Iodine Extravasation Quantification on Dual-Energy CT of the Brain Performed after Mechanical Thrombectomy for Acute Ischemic Stroke Can Predict Hemorrhagic Complications

Abstract

Background and purpose: Intracerebral hemorrhage represents a potentially severe complication of revascularization of acute ischemic stroke. The aim of our study was to assess the capability of iodine extravasation quantification on dual-energy CT performed immediately after mechanical thrombectomy to predict hemorrhagic complications.

Materials and methods: Because this was a retrospective study, the need for informed consent was waived. Eighty-five consecutive patients who underwent brain dual-energy CT immediately after mechanical thrombectomy for acute ischemic stroke between August 2013 and January 2017 were included. Two radiologists independently evaluated dual-energy CT images for the presence of parenchymal hyperdensity, iodine extravasation, and hemorrhage. Maximum iodine concentration was measured. Follow-up CT examinations performed until patient discharge were reviewed for intracerebral hemorrhage development. The correlation between dual-energy CT parameters and intracerebral hemorrhage development was analyzed by the Mann-Whitney U test and Fisher exact test. Receiver operating characteristic curves were generated for continuous variables.

Results: Thirteen of 85 patients (15.3%) developed hemorrhage. On postoperative dual-energy CT, parenchymal hyperdensities and iodine extravasation were present in 100% of the patients who developed intracerebral hemorrhage and in 56.3% of the patients who did not (P = .002 for both). Signs of bleeding were present in 35.7% of the patients who developed intracerebral hemorrhage and in none of the patients who did not (P < .001). Median maximum iodine concentration was 2.63 mg/mL in the patients who developed intracerebral hemorrhage and 1.4 mg/mL in the patients who did not (P < .001). Maximum iodine concentration showed an area under the curve of 0.89 for identifying patients developing intracerebral hemorrhage.

Conclusions: The presence of parenchymal hyperdensity with a maximum iodine concentration of >1.35 mg/mL may identify patients developing intracerebral hemorrhage with 100% sensitivity and 67.6% specificity.

Fig 1.

A, Postoperative DECT with an iodine map overlay shows a cortical-subcortical hyperdensity secondary to iodine extravasation with a maximum iodine concentration of 3.0 mg/mL; no hyperdensity was visible on virtual unenhanced images (not included). B, A follow-up CT performed 48 hours later because of sudden clinical worsening shows a large parenchymal hematoma with a contralateral shift of the midline structures.

Fig 2.

A, Postoperative DECT with an iodine map overlay shows a cortical-subcortical and deep white matter hyperdensity secondary to iodine extravasation with a maximum iodine concentration of 1.2 mg/mL; no hyperdensity was visible on virtual unenhanced images (not included). B, The follow-up CT performed before discharge, 4 days later, shows ischemic lesions at the sites of iodine extravasation but no hemorrhage.

Fig 3.

Receiver operator characteristic (ROC) curve showing sensitivity and specificity of maximum hyperdensity attenuation in identifying patients developing ICH.

Fig 4.

Receiver operator characteristic (ROC) curve showing sensitivity and specificity of maximum iodine concentration in identifying patients developing ICH.

Fig 5.

Graph showing the linear correlation existing between maximum hyperdensity attenuation and maximum iodine concentration.

Fig 6.

Diagnostic algorithm that enables identifying patents developing ICH with 100% sensitivity and 67.6% specificity.