What are the radiological findings in cavernoma?

Radiological Findings in Cavernoma

MRI is the imaging study of choice for cavernoma, demonstrating the characteristic "bull's-eye" or "popcorn" appearance with a reticulated core of mixed signal intensity surrounded by a hypointense hemosiderin rim on T2-weighted sequences. 1

MRI Characteristics

Classic Appearance on Standard Sequences

• The pathognomonic finding is a reticulated core of mixed signal intensity with a surrounding rim of decreased signal intensity on T2-weighted imaging, representing hemosiderin deposition from repeated hemorrhages 2
• The "popcorn" morphology reflects various stages of hemorrhage with blood products of different ages, though this classic appearance is only visible in 15-22% of cases 3
• T1-weighted imaging shows variable signal intensity depending on the age of blood products, with hyperintense signals indicating subacute hemorrhage (methemoglobin) 1, 4
• The hemosiderin rim appears as a complete or near-complete hypointense border on T2-weighted sequences in only 37% of cases 3

Advanced MRI Sequences

• T2-weighted gradient-echo imaging or susceptibility-weighted imaging (SWI) is superior to standard spin-echo sequences for detecting cavernomas, particularly smaller lesions and multiple cavernomas not visible on conventional imaging 1, 5
• Smaller cavernomas appear as "black dots" on gradient-echo sequences due to magnetic susceptibility effects from hemosiderin 2
• These advanced sequences can reveal additional lesions in patients with multiple cavernomas (15% of cases) or familial forms (50% of familial cases) 1

Hemorrhagic Features

• Adjacent intramedullary hemorrhage extending away from the lesion is present in 58% of spinal cord cavernomas, appearing as linear or flame-shaped non-edematous signal abnormality 3
• Acute hemorrhage appears isointense on T1-weighted and hypointense on T2-weighted sequences 4
• Subacute hemorrhage demonstrates hyperintense signal on both T1- and T2-weighted sequences 4
• Internal blood-fluid levels are uncommon, seen in only 4% of cases 3

Contrast Enhancement

• Cavernomas typically show slight heterogeneous enhancement or no enhancement after gadolinium administration 4
• Contrast may increase conspicuity of associated developmental venous anomalies (DVAs), which occur in 20% of cases 1, 5

CT Findings

Non-Contrast CT

• Non-contrast CT can demonstrate acute hemorrhage but is less sensitive than MRI for detecting non-hemorrhagic cavernomas 1
• Cavernomas may appear as faintly hyperdense lesions on non-contrast imaging, often with a suprasellar mass that is spontaneously denser than adjacent brain parenchyma 1, 4
• Microcalcifications are present in some cases, representing chronic hemorrhage with tissue fibrosis and calcification 1, 4

Contrast-Enhanced CT

• IV contrast increases conspicuity of associated DVAs but adds limited value for cavernoma detection itself 1

Angiographic Findings

Catheter Angiography

• Cavernomas are typically angiographically occult due to sluggish blood flow through thin-walled sinusoidal spaces without arteriovenous shunting 1
• Feeding arteries and draining veins are of normal caliber, distinguishing cavernomas from high-flow vascular malformations 1
• Only 30% of cavernomas show any abnormal vasculature, typically limited to venous pooling or minimal capillary blush 2
• Catheter angiography may be used to exclude associated high-flow malformations or to demonstrate associated DVAs, which appear as abnormal venous clusters draining into a single collector on the venous phase 1

CTA and MRA

• CTA and MRA play limited roles in cavernoma assessment, as these modalities are optimized for high-flow lesions 1
• MRA is not usually helpful for evaluating cavernomas but may demonstrate associated DVAs 1

Location-Specific Features

Supratentorial Lesions

• 86% of cavernomas are supratentorial, with 63% measuring less than 1 cm in length 1, 3
• 78% extend to the cord surface, and 65% cause cord expansion 3
• 32% have an exophytic component extending beyond the brain parenchyma 3

Deep and Eloquent Locations

• Deeply situated cavernomas (basal ganglia, thalamus, brainstem) are more likely to bleed than superficial lesions 1
• Chiasmatic cavernomas present with regular enlargement of the optic chiasm (2.5-3 cm), often with acute or subacute hemorrhage 4

Common Pitfalls and Caveats

• Do not rely solely on standard MRI sequences—gradient-echo or SWI sequences are essential for detecting multiple lesions and smaller cavernomas that may be missed on spin-echo imaging 1, 2
• Avoid including the hemosiderin rim in treatment planning for radiosurgery, as it may potentiate radiation effects and increase risk of adverse events 1
• Be aware that classic imaging features (popcorn morphology, complete hemosiderin rim, blood-fluid levels) are often absent, particularly in smaller lesions or those without recent hemorrhage 3
• Consider associated DVAs in 20% of cases, as most hemorrhage in DVA patients is attributed to associated cavernomas rather than the DVA itself 1, 5
• Recognize that cavernomas can develop de novo from microhemorrhages, particularly in familial cases or after cranial irradiation, requiring long-term follow-up imaging 6