Surface Of Kidney Stones Research Articles

Etiology of the color Doppler twinkling artifact on kidney stones

Rapid Doppler shifts highlight some kidney stones with a rapid change in color in ultrasound imaging which is called the “twinkling artifact.” Many hypotheses exist to describe the mechanism of twinkling, including the hypothesis that microbubbles are stabilized in crevices on the surface of kidney stones. The objective is to evaluate the distribution of stable microbubbles on kidney stone surfaces with humidity-controlled scanning electron microscopy (ESEM) and determine whether any sub-surface characteristics as assessed with micro-computed tomography (µCT) may contribute to twinkling. A Verasonics® research ultrasound system with the Verasonics L22-14 and Philips/ATL L7-4 and C5-2 transducers quantified twinkling. Results show a correlation between voids within kidney stones and the locations of twinkling on the stone surface. These voids had a calculated free-field Minneart resonant frequency of 3–9 MHz depending on the size. ESEM revealed that surfaces that twinkled had more crevices with radii corresponding to bubbles with a free-field resonant frequency of 3–7 MHz. These results suggest that internal voids and surface crevices contribute to the twinkling artifact on kidney stones.

New insights into the presence of sodium hydrogen urate monohydrate in Randall's plaque

Calcium oxalate nephrolithiasis is a common ailment. Frequent risk factors associated with are low diuresis, dietary imbalance, inherited or acquired metabolic disorders. Another important factor, namely the presence of a mineral deposit made of apatite at the surface of the papilla, named Randall's plaque (RP), has been recently underlined. In most cases, RP which serves as a nidus for kidney stone formation is made of calcium phosphate apatite (CA). However, RP does not seem to be composed exclusively of CA. We would like to assess the case of RP where sodium hydrogen urate monohydrate (NaUr) is also present in its chemical composition. To attain this goal, a set of experiments including Environmental Scanning Electron Microscopy (ESEM) and Synchrotron Radiation Fourier Transform InfraRed (SR-FTIR) has been performed to analyze papillae of six kidneys randomly selected after they were surgically removed for cancer. NaUr crystals were found in two samples. We show through ESEM an usual morphology of RP present at the surface of kidney stones in the presence of NaUr. Moreover, we discuss the presence of NaUr in the renal parenchyma and its spatial repartition with CA. The complete set of data indicates that different biochemical mechanisms are probably involved in the pathogenesis of RP. The next step will be to establish a significant relationship between these physicochemical data and the clinical and biochemical data of the patients.

Bubbles trapped on the surface of kidney stones as a cause of the twinkling artifact in ultrasound imaging

A twinkling artifact (TA) associated with urinary calculi has been described as rapidly changing colors on Doppler ultrasound. The purpose of this study was to investigate the mechanism of TA. Doppler processing was performed on raw per channel radio-frequency data collected when imaging human kidney stones in degassed water. Suppression of twinkling by an ensemble of computer generated replicas of a single received signal demonstrated that the TA arises from variability among the acoustic signals and not from electronic signal processing. This variability was found to be random in nature, and its suppression by elevated static pressure, and its return when the pressure was released, suggests that the presence of surface bubbles on the stone is the mechanism that gives rise to the TA. Submicron size bubbles are often trapped in crevices on solid objects, but the presence of these bubbles in vivo is unexpected. To further check this mechanism under conditions identical to in vivo, stone-producing porcine kidneys were harvested en bloc with a ligated ureter and then placed into a pressure chamber and imaged at elevated atmospheric pressure. The result was similar to in vitro. [Work supported by NIH DK43881, DK092197, RFBR, and NSBRI through NASA NCC 9-58.]

2aBA6. Bubbles trapped on the surface of kidney stones as a cause of the twinkling artifact in ultrasound imaging.

A twinkling artifact (TA) associated with urinary calculi has been described as rapidly changing colors on Doppler ultrasound. The purpose of this study was to investigate the mechanism of the TA. Doppler processing was performed on raw per channel radio-frequency data collected when imaging human kidney stones in degassed water. Suppression of twinkling by an ensemble of computer generated replicas of a single received signal demonstrated that the TA arises from variability among the acoustic signals and not from electronic signal processing. This variability was found to be random in nature, and its suppression by elevated static pressure, and its return when the pressure was released, suggests that the presence of surface bubbles on the stone is the mechanism of the TA. Submicron size bubbles are often trapped in crevices on solid objects, but the presence of these bubbles in vivo is unexpected. To further check this mechanism under conditions identical to in vivo, stone-producing porcine kidneys were harvested en bloc with a ligated ureter and then placed into a pressure chamber and imaged at elevated atmospheric pressure. The result was similar to in vitro. Work supported by NIH DK43881, DK092197, RFBR 11-02-01189, 12-02-00114, and NSBRI through NASA NCC 9-58.