The split bolus technique is employed in investigation of the genitourinary tract. It is an attempt to maximize the identification of pathology, whilst limiting dose.
Given that one of the key indications is hematuria and the commonality of urolithiasis, is may often be combined with a separate CT-KUB.
The spilled bolus technique images attempts to offer one exposure for the 3 contrast enhanced parts of the so called four-phase CT study (non contrast, corticomedullary, nephrographic and excretory phases).
The excretory phase is synonymous with a CT-IVU.