Objective: Pilocytic astrocytomas may show heterogeneous histopathological and imaging features which are commonly attributed to malignant gliomas. Using magnetic resonance (MR) spectroscopy, we assessed if pilocytic astrocytomas show increased choline (tCho), classically related to proliferation and malignancy of gliomas.
Methods: Sixteen patients (five adults, age 20-55 years and 11 children, age 6 months-15 years) with histologically proven pilocytic astrocytomas were evaluated retrospectively. MR spectroscopy was performed prior to surgery or biopsy in all patients. Intensities of tCho and total creatine (tCr) signals were normalised to the respective signal intensity of contralateral brain tissue and statistically evaluated for group differences between adults and children.
Results: The tCho levels covered a wide range with a trend towards elevated values, especially in the adult group. tCho levels ranged from 0.78 to 2.92 in the paediatric group (mean 1.15) and from 1.15 to 3.03 in the adult group (mean 1.35). Diminished or normal tCr values were observed in all patients but one.
Conclusions: The well-known positive correlation between increase of tCho and the grade of gliomas seems to be violated by WHO grade I pilocytic astrocytomas showing a wide range of tCho values with an even marked increase in some cases. No significant differences have been identified in the MR spectroscopy metabolite profiles between paediatric and adult pilocytic astrocytomas.