1. Ultra-Low Contrast Volumes Reduces Contrast-Induced Nephropathy in Patients With Chronic Kidney Disease Undergoing Neurointerventional Procedures
eP-150
Amar Swarnkar MBBS
Department of Radiology
Upstate Medical university Hospital
Syracuse, NY

2. Ultra-Low Contrast Volumes Reduces Contrast-Induced Nephropathy in Patients With Chronic Kidney Disease Undergoing Neurointerventional Procedures
eP-150
Disclosure: nothing to disclose

3. Introduction
Patients with impaired renal function are at risk of iodinated contrast-induced nephropathy (CIN).
Defined as 25% increase in serum creatinine from baseline or 0.5 mg/dL increase in absolute value, within hours).
In these populations, CIN has been shown to be dose dependent.
4.4% with 14 cc
increasing to 29.8% with 61 cc
G. C. Kane et al. Journal of the American College of Cardiology, vol. 51, no. 1, pp. 89–90, 2008.

4. Introduction
In patients with impaired renal function it is prudent to keep contrast dose as low as possible.
We propose techniques that would allow lower contrast doses for neurointerventional procedures.

5. Materials and Methods
We have selected 3 representative cases to exemplify our technique which can be applied to any endovascular procedure requiring contrast.
1: A 49-year-old female (GFR 17) underwent 4-vessel cerebral angiogram (contrast dose-11.5 cc, visipaque-320).
2: A 69-year-old female (GFR 21) underwent stent-assisted coiling of recurrent 8x6 mm recurrent middle cerebral artery aneurysm (14.5 cc Omnipaque-300).
3: A 60-year-old male (GFR 48) treated for symptomatic carotid stenosis by carotid stenting (10 cc Visipaque -320).
All patient also had standard CIN preventive measures such as hydration and GFR was checked pre and post procedurally.

6. Strategies to Decrease Contrast Load
Review all relevant previous studies.
Previous old CTA or MRA may show aortic arch anatomy and help in choosing appropriate catheter for the procedure.
May allow limited number of blood vessels injection requiring visualization, e.g. injecting 1 v/s 2 vertebral arteries.
May show tourtous blood vessel – help in planning endovascular treatment.
May show atherosclerotic disease – absence may allow distal catheter placement thus lower contrast injection.
MRA may be done if needed.

7. Strategies to Decrease Contrast Load
Review of all relevant previous studies.
MRA may be done if needed.
MRA showing severe left ICA stenosis
Uncomplicated arch and CCA - easier for carotid stenting

8. Avoid Routine 3D Rotational Angiography (3D DSA)
Requires larger dose of contrast but important for certain endovascular treatment of aneurysms.
Normally we use cc of contrast for ICA injection (typical 7 second x 3cc/sec).
3D DSA may be avoided by
Review previous 3D DSA for recurrent aneurysm if available.
Coiling projection is often the same as in previous 3D DSA.
Some aneurysms may not need 3D DSA. e.g. when aneurysm neck and parent arteries clearly visualized and are separate from sac .
Previous CTA may provide similar information.
MRA may be performed instead of 3D DSA prior to coiling of aneurysm to assess morphology, neck, parent artery, branches and coiling projection.
Previous DSA showing recurrent M1 bifurcation aneurysm
Size, coiling projection, parent artery and branches assessed to avoid getting new 3D DSA

9. Avoid Routine 3D Rotational Angiography (3D DSA)
MRA may be performed instead of 3D DSA prior to coiling of aneurysm to assess morphology, neck, parent artery, branches and coiling projection.
MRA done prior to coiling
Size, coiling projection, parent artery and branches assessed to avoid getting new 3D DSA

