Parcel-guided rTMS for depression.

Transcranial magnetic stimulation (TMS) is an approved intervention for treatment-resistant depression (TRD), but current targeting approaches are only partially successful. Our objectives were (1) to examine the feasibility of MRI-guided TMS in the clinical setting using a recently published surface-based, multimodal parcellation in patients with TRD who failed standard TMS (sdTMS); (2) to examine the neurobiological mechanisms and clinical outcomes underlying MRI-guided TMS compared to that of sdTMS. We used parcel-guided TMS (pgTMS) to target the left dorsolateral prefrontal cortex parcel 46. Resting-state functional connectivity (rsfc) was assessed between parcel 46 and predefined nodes within the default mode and visual networks, following both pgTMS and sdTMS. All patients (n = 10) who had previously failed sdTMS responded to pgTMS. Alterations in rsfc between frontal, default mode, and visual networks differed significantly over time between groups. Improvements in symptoms correlated with alterations in rsfc within each treatment group. The outcome of our study supports the feasibility of pgTMS within the clinical setting. Future prospective, double-blind studies of pgTMS vs. sdTMS appear warranted.

Resting state functional connectivity predictors of treatment response to electroconvulsive therapy in depression.

There is increasing focus on use of resting-state functional connectivity (RSFC) analyses to subtype depression and to predict treatment response. To date, identification of RSFC patterns associated with response to electroconvulsive therapy (ECT) remain limited, and focused on interactions between dorsal prefrontal and regions of the limbic or default-mode networks. Deficits in visual processing are reported in depression, however, RSFC with or within the visual network have not been explored in recent models of depression. Here, we support prior studies showing in a sample of 18 patients with depression that connectivity between dorsal prefrontal and regions of the limbic and default-mode networks serves as a significant predictor. In addition, however, we demonstrate that including visual connectivity measures greatly increases predictive power of the RSFC algorithm (>80% accuracy of remission). These exploratory results encourage further investigation into visual dysfunction in depression, and use of RSFC algorithms incorporating the visual network in prediction of response to both ECT and transcranial magnetic stimulation (TMS), offering a new framework for the development of RSFC-guided TMS interventions in depression.

Compressed sensing MRI combined with SENSE in partial k-space.

Compressed sensing (CS), parallel imaging and partial Fourier (PF) acquisition are all effective methods to reduce k-space sampling and therefore accelerate MR acquisition. The combined use of these methods gives us more options to balance the needs for scan speed and image quality. We conducted simulations on full k-space data to demonstrate the potential use of combining CS-SENSE with PF acquisition in anatomical MRIs of the human brain. To test the accelerated acquisition of high-resolution T1-weighted images of brain, we modified a 3D FSPGR sequence on a GE 3T scanner to implement different undersampling schemes based on CS, including partial Fourier CS-SENSE. Partially sampled k-space data were acquired and then reconstructed to brain images. CS-SENSE combined with PF sampling is able to provide better reconstructed images than CS only, or than CS-SENSE without PF for the same total acceleration. Combining PF sampling with CS-SENSE enables us to further accelerate image acquisition or improve image quality while holding the acceleration rate constant.

Cerebral cortical lesions in multiple sclerosis detected by MR imaging at 8 Tesla.

BACKGROUND AND PURPOSE: Conventional imaging of ex-vivo brain at 1.5T in multiple sclerosis (MS) detects only a small fraction of the gray matter cerebral cortical lesions that can be detected by pathology. Our purpose was to examine if imaging at 8T can detect plaques in cortical gray matter (CGM) not evident at 1.5T. METHODS: An ex-vivo brain obtained at autopsy from a patient with MS was formalin fixed and 1 cm coronal slices were examined using MR imaging at 8T. RESULTS: Numerous cerebral cortical lesions not evident at 1.5T were seen at 8T. Lesions were easily identified using gradient-echo and spin-echo (SE) as well as diffusion images. MR imaging at 8T identified many of the types of plaques previously evident only by pathology. The magnitude of the cortical involvement in this 1 patient was severe. Lesions in the gray matter readily visible by high-field MR imaging were sometimes barely visible by pathology. MR imaging at 8T often facilitated the detection of such plaques by pathology. CONCLUSION: This study establishes the utility of high-field imaging at 8T in the delineation of plaques in the cerebral CGM in MS.

Magnetic resonance imaging characterization of osteochondral defect repair in a goat model at 8 T.

