Magnetic Resonance Imaging

Editorial Board

2010-02-01

Analysis of hyperpolarized dynamic 13C lactate imaging in a transgenic mouse model of prostate cancer

2009-08-20

Abstract: This study investigated the application of an acquisition that selectively excites the [1-13C]lactate resonance and allows dynamic tracking of the conversion of 13C-lactate from hyperpolarized 13C-pyruvate at a high spatial resolution. In order to characterize metabolic processes occurring in a mouse model of prostate cancer, 20 sequential 3D images of 13C-lactate were acquired 5 s apart using a pulse sequence that incorporated a spectral–spatial excitation pulse and a flyback echo-planar readout to track the time course of newly converted 13C-lactate after injection of prepolarized 13C-pyruvate. The maximum lactate signal (MLS), full-width half-maximum (FWHM), time to the peak 13C-lactate signal (TTP) and area under the dynamic curve were calculated from the dynamic images of 10 TRAMP mice and two wild-type controls. The regional variation in 13C-lactate associated with the injected pyruvate was demonstrated by the peak of the 13C-lactate signal occurring earlier in the kidney than in the tumor region. The intensity of the dynamic 13C-lactate curves also varied spatially within the tumor, illustrating the heterogeneity in metabolism that was most prominent in more advanced stages of disease development. The MLS was significantly higher in TRAMP mice that had advanced disease.

MR spectroscopic imaging of glutathione in the white and gray matter at 7 T with an application to multiple sclerosis

2009-08-20

Abstract: Detection of glutathione (GSH) is technically challenging at clinical field strengths of 1.5 or 3 T due to its low concentration in the human brain coupled with the fact that conventional single-echo acquisitions, typically used for magnetic resonance (MR) spectroscopy acquisitions, cannot be used to resolve GSH given its overlap with other resonances. In this study, an MR spectral editing scheme was used to generate an unobstructed detection of GSH at 7 T. This technique was used to obtain normative white (WM) and gray matter (GM) GSH concentrations over a two-dimensional region. Results indicated that GSH was significantly higher (P<.001) in GM relative to WM in normal subjects. This finding is consistent with previous radionuclide experiments and histochemical staining and validates this 7 T MR spectroscopy technique. To our knowledge, this is the first study to report normative differences in WM and GM glutathione concentrations in the human brain. Glutathione is a biomarker for oxidative status and this non-invasive in vivo measurement of GSH was used to explore its sensitivity to oxidative state in multiple sclerosis (MS) patients. There was a significant reduction (P<.001) of GSH between the GM in MS patients and normal controls. No statistically significant GSH differences were found between the WM in controls and MS patients. Reduced GSH was also observed in a MS WM lesion. This preliminary investigation demonstrates the potential of this marker to probe oxidative state in MS.

Spatially resolved multidimensional cross-correlation relaxometry

Luca Venturi, Brian Hills — 2009-09-04

Abstract: Novel protocols are presented for acquiring one- and two-dimensional relaxation time spectra from selected subvolumes of a macroscopically heterogeneous sample. Although the protocols are generally applicable, special emphasis is given to their implementation on low-cost, low-field bench-top relaxometers lacking pulse shaping or pulsed gradient facilities.

Orientational analysis of the Achilles tendon and enthesis using an ultrashort echo time spectroscopic imaging sequence

2009-08-20

Abstract: Tendons and entheses are magnetic resonance (MR) “invisible” when imaged with conventional clinical pulse sequences. When the highly ordered, collagen-rich fibers in tendons and entheses are placed at the magic angle, dipolar interactions are decreased and their T2s are often considerably increased. The bulk magnetic susceptibility of tendons and entheses also varies with orientation to B0, leading to a direction-dependent resonance frequency shift. Ultrashort echo time (UTE) sequences with a minimum TE of 8 μs provide high signal from both tendons and entheses. The combination of a UTE sequence with an interleaved undersampled variable TE acquisition scheme provides a new approach for fast spectroscopic imaging of short T2 tissues. This UTE spectroscopic imaging (UTESI) technique provides quantitative information including T2⁎, chemical shift and resonance frequency shift due to bulk susceptibility effect. In this article, the orientational effects on tendons and entheses were investigated using a UTESI sequence on a clinical 3-T scanner. T2⁎ was found to increase fivefold for tendons and twofold for entheses due to the magic angle effect. A resonance frequency shift up to 1.2 ppm was observed for both tendons and entheses due to the bulk susceptibility effect when their orientation was changed from 0° to 90° relative to B0.

