MRI and F¹⁸-FDG PET-CT features of intracranial primary lymphoma

Objective: To analyze the MRI and F¹⁸-FDG PET-CT appearances of intracranial primary lymphoma. Methods: The MRI and F¹⁸-FDG PET-CT of 21 patients (14 men, 7 women, age range: 28 to 84 years, mean: 53 years) with histologically confirmed IPL were analyzed retrospectively. The tumor location, size, shape, signal intensities on T₁-, T₂- and FLAIR-weighted MR images, contrast enhancement characteristics, peritumoral edema and necrosis were assessed. Results: Of 15 patients over the age of 50 years, 6 patients (28.6%) had solitary lesions and 15 patients (71.4%) had multifocal disease yielding a total of 70 lesions, 90% of the lesions were located in the corpus callosum, basal ganglia, thalamus and periventricular regions. 62.9 of lesions were irregular. The tumor spread along V-R spaces (36.4%), white matter (52.3%), gray matter and meninges. Most lesions were slightly hypointense or isointense on T₁WI (88.5%), and slightly hyperintense or isointense on T₂WI (97.1%) relative to gray matter, and showed obvious enhancement (75.7%). The tumor was hyper-metabolic in 8/9 (88.9%) of patients on F¹⁸-FDG PET-CT. Conclusion: Intracranial primary lymphoma has characteristic features on MRI and ¹⁸FDG PET-CT, which are helpful for preoperative diagnosis. (authors)