OBJECTIVE: This study was performed to non-invasively visualize and characterize osteochondral (OC) repair in ex vivo goat stifles using an 8 T magnetic resonance imaging (MRI) scanner and to compare the MR morphology with images obtained from 1.5 T, gross morphology and histology. METHODS: Mature, neutered male goats were assigned to an 8-week (n = 4) or 16-week (n = 4) study period. Two cylindrical OC defects (7 mm diameter, full cartilage thickness and 1mm into subchondral bone) were surgically created in the right stifle: one in the medial femoral condyle (MFC) and the other in the trochlear groove (TG). The implant matrices (non-woven or foam) were secured in the defect using a bottom anchored fixation device (FD). The contralateral left stifles served as time zero controls. At the day of necropsy, implants were placed at both defect sites (MFC and TG) on the normal left stifles. Following necropsy, the ex vivo goat stifles (intact and encapsulated) were disarticulated. Within 24 h postnecropsy, MR scans of the stifles along the mid-sagittal plane of the OC defect were acquired at 8 T and 1.5 T. MR relaxation times, T1 and T2, were measured at the region of repair tissue (RT) and adjacent native cartilage. Immediately after MR imaging, the stifles were dissected, grossly examined, and a sagittal OC block corresponding to the MR region of interest was prepared for formalin fixation. RESULTS: The high-resolution MR images enabled visualization of cartilage and bone integrity surrounding the implant as well as delineating the margins of RT/implant matrix and the FD. On spin echo sequence, the RT variably appeared as high, intermediate or low MR signal intensity; whereas, the FD always appeared as low signal intensity. In general, the MR signal intensity of 8-week RT was slightly higher compared to 16-week RT; however, there was no difference in RT morphology of stifles implanted with the non-woven matrix or foam matrix. Subchondral sclerosis appeared as low signal intensity. The 8 T MR images showed better delineation of the stifle tissues compared to the images acquired at 1.5 T. The T2 relaxation time of the RT appears to indicate (inconclusive due to small number of samples) a slight variation in the RT type between 8 weeks and 16 weeks. At both study times, the defects grossly appeared whitish to reddish but did not have the characteristic hyaline appearance typical of articular cartilage (AC). The gross appearance of the MFC and TG RT differed, which was predominantly mottled and recessed with fissuring of adjacent native AC in the MFC. Histologically, the RT of both 8-week and 16-week postsurgical defects predominantly comprised fibrovascular connective tissue with only few samples showing the presence of fibrocartilaginous and/or hypertrophic chondrocytes within the defect RT at 8 weeks. Also, compared to 8-week, the 16-week RT appeared to be more fibrotic. CONCLUSION: Using 8 T scanner, high-resolution MR images of ex vivo encapsulated goat stifles confirmed the capability of high-field MR imaging to distinguish the defect RT from the FD and adjacent joint tissues. The extent of OC repair and adjacent bone lesions (at 8 weeks and 16 weeks) observed in the MR images compared well with those observed on the corresponding histological sections.

[Clinical high- and ultrahigh-field MR and its interaction with biological systems]. / Klinische Hoch- und Ultrahochfeld-MR und ihre Wechselwirkung mit biologischen Systemen.

The field strength of the static field in MRI has increased from 0.015 to 12 Tesla (T) during the last 25 years, which is about an 800 fold increase. In addition to low- and high field systems (1.5-4 T), ultra-high field systems with field strengths above 4 T are now available for human MRI. The extension of non-significant risk status for clinical fields up to 8 T by the FDA in July 2003 facilitates the further growth of this technology. The increase in field strength creates the need for a better understanding of the safety challenges to ensure safety for human imaging applications. This encompasses understanding the effects of the strong magnetic field at the atomic and molecular level and from biological tissue to organ systems. Moreover, in addition to the effects of a static magnetic field, the effects of radio-frequency- and gradient-fields have to be considered. This paper reviews the safety relevant issues for high- and ultrahigh field MR.

Computational modeling of cerebral diffusion-application to stroke imaging.

