| 1. |
- Brockstedt, Sara, et al.
(författare)
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Vertical field MR imaging of upper thorax and spine in small children. Evaluation of a new surface coil
- 1993
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Ingår i: Acta Radiologica. - 1600-0455. ; 34:6, s. 549-553
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Tidskriftsartikel (refereegranskat)abstract
- To improve image quality in a vertical field MR imaging unit, operating at low field strength (0.3 T), we have designed a half-elliptical coil for use in the upper thoracic region of small children. Our intention was also to shorten the examination time, which until now has been long, because several scans with different coils have been necessary to cover the thoracic region. The experimental coil is designed so that a child's shoulders fit into the central region. The coil consists of 2 serially connected cable-loops, mounted on a foam rubber vest. The coil performance was tested in a phantom and improvements relative to standard coils were demonstrated in in vivo studies. The results indicate that by using the half-elliptical coil, the signal-to-noise (S/N) ratio can be improved by a factor of 2 to 3 in the thoracic region of a child.
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| 2. |
- Cronqvist, Mats, et al.
(författare)
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Diffusion and perfusion MRI in patients with ruptured and unruptured intracranial aneurysms treated by endovascular coiling: complications, procedural results, MR findings and clinical outcome.
- 2005
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Ingår i: Neuroradiology. - : Springer Science and Business Media LLC. - 1432-1920 .- 0028-3940. ; 47:11, s. 855-873
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Tidskriftsartikel (refereegranskat)abstract
- Our purpose was to evaluate treatment safety as well as complications frequency and management in endovascular coiling of intracerebral aneurysms using MR diffusion and perfusion imaging. In this prospective study, 77 MR examinations were performed in conjunction with 43 procedures in 40 patients, 14 patients presented with ruptured and 26 with unruptured aneurysms. Mean time interval between treatment and post-procedure MRI was 29 and 25 h for the ruptured and unruptured aneurysm group, respectively. Peri-procedural complications, including five major events and five minor transient events, occurred in 10/43 procedures (23%), necessitating thrombolytic therapy in two patients and angioplasty in one, all three within the unruptured aneurysm group. Fifty-one new lesions were found on post-treatment DWI and 47 of them were regarded as of ischemic origin. Most lesions were small (< 3 mm), ipsilateral to the treated aneurysm and asymptomatic (37/40 patients). Sixty-seven percent of the lesions were found in the ruptured and 33% in the unruptured aneurysm group. The ischemic lesions did occur more frequently in patients treated for aneurysm of large neck size and according to the remodelling technique. The overall morbidity and mortality rates were 14.6 and 7.3% whereas morbidity and mortality rates related to the technique were only 2.6 and 0%, respectively. Silent embolism seems to be more common than clinically evident and partially related to patient presentation, heparinazation and treatment strategy. The capability to depict early complications and analyse their potential causes by using MR with DWI has been of great importance in our modification and improvement of therapeutic protocols, evaluations and strategies.
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| 3. |
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| 4. |
- Larsson, Elna-Marie, et al.
(författare)
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Aortic pathology revealed by MRI in patients with clinical suspicion of spinal disease
- 1993
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Ingår i: Neuroradiology. - 1432-1920. ; 35:7, s. 499-502
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Tidskriftsartikel (refereegranskat)abstract
- In five patients with clinical suspicion of spinal disease, MRI of the spine revealed unexpected aortic pathology explaining the symptoms. No significant intraspinal pathology was found on MRI. However, in one patient with clinical suspicion of spinal stenosis, an aortic occlusion was detected on MR images of the spine. The lower extremity ischaemia, caused by the occlusion, was responsible for the symptoms. In another patient a paravertebral haematoma from a ruptured aortic aneurysm resulted in spinal nerve compression, thought before MRI to be caused by a spinal tumour. In three patients aortic aneurysm or dissection resulted in spinal cord ischaemia with symptoms mimicking those of compressive spinal disease. Thus, if MRI of the spine does not provide an explanation for the patient's symptoms, examination of the aorta is recommended.
