Ultrasound Stone Research Articles

Measurement of Posterior Acoustic Stone Shadow on Ultrasound Is a Learnable Skill for Inexperienced Users to Improve Accuracy of Stone Sizing.

Studies suggest that the width of the acoustic shadow on ultrasound (US) more accurately reflects true stone size than the stone width in US images. We evaluated the need for training in the adoption of the acoustic shadow sizing technique by clinical providers. Providers without shadow sizing experience were recruited and assigned in a stratified, alternating manner to receive a training tutorial ("trained") or no intervention ("control"). Each conducted a baseline assessment of 24 clinical US images; where present, shadow width was measured using custom calipers. The trained group subsequently completed a standardized training module on shadow sizing. All subjects repeated measurements after ∼1 week. Group demographics were compared using Fisher's exact test. Measurements were compared to clinically reported stone sizes on corresponding CT and US using mixed-effects models. One millimeter concordance between shadow and CT size was compared using a generalized linear mixed-effects model. Twenty-six subjects were included. There was no significant difference between groups in demographics, clinical role, or US experience. Mean reported CT and US stone sizes were 6.8 ± 4.0 mm and 10.3 ± 4.1 mm, respectively. At baseline, there was no difference in shadow size measurements between groups (p = 0.18), and shadow size was no more accurate than US stone size (p = 0.28 trained; p = 0.81 control), compared to CT. After training, overestimation bias of shadow size in the trained group decreased to 1.6 ± 0.5 mm (p < 0.01), relative to CT. This was not significantly associated with clinical rank, US experience, or stone-measuring experience. One millimeter concordance with CT size significantly increased from 23% to 35% of stones after training (p = 0.01). No significant improvement occurred in the control group. Acoustic shadow sizing was readily adopted by inexperienced providers, but was not more accurate than reported US stone sizes without training. Education on shadow sizing may be warranted before clinical adoption.

Cuantificación del riesgo de formación de cálculos cálcicos en la orina correspondiente a 2 momentos del día en un grupo de niños estudiados para descartar prelitiasis

BackgroundVarious genetic and environmental factors are involved in urolithiasis. The 2 most common metabolic abnormalities are the increase in urinary calcium and low urinary citrate excretion. The ratio calculated between the concentrations of both substances is a good risk marker for the formation of calcium stones. ObjectivesTo determine whether the risk of urinary calcium stone formation changes throughout the day in the same patient. MethodsWe studied 56 children (23V, 33M) to check if they had prelithiasis. Calcium, citrate, and creatinine concentrations were determined in two urine samples collected one before dinner and the other in the morning. It was collected if they had ultrasound stones and if there was a history of urolithiasis in first and/or second degree relatives. ResultsIn 25 patients (44.6%), renal ultrasound was positive for lithiasis (stones [n=9] and microlithiasis [n=16]). Forty of the 56 families (71.4%) had a history of urolithiasis. The percentage of abnormal urinary calcium (28.6%) concentrations and an abnormal calcium/citrate ratio (69.6%) was higher in the first urine of the day. The calcium/citrate ratio was the only studied parameter that was related to a family history of urolithiasis. There were no differences in urinary parameters between patients with and without ultrasound-confirmed kidney stones. ConclusionsUrinary concentrations of calcium and the calcium/citrate ratio vary throughout the day. Urine produced at night has a higher risk of urinary calcium stone formation.

Quantification of the risk of urinary calcium stone formation in the urine collected at 2 times of the day in a group of children studied to rule out prelithiasis

BackgroundVarious genetic and environmental factors are involved in urolithiasis. The 2 most common metabolic abnormalities are the increase in urinary calcium and low urinary citrate excretion. The ratio calculated between the concentrations of both substances is a good risk marker for the formation of calcium stones. ObjectivesTo determine whether the risk of urinary calcium stone formation changes throughout the day in the same patient. MethodsWe studied 56 children (23 V, 33 M) to check if they had prelithiasis. Calcium, citrate, and creatinine concentrations were determined in two urine samples collected one before dinner and the other in the morning. It was collected if they had ultrasound stones and if there was a history of urolithiasis in first and/or second degree relatives. ResultsIn 25 patients (44.6%), renal ultrasound was positive for lithiasis (stones [n=9] and microlithiasis [n=16]). Forty of the 56 families (71.4%) had a history of urolithiasis. The percentage of abnormal urinary calcium (28.6%) concentrations and an abnormal calcium/citrate ratio (69.6%) was higher in the first urine of the day. The calcium/citrate ratio was the only studied parameter that was related to a family history of urolithiasis. There were no differences in urinary parameters between patients with and without ultrasound-confirmed kidney stones. ConclusionsUrinary concentrations of calcium and the calcium/citrate ratio vary throughout the day. Urine produced at night has a higher risk of urinary calcium stone formation.