Registering spherical navigators with spherical harmonic expansions to measure three-dimensional rotations in magnetic resonance imaging

Andreu F. Costa, Yi-Fen Yen, Maria Drangova — 2009-09-16

Abstract: Subject motion remains a challenging problem to overcome in clinical and research applications of magnetic resonance imaging (MRI). Subject motion degrades the quality of MR images and the integrity of experimental data. A promising method to correct for subject motion in MRI is the spherical navigator (SNAV) echo. Spherical navigators acquire k-space data on the surface of a sphere in order to measure three-dimensional (3D) rigid-body motion. Analysis begins by registering the magnitude of two SNAVs to determine the 3D rotation between them. Several different methods to register SNAV data exist, each with specific capabilities and limitations. In this study, we assessed the accuracy, precision and computational requirements of measuring rotations about all three coordinate axes by correlating the spherical harmonic expansions of SNAV data. We compare the results of this technique to previous SNAV studies and show that, although computationally expensive, the spherical harmonic technique is a highly accurate, precise and robust method to register SNAVs and detect 3D rotations in MRI. A key advantage to the spherical harmonic technique is the ability to optimize the accuracy, precision, processing time and memory requirements by adjusting parameters used in the registration. While present developments are aimed at improving the programming efficiency and memory handling of the algorithm, this registration technique is currently well suited for retrospective motion correction applications, such as removing motion-related image artifacts and aligning slices within a high-resolution 3D volume.

Time-resolved contrast-enhanced coronary magnetic resonance angiography with highly constrained projection reconstruction

Lan Ge, Xiaoming Bi, Peng Lai, Debiao Li — 2009-09-25

Abstract: Contrast-enhanced magnetic resonance angiography (MRA) is a promising technique for coronary artery imaging. The blood signal changes during the contrast injection will result in image artifacts, blurring and relatively low signal-to-noise ratio, when the k-space segments from different cardiac cycles are combined to reconstruct the final image as “time averaged.” Thus, it is important to acquire data during maximal blood signal enhancement for first-pass, contrast-enhanced MRA, and relatively high temporal resolution is required. This work demonstrated the feasibility of highly constrained backprojection reconstruction for time-resolved, contrast-enhanced coronary MRA. With this method, the temporal resolution can be increased. In addition, coronary artery images around blood signal enhancement peak have significantly improved contrast-to-noise ratio and suppressed artifacts compared to the composite images which were collected during a much longer acquisition time during substantial blood signal changes.

Efficient anisotropic filtering of diffusion tensor images

Qing Xu, Adam W. Anderson, John C. Gore, Zhaohua Ding — 2010-01-11

Abstract: To improve the accuracy of structural and architectural characterization of living tissue with diffusion tensor imaging, an efficient smoothing algorithm is presented for reducing noise in diffusion tensor images. The algorithm is based on anisotropic diffusion filtering, which allows both image detail preservation and noise reduction. However, traditional numerical schemes for anisotropic filtering have the drawback of inefficiency and inaccuracy due to their poor stability and first order time accuracy. To address this, an unconditionally stable and second order time accuracy semi-implicit Craig-Sneyd scheme is adapted in our anisotropic filtering. By using large step size, unconditional stability allows this scheme to take much fewer iterations and thus less computation time than the explicit scheme to achieve a certain degree of smoothing. Second-order time accuracy makes the algorithm reduce noise more effectively than a first order scheme with the same total iteration time. Both the efficiency and effectiveness are quantitatively evaluated based on synthetic and in vivo human brain diffusion tensor images, and these tests demonstrate that our algorithm is an efficient and effective tool for denoising diffusion tensor images.

Diffusion tensor imaging in horizontal gaze palsywith progressive scoliosis

Ashwin Avadhani, V. Ilayaraja, Ajoy P. Shetty, S. Rajasekaran — 2010-01-14

Abstract: Horizontal gaze palsy with progressive scoliosis (HGPPS) is a rare disorder characterized by absence of conjugate horizontal eye movements, preservation of vertical gaze and convergence, progressive scoliosis developing in childhood and adolescence. It is caused by mutations in the ROBO3 gene which are critical for the crossing of long ascending medial lemniscal and descending corticospinal tracts in the medulla. Diffusion tensor imaging on a 14-year-old boy with HGPPS revealed ipsilateral ascending and descending connectivity in the brainstem without any crossing over of the major tracts although normal interhemispheric connections in the corpus callosum was demonstrable. Absent decussation of smaller sized superior cerebellar peduncles but with normal crossing over of the middle cerebellar peduncle was also observed. Tractography is a valuable investigative modality to assess neuronal connections in the brain and is a useful adjunct to the structural magnetic resonance imaging in confirming the diagnosis of HGPPS.

