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  • 1
    ISSN: 1432-1920
    Keywords: NMR imaging ; Optic nerve ; Chemical shift artefact ; Contrast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Orbital fat surrounding the optic nerve causes considerable difficulties in NMR imaging due to its high image intensity and the chemical shift artefact. We have investigated the ability of inversion recovery seqeunces with short inversion times (STIR sequences) to suppress fat signals in imaging the optic nerve. We have also compared the contrast attainable with STIR sequences with that obtainable from other sequences. Measurements were made on 4 normal controls and 5 patients with multiple sclerosis (MS) to obtain typical values of relaxation times and proton densities for orbital fat, cerebral white matter and MS lesions. The fat T1 measurements were used to predict an appropriate inversion time for the STIR sequence and estimate how much residual fat signal might be expected as a result of natural variations in fat T1. STIR sequences can be used to suppress the signal from orbital fat with little residual signal. Measurements from white matter and MS lesions were used to predict the contrast between normal and pathological tissues that is attainable with STIR sequences. STIR contrast compares favourably with that obtainable from other sequences.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1920
    Keywords: Key words Magnetisation transfer ratio ; Cervical spinal cord ; Multiple sclerosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract MRI readily detects the lesions of multiple sclerosis (MS) in the brain and spinal cord. Conventional MRI sequences do not, however, permit distinction between the various pathological characteristics (oedema, demyelination, axonal loss and gliosis) of lesions in MS. Magnetisation transfer (MT) imaging may be more specific in distinguishing the pathologies responsible for disability in MS, namely demyelination and axonal loss, and therefore may have a potential role in monitoring treatment. We have applied MT imaging to the cervical spinal cord to see if it is feasible to measure MT ratios (MTR) in this region where pathological changes may result in considerable disability. We studied 12 patients with MS and 12 age- and sex-matched normal controls using a sagittal T2-weighted fast spin-echo sequence with and without an MT pulse. The median value for cervical cord mean MTR measurement in normal controls was 19.30 % units (interquartile range 19.05–19.55), whereas values were significantly lower in MS patients (median = 17.95 % units, interquartile range 17.25–19.00, P = 0.0004). There was a low intrarater variability for repeated mean MTR measurements. We conclude that it is possible to measure MTR in the cervical spinal cord, that a significant reduction occurs in patients with MS, and that there may be a role for this measure in future MS treatment trials.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1920
    Keywords: Key words Multiple sclerosis ; Spinal cord ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report assessment of a new three-dimensional fast spin echo (3D FSE) sequence in ten patients with clinically definite multiple sclerosis, comparing it with standard 2D FSE, and in ten normal controls. We saw 29 focal lesions on the 2D images and 53 on the 3D FSE imgages (P = 0.05); none were seen in controls. Lesion length was significantly smaller on the 3D FSE than on to the 2D FSE images (3D: 1.36; 2D 2,0; P = 0.03). This may relate in part to separation into several lesions on the 3D images of confluent abnormal signal seen on 2D and in part to detection of small lesions missed by the thicker 2D FSE slices (3 mm compared to 1.5 mm). The 3D FSE sequence looks promising in improving spinal cord imaging.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1920
    Keywords: Magnetic resonance imaging ; Fast spin-echo ; Multiple sclerosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Long repetition time (TR) spin-echo (SE) with T2- or proton density weighting is the sequence of choice to detect the brain lesions of multiple sclerosis (MS). Fast spin-echo (FSE) permits the generation of T2-weighted images with similar contrast to SE but in a fraction of the time. We compared the sensitivity of FSE and SE in the detection of the brain lesions of MS. Six patients with clinically definite MS underwent brain imaging with both dual echo (long TR, long and short echo time (TE) SE and dual echo FSE. The SE and FSE images were first reviewed independently and then compared. A total of 404 lesions was detected on SE and 398 on FSE. Slightly more periventricular lesions were detected using SE than FSE (145 vs 127), whereas more posterior cranial fossa lesions were detected by FSE (77 vs 57). With both SE and FSE the short TE images revealed more lesions than the long echo. These results suggest that FSE could replace SE as the long TR sequence of choice in the investigation of MS.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1920
    Keywords: Magnetic resonance imaging ; Arteriovenous malformations ; Spinal cord ; Contrast media
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Arteriovenous fistulae and malformations (AVFs and AVMs) of the spinal cord are rare, potentially treatable causes of progressive disability. Although a variety of MRI abnormalities has been described, the diagnosis rests on the findings on selective spinal angiography.Collecting T2*-weighted MR images during the passage of a gadolinium bolus gives information about perfusion and blood volume. We carried out dynamic MRI in seven patients with vascular abnormalities (5 dural AVFs, 1 intramedullary AVM, 1 cryptic angioma) and in two patients without an AVM. High resolution T1- and T2-weighted sagittal images of the whole spinal cord were first obtained using a multiarray receiver coil. Sagittal radiofrequency spoilt gradient echo images (GE34/25, flip angle 100) were then obtained during bolus injection of gadolinium-DTPA. Abnormalities were seen in all seven patients with AVFs or AVMs. In the patient with an intramedullary AVM and four of the five with dural AVFs transient signal reduction was seen within the perimedullary venous plexus during passage of the bolus. The findings correlated well with those from selective spinal angiography. We conclude that dynamic MRI offers a useful adjunct to angiography and may localise an arteriovenous shunt when conventional MRI fails to do so. In combination with high-resolution imaging of the entire spinal cord the technique may make myelography redundant; it is simple, well tolerated and can be carried out without significant time penalty.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-1920
