The usefulness of computed tomography during and after radiation therapy in patients with brain tumors

High-dose conformal radiotherapy influenced the pattern of failure but did not improve survival in glioblastoma multiforme

BACKGROUND AND PURPOSE

Although glioblastoma multiforme is clearly radiation-resistant, there is evidence of a dose-dependent response relationship. The purpose of the study was to evaluate the impact of higher dose by rotational multileaf collimator (MLC) conformal radiation therapy.

MATERIALS AND METHODS

From 1984 to 1995, 38 consecutive cases with intracranial glioblastoma multiforme were treated using the rotational MLC conformal therapy. There were 25 men and 13 women with a median age of 47 years (12-73 years, mean 46.5 years). Median Karnofsky performance score was 80 (30-100, mean 78.2). Median tumor volume was 64 cc (8-800 cc, mean 110.3 cc). All underwent surgical intervention (only biopsy in 1, partial resection in 13, subtotal resection in 21, and gross total resection in 3). Radiation dose to was 60 to 80 Gy (median 68.5 Gy, mean 68.3 Gy) in 21 patients treated before 1990 and 90 Gy in the 17 patients thereafter. Biweekly i.v. chemotherapy was also administered for both arms.

RESULTS

The 1-year, 2-year, 5-year, and 10-year overall survival rates were 75%, 42%, 20%, and 15%, respectively. Univariate analysis showed the initial tumor volume, residual tumor volume, and Karnofsky performance score were statistically significant factors for survival. Only the residual tumor volume was statistically significant by multivariate analysis. The 5-year survival rate of patients with residual tumors of 5 cc or less in volume was as good as 37%. Survival of the 90-Gy Group appeared inferior to that of the Low-Dose Group, though no statistical difference was seen (the 3-year survival was 40% vs. 22%). Local failure was observed in 16 of the 19 recurrences in the Low-Dose Group, whereas it was observed in only 4 of the 13 recurrences in the 90-Gy Group. The difference in pattern of failure was statistically significant. Two patients of the High-Dose Group developed radiation necrosis and one died of it.

CONCLUSIONS

The high-dose conformal radiotherapy did not improve survival in the disease, but did change the pattern of failure.

New treatment protocol by intra-operative radiation therapy for metastatic brain tumours

In patients with brain metastasis from lung cancer, we have been able to control local recurrence in approximately 80% of cases. But many of them tend to show brain atrophy with mental deterioration developing a few months after whole brain radiation. To prevent brain atrophy, we have attempted treating patients, whose metastasis was diagnosed as single, by intra-operative radiotherapy (IOR) alone following surgical resection. Among 43 patients, 19 patients who had no metastases other than the brain metastases, were chosen as subjects for active treatment (surgical resection+IOR). Their 1-year survival rate was 75%. Fourteen out of 27 patients with brain metastases from lung cancer received active treatment and their 1-year survival rate was 74%. This result was not inferior to our result of 71 patients who received surgical resection and whole brain irradiation. When no preventive whole brain irradiation was performed, patients were observed every 8 weeks by CT scan in order to ascertain tumour recurrence limited to the treated site or appearance of any new metastatic lesion remote from the treated site. Among all 43 patients, local recurrence was recognized in 7 cases and remote recurrence was observed in 7 cases. Within 6 months, local and remote recurrence was found in 3 cases each. These results were almost the same as those for the usual therapy (surgery plus whole brain irradiation). If such a new lesion is detected, additional radiation can be performed with the possibility of achieving complete remission.

Reversible oedema and necrosis after irradiation of the brain. Diagnostic procedures and clinical manifestations

One hundred and twelve patients with primary brain tumour were followed every 3 months during and after brain irradiation and chemotherapy with brain scanning, EEG and neurological examination. Early delayed radiation reactions were seen in 6 patients. The symptoms developed 2-8 months after irradiation and lasted for 2-3 months. Two types of reactions were observed. One mild form appeared after 2-3 months and was characterized by low-attenuated expansive areas within the irradiated volume, without contrast enhancement on CT scan. Severe reactions appeared in some patients after 6 months, with exacerbation of earlier clinical signs and contrast enhancing lesions on CT. Regression of the CT finding was seen after 3 months. Recognition of this syndrome is important, as a new neurosurgical procedure might cause lasting neurological sequelae in patients who otherwise would recover without treatment.

