Differentiation of Hemorrhage from Iodine Using Spectral Detector CT: A Phantom Study

S. Van Hedent; N. G. Hokamp; K.R. Laukamp; N. Buls; R. Kessner; B. Rose; P. Ros; D. Jordan

doi:10.3174/ajnr.A5872

Abstract

BACKGROUND AND PURPOSE: Conventional CT often cannot distinguish hemorrhage from iodine extravasation following reperfusion therapy for acute ischemic stroke. We investigated the potential of spectral detector CT in differentiating these lesions.

MATERIALS AND METHODS: Centrifuged blood with increasing hematocrit (5%–85%) was used to model hemorrhage. Pure blood, blood-iodine mixtures (75/25, 50/50, and 25/75 ratios), and iodine solutions (0–14 mg I/mL) were scanned in a phantom with attenuation ranging from 12 to 75 HU on conventional imaging. Conventional and virtual noncontrast attenuation was compared and investigated for correlation with calculation of relative virtual noncontrast attenuation. Values for all investigated categories were compared using the Mann-Whitney U test. Sensitivity and specificity of virtual noncontrast, relative virtual noncontrast, conventional CT attenuation, and iodine quantification for hemorrhage detection were determined with receiver operating characteristic analysis.

RESULTS: Conventional image attenuation was not significantly different among all samples containing blood (P > .05), while virtual noncontrast attenuation showed a significant decrease with a decreasing blood component (P < .01) in all blood-iodine mixtures. Relative virtual noncontrast values were significantly different among all investigated categories (P < .01), with correct hemorrhagic component size estimation for all categories within a 95% confidence interval. Areas under the curve for hemorrhage detection were 0.97, 0.87, 0.29, and 0.16 for virtual noncontrast, relative virtual noncontrast, conventional CT attenuation, and iodine quantification, respectively. A ≥10-HU virtual noncontrast, ≥20-HU virtual noncontrast, ≥40% relative virtual noncontrast, and combined ≥10-HU virtual noncontrast and ≥40% relative virtual noncontrast attenuation threshold had a sensitivity/specificity for detecting hemorrhage of 100%/23%, 89%/95%, 100%/82%, and 100%/100%, respectively.

CONCLUSIONS: Spectral detector CT can accurately differentiate blood from iodinated contrast in a phantom setting.

ABBREVIATIONS:

ICH: intracranial hemorrhage
R-VNC: relative virtual noncontrast
SDCT: spectral detector CT
VNC: virtual noncontrast

Footnotes

Disclosures: Steven Van Hedent—RELATED: Grant: Philips Healthcare, Comments: Partial funding support was provided by Philips Healthcare under a research agreement with University Hospitals Cleveland Medical Center and Case Western Reserve University.* Nils Grosse Hokamp—RELATED: Grant: University Hospitals Cleveland Medical Center/Case Western Reserve University/Philips Healthcare, Comments: Part of this Research was funded under a research agreement among University Hospitals Cleveland Medical Center, Case Western Reserve University, and Philips Healthcare*; UNRELATED: Payment for Lectures Including Service on Speakers Bureaus: Philips Healthcare, Comments: Speakers Bureau; Payment for Development of Educational Presentations: Philips Healthcare. Nico Buls—UNRELATED: Payment for Lectures Including Service on Speakers Bureaus: GE Healthcare, Comments: lectures on dual-energy CT.* Pablo Ros—UNRELATED: Other: Philips Healthcare, Comments: The CT unit where this research was performed is provided by Philips Healthcare to our hospital to test clinical applications. This project was an exhibit in our existing Master Research Agreement. No direct funds were received*; OTHER RELATIONSHIPS: hospital grant from Philips regulated by Master Research Agreement, consisting of a Spectral Detector CT unit. David Jordan—RELATED: Grant: Philips Healthcare, Comments: The IQon CT scanner was provided to University Hospitals Cleveland Medical Center under a research agreement*; UNRELATED: Payment for Lectures Including Service on Speakers Bureaus: Medical Technology Management Institute/Herzing University, Comments: paid speaker for continuing education programs for medical physicists. Kai Roman Laukamp—RELATED: Grant: Philips Healthcare, Comments: Philips Healthcare provided partial funding*. *Money paid to the institution.
Preliminary results previously presented as an electronic poster at: Annual Meeting of the European Congress of Radiology, February 28 to March 4, 2018;Vienna, Austria.
This work was partially supported by Philips Healthcare under a research agreement with University Hospitals Cleveland Medical Center and Case Western Reserve University.