Non-Contrast CT in Place of MRI Mismatch in the Imaging Triage of Acute Ischemic Stroke Patients

Main Article Content

Emmad Qazi Fahad S Al-Ajlan Akash Mahajan Sung Il Sohn Sachin Mishra Hyuk Won Chang Mohamed Najm Christopher d’Esterre Andrew M Demchuk Mayank Goyal Ting Yim Lee Michael D Hill Bijoy K Menon


Purpose: We test if assessment of attenuation on NCCT identifies similar patients with acute ischemic stroke as the MRI DWI-FLAIR mismatch paradigm.

Methods: Data are from the Keimyung Stroke Registry. Patients with anterior circulation occlusion on baseline CT-angiography, known symptom onset time and MRI within 60 minutes of baseline CT were included. All patients received revascularization therapy. Baseline MRI DWI-FLAIR mismatch, hypoattenuation on baseline NCCT and parenchymal hemorrhage (PH) on follow-up imaging were assessed by consensus. Ratio of ipsilateral/contralateral NCCT Hounsfield Unit (HU) (rCT) within baseline DWI lesion was calculated. Statistical methods were used to assess if CT hypoattenuation was a reliable biomarker of time from stroke symptom onset and if it compared well with DWI-FLAIR mismatch in  predicting PH at 24 hours.

Results: Of 127 patients included [median age 68 (IQR-15), 53.5% male, median onset to MR time 158 (94) minutes], DWI-FLAIR mismatch was seen in 85/127 (67%). NCCT hypo-attenuation was seen in 111/127 (87%). A statistically significant negative correlation was noted between rCT and stroke symptom onset to MRI time (Spearman’s r = -0.33, p<0.001). A rCT > 0.87 best predicted the presence of DWI-FLAIR mismatch [c statistic = 0.84 (95% CI 0.77-0.91), sensitivity 73.75% (95%CI 62.71%-82.95%); specificity 76.92% (95%CI 60.67-88.87%)]. Models with CT hypoattenuation were similar to a model with DWI-FLAIR mismatch in ability to discriminate PH (p>0.5).

Conclusion: Degree of hypoattenuation on NCCT can be used in place of DWI-FLAIR mismatch to identify patients with wake up strokes or unknown time of onset.

Article Details

How to Cite
QAZI, Emmad et al. Non-Contrast CT in Place of MRI Mismatch in the Imaging Triage of Acute Ischemic Stroke Patients. Medical Research Archives, [S.l.], v. 4, n. 6, oct. 2016. ISSN 2375-1924. Available at: <>. Date accessed: 25 june 2024.
Non contrast CT hypoattenuation, MRI DWI-FLAIR mismatch, acute ischemic stroke
Research Articles


1. Bal S, Bhatia R, Shobha N, et al. Stroke- on- Awakening: Safety of CT-CTA Based Selection for Reperfusion Therapy. Can J Neurol Sci. 2014;41(2):182-6.

2. Hill MD, Kenney C, Dzialowski I, et al. Tissue Window in Stroke Thrombolysis study (TWIST): a safety study. Can J Neurol Sci. 2013;40(1):17-20.

3. Hill MD, Frayne R. Stroke on awakening and the tissue window for thrombolysis. Lancet Neurol. 2011;10(11):951-2.

4. Kelly-Hayes M, Wolf PA, Kase CS, Brand FN, McGuirk JM, D'Agostino RB. Temporal patterns of stroke onset. The Framingham Study. Stroke. 1995;26(8):1343-7.

5. Guidelines for management of ischaemic stroke and transient ischaemic attack 2008. Cerebrovasc Dis. 2008;25(5):457-507.

6. Jauch EC, Saver JL, Adams HP, Jr., et al. Guidelines for the early management of patients with acute ischemic stroke: a guideline for healthcare professionals from the American Heart Association/American Stroke Association. Stroke. 2013;44(3):870-947.

7. Thomalla G, Cheng B, Ebinger M, et al. DWI-FLAIR mismatch for the identification of patients with acute ischaemic stroke within 4.5 h of symptom onset (PRE-FLAIR): a multicentre observational study. Lancet Neurol. 2011;10(11):978-86.

8. Aoki J, Kimura K, Iguchi Y, Shibazaki K, Sakai K, Iwanaga T. FLAIR can estimate the onset time in acute ischemic stroke patients. J Neurol Sci. 2010;293(1-2):39-44.

9. Petkova M, Rodrigo S, Lamy C, et al. MR imaging helps predict time from symptom onset in patients with acute stroke: implications for patients with unknown onset time. Radiology. 2010;257(3):782-92.

10. Thomalla G, Rossbach P, Rosenkranz M, et al. Negative fluid-attenuated inversion recovery imaging identifies acute ischemic stroke at 3 hours or less. Annals of neurology. 2009;65(6):724-32.