Subacute brain atrophy after radiation therapy for malignant brain tumor

Brain atrophy with mental and neurologic deterioration developing a few months after radiation therapy in patients without residual or recurrent brain tumors has been recognized. Two illustrative case reports of this pathologic entity are presented. Six autopsy cases with this entity including the two cases were reviewed neurologically, radiographically, and histopathologically. All patients presented progressive disturbances of mental status and consciousness, akinesia, and tremor-like involuntary movement. Computerized tomography (CT) demonstrated marked enlargement of the ventricles, moderate widening of the cortical sulci, and a moderately attenuated CT number for the white matter in all six patients. Four of the six patients had CSF drainage (ventriculoperitoneal shunt or continuous lumbar drainage), however, none of them improved. Histologic examination demonstrated swelling and loss of the myelin sheath in the white matter in all patients, and reactive astrocytosis in three of the six patients. Neither prominent neuronal loss in the cerebral cortex or basal ganglia, nor axonal loss in the white matter was generally identified. The blood vessels of the cerebral cortex and white matter were normal. Ependymal layer and the surrounding brain tissue were normal in all patients. These findings suggested that this pathologic condition results from demyelination secondary to direct neurotoxic effect of irradiation. The authors' previous report was reviewed and the differential diagnoses, the risk factors for this pathologic entity, and the indication for radiation therapy in aged patients with a malignant brain tumor are discussed.

Microwave hyperthermia radiosensitized iridium-192 for recurrent brain malignancy

Twenty-one patients whose solitary detectable biopsy proven recurrent brain malignancies produced Central Nervous System (CNS) symptoms warranting further intervention received 60-minute 43 degrees C (180 degree-minute) interstitial 2450 MHz microwave hyperthermia fractions. All received brain teletherapy prior to recurrence. The first 15 received no brachytherapy and served as a toxicity pilot. All 15 enjoyed neurologic improvement, 12 symptomatic improvement, and 12 objective response as mass reduction and/or tumor necrosis. The next 6 patients were selected with more favorable Karnofsky performance status, no known active malignancy elsewhere, and received afterloading Ir-192 interstitial implantation juxtaposed to radiosensitizing hyperthermia. Volume dose varied from 1000 to 2245 rad, and dose rate from 40 to 100 rad/hr. Dose selected varied as a function of pre-recurrence teletherapy dose, general condition, histologic type, and volume. Neurosurgical debulking, if technically indicated through no additional aperture or trauma, was permitted if consistent with preservation of neurological function. Six enjoyed neurologic improvement, symptom reduction, and objective tumor response; three remain alive, and one experienced transient improvement. Complications, histologic subtypes, autopsy findings, stereotactic approach, thermal monitoring methods and CT follow-up of objective response are presented along with computer dosimetry and isotherm chart. Our microtraumatic universal catheter technique for CT guided stereotactic biopsy, aspiration, decompression, thermal sensory loop, thermalization antennae, and brachytherapy without multiple trauma nor changing catheters is stressed. The rationale for combined modes peculiar to the CNS will be outlined.2+ Proposal for incorporating controlled-release ARA-C chemotherapy polymer micro-rods into the interstitial format will be offered. The preceeding is an FDA-approved controlled clinical trial.(ABSTRACT TRUNCATED AT 250 WORDS)

Evolution of computed tomographic abnormalities in leptomeningeal metastases

We obtained serial cranial computed tomographic (CT) scans from 25 patients with documented leptomeningeal metastases in order to correlate the course of clinical symptoms and cerebrospinal fluid abnormalities with the evolution of CT abnormalities. In almost one-third of patients, relatively specific CT findings such as enhancement of the meninges, obliteration of cisterns or sulci, and hydrocephalus with transependymal edema preceded clinical symptoms. By the time patients became symptomatic, 10 of 25 (40%) had specific abnormalities, and 4 more became specifically abnormal with time. The first scan after cerebrospinal fluid tumor cells were discovered showed specific abnormalities in only 6 patients, but 7 more became specifically abnormal with time. Ventriculomegaly occurred in 18 of 25 patients (72%) and was associated with sulcal and/or cisternal obliteration in one-half of the patients. In 4 patients sulcal and cisternal obliteration developed prior to ventricular enlargement. Multiple small, enhancing cortical nodules were detected prior to symptom onset and discovery of leptomeningeal tumor in 5 patients.

The relative roles of neurological examination, functional abilities, and computed tomography in the definition of treatment failure in patients with anaplastic gliomas

Forty-one patients with anaplastic gliomas undergoing postoperative treatment and evaluation underwent bimonthly evaluation of the following indices of treatment failure: neurological examination; Karnofsky functional rating; and computed tomography (CT) brain scanning. Treatment failure was declared when neurological examination or Karnofsky rating showed increased impairment or when CT scan revealed an increase in tumor sizes. Most often, all three indices simultaneously indicated treatment failure. In only 6 of 41 cases the CT scan alone was the first indication of treatment failure. During the first 6 months of follow-up, tumor enlargement on CT scan as a sole index of treatment failure occurred in only 3 of 26 cases that showed evidence of treatment failure during that time. For patients with glioblastoma, about 6% of treatment failures within 6 months are predicted to be missed by Karnofsky rating plus neurological examination, whereas CT scan alone is predicted to miss about 30%. It would seem reasonable to rely on the neurological examination and Karnofsky rating for follow-up during the first 6 months after surgery, without routine serial CT scanning during that time.

