Differential diagnosis of infarct-like intracranial ectopic germinomas and subacute lacunar infarct on susceptibility-weighted imaging.

PURPOSE: To determine the efficacy of susceptibility-weighted imaging (SWI) in the differential diagnosis between basal ganglia (BG) infarct-like early stage intracranial ectopic germinomas (IEGs) and subacute lacunar infarct (SLI).

MATERIALS AND METHODS: Six children with early stage BG IEGs displaying an infarct-like episode proven by pathology and eight children with BG SLI proven by clinic and vascular imaging were investigated retrospectively. On SWI, the contrast-to-noise ratio (CNR) in abnormal signal intensity regions was calculated and compared between the two groups.

RESULTS: For both IEGs and SLI the BG lesions were invisible or showed slight hyperintensity/hypointensity on T1-weighted images and diffusion-weighted images, patchy slight hyperintensity on T2-weighted images without mass effect, and variable enhancement on postcontrast magnetic resonance imaging (MRI). On SWI, obvious hypointensity in BG lesions and pineal gland (PG) was found in IEG patients but unremarkable in SLI patients. The CNRs of BG lesions and PG were significantly higher in IEG patients compared with those in SLI patients (P < 0.01).

CONCLUSION: SWI is useful in differentiating IEGs from SLI when clinical symptoms and conventional MRI manifestations overlap in these two conditions. PG may be involved with tumor, although it is normal on conventional MRI in patients with IEGs.