Clinical Values Of Susceptibility Weighted Imaging In Brain

PART ONE MANIFESTATIONS OF SUSCEPTIBILITY WEIGHTED IMAGING IN NORMAL BRAINOBJECTIVES: To evaluate the manifestations of SWI in normal brain by comparison SWI with conventional MRI sequences.MATERIALS AND METHODS: Twenty healthy volunteers were recruited into this research. They underwent routine MRI including T1WI, T2WI ,T2FLAIR and SWI. Of them, 6 underwent enhancement MRI scan. The whole brain SWI was performed before and after contrast. SWI scan resulted in the magnitude image and phase image. Original images of SWI were transmitted to the work station (AW4.1) provided by GE, and Functool software was employed to process the data. After filtering of phase image and phase masking of magnitude image, 20mm thickness minimum intensity projection (MinIP) was used to reconstruct the SWI images for analysis.RESULTS: Clear SWI images of 20 healthy volunteers were gained. Compared with the conventional MRI images (T1WI, T2WI and T2FLAIR), SWI showed better contrast of gray matter and white matter. The signal of cerebrospinal fluid was inhibited like T2FLAIR on SWI. Cerebral veins were clearly demonstrated on SWI reconstructed by MinIP including the slim linear low signals alone the sulci standing for the superficial cerebral veins and streak-like low signals in basal ganglia region representing deep cerebral veins. Normal intracerebral iron deposition was demonstrated in all volunteers showing the symmetrically distributed low signals in basal ganglia region and midbrain. Band-like low signal alone the cortex shown on SWI stood for the iron deposition in cortex.CONCLUSION: SWI is very sensitive to small veins and iron deposition of brain. It can show venous system of normal brain clearly and monitor the changes of distribution and concentration of normal brain iron deposition.PART TWO CLINICAL VALUES OF SUSCEPTIBILITY WEIGHTED IMAGING IN CRANIOCEREBRAL DISEASESOBJECTIVES: To evaluate clinical values of susceptibility weighted imaging (SWI) in craniocerebral diseases.MATERIALS AND METHODS: A total of 54 cases from May 2007 to March 2008 with craniocerebral diseases proved by pathology and radiology included 18 cerebral infarctions, 15 hemorrhage, 2 cerebral venous malformations, 8 gliomas, 6 meningiomas and 5 metastatic tumors. They underwent routine MRI( T1WI, T2WI and T2FLAIR) and SWI. Of them, 37 underwent DWI, 18 underwent MRA, 2 underwent MRV and 19 underwent pre- and post-contrast SWI. SWI images were analyzed to evaluate the diagnostic values of SWI in craniocerebral diseases.RESULTS: Eighteen patients had cerebral infarctions including 13 lacular infarctions and 5 large cerebral infarctions. Of them, SWI showed hemorrhage inside infarction in 3 patients and the thrombi in the affected cerebral artery in 4 patients. Of 15 patients with intracerebral hemorrhage, 12 were detected by conventional MRI and SWI demonstrated all showing iso or high signal in the central part with peripheral low signal including 3 cases with new hemorrhage. 2 patients with cerebral venous malformations showed linear long T2 signal on conventional MRI image, MRV failed to show it. SWI demonstrated the malformation and the draining veins. In the 19 patients with brain tumors, SWI showed the hemorrhage inside the tumors in 10 patients, which could not be clearly displayed by conventional MRI. SWI also displayed the venula and calcification inside the tumors in 8 and 4 patients respectively. Furthermore it showed the peripheral edema and the details of vein compression of tumors.CONCLUSION: SWI is more advanced than conventional MRI in detecting the early bleeding and infarction accompanying with bleeding. It can clearly show the malformation and the draining veins of the cerebral venous malformation, the inside tumors'structures and its peripheral changes. Combined with conventional MRI, SWI plays an important role in diagnosing the craniocerebral diseases more precisely.