Rare Prostatic Artery Origins and the Importance of Collateral Circulation in Prostate Artery Embolization: A Pictorial Essay

Benefits and advances of Cone Beam CT use in prostatic artery embolization: review of the literature and pictorial essay

Prostatic artery embolization (PAE) has proven to be an efficacious treatment for urinary symptoms of benign prostatic hyperplasia. PAE is performed in a complex and challenging anatomical field which may pose difficulties from procedural standpoint. Cone beam computed tomography (CBCT) has been proposed as an invaluable tool during the PAE procedure. A review of different techniques and advancements, as well as demonstration of CBCT benefits via a pictorial overview of the salient examples is lacking. The techniques of CBCT are discussed herein and the virtual injection technology as an advancement in CBCT is discussed. To show the merits of CBCT in PAE, a pictorial overview of various clinical scenarios is presented where CBCT can be crucial in decision making. These scenarios are aimed at showing different benefits including identification of the origin of the prostatic artery and avoiding non-target embolization. Other benefits may include ensuring complete embolization of entire prostate gland as angiographic appearance alone can be inconclusive if it mimics a severely thickened bladder wall or ensuring adequate embolization of the median lobe to provide relief from "ball-valve" effect. Further examples include verification of embolization of the entire prostate when rare variants or multiple (> 2) arterial feeders are present.

Angiographic Imaging of Prostatic Artery Origin in a Greek Population and Correlation With Technical and Clinical Aspects of Prostatic Artery Embolization

Background This study aimed, first, to angiographically investigate and analyze prostatic artery (PA) origin in a Greek male population with benign prostatic hyperplasia (BPH) treated with prostatic artery embolization (PAE) and, second, to correlate prostatic arterial anatomy with technical and clinical aspects of PAE. Methodology This was a retrospective study of BPH patients who underwent PAE in a single tertiary center in Greece from June 2019 to July 2022. For the first part of the study, PA was imaged with computed tomography angiography (CTA) before PAE and with digital subtraction angiography (DSA) during PAE in all patients. A widely accepted system for the classification of PA origin was applied. Type I, a common origin of PA and superior vesical artery (SVA) from the anterior division of internal iliac artery (IIA). Type II, PA originating from the anterior division of IIA, separate from, and inferior to SVA. Type III, the origin of PA from the obturator artery. Type IV, the origin of PA from the internal pudendal artery. Type V, rarer origins of PA. For the second part of the study, a subgroup of patients from the first part (treated with the same PAE protocol and free of vascular pathology that could have interfered with the technical success of PAE) was selected. In this subgroup, differences in PA origin were correlated with technical aspects (feasibility of catheterization of PA, fluoroscopy time (FT), dose area product (DAP)) and clinical outcomes of PAE. Results After the exclusion of four patients, 159 patients were included in the first part of the study. From a total of 355 PAs, 110 (31%) were compatible with type I, 58 (16.3%) type II, 45 (12.7%) type III, 110 (31%) type IV, and 32 (9%) type V. PA origin from an accessory internal pudendal artery was the most common among the rare origins of type V. Regarding the second part of the study (a subgroup of 101 patients selected to facilitate comparisons between the different types of PA origin), type I was associated with significantly more incidences of failed or difficult catheterization of the PA compared to all other types combined (27/64 vs. 18/138, p < 0.001). Types III, IV, and V showed a relatively low degree of technical difficulty. Patients with type I PA origin of at least one pelvic side (subgroup (I), n = 48) had significantly longer FT and DAP compared to the rest (subgroup (O), n = 53). Clinical success rates of PAE were slightly lower for the subgroup (I), although the difference was not statistically significant (75.8% vs. 83.8% at 18 months post-PAE, p = 0.137). No major complications were observed. Conclusions This is the first study of PA origin in Greece. It was demonstrated that types I and IV of PA origin were the most common and had the same prevalence. Type I showed significantly higher technical difficulty compared to the others, but had no significant impact on the clinical outcomes of PAE.

Protection of nontarget structures in prostatic artery embolization

Objective

To describe the efficacy and safety of protective embolization during prostatic artery embolization, as well as to discuss its clinical relevance.

Materials and Methods

This was a retrospective, observational, single-center study including 39 patients who underwent prostatic artery embolization to treat lower urinary tract symptoms related to benign prostatic hyperplasia between June 2008 and March 2018. Follow-up evaluations, performed at 3 and 12 months after the procedure, included determination of the International Prostate Symptom Score, a quality of life score, and prostate-specific antigen levels, as well as ultrasound, magnetic resonance imaging, and uroflowmetry.

Results

Protective embolization was performed in 45 arteries: in the middle rectal artery in 19 (42.2%); in the accessory internal pudendal artery in 11 (24.4%); in an internal pudendal artery anastomosis in 10 (22.2%); in the superior vesical artery in four (8.9%); and in the obturator artery in one (2.2%). There was one case of nontarget embolization leading to a penile ulcer, which was attributed to reflux of microspheres to an unprotected artery. There were no complications related to the protected branches. All of the patients showed significant improvement in all