Computerized optimization of 125I implants in brain tumors

A computer program for treatment planning for the interstitial radiotherapy of brain tumors with 125I stereotactic implants is presented. To minimize brain traumatization only 1-3 catheters loaded with several seeds are implanted. It is possible to position the catheters very accurately due to CT guided stereotactic techniques. Precise treatment planning is necessary because of the high dose gradient of the radiation field. Two planning methods are available: conventional planning with interactive optimization of source configurations and an automatic optimization procedure. The goal of optimization is to identify source parameters (catheter positions and seed activities) for which a prescribed dose at the target surface is approximated as closely as possible.

[CT kinetics of intratumor liposome deposits]

CT follow-up studies of liposome-entrapped metrizamide after intraneoplastic injection into neurogenic s.c. rat tumors were performed. By closely resembling clinical examination conditions, the experimental design has proven suitable in determining the in vivo kinetics of these interstitial liposome deposits. When compared to free metrizamide which may be considered an analogue of water-soluble chemotherapeutics, the encapsulation of metrizamide in liposomes resulted in a retarded decline of the contrast enhancement. Diffusion of liposomes could not be detected and the X-ray attenuation values measured within the liposome deposits continuously decreased with time for both types of liposomes. In the case of multilamellar vesicles, this significantly corresponded to a zero order kinetics with a mean halflife of 300 h. An initial increment in the X-ray attenuation of the liposome deposits might be due to the interstitial absorption of the water component of the liposome-dispersion. Because of the pronounced retardation effect of multilamellar liposomes resulting in a 140-fold prolongation of the interstitial retention time of metrizamide and due to their release kinetics these vesicles may be an appropriate carrier system for a local interstitial chemotherapy modality. Small unilamellar vesicles having an interstitial half-life of 14 h may be used as a faster component of a composed therapy system.

Diagnostic value of the stereotactic approach to focal lesions in the deep brain of children and adolescents

Since it is relatively harmless, stereotactic biopsy has become in recent years a useful method for the diagnostic assessment of lesions deep in the brain, which are not accessible to open surgery. With the aid of stereotaxis, focal lesions only a few millimeters in diameter can be approached in every location in the brain with high precision. Since stereotaxis does not require general anesthesia, or at most requires only a very shallow anesthesia, it can also be applied to young infants or persons of advanced age. Experience with stereotactic biopsy exploration of lesions of various kinds in the deep brain of 74 children and adolescents, out of a sample of 260 patients of all age groups who received stereotactic biopsy, is reported. Our aim is to demonstrate and discuss the advantage of this contemporary method for child neurology and neurosurgery. In many medical centers in the world where stereotactic tumor biopsy has been established, it has become an important criterion for the choice of treatment.

Three dimensional image correlation of CT, MR, and PET studies in radiotherapy treatment planning of brain tumors

A treatment planning system for stereotactic convergent beam irradiation of deeply localized brain tumors is reported. The treatment technique consists of several moving field irradiations in noncoplanar planes at a linear accelerator facility. Using collimated narrow beams, a high concentration of dose within small volumes with a dose gradient of 10-15%/mm was obtained. The dose calculation was based on geometrical information of multiplanar CT or magnetic resonance (MR) imaging data. The patient's head was fixed in a stereotactic localization system, which is usable at CT, MR, and positron emission tomography (PET) installations. Special computer programs for correction of the geometrical MR distortions allowed a precise correlation of the different imaging modalities. The therapist can use combinations of CT, MR, and PET data for defining target volume. For instance, the superior soft tissue contrast of MR coupled with the metabolic features of PET may be a useful addition in the radiation treatment planning process. Furthermore, other features such as calculated dose distribution to critical structures can also be transferred from one set of imaging data to another and can be displayed as three-dimensional shaded structures.

[Cystic craniopharyngiomas: computed tomography in the pretherapeutic evaluation and control of treatment results following intracystic contact irradiation]

A report is given on the treatment planning by computed tomography and monitoring in 37 cases of preponderantly cystic craniopharyngiomas with different solid tumor parts. Colloidal yttrium 90 silicate was used for the intracystic contact irradiation. Two pretherapeutic forms of the solid tumor parts were found in CT examination which correlated with different courses: 1. the polymorphic type and 2. the type with a smooth outline. A posttherapeutic decrease of the cystic volume was observed in 74% of type 1 cases (n = 19) and in 89% of type 2 cases (n = 18). An increase in volume was only found in type 1 (21%). An increase of the solid tumor part was also found exclusively in the polymorphic type (68%). An additional external irradiation should be considered for this CT manifestation of the tumor, as the solid tumor part is not exposed in intracystic contact irradiation.