Advantages of the supine transgluteal approach for distal ureteral stone extracorporeal shock wave lithotripsy: outcomes based on CT characteristics.

Extracorporeal shock wave lithotripsy (ESWL) for distal ureteral stones can be performed in prone or supine position. The aim of this study was to investigate the advantages brought by the supine transgluteal ESWL approach for distal ureteral stones treatment using real-time ultrasound (US), and to show how computerized tomography (CT) scan parameters may be related to the outcomes. Seventy consecutive supine transgluteal ESWL of distal ureteral stones were performed. All patients had a pre-treatment CT scan. The following parameter were evaluated: stone size, Hounsfield Units, skin-to-stone distance, sciaticum majus foramen width, stone to ureteral ostium distance, fragmentation and expulsion perception during the treatment, and the stone-free status. Stone focusing was obtained US, which allows a real-time visualization of stone location and fragmentation. Follow-up included a kidney ureter bladder (KUB) film and US examination at 2-3 weeks after treatment (median time: 18 days). Stone-free condition was defined as the complete absence of stone fragments. A linear regression analysis was used to assess the possible variables mostly related to stone-free status. P<0.05 was considered as significant. Median number of SWL sessions for patient was 1 (IQR: 1-1), mean 1.2±0.5. The re-treatment rate for stone-free patients was 18.3%. Stone-free rate was 85.7%. A clear and real time US stone fragmentation was perceived by the surgeon during the treatment in 42/70 (60%) of patients and correlated to the definitive stone-free status (P=0.04). Stone to ureteral ostium distance was the only variable affecting the stone-free condition (P=0.01). Supine transgluteal SWL of distal ureteral stones provide satisfactory outcomes in terms of stone-free rate. The distance of the stone to the ureteral ostium, measured by CT, appeared to be the only significant variable connected to SWL success.

Nouveau repérage échographique en lithotritie extracorporelle : diminution des temps de scopie et de l’irradiation

Extracorporeal shock wave lithotripsy is the most common method of treatment for kidney stones. Both fluoroscopy and ultrasound imaging can be used to locate stones, but fluoroscopy is more frequently employed. Evaluation of a new stereotaxic navigational system: the stone was located using an ultrasound probe, and its 3D location was saved. The table automatically moved to position the stone at the focal point. A real-time follow-up was possible during treatment. Our objective was to demonstrate a decrease in the use of fluoroscopy to locate kidney stones for extracorporeal shock wave lithotripsy through the use of a 3D ultrasound stone locking system. Prospective analysis of the case records of the 20 patients preceding and the 20 patients succeeding the arrival of the ultrasound stone locking system Visio-Track (EDAP-TMS). We used a Student test to compare age, BMI, kidney stone size, number of shock waves and administered energy. Patient characteristics were comparable. The average age was 55 years old and the average kidney stone size was 10.7 mm. Radiation duration was 174.8 seconds in the group without Visio-Track versus 57.1 seconds in the group with it (P<0.0001). A similar result was observed for radiation doses: 5197.25 mGy x cm2 for the group without versus 1987.6 mGy x cm2 for the group with Visio-Track (P=0.0033). The stone locking system Visio-Track reduced fluoroscopy in our first group of patients, which decreased the patient's individual absorbed irradiation dose.

In Vitro Study of Ultrasound Based Real-Time Tracking for Renal Stones in Shock Wave Lithotripsy: Part II—A Simulated Animal Experiment

We have previously developed and reported an ultrasound based real-time tracking system for renal stones. In the current study we continued to verify the reliability of this tracking system by a simulated animal test. We used 13 prerecorded ultrasound stone trajectories to test the system. The real-time tracking system was implemented on the Litemed 9200 electrohydraulic lithotriptor (LiteMed Co., Taipei, Taiwan). An artificial stone and tap water were sealed in a balloon. The balloon was inserted into the pelvis of a pig kidney. While the kidney was affixed to and moved by a simulator, it was immersed in a specifically designed simulated animal model tank containing tap water. The stone was localized by ultrasound. The kidney was moved by the simulator according to a prerecorded stone trajectory. A total of 3,000 shock waves were delivered to the stone. For each recorded stone trajectory experiments were done under nontracking and tracking conditions. We performed tests of the fragment-to-weight ratio, which denotes the performance of a shock wave lithotriptor when fragmenting a stone. The mean fragment-to-weight ratio was 55.3% +/- 25.9% in the nontracking and 100% +/- 0% in the tracking group. The difference in these 2 groups was statistically significant (paired t test p <0.01). The ultrasound based real-time tracking system proved to improve the performance of a shock wave lithotriptor significantly when fragmenting stones in a simulated animal test. We believe that the tracking system would greatly reduce the number of shocks and time needed for treating renal stones.

