Purpose: To evaluate the tracing of optic nerve tract using manganese enhanced magnetic resonance imaging. Materials and Methods: After injecting 30 microliter of MnCl2 (1 mol) into the retina of female New Zealand white rabbit, the contrast enhancements at major anatomical structures of optic nerve tract were evaluated by high resolution T1-weighted images 12 hours, 24 hours, and 48 hours after MnCl2 injection using 3D FSPGR (Fast Spoiled Gradient Recalled echo) pulse sequence at 1.5 T clinical MR scanner with high performance gradient system. Also, for quantitative evaluation, the signal-to-noise ratios of circular ROI on anatomical locations were measured. Results: The major structures on the optic nerve tract were enhanced after injecting MnCl2. The structures, which showed enhancement, were right optic nerve, optic chiasm, left optic tract, left lateral geniculate nucleus, left superior colliculus. The structures on the contralateral optic pathway to the right retina were enhanced whereas the structures on the ipsilateral pathway did not show enhancement. Conclusion: The Mn transport through axonal pathway of optic nerve system was non-invasively observed after injecting MnCl2 at the retina, which is the end terminal of optic nerve system. This Mn transport seems to occur by voltage gated calcium (Ca2+) channel and in case of direct injection into the retina, the fast transport pathway of voltage gated calcium channel seems to be responsible for Mn transport.
Axons ; Calcium ; Calcium Channels ; Evaluation Studies as Topic ; Female ; Humans ; Magnetic Resonance Imaging ; Manganese ; New Zealand ; Optic Chiasm ; Optic Nerve ; Retina ; Signal-To-Noise Ratio ; Superior Colliculi ; Visual Pathways*

PURPOSE: To separate and evaluate the low frequency spontaneous fluctuation BOLD signals from the functional magnetic resonance imaging data using sensorimotor active task. MATERIALS AND METHODS: Twenty female archery players and twenty three control subjects were included in this study. Finger-tapping task consisted of three cycles of right finger tapping, with a subsequent 30 second rest. Blood oxygenation level-dependent (BOLD) data were collected using T2*-weighted echo planar imaging at a 3.0 T scanner. A 3-D FSPGR T1-weighted images were used for structural reference. Image processing and statistical analyses were performed using SPM5 for active finger-tapping task and GIFT program was used for statistical analyses of low frequency spontaneous fluctuation BOLD signal. RESULTS: Both groups showed the activation in the left primary motor cortex and supplemental motor area and in the right cerebellum for right finger-tapping task. ICA analysis using GIFT revealed independent components corresponding to contralateral and ipsilateral sensorimotor network and cognitive-related neural network. CONCLUSION: The current study demonstrated that the low frequency spontaneous fluctuation BOLD signals can be separated from the fMRI data using finger tapping paradigm. Also, it was found that these independent components correspond to spontaneous and coherent neural activity in the primary sensorimotor network and in the motor-cognitive network.
Cerebellum ; Echo-Planar Imaging ; Female ; Fingers ; Humans ; Magnetic Resonance Imaging ; Motor Cortex ; Oxygen

Fear memory recruits various brain regions with long-lasting brain-wide subcellular events. The medial prefrontal cortex processes the emotional and cognitive functions required for adequately handling fear memory. Several studies have indicated that subdivisions within the medial prefrontal cortex, namely the prelimbic, infralimbic, and anterior cingulate cortices, may play different roles across fear memory states. Through a dedicated cytoarchitecture and connectivity, the three different regions of the medial prefrontal cortex play a specific role in maintaining and extinguishing fear memory. Furthermore, synaptic plasticity and maturation of neural circuits within the medial prefrontal cortex suggest that remote memories undergo structural and functional reorganization. Finally, recent technical advances have enabled genetic access to transiently activated neuronal ensembles within these regions, suggesting that memory trace cells in these regions may preferentially contribute to processing specific fear memory. We reviewed recently published reports and summarize the molecular, synaptic and cellular events occurring within the medial prefrontal cortex during various memory stages.