The connectivity of the superior longitudinal fasciculus: a tractography DTI study

Byron Bernal, Nolan Altman — 2009-08-20

Abstract: Purpose: The left superior longitudinal fasciculus (SLF) has been felt to link receptive with expressive language areas. The latter is located in the pars opercularis (Broca's area) of the left inferior frontal gyrus. We report the findings with tractography of the SLF in a group of normal volunteers.Methods and materials: The data and subsidiary results of 12 normal right-handed volunteers who participated in an institutional review board-approved diffusion tensor imaging study were evaluated. The SLF fibers were obtained bilaterally placing a region of interest at the triangular-shaped region lateral to each of the corticospinal tracts, in a coronal plane along the rostral aspect of the corpus callosum. A sagittal fractional anisotropy image was used to determine the rostral endpoint of the SLF fibers in the white matter pertaining to specific gyri or pars of the frontal lobe. The SLF projection to Broca's area was ranked qualitatively as none, minimal, most or all. Findings are presented in descriptive statistics.Results: The SLF projection to Broca's areas was absent in seven subjects (58.3%) and minimal in five (41.6%). SLF's rostral end points were found uniquely or mainly in the precentral gyrus in 100% of cases.Conclusion: The SLF was found connecting the posterior language areas to the precentral gyrus and only marginally in some cases to the canonical Broca's area. This finding is consistent with reports describing lack of correlation between lateralization of the SLF and language areas. The understanding of language circuitry is beginning to emerge with the use of tractography.

Functional MRI changes in the central motor system in myotonic dystrophy type 1

2009-08-20

Abstract: Myotonic dystrophy type 1 (DM1) is a multisystemic disease involving multiple organ systems including central nervous system (CNS) and muscles. Few studies have focused on the central motor system in DM1, pointing to a subclinical abnormality in the CNS. The aim of our study was to investigate patterns of cerebral activation in DM1 during a motor task using functional MRI (fMRI). Fifteen DM1 patients, aged 20 to 59 years, and 15 controls of comparable age were scanned during a self-paced sequential finger-to-thumb opposition task of their dominant right hand. Functional MRI images were analyzed using SPM99. Patients underwent clinical and genetic assessment; all subjects underwent a conventional MR study. Myotonic dystrophy type 1 patients showed greater activation than controls in bilateral sensorimotor areas and inferior parietal lobules, basal ganglia and thalami, in the ipsilateral premotor area, insula and supplementary motor area (corrected P<.05). Analysis of the interaction between disease and age showed that correlation with age was significantly greater in patients than in controls in bilateral sensorimotor areas and in contralateral parietal areas. Other clinical and MR characteristics did not correlate with fMRI. Functional changes in DM1 may represent compensatory mechanisms such as reorganization and redistribution of functional networks to compensate for ultrastructural and neurochemical changes occurring as part of the accelerated aging process.

Evaluation of preprocessing steps to compensate for magnetic field distortions due to body movements in BOLD fMRI

2009-08-20

Abstract: Blood oxygenation level-dependent (BOLD) functional magnetic resonance imaging (fMRI) is currently the dominant technique for non-invasive investigation of brain functions. One of the challenges with BOLD fMRI, particularly at high fields, is compensation for the effects of spatiotemporally varying magnetic field inhomogeneities (ΔB0) caused by normal subject respiration and, in some studies, movement of the subject during the scan to perform tasks related to the functional paradigm. The presence of ΔB0 during data acquisition distorts reconstructed images and introduces extraneous fluctuations in the fMRI time series that decrease the BOLD contrast-to-noise ratio. Optimization of the fMRI data-processing pipeline to compensate for geometric distortions is of paramount importance to ensure high quality of fMRI data. To investigate ΔB0 caused by subject movement, echo-planar imaging scans were collected with and without concurrent motion of a phantom arm. The phantom arm was constructed and moved by the experimenter to emulate forearm motions while subjects remained still and observed a visual stimulation paradigm. These data were then subjected to eight different combinations of preprocessing steps. The best preprocessing pipeline included navigator correction, a complex phase regressor and spatial smoothing. The synergy between navigator correction and phase regression reduced geometric distortions better than either step in isolation and preconditioned the data to make them more amenable to the benefits of spatial smoothing. The combination of these steps provided a 10% increase in t-statistics compared to only navigator correction and spatial smoothing and reduced the noise and false activations in regions where no legitimate effects would occur.

