COMPUTERIZED TOMOGRAPHIC URETEROSCOPY FOR DIAGNOSING URETERAL TUMORS

Establishment and Evaluation of Patient-Specific Virtual Ureteroscopy in Assisting Flexible Ureteroscopy for Urolithiasis

Objectives. To establish virtual ureteroscopy (VU) through computed tomography urography (CTU) data from patients with upper urinary tract (UUT) stones indicated for flexible ureteroscopy (fURS) and to validate its effectiveness. Methods. Patient-specific VU generation was accomplished through incorporating CTU data into specialized software (Crusher) developed on the open access Visualization Tools Kit (VTK). These were then presented to fURS experts and novice urologists for evaluation and comparison using modified Likert-type questionnaire of 10-point rating scales (1 = not at all useful/not at all realistic/poor, 10 = very useful/very realistic/ excellent). Results. Face and content validation of VU from 5 fURS experts in 3 different centers: overall usefulness 7.4 ± 0.5, graphics 7.4 ± 0.5, intrarenal anatomy 8.4 ± 0.5, stone details 7.8 ± 0.4, usefulness in surgical planning and training 7.6 ± 0.9. Significant increase of detection in the number of calyces and stones was found from using CTU only to CTU-VU combined in the novice group ( P = .000). Before VU observation, novices found much fewer calyces and stones than experts ( P = .004 and .000, respectively). However, this gap disappeared after VU observation ( P = .327 and .292, respectively). VU feedback from the novices was superb. Conclusions. Establishing patient-specific VU through CTU data from renal stone patients is feasible. The present VU can significantly improve novice urologists’ comprehension of intrarenal anatomy and stone information before fURS procedures. Face and content validity is also proved. This novel modality may serve as an important tool for fURS surgical planning, navigation, and training.

The Role of Virtual Cystoscopy, after Multidetector Computed Tomography Imaging Reconstruction without the Use of Contrast Medium, in the Diagnosis and Evaluations of Bladder Tumors: Preliminary Study

Introduction. Although conventional cystoscopy is considered to be the gold standard for diagnosis and follow-up of bladder tumors, it remains an invasive and costly procedure. With the advent of the multidetector CT (MDCT) scanners supported by specialized software virtual cystoscopy (VC) is possible. We assess the role of VC in diagnosing and evaluating bladder lesions. Materials and Methods. Between September 2010 and October 2011, 25 consecutive patients with cystoscopically confirmed bladder tumor underwent VC. The radiologists involved in this prospective study were blinded to the exact findings. After draining any residual urine with a catheter, the bladder was retrogradely insufflated with 200–600 cc of air. No intravenous or intravesical contrast was used. MDCT scan was performed in supine and prone positions and three-dimensional reconstruction of the urinary bladder was performed. Results. The examination was well tolerated by all patients with no complications. In total, 43 lesions were detected both with conventional cystoscopy and VC. Tumor size measured by CT ranged from 3 to 80 mm in diameter. The pathological report revealed noninvasive transitional cell carcinomas in all cases. Conclusion. VC has promising results in detecting exophytic bladder lesions. In the future it could be part of the diagnostic algorithm for bladder tumors.

Computed tomography urography 1: techniques and technology

Contrast-enhanced computed tomography urography has become possible because of the development of multidetector technology, which has evolved to try and increase its diagnostic efficacy and reduce the radiation exposure. This review highlights important aspects of computed tomography urography as an imaging technique.

[Diagnostic study of the usefulness of virtual endoscopic images and 3-D modeling for lower urinary tract obstruction]

PURPOSE

I observed bladder and urethral morphology and lumen by making a virtual endoscopy (VE) of the bladder and a urethra for patients with lower urinary tract symptoms. I have herein reported the procedures to use this model to evaluate the condition of patients more precisely.

PATIENTS AND METHODS

Of those referred for investigation of lower urinary tract symptoms, subjects were 22 boys (5-13 years old, mean 9) in whom voiding cystourethrography (VCUG) was suspected for urethral obstruction between March, 2009 and October, 2010. Eleven of these 22 cases were extracted at random and underwent voiding computed tomography (VCT). Except one dropped out, the 21 cases were assigned to a VCT/VCUG combination group or a VCUG-single group. We confirmed the two groups, the rate of agreement of imaging views and cystourethroscopy (CS) views, and the effectiveness of endoscopic operation.

