Tobias De Zordo MD, Presenter: Nothing to Disclose

Thomas Auer MD, Abstract Co-Author: Nothing to Disclose

Daniel Junker, Abstract Co-Author: Nothing to Disclose

Gudrun Feuchtner MD, Abstract Co-Author: Nothing to Disclose

Werner R. Jaschke MD, PhD, Abstract Co-Author: Nothing to Disclose

Friedrich Hermann Aigner MD, Abstract Co-Author: Nothing to Disclose

Marco Hollaus, Abstract Co-Author: Nothing to Disclose

Christian Dejaco, Abstract Co-Author: Nothing to Disclose

Comparison of radiation dose and image quality of traditional 4 phases computed tomography (CT) imaging of the kidney to split-bolus CT on a 64-slice and 128-slice scanner.

Retrospectively, 80 patients undergoing kidney CT with 4 different scanners or protocols were analyzed: protocol 1: 4 phases (native, corticomedullar, nephrographic, excretoric) CT on 64-slice CT; protocol 2: 4 phases CT on a 128-slice CT; protocol 3: split-bolus CT on 64-slice CT; protocol 4: split-bolus dual-energy CT on 128-slice CT. Split-bolus CT was performed using a split contrast bolus that yields synchronous nephrographic and excretory phase enhancement besides native and corticomedullary phases. Overall, 20 sex, age and body-mass-index matched patients for each group were assessed regarding radiation dose, subjective (2 observers) and objective (HU measurements at cortex, pyramids and pelvis) image quality. Virtual unenhanced images were calculated from dual energy CT scans and subjective image quality was evaluated.

A significant dose reduction was obtained when using new split-bolus CT protocols: protocol 1: median 19.1 mSv (range:13.8-28.8) (CTDIvol: 23.4 mGy (12.6-40.7)), protocol 2: 24.3 mSv (16.0-50.2) (CTDIvol: 44.0 mGy (30.5-79.3)), protocol 3: 14.4 mSv (5.9-26.9) (CTDIvol: 23.4 mGy (12.6-40.7)), protocol 4: 13.4 mSv (8.8-29.3) (CTDIvol: 26.5 mGy (15.4-50.9). When comparing median CTDIvol of the nephrographic and excretoric phases only, radiation could be reduced more than 50% using split-bolus CT: protocol 1: 17.2 mGy (12.8-22.7), protocol 2: 22.3 mGy (16.3-38.7), protocol 3: 8.1 mGy (4.8-14.0), protocol 4: 9.1 mGy (6.1-20.1). Comparable subjective (p=0.58) and objective (p=0.46) image quality could be observed for all protocols. Good interobserver variability was found (92%). Virtual unenhanced images of dual-energy CT resulted in sufficient image quality for diagnosis in all patients.

Split-bolus CT technique combining the nephrographic and excretory phase in one CT scan allows for a significant dose reduction when assessing kidney pathologies while maintaining image quality. Using the dual-energy modus would allow for further dose reduction by omitting also the native scan and calculating a virtual native image.

Patients undergoing CT imaging of the kidneys can be scanned with significantly lower radiation dose when using split-bolus CT techniques.

De Zordo, T, Auer, T, Junker, D, Feuchtner, G, Jaschke, W, Aigner, F, Hollaus, M, Dejaco, C, Radiation Dose Reduction by Applying New Computed Tomography Protocols for Imaging Kidney Disease.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14011463.html