An improved lesion detection approach based on similarity measurement between fuzzy intensity segmentation and spatial probability maps

Shan Shen, Andre J. Szameitat, Annette Sterr — 2009-08-20

Abstract: The application of automatic segmentation methods in lesion detection is desirable. However, such methods are restricted by intensity similarities between lesioned and healthy brain tissue. Using multi-spectral magnetic resonance imaging (MRI) modalities may overcome this problem but it is not always practicable. In this article, a lesion detection approach requiring a single MRI modality is presented, which is an improved method based on a recent publication. This new method assumes that a low similarity should be found in the regions of lesions when the likeness between an intensity based fuzzy segmentation and a location based tissue probabilities is measured. The usage of a normalized similarity measurement enables the current method to fine-tune the threshold for lesion detection, thus maximizing the possibility of reaching high detection accuracy. Importantly, an extra cleaning step is included in the current approach which removes enlarged ventricles from detected lesions. The performance investigation using simulated lesions demonstrated that not only the majority of lesions were well detected but also normal tissues were identified effectively. Tests on images acquired in stroke patients further confirmed the strength of the method in lesion detection. When compared with the previous version, the current approach showed a higher sensitivity in detecting small lesions and had less false positives around the ventricle and the edge of the brain.

Influence of age and sex on aortic distensibility assessed by MRI in healthy subjects

2009-08-20

Abstract: Magnetic resonance imaging (MRI) is particularly well adapted to the evaluation of aortic distensibility. The calculation of this parameter, based on the change in vessel cross-sectional area per unit change in blood pressure, requires precise delineation of the aortic wall on a series of cine-MR images. Firstly, the study consisted in validating a new automatic method to assess aortic elasticity. Secondly, aortic distensibility was studied for the ascending and descending thoracic aortas in 26 healthy subjects. Two homogeneous groups were available to evaluate the influence of sex and age (with an age limit value of 35 years). The automatic postprocessing method proved to be robust and reliable enough to automatically determine aortic distensibility, even on artefacted images. In the 26 healthy volunteers, a marked decrease in distensibility appears with age, although this decrease is only significant for the ascending aorta (8.97±2.69 10−3 mmHg−1 vs. 5.97±2.02 10−3 mmHg−1). Women have a higher aortic distensibility than men but only significantly at the level of the descending aorta (7.20±1.61 10−3 mmHg−1 vs. 5.05±2.40 10−3 mmHg−1). Through our automatic contouring method, the aortic distensibility from routine cine-MRI has been studied on a healthy subject population providing reference values of aortic stiffness. The aortic distensibility calculation shows that age and sex are causes of aortic stiffness variations in healthy subjects.

Magnetic resonance imaging follow-up of liver growth of neuroendocrine tumors in an experimental mouse model

2009-08-20

Abstract: Liver metastases in patients with gastroenteropancreatic (GEP) endocrine tumors represent the main factor of adverse prognosis in this tumor type and thus have a strong effect on the therapeutic strategies. Currently, magnetic resonance imaging (MRI) is considered the modality of choice for the noninvasive, in vivo detection of liver metastases. Dedicated MRI protocols suitable for following liver lesion evolution on an experimental model of endocrine tumors could be valuable. An experimental animal model mimicking the clinical situation of intrahepatic dissemination has been designed. The goal of this study was to characterize liver lesions in this athymic nude mouse model and assess the detection sensitivity of MRI using a physiological gating strategy optimized for high magnetic fields.The experiments were performed at 7 T using a dual cardiac–respiratory-triggered multiple spin-echo sequence. This protocol was used to carry out a longitudinal follow-up of hepatic lesions in a group of eight nude mice at different stages: Day 7 (D7), Day 12 (D12), Day 17 (D17) and Day 24 (D24). The hepatic lesion volume fraction (HLVF) was quantified using an adaptive segmentation procedure based on a dual-reference limit. Mean transverse relaxation time T2 values were quantified from multiple spin-echo images.The first lesions were detected at stage D12 on images with 20-ms TE. From D12, the HLVF increased significantly with stage. The mean T2 values also increased significantly at D17 and D24.In conclusion, the level of detection and characterization of liver lesions were performed using a devoted protocol with a dedicated high-field MRI synchronization strategy. In future studies, MRI could be used to monitor the effects of targeted therapies on liver endocrine metastases in preclinical animal models.

