Early Irradiation Effects Observed on Magnetic Resonance Imaging and Angiography, and Positron Emission Tomography for Arteriovenous Malformations Treated by Gamma Knife Radiosurgery

Abstract

In 14 patients (7 males and 7 females, age 16–49, mean 29 years), medium-to-large arteriovenous malformations (AVMs; nidus volume 3.5–17.5 cm³, mean 9.4 cm³) were treated by Gamma Knife radiosurgery. Stereotactic MR and conventional angiography were included for targeting to improve targeting accuracy and tissue content in the irradiation volume. Maximum irradiation doses to the nidi were 36–40 Gy (mean 38.9 Gy) and minimum target doses were 18–24 Gy (mean 20 Gy). MR images and MR angiography demonstrated decreasing caliber of feeding vessels and AVM nidus volumes from an early stage, 3 months after radiosurgery, which indicated improvement in cerebral hemodynamics. The improvement correlated well with that observed on PET using [¹⁸F]fluorodeoxyglucose (FDG) and with the patients'' clinical condition. MR creates an opportunity to monitor treatment effects in a completely noninvasive manner, while conventional angiography

The Impact of Arteriovenous Malformation Radiosurgery on the Brain: From Morphology and Perfusion to Neurocognition

“…The clinical results of AVM radiosurgery direct our interest to exploring the possible pathogenesis involved. In one of our previous studies, improvement of AVM-relevant hemodynamics was observed since the early stage after radiosurgery [5] . In another prospective study of AVM patients with positron emission tomography using [ 18 F]fluorodeoxyglucose as the tracer (FDG-PET), we found recovered cerebral metabolism after AVM radiosurgery ( fig.…”

“…On a regular interval base (mostly 6 months), studies with the same imaging protocol and neurocognition tests were repeated after radiosurgery. The imaging protocols were the same as those we routinely used [1,5] . There were 29, 22, 23, 16, 11, 5 and 1 patients having posttherapeutic follow-ups at about 6, 12, 18, 24, 30, 36 and 40 months after radiosurgery, respectively.…”

Territorial and Microvascular Perfusion Impairment in Brain Arteriovenous Malformations

“…Perinidal capillary perfusion has been estimated by researchers by using a variety of techniques, including positronemission tomography (PET), [6][7][8][9][10] single-photon emission CT (SPECT), [10][11][12] and MR imaging. 13,14 The problems encountered by using PET and SPECT to evaluate perinidal brain are due to their comparatively low spatial resolution, which requires that structures in the direct vicinity of the nidus be subject to the effects of partial voluming.…”

Invited. Application of MR in stereotactic radiosurgery

“…Use of nonionization radiation in MR makes the application of MR for longitudinal studies without restrains. The feasibility provides us the means to understand more about the evolving radiosurgical effects (18)(19)(20)(21). For tumor patients, sequential MR studies demonstrate regression of tumor volumes in most cases.…”

“…Good quality MR may be as good as x-ray angiography (an invasive imaging) in demonstrating AVM and its regression after radiosurgery (19). For venfylng treatment results, ie, total obliteration, MR is as reliable as x-ray angiography.…”