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Research ArticleBRAIN

Dynamic Perfusion CT: Optimizing the Temporal Resolution and Contrast Volume for Calculation of Perfusion CT Parameters in Stroke Patients

Max Wintermark, Wade S. Smith, Nerissa U. Ko, Marcel Quist, Pierre Schnyder and William P. Dillon
American Journal of Neuroradiology May 2004, 25 (5) 720-729;

Article Figures & Data

Figures

  • Fig 1.
    Fig 1.

    Time-enhancement curves for four temporal sampling intervals: 0.5 second, 1 second, 2 seconds, and 4 seconds. The area under the curve is approximately the same for the first three sampling intervals. For the interval of 4 seconds, however, the peak points of the curve are undersampled (circle), resulting in a reduction in the area under the curve. This would result in significant errors in the calculation of rCBV.

  • Fig 2.
    Fig 2.

    Sample PCT datasets in one patient from the 40-mL group. rCBF, rCBV, MTT, and TTP maps are displayed for six sampling intervals: 1, 2, 3, 4, 5, and 6 seconds. Sparsing sampling results in overestimation of rCBF, rCBV, and TTP values and in underestimation of MTT values.

  • Fig 3.
    Fig 3.

    Time to entrance of the contrast material into the arterial pixel and time to exit of the contrast material in the venous and ischemic pixels, displayed for the four bolus volume groups. Boxes represent the mean ± 1 SD, and vertical lines indicate the mean ± 2 SDs. Time to arterial entrance does not vary with bolus volumes. However, time to exit does increase with increasing bolus volumes, resulting in longer acquisition times required for larger bolus volumes.

Tables

  • TABLE 1:

    PCT rCBF values for the healthy hemisphere

    GroupSampling Interval
    0.5 second1 second*2 seconds3 seconds4 seconds5 seconds6 seconds
    1 (30 mL)
     Mean ± SD45.0 ± 3.641.7 ± 3.743.3 ± 3.752.9 ± 4.671.1 ± 5.891.8 ± 15.5295.1 ± 87.0
     Range−2.9% to +10.7%NA−4.9% to +8.4%+2.6% to +28.3%+47.0% to +139.4%+84.2% to +170.1%+379.7% to +748.2%
     P value.038NA.239.001<.001<.001<.001
    2 (40 mL)
     Mean ± SD43.5 ± 3.843.1 ± 3.941.6 ± 3.947.0 ± 3.553.2 ± 6.879.4 ± 13.994.0 ± 24.3
     Range−5.9% to +7.9%NA−7.6% to +6.1%−2.8% to +9.6%+24.2% to +60.4%+59.8% to +113.0%+107.3% to +277.5%
     P value.759NA.344.052<.001<.001<.001
    3 (50 mL)
     Mean ± SD45.1 ± 3.043.7 ± 3.342.1 ± 3.544.7 ± 4.455.1 ± 5.464.8 ± 8.873.6 ± 17.5
     Range−4.0% to +7.2%NA−6.9% to +6.3%−5.4% to +8.2%+12.3% to +49.1%+44.9% to +81.5%+79.4% to +108.1%
     P value.276NA.248.494.001.001.001
    4 (60 mL)
     Mean ± SD45.7 ± 3.844.2 ± 3.741.6 ± 3.642.5 ± 3.847.6 ± 4.654.6 ± 6.460.4 ± 9.3
     Range−4.8% to +7.4%NA−8.0% to +5.7%−7.4% to +5.5%−4.0% to +11.0%+8.3% to +39.4%+22.7% to +47.7%
     P value.306NA.112.252.012.004.001

    • Note.—No significant difference (P = .886, Kruskal-Wallis) was identified among the four groups for rCBF values obtained with an interval of 1 second. Range indicates the overestimation or underestimation compared with the reference. Values in boldface indicate the temporal sampling interval thresholds beyond which rCBF values were significantly overestimated.

    • * Reference for Wilcoxon (Mann-Whitney) tests performed in each group. NA indicates not applicable.

