Diffusion-Weighted MR in Cerebral Venous Thrombosis

Abstract

The diagnosis of cerebral venous thrombosis is often difficult both clinically and radiologically and until now there is no method available to predict if brain lesions, detected clinically and using conventional brain imaging methods, may lead to full recovery, as expected in vasogenic edema or ischemic infarcts and even a hematoma. New fast neuroimaging techniques such as diffusion-weighted imaging (DWI) are sensitive to different reasons of changes in local tissular water concentration thus giving further insight into the pathophysiological mechanism as well as prognosis of cerebral venous thrombosis. We report the cases of 18 consecutive patients with a diagnosis of cerebral venous thrombosis based on clinical and imaging criteria. All patients underwent magnetic resonance imaging (MRI) of the brain, which comprised isotropic diffusion-weighted MR. Diffusion-weighted MRI showed positive findings in 17/18 cases. In 7 cases the clot could be directly visualized as an area of hyperintensity in the affected vein on DWI. In 7 cases DWI showed areas of signal loss corresponding to hematomas. In 6 cases DWI showed changes in signal intensity that were more subtle. In 4 cases of superficial venous thrombosis, there were areas of decreased ADC values (0.65–0.79 × 10^–3 mm²/s) whereas in 2 cases of deep venous thrombosis, increased DWI intensities could be found that corresponded to both an increase and a decrease in ADC, corresponding to a coexistence of cytotoxic and vasogenic edemas. Diffusion-weighted MRI can demonstrate directly the presence of an intravenous clot in a select number of patients. It can also demonstrate early ischemic changes, and can differentiate conventional T2-weighted MR areas of cytotoxic from vasogenic edema.

Should Decompressive Surgery Be Performed in Malignant Cerebral Venous Thrombosis?

“…Second, because mass effect and elevated intracerebral pressure impair venous outflow and increase venous congestion, 9 decompressive surgery may improve cortical collateral vein drainage, thus preventing the extension of thrombosis and possibly favoring the diffusion of heparin. Finally, there is a ample evidence from MRI diffusion studies [15][16][17] that even large venous infarcts differ from arterial infarcts, with variable patterns of apparent diffusion coefficient maps explaining that venous infarcts in general have a far better potential for recovery than arterial infarcts. By saving lives, surgery allows the frequently favorable recovery observed in CVT.…”

Diagnosis and Management of Cerebral Venous Thrombosis

“…MRI signal can also predict radiographic outcome to some extent, because DWI abnormality within veins or sinus predicts poor recanalization. 71,105,110,[117][118][119][131][132][133]135,140,141 CT Venography CTV can provide a rapid and reliable modality for detecting CVT ( Figure 9). CTV is much more useful in subacute or chronic situations because of the varied density in thrombosed sinus ( Figure 10).…”

“…This finding accounts for the observed delayed cerebral perfusion seen with perfusionweighted MRI with prolonged transit time. 74,91,104,124,130,132,153 Direct Cerebral Venography Direct cerebral venography is performed by direct injection of contrast material into a dural sinus or cerebral vein from microcatheter insertion via the internal jugular vein. Direct cerebral venography is usually performed during endovascular therapeutic procedures.…”

Neuroimaging of Cerebral Ischemia and Infarction

“…FLAIR images are also highly sensitive in detecting other lesions, including subarachnoid hemorrhage and acute cerebral venous sinus thrombosis [25][26][27].…”