FIG 3. Patient 9 (astrocytoma, WHO grade II).

Top left and top right, T2-weighted axial fast spin-echo images were used to determine the tumor area before resection.

Middle left and middle right, Comparable slices obtained at the point at which the neurosurgeon considered the resection to be complete (first control) were used to calculate the residual tumor volume.

Bottom left and bottom right, T2-weighted images at the same position were used to measure very small areas of residual tumor tissue at the end of the operation before closing the craniotomy.