Ventral penile curvature estimation using an app

What is the angle of a banana? The difficulty in reliable assessment of hypospadias chordee

INTRODUCTION

The degree of chordee associated with hypospadias impacts operative management. Unfortunately, poor inter-observer reliability in assessing chordee by multiple methods in vitro has been demonstrated. This variability may be related to the fact that chordee is not a discrete angle, but rather an arc-like curvature similar to that of a banana. On an attempt to improve this variability, we assessed the inter-rater reliability of a novel method of chordee measurement and compared it to measurements with a goniometer both in vitro and in vivo.

MATERIALS AND METHODS

In vitro assessment of curvature was performed using 5 bananas. In vivo chordee measurement was performed during 43 hypospadias repairs. On in vitro and in vivo cases, chordee was assessed independently by faculty and resident physicians. Angle assessment was performed in a standard manner with a goniometer and with a smartphone app using ruler measurements of the length and width of the arc (Summary Figure). The proximal and distal aspect of the arc to be measured was marked on the bananas, whereas the penile measurements were taken from the penoscrotal to the sub-coronal junctions.

RESULTS

In vitro banana assessment demonstrated strong intra- and inter-rater reliability for length (0.89 and 0.88, respectively) and width measurements (0.97 and 0.96). The calculated angle demonstrated an intra- and inter-rater reliability of 0.67 and 0.67. The banana goniometer/protractor measurements were weak with an intra-rater and inter-rater reliability of 0.33 and 0.21. With hypospadias chordee, the inter-rater reliability was strong for length and width measurements (0.95 and 0.94) and 0.48 for calculated angle. The inter-rater reliability of the goniometer angle was 0.96. Further assessment of inter-rater goniometer reliability was performed relative to degree of chordee as characterized by faculty. The inter-rater reliability for ≤15°, 16-30, and ≥30° was 0.68 (n = 20), 0.34 (n = 14), and 0.90 (n = 9), respectively. When the goniometer angle was classified as ≤15, 16-30, or ≥30° by one physician, it was classified outside of this range by the other physician 23%, 47%, and 25% of the time, respectively.

DISCUSSION

Our data demonstrate significant limitations of the goniometer for assessing chordee in vitro and in vivo. We were unable to demonstrate significant improvement in chordee assessment using arc length and width measurements to calculate radians.

CONCLUSIONS

Reliable and precise techniques for measuring hypospadias chordee remain elusive and draw into question the validity and usability of management algorithms employing discrete values.

Unaided visual assessment of ventral curvature during hypospadias repair is inferior to objective measurement using app goniometry

OBJECTIVE

Failure to perform artificial erection or objectively assess ventral curvature (VC) during primary hypospadias repair is an important reason for residual/ recurrent chordee. The present study compares the accuracy of unaided visual inspection (UVI) with objective VC assessment using smartphone application (app) goniometry.

METHODS

All patients who underwent primary hypospadias repair between January 2021 and September 2022 were included. Assistant surgeons were asked to grade the degree of VC on UVI (after degloving and an artificial erection test) into: none, mild (<30 degree), severe(>30 degree). Lateral profile photograph was taken and angle measurement was performed on an android mobile application (Angulus). Correlation was performed with both methods of assessment.

RESULTS

During this period a total of 210 patients were analyzed; VC was noted in 40/138 (29%) cases of distal and in 62/72 (86%) cases of proximal hypospadias. Erroneous visual inspection was noted in 41/210 (20%; 95% CI 14-25%) on UVI (15 erroneously marked none while 26 marked mild). Among those found to have chordee, UVI assessed 39/82 (47%) as severe while app goniometry assessed 65/97 (67%) as severe. There was significant relative risk of labelling severe chordee as a mild one by UVI: 1.4 (95%CI 1-1.8; p=0.01).

CONCLUSIONS

UVI was erroneous in 20% of cases. UVI was less accurate in differentiating severe chordee from mild one. In 60% patients UVI alone could have led to erroneous VC assessment and thus wrong selection of technique. Further studies are required to validate our findings and standardize VC measurement using an app goniometry.

Automated measurement of penile curvature using deep learning-based novel quantification method

Objective

Develop a reliable, automated deep learning-based method for accurate measurement of penile curvature (PC) using 2-dimensional images.