Water diffusion within the structure of a brain extracellular space is analyzed numerically for various diffusion parameters of brain tissue namely extracellular space porosity and tortuosity. An algorithm for predicting diffusion pattern of water molecules within human brain considering the mechanics of water diffusion within porous media is developed. The extracellular space is modeled as a homogeneous porous medium with uniform porosity and permeability. Discretization of the fluid flow, heat transfer and mass transport equations is achieved using a finite element scheme based on the Galerkin method of weighted residuals. Concentration maps are developed in this study for various clinical conditions. The effect of the space porosity and the turtousity on the heat and mass transport within the extracellular space are found to be significant. The results presented in this work play an important role in producing more effective imaging techniques for brain injury based on the apparent diffusion coefficient.

Water diffusion in biomedical systems as related to magnetic resonance imaging.

Water diffusion within the brain is studied numerically for various clinical conditions. The numerical procedure used in this work is based on the Galerkin weighted residual method of finite-element formulation. A wide range of pertinent parameters such as Lewis number, cell volume, and the buoyancy ratio are considered in the present study. Comparisons with previously published work show excellent agreement. The results show that the diffusion coefficient, cell volume, and the buoyancy ratio play significant roles on the characterization of the mass and heat transfer mechanisms within the cell. Concentration maps are developed for various clinical conditions. Pertinent results for the streamlines, isotherms and the mass and heat transfer rates in terms of the average Sherwood and Nusselt numbers are presented and discussed for different parametric values. Experimental tests are also conducted to produce an 8 Tesla image which is compared with our numerical simulation. The present study provides essential maps for brain disorders classified based on several pertinent clinical attributes.

Intracranial ossifications and microangiopathy at 8 Tesla MRI.

UNLABELLED: Clinical evaluation and MR imaging of microangiopathy associated with hypertension is limited. We describe a case that illustrates sensitivity of MRI at 8 Tesla for imaging of microvasculature, iron, calcium deposits and silent white matter lesions (WML). A 60-year-old black hypertensive woman was evaluated for numbness in the face and extremities. MRI at 1.5 Tesla was unrevealing.MRI at 8 Tesla: Axial and sagittal Gradient Echo images were obtained with an 8T/80 cm human scanner and showed: 1) Large areas of signal voids due to ossifications and fat deposits within the falx. 2) Obstructed small vessels in the periventricular regions and distended cortical veins. 3) Numerous small WML, suggestive of mini-infarcts (<1 cm) and microhemorrhages. 4) Intracranial calcifications in the falx, tentorium, basal ganglia and chorioid plexus that were confirmed by CT scan. Atherosclerotic plaque in right carotid artery and reduced vasomotor reserve in middle cerebral arteries, documented by ultrasound, indicated large and small vessel disease. CONCLUSIONS: MRI at 8 Tesla improves visualization of microangiopathy, ossifications and iron deposits due to enhanced magnetic susceptibility at ultra high magnetic field.

Canine abdominal MRI at 8 Tesla: initial experience with conventional gradient-recalled echo and rapid acquisition with relaxation enhancement (RARE) techniques.

PURPOSE: In this manuscript, we present our initial experience with MRI of the abdomen at 8 T of canine subjects both alive and dead. Our hypothesis is that abdominal imaging at 8 T should be possible and should demonstrate unique information. To our knowledge, this is the first description of imaging characteristics of the abdomen at such field strengths using a human MR scanner. METHOD: An 8 T, 80 cm magnet housed in our department since 1998 was used for our study. GRE and rapid acquisition by relaxation enhancement (RARE) pulse sequences were selected to give reasonable slice profiles with relatively low power. Three dogs were imaged alive and after being killed. RESULTS: Our initial results show excellent signal-to-noise ratio and good RF penetration. Structures in the center of the abdomen were well visualized. Homogeneous signal was noted throughout each image without dielectric resonance artifact. Magnetic susceptibility artifacts were most severe on the GRE sequences. On the GRE sequences, the images appeared relatively T2 weighted. Signal voids were seen due to gas in the lung and bowel and susceptibility artifact at subcutaneous fat-muscle boundaries. The liver and spleen showed similar signal intensity, hypointense to subcutaneous muscle at low TE values. There was little internal anatomy of the liver or spleen visible except for the vessels. The kidney, in contrast, demonstrated very good internal structure with visualization of the cortex and medulla. Linear signal voids were depicted in the expected location of normal renal vascular anatomy on the GRE sequences. On the RARE sequences, the images also appeared T2 weighted. Magnetic susceptibility artifacts at subcutaneous fat-muscle boundaries were absent. Signal voids were noted in vessels with blood flow and gas. The liver and spleen were of similar signal intensity and slightly hypointense to muscle. The kidney and pancreas were of higher signal intensity than liver and subcutaneous muscle. The gallbladder wall demonstrated a striated pattern of two layers, with an inner hypointense and an outer hyperintense layer on the RARE sequence. The gastric wall demonstrated a striated pattern of five layers on the RARE sequence. CONCLUSION: Images of the dog abdomen with the world's first ultra high field 8 T magnet show robust image quality and excellent spatial resolution. Image contrast is greatest on the RARE sequence, and susceptibility artifact is strongest on the GRE sequence.

