1.
Sundgren, PC, et al.
(författare)
Carotid artery stenosis: contrast-enhanced MR angiography with two different scan times compared with digital subtraction angiography
2002
Ingår i: Neuroradiology. - : Springer Science and Business Media LLC. - 1432-1920 .- 0028-3940. ; 44:7, s. 592-599
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.
2.
Brockstedt, Sara, et al.
(författare)
SchnelleMagnetresonanz-Bildgebung
2002
Ingår i: Radiologie Up2Date. - : Georg Thieme Verlag KG. - 1616-0681 .- 1617-8300. ; :4, s. 413-438
Tidskriftsartikel (refereegranskat) abstract
Abstract in German Die Verkürzung der Untersuchungszeiten bei der klinischen Magnetresonanztomographie (MRT) bietet für den Patienten den Vorteil einer angenehmeren und schnelleren Untersuchung und erhöht gleichzeitig den Patientendurchsatz. Dies erfordert schnelle und robuste Aufnahmetechniken, welche beispielsweise auch bei der Aufnahme bewegter Organe oder für atemangehaltene Messungen eingesetzt werden können. Durch die Entwicklung leistungsfähiger Gradientensysteme konnten in den letzten Jahren neue und schnelle Pulssequenzen entwickelt werden. Die rasante Entwicklung neuer Aufnahmemethoden und Rekonstruktionstechniken macht es für den Anwender immer wichtiger, die grundlegenden Prinzipien schneller Aufnahmetechniken zu verstehen. In diesem Übersichtsartikel wird versucht, die Grundlagen der schnellen Pulssequenzen und deren klinische Anwendungsbereiche darzustellen. Dies beinhaltet die schnelle Spin-Echo-Technik und deren Kombination mit selektiven Präparationstechniken, die schnelle und ultraschnelle Gradienten-Echo-Technik sowie die echoplanare Bildgebung. Abschließend werden kurz neueste Entwicklungen wie die parallele Bildgebung beschrieben.Zusammenfassung auf S. 434
3.
Cronberg, Carin, et al.
(författare)
Peripheral arterial disease.
2003
Ingår i: Acta Radiologica. - : SAGE Publications. - 1600-0455 .- 0284-1851. ; 44:1, s. 59-66
Tidskriftsartikel (refereegranskat)
4.
Engellau, Lena, et al.
(författare)
Long-term results after endovascular repair of abdominal aortic aneurysms with the Stentor and Vanguard stent-graft.
2004
Ingår i: Acta Radiologica. - : SAGE Publications. - 1600-0455 .- 0284-1851. ; 45:3, s. 275-283
Tidskriftsartikel (refereegranskat) abstract
Purpose: To present a single institution experience of long‐term results after endovascular repair of abdominal aortic aneurysms (AAA) with the Stentor and Vanguard stent‐grafts. Material and Methods: Twenty‐three patients (20 men, 3 women; mean age 68 years, range 53–81 years) were included in this prospective study. A first generation nitinol stent‐graft (Stentor™) was used in 12 patients and a second generation (Vanguard™) in 11 patients. Follow‐up was performed with magnetic resonance imaging (MRI) with contrast‐enhanced MR angiography (CE MRA) at 1, 6, and 12 months, and thereafter annually (median follow‐up 3 years; range 8 months to 8 years). A conventional radiograph of the abdomen was also performed. Before secondary intervention the findings on MRI with CE MRA were confirmed with spiral computed tomography (CT) and/or angiography (DSA). Results: Only one patient (4%) had no complication. Endoleak was found in 15 patients (65%), graft migration in 8 (35%), and graft deformation in 18 (78%). Secondary endovascular repair was required in 7 patients (30%) and 7 (30%) were converted to open repair. Conclusion: Complications with the Stentor and Vanguard stent‐grafts were common. Long‐term follow‐up of endovascularly repaired AAA is mandatory.
5.
6.
Engellau, Lena, et al.
