error propagation. For the cost function is highly nonconvex in the magnetic measurement problem, the new kind of BPNN can get convergent results quickly and precisely. A simulation result for this method is also presented.

Growth and differentiation of neural stem cells with superparamagnetic iron oxides labeling in vitro

Objective： To study the growth and differentiation of superparamagnetie iron oxides（SPIOs） labeled neural stem cells （NSCs）. Methods： After NSCs were cultured and subcuhured from newborn rat brain, they were magnetically labeled with ferumoxides （a kind of SPIOs ）. Growth, differentiation and other biology properties of the cells were investigated with immunocytochemistry, transmission electron microscopy （TEM） and Prussian blue staining. Results： Nestin positive cells were found in the culture and offspring clones. NSCs could be differentiated into positive GFAP and NF200 cells in serum culture. When NSCs incubated with ferumoxides, the iron particles were seen in intracellular as well as in offspring clones. With the increase in concentration of ferumoxides （5.6-11.2/μg/ml）, ferumoxides showed no significant difference effects on the growth and differentiation of NSCs. When the concentration of ferumoxides exceeded 22.4μg/ml ,there was significant difference（P〈0.05）. Conclusion： We successfully label NSCs with ferumoxides,it is useful for tracking of magnetic labeled NSCs in vivo with MRI.

Empirical modeling of nonlinear and hysteresis characteristics of the shock absorber

An empirical hybrid shock absorber model capable of capturing nonlinear and hysteresis characteristics of shock absorbers is built.The nonlinear characteristics are modeled by algebraic function and the hysteresis effects between shock force and shock velocity are modeled by neural network.To develop the empirical hybrid shock absorber model,a Mazda CX-7 front shock absorber is tested by a displacement-controlled hydraulic shock absorber testing machine.The hybrid shock absorber model is built and validated using the experimental shock absorber data.The RMS value for the hybrid shock absorber model is 60.28N at the velocity range from-1.3m/s to 1.3m/s.

Propagation of Light in an Ensemble of Tripod Level Atoms

We study the propagation of a quantum probe light in an ensemble of tripod level atoms when the atoms are coupled to two other classical control fields. First we calculate the dispersion properties, such as susceptibility and group velocity, of the probe light within such an atomic medium under the case of three-photon resonance via the dynamical algebra method of collective atomic excitations. Then we calculate the dispersion of the probe light in the case that two classical control fieMs have the different detunings to the relative atomic transitions. Our results show that in both cases the phenomenon of electromagnetically induced transparency can occur. Especially under the second case, we can find two transparency windows for the probe light.

Transcranial magnetic stimulation probes the excitability of the primary motor cortex:A framework to account for the facilitating effects of acute whole-body exercise on motor processes

The effects of exercise on decision-making performance have been studied using a wide variety of cognitive tasks and exercise interventions. Although the current literature supports a beneficial influence of acute exercise on cognitive performance, the mechanisms underlying this phenomenon have not yet been elucidated. We review studies that used single-pulse transcranial magnetic stimulation （TMS） to probe the excitability of motor structures during whole-body exercise and present a framework to account for the facilitating effects of acute exercise on motor processes. Recent results suggest that, even in the absence of fatigue, the increase in corticospinal excitability classically reported during submaximal and exhausting exercises may be accompanied by a reduction in intracortical inhibition. We propose that reduced intracortical inhibition elicits an adaptive central mechanism that counteracts the progressive reduction in muscle responsiveness caused by peripheral fatigue. Such a reduction would render the motor cortex more sensitive to upstream influences, thus causing increased corticospinal excitability. Furthermore, reduction of intracortical inhibition may account for the more efficient descending drive and for the improvement of reaction time performance during exercise. The adaptive modulation in intracortical inhibition could be implemented through a general increase in reticular activation that would further account for enhanced sensory sensitivity.

