1 of 19

CT Perfusion in Acute Ischemic Stroke and Review of Turnaround Time in an Emergency Teleradiology Setting

Authors: Dr Srilozu Bhavya , Dr . Pallavi Rao, Dr . Arjun Kalyanpur

Institution: Teleradiology Solutions and Image Core Lab

SERCON 2023, October, Bengaluru

2 of 19

Introduction

Acute ischemic stroke is a leading cause of adult disability worldwide.

Modern endovascular treatment for acute ischemic stroke is predicated on advanced imaging modalities and the identification of salvageable ischemic penumbra from the irrevocably damaged infarcted brain.

CT perfusion (CTP) is an important adjunct to conventional non-enhanced CT brain and CT angiography in the evaluation of acute ischemic stroke (AIS).

https://www.sciencedirect.com/science/article/pii/S0010865016000102

3 of 19

Methods of CT perfusion

https://www.sciencedirect.com/science/article/pii/S0010865016000102

The basis of CT perfusion imaging is the “tracking” of a single injected bolus of iodinated contrast material through the cerebral circulation via sequential spiral CT scanning.

rCBF - Measured in mL of blood per 100 g of parenchyma per minute.

rCBV - Measured in mL of blood per 100 g of parenchyma.

MTT - Measurement of the mean time for blood to travel through a given volume of brain, thereby reflecting the amount of time it takes for the bolus of contrast material to pass from the arterial to the venous circulation.

Tmax - Delay between the first arrival of contrast material intracranially and the time at which the contrast reaches its peak concentration in a given region of brain parenchyma.

CT Perfusion parameters

4 of 19

Acute infarct - matched decrease in rCBF and rCBV, increased MTT and Tmax.

Acute ischemia - mild decrease in rCBF with relatively preserved rCBV, increased Tmax, and MTT.

Acute infarct with ischemic penumbra - focal area of decreased rCBF and rCBV, increased MTT and Tmax with a surrounding area of preserved rCBV.

Acute infarct

Acute ischemia/penumbra

Acute infarct with ischemic penumbra

5 of 19

Materials and Methods

Retrospective evaluation of 1230 CT Perfusion studies positive for infarcts as per the emergency radiology reports.

Study images were analysed for different features of Acute ischemic stroke.

The results were analyzed and compiled into a pictorial review.

6 of 19

Due to timely CTP imaging, reversible ischemic brain parenchyma is identified in majority of cases.

7 of 19

MCA territories are involved in more than 80 percent of cases with incidence of right MCA involvement slightly greater than left MCA territory.

MCA –Middle cerebral artery, ACA – Anterior cerebral artery, PCA – Posterior cerebral artery, BA – Basilar artery

8 of 19

More than 80 percent of cases were reported under 30min with

critical value findings of salvageable areas of ischemic brain parenchyma conveyed within the golden hour of treatment of stroke thereby improving patient outcomes.

9 of 19

Case 1

Case details: A female patient aged 52 years with a perfusion defect showing focal area of decreased rCBF and rCBV, increased MTT and Tmax with a surrounding area of preserved rCBV in the right MCA territory, consistent with

acute infarct with ischemic penumbra.

10 of 19

Case details: A male patient aged 82 years with a perfusion defect showing decreased rCBF and rCBV, increased MTT and Tmax in the right MCA territory, consistent with acute infarct.

11 of 19

Case details: A male patient aged 31 years with a perfusion defect showing focal area of decreased rCBF and rCBV, increased MTT and Tmax with a surrounding area of preserved rCBV, consistent with acute infarct with ischemic penumbra in left MCA territory.

12 of 19

Case details: A 48 years aged patient with perfusion defect showing decreased rCBF, preserved rCBV and increased MTT,

consistent with large ischemic penumbra in right MCA territory.

13 of 19

Case details: A 68years old patient with a perfusion defect showing focal area of decreased rCBF and rCBV, increased MTT and Tmax with a surrounding area of preserved rCBV, consistent with

acute infarct with ischemic penumbra in left MCA and ACA territory.

14 of 19

Case 8

Case details: A male patient aged 88 years with a perfusion defect showing preserved rCBF, rCBV and increased MTT, consistent with acute ischemia in Left PCA territory.

15 of 19

Case details: A 51-year-old male patient with perfusion defect showing increased Tmax without significant decrease in rCBF, suggestive of ischemic penumbra in bilateral ACA territories.

16 of 19

Case details: A male patient aged 46 years with a perfusion defect showing increased MTT and T max without significant decrease of rCBF and rCBV, consistent with large ischemic penumbra in left MCA territory. There is also small acute infarct in right PCA territory.

17 of 19

Conclusion

Our study establishes that more than half of the patients with AIS potentially benefited from CTP evaluation by predicting presence of salvageable ischemic non infarcted brain tissue.

We also highlight the significance of decreasing TAT through efficient Teleradiology reports, conveying critical value reversible findings and improve patient outcomes during golden hour of treatment of stroke.

18 of 19

References

Stephan A. Munich, Hakeem J. Shakir, Kenneth V. Snyder. Role of CT perfusion in acute stroke management. Cor et Vasa,2016;58(2):215-224.

Straka M, Albers GW, Bammer R. Real-time diffusion-perfusion mismatch analysis in acute stroke. J Magn Reson Imaging. 2010;32(5):1024-1037.

Potter, Achala S. Vagal, Mayank Goyal. CT for Treatment Selection in Acute Ischemic Stroke: A Code Stroke Primer. RadioGraphics 2019; 39:1717–1738.

Bivard Andrew, Levi Christopher, et al. Perfusion CT in Acute Stroke: A Comprehensive Analysis of Infarct and Penumbra. Radiology.2013;276(2): 458-502.