Materials and methods

A set of nine 3D-printed models was used to generate a batch of 913 images of penile curvature (PC) with varying configurations (curvature range 18° to 86°). The penile region was initially localized and cropped using a YOLOv5 model, after which the shaft area was extracted using a UNet-based segmentation model. The penile shaft was then divided into three distinct predefined regions: the distal zone, curvature zone, and proximal zone. To measure PC, we identified four distinct locations on the shaft that reflected the mid-axes of proximal and distal segments, then trained an HRNet model to predict these landmarks and calculate curvature angle in both the 3D-printed models and masked segmented images derived from these. Finally, the optimized HRNet model was applied to quantify PC in medical images of real human patients and the accuracy of this novel method was determined.

Results

We obtained a mean absolute error (MAE) of angle measurement <5° for both penile model images and their derivative masks. For real patient images, AI prediction varied between 1.7° (for cases of ∼30° PC) and approximately 6° (for cases of 70° PC) compared with assessment by a clinical expert.

Discussion

This study demonstrates a novel approach to the automated, accurate measurement of PC that could significantly improve patient assessment by surgeons and hypospadiology researchers. This method may overcome current limitations encountered when applying conventional methods of measuring arc-type PC.

Pediatric urologists' confidence and accuracy in estimating penile curvature

BACKGROUND

Assessment and management of congenital penile curvature (PC) can be variable. Methods for correction of PC usually are dependent on degree of PC which is reliant on how degree is assessed. We sought to assess the confidence and accuracy of measuring PC and hence management using case-based examples.

METHODS

A survey was emailed to members of the Societies for Pediatric Urology. Demographic information, management strategies for PC, and self-reported confidence in measuring PC were assessed. A Likert scale measured self-confidence. Case scenarios were used to assess ability to measure PC and methods of correction. The cases consisted of three computer-generated penis model images with arc-type ventral curvature and one image of lateral curvature in an infant.

RESULTS

The response rate was 30% (108/355). The mean confidence score was 3.6 ± 0.8 (3-fairly confident; 4-very confident). In clinic, 89% of urologists used eyeball estimates to assess PC; 5% used both eyeball and goniometer. In the operating room, 71% used eyeball estimates, 8% used goniometer, and 16% used both. If sole decision-maker, urologists recommend surgical correction of PC over observation at median 30° (IQR 21-30°). At a median of 45°, there was a shift in corrective surgical preference from dorsal plication (DP) (IQR 30-54°) to ventral lengthening (IQR 34-60°). Urologists underestimated PC degree for all cases (summary table). For all cases, there was no association between years in practice or confidence level on estimated PC degree. In case 1, only 24% of urologists would correct a mean estimate of 23° PC; those who would correct had a higher mean PC estimate vs those who would not (28° vs 21°, p < 0.001). Case 2 and 4 had similar estimations and correction methods. In case 2, those who chose VL had a higher mean PC estimate vs those who did not (43° vs 37°, p < 0.01), but no estimate difference was seen for DP (p = 0.52). In case 4 with lateral PC, those who chose DP had a higher mean PC estimate vs those who did not (41° vs 33°, p = 0.049). Yet in case 3, there was no difference in PC estimate in urologists who chose VL vs not (57° vs 53°, p = 0.16).

CONCLUSIONS

A uniform underestimation of PC existed despite self-reported confidence in the ability to measure PC. An increasing willingness to perform surgical correction was demonstrated with a shift towards VL for ventral curvature and less so for lateral curvature as PC worsens.

How accurate is eyeball measurement of curvature? A tool for hypospadias surgery

INTRODUCTION

Correction of penile curvature or "chordee" is a major component in the management of hypospadias. Accurate assessment and management of penile curvature influence both short- and long-term outcomes of surgery.

AIM OF THE STUDY

The objective of this study is to investigate the accuracy of eyeball measurement and how does it compare to objective measurement by standard goniometry (SG) and smartphone app goniometry (AG).