Trigeminal Ganglioneuroma in the Middle-posterior Cranial Fossa： a Case Report

GANGLIONEUROMA is considered as the most mature and noninvasive form of neuroblastic tumors. It derives from neural crest cells, and can arise from wherever sympathetic tissue exists, including neck, posterior mediastinum, adrenal gland, retroperitoneum and pelvis. The two most common locations for this tumor are retroperitoneum and posterior mediastinum; infrequently it occurs in the intracranial re-gion,2-8 with only three cases has been reported arising from trigeminal nerve.2-4 The current paper presents a 49-year-old male patient with a ganglioneuroma arising from right trigeminal ganglion and extending to the mid-dle-posterior cranial fossa. We summarized the clinical and diagnostic characteristics of this extremely rare tumor, in comparison with the three reported cases in literatures.

Simultaneous large cell neuroendocrine carcinoma and adenocarcinoma of the stomach

A large cell neuroendocrine carcinoma(LCNEC) of the stomach is very rare.A 76-year-old Japanese man was admitted to our hospital because of epigastralgia and nausea.Endoscopy revealed 2 large tumors in the stomach.He did not have multiple endocrine neoplasia typeⅠor Zollinger-Ellison syndrome.Imaging modalities,including computed tomography and magnetic resonance imaging,revealed no other tumors.Gastrectomy,cholecystectomy,and lymph node dissection were performed.The resected stomach had 2 tumors:one was an antral ulcerated type 3 tumor measuring 5 cm x 5 cm,and the other was a polypoid type 1 tumor measuring 6 cm x 6 cm x 3 cm in the fundus.Microscopically,the antral ulcerated tumor was a well differentiated adenocarcinoma with deep invasion.The fundus polypoid tumor was a LCNEC,being composed of malignant large cells arranged in trabecular and nested patterns.The tumor cells were large and the nuclei were vesicular.Nucleoli were frequently present,and there were many mitotic figures,apoptotic bodies,and necrotic areas.Much lymphovascular permeation was seen.Seven out of 29 dissected lymph nodes showed metastatic foci;6 were from the LCNEC and 1 from theadenocarcinoma.Many intravascular tumor emboli of LCNEC were seen in the peritoneum around the lymph nodes.Mucins were present in the adenocarcinoma but not in the LCNEC.Immunohistochemically,the LCNEC tumor cells were positive for pancytokeratins,synaptophysin(50%positive) ,chromogranin A(10% positive) ,Ki-67(90%labeled) ,and platelet-derived growth factor-α(80%positive) .They were negative for KIT,p53,CD56,and neuron-specific enolase.The non-cancerous stomach showed a normal number of endocrine cells.The patient is now treated with adjuvant chemotherapy.

Modeling of Large ELM Suppressions for High Confinement Plasma in D Ⅲ-D

The H-mode discharges with high edge pressure gradients are expected for the economic feasibility of future fusion reactors. However, the high edge pressure gradients easily produce ELM instability , which generally can expel large, heat and particle loading to the divertor targets. These ELMs limit the core plasma performance and reduce the lifetime of divertor target plates. The transports of heat and particles outward across plasma boundary are useful to control density and impurity profiles for achieving steady state, high performance plasmas. Consequently, any technique to eliminate or mitigate large fast ELM impulses must replace the transient heat and particle transports with another slow process. Such a technique is high priority for a burning plasma device such as ITER.

Effect of electroacupuncture combined with repetitive transcranial magnetic stimulation on limb dysfunction in patients with ischemic stroke

(rTMS) on limb dysfunction in ischemic stroke patients. Methods: A total of 63 stroke patients were divided into an observation group and a control group using the random number table method. Thirty-one patients in the control group were treated with routine Western medicine combined with rTMS;32 patients in the observation group were treated with EA in addition to the intervention in the control group. The duration of treatment was 3 months. The National Institutes of Health stroke scale (NIHSS), the Fugl-Meyer assessment (FMA), the modified Barthel index (MBI), and the motor evoked potential (MEP) latency of transcranial magnetic stimulation were observed before and after treatment in both groups. Results: Two cases withdrew from the observation group and 1 case withdrew from the control group. After treatment, the NIHSS score in both groups was lower than that before treatment, the FMA and MBI scores were higher than those before treatment, and the latency period of MEP was shorter than that before treatment, and the differences were statistically significant (P<0.05). After treatment, the NIHSS, FMA, and MBI scores and MEP latency period of the observation group improved more than those of the control group, and the differences between the groups were statistically significant (P<0.05). Conclusion: EA combined with rTMS can improve the motor function of limbs in ischemic stroke patients and improve their self-care ability. The mechanism may be related to increasing the excitability of the motor cortex and improving the electrophysiological function of the central nervous system.

