Assessing deep learning methods for the identification of kidney stones in endoscopic images

Knowing the type (i.e., the biochemical composition) of kidney stones is crucial to prevent relapses with an appropriate treatment. During ureteroscopies, kidney stones are fragmented, extracted from the urinary tract, and their composition is determined using a morpho-constitutional analysis. This procedure is time-consuming (the morpho-constitutional analysis results are only available after several weeks) and tedious (the fragment extraction lasts up to an hour). Identifying the kidney stone type only with the in-vivo endoscopic images would allow for the dusting of the fragments and eneable early treatments, while the morpho-constitutional analysis is ready. Only few contributions dealing with the in vivo identification of kidney stones have been published. This paper discusses and compares five classification methods including deep convolutional neural networks (DCNN)-based approaches and traditional (non DCNN-based) ones. Even if the best method is a DCCN approach with a precision and recall of 98% and 97% over four classes, this contribution shows that an XGBoost classifier exploiting well-chosen feature vectors can closely approach the performances of DCNN classifiers for a medical application with a limited number of annotated data.

Success of extracorporeal shock wave lithotripsy based on CT texture analysis

OBJECTIVE

The aims of the study were to evaluate whether computerised tomography texture analysis (CTTA) based on non-contrast computed tomography (NCCT) has predictive value for the success of extracorporeal-shockwave lithotripsy (ESWL) in upper urinary tract stones (UUTS).

METHODS

This study included 156 of 356 patients undergoing ESWL for UUTS sized 0.5-2 cm from 2015 to 2019. Patients with congenital kidney anomalies, radiolucent stones, multiple stones, treated for upper urinary tract stones previously and lower pole stones were excluded from study. The number of ESWL sessions of the patients was as follows: 78 (50%) patients had 1 session, 30 (19.2%) patients had 2 sessions and 48 (30.8%) patients had >2 sessions. First- and second-order CTTA properties of patients' UUTS were evaluated using texture analysis software (LIFEx Software). Other clinical features such as Hounsfield Unit (HU), initial stone size, body-mass index (BMI) and skin to stone distance (SSD) was recorded. The patients were divided into two groups according to ESWL success. Cases with residual stones larger than 4 mm were considered failed cases.

RESULTS

BMI, the standard deviation of HU, SSD, skewness, kurtosis, entropy and all second-order statistics were found to be statistically different between the two groups except for correlation (P < .05). Multivariate analysis showed longer SSD and four new parameters of CTTA (kurtosis, entropy, dissimilarity and energy by the distribution of pixel grey levels in the UUTS) to be significant predictors for unsuccessful ESWL outcomes. SSD and second-order CTTA properties (dissimilarity and energy) had an area under ROC curve of 0.802, 0.850 and 0.824 at a 95% confidence interval. ESWL success rate in all patients was 76.9%.

CONCLUSION

CTTA can help select patients who will undergo ESWL for upper urinary tract stones. Thus, we can reduce treatment costs and ESWL complications by preventing unnecessary ESWL applications.

Complex renal calculi treated with traditional Chinese medicine Paishi decoction combined with laparoscopic ureterectomy

To analyze the effect of traditional Chinese medicine Paishi decoction combined with laparoscopic ureterectomy and lithotripsy in the treatment of complex kidney stones. Totally 100 patients with complicated kidney stones admitted to our hospital from January 2019 to January 2021 were selected and randomly divided into a control group and an experimental group, with 50 cases in each group. The control group was treated with laparoscopic ureterectomy for stone removal, the experimental group was treated with traditional Chinese medicine Paishi decoction combined with laparoscopic ureterectomy for stone removal. The therapeutic effects of the two groups were compared. The total effective rate of treatment in the control group was 76% and that of the experimental group was 96%. The stone clearing time, time to pain resolution and time to hematuria disappearance time in the experimental group were significantly shorter as compared with the control group. After treatment, the levels of serum creatinine and blood urea nitrogen in the experimental group were significantly lower than those in the control group. Traditional Chinese medicine Paishi decoction combined with laparoscopic ureterectomy and lithotripsy for treatment of complex kidney stones ameliorates the treatment efficacy, shortens the time of stone removal, mitigates the clinical symptoms of patients, and helps restore renal function, which is worthy of clinical promotion and application.

[The use of ultrasound imaging in minimally invasive percutaneous nephrolithotomy. Can we completely abandon fluoroscopy?]

