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Keywords:

  • bladder outlet obstruction;
  • Doppler ultrasonography;
  • fluid dynamics;
  • non-invasive;
  • pediatric urodynamics;
  • urodynamic study

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Uroflowmetry
  5. Non-urodynamic parameters
  6. The indirect measurement of bladder pressure
  7. Perineal noise recording
  8. Transperineal Doppler ultrasound videourodynamics
  9. Improving image-processing computer program
  10. Overcoming the rare chance to record micturition images
  11. Indications of Doppler ultrasound videourodynamics
  12. Conclusion
  13. References

A totally non-invasive transperineal urodynamic technique using Doppler ultrasonography has been developed. Normal urine doesn't have blood cells so urine was thought not to produce Doppler effects. However, basic studies confirmed that the decrease of pressure at high velocity (Bernoulli effects) caused dissolved gas to form microbubbles, which are detected by Doppler ultrasonography. Subjects sat and a probe was advanced via remote control to achieve gentle contact with the perineal skin. The digital uroflow data signals and the color Doppler ultrasound video images were processed on a personal computer. This method was viable to diagnose the degree of bladder outlet obstruction. The advantage of being rapid, effective, and equipped with no special attachments allows it to surpass any other non-invasive urodynamic methods. The difference between the echocardiogram and the ultrasound urodynamic system is only the frequency of obtaining velocity information: more than 50 times per minute vs once every several hours, respectively. Although the ultrasound urodynamic system is more difficult to develop than the echocardiogram, one principle is shared by both methods. The patient can void freely without interruptions, there is no contact between the penis and the equipment and it is specifically directed toward non-invasive diagnosis. The development of non-invasive Doppler ultrasound videourodynamics will dramatically expand understanding of voiding function.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Uroflowmetry
  5. Non-urodynamic parameters
  6. The indirect measurement of bladder pressure
  7. Perineal noise recording
  8. Transperineal Doppler ultrasound videourodynamics
  9. Improving image-processing computer program
  10. Overcoming the rare chance to record micturition images
  11. Indications of Doppler ultrasound videourodynamics
  12. Conclusion
  13. References

Does it hurt? No! Not a bit

Our echo urodynamic system is a quick and easy way to observe your urinating function, as well as the urine flow. The machine we use is much the same as one used to scan the heart. Shortly after your arrival in the urodynamic department, you will be shown into a curtained cubicle and asked to change your clothes below the waist into special clothing for the examination. You will then be asked to be seated on a specially equipped lavatory chair.

First, we will apply a small amount of gel to an ultrasound probe, and then we will use a remote control robotic arm with the probe up against the perineal region – between your scrotum and anus – on the lavatory chair. A small quantity of gel will then be attached to your perineum (which might feel a bit cold), and the probe will slide over your skin. Please tell the doctor or technician if the probe is applying too much pressure. The probe allows us to see images of your lower urinary tract on a monitor. These images are recorded, so that they can be reviewed later. There may also be a Doppler examination, to give us more information on urine flow through your urethra. It is important that you urinate as usual, and we will try our best to ensure that you can. If you can pass urine in adequate time, the process will be finished in less than 5 min.

When the examination is finished, you will be given some tissue to wipe off the gel and when you are ready you may dress and leave. If you have any comments or suggestions on how we can improve our echo urodynamic service, please contact one of the staff.

Detrusor pressure measurement hurts

The paragraphs above are patient instructions for non-invasive ultrasound videourodynamic study in the near future. The development of non-invasive urodynamic study is the dream of urologists. Urodynamics is the field of urology involving the study of the function and dysfunction of the urinary tract by appropriate methods.1 It encompasses the morphological, physiological, biochemical and hydrodynamic aspects of urine transport. Urodynamic study has historically been developed mainly as a measurement of the detrusor pressure. Unfortunately, there are several limitations of detrusor pressure measurement that cannot be overcome with current technology.2 The biggest critique is that two catheters, ranging in size from 4 to 12 French are required to measure bladder pressure and rectal pressure during the study. The urodynamic catheter used causes significant artifacts including decreased flow-rate, increased voiding pressure, and it alters and inhibits the normal voiding reflex. Many patients simply cannot void during the pressure-flow studies. Attempts have been made to perform pressure-flow studies using a temporary suprapubic catheter. This invasive procedure increases cost, pain to the patient, and risk of injury to the bladder and adjacent organs. The suprapubic tube also alters bladder sensation and can alter normal micturition reflex. Moreover, it not only causes significant discomfort but also usually does not guarantee patient privacy.3

