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Combined effects of embolisation and hypofractionated conformal stereotactic radiotherapy in arteriovenous malformations of the brain
Umeå University, Faculty of Medicine, Department of Pharmacology and Clinical Neuroscience, Neurosurgery.
Umeå University, Faculty of Medicine, Department of Radiation Sciences, Oncology.
Umeå University, Faculty of Medicine, Department of Radiation Sciences.
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2005 (English)In: INTERVENTIONAL NEURORADIOLOGY, ISSN 1123-9344, Vol. 11, no 3, 223-229 p.Article in journal (Refereed) Published
Abstract [en]

There are three major treatment options for cerebral AVMs; surgery, embolization and radiosurgery. Embolization may be effective to reduce the size and density but completely obliterates AVMs only in a minority of cases. Radiosurgery may be an alternative to resection, especially in smaller AVMs. Large AVMs have been considered difficult to treat safely and effectively with single fraction radiosurgery. Hypofractionated conformal stereotactic radiotherapy (HCSRT)alone or in combination with embolization may be an alternative treatment. Embolization may reduce the volume and density of AVMs, followed by HCSRT, allowing a safe delivery of a higher total dose of radiation than possible with a single fraction. Sixteen patients with AVMs were treated with embolization and HCSRT. Embolization was performed in 1-6(median 2) sessions. HCSRT was delivered in 5fractions with 6-7 Gy each to the total dose of30–35 Gy. Cerebral angiographies before and after embolization were digitally compared for calculation of volume reduction and luminescence as a measure of AVM density. The mean AVM volume in 15 patients was reduced from11.9 ± 2.1 (1-29, median 10.0) ml to 6.5 ± 2.0(0.5–28, median 3) ml by embolization. The luminescence for all AVMs was significantly higher after than before embolization, indicating that all AVMs were less dense after embolization. Thirteen out of 16 patients (13/16, 81%) treatedwith embolization and HCSRT have so farshown obliteration of their AVMs 2-9 (median4) years after HCSRT. Three patients experienced neurological sequele after embolization, and three patients developed radionecrosis after HCSRT. Using a new method to compare cerebral angiographies in AVMs we report reduction in density and volume after embolization. The obliteration rate of a combined treatment with embolization and HCSRT seems comparable with single fraction radiosurgery although the AVMs in our series are larger than reported in most series treated with single fraction radiosurgery.

Place, publisher, year, edition, pages
Milan, Udine, Italy: Edizioni del Centauro , 2005. Vol. 11, no 3, 223-229 p.
Keyword [en]
AVM, embolization, stereotactic, radiotherapy
URN: urn:nbn:se:umu:diva-5305OAI: diva2:144783
Available from: 2006-09-18 Created: 2006-09-18 Last updated: 2011-07-05Bibliographically approved
In thesis
1. Hypofractionated conformal stereotactic radiotherapy in the treatment of AVMs and cerebral metastases
Open this publication in new window or tab >>Hypofractionated conformal stereotactic radiotherapy in the treatment of AVMs and cerebral metastases
2006 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Hypofractionated conformal stereotactic radiotherapy (HCSRT) has been used for the treatment of AVMs at the Umeå University Hospital since 1986. From this year and onwards an increasing number of patients with single or oligo brain metastases have also been treated using this technique.

In paper I we have retrospectively evaluated our treatment results of AVMs in terms of obliteration and complications. The rates of obliteration and complications seem to be comparable with SRS even if the AVM volumes in our series were larger than in most series with SRS. In paper II we have retrospectively evaluated the results in terms of local control, survival and complications in two groups of patients with single or oligo brain metastases. One group was treated with HCSRT alone and the other group was treated with whole brain radiotherapy in combination with a stereotactic boost. Controversy still exists concerning the benefit of additional use of WBRT in combination with stereotactic irradiation. The survival times were equal in the two groups and no significant difference in local control was observed. The omission of WBRT seems to carry a higher risk for development new brain metastases distant from the irradiated area. In paper III we report the treatment results in a subgroup of AVMs treated with a combination of embolisation and HCSRT. We also focus on the reduction of vascular density within the nidus of an AVM and propose a method to digitally compare images and more objectively assess a reduction in vascular density following embolisation. Obliteration rates seem comparable with other series using a combination of SRS and embolisation even if our rate of complications was higher than what is usually reported. Using luminescence as measure of vascular density all AVMs seemed to be less dense after embolisation.

Treatment accuracy in terms of reproducibility of the isocenter in consecutive treatment sessions is crucial in fractionated radiotherapy. In paper IV we have radiologically evaluated the reproducibility of the isocenter in successive treatment sessions using the non invasive relocatable Fixster frame. There was a high degree of reproducibility and only small errors that most likely is of no clinical importance.

A reliable dose plan is equally important as a tool to predict the dose delivered inside and outside the target volume. In paper V we have evaluated the reliability of treatment plans in HCSRT for targets of different geometry and size. A liquid ion chamber and gel dosimeter was used for assessment of dose distribution and absorbed dose. The doseplanning system proved to be accurate in predicting the absorbed dose and dose distribution for the different targets.

91 p.
Umeå University medical dissertations, ISSN 0346-6612 ; 1042
arteriovenous malformations, brain metastases, hypofractionation, stereotactic radiotherapy, LINAC, embolisation
Research subject
Clinical Neurophysiology
urn:nbn:se:umu:diva-864 (URN)91-7264-135-5 (ISBN)
Public defence
2006-10-13, Sal B, plan 9, 1D, Tandläkarhögskolan, Umeå, 09:00 (English)
Available from: 2006-09-18 Created: 2006-09-18 Last updated: 2009-10-09Bibliographically approved

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