Novel scoring system for predicting stone-free rate after flexible ureteroscopy lithotripsy

This study aims to investigate the factors affecting the stone-free rate (SFR) of flexible ureteroscopy and laser lithotripsy (fURSL) for renal stones and establish predictive models by identifying their prognostic factors. We retrospectively examined 252 patients with renal stones who were treated with fURSL between July 2020 and April 2022. We analyzed the relationship between the patient's clinical data (sex, age, and body mass index), stone status (side, size, location, stone/transverse process pixel ratio [STPR], and the CT value of stone [SCTV]), and SFR to determine the relevant factors and analyze their influence. Additionally, a nomogram was constructed based on these prediction results. A total of 252 patients were enrolled based on the inclusion and exclusion criteria. They were reviewed 7, 30, and 90 days postoperatively, with 46, 23, and 10 patients failing to discharge stones, respectively. Univariate Cox proportional hazard regression results revealed that the SFR was correlated with stone location, diameter (D1, diameter of stone measured by computed tomography [CT]; D2, diameter of stone measured by kidney-ureter-bladder abdominal radiography), SCTV, STPR, and operation time. Multivariate Cox proportional hazard regression was used to develop 2 predictive models for the SFR. The influencing factors of model 1 included D1, location, and SCTV, whereas those of model 2 were D2, location, and STPR. The results are shown in the nomogram. Receiver operating characteristic curves showed no significant difference between models 1 and 2 (P = .498), indicating that the nomogram was highly predictive. After 1000 resamples and internal self-validation, the C-indices of models 1 and 2 were 0.924 and 0.895, respectively, showing that the stone clearance predicted by the nomogram matched the actual situation. Stone location, size, and density (SCTV and STPR) were significant predictors of SFR after fURSL. The scoring system based on these factors may be used to guide optimal treatment strategy selection.

Comparison of diagnostic accuracy of ultra low-dose computed tomography and X-ray of the kidneys, ureters and bladder for urolithiasis in the follow-up setting

INTRODUCTION

Urolithiasis is frequently followed up with a low-dose computed tomography of the kidneys ureters and bladder (LD-CTKUB) with doses typically less than 3 millisieverts. Although X-ray is a lower dose (0.5-1.1 mSv) alternative for follow up, it has lower diagnostic accuracy and is limited to radiopaque calculi. This study aims to compare the diagnostic accuracy of sub-millisievert ultra-low dose CT (ULD-CTKUB) against X-ray KUB for the follow up of urolithiasis when both are compared against the standard of care of a low-dose CT KUB (LD-CTKUB).

METHODS

This prospective study included patients with a known diagnosis of urolithiasis on prior CTKUB presenting for follow up. Each patient underwent a repeat reference LD-CTKUB, ULD-CTKUB and X-ray KUB. All imaging studies were interpreted by three readers. The radiation dose and quantitative noise was calculated for each CT. Both CT and X-ray were assessed for the presence, number and size of all calculi ≥2 mm.

RESULTS

A total of 58 patients were included in this study. LD-CTKUB identified 197 calculi. ULD-CTKUB in our study had a mean effective dose of 0.5 mSv compared to X-ray KUB where doses range in the literature from 0.5 to 1.1 mSv. Per-patient pooled analysis for intrarenal calculi when comparing ULD-CTKUB versus X-ray KUB against a reference LD-CTKUB found a sensitivity of 90% versus 67% (P < 0.01) and specificity of 93% versus 98% (P = 0.18) respectively. For ureteric calculi, the sensitivity was 67% versus 33% (P < 0.01) and specificity 94% versus 94% (P = 1.00) respectively. Per-stone pooled analysis detection rate was 79% for ULD-CTKUB versus 48% for X-ray (P < 0.01) when each was compared to the reference LD-CTKUB. Interobserver agreement was high for intrarenal calculi and moderate for ureteric calculi.

CONCLUSION

Sub-millisievert ULD-CTKUB had lower doses and higher sensitivity than X-ray in patients requiring follow up of known urolithiasis.

Assessing the Diagnostic Performance of CT in Suspected Urinary Stones: A Retrospective Analysis

Background Urinary stone disease is a common reason for emergency department (ED) visits, and a computed tomography scan of the kidneys, ureters, and bladder (CT-KUB) is frequently used for diagnosis. The objective of this study was to estimate the positive rate of CT-KUB and identify predictors of emergency interventions for patients with ureteric stones. Methods A retrospective study was conducted to investigate the positive rate of CT-KUB for urinary stone disease and to explore the factors that determine the need for emergency urologic interventions. The study population included adult patients who underwent CT-KUB to rule out urinary stones at King Fahd University Hospital. Results The study included 364 patients, of whom 245 (67.3%) were men and 119 (32.7%) were women. CT-KUB revealed stones in 243 (66.8%) patients, including 32.4% with renal stones and 54.4% with ureteric stones. Female patients were more likely to have normal results than male patients. Approximately 26.8% of patients with ureteric stones required emergency urologic intervention. Multivariable analysis found that the size and location of ureteric stones were independent predictors for emergency intervention. Patients with distal ureteric stones were 35% less likely to need emergency interventions than those with proximal stones. Conclusion The positive rate of CT-KUB was acceptable for patients with suspected urinary stone disease. Most demographic and clinical characteristics were not predictors for emergency interventions, but the size and location of ureteric stones and elevated creatinine levels were significantly associated.