Until recently, practical use of a non-invasive urodynamic method has not been commercially available. However, the future of urodynamic studies should evaluate dynamic function of the lower urinary tract non-invasively. Therefore, there remains a need for a safe and accurate diagnostic test. In this review, we focus on non-invasive, dynamic, functional examination of the lower urinary tract.

Uroflowmetry

  1. Top of page
  2. Abstract
  3. Introduction
  4. Uroflowmetry
  5. Non-urodynamic parameters
  6. The indirect measurement of bladder pressure
  7. Perineal noise recording
  8. Transperineal Doppler ultrasound videourodynamics
  9. Improving image-processing computer program
  10. Overcoming the rare chance to record micturition images
  11. Indications of Doppler ultrasound videourodynamics
  12. Conclusion
  13. References

Uroflowmetry should be regarded as a basic clinical urodynamic test. Urinary flow-rate measurement is useful in the initial diagnostic assessment and during or after treatment to determine response. Because of the non-invasive nature of the test and its clinical value, it is recommended as part of the specialized evaluation to be performed before embarking on any active therapy. Maximum flow-rate (Qmax) is the best single measure but low Qmax does not distinguish between obstruction and decreased detrusor contractility. Invasive pressure flow studies are proven value in the evaluation of patients before invasive therapies, or when a precise diagnosis of bladder outlet obstruction is important.4 Because of intra-individual variability and volume dependency of the Qmax, at least two flow-rate measurements are preferable, ideally both with a volume greater than 150 mL of voided urine. The main uroflowmeters in use today employ the weight transducer and rotating disc techniques. Following our report that velocity measurement was proven to be possible for fluid containing no particles like urine, ultrasound flow measurement can make it possible to extend this tool to neonates and infants.5–8

The measurement of post-void residual urine is also useful in the initial diagnosis and during subsequent monitoring as a safety parameter. Because of the marked intra-individual variability of residual urine volume, the test is limited in its clinical usefulness.9

Non-urodynamic parameters

  1. Top of page
  2. Abstract
  3. Introduction
  4. Uroflowmetry
  5. Non-urodynamic parameters
  6. The indirect measurement of bladder pressure
  7. Perineal noise recording
  8. Transperineal Doppler ultrasound videourodynamics
  9. Improving image-processing computer program
  10. Overcoming the rare chance to record micturition images
  11. Indications of Doppler ultrasound videourodynamics
  12. Conclusion
  13. References

Prostatic volume

Although there have been many attempts to develop non-invasive non-urodynamic methods using ultrasound B-mode, such as prostate volume, bladder wall thickness and intravesical prostatic protrusion, these tests are not sufficient to diagnose bladder outlet obstruction during voiding.3 The diagnostic accuracy of prostatic volume more than 40 mL against bladder outlet obstruction confirmed by pressure flow study is low in specificity (49%) and low in sensitivity (32%).10

Ultrasound detrusor wall thickness measurements

Basic knowledge about changes in the human bladder as a result of bladder outlet obstruction (BOO) has been obtained from an experimental animal study in which a suture was placed around a catheterized urethra and an increase of urethral resistance occurred after catheter removal.11 Thickening of the detrusor occurs as a result of BOO similar to the heart in which the muscular wall thickens due to valve stenosis or arterial hypertension.12

Ultrasound studies in human bladders demonstrated that all parts of the bladder have the same thickness in one individual.13 Ultrasound measurement of detrusor wall thickness should be performed at the anterior bladder wall with a 7.5-MHz array scanner. Detrusor wall thickness increases with increasing obstruction grade. The diagnostic accuracy of ultrasound detrusor wall thickness is high in specificity (92%) and low in sensitivity (54%).14 A certain overlap between detrusor wall thickness measurements in men with or without BOO is responsible for the difficult definition of an accurate threshold value for BOO diagnosis.11 As some neuropathic detrusor dysfunction also causes detrusor wall thickness, this method cannot diagnose BOO accurately.