10. Guide Catheter Access Distal access: to limit contrast dose.
Guide catheter in M1 segment
Distal access: to limit contrast dose.
Place catheter distally e.g. ICA rather than CCA.
May use distal access catheter/intracranial support catheter close to the aneurysm, e.g. place catheter in M1 segment for M1 bifurcation aneurysm or in basilar artery for basilar tip aneurysm.
Stent assisted coiling of recurrent M1 bifurcation aneurysm
Injections were done through intracranial support catheter placed in M1 segment
Average contrast for each injection was approximately 1.3 cc

11. Contrast Injection
Contrast – we typically limit dilution of contrast to 10-20%.
Initially contrast is injected slowly till a tiny wisp of contrast is seen coming out of the catheter on fluoroscopy.
Next 1-2 cc of contrast is injected with sharp and short bolus through 5/6F catheters.
Smaller dose may be sufficient, e.g. 0.5 cc with intracranial support catheter with coaxial microcatheter.
Smaller volume syringe is better than large volume syringe, 6 cc medallion is preferred.
Visipaque is harder to inject through smaller catheter; more suitable for larger catheters.

12. Faster Targeted Imaging
Faster frame rate: typically 6 frames/sec to chase short bolus as opposed to 3-4 frames/sec traditionally used.
Adjust to lower frame rate for visipaque.
Targeted imaging: limiting DSA to arterial phase avoids unnecessary venous phase of DSA and reduces radiation dose.
May use larger FOV to limit number of injections e.g. cervical carotid and intracranial blood vessel rather then 2 separate injections.
Larger FOV used to limit number of injections e.g. both cervical carotid and intracranial blood vessel with single injection

13. Aspiration of Contrast
Main factor in limiting the dose.
Normally after each injection the residual contrast filling the dead space, is flushed in to the vessel, unnecessarily increasing the contrast dose.
Typical dead space:
0. 5 cc: 5F diagnostic catheter
1.5 cc: 5F diagnostic catheter + attached RHV + 3-way valve
2.2 cc: 6F guide catheter + attached RHV + 3-way valve
4 cc: 6F guide sheath + attached RHV + 3-way valve
Aspiration after injection reduces unnecessary contrast load e.g. total aspirated contrast after 10 injections from each of the above catheters will be 5, 15, 22 and 40 cc respectively.

14. Aspiration of Contrast - Technique
After injection contrast is aspirated from the catheter till blood reaches the 3-way valve.
Residual contrast is then flushed away by opening RHV.
Normal saline flush is then re-established.
For short interval injections- catheter may remain loaded with contrast which is then aspirated after the last injection.

15. Results
Patient 1: GFR increased from 17 to 20 (17.6% increased – likely hydration related) by day 3 without further impairment.
Patient 2: GFR decreased from 21 to 19 (9.5% decrease) on day 3 then returned to normal.
Patient 3: GFR increased from day 48 to 56 (16.6% increase related to hydration) by day 2 then returned to baseline.
Contrast opacification was good and no technique related complication occurred.

16. Good opacification of blood vessels
4 vessel diagnostic angiogram with average contrast dose of 2cc per injection

17. Successful Stent Assisted Coiling of Recurrent M1 bifurcation aneurysm
8 x6 mm recurrent lumen, treated with stent assisted coiling (Deployed 7 coils) Total injections 11, dose 14.5 cc Omnipaque-300, average contrast dose 1.3 cc per injection

18. Carotid stenting for recurrent stenosis presenting with acute hypoperfusion stroke
Nearly 80% carotid stenosis. Pre and post-stenting angiograms. Total injection 10, average dose 1 cc per injection, Visipaque 320

19. Conclusion
Ultra-low contrast volume neurointerventional angiogram technique could be an additional tool used to prevent contrast-induced nephropathy in susceptible populations.

20. References
G. C. Kane, B. J. Doyle, A. Lerman, G. W. Barsness, P. J. Best, and C. S. Rihal, “Ultra-low contrast volumes reduce rates of contrast-induced nephropathy in patients with chronic kidney disease undergoing coronary angiography,” Journal of the American College of Cardiology, vol. 51, no. 1, pp. 89–90, 2008