Diet and gastrointestinal signal on T1-weighted magnetic resonance imaging of mice

2010-01-11

Abstract: In magnetic resonance (MR) imaging of small animals, the gastrointestinal contents may give rise to intense signals on T1-weighted images. The aim of this study was to determine the optimal dietary preparation to reduce gastrointestinal signals in mice and to evaluate the usefulness of this approach. Images of the mouse trunk were obtained using a T1-weighted, three-dimensional fast low-angle shot sequence under various dietary conditions and were compared with respect to the gastrointestinal signals and image quality. The dietary preparation studied included giving alternative diets for 24 h, intestinal cleansing, and 6-h fasting. Mice with and without dietary preparation underwent MR lymphography using gadofluorine 8, and the visualization of abdominal lymph nodes was compared. In the absence of dietary preparation, hyperintense areas were conspicuous in the gastrointestinal system, whereas on the images taken from mice fed potato or sweet potato for 24 h before imaging, gastrointestinal hyperintensity was less prominent. This preparation also reduced artifactual signals and resulted in higher-quality images of the kidneys. Intestinal cleansing, which consisted of 24-h fasting and laxative intake, did not reduce the gastrointestinal signals and caused signal changes that were indicative of fatty liver development. Some of the abdominal lymph nodes of the mice that did not receive dietary preparation were visualized on MR lymphography source images but not on maximum intensity projection (MIP) images. In contrast, on the MIP images of mice fed potato, all the lymph nodes delineated on the source images were successfully visualized. In conclusion, feeding mice potato or sweet potato for 24 h before MR imaging reduces the gastrointestinal signals and image degradation due to artifacts. Appropriate dietary preparations facilitate the display of target structures on MIP images and are expected to enhance the capabilities of small animal MR imaging.

The use of T2*-weighted multi-echo GRE imaging as a novel method to diagnose hepatocellular carcinoma compared with gadolinium-enhanced MRI: a feasibility study

Andrew D. Hardie, Peter B. Romano — 2010-01-14

Abstract: Background: The goal of the study was to assess a T2*-weighted MRI sequence for the ability to identify hepatocellular carcinoma (HCC).Methods: Hepatic iron deposition, which is common in chronic liver disease (CLD), may increase the conspicuity of HCC on GRE imaging due to increased T2* signal decay in liver parenchyma. In this study, a breath-hold T2*-weighted MRI sequence was evaluated by a blinded observer for HCC and the results compared to a reference standard of gadolinium-enhanced MRI in these same patients. Forty-one patients (mean age 56.2 years; 17 females) were included in this approved, retrospective study.Results: By the reference standard, 14 of 41 patients had a total of 25 HCCs. The sensitivity of the T2*-weighted MR sequence for identifying HCC, per lesion, was 60%, while the specificity was 100%. There was a significantly lower T2* value of liver parenchyma in patients with HCC identified by the T2*-weighted sequence than in those with HCCs which were not identified by the T2*-weighted sequence (27.8±2.2 vs. 21.9±2.1 ms; P=.02).Conclusions: A T2*-weighted MRI sequence can identify HCC in patients with CLD. This technique may be beneficial for imaging of patients contraindicated for gadolinium.

A volume resolution phantom for MRI

Sang Yun Moon, Joseph P. Hornak — 2009-08-20

Abstract: Multisite quantitative magnetic resonance imaging (qMRI) of volume requires a small isotropic point spread-function (PSF) that is spatially, temporarily, and platform invariant. A phantom which will allow rapid assessment of this metric throughout the imaged volume without repositioning will assist certification of imaging sites for use in qMRI studies based on volume. This paper presents a phantom design for this purpose with a three-dimensional repeating pattern throughout its 800-cm3 volume. The image of the pattern from the phantom contains a series of positive signal points and lines which can be used to measure the PSF, gradient linearity, gradient orthogonality, and B0 homogeneity at multiple locations throughout its volume. The phantom is readily constructed, can be filled with any nuclear magnetic resonance signal-bearing liquid, and the design is scalable to cover larger volumes.