Intravesical prostatic protrusion

By measuring the vertical distance from the tip of the protrusion to the circumference of the bladder at the base of the prostate gland, intravesical prostatic protrusion (IPP) correlated well with parameters obtained from conventional pressure flow study.15 But IPP is an anatomical parameter and cannot indicate some types of BOO, namely, those not associated with mechanical obstruction due to benign prostatic enlargement.

The indirect measurement of bladder pressure

  1. Top of page
  2. Abstract
  3. Introduction
  4. Uroflowmetry
  5. Non-urodynamic parameters
  6. The indirect measurement of bladder pressure
  7. Perineal noise recording
  8. Transperineal Doppler ultrasound videourodynamics
  9. Improving image-processing computer program
  10. Overcoming the rare chance to record micturition images
  11. Indications of Doppler ultrasound videourodynamics
  12. Conclusion
  13. References

Penile cuff

Infravesical obstruction is by definition assessed from a correlation between pressure and flow-rate. Using a small inflatable cuff around the penis, urinary flow can be blocked. In an analogy with blood pressure measurements and simultaneous monitoring uroflowmetry, it can be possible to estimate the pressure in the penile urethra by slowly inflating or deflating the cuff until flow stops or starts.16 In this method, the patient cannot void freely without involuntary interruptions. Measuring pressure simulates not detrusor pressure, but bladder pressure. It was also noted that occasionally patients were unable to relax the sphincter to void against the occlusion provided by the cuff, resulting in an inappropriately low pressure.17

Condom catheter

By attaching a pressure transducer to an incontinence condom applied to the penis, bladder pressure might be measured non-invasively. Patients can be asked to try to initiate voiding through a tube attached to the condom, which is closed at some instant during voiding to measure pressure.18 During condom catheter measurements, involuntary interruption of voiding increases post-void residual volume.19 The patient cannot void freely with interruptions, there is contact between the penis and the equipment and it is unfavorable for diagnosing BOO.

Perineal noise recording

  1. Top of page
  2. Abstract
  3. Introduction
  4. Uroflowmetry
  5. Non-urodynamic parameters
  6. The indirect measurement of bladder pressure
  7. Perineal noise recording
  8. Transperineal Doppler ultrasound videourodynamics
  9. Improving image-processing computer program
  10. Overcoming the rare chance to record micturition images
  11. Indications of Doppler ultrasound videourodynamics
  12. Conclusion
  13. References

Perineal noise recording may be based on voiding with a microphone attached against the perineum between the scrotum and anus. A major advantage of such a diagnostic method is simplicity. The development of this non-invasive technique for diagnosing lower urinary tract symptoms started in the mid-1960s with a voiding audiograph.20 It was hypothesized that urinary flow is turbulent at the bladder neck. These turbulences cause pressure fluctuations on the urethral wall that can be recorded as noise transmitted via the urethra to the skin. It was also hypothesized that this perineal noise is related to the degree of bladder outlet obstruction. However, the precise relation between perineal recorded noise during voiding and the degree of obstruction is far from correlated. There are many factors besides the degree of obstruction that could influence the recorded noise, for example viscoelastic properties and thickness of the urethral wall and tissue surrounding the urethra.21

Auscultation as noise recording of the heart has a longer history in cardiology than urethral noise recording in urology. Cardiac auscultation was originally reported by Harvey in 1616.22 Over almost 400 years, cardiac auscultation developed with the phonocardiograph, which was an instrument consisting of microphones and recording equipment used to monitor and record heart sounds and murmurs. The phonocardiograph had been one of the main diagnostic tools alongside X-ray, electrocardiograph and coronary angiography, which all received Nobel Prizes.23,24 But in the last 40 years since development of the echocardiogram, the phonocardiograph has become a historical artifact, restricted to fetal phonocardiography. An echocardiogram is a totally safe and painless ultrasound examination. It uses high frequency sound waves to form a picture of the valves and chambers of the heart. Although the phonocardiographic methods might be non-invasive and inexpensive, clinical application of these methods has been overtaken by echocardiogram, which provides overwhelming anatomic information and hemodynamic data. Considering the same principle, clinical application of perineal noise recording might be supplanted by the development of Doppler ultrasound urodynamics.