AIM

To determine the possibility of performing minimally invasive percutaneous nephrolithotomy (PCNL) under ultrasound guidance with the use of X-ray during the access tract formation.

MATERIALS AND METHODS

The results of 102 mini-PNL procedures, performed by a single surgeon during the period 2018-2019, were analyzed retrospectively. In the beginning, ureteral catheter Ch5 was put into an ipsilateral ureter. Further, a puncture of the collecting system was performed with an advancement of the guidewire. At the next stage, a dilation of tract was done using X-ray guidance for the safe formation of the working channel, followed by holmium lithotripsy. At the end a nephrostomy or JJ-stent was left.

RESULTS

The mean age of the patients was 53.13+/-12.9, while average BMI was 29.3+/-6.5. In total, there were 44.1% of women. The average stone size was 20.7+/-10.9 mm; 45.1% of stones were left-sided. Staghorn stones accounted for 15.7% of cases and hydronephrosis was found in 18.6% of patients. The time for creating renal access, dilation of the nephrostomy tract, total operative time and fluoroscopy time were: 19.6+/-13.1, 7.7+/-4.2, 107.7+/-49.9, 57.1+/-41.2 minutes, respectively. In the Group I there were 32 (31.4%) patients undergoing to PCNL under X-ray guidance, while in Group II (n=70, 68.6%) combined US+/-X-ray control was used. The patients age (52.2+/-12.6 vs 53.6+/-13.2, p<0.05) and the stone size (20.6+/-8.9 vs 20.7+/-10.4, p=0.30) were comparable in both groups. There were slightly shorter access time and the total operative time in group II compared with group I (20.6+/-12.3 vs 19.2+/-13.5, p=0.27; 108.1+/-43.3 vs 106.9+/-53.2, p=0.25 respectively). In total, hematocrit level decreased by 4.5% and blood transfusions was done in 3 patients. Postoperative complications developed in 9 cases in both groups (according to the Clavien-Dindo classification, all complications were grade I-II). The stone-free rate (SFR) was 87.2%, and a second-stage was required in 2 cases.

DISCUSSION

The use of ultrasound guidance improves visualization of the collecting system and contributes to the creation of an optimal renal access. It significantly reduces the radiation exposure to the patient and the operating team. We were able to puncture the collecting system in all cases. SFR after PCNL under ultrasound guidance was 88.6%, which is comparable to the results of conventional PCNL with X-ray navigation.

CONCLUSION

PCNL can be performed effectively and safely under ultrasound guidance, which reduces the number of renal punctures and lowers the complication rate. However, this technique also has disadvantages, including longer puncture time in morbidly obese patients without hydronephrosis. With growing experience, the number of unsuccessful kidney punctures decreases, as well as operative time. The use of fluoroscopy during dilatation of the nephrostomy tract allows for preventing additional injuries of the collecting system.

Systematic Review of the Prevalence of Kidney Stones in Cystic Fibrosis

Purpose: To investigate the prevalence of urolithiasis in cystic fibrosis (CF) and to summarize the available clinical features within this unique population. Methods: Studies reporting the prevalence of urolithiasis in CF patients were identified by a systematic search of the literature from inception to July 31, 2020 on three databases: Ovid Medline, Ovid Embase, and Web of Science. Data were extracted on a predetermined standardized form by two independent authors. Results: A total of 596 publications were retrieved and screened, 15 of which met the eligibility criteria. The publications were published between 1993 and 2019 and were all observational in design. There was a total of 2982 patients with CF included in this review. The overall prevalence of stone formation in the CF population was 4.6% (137/2982). The mean age of diagnosis was 25.1 ± 9.6 and ranged from 0.25 to 47. Ultrasound was the most common imaging modality for kidney stone diagnosis. There was no apparent sex difference, with a female to male ratio of 1:1. Surgical intervention was required in 37.8% (34/90) of cases. Stone recurrence was reported in 42.9% (33/77) of stone formers. Conclusions: This review provides the most recent update for the prevalence of urolithiasis in CF patients and summarizes the available clinical data. Our findings suggest that patients with CF could be at risk for developing stones at a younger age and require interventional management strategies at higher rates compared with the general population. Given the heterogeneity of the literature for urolithiasis in CF, larger population-based studies reporting the epidemiology, clinical features, and management strategies are required to further our understanding of urolithiasis in CF.

