What is the recommended MRI follow‑up interval for meningioma?

MRI Follow-Up Intervals for Meningioma

For WHO grade 1 meningiomas, perform MRI brain without and with IV contrast every 6-12 months, with the option to extend intervals after demonstrating stability, continuing surveillance for at least 10 years due to potential for late recurrences. 1, 2

Surveillance Protocol Based on WHO Grade

WHO Grade 1 (Benign) Meningiomas

• Initial surveillance: MRI brain without and with IV contrast every 6-12 months 1, 2, 3
• After tumor demonstrates stability (typically after 5 years), consider extending intervals to longer periods 2, 3
• Continue annual surveillance for at least 10 years minimum, as late recurrences can occur 2
• The frequency can be adjusted based on combined histologic and molecular profiling to optimize imaging follow-up 1

WHO Grade 2 (Atypical) Meningiomas

• More frequent surveillance required compared to grade 1 tumors 1, 2
• MRI brain without and with IV contrast every 3-6 months initially 2
• Consider adding perfusion MRI as a helpful adjunct to conventional MRI 2
• Somatostatin receptor PET/CT or PET/MRI provides more accurate assessment, particularly useful for these higher-grade tumors 1, 2

WHO Grade 3 (Malignant) Meningiomas

• MRI brain without and with IV contrast every 3 months initially 2
• Consider adding spine imaging if there are concerns for CSF dissemination 2
• These tumors necessitate more frequent follow-up, especially after treatment 1

MRI Technical Specifications

Essential sequences to include: 1, 2

• Pre- and post-contrast T1-weighted sequences
• T2 FLAIR sequences to evaluate for vasogenic edema
• SWI sequences for detecting intratumoral calcifications
• Consider perfusion MRI for grading and detecting recurrence 2

Post-Treatment Surveillance Adjustments

After Surgical Resection

• The postradiotherapy MRI should be considered the "new baseline" rather than the postsurgical MRI 1, 2
• Simpson resection grade influences recurrence risk and should guide surveillance intensity 4, 5

After Stereotactic Radiosurgery (SRS)

• Initial close surveillance as tumor typically stabilizes within first several years 1
• 95% of tumors achieve steady state by 5 years and 90% by 10 years 1
• Once tumor attains steady state, routine radiological follow-up can be extended to longer intervals 1, 6
• Clinical follow-up with routine neurological exams and ophthalmological assessment should continue 1

Advanced Imaging Considerations

Consider additional imaging modalities when: 1, 2

• Suspected recurrence with equivocal findings on conventional MRI
• Differentiating between tumor recurrence and post-treatment changes
• Tumor extension is unclear on conventional imaging

Somatostatin receptor (SSTR) PET imaging provides superior detection sensitivity compared to contrast-enhanced MRI alone and is particularly valuable for WHO grade 2 and 3 tumors 1, 2, 6

Special Populations Requiring Modified Surveillance

Genetic Syndromes

• SMARCE1-associated clear cell meningiomas: yearly MRI brain and spine until age 30, then every 2-3 years 2
• LZTR1-associated meningiomas: MRI brain and spine every 2-3 years, beginning at age 15-19 2
• Patients with NF2 and other genetic syndromes require specialized surveillance protocols 2

Radiation-Induced Meningiomas

• These tumors exhibit high absolute and relative growth rates after discovery (median 0.62 cm³/year) 7
• Tend to be clinically aggressive with 43.6% being WHO grade 2 at first resection 7
• High recurrence risk after surgery (41% progression rate) with median time to progression of 28 months 7
• Require more intensive surveillance given aggressive behavior 7

Common Pitfalls and Caveats

Post-treatment changes can mimic tumor recurrence on conventional MRI, making interpretation challenging 2

Inflammatory lesions may present with increased uptake on SSTR PET, leading to false positives, though rare cases of meningioma may show decreased or absent uptake 2

Larger tumor size at discovery is associated with growth (HR 1.2, p=0.039), requiring closer surveillance 7

Disruption of the arachnoid layer on MRI is a stronger risk factor for recurrence (HR 9.41, p<0.001) than high-grade histology alone (HR 5.15, p=0.001), and should prompt more frequent imaging 4

Heterogeneous contrast enhancement (OR 2.51, p=0.014) and edema volume (OR 1.00, p=0.037) on preoperative MRI are associated with high-grade histology and should influence surveillance intensity 4