Comparison of standard and second harmonic B-mode sonography in the detection of segmental renal infarction with sonographic contrast in a rabbit model

This study compares contrast-enhanced fundamental and second harmonic B-mod e sonography using a rabbit renal infarct model. Segmental renal infarction s were produced in 13 rabbits by embolizing a 0.7 mm bead into the renal ar tery 1 day prior to imaging. An ultrasonographic unit equipped with an L10- 5 transducer and second harmonic imaging capability was used. Real-time rec ordings were made during the injection of 0.5 ml of an experimental formula tion of a perfluorohexane vapor-stabilized microbubble (AF0145) given into the ear vein, and the imaging technique alternated between standard and har monic imaging every 20 s. Each rabbit received two injections 1 h apart. To control for the effect of peak bolus enhancement, the initial imaging tech nique used for the first injection was randomized, and the other technique was used initially for the second injection. The videointensity difference between the infarcted and the normal cortex was then calculated and evaluat ed as a function of time. The infarcted segment could not be seen before ad ministration of contrast agent with either technique. Although the infarcti on could be seen after injection of contrast agent with either technique, i mage contrast and contrast duration were nearly 75% greater for the harmoni c technique than for the standard technique. AF0145 allows the visualizatio n of segmental renal infarction on standard B-mode imaging. The second harm onic B-mode technique significantly increases image contrast and contrast d uration.