| 1. |
- Lätt, Jimmy, et al.
(author)
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In vivo visualization of displacement-distribution-derived parameters in q-space imaging.
- 2008
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In: Magnetic Resonance Imaging. - : Elsevier BV. - 1873-5894 .- 0730-725X. ; 26:1, s. 77-87
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Journal article (peer-reviewed)abstract
- Objective This study aimed to explore the potential of in vivo q-space imaging in the differentiation between different cerebral water components. Materials and Methods Diffusion-weighted imaging was performed in six directions with 32 equally spaced q values and a maximum b value of 6600 s/mm2. The shape of the signal-attenuation curve and the displacement propagator were examined and compared with a normal distribution using the kurtosis parameter. Maps displaying kurtosis, fast and slow components of the apparent diffusion coefficients, fractional anisotropy and directional diffusion were calculated. The displacement propagator was further described by the full width at half and at tenth maximum and by the probability density of zero displacement P(0). Three healthy volunteers and three patients with previously diagnosed multiple sclerosis (MS) were examined. Results Simulations indicated that the kurtosis of a signal-attenuation curve can determine if more than one water component is present and that care must be taken to select an appropriate threshold. It was possible to distinguish MS plaques in both signal and diffusional kurtosis maps, and in one patient, plaques of different degree of demyelinization showed different behavior. Discussion Our results indicate that in vivo q-space analysis is a potential tool for the assessment of different cerebral water components, and it might extend the diagnostic interpretation of data from diffusion magnetic resonance imaging.
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| 2. |
- Ramgren, Birgitta, et al.
(author)
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Follow-up of intracranial aneurysms treated with detachable coils: comparison of 3D inflow MRA at 3T and 1.5T and contrast-enhanced MRA at 3T with DSA.
- 2008
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In: Neuroradiology. - : Springer Science and Business Media LLC. - 1432-1920 .- 0028-3940. ; 50, s. 947-954
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Journal article (peer-reviewed)abstract
- INTRODUCTION: The purpose of this prospective study was to compare 3T and 1.5T magnetic resonance angiography (MRA) with digital subtraction angiography (DSA) for the follow-up of endovascular treated intracranial aneurysms to assess the grade of occlusion. MATERIALS AND METHODS: Thirty-seven patients with 41 aneurysms who had undergone endovascular treatment with detachable coils were included. MRA was performed on the same day using an eight-channel sensitivity encoding head-coil with 3D axial inflow technique. At 3T, a contrast-enhanced transverse 3D fast gradient echo acquisition was also performed. Most patients underwent DSA the following day. MRA scans and DSA were classified first independently by two neuroradiologists and an interventional neuroradiologist. Secondly, a consensus was done. Source images, maximum intensity projection, multiplanar reconstruction and volume rendering reconstructions were used for MRA evaluations. A modification of the Raymond classification, previously used for DSA evaluation of recanalization, was used. RESULTS: Statistical comparison of the consensus showed that 3T MRA with 3D axial inflow technique had better agreement with DSA (kappa = 0.43) than 1.5T MRA(kappa = 0.21) and contrast-enhanced MRA (CE-MRA) at 3T (kappa = 0.17). The susceptibility artefacts from the coil mesh were significally smaller at 3T (p = 0.002-0.007) than at 1.5T. CONCLUSION: 3T MRA, using a sensitivity encoding head-coil, showed better agreement with DSA than 1.5T and CE-MRA at 3T for evaluation of aneurysms treated with endovascular coiling.
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| 3. |
- Strandberg, Maria, et al.
(author)
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Pre-surgical epilepsy evaluation using 3T MRI. Do surface coils provide additional information?
- 2008
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In: Epileptic Disorders. - 1294-9361. ; 10:2, s. 83-92
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Journal article (peer-reviewed)abstract
- Purpose. To assess if 3T MRI can be further improved by adding surface coil imaging, in the context of detection and characterization of cerebral lesions in patients with drug-resistant epilepsy. Methods. Twenty five patients with drug-resistant epilepsy undergoing evaluation for epilepsy surgery were examined with high resolution 3T MRI. The patients were MRI-negative (n = 15), or had unclear findings (n = 10), on previous MRI at 1.0-1.5T. Surface coils were applied over the suspected epileptogenic zone after imaging in the head coil. In MRI-negative patients, placement of the coils was defined by semiological analysis, extracranial video-EEG, and, in selected cases, subtraction ictal SPECT co-registered with MRI and PET. Coil placement was re-analyzed and graded, based on the degree of convergence between different investigational modalities. Results. Surface coil MRI allowed visualization of the cortical lesions with somewhat better demarcation and detail, but did not contribute to detection of previously undiagnosed lesions and did not provide additional information regarding type of lesion. Possible epileptogenic lesions were detected on 3T MRI in 12 patients. No abnormalities were found in the remaining 13 patients. 3T MRI provided new or additional information about the cortex, compared with reports from previous 1.0-1.5T MRI in 5 patients (20%). Conclusion. 3T MRI with high resolution is valuable for lesion detection, especially MCD, in patients with drug-resistant epilepsy. We question the additional contribution from supplementary surface coil imaging at 3T MRI.
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| 4. |
- Svensson, Per-Ake, et al.
(author)
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Infratentorial progressive multifocal leucoencephalopathy (PML) in a patient with SLE (2008: 4b).
- 2008
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In: European Radiology. - : Springer Science and Business Media LLC. - 0938-7994 .- 1432-1084. ; 18:7, s. 1526-1528
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Journal article (peer-reviewed)abstract
- Progressive multifocal leucoencephalopathy (PML) is a viral infection occurring in immunocompromised patients. The typical magnetic resonance imaging (MRI) findings include supratentorial asymmetric nonenhancing white matter lesions without mass effect. We present a patient with progressive cerebellar and brain stem lesions, emphasizing the fact that the diagnosis of PML should be considered also in cases with selective infratentorial involvement.
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