Imaging description

Cavernous malformations (CMs) are angiographically cryptic vascular malformations of the brain and spinal cord that consist of discrete, honeycomb-like masses of endothelial-lined sinusoidal spaces. These are circumscribed lesions and consist of thrombosed blood. While the majority of these lesions are solitary, multiplicity may occur in nearly 20% of patients. Multiple lesions are more common in genetic/familial forms of CMs.

Cross-sectional studies identify and characterize the majority of these lesions, and these are nearly always occult on angiography [1]. CT demonstrates well-defined, focal hyperdense masses that may have internal, speckled calcifications. There is a lack of mass effect or edema, differentiating these from brain neoplasms. MRI is far more sensitive, as well as more specific, in the diagnosis of CMs. The MR appearances parallel the pathoanatomic changes on histologic exam. There is internal heterogeneity, and “popcorn”-type areas of high T1 signal from subacute blood products (methemoglobin) are often noted [1]. There is a peripheral rim of hemosiderin around the lesion, generally indicative of seepage of blood breakdown products in the periphery of the mass. This rim is best noted on T2-weighted sequences, although even more marked blooming is observed on gradient echo (GRE) and susceptibility-weighted imaging (SWI) sequences (Fig. 17.1). There is no edema and generally no adjacent arterial vessels. CMs have a known association with developmental venous anomalies.