Delayed contrast-enhanced MRI to localize Botox after cystoscopic intravesical injection

Intravesical Contrast-Enhanced MRI: A Potential Tool for Bladder Cancer Surveillance and Staging

This review article gives an overview of the current state of the art of bladder cancer imaging and then discusses in depth the scientific and technical merit of a novel imaging approach, tracing its evolution from murine cancer models to cancer patients. While the poor resolution of soft tissue obtained by widely available imaging options such as abdominal sonography and radiation-based CT leaves them only suitable for measuring the gross tumor volume and bladder wall thickening, dynamic contrast-enhanced magnetic resolution imaging (DCE MRI) is demonstrably superior in resolving muscle invasion. However, major barriers still exist in its adoption. Instead of injection for DCE-MRI, intravesical contrast-enhanced MRI (ICE-MRI) instills Gadolinium chelate (Gadobutrol) together with trace amounts of superparamagnetic agents for measurement of tumor volume, depth, and aggressiveness. ICE-MRI leverages leaky tight junctions to accelerate passive paracellular diffusion of Gadobutrol (604.71 Daltons) by treading the paracellular ingress pathway of fluorescein sodium and of mitomycin (<400 Daltons) into bladder tumor. The soaring cost of diagnosis and care of bladder cancer could be mitigated by reducing the use of expensive operating room resources with a potential non-surgical imaging option for cancer surveillance, thereby reducing over-diagnosis and over-treatment and increasing organ preservation.

Perioperative Techniques for the Use of Botulinum Toxin in Overactive Bladder: Results of a Multinational Online Survey of Urogynecologists in Germany, Austria, and Switzerland

INTRODUCTION AND HYPOTHESIS

Botulinum toxin (BoNT) is a widely used treatment for overactive bladder (OAB). Despite its common use, no standardized treatment regimen exists so far. The aim of this survey was to evaluate the variation in perioperative treatment strategies among members of the German-speaking urogynecologic societies.

MATERIALS AND METHODS

A clinical practice online survey was carried out between May 2021 and May 2022, and all members of the German, Swiss, and Austrian urogynecologic societies were invited to participate. Participants were grouped in two ways. First, they were grouped into (1) urogynecologists with board certification and (2) non-board-certified general obstetricians and gynecologists (OBGYNs). Second, we set a cut-off at 20 transurethral BoNT procedures per year to differentiate between (1) high- and (2) low-volume surgeons.

RESULTS

One hundred and six completed questionnaires were received. Our results demonstrated that BoNT is mostly used as a third-line treatment (93%, n = 98/106), while high-volume surgeons used it significantly more often as a first/second-line treatment (21% vs. 6%, p = 0.029). Large variations existed in the use of perioperative antibiotics, preferred sites of injection, the number of injections, and the timing of the measurement of the postvoid residual volume (PVRV). Forty percent of participants did not offer outpatient treatment to patients. Local anesthesia (LA) was mostly used by board-certified urogynecologists (49% vs. 10%, p < 0.001) and high-volume surgeons (58% vs. 27%, p = 0.002). Injections into the trigone were also more often performed by board-certified urogynecologists and high-volume surgeons (22% vs. 3% (p = 0.023) and 35% vs. 6% (p < 0.001), respectively). PVRV was controlled between weeks 1 and 4 by only 54% of participants (n = 57/106). Clean intermittent self-catheterization (CISC) was infrequently taught (26%).

CONCLUSIONS

Our survey confirmed that BoNT is widely used by urogynecologists in the three German-speaking countries, but practice patterns vary widely, and no standardized method could be detected, despite interviewing urogynecologic experts. These results clearly demonstrate that there is a need for studies to define standardized treatment strategies for the best perioperative and surgical approach regarding the use of BoNT in patients with OAB.

Pathophysiology, assessment, and treatment of overactive bladder symptoms in patients with interstitial cystitis/bladder pain syndrome

INTRODUCTION

Interstitial cystitis/bladder pain syndrome (IC/BPS) is prevalent, difficult to treat, and has close symptom overlap with overactive bladder (OAB). A review of the pathophysiology, assessment, and treatment of IC/BPS patients with overlapping OAB symptoms has not been summarized recently in the published literature.

