Article Figures & Data
Figures
- Fig 1.
A 78-year-old-female patient with symmetric infraclinoid aneurysms of the ICA. A, Volume-rendering of BSCTA displays both aneurysms (arrowhead: right aneurysm; arrow: left aneurysm). B and C, DSA confirms both aneurysms in size and configuration.
- Fig 2.
False-negative bone-subtraction CTA findings of an aneurysm of the right anterior cerebral artery in a 50-year-old woman. A, The right anterior oblique projection DSA shows a small broad-based aneurysm (arrow). B, On volume-rendering reconstruction, the aneurysm (arrow) appears fusiform. The white surface in the lower part of the image represents the bone-to-vessel boundary of the bone-removal processing.
- Fig 3.
False-positive bone-subtraction CTA findings in an aneurysm (2.5 mm) of the left middle cerebral artery distal to the trifurcation in a 50-year-old man with 2 aneurysms. A, Volume-rendering of bone-subtraction CTA depicts the aneurysm (anteroposterior view) that was missed by DSA. B, 3D-DSA image of the initially missed M2 MCA trifurcation aneurysm (left anterior oblique view) that was confirmed in retrospect.
- Fig 4.
Bland-Altman plots show the relationship between differences and means of DSA and BSCTA in aneurysm dome (A) and neck (B) measurements and dome/neck ratios (C). The black dotted line indicates the regression line of the differences. The 2 thin black lines represent the 95% confidence interval for the regression line of the differences. A, Bone subtraction CTA tends to overestimate aneurysm domes by 0.17 mm (95% CI, 0.04–0.39 mm) and has a mild trend toward higher values for dome diameters with larger values. The colored rectangular boxes highlight manual measurements with interpolation of DSA results because DSA millimeter calibrations were not transferred with the other DSA data. The outlier case is 1 large 14.0-mm aneurysm that was overestimated by 6.0 mm and belongs to the manually calculated measurements. B, Bone-subtraction CTA measurements of the aneurysm neck are in good agreement with DSA (0 ± 1.96 mm). Outlier cases are small 2.5- and 2.7-mm aneurysms that were underestimated by −1.5 and −1.2 mm. The third outlier was a 2.7-mm aneurysm that was overestimated by 1.5 mm. C, Bone-subtraction CTA slightly overestimates dome/neck ratios compared with DSA (mean, 0.04; 95% CI, 0.08–0.16). Four of the 6 outliers belong to the manually calculated DSA measurements (colored rectangular boxes).
Tables
Scan Parameters NECT BSCTA Low-Dose CT CTA Tube voltage (kV) 120 100 100 Tube current (effective mAs) 320 70 140 Rotation time (sec) 1.0 0.5 0.5 Section acquisition (mm) 16 × 1.5 16 × 0.75 16 × 0.75 Table speed/rotation (mm) 13.2 13.8 13.8 Recon. section thickness (mm) 8 1.0 1.0 Reconstruction increment (mm) 8 0.5 0.5 Automated exposure control Off Off Off Contrast material (mL)a NA NA 80 Injection rate (mL/s) NA NA 4–5 Note:—Recon. indicates reconstruction; NA, not applicable.
↵a Iopromide, Ultravist, 370 mg I/mL; Bayer HealthCare, Berlin, Germany.
Location Size Categories Small (≤3.0 mm) Medium (3.1–5.0 mm) Large (>5 mm) ICA Infraclinoid 0 0 1 Ophthalmic 0 0 1 PcomA 1 6 2 Carotid-T 1 0 0 ACA A1 0 1 0 A1/A2 5 16 7 A2 and A3 3a 0 3 MCA Trifurcation 4b 8 2 PCA 0 1 1 BA Oral 1 0 3 VA PICA 0 3 2 V4 0 0 1 All 15 35 23 Note:—PcomA indicates posterior communicating artery; Carotid–T, intracranial ICA bifurcation; ACA, anterior cerebral artery; A1, A2, A3, segments of the ACA; PCA, posterior cerebral artery; BA, basilar artery; VA, vertebral artery; PICA, posterior inferior cerebellar artery; V4, distal segment of VA.
↵a One aneurysm missed by bone-subtraction CTA.
↵b One aneurysm missed by DSA but detected by bone-subtraction CTA.
TP (No.) TN (No.) FP (No.) FN (No.) Sensitivity (%) (No.) Specificity (%) (No.) PPV (%) (No.) NPV (%) (No.) Accuracy (%) (No.) Per patient 70 45 0 1 99 (70/71) 100 (45/45) 100 (70/70) 98 (45/46) 99 (115/116) 95% CI 92–100 92–100 95–100 89–100 95–100 Per aneurysm 73 45 1 1 99 (73/74) 98 (45/46) 99 (73/74) 98 (45/46) 98 (118/120) 95% CI 93–100 89–100 93–100 89–100 94–100 Note:—TP indicates true-positive; TN, true-negative; FP, false-positive; FN, false-negative; PPV, positive predictive value; NPV, negative predictive value.
Diameter TP (No.) TN (No.) FP (No.) FN (No.) Sensitivity (%) (No.) Specificity (%) (No.) PPV (%) (No.) NPV (%) (No.) Accuracy (%) (No.) >5.0 mm 23 45 0 0 100 (23/23) 100 (45/45) 100 (23/23) 100 (45/45) 100 (68/68) 95 % CI 86–100 92–100 86–100 92–100 95–100 3.1–5.0 mm 35 45 0 0 100 (35/35) 100 (45/44) 100 (35/35) 100 (45/45) 100 (80/80) 95 % CI 90–100 92–100 90–100 92–100 94–100 ≤3.0 mm 16 45 1 1 94 (16/17) 98 (45/46) 94 (16/17) 98 (45/46) 97 (61/63) 95 % CI 73–99 89–100 73–99 89–100 89–100 Note:—TP indicates true-positive; TN, true-negative; FP, false-positive; FN, false-negative; PPV, positive predictive value; NPV, negative predictive value.
Method Intubated Patients Motion Artifacts Aneurysm Detection Mild Moderate Severe FN FP DSA 1 15 6 7 0 0 CT 0 1 1 0 0 0 Note:—.FP indicates false-positive; FN, false-negative.
