Performance of a miniature high‐temperature superconducting (HTS) surface coil for in vivo microimaging of the mouse in a standard 1.5T clinical whole‐body scanner

The performance of a 12‐mm high‐temperature superconducting (HTS) surface coil for in vivo microimaging of mice in a standard 1.5T clinical whole‐body scanner was investigated. Systematic evaluation of MR image quality was conducted on saline phantoms with various conductivities to derive the sensitivity improvement brought by the HTS coil compared with a similar room‐temperature copper coil. The observed signal‐to‐noise ratio (SNR) was correlated to the loaded quality factor of the radio frequency (RF) coils and is theoretically validated with respect to the noise contribution of the MR acquisition channel. The expected in vivo SNR gain was then extrapolated for different anatomical sites by monitoring the quality factor in situ during animal imaging experiments. Typical SNR gains of 9.8, 9.8, 5.4, and 11.6 were found for brain, knee, back, and subcutaneous implanted tumors, respectively, over a series of mice. Excellent in vivo image quality was demonstrated in 16 min with native voxels down to (59 μm)³ with an SNR of 20. The HTS coil technology opens the way, for the first time at the current field strength of clinical MR scanners, to spatial resolutions below 10^–3 mm³ in living mice, which until now were only accessible to specialized high‐field MR microscopes. Magn Reson Med 60:917–927, 2008. © 2008 Wiley‐Liss, Inc.     

Three‐element phased‐array coil for imaging of rat spinal cord at 7T

To overcome some of the limitations of an implantable coil, including its invasive nature and limited spatial coverage, a three‐element phased‐array coil is described for high‐resolution magnetic resonance imaging (MRI) of rat spinal cord. This coil allows imaging both thoracic and cervical segments of rat spinal cord. In the current design, coupling between the nearest neighbors was minimized by overlapping the coil elements. A simple capacitive network was used for decoupling the next neighbor elements. The dimensions of individual coils in the array were determined based on the signal‐to‐noise ratio (SNR) measurements performed on a phantom with three different surface coils. SNR measurements on a phantom demonstrated higher SNR for the phased array coil relative to two different volume coils. In vivo images acquired on rat spinal cord with our coil demonstrated excellent gray and white matter contrast. To evaluate the performance of the phased array coil under parallel imaging, g‐factor maps were obtained for acceleration factors of 2 and 3. These simulations indicate that parallel imaging with an acceleration factor of 2 would be possible without significant image reconstruction–related noise amplifications. Magn Reson Med 60:1498–1505, 2008. © 2008 Wiley‐Liss, Inc.     

Custom‐fitted 16‐channel bilateral breast coil for bidirectional parallel imaging

A 16‐channel receive‐only, closely fitted array coil is described and tested in vivo for bilateral breast imaging at 3 T. The primary purpose of this coil is to provide high signal‐to‐noise ratio and parallel imaging acceleration in two directions for breast MRI. Circular coil elements (7.5‐cm diameter) were placed on a closed “cup‐shaped” platform, and nearest neighbor coils were decoupled through geometric overlap. Comparisons were made between the 16‐channel custom coil and a commercially available 8‐channel coil. SENSitivity Encoding (SENSE) parallel imaging noise amplification (g‐factor) was evaluated in phantom scans. In healthy volunteers, we compared signal‐to‐noise ratio, parallel imaging in one and two directions, Autocalibrating Reconstruction for Cartesian sampling (ARC) g‐factor, and high spatial resolution imaging. When compared with a commercially available 8‐channel coil, the 16‐channel custom coil shows 3.6× higher mean signal‐to‐noise ratio in the breast and higher quality accelerated images. In patients, the 16‐channel custom coil has facilitated high‐quality, high‐resolution images with bidirectional acceleration of R = 6.3. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.     

Initial feasibility testing of limited field of view magnetic resonance thermometry using a local cardiac radiofrequency coil

