Detection Of Renal Calculi Research Articles

Ultrasonography in Detection of Renal Calculi in Children; a Systematic Review and Meta-analysis.

Although numerous studies have been done to evaluate the diagnostic value of ultrasonography in diagnosis of renal calculi in children, there is still no consensus. Therefore, in the present systematic review and meta-analysis, we aimed to evaluate the diagnostic accuracy of ultrasonography in identifying renal stones in children. A comprehensive search of the electronic databases including Medline, Embase, Scopus and Web of Science was conducted up to July 2019. Diagnostic accuracy studies in children were included. Data was summarized and pooled. Area under the curve (AUC), sensitivity, specificity, diagnostic score and diagnostic odds ratio were reported with 95% confidence interval (95% CI). Data from 7 articles were included. Pooled analysis showed that the area under the curve of ultrasonography in diagnosis of pediatric renal calculi was 0.94 (95% CI: 0.92 to 0.96). The sensitivity and specificity of this diagnostic modality were 0.80 (95% CI: 0.70 to 0.87) and 1.00 (95% CI: 0.84 to 1.00), respectively. Diagnostic score and diagnostic odds ratio of ultrasonography in detection of renal calculi were 110.32 (95% CI: 2.88 to 19.76) and 82362.41 (95% CI: 17.80 to 3.8 × 108), respectively. Overall, the low level of evidence indicates that sensitivity and specificity of ultrasonography in detecting renal calculi in children are 80% and 100%, respectively. However, due to the serious limitations of the included studies, well-designed prospective diagnostic accuracy studies are recommended for future studies.

AIUM Practice Parameter for the Performance of Point-of-Care Ultrasound Examinations.

AIUM Practice Parameter for the Performance of Point-of-Care Ultrasound Examinations.

Computer-aided detection of renal calculi from noncontrast CT images using TV-flow and MSER features.

Renal calculi are common extracolonic incidental findings on computed tomographic colonography (CTC). This work aims to develop a fully automated computer-aided diagnosis system to accurately detect renal calculi on CTC images. The authors developed a total variation (TV) flow method to reduce image noise within the kidneys while maintaining the characteristic appearance of renal calculi. Maximally stable extremal region (MSER) features were then calculated to robustly identify calculi candidates. Finally, the authors computed texture and shape features that were imported to support vector machines for calculus classification. The method was validated on a dataset of 192 patients and compared to a baseline approach that detects calculi by thresholding. The authors also compared their method with the detection approaches using anisotropic diffusion and nonsmoothing. At a false positive rate of 8 per patient, the sensitivities of the new method and the baseline thresholding approach were 69% and 35% (p < 1e - 3) on all calculi from 1 to 433 mm(3) in the testing dataset. The sensitivities of the detection methods using anisotropic diffusion and nonsmoothing were 36% and 0%, respectively. The sensitivity of the new method increased to 90% if only larger and more clinically relevant calculi were considered. Experimental results demonstrated that TV-flow and MSER features are efficient means to robustly and accurately detect renal calculi on low-dose, high noise CTC images. Thus, the proposed method can potentially improve diagnosis.

Correlation Between Twinkling Artifact and Color Doppler Carrier Frequency: Preliminary Observations in Renal Calculi

Color Doppler twinkling is a well-defined but not well-understood phenomenon that may assist in the detection of renal calculi. However, the relationship between the appearance of color Doppler twinkling and color Doppler carrier frequency has not been described systematically. To evaluate this relationship, a retrospective review was performed on 20 cases of renal calculi detected by twinkling on renal color Doppler sonography and confirmed with unenhanced computed tomography. The variable strength of twinkling at and behind renal calculi was observed with color Doppler carrier frequencies ranging from 1.75–4.0 MHz. All 20 calculi (100%) demonstrated twinkling when a low color Doppler carrier frequency, 1.75 or 2 MHz, was applied, whereas 12 of 20 cases (60%) were absent of twinkling when the highest carrier frequencies tested—3.5 or 4 MHz—were used. Quantitatively, there was a significant correlation between the amount of twinkling and carrier frequency (p = 0.002102). Hence, we conclude that the strength of the twinkling is color Doppler carrier frequency–dependent. The strength of the twinkling significantly increased when the color carrier frequency used for imaging decreased. Therefore, to improve renal calculi detection by enhancing the strength of the twinkling, the use of a lower color Doppler carrier frequency is recommended.

