Evaluate whether a treatment plan based on CT angiography can accurately and precisely identify the target nidus as compared to standard cerebral arteriography fused to MRI.

Stereotactic Radiosurgery is a preferable treatment option for patients with Arteriovenous malformation (AVM) that are not surgically accessible or in patients with comorbidities that make them poor surgical candidates At University of Texas Southwestern Medical Center (UTSW), investigator routinely perform interventional cerebral arteriography on the day of the SRS procedure for improved target delineation. Even though the addition of angiography is time consuming and requires multi-modality team care, this approach has allowed UTSW to treat the smallest possible target, yet achieve excellent obliteration rates of AVM with very low toxicity from the procedure. At UTSW the investigator also use CT angiogram at the treatment team's discretion to further enhance the accurate delineation of the final treatment target volume. However, it had not been routinely done due to uncertain benefit in treatment planning and a concern for renal burden from additional intravenous (IV) contrast usage.

This prospective enrollment and conduct open-label, retrospective analysis study is to evaluate whether a target volume based on CT angiography can serve as a reliable substitute for a target based on interventional cerebral arteriography. Patients on this protocol will still get treated based on target generated by interventional cerebral arteriography but also receive CT angiography. If the target volume based on CT angiography are adequate compared to their invasive counterpart, future investigators may selectively omit performing interventional cerebral arteriography in the treatment planning for SRS of AVM. Use of CT angiography may lead to reduction in the risk from the procedure and cost, improve the efficiency of the treatment process ideally without compromising the success of the procedure, with greater patient comfort and satisfaction.

Inclusion Criteria:

1. Documented AVM with draining vein(s).

2. Adequate renal function (serum Creatinine < 1.5 mg/dl within 30 days of SRS) to undergo contrast CT and interventional cerebral arteriography on the same day, as determined by treating physicians.

3. AVM must be physically separated from the optic pathway, brainstem or spinal cord.

4. The maximum diameter of AVM nidus must be less than 3.5 cm and/or less than 12 cc.

5. Age ≥ 10 years.

6. All men, as well as women of child-bearing potential must agree to use adequate contraception (hormonal or barrier method of birth control; abstinence) prior to study entry and for the duration of study participation. Should a woman become pregnant or suspect she is pregnant while participating in this study, she should inform her treating physician immediately

   6.1 A female of child-bearing potential is any woman (regardless of sexual orientation, having undergone a tubal ligation, or remaining celibate by choice) who meets the following criteria:

   • Has not undergone a hysterectomy or bilateral oophorectomy; or
   • Has not been naturally postmenopausal for at least 12 consecutive months (i.e., has had menses at any time in the preceding 12 consecutive months).

7. Ability to understand and the willingness to sign a written informed consent.

Exclusion Criteria:

1. Patients without a documented AVM.
2. Patients with a contraindication to CT or MRI such as contrast allergy, kidney failure or implanted metal devices or foreign bodies or severe claustrophobia.
3. Use of Nephrotoxic drugs, such as gentamycin, high-dose nonsteroidal anti-inflammatory drugs, or certain chemotherapeutic drugs within 10 days of the procedure.
4. Psychiatric illness/social situations that would limit compliance with study requirements.
5. Patients must not be pregnant at the time of SRS treatment.

All patients enrolled to study

1 month

Neurosurgeon who contoured AVM nidus using interventional cerebral arteriography.