Cerebral venous thrombus signal intensity and susceptibility effects on gradient recalled-echo MR imaging

Abstract

Background and purpose: Cerebral venous thrombus (CVT) signal intensity is variable on MR imaging, and the appearance of CVT on gradient recalled-echo (GRE) sequences has been incompletely assessed. This study was performed to evaluate the GRE imaging appearance of CVT in different stages of thrombus evolution and its relationship to signal intensity on other MR pulse sequences.

Materials and methods: The clinical and MR imaging findings in 18 patients with CVT and GRE imaging were reviewed. Sixty-nine thrombosed venous segments were evaluated, and the signal intensity of thrombus relative to gray matter was determined. The degree of thrombus susceptibility effect (SE) was assessed and related to time of imaging after onset of symptoms (clinical thrombus age) and appearance on other pulse sequences. Segments were classified as SE+ (demonstrating susceptibility effect) or SE- (no susceptibility effect).

Results: Thirty-six venous segments exhibited visible SE. SE+ segments had a clinical thrombus age that was less than that in SE- segments (8.1 versus 24.6 days, P=.003). Sixty-three percent (23/36) of SE+ segments exhibited hypointensity on T2-weighted images (T2WI) versus 12% (4/33) of SE- segments (P<.001). Twenty-nine of 32 (90.6%) segments with clinical thrombus age of 0-7 days were SE+, versus 7 of 30 (23.3%) segments with a thrombus age of 8 days or greater.

Conclusion: SEs from CVT can be detected with GRE imaging and are most prevalent in patients with hypointense thrombus on T2WI within 7 days after the symptom onset. This correlates with the paramagnetic effects of deoxyhemoglobin in acute stage thrombus. GRE imaging may be useful in detecting thrombus in this stage when difficult to detect on other pulse sequences.

Fig 1.

Signal intensity of thrombosed venous segments without susceptibility effect on GRE T2*- weighted sequences. Black, hypointense relative to gray matter; gray, isointense to gray matter; white, hyperintense to gray matter.

Fig 2.

Signal intensity of thrombosed venous segments with susceptibility effect on GRE T2*- weighted sequences. Black, hypointense relative to gray matter; gray, isointense to gray matter; white, hyperintense to gray matter. GRE*, all segments exhibiting susceptibility effect were hypointense on GRE T2*- weighted sequences.

Fig 3.

A 22-year-old woman with a 6-day history of headache. Note the subtle abnormal signal intensity in the right transverse sinus on T2-weighting (A). The medial sinus is isointense (black arrow, A) and the lateral transverse sinus is hypointense (white arrow, A). The signal intensity on GRE sequences is very dark and enlarged compared with the size of the sinus on other sequences, consistent with susceptibility effect (arrows, B). On the postcontrast T1-weighted image, an isointense filling defect is noted consistent with thrombus (arrows, C). A, FSE T2-weighted image. B, GRE T2*-weighted image. C, T1WI after the administration of contrast.

Fig 4.

Clinical thrombus age and susceptibility effect. Gray, susceptibility effect present; white, susceptibility effect absent.

Fig 5.

A 20-year-old woman with 2-day history of severe headache. Thrombosis of the superior sagittal sinus and multiple cortical veins is present. Note the prominent hypointensity of the thrombosed superior sagittal sinus and cortical veins in B (arrows), much larger than the thrombosed venous structures on other sequences (A and C, arrows). Graded as 3+ susceptibility effect. Signal intensity of the thrombosed segments is hypointense on T2WI and isointense on T1WI. Note the normal parietal cortical vein on the left (arrowheads). A, FSE T2-weighted image. B, GRE T2*-weighted image. C, T1WI after the administration of contrast.