Perfusion MRI for vestibulair schwannoma, a growth predictor?

Vestibular schwannoma remains difficult in decision making and timing of
treatment. The difficulty lies in the unpredictable growth of these tumors,
whether or not to decide for immediate treatment (operation or radiotherapy).
Until now we judge tumors on their clinical and radiological features. The
question is in which cases tumor growth is progressive and requires treatment.
With the new perfusion MRI, vascularisation in tumors can be visualized. This
technique has already been used in grading gliomas, prediction of early lung
cancer and treatment reaction.
Perhaps this new imaging method is applicable for the vestibular schwannomas
and the decision making is going to be easier in the future. First we perform
a pilotstudy to measure the feasibility for a greater study.

Optimalisation of the perfusion protocol for vestibular schwannoma.

Feasibility study

Growth:
Growth is defined as, 4mm/yr or 20% volume expansion. Measured with MR imaging

Perfusion
3 Tesla MR scan. Conventional MR axial plane, T1 weighted (TR/TE= 600/14ms),
T2 weighted (TR/TE= 5400/99 ms) and FLAIR imaging (TR/TE/TI = 9000/ 110/ 2100
ms). Perfusion is measured after first passage of gadolinium T2*W *PRESTO*
sequentie, using fast automatical (5ml/s) iv administration (0,2 mmol/kg).
First images are being used as the baseline.
During the first passage of the contrast agent the T2* relaxation time and the
T2* signal intensity decreases. The difference in relaxation time (*R2*) can be
calculated with the formula *R2*(t) = {-In(S(t)/S(0))}/TE. Where TE is the echo
time, S(0) the baseline signal intensity and S(t) is the signal intensity at a
particular time. *R2* is depending on the quantity of the contrast agent within
the lesion and the cerebral vlood volume (CBV) is the surface under *R2* curve.
With this data the relative CBV maps can be calculated and perfusion can be
measured.

Risks are associated with vena puncture and contrast agent administration.