Effect of Reduced Radiation CT Protocols on the Detection of Renal Calculi

To determine the effect of reduced radiation (tube charge, measured as milliamperes per second) protocols on the sensitivity and specificity of multidetector computed tomography (CT) in the detection of renal calculi. This Health Insurance Portability and Accountability Act-compliant human cadaveric study was approved by the Department of Anatomic Pathology with strict adherence to the university policy for handling donor specimens. Three to five renal stones (range, 2.0-4.0 mm) were randomly placed in 14 human cadaveric kidneys and scanned with a 16-detector CT scanner at 100, 60, and 30 mAs while maintaining other imaging parameters as constant. Following acquisition, images were reviewed independently by two radiologists who were blinded to the location and presence of renal calculi. Interobserver agreement was measured with kappa statistics. The McNemar test was used to compare the sensitivity and specificity between different radiation settings for each reader. Specificity for both readers ranged from 105 (0.95; 95% confidence interval [CI]: 0.90, 0.99) to 109 (0.99; 95% CI: 0.95, 1.0) of 110 without significant differences between 30 and 60 mAs to the standard 100 mAs (P = .500 to >.999). Sensitivity ranged from 42 (0.74; 95% CI: 0.60, 0.84) to 48 (0.84; 95% CI: 0.72, 0.93) of 57, also without significant differences (P = .070 to >.999). When renal calculi detection rates were analyzed by size, 3.0-4.0-mm stones were detected well at all tube charge settings, ranging from 86%-90% (n = 21 for 3.0-mm stones) to 95%-100% (n = 19 for 4.0-mm stones). However, 2.0-mm stones were poorly detected at all tube charge settings (29%-59%; 5-10 of 17). Overall interobserver agreement for stone detection was excellent, with kappa = 0.862. Decreasing the tube charge from 100 to 30 mAs resulted in similar detection of renal stones while reducing patient radiation exposure by as much as 70%. Multidetector CT scanning parameters should be tailored to minimize radiation exposure to the patients while helping detect clinically significant renal stones.

Detection of Renal Calculi on Late Arterial Phase Computed Tomography Images

Renal calculi are sometimes incidentally detected on contrast-enhanced computed tomography (CT) scans. The purpose of this study was to evaluate the detectability of renal calculi on arterial phase CT. One hundred thirty-three kidneys of 67 consecutive patients (one had prior unilateral nephrectomy) who underwent multidetector CT including noncontrast and arterial phase (acquired at 25 seconds from the start of 120 mL of intravenous contrast injection at a rate of 3 mL/s) scans were retrospectively evaluated. The detectability of renal calculi was determined by comparison of the noncontrast and contrast-enhanced scans. Sixty-three calculi in 25 kidneys were detected in 17 patients on noncontrast CT. Forty-seven (75%) of the 63 calculi were also detected on the arterial phase scans. The size and highest attenuation of calculi (measured on noncontrast CT) detected on arterial phase scans were 4.3 +/- 3.0 mm and 556 +/- 353 Hounsfield units, and those detected only on noncontrast CT were 2.8 +/- 0.8 mm (P = 0.053) and 181 +/- 47 Hounsfield units (P < 0.0001), respectively. All calculi larger than 5 mm were detected on arterial phase scans. On arterial phase scans, 75% of the renal calculi and allrenal calculi larger than 5 mm were detected; the attenuation of the calculi had a significant correlation to detectability.

Segmentation of renal calculi in ultrasound images.

An algorithm proposed by Sridhar and Kumaravel is extended to include a framework for the detection of renal calculi. Calculi occur due to abnormal collection of certain chemicals like oxalate, phosphate and uric acid. These calculi can be present in the kidney, ureter or urinary bladder. Performance analysis is done to a set of five known algorithms using parameters such as success rate in calculi detection, border error metric and time. The framework is constructed by combining the best algorithm based on the performance analysis and a procedure to validate the detected calculi using the shadow it casts in ultrasound images. Ultrasound images of 37 patients are used for testing the algorithm. The detected calculi based on the framework match those determined by expert clinicians in more than 95% of the cases.

Incidencia y tratamiento de la litiasis urinaria en el injerto renal

Urinary calculi is an uncommon complication in kidney transplantation; several stone risk factors are found in transplanted patients, but in most cases there is not a relationship between these risk factors and stone formation. The treatment of these patients is complex due to their both immunosuppressive status and border-line renal function. From 1980 to February 2000, 1198 kidney transplant have been performed in our institution. We describe our series consisting in 22 urinary calculi (15 in the graft, 3 in the urether and 4 in the bladder) in 18 patients, including 7 stones detected in cadaveric donor patients. We performed external shock wave lithotripsy in 7 patients, bench surgery in 4, endoscopic mechanic lithotripsy in 5, open surgery in 1 and observation in 6. Calcium oxalate (mono and dihidrate) was found in 9 of 13 calculi. Metabolic changes were found in 15 of the 18 patients, the most common was hiperuricemia. There were not complications of every treatment applied and 9% of them needed a savage treatment. We found recurrence in 4 cases (22.2%). Now 12 of the patients are stone-free (66.7%) and three have non-significative stones (83.3% without symptoms). Detection of renal calculi in cadaveric renal donors is not a reason to refuse the graft for further transplantation. In both renal calculi up to 2 cm and uretheric calculi surgical treatment is assessed as first option. In caliceal stones smaller than 5 mm observations is the best treatment.

Intravenous urography in the emergency department: when do we need it?

