Susceptibility-Weighted Imaging of the Brain: Current Utility and Potential Applications

Abstract

SWI is an extremely useful adjunct to current MRI sequences of the brain and is advocated for inclusion into routine Neuroimaging protocols.

Improved T2* Imaging without Increase in Scan Time: SWI Processing of 2D Gradient Echo

“…Furthermore, 2D SWI/PU images can help distinguish calcification from hemorrhage, similar to 3D SWI. 13,18 While prior work by Haacke et al and Sehgal et al 3,18 suggested that 2D GRE acquisitions result in rapid dephasing across voxels that could inhibit the additional T2* visualization achieved with 3D GRE acquisitions of SWI, our results suggest that phase information derived from 2D GRE images has the capacity to produce 2D SWI/PU images that are superior to standard 2D GRE images. A few pitfalls of 2D SWI were noted.…”

“…3 SWI better accentuates the paramagnetic properties of blood products than 2D GRE imaging and adds the ability to distinguish blood products from calcification. While SWI has shown clinical utility in the evaluation of hemorrhage, arterial venous malformations, small vessel diseases, amyloid angiopathy, cavernous malformations, multiple sclerosis, trauma, tumors, and hemosiderosis, [3][4][5][6][7][8][9][10][11][12][13] routine clinical implementation may be difficult due to the longer acquisition time (between 5 and 10 minutes [3][4][5][14][15][16][17] ), particularly in children who are motionprone and often require sedation.…”

Simultaneous Arteriovenous Shunting and Venous Congestion Identification in Dural Arteriovenous Fistulas Using Susceptibility-Weighted Imaging: Initial Experience

“…Subcortical calcifications in DAVFs 23,24 could also be identified on SWI by the use of filtered-phase images. 25,26 Among the disadvantages of SWI is its vulnerability to susceptibility artifacts present at the skull base, as seen in 1 of our cases. Another caveat for SWI in the diagnosis of DAVF is the possibility of fistula obscuration by blood-degradation products as seen in 1 instance in the report from Noguchi et al 8 However, in the series from Jagadeesan et al, 10 the depiction of arteriovenous shunt surgery was paradoxically higher in cases of intracerebral hematoma compared with cases without hemorrhage.…”

“…25,27 Transient unilateral venous prominence has also been described in migraines. 28,29 Venous congestion secondary to venous thrombosis can also lead to dilated collateral veins, 25,26,30 but contrary to arterialized veins in DAVFs, the thrombosed veins should appear hypointense from susceptibility effects. 31 This latter pattern should prompt further evaluation with MR venography because the distinction between patent and thrombosed veins could be difficult on SWI.…”

Differentiation of Pyogenic Brain Abscesses from Necrotic Glioblastomas with Use of Susceptibility-Weighted Imaging

“…8 Its high sensitivity in the detection of paramagnetic and diamagnetic substances such as iron deposits, blood-degradation products, and calcifications provides clinically useful information in the evaluation of various disorders, including neurodegenerative disease, cerebral neoplasm, trauma, demyelination, vascular malformation, and intracranial hemorrhage. 9 In pictorial essays illustrating the clinical utility of SWI, 10,11 brain abscesses were described as having a markedly hypointense rim. The contrast between the hypointense rims and the abscess cavities as well as the surrounding edema was higher compared with FSE T2WI.…”