EFFECTIVENESS OF CTA AND CTP IN GUIDING MANAGEMENT DECISIONS FOR ACUTE STROKE Jon Benton MS-4, Chirag Dani MD, Vincent Persaud MD, Bilal A. Manzer, Macksood Aftab DO, MHA
OBJECTIVES 1. Utility of advanced CT modalities; CTA & CTP 2. Concordance/Discordance between CTA & CTP 3. Correlation between imaging results and management decision 4. Are both CTA & CTP necessary in evaluating stroke symptoms? 5. Limitations to this retrospective analysis
METHODS Selection & Data retrieval: IRB Exemption obtained. 130 radiology reports gathered from last 200 days using Picture Archiving and Communication System (PACS) & anonymized Inclusion Criteria: Code Stroke patient from last 200 days. CTA and CTP studies ordered. Exclusion Criteria: (+) Head CT
METHODS Interpretation: (+) CTP: pneumbra at least 2x size of core infarct (+) CTA: major vessel occlusion of Basilar Artery, MCA or ICA Initial interpreted by the same radiologist Incongruent results reviewed again by second neuroradiologist (Dr. Aftab) to confirm results.
CTA: anatomical identifies blood flow obstructions CTA VS CTP CTP : physiologic identifies areas of hypoperfusion (infarct/penumbra) CBF CBV MTT Figure 1: Small left MCA core infarct with large pneumbra. Dynamic CT Perfusion imaging (CTP) generates color maps displayed above: Cerebral Blood Volume (CBV), Cerebral Blood Flow (CBF) and Mean Transit Time (MTT), respectively. Figure 2: Left MCA (M1 segment) occlusion. CT Angiography (CTA) visualizes intracranial arterial flow and is very sensitive for major vessel occlusions.
Demographics: n=130 (65 male, 65 female) Age: 24-93y/o. (Mean 66.9 +/-15.4 y/o) Findings: - Either CTA or CTP positive (22%) - Detection by CTP (22%) > CTA (9%) Excluding cases with N/A values - PPV: CTP > CTA in stroke detection - Low agreement between CTA & CTP results (Cohen s Kappa = 0.192) - IV-tPA administration - - less likely if advanced CT(-) - - more likely if advanced CT (+) RESULTS
DISCORDANCE BETWEEN MODALITIES PPV: CTP > CTA in stroke detection Low agreement between CTA & CTP results Cohen s Kappa = 0.192 CTP CTP/CTA Correlation CTA Positive Negative Positive 6 20 Negative 3 90 Table 1: Predictive value table of CTA vs CTP results. Positive predictive value (PPV) reflecting agreement (CTA+ and CTP+) was 0.23. The negative predictiv value (NPV) reflecting discordance (CTA+ and CTP-) was 0.97.
IMAGING EFFECTIVENESS CTP positive 19.2% CTA positive 7.7% Both positive 4.6% Discordance between CTA & CTP Figure 1: The proportion of positive CTP (19.2%), CTA (7.7%), CTA AND CTP (4.6%), either CTA OR CTP (22.3%) out of the total cases (n=130) This includes cases in which no values were obtained due to mechanical failure. All cases were negative for
LIMITATIONS Mechanical failure of CTA and/or CTP may underestimate the PPV for Imaging IV-TPA candidates that did not receive treatment were not excluded Refusal advanced directives death Secondary measures not obtained in stroke identified outside the emergency dept NIHSS score Time of onset Time to CT
DISCUSSION IV-tPA less likely given when advanced CT(-) and more likely if advanced CT (+) Reasons documented for no tpa when CT (+) 1. Stroke mimic 2. Refusal/advanced directives 3. tpa exclusion criteria 4. Death
DISCUSSION Reasons for (+) CTP with (-) CTA Small vessel infarcts, high grade proximal stenosis. (-) CTP with (+) CTA: Chronic occlusion with collateralization/hemodynamic compensation. Most cases were CT negative despite stroke-like symptoms (mimic or small lacunar stroke)
DISCUSSION CTP most sensitive Low agreement between CTA & CTP results Both CTA & CTP necessary
ACKNOWLEDGEMENTS Lui, Y., Tang, E., Allmendinger, A., Spektor, V. Evaluation of CT perfusion in the setting of cerebral ischemia: patterns and pitfalls. AJNR Am J Neuroradiol. 2010. 31:1552 1563. Bivard, A., Levi, C., Krishnamurthy, V., McElduff, P., Miteff, F., Spratt, N., Bateman, G., Donnan, G., Davis, S., Parsons, M. Perfusion computed tomography to assist decision making for stroke thrombolysis. Brain. Jul 2015. 38 (7) 1919-1931. Allmendinger, A., Tang, E., Lui, Y., Spektor, V. Imaging of Stroke: Part I, Perfusion CT- Overview of Imaging technique, Interpretation, and Common Pitfalls. AJR Jan 2012. 198:52-62. News from the International Stroke Conference: The Cost of tpa Has Doubled, But Reimbursement to Hospitals Has Not Kept Pace. Neurology Today. Mar 2016. 16(6): 46. Hoeffner, E., Case, I., Jain,R., Gujar, S., Shah, G., Deveikis, J., Carlos, R., Thompson, B., Harrigan, M. and Mukherji, S. "Cerebral Perfusion CT: Technique and Clinical Applications." Radiology, June 2004. Web. 26 July 2016. Srinivasan, Aravind, M. Goyal, F. Al Azri, and C. Lum. "State-of-the-art Imaging of Acute Stroke." Pubmed