Dual-Layer Detector Cone-Beam CT Angiography for Stroke Assessment: First-in-Human Results (the Next Generation X-ray Imaging System Trial)

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FIG 1.
Of 28 consecutively enrolled patients, 5 had no in-house CTA and 2 had subcutaneous IV contrast media injection during the DL-CBCTA scan. Two patients were imaged twice with DL-CBCTA, and for those, the results from both scans were averaged. Consequently, 21 complete and matched DL-CBCTA and CTA image sets from 21 patients were included.
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FIG 2.
DL-CBCTA 70-keV images (upper row) and CTA (lower row) with MIP 35-mm section thickness. A and B, Acceptable-quality DL-CBCTA scans. C and D, Typical scans in the data set affected by motion artifacts. Lower row (E–H) shows the corresponding CTA. Note that images F, G, and H show a right-sided MCA occlusion, which have been resolved at the time for DL-CBCTA imaging. Only the arterial anatomy in the unaffected hemisphere was evaluated in this study.

Table 1:

Scan details

	Canon Aquilion ONE	Philips IQon	Prototype DL-CBCT
Tube (kV)	100	120	120
Tube current (mAs/mA) (average)	196 (Auto-modulation)	114 (Auto-modulation)	310
Scan time/rotation time (sec)	3.3/0.5 (Full rotation)	2.5/0.3 (Full rotation)	20.0/20.0 (200° rotation)
Nominal beam width (mm)	80 × 0.500	64 × 0.625	194.700
Pitch factor	0.813	0.671	NA
Display FOV coronal × sagittal × axial (mm³)	210.9 × 210.9 × 160.0	210.0 × 210.0 × 160.0	251.8 × 251.8 × 194.7
Section thickness (mm)	0.50	0.67	0.66
Matrix size	512 × 512	512 × 512	384 × 384
Reconstruction kernel	FC43	Filter UA	Ståhl et al^{15^a}
Reconstruction algorithm	AIDR 3D eStandard	iDose⁴ level 4	Ståhl et al^{15^a}
Avg CTDIvol (16-cm phantom)	20.0 mGy	21.3 mGy	NA
Air kerma (in an 18-cm water phantom)^{^b}	NA	NA	57.6 mGy
MTF^{^c}	50%: 3.78	50%: 3.46	50%: 3.57
	10%: 6.57	10%: 6.65	10%: 6.04

Note:—CTDIvol indicates volume CT dose index; MTF, modulation transfer function; NA, not applicable.
↵a Details of the prototype algorithm are described in Ståhl et al.¹⁵
↵b Air kerma in an 18-cm diameter plastic water phantom at the center of the scan length, measured in accordance with American Association of Physicists in Medicine Task Group Report 111.²⁶
↵c Generated from consecutive scans of the upper bead of a Catphan CTP528 module (The Phantom Laboratory).

Table 2:

Arterial segments

Note:—Lenticulostriate indicates lenticulostriate artery perforators; Vertebral, intracranial vertebral artery; Basilar perforators, basilar artery perforating branches; SCA, superior cerebellar artery.

Table 3:

Vessel visibility^{^a}

	Powered Data Set	Powered Subset	Thrombectomy Data Set	Thrombectomy Subset
Patients	21	12	21	12
Segments rated	231	132	231	132
Majority	0.77 (0.70)	0.98 (0.93)^{^b}	0.77 (0.71)	0.98 (0.93)^{^b}
Reader 1	0.65 (0.58)	0.88 (0.80)^{^b}	0.67 (0.60)	0.91 (0.84)^{^b}
Reader 2	0.90 (0.84)^{^b}	0.98 (0.93)^{^b}	0.89 (0.83)^{^b}	0.98 (0.93)^{^b}
Reader 3	0.60 (0.53)	0.78 (0.69)	0.68 (0.61)	0.88 (0.80)^{^b}

↵a Proportion of DL-CBCTA arterial segment visibility rated equal or superior to CTA. The data set (21 patients) includes all scans; the subset (12 patients) excluded inferior scans. The 98.75% CI of the 1-sided lower performance boundary is in parentheses (lower boundary is defined as 80% rated equal or superior).
↵b Statistically significant result.

Table 4:

Artifacts^{^a}

	Powered Data Set	Powered Subset	Thrombectomy Data Set	Thrombectomy Subset
Patients	21	12	21	12
Segments rated	231	132	231	132
Majority	0.41 (0.34)	0.63 (0.53)	0.55 (0.48)	0.81 (0.72)
Reader 1	0.42 (0.35)	0.68 (0.58)	0.54 (0.46)	0.85 (0.77)
Reader 2	0.58 (0.50)	0.66 (0.56)	0.65 (0.58)	0.74 (0.64)
Reader 3	0.36 (0.29)	0.55 (0.44)	0.52 (0.44)	0.73 (0.63)

↵a Proportion of DL-CBCTA arterial segment artifacts rated equal or superior to CTA. Data set (21 patients) includes all scans; subset (12 patients) excluded inferior scans. The 98.75% CI of the 1-sided lower performance boundary is in parentheses (lower boundary is defined as 80% rated equal or superior).