[Bilateral simultaneous retrograde intrarenal surgery]

Bilateral nephrolithiasis is one of the most prevalent and severe form of urinary stone disease, that is usually linked with endocrinological disorders. These patients are quite often treated in our clinic. A clinical case of patient with bilateral nephrolithiasis who undergone to bilateral simultaneous retrograde intrarenal surgery is presented.

Factors associated with the stone-free status after retrograde intrarenal surgery in children

INTRODUCTION

Paediatric urolithiasis has a recurrent nature because it is frequently associated with metabolic or anatomical disorders or infectious conditions. The rising incidence of the disease with its recurrent nature emphasises the need for minimally invasive therapeutic options. In this study, we aimed to evaluate efficacy and factors affecting the success of retrograde intrarenal surgery (RIRS) in children.

MATERIALS AND METHODS

Patients who underwent RIRS were evaluated retrospectively. Two different flexible ureteroscopes (F-URS) were used (7.5F F-URS and 7.95F with a 4.9F bullet-shaped tip). Irrespective of size, all residual fragments were considered as failure. Age, stone size, stone localisation, Hounsfield Unit (HU), stone-free rate (SFR) and complications were evaluated.

RESULTS

Forty-six patients (29 boys and 17 girls) with a median age of 70.5 months (6-214 months) were treated with RIRS between August 2014 and November 2019. The median operative time was 60 minutes (45-120 minutes). The median follow-up was 26 months (3-65 months). Fourteen patients had lower pole and 10 patients had multiple stones. Ureteral access sheath (UAS) was used in 16 (35%) patients. SFR was 61%. The median number of general anaesthesia was 2 (min 1, max 5). Auxiliary semirigid URS, PCNL and repeat RIRS were required in 4, 6 and 5 patients, respectively. Two patients had postoperative febrile urinary tract infection (UTI) as a complication. Age was associated with post-operative febrile UTI. Presence of stones with HU lower than 700, being operated 4.9F F-URS and without UAS were associated with better SFR.

CONCLUSIONS

RIRS is a minimally invasive method with low complication rates in the treatment of childhood stone disease. Higher stone-free rates are obtained in low HU stones and cases in which we used 4.9 F tip F-URS.

Importance of precise imaging for stone identification during shockwave lithotripsy: a critical evaluation of "OptiVision" as a post-processing radiography imaging modality

To evaluate the efficacy of a unique imaging software "OptiVision" on the confidence of stone identification using X-ray imaging during shockwave lithotripsy. A total of 57 patients with solitary radio-opaque kidney stones sized < 15 mm were included and evaluated with appropriate radiological imaging and laboratory studies before undergoing shockwave lithotripsy (SWL). The size of the stones was measured on KUB and CT images using maximal stone diameters. All patients were evaluated with radiography on the Dornier Delta III immediately before SWL and at the end of the SWL session with fluoroscopy, a snapshot image, and the OptiVision modality (applied over the acquired snapshot image without additional radiation exposure) for precise identification of the stone. All images obtained with these three different imaging modalities (fluoroscopy, snapshot, and OptiVision) were comparatively evaluated for confidence levels in stone identification using a five-point Likert scale (1 = poor diagnostic confidence, 5 = excellent diagnostic confidence). These confidence levels were also used to differentiate between stones and bony structures using these same imaging modalities. Results were evaluated for statistical significance regarding their impact on the precise identification of renal stones. A total of 57 patients with solitary stones were evaluated using flouroscopy, snapshot, and OptiVision images before and after SWL to ascertain the efficacy of these 3 imaging modalities on the precise identification of the calculi. Stone sizes ranged from 4 to 15 mm, with a mean of 8.30 mm in the longest dimension. Evaluation of the findings demonstrated that while the pre- and post-SWL confidence of fluoroscopic stone identification was from 29.51 to 31.15%, the values using snapshot ranged from 31.15 to 39.34%. Pre- and post-SWL confidence of stone identification with OptiVision post-processing imaging was approximately 89%. In the majority of cases (n = 43), the use of OptiVision image processing enabled urologists to identify the stone with a higher level of confidence rating than the use of both fluoroscopy (n = 0) and snapshot (n = 0) image processing tools. While a rating level of 4 or higher was given in 89% of images obtained by OptiVision during the pre- and post-SWL phase, this value was only 37% (4 or more points) using fluoroscopy and Snapshot image processing techniques. For all the radiography image processing tools, the distribution of the Likert score differed significantly among the OptiVision, fluoroscopy, and snapshot imaging modalities (p < 0.001). Precise and reliable identification of stone(s) located in the kidney is essential in delivering shock waves to the desired focal point and achieving higher stone-free rates. Our findings demonstrated that using the specially designed imaging modality OptiVision was significantly helpful in identifying and localizing stones with high-quality images before SWL for effective stone disintegration during this procedure.

