The authors suggest the use of stereotactic radiosurgery as the preferred treatment for recurrent acromegaly resulting from unsuccessfully resected tumors.

Clinical experience shows that an increasing number of patients undergoing radiation treatment for recurring acromegaly or acromegaly persisting after surgery are treated with octreotide. We, therefore, performed a follow-up study of patients undergoing stereotactic radiosurgery (Gamma Knife) to determine whether this medication has an influence on the ultimate result of radiation therapy in either a positive or negative sense. It has been suggested that the combination of radiation with antisecretory drugs may increase the effectiveness of radiation. A follow-up study of 31 patients suffering from recurrent acromegaly and acromegaly persisting after surgery, and who had been treated with stereotactic radiosurgery, showed that patients treated with octreotide at the time of radiation application simultaneously reached a normal level of growth hormone and insulin-like growth factor-I only after a significantly longer interval than patients who did not receive the drug. The two groups of patients did not demonstrate significant differences in the main clinical findings (age, sex, target volume, radiation dose, baseline growth hormone, and baseline insulin-like growth factor-I).

Seven patients with metastatic tumour in the pituitary-hypothalamic axis were investigated by MRI. The main clinical problems were diabetes insipidus (5 cases) and general pituitary dysfunction (2 cases). No patient had visual or oculomotor symptoms. In 6 of the 7 patients the primary malignant tumour was known, but no patient had symptoms from the primary tumour; 1 had symptoms from metastases in locations other than the pituitary gland. In one patient no primary tumour was known. MR detection of a second, clinically silent, 5 mm lesion in the posterior cranial fossa initiated the search for primary tumour. MRI showed purely suprasellar tumours in 3 patients and intra- and suprasellar tumours in 4. The latter were dumbbell lesions with only a small bridge of tissue connecting the intra- und suprasellar portions. Six of the 7 suprasellar tumours seemed to be in the infundibular recess of the third ventricle; in 5 the infundibulum was visible as an enhancing linear structure at the postero-inferior border of the tumour. The pituitary fossa was normal in all cases.

We report magnetic resonance imaging (MRI) findings in two obligate and four facultative carriers for the "classical" X-linked form of Pelizaeus-Merzbacher disease (PMD). In T2-weighted images MR revealed bilateral multiple areas with signal hyperintensity in the periventricular and subcortical white matter in five women. Until suitable and closely linked DNA probes are found for heterozygote determination, MRI may represent a suitable means for carrier detection in individuals at risk in PMD families.

In clinical follow-up studies after radiosurgery, imaging modalities such as computerized tomography (CT) and magnetic resonance (MR) imaging are used. Accurate determination of the residual lesion volume is necessary for realistic assessment of the effects of treatment. Usually, the diameters rather than the volume of the lesion are measured. To determine the lesion volume without using stereotactically defined images, the software program VOLUMESERIES has been developed. VOLUMESERIES is a personal computer—based image analysis tool. Acquired DICOM CT scans and MR image series can be visualized. The region of interest is contoured with the help of the mouse, and then the system calculates the volume of the contoured region and the total volume is given in cubic centimeters. The defined volume is also displayed in reconstructed sagittal and coronal slices. In addition, distance measurements can be performed to measure tumor extent. The accuracy of VOLUMESERIES was checked against stereotactically defined images in the Leksell GammaPlan treatment planning program. A discrepancy in target volumes of approximately 8% was observed between the two methods. This discrepancy is of lesser interest because the method is used to determine the course of the target volume over time, rather than the absolute volume. Moreover, it could be shown that the method was more sensitive than the tumor diameter measurements currently in use. VOLUMESERIES appears to be a valuable tool for assessing residual lesion volume on follow-up images after gamma knife radiosurgery while avoiding the need for stereotactic definition.