Intravenous urography (IVU) is a useful radiographic study in the detection of renal and ureteral calculi. However, it is time consuming, expensive, and exposes the patient to i.v. contrast and radiation. To determine the impact of utilizing IVU less for the detection of renal calculi, criteria for ordering IVU in the emergency department (ED) were evaluated, and patients with high probability of positive IVU were identified. Variables included presence of acute flank pain with haematuria, prior history of renal calculus, degree of haematuria, and uncontrolled pain. We reviewed patients presenting with acute flank and abdominal pain with haematuria from May 1995 to May 1996 at a large urban university hospital. Charts were abstracted for prior history, reason for ordering IVU, time in the ED, laboratory results, IVU result, final diagnosis, and disposition. Data was analysed with Student's t-test, Wilcoxon rank-sum and receiver operating characteristic (ROC) analysis. A total of 302 patients were identified, and 185 underwent IVU during the study period. For patients with prior history of renal calculi 82% had positive IVU (sensitivity 51%, specificity 87%). For patients with both acute flank pain and haematuria, 92% had a positive IVU (sensitivity 93%, specificity 43%), and 19% of patients with abdominal pain of unclear aetiology with haematuria had a positive IVU. All patients with uncontrolled pain had evidence of high-grade obstruction on IVU. Degree of haematuria was not predictive of a positive IVU from ROC curve derivation. IVU is a useful study in the ED but may be overutilized, leading to lengthy patient stays. The combined objective findings of acute flank pain and haematuria are sensitive, and prior history is specific in identifying patients with renal calculi. Degree of haematuria was not useful in predicting renal calculi. By utilizing the criteria of acute flank pain and haematuria as a decision aid, 66% of all IVUs ordered could have been avoided.

The evaluation of suspected renal colic: Ultrasound scan versus excretory urography

Patients commonly present to the emergency department with a suspected diagnosis of renal colic. A prospective study of 98 patients presenting with acute flank or abdominal pain or both was conducted to determine the diagnostic accuracy of ultrasound scan compared with excretory urography for the diagnosis of urinary tract calculi. All patients underwent standardized ultrasound scan and excretory urography as independent procedures. Two staff radiologists who reported the procedures were blinded to the results of the other diagnostic test and ultimate clinical outcome. All patients discharged home from the ED were followed to the hospital urology clinic. The diagnosis of urinary calculus was made only by identification of calculus at surgery or by reported passage of a stone by the patient. Of 85 patients available for follow-up study (56 men, 29 women; mean age, 40.5 years; range 18 to 77 years), calculi were identified in 69 (81%). Ultrasound identified calculi in 44 patients (sensitivity, 64%; specificity, 100%). Excretory urography identified calculi in 44 patients (identical sensitivity and specificity). When the presence of obstructive hydronephrosis only was used to diagnose renal calculi, ultrasound scan identified 59 patients (sensitivity, 85%; specificity, 100%) and excretory urography identified 62 patients (sensitivity, 90%; specificity, 94%). When the results of both diagnostic modalities were combined, calculi were identified in 59 patients (sensitivity, 85%; specificity, 100%) and hydronephrosis was seen in 66 patients (sensitivity, 95%; specificity, 94%). Our study shows that the diagnostic abilities of these procedures are equal in the detection of renal calculi.(ABSTRACT TRUNCATED AT 250 WORDS)

Renal Imaging With Dual Energy Projection Radiography

Applications of dual energy radiography to renal imaging were evaluated using an experimental system for line-scanned projection radiography. This system combines digital radiographs simultaneously obtained at two differing x-ray energies (85 and 135 kVp) to create images in which materials of a desired mean atomic number are selectively cancelled. A preliminary evaluation of the technique was performed for three renal imaging problems: detection and characterization of renal masses of low radiographic contrast, evaluation of renal artery stenosis and unilateral renal ischemia, and detection of renal calculi. In all three applications, the dual energy technique produced results indicating potential advantages over conventional radiographic studies.

Renal imaging with dual energy projection radiography.

Applications of dual energy radiography to renal imaging were evaluated using an experimental system for line-scanned projection radiography. This system combines digital radiographs simultaneously obtained at two differing x-ray energies (85 and 135 kVp) to create images in which materials of a desired mean atomic number are selectively cancelled. A preliminary evaluation of the technique was performed for three renal imaging problems: detection and characterization of renal masses of low radiographic contrast, evaluation of renal artery stenosis and unilateral renal ischemia, and detection of renal calculi. In all three applications, the dual energy technique produced results indicating potential advantages over conventional radiographic studies.

Intraoperative kidney radiography

Single and dual prepacked intraoperative kidney films (Kodak Eastman Company) were tested in experimental studies and were used in 45 patients for intraoperative detection of renal calculi. In 92.5% of patients (38/41) operative removal of calculi was verified, or the correct diagnosis of residual calculi by intraoperative radiography was confirmed by post-operative studies. From the diagnostic point of view, no real advantage of the dual films over the single prepacked films was seen.

Ultrasonic detection of renal calculi: accuracy tested in an in vitro porcine kidney model.

Porcine kidneys containing human calculi of known size and composition were used to study the ability of ultrasound to localize intrarenal calculi. The study conducted in a blind fashion demonstrated that stones as small as 2 mm could be detected. The chemical composition was not related to the ability to detect the stone. Early trials in the operating room have been encouraging. The porcine kidney model is useful for training purposes.