What MRI changes are characteristic of lymphoma in the brain?

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Last updated: January 23, 2026 • View editorial policy

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MRI Characteristics of Brain Lymphoma

Brain lymphoma demonstrates characteristic MRI features including hypointense lesions on T1-weighted imaging, isointense to hypointense appearance on T2-weighted imaging, restricted diffusion with reduced apparent diffusion coefficient (ADC), variable surrounding edema, and homogeneous strong enhancement with gadolinium contrast. 1, 2

Key MRI Features to Identify

Signal Characteristics

  • T1-weighted sequences: Lesions appear hypointense (darker than normal brain tissue) 1
  • T2-weighted sequences: Lesions are isointense to hypointense (similar to or darker than normal brain tissue) 1
  • Diffusion-weighted imaging (DWI): Shows restricted diffusion with reduced ADC values, reflecting high cellularity 1, 2
  • Contrast enhancement: Strong, homogeneous enhancement is characteristic after gadolinium administration 1, 2

Anatomical Distribution Patterns

The most common locations to examine include 1:

  • Frontal lobe and cerebral hemispheres (38% of cases)
  • Thalamus or basal ganglia (16%)
  • Corpus callosum (14%)
  • Periventricular regions (12%)
  • Cerebellum (9%)
  • Meninges (16%)
  • Spinal cord (1%)

Multifocality

  • 40-50% of patients present with multifocal disease on standard MRI, which is an important distinguishing feature 1
  • Multiple lesions should raise suspicion for lymphoma over other diagnoses

Recommended MRI Protocol

Contrast-enhanced cranial MRI is the mandatory imaging modality for suspected CNS lymphoma. 1, 2 The International PCNSL Collaborative Group (IPCG) protocol should be followed, utilizing either 3T or 1.5T MRI with 1:

  • Diffusion-weighted sequences
  • Perfusion-weighted scans
  • Volumetric protocols
  • Gadolinium contrast administration

Critical Diagnostic Considerations

Corticosteroid Effect

  • Avoid corticosteroids before imaging and biopsy whenever clinically possible, as they cause rapid tumor regression and can make lesions disappear on MRI, leading to false-negative results 1
  • If corticosteroids have been administered, repeat MRI after stopping them may be necessary before biopsy 1

Differential Diagnosis Challenges

The combined use of MRI and biomarkers helps distinguish lymphoma from 1:

  • Toxoplasmosis (especially in HIV-positive patients) 1
  • Brain metastases
  • Non-necrotic brain tumors
  • Abscesses
  • Tumefactive demyelination
  • Neuroinflammatory diseases

HIV-Associated Lymphoma Considerations

  • In HIV-positive patients, contrast enhancement remains highly sensitive (96.1%) at diagnosis 3
  • FDG-PET/CT can help differentiate cerebral infections like toxoplasmosis from CNS lymphoma, though biopsy remains the gold standard 1
  • MRI is the optimal method for staging CNS lymphomas in HIV patients, but may give false-positive results due to opportunistic infections 1

Limitations and Pitfalls

  • Imaging alone cannot definitively diagnose CNS lymphoma—histopathological confirmation via stereotactic biopsy remains essential 1
  • Contrast-enhanced CT can be used only in patients with MRI contraindications, but is inferior to MRI 1
  • Variable surrounding edema may be present, which is not specific to lymphoma 1

References

1
Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

2
Guideline

Diagnosis and Management of Central Nervous System Lymphoma

Praxis Medical Insights: Practical Summaries of Clinical Guidelines, 2026

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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