EFFECTIVENESS OF CTA AND CTP IN GUIDING MANAGEMENT DECISIONS FOR ACUTE STROKE

Transcription

1 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

2 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

3 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

4 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.

5 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.

6 Demographics: n=130 (65 male, 65 female) Age: 24-93y/o. (Mean /-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

7 DISCORDANCE BETWEEN MODALITIES PPV: CTP > CTA in stroke detection Low agreement between CTA & CTP results Cohen s Kappa = 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 The negative predictiv value (NPV) reflecting discordance (CTA+ and CTP-) was 0.97.

8 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

9 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

10 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

11 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)

12 DISCUSSION CTP most sensitive Low agreement between CTA & CTP results Both CTA & CTP necessary

13 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 : 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 (7) 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 : News from the International Stroke Conference: The Cost of tpa Has Doubled, But Reimbursement to Hospitals Has Not Kept Pace. Neurology Today. Mar (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 Web. 26 July Srinivasan, Aravind, M. Goyal, F. Al Azri, and C. Lum. "State-of-the-art Imaging of Acute Stroke." Pubmed