    Keywords: Magnetic resonance imaging ; Fast spin-echo ; STIR ; Fat suppression ; Optic neuritis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Fast spin-echo (FSE) is a new sequence with acquisition times currently down to one-sixteenth of those obtained with conventional spin-echo sequences, which allows high-resolution (512×512 matrix) images to be acquired in an acceptable time. We compared the higher resolution of FSE with the medium resolution of a short inversion-time inversion-recovery (STIR) sequence in depicting the optic nerves of healthy controls and patients with optic neuritis. Optic nerve MRI examinations were performed in 18 patients with optic neuritis and 10 normal controls. Two sequences were obtained coronally: fat-suppressed FSE (FSE TR 3250 ms/TEef 68 ms, echo-train length 16, 4 excitations, 24 cm rectangular field of view, 3 mm interleaved contiguous slices, in-plane resolution 0.5×0.5 mm) and STIR (TR 2000 ms/TE 50 ms/TI 175 ms, inplane resolution 0.8×0.8 mm, slice thickness 5 mm). FSE demonstrated much more anatomical detail than STIR, e. g. distinction of optic nerve and sheath. Lesions were seen in 20 of 21 symptomatic nerves using FSE and in 18 of 21 using STIR. Nerve swelling or partial cross-sectional lesions of the optic nerve were each seen only on FSE in 3 cases. Fatsuppressed FSE imaging of the optic nerve improves anatomical definition and increases lesion detection in optic neuritis.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1432-1920
    Keywords: Key words Magnetic resonance imaging ; Fast spin-echo ; STIR ; Fat suppression ; Optic neuritis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Fast spin-echo (FSE) is a new sequence with acquisition times currently down to one-sixteenth of those obtained with conventional spin-echo sequences, which allows high-resolution (512 × 512 matrix) images to be acquired in an acceptable time. We compared the higher resolution of FSE with the medium resolution of a short inversion-time inversion-recovery (STIR) sequence in depicting the optic nerves of healthy controls and patients with optic neuritis. Optic nerve MRI examinations were performed in 18 patients with optic neuritis and 10 normal controls. Two sequences were obtained coronally: fat-suppressed FSE (FSE TR 3250 ms/TEef 68 ms, echo-train length 16, 4 excitations, 24 cm rectangular field of view, 3 mm interleaved contiguous slices, in-plane resolution 0.5 × 0.5 mm) and STIR (TR 2000 ms/TE 50 ms/TI 175 ms, in-plane resolution 0.8 × 0.8 mm, slice thickness 5 mm). FSE demonstrated much more anatomical detail than STIR, e. g. distinction of optic nerve and sheath. Lesions were seen in 20 of 21 symptomatic nerves using FSE and in 18 of 21 using STIR. Nerve swelling or partial cross-sectional lesions of the optic nerve were each seen only on FSE in 3 cases. Fat-suppressed FSE imaging of the optic nerve improves anatomical definition and increases lesion detection in optic neuritis.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-1920
    Keywords: Key words Magnetic resonance spectroscopy ; Spinal cord ; Multiple sclerosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Magnetic resonance spectroscopy (MRS) has been used in a variety of conditions affecting the central nervous system. Until now, only the brain has been studied, and spectroscopy of the spinal cord has not been previously reported. During the past 12 months, we have been experimenting with MRS of the cervical spinal cord of healthy volunteers. We present this technique, its current limitations, and possible future technological improvements and potential applications.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-1920
    Keywords: Key words Multiple sclerosis ; Magnetic resonance imaging ; Pulse sequences ; Echo-planar imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We used five MRI sequences in six patients with multiple sclerosis (MS): conventional spin-echo (CSE) with 5-mm slices; 2D fast spin-echo (FSE) with 2-mm slices; multishot T2*-weighted echo-planar imaging (EPI) with 5-mm slices; fast fluid-attenuated inversion recovery (fFLAIR) with 2-mm slices; and 3D fast spin-echo with 1.5-mm-thick slices. A total of 225 lesions were detected on CSE, 274 on 2D FSE, 137 on EPI, 385 on fFLAIR and 320 on 3D FSE. The EPI sequence was clearly the least sensitive and susceptibility artefact was a problem, particularly in the brain stem and temporal lobes. Fast FLAIR displayed a much higher number of supratentorial lesions (380) than 3D FSE (297), 2D FSE (264) or CSE (211). However, in the posterior cranial fossa 3D FSE was the most sensitive sequence (23 lesions), followed by CSE (14) and 2D FSE (10), while fFLAIR (5) was extremely insensitive.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1432-1920
    Keywords: Key words Magnetic resonance imaging ; Benign intracranial hypertension ; Papilloedema ; Optic nerve
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We investigated the MRI appearance of the optic nerve and its cerebrospinal-fluid-containing sheath in 17 patients with benign intracranial hypertension (BIH) and 15 normal controls. Using phased-array local coils, 3-mm coronal T2-weighted fat-suppressed fast spin-echo images were obtained with an in-plane resolution of 〈 0.39 mm. The optic nerve and its sheath were clearly differentiated. An enlarged, elongated subarachnoid space around the optic nerve was demonstrated in patients with BIH. High-resolution MRI of the optic nerve offers additional information which may be of value for diagnosis and in planning and monitoring treatment.
    Type of Medium: Electronic Resource
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