Utility of Flat Panel CT Perfusion Studies to Assess Acute Ischemic Stroke in the Angiography Suite

Background

  • Good outcome rates have not increased as quickly, highlighting a need for improved patient selection
  • Physiologic imaging such as CT perfusion (CTP) can demonstrate salvageable penumbra, but such studies take time
  • Modern endovascular devices and techniques achieve high rates of vessel recanalization in acute ischemic stroke (AIS)
  • Flat Panel Detector CT (FPD-CT) can provide physiologic information before, during and after intervention, acquired on the angiography table, but has not been correlated with CTP


Objective

To compare the techniques of CTP and FPD-CT for image quality, speed of acquisition and utility in guiding decision making for treatment of patients with AIS.


Methods

prospective, observational comparison between CTP and FPD-CT


Subjects

  • All patients with AIS that were candidates for endovascular intervention and had standard CTP images available were approached for enrollment and informed consent obtained

FDP-CT

  • Aortic contrast injection and rotational imaging was obtained before and after intervention
  • Image assessment was performed on the workstation with commercially available software (Siemens, Erlangen, Germany)

Image Comparison

  • CTP images including cerebral blood volume, cerebral blood flow and mean transit time were assessed for penumbra/mismatch
  • FPD-CT relative blood volume was assessed before and after intervention, and compared with the CTP penumbra

Results

  • Four cases have been enrolled to date
  • Anatomic correlations between the areas of perfusion defects in the standard CTP representing the penumbra zone (CBV/CBF mismatch) and the area of restricted blood volume on FPD-CT have been observed in all cases
  • Case example: 58-year-old man with left sided hemiplegia had a CTP scan that demonstrated a right MCA territory penumbra with small core infarct (Fig 1A)
  • Pre-intervention FPD-CT perfusion showed restricted blood volume in the same territory (Fig 1B)
  • Successful mechanical thrombectomy was performed (Fig 1 C pre and D post)
  • Post intervention FPD-CT showed reversal of the blood volume perfusion deficit outside of the core infarct zone (Fig 1E)
  • The patient made a good clinical recovery and only small infarct on follow up CT consistent with the observed core deficit (Fig 1 F)

 

Conclusion

  • FPD-CT images can be obtained quickly and reliably with available resources during AIS interventions in the interventional radiology suite
  • Reliable anatomic correlations were observed between CTP penumbra images and FPD-CT restricted perfusion images
  • Following intervention, FPD demonstrated restoration of blood volume to recanalized territory
  • FPC-CT may prove a valuable aid in guiding treatment decisions and evaluating outcomes for AIS management

 

Limitations and Future Directions

  • Small sample size to date, but enrollment is ongoing
  • Further investigation is required to establish the reliability of FPD-CT as a valid marker of salvageable brain tissue, which currently requires comparison with standard perfusion images
  • FPD-CT requires additional iodinated contrast agent, which may limit its use in patients with renal insufficiency

 

References

  1. Mordasini et al. Applicability of tableside flat panel detector CT parenchymal cerebral blood volume measurement in neurovascular interventions: Preliminary clinical experience AJNR. 2012;33:154–158.

  2. Struffert et al. Feasibility of cerebral blood volume mapping by flat panel detector CT in the angiography suite: First experience in patients with acute middle cerebral artery occlusions. AJNR. 2012;33:618-625

 

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