  • TABLE 2:

    PCT rCBF values for the ischemic area

    GroupSampling Interval
    0.5 second1 second*2 seconds3 seconds4 seconds5 seconds6 seconds
    1 (30 mL)
     Mean ± SD10.1 ± 4.711.7 ± 6.012.3 ± 6.124.4 ± 12.154.2 ± 27.4102.2 ± 50.2238.3 ± 188.0
     Range−9.2% to +17.3%NA−10.0% to +18.4%+18.1% to +126.3%+151.1% to +402.4%+513.7% to +991.1%+1183.9% to +2561.1%
     P value.450NA.803.004<.001<.001<.001
    2 (40 mL)
     Mean ± SD11.4 ± 5.112.9 ± 4.912.0 ± 5.113.8 ± 6.347.1 ± 23.385.9 ± 35.9194.8 ± 137.9
     Range−10.0% to +16.2%NA−9.4% to +17.4%−8.9% to +18.2%+115.1% to +319.9%+392.6% to +718.7%+946.0% to +1945.8%
     P value.958NA.653.683<.001<.001<.001
    3 (50 mL)
     Mean ± SD9.8 ± 4.911.3 ± 4.59.6 ± 4.111.4 ± 5.325.6 ± 12.247.1 ± 20.760.3 ± 31.8
     Range−10.6% to +18.1%NA−10.0% to +18.8%−9.5% to +19.8%+55.8% to +171.1%+251.6% to +439.4%+380.4% to +795.1%
     P value.494NA.393.939.001<.001<.001
    4 (60 mL)
     Mean ± SD9.6 ± 4.49.7 ± 4.49.3 ± 4.09.2 ± 4.310.6 ± 5.723.4 ± 12.029.6 ± 19.0
     Range−9.7% to +19.8%NA−9.6% to +19.2%−10.0% to +17.3%−8.9% to +18.6%+118.9% to +286.7%+136.9% to +324.7%
     P value.970NA.777.776.216.001.001

    • Note.—No significant difference (P = .166, Kruskal-Wallis) was identified among the four groups for rCBF values obtained with an interval of 1 second. Range indicates the overestimation or underestimation compared with the reference. Values in boldface indicate the temporal sampling interval thresholds beyond which rCBF values were significantly overestimated.

    • * Reference for Wilcoxon (Mann-Whitney) tests performed in each group. NA indicates not applicable.

  • TABLE 3:

    PCT rCBV values for the healthy hemisphere

    GroupSampling Interval
    0.5 second1 second*2 seconds3 seconds4 seconds5 seconds6 seconds
    1 (30 mL)
     Mean ± SD3.0 ± 0.42.8 ± 0.52.9 ± 0.43.0 ± 0.53.9 ± 0.74.8 ± 1.314.9 ± 4.8
     Range−6.5% to +8.0%NA−7.5% to +6.8%−6.2% to +9.2%+16.8% to +59.4%+52.5% to +99.1%+136.0% to +628.3%
     P value.213NA.700.124.004.002<.001
    2 (40 mL)
     Mean ± SD3.1 ± 0.53.0 ± 0.42.8 ± 0.43.2 ± 0.53.2 ± 0.64.3 ± 0.74.9 ± 1.2
     Range−5.8% to +7.1%NA−8.3% to +4.9%−5.8% to +7.4%−4.2% to +9.6%+18.0% to +69.3%+42.0% to +278.2%
     P value.225NA.595.0196.024<.001<.001
    3 (50 mL)
     Mean ± SD3.2 ± 0.43.1 ± 0.52.9 ± 0.43.0 ± 0.33.3 ± 0.53.9 ± 0.64.1 ± 0.8
     Range−7.2% to +6.2%NA−9.0% to +7.9%−7.4% to +8.3%−5.3% to +8.3%+7.9% to +41.6%+22.3% to +66.6%
     P value.708NA.243.494.139.008.007
    4 (60 mL)
     Mean ± SD3.2 ± 0.43.1 ± 0.52.9 ± 0.42.9 ± 0.33.2 ± 0.43.3 ± 0.43.7 ± 0.5
     Range−6.5% to +8.0%NA−8.3% to +10.2%−8.1% to +9.0%−5.8% to +7.6%−4.8% to +9.6%+8.5% to +32.6%
     P value.230NA.650.420.324.038.007

    • Note.—No significant difference (P = .908, Kruskal-Wallis) was identified among the four groups for rCBV values obtained with an interval of 1 second. Range indicates the overestimation or underestimation compared with the reference. Values in boldface indicate the temporal sampling interval thresholds beyond which rCBV values were significantly overestimated.

    • * Reference for Wilcoxon (Mann-Whitney) tests performed in each group. NA indicates not applicable.

