Abstract
PurposeTo evaluate a novel flow-independent 3D isotropic REACT sequence compared with CE-MRA for the imaging of extracranial arteries in acute ischemic stroke (AIS).MethodsThis was a retrospective study of 35 patients who underwent a stroke protocol at 3 T including REACT (fixed scan time: 2:46 min) and CE-MRA of the extracranial arteries. Three radiologists evaluated scans regarding vessel delineation, signal, and contrast and assessed overall image noise and artifacts using 5-point scales (5: excellent delineation/no artifacts). Apparent signal- and contrast-to-noise ratios (aSNR/aCNR) were measured for the common carotid artery (CCA), internal carotid artery (ICA, C1 segment), and vertebral artery (V2 segment). Two radiologists graded the degree of proximal ICA stenosis.ResultsCompared to REACT, CE-MRA showed better delineation for the CCA and ICA (C1 and C2 segments) (median 5, range 2–5 vs. 4, range 3–5; P < 0.05). For the ICA (C1 and C2 segments), REACT provided a higher signal (5, range 3–5; P < 0.05/4.5, range 3–5; P > 0.05 vs. 4, range 2–5) and contrast (5, range 3–5 vs. 4, range 2–5; P > 0.05) than CE-MRA. The remaining segments of the blood-supplying vessels showed equal medians. There was no significant difference regarding artifacts, whereas REACT provided significantly lower image noise (4, range 3–5 vs. 4 range 2–5; P < 0.05) with a higher aSNR (P < 0.05) and aCNR (P < 0.05) for all vessels combined. For clinically relevant (≥50%) ICA stenosis, REACT achieved a detection sensitivity of 93.75% and a specificity of 100%.ConclusionGiven its fast acquisition, comparable image quality to CE-MRA and high sensitivity and specificity for the detection of ICA stenosis, REACT was proven to be a clinically applicable method to assess extracranial arteries in AIS.
Highlights
In acute ischemic stroke (AIS), imaging of the extracranial arteries is required to detect atherosclerosis and associated comorbidities, such as internal carotid artery (ICA) stenosis as well as large vessel occlusion and dissection [1].First-pass contrast-enhanced magnetic resonance angiography (CE-MRA) using gadolinium-based contrast agents represents the standard of care for cervical arteries in stroke magnetic resonance imaging (MRI), providing high spatial resolution [2, 3]
Mistiming of image acquisition regarding first-pass contrast bolus resulting in insufficient contrast or venous contamination leads to impaired image quality in CE-MRA [9, 10]
Several non-CE-MRA techniques have been developed in the past, with 2D/3D time-of-flight (TOF)MRA being a possible approach for extracranial arteries; compared to CE-MRA, 2D/3D TOF-MRA has the disadvantages of a long acquisition time, sensitivity to respiratory and flow artifacts, inferior image quality, decreased anatomic coverage and overestimation of ICA stenosis [12,13,14,15,16]
Summary
First-pass contrast-enhanced magnetic resonance angiography (CE-MRA) using gadolinium-based contrast agents represents the standard of care for cervical arteries in stroke magnetic resonance imaging (MRI), providing high spatial resolution [2, 3]. Mistiming of image acquisition regarding first-pass contrast bolus resulting in insufficient contrast or venous contamination leads to impaired image quality in CE-MRA [9, 10]. Several non-CE-MRA techniques have been developed in the past, with 2D/3D time-of-flight (TOF)MRA being a possible approach for extracranial arteries; compared to CE-MRA, 2D/3D TOF-MRA has the disadvantages of a long acquisition time, sensitivity to respiratory and flow artifacts, inferior image quality, decreased anatomic coverage and overestimation of ICA stenosis [12,13,14,15,16]. 2D acquisition and dependency on the inflow of spins from outside the saturation volume have to be considered [10, 18,19,20]
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