Percutaneous puncture during PCNL: new perspective for the future with virtual imaging guidance

CONTEXT

Large and complex renal stones are usually treated with percutaneous nephrolithotomy (PCNL). One of the crucial steps in this procedure is the access to the collecting system with the percutaneous puncture and this maneuver leads to a risk of vascular and neighboring organs' injury. In the last years, the application of virtual image-guided surgery has gained wide diffusion even in this specific field.

OBJECTIVES

To provide a short overview of the most recent evidence on current applications of virtual imaging guidance for PCNL.

EVIDENCE ACQUISITION

A non-systematic review of the literature was performed. Medline, PubMed, the Cochrane Database and Embase were screened for studies regarding the use virtual imaging guidance for PCNL.

EVIDENCE SYNTHESIS

3D virtual navigation technology for PCNL was first used in urology with the purpose of surgical training and surgical planning; subsequently, the field of surgical navigation with different modalities (from cognitive to augmented reality or mixed reality) had been explored. Finally, anecdotal preliminary experiences explored the potential application of artificial intelligence guidance for percutaneous puncture.

CONCLUSION

Nowadays, many experiences proved the potential benefit of virtual guidance for surgical simulation and training. Focusing on surgery, this tool revealed to be useful both for surgical planning, allowed to achieve a better surgical performance, and for surgical navigation by using augmented reality and mixed reality systems aimed to assist the surgeon in real time during the intervention.

Manual kidney stone size measurements in computed tomography are most accurate using multiplanar image reformatations and bone window settings

Computed tomography in suspected urolithiasis provides information about the presence, location and size of stones. Particularly stone size is a key parameter in treatment decision; however, data on impact of reformatation and measurement strategies is sparse. This study aimed to investigate the influence of different image reformatations, slice thicknesses and window settings on stone size measurements. Reference stone sizes of 47 kidney stones representative for clinically encountered compositions were measured manually using a digital caliper (Man-M). Afterwards stones were placed in a 3D-printed, semi-anthropomorphic phantom, and scanned using a low dose protocol (CTDIvol 2 mGy). Images were reconstructed using hybrid-iterative and model-based iterative reconstruction algorithms (HIR, MBIR) with different slice thicknesses. Two independent readers measured largest stone diameter on axial (2 mm and 5 mm) and multiplanar reformatations (based upon 0.67 mm reconstructions) using different window settings (soft-tissue and bone). Statistics were conducted using ANOVA ± correction for multiple comparisons. Overall stone size in CT was underestimated compared to Man-M (8.8 ± 2.9 vs. 7.7 ± 2.7 mm, p < 0.05), yet closely correlated (r = 0.70). Reconstruction algorithm and slice thickness did not significantly impact measurements (p > 0.05), while image reformatations and window settings did (p < 0.05). CT measurements using multiplanar reformatation with a bone window setting showed closest agreement with Man-M (8.7 ± 3.1 vs. 8.8 ± 2.9 mm, p < 0.05, r = 0.83). Manual CT-based stone size measurements are most accurate using multiplanar image reformatation with a bone window setting, while measurements on axial planes with different slice thicknesses underestimate true stone size. Therefore, this procedure is recommended when impacting treatment decision.

Automated Needle Targeting with X-ray (ANT-X) - Robot-assisted device for percutaneous nephrolithotomy (PCNL) with its first successful use in human

INTRODUCTION

To make percutaneous access easier in PCNL, we developed Automated Needle Targeting with X-ray (ANT-X).

METHOD

ANT-X uses an image registration software with a closed loop feedback system to autoalign the puncture needle to the desired calyx using the bullseye technique. We tried percutaneous punctures on a live pig model and compared the results with free-hand technique. We then performed our first PCNL in a human subject with the aid of ANT-X. Our patient was a 48 year-old gentleman with a 1.4cm left lower pole stone.

RESULTS

Initial results for live animal trial showed radiation exposure for robot-assisted arm during puncture was reduced by 26% compared to the free-hand technique (8.2mGy vs 11.2mGy). In the human trial, obtaining percutaneous access was successful at first attempt.

