Contrast medium-related artifacts observed during in vitro radiographic characterization of urocystolith mineral composition

Nine pure mineral types of canine uroliths (bladder or urethral origin only ) mere exposed to sequential increasing concentrations of iodinated, radiog raphic contrast medium in petri dishes. The uroliths studied were those com posed of 100% magnesium ammonium phosphate, calcium oxalate monohydrate, ca lcium oxalate dihydrate, calcium phosphate appatite, and calcium hydrogen p hosphate dihydrate (Brushite), ammonium acid urate, sodium acid urate, cyst ine, and silica, Two phenomena were observed. First, there was a tendency f or selected urocystoliths to undergo radiopacity augmentation beyond that e xpected for just contrast medium superimposition. This was termed, contrast medium adhesion, which persisted despite repeated mashing of the urocystol iths, Second, there was a tendency for bubbles to form on or near selected urocystolith chemical types. These observations prompted careful scrutiny f or their occurrence in subsequent clinical simulation of radiographic proce dures using these same urocystoliths in a urinary bladder phantom, Imaging techniques simulated were survey radiography, pneumocystography, double con trast cystography (two iodine concentrations). The contrast medium adhesion occurrence found in the petri dish studies was compared to urocystolith mi neral type. Similar comparisons were made for contrast medium adhesion occu rrence in the bladder phantom. The detection of contrast medium adhesion in the bladder phantom differed from that observed in the petri dish experime nts, While contrast adhesion occurred across a fairly broad range of the ur ocystolith mineral types in the petri dish studies, it was observed primari ly for sodium acid urate and cystine urocystoliths in the bladder phantom, Prompted by the observation of bubbles in association with a limited number of urocystolith types in the petri dish studies, bubble occurrence in the bladder phantom was compared to the urocystolith type. Bubble formation on or near the urocystoliths, although uncommonly observed, was seen only with either cystine or silica urocystoliths, The potential clinical utility and clinical caveat aspects of these phenomena are discussed.