METHODS

A review of the published literature on the overlap of IC/BPS and OAB was conducted using MeSH terminology (1992-2022).

RESULTS

The pathophysiology of IC/BPS is not fully understood. Animal research has found the bladder trigone and base are richly populated by afferent fibers, including many small unmyelinated C-fibers that may be upregulated in IC/BPS. Successful therapies with multimodal effects on OAB symptoms in patients with IC/BPS are likely to exert beneficial effects on both pain and lower urinary tract symptoms. Potentially efficacious therapies for the treatment of OAB in IC/BPS include pelvic floor physical therapy, oral pharmacotherapy (antimuscarinics and beta-3 agonists), sacral neuromodulation, percutaneous tibial nerve stimulation, and botulinum toxin A (BTA). Antimuscarinics and beta-3 agonists have yielded partial efficacy in IC/BPS, although may help differentiate symptoms of OAB from those associated with IC/BPS. The transvaginal trigone treatment (T3) intradetrusor injection approach allows for delivery of therapeutics to the bladder without the need for a cystoscope and appears to be feasible.

CONCLUSIONS

Further research is needed to understand the pathophysiology of IC/BPS and symptom overlap with OAB, which in turn should enable the development of more personalized therapeutics.

Trigone as a diagnostic and therapeutic target for bladder-centric interstitial cystitis/bladder pain syndrome

The pathophysiology of interstitial cystitis/bladder pain syndrome (IC/BPS) may be bladder-centric, with afferent nerve hyperexcitability and/or due to neural central sensitization. In bladder-centric disease, the trigone's unmyelinated nociceptive C-fibers are thought to be upregulated, suggesting this as a potential target for diagnostic modalities and for treatment with local anesthetics and chemodenervation. We propose that the transvaginal trigone treatment (T3) route of administration of such treatments should be considered in women with IC/BPS, as this approach is easier and less invasive than cystoscopy. For T3, or other bladder-centric treatments to be successful, patient selection should attempt to exclude patients with predominantly neural central sensitization.

Prophylactic intravenous gentamicin with sedation-free cystoscopic injection of BoNT-A: No demonstrable adverse extravesical neuromuscular effects in a pilot safety study of 220 idiopathic overactive bladder patients

Objectives:

To determine whether administration of single dose prophylactic intravenous gentamicin prior to intravesical injection of botulinum toxin type A (BoNT-A) is associated with adverse extravesical neuromuscular effects in idiopathic overactive bladder syndrome.

Patients and methods:

A retrospective analysis of 220 consecutive idiopathic overactive bladder patients following sedation-free flexible cystoscopic injection of intravesical BoNT-A. All patients received a single dose of intravenous gentamicin (160 mg) followed by 100-200 IU of BoNT-A. They were followed up at intervals to determine whether they had experienced any adverse extravesical neuromuscular side effects.

Results:

None of our patients developed adverse extravesical neuromuscular side effects from intravesical botulinum injections with concomitant administration of intravenous gentamicin.

Conclusion:

Single dose intravenous gentamicin is safe to use as a prophylaxis for intravesical BoNT-A injections of 200 IU or below in idiopathic overactive bladder patients.

Level of evidence:

Not applicable.

How can we improve the diagnosis and management of bladder pain syndrome? Part 1: ICI-RS 2018

BACKGROUND

This paper summarizes the discussion in a think tank at the ICI-RS 2018 about the diagnosis of bladder pain syndrome (BPS).

AIMS

To review the guidelines, investigations and subtypes of BPS.

MATERIALS AND METHODS

Review of literature in the light of the think tank discussion.

RESULTS

All guidelines recommend completing history, physical examination, urine analysis, urine culture, and urine cytology to define the BPS phenotype but there are differences on further investigations. In those guidelines which recommend cystoscopy, the identification of Hunner's lesions (HLs) is recommended as this changes the treatment plan and outcome.

CONCLUSION

We propose that the differentiation of Hunner's ulcers is an important step in the assessment of these patients. Further suggestions for research are suggested.