CONCLUSION

ANT-X system can help surgeons feel confident and potentially reduce complications, hence enabling more surgeons to adopt this procedure.

Factors Affecting Tissue Cavitation during Burst Wave Lithotripsy

Burst wave lithotripsy (BWL) is a technology under clinical investigation for non-invasive fragmentation of urinary stones. Under certain ranges of ultrasound exposure parameters, this technology can cause cavitation in tissue leading to renal injury. This study sought to measure the focal pressure amplitude needed to cause cavitation in vivo and determine its consistency in native tissue, in an implanted stone model and under different exposure parameters. The kidneys of eight pigs were exposed to transcutaneous BWL ultrasound pulses. In each kidney, two locations were targeted: the renal sinus and the kidney parenchyma. Each was exposed for 5 min at a set pressure level and parameters, and cavitation was detected using an active cavitation imaging method based on power Doppler ultrasound. The threshold was determined by incrementing the pressure amplitude up or down after each 5-min interval until cavitation occurred/subsided. The pressure thresholds were remeasured postsurgery, targeting an implanted stone or collecting space (in sham). The presence of a stone or sham surgery did not significantly impact the threshold for tissue cavitation. Targeting parenchyma instead of kidney collecting space and lowering the ultrasound pulse repetition frequency both resulted in an increased pressure threshold for cavitation.

Initial Experience with the New Super Thin Single-use Pusen Flexible Ureteroscope 7.5 Fr in Renal Stones Endoscopic Treatment

Introduction: Single-use flexible ureteroscopes (SU-fURS) seems to overcome the main limitations of conventional reusable ureteroscopes in terms of acquisition and maintenance costs and breakages. Our aim was to analyz the efficiency and safety of the thinnest single use flexible scope from Pusen: Uscope Pusen, PU 3033A (Tip = 7.5 Fr.). Material and Methods: We analyzed data from 24 patients with pyelocaliceal stones from January to March 2021. The mean age of the patients was 49 years (range 27 to 71 years). There were unique stones, 7 pyelic, 10 in inferior calyx, 4 in the middle calyx and 3 in superior calyx. The average stone size (larger diameter) was 18 mm (12-26 mm). We used Uscope Pusen 7.5 Fr. (PU 3033A) and Dornier Medilas H Solvo laser. In all cases we applied no touch technique (NTT). We did't used CArm for progression control of the ureteroscope. We evaluated the patients for stone-free rate (SFR), mean operation time and complication rate. Results: The average operative time was 72 +- 21 minutes, range 66-131 min. For all 24 patients we didn't use wires or ureteral access sheath (NTT). Concerning the laser settings for dusting we used low energy: 0.5J, high frequency: 50 Hz, for pop-corning we used high energy: 1 J, medium frequency: 10-50 Hz, and for fragmenting high energy: 1 J, low frequency: 10 Hz. The stone-free status (residual fragments under 3 mm.) after one month was 91,7%. In 2 patients we need the second session with completely dusting of the residual stones. The visibility was optimal and we didn't describe any mucosal lesions of the ureter when we retired the scope. The intrarenal maneuverability was very good. Clavien I and II occurred in 6 patients. Conclusions: This new SU-fURS (7.5 Fr.) seems to be very effective and safe offering us an easy NTT. No ureteral damage and one day surgery are the main real minimally invasive characteristics of this ureteroscope.

Use Of Computed Tomography-Based Nomogram In Adult Age Patients To Predict Success Rates After Shock Wave Lithotripsy For Renal Stones: A Single Center Experience

BACKGROUND

The Triple D score is a novel and easy to use nomogram to predict shock-wave lithotripsy (SWL) outcomes. It is based on Computed Tomography (CT scan) parameters including stone density, skin-to-stone distance, and stone volume. However, its use has not been validated much as studies are sparse regarding its use. Our aim was to validate and evaluate accuracy of the Triple D scoring system in predicting SWL success rates.

METHODS

It was a prospective study of 277 patients who had undergone SWL procedure for renal stones. They were evaluated by using non-contrast tomography, before undergoing SWL. CT scan-based parameters including distance of stone to skin (SSD), stone volume (SV), stone density was assessed. Computation of Cut off values was done with receiver operating characteristics analysis. Score was assigned on the basis of these cut-off values and success rate of SWL was determined. This score ranged from 0 (least favourable score) to 3 (most favourable score).