Ultra high field MRI at 8 Tesla of subacute hemorrhagic stroke.

PURPOSE: Optimal treatment strategies and neurologic outcome after stroke depend on an accurate characterization of the lesion. There is a need for high resolution noninvasive imaging for assessment of the infarct size, perfusion, and vascular territory. MRI at the ultra high field (UHF) of 8 T offers unprecedented resolution, but its utility for stroke evaluation has not been determined yet. METHOD: A 55-year-old man with hypertension experienced sudden onset of speech arrest and right-sided hemiparesis that resolved in < 24 h with minimal neurologic deficit. MRI at 1.5 T showed initially a left posterior frontal lesion with subacute infarct (hyperintense on T2-weighted spin echo images) and right-sided frontal and periventricular lesions consistent with chronic infarct. There were many smaller white matter lesions. Delayed studies showed high signal changes involving the gray matter only on T1-weighted images. RESULTS: Gradient echo and rapid acquisition with relaxation enhancement (RARE) multislice images revealed a serpentine area of low signal in the left posterior frontal lobe gray matter suggestive of a hemorrhagic infarct, right-sided frontal lesion also showing iron deposits, multiple periventricular and cortical areas with abnormal high signal regions that were consistent with old infarcts, and numerous small vessels readily visible, more prominent on the right. CONCLUSION: MRI at 8 T displays lesions with a high resolution and striking anatomic details. Susceptibility to iron and sensitivity to detect blood products are increased at 8 T. The imaging characteristics at high field are different from those at low field, but both represent findings of iron products.

High resolution MRI of the brainstem at 8 T.

A recently developed ultra high field MRI system operating at 8 T (UHFMRI) was applied for brainstem imaging. UHFMRI was performed in five healthy volunteers (three men, two women; age range 34--46 years). Sagittal and axial slices were obtained with the following settings: GE, TR 750--1,000 ms, TE 7-9 ms, FOV 20 cm, matrix 1,024 x 1,024 or 512 x 512 points, slice thickness 2 mm, resolution 195 or 390 microm/pixel. The brainstem structures were assigned based on anatomy and course. Images with good signal strength and homogeneity were acquired from the midbrain and the pons. Main intraaxial structures could be directly visualized. The periaqueductal gray matter and nuclei had higher signal intensity than the predominantly white matter structures such as the corticobulbar/corticopontine/corticospinal tracts, the sensory lemnisci, and the medial longitudinal fasciculus. Structures with high iron content such as the substantia nigra and the red nucleus were seen as prominent signal hypointensities. Numerous vessels traversing the brainstem including small perforators were also distinguished. It is concluded that UHFMRI enables the acquisition of high quality images of the upper brainstem with details approaching that of histologic specimen.

Aneurysm clips: evaluation of magnetic field interactions with an 8.0 T MR system.

This study was conducted to evaluate magnetic field interactions for aneurysm clips exposed to an 8.0 T magnetic resonance (MR) system. Twenty-six different aneurysm clips were tested for magnetic field translational attraction (deflection angle test) and torque (qualitative assessment method) using previously described techniques. Six of the specific aneurysm clips (i.e. type, model, blade length) made from stainless steel alloy (Perneczky) and Phynox (Yasargil, models FE 748 and FE 750) displayed deflection angles above 45 degrees and torque measurements of +4, indicating that these aneurysm clips maybe unsafe for patients or individuals in an 8.0 T MR environment. The specific aneurysm clips (i.e. type, model, blade length) made from commercially pure titanium (Spetzler), Elgiloy (Sugita), titanium alloy (Yasargil, model FE 750T), and MP35N (Sundt) displayed deflection angles less than 45 degrees and torque that ranged from + 1 to +4. Accordingly, these aneurysm clips are likely to be safe for patients or individuals exposed to an 8.0 T MR system. Depending on the actual dimensions and mass, an aneurysm clip made from Elgiloy may or may not be acceptable for a patient or individual in the 8.0 T MR environment.