Computerized tomographic and pathologic studies of the untreated, quiescent, and recurrent glioblastoma multiforme

Pathological findings in 20 cases of glioblastoma multiforme were correlated with clinical histories and computerized tomographic (CT) scans. This was done to define the neoplasm in three stages: before treatment, during remission, and during recurrence. The untreated lesions were markedly cellular neoplasms composed predominantly of small anaplastic cells. The radiographic central region of low density was necrosis, the enhancing rim was a cellular zone of viable neoplasm, and the perilesional low-density area was edema with infiltrating tumor. In these 20 cases, all of the identifiable neoplasms lay within the zone of peritumoral edema or contrast enhancement, although small anaplastic cells may have been present in more distant regions. The lesions in remission were remarkable for their minimal mass effect, discrete nature, extensive necrosis, and content of large bizarre glia. The large cells were confined to the original tumor bed and were consistent with neoplastic cells inactivated and immobilized by radio- and chemotherapy. These lesions were accurately localized by CT scanning. The recurrent lesions were heterogeneous, but most were formed of widely disseminated small anaplastic cells. The highly cellular regions of such lesions could be localized by CT scanning, but CT could not detect less cellular foci in the cerebrum, cerebellum, or brain stem. In one patient, the contrast-enhancing lesions of "recurrence," were foci of radionecrosis, underscoring the difficulty in distinguishing this entity from recurrent neoplasm.

Measurements of the volume and density of intracerebral tumors by CT following therapy

For the interpretation of curative measures in patients with cerebral tumors CT is of increasing importance. The therapeutic effects can be demonstrated by close follow-up studies without any of the disadvantage of invasive neuroradiological methods. Our investigations of 125 patients with cerebral tumors are based on volume and density determinations. The CT studies of removed or inoperable tumors followed by radiation and/or cytostatic therapy prove that the best results follow a combination of both. In the present cases however, if CT proves postoperatively, at the end of radiation or at the beginning of the application of cytostatics that there is a residual mass, a complete remission cannot be obtained.

Pineal and ectopic pineal tumors: the role of radiation therapy

Seventeen patients wih pineal tumors and one ectopic (suprasellar) germinoma were treated with radiation therapy. Surgery was restricted to decompression in 16 patients, and only two patients had resection of the tumor. Thirteen of 18 patients are alive without evidence for disease with a ten-year survival rate of 88%. The tumor dose ranged from 4000 rads to 6000 rads. No age or dose dependence in survival was noted, but patients with whole brain irradiation or generous volume to include ventricular system had better survival. No case of spinal metastasis was noted. The possibility of increased incidence of meningeal seeding following surgical intervention is considered. From their data, the authors feel that radiation therapy with or without surgical decompression should be the primary treatment for pinealoma. Surgery can be used for diagnosis and/or treatment of patients who show delayed response to radiation. Recommendation is made for the use of whole brain irradiation to 4000 rads followed by a boost to the tumor area to 5000 rads.

The role of computed tomography in the diagnosis and management of brain tumors

This review article emphasizes the role of computed tomography in the diagnosis and management of brain tumors. The head CT scan has become one of the most precise noninvasive tests in the neurosciences. It has given clinicians more information than they were able to obtain in the past. The subject is covered by subdividing it into several categories: detection of true tumor extent, radiation treatment planning, the immediate postoperative period, treatment responses, failure patterns, detection of radiation-induced damage, and the potential to predict histopathology. The paper is illustrated with examples that emphasize the advantages and some of the limitations of computed tomography as it exists today.

Progressive white matter destruction following irradiation of an extracranial neoplasm

Although numerous "cures# have been reported following surgical extirpation of symptomatic foci of cerebral radiation nerosis, delayed progressive white matter destruction and neurological deterioration may occur in some patients who survive for prolonged periods after operation. The postoperative appearance on CT scans of hypodensity within heavily irradiated white matter structures at a distance from the initial radionecrotic focus or operative site suggests continuing radiation-induced tissue injury and a poor prognosis. Anticipated survival as well as administered radiation dose must be taken into account when "safe# radiation thresholds are calculated.

Prognostic significance of the pretreatment CT scan on time to progression for patients with malignant gliomas

Case histories of 61 patients receiving multimodality therapy for primary malignant brain tumors were reviewed for factors visible on the computerized tomography (CT) scan that correlated with the interval of time from diagnosis and pretherapy evaluation to the time of documented tumor progression. The initial pretreatment CT scan of each patient was reviewed. Midline shift, peritumor low density (edema), the greatest diameter of tumor enhancement, and the greatest diameter of the intratumor low-density area were measured prior to radiation therapy and chemotherapy. Using a Weibull survival probability model, time to tumor progression was most satisfactorily fitted using two covariates, the volume of enhancing tumor (for instance, contrast-enhancing tumor less intratumor low density), and the presence of a peritumor low-density area. Patients who exhibited a small amount of contrast-enhancing tumor with peritumor low density tended to have a longer time to progression than patients with large contrast-enhancing tumor volume and no peritumor low density. Midline shift was not as important a variable as the extent of tumor contrast enhancement or peritumor low density.

