SIGNIFICANT REDUCTION OF DOOR-TO-GROIN TIMES

We first started our one stop management back in January 2016 with transfer patients. As the majority of those patients is treated with thrombolysis during transport to our comprehensive stroke center, repeated imaging is justified to exclude an intracranial hemorrhage. We recently published a paper showing high sensitivity and specificity of FDCT in the detection of intracranial hemorrhages.¹⁰ Based on this study, we also implemented this one stop management in direct admission or “mothership” patients in June 2016.

We only included patients with an NIHSS ≥ 10 in this first step. After treating 30 patients with this protocol we analyzed our findings and have submitted a manuscript, which is currently under review. The initial experience shows that we were able to significantly reduce our door to CT and door to groin times, while successfully differentiating ischemic from hemorrhagic stroke. In January 2017, we lowered the one stop management threshold to an NIHSS ≥ 7 based on a study indicating that an NIHSS ≥ 7 in the best threshold for predicting LVO.¹¹

Portrait FDCT-A - intravenous injection of 60 ml contrast agent (Imeron 400; Bracco Imaging GmbH, Konstanz, Germany) at an injection rate of 5 ml/s followed by 60 ml saline chaser at the same injection rate of 5 ml/s; a power injector is used for injection; 1 x 10 s rotation, 200° total angle (0.8° per frame), 90 kV, 1,2 μGy/frame; effective dose ∼0.91 mSv.

FDCT-P - intravenous injection of 60 ml contrast agent (Imeron 400; Bracco Imaging GmbH, Konstanz, Germany) at an injection rate of 5 ml/s followed by 60 ml saline chaser at the same injection rate of 5 ml/s; a power injector is used for injection; 10 x 5 s rotation, 200° total angle (0.8° per frame), 70 kV, 0,36 μGy/frame; effective dose ∼2.88 mSv (collimated).

For the non-contrast Sine Spin FDCT, a “HU smooth” kernel and “DynaCT Clear” algorithm are applied to obtain images with a 512 × 512 matrix. These are reconstructed with 5 mm slice thickness and 3 mm interslice distance. FDCT images are used for the detection of intracranial hemorrhages and large ischemic lesions. Images acquired according to our protocol proved to be a reliable and accurate tool for the detection of intracranial hemorrhage. Gray–white differentiation is feasible in the supratentorial region.^{10, 12}

The rotation of the portrait FDCT-A is timed after a bolus-tracking digital subtraction angiography to capture the peak arterial phase. The portrait FDCT-A has an increased field of view compared to the traditional “landscape” FDCT-A due to a rotation of the detector by 90° (see figure X for comparison). It enables the physician to simultaneous visualize the circulus willisii and the intra- and extracranial carotid arteries down to their origin. This information is crucial for the planning of the intervention. For reconstruction of the FDCT-A, a “HU normal” kernel is utilized. Images are reconstructed as maximum intensity projections (MIPs) with a slice thickness of 24 mm and an interslice distance of 3 mm. It allows for the reliable detection of large vessel occlusions.

We collimate the FDCT-P for depiction of the cerebrum only, thus reducing the radiation dose substantially (almost 50%). The FDCT-P images are automatically reconstructed using RAPID AI for Angio (see figure X). As a recent publication showed a strong correlation between FDCT-P and MDCT-P for the automated measurements of core and mismatch values, this protocol can be used for patient selection.¹³ Recent studies showed that Perfusion imaging has a higher sensitivity for the detection of distal vessel occlusions.¹⁴ We therefore use this protocol also in the early time-window to detect patients suitable for endovascular therapy. This approach ensures that no patient with a distal but treatable vessel occlusion is missed.

The effective dose of our stroke protocol (overall effective dose of ~5.5 mSv) is comparable to published MDCT stroke protocols with perfusion imaging. Although the coverage of our FDCT-A protocol is not equal to cervical MDCT-A scans depicting the aortic arch, the coverage is long enough to evaluate the internal and external carotid arteries down to their origins.