Introduction: DSA has evolved from a two-dimensional, low-resolution static imaging-system to a three-dimensional real-time system with high spatial-resolution. Recently, the use of parametric-color-coded-DSA has come to the fore, especially in evaluation of aneurysms and AVM embolisation. There is good evidence to demonstrate that time to maximum-opacification(Tmax) and time-intensity-curves(TIC) reliably represent blood-flow characteristics inside intracranial-vessels. Also, varied scores(TIMI,TICI,AOL) have been used in the evaluation of the radiological outcomes but they lack uniformity and reproducibility .We presents ,University at Buffalo experience with parametric imaging. To the best of our knowledge this is the first-instance of use of parametric imaging in the treatment of steno-occlusive intracranial arterial disease.

Methods: Two-dimensional DSA images were acquired in 6 patients (3 cases each of intracranial stenosis(Figure-1) and acute-large vessel(Figure-2) occlusion. Approximately 10ml of contrast media, iohexol-300/ iodixanol-320 was injected during the DSA-acquisition. The images were acquired using transfemoral approach while maintaining similar injection conditions. TIC analysis was performed for each image pixels using prototype software (Toshiba Medical Systems, Tochigi, Japan). Once the DSA data was loaded on the prototype software, TIC analysis is automatically performed and Time To Arrival (TTA), Time To Peak (TTP), Mean Transit Time(MTT) and Area Under the Curve(AUC) are calculated for each TIC(Figure 1 and 2)

Results: Ten vascular territories and 39 regions of interests (ROI’s) were evaluated in 6 patients. Analysis of time density curve showed that, subsequent to intervention there was a decrease in parameters such as TTP and TTA. However, MTP did not show consistency with the radiological outcome. Area under curve increased following intervention in all six cases.

Conclusions: Our experience shows that color coded parametric imaging can be used successfully to assess the radiological outcomes of interventions for acute arterial occlusion and intracranial angioplasty. It is a step to make a standard angiogram into a "functional angiogram".

Patient Care: Our research helps in the decision making of endpoint during the intervention , real time. That added information affects the clinical outcome.

Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the importance of parametric imaging in the setting of Neuro-endovascular intervention for intracranial stenosis and large vessel occlusion. 2) Discuss, in small groups about the implications of absolute values from Time density curve and clinical outcomes 3) Identify treatment end-point during endovascular interevntion.

