Radiosurgery with a linear accelerator in cerebral arteriovenous malformations / Radiocirurgia com acelerador linear em malformações arteriovenosas cerebrais

OBJECTIVE: To evaluate results achieved with radiosurgery and complications of the procedure when treating arteriovenous malformations with linear accelerator. METHODS: This retrospective study was conducted between October 1993 and December 1996. Sixty-one patients with arteriovenous malformations were treated with radiosurgery utilizing a 6MV energy linear accelerator. Ages of the 32 female and 29 male patients ranged from 6 to 54 years (mean: 28.3 years). The most frequent initial symptom was cephalea (45.9 percent), followed by neurological deficit (36.1 percent). Cerebral hemorrhage diagnosed by image was observed in 35 patients (57.3 percent). Most arteriovenous malformations (67.2 percent) were graded Spetzler III and IV. Venous stenosis (21.3 percent) and aneurysm (13.1 percent) were the most frequent angioarchitecture changes. The dose administered varied from 12 to 27.5Gy in the periphery of the lesion. RESULTS: Out of twenty-eight patients that underwent conclusive angiography control, complete obliteration was achieved in 18 (72 percent) and treatment failed in 7 (absence of occlusion with more than 3 years of follow-up). Four were submitted to a second radiosurgery, and one of these has shown obliteration after 18 months of follow-up. DISCUSSION: Several factors were analyzed regarding the occlusion rate (gender, age, volume, localization, Spetzler, flow, embolization, total of isocenters, prescribed dose and chosen isodose) and complications (total of isocenters, localization, volume, maximum dose, prescribed dose and chosen isodose). Analyzed variables showed no statistical significance for obliteration of the vessel, as well as for treatment complications. The largest diameter of the arteriovenous malformation, its volume and the dose administered did not influence time of obliteration. CONCLUSION: Radiosurgery is effective in the treatment of arteriovenous malformations and can be an alternative for patients with clinical...

OBJETIVO: Analisar os resultados obtidos com radiocirurgia e as suas complicações do procedimento, no tratamento das malformações arteriovenosas com acelerador linear. MÉTODOS: Este é um estudo retrospectivo. Entre Outubro de 93 e Dezembro de 96, sessenta e um pacientes com malformações arteriovenosas foram tratados, utilizando um acelerador linear com 6MV de energia. As idades variaram de 6 a 54 anos (média: 28,3 anos), 32 pacientes mulheres e 29 pacientes homens. O sintoma inicial mais freqüente foi cefaléia (45,9 por cento), seguido de déficit neurológico (36,1 por cento). Hemorragia cerebral diagnostica por exame de imagem foi observada em 35 pacientes (57,3 por cento). A maioria das malformações arteriovenosas (67,2 por cento) eram graus III e IV de Spetzler. Estenose venosa (21,3 por cento) e aneurisma (13,1 por cento) foram as mais freqüentes alterações da arquitetura vascular. A dose administrada variou de 12 a 27,5Gy na periferia da lesão. RESULTADOS: Dos vinte e oito pacientes que se submeteram a controle angiográfico conclusivo, 18 tiveram obliteração completa (72 por cento) e 7 falharam ao tratamento (ausência de oclusão com mais de três anos de seguimento). Quatro pacientes foram submetidos a uma segunda radiocirurgia, e um paciente deste grupo apresentou obliteração em 18 meses de seguimento. DISCUSSÃO: Vários fatores foram analisados em relação ao grau de oclusão (sexo, idade, volume, localização, Spetzler, fluxo, embolização, total de isocentros, dose prescrita e isodose escolhida) e complicações (total de isocentros, localização, volume, dose máxima, dose prescrita e isodose escolhida). As variáveis analisadas não mostraram significância estatística para a obliteração do vaso, bem como para as complicações de tratamento. O maior diâmetro da malformação arteriovenosa, seu volume e a dose administrada não influenciaram no tempo de obliteração. CONCLUSÃO: Radiocirurgia é eficiente no tratamento das malformações arteriovenosas...

LINAC Radiosurgery for Hemangioblastoma

The author performed radiosurgery with linear accelerator(LINAC) on two patients who were unable to receive surgical treatment. A 75-year-old-male patient(case 1) whose main complaints were gait disturbance and headache had undergone total resection of cerebellar hemangioblastoma five years before the admission and the lesion recurred. Because the patient's general condition was poor, radiosurgery with LINAC was performed and at 1 month after the radiosurgery, obstructive hydrocephalus developed, and ventriculoperitoneal shunt was done. After 11 months, follow-up brain magnetic resonance image findings showed the decrease of the size of the tumor, and the patient's consciousness returned to alertness. He could also walk using a cane. A 28-year-old male paient(case 2) whose main complaints were vertigo, ataxia refused to receive surgical resection due to his religious beliefs, and radiosurgery was performed, after cyst aspiration with ommaya reservoir insertion as an alternative. Eighteen months later, the tumor size has decreased and there were no radiosurgical complications. The patient has been followed-up at the outpatient without any notable symptoms. Through these two cases, the authors experienced tumor control by LINAC radiosurgery when surgical treatment is not acceptable. Radiosurgery seems safe and effective in the treatment of hemangioblastoma, but there is the need for further evaluation.