Does unenhanced computerized tomography as imaging standard post-retrograde intrarenal surgery paradoxically reduce stone-free rate and increase additional treatment for residual fragments? Outcomes from 5395 patients in the FLEXOR study by the TOWER group

Background

Assessment of residual fragments (RFs) is a key step after treatment of kidney stones.

Objective

To evaluate differences in RFs estimation based on unenhanced computerized tomography (CT) versus X-rays/ultrasound after retrograde intrarenal surgery (RIRS) for kidney stones.

Design

A retrospective analysis of data from 20 centers of adult patients who had RIRS was done (January 2018-August 2021).

Methods

Exclusion criteria: ureteric stones, anomalous kidneys, bilateral renal stones. Patients were divided into two groups (group 1: CT; group 2: plain X-rays or combination of X-rays/ultrasound within 3 months after RIRS). Clinically significant RFs (CSRFs) were considered RFs ⩾ 4 mm. One-to-one propensity score matching for age, gender, and stone characteristics was performed. Multivariable logistic regression analysis was performed to evaluate independent predictors of CSRFs.

Results

A total of 5395 patients were included (1748 in group 1; 3647 in group 2). After matching, 608 patients from each group with comparable baseline and stone characteristics were included. CSRFs were diagnosed in 1132 patients in the overall cohort (21.0%). Post-operative CT reported a significantly higher number of patients with RFs ⩾ 4 mm, before (35.7% versus 13.9%, p < 0.001) and after matching (43.1% versus 23.9%, p < 0.001). Only 21.8% of patients in the matched cohort had an ancillary procedure post-RIRS which was significantly higher in group 1 (74.8% versus 47.6%, p < 0.001). Age [OR 1.015 95% confidence interval (CI) 1.009-1.020, p < 0.001], stone size (OR 1.028 95% CI 1.017-1.040, p < 0.001), multiple stones (OR 1.171 95% CI 1.025-1.339, p = 0.021), lower pole stone (OR 1.853 95% CI 1.557-2.204, p < 0.001) and the use of post-operative CT scan (OR 5.9883 95% CI 5.094-7.037, p < 0.001) had significantly higher odds of having CSRFs.

Conclusions

CT is the only reliable imaging to assess the burden of RFs following RIRS and urologist should consider at least one CT scan to determine the same and definitely plan reintervention only based on CT rather than ultrasound and X-ray combination.

Can plain film radiography improve the emergency department detection of clinically important urinary stones?

OBJECTIVE

Physicians frequently use ultrasound to assess hydronephrosis in patients with suspected renal colic, but ultrasound has limited diagnostic sensitivity and rarely clarifies stone size or location. Consequently, up to 80% of emergency department (ED) renal colic patients undergo confirmatory CT imaging. Our goal was to estimate x-ray sensitivity for urinary stones and determine whether x-ray substantially improves stone detection (sensitivity) compared to hydronephrosis assessment alone.

METHODS

We reviewed imaging reports from all renal colic patients who underwent x-ray and CT at four EDs. For each patient, we documented stone size, location and hydronephrosis severity on CT and whether stones were identified on x-ray. We considered moderate and severe hydronephrosis (MS-Hydro) as significant positive findings, then calculated the sensitivity (detection rate) of MS-Hydro and x-ray for large stones ≥5 mm and for stones likely to require intervention (all ureteral stones >7 mm and proximal or middle stones >5 mm). We then tested a diagnostic algorithm adding x-ray to hydronephrosis assessment.

RESULTS

Among 1026 patients with 1527 stones, MS-Hydro sensitivity was 39% for large stones and 60% for interventional stones. X-ray sensitivity was 46% for large stones and 52% for interventional stones. Adding x-ray to hydronephrosis assessment increased sensitivity in all stone categories, specifically from 39% to 68% for large stones (gain = 29%; 95%CI, 23% to 35%) and from 60% to 82% for interventional stones (gain = 22%; 95%CI, 13% to 30%). Because CT and ultrasound show strong agreement for MS-Hydro identification, physicians who depend on ultrasound-based hydronephrosis assessment could achieve similar gains by adding x-ray.

CONCLUSIONS

Adding x-ray to hydronephrosis assessment substantially improves diagnostic sensitivity, enabling the detection of nearly 70% of large stones and over 80% of interventional stones. This level of sensitivity may be sufficient to reassure physicians about a renal colic diagnosis without CT imaging for many patients.

A clinical study on surgical causes of Hematuria

Introduction:

Hematuria is a clinical sign and symptom that every individual would have a worst nightmare and invokes a physician to carefully evaluate possible causes of hematuria. It may be medical or surgical causes. A thorough examination is required to exact the primary pathology. As such, a study on hematuria in North east India is not sufficiently researched or published.

Material & methods:

Here we present an observational study in our institution on that very topic. A study was done purely on surgical causes of hematuria on symptomatic patients. It was done on the inpatient and outpatient basis in Assam Medical College, Dibrugarh during the period of 2016–2019. Total 43 patients were evaluated, who came with symptomatic hematuria.