References: 1. Al-Ali F, Jefferson A, Barrow T, Cree T, Louis S, Luke K, et al.: The capillary index score: rethinking the acute ischemic stroke treatment algorithm. Results from the Borgess Medical Center Acute Ischemic Stroke Registry. J Neurointerventional Surg 5:139–143, 2013 2. Al-Ali F, Tomsick TA, Connors JJ, Gebel JM, Elias JJ, Markarian GZ, et al.: Capillary Index Score in the Interventional Management of Stroke trials I and II. Stroke J Cereb Circ 45:1999–2003, 2014 3. Benndorf G: Color-coded digital subtraction angiography: the end of a monochromatic era? AJNR Am J Neuroradiol 31:925–927, 2010 4. Blomley MJ, Dawson P: Bolus dynamics: theoretical and experimental aspects. Br J Radiol 70:351–359, 1997 5. Bürsch JH, Heintzen PH: Parametric imaging. Radiol Clin North Am 23:321–333, 1985 6. Campbell BCV, Mitchell PJ, Kleinig TJ, Dewey HM, Churilov L, Yassi N, et al.: Endovascular Therapy for Ischemic Stroke with Perfusion-Imaging Selection. N Engl J Med 0:null, 2015 7. Cover KS, Lagerwaard FJ, van den Berg R, Buis DR, Slotman BJ: Color intensity projection of digitally subtracted angiography for the visualization of brain arteriovenous malformations. Neurosurgery 60:511–515, 2007 8. Fugate JE, Klunder AM, Kallmes DF: What is meant by “TICI”? AJNR Am J Neuroradiol 34:1792–1797, 2013 9. Furlan A, Higashida R, Wechsler L, et al: Intra-arterial prourokinase for acute ischemic stroke: The proact ii study: a randomized controlled trial. JAMA 282:2003–2011, 1999 10. Gölitz P, Struffert T, Rösch J, Ganslandt O, Knossalla F, Doerfler A: Cerebral aneurysm treatment using flow-diverting stents: in-vivo visualization of flow alterations by parametric colour coding to predict aneurysmal occlusion: preliminary results. Eur Radiol 25:428–435, 2015 11. Hunter GJS, Hunter JV, Brown NJG: Parametric imaging using digital subtraction angiography. Br J Radiol 59:7–11, 1986 12. IMS Study Investigators: Combined intravenous and intra-arterial recanalization for acute ischemic stroke: the Interventional Management of Stroke Study. Stroke J Cereb Circ 35:904–911, 2004 13. Ionita CN, Garcia VL, Bednarek DR, Snyder KV, Siddiqui AH, Levy EI, et al.: Effect of injection technique on temporal parametric imaging derived from digital subtraction angiography in patient specific phantoms, 2014, Vol. 9038, p 90380L–90380L–12 Available: http://dx.doi.org/10.1117/12.2041347. Accessed 3 December 2014 14. Khatri P, Neff J, Broderick JP, Khoury JC, Carrozzella J, Tomsick T: Revascularization End Points in Stroke Interventional Trials Recanalization Versus Reperfusion in IMS-I. Stroke 36:2400–2403, 2005 15. Levitt MR, Morton RP, Haynor DR, Cohen W, Ghodke BV, Hallam DK, et al.: Angiographic perfusion imaging: real-time assessment of endovascular treatment for cerebral vasospasm. J Neuroimaging Off J Am Soc Neuroimaging 24:387–392, 2014 16. Lin CJ, Hung SC, Guo WY, Chang FC, Luo CB, Beilner J, et al.: Monitoring peri-therapeutic cerebral circulation time: a feasibility study using color-coded quantitative DSA in patients with steno-occlusive arterial disease. AJNR Am J Neuroradiol 33:1685–1690, 2012 17. Lin C-J, Luo C-B, Hung S-C, Guo W-Y, Chang F-C, Beilner J, et al.: Application of color-coded digital subtraction angiography in treatment of indirect carotid-cavernous fistulas: Initial experience. J Chin Med Assoc 76:218–224, 2013 18. Marks MP, Lansberg MG, Mlynash M, Kemp S, McTaggart R, Zaharchuk G, et al.: Correlation of AOL recanalization, TIMI reperfusion and TICI reperfusion with infarct growth and clinical outcome. J Neurointerventional Surg 6:724–728, 2014 19. Mehndiratta A, Knopp MV, Zechmann CM, Owsijewitsch M, von Tengg-Kobligk H, Zamecnik P, et al.: Comparison of diagnostic quality and accuracy in color-coded versus gray-scale DCE-MR imaging display. Int J Comput Assist Radiol Surg 4:457–462, 2009 20. Nagata K, Asano T: Functional image of dynamic computed tomography for the evaluation of cerebral hemodynamics. Stroke 21:882–889, 1990 21. Strother CM, Bender F, Deuerling-Zheng Y, Royalty K, Pulfer KA, Baumgart J, et al.: Parametric color coding of digital subtraction angiography. Am J Neuroradiol 31:919–924, 2010 22. Struffert T, Deuerling-Zheng Y, Engelhorn T, Kloska S, Gölitz P, Bozzato A, et al.: Monitoring of balloon test occlusion of the internal carotid artery by parametric color coding and perfusion imaging within the angio suite: first results. Clin Neuroradiol 23:285–292, 2013 23. Tomsick T: TIMI, TIBI, TICI: I Came, I Saw, I Got Confused. Am J Neuroradiol 28:382–384, 2007