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To identify the predictors of symptomatic post-radiation T2 signal change in patients with arteriovenous malformations (AVM) treated with radiosurgery.
Materials and Methods:
The charts of 211 consecutive patients with arteriovenous malformations treated with either gamma knife radisurgery or linear accelerator radiosurgery between 2000-2009 were retrospectively reviewed. 168 patients had a minimum of 12 months of clinical and radiologic follow-up following the procedure and complete dosage data. Pretreatment characteristics and dosimetric variables were analyzed to identify predictors of adverse radiation effects.
141 patients had no clinical symptomatic complications. 21 patients had global or focal neurological deficits attributed to symptomatic edema. Variables associated with development of symptomatic edema included a non-hemorrhagic symptomatic presentation compared to presentation with hemorrhage, p=0.001; OR (95%CI) = 6.26 (1.99, 19.69); the presence of venous rerouting compared to the lack of venous rerouting, p=0.031; OR (95% CI) = 3.25 (1.20, 8.80); radiosurgery with GKS compared to linear accelerator radiosurgery p = 0.012; OR (95% CI) = 4.58 (1.28, 16.32); and the presence of more than one draining vein compared to a single draining vein p = 0.032; OR (95% CI) = 2.82 (1.06, 7.50).
We postulated that the higher maximal doses used with gamma knife radiosurgery may be responsible for the greater number of adverse radiation effects with this modality compared to linear accelerator radiosurgery. We found that AVMs with greater venous complexity and therefore instability resulted in more adverse treatment outcomes, suggesting that AVM angioarchitecture should be considered when making treatment decisions.
To evaluate the impact of an emergency department (ED) automatic preauthorization policy on after-hours utilization of neuroradiology computed tomography (CT).
All CT studies of the head with contrast facial bones, orbits, spine, and neck requested through the ED and performed between January 1, 2004, and December 31, 2010, were reviewed. The preauthorization policy was instituted on February 25, 2008. A control group of noncontrast CT head studies was used for comparison. Pre- and postpolicy implementation utilization rates were compared between the control group of noncontrast CT head studies and the study group neuroradiology CT studies.
During the study period, 408,501 ED patient visits occurred and 20,703 neuroradiology CT studies were carried out. The pre- and postimplementation groups of noncontrast CT head scans totalled 7,474 and 6,094, respectively, whereas the pre- and postimplementation groups of all other neuroradiology CT studies totalled 3,833 and 3,302, respectively. The CT utilization between the two groups did not differ significantly: the noncontrast head group pre- and postpolicy implementation increased by 0.31 to 3.41%, whereas the utilization of all other neuroradiology CT studies increased by 0.22 to 1.84% (p value = 0.061 for a difference between groups).
Implementation of an automatic preauthorization policy for after-hours neuroradiology CT studies did not result in a statistically significant increase in CT utilization. This suggests that concerns regarding the negative effects of such policiesmay be unfounded, and further research in this area is warranted.
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