MR Perfusion - Brain Tumour

MR perfusion adds haemodynamic information to conventional brain MRI by quantifying tumour microvascularity. Dynamic susceptibility contrast produces relative cerebral blood volume maps that correlate with glioma grade and angiogenesis, and it is central to distinguishing recurrent tumour from treatment-related change where conventional enhancement is ambiguous.

Indications

Grading of gliomas and estimation of tumour angiogenesis
Differentiating recurrent/progressive tumour from treatment-related change (pseudoprogression, radiation necrosis)
Distinguishing neoplastic from non-neoplastic enhancing lesions (e.g. tumefactive demyelination, abscess)
Guiding stereotactic biopsy to the most malignant (highest rCBV) region
Assessing response to anti-angiogenic and chemoradiation therapy
Characterising suspected lymphoma versus high-grade glioma

Contraindications & Cautions

Non-conditional pacemakers, ICDs, neurostimulators and ferromagnetic aneurysm clips
Cochlear implants and unstable metallic intra-ocular foreign bodies
Gadolinium caution with eGFR <30 mL/min/1.73 m2 (NSF risk); ASL is a contrast-free alternative
Severe claustrophobia without sedation
Pregnancy: avoid gadolinium; consider arterial spin labelling if perfusion is essential

Patient Preparation

MRI safety screening and removal of ferromagnetic objects
Large-bore intravenous access and a power injector for a tight contrast bolus
For DSC, consider a gadolinium preload dose to reduce contrast-leakage (T1) error in enhancing tumours
Explain the need for stillness during the dynamic acquisition
Review prior imaging and treatment history to frame recurrence-versus-necrosis questions

Technique & Parameters

Dynamic susceptibility contrast (DSC): rapid T2*-weighted gradient-echo EPI acquired continuously through a power-injected gadolinium bolus
Preload/leakage correction to mitigate signal error from blood-brain barrier breakdown
Generation of relative cerebral blood volume (rCBV) and relative cerebral blood flow maps, normalised to contralateral normal white matter
Dynamic contrast-enhanced (DCE) T1 perfusion for permeability metrics (Ktrans) where available
Arterial spin labelling (ASL) for a contrast-free cerebral blood flow map
Co-registration with conventional pre- and post-contrast T1, T2/FLAIR and DWI for anatomical correlation

Systematic Review

Confirm technical adequacy: bolus timing, susceptibility artefact and adequate normalisation region
Place regions of interest in the solid enhancing tumour, avoiding vessels, haemorrhage and calcification
Measure maximum rCBV and normalise to contralateral normal white matter
Correlate high-rCBV foci with enhancing and non-enhancing (FLAIR) components
Assess the DSC signal-intensity-time curve for return to baseline (leakage) versus overshoot
Integrate with DWI, spectroscopy and conventional sequences before concluding

Key Findings & Significance

High-grade glioma: markedly elevated maximum rCBV in the enhancing tumour reflecting neovascularity
Low-grade glioma: relatively low rCBV (with caution for oligodendroglial tumours which can have elevated rCBV)
Tumour recurrence/progression: elevated rCBV in the enhancing region
Radiation necrosis/treatment change: low rCBV with a low signal-recovery (leakage) curve
Tumefactive demyelination: relatively low rCBV despite avid enhancement, aiding differentiation from tumour
Cerebral abscess: low rCBV rim with central restricted diffusion, unlike a necrotic high-rCBV tumour

Differential Considerations

Enhancing lesion with high rCBV: high-grade glioma, metastasis, recurrent tumour
Enhancing lesion with low rCBV: radiation necrosis, tumefactive demyelination, abscess, subacute infarct
Lymphoma: variable, often modest rCBV with a characteristic DSC leakage overshoot pattern
Peritumoural high FLAIR signal: infiltrative tumour (raised rCBV) versus vasogenic oedema (low rCBV) around a metastasis
Post-treatment enhancement: pseudoprogression versus true progression

Pearls & Pitfalls

rCBV must be normalised to contralateral normal-appearing white matter for meaningful comparison
Leakage correction or a preload dose is essential in enhancing tumours to avoid underestimating rCBV
Elevated peritumoural rCBV favours infiltrative glioma over a well-circumscribed metastasis
Perfusion is an adjunct: always integrate rCBV with conventional MRI, diffusion and spectroscopy
Sample the highest-rCBV region to guide biopsy and avoid undersampling the most aggressive tumour component

Structured Report

State field strength, perfusion technique (DSC/DCE/ASL) and whether preload/leakage correction was applied
Report normalised maximum rCBV and its relation to enhancing and non-enhancing tumour
Give an interpretation regarding grade or recurrence-versus-treatment change
Correlate with conventional sequences, diffusion and spectroscopy
Provide an impression with recommendation for biopsy target, follow-up or multidisciplinary discussion

References

Boxerman JL, et al. Consensus recommendations for a dynamic susceptibility contrast MRI protocol for use in high-grade gliomas. Neuro-Oncology 2020
Essig M, et al. Perfusion MRI: the five most frequently asked technical questions. AJR
Radiographics: MR perfusion imaging of brain tumours (DSC, DCE, ASL)
ASFNR recommendations for clinical performance of MR perfusion in neuro-oncology

Educational clinical decision support only. Protocols vary by institution and equipment; always confirm with a qualified radiologist and local guidelines before clinical use.

MR Perfusion - Brain Tumour

📋 Indications

⛔ Contraindications & Cautions

🧑‍⚕️ Patient Preparation

⚙️ Technique & Parameters

🔎 Systematic Review

🩻 Key Findings & Significance

🧠 Differential Considerations

💡 Pearls & Pitfalls

📝 Structured Report

📚 References