Extreme Anemia Causing Unusual "Black-out" of the Cerebral Vessels on Noncontrast Brain CT.

Laboratory tests revealed an extreme anemia with a collapsed hemoglobin concentration at 34 g/L and a hematocrit value of only 10 %. During the delay in obtaining compatible blood for transfusion, noncontrast brain CT was performed to explore the diplopia (Figs. 1 and 2). The attention of the radiologists was retained by the very unusual and generalized hypodensity of blood in all cerebral vessels comprising carotids, jugular veins, vertebral arteries, carotid siphons, and cavernous sinuses and also within the lateral and longitudinal venous sinuses and torcular herophili. The mean density of blood in these structures was only about 26 Hounsfield units (HU). Gastroscopy was normal. Rectosigmoidoscopy demonstrated fresh rectal blood with clots but no tumoral lesion within the last 50 cm of the colon. Diverticulosis was present. It was concluded that rectal bleeding was related to colonic diverticular bleeding. Contrast-enhanced abdominal CT was performed a few hours later to exclude other potential causes of rectal bleeding. At this time, the patient had already been transfused, but both the hemoglobin level and the hematocrit value remained deeply lowered at 50 g/L and 16 %, respectively. On preliminary noncontrast series, the spontaneous density of blood still remained very low, with a mean density of 20 HU, allowing spontaneous visualization of the cardiac septum and aortic wall (Fig. 2e and f).