Pilot study using high-frequency diagnostic ultrasound to assess surgical wounds in renal transplant patients

The majority of renal transplant patients will sustain at least one acute rejection episode during the first 4 months, following transplantation. Clinical rejection is rarely an all-or-nothing reaction, and the first episode seldom progresses to complete renal destruction. The functional changes induced by rejection appear to be in large part reversible; therefore the recognition and treatment of the rejection episode, before the development of severe renal damage, are of extreme importance.

This pilot study describes a technique of non-invasive wound assessment used to monitor 14 transplant patients, over a 3 week post-operative period. The technique involved the use of 20 MHz diagnostic ultrasound, in conjunction with fractal image analysis. Ultrasound scans of both wounded and adjacent uninjured tissue were taken 5, 7, 11, 14 and 21 days post-surgery.

When patients were divided into those who experienced allograft rejection and those who did not, a distinct trend appeared. In those who did not reject, the fractal signature of the wound progressed towards that of normal tissue in a linear fashion. In patients that did reject, the fractal signature initially progressed towards normal until day 11, then changed direction moving away from normal, between days 11 and 14. The patients experiencing allograft rejection were clinically diagnosed around a mean time of 14 days post-surgery. It is therefore possible that this shift in fractal signature may correlate with graft rejection.

The results of this pilot study indicate that high frequency diagnostic ultrasound, coupled with appropriate image analysis, may be a useful adjunct to renal function assessment.