# Low-flow vascular malformations without arteriovenous shunting of the central nervous system: a pictorial review

## TL;DR

This paper reviews low-flow vascular malformations in the brain and spinal cord, focusing on how to diagnose them using imaging to avoid misdiagnosis.

## Contribution

The paper provides a detailed pictorial guide to distinguish low-flow vascular malformations from other brain lesions using MRI features.

## Key findings

- Developmental venous anomalies (DVAs) appear as a 'caput medusae' venous pattern on MRI.
- Cavernous malformations (CMs) show a mulberry-like core with a hemosiderin rim on SWI sequences.
- Capillary telangiectasias are often occult on routine MRI but may show subtle SWI hypointensity.

## Abstract

This review aims to provide a comprehensive pictorial review of low-flow vascular malformations (LFVMs) of the central nervous system (CNS) without arteriovenous shunting, focusing on their epidemiology, pathophysiology, imaging features, and associations with other vascular anomalies. LFVMs - developmental venous anomalies (DVAs), cavernous malformations (CMs), brain capillary telangiectasias (BCTs), and sinus pericranii (SP) - are typically benign and incidental but may cause symptoms or hemorrhage. Differentiating LFVMs from neoplastic, inflammatory, or high-flow vascular lesions is critical to avoid misdiagnosis and inappropriate treatment. MRI is the reference technique. DVAs show a “caput medusae” venous pattern; CMs have a mulberry-like core with a complete hemosiderin rim on T2*/SWI; BCTs are often occult on routine MRI but may display brush-like enhancement and subtle SWI hypointensity; SP consists of an extracranial venous mass communicating with a dural sinus through a transosseous vein. Familiarity with the imaging spectrum and typical associations of CNS LFVMs enables confident diagnosis and helps avoid unnecessary invasive procedures.

By illustrating key imaging features of low-flow CNS vascular malformations, this article critically addresses frequent diagnostic pitfalls. It advances radiological practice by guiding differentiation from neoplastic or high-flow lesions and improving multidisciplinary patient care.

LFVMs (DVAs, CMs, capillary telangiectasia, SP) are frequently incidental but may cause hemorrhage, seizures, or neurological deficits.DVAs are typically benign drainage variants; hemodynamic congestion on perfusion weighted imaging explains occasional symptoms and the frequent association with acquired CMs.CMS presents as “mulberry-shaped” lesions with a hemosiderin rim on SWI sequences, reflecting microhemorrhages and the absence of intervening brain parenchyma.Capillary telangiectasia most often occurs in the pons; recognition of the characteristic SWI hypointensity with faint enhancement prevents misdiagnosis as a neoplasm or ischemia.AP shows trans‑osseous venous channels connecting dural sinuses to epicranial varices; CT characterizes bony defects, and MRI depicts venous communication.

LFVMs (DVAs, CMs, capillary telangiectasia, SP) are frequently incidental but may cause hemorrhage, seizures, or neurological deficits.

DVAs are typically benign drainage variants; hemodynamic congestion on perfusion weighted imaging explains occasional symptoms and the frequent association with acquired CMs.

CMS presents as “mulberry-shaped” lesions with a hemosiderin rim on SWI sequences, reflecting microhemorrhages and the absence of intervening brain parenchyma.

Capillary telangiectasia most often occurs in the pons; recognition of the characteristic SWI hypointensity with faint enhancement prevents misdiagnosis as a neoplasm or ischemia.

AP shows trans‑osseous venous channels connecting dural sinuses to epicranial varices; CT characterizes bony defects, and MRI depicts venous communication.