RESULT

I made the following imaging diagnoses in the VCT/VCUG combination group: congenital obstructive posterior urethral membrane (COPUM), n = 7; Cobb's collar, n = 1; and COPUM and Cobb's collar combined, n = 3. In contrast, in the VCUG-single group, I diagnosed COPUM, n = 5; bulbar region urethral stricture, n = 2; posterior urethral expansion, n = 2; and bladder form abnormality, n = 1. The rate of agreement between preoperative diagnosis and CS views on imaging was 72.7% in the VCT/VCUG combination group, and 33.3% in the VCUG-single group. All patients underwent transurethral incision (TUI) of the urethral obstruction. In the VCT/VCUG combination group, effectiveness of the TUI was assessed as good in 2 cases and moderate in 6 cases giving an overall effectiveness rate (good + moderate) of 72.7%. In the VCUG-single group, effectiveness was rated as moderate in 5 cases (overall effectiveness rate = 50%).

CONCLUSION

I developed a method of VE for lower urinary tract obstruction of children and examined the effectiveness. This method was found to be more effective than conventional urinary tract imaging. With the developments in the equipment, this method may in future be useful as an adjunct to CS and urodynamic studies.

Where next for the endoscope?

The concept of examining the body's interior and its organs dates back to ancient times. The roots of modern endoscopy lie in early nineteenth century Europe, and the intervening centuries have seen a steady evolution of devices and techniques. Nowadays, a wide variety of urinary tract disorders are successfully managed in a minimally invasive manner thanks to the endoscope and related technologies. Distal-sensor, 'digital', endoscopes have the potential to revolutionize the field, and change the way in which we use and think about endoscopy. Virtual endoscopy, capsule endoscopy, and a range of other techniques derived from physics and molecular biology all promise great improvements in visualization of the urinary tract and other urologic structures. Ultimately, the continued improvement of these minimally invasive technologies will enhance the quality of care that we can offer our patients.

Diagnostic potential of virtual pneumoendoscopy of the urinary tract

OBJECTIVE

To evaluate the diagnostic possibilities of CT virtual pneumoendoscopy, in various vesical and extra-vesical urinary tract abnormalities and suggest possible indications for this examination.

PATIENTS AND METHODS

Thirty-three patients (26 men and 7 women, aged 30-91, mean-61 years) were referred by the urologists for specific further evaluation of the urinary tract with virtual pneumoendoscopy for various indications. All patients except three underwent conventional endoscopy within a week either before or after the virtual examination, but the endoscopy was either equivocal or limited. The urinary tract was insufflated with room air.

RESULTS

Successful CT pneumoendoscopy was achieved in 31 of the 33 patients. The indications for the virtual study included obstructive uropathy (22), hematuria (15), and suspected fistula (2). The virtual examination findings included urethral stricture, recto-urethral fistula, multiple bladder tumors, bladder tumor invading the distal ureter or urethra, bladder diverticula containing a tumor, ureteral stricture, renal transitional cell carcinoma, and renal calculi with inflammation. Virtual CT endoscopy had added value to the diagnostic process in all our patients.

CONCLUSION

In selected cases virtual CT pneumoendoscopy may serve as an important adjunctive diagnostic aid for urologic pathologies.

Ureteral polyps: an etiological factor of hydronephrosis in children that should not be ignored

To better define the demographics, urothelial distribution and typical gross anatomic and radiologic appearances of fibroepithelial polyps of the ureter in children. We reviewed 15 cases of fibroepithelial polyps of the ureter with hydronephrosis from the archives of our department. Data were collected from radiographic studies, gross anatomic pathology and pathology and radiology reports and categorized by age, sex, clinical presentation, lesion size and location. The mean patient age was 9.1 years, and 80% were male. All of them presented with hematuria and/or flank pain. The polyps were located in the upper ureter or ureteropelvic junction (UPJ) and pelvis. Of the polyps, 60% were multiple polyps or filiform, and 40% were single or bilobed and 1-6 cm in size. Only four cases showed typical filling defect on intravenous urography. In five cases, sonography showed a mildly echogenic structure extending into the ureter from the renal pelvis. Enhanced CT revealed soft tissue filling UPJ or/and proximal ureter in six cases, and hydroureter was found in one case by three-dimensional (3D) image. Fibroepithelial polyps were diagnosed in all cases by postoperative histological examination. Fibroepithelial polyps are the most common benign tumors of the ureter. Congenital factor may be associated with the origin of fibroepithelial polyps in children. The preoperative diagnosis of ureteral polyps is difficult. A history of flank pain, hematuria or both, other than abdominal mass, light-to-moderate hydronephrosis with soft-tissue in UPJ or upper ureter, shown by sonography and radiological examination, may help in the diagnosis of ureteral polyps in children. Ureteral polyps should be recognized as an important etiology for hydronephrosis in children.

Ureteral fibroepithelial polyp diagnosed preoperatively on virtual CT ureteroscopy

We report a 28-year-old man who presented with hematuria and intermittent flank pain. Conventional CT urography showed mild left hydronephrosis and an undetermined lesion in the left ureter. By virtual CT ureteroscopy, a fibroepithelial polyp (FEP) was preoperatively diagnosed. The patient had segmental resection of the ureter and pathological proof of FEP was obtained.

Virtual Cystoscopy by Intravesical Instillation of Dilute Contrast Medium: Preliminary Experience

PURPOSE

We determined whether virtual cystoscopy based on helical data sets can yield urinary capabilities similar to those achieved by fiber-optic cystoscopy.

MATERIALS AND METHODS

A total of 11 patients with ultrasound detected bladder tumors underwent pelvic CT as a single volumetric scan after preliminary bladder distention with saline mixed with contrast medium using a 6Fr infant feeding tube. Cystoscopy was simulated based on a 3-dimensional helical CT data set in real time. Source raw CT data for virtual cystoscopy were reconstructed and navigation was done in real time using surface rendering navigation software. These images and findings were then compared with conventional cystoscopy findings.

RESULTS

An attenuation gradient of 350 HU between the vesical mucosa and urine was noted. Two of the 14 tumors (11 patients) were missed and each was 0.7 cm. All tumors greater than 0.9 cm were detected. Overall sensitivity was 85.7%. There were no false-positive findings. There was good correlation with tumor location and size. The ureteral orifices and their relationship to the tumor were also well appreciated. Subtle mucosal changes on conventional cystoscopy were not delineated by virtual cystoscopy.

CONCLUSIONS

Our method of instilling dilute contrast medium in the bladder offers an excellent attenuation gradient. The overall sensitivity of tumor detection is better than that reported for intravenous contrast medium and pneumocystoscopy.

[Virtual multislice computed tomography cystoscopy for evaluation of urinary bladder lesions]

The introduction of multislice computed tomography (MDCT) with the possibility of acquiring isotropic datasets has been an ideal prerequisite for development of virtual MDCT cystoscopy. Remarkable technical progress regarding post-processing of high-resolution 3D datasets as well as a considerable reduction of the time required for post-processing made it possible to introduce virtual MDCT cystoscopy into the clinical routine. 3D post-processing that often required 7-8 h when virtual endoscopy techniques were first developed can now be performed in less than 5 min after transfer of data to the 3D workstation. With the limitations and contraindications of conventional cystoscopy in mind, virtual MDCT cystoscopy may be seen as a valuable alternative to conventional cystoscopy for evaluation of hematuria.

Imaging for kidney stones

Imaging investigations play a vital role in the management of patients with kidney stones. The techniques available include plain x-ray of the abdomen, ultrasound scan, intravenous urogram, computed tomography (CT) and magnetic resonance imaging, amongst others. All of these techniques have their own individual roles to play and also have limitations. CT has been establishing itself as the imaging technique of choice and some exciting developments are on the way. However, renal stone disease is a complex condition. Furthermore, there are a variety of surgical techniques used to treat stones. It is therefore important that the strengths and weakness of each of the modalities are clearly understood and the investigations are tailored to address the problem in hand.

Ureteroscopes: flexible, rigid, and semirigid

Since its introduction, the ureteroscope has undergone significant improvements. Using the currently available rigid, semirigid, and flexible ureteroscopes and working instruments, urologists can diagnose and treat lesions throughout the upper urinary tract. Over the past 25 years, the ureteroscope in combination with shock wave lithotripsy has transformed the diagnosis and treatment of more than 90% of upper urinary tract pathology from an open to an endourologic procedure. With endoscope manufacturers continually incorporating new technology into their ureteroscopes, future models will undoubtedly provide better optics, increased durability, and improved capabilities, resulting in greater success when urologists perform endoscopic forays into the upper urinary tract.

Emerging role of botulinum toxin in the treatment of neurogenic and non-neurogenic voiding dysfunction

Botulinum toxin (BTX) is the most lethal naturally occurring toxin known to mankind. Why, then, would an urologist want to use this agent to poison the bladder or urethral sphincter? This article reviews the mechanisms underlying the effects of BTX treatment, summarizes the current usage of this agent within the urologic community, and provides perspectives on future targets of this therapy.

Functional reconstruction and minimally invasive techniques

Recent years have seen notable advances in imaging technologies. Three-dimensional computer-rendered techniques with rapid image acquisition have led to the development of virtual reality imaging. Virtual reality imaging allows interactive intraluminal navigation through any hollow viscus, simulating conventional endoscopy. This technique of virtual endoscopy has been applied to many organs, including the urinary tract. Virtual reality endoscopy is beginning to challenge the gold standard of conventional endoscopic evaluation. Recent advances in laparoscopic surgery are largely attributable to technological improvements in imaging equipment. Laparoscopic ultrasound has become a common adjunct in laparoscopic surgery. In particular, advances in video cameras and digital imaging technology have decreased the steep learning curve associated with laparoscopic procedures. Telerobotic systems offer several advantages to laparoscopic surgery, such as all six degrees of freedom, dexterity enhancement, tremor filtering, and stereovision. In addition, technological breakthroughs allow many procedures to evolve from open operations involving lengthy hospital stays to imaging-guided minimally invasive procedures performed on an outpatient basis. Finally, Internet-based imaging is changing the way in which urology services are delivered, by allowing rapid communication between remote locations.

Gene therapy and tissue engineering for urologic dysfunction: status and prospects

This article reviews the recent advances in gene therapy and tissue engineering for urologic dysfunction. Although the number of gene therapy-based clinical trials has increased dramatically in the field of urologic oncology, such trials are still few within the neurourologic field. Recently, new biologic approaches employing growth factors have been utilized to treat various pathological conditions. Among them, transfer of genes such as those encoding growth factors represents a promising way to deliver therapeutic proteins to malfunctioning tissues, which leads to the improvement of organ function. Tissue engineering, which may eventually be combined with gene therapy, also offers the potential to create new functional genitourinary tissue for regeneration and replacement of tissue lost as a consequence of disease. Thus, both tissue engineering and gene therapy may hold promising new solutions in the urologic field.

Virtual endoscopy in urology

Recent years have seen notable advances in virtual reality technology and increased interest in potential medical applications. Computed tomography and magnetic resonance imaging data sets, historically viewed as axial images, may now be used to construct a virtual reality endoscopic image, and navigator software systems allow the operator to 'fly' through the urinary tract. Technological evolution has improved the quality of reconstruction, as this is dependent on the software and data set, allowing virtual reality to begin to challenge endoscopic evaluation. This review describes the evolution of virtual reality in urology and the milestones of its current clinical use. Applications may become widespread in the diagnostic evaluation of common urological symptoms, the planning of surgery and the training of future urologists.

2000 AD: still a role for the intravenous urogram in stone management?

The intravenous urogram (IVU) remains a useful investigation in the assessment of upper urinary tract calculi. Helical computed tomography scanning appears to have superseded the IVU in the diagnosis of acute flank pain due to a higher sensitivity in diagnosis. Results of extracorporeal shockwave lithotripsy (ESWL) for lower calyceal stones are generally disappointing. Recent studies using the intravenous urogram have demonstrated that an acute infundibulopelvic angle may be a significant indicator of the likelihood of failure of ESWL. A prospective evaluation of the role of spatial anatomy in the clearance of lower calyceal stones by ESWL is needed. In future this parameter may be used to determine treatment protocols for lower calyceal stones. Future imaging methods may make the IVU redundant, but for the time being it remains an essential part of the urologist's armamentarium.