The visualization of lesion formation in real time is one potential benefit of carrying out radiofrequency ablation under magnetic resonance (MR) guidance in the treatment of atrial fibrillation. MR thermometry has the potential to detect such lesions. However, performing MR thermometry during cardiac radiofrequency ablation requires high temporal and spatial resolution and a high signal‐to‐noise ratio. In this study, a local MR coil (2‐cm diameter) was developed to investigate the feasibility of performing limited field of view MR thermometry with high accuracy and speed. The local MR coil allowed high‐resolution (1 × 1 × 3 mm³) image acquisitions in 76.3 ms with a field of view 64 × 32 mm² during an open‐chest animal experiment. This represents a 4‐fold image acquisition acceleration and an 18‐fold field of view reduction compared to that achieved using external MR coils. The signal sensitivity achieved using the local coil was over 20 times greater than that achievable using external coils with the same scan parameters. The local coil configuration provided fewer artifacts and sharper and more stable images. These results demonstrate that MR thermometry can be performed in the heart wall and that lesion formation can be observed during radiofrequency ablation procedures in a canine model. Magn Reson Med, 70:994–1004, 2013. © 2012 Wiley Periodicals, Inc.>     

A high‐throughput eight‐channel probe head for murine MRI at 9.4 T

Murine MRI studies are conducted on dedicated MR systems, typically equipped with ultra‐high‐field magnets (≥4.7 T; bore size: ～12–25 cm), using a single transmit‐receive coil (volume or surface coil in linear or quadrature mode) or a transmit‐receive coil combination. Here, we report on the design and characterization of an eight‐channel volume receive‐coil array for murine MRI at 400 MHz. The array was combined with a volume‐transmit coil and integrated into one probe head. Therefore, the animal handling is fully decoupled from the radiofrequency setup. Furthermore, fixed tune and match of the coils and a reduced number of connectors minimized the setup time. Optimized preamplifier design was essential for minimizing the noise coupling between the elements. A comprehensive characterization of transmit volume resonator and receive coil array is provided. The performance of the coil array is compared to a quadrature‐driven birdcage coil with identical sensitive volume. It is shown that the miniature size of the elements resulted in coil noise domination and therefore reduced signal‐to‐noise‐ratio performance in the center compared to the quadrature birdcage. However, it allowed for 3‐fold accelerated imaging of mice in vivo, reducing scan time requirements and thus increasing the number of mice that can be scanned per unit of time. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.     

Non‐invasive visualization of basilar artery perforators with 7T MR angiography

Purpose:

To visualize the perforating arteries originating from basilar artery (BA) by using ultra‐high resolution 7T MR angiography (MRA) and optimizing MR parameters as well as radio frequency (RF) coils, which may provide important information for neurosurgery and understanding diseases of the pons, but was unable to clearly visualize with conventional MRA techniques.

Materials and Methods:

Seven healthy volunteers (five males and two females, age [mean ± SD] = 28.71 ± 7.54 years) were scanned using optimized MR parameters to obtain images of pontine arteries (PAs) originating from the main trunk of BA. Two different volume coils and a phased array coil were designed and compared for this study. The images obtained at 7T MRA were compared with those at 1.5T and 3T MRA.

Results:

The results showed that PA imaging at 7T MRI consistently provided clearly identifiable vessels, which were difficult to visualize in MR angiograms obtained at 1.5T and 3T MRIs. Volume RF coils had higher sensitivity for the center of the brain, which enhanced PA imaging compared to phased array coil. The average number of PA branches in all seven subjects observable by 7T MRA was 7.14 ± 2.79, and the visualized PA branches were found to mainly propagating on the surface of the pons.

Conclusion:

We have demonstrated that ultra‐high resolution 7T MRA could delineate the PAs using optimized imaging parameters and volume RF coils compared to commercially available 1.5T and 3T MRIs. J. Magn. Reson. Imaging 2010;32:544–550. © 2010 Wiley‐Liss, Inc.     

Size‐optimized 32‐channel brain arrays for 3 T pediatric imaging

Size‐optimized 32‐channel receive array coils were developed for five age groups, neonates, 6 months old, 1 year old, 4 years old, and 7 years old, and evaluated for pediatric brain imaging. The array consisted of overlapping circular surface coils laid out on a close‐fitting coil‐former. The two‐section coil former design was obtained from surface contours of aligned three‐dimensional MRI scans of each age group. Signal‐to‐noise ratio and noise amplification for parallel imaging were evaluated and compared to two coils routinely used for pediatric brain imaging; a commercially available 32‐channel adult head coil and a pediatric‐sized birdcage coil. Phantom measurements using the neonate, 6‐month‐old, 1‐year‐old, 4‐year‐old, and 7‐year‐old coils showed signal‐to‐noise ratio increases at all locations within the brain over the comparison coils. Within the brain cortex the five dedicated pediatric arrays increased signal‐to‐noise ratio by up to 3.6‐, 3.0‐, 2.6‐, 2.3‐, and 1.7‐fold, respectively, compared to the 32‐channel adult coil, as well as improved G‐factor maps for accelerated imaging. This study suggests that a size‐tailored approach can provide significant sensitivity gains for accelerated and unaccelerated pediatric brain imaging. Magn Reson Med, 2011. © 2011 Wiley Periodicals, Inc.     