Transperineal Doppler ultrasound videourodynamics

  1. Top of page
  2. Abstract
  3. Introduction
  4. Uroflowmetry
  5. Non-urodynamic parameters
  6. The indirect measurement of bladder pressure
  7. Perineal noise recording
  8. Transperineal Doppler ultrasound videourodynamics
  9. Improving image-processing computer program
  10. Overcoming the rare chance to record micturition images
  11. Indications of Doppler ultrasound videourodynamics
  12. Conclusion
  13. References

Basic principle of Doppler ultrasound videourodynamics

We are developing Doppler ultrasound videourodynamics, which can diagnose bladder outlet obstruction, and provide much more information as well.6 Why did we apply Doppler ultrasound? Using Doppler ultrasonography, flow-velocity can be measured. We can obtain flow-rate through the urethral meatus using a flow meter. We assume that flow-rate divided by flow-velocity in adequate phase represents the functional cross-sectional area of the urethra, which is directly correlated with obstruction (Fig. 1). But the use of Doppler ultrasonography has never been assessed previously with regard to velocity measurement in the urethra. General thinking has assumed that flow without particles could never provide the Doppler effects.25 During normal bodily Doppler ultrasonography, blood cells are playing a great role in producing the Doppler effects.26 As normal urine doesn't have blood cells, urine was thought not to produce the Doppler effects. However, we demonstrated practically that these assumptions were false.

image

Figure 1. Significance of flow-velocity during voiding. Flow-rate can be contained through the urethral meatus using a flow meter. Flow-rate (Q) divided by flow-velocity (v) in adequate phase is assumed to represent the functional cross-sectional area of the urethra (A), which is a direct parameter of obstruction. Obstruction can then be predicted by cross-sectional area measurement.

Download figure to PowerPoint

When we tried to attach the ultrasound probe at the perineal region, the urinary stream in the male urethra could be clearly detected.5 How can Doppler signals be obtained from urine without particles? We hypothesize that microbubbles formed in liquid and/or tiny particles in the urine during flow are responsible for creating the Doppler effects based on Bernoulli's principle.27 Bernoulli's principle states that where the velocity of a fluid is high, the pressure of the flow becomes low, and where the velocity is low, the pressure becomes high.28 Dissolved gasses will be reformed to microbubbles by a decrease in pressure or increase in temperature.29 As the temperature is stable in the urethra, decreased pressure due to a high velocity reforms dissolved gasses into microbubbles, which may contribute to the Doppler effect.5

Doppler ultrasound videourodynamic system

We used an ultrasonic image-directed color Doppler system (SSD-5500; Aloka), composed of a 3.75-MHz micro-convex electroprobe for this study. The probe holder is remotely controlled by a robotic arm to obtain a frontal plane angle of the urinary stream. Subjects sat on a uroflow micturition chair. The ultrasound probe was covered with solid echogel and advanced via remote control to achieve gentle contact with the patient's perineal skin (Fig. 2). Natural micturition was observed under ultrasound monitoring. Uroflow-rates from urethral meatus were measured with a uroflowmeter (Urocap-2; Laborie Medical Technology). This prototype system was designed to measure both flow-velocities in the urethra and flow-rate simultaneously. The digital uroflow data signals and the color Doppler ultrasound images were processed on a personal computer. The Doppler angle, the angle between the flow direction and the direction of sound propagation, was also measured and angle correction was performed. The flow-velocity curves from two sites, the distal prostatic urethra just above the external sphincter (S1) and the sphincteric urethra (S2), were plotted against time (Fig. 3). The maximum flow-velocities at both sites (V1 representing the velocity at S1, V2 that at S2) were recorded at the same instant. From these data, the velocity ratio (VR = V1/V2), and the functional cross-sectional area at S1 (A1) were computed from the following formula: A1 = Qmax/V1.30

image

Figure 2. Schematic overview of non-invasive ultrasound (US) videourodynamics. The US probe was operated by a specially-equipped remote controlling robotic device. The color Doppler flow image, flow-velocity curve and flow-rate curve were displayed on the computer monitor. VF, velocity-flow.