Application of finite difference time domain method for the design of birdcage RF head coils using multi-port excitations.

A three-dimensional finite difference time domain model was developed where the high pass birdcage coil and the imaged object are analysed as a single unit. A study was performed comparing linear, conventional quadrature, and four-port excitation at 64 MHz and 200 MHz for different coil loadings, namely muscle phantoms and an anatomically detailed human head model. A phase array concept was utilized to excite the birdcage coil in four ports. Two phase conditions were analyzed, the simple fixed phase and the variable phase. At 200 MHz, compared to the conventional quadrature drive, the four-port drive reduces the effects of the tissue-coil interactions leading to more uniform currents on the coil legs and consequently to a better B(1) field homogeneity. Also at 200 MHz, driving the coil in four ports provides an SAR distribution with peak values that are significantly less than those with linear or quadrature excitations.

Theoretical model for an MRI radio frequency resonator.

A theoretical model is described for a magnetic resonance imaging (MRI) radio-frequency resonator (an MRI "coil") that is useful at ultrahigh frequencies. The device is a "TEM resonator," which is based on a concept originally proposed by Röschmann (1988). The coil comprises a circular cavity-like structure containing several coaxial transmission lines operating in a transverse electromagnetic (TEM) mode. The model developed herein treats the empty coil and is based on multiconductor transmission line theory. This work generalizes and extends similar analyses of the device by Röschmann (1995) and Chingas and Zhang (1996). The model employs explicit calculation of per-unit-length parameters for TEM lines having arbitrary geometries. Calculations of the resonator's frequency response are found to compare well with measurements. Fields produced by linear (single-point) and quadrature drive are also computed and compared to images of low-permittivity phantoms.

Ultra high resolution imaging of the human head at 8 tesla: 2K x 2K for Y2K.

PURPOSE: To acquire ultra high resolution MRI images of the human brain at 8 Tesla within a clinically acceptable time frame. METHOD: Gradient echo images were acquired from the human head of normal subjects using a transverse electromagnetic resonator operating in quadrature and tuned to 340 MHz. In each study, a group of six images was obtained containing a total of 208 MB of unprocessed information. Typical acquisition parameters were as follows: matrix = 2,000 x 2,000, field of view = 20 cm, slice thickness = 2 mm, number of excitations (NEX) = 1, flip angle = 45 degrees, TR = 750 ms, TE = 17 ms, receiver bandwidth = 69.4 kHz. This resulted in a total scan time of 23 minutes, an in-plane resolution of 100 microm, and a pixel volume of 0.02 mm3. RESULTS: The ultra high resolution images acquired in this study represent more than a 50-fold increase in in-plane resolution relative to conventional 256 x 256 images obtained with a 20 cm field of view and a 5 mm slice thickness. Nonetheless, the ultra high resolution images could be acquired both with adequate image quality and signal to noise. They revealed numerous small venous structures throughout the image plane and provided reasonable delineation between gray and white matter. DISCUSSION: The elevated signal-to-noise ratio observed in ultra high field magnetic resonance imaging can be utilized to acquire images with a level of resolution approaching the histological level under in vivo conditions. However, brain motion is likely to degrade the useful resolution. This situation may be remedied in part with cardiac gating. Nonetheless, these images represent a significant advance in our ability to examine small anatomical features with noninvasive imaging methods.

Dielectric resonance phenomena in ultra high field MRI.

PURPOSE: Dielectric resonances have previously been advanced as a significant cause of image degradation at higher fields. In this work, a study of dielectric resonances in ultra high field MRI is presented to explore the real importance of dielectric resonances in the human brain in this setting. METHOD: Gradient-recalled echo images were acquired using a transverse electromagnetic resonator at 1.5, 4.7, and 8 T. Images were obtained from the human head and from phantoms filled with pure water, saline, and mineral oil. In addition, an exact theoretical analysis of dielectric resonances is presented for a spherical phantom and for a model of the human head. RESULTS: Theoretical results demonstrate that distilled water can sustain dielectric resonances in head-sized spheres near 200 and 360 MHz, but the presence of significant conductivity suppresses these resonances. These findings are confirmed experimentally with proton images of water and saline (0.05 and 0.125 M NaCl). For lossy phantoms, coupling between the source and phantom overwhelms the dielectric resonance. Because of their low relative permittivity, mineral oil phantoms with 20 cm diameter do not exhibit dielectric resonances below approximately 900 MHz. Significant dielectric resonances were not observed in human head images obtained at 1.5, 4.7, and 8 T.

