Association between possible osteopenia and the growth of small unruptured intracranial aneurysms.

Both bone and intracranial arterial walls are composed of type 1 collagen, and bone mineral density (BMD) may be associated with the presence, size, and multiplicity of intracranial aneurysms. This longitudinal study aimed to investigate whether BMD was associated with aneurysm growth in patients with UIAs < 7 mm. This prospective cohort study consecutively enrolled 425 patients with UIAs < 7 mm between 2016 and 2023. Hounsfield unit (HU) values of the frontal skull on brain computed tomography (CT) were measured as a convenient surrogate for assessing skeletal status. According to the mean HU cutoff value of 719.9, patients were categorized into hypothetical normal group (> 719.9) and possible osteopenia (PO) group (≤ 719.9). The PO was defined as a CT-based surrogate, not dual-energy X-ray absorptiometry-defined osteopenia. The primary outcome was aneurysm growth. After a follow-up time of 647.0 patient-years (median duration, 15.7 months; interquartile range, 8.1-26.0 months), 46 (10.8%) aneurysms grew. The incidence rate of aneurysm growth was 7.11 per 100 person-years. Cox analysis revealed that larger initial aneurysm size, aneurysm location (anterior communicating artery, posterior communicating artery, and middle cerebral artery), uncontrolled hypertension, and PO (hazard ratio, 2.98 [95% CI, 1.55-5.71]; P = 0.001) were associated with a high risk of aneurysm growth, whereas aspirin use was associated with a decreased risk of aneurysm growth. PO was associated with an elevated risk of UIA growth. Our findings may be useful for predicting growth in UIA patients using a convenient method of measuring skull HU values on brain CT.Clinical trial registration: Not applicable.