Download figure to PowerPoint

image

Figure 3. Voiding analysis of a case with benign prostatic enlargement: Left lower portion: A retrieved picture obtained from Doppler ultrasound, which demonstrated enlarged prostatic nodule. Note, although the proximal urethra was clearly identified from the prostatic nodule, the proximal site of the prostatic urethra did not show a Doppler signal. Right lower portion: Flow-velocity curve obtained by Doppler ultrasound. Right upper portion: Flow-rate curve obtained by uroflowmetry. Calculated parameters appear on left upper portion. S1, S2: Sample volume.

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Comparison to conventional pressure-flow study

We have been conducting a clinical investigation in order to develop accurate Doppler ultrasound urodynamic parameters that correlated best with urethral resistance measured by pressure-flow study (PFS). An investigator conducted both PFS according to both the International Continence Society Guidelines and the Doppler ultrasound urodynamics.31 Urethral resistance was quantified using the bladder outlet obstruction index (BOOI), in the following formula: BOOI = PdetQmax-2 × Qmax, where PdetQmax is the detrusor pressure at the maximum flow-rate and Qmax is the maximum flow-rate using PFS.32 Based on the BOOI, bladders were categorized as obstructed (BOOI more than 40), equivocal (20–40), or unobstructed (less than 20). Figure 2 illustrates the Doppler ultrasound urodynamics of a case with benign prostatic enlargement.

Men who have various degrees of obstruction were compared along the parameters of both PFS and Doppler ultrasound urodynamic studies. VR was the parameter having the best correlation with BOOI (Spearman's rho = 0.728; P < 0.001), although A1 had a similar correlation (rho = –0.708; P = 0.001). All men with VR exceeding 1.6 were in the obstructed group. Similarly, all men with below 1.0 were equivocal or unobstructed. This means that although flow was accelerated through the sphincter in the unobstructedgroup and the equivocal group, flow-velocity was reduced through the sphincter in the obstructed group.30

Ding reported that the retest correlation using Spearman's rho for VR in terms of intrarater and interrater reliability was 0.95 and 0.57, respectively; and that for A1 was 0.97 and 0.64, respectively.33 In a recent report by Nose this non-invasive urodynamics has better correlation with obstruction than the other non-invasive method using transabdominal ultrasound of the IPP.34 We found that non-invasive velocity flow urodynamic evaluation based on Doppler ultrasound was viable to diagnose BOO with reasonable reliability.35

Improving image-processing computer program

  1. Top of page
  2. Abstract
  3. Introduction
  4. Uroflowmetry
  5. Non-urodynamic parameters
  6. The indirect measurement of bladder pressure
  7. Perineal noise recording
  8. Transperineal Doppler ultrasound videourodynamics
  9. Improving image-processing computer program
  10. Overcoming the rare chance to record micturition images
  11. Indications of Doppler ultrasound videourodynamics
  12. Conclusion
  13. References

We initially developed custom software run on a personal computer using Microsoft Windows 95 (Microsoft). Information on Doppler shift frequencies derived from different flow-velocities were converted to color-encoded data using SSD-5500 (Aloka) system software. These color-scale data were recorded as a picture each 0.5 s, then analyzed by a custom software (API-TOOL; Contec) run on a personal computer (GL5133; Celebris). Multiple rectanglular sample volumes can be set in any size at any point around the bladder and the urethra. The color-coded data of each nine pixels/1 mm2 in the sample volume were averaged to reduce technical artifacts. This calculation was performed every 0.5 s and a flow-velocity curve in the region of interest was obtained. The Doppler angle was also measured and the angle correction was performed to detect each flow-velocity vector.

