Study on intracranial meningioma using PET ligand investigation during follow-up over years [SIMPLIFY]

Meningiomas are a common type of intracranial tumor. Although meningiomas often
are histopathologically benign, their localization can lead to severe
neurologic disturbances, such as epilepsy and cranial nerve deficits.
Particularly meningiomas of the skull base and/or near large vascular
structures are notorious. Treatment consists of surgery, radiotherapy or a
combination of both. Treatment planning and follow-up can be troublesome when
based on conventional contrast-enhanced MRI: 1. The distinction between
post-operative and post-radiotherapy tissue enhancement ('scar tissue'or
'radionecrosis') and tumor remnant is difficult. 2. The identification of tumor
invasion in venous structures, e.g. cavernous sinus and superior sagittal sinus
is difficult. 3. The judgment of possible invasion in bony structures of the
skull base can be difficult. 4. It is problematic to evaluate tumor invasion in
a contrast-enhancing 'dural tail' on MRI.
The PET-tracer 11C-methionine is involved in the amino-acid metabolism and is
used for diagnostic PET-scanning (MET-PET) purposes in different types of
intracranial diseases. With this type of investigation information about the
metabolism of a lesion is obtained.
Based on the literature MRI and PET have proven to be complementary diagnostic
tools in many oncologic conditions. The first renders mainly structural
(anatomic) information and the latter mainly molecular (metabolic) information.
With this study we want to investigate if combined MRI/MET-PET investigation
leads to a different conclusion/interpretation than MRI-scanning only.

Compare the combined MRI/MET-PET report to the MRI-only report.

35 patients with intracranial meningioma, who received stereotactic
radiotherapy (with a pre-radiotherapy MET-PET for radiation planning purposes)
and a longterm follow-up (of preferably > 5 years), will be asked to undergo
MET-PET again in adjunct to their regular follow-up MRI-scan.
For each participant a separate MRI/MET-PET and MRI-only report will be made.
Agreement between these reports will be calculated (Cohen's kappa).

Patients will have to make one extra hospital visit. We will try to combine MRI
and MET-PET scanning on the same day, but often this will not be possible due
to logistics.
The MET-PET scan will take approximately 40 minutes. Patients will haven an IV
access line placed in their arm or hand. The total hospital visit will take
approximately 60 minutes.
MET-PET scanning is regularly performed for many different clinical
indications. Until now no adverse events have been encountered with this type
of investigation in our hospital. No adverse events of this type of scanning
have been described in the literature.