AIUM practice guideline for the performance of an ultrasound examination in the practice of urology

Predictive value of contrast-enhanced ultrasound combined with conventional ultrasound in solid renal parenchymal lesions

OBJECTIVE

This study aimed to develop a model to predict the risk of malignancy in solid renal parenchymal lesions based on the imaging features of combined conventional and contrast-enhanced ultrasound (CEUS).

METHODS

A retrospective review was performed among patients with focal solid renal parenchymal lesions on ultrasound images. Ultrasound features were characterized by two experienced radiologists independently. A multiple logistic regression analysis was performed to determine the most relevant features and to estimate the risk of malignancy. Scoring and counting methods were developed based on the most relevant features. The diagnostic performance was evaluated by the sensitivity, specificity, positive predictive value, negative predictive value and area under the receiver operating characteristic curve (AUC).

RESULTS

A total of 519 renal lesions were included in this study. The conventional ultrasound features of diameter, echogenicity, hypoechoic rim and the CEUS feature of heterogeneity were identified as the most relevant features for prediction of malignancy. The sensitivity and specificity for the logistic regression model, the scoring method and the counting method were 95.3 and 93.4%, 93.8 and 87.8%, 88.8 and 93.9%, respectively. The logistic model had the best performance for diagnosing malignant renal lesions with AUC of 0.978, compared with the scoring method and the counting method with AUCs of 0.958 and 0.965.

CONCLUSION

The combination of contrast-enhanced ultrasound with conventional ultrasound improved the diagnostic performance of solid renal lesions based on the logistic regression model.

ADVANCES IN KNOWLEDGE

In this study, we revealed that the combination of CEUS and conventional ultrasound provided higher accuracy for diagnosing malignant renal tumors.

Ureter Visualization With Transvaginal Ultrasound: A Learning Curve Study

OBJECTIVES

To evaluate the learning curve of gynecologic surgical fellows (ie, in training) to properly identify the ureters in real time while simultaneously performing and interpreting transvaginal ultrasound (TVUS) examinations.

METHODS

We performed a prospective study, which took place at 2 centers in Sydney, Australia, from December 2017 to December 2018. Three fellows (F1-F3), of varying prestudy ultrasound (US) experience, were recruited to participate. One hundred fifty predetermined examinations were planned. A TVUS examination was performed by the study reference standard (an expert in gynecologic US). Subsequently, the fellows performed a focused component to identify bilateral ureters, having been blinded to the patient's clinical history and reference standard findings. Immediate feedback and hands-on teaching were provided after each of the fellow's evaluations were complete. To evaluate the number of scans needed to gain competency, the cumulative summation test for the learning curve was used.

RESULTS

A total of 150 examinations were performed on 145 patients. One patient had a single ureter, and 1 patient had US evidence of hydroureter. The cumulative summation test for the learning curve for bilateral ureter identification showed that F1 did not reach competency by 50 TVUS examinations, whereas F2 and F3 required 41 and 31 TVUS examinations to reach competency, respectively.

CONCLUSIONS

Contrary to other studies on the topic, this study suggests that although it is feasible for surgical fellows to learn TVUS identification of bilateral ureters, not all fellows can reach competency during a program based on a predefined number of scans. We advocate for an individualized, competency-based medical education model in learning US for identifying the ureters.

National Imaging Trends of Recurrent Pediatric Urolithiasis

OBJECTIVES

The aim of this study was to examine computed tomography (CT) and ultrasound (US) utilization trends in incident and prevalent pediatric emergency department (ED) urolithiasis patients before and after imaging guideline release.

METHODS

We reviewed imaging modalities for children with 2 or more ED encounters between January 1, 2006, and September 1, 2013, for urolithiasis using the Pediatric Health Information System database. Z scores compared the proportion of patient encounters receiving CT and US before (January 1, 2006, to December 31, 2010) and after (January 1, 2011, to September 1, 2013) the release of imaging guidelines. McNemar test for paired proportions compared the percentage of US and CT use between initial versus subsequent visits. Piecewise logistic regression was used to determine the probability of US use and CT use over time before and after the implementation of imaging guidance.

RESULTS

Analysis was completed on 2041 patients with 4930 unique encounters for urolithiasis. During 1758 encounters (35.7%), CT was performed initially. Ultrasound was performed 1585 times (32.2%). Fourteen percent fewer CT procedures were performed during first urolithiasis visits after guideline release (P < 0.01), whereas US use increased by 15% (P < 0.01). Fewer CT procedures were performed at later visits compared with the first (P < 0.05), and US was used more during second or later visits than the first (P < 0.05).

