Abstract

DSCT for Evaluation of Urolithiasis

posted by Anno Graser, M. D. | Oct 23, 2008

History

A 34 year-old female (A) and a 55 year-old male (B) patient were both referred for MDCT evaluation of a known urinary calculi. A non-enhanced MDCT scan of the abdomen was performed on the Dual Source CT (DSCT) using spiral Dual Energy evaluation.

Diagnosis

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 materials. The red color-coding 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-coding shown in patient B characterizes a calcium oxalate stone. Based on this Dual Energy study, the stone was removed in an interventional procedure. The stone analysis of the removed stone confirmed the calcium oxalate composition.

Comments

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 materials. Dual Energy CT 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.

[1a] + [1b] Using conventional CT imaging the kidney stones (arrows) can clearly be visualized; however its composition can not be characterized.
[2a] The Dual Energy scan enables the characterization of tissue and other materials. In patient A the kidney stone could be identified as uric acid stone, color-coded in red.	[2b] Spiral Dual Energy enables the characterization of the kidney stone in Patient B as calcium oxalate stone, color-coded in blue (same color as cortical bone).