  • TABLE 4:

    PCT rCBV values for the ischemic area

    GroupSampling Interval
    0.5 second1 second*2 seconds3 seconds4 seconds5 seconds6 seconds
    1 (30 mL)
     Mean ± SD1.0 ± 0.41.2 ± 0.51.1 ± 0.52.2 ± 0.43.7 ± 0.65.4 ± 1.512.1 ± 4.8
     Range−14.4% to +8.6%NA−10.2% to +8.5%+33.7% to +111.2%+104.2% to +335.0%+222.0% to +447.4%+630.5% to +1275.2%
     P value.018NA.519<.001<.001<.001<.001
    2 (40 mL)
     Mean ± SD1.1 ± 0.31.2 ± 0.41.1 ± 0.41.2 ± 0.43.2 ± 0.55.1 ± 0.910.9 ± 2.8
     Range−13.0% to +13.7%NA−10.5% to +8.1%−10.6% to +10.2%+53.0% to +220.5%+197.3% to +427.3%+510.8% to +937.3%
     P value.156NA.076.765<.001<.001<.001
    3 (50 mL)
     Mean ± SD0.9 ± 0.51.1 ± 0.31.0 ± 0.31.1 ± 0.62.3 ± 0.33.4 ± 0.54.3 ± 0.9
     Range−12.4% to +10.6%NA−8.1% to +8.5%−10.5% to +9.4%+33.5% to +122.3%+95.5% to +323.7%+249.7% to +435.4%
     P value.021NA.033.603<.001<.001<.001
    4 (60 mL)
     Mean ± SD1.0 ± 0.41.0 ± 0.50.9 ± 0.60.9 ± 0.41.1 ± 0.32.0 ± 0.32.4 ± 0.4
     Range−11.3% to +10.4%NA−7.2% to +7.2%−9.5% to +9.3%−11.8% to +12.1%+23.3% to +155.9%+97.9% to +228.1%
     P value.614NA.164.172.014<.001<.001

    • Note.—No significant difference (P = .556, Kruskal-Wallis) was identified among the four groups for rCBV values obtained with an interval of 1 second. Range indicates the overestimation or underestimation compared with the reference. Values in boldface indicate the temporal sampling interval thresholds beyond which rCBV values were significantly overestimated.

    • * Reference for Wilcoxon (Mann-Whitney) tests performed in each group. NA indicates not applicable.

  • TABLE 5:

    PCT MTT values for the healthy hemisphere

    GroupSampling Interval
    0.5 second1 second*2 seconds3 seconds4 seconds5 seconds6 seconds
    1 (30 mL)
     Mean ± SD4.0 ± 0.44.1 ± 0.54.0 ± 0.43.8 ± 0.53.3 ± 0.43.1 ± 0.43.0 ± 0.6
     Range−11.4% to +8.0%NA−10.0% to +9.8%−11.1% to +4.1%−6.2% to −33.6%−3.1% to −40.3%−27.0% to −53.5%
     P value.789NA.594.016.008.006.002
    2 (40 mL)
     Mean ± SD4.3 ± 0.54.2 ± 0.44.1 ± 0.44.0 ± 0.53.9 ± 0.53.4 ± 0.53.1 ± 0.6
     Range−6.7% to +10.1%NA−10.5% to +8.2%−8.3% to +7.8%−10.6% to +7.3%−7.4% to −28.1%−15.7% to −36.7%
     P value.202NA.889.803.169.007.002
    3 (50 mL)
     Mean ± SD4.2 ± 0.34.1 ± 0.54.1 ± 0.64.0 ± 0.43.9 ± 0.43.8 ± 0.53.4 ± 0.4
     Range−9.8% to +9.2%NA−9.5% to +8.6%−9.9% to +7.0%−10.6% to +2.8%−11.1% to +7.0%−9.9% to −28.3%
     P value0.783NA.485.256.043.013.009
    4 (60 mL)
     Mean ± SD4.1 ± 0.54.0 ± 0.54.2 ± 0.64.0 ± 0.54.0 ± 0.33.8 ± 0.43.7 ± 0.5
     Range−9.2% to +12.4%NA−8.3% to +10.1%−10.5% to +9.1%−10.7% to +9.5%−10.6% to +8.6%−10.5% to +8.5%
     P value.487NA.341.873.306.129.118

    • Note.—No significant difference (P = .556, Kruskal-Wallis) was identified among the four groups for MTT values obtained with an interval of 1 second. Range indicates the overestimation or underestimation compared with the reference. Values in boldface indicate the temporal sampling interval thresholds beyond which MTT values were significantly underestimated.

    • * Reference for Wilcoxon (Mann-Whitney) tests performed in each group. NA indicates not applicable.