RESULTS

Stone-free status was attained in 160 patients (57.7%), and 117 (42.3%) patients were labelled to have failed the procedure. Differences between these two groups in terms of Stone volume, stone density and skin to stone distance were significant. Triple D scores of zero,1, 2, and 3 had stone-free rates of 3.6%, 52.56%, 53.3%, and 93.1% respectively (p-vaue<0.001).

CONCLUSIONS

Shock-wave lithotripsy outcomes can be predicted with use of Triple D score and hence, it's externally corroborated. It may help urologist in appropriate patient selection and hence decision making and patient counselling.

[Assessment of radiopaque kidney stone treatment: Combination of extracorporeal shock wave lithotripsy and Fagolitos Plus®. Preliminary case control description.]

INTRODUCTION

The nutritional supplement called Fagolitos plus® contains hydroxycitric acid as main component, in addition to zinc, magnesium, vitamin A and vitamin B6. It is necessary to study new molecules as chemolytic treatment in calcium lithiasis or that facilitate its fragmentation with the help of other instrumental treatments.

OBJECTIVE

The objective of this study is to evaluate the effectiveness of the combined treatment of Fagolitos plus® and extracorporeal lithotripsy in the fragmentation of the lithiasis.

MATERIAL AND METHODS

Retrospective case-control study includes 88 patients with lithiasis. Group 1: Treated with 1 session of extracorporeal lithotripsy and Fagoliths plus®. Group 2: Treated with 1 session of extracorporeal lithotripsy. The variables analyzed were: Age, sex, body mass index, maximum diameter of the stone, area of the stone, hounsfield units of the stone measured by axial tomography, location of the stone, result after 1 session of extracorporeal wave lithotripsy shock [complete fragmentation, partial fragmentation (presence of a fragment greater than 5 mm) and absence of fragmentation (same size of the lithiasis)], adverse effects that occurred after taking Fagolitos plus®, days of treatment with Fagolitos plus® and energy shock wave applied to lithiasis. Results were analyzed with SPSS 20.0, p≤0.05.

RESULTS

The mean age of the patients included in the study is 53.81 ± 12.62 years in group 1 compared to 56.53 ± 12.37 years in group 2, p=0.31. According to the distribution by sex, there were no statistically significant differences (p=0.5), including 24 men and 24 women in group 1 and 23 men and 17 women in group 2. The mean of body mass index of the patients in group 1 was 28.39 ± 2.27 kg/m2 in group 1 versus 28.39 ± 3.03 kg/m2 in group 2, p=0.9. The maximum diameter of the stone was 11.5 ± 3.91 mm in group 1 compared to 13.15 ± 5.49 mm in group 2, p=0.1. The area of the lithiasis measured by tomography was 104.74 ± 70.56 mm2 in group 1 compared to 141.91 ± 80.95 mm2 in group 2, p=0.3. The Hounsfield units measured by tomography of the lithiasis in group 1 was 1061.98 ± 213.68 compared to 1143.15 ± 172.24 in group 2, p=0.06. Relation to fragmentation, complete fragmentation was observed in 66.7% of group 1 patients, compared to 41% of group 2 patients (p=0.02), between 20-30 days after the first session of Extracorporeal Lithotripsy evaluated by means of a simple X-ray of the Abdomen.

CONCLUSIONS

The administration of Fagolitos plus® concomitant to extracorporeal lithotripsy could increase its effectiveness in lithiasis fragmentation, requiring clinical trials and prospective studies to confirm these findings.

Evaluation of Stone Features That Cause the Color Doppler Ultrasound Twinkling Artifact

The color Doppler ultrasound twinkling artifact is a rapid color shift that appears on 43%-96% of kidney stones. Surface microbubbles on kidney stones are theorized to cause twinkling as exposure to elevated static pressures of 0.41-1.13 MPa (approximately 0.5-1 times diagnostic ultrasound pressure and 5-10 times ambient pressure) reduced twinkling. However, it is unclear what external and internal stone features support bubbles. Thirteen ex vivo kidney stones were scanned with color Doppler ultrasound at 2.5, 5 and 18.5 MHz. Select stones were imaged with environmental scanning electron microscopy or underwater micro-computed tomography to evaluate features that may cause twinkling. Results revealed that the lower frequencies produced larger volumes of twinkling. Condensation first occurred in the smallest (∼1 µm diameter) surface pores and may be indicative of where bubbles form. Gas pockets were seen inside two of three tested stones that may contribute to twinkling. Overall, these results provide evidence of cavity structures both externally and internally and their correlation to the twinkling artifact. This indicates that microbubbles may be present on and within kidney stones and may contribute to the twinkling artifact.

