Purpose: A better understanding of the significance of diffuse hyperdensity affecting the circle of Willis and the dural sinuses on unenhanced CT.
Materials and methods: We performed a retrospective study of 19 patients with a neurological manifestation and a CT scan without contrast injection. Among these 19 patients, six had been included because of primary or secondary polycythemia. The analysis of cerebral CT scans was made qualitatively by visual inspection and quantitatively.
Results: In patients with a hematocrit percentage exceeding 60%, both circle of Willis and dural sinuses were dense on unenhanced CT scans. A linear relation between the hemoglobin level and the contrast of the dural sinuses compared with the grey matter was observed with an excellent correlation (r = 0.934; n < 0.0001; p = 19).
Conclusion: Increased density of cerebral vessels on unenhanced CT is a sign of a high hemoglobin level.