CONCLUSIONS

Medical providers at large academic pediatric EDs have decreased use of CT and increased use of US over the study time frame to diagnose urolithiasis and are now similar during initial visits (US 36.4% vs CT 36.2%, P = 0.94). Physicians are still more likely to use US as the initial urolithiasis imaging modality during second and later encounters.

Diagnostic Performance of Ultrasound Shear Wave Elastography in Solid Small (≤4 cm) Renal Parenchymal Masses

The aim of the study was to analyze the diagnostic performance of shear wave elastography (SWE) in differentiating between malignant and benign solid renal parenchymal masses ≤4 cm, compared with conventional ultrasound. A total of 20 healthy volunteers and 117 patients had been included in this study. Conventional ultrasound and SWE were performed in all volunteers and patients. The elasticity of healthy cortex and the elastic parameters of tumors such as mean elasticity (E_mean), minimum elasticity (E_min), maximum elasticity (E_max), standard deviation and elasticity ratio of the lesion to surrounding cortex (E_ratio) were measured on SWE images. Diagnostic performance of SWE was compared with that of conventional ultrasound. The cortical elasticity values of healthy right and left kidneys were 4.7 ± 1.7 and 4.5 ± 1.5 kPa, respectively. Of the 117 renal tumors, 68 were renal cell carcinomas (RCCs) and 49 were benign. E_mean, E_min and E_ratio were significantly lower in RCCs compared with benign lesions: E_mean 7.2 ± 2.5 kPa versus 10.0 ± 2.4 kPa, E_min 2.5 ± 2.4 kPa versus 5.6 ± 2.3 kPa, E_ratio 1.6 ± 0.5 versus 2.2 ± 0.6 (all p values < 0.001). The cutoff values of 9.15 kPa for E_mean, 3.55 kPa for E_min and 1.99 for E_ratio had the highest areas under the receiver operating characteristics curve (0.801 for E_mean, 0.832 for E_min and 0.806 for E_ratio). Combining E_mean, E_min and E_ratio with conventional ultrasound improved the specificity for predicting RCCs to 87.8%, but the sensitivity was not increased.

Variability in penile duplex ultrasound international practice patterns, technique, and interpretation: an anonymous survey of ISSM members

Penile duplex ultrasound (PDU), combined with pharmacologic stimulation of erection, is the gold standard for the evaluation of multiple penile conditions. A 30-question electronic survey was distributed to members of the International Society for Sexual Medicine (ISSM). The survey assessed the variability in current PDU practice patterns, technique, and interpretation. Chi-square test was used to determine the association between categorical variables. Approximately 9.5% of all 1996 current ISSM members completed the survey. Almost 80% of members surveyed reported using PDU, with more North American practitioners utilizing PDU than their European counterparts (94% vs 69%, p < 0.01). Approximately 62% of PDU studies were performed by a urologist and more than 76% were interpreted by a urologist. Although almost 90% of practitioners reported using their own protocol, extreme variation in the technique existed among respondents. Over ten different pharmacologic mixtures were used to generate erections, and 17% of respondents did not repeat dosing for insufficient erection. Urologists personally performing PDU were more likely to assess the cavernosal artery flow using recommended techniques with the probe at the proximal penile shaft (73% vs 40%) and at a 60-degree angle or less (68% vs 36%) compared with non-urologists (p < 0.01). Large differences in PDU diagnostic thresholds were apparent. Only 38% of respondents defined arterial insufficiency with a peak systolic velocity < 25 cm/s, while 53% of respondents defined venous occlusive disease with an end diastolic velocity > 5 cm/s. This is the first study to assess the variability in the PDU protocol and practice patterns, and to pinpoint areas of improvement. As in other surveys, recall bias, generalizability, and response rate (9.5%) are inherent limitations to this study. Although most respondents report utilizing a standardized PDU protocol, widespread variation exists among practitioners in terms of both technique and interpretation, limiting accurate diagnosis and appropriate treatment of penile conditions.

Office ultrasound for the urologist

Imaging of the genitourinary tract is essential in the workup of the majority of the conditions seen daily by urologists. The use of ultrasound in the office provides a safe, low cost, and efficient way for the clinician to evaluate the patient in real time. Ultrasound can allow for bedside diagnosis in many conditions and assist in treatment planning. This chapter covers the major applications of office ultrasound for the urologist as well as discusses future applications of ultrasound for the office setting.