Results:

Out of 43 cases of symptomatic hematuria, 34 were male and 9 were females patients. Carcinoma urinary bladder was the commonest cause of hematuria, followed by BPH, urolithiasis, carcinoma prostrate, carcinoma upper urinary tract, etc.

Conclusion:

Benign prostatic hyperplasia was found to be the most common benign cause and carcinoma bladder was the commonest malignant cause of hematuria.

Stone residual fragments: A thorny problem

Urolithiasis represents a widespread and common disorder among the world population, with a predicted increase in affected patients in the coming years. Treatment of renal and ureteral stones varies widely, and achieving true stone-free status in all patients is still difficult. Moreover, imaging used to assess residual fragments following procedure impacts the diagnosed stone-free rate percentage considerably. In particular, the use of computed tomography scans has led to a better evaluation of residual fragments as well as so-called clinically insignificant residual fragments, which in a considerable number of cases are, despite their definition, causes of adverse urological events, thus creating a thorny problem for both patients and urologists. Currently, there is no gold standard or validated protocol regarding the management, clearance and prevention of residual fragments. In this article, we review the current literature regarding residual fragments, clinically insignificant residual fragments and their natural history, reporting on diagnostic methods, incidence, complications and outcome with the use of less invasive procedures, taking into consideration viable treatment and management of patients affected.

Ray sum image: its efficacy in renal tract calculus detection

AIM

To determine the efficacy of a ray sum image derived from computed tomography of the kidneys, ureters and bladder (CT KUB) in detecting renal tract calculi and whether this can replace the baseline abdominal radiograph (AXR).

MATERIALS AND METHODS

This is a retrospective study performed at a tertiary referral centre examining adult patients referred for urolithiasis who had undergone AXR within 24 hours of the diagnostic CT KUB. AXR and ray sum image for calculus visibility were reviewed blindly by two readers. Anteroposterior thickness of the patient, presence of excess gas/faecal material, calculus size, location, and mean attenuation were analysed to determine effect on the AXR and ray sum sensitivity.

RESULTS

One hundred and fifty-two calculi were examined with ray sum image sensitivity of 44% (95% confidence interval [CI]: 36-52) and AXR 30% (95% CI: 22-38). Calculus size and mean attenuation significantly affected sensitivities of both ray sum and AXR. There was substantial agreement between the two techniques with κ(Kappa)=0.70 (95% CI: 0.58-0.81, p<0.001).

CONCLUSION

Ray sum image as a post-processed image derived from CT KUB dataset may be a viable alternative to the baseline AXR in patients with CT proven urolithiasis. This would reduce patient radiation dose and streamline workflow in busy radiology and emergency departments.

New Imaging Techniques in the Management of Stone Disease

Recent advances in computed tomography, X-ray-based imaging, and ultrasonography have improved the accuracy of urinary stone detection and differentiation of stone composition while minimizing radiation exposure. Dual-energy computed tomography and digital tomosynthesis show promise in predicting mineral composition to optimize medical and surgical therapy. Electromagnetic tracking may enhance the use of ultrasonography to achieve percutaneous renal access for nephrolithotomy. This article reviews innovations in imaging technology in the contemporary management of urinary stone disease.

Abdominal Radiography With Digital Tomosynthesis: An Alternative to Computed Tomography for Identification of Urinary Calculi?

OBJECTIVE

To compare the accuracy of plain abdominal radiography (kidneys, ureter, and bladder [KUB]) with digital tomosynthesis (DT) to noncontrast computed tomography (NCCT), the gold standard imaging modality for urinary stones. Due to radiation and cost concerns, KUB is often used for diagnosis and follow-up of nephrolithiasis. DT, a novel technique that produces high-quality radiographs with less radiation and/or cost than low-dose NCCT, has not been assessed in this situation.

MATERIALS AND METHODS

Seven fresh tissue cadavers were implanted with stones of known size and/or composition and imaged with KUB, DT, and NCCT. Four blinded readers (2 urologists, 2 radiologists) evaluated KUBs for presence and/or location of calculi. They then re-evaluated with addition of tomograms to assess additional value. After a memory extinction period, readers evaluated NCCT images. Accuracy of detection was determined using nearest-neighbor match with generalized linear mixed modeling.

RESULTS

Total of 59 stones were identified on reference read. Overall, NCCT and DT were both superior to KUB alone (P < .001) while the difference between DT and NCCT was not significant (P = .06). When evaluating uric acid stones, NCCT and DT outperformed KUB (P < .01 and P < .05, respectively) while DT and NCCT were similar (P = .16). Intrarenal stones were better evaluated on DT and NCCT (P < .001 compared to KUB), while DT and NCCT were similar (P = 1.00). Accuracy was lower than anticipated across modalities due to use of the cadaver model.

CONCLUSION

Our study demonstrates DT is superior to KUB for identification of intrarenal calculi and could replace routine use of KUB or NCCT for detecting renal stones, even those composed of uric acid.

