Radiation Exposure During Pediatric Videourodynamics

An innovative diagnostic procedure in children: videourodynamics with contrast-enhanced voiding urosonography

Contemporary videourodynamic (VUD) investigation combines voiding cystourethrography (VCUG) and urodynamics into one study, which allows simultaneous visualization of the urinary tract by ionizing radiation alongside the measurement of sensation, capacity, compliance, and detrusor pressure during bladder filling and voiding using one double lumen catheter. Today VUD is a benchmark for evaluating the lower urinary tract disorders in children because it evaluates urinary bladder and sphincter function and visualizes bladder morphology and vesicoureteral reflux (VUR) presence at the same time. Several previous studies of fluoroscopic videourodynamics issued concerns regarding radiation exposure. This technical report aims to describe a new modality of VUD in children by replacing fluoroscopic VCUG with contrast-enhanced voiding urosonography (ceVUS). ceVUS using second-generation contrast media and harmonic imaging is a radiation-free and highly sensitive imaging modality used to detect VUR in children. We simultaneously performed an infusion of ultrasound contrast through the double lumen urodynamic catheter during urodynamic evaluation. This article describes the advantages of this method compared with a conventional technique. In addition to being radiation-free, this procedure of advanced videourodynamics method can better detect vesicoureteral reflux and intrarenal reflux combined with urodynamic disorders associated with VUR.

Radiation exposure during videourodynamic testing: Is dose reduction possible using a standardized protocol?

AIMS

To evaluate the impact of a protocol for standardized image capture during video urodynamics (VUD) on radiation exposure. Secondly, to categorize radiation exposure by condition warranting VUD and to identify clinical variables that correlate with increased radiation exposure.

METHODS

One hundred fifty patients underwent VUD using our standardized protocol. All images were taken using low dose and pulsed settings. Four images are captured: one scout image, one filling image, one voiding image, and one post-void image. If the patient is unable to void with the catheter in place, the catheter is removed and a second image is taken during an attempt at unintubated flow. If vesicoureteral reflux (VUR) is identified, an alternate protocol is entered to document parameters. The mean radiation exposure measured in dose area product (DAP), fluoroscopy time, and number of images were noted and compared with previously published fluoroscopy data collected at our institution before protocol implementation.

RESULTS

The mean fluoroscopy exposure after the implementation of our protocol was 273.5 mGy/cm² taking 5.2 images in 4.5 seconds. Protocol implementation leads to a 51.2% reduction in radiation exposure calculated by mean DAP (P < .0001) and a 96.5% reduction in fluoroscopy time (P < .0001). The presence of VUR, fluoroscopy time, and body mass index (BMI) > 25 were associated with higher radiation exposure (P < .0001).

CONCLUSION

Implementation and adherence to a standardized protocol for fluoroscopy led to a reduction in radiation exposure fluoroscopy time. The presence of VUR, fluoroscopy time, and BMI > 25 were associated with higher radiation exposure.

Follow-up urodynamics in patients with neurogenic bladder

INTRODUCTION

Neurogenic bladder patients are at long-term risk of secondary upper urinary tract damage. Symptoms are unreliable and follow-up urodynamics is the only method of ascertaining safety of bladder pressures. This review examines the recommendations, shortcomings and utilization of existing guidelines. The evidence with regard to follow-up urodynamics in different settings relevant to neurogenic bladder is evaluated and an algorithm is proposed.

METHODS

A pubmed search was conducted for studies on follow-up urodynamics in patients with neurogenic bladder. Additional search was made of secondary sources including reviews and guidelines.

RESULTS

The need for follow-up urodynamics should be considered in all patients undergoing an initial assessment and weighed against the risks. Existing guidelines, while unanimous in their recommendation of its utilization, give scant details regarding its incorporation in clinical management. Follow-up urodynamics can document efficacy and identify the need for escalation of therapy in patients on intermittent catheterization and antimuscarinics. Patients with spinal injury, spinal dysraphism and anorectal malformations are at higher risk for upper tract damage. Follow-up urodynamics can help identify patients suitable for intravesical botulinum and mark those destined for failure. Patients undergoing augmentation cystoplasty may be candidates for less aggressive urodynamic follow-up.

