The role of medical imaging in the identification and mineral -type characterization of canine urocystoliths.

摘要

Urocystoliths from 2041 dogs submitted to the University of Minnesota Urolith Center were evaluated visually for size spectrum, geologic shape and surface characteristics, and color. Characteristics were statistically compared to the mineral types (ammonium/sodium acid urate, calcium oxalate dihydrate, calcium oxalate monohydrate, calcium phosphate appatite, calcium hydrogen phosphate dihydrate, cystine, magnesium ammonium phosphate, silica). Relative breed (or breed-crosses) occurrence were statistically compared to the registrations from the American Kennel Club and accessions to the University of Minnesota Veterinary Teaching Hospital as an assessment of relative likelihood of urocystolith occurrence.;From the 2041 urocystolith database, a randomly selected subset of 437 cases was examined using small focal-spot, table top, and standard radiographic techniques (in air and in serial dilutions of iodinated radiographic contrast medium), and simulated survey radiography, pneumocystography, double contrast radiography and real-time ultrasonography in a bladder phantom. Effective atomic number was used for comparison of the relative radiopacities of the contrast medium dilutions to the urocystoliths.;Urocystolith detection accuracy was compared among the radiographic and ultrasonographic techniques. Survey radiographic techniques were roughly equal to 3.5 MHz ultrasonography, pneumocystographic techniques were roughly equal to 5.0 MHz ultrasonography, and double contrast techniques (using 200 mg iodine/ml) were roughly equal to 7.5 MHz ultrasonography. Contrast medium "adhesion" was identified on some urocystolith mineral types. It was determined that not all urocystoliths caused an acoustic shadow.;The research goal was to determine if urocystolith mineral type could be predicted using a combination of geographic region occurrence frequency, age, breed, gender and radiographic appearance. Multivariate discriminant analyses and resulting prediction equations calculated the relative likelihood of a specific mineral type for a canine patient. The combination of 200 mg iodine/ml double contrast cystogram and the nonimaging variables yielded an average mineral type prediction accuracy of 75.3% across mineral types (range 61.5--92.9%). The utility of the equation-based predictions were better than their mineral type prediction accuracy seemed because urocystoliths requiring medical versus surgical therapy were readily differentiated.