Multiphase CT angiography increases detection of anterior circulation intracranial occlusion

Abstract

Objective: To evaluate whether the use of multiphase CT angiography (CTA) improves interrater agreement for intracranial occlusion detection between stroke neurology trainees and an expert neuroradiologist.Methods: A neuroradiologist and 2 stroke neurology fellows independently reviewed 100 prospectively collected single-phase and multiphase CTA scans from acute ischemic stroke patients with mild symptoms (NIH Stroke Scale score #5). The presence and location of a vascular occlusion(s) were documented. Interrater agreement single-and multiphase CTA was quantified using unweighted k statistics. We assessed for any occlusions, anterior vs posterior occlusions, and pial vessel asymmetry.Results: Using multiphase CTA, the neuroradiologist detected 50 scans with anterior circulation occlusions and 15 scans with posterior circulation occlusions. Median reading time was 2 minutes per scan. Median reading time for the neurologists was 3 minutes per multiphase CTA scan. Interrater agreement was fair between the 2 neurologists and neuroradiologist when using single-phase CTA (k 5 0.45 and 0.32). Agreement improved minimally when stratified by anterior vs posterior circulation. When using multiphase CTA, agreement was high for detection of occlusion or asymmetry of pial vessels in the anterior circulation (k 5 0.80 and 0.84).Conclusions: Multiphase CTA improves diagnostic accuracy in minor ischemic stroke for detection of anterior circulation intracranial occlusion. Classification of evidence:This study provides Class II evidence that multiphase CTA, compared to single-phase CTA, improves the interrater agreement between stroke neurology trainees and an expert neuroradiologist for detecting anterior circulation intracranial vascular occlusion in patients with minor acute ischemic strokes.

“Delayed Pial Vessels” in Multiphase CT Angiography Aid in the Detection of Arterial Occlusion in Anterior Circulation

“…Both low-flow (upstream stenoocclusive lesions) and high-flow (recanalization) states could cause pial vessel asymmetry as proposed in our article. 3 Our study also established that mCTA is a user-friendly imaging tool that can improve the diagnostic accuracy for anterior circulation occlusions, even when used by relatively inexperienced readers and when occlusions are more distal. Thus, inclusion of multiphase CTA in acute ischemic stroke imaging protocols has the potential to allow non-radiology trained physicians and trainees to rapidly and accurately determine anterior circulation occlusions, a crucial point in clinical management when considering patients for revascularization procedures.…”

“…A recent study from our group was able to show an increase in the detection of anterior circulation intracranial occlusion with mCTA, especially for distal occlusions. 3 In the presence or absence of obvious large-vessel occlusion, pial vessel asymmetry in the second and third phase added to the yield of mCTA for occlusion detection. The "delayed vessel sign" mentioned in the study by Byrne et al 1 is one but not the only component of pial vessel asymmetry as explained above.…”

“…Thus, inclusion of multiphase CTA in acute ischemic stroke imaging protocols has the potential to allow non-radiology trained physicians and trainees to rapidly and accurately determine anterior circulation occlusions, a crucial point in clinical management when considering patients for revascularization procedures. 3 Furthermore, pial vessel dynamics captured on mCTA can also be quantified to provide information similar to that of perfusion CT and can be used to predict tissue fate regionally in patients with acute ischemic stroke. 4…”

Management of Acute Ischemic Stroke

“…Neurointerventionalists can plan an endovascular procedure with CT angiography information. 26 MRI diffusion-weighted imaging and fluid-attenuated inversion recovery are more sensitive to detect ischemia/ infarction, but they are time consuming. DWI maps show early ischemic changes within minutes from stroke onset, and a correlating apparent diffusion coefficient map visualizes the extent of cytotoxic edema caused by brain ischemia.…”

Acute Ischemic Stroke Management Review for the Hospitalist

“…CTA is also beneficial in recognizing large non-stenotic plaques, more common in the ipsilateral carotids, which are implied in cryptogenic strokes (60). Multiphase CTA is an imaging tool that provides three timeresolved images of pial arterial filling in the whole brain; it has excellent inter rater agreement, especially for anterior circulation occlusions (61,62). Multimodal CT evaluation improves detection rate and prediction of the final size of an infarction in comparison with unenhanced CT, CT angiography, and perfusion CT alone (63).…”