An absence of signal on magnetic resonance (MR) images caused by blood or cerebral spinal fluid flow is known as a flow void, and may be related to intracranial tumors such as intracranial solitary fibrous tumor (SFT) or meningioma. However, the differential diagnosis of these neoplasms based on flow void configuration is controversial. This study investigated common intratumoral flow void patterns for differentiating intracranial SFT from meningioma.

From May 2008 to May 2015, 14 patients (10 men, 4 women; 14–63y) received a pathologic diagnosis of primary intracranial SFT, and in 85 patients (23 men, 62 women; 20–76y) a pathologic diagnosis of meningioma was made. Intratumoral flow void signs were retrospectively observed on MR images of all these patients and classified by radiologists blinded to the pathology findings. Statistical significance was established by chi-squared tests.

In intracranial SFT patients, the sunburst flow void was detected in 1 case (7.1%) and the serpentine in 13 cases (92.9%). In meningioma patients, the sunburst flow void was detected in 82 cases (96.5%) and the serpentine in 3 cases (3.5%). The differences in the prevalence of the flow void types between the 2 groups were significant (χ²=64.348; P<0.01).

Intracranial SFTs on MR images were more likely to show a serpentine than a sunburst flow void, while the sunburst pattern was far more typical of meningioma. Thus, the pattern of the intratumoral flow void sign may be a useful tool to assist in differentiating these tumors.