[Intracranial manifestation of lymphomatoid granulomatosis (Liebow's disease)]

An intracranial manifestation of lymphomatoid granulomatosis occurs in 20% of patients. In the case of a 56-year-old patient it is shown that a relative long period can pass from the first neurological symptoms to histological diagnosis by stereotactic brain puncture. Over 15 months, follow-up studies were performed using computed tomography and magnetic resonance.

Correction of spatial distortion in MR imaging: a prerequisite for accurate stereotaxy

With magnetic resonance (MR) imaging, accurate spatial information--critical for effective stereotaxy--demands a homogeneous static field and linear gradients. Inhomogeneities and nonlinearities induced by eddy currents during the pulse sequences distort the images and produce spurious displacements of the stereotactic coordinates in both the x-y plane and the z axis. These errors in position can be assessed by means of two phantoms placed within the stereotactic guidance system--a "two-dimensional phantom" displaying "pincushion" distortion in the image (i.e., x, y) plane, and the "three-dimensional phantom" displaying displacement, warp, and tilt of the image plane itself. The pincushion distortion can be "corrected" (reducing displacements from 5 to 1-2 mm) by calculations based on modeling the distortion as a fourth order two-dimensional polynomial. Based on these corrected images, errors in the z coordinate and tilt of image planes may be corrected by adjustment of the gradient shimming currents. Such correction not only implements stereotaxy under MR guidance but also provides for the accurate transfer of anatomic/pathologic information between MR and CT images.

In vitro model for the response to irradiation of different types of human intracranial tumours

Twenty-seven human low and high grade gliomas and five meningiomas were cultured in vitro as tumour tissue and/or tumour cells. Cell survival or growth was taken as a measure of radiation response. Astrocytomas II-III and glioblastomas manifested individual patterns of radiosensitivity, ranging from 10 to 90 Gy. Meningiomas did not react. Our findings are consistent with the differences in radiosensitivity of human gliomas experienced clinically and corroborate the validity of the in vitro model.

Perspectives of radiotherapy

The 5 years' survival rate of all cancer patients is 35-45%. In that survival rate radiotherapy takes part in 15%. By further development of radiological methods and techniques radiotherapy gains significance in the recent time. Optimizing radiation planning and tactics, all modern imaging techniques are applied consequently. The radiotherapist must be able to asses their immanent specifity which should remain object of the radiological training, even if separated into therapy and diagnostics. Dose distribution is calculated by computer; three-dimensional planning is done in tumors of the mediastinum, oesophagus carcinoma and paraaortic lymphomas. Critical description of radiation techniques, results, problems and prognoses are given by results in tumors of the epipharynx and gastric cancer. After-loading, done until now only in gynaecological tumors, is performed in recurrences of pharyngeal tumors by individually shaped applicators. Reducing the number of therapy failures as well as possible, the application of higher tumor doses, new kinds of rays as neutrons and combinations with physical and chemical methods is outlined. Modifications of radiation volumes are discussed, especially the irradiation of the complete abdomen in ovarian cancer, the irradiation of the complete body surface by electrons in mycosis fungoides, and the total body irradiation prior to autologue bone marrow transplantation. Modifications of fractionation are shown in short-time radiation of bone metastases and single-time radiation of brain lesions. Low penetrating electron therapy facilitates intraoperative single-time irradiation. Because of higher biological efficiency neutrons and heavy ions allow to irradiate low sensible tumors or recurrences embedded in fibrotic tissue respectively. The combination with hyperthermia yields good results in tumors of the head and neck with better local response and total remissions of 59%. There are potentials in synchronising with chemotherapeutics. Remissions of different duration were achieved in 190 patients. Because of neutrotoxicity there are still problems in applicating radiosensitizers. New methods are applied treating endocrine active tumors by labelled hormone precursers.

Stereotactic percutaneous single dose irradiation of brain metastases with a linear accelerator

The effectivity of stereotactic percutaneous single dose irradiations in the treatment of solitary brain metastases has been assessed in a series of 12 consecutive patients. Only radioresistant deeply localized metastases have been treated. Photon-irradiation was carried out with the convergent beam technique using stereotactic localization methods, in a linear accelerator facility. In 11 of the 12 patients no side effects occurred. The first 7 patients, who could be observed 3 months or longer, have been studied in detail. In each of these cases single dose irradiation with 20-30 Gy yielded arrest of tumor growth. In one case a marked decrease in contrast enhancement and in four cases shrinkage of the metastasis as well as a marked decrease of the edema occurred. In every patient a marked, sometimes dramatic improvement of the clinical condition was achieved, beginning a few days after irradiation. Stereotactic radiosurgery is a valuable tool in the treatment of inoperable, radioresistant brain metastases, the major advantage being high efficacy and smoothness of the procedure, as well as extremely short hospitalization times (2-3 days).