Donor-gifted allograft urolithiasis: early percutaneous management

Objectives. To describe our successful early management of donor-gifted nephrolithiasis by percutaneous nephrolithotomy. Donor-gifted nephrolithiasis is a rare and frustrating complication of renal transplantation. In the past, initial conservative management with relief of obstruction and shock wave lithotripsy has been recommended. Methods. We treated 3 cases of donor-gifted cadaveric kidney transplant stones by a percutaneous approach 1 to 2 months postoperatively. Two patients presented with hydronephrosis-associated renal deterioration and febrile urinary tract infection, and the third was diagnosed incidentally on routine postoperative ultrasonography. Results. Percutaneous nephrolithotomy was performed with ultrasound stone fragmentation after initial nephrostomy tube drainage in 1 patient. In the second patient, the stone was successfully removed in a basket in an antegrade fashion. The third patient’s ureteral stone was successfully removed by antegrade ureteroscopy. Postoperatively, no residual stones were noted on nephrostography, and renal function returned to normal. Conclusions. Post-transplant renal calculi can be managed successfully by percutaneous techniques in the early postoperative period and renal function can be salvaged. Pretransplant renal sonography may be considered to limit donor-gifted calculi.

IN VITRO STUDY OF ULTRASOUND BASED REAL-TIME TRACKING OF RENAL STONES FOR SHOCK WAVE LITHOTRIPSY: PART 1

We developed a real-time tracking system for renal stones that decreases the number of shock waves and treatment time of shock wave lithotripsy. Ultrasound images were analyzed to identify the renal stones. A computer software module for ultrasound image processing was developed to monitor stone location instantaneously. Another computer software module controlled generator movement in real time for tracking the stone. We used 13 ultrasound stone trajectories recorded from patients to test the system in vitro. Two tests were established to verify tracking system reliability. One test focused on improvement in the coincidence ratio, which denotes the matching extent of the stone within the effective focal area. The other test focused on improvement in the efficiency ratio, that is a decrease in the number of shocks for stone fragmentation. For each recorded stone trajectory 2 experiments were done under tracking and nontracking conditions. The average coincidence and efficiency ratios plus or minus standard deviation were 79.6% +/- 9.8% and 45.0% +/- 12.7% without tracking, and 97.0% +/- 3.0% and 85.5 +/- 6.8% with tracking, respectively. All tests were statistically significant (paired t test p <0.01). An ultrasound based real-time tracking system proved to be significantly helpful for in vitro lithotripsy. It appears that the tracking system may greatly decrease the number of shocks and treatment time for renal stones.

STAGHORN CALCULI IN CHILDREN: TREATMENT WITH MONOTHERAPY EXTRACORPOREAL SHOCK WAVE LITHOTRIPSY

Purpose We evaluated the effectiveness of monotherapy extracorporeal shock wave lithotripsy (ESWL [dagger]) for treating children with staghorn calculi. Materials and Methods From February 1992 to December 1997, 11 boys and 4 girls 14 months to 13 years old (median age 4 years) presented to our institution with staghorn calculi. In these patients ESWL was performed using a Siemens Lithostar-ULTRA [double dagger] with ultrasound stone localization and with intravenous sedation or without anesthesia. Using the Puigvert method the frequency and energy of the shock waves delivered were increased progressively to desensitize cutaneous nerve receptors, making the procedure less painful and improving stone fragmentation. Results Overall stones resolved in 11 of the 15 patients (73.3%) after an average of 2 ESWL sessions. Of the 11 patients 7 were stone-free after only 1 session, 2 with fragments less than 5 mm. required no further intervention, and 2 required additional surgery, including percutaneous nephrolithotomy to remove large residual stone fragments in 1 and open renal surgery to remove a cystine staghorn calculus in 1. Ureteral stents were not required in any patients. One case of post-ESWL fever resolved promptly with antibiotics. Conclusions ESWL using the Siemens Lithostar-ULTRA is simple, effective and safe primary treatment in children with staghorn calculi.