MATERIALS AND METHODS

A Dropbox file request link was shared with paediatric urologists on various social media platforms requesting participants to upload a picture of their index finger showing what they thought 30 degrees of curvature look like using their proximal inter phalangeal joint as the point of maximal curvature., The images were assessed using SG to measure the angle of curvature. The images were also assessed using AG by the principal investigator, a physician, a scrub nurse and a paediatric urology consultant., Statistical analysis was performed using SPSS statistics software version 26 (Armonk, NY: IBM Corp). A one sample t-test and a one-way chi squared test were used to evaluate significant frequency differences. Pearson correlation was used to compare AG measurements to test intra- and inter-observer reliability and to compare AG measurements vs SG measurements. Assuming 5-degree variability in goniometer measurements and 2-degree difference between the sample and population, the number of participants needed was calculated to be 49.

RESULTS

Fifty-two responses were received.32.7% of respondents simulated 30° accurately (17/52). A significant proportion (23/52, 44.2%) overrepresented the degree of curvature and 23.1% (12/52) underrepresented it (p = 0.01). Compared with objective measures, eyeball estimates differed by an average of 10° ± 1.5 SE. Measurements obtained by AG were comparable to measures obtained by SG and showed excellent intra-observer and inter-observer correlation (R = 0.983, P < 0.001).

DISCUSSION

We demonstrated a significant discrepancy between eyeball assessment of curvature and objective measurements in a cohort of hypospadiologists. This can be very relevant to intraoperative decision making. The limitation of the study is the use of a simulated model rather than assessment of curvature in patients with hypospadias. Another limitation is the lack of standardization of the way the pictures were taken.

CONCLUSION

We demonstrated a tendency among hypospadiologists to overestimate or underestimate curvature by an average of 10° on eyeball assessment. The use of App Goniometry shows excellent interobserver reliability and is comparable to standard goniometry in curvature assessment.

Evaluation of penile curvature in patients with hypospadias; gaps in the current practice and future perspectives

BACKGROUND/PURPOSE

Penile curvature (PC) is a significant phenotypic anomaly associated with hypospadias that can affect hypospadias repair post-operative outcomes and impact on long-term quality of life as well as psychosexual wellbeing of affected patients. While several previous studies have attempted to define PC assessment criteria, there is still no accurate, reproducible, and reliable tool for quantifying severity. Our goal was to review the pros and cons of the current tools utilized for assessing the degree of PC in children, stressing on both strengths and limitations of each method.

METHODS

A wide and deliberate review of the literature discussing the assessment of PC in hypospadias patients was conducted. We also draw on relevant methods employed in adults with PC and Peyronie's disease where a greater breadth of studies has been conducted.

RESULTS

The appraisal outcomes combined with our recommendations were presented in a structured approach discussing the pre-, intra-, and post-operative evaluation of PC in patients with hypospadias. Critical appraisal of the evaluation tools in terms of availability, cost, objectivity, and potential reproducibility was presented.

CONCLUSION

This review reflects on current tools used for assessing the degree of PC in children, highlighting both strengths and limitations of each method. A wide variety of approaches are currently being practiced or investigated, with each method displaying particular utility and reliability characteristics. Several approaches are currently being explored with high potential to overcome the current difficulties encountered when measuring PC both in clinical practice and research studies.

Surgical management of primary severe hypospadias in children: an update focusing on penile curvature

Over the past two decades, assessment and treatment of associated curvature has emerged as a major issue in treating patients with proximal hypospadias. However, the cut-off for defining a curvature as clinically significant is still unclear, as not all patients are bothered by the same degree of curvature and, although the need for a method to assess the curvature objectively has been emphasized, no standard method yet exists. Curvature is multifactorial. The same degree of curvature can be due to any possible combination of skin and/or subcutaneous dartos tethering, a short urethral plate and an intrinsic corpora disproportion. Different strategies can be used to treat curvature, depending on the underlying cause, surgeon preferences, and the goals of the repair. In the past 10 years, use of urethral plate transection and ventral lengthening procedures has increased, although the lack of long-term follow-up data on ventral lengthening procedures suggests that the use of such procedures should be selective. Furthermore, straightening manoeuvres are influenced by the technique used for subsequent urethroplasty and, in turn, may influence the success rate of the urethroplasty. This Review provides a comprehensive overview of the major developments from the past 10 years in the management of severe proximal hypospadias in children.