Aneurysmal subarachnoid haemorrhage: Volumetric quantification of the blood distribution pattern to accurately predict the ruptured aneurysm location

Background In spontaneous subarachnoid haemorrhage (SAH) accurate determination of the bleeding source is paramount to guide treatment. Traditionally, the bleeding pattern has been used to predict the aneurysm location. Here, we have tested a software-based tool, which quantifies the volume of intracranial blood and stratifies it according to the regional distribution, to predict the location of the ruptured aneurysm. Methods A consecutive series of SAH patients admitted to a single tertiary centre between 2012–2018, within 72 h of onset, harbouring a single intracranial aneurysm. A semi-automatized method of blood quantification, based on the relative density increase, was applied to initial non-contrast CTs. Five regions were used to define the bleeding patterns and to correlate them with aneurysm location: perimesencephalic, interhemispheric, right/left hemisphere and intraventricular. Results 68 patients were included for analysis. There was a strong association between the distribution of blood and the aneurysm location (p < 0.001). In particular: ACom and interhemispheric fissure (p < 0.001), MCA and ipsilateral hemisphere (p < 0.001), ICA and ipsilateral hemisphere and perimesencephalic cisterns (p < 0.001), PCom and hemispheric, perimesencephalic and intraventricular (p = 0.019), and PICA and perimesencephalic and intraventricular (p < 0.001). The internal diagnostic value was high (AUROC ≥ 0.900) for these locations. Conclusion Regional automatised volumetry seems a reliable and objective tool to quantify and describe the distribution of blood within the subarachnoid spaces. This tool accurately predicts the location of the ruptured aneurysm; its use may be prospectively considered in the emergency setting when speed and simplicity are attained.