Imaging Advances in Urolithiasis

The prevalence of urinary stones in the United States has been described as 1 in 11 persons reporting a history of stones. Imaging plays a crucial role in diagnosis, management, and follow-up for these patients and imaging technology over the last 100 years has advanced as the disease prevalence has increased. CT remains the gold standard for imaging urolithiasis and changes in this technology, with the addition of multidetector CT and dual-energy CT, as well as the changes in utilization of CT, have decreased the radiation dose encountered by patients and allowed for improved stone detection. The use of digital tomography has been introduced for follow-up of recurrent stone formers offering the potential to lower radiation exposure over the course of a patient's lifelong treatment. However, there is still a demand for improved imaging techniques to detect smaller stones and stones in larger patients at lower radiation doses as well as the continued need for the judicious use of all imaging modalities for healthcare cost containment and patient safety.

Alternatives to the baseline KUB for CTKUB-detected calculi: evaluation of CT scout and average and maximum intensity projection images

PURPOSE

A CT of the kidneys, ureters, and bladder (CTKUB) is the investigation of choice in suspected renal colic. Plain kidney, ureter, and bladder radiographs (KUB) can be used to monitor the progress of a stone if radiographically visible on a baseline KUB. This study aims to determine if a low-dose CT Scout, thick-slab average intensity projection (AIP), or maximum intensity projection (MIP) images are suitable as substitutes for a baseline KUB.

METHOD

A retrospective review of patients from a tertiary adult institute that had a positive CTKUB and a KUB within 4 h of the CT was performed. Two consultant radiologists independently reviewed the KUB, CT Scout, AIP, and MIP for stone visibility and their sensitivities and agreement values were compared. Stone characteristics (size, location, and peak Hounsfield units) and patient thickness were recorded and examined for any association with discordant results.

RESULTS

74 stones were evaluated for the study. KUB had a sensitivity of 66.2% (95% CI 54.3-76.8), CT Scout 47.3% (95% CI 35.6-59.3), AIP 55.4% (95% CI 43.4-67.0), and MIP 83.8% (95% CI 73.4-91.3). Fair agreement was found between the KUB and both CT Scout (κ=0.363, 95% CI 0.167-0.558) and AIP (κ=0.384, 95% CI 0.175-0.592). Moderate agreement was found between the KUB and MIP (κ=0.412, 95% CI 0.198-0.625). Neither any stone characteristic nor patient thickness had a significant association with discordant results.

CONCLUSION

None of the possible substitutes for a baseline KUB showed strong agreement with the KUB. Low-dose CT Scouts have a similar sensitivity to the published literature for higher dose CT Scouts.

An overview of kidney stone imaging techniques

Kidney stone imaging is an important diagnostic tool and initial step in deciding which therapeutic options to use for the management of kidney stones. Guidelines provided by the American College of Radiology, American Urological Association, and European Association of Urology differ regarding the optimal initial imaging modality to use to evaluate patients with suspected obstructive nephrolithiasis. Noncontrast CT of the abdomen and pelvis consistently provides the most accurate diagnosis but also exposes patients to ionizing radiation. Traditionally, ultrasonography has a lower sensitivity and specificity than CT, but does not require use of radiation. However, when these imaging modalities were compared in a randomized controlled trial they were found to have equivalent diagnostic accuracy within the emergency department. Both modalities have advantages and disadvantages. Kidney, ureter, bladder (KUB) plain film radiography is most helpful in evaluating for interval stone growth in patients with known stone disease, and is less useful in the setting of acute stones. MRI provides the possibility of 3D imaging without exposure to radiation, but it is costly and currently stones are difficult to visualize. Further developments are expected to enhance each imaging modality for the evaluation and treatment of kidney stones in the near future. A proposed algorithm for imaging patients with acute stones in light of the current guidelines and a randomized controlled trial could aid clinicians.

Managing Small Ureteral Stones: A Retrospective Study on Follow-Up, Clinical Outcomes and Cost-Effectiveness of Conservative Management vs. Early Surgery

INTRODUCTION

The management of ureteral calculi has evolved over the past decades with the advent of new surgical and medical treatments. The current guidelines support conservative management as a possible approach for ureteral stones sized = 10 mm.

OBJECTIVES

We purport to follow the natural history of ureteral stones managed conservatively in this retrospective study, and attempt to ascribe an estimated health-care and cost-effectiveness, from presentation to time of being stone-free.

MATERIALS AND METHODS

192 male and female patients with a single ureteral stone sized = 10 mm were included in this study. The clinical and cost-related outcome was analyzed for different stone sizes (0-4, 4-6 and 6-10 mm). The effectiveness of selected follow-up (FU) scans was also analyzed.

RESULTS

Stone size was found to be related to the degree of hydronephrosis and to the likelihood of need for a surgical management. Conservative management was found to be clinically effective, as 88% of the patients did not require surgery for their stone. 96.1% of the patients with a stone 0-4mm managed to expel their ureteral stone. Bigger ureteral stones were found to be more costly. The cost-effectiveness of the single FU scans was found to be related to their efficiency, while the global cost-effectiveness of conservative management vs. early surgery was higher for smaller stones (26.8 vs. 17.32% for stones 0-4 vs. 6-10 mm).

CONCLUSION

Conservative management is clinically effective with a significant cost-benefit, particularly for the subgroup of stones sized 0-4 mm, where a need for FU scans is in dispute.