High‐resolution uniform MR imaging of finger joints using a dedicated RF coil at 3T

Purpose

To develop a dedicated radiofrequency (RF) coil for high‐resolution magnetic resonance imaging (MRI) of finger joints at 3T to improve diagnostic evaluation of arthritic diseases.

Materials and Methods

A dedicated cylindrical RF receive coil was developed for imaging finger joints at 3T. A planar coil, a saddle coil, and a 1.5T coil with similar design as the dedicated coil were also constructed to compare imaging performance with the dedicated coil. A phantom was used for quantitative evaluation. Three‐dimensional images were obtained on four subjects and a cadaver finger specimen using isotropic resolution of 160 μm in 9:32 minutes. The images were reviewed by two musculoskeletal radiologists.

Results

The dedicated finger coil provided higher signal‐to‐noise and greater signal uniformity than the other coils. It supported high‐resolution imaging that demonstrated anatomical details of the entire finger joint, and in the subject study revealed abnormalities not detectable by traditional clinical resolution.

Conclusion

The dedicated finger coil optimizes the potential advantages of 3T scanners compared to lower field magnets. Use of this coil should facilitate early diagnosis, improve assessment of treatment response, and provide better understanding of basic mechanisms that underlie arthritis. J. Magn. Reson. Imaging 2010. © 2009 Wiley‐Liss, Inc.     

Prospective motion correction using tracking coils

Intracavity imaging coils provide higher signal‐to‐noise than surface coils and have the potential to provide higher spatial resolution in shorter acquisition times. However, images from these coils suffer from physiologically induced motion artifacts, as both the anatomy and the coils move during image acquisition. We developed prospective motion‐correction techniques for intracavity imaging using an array of tracking coils. The system had <50 ms latency between tracking and imaging, so that the images from the intracavity coil were acquired in a frame of reference defined by the tracking array rather than by the system's gradient coils. Two‐dimensional gradient‐recalled and three‐dimensional electrocardiogram‐gated inversion‐recovery‐fast‐gradient‐echo sequences were tested with prospective motion correction using ex vivo hearts placed on a moving platform simulating both respiratory and cardiac motion. Human abdominal tests were subsequently conducted. The tracking array provided a positional accuracy of 0.7 ± 0.5 mm, 0.6 ± 0.4 mm, and 0.1 ± 0.1 mm along the X, Y, and Z directions at a rate of 20 frames‐per‐second. The ex vivo and human experiments showed significant image quality improvements for both in‐plane and through‐plane motion correction, which although not performed in intracavity imaging, demonstrates the feasibility of implementing such a motion‐correction system in a future design of combined tracking and intracavity coil. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.     

Inductively coupled helmholtz coil on a dedicated imaging platform for the in vivo 1H‐MRS measurement of intramyocellular lipids in the hind leg of rats

Skeletal muscle triglycerides are markers for insulin resistance in type 2 diabetes. Recently, MR spectroscopy was adapted for in vivo measurement of triglycerides in animal models and for the characterization of new therapeutic approaches. Because of small MR spectroscopy voxel sizes used in skeletal muscles, surface coils are used for signal reception. Furthermore, to obtain well‐resolved and undistorted lipid spectra, muscle fibers must be aligned parallel to the magnetic field. Consequently, to achieve a high signal‐to‐noise ratio and spectral quality, a coil setup must combine high sensitivity with a reliable and reproducible positioning of muscle and voxel. These demands are difficult to match using surface coils. Here, a coil platform is described, which uses inductively coupled Helmholtz coil setup combined with a leg retainer system for rats. The new system allows for measurement of intramyocellular lipids with high signal‐to‐noise ratio and for significantly improved animal handling, positioning, and throughput. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.     