CONCLUSIONS

Neurogenic bladder is managed by a broad cross-section of physicians. Clear recommendations and a management algorithm are important for improving patient care. Follow-up urodynamics can identify patients at risk, prevent renal dysfunction and improve the quality of life. There is an urgent need for more evidence on this important subject.

Radiation Exposure During Videourodynamics: Establishing Risk Factors

OBJECTIVES

The use of fluoroscopy during urodynamics can be helpful in the evaluation of patients with lower urinary tract dysfunction. However, fluoroscopy introduces the potential hazards of ionizing radiation, including malignancy. In this study we analyzed the data for radiation exposure during videourodynamic study (VUDS) at our center; we have also tried to establish the factors associated with increased exposure to radiation during VUDS.

METHODS

We reviewed all VUDS from August 2010 to May 2011. Patients were included if they were ≥18 years old and had data recorded on total radiation exposure (radcm² ). Age, sex, body mass index, fluoroscopy time, diagnosis, and urodynamic findings were recorded. Multivariate linear regression analysis was used to identify independent risk factors that influenced increased radiation exposure.

RESULTS

A total of 203 videourodynamic studies were assessed in 106 female and 97 male patients with a mean age of 64.3 and body mass index of 26.8. The average fluoroscopy time was 100.2 sec and exposure was 560.9 radcm² . The most common indication for videourodynamics was incontinence, 40.9%. On multivariate linear regression analysis body mass index, vesico-ureteral reflux, sex, number of fill cycles, and larger capacity were independent predictors of increased radiation exposure.

CONCLUSIONS

We have shown that increased radiation exposure as measure with Dose Area Product during VUDS was significantly associated with larger BMI, female gender, larger bladder capacity, presence of VUR, junior operator, and higher number of fill cycles. Further studies are now underway to attempt to reduce exposure based on these findings.

Effective and organ specific radiation doses from videourodynamics in children

PURPOSE

Effective and organ specific doses of ionizing radiation during videourodynamics are unknown. We estimated radiation exposure in children undergoing videourodynamics, and identified patient and examination factors that contribute to higher dosing.

MATERIALS AND METHODS

Fluoroscopy data were collected from consecutive patients undergoing videourodynamics. Documented dose metrics were used to calculate entrance skin dose after applying a series of correction factors. Effective doses and organ specific doses (ovaries/testes) were estimated from entrance skin dose using Monte Carlo methods on a mathematical anthropomorphic phantom (ages 0, 1, 5, 10 and 15 years). Regression analysis was performed to determine patient and procedural factors associated with higher dosing.

RESULTS

A total of 100 children (45% male, mean ± SD age 9.3 ± 5.7 years) were studied. Diagnoses included neurogenic bladder (73%), anatomical abnormality (14%) and functional/nonneurogenic disorder (13%). Mean fluoroscopy time was 0.17 ± 0.12 minutes. Mean age adjusted entrance skin dose, effective dose, and testis and ovary doses were 2.18 ± 2.00 mGy, 0.07 ± 0.05 mSv, 0.09 ± 0.10 mGy and 0.20 ± 0.13 mGy, respectively. On univariate analysis age, height, weight, body mass index, bladder capacity and fluoroscopy time were associated with effective dose. On multivariate adjusted analysis, body mass index, bladder capacity and fluoroscopy time were independently associated with effective dose.

CONCLUSIONS

The average effective dose of ionizing radiation from videourodynamics was less compared to voiding cystourethrogram dose reported in the literature. Greater fluoroscopy time, body mass index and bladder capacity are independently associated with higher dosing.