Article Figures & Data
Figures
- FIG 1.
Flow chart of patients included in the diagnostic accuracy study.
- FIG 2.
Mean flow velocities for patients with and without vasospasm, defined as 33% (A), 50% (B), and 66% (C) vessel narrowing. MFV thresholds for anterior and posterior circulation vessels are shown (dashed lines). Note that for all individual arterial segments, MFVs were significantly higher for spastic vessels. Four asterisks indicate P < .0001; 2 asterisks, P < .01; 1 asterisk, P < .05. Error bars represent 95% confidence intervals.
- FIG 3.
Sensitivity, specificity, and the Youden number at various possible mean flow velocity cutoffs for anterior circulation arterial segments. This data-driven method of analysis shows that the best MFV cutoff is close to 160 cm/s. Data for posterior circulation segments are not shown.
- FIG 4.
Per-patient analysis of the diagnostic accuracy of TCD. Distributions of the maximal mean flow velocity found in any segment of the anterior circulation with or without vasospasm according to thresholds of 33% (A), 50% (B), and C) 66%. The 80% sensitivity line is labeled. Corresponding ROC curves are presented in A’, B’, and C’. Note the large amount of overlap of the curves despite acceptable areas under the curve (AUCs).
Tables
- Table 1:
Per-arterial segment TCD MFVs corresponding to Youden index optimizing sensitivity and specificity in detecting 50% vasospasm
MFV Threshold (cm/s) Sensitivity (95% CI) Specificity (95% CI) AUC (95%CI) Right ICA 154 0.86 (0.56–0.98) 0.86 (0.81–0.90) 0.88 (0.81–0.95) Left ICA 109 1.0 (0.68–1.0) 0.69 (0.63–0.76) 0.90 (0.84–0.96) Right M1 157 0.73 (0.56–0.90) 0.82 (0.76–0.87) 0.84 (0.75–0.92) Left M1 124 0.92 (0.73–0.99) 0.65 (0.58–0.72) 0.85 (0.78–0.91) Basilar artery 98 0.75 (0.51–0.81) 0.81 (0.76–0.87) 0.84 (0.73–0.95) Note:—AUC indicates area under the curve.
- Table 2:
Per-patient TCD MFV thresholds for various minimal sensitivities in detecting 50% vasospasm
Minimum Sensitivity Predefined MFV Threshold (cm/s)a ICA or M1 Basilar Artery Sensitivity (95% CI) Specificity (95% CI) 80% >164 >80 0.86 (0.72–0.94) 0.64 (0.56–0.71) 85% >160 >61 0.90 (0.77–0.96) 0.48 (0.40–0.56) 90% >126 >60 0.94 (0.82–0.98) 0.37 (0.30–0.45) 95% >95 >56 0.96 (0.85–0.99) 0.24 (0.18–0.31) ↵a Severe vasospasm was determined when 1 threshold was exceeded.