Cerebral radiation surgery using moving field irradiation at a linear accelerator facility

A modified irradiation technique at a linear accelerator facility for radiation surgery within the brain is described consisting of several moving field irradiations in non-coplanar planes. Using collimated narrow beams, a localization system and special computer programs for precise patient positioning, a high concentration of dose within small, well circumscribed volumes is obtained. Resulting dose distributions were studied experimentally and by calculations. A simple algorithm for treatment planning was developed and based on CT images. Radiation surgery within the brain is now technically feasible at our linear accelerator. Seventeen patients have now been treated.

Neurosurgical treatment of cancer pain

Neurosurgical pain operations in carcinoma patients should always be considered when conservative treatment methods fail or pain relief can be attained only at the cost of undesired side effects. The therapeutic spectrum of neurosurgery has been appreciably extended in recent years. Due to the introduction of percutaneous surgery methods, the operations have become less burdensome, so that carcinoma patients who were formerly regarded as inoperable can also be given neurosurgical pain treatment. The advances in neurophysiology have led to a better understanding of pain mechanisms, in consequence of which the various possibilities of treatment can be employed more specifically with prospects of better treatment results. The spectrum of neurosurgical treatment extends from destructive measures (rhizotomies, cordotomies, thalamotomies, neurolytics) via intrathecal administration of morphine-like substances to the augmentative nondestructive neurostimulation techniques. Despite the advances in conservative therapy of cancer pain, in many cases, a neurosurgical procedure is most efficacious in controlling carcinoma pain.

Involvement of dopamine in amygdaloid kindling

The concentrations of dopamine, noradrenaline, and dihydroxyphenylacetic acid were determined in the amygdala, neostriatum, neocortex, hippocampus, brain stem, and hypothalamus of cats, which had had 9 to 14 tonic-clonic kindled seizures. No significant biochemical changes were observed compared to control cats. Pharmacological manipulations of dopamine receptors (haloperidol, apomorphine) did not modify the kindling procedure. According to the data it seems unlikely that dopamine plays a major role in amygdaloid kindling.

Stereotactic computer tomography with a modified Riechert-Mundinger device as the basis for integrated stereotactic neuroradiological investigations

For stereotactic biopsy, intracavitary and interstitial irradiation of intracranial tumours, stereotactic CT investigations are of utmost importance. Target-points within a tumour as well as the tumour-outlines have to be transferred precisely from transverse and longitudinal CT sections to stereotactic X-ray images. For this purpose, the stereotactic apparatus of Riechert and Mundinger has been equipped with a fixation system of carbon fibre and a measuring phantoma of plexiglass with embedded steel wires allowing stereotactic CT scanning without artefacts. The stereotactic coordinates (x, y, z) of any target point can be taken directly from transverse CT images with high accuracy. The tumour outlines can be transferred to the stereotactic coordinate system from longitudinal CT reconstructions using special computer programmes. Precise transfer is possible if the CT investigation is performed stereotactically.

Combined use of stereotaxic CT and angiography for brain biopsies and stereotaxic irradiation

A Riechert Mundinger stereotaxic device was modified to enable artifact-free computed tomographic (CT) scanning with the stereotaxic frame attached to the patient's head. A localization system was developed allowing determination of the XYZ coordinates of the target point directly from the CT cut. Angiography was performed intraoperatively with the stereotaxic frame attached. Coronal and sagittal CT reconstructions were enlarged to the radiographic magnification to allow direct comparison with angiography. CT offered optimum localization of the target, whereas angiography determined the safest approach. Computer programs were developed to enable three-dimensional radiotherapy planning. 125I seeds were implanted for treatment of low-grade gliomas and solid craniopharyngiomas. Yttrium-90 was applied in cystic craniopharyngiomas. Intracavitary rhenium-186 application was abandoned because of frequent cyst recurrence and leakage from the cyst.