Kidney stones

Kidney stones are mineral deposits in the renal calyces and pelvis that are found free or attached to the renal papillae. They contain crystalline and organic components and are formed when the urine becomes supersaturated with respect to a mineral. Calcium oxalate is the main constituent of most stones, many of which form on a foundation of calcium phosphate called Randall's plaques, which are present on the renal papillary surface. Stone formation is highly prevalent, with rates of up to 14.8% and increasing, and a recurrence rate of up to 50% within the first 5 years of the initial stone episode. Obesity, diabetes, hypertension and metabolic syndrome are considered risk factors for stone formation, which, in turn, can lead to hypertension, chronic kidney disease and end-stage renal disease. Management of symptomatic kidney stones has evolved from open surgical lithotomy to minimally invasive endourological treatments leading to a reduction in patient morbidity, improved stone-free rates and better quality of life. Prevention of recurrence requires behavioural and nutritional interventions, as well as pharmacological treatments that are specific for the type of stone. There is a great need for recurrence prevention that requires a better understanding of the mechanisms involved in stone formation to facilitate the development of more-effective drugs.

Do we really need kidneys-ureters-bladder radiography to predict stone radiopacity before treatment with shockwave lithotripsy? Development and internal validation of a novel predictive model based on computed tomography parameters

PURPOSE

To produce and validate a predictive model based on CT parameters for calculating the probability of a stone to be visible on fluoroscopy of shockwave lithotripsy (SWL) and to compare its accuracy to that of kidneys-ureters-bladder (KUB) radiography.

METHODS

We retrospectively analyzed 306 patients (sample group) who underwent an SWL between March 2011 and August 2012. A multivariate analysis of several parameters extracted from the preoperative CT scan was conducted to identify independent predictors for radiopacity on SWL fluoroscopy. The results were used for the creation of a predictive model. Internal validation was made on a group of 75 patients (validation group) treated from September 2012 until December 2012. Predictive accuracy of the model was evaluated by receiver operating characteristic (ROC) curve and calibration plot. The ROC curve was also used for comparing the predictive accuracy of the model to that of KUB radiography.

RESULTS

From 306 evaluated stones, 238 (77.8%) were visible on fluoroscopy. Results of the multivariate analysis revealed that stone size (P<0.001), stone attenuation (P<0.001), location in the midureter (P<0.001), the distance between the stone and the anterior abdominal wall (P<0.001), and fat thickness of the anterior abdominal wall (P=0.001) were all independent predictors for stone radiopacity on fluoroscopy. A predictive model was produced based on the above parameters. The model demonstrated high calibration and areas under the curve of 0.923 and 0.965 in the sample and validation group, respectively, while its predictive performance was significantly higher (P<0.001) of that of KUB radiography (area under the curve=0.727).

CONCLUSIONS

This novel model can estimate with high accuracy stone radiopacity on SWL fluoroscopy using parameters of CT scan and thus it can be used as an alternative to KUB radiography for treatment planning.

Imaging for Urinary Stones: Update in 2015

CONTEXT

Imaging is essential for the diagnosis and the clinical decision-making process of patients with urinary stones.

OBJECTIVE

To assess the benefits and limitations of various imaging techniques by specifically focusing on different phases of stone patients' management.

EVIDENCE ACQUISITION

PubMed and Web of Science databases were used to identify studies published in the last 10 yr on this argument. Search terms included 'urolithiasis', nephrolithiasis', or 'urinary stones' in combination (AND) with the terms 'imaging', 'computer tomography', 'ultrasonography', 'intravenous pyelogram', or 'radiation exposure'. Study selection was based on an independent peer-review process of all the authors after the structured data search.

EVIDENCE SYNTHESIS

Noncontrast-enhanced computer tomography (CT) provides the highest value of diagnostic accuracy for urinary stones. Stone composition can be specifically assessed through the use of dual-energy CT. When information about the anatomy of the renal collecting system is required or alternative pathologies are suspected, CT with contrast injection is recommended. Low-dose protocols allowed a drastic reduction of the effective dose administered to the patient, thus limiting the biological risk due to ionising radiations. Other strategies to contain the radiation exposure include the dual-split bolus dual energy CT and the adaptive statistical image reconstruction. Abdomen ultrasound may be a valid alternative as an initial approach since it does not change the outcome of patients compared with CT, and should be the imaging of choice in children and pregnant women.

CONCLUSIONS

Noncontrast-enhanced CT is the most accurate imaging technique to identify urinary stones. Abdomen ultrasound seems to be a valid alternative in the initial evaluation of urinary colic. New low-dose protocols and strategies have been developed to contain radiation exposure, which is a major issue especially in specific circumstances.

PATIENT SUMMARY

Noncontrast-enhanced computer tomography has been increasingly used for the diagnosis and management of urinary stones. Low-dose protocols as well as alternative imaging should be considered by clinicians in specific circumstances to minimise radiation exposure.

Acute Urinary Tract Disorders

Acute urinary tract disorders often manifest as flank pain and are a common complaint of patients who present to the emergency department. The pain is often a vague, poorly localized sensation that may have a variety of causes. Laboratory and clinical findings, such as hematuria, are neither sensitive nor specific for determining the cause of the flank pain. Accordingly, imaging is an important tool in determining a diagnosis and management plan. Patients with acute urinary tract disorders who present with pain include those with calculi as well as renal infection, vascular disorders, and hemorrhage.

Radiation dosage in the urolithiasis population: Do we over-radiate our patients?

