Susceptibility-Weighted Imaging in the Diagnosis of Isolated Cortical Vein Thrombosis

Abstract

globin serves as an intrinsic contrast agent for cerebral veins which contain deoxygenated blood. Other extravascular blood degradation products with paramagnetic properties such as methemoglobin, hemosiderin and ferritin also create a contrast in SWI. In this sequence in order to increase the visualization of the smaller veins, a phase mask obtained from the magnetic resonance (MR) phase images is multiplied with magnitude images. After the postprocessing, susceptibility-weighted images can be displayed with the minimal intensity projection algorithm [2, 3] . SWI has become a useful method to evaluate cerebral venous sinus and isolated cortical vein thromboses by depicting direct signs of thrombus and demonstrating indirect signs such as venous stasis and collateral slow flow. Cortical vein thrombosis causes an increase of the deoxyhemoglobin concentration in the involved veins. This clearly and distinctly appears as prominent hypointense signal intensity in the affected vein on SWI [4] . The comprehensive study performed by Idbaih et al. [5] showed that T2 * SW is of additional diagnostic value for clot detection in cerebral vein thrombosis in conjunction with conventional MRI and MR venography, particularly in the acute phase of thrombosis and in cortical cerebral vein thrombosis. They also stated that conventional MRI sequences and MR venography techniques are usually insuffiDear Sir, We read the recent article entitled ‘Isolated cortical vein thrombosis: a widely variable clinicoradiological spectrum’ by Xue et al. [1] , published in European Neurology , with great interest. The authors evaluated the variable clinicoradiological spectrum of isolated cortical vein thrombosis, which is a clinicoradiological diagnostic challenge. They concluded that neurological features and brain imaging findings of isolated cortical vein thrombosis are highly variable, which might be partly responsible for the underestimation of isolated cortical vein thrombosis. Moreover, the authors stated that direct signs of thrombosis on computed tomography and magnetic resonance imaging (MRI) may be subtle or missing, and even digital subtraction angiography may fail to detect them because of a variation in number, size and location of the cortical veins. At this point, we would like to make a suggestion regarding the usefulness of susceptibility-weighted imaging (SWI) which is a relatively new MRI sequence and seems to be helpful in the early and easy diagnosis of isolated cortical vein thrombosis. SWI is a new MRI technique that is based on high-spatial-resolution, three-dimensional, fully flow-compensated gradient-echo sequences using both magnitude and phase information. The cerebral venous visualization is based the paramagnetic effects of deoxyhemoglobin due to full flow compensation. The deoxyhemoReceived: August 2, 2013 Accepted: September 22, 2013 Published online: December 4, 2013