No abstract available.
Animals ; Brain* ; Cats* ; Magnetic Resonance Spectroscopy*

Gadolinium contrast agents (CAs) are integral components of clinical magnetic resonance imaging (MRI). However, safety concerns have arisen regarding the use of gadolinium CAs, due to their association with nephrogenic systemic fibrosis (NSF). Furthermore, recently the long-term retention of Gd²⁺-based CAs in brains patients with normal renal function raised another possible safety issue. The safety concerns of Gd²⁺-based CAs have been based on the ligand structure of Gd²⁺-based CAs, and findings that Gd²⁺-based CAs with linear ligand structures showed much higher incidences of NSF and brain retention of CAs than Gd²⁺-based CAs with macrocyclic ligand structure. In the current study, we report the in vivo biodistribution profile of a new highly stable multifunctional Gd²⁺-based CA, with macrocyclic ligand structure (HNP-2006). MR imaging using HNP-2006 demonstrated a significant contrast enhancement in many different organs. Furthermore, the contrast enhanced tumor imaging using HNP-2006 confirmed that this new macrocyclic CA can be used for detecting tumor in the central nervous system. Therefore, this new multifunctional HNP-2006 with macrocyclic ligand structure shows great promise for whole-body clinical application.
Brain ; Central Nervous System ; Contrast Media ; Gadolinium ; Humans ; Incidence ; Magnetic Resonance Imaging ; Nephrogenic Fibrosing Dermopathy

The aim of this study is to investigate the mechanism of motor recovery using both functional Magnetic Resonance Imaging (fMRI) and Transcranial Magnetic Stimulation (TMS) in a patient with hemorrhagic contusion on the right basal ganglia area. Functional MRI showed that the left primary sensorimotor cortex and the supplementary motor area were activated when the right fingers performed the flexion-extension exercise. On the other hand, the bilateral primary sensorimotor cortex and the left premotor area were activated with the excerise of left hand. Brain mapping for both abductor pollicis brevis muscles (APB) using TMS revealed that ipsilateral motor evoked potentials (MEPs) were obtained at left APB. Ipsilateral MEPs of left APB showed delayed latency and lower amplitude compared to that of right APB when stimulated at the left motor cortex. We concluded that ipsilateral motor pathway from undamaged motor cortex seems to contribute to the motor recovery in this patient and combining TMS with fMRI may provide a powerful tool for investigating the mechanism of motor recovery.
Basal Ganglia ; Brain Injuries* ; Brain Mapping* ; Brain* ; Contusions ; Evoked Potentials, Motor ; Fingers ; Hand ; Humans ; Magnetic Resonance Imaging ; Motor Cortex ; Muscles ; Transcranial Magnetic Stimulation

PURPOSE: To measure the NMR relaxation properties of MnPC, to observe the characteristics of liver enhancement patterns on MR images in experimentally implanted rabbit VX2 tumor model, and to estimate the possibility of tissue specific contrast agent for MnPC in comparison with the hepatobiliary agent. MATERIALS AND METHODS: Phthalocyanine (PC) was chelated with paramagnetic ions, manganese (Mn). 2.01 g (5.2 mmol) of phthalocyanine was mixed with 0.37 g (1.4 mmol) of Mn chloride at 310 degrees C for 36 hours and then purified by chromatography (CHCl3:CH3 OH=98:2, volume ratio) to obtain 1.04 g (46%) of MnPC (molecular weight=2000 daltons). The T1/T2 relaxivity (R1/R2) for MnPC were determined at a 1.5 T (64 MHz) MR spectrometer. VX2 tumor model was experimentally implanted in the liver parenchyma of rabbits. All MR studies were performed on 1.5 T. The human extremity radio frequency coil of a bird cage type was employed. MR images were acquired at 17 to 24 days after VX2 carcinoma implantation. 4 mmol/kg MnPC and 0.01 mmol/kg Mn-DPDP were injected via the ear vein of rabbits. T1-weighted images were obtained with spin-echo (TR/TE=516/14 msec) and fast multiplanar spoiled gradient recalled (TR/TE=80/4 msec, 60 degree flip angle) pulse sequence. Fast spin-echo (TR/TE=1200/85 msec) was used to obtain the T2-weighted images. RESULTS: The value of T1/T2 relaxivity (R1/R2) of MnPC was 7.28 mM-1S-1 and 55.56 mM-1S-1 respectively at 1.5 T (64 MHz). Because the T2 relaxivity of MnPC that bonded strongly, covalently manganese with phthalocyanine was very high, the signal intensity of liver parenchyma was decreased on postcontrast T2-weighted images and we could easily distinguish the VX2 carcinoma within the liver parenchyma. When MnPC was administrated intravenously, the tumor margin delineation was more remarkable than Mn-DPDP-enhanced images. The enhancement of liver parenchyma with MnPC persisted at relatively high levels over at least one hour after injection of the contrast agents. CONCLUSION: The hepatic uptake and biliary excretion of MnPC, which are similar to Mn-DPDP, suggest that this agent is a new liver-specific agent. Also, MnPC seems to Introduction be used as a dual contrast agent (T1 and T2) with high T2 relaxivity. However, it is warranted that MnPC needs further investigation as a potential contrast agent for MR imaging of the liver. That is, further characterizations of MnPC are needed in vivo and in vitro before clinical trials. The diagnostic potential of MnPC will also have to be examined more in the animal models of additional types.
Animals* ; Birds ; Chromatography ; Contrast Media ; Ear ; Extremities ; Humans ; Ions ; Liver ; Magnetic Resonance Imaging ; Manganese ; Models, Animal* ; Rabbits ; Relaxation ; Veins