Introduction:

There is increasing concern about the amount of radiation that patients with urolithiasis receive. Ensuring patients are exposed to the minimum necessary radiation is imperative. Here we review the radiation dosages that newly diagnosed urolithiasis patients received in the year following their presentation, both those presenting acutely and those referred electively.

Patients and methods:

A retrospective study of 95 treatment-naïve patients (47 acute, 48 elective) referred for management of urolithiasis was undertaken. The analysis included all imaging modalities related to stone disease for both patient groups within one year following presentation. The total effective dose (mSV) in one year was calculated by summing the dose for each individual radiation exposure.

Results:

An average of 5.6 radiological investigations (range 1–14) was carried out for acute patients and 4.57 for elective patients (range 1–11). The mean total effective dose was 14.45 mSV for the acute cases and 12.87 mSV for the elective cases. The maximum radiation dose reached 30.1 mSV in acute patients and 36.51 mSV in elective ones. None of the patients exceeded the maximal annual dose recommended by the International Commission on Radiological Protection (ICRP) of 50 mSV.

Conclusion:

Management of acute and elective urolithiasis patients can be achieved with acceptable radiation dose exposure. It is extremely important to keep the hazards of radiation in mind whilst managing patients with urolithiasis and clinicians need to remember adherence to the ALARA principle.

Use of computed tomography scout film and Hounsfield unit of computed tomography scan in predicting the radio-opacity of urinary calculi in plain kidney, ureter and bladder radiographs

Objective:

The objective of this study is to determine the diagnostic utility of computed tomography (CT)- scout film with an optimal non-contrast helical CT scan Hounsfield unit (HU) in predicting the appearance of urinary calculus in the plain kidneys, ureter, urinary bladder (KUB)-radiograph.

Methods:

A prospective cross-sectional study was executed and data were collected from June 2007 to June 2012 at a tertiary hospital. The included subjects were diagnosed to have <10mm urolithiasis with non-contrast helical CT scan and KUB X-ray, which were carried out on the same day. Both KUB radiographs and CT-scout film were read by two qualified radiologists with inter-observer standardization prior to the study. Urolithiasis characteristics such as stone location, CT attenuation value, CT-scout film and KUB radiograph appearance were recorded independently by two observers. Univariate logistic analysis with receiver operating characteristic curve was generated to determine the best cut-off HU value of urolithiases not identified in CT-scout film, but determined radio-opaque in KUB X-ray. Subsequently, its sensitivity, specificity, predictive values and likelihood ratios were calculated. Statistical significance was set at P value of 0.05 or less.

Results:

Two hundred and three valid cases were included. 73 out of 75 CT-scout film detected urolithiasis were identified on plain radiograph and determined as radio-opaque. The determined best cut off value of HU utilized for prediction of radiographic characteristics was 630HU at which urinary calculi were not seen at CT-scout film and were KUB X-ray radio-opaque. The set HU cut-off was established of ideal accuracy with an overall sensitivity of 82.2%, specificity of 96.9% and a positive predictive value of 96.5% and negative predictive value of 83.5%.

Conclusion:

Urolithiases identified on the CT-scout film were also seen as radiopaque on the KUB radiograph while those stones not visible on the CT-scout film, but above the optimal HU cut-off value of 630 are also likely to be radiopaque.

Results of urinary dissolution therapy for radiolucent calculi

PURPOSE

In this paper we present our experience with dissolution therapy of radiolucent calculi.

MATERIALS AND METHODS

This was a retrospective analysis of patients who were offered urinary dissolution therapy between January 2010 and June 2011. Patients were treated with tablets containing potassium citrate and magnesium oxide. Partial dissolution was defined as at least a 50% reduction in stone size. Patients with complete or partial dissolution were classified in the successful dissolution group. Patients with no change, inadequate reduction, increase in stone size and those unable to tolerate alkali therapy were classified as failures. Patient sex, stenting before alkalinization, stone size, urine pH at presentation and serum uric acid levels were analyzed using Fisher t-test for an association with successful dissolution.

RESULTS

Out of 67, 48 patients reported for follow up. 10 (15%) had complete dissolution and 13 (19%) had partial dissolution. Alkalinization was unsuccessful in achieving dissolution in 25 (37%). Stenting before alkalinization, patient weight (< 60 vs. > 75kg) and serum uric acid levels (≤ 6 vs. > 6) were the only factors to significantly affected dissolution rates (p = 0.039, p 0.035, p 0.01 respectively).

CONCLUSIONS

A policy of offering dissolution therapy to patients with radiolucent calculi had a successful outcome in 34% of patients.

Radiation exposure in the follow-up of patients with urolithiasis comparing digital tomosynthesis, non-contrast CT, standard KUB, and IVU

OBJECTIVE

To compare the effective doses (EDs) associated with imaging modalities for follow-up of patients with urolithiasis, including stone protocol non-contrast computed tomography (NCCT), kidney, ureter, and bladder radiograph (KUB), intravenous urogram (IVU), and digital tomosynthesis (DT).

