Quantitative ultrasound imaging of healthy and reconstructed cleft lip: a feasibility study

To investigate the feasibility of echographic imaging of healthy and reconstructed cleft lip and to estimate tissue dimensions and normalized echo level.

Echographic images of the upper lip were made on three healthy subjects and two patients using a linear array transducer (7 to 11 MHz bandwidth) and a noncontact gel coupling. Tissue dimensions were measured using calipers. Echo levels were calibrated and were corrected for beam characteristics, gel path, and tissue attenuation using a tissue-mimicking phantom.

At the central position of the philtrum, mean thickness (SD) of lip loose connective tissue layer, orbicularis oris muscle, and dense connective layer was 4.0 (0.1) mm, 2.3 (0.7) mm, and 2.2 (0.7) mm, respectively, in healthy lip at rest; and 4.1 (0.9) mm, 3.8 (1.7) mm, and 2.6 (0.6) mm, respectively, in contracted lip. Mean (SD) echo level of muscle and dense connective tissue layer with respect to echo level of lip loose connective tissue layer was -19.3 (0.6) dB and -10.7 (4.0) dB, respectively, in relaxed condition and -20.7 (1.5) dB and -7.7 (2.3) dB, respectively, in contracted state. Color mode echo images were calculated, showing lip tissues in separate colors and highlighting details like discontinuity of the orbicularis oris muscle and presence of scar tissue.

Quantitative assessment of thickness and echo level of various lip tissues is feasible after proper echographic equipment calibration. Diagnostic potentials of this method for noninvasive evaluation of cleft lip reconstruction outcome are promising.