Selective renal transplantation in primary hyperoxaluria type 1

Primary hyperoxaluria type I (PHI) is a cause of end-stage renal disease in young people. It is caused by deficient activity of hepatic peroxisomal alanine:glyoxylate aminotransferase (AGT), which results in hyperoxalemia and hyperoxaluria. The consequent urolithiasis and nephrocalcinosis result in renal impairment, with further reduction in oxalate excretion and eventual systemic oxalosis. Historically, renal transplantation has yielded very poor results in these patients because of recurrent oxalosis of the graft. Within the last 10 years, combined hepatorenal transplantation has been successfully applied, simultaneously correcting the metabolic lesion in the liver and replacing the damaged kidneys. It has, however, become apparent that medical therapy with vigorous hydration, inhibitors of stone formation and pyridoxine (AGT co-factor), may be successful at delaying, and occasionally in preventing, urolithiasis in some hyperoxaluric patients, particularly those whose hyperoxaluria is reduced by pyridoxine. This, together with intensive perioperative management and modem surgical methods of stone management such as lithotripsy, laser or ultrasound stone fragmentation, and peroutaneous nephrolithotomy, means that renal transplantation alone may be feasible in selected patients. We describe a patient with PHI with clinical and biochemical evidence of significant residual AGT activity who underwent a successful live-related renal transplantation with excellent renal function and no stone recurrence 1 year posttransplantation. The appropriate transplantation strategies for these complex patients are discussed and include isolated renal transplantation for those patients who are without significant systemic oxalosis and have evidence of residual AGT activity.

Extracorporeal Piezoelectric Lithotripsy: Experience in 930 Patients

We treated 930 patients with a Wolf Piezolith 2300 piezoelectric lithotripter using ultrasound stone location and completed a 3-month follow-up. Most (80.7%) of the 986 renoureteral units had solitary stones; of the stones, 74.9% were renal, 21.9% ureteral, and 3.2% both. Preoperative manipulations were limited as much as possible, and ureteral stones were treated in situ. No anesthesia was given. One percent of patients required analgesics because of pain during treatment. Slightly more than half (56.4%) required more than one treatment session, and the average number of sessions was 2.4. The overall success rate was 90.1% (range 95.7% for stones 5-10 mm in diameter; 61% for stones >30 mm). The stone-free rate was 77.5%; the rate of asymptomatic residual fragments under 4 mm in diameter was 12.6%. Morbidity was low and related to stone size. Obstructing ureteric fragments occurred in 56 renoureteral units, 44 of which were successfully treated with extracorporeal shock wave lithotripsy alone and 12 of which required ancillary procedures. Three subcapsular hematomas were detected. Ultrasound stone location limits ureteral stone lithotripsy to upper and lower ureteral calculi. Piezoelectric lithotripsy is a safe and efficient procedure for the treatment of urinary stones.

誤照射防止装置付きピエゾ型砕石装置を用いた体外衝撃波結石破砕術の経験

The results of clinical trial using a TOSHIBA piezolectric extracorporeal lithotripter are presented. The advantages of this machine are the installation of an anti-miss-shot control device (AMCD) to prevent miss-shots to the renal tissue and the improved ultrasound stone localization by an over-head type applicator. AMCD functions so that shock waves are generated only when the stone is in the focal region. Forty patients with urinary tract stone were treated by this machine from October 1989 to March 1990 at the Department of Urology, Tohoku University School of Medicine. Almost all patients could be treated with an analgesic only. The X-ray film obtained three months after ESWL treatment showed that 23 cases (57.5%) were stone-free and 10 cases (25.0%) had stone fragments of less than 4 mm. The successful rate of ESWL using this machine was 82.5%, the result was better than that using other piezolectric machines. No serious complication was observed, except mild hematuria in all cases. Milder postoperative hematuria suggested the decrease of renal tissue injury. It is concluded that the treatment with this machine is safe and seems to be more favorable than the conventional ones.

Painless Piezoelectric Extracorporeal Lithotripsy

A total of 693 stones in 438 renoureteral units from 426 patients 4 months to 84 years old was treated with a mobile piezoelectric lithotriptor using ultrasound stone localization. Of the units 37 per cent had solitary stones smaller than 1.5cm. in diameter, (group 1), 32 per cent had multiple stones up to this size (group 2), 21 per cent had stones 1.6 to 2.5cm. in diameter (group 3) and 10 per cent had calculi larger than 2.5cm. in diameter (group 4). No sedation or analgesics were necessary in 96.2 per cent of the treatments. Of all stones 97.2 per cent were disintegrated, with 39 per cent of the units requiring repeat treatments usually on an outpatient basis. Of the patients 82 per cent had transient hematuria, 6 per cent had fever and 28 per cent temporarily took some type of analgesics within the first 3 months after treatment. Nine per cent of the patients required postoperative ancillary interventions. After 3 months 92 per cent of the renoureteral units in group 1, 73 per cent in group 2, 74 per cent in group 3 and 50 per cent in group 4 were free of stones. Piezoelectric extracorporeal lithotripsy proved to be as efficient as spark-gap lithotripsy, yet it was essentially painless. Ultrasound localization permits treatment of all renal stones but it restricts lithotripsy of ureteral stones to the most proximal and distal fourths of the ureter.