11. Breuer L, Schellinger PD, Huttner HB, et al. Feasibility and safety of magnetic resonance imaging-based thrombolysis in patients with stroke on awakening: initial single-centre experience. Int J Stroke. 2010;5(2):68-73.

12. Kang DW, Sohn SI, Hong KS, et al. Reperfusion therapy in unclear-onset stroke based on MRI evaluation (RESTORE): a prospective multicenter study. Stroke. 2012;43(12):3278-83.

13. Aoki J, Kimura K, Iguchi Y, et al. Intravenous thrombolysis based on diffusion-weighted imaging and fluid-attenuated inversion recovery mismatch in acute stroke patients with unknown onset time. Cerebrovasc Dis. 2011;31(5):435-41.

14. Sheth KN, Terry JB, Nogueira RG, et al. Advanced modality imaging evaluation in acute ischemic stroke may lead to delayed endovascular reperfusion therapy without improvement in clinical outcomes. Journal of neurointerventional surgery. 2012.

15. Symons SP, Cullen SP, Buonanno F, Gonzalez RG, Lev MH. Noncontrast conventional computed tomography in the evaluation of acute stroke. Seminars in roentgenology. 2002;37(3):185-91.

16. Dzialowski I, Weber J, Doerfler A, Forsting M, von Kummer R. Brain tissue water uptake after middle cerebral artery occlusion assessed with CT. J Neuroimaging. 2004;14(1):42-8.

17. Menon BK, Smith EE, Coutts SB, et al. Leptomeningeal collaterals are associated with modifiable metabolic risk factors. Ann Neurol. 2013;74(2):241-8.

18. Nambiar V, Sohn SI, Almekhlafi MA, et al. CTA collateral status and response to recanalization in patients with acute ischemic stroke. AJNR Am J Neuroradiol. 2014;35(5):884-90.

19. Hacke W, Kaste M, Fieschi C, et al. Randomised double-blind placebo-controlled trial of thrombolytic therapy with intravenous alteplase in acute ischaemic stroke (ECASS II). Second European-Australasian Acute Stroke Study Investigators. Lancet. 1998;352(9136):1245-51.

20. Berkhemer OA, Fransen PS, Beumer D, et al. A randomized trial of intraarterial treatment for acute ischemic stroke. N Engl J Med. 2015;372(1):11-20.

21. Goyal M, Demchuk AM, Menon BK, et al. Randomized assessment of rapid endovascular treatment of ischemic stroke. N Engl J Med. 2015;372(11):1019-30.

22. Saver JL, Goyal M, Bonafe A, et al. Stent-Retriever Thrombectomy after Intravenous t-PA vs. t-PA Alone in Stroke. N Engl J Med. 2015.

23. Jovin TG, Chamorro A, Cobo E, et al. Thrombectomy within 8 Hours after Symptom Onset in Ischemic Stroke. N Engl J Med. 2015.

24. Campbell BC, Mitchell PJ, Kleinig TJ, et al. Endovascular therapy for ischemic stroke with perfusion-imaging selection. N Engl J Med. 2015;372(11):1009-18.

25. Menon BK, Campbell BC, Levi C, Goyal M. Role of imaging in current acute ischemic stroke workflow for endovascular therapy. Stroke. 2015;46(6):1453-61.

26. Kuntz M, Mysiorek C, Petrault O, et al. Stroke-induced brain parenchymal injury drives blood-brain barrier early leakage kinetics: a combined in vivo/in vitro study. J Cereb Blood Flow Metab. 2014;34(1):95-107.

27. Agarwal S, Matys T, Marrapu ST, et al. Is CT-Based Perfusion and Collateral Imaging Sensitive to Time Since Stroke Onset? Frontiers in Neurology. 2015;6:70.

28. Menon BK, Almekhlafi MA, Pereira VM, et al. Optimal workflow and process-based performance measures for endovascular therapy in acute ischemic stroke: analysis of the Solitaire FR thrombectomy for acute revascularization study. Stroke. 2014;45(7):2024-9.

29. Bal S, Bhatia R, Menon BK, et al. Time dependence of reliability of noncontrast computed tomography in comparison to computed tomography angiography source image in acute ischemic stroke. Int J Stroke. 2015;10(1):55-60.


31. Menon BK, Saver JL, Prabhakaran S, et al. Risk score for intracranial hemorrhage in patients with acute ischemic stroke treated with intravenous tissue-type plasminogen activator. Stroke. 2012;43(9):2293-9.

32. Cucchiara B, Kasner S, Tanne D, et al. Validation assessment of risk scores to predict postthrombolysis intracerebral haemorrhage. International journal of stroke : official journal of the International Stroke Society. 2011;6(2):109-11.

33. Strbian D, Engelter S, Michel P, et al. Symptomatic intracranial hemorrhage after stroke thrombolysis: the SEDAN score. Ann Neurol. 2012;71(5):634-41.