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| 5. |
- Li, M H, et al.
(författare)
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MRI of extradural spinal tumours at 0.3 T
- 1993
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Ingår i: Neuroradiology. - 1432-1920. ; 35:5, s. 370-374
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Tidskriftsartikel (refereegranskat)abstract
- Ninety-one patients with extradural spinal tumours were examined by magnetic resonance imaging. There were 76 metastases (6 from unknown primary tumours). Seven patients had primary spinal tumours and 8 had multiple myeloma. Sixteen had bulging, diseased vertebral bodies compressing the subarachnoid space and 67 had extradural tumour compressing the spinal cord. Sixty patients had paravertebral involvement. Intraspinal involvement did not correlate with the extent of spinal lesions. All patients had vertebral destruction, with hypointense or combined hypo- and isointense signal relative to bone marrow on T1-weighted images. In most of the 22 patients with T2-weighted images the tumours were isointense or slightly hyperintense. It was usually impossible to differentiate the various tumours on the basis of signal intensity and morphology. However, metastases from carcinoma of the prostate were often more hypointense than other tumours on T1- and T2-weighted images. An inhomogeneous pattern in which diffusely low signal is combined with focal lower signal on T1-weighted images may suggest myeloma. In the 22 patients examined with both T1- and T2-weighted images, T1-weighted images gave the best information in 18; in 3 they were equivalent and in 1 inferior to T2-weighted images; they are therefore recommended for routine imaging of epidural spinal tumours.
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| 6. |
- Lundborg, Göran, et al.
(författare)
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Hand-Arm-Vibration Syndrome (HAVS): Is there a central nervous component? An fMRI study.
- 2002
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Ingår i: Journal of Hand Surgery (British Volume). - : SAGE Publications. - 0266-7681. ; 27:6, s. 514-519
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Tidskriftsartikel (refereegranskat)abstract
- Hand-held vibrating tools may result in neuromuscular dysfunction and vasospastic problems of the hand. Sensory and motor dysfunction can be explained by injury to peripheral structures, but could also be due to changes in cortical somatotopic mapping of the hand in the brain. The purpose of the present study was to use functional magnetic resonance imaging (fMRI) to assess the somatotopic cortical representation of the hands of workers subjected to occupational vibration. The study included six men with severe vibration exposures who were suffering from hand-arm-vibration syndrome (HAVS) and six controls. The analysis focused on the pattern and degree of activation of contra- and ipsilateral hemispheres of the brain with tactile stimulation and motor activation of the hand. These stimulations resulted in well-defined activation of the contralateral, and to a lesser extent the ipsilateral hemisphere. Statistical analysis of this limited patient material did not indicate any significant somatotopic cortical changes following long-term exposure to vibrating hand-held tools, although there was a tendency to a shift of activation towards the more cranial parts of the cortex in the patient group.
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| 7. |
- Malmgren, Lars, et al.
(författare)
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Improved receiver coil for upper thoracic spine imaging in a vertical magnetic field
- 1992
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Ingår i: Journal of Magnetic Resonance Imaging. - : Wiley. - 1522-2586 .- 1053-1807. ; 2:2, s. 191-195
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Tidskriftsartikel (refereegranskat)abstract
- To improve image quality in the upper thoracic spine, an anatomically shaped copper wire loop coil, made to fit over the patient's shoulders, was constructed. The coil was permanently mounted on a foam-rubber vest to facilitate attachment to the patient. Phantom and in vivo studies of the performance of the coil in healthy volunteers showed as much as a two times greater signal-to-noise ratio relative to that of standard coils for the upper thoracic spine. In a patient with lesions in the upper thoracic cord, the coil gave better image quality in the region of interest than did the standard coils. The coil has been integrated into the authors' routine imaging equipment and has been the coil of choice for imaging of the upper thoracic spine on their 0.3-T vertical field system.
