Dual-energy CT for the characterization of urinary calculi: In vitro and in vivo evaluation of a low-dose scanning protocol

Abstract

The efficiency and radiation dose of a low-dose dual-energy (DE) CT protocol for the evaluation of urinary calculus disease were evaluated. A low-dose dual-source DE-CT renal calculi protocol (140 kV, 46 mAs; 80 kV, 210 mAs) was derived from the single-energy (SE) CT protocol used in our institution for the detection of renal calculi (120 kV, 75 mAs). An Alderson-Rando phantom was equipped with thermoluminescence dosimeters and examined by CT with both protocols. The effective doses were calculated. Fifty-one patients with suspected or known urinary calculus disease underwent DE-CT. DE analysis was performed if calculi were detected using a dedicated software tool. Results were compared to chemical analysis after invasive calculus extraction. An effective dose of 3.43 mSv (male) and 5.30 mSv (female) was measured in the phantom for the DE protocol (vs. 3.17/4.57 mSv for the SE protocol). Urinary calculi were found in 34 patients; in 28 patients, calculi were removed and analyzed (23 patients with calcified calculi, three with uric acid calculi, one with 2,8-dihyxdroxyadenine-calculi, one patient with a mixed struvite calculus). DE analysis was able to distinguish between calcified and non-calcified calculi in all cases. In conclusion, dual-energy urinary calculus analysis is effective also with a low-dose protocol. The protocol tested in this study reliably identified calcified urinary calculi in vivo.

Determining the composition of urinary tract calculi using stone-targeted dual-energy CT: evaluation of a low-dose scanning protocol in a clinical environment

“…In vivo studies have demonstrated accurate pre-operative prediction of urinary tract stone material with DECT in agreement with crystallography analysis. [8][9][10] The aim of this study was to further evaluate the utility of DECT to predict urinary tract stone composition on a cohort of patients presenting to a UK National Health Service (NHS) hospital against a gold standard (infrared spectroscopy). The study will also compare ionizing radiation dose output of the DECT protocol with standard non-contrast single-energy CT protocol.…”

The use of non-contrast computed tomography and color Doppler ultrasound in the characterization of urinary stones - preliminary results

“…In recent years some authors investigated use of dual-energy CT to determine the stone type. [15][16][17][18][19][20] These studies have yielded promising results, and this new method has been claimed to be more successful relative to conventional CT. Wisenbaugh et al [19] advocated use of this method for the discrimination between uric acid and other stone types. Foreseeing the presence of uric acid stones beforehand which are amenable to medical chemolysis will save many patients from undergoing unnecessary invasive procedures.…”

Evaluation of virtual unenhanced CT obtained from dual-energy CT urography for detecting urinary stones

“…In fact, we were not able to focus on stone composition but on comparison of VUCT and UCT for detection of urinary stone because our study was retrospectively designed. Several studies reported that DECT is useful for evaluating the composite of urinary stones and that uric acid stones can be differentiated from calcified stones in vitro and in vivo [4,6,7,12]. More in vivo studies are necessary to determine if VUCT helps not only detect a urinary stone but also assess the stone composition.…”

“…As VUCT is equivalent to UCT in characterising renal masses, radiation dose to patients can be reduced during CT scans using dual-energy sources [4,5]. DECT is also useful in evaluating composition of urinary stones, uric acid stones can be differentiated from calcified stones [6][7][8][9][10]. However, there are few in vitro or in vivo reports about the validity of VUCT in detecting urinary stones [11][12][13].…”