METHODS

A validated Monte-Carlo simulation-based software PCXMC 2.0 (STUK) designed for estimation of patient dose from medical X-ray exposures was used to determine the ED for KUB, IVU (KUB scout plus three tomographic images), and DT (two scouts and one tomographic sweep). Simulations were performed using a two-dimensional stationary field onto the corresponding body area of the built-in digital phantom, with actual kVp, mAs, and geometrical parameters of the protocols. The ED for NCCT was determined using an anthropomorphic male phantom that was placed prone on a 64-slice GE Healthcare volume computed tomography (VCT) scanner. High-sensitivity metal oxide semiconductor field effect transistors dosimeters were placed at 20 organ locations and used to measure organ radiation doses.

RESULTS

The ED for a stone protocol NCCT was 3.04±0.34 mSv. The ED for a KUB was 0.63 and 1.1 mSv for the additional tomographic film. The total ED for IVU was 3.93 mSv. The ED for DT performed with two scouts and one sweep (14.2°) was 0.83 mSv.

CONCLUSIONS

Among the different imaging modalities for follow-up of patients with urolithiasis, DT was associated with the least radiation exposure (0.83 mSv). This ED corresponds to a fifth of NCCT or IVU studies. Further studies are needed to demonstrate the sensitivity and specificity of DT for the follow-up of nephrolithiasis patients.

Recent finding and new technologies in nephrolitiasis: a review of the recent literature

This review summarizes recent literature on advances regarding renal and ureteral calculi, with particular focus in areas of recent advances in the overall field of urolithiasis. Clinical management in everyday practice requires a complete understanding of the issues regarding metabolic evaluation and subgrouping of stone-forming patients, diagnostic procedures, effective treatment regime in acute stone colic, medical expulsive therapy, and active stone removal. In this review we focus on new perspectives in managing nephrolitihiasis and discuss recentadvances, including medical expulsive therapy, new technologies, and refinements of classical therapy such as shock wave lithotripsy, give a fundamental modification of nephrolithiasis management. Overall, this field appears to be the most promising, capable of new developments in ureterorenoscopy and percutaneous approaches. Further improvements are expected from robotic-assisted procedures, such as flexible robotics in ureterorenoscopy.

Is bilateral ureterorenoscopy the first choice for the treatment of bilateral ureteral stones? An updated study

INTRODUCTION

We analyze our recent results and discuss the advantages and disadvantages of bilateral single-session ureterorenoscopy (URS) for bilateral ureteral stones.

PATIENTS AND METHODS

55 patients underwent URS with pneumatic lithotripsy (PL) for bilateral stones. 61 (55.5%), 28 (25.4%) and 21 (19.1%) stones were located in the lower, middle and upper ureter, respectively.

RESULTS

Of the 110 stones, 99 (90.0%) were fragmented in a single procedure. The stone clearance rate was 94.5% after the second session. The stone clearance rates with regard to stone location were 71.4, 89.3 and 96.7% for the upper, middle and lower ureter, respectively. An analysis of the clearance rates based on location demonstrated that lower ureteric stones were more successfully removed than upper ureteric stones (96.7 vs.71.4%, p = 0.003).

CONCLUSION

Bilateral single-session URS with PL is a highly effective treatment modality for bilateral ureteral stones. The success rate of PL is affected by stone size and location.

Imaging techniques for stone disease and methods for reducing radiation exposure

Imaging plays a critical role in the evaluation of patients with urolithiasis. It is essential for the diagnosis of stones and provides important information to aide in determining the appropriate treatment of renal or ureteral calculi. Imaging for urolithiasis has evolved over the past 30 years. Currently, noncontrast computed tomography remains the first-line imaging modality for the evaluation of patients with suspected urolithiasis. Proper imaging modality selection helps to minimize radiation exposure. Following the principles of As Low As Reasonably Achievable in the operating room can help reduce the amount of radiation patients are exposed to from fluoroscopy.

Clinical effectiveness protocols for imaging in the management of ureteral calculous disease: AUA technology assessment

PURPOSE

This technology assessment addresses the optimal use of imaging in the evaluation and treatment of patients with suspected or documented ureteral stones.

MATERIALS AND METHODS

A comprehensive literature search addressing 4 guiding questions was performed for full text in English articles published between January 1990 and July 2011. The search focused on major subtopics associated with the imaging of ureteral calculi, and included specific imaging modalities used in the diagnosis and management of ureteral calculous disease such as unenhanced (noncontrast) computerized tomography, conventional radiography, ultrasound, excretory urography, magnetic resonance imaging and nuclear medicine studies. Protocols (in the form of decision tree algorithms) were developed based on this literature review and in some instances on panel opinion. The 4 questions addressed were 1) What imaging study should be performed for suspected ureteral calculous disease? 2) What information should be obtained? 3) After diagnosis of a ureteral calculus, what followup imaging should be used? 4) After treatment of a ureteral calculus, what followup imaging studies should be obtained?

RESULTS

Based on these protocols, noncontrast computerized tomography is recommended to establish the diagnosis in most cases, with a low energy protocol advocated if body habitus is favorable. Conventional radiography and ultrasound are endorsed for monitoring the passage of most radiopaque stones as well as for most patients undergoing stone removal. Other studies may be indicated based on imaging findings, and patient, stone and clinical factors.

CONCLUSIONS

The protocols generated assist the clinician in establishing the diagnosis of ureteral calculous disease, monitoring stone passage and following patients after treatment. The protocols take into account not only clinical effectiveness but also cost-effectiveness and risk/harm associated with the various imaging modalities.

