Aortic arch injection with C-arm cone beam CT for radiosurgery treatment planning of cerebral arteriovenous malformations: technical note

Adjunctive Efficacy of Intra-Arterial Conebeam CT Angiography Relative to DSA in the Diagnosis and Surgical Planning of Micro-Arteriovenous Malformations

BACKGROUND AND PURPOSE

Micro-arteriovenous malformations are an underrecognized etiology of intracranial hemorrhage. Our study aimed to assess the adjunctive efficacy of intra-arterial conebeam CTA relative to DSA in the diagnosis and surgical planning of intracranial micro-AVMs.

MATERIALS AND METHODS

We performed a retrospective study of all micro-AVMs (≤1-cm nidus) at our institution. Blinded neuroradiologists qualitatively graded DSA and intra-arterial conebeam CTA images for the detection of specific micro-AVM anatomic parameters (arterial feeder, micronidus, and venous drainer) and defined an overall diagnostic value. Statistical and absolute differences in the overall diagnostic values defined the relative intra-arterial conebeam CTA diagnostic values, respectively. Blinded neurosurgeons reported their treatment approach after DSA and graded the adjunctive value of intra-arterial conebeam CTA to improve or modify treatment. Intra-arterial conebeam CTA efficacy was defined as interobserver agreement in the relative intra-arterial conebeam CTA diagnostic and/or treatment-planning value scores.

RESULTS

Ten patients with micro-AVMs presented with neurologic deficits and/or intracranial hemorrhages. Both neuroradiologists assigned a higher overall intra-arterial conebeam CTA diagnostic value (P < .05), secondary to improved evaluation of both arterial feeders and the micronidus, with good interobserver agreement (τ = 0.66, P = .018) in the relative intra-arterial conebeam CTA diagnostic value. Both neurosurgeons reported that integrating the intra-arterial conebeam CTA data into their treatment plan would allow more confident localization for surgical/radiation treatment (8/10; altering the treatment plan in 1 patient), with good interobserver agreement in the relative intra-arterial conebeam CTA treatment planning value (τ = 0.73, P = .025).

CONCLUSIONS

Adjunctive intra-arterial conebeam CTA techniques are more effective in the diagnostic identification and anatomic delineation of micro-AVMs, relative to DSA alone, with the potential to improve microsurgical or radiosurgery treatment planning.

Interobserver Agreement on Arteriovenous Malformation Diffuseness Using Digital Subtraction Angiography

BACKGROUND

Arteriovenous malformation (AVM) diffuseness has been shown to be prognostic of treatment outcomes. We assessed interobserver agreement of AVM diffuseness among physicians of different specialty and training backgrounds using digital subtraction angiography (DSA).

METHODS

All research protocols were approved by the institutional review board for this retrospective chart review. In a single-blinded setting, 2 attending neurosurgeons, 1 attending interventional neuroradiologist, and 1 senior neurosurgical resident rated 80 DSA views of 36 AVMs as either compact or diffuse. Individual interobserver agreement and subgroup agreement were analyzed using κ agreement and intraclass correlation coefficient.

RESULTS

Disagreement regarding AVM diffuseness occurred in 43.8% of all DSA views (n = 80). Interobserver κ agreement on AVM diffuseness using DSA views among 4 physicians ranged from fair (κ = 0.40 [95% confidence interval (CI) = 0.22-0.58]) to substantial (κ = 0.65 [95% CI = 0.48-0.81]), whereas total intraclass correlation coefficient was 0.81 (95% CI = 0.73-0.87). For the 36 AVMs, κ agreement ranged from fair (κ = 0.36 [95% CI = 0.13-0.60]) to moderate (κ = 0.57 [95% CI = 0.35-0.79]), whereas intraclass correlation coefficient among all 4 physicians was 0.68 (95% CI = 0.47-0.82). Moderate agreement on AVM diffuseness (n = 80) was found between attending and resident assessments (κ = 0.57 [95% CI = 0.39-0.75]) and between neurosurgeon and interventional neuroradiologist assessments (κ = 0.55 [95% CI = 0.37-0.73]).

CONCLUSIONS

Agreement of individual physicians on AVM diffuseness varies from fair to substantial. Objective and three-dimensional measures of AVM diffuseness should be developed for consistent clinical application.

Imaging the spontaneous obliteration of a cerebral arteriovenous malformation using c-arm cone beam computed tomography: A case report

Background:

Spontaneous occlusion of a cerebral arteriovenous malformation (AVM) without treatment is a rare occurrence.

Case Description:

We report the case of a 56-year-old male who presented with aphasia and right hemiparesis secondary to intracerebral and intraventricular hemorrhage. Diagnostic digital subtraction angiography (DSA) and c-arm cone beam computed tomography (CBCT) demonstrated a 5 mm Spetzler-Martin Grade III left thalamic AVM drained by the internal cerebral vein. Subsequent DSA and CBCT studies confirmed the spontaneous obliteration of the AVM.

Conclusions:

In this case, CBCT provided high resolution imaging of the AVM. Future clinical use of CBCT as an adjunct to DSA may enhance the diagnostic and therapeutic imaging of vascular lesions.

Contrast-enhanced angiographic cone-beam computed tomography without pre-diluted contrast medium

INTRODUCTION

Contrast-enhanced cone-beam computed tomography (CBCT) has been introduced and accepted as a useful technique to evaluate delicate vascular anatomy and neurovascular stents. Current protocol for CBCT requires quantitative dilution of contrast medium to obtain adequate quality images. Here, we introduce simple methods to obtain contrast-enhanced CBCT without quantitative contrast dilution.