We have developed a new version of the program accompanying the advent of a new operating system. This program works on any personal computer running either Microsoft Windows XP or Windows Vista (Microsoft). Accompanying this, automatic measures of velocity-flow urodynamic parameters using the same principle of the former version and corresponding flow-rates during complete voiding can now be plotted against each other on an x–y graph, which will be reported elsewhere.

Overcoming the rare chance to record micturition images

  1. Top of page
  2. Abstract
  3. Introduction
  4. Uroflowmetry
  5. Non-urodynamic parameters
  6. The indirect measurement of bladder pressure
  7. Perineal noise recording
  8. Transperineal Doppler ultrasound videourodynamics
  9. Improving image-processing computer program
  10. Overcoming the rare chance to record micturition images
  11. Indications of Doppler ultrasound videourodynamics
  12. Conclusion
  13. References

Echocardiogram has been established as the most popular diagnostic method for non-invasive measurement of cardiac function. Many cardiac physicians and ultrasonographers are using this technique for evaluating heart disease in most cardiac specialized clinics worldwide. Doppler ultrasonography has been widely used for evaluating blood-flow-velocities. On the other hand, few urologists in only a few academic centers use this imaging modality to study urodynamics. Urine normally contains no blood cells so urinary flow was presumed not to create the backscattered signals that are essential for Doppler flow imaging.25 We demonstrated that normal urine contains enough echodense microbubbles to allow clear visualization through Doppler ultrasonography.3,27 The contrast material is not necessary. Although heart examiners have the chance to measure velocity more than 50 times per minute, one can measure urine velocity during micturition only once every several hours. Voiding observation using a probe held manually by the examiner is not sufficient to obtain urinary flow information just once every several hours. We should never miss the images during voiding of the patient. For this purpose, a high-quality transperineal robotic probe manipulator and the above-mentioned computer program are required. The transperineal robotic probe manipulator also helps to attach the probe to the perineal region when the patient is in a sitting position without violation of the patient's privacy. Initially a simple probe holder with forward/backward, right/left and upward/downward movements was developed (Fig. 4).

image

Figure 4. A specially-devised perineal ultrasound probe robotic holder. Subjects sit on a uroflow micturition chair. The ultrasound probe is covered with echo gel and advanced via remote control to achieve gentle contact with the patient's perineal skin. Manipulating touch panel on the position indicator (arrows).

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Although we are making improvements to the remote control robotic manipulator, urologists may still have difficulty conducting the same procedure in their own practices. Recently, we have been using a new model with a pressure-regulating function and a touch-panel manipulator on the display panel accompanying the probe position indicator. With the prototype manipulator, probe orientation was sometimes lost when an examiner manipulated the probe just before the examination. We could hardly see the probe position beneath the patient's buttock. The ultrasound monitor could not provide sufficient information to orient the probe position. For this reason, we concluded that the manipulator needed a position indicator. One push button would correspond to returning the probe to the home position, the center of the lavatory chair. A pressure regulating function was also seen as necessary, because otherwise patients would complain of perineal discomfort, or else the ultrasound monitor image would be blurred. The usefulness of this new model with the two above functions of pressure regulation and touch panel manipulation on the display panel accompanying probe position indicator will be reported elsewhere.

Ideally the remote control robotic manipulator should be able to adjust to an adequate probe position before micturition, regardless of whether the examiner is skilled or not in manipulating the probe. Practically, this aiming process is relatively easier for a skilled examiner than it is for a beginner at this examination. However, there have recently been many amazing developments in technology for digital cameras and camcorders. Small signal processing and control units can find and track up to several human faces in one frame, and controls exposure and flash to ensure proper illumination of the faces as well as the rest of the frame, reducing the detrimental effect of over- or underexposed faces in a photo (http://en.wikipedia.org/wiki/DIGIC). Considering the same principle, this technology can help overcome the difficulties in recording micturition images. If similar signal processing and control units were incorporated into the remote control robotic manipulator, transperineal ultrasound images of the prostatic urethra could be recognized by the processing unit and the control unit could move and set the probe automatically before micturition. As these processes might not be as quick as a digital camera, and no more than one prostatic urethra would need to be tracked simultaneously, control of the remote probe manipulator should be technically easier than that of a digital camera. Although digital cameras and camcorders sell tens of millions of units in the world, high-quality transperineal robotic manipulators would be produced at a much smaller scale but would certainly be in demand for non-invasive ultrasound videourodynamic systems.

