Ultrasound (US) contrast media are not nephrotoxic, which makes these potentially ideal agents for microvascular imaging in AKI or CKD [10]. Contrast-enhanced US has the potential to provide dynamic quantitative information about renal perfusion and can diagnose acute cortical necrosis and infarction in allografts and native kidneys [11- 13]. All elements are essential: 1) timing, 2) reconstructions/reformats, and 3) 3-D renderings. Standard CTs with contrast also include timing issues and reconstructions/reformats. Only in CTA, however, is 3-D rendering a required element. This corresponds to the definitions that the CMS has applied to the Current Procedural Terminology codes. CT urography (CTU) is an imaging study that is tailored to improve visualization of both the upper and lower urinary tracts. There is variability in the specific parameters, but it usually involves unenhanced images followed by intravenous (IV) contrast-enhanced images, including nephrographic and excretory phases acquired at least 5 minutes after contrast injection. Alternatively, a split-bolus technique uses an initial loading dose of IV contrast and then obtains a combined nephrographic-excretory phase after a second IV contrast dose; some sites include arterial phase. CTU should use thin-slice acquisition. Oral hydration, IV saline hydration, compression bands, and low- dose furosemide have all been reported as methods to improve urinary distension. Reconstruction methods commonly include maximum intensity projection or 3-D volume rendering. For the purposes of this document, we make a distinction between CTU and CT abdomen and pelvis without and with IV contrast. CT abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts and without both the precontrast and excretory phases. MR urography (MRU) is also tailored to improve imaging of the urinary system.
Renal Failure. Ultrasound (US) contrast media are not nephrotoxic, which makes these potentially ideal agents for microvascular imaging in AKI or CKD [10]. Contrast-enhanced US has the potential to provide dynamic quantitative information about renal perfusion and can diagnose acute cortical necrosis and infarction in allografts and native kidneys [11- 13]. All elements are essential: 1) timing, 2) reconstructions/reformats, and 3) 3-D renderings. Standard CTs with contrast also include timing issues and reconstructions/reformats. Only in CTA, however, is 3-D rendering a required element. This corresponds to the definitions that the CMS has applied to the Current Procedural Terminology codes. CT urography (CTU) is an imaging study that is tailored to improve visualization of both the upper and lower urinary tracts. There is variability in the specific parameters, but it usually involves unenhanced images followed by intravenous (IV) contrast-enhanced images, including nephrographic and excretory phases acquired at least 5 minutes after contrast injection. Alternatively, a split-bolus technique uses an initial loading dose of IV contrast and then obtains a combined nephrographic-excretory phase after a second IV contrast dose; some sites include arterial phase. CTU should use thin-slice acquisition. Oral hydration, IV saline hydration, compression bands, and low- dose furosemide have all been reported as methods to improve urinary distension. Reconstruction methods commonly include maximum intensity projection or 3-D volume rendering. For the purposes of this document, we make a distinction between CTU and CT abdomen and pelvis without and with IV contrast. CT abdomen and pelvis without and with IV contrast is defined as any protocol not specifically tailored for evaluation of the upper and lower urinary tracts and without both the precontrast and excretory phases. MR urography (MRU) is also tailored to improve imaging of the urinary system.