Brainstem lesion diagnostic Dilemma: The role of multiparametric magnetic resonance imaging

• Multiparametric MRI enhances differentiation of brainstem lesions. • 58% of indeterminate cases benefited from advanced imaging insights. • Multiparametric MRI accurately differentiates inflammatory and neoplastic lesions. • Non-invasive methods reduced the need for high-risk biopsies. • Combined techniques improved diagnostic accuracy for treatment guidance. Brainstem lesions pose a significant diagnostic challenge. The critical nature of the brainstem renders invasive biopsy difficult, often yielding inconclusive results. Multiparametric magnetic resonance imaging (MRI) is a useful addition to standard MRI sequences and can aid in the differentiation between neoplastic and non-neoplastic lesions. Although few studies have examined its utility for this purpose. Here we present our experience in characterising brainstem lesions using multiparametric MRI at a tertiary neurosciences centre. We retrospectively reviewed multiparametric MRI studies performed at our institution between 2015–2020. Brainstem lesion characterists on standard contrast-enhanced T1- and T2-weighted sequences, Dynamic Susceptibility Contrast (DSC) MRI, Diffusion Weighted Imaging (DWI), including Apparent Diffusion Co-efficient (ADC) maps, and MR spectroscopy were examined. Multiparametric MRI was performed on 560 patients, 31 (5.5%) of whom were assessed for indeterminate brainstem lesions. Of these, 18 (58%) provided useful additional diagnostic information to correctly differentiate neoplastic and inflammatory lesions. Cases of note include a low-grade glioma, non-enhancing high-grade glioma (transforming glioma), enhancing high-grade glioma, Bickerstaff encephalitis and neurosarcoidosis. Standard MRI sequences in combination with multiparametric data can provide an accurate and non-invasive means of differentiating between inflammatory and neoplastic brainstem lesions, potentially avoiding biopsy in some cases.