Quantitative assessment of motion correction for high angular resolution diffusion imaging

Ken E. Sakaie, Mark J. Lowe — 2009-08-20

Abstract: Several methods have been proposed for motion correction of high angular resolution diffusion imaging (HARDI) data. There have been few comparisons of these methods, partly due to a lack of quantitative metrics of performance. We compare two motion correction strategies using two figures of merit: displacement introduced by the motion correction and the 95% confidence interval of the cone of uncertainty of voxels with prolate tensors. What follows is a general approach for assessing motion correction of HARDI data that may have broad application for quality assurance and optimization of postprocessing protocols. Our analysis demonstrates two important issues related to motion correction of HARDI data: (1) although neither method we tested was dramatically superior in performance, both were dramatically better than performing no motion correction, and (2) iteration of motion correction can improve the final results. Based on the results demonstrated here, iterative motion correction is strongly recommended for HARDI acquisitions.

The sign convention for phase values on different vendor systems: definition and implications for susceptibility-weighted imaging

Gisela E. Hagberg, E. Brian Welch, Andreas Greiser — 2009-08-25

In susceptibility-weighted imaging (SWI), the contrast in magnitude gradient echo images is enhanced by multiplication with a mask generated from the phase information . The technique has proven useful for imaging of veins and venules in virtue of the local magnetic field changes in the presence of paramagnetic elements that affect the measured MR phase . The actual value of the phase will not only depend on factors related to the geometry of the brain and vessel structures and their orientation with respect to the external static magnetic field B0 or the imaging parameters (such as TE, sampling bandwidth and voxel aspect ratio as described in Refs. ), but will also be affected by the sum effect of hardware differences in different vendor systems, like the phase relationship between transmission and receiver lines, the sign relation between the direct and the delayed line in the demodulator, as well as the sign of the actual gradient applied during read out, besides possible postprocessing of the incoming signal before or after Fourier transform. The final result is that a system is going to be one of two ways in regard to the phase sign convention. The aim of this letter was to show how all these factors related to different parts of the MR system can be summed up in two frameworks for describing spin behavior: the rotating frame or complex plane descriptions. Moreover, we highlight that the desired improvement in SWI contrast can only be achieved if the vendor setting has been taken into account.

Letter to the Editor

Francesco Palmieri, Giovanni di Salvo, Silverio Perrotta, Alfonso Ragozzino — 2009-08-20

We read with interest the article from Positano et al. in the February 2009 issue of Magnetic Resonance Imaging, in which they create a software model of iron overloaded liver, inferred from magnetic resonance (MR) images acquired from 40 patients with thalassemia major. They develop a method that considers the different signal decay of liver parenchyma and blood vessels of this model on a region of interest (ROI) that excludes hilar blood vessels and calculate the T2⁎ value. They compared this software to the classic ROI-based approach , evaluating the intra- and interobserver coefficients of variation and reproducibility for the global analysis. According the authors, the main advantage of this semiautomatic global approach (SGA) is to avoid sampling errors of manual ROI-based methods, as for example the inclusion of blood vessels.

Magnetic Resonance Imaging

Editorial Board

Contents

Analysis of hyperpolarized dynamic 13C lactate imaging in a transgenic mouse model of prostate cancer

MR spectroscopic imaging of glutathione in the white and gray matter at 7 T with an application to multiple sclerosis

Spatially resolved multidimensional cross-correlation relaxometry

Orientational analysis of the Achilles tendon and enthesis using an ultrashort echo time spectroscopic imaging sequence

Registering spherical navigators with spherical harmonic expansions to measure three-dimensional rotations in magnetic resonance imaging

Time-resolved contrast-enhanced coronary magnetic resonance angiography with highly constrained projection reconstruction

Efficient anisotropic filtering of diffusion tensor images

Diffusion tensor imaging in horizontal gaze palsywith progressive scoliosis

The connectivity of the superior longitudinal fasciculus: a tractography DTI study

Functional MRI changes in the central motor system in myotonic dystrophy type 1

Evaluation of preprocessing steps to compensate for magnetic field distortions due to body movements in BOLD fMRI

An improved lesion detection approach based on similarity measurement between fuzzy intensity segmentation and spatial probability maps

Influence of age and sex on aortic distensibility assessed by MRI in healthy subjects

Magnetic resonance imaging follow-up of liver growth of neuroendocrine tumors in an experimental mouse model

Diet and gastrointestinal signal on T1-weighted magnetic resonance imaging of mice

The use of T2*-weighted multi-echo GRE imaging as a novel method to diagnose hepatocellular carcinoma compared with gadolinium-enhanced MRI: a feasibility study

A volume resolution phantom for MRI

Quantitative assessment of motion correction for high angular resolution diffusion imaging

The sign convention for phase values on different vendor systems: definition and implications for susceptibility-weighted imaging

Letter to the Editor