(författare)
MR evaluation ex vivo and in vivo of a covered stent-graft for abdominal aortic aneurysms: ferromagnetism, heating, artifacts, and velocity mapping
2000
Ingår i: Journal of Magnetic Resonance Imaging. - 1522-2586. ; 12:1, s. 112-121
Tidskriftsartikel (refereegranskat) abstract
Magnetic resonance imaging (MRI) safety was evaluated at 1.5 T in a covered nickel titanium stent-graft (Vanguard) used for endovascular treatment of abdominal aortic aneurysms (AAAs). Imaging artifacts were assessed on MRI with contrast-enhanced (CE) three-dimensional (3D) MR angiography (MRA) and spiral computed tomography (CT) in 10 patients as well as ex vivo. Velocity mapping was performed in the suprarenal aorta and femoral arteries in 14 patients before and after stent-graft placement. For comparison it was also performed in six healthy volunteers. No ferromagnetism or heating was detected. Metal artifacts caused minimal image distortion on MRI/MRA. The artifacts disturbed image evaluation on CT at the graft bifurcation and graft limb junction. No significant differences in mean flow were found in patients before and after stent-graft placement. Our study indicates that MRI at 1.5 T may be performed safely in patients with the (Vanguard) stent-graft. MRI/MRA provides diagnostic image information. Velocity mapping is not included in our routine protocol.
7.
Holmqvist, Catarina, et al.
(författare)
Collateral flow in coarctation of the aorta with magnetic resonance velocity mapping: correlation to morphological imaging of collateral vessels.
2002
Ingår i: Journal of Magnetic Resonance Imaging. - : Wiley. - 1522-2586 .- 1053-1807. ; 15:1, s. 39-46
Tidskriftsartikel (refereegranskat) abstract
PURPOSE: To correlate quantification of collateral flow in aortic coarctation with the morphological visualization of the collateral vessels and to compare different approaches to measurement of collateral flow. MATERIALS AND METHODS: Thirteen children with coarctation were examined with T1-weighted spin-echo (T1-W SE) imaging and 3D contrast-enhanced magnetic resonance angiography (MRA). MR velocity mapping was performed at four levels in the descending aorta. RESULTS: The flow immediately above and below the coarctation did not differ significantly. Measuring within the coarctation resulted in flow overestimation. The increase of flow from proximal to distal aorta was 12 +/- 21% in patients with no or uncertain collaterals and 69 +/- 55% in patients with pronounced collaterals. Spin-echo images and MRA were comparable in visualizing collateral vessels. The visual estimation of collaterals correlated reasonably well with flow quantification MR velocity mapping. CONCLUSION: Collateral flow assessment with MR velocity mapping is an accurate technique for evaluating the hemodynamic importance of a coarctation and is recommended if abundant collaterals are not visualized with spin echo or MRA.
8.
9.
Larsson, Elna-Marie, et al.
(författare)
MRI with diffusion tensor imaging post-mortem at 3.0 T in a patient with frontotemporal dementia.
2004
Ingår i: Dementia and Geriatric Cognitive Disorders. - : S. Karger AG. - 1420-8008 .- 1421-9824. ; 17:4, s. 316-319
Tidskriftsartikel (refereegranskat) abstract
The formalin-fixed brain of a patient with clinically diagnosed frontotemporal dementia (FTD) was examined post-mortem using magnetic resonance imaging (MRI) with diffusion tensor imaging (DTI) at 3.0 T. Frontotemporal atrophy as well as bilateral frontal white matter abnormalities were seen. The white matter changes were slightly more extensive on DTI than on conventional MRI. Correlation with histopathology of the corresponding regions revealed typical frontal lobe degeneration of non-Alzheimer type, with mild frontotemporal degeneration in the outer cortical layers and a moderate frontal white matter gliosis with demyelination. Post-mortem MRI/DTI with histopathologic correlation will enhance our understanding of the basis of white matter changes observed in dementia patients and may improve the in vivo MRI/DTI diagnostic assessment in FTD.
10.
Lundborg, Göran, et al.
(författare)
Hand-Arm-Vibration Syndrome (HAVS): Is there a central nervous component? An fMRI study.
2002
Ingår i: Journal of Hand Surgery (British Volume). - : SAGE Publications. - 0266-7681. ; 27:6, s. 514-519
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.
