Authors - Jacob Young M.D 1, Madhurima Datta PhD 2, Yosef Chodakiewitz M.D2, Alex Exuzides PhD2
1. UCSF, 2. Prenuvo Inc. USA
Introduction
Data on incidental brain findings remain limited despite the increase in MRI frequency. We analyzed brain findings in 78,000 individuals undergoing preventive screening whole-body MRI to determine the incidence, types, and demographic distribution of intracranial abnormalities.
Methods
We reviewed screening whole-body MRIs performed between January 2024 and June 2025 across 21 Prenuvo clinics. All scans were non-contrast, multiparametric studies on 1.5T MRI systems. The brain protocol included T1 MPRAGE, FLAIR, TOF MRA, and whole-body sequences (STIR, DWI). Radiologists used a standardized synoptic template and a 5-point Clinically Significant Diagnosis (CSD) scale. Brain findings with CSD 3 (low concern), 4 (moderate, timely follow-up), and 5 (major, expedited follow-up) were included.
Results
Of 78,800 individuals, 5,637 (7.1%) had at least one brain finding with CSD ≥3 (mean age 50.6± 12.7 years; 44% male). The most common were intracranial aneurysm (IA, 2.2%, n=1,759), small vessel ischemia (0.95%, n=753), brain infarct (0.65%, n=529), indeterminate brain lesion (IBL, 0.7%, n=555), narrowed intracranial arteries (0.38%, n=310), meningioma (0.22%, n=181), and pituitary mass (0.19%, n=152). Rare findings included AVM (0.04%), glioma (0.02%), and metastases (0.01%).
Among IAs, 67% were female, 87% in anterior circulation, and 2.6% >7 mm in size; 17.3% CSD 4, 0.3% CSD 5. IBLs (55.6% female; 51.6% aged 35–54) measured 0.3–5.8 cm, with 34.5% intra-axial, 21.2% extra-axial, 7.2% CSD 4, and 0.7% CSD 5. Meningiomas (0.3-5.0 cm; 76% female; 55% aged 45–64) were CSD 4 in 5.5% and CSD 5 in 1.1%. Among individuals with indeterminate brain lesions (IBL), 55.6% were female, and 51.6% were aged 35–54
years. IBL ranged from 0.3-5.8 cm in size, with 34.5% intra-axial, 21.2% extra-axial, and the remainder unspecified. Among IBL, 40 (7.2%) were CSD 4 and 4 (0.7%) were CSD 5.
Conclusion
In a large general population, CSD ≥3 brain findings occurred in 7% of individuals. These findings align with population MRI studies (e.g., Rotterdam) and highlight the importance of silent but actionable brain pathology detected on screening MRI.