Phase‐field dithering for active catheter tracking

A strategy to increase the robustness of active MR tracking of microcoils in low signal‐to‐noise ratio conditions was developed and tested. The method employs dephasing magnetic field gradient pulses that are applied orthogonal to the frequency‐encoding gradient pulse used in conventional point‐source MR tracking. In subsequent acquisitions, the orthogonal dephasing gradient pulse is rotated while maintaining a perpendicular orientation with respect to the frequency‐encoding gradient. The effect of the dephasing gradient is to apply a spatially dependent phase shift in directions perpendicular to the frequency‐encoding gradient. Since the desired MR signal for robust MR tracking comes from the small volume of nuclear spins near the small detection coil, the desired signal is not dramatically altered by the dephasing gradient. Undesired MR signals arising from larger volumes (e.g., due to coupling with the body coil or surface coils), on the other hand, are dephased and reduced in signal intensity. Since the approach requires no a priori knowledge of the microcoil orientation with respect to the main magnetic field, data from several orthogonal dephasing gradients are acquired and analyzed in real time. One of several selection algorithms is employed to identify the “best” data for use in the coil localization algorithm. This approach was tested in flow phantoms and animal models, with several multiplexing schemes, including the Hadamard and zero‐phase reference approaches. It was found to provide improved MR tracking of untuned microcoils. It also dramatically improved MR tracking robustness in low signal‐to‐noise‐ratio conditions and permitted tracking of microcoils that were inductively coupled to the body coil. Magn Reson Med 63:1398–1403, 2010. © 2010 Wiley‐Liss, Inc.     

Diffusion tensor echo planar imaging using surface coil transceiver with a semiadiabatic RF pulse sequence at 14.1T

Diffusion magnetic resonance studies of the brain are typically performed using volume coils. Although in human brain this leads to a near optimal filling factor, studies of rodent brain must contend with the fact that only a fraction of the head volume can be ascribed to the brain. The use of surface coil as transceiver increases Signal‐to‐Noise Ratio (SNR), reduces radiofrequency power requirements and opens the possibility of parallel transmit schemes, likely to allow efficient acquisition schemes, of critical importance for reducing the long scan times implicated in diffusion tensor imaging. This study demonstrates the implementation of a semiadiabatic echo planar imaging sequence (echo time = 40 ms, four interleaves) at 14.1T using a quadrature surface coil as transceiver. It resulted in artifact free images with excellent SNR throughout the brain. Diffusion tensor derived parameters obtained within the rat brain were in excellent agreement with reported values. Magn Reson Med, 2011. © 2010 Wiley‐Liss, Inc.     

Single breath‐hold assessment of ventricular volumes using 32‐channel coil technology and an extracellular contrast agent

Purpose:

To evaluate the feasibility of a single breath‐hold 3D cine balanced steady‐state free precession (b‐SSFP) sequence after gadolinium diethylenetriamine penta‐acetic acid (Gd‐DTPA) injection for volumetric cardiac assessment.

Materials and Methods:

Fifteen adult patients routinely referred for cardiac magnetic resonance imaging (MRI) underwent quantitative ventricular volumetry on a clinical 1.5T MR‐scanner using a 32‐channel cardiac coil. A stack of 2D cine b‐SSFP slices covering the ventricles was used as reference, followed by a single breath‐hold 3D cine balanced SSFP protocol acquired before and after administration of Gd‐DTPA. The acquisition was accelerated using SENSE in both phase encoding directions. Volumetric and contrast‐to‐noise data for each technique were assessed and compared.

Results:

The 3D cine protocol was accomplished within one breath‐hold (mean acquisition time 20 sec; spatial resolution 2.1 × 2.1 × 10 mm; temporal resolution 51 msec). The contrast‐to‐noise ratio between blood and myocardium was 234 determined for the multiple 2D cine data, and could be increased for the 3D acquisition from 136 (3D precontrast) to 203 (3D postcontrast) after injecting Gd‐DTPA. In addition the endocardial definition was significantly improved in postcontrast 3D cine b‐SSFP. There was no significant difference for left and right ventricular volumes between standard 2D and 3D postcontrast cine b‐SSFP. However, Bland–Altman plots showed greater bias and scatter when comparing 2D with 3D cine b‐SSFP without contrast.

Conclusion:

3D cine b‐SSFP imaging of the heart using 32 channel coil technology and spatial undersampling allows reliable volumetric assessment within a single breath‐hold after application of Gd‐DTPA. J. Magn. Reson. Imaging 2010;31:838–844. ©2010 Wiley‐Liss, Inc.     