Indications of Doppler ultrasound videourodynamics

  1. Top of page
  2. Abstract
  3. Introduction
  4. Uroflowmetry
  5. Non-urodynamic parameters
  6. The indirect measurement of bladder pressure
  7. Perineal noise recording
  8. Transperineal Doppler ultrasound videourodynamics
  9. Improving image-processing computer program
  10. Overcoming the rare chance to record micturition images
  11. Indications of Doppler ultrasound videourodynamics
  12. Conclusion
  13. References

A non-invasive urodynamic test should be sought when empiric therapy presents unacceptable risks (e.g. retention from anticholinergic medication with frail elderly patients). This test would also provide essential diagnostic information when there is complicating comorbidity such as pharmacotherapy for neurogenic disease or urological surgery. Although psychoactive drugs, anti-hypertensive drugs and opioid derivatives are likely to affect voiding function, no studies have been reported using the urodynamic test in humans. We can evaluate such delicate voiding function before and after treatment using this pain-free urodynamic test. Children with voiding dysfunction, recurrent urinary tract infection, and certain congenital urological abnormalities have all benefited from painless study.

Urologists must develop a non-invasive ultrasound videourodynamic system with as much enthusiasm as cardiologists have developed the echocardiogram. The difference between the echocardiogram and the ultrasound urodynamic system is only the frequency of obtaining velocity information: more than 50 times per minute vs once every several hours, respectively. Although the ultrasound urodynamic system is more difficult to develop than the echocardiogram, one principle is shared by both methods. Urethral catheterization can be avoided with the ultrasound urodynamic system. Observation of only static anatomic characteristics, for example, prostatic volume, post-void residual volume and/or bladder wall thickness obtained from transabdominal ultrasonography is not sufficient for urodynamic study.3 Using the transperineal Doppler ultrasound urodynamic system, the patient can void freely without interruptions, there is no contact between the penis and the equipment and it is specifically directed toward non-invasive diagnosis.

Conclusion

  1. Top of page
  2. Abstract
  3. Introduction
  4. Uroflowmetry
  5. Non-urodynamic parameters
  6. The indirect measurement of bladder pressure
  7. Perineal noise recording
  8. Transperineal Doppler ultrasound videourodynamics
  9. Improving image-processing computer program
  10. Overcoming the rare chance to record micturition images
  11. Indications of Doppler ultrasound videourodynamics
  12. Conclusion
  13. References

The development of non-invasive Doppler ultrasound videourodynamics will dramatically expand our understanding of voiding function. Patients have only to sit and void without painful catheterization. The advantage of being rapid, effective, and equipped with no special attachments allows it to surpass any other non-invasive urodynamic methods (e.g. perineal noise recording, the penile cuff and the condom method). Although some analytical methods and robotic-arm-related technology still require confirmation by larger-sample studies, these applications will become more attractive to the neurourologist. Urologists must work together to develop non-invasive ultrasound videourodynamics, as cardiologists are doing with the echocardiogram. Repeated innovations in associated technology will further broaden the applications of Doppler ultrasound videourodynamics and make them more informative. The current revolution in computer engineering, robotic technology, imaging and information technology will allow major advances in non-invasive Doppler ultrasound videourodynamics within the next decade.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Uroflowmetry
  5. Non-urodynamic parameters
  6. The indirect measurement of bladder pressure
  7. Perineal noise recording
  8. Transperineal Doppler ultrasound videourodynamics
  9. Improving image-processing computer program
  10. Overcoming the rare chance to record micturition images
  11. Indications of Doppler ultrasound videourodynamics
  12. Conclusion
  13. References