Table 3. Comparison of attenuation, noise, CNR, and SNR between the VMI reconstructions and M_0.5-C images.
| Parameters | 40 keV (95% CI) | 60 keV (95% CI) | 80 keV (95% CI) | 100 keV (95% CI) | M_0.5 (95% CI) |
|---|---|---|---|---|---|
| Popliteal artery | |||||
| Attenuation, HU | 1,218.88±265.09* (1,152.88, 1,285.09) | 589.51±107.94* (558.31, 613.84) | 322.13±63.34* (304.16, 336.31) | 206.03±36.67* (196.62, 215.44) | 451.88±103.07 (431.79, 484,06) |
| Noise, HU | 26.94±3.50* (26.06, 27.81) | 11.99±1.63 (11.71, 12.87) | 6.76±1.47* (6.38, 7.13) | 6.19±1.77* (5.75, 6.63) | 11.69±1.78 (11.02, 12.09) |
| SNR | 45.74±10.59 (43.09, 48.39) | 48.50±11.61* (45.59, 51.40) | 49.65±14.51* (46.02, 53.27) | 36.33±13.49 (32.96, 39.69) | 40.55±12.55 (37.96, 44.24) |
| CNR | 61.81±19.16* (57.02, 66.59) | 50.38±15.17* (46.49, 54.26) | 36.41±12.02 (33.26, 39.46) | 24.97±8.80* (22.77, 27.16) | 40.77 ±14.94 (36.95, 44.60) |
| Anterior tibial artery | |||||
| Attenuation, HU | 1,090.85±235.12* (1,032. 1,149.57) | 554.6 8±92.37* (527.13, 577.71) | 303.27±55.28* (289.35, 317.19) | 194.81±32.87* (186.60, 203.02) | 418.13±90.98 (396.19, 445.91) |
| Noise, HU | 26.74±4.67* (25.57, 27.91) | 12.52±2.14 (11.71, 13.10) | 7.19±2.05* (6.68, 7.73) | 5.59±2.13* (5.06, 6.12) | 12.58±2.08 (12.20, 13.64) |
| SNR | 41.83±11.11 (39.06, 44.61) | 43.16±11.08* (40.04, 45.34) | 45.05±13.76* (41.25, 48.31) | 41.64±21.93 (36.17, 47.12) | 36.71±11.16 (34.18, 39.75) |
| CNR | 54.86±16.98* (50.62, 59.10) | 46.87±13.2* (42.94, 49.48) | 33.91±10.36 (31.16, 36.48) | 23.09±7.51* (21.22, 24.97) | 37.68±13.38 (34.13, 41.23) |
| Posterior tibial artery | |||||
| Attenuation, HU | 1,090.53±254.31* (1,027.01, 1,154.06) | 565.48±99.98* (533.73, 589.61) | 302.47±64.60* (286.33, 318.61) | 192.8 2± 38.92* (183.10, 202.55) | 413.09± 93.10 (387.43, 438.75) |
| Noise, HU | 27.46±4.22* (26.41, 28.52) | 12.70±2.07 (12.01, 13.32) | 6.94±1.88* (6.45, 7.41) | 5.27±2.21* (4.71, 5.82) | 12.78±2.16 (12.10, 13.46) |
| SNR | 40.80±12.65 (37.64, 43.96) | 42.61±12.99* (39.36, 45.85) | 47.21±19.02* (42.13, 51.90) | 41.3±16.41 (37.20, 45.40) | 36.33±12.25 (33.75, 39.90) |
| CNR | 54.69±17.35* (50.36, 59.02), | 48.48±12.61* (44.96, 51.98) | 33.50±10.70 (30.59, 36.09) | 22.67±7.91* (20.69, 24.64) | 36.58±12.53 (33.53, 40.25) |
| Peroneal artery | |||||
| Attenuation, HU | 1,126.48±247.03* (1,064.77, 1,188.18) | 558.32±102.99* (528.05, 582.13) | 304.07±60.20* (289.11, 319.48) | 197.35±53.03* (184.11, 210.60) | 425.89±100.10 (402.67, 455.28) |
| Noise, HU | 27.58±4.55* (26.44, 28.71) | 12.78±2.07 (12.40, 13,71) | 6.91±1.43* (6.57, 7.30) | 5.47±2.49* (4.84, 6.09) | 12.89±2.01 (12.00, 13.21) |
| SNR | 42.14±11.32* (39.31, 44.97) | 43.34±11.31* (40.51, 46.16) | 45.73±13.22* (42.02, 48.42) | 40.26±16.80 (36.06, 44.45) | 35.57±10.04 (33.25, 38.28) |
| CNR | 56.46±16.37* (52.37, 60.55) | 48.38±12.51* (44.60, 51.25) | 33.69±10.25 (31.12, 36.24) | 23.09±8.52* (20.97, 25.22) | 37.12±12.23 (34.22, 40.64) |
| Muscle | |||||
| Attenuation, HU | 78.22±17.01* (73.97, 82.47) | 63.45±7.53* (61.43, 65.47) | 55.71±5.33 (54.43, 57.16) | 52.91±4.49* (51.78, 54.03) | 57.98±5.58 (56.44, 59.51) |
| Noise, HU | 19.04±2.92* (18.31, 19.76) | 10.68±1.73 (9.87, 10.94) | 7.60±1.40* (7.21, 7,92) | 6.44±1.36* (6.10, 6.78) | 9.98±1.80 (9.68, 10.77) |
| SNR | 4.21±1.17* (3.91, 4.50) | 5.96±1.29 (5.63, 6.28) | 7.61±1.67* (7.18, 8.02) | 8.59±2.06* (8.08, 9.11) | 6.17±1.26 (5.85, 6.48) |
Data are expressed as mean ± SD (95% CI). *, the difference was statistically significant between VMI reconstructions and M_0.5-C images. VMI, virtual monoenergetic imaging; M_0.5-C, 0.5 linear image blending image in arterial phase; keV, kiloelectron volt; SNR, signal-to-noise ratio; CNR, contrast-to-noise ratio; HU, Hounsfield unit.