Transvaginal ultrasound guided trigone and bladder injection: A cadaveric feasibility study for a novel route of intradetrusor chemodenervation

Purpose

OnabotulinumtoxinA (BTX) detrusor chemodenervation is an efficacious third-line treatment for overactive bladder. Despite high clinical efficacy rates for BTX injection, many patients refuse initial or repeat treatment due to the invasiveness of the cystoscopic route of delivery. We assess the feasibility of injecting the trigone and posterior bladder wall via a transvaginal route under ultrasound guidance using a human cadaveric model.

Materials and Methods

Eight de-identified anonymous fresh female deceased donor cadaver pelvises were placed in supine split leg position. A transvaginal ultrasound probe guided injections of India ink into the trigone in 3 sites and the posterior wall in 2 sites. Full thickness bladder biopsies were then obtained and histologic analysis was performed to confirm presence of India ink in the detrusor layer.

Results

The mean time from day of death was 11.0 days (range, 4.0–23.0 days). Three to five bladder biopsies were obtained per cadaver, for a total of 34 specimens (20 trigone, 14 posterior wall). Histologic analysis revealed presence of India ink within the detrusor layer in 8/8 (100.0%) of cadavers. The surgeon's perception of appropriate targeting under ultrasound guidance was confirmed in 8/8 cadavers (100.0%) involving the bladder trigone, and 7/8 (87.5%) involving the posterior wall. Of injections that were believed to have appropriately targeted the detrusor layer, 22/34 specimens (64.7%) demonstrated the presence of India ink under histologic analysis.

Conclusions

Intradetrusor injection of the bladder trigone and posterior wall under transvaginal ultrasound guidance is feasible and has acceptable accuracy.

Recent advances in imaging and understanding interstitial cystitis

Interstitial cystitis/bladder pain syndrome (IC/BPS) is a debilitating condition associated with intense pelvic pain and bladder storage symptoms. Since diagnosis is difficult, prevalence estimates vary with the methodology used. There is also a lack of proven imaging tools and biomarkers to assist in differentiation of IC/BPS from other urinary disorders (overactive bladder, vulvodynia, endometriosis, and prostatitis). Current uncertainty regarding the etiology and pathology of IC/BPS ultimately impacts its timely and successful treatment, as well as hampers future drug development. This review will cover recent developments in imaging methods, such as magnetic resonance imaging, that advance the understanding of IC/BPS and guide drug development.

Current Therapeutic Strategies in Clinical Urology

The field of urology encompasses all benign and malignant disorders of the urinary tract and the male genital tract. Urological disorders convey a huge economic and patient quality-of-life burden. Hospital acquired urinary tract infections, in particular, are under scrutiny as a measure of hospital quality. Given the prevalence of these pathologies, there is much progress still to be made in available therapeutic options in order to minimize side effects and provide effective care. Current drug delivery mechanisms in urological malignancy and the benign urological conditions of overactive bladder (OAB), interstitial cystitis/bladder pain syndrome (IC/BPS), and urinary tract infection (UTI) will be reviewed herein. Both systemic and local therapies will be discussed including sustained release formulations, nanocarriers, hydrogels and other reservoir systems, as well as gene and immunotherapy. The primary focus of this review is on agents which have passed the preclinical stages of development.

Novel contrast mixture achieves contrast resolution of human bladder wall suitable for T1 mapping: applications in interstitial cystitis and beyond

PURPOSE

Instillation of novel contrast mixture (NCM) was recently shown to improve the contrast resolution of rat bladder wall with high contrast-to-noise ratio (CNR). Here, the clinical safety and the feasibility of NCM-enhanced MRI to achieve artifact-free visualization of human bladder wall suitable for quantitative measurement of the magnetic resonance (MR) longitudinal relaxation time (T1) was assessed.

METHODS

Six female subjects [two controls and two with Hunner-type interstitial cystitis IC and two with non-Hunner-type IC] consented for MRI at 3 T before and after instillation of NCM [4 mM gadobutrol and 5 mM ferumoxytol in 50 mL of sterile water for injection]. Single breath-hold fast MR acquisition in large readout bandwidth for 5-mm-thick single slice with variable flip angle was applied to minimize the motion and chemical shift artifacts in measurements of bladder wall thickness (BWT), CNR and T1 from 20 pixels.

