Clinical Applications of Neuroimaging with Susceptibility Weighted Imaging: Review Article

Abstract

Purpose : Susceptibility-weighted magnetic resonance (MR) sequence is three-dimensional (3D), spoiled gradient-echo pulse sequences that provide a high sensitivity for the detection of blood degradation products, calcifications, and iron deposits. This pictorial review is aimed at illustrating and discussing its main clinical applications. Materials and Methods:SWI is based on high-resolution, 3D, fully velocity-compensated gradient-echo sequences using both magnitude and phase images. To enhance the visibility of the venous structures, the magnitude images are multiplied with a phase mask generated from the filtered phase data, which are displayed at best after post-processing of the 3D dataset with the minimal intensity projection algorithm. A total of 200 patients underwent MR examinations that included SWI on a 3 tesla MR imager were enrolled.Results: SWI is very useful in detecting multiple brain disorders. Among the 200 patients, 80 showed developmental venous anomaly, 22 showed cavernous malformation, 12 showed calcifications in various conditions, 21 showed cerebrovascular accident with susceptibility vessel sign or microbleeds, 52 showed brain tumors, 2 showed diffuse axonal injury, 3 showed arteriovenous malformation, 5 showed dural arteriovenous fistula, 1 showed moyamoya disease, and 2 showed Parkinson's disease. Conclusion:SWI is useful in detecting occult low flow vascular lesions, calcification and microbleed and characterising diverse brain disorders.

High-Resolution Intratumoral Susceptibility Signal (ITSS) as an Adjunctive Imaging Tool in the Evaluation of Treatment Response of Brain Metastases Following Stereotactic Radiosurgery

“…SWI has been investigated to predict brain tumors, differentiate primary brain tumors and brain metastasis, and differentiate brain metastases. 19,37,39,48 Radbruch, et al have investigated quantitative measurement of SWI using percentagewise quantification for the discrimination of intracerebral metastases. They found excellent diagnostic performance of the PQ of ITSS to differentiate malignant melanoma and breast carcinoma (AUC= 0.96; 95% CI 0.9 -1.0).…”

“…18 Spoiled gradientecho sequences use both magnitude and phase images, which provide high sensitivity for the detection of blood degradation products, calcifications, and iron deposits. 19 High-resolution SWI provides visualization of small vessels, can detect iron deposition, and can generate image contrast depending on magnetic susceptibility differences in tissues. 18 The phase images further help to differentiate between paramagnetic materials like iron which have strong positive susceptibility phase, from diamagnetic materials like calcium which have negative susceptibility phase.…”

Cerebral Arteriovenous Malformations (cAVMs): What Is New?

“…Precisely, rates of poor outcome were calculated as follows: S-M grade I = 4% (95% CI, 2-7), S-M grade II = 10% (95% CI, 7-13), S-M [19]. grade III = 18% (95% CI, [15][16][17][18][19][20][21][22], S-M grade IV = 31% (95% CI, 25-37), and S-M grade V = 37% (95% CI, . These results prove that microsurgical resection is suitable for low-grade cAVMs (S-M grades I and II), whereas surgical resection of high-grade cAVMs (S-M grades IV and V) is associated with a high risk of poor patient outcome.…”

“…Most series with long-term follow-up show obliteration in 70-80% of cAVMs and it is achieved within 2-3 years after starting stereotactic radiosurgery ( Table 3) [17,20]. The time between starting radiosurgery and complete obliteration is named the latency period; it varies from 1 to 3 years.…”

“…MRI brain of an adult patient T2-weighted image A and SWI (susceptibility weighted image). B demonstrates right temporal T2WI and DWI serpiginous hypointensity representing AVM[20].…”