P15.02 The accuracy of MRI for diagnosing intracranial lymphoma

Abstract

Abstract Introduction: Intracranial lymphoma is a rare but serious condition. Diagnostic workup includes at least a physical exam, cerebral spinal fluid examination and MRI, though the gold standard is stereotactic biopsy. Stereotactic biopsy is a procedure with possible complications, which include infection, bleeding and diagnostic delay. This inspired our ­multidisciplinary team to study the necessity of biopsy when a lesion is radiologically (very) suspicious for lymphoma. MRI features of lymphoma have been well-described. We investigated the accuracy of MRI for diagnosing intracranial lymphoma. Additionally, we aimed to explore diagnostic delay caused by the biopsy. Materials and methods: We conducted a retrospective single center database study, obtaining MRI reports and biopsy results of patients with brain lesions visiting our outpatient clinic in the past 5 years. We selected all patients with an MRI-report where lymphoma was mentioned as the only possible diagnosis or where lymphoma was mentioned in the differential diagnosis. Primary outcomes were sensitivity and positive predictive value (PPV) of MRI. Secondary outcomes were differences in sensitivity and PPV between subgroups and time between MRI, biopsy and treatment. Results: Positive MRIs had a sensitivity of 87.5%, 95% CI [64.0, 96.5] and PPV of 48.3%, 95% CI [31.4, 65.6]. All MRIs where lymphoma was the only possible diagnosis, had a biopsy proven lymphoma. Mean time in days between MRI and biopsy was 13.60 days, SD10.1, and between MRI and treatment 26.41 days, SD12.7. DISCUSSION: In this study, all MRIs that have lymphoma as their only possible diagnosis, had biopsy proven lymphoma. This suggests that these patients might not need a stereotactic biopsy to prove diagnosis. Further research is necessary to determine whether the same results come up in larger sample sizes and other study designs. In the meantime, our multidisciplinary team designed a diagnostic fast track for these patients, shortening the diagnostic delay caused by the need to biopsy.