High resolution MRI of the deep brain vascular anatomy at 8 Tesla: susceptibility-based enhancement of the venous structures.

PURPOSE: The purpose of this work was to describe the deep vascular anatomy of the human brain using high resolution MR gradient echo imaging at 8 T. METHOD: Gradient echo images were acquired from the human head using a transverse electromagnetic resonator operating in quadrature and tuned to 340 MHz. Typical acquisition parameters were as follows: matrix = 1,024 x 1,024, flip angle = 45 degrees, TR = 750 ms, TE = 17 ms, FOV = 20 cm, slice thickness = 2 mm. This resulted in an in-plane resolution of approximately 200 microm. Images were analyzed, and vascular structures were identified on the basis of location and course. RESULTS: High resolution ultra high field magnetic resonance imaging (UHFMRI) enabled the visualization of many small vessels deep within the brain. These vessels were typically detected as signal voids, and the majority represented veins. The prevalence of the venous vasculature was attributed largely to the magnetic susceptibility of deoxyhemoglobin. It was possible to identify venous structures expected to measure below 100 microm in size. Perforating venous drainage within the deep gray structures was identified along with their parent vessels. The course of arterial perforators was more difficult to follow and not as readily identified as their venous counterparts. CONCLUSION: The application of high resolution gradient echo methods in UHFMRI provides a unique detailed view of particularly the deep venous vasculature of the human brain.

Design and assembly of an 8 tesla whole-body MR scanner.

PURPOSE: The purpose of this report is to describe the design and construction of an 8 T/80 cm whole-body MRI system operating at 340 MHz. METHOD: The 8 T/80 cm magnet was constructed from 414 km of niobium titanium superconducting wire. The winding of this wire on four aluminum formers resulted in a total inductance of 4,155 H. Gradient subsystems included either a body gradient or a head gradient along with a removable shim insert. The magnet and gradient subsystems were interfaced to two spectrometers. These provided the control of the gradient amplifiers and the two sets of four RF power amplifiers. The latter provide in excess of 8 kW of RF power from 10 to 140 MHz and 10 kW of RF power from 245 to 345 MHz. A dedicated computer-controlled patient table was designed and assembled. The entire system is located in a clinical setting, facilitating patient-based studies. RESULTS: The 8 T/80 cm magnet was energized without complication and achieved persistent operation using 198.9 A of current, thereby storing 81.5 MJ of magnetic energy. Exceptional performance was observed for nearly all components both in isolation and when combined within the complete system. CONCLUSION: An 8 T/80 cm MRI system has been assembled. The magnet subsystem is extremely stable and is characterized by good homogeneity and acceptable boil-off rates.

High resolution MRI of the deep gray nuclei at 8 Tesla.

PURPOSE: High resolution MR images obtained from a normal human volunteer at 8 T are utilized to describe the appearance of iron-containing deep gray nuclei at this field strength. METHOD: High resolution (1,024 x 1,024 matrix) near-axial gradient echo images of the deep gray nuclei were acquired on a human volunteer by using an 8 T scanner. The images were acquired using a transverse electromagnetic resonator operating in quadrature. The following parameters were utilized: TR = 750 ms, TE = 17 ms, flip angle = 45 degrees, receiver bandwidth = 50 kHz, slice thickness = 2 mm, FOV = 20 cm. The 8 T images were reviewed and correlated to the known anatomy of the deep nuclei by comparing them with images observed at lower field strength, published diagrams, and histologic sections. In addition, the appearance of the nuclei was related to the known imaging characteristics of brain iron at lower fields. RESULTS: The caudate, globus pallidus, putamen, thalami, substantia nigra, and red nuclei were clearly identified. The structures with the highest levels of iron, the globus pallidus, substantia nigra, and red nuclei, demonstrated significantly decreased signal, providing a map of iron distribution in the human brain. CONCLUSION: Preliminary imaging at 8 T demonstrates the ability to acquire ultra high resolution images of the deep nuclei, with signal characteristics believed to represent the distribution of brain iron. This may prove to be important in the early diagnosis of several neurodegenerative disorders.