Gadobutrol Enhanced MRA of the Supra-aortic Vessels

Each vascular segment was visualized using unenhanced MRA and gadobutrol-enhanced MRA, characterized by the on-site investigators, three independent blinded readers (BR) (BR 1, BR 2 and BR 3) and majority readers (the outcome determined by at least two of the blinded readers). A segment was assessable if it was visualized along its entire length and if any region of stenosis, was measured reliably. There were 21 segments of the supra-aortic arteries assessed per participant.

Clinically significant disease was defined as 70 to 99% stenosis of a segment, but not occluded, as assessed by the standard of reference (SoR) (computed tomographic angiography [CTA]; blinded readers). This was determined using the North American Symptomatic Carotid Endarterectomy Trial (NASCET) criteria. For each segment, the most severe stenosis/narrowing was identified and considered for the evaluation of clinically significant disease. In case of multiple stenosis in any one segment, the most severe stenosis in the segment was recorded.

Clinically significant disease was defined as 70 to 99% stenosis of a segment, but not occluded, as assessed by the SoR (CTA; blinded readers). This was determined using the NASCET criteria. For each segment, the most severe stenosis/narrowing was identified and considered for the evaluation of clinically significant disease. In case of multiple stenosis in any one segment, the most severe stenosis in the segment was recorded.

Clinically significant disease was defined as 70 to 99% stenosis of a segment, but not occluded as assessed by the SoR (CTA; blinded readers). For each segment, the most severe stenosis/narrowing was identified and considered for the evaluation of clinically significant disease. Gadobutrol minimum performance criteria was based on a stenosis of 50% calculated from the native vessel diameter.

Clinically significant disease was defined as 70 to 99% stenosis of a segment, but not occluded as assessed by the SoR (CTA; blinded readers). For each segment, the most severe stenosis/narrowing was identified and considered for the evaluation of clinically significant disease. Gadobutrol minimum performance criteria was based on a stenosis of 50% calculated from the native vessel diameter.

The segment reduction in diameter (DIA) of greater than 10% was considered abnormal and measured. The diameter of each of these abnormal segments was measured using electronic calipers (perpendicular to the long axis of the vessel) at the point of most severe stenosis within each segment. Mean of vessel diameters was calculated by segment separately for CTA and MRA readers. For ease of expression, the following abbreviations will be used: Diameter (DIA), Blinded Reader (BR), Clinical Investigator (CI).

Artifacts were collected for the MRA images on a segmental basis.

The following types of artifacts were considered: Motion artifact (including pulsatility, breathing, swallowing), venous opacification, saturation artifact (for example [eg], in-plane flow, turbulence, dephasing, saturation band), susceptibility artifacts (including devices, eg, stents), ringing artifact (eg, bands), bolus timing error, and other (artifact not specified above or no artifact).

The following types of artifacts were considered: Motion artifact (including pulsatility, breathing, swallowing), venous opacification, saturation artifact (for example [eg], in-plane flow, turbulence, dephasing, saturation band), susceptibility artifacts (including devices, eg, stents), ringing artifact (eg, bands), bolus timing error, and other (artifact not specified above or no artifact).

The following types of artifacts were considered: Motion artifact (including pulsatility, breathing, swallowing), venous opacification, saturation artifact (for example [eg], in-plane flow, turbulence, dephasing, saturation band), susceptibility artifacts (including devices, eg, stents), ringing artifact (eg, bands), bolus timing error, and other (artifact not specified above or no artifact).

Location within a segment was based on the point of greatest stenosis and was recorded for stenosis >=70% (including occlusions) as: - At the bifurcation or proximal origin of a segment (occlusion proximal to the origin of the segment); - Within 5 mm of the bifurcation or proximal origin of a segment; - Beyond 5 mm from the bifurcation or proximal origin of a segment.

The length of stenosis was based on the most proximal (first point) in a segment where a stenosis exceeded 10% and the most distal point (last point) in the segment where a stenosis exceeded 10%. If a stenosis spanned more than one segment then the measurement was only included to the beginning or end (boundary) of the segment being evaluated. If there was no stenosis of >=70% in a segment then the length was designated as 0.

Each segment was assessed for secondary signs of stenosis for diagnosis of clinically significant disease. The following indicators were considered for the MRA studies: - post-stenotic dilation or ulceration (segmental), - post-stenotic signal dropout, narrowing and intensity reduction, and - thrombus. Each of the three parameters were assessed as present or absent in the region distal to the stenosis. If they were found in any segment distal to the stenosis then they were assessed as present.

Each segment was assessed for secondary signs of stenosis for diagnosis of clinically significant disease. The following indicators were considered for the MRA studies: - post-stenotic dilation or ulceration (segmental), - post-stenotic signal dropout, narrowing and intensity reduction, and - thrombus. Each of the three parameters were assessed as present or absent in the region distal to the stenosis. If they were found in any segment distal to the stenosis then they were assessed as present. If there were tandem (serial) stenosis in a vessel then the secondary signs were assigned to the stenosis of >=70% that was proximal and closest in proximity to the secondary sign.

Diagnostic confidence was evaluated to determine the level of certainty that the blinded readers assigned to a diagnosis for each segment. This was defined as the degree of confidence that the information on the MRA images represented the true and complete clinical picture of a particular segment. The degree of confidence was rated on a 4-point scale: 1 = Not confident, 2 = Somewhat confident, 3 = Confident, and 4 = Very confident.

A measure of diagnostic value was the reduction in the number of additional diagnostic imaging studies recommended/ordered. The clinical investigators and the blinded readers were asked if they would have recommended an additional imaging study for each participant and was recorded.

An additional imaging study recommended was specified from the following list: Non-contrast MRA, Contrast-enhanced MRA, CTA, Ultrasound, Digital subtraction catheter angiogram (DSCA), and Nuclear medicine study.

An additional imaging study recommended was specified from the following list: Non-contrast MRA, Contrast-enhanced MRA, CTA, Ultrasound, Digital subtraction catheter angiogram (DSCA), and Nuclear medicine study.

An additional imaging study recommended was specified from the following list: Non-contrast MRA, Contrast-enhanced MRA, CTA, Ultrasound, Digital subtraction catheter angiogram (DSCA), and Nuclear medicine study.

An additional imaging study recommended was specified from the following list: Non-contrast MRA, Contrast-enhanced MRA, CTA, Ultrasound, Digital subtraction catheter angiogram (DSCA), and Nuclear medicine study.