[Unilateral combination of staghorn stone with kidney tumor]

This manuscript provides an overview of the available literature about unilateral combination of nephrolithiasis and renal tumor. Analysis of publications has shown that ipsilateral staghorn calculus and kidney tumors are an extremely rare combination. The majority of these infrequent papers describe case reports where the method of treating such patients is limited by the capabilities and competence of the surgeon or clinic. Despite some messages of favorable outcomes of combined interventions, the effectiveness of simultaneous laparoscopic partial nephrectomy and pyelolithotomy has not been studied, and the technique of this procedure, tactics and criteria for choosing this method are not defined.

[A patient with a palpable mass, haematuria and flank pain]

In this case report we present a 54-year-old female with progressive pain in the left flank. Physical examination showed a non-mobile, painless mass in the left upper abdomen. CT revealed an exceptionally large kidney stone. Stone removal (448 g) was performed by hand-assisted laparoscopic nephrectomy.

Crossed unfused renal ectopia with pelviureteric junction obstruction associated with nephrolithiasis: a rare troublesome triad managed by robotic surgery

We report a rare case of non-fused renal ectopia with pelviureteric junction obstruction and multiple pelvic and renal calculi thereby discussing vascular anatomy of the non-fused ectopic kidney along with robot assisted surgical management of this rare clinical entity which amounts for good preoperative workup for best surgical and clinical outcome.

Technical aspects to maximize the hyperaccuracy three-dimensional (HA3D™) computed tomography reconstruction for kidney stones surgery: a pilot study

The aim of the current prospective pilot study was to describe a hyperaccuracy three-dimensional (HA3D^™) model reconstruction technique, specifically developed to maximize the visualization of the renal collecting system's anatomy, and its relationship with the stones, vessels and renal parenchyma, and to compare the HA3D^™ virtual models with the intraoperative findings. The image acquisition was performed using a CT scanner (Toshiba, Aquilion Prime) and included the unenhanced, arterial, venous and excretory phases. The DICOM format CT images were processed by MEDICS Srl ( www.medics3d.com , Turin, Italy). In total, study included three patients with renal stone scheduled for non-papillary prone percutaneous nephrolithotomy (PCNL). The median age and BMI were 51 (range 49-54) and 25.5 (range 25.0-32.7), respectively. The median stone size was 1170 mm² (range 830-1520) and median stone density was 1130 HU (range 600-1340). In all cases, the quality of the CT images acquired with our protocol was adequate to perform the HA3D^™ reconstruction. Median operative and puncture time were 39.4 (range 35.2-44.0) and 1.9 (range 1.8-2.1) mins, respectively. The success rate for the first attempt of the percutaneous puncture was 100%, and only one PCNL tract was sufficient to complete the surgery. All three patients were stone-free on the third postoperative day. A dedicated imaging acquisition protocol and a tailored 3D model reconstruction process specifically developed for kidney stones treatment allow obtaining HA3D^™ highly relevant models to greatly match intraoperative findings during PCNL with the potential of minimizing bleeding and organ injury complications.

Histogram of kidney stones on non-contrast computed tomography to predict successful stone dusting during retrograde intrarenal surgery

PURPOSE

To predict successful dusting of kidney stones during retrograde intrarenal surgery (RIRS) using stone density parameters and histograms measured with non-contrast computed tomography imaging.

METHODS

Medical records of 49 patients who underwent retrograde intrarenal surgery between January 2018 and January 2019 at Kyung Hee University Hospital were reviewed, and the data of 55 stones were evaluated. Patient age, sex, mean stone density, the highest and lowest measured Hounsfield unit (HU), standard deviation and range of the measured HUs, volume of the most measured HU, and success of dusting were evaluated. Histograms of the measured HUs were created and cutoff values for successful dusting were analyzed.

RESULTS

Thirty-two stones were successfully dusted during surgery. Dusted stones had a wider range of HU and higher standard deviation. The volume of the most measured HU was smaller in the dusted stones. Successful dusting could be predicted when the volume of the most measured HU was < 8.9 mm³, with range ≥ 853, or when the volume of the most measured HU was < 8.9 mm³, with range < 853, and the mean stone density was < 355. The histograms of HUs of the dusted stones were wide and rugged, while those of dusting failed stones were narrow and peaked.

