How to “Get Out of Trouble” During Prostatic Artery Embolization

Guiding the prostatic artery embolization procedure with computational uid dynamics

Benign prostatic hyperplasia (BPH) is a common disease associated with lower urinary tract symptoms and the most frequent benign tumor in men. To reduce BPH therapy complications, prostatic artery embolization (PAE) was developed to replace the surgical options. PAE is a minimally invasive technique in which emboli are injected into the prostate arteries (PA), obstructing the blood flow in the hypervascular nodules. In this work, a personalized PAE treatment strategy was proposed using patient-specific computational fluid dynamics (CFD). First, the hemodynamics environment in the iliac arterial tree considering a large network of bifurcations was studied. The results showed complex blood flow patterns in the iliac arterial network. Subsequently, the transport of embolic particulates during PAE for the standard horizontal and a hypothetical vertical patient positioning was simulated using Lagrangian particle tracking. Emboli with different sizes were released at various locations across the iliac arterial tree. The emboli entering the PA were mapped back to their initial location to create emboli release maps (ERMs). The obtained ERMs during the standard patient positioning for smaller emboli at certain release locations showed distinct regions in which if the emboli were released within these regions, all of them would reach the PA without non-target embolization. During the hypothetical vertical patient positioning, the larger emboli formed a larger coherent region in the ERMs. Our patient-specific model can be used to find the best spatial location for emboli injection and perform the embolization procedure with minimal off-target delivery.

Reduced nontarget embolization and increased targeted delivery with a reflux-control microcatheter in a swine model

PURPOSE

To evaluate the potential differences in non-target embolization and vessel microsphere filling of a reflux-control microcatheter (RCM) compared to a standard end-hole microcatheter (SEHM) in a swine model.

MATERIALS AND METHODS

Radiopaque microspheres were injected with both RCM and SEHM (2.4-Fr and 2.7-Fr) in the kidneys of a preclinical swine model. Transarterial renal embolization procedures with RCM or SEHM were performed in both kidneys of 14 pigs. Renal arteries were selectively embolized with an automated injection protocol of radio-opaque microspheres. Ex-vivo X-ray microtomography images of the kidneys were utilized to evaluate the embolization by quantification of the deposition of injected microspheres in the target vs. the non-target area of injection. X-ray microtomography images were blindly analyzed by five interventional radiologists. The degree of vessel filling and the non-target embolization were quantified using a scale from 1 to 5 for each parameter. An analysis of variance was used to compare the paired scores.

RESULTS

Total volumes of radio-opaque microspheres injected were similar for RCM (11.5±3.6 [SD] mL; range: 6-17mL) and SEHM (10.6±5.2 [SD] mL; range: 4-19mL) (P=0.38). The voxels enhanced ratio in the target (T) vs. non-target (NT) areas was greater with RCM (T=98.3% vs. NT=1.7%) than with SEHM (T=89% vs. NT=11%) but the difference was not significant (P=0.30). The total score blindly given by the five interventional radiologists was significantly different between RCM (12.3±2.1 [SD]; range: 6-15) and the standard catheter (11.3±2.5 [SD]; range: 4-15) (P=0.0073), with a significant decrease of non-target embolization for RCM (3.8±1.3 [SD]; range: 3.5-4.2) compared to SEHM (3.2±1.5 [SD]; range: 2.9-3.5) (P=0.014).

CONCLUSION

In an animal model, RCM microcatheters reduce the risk of non-target embolization from 11% to 1.7%, increasing the delivery of microspheres of 98% to the target vessels, compared to SEHM microcatheters.

Safety and efficacy of prostatic artery embolization for large benign prostatic hyperplasia in elderly patients

Objective

To assess the safety and efficacy of prostatic arterial embolization (PAE) for elderly patients with lower urinary tract symptoms secondary to large benign prostatic hyperplasia.

Methods

Twenty-eight patients (>80 years of age) with prostate volume >80 mL were enrolled from October 2016 to October 2019. PAE was performed using microspheres and functional results were evaluated at 1, 3, 6, and 12 months postoperatively. The following data were recorded: International Prostate Symptom Score (IPSS), quality of life (QoL), maximum urine flow rate (Qmax), post-void residual urine volume, prostate volume and total prostate-specific antigen level.

Results

Selective prostatic arterial catheterization and embolization were achieved in 27 of 28 patients. Follow-up data were available for those 27 patients until 12 months postoperatively. Significant improvements were found at all postoperative time points in terms of the mean IPSS, mean QoL score, mean Qmax, mean post-void residual urine volume, mean total prostate-specific antigen level, and mean prostate volume. The overall complication rate was 46.4%.

Conclusions

PAE is an efficacious and safe treatment for elderly patients with large prostate volume; it may offer an effective approach for patients who are not candidates for open or endoscopic surgical procedures because of comorbidities.

Prostatic Artery Embolization: Equipment, Procedure Steps, and Overcoming Technical Challenges

In the last decade, prostatic artery embolization (PAE) established itself as a safe and effective treatment option for lower urinary tract symptoms (LUTS) attributed to benign prostate hyperplasia (BPH), with reproducible results across multiple centers and endorsement by important international societies. However, PAE is also known to be a technically demanding procedure. Accompanying the prevalence of benign prostate hyperplasia, the procedure is usually performed in older patients, in whom atherosclerosis and comorbidities are common features. Also, prostatic vascular anatomy is described to be complex and variable, and pelvic structures are deeply interconnected by anastomosis. Thus, PAE demands a deep familiarization with materials and devices, intraprocedure imaging techniques, microcatetherization skills and with the pelvic vascular anatomy. Especially in the beginning of the learning curve, the procedure can be time-consuming and related to high radiation exposure for both medical team and the patient. In this article, the main points of technical concern during PAE are described and discussed, such as the equipment needed, the effect of different embolic materials, patient's preparation for the procedure, arterial access sites, identifying and catheterizing the prostatic arteries, the embolization techniques, among others. Finally, the most frequent technical challenges are presented, and the possible strategies to overcome them are exemplified and discussed.