  • TABLE 6:

    PCT MTT values for the ischemic area

    GroupSampling Interval
    0.5 second1 second*2 seconds3 seconds4 seconds5 seconds6 seconds
    1 (30 mL)
     Mean ± SD5.8 ± 0.65.9 ± 0.75.6 ± 0.75.4 ± 0.64.1 ± 0.63.2 ± 0.63.1 ± 0.6
     Range−16.0% to +10.5%NA−17.6% to +7.8%−13.3% to +16.3%−13.6% to −44.3%−32.1% to −67.5%−42.4% to −75.2%
     P value.634NA.168.099.009.002.002
    2 (40 mL)
     Mean ± SD6.0 ± 0.75.8 ± 0.85.6 ± 0.75.4 ± 0.64.1 ± 0.53.5 ± 0.53.4 ± 0.5
     Range−9.2% to +18.1%NA−18.7% to +9.3%−17.6% to +7.3%−9.8% to −36.2%−26.3% to −60.5%−37.9% to −50.5%
     P value.205NA.623.277.004.0020.002
    3 (50 mL)
     Mean ± SD5.8 ± 0.65.9 ± 0.96.0 ± 0.65.7 ± 0.75.3 ± 0.74.3 ± 0.64.3 ± 0.6
     Range−17.1% to +16.5%NA−11.8% to +19.7%−18.2% to +15.5%−22.5% to +8.9%−12.1% to −43.2%−28.1% to −36.0%
     P value.611NA.652.435.057.007.006
    4 (60 mL)
     Mean ± SD6.1 ± 0.86.1 ± 0.85.9 ± 0.66.0 ± 0.75.6 ± 0.75.5 ± 0.64.8 ± 0.6
     Range−19.6% to +11.6%NA−19.5% to +12.3%−18.4% to +12.4%−17.7% to +9.5%−16.1% to +10.35%−13.0% to −33.1%
     P value.677NA.528.649.283.017.008

    • Note.—No significant difference (P = .108, Kruskal-Wallis) was identified among the four groups for MTT values obtained with an interval of 1 second. Range indicates the overestimation or underestimation compared with the reference. Values in boldface indicate the temporal sampling interval thresholds beyond which MTT values were significantly underestimated.

    • * Reference for Wilcoxon (Mann-Whitney) tests performed in each group. NA indicates not applicable.

  • TABLE 7:

    Thresholds beyond which PCT results were significantly different from reference results

    Value and RegionTemporal Sampling Interval (seconds)
    Group 1 (30 mL)Group 2 (40 mL)Group 3 (50 mL)Group 4 (60 mL)
    rCBF
     Healthy hemisphere2334
     Cortical gray matter3345
     White matter2334
     Caudate nucleus3445
     Lenticular nucleus2344
     Ischemic area2334
     Ischemic/healthy ratio2334
    rCBV
     Healthy hemisphere3445
     Cortical gray matter3456
     White matter2334
     Caudate nucleus3345
     Lenticular nucleus3345
     Ischemic area2334
     Ischemic/healthy ratio2334
    MTT
     Healthy hemisphere3456
     Cortical gray matter4556
     White matter4455
     Caudate nucleus3456
     Lenticular nucleus3446
     Ischemic area3345
     Ischemic/healthy ratio3344
    TTP
     Healthy hemisphere3456
     Cortical gray matter4566
     White matter3456
     Caudate nucleus2345
     Lenticular nucleus2445
     Ischemic area2345
     Ischemic/healthy ratio2334
    Global2334

    • Note.—Reference results were calculated from the raw acquisition PCT series (temporal sampling interval of 1 second). The final global threshold for each volume was defined as the minimum temporal sampling interval identified as accurate for any of the four parametric PCT results in any region.

  • TABLE 8:

    Imaging protocols for acceptable PCT results

    Bolus (mL)No. of BolusesTotal (mL)Scanning Duration (seconds)Temporal Sampling Interval (seconds)Images per Series (per section)PCT TechniqueMDCT Spatial Coverage (cm)kVpmAsmSvDose-Coverage RatioImage-Quality Ratio
    3026036219Cine4801201.2450.3110.645
    3039036219Cine6801201.8670.3110.645
    4028042315Cine4801200.9830.2460.712
    50210042315Cine4801200.9830.2460.767
    6016048413Toggling-table4801200.8520.2130.850

    • Note.—Parameters in boldface indicate the recommended protocols with optimal dose-coverage ratios.

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Dynamic Perfusion CT: Optimizing the Temporal Resolution and Contrast Volume for Calculation of Perfusion CT Parameters in Stroke Patients
Max Wintermark, Wade S. Smith, Nerissa U. Ko, Marcel Quist, Pierre Schnyder, William P. Dillon
American Journal of Neuroradiology May 2004, 25 (5) 720-729;
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