الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Susceptibility-weighted imaging (SWI) is a new technique that exploits the magnetic susceptibility among various tissues, it relies on utilization of a high resolution, three dimensional fully flow compensated gradient echo sequence. A phase image is utilized to create a phase mask, after filtering; the phase mask is multiplied by the magnitude image giving the final image which is viewed in minimal intensity projection (minIP) to increase the conspicuity of the smaller veins and other sources of susceptibility effects.
Both calcification and hemorrhage appear as hypointense foci on SWI, known as blooming. Phase image can differentiate between hemorrhage and calcification in a left handed MR system.
This study aimed to assess the role of susceptibility-weighted imaging using the post processing phase image to differentiate between intracranial hemorrhage and calcification.
All patients were subjected to the following:
o History taking.
o Thorough clinical examination.
o Conventional MRI study of the brain.
o Susceptibility-weighted imaging of the brain with post processing phase image.
The study was applied on a 1.5 Tesla Magnetom Avanto Siemens (left handed system) machine using conventional MRI sequences in addition to SWI using the phase image and confirmed by non-enhanced contrast CT.
50 cases were selected and they showed total of 170 lesions, including: brain tumors, microbleeds, cavernomas, intracranial hemorrhage and cases with cortical/subependymal calcifications. 16/50 cases showed hypointense phase signal (28/170) lesions, 21/50 cases showed hyperintense phase signal (85/170) lesions, 13/50 cases showed heterogeneous phase signal (57/170) lesions.
SWI/phase was successful in differentiating hemorrhage and calcification in 113/170 (67%) of the lesions (size less than 1cm), included whole lesions and intralesional foci. Hypointense phase lesions were 28/170 (17%) and their CT showed calcification, while hyperintense phase lesions were 85/170 (50%) and their CT showed hemorrhage in 23/85 and showed negative results in 62/85 of the lesions.
The remaining 57/170 (33%) of the lesions (with size more than 1cm) showed heterogeneous signal known also as aliasing artifact. Their confirmatory CT showed some calcific lesions in 4/57, hemorrhagic lesions in 5/57, negative CT findings in 22/57 and mixed calcific/blood products in 26/57 lesions. Large size, as well as extra-axial lesions and lesions with mixed blood and calcific products as cavernomas, contributed also to heterogeneous phase signal.
CT was the confirmatory reference we used in the current study. It showed negative findings in total of 84/170 (49%) of the lesions, namely small cavernomas and microbleeds. It detected all calcific lesions; it remains the gold standard in detecting calcification.