LINAC Radiosurgery for Metastatic Brain Tumors

OBJECTIVE: The authors take a group of patient who have undergone radiosurgery for the treatment of metastatic brain tumor, and conduct a retrospective analysis on the therapeutic response and prognotic factors which influenced the outcome. METHODS: The cases of metastatic brain tumor managed with radiosurgery at our hospital between January of 1996 and December of 2000 were 26. Second radiosurgery was performed for new metastasis in two patients. RESULTS: Average age of patients was 59.3 years. A single lesion was found in 17 cases while multiple lesions were found in 11 cases. Median survival period of the pateints who have undergone radiosurgery was 53 weeks, and survival rate at 6 months, 12 months, and 24 months was 84.6%, 53.9%, and 19.6% respectively. Overall tumor-control-rate was 92.9%. There was one case of radiation necrosis as a complication. Extracranial metastasis, controlled primary cancer and above 70 of Karnofsky performance scale score were statistically significant prognostic factors for survival. CONCLUSION: Radiosurgery is safe and effective in the treatment of metastatic brain tumor. And the control of primary malignant tumor, the presence of extracranial metastasis and above 70 of KPS have seen shown to influence the therapeutic response and prognosis.

Frameless Fractionated Stereotactic Radiotherapy Using Linear Accelerator in Large Brain Tumors

OBJECTIVE: The goals of this study are to introduce the method of fractionated stereotactic radiotherapy (FSRT), to make treatment plans and to evaluate the role of frameless FSRT in large brain tumors. METHODS: Between August 1997 and December 2000, FSRT was performed in 47 patients with brain lesion. Eighteen patients had brain tumor larger than 3cm. We used 'Point Reference System' of Northwest Medical Physics Center. Three gold markers were fixated at a given place instead of sticking the frame in the head. We used multiple-arc FSRT for round tumor and conformal FSRT for irregular tumor. RESULTS: There was no acute toxicity, except for transient headache and dizziness in two patients. Patients did not need to be hospitalized, and also did not suffer from being invasive with frames. In the radiological response of tumor volume, 2(11.1%) showed complete remission. 8(44.5%) were reduced. 4(22.2%) showed no change. 4(22.2%) were not followed up. In the clinical response of symptoms, 9(50%) were improved, 7(38.9%) were continued, and 2(11.1%) were aggravated. There were limitations that the clinical results of each patient were varied in diagnosis and underlying disease. CONCLUSION: We can apply FSRT for brain tumor larger than 3cm safely and effectively, regardless of shape irregularity and minimize the injury of normal brain tissue.

Result of Stereotactic LINAC Radiosurgery of AVM

There are several treatment modalities of cerebral arteriovenous malformation, among these, stereotactic radiosurgery is effective means of obliteration of AVM with minimal morbidity. Since July 1988 to May 1998, our institute have conducted 98 radiosurgery for arteriovenous malformations. During this period, there were 2 major changes in delivering radiation, the first one is introduction of compute r dose planning system at september 1996(CUMC normal mode), the next was CUMC Stereotactic mode using non-flat filter delivery system since september 1997. Authors report the results of the first generation LINAC(linear Accelerator) radiosurgery before introduction of computer dose planning system for radiosurgery. During the first generation period(July 1988 to september 1996), 70 patients have had stereotactic radiosurgery for vascular malformation. Among these, 49 patients could be followed at least for 2 year with angiography or MRA(magnetic resonance angiography). Hemorrhage was the most common presenting causes of undergoing radiosurgery, the parietal lobe was the most prevalent area undergoing radiosurgery for vascular malformations. With grouping of volumes, vascular malformations we re grouped as 1) volumes less than 1 ml(n= 14 ), 2) 1- 4ml (n=21), 3) 4-10ml (n=4 ), 4 ) 10-14ml(n=4 ), 5 ) volumes over 14ml (n=6). the results are as follows ' for group 1 ), total occlusion rate were 85.7 F, for group 2 ) total occlusion rate were 71.4 %, for group 3 ),4 ),5 ), total occlusion rate were 50%. As a gross result of 49 patients, total occlusion rate was 69.4%, partial occlusion was 22.4%, no response 14.3 %. 4 cases of 70 radiosurgery for vascular malformation rebleeded (5.7 %) and 2 of these patients died of bleeding (2.9%). There was no symptomatic radiation complication, but 6 patients showed increased signal intensity on T2 weighted image on follow up magnetic resonance imaging.