CONCLUSION

Evaluation of stone HU histograms showed differences in distribution and proportion. This will help predict surgical outcomes and prepare for intraoperative complications.

Intraoperative cone beam computed tomography for detecting residual stones in percutaneous nephrolithotomy: a feasibility study

Cone beam computed tomography (CBCT) provides multiplanar cross-sectional imaging and three-dimensional reconstructions and can be used intraoperatively in a hybrid operating room. In this study, we investigated the feasibility of using a CBCT-scanner for detecting residual stones during percutaneous nephrolithotomy (PCNL). Intraoperative CBCT-scans were made during PCNL procedures from November 2018 until March 2019 in a university hospital. At the point where the urologist would have otherwise ended the procedure, a CBCT-scan was made to image any residual fragments that could not be detected by either nephroscopy or conventional C-arm fluoroscopy. Residual fragments that were visualized on the CBCT-scan were attempted to be extracted additionally. To evaluate the effect of this additional extraction, each CBCT-scan was compared with a regular follow-up CT-scan that was made 4 weeks postoperatively. A total of 19 procedures were analyzed in this study. The mean duration of performing the CBCT-scan, including preparation and interpretation, was 8 min. Additional stone extraction, if applicable, had a mean duration of 11 min. The mean effective dose per CBCT-scan was 7.25 mSv. Additional extraction of residual fragments as imaged on the CBCT-scan occurred in nine procedures (47%). Of the follow-up CT-scans, 63% showed a stone-free status as compared to 47% of the intraoperative CBCT-scans. We conclude that the use of CBCT for the detection of residual stones in PCNL is meaningful, safe, and feasible.

[InsKid Mobile application for the reconstruction of the internal view of the collecting system]

INTRODUCTION

patients with urinary stone disease during consultation often cannot realize their condition and features of upcoming procedure. Creation of 3D printed models is also not always available or too expensive.

AIM

to create a special program that allows for virtual intrarenal visualization of the collecting system and kidney stone on devices based on the Android operating system and evaluate its efficiency in counseling patients before the upcoming percutaneous nephrolithotomy (PCNL).

MATERIALS AND METHODS

a total of 15 patients who were scheduled to PCNL, were included in the study. All of them had two consultations. During the second consultation, the newly developed program was used. Patient data from DICOM (computed tomography) format were converted to stereolithography (STL) format in order to display it in the application. Each patient assessed the quality of the consultation using a questionnaire.

RESULTS

patients understanding of the kidney anatomy improved by 55% (from 34 to 75 points, p=0.0001), and stone localization by 51% (from 37 to 75 points, p=0.0001). The stages of PCNL became clearer by 57% (from 32 points to 75, p=0.0001), and understanding of possible intra- and postoperative complications was improved by 48% (from 38 to 73 points, p=0.0002). Overall patient satisfaction with counseling improved by 53% (from 35 to 74 points, p=0.0001), and the number of patients who desired for better repeated counseling decreased by 89% (from 9 to 1, p=0.006).

CONCLUSION

The InsKid app is an affordable and easy-to-use program, which doesnt require significant costs and allows patients to understand their disease and upcoming procedure.

Can Dual Energy CT with Fast kV-Switching Determine Renal Stone Composition Accurately?

RATIONALE AND OBJECTIVES

To determine whether a single source computed tomography (CT) system utilizing fast kV switching and low dose settings can characterize (diameter and chemical composition) renal stones accurately when compared infrared spectroscopy.

MATERIALS AND METHODS

The chemical composition of 15 renal stones was determined using Fourier transform infrared spectroscopy. The stones were inserted into a porcine kidney and placed within a water tank for CT scanning using both fast kV switching dual energy and standard protocols. Effective atomic number of each stone was measured using scanner software. Stone diameter measurements were repeated twice to determine intra-rater variation and compared to actual stone diameter as measured by micro CT.

RESULTS

The chemical composition of three stones (one calcium phosphate and two carbonite apatite) could not be determined using the scanner software. The composition of 10/12 remaining stones was correctly identified using dual energy computed tomography (83% absolute agreement; k = 0.69). No statistical difference (p = 0.051) was noted in the mean stone diameter as measured by clinical CT and micro CT.

CONCLUSION

Dual energy computed tomography using fast kV switching may potentially be developed as a low dose clinical tool for identifying and classifying renal stones in vivo supporting clinical decision-making.