Elsevier

Clinical Imaging

Volume 69, January 2021, Pages 75-78
Clinical Imaging

Neuroradiology
Differentiation of hemorrhage from contrast enhancement using dual-layer spectral CT in patients transferred for acute stroke

https://doi.org/10.1016/j.clinimag.2020.06.046Get rights and content

Highlights

  • CT spectral imaging can differentiate intracranial contrast from hemorrhage.

  • Patients transferred for acute stroke undergo a CT head exam upon arrival.

  • Contrast given at the first hospital may mimic hemorrhage on the post-transfer CT.

  • CT spectral imaging helps distinguish contrast from hemorrhage in this setting.

Abstract

Acute stroke patients transferred to thrombectomy capable centers (TCC), undergo a CT head exam upon arrival at the TCC to evaluate for ASPECTS decay and intracranial hemorrhage. In patients who received iodinated contrast prior to transfer, parenchymal enhancement may simulate hemorrhage on this post-transfer CT. We report two cases utilizing CT spectral imaging to differentiate between parenchymal contrast enhancement and hemorrhage in this setting. TCC may consider dual-energy or dual-layer (spectral) imaging for this patient cohort.

Section snippets

Technique and illustrative cases

Spectral CT imaging was performed utilizing a Philips IQon Spectral CT 64 slice scanner (Philips Healthcare, Best, Netherlands): 255 mAs, 120 kVp, pitch = 0.359, gantry rotation time = 330 ms, detector collimation = 64 × 0.625 mm, volume CT dose index = 43.8 mGy. Conventional CT images were reconstructed using an iterative reconstruction algorithm (iDose, Level 2; Philips Healthcare). Spectral images were reconstructed using a spectral reconstruction algorithm (Spectral, level 2). Reconstructed

Case 1

An 84 year-old male with history of atrial fibrillation on anticoagulation presented to an outside hospital with right sided weakness, facial droop, and aphasia. CT angiogram demonstrated a proximal left middle cerebral artery M2 occlusion. The patient was transferred for potential mechanical thrombectomy. Upon arrival, the NIH stroke scale was 24. The initial head CT upon arrival was performed on a Philips IQon CT 256 slice scanner (without spectral imaging) and was obtained approximately 3 h

Case 2

A 93 year-old male with history of atrial fibrillation presented to an outside institution with slurred speech and left sided weakness. CTA of the head performed at the outside institution demonstrated a proximal right middle cerebral artery M2 branch occlusion. Upon arrival, the NIH stroke scale was 16. Initial head CT after arrival was performed on a CT spectral scanner (approximately 3.5 h after the initial CT angiogram examination), and demonstrated acute infarcts within the right temporal

Discussion

Recent clinical trials have demonstrated the benefits of mechanical thrombectomy in patients presenting with late window strokes [[1], [2], [3]]. Consequently, increasing number of patients may be suitable candidates for transfer to a TCC for mechanical thrombectomy. During transfer to a TCC, stroke patients may exhibit a decay in the ASPECTS score [4] or new intracranial hemorrhage. Accordingly, upon arrival to the TCC, immediate imaging evaluation is performed to exclude a large stroke burden

Conclusion

In our experience, acute stroke patients transferred for potential mechanical thrombectomy, may demonstrate parenchymal hyperdensities related to contrast administration at the first institution. Virtual non-contrast images are helpful in distinguishing parenchymal contrast enhancement from hemorrhage in this setting. TCC may consider adopting a workflow in which acute stroke patients transferred for potential thrombectomy are initially imaged with a dual-energy or dual-layer spectral CT

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Cited by (5)

  • Potential of dual-layer spectral CT for the differentiation between hemorrhage and iodinated contrast medium in the brain after endovascular treatment of ischemic stroke patients

    2021, Clinical Imaging
    Citation Excerpt :

    As SPCCT is a promising technique that offers the potential to improve image quality, lower image noise and reduce radiation dose38 it might replace the DLSCT system in the future when applicable for clinical use. The possibility to differentiate between blood and iodinated contrast agent might also be useful in cases where patients received iodinated contrast agent prior to the essential head CT scan within the stroke examination or before the transport to centers capable for thrombectomy, where CT scans might be repeated to exclude secondary hemorrhage.39 Another interesting application of DLSC in the field of neuroradiology might be for tumor diagnostics for the differentiation between hemorrhage and contrast-enhancing tumor parts40 or the differentiation between iodinated contrast agent and calcifications.41

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