The morphologic effects of radiation administered therapeutically for intracranial gliomas: a postmortem study of 25 cases

To investigate the pathologic consequences of therapeutic radiation, this morphologic study evaluated the brains of 25 patients with intracranial gliomas treated both with and without this form of therapy. Although beneficial effects such as the retardation of tumor growth were evident in these studies, among the seventeen patients who received from 5000--6000 rads for malignant gliomas, four developed "late delayed" radiation necrosis. The strong predilection of this tissue response for the white matter adjacent to the neoplasm suggests a local sensitivity which may have been engendered or enhanced by cerebral edema. A fifth case disclosed focal demyelination in the mid-brain suggesting "early delayed" radiation necrosis, and an additional case had distinctive foci of necrosis within the brain stem. Changes of diffuse cerebral edema were noted in many of the radiated brains. It is concluded that radiation therapy in commonly employed dosages for malignant gliomas carries a risk of injury to surrounding cerebral tissues.

Computerized axial-tomography in the preoperative evaluation of an angiofibroma

Computerized axial tomography (CAT) of the head provides the otolaryngologist with an effective diagnostic tool. This technique is particularly useful when used in the preoperative evaluation of head and neck pathology and may be used to define the extent of disease and to direct the surgical approach. The case of a 16-year-old male with an extensive angiofibroma involving the paranasal sinuses and nasopharynx is presented as an example of CAT in preoperative planning of the surgical procedure. Computerized tomography was used initially to define the tumor margins. Serial CAT scans were also obtained at intervals during the patient's preoperative estrogen therapy. Evidence was obtained which suggests CAT may be used to monitor the effects of preoperative hormone management of angiofibromas and in the definition of the optimal time for surgery. In the case presented the final CAT scan provided a detailed and accurate description of the tumor margins which were confirmed at surgery. Our experience with a case of an extensive nasopharyngeal angiofibroma demonstrates the CAT scan to be a useful objective diagnostic method for preoperative planning.

The diagnostic value of CT for radiotherapy of cerebral tumors

The paper deals with CT followup studies on 73 patients with cerebral tumors who received radiotherapy. The value of CT for the indication of radiotherapy, for followup therapy and for the demonstration of therapeutic success are discussed. Since the cerebral tumors become visualized by means of CT in their entire extent and can be differentiated from perifocal edema, the question arises whether radiotherapy should consist of higher doses in the future. It is also suggested that the "clinical malignancy" may be used to compare the behavior of cerebral tumors when there is no exact histological classification. The possible histopathological effects of radiotherapy (edema, necrosis) and their demonstration by CT are discussed.

Computed tomographic evaluation of therapeutically induced changes in primary and secondary brain tumors

A prospective study was initiated to evaluate computed tomography as a method for monitoring therapeutically induced changes in brain tumors. Early postoperative scans may be misleading in the evaluation of residual tumor because of trauma to the blood-brain barrier during operation. The size of the dominant mass (17/25), enhancement (11/25), edema (11/25), and ventricular distortion (14/25) were decreased in many patients after radiation therapy. Occasional tumors increased in size during radiation therapy (3/25). Enlargement of the lateral ventricles developed in 9 of 25 patients. Computed tomography offers definite advantages over nuclide brain scans, angiography and other diagnostic studies for evaluating therapeutically induced changes in brain tumors.

Serial CT studies of a metastatic pinealoma with reference to the radiotherapeutic problems

Serial CT studies performed for 1 year on a female patient suffering from a pinealoma are reported. Under cobalt therapy (5000 rads) a remission of the pinealoma was achieved. A short time later, metastases developed and cobalt therapy was repeated (6000 rads). Rapid tumor remission was seen again, but rapid occurrence of probable metastases too. The question whether radionecrosis or metastases were present cannot be answered.

Computed tomography for neurological intensive care patients. Report on one hundred CT examinations

The first 100 computed tomographic (CT) examinations of the patients on the neurological intensive care ward are discussed and reported on the basis of selected typical findings. Characteristic patterns of the CT findings in determined cerebral diseases are explained. The possibility and necessity of CT observations of the development, of inflammatory and cerebrovascular processes in particular are emphasized. A comparison of our experience with CT and other neuroradiological methods, is made. The clinical diagnoses, including the respective number of cases and the pertinent CT findings, are presented in a Table.