Dual Energy – Evaluation of Kidney Stones
SOMATOM Definition abdominal scan with spiral dual energy
Anno Graser, M.D., Thorsten Johnson, M. D., and Christoph R. Becker, M. D.
Department of Clinical Radiology, University of Munich - Grosshadern Campus
A 34 year-old male (A) and a 55 year-old male (B) patient were both referred for MDCT evaluation of a known urolithiasis. A non-enhanced MDCT scan of the abdomen was performed on the SOMATOM Definition using spiral Dual Energy evaluation.
The Dual Energy acquisition allowed not only a precise localization of the kidney stones in both patients, moreover it permitted a characterization of the scanned tissue, or material.. The red color-code of the kidney stone shown in Patient A indicates a uric acid stone. After the Dual Energy CT, we could transfer the patient for drug therapy treatment. Subsequently, the stone passed spontaneously, and was analyzed. The analysis confirmed that the concrement consisted of 100% uric acid. The blue color-code shown in Patient B characterizes a calcium oxalate stone. Based on this Dual Energy study, the stone was removed in an interventional procedure. The lab analysis of the removed stone confirmed the calcium oxalate composition.
The majority of kidney stones can be grouped as either calcium oxalate stones (65%) or uric acid material (15%). Conventional CT imaging helps to locate and visualize the kidney stone. However, a fast and secure characterization is not possible. Dual Energy scanning overcomes this limitation and enables us to differentiate the scanned tissue. The SOMATOM Definition permits the use of two sources at two different kV levels simultaneously. The result are two spiral data sets acquired in a single scan providing diverse information, which allows to differentiate, characterize, isolate, and distinguish the imaged tissue and material as shown in Figure 1b and 2b. A corresponding treatment decision can be immediately taken, avoiding unnecessary hospitalization of the patient.
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