Study on the Relation Between MRI Findings and Acupuncture Effect in Trigeminal Neuralgia Patients

Objective： To observe the relationship between acupuncture and MRI （Magnetic Resonance Imaging） findings in patients with trigeminal neuralgia （TN）. Methods： A total of 32 idiopathic TN patients who completed acupuncture treatment protocol were recruited in this trial. The relationship between acupuncture effect and MRI findings were analyzed by using MRI-B-FFE （Balanced Fast Field Echo） technique to record MRI information, such as the distance from the brainstem to the contact point of offending vessels and trigeminal nerve, the contact angle of offending vessels and trigeminal nerve, and the ratio of the diameter of the contact vessel to trigeminal nerve width. Results： After acupuncture treatment, 9 cases got marked effect, 19 got improvement, and 4 got no effect. Acupuncture effect was neither associated with the distance from the brainstem to the contact point of the offending vessel and trigeminai nerve （P〉0.05） nor the ratio of the diameter of the offending vessel to trigeminal nerve width （P〉0.05）; however, it was indeed associated with the running course of the offending vessels （P〈0.05）. Conclusion： The bigger the angle between the offending vessels and trigeminal nerve, the poorer the acupuncture effect. The B-FFE technique can be used for screening acupuncture-indicated TN patients.

Characteristics of the induced voltage between deep brain stimulation(DBS) device electrodes by a transcranial magnetic stimulation(TMS) device

The combination of deep brain stimulation(DBS) and transcranial magnetic stimulation(TMS) is expected to provide additional insights into the pathophysiology of some brain diseases. However, when using TMS in patients with DBS implants, the induced voltage between DBS electrodes presents the greatest risk of brain damage. This paper describes the characteristics of the induced DBS electrode voltage due to TMS. We first examined the TMS stimulus signal and the DBS output impedance characteristics, and then experimentally investigated the induced DBS electrode voltage for various DBS and TMS conditions. The results show that many factors impact the induced electrode voltage. The induced electrode voltage with DBS device working in the unipolar mode is greater than that with DBS device working in the bipolar mode. No matter DBS device is turned on or turned off, the induced electrode voltage is almost the same, but it can provide a significant addition to the original stimulus waveform. There are no significant differences in the induced DBS electrode voltage when the DBS system is working at different stimulus intensities. Lowering the TMS stimulus intensity could effectively reduce the induced DBS electrode voltage. The induced electrode voltage is also strongly related to the position of the TMS coil relative to the DBS lead. This study provides further information about the characteristics of the induced DBS electrode voltage in TMS applications and a reference for the combined use of DBS and TMS.

Martian magnetic field properties before the termination of its core dynamo

Observed Martian crustal magnetism shows that the Mars does not possess a global-scale,dynamo-driven intrinsic magnetic field.In addition,the remnant field at the surface is hemi-spherically asymmetric.Our earlier simulation results suggest that the Martian dynamo could be sub-critical near its end(the energy required to sustain a subcritical dynamo is less than that to excite the dynamo)and the generated field morphology is non-dipolar.We further the study to examine the characteristics of the magnetic field via Empirical Orthogonal Function(EOF)analysis on the subcritical dynamo solutions with the Rayleigh number Rth = 2480(below the critical point for the onset of the Martian dynamo).Our results show that the magnetic field is dominantly equatorial dipolar.Reversals and excursions occur frequently,and the magnetic dipole moment does not vary monotonically in time.