Computed tomography scout views vs. conventional radiography in body-packers - delineation of body-packs and radiation dose in a porcine model

OBJECTIVE

To compare abdominal computed tomography (CT) scout views with conventional radiography regarding radiation dose and delineation of drug packages in a porcine body-packer model.

MATERIALS AND METHODS

Nine samples of illicit drugs packed in ovoid plastic containers were consecutively placed in the rectum of a 121.5 kg pig cadaver. Antero-posterior and lateral scout views were obtained at 120 kVp and 80 mA, 150 mA and 200 mA, respectively, using a 64-row MDCT. Scout views were compared with conventional abdominal antero-posterior radiographs (77 kV and 106 ± 13 mAs). Visibility of three body pack characteristics (wrapping, content, shape) was rated independently by two radiologists and summarized to a delineation score ranging from 0 to 9 with a score ≥ 6 representing sufficient delineation. Mean delineation scores were calculated for each conventional radiography and single plane scout view separately and for a combined rating of antero-posterior and lateral scout views.

RESULTS

Even the lowest single plane scout view delineation score (5.3 ± 2.0 for 80 mA lateral; 0.4 mSv; sensitivity=44%) was significantly higher than for conventional radiographs (3.1 ± 2.5, p<0.001; 2.4 ± 0.3 mSv; sensitivity=11%). Combined reading of antero-posterior and lateral scout views 80 mA yielded sufficient delineation (6.2 ± 1.4; 0.8 mSv; sensitivity=56%).

CONCLUSIONS

All CT scout views showed significantly better delineation ratings and sensitivity than conventional radiographs. Scout views in two planes at 80 mA provided a sufficient level of delineation and a sensitivity five times higher than conventional radiography at less than one third of the radiation dose. In case of diagnostic insecurity, CT can be performed without additional logistical effort.

Evaluation of the sensitivity of scout radiographs on unenhanced helical CT in identifying ureteric calculi: a large UK tertiary referral centre experience

OBJECTIVE

Unenhanced helical CT for kidney, ureter and bladder (CT KUB) has become the standard investigation for renal colic. This study aims to determine the sensitivity of scout radiographs in detecting ureteric calculi using CT KUB as a standard reference.

METHODS

A retrospective review of consecutive patients who presented with acute flank pain and were investigated using CT KUB. 201 patients with positive ureteric calculi were included. Two radiologists independently reviewed the scout radiographs with access to CT KUB images. Each observer recorded the presence or absence of calculi, location, size and mean Hounsfield units of each calculus.

RESULTS

203 ureteric calculi were analysed from 201 patients. The overall sensitivity of scout radiographs for Observer A was 42.3% and for Observer B 52.2%, with an interobserver reliability κ-value of 0.78. The significance of mean Hounsfield units and size between two groups of patients with visible stones and those not visible were tested; the p-value for both variables was <0.0001, which is statistically significant. The study found that calculi in the upper ureter and larger than 4 mm are more likely to be seen on the scout radiograph.

CONCLUSIONS

Usage of CT scout radiography should be encouraged and reported routinely in conjunction with CT KUB as a baseline for treatment follow-up.

Comparison of conventional radiography combined with ultrasonography versus nonenhanced helical computed tomography in evaluation of patients with renal colic

The aim of this study is to determine whether kidneys ureters bladder X-ray (KUB) film combined with ultrasound (US) can be effectively used in evaluation of renal colic and miss stones with clinically significant size identified on nonenhanced computed tomography (NECT) in patients with urolithiasis. This retrospective study evaluated the clinical and radiological records of 300 patients at our institution undergoing KUB and/or US and/or NECT for the evaluation of renal colic from June 2007 to December 2010. Of patients with negative findings on KUB and/or US, 22 had renal stones on NECT (mean size 4.4 mm, range 3-8), 3 had lower ureteral stone (mean size 3.3 mm, range 2-5). In patients with isolated suspicious renal ectasia without stone image, two had renal stone on NECT (mean size 4 mm, range 2-6), 5 had upper ureteral stone (mean size 4.4 mm, range 4-6), 7 had middle ureteral stone (mean size 3.7 mm, range 3-4) and 14 had lower ureteral stone (mean size 4 mm, range 2-6). The cost-effective and almost radiation-free combination of KUB and US should be preferred for diagnosis of urolithiasis, as it detects most of the ureteral and renal calculi which are clinically significant.

Nephrolithiasis: Endocrine evaluation

Nephrolithias is a common problem in populations around the world, and contribute significantly to the development of end stage renal disease. It is a matter of debate whether the metabolic factors responsible for renal stone formation are similar or variable in different populations around the globe. This review discusses the influence of different metabolic and dietary factor, and some other co-morbid conditions on the etiopathogenesis Nephrolithiasis. Evaluation and medical management of Nephrolithiasis is summarized in the later part of the article.

Nephrolithiasis: what surgeons need to know

OBJECTIVE

In this article, we review the standard of care for imaging of nephrolithiasis as well as new technology and radiation concerns from the perspective of the urologic surgeon.

CONCLUSION

Nephrolithiasis is a common cause of morbidity with a lifetime prevalence of 5-10% worldwide. Increasingly, diagnostic evaluation and planning for medical or surgical intervention have become reliant on imaging.