Initial evaluation of virtual histology ultrasonographic techniques applied to a case of renal transplant

Abstract

Ultrasound virtual histology (USVH) techniques have been applied to B-mode images of coronary, carotid, and peripheral arteries and to deep venous thrombosis. We expanded USVH to evaluate the kidney. This case reports USVH applied to a renal transplant. A 29-year-old male with chronic renal insufficiency received his sister’s kidney. B-mode images were recorded during (a) routine 1-day posttransplant US examination; and (b) a second follow-up US performed 6 days later once the patient became symptomatic. B-mode brightness of each pixel was classified into 14 ranges. USVH demonstrated high echogenicity of the kidney on day 1; gray scale median, GSM = 60, was elevated when compared with average GSM = 37 for normal, young kidneys. Muscle-like plus fiber-like echoes, 46 + 10 = 56%, were higher than expected for a normal young kidney, 34 + 3 = 37% (p = 0.0071). GSM increased to 88 on day 7. Normal resistivity indices (RI) on day 1 increased from 0.66–0.70 to 0.81–0.90. Biopsy confirmed kidney rejection. These findings confirmed the concepts that tissue changed before hemodynamics were altered and signs and symptoms developed. Ultrasonographic tissue characterization, particularly of transplanted kidneys, deserves extensive investigation focused on early changes that precede present-day detectable abnormalities.