Acute cerebral vein thrombosis is usually seen as increased attenuation in brain non-contrast computed tomography. It is so helpful to define measurable parameters for subjective evaluation of sinus thrombosis in non-enhanced brain computed tomography, especially where advanced neuroimaging techniques are not available. the purpose of this study is to evaluate the diagnostic value of venobasilar attenuation ratio and venobasilar attenuation difference in the evaluation of acute cerebral venous sinuous thrombosis in non-enhanced brain CT scan. Fifty confirmed cases of acute cerebral vein thrombosis were sex-and age-matched with 73 subjects who did not have the condition. Average venous sinus attenuation, Hounsfield to hematocrit ratio, basilar artery density, venobasilar attenuation ratio and venobasilar attenuation difference were measured. Mean attenuation was 65.8 in thrombosed and 44.9 in non-thrombosed sinuses (P < 0.0001). A cutoff absolute sinus attentuaion of 61 HU led to a sensitivity of 82%, specificity of 100% and accuracy of 92%. A cutoff ratio of 1.4 for venobasilar ratio led to a sensitivity of 100%, specificity of 78% and accuracy of 87%. A cutoff value of 24 for venobasilar difference resulted in the sensitivity of 80%, specificity of 100% and accuracy of 92%. The additional measurement of venous sinus and basilar artery attenuations and calculation of venobasilar ratio and difference can increase the sensitivity and specificity of NCCT in the diagnosis of acute cVSt. Cerebral venous sinus thrombosis (CVST) is responsible for about 0.5-1% of all strokes and occurs in about 2-5 patients per million every year 1,2. Patients exhibit a wide range of non-specific signs and symptoms, including-but not limited to-headache (the most common symptom), focal neurologic deficits, seizure and impaired level of consciousness. So, the diagnosis is usually not suspected at the initial presentation 3,4. NCCT may be the only modality available in low resource settings 5. The elevated density of the venous sinuses (dense sinus sign or cord sign) is the only direct sign of acute CVT in brain NCCT 6. It has been shown in several studies that blood density within dural veins correlates with hematocrit level 7-10 , and polycythemia is considered as a mimicker of CVST 11,12. It seems rational to define quantitative criteria for more accurate diagnosis and reduce the false positive results. The aim of this study is to evaluate NCCT in patients with and without acute CVST and determine the diagnostic value of venous sinus density, Hounsfield-hematocrit (H:H) ratio, veno-basilar (VB) ratio and VB difference in the evaluation of acute CVST. Materials and Methods patient selection. The ethics committee of Mashhad university of medical sciences approved the study (approval ID: IR.MUMS.MEDICAL.REC.1398.233) and waived the need for informed consent. In this retrospective observational study, we sought the archive of our academic hospital which is a first-level and referral neurology center, to compile the database of patients wit...