Table 1:
Regression-derived effects of scan duration on various hemodynamic measurements
| Hemodynamic Measurement | Deconvolution Algorithm | Function Used for CBV Integration | t-statistic | Slopea | Potential Truncation Effectb | Lesion Reversal Frequency |
|---|---|---|---|---|---|---|
| CBVc | None | Concentration | 41.53 | 1.08/log10(s) | 47.6% | 37% (21/57) |
| sCBVr | sSVD | Response | 17.99 | 1.46/log10(s) | 64.2% | 35% (20/57) |
| oCBVr | oSVD | Response | 16.72 | 1.17/log10(s) | 51.4% | 46% (26/57) |
| sCBF | sSVD | NA | 9.62 | 0.09/log10(s) | 4.10% | 4% (2/57) |
| oCBF | oSVD | NA | 3.58 | 0.04/log10(s) | 1.96% | 2% (1/57) |
| sMTTc | sSVD | Concentration | 34.49 | 3.03/log10(s) | 133% | 47% (27/57) |
| sMTTr | sSVD | Response | 35.57 | 3.73/log10(s) | 164% | 28% (16/57) |
| oMTTc | oSVD | Concentration | 42.50 | 3.79/log10(s) | 166% | 54% (31/57) |
| oMTTr | oSVD | Response | 51.15 | 4.67/log10(s) | 205% | 39% (22/57) |
| sTmax | sSVD | NA | 25.91 | 14.10/log10(s) | 6.19 seconds | 44% (25/57) |
| oTmax | oSVD | NA | 28.62 | 18.2/log10(s) | 8.00 seconds | 42% (24/57) |
Note:—NA indicates not applicable.
a
The slopes of all 11 hemodynamic parameters with respect to the logarithm of scan duration were significantly greater than zero (P < .001). Therefore, t-statistics rather than P values are reported.
b
“Potential truncation effect” refers to the expected reduction in the calculated parameter value that would result from decreasing the scan duration from 110 seconds to 40 seconds postinjection. For example, if the CBVc value derived from a 110-second scan were 107.6% of normal, the expected CBVc using a 40-second scan would be 60.0% of normal.