What imaging study and MRI protocol should be used to evaluate an adult patient with a suspected brain tumor?

MRI Imaging of Brain Tumors

For adult patients with suspected brain tumors, MRI brain without and with IV contrast using a standardized Brain Tumor Imaging Protocol (BTIP) is the gold standard imaging study. 1

Essential MRI Protocol Components

The American College of Radiology recommends a standardized BTIP that includes the following sequences 1:

• High-resolution 3D T1-weighted imaging pre- and post-contrast - This is the single most critical component for tumor visualization, delineation of tumor extent, and surgical planning 1
• Axial 2D T2 FLAIR - Essential for evaluating vasogenic edema, assessing tumor-associated changes, and identifying leptomeningeal involvement 1
• Axial diffusion-weighted imaging (DWI) with ADC maps - Provides information about tumor cellularity and helps differentiate tumor from other pathologies like abscess 1
• Axial susceptibility-weighted imaging (SWI) - Critical for detecting intratumoral calcifications, hemorrhage, and vascular structures 1
• Axial T2-weighted sequences - Provides complementary anatomic detail 1

Why Contrast Administration is Mandatory

MRI without contrast alone is insufficient for clinical decision-making about brain tumors. 1, 2 The American College of Radiology explicitly states that non-contrast MRI cannot:

• Accurately determine tumor extent and tissue involvement 1, 2
• Differentiate tumor from other pathologies 2
• Assess for leptomeningeal or dural involvement 2
• Distinguish recurrent tumor from post-treatment changes 2
• Guide treatment decisions effectively 2

Contrast enhancement indicates blood-brain barrier breakdown and provides critical information about enhancement patterns that help with preoperative differential diagnosis and stratification into high- versus low-grade tumors 1

Advanced Imaging Sequences as Adjuncts

Perfusion MRI (DSC or ASL)

Perfusion imaging should be strongly considered as an adjunct to the standard protocol, particularly for:

• Differentiating high-grade from low-grade gliomas (sensitivity of 100% in pediatric studies) 1
• Distinguishing primary CNS lymphoma from glioblastoma and metastases 1
• Survival prediction and optimization of biopsy targeting 1
• Identifying metabolic hotspots for tissue sampling 1

DSC-MRI-derived relative cerebral blood volume (rCBV) has been shown to predict improved overall survival in glioblastoma patients 1

MR Spectroscopy (MRS)

MRS can be added to increase diagnostic certainty by identifying characteristic metabolite patterns, particularly useful in combination with perfusion imaging for predicting molecular markers like IDH mutation and 1p/19q deletion status 1

Functional MRI (fMRI) and DTI

These sequences are helpful for surgical planning when tumors involve eloquent brain regions, allowing preservation of critical neurological function 1

Specific Considerations by Tumor Location

For Intraaxial (Parenchymal) Tumors

The standardized BTIP protocol is mandatory 1. Postcontrast 3D T2 FLAIR imaging should be added to evaluate for leptomeningeal metastases, which has implications for management and overall survival 1

For Extraaxial (Dural-Based) Tumors

The same MRI protocol without and with contrast applies 1. For skull base meningiomas specifically:

• SWI is particularly important as calcifications occur in up to 50% of cases 3
• Consider adding MR perfusion (DSC) when grading is important, as meningiomas are highly vascular 1, 3
• SSTR PET (DOTATATE) may be valuable when morphologic tumor borders are difficult to assess by MRI alone at the skull base 3

Critical Imaging Standardization

MRI images should be converted to digital format (e.g., CD) for possible subsequent dosimetric studies and treatment planning. 1 Standardization of MRI acquisition protocols is critical, especially for enrollment in multicenter clinical trials 1

Common Pitfalls to Avoid

• Never rely on CT alone - CT has significantly inferior sensitivity compared to MRI and frequently misses small lesions 3
• Do not skip contrast unless contraindicated - Post-contrast T1-weighted imaging is essential for optimal tumor delineation 3, 2
• Do not omit SWI sequences - Calcifications provide important diagnostic information 3
• Recognize pseudoprogression - Increases in abnormalities on neuroimaging in the first months after radiotherapy should not automatically be considered treatment failure 1

Timing Considerations

For postoperative imaging, MRI should be performed within 72 hours after surgical removal to assess residual tumor, as this becomes the new baseline for surveillance 1