High‐resolution MRS in the presence of field inhomogeneity via intermolecular double‐quantum coherences on a 3‐T whole‐body scanner

Signals from intermolecular double‐quantum coherences (iDQCs) have been shown to be insensitive to macroscopic field inhomogeneities and thus enable acquisition of high‐ resolution MR spectroscopy in the presence of large inhomogeneous fields. In this paper, localized iDQC ¹H spectroscopy on a whole‐body 3‐T MR scanner is reported. Experiments with a brain metabolite phantom were performed to quantify characteristics of the iDQC signal under different conditions. The feasibility of in vivo iDQC high‐resolution MR spectroscopy in the presence of large intrinsic and external field inhomogeneity (in the order of hundreds of hertz) was demonstrated in the whole cerebellum of normal volunteers in a scan time of about 6.5 min. Major metabolite peaks were well resolved in the reconstructed one‐dimensional spectra projected from two‐dimensional iDQC acquisitions. Investigations on metabolite ratios, signal‐to‐noise ratio, and line width were performed and compared with results obtained with conventional point‐resolved spectroscopy/MR spectroscopy in homogeneous fields. Metabolite ratios from iDQC results showed excellent consistency under different in vitro and in vivo conditions, and they were similar to those from point‐resolved spectroscopy with small voxel sizes in homogeneous fields. MR spectroscopy with iDQCs can be applied potentially for quantification of gross metabolite changes due to diseases in large brain volumes with high field inhomogeneity. Magn Reson Med, 2010. © 2010 Wiley‐Liss, Inc.     

Dynamic and high‐resolution metabolic imaging of hyperpolarized [1‐13C]‐pyruvate in the rat brain using a high‐performance gradient insert

Fast chemical shift imaging (CSI) techniques are advantageous in metabolic imaging of hyperpolarized compounds due to the limited duration of the signal amplification. At the same time, reducing the acquisition time in hyperpolarized imaging does not necessarily lead to the conventional penalty in signal‐to‐noise ratio that occurs in imaging at thermal equilibrium polarization levels. Here a high‐performance gradient insert was used in combination with undersampled spiral CSI to increase either the imaging speed or the spatial resolution of hyperpolarized ¹³C metabolic imaging on a clinical 3T MR scanner. Both a single‐shot sequence with a total acquisition time of 125 ms and a three‐shot sequence with a nominal in‐plane resolution of 1.5 mm were implemented. The k‐space trajectories were measured and then used during image reconstruction. The technique was applied to metabolic imaging of the rat brain in vivo after the injection of hyperpolarized [1‐¹³C]‐pyruvate. Dynamic imaging afforded the measurement of region‐of‐interest‐specific time courses of pyruvate and its metabolic products, while imaging at high spatial resolution was used to better characterize the spatial distribution of the metabolite signals. Magn Reson Med, 2011. © 2010 Wiley‐Liss, Inc.     

A comparison of an inductively coupled implanted coil with optimized surface coils for in vivo NMR imaging of the spinal cord

A study was performed to determine whether an implanted, inductively coupled nuclear magnetic resonance (NMR) imaging spine coil could provide a significant gain in signal-to-noise ratio (SNR) on images of the spinal cord relative to the SNR of optimized surface coils. Implanted coils were surgically affixed to the upper lumbar spine (first lumbar through third lumbar vertebrae) in a total of four adult cats. The implanted coil was inductively coupled to an external 12 × 12 cm square surface coil that was mounted on a 14-cm diameter Plexiglas® cradle (Townsend Industries, Des Moines, IA). Two similar cradles were prepared with transmit-only 12 × 12 cm surface coils and either a receive-only 6 × 6 cm square surface coil or a receive-only quadrature coil pair (two 4 × 6 cm coils overlapped slightly to minimize their mutual inductance) with 'the same surface area (6 × 6 cm). A total of five single-slice, T1-weighted spin-echo images (TR = 500 ms, TE = 30 ms, 4-mm slice thickness) were acquired from a 1-liter saline phantom and from the second lumbar spinal level in an adult cat with a normal, uninjured spinal cord. On the spinal cord images, the quadrature coil exhibited a factor of 1.65 increase in SNR relative to the single-turn surface coil, whereas the implanted coil achieved a factor of 2.19 increase in SNR. The improved SNR for the quadrature and implanted coils was observed as a dramatic improvement in the clarity of the images. The high SNR available with the implanted coils allows the acquisition of higher resolution NMR images and opens up the possibility of measuring localized spectroscopy in vivo within the spinal cord.     