Radioisotope therapy of cystic craniopharyngomas

Eighteen patients suffering from cystic craniopharyngeoma were treated with intracavitary irradiation. The beta-emitting radioisotope 90y (2.25 MeV) was instilled into the cyst following stereotactic puncture of the space-occupying lesion. The surgical approach was planned using angiograms and reconstructed transmission computer tomography (TCT) coronal and saggital sections. Therapy was devised to deliver 20,000 rad to the cyst's wall. Eleven patients received follow-up TCT examinations after four months. Eight of 11 patients had a significant volume decrease in the craniopharyngeoma cyst. In two patients, the cystic volume remained unchanged; one had progression of disease. It is concluded that the intracavitary treatment of cystic craniopharyngeoma will result in a reduction of the size of the space-occupying lesion.

Opioid peptides and blood pressure regulation

Immunohistochemical and functional studies suggest that opioid peptides are involved in blood pressure regulation. Endorphin and enkephalins contained in the brain seem to exert their effects by mediation of cardiovascular centers in the brain stem. Additional effects on blood pressure may be exhibited by circulating opioid peptides released from the pituitary and adrenal gland which may act at both central and peripheral sites. It is expected that further studies will complete our knowledge about the interaction of opioid peptides and blood pressure regulation and will result in therapeutic applications.

Direct visualization of intracranial tumours in stereotactic and angiographic films by computer calculation of longitudinal CT-sections: a new method for stereotactic localization of tumour outlines

A new method for the direct transformation not only of a target point, but also of the whole tumour outlines from sagittal, coronal, and oblique computer calculated CT-reconstructions to stereotactic X-ray films of any scale is presented. The role of this method in the stereotactic therapy of intracranial tumours and the possibilities which are thus provided are discussed.

[Pre and intraoperative volume determination of craniopharyngioma cysts (author's transl)]

Exact cystic volume measurement is a prerequisite to proper 90Y dosage in the therapy of of intracavitary monocystic craniopharyngiomas. The method of intraoperative volume measurement by a radionuclide dilution technique is compared to results obtained by preoperative volumetry using computer tomography. Both methods gave congruous results. It is pointed out that gamma camera scintigrams are essential for the early detection of complications.

[Simultaneous therapy of gonorrhea with penicillin and probenecid. Serum penicillin picture]

19 patient received penicillin and probenecid. The resulting serum concentrations of penicillin was determined. In regimen I 4 mill. IU depot penicillin was given i.m. simultaneously with 1 g probenecid orally. In regimen II probenecid was given 30 min prior to the administration of penicillin. In both series the average serum concentrations of penicillin were not significantly different (p = 0.01).

Chronic electrical stimulation of the thalamic unspecific activating system in a patient with coma due to midbrain and upper brain stem infarction

Chronic intermittent bipolar electrical stimulation of the left nucleus reticulatus polaris thalami was performed in a patient in a state of subcoma due to ischaemic infarction of wide medial parts of the midbrain, mainly the tegmentum, and the right-sided mediobasal parts of the forebrain. Stimulation immediately resulted in autonomic reactions and behavioural arousal reactions during the periods of stimulation. Longterm effect consisted of a rise in the level of clinical responsiveness for a period of seven weeks. A preexistent severe pneumonia disappeared completely after one week of stimulation and returned after seven weeks. The results are discussed on the basis of the pathoanatomical findings and of the physiological functions of the damaged as well as of the stimulated areas.

The influence of chronic deep brain stimulation on excitability and morphology of the stimulated tissue

Bipolar electrical stimulations of the rostal hippocampus and of the amygdala were performed at irregular intervals in wakeful unrestrained cats via chronically implanted glass-insulated stainless steel electrodes. The excitability of the stimulated tissue remained unchanged during the whole investigation period of six months up to one and a half years, as was revealed by regularly performed comparisons of shape, latency, and amplitude of evoked potentials elicited by electrical stimulation of the rostral hippocampus and recorded within the ipsilateral mammillary body. The histological examination of the stimulated tissue revealed a fibrillary gliosis due to the trauma caused by the insertion of the electrodes, but no signs of additional tissue damage due to electrical stimulation or chronic mechanical irritation. The results indicate that it is possible to perform therapeutic stimulations of deep brain structures for long periods without inducing relevant changes in morphology or electrical responsiveness of the stimulated tissue. No kindling phenomena are to be expected, if the stimulations are performed at irregular intervals.

[Problems of peripheral nerve surgery in amputation stump pain and phantom limbs]

Follow-up examination of 17 patients with severe and lasting stump and phantom limb pain which could not be improved by analgetics and who then underwent surgical procedures at the neuroma. The results were discouraging. Only 2 patients showed a lasting improvement. Resection of the neuroma and injection of alcohol into the neuroma seem to be successful only if the preoperative history of pain is very short or if there is an isolated injury of a peripheral nerve and a subsequent single neuroma.