PURPOSE: To determine the electronic spin relaxation times, T1e, of three commercially available Gd-chelated MR contrast agents, Gd-DTPA, Gd-DTPA-BMA and Gd-DOTA, using Electron Paramagnetic Resonance(EPR) technique. Material and Methods: The paramagnetic MR contrast agents, Gd-DTPA(Magnevist), Gd-DTPA-BMA(OMNISCAN) and Gd-DOTA(Dotarem), were used for this study. The EPR spectra of these contrast agents, which were prepared 2:1 methanol/water solution, were obtained at low temperatures, from-160degrees C~-20degrees C. The glassy-state EPR spectra for these contrast agents were then fitted by the simulation spectra generated with different zero-field splitting (ZFS) parameters by a computer simulation program 'GE N', which generates the EPR powder spectrum using a given ZFS in 3X3 tensor. Finally, the spin relaxation times of the contrast agents were then determined from the T2e, D, and E values of the best simulation spectra using the McLachlan's theory of average relaxation rate. Results: The electronic transverse spin relaxation times, T2e's, of Gd-DTPA, Gd-DTPA-BMA and Gd-DOTA were 0.113ns, 0.147ns and 1.81ns respectively. The g-values were 1.9737, 1.9735 and 1.9830 and the electronic spin relaxation times, T1e's, were 18.70ns, 33.40ns and 1.66micros, respectively. Conclusion: The results of these studies reconfirm that the paramagnetic MR contrast agents with larger ZFS parameters should have shorter T1e's. Among three contrast agents used for this study, Gd-DOTA chelated with cyclic ligand structure shows better electronic property then the others with linear structure. Thus, it is concluded that the exact determination of ZFS parameters is the important factor in evaluating relaxation enhancement effect of the agents and in developing new contrast agents.
Computer Simulation ; Contrast Media* ; Gadolinium DTPA ; Magnetic Resonance Imaging* ; Relaxation*

Functional magnetic resonance imaging (fMRI) was used to assess the temporal response of neural activation in healthy subjects while they performed the Iowa Gambling Test (IGT), which utilizes decisions involving ambiguity and risk. The IGT was divided into five blocks of 20 trials; analysis showed that activity in the medial prefrontal cortex (mPFC) moves gradually from the dorsal to the ventral mPFC over the course of the IGT. These findings suggest that cognitive division of the mPFC, including the dorsal portion of the anterior cingulated cortex (ACC), plays a major role in ambiguous decision making and that the aspect of the IGT corresponding to risky decision making is associated with significant activity within the corticolimbic network strongly implicated in emotion and reinforcement. Our results also suggest that decisions made under ambiguity and decisions made under risk situations can be further divided into sub-phases based on the neural network involved.
Decision Making ; Gambling ; Iowa ; Magnetic Resonance Imaging ; Prefrontal Cortex ; Reinforcement (Psychology)

Objectives: The aim of this study was to evaluate brain activity in youth during chewing gum and wood stick using functional magnetic resonance imaging (fMRI). Methods: Two participants chewed wax gums and wood stick on the rhythm of 1 Hz during MRI scanning. The task paradigm was a block design and each chewing-rest procedure was repeated five times for 30s. Results: The brain regions activated during chewing gum and wood stick were the precentral gyrus, postcentral gyrus, supplementary motor area, thalamus cerebellum. The medial prefrontal cortex (mPFC), anterior cingulate cortex (ACC), hippocampus, and precuneus were additionally activated by mastication of the wood stick. Brain activation induced by chewing wood stick was higher than chewing gum. Conclusions Our results suggest that mastication contribute to cognitive improvement through brain activity, this effect is stronger during chewing wood than gum. Therefore, eating harder foods may improve cognitive function more effectively.