Objective: Preoperative differentiation between primary central nervous system lymphoma (PCNSL) and high grade astrocytoma (HGA) on conventional magnetic resonance imaging (MRI) can be difficult and even impossible. However, differentiation is important to guide therapeutic strategy. Several authors have reported the leakage pattern in dynamic susceptibility-contrast (DSC)-MRI in PCNSL. It describes the shape of the signal intensity curve which does not return to the baseline after the first pass of the bolus of contrast agent but crosses above it and sometimes even slopes up. In this retrospective study, our goal was to define the sensitivity and specificity of this sign.
Material and methods: Patients with first ever diagnosed PCNSL and HGA who were treatment naive and received DSC-MRI were included. In all patients, a histological specimen was available. Patients did not receive corticosteroids prior to imaging and were HIV negative. The presence of a leakage pattern was assessed by two neuroradiologists working in consensus and correlated with the histological diagnosis.
Results: Nine patients with PCNSL (2 women, 7 men, age 59 ± 10 years) and 14 patients with HGA (3 women, 11 men, age 58 ± 17 years) were included. Six of the patients with PCNSL exhibited a leakage pattern, while only two patients with HGA did (P = 0.0227, Fischer's exact test). Sensitivity was 0.67, and specificity was 0.86.
Discussion: Although the leakage pattern does not prove PCNSL, it is an important diagnostic clue and can be easily assessed.