96‐Channel receive‐only head coil for 3 Tesla: Design optimization and evaluation

The benefits and challenges of highly parallel array coils for head imaging were investigated through the development of a 3T receive‐only phased‐array head coil with 96 receive elements constructed on a close‐fitting helmet‐shaped former. We evaluated several designs for the coil elements and matching circuitry, with particular attention to sources of signal‐to‐noise ratio (SNR) loss, including various sources of coil loading and coupling between the array elements. The SNR and noise amplification (g‐factor) in accelerated imaging were quantitatively evaluated in phantom and human imaging and compared to a 32‐channel array built on an identical helmet‐shaped former and to a larger commercial 12‐channel head coil. The 96‐channel coil provided substantial SNR gains in the distal cortex compared to the 12‐ and 32‐channel coils. The central SNR for the 96‐channel coil was similar to the 32‐channel coil for optimum SNR combination and 20% lower for root‐sum‐of‐squares combination. There was a significant reduction in the maximum g‐factor for 96 channels compared to 32; for example, the 96‐channel maximum g‐factor was 65% of the 32‐channel value for acceleration rate 4. The performance of the array is demonstrated in highly accelerated brain images. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.     

Adaptive non‐local means denoising of MR images with spatially varying noise levels

Purpose:

To adapt the so‐called nonlocal means filter to deal with magnetic resonance (MR) images with spatially varying noise levels (for both Gaussian and Rician distributed noise).

Materials and Methods:

Most filtering techniques assume an equal noise distribution across the image. When this assumption is not met, the resulting filtering becomes suboptimal. This is the case of MR images with spatially varying noise levels, such as those obtained by parallel imaging (sensitivity‐encoded), intensity inhomogeneity‐corrected images, or surface coil‐based acquisitions. We propose a new method where information regarding the local image noise level is used to adjust the amount of denoising strength of the filter. Such information is automatically obtained from the images using a new local noise estimation method.

Results:

The proposed method was validated and compared with the standard nonlocal means filter on simulated and real MRI data showing an improved performance in all cases.

Conclusion:

The new noise‐adaptive method was demonstrated to outperform the standard filter when spatially varying noise is present in the images. J. Magn. Reson. Imaging 2010;31:192–203. © 2009 Wiley‐Liss, Inc.     

Online real‐time reconstruction of adaptive TSENSE with commodity CPU/GPU hardware

Adaptive temporal sensitivity encoding (TSENSE) has been suggested as a robust parallel imaging method suitable for MR guidance of interventional procedures. However, in practice, the reconstruction of adaptive TSENSE images obtained with large coil arrays leads to long reconstruction times and latencies and thus hampers its use for applications such as MR‐guided thermotherapy or cardiovascular catheterization. Here, we demonstrate a real‐time reconstruction pipeline for adaptive TSENSE with low image latencies and high frame rates on affordable commodity personal computer hardware. For typical image sizes used in interventional imaging (128 × 96, 16 channels, sensitivity encoding (SENSE) factor 2‐4), the pipeline is able to reconstruct adaptive TSENSE images with image latencies below 90 ms at frame rates of up to 40 images/s, rendering the MR performance in practice limited by the constraints of the MR acquisition. Its performance is demonstrated by the online reconstruction of in vivo MR images for rapid temperature mapping of the kidney and for cardiac catheterization. Magn Reson Med, 2009. © 2009 Wiley‐Liss, Inc.     

In vivo high‐resolution imaging of the injured rat spinal cord using a 3.0T clinical MR scanner

Purpose

To investigate the feasibility of obtaining high‐resolution MR images for the detection of pathological changes occurring in the injured rat spinal cord with a routine clinical 3.0T imaging system.

Materials and Methods

Adult female Fischer 344 rats received thoracic spine contusion injuries. In vivo MR imaging was performed on days 1 and 43 postinjury with a clinical head 3.0T imaging system equipped with a dedicated small animal 4‐channel phased array spine surface coil using T2‐weighted turbo spin‐echo and T1‐weighted spin‐echo sequences.

Results

The acquired images provide good spatial resolution allowing reliable gray/white matter differentiation in the intact spinal cord as well as detection of hemorrhage, edema, and cystic degenerative changes in the injured rat spinal cord as confirmed by correlation with structural alterations in histological sections.

Conclusion

Results from the present study demonstrate that a routine clinical MR imaging system can be employed for noninvasive analysis of pathological changes occurring in the injured rat spinal cord and thus might represent a more broadly available, powerful tool to monitor the effects of experimental therapeutic interventions in vivo. J. Magn. Reson. Imaging 2009;29:725–730. © 2009 Wiley‐Liss, Inc.