High-frequency ultrasound measurement of patch test reactions

53 patients who produced 34 positive patch test reactions (+/- 15, +10, ++4, +++5) had their reactions read by a high-frequency pulsed ultrasonic (A-scan) dermal depth detector with a resolution of 0.05 mm. The positive reactions were compared with both random and regional controls. The machine could not differentiate between + or +/- reactions from the control readings. However, for 75% of ++ cases and 80% of +++ cases, a significant change was confirmed by the detector. It is concluded that the high-frequency ultrasound method is of little use in confirming or quantifying of positive patch test results.