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| 8. |
- Ramgren, Birgitta, et al.
(författare)
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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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Ingår i: Neuroradiology. - : Springer Science and Business Media LLC. - 1432-1920 .- 0028-3940. ; 50, s. 947-954
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Tidskriftsartikel (refereegranskat)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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| 9. |
- Ramgren, B, et al.
(författare)
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Vertebrobasilar dissection with subarachnoid hemorrhage: a retrospective study of 29 patients.
- 2005
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Ingår i: Neuroradiology. - : Springer Science and Business Media LLC. - 1432-1920 .- 0028-3940. ; 47:2, s. 97-104
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Tidskriftsartikel (refereegranskat)abstract
- We have reviewed initial diagnostic features, treatment, and outcome in 29 patients with acute subarachnoid hemorrhage due to non-traumatic vertebrobasilar artery dissection diagnosed in our hospital between 1993 and 2003. The dissections occurred in the vertebral artery in 19 patients, the posterior inferior cerebellar artery ( PICA) in two patients, the basilar artery in four patients, and in the vertebral artery extending into the PICA in four patients. A pseudoaneurysm was found in 20 patients. Clinical manifestations typically included sudden onset of moderate to severe headache, nuchal rigidity, and drowsiness. Fourteen patients were treated conservatively. Fifteen patients underwent endovascular treatment with either parent artery occlusion ( 13 patients) or aneurysmal coil occlusion with preservation of the parent artery ( 2 patients). Re-bleeding occurred within 12 days and before treatment in nine patients. Eight of these had a pseudoaneurysm. No patient bled after endovascular treatment. Poor grade and early re-bleeding were associated with less favorable outcome. Outcome at 6 months did not differ significantly between endovascular and conservative treatment. Altogether, good recovery was achieved for 16 patients, moderate disability was seen in one, severe disability in four, and eight patients ( 27%) died. The absence of bleeding subsequent to endovascular treatment in this study suggests that endovascular treatment may be a rational approach in these patients at high risk of re-bleeding, especially those with a pseudoaneurysm.
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| 10. |
- Sundgren, PC, et al.
(författare)
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Carotid artery stenosis: contrast-enhanced MR angiography with two different scan times compared with digital subtraction angiography
- 2002
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Ingår i: Neuroradiology. - : Springer Science and Business Media LLC. - 1432-1920 .- 0028-3940. ; 44:7, s. 592-599
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Tidskriftsartikel (refereegranskat)abstract
- Contrast enhanced magnetic resonance angiography (CE MRA) is a non-invasive alternative to conventional digital subtraction angiography (DSA). CE MRA is increasingly used as a complement to Duplex in the preoperative assessment of carotid artery stenosis. The purpose of this study was to determine if CE MRA could replace preoperative DSA. CE MRA with a scan time of 10 or 28 s was performed in 24 consecutive patients who were scheduled for preoperative DSA because of Duplex-verified severe carotid artery stenosis. Two neuroradiologists measured the degree of stenosis with three different methods, and the image quality was evaluated. DSA was used as the gold standard. For detection of severe stenosis (N. American symptomatic carotid endarterectomy trial (NASCET) greater than or equal to70%; European symptomatic carotid endarterectomy trial (ECST) greater than or equal to80%; common carotid artery method (CCAM) greater than or equal to80%), the sensitivity of CE MRA maximum intensity projection (MIP) compared with DSA was 82%-100%, the specificity was 74%-93% and the accuracy was 77%-90%. The inter-observer agreement was higher, the image quality was better and the intracranial main arteries were better visualized with the 28 s than with the 10 s scan time. The enhancement of the jugular veins seen in 17% of the 10 s scans and in 58% of the patients with the 28 s scans did not interfere with the evaluation of the carotid arteries. CE MRA, preferably with a scan time of 28 s, can replace DSA in the preoperative assessment of most patients with carotid artery stenosis.
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