Use of relocatable stereotactic frame to integrate positron emission tomography and computed tomography images: application in human malignant brain tumours

Computer planning of stereotactic iodine-125 seed brachytherapy for recurrent malignant gliomas

At St Thomas' Hospital, we have developed a computer program on a Titan graphics supercomputer to plan the stereotactic implantation of iodine-125 seeds for the palliative treatment of recurrent malignant gliomas. Use of the Gill-Thomas-Cosman relocatable frame allows planning and surgery to be carried out at different hospitals on different days. Stereotactic computed tomography (CT) and positron emission tomography (PET) scans are performed and the images transferred to the planning computer. The head, tumour and frame fiducials are outlined on the relevant images, and a three-dimensional model generated. Structures which could interfere with the surgery or radiotherapy, such as major vessels, shunt tubing etc., can also be outlined and included in the display. Catheter target and entry points are set using a three-dimensional cursor controlled by a set of dials attached to the computer. The program calculates and displays the radiation dose distribution within the target volume for various catheter and seed arrangements. The CT co-ordinates of the fiducial rods are used to convert catheter co-ordinates from CT space to frame space and to calculate the catheter insertion angles and depths. The surgically implanted catheters are after-loaded the next day and the seeds left in place for between 4 and 6 days, giving a nominal dose of 50 Gy to the edge of the target volume. 25 patients have been treated so far.

Neurosurgical navigation using a noninvasive stereoadapter

A neurosurgical navigation system incorporating a multiarticulated arm and an isocentric stereotaxic mechanism has been developed. The usefulness of the navigation system has been increased by using it in combination with Laitinen's noninvasive, accurately reproducible stereoadapter. Stereotaxic microsurgery and surgical navigation was performed successfully in 30 cases with these systems.

Stereotactic brachytherapy for malignant glioma using a relocatable frame

Interstitial brachytherapy for recurrent gliomas normally necessitates the invasive application of a stereotactic frame by screw-fixation which must be kept on for several hours. The use of a relocatable stereotactic frame offers many advantages over conventional systems. We present our experience in 18 patients and verify that the frame used is accurate, comfortable, well tolerated and associated with no major disadvantages.

Cell proliferation in serial biopsies through human malignant brain tumours: measurement using Ki67 antibody labelling

Cell proliferation was assessed in brain tumours using the monoclonal antibody Ki67 which recognizes a nuclear antigen expressed by proliferating cells. Using a novel stereotactic biopsy procedure, serial 1 cm biopsies were taken along a trajectory through six malignant brain tumours. Specimens were also obtained from 10 other brain tumours during conventional surgery. The percentage of Ki67 positive cells was determined as a fraction of the total number of tumour cells present. The Ki67 index for anaplastic astrocytomas and glioblastomas was significantly higher (Ki67 index range 11-18%) than that for benign or low grade tumours. Significant variation in proliferation was measured along the biopsy track through individual tumours (e.g. 0-12.3%) which correlated well with histological appearance. The Ki67 indices of normal brain were very low. In general the Ki67 indices increased with increasing histological grade and also appear to be a useful indicator of the active tumour volume and margin. This method provides spatial information about tumour proliferation which may be used to decide between different treatments and relate to prognosis.