Characterisation of red and white thrombus by intravascular ultrasound using radiofrequency and videodensitometric data-based texture analysis.

Visual assessment of intravascular ultrasound (IVUS) video images cannot reliably identify thrombus. We examined if texture analysis of radiofrequency (r.f.) data or videodensitometric data (VD) could distinguish thrombi of different ages and cell compositions. Whole human blood (red clot = RC), platelet-rich plasma (white clot = WC) and plasma (n = 6/group) were imaged at 4 and 24 h with 30 MHz IVUS transducers. At 4 h, VD- and r.f.-based analyses revealed significant differences between RC and WC with variance (VD red 26.4 +/- 2.5, white 33.9 +/- 7.8; r.f. red 1.4 +/- 0.5, white 4.9 +/- 1.3), kurtosis (VD red 0.29 +/- 0.9, white 0.23 +/- 0.3) and skewness (VD red 0.23 +/- 0.13, white 0.35 +/- 0.52; r.f. red 0.06 +/- 0.01, white -0.06 +/- 0.05). Also mean grey-level from both data sets was higher in RC (VD 134.8 +/- 18.0; r.f. -13.3 +/- 1.2) than in WC (VD 105.3 +/- 17.4, r.f. 16.5 +/- 2.2) (p < 0.01). With increasing time, variance increased in WC (5.5 +/- 1.5 at 24 h) and decreased in RC (0.9 +/- 0.3.3 at 24 h). The more heterogeneous structure of WC may be distinguished from that of RC using texture analysis of either VD or r.f.-signals.