METHODS

A simple experiment was performed to estimate the change in flow rate in the internal carotid artery during the procedure. Transcranial doppler (TCD) was used to evaluate the velocity change before and after catheterization and fluid infusion. In addition, 0.3 cm(3)/s (n = 3) and 0.2 cm(3)/s (n = 7) contrast infusions were injected and followed by saline flushes using a 300 mmHg pressure bag to evaluate neurovascular stent and host arteries.

RESULTS

Flow velocities changed -15 ± 6.8 % and +17 ± 5.5 % from baseline during catheterization and guiding catheter flushing with a 300 mmHg pressure bag, respectively. Evaluation of the stents and vascular structure was feasible using this technique in all patients. Quality assessment showed that the 0.2 cm(3)/s contrast infusion protocol was better for evaluating the stent and host artery.

CONCLUSION

Contrast-enhanced CBCT can be performed without quantitative contrast dilution. Adequate contrast dilution can be achieved with a small saline flush and normal blood flow.

Use of cone-beam computed tomography angiography in planning for gamma knife radiosurgery for arteriovenous malformations: a case series and early report

BACKGROUND

The effectiveness of Gamma Knife radiosurgery (GKR) for cerebral arteriovenous malformations (AVMs) is predicated on inclusion of the entire nidus while excluding normal tissue. As such, GKR may be limited by the resolution and accuracy of the imaging modality used in targeting.

OBJECTIVE

We present the first case series to demonstrate the feasibility of using ultrahigh-resolution C-arm cone-beam computed tomography angiography (CBCT-A) in AVM targeting.

METHODS

From June 2009 to June 2013, CBCT-A was used for targeting of all patients with AVMs treated with GKR at our institution. Patients underwent Leksell stereotactic head frame placement followed by catheter-based biplane 2-dimensional digital subtraction angiography, 3-dimensional rotational angiography, as well as CBCT-A. The CBCT-A dataset was used for stereotactic planning for GKR. Patients were followed at 1, 3, 6, and 12 months and then annually thereafter.

RESULTS

CBCT-A-based targeting was used in 22 consecutive patients. CBCT-A provided detailed spatial resolution and sensitivity of nidal angioarchitecture enabling treatment. The average radiation dose to the margin of the AVM nidus corresponding to the 50% isodose line was 15.6 Gy. No patient had treatment-associated hemorrhage. At early follow-up (mean, 16 months), 84% of patients had a decreasing or obliterated AVM nidus.

CONCLUSION

CBCT-A-guided radiosurgery is feasible and useful because it provides sufficient detailed resolution and sensitivity for imaging brain AVMs.

Target delineation for radiosurgery of a small brain arteriovenous malformation using high-resolution contrast-enhanced cone beam CT

Three years following endovascular embolization of a 3 mm ruptured arteriovenous malformation (AVM) of the left superior colliculus in a 42-year-old man, digital subtraction angiography showed continuous regrowth of the lesion. Thin-slice MRI acquired for treatment planning did not show the AVM nidus. The patient was brought back to the angiography suite for high-resolution contrast-enhanced cone beam CT (VasoCT) acquired using an angiographic c-arm system. The lesion and nidus were visualized with VasoCT. MRI, CT and VasoCT data were transferred to radiation planning software and mutually co-registered. The nidus was annotated for radiation on VasoCT data by an experienced neurointerventional radiologist and a dose/treatment plan was completed. Due to image registration, the treatment area could be directly adopted into the MRI and CT data. The AVM was completely obliterated 10 months following completion of the radiosurgery treatment.

Comparison of aortic arch and intravenous contrast injection techniques for C-arm cone beam CT: implications for cerebral perfusion imaging in the angiography suite

RATIONALE AND OBJECTIVES

The ability to perform cerebral perfusion imaging (CPI) in the angiography suite has provided a new tool for diagnosis and treatment of neurovascular patients but requires comparable contrast perfusion to each cerebral hemisphere. In the angiography suite, contrast injection may be performed via an intra-arterial or intravenous (IV) route. The purpose of this study was to investigate whether a difference exists between contrast injection in the aortic arch (AA) and a peripheral vein (IV), particularly in the setting of stroke.

MATERIALS AND METHODS

Using three canines, both AA and IV injection protocols compatible with CPI were performed prospectively at three time points after creation of a stroke. The common carotid arteries in the resulting image data sets were segmented and the means and distributions of corresponding pixel intensities analyzed with Student's t-test. Using similar techniques, the internal carotid arteries of three patients (one female, two males, ages 69, 29, and 20) undergoing AA contrast injection with cone beam computed tomography (CBCT) cerebral imaging were analyzed and compared retrospectively with those of three random patients (one female, two males, ages 19, 57, and 35) undergoing standard head CT scans using IV contrast administration. All acquisitions followed institutionally approved protocols and informed consent.

RESULTS

No statistical significance (P < .05) was found when mean values for the right and left carotid artery pixel intensities were compared in the canine model or the clinical studies in which patients underwent imaging after AA or IV contrast administration.

CONCLUSIONS

No statistically significant difference exists between right and left carotid artery filling density using either AA or IV contrast injection methods, making both suitable for CPI in the angiography suite.