RESULTS

NCM instillation in subjects did not evoke pain or discomfort. Fourfold increase in bladder wall CNR (*p < 0.02) and pixel size of 0.35 mm with minimal influence of artifacts allowed accurate determination of bladder wall thinning ~ 0.46 mm from 50 mL NCM (*p < 0.05). Pre-contrast bladder wall T1 of 1544 ± 34.2 ms was shortened to 860.09 ± 13.95 ms in Hunner-type IC (*p < 0.0001) relative to only 1257.42 ± 20.59 and 1258.16 ± 6.16 ms in non-Hunner-type IC and controls, respectively.

CONCLUSION

Findings demonstrate the safety and feasibility of NCM-enhanced MRI to achieve artifact-free differential contrast and spatial resolution of human bladder wall, which is suitable for measuring BWT and pixel-wise measurement of T1 in post-contrast setting.

Past, Present and Future of Chemodenervation with Botulinum Toxin in the Treatment of Overactive Bladder

PURPOSE

We systematically reviewed preclinical and clinical studies on bladder chemodenervation with onabotulinumtoxin A to highlight current limitations and future drug delivery approaches.

MATERIALS AND METHODS

We identified peer reviewed basic and clinical research studies of onabotulinumtoxin A in the treatment of neurogenic bladder and refractory idiopathic overactive bladder published between March 2000 and March 2016. Paired investigators independently screened 125 English language articles to identify controlled studies on onabotulinumtoxin A administration in the MEDLINE® database and abstracts presented at annual American Urological Association meetings. The review yielded an evidence base of more than 50 articles relevant to the approach of injection-free onabotulinumtoxin A chemodenervation.

RESULTS

The efficacy and safety of intradetrusor injection of onabotulinumtoxin A for the treatment of overactive bladder are sensitive to injection volume and depth, and this issue has motivated researchers to study injection-free modes of drug delivery into the bladder. Urothelial denudation with protamine sulfate or dimethyl sulfoxide, liposome encapsulated onabotulinumtoxin A and other physical approaches are being studied to increase toxin permeability and avoid intradetrusor injections. Liposome encapsulated onabotulinumtoxin A enhances toxin activity while reducing its toxin degradation. The safety and efficacy of liposome encapsulated onabotulinumtoxin A were tested in a multicenter, placebo controlled study. Although this treatment successfully reduced urinary frequency and urgency, it did not significantly reduce urgency urinary incontinence episodes.

CONCLUSIONS

Intradetrusor injection of onabotulinumtoxin A is a safe and effective treatment as reported in several large multicenter, randomized controlled trials. Injection of the toxin into the bladder wall impairs afferent and efferent nerves, but injection-free drug delivery approaches only impair the bladder afferent nerves. Further studies are needed to develop better drug delivery platforms that overcome the drawbacks of intradetrusor injection, increase patient acceptance and reduce treatment costs.

Intraprostatic Botulinum Neurotoxin Type A Injection for Benign Prostatic Hyperplasia-A Spotlight in Reality

Botulinum toxin is a neurotoxin produced by the bacterium Clostridium botulinum. It inhibits the release of acetylcholine and other neurotransmitters from the nerve terminal. Botulinum toxin, specifically toxin type A (BoNT-A) has been used since the 1970s to reduce the muscular hypercontraction disorders. The application of BoNT-A in urology field started from intra-bladder injection for overactive bladder, which has been recognized as third line therapy in many countries. Since prostate gland as well as bladder is under the influence of autonomic innervation, theorectically, injection of BoNT-A into the prostate induces chemo-denervation and modulation of prostate function, and reduces lower urinary tract symptoms (LUTS). This article reviews the application of BoNT-A in patients with LUTS/ benign prostatic hyperplasia (BPH) from mechanisms of action to clinical results. BoNT-A has been shown to induce prostate apoptosis, downregulation of alpha 1A receptors, and reduce contractile function of prostate in animal studies. Open studies of intraprostate BoNT-A injection have demonstrated promising results of reducing LUTS and improvement of voiding function in human LUTS/BPH, however, intraprostatic BoNT-A injection did not perform better than the placebo group in recent publications of placebo controlled studies. We suggested that BoNT-A prostate injection might benefit selected population of BPH/LUTS, but it is unlikely to be an effective therapy for general population of male LUTS/BPH.

Urodynamic and Immunohistochemical Evaluation of Intravesical Botulinum Toxin A Delivery Using Low Energy Shock Waves

PURPOSE

We investigated the feasibility of using low energy shock waves for intravesical botulinum toxin A delivery. We also evaluated its efficacy for acetic acid induced bladder hyperactivity in rats.

MATERIALS AND METHODS

In study 1 magnetic resonance imaging with intravesical administration of Gd-DTPA (Gd-diethylenetriamine pentaacetic acid) contrast medium was performed to visualize increased bladder urothelial permeability after low energy shock waves. In study 2 saline (1 ml) or botulinum toxin A (20 U/1 ml saline) was administered in the bladder with or without low energy shock waves (300 pulses at 0.12 mJ/mm(2)) and retained for 1 hour on day 1. Continuous cystometrograms were performed on day 8 by filling the bladder with saline followed by 0.3% acetic acid. The bladder was harvested for histology, and SNAP-25, SNAP-23 and COX-2 expression by Western blot or immunostaining.

RESULTS

Magnetic resonance imaging established bladder urothelial leakage of Gd-DTPA after low energy shock waves, which was not seen in controls. The intercontraction interval was decreased 71.9%, 72.6% and 70.6% after intravesical instillation of acetic acid in saline, saline plus low energy shock wave and botulinum toxin A pretreated rats, respectively. However, rats that received botulinum toxin A plus low energy shock waves showed a significantly reduced response (48.6% decreased intercontraction interval) to acetic acid instillation without compromising voiding function. Rats pretreated with botulinum toxin A plus low energy shock waves showed a decreased inflammatory reaction (p <0.05), and decreased expression of SNAP-23 (p <0.05), SNAP-25 (p = 0.061) and COX-2 (p <0.05) compared with the control group.

CONCLUSIONS

Low energy shock waves increased urothelial permeability, facilitated intravesical botulinum toxin A delivery and blocked acetic acid induced hyperactive bladder. These results support low energy shock waves as a promising method to deliver botulinum toxin A without the need for injection.

Assessment of colon and bladder crosstalk in an experimental colitis model using contrast-enhanced magnetic resonance imaging

BACKGROUND

Inflammatory bowel disease (IBD) consists of two chronic remitting-relapsing inflammatory disorders in the colon referred to as ulcerative colitis and Crohn's disease (CD). Inflammatory bowel disease affects about 1.4 million Americans. 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis is a widely used model of experimental intestinal inflammation with characteristic transmural and segmental lesions that are similar to CD.

METHODS

Here, we report on the use of contrast-enhanced magnetic resonance imaging (CE-MRI) to monitor in vivo bladder permeability changes resulting from bladder crosstalk following colon TNBS exposure, and TNBS-induced colitis. Changes in MRI signal intensities and histology were evaluated for both colon and bladder regions.

KEY RESULTS

Uptake of contrast agent in the colon demonstrated a significant increase in signal intensity (SI) for TNBS-exposed rats (p < 0.01) compared to controls. In addition, a significant increase in bladder SI for colon TNBS-exposed rats (p < 0.001) was observed compared to saline controls. Histological damage within the colon was observed, however, bladder histology indicated a normal urothelium in rats with TNBS-induced colitis, despite increased permeability seen by CE-MRI.

CONCLUSIONS & INFERENCES

Contrast-enhanced MRI was able to quantitatively measure inflammation associated with TNBS-induced colitis, and assess bladder crosstalk measured as an increase in urothelial permeability. Although CE-MRI is routinely used to assess inflammation with IBD, currently there is no diagnostic test to assess bladder crosstalk with this disease, and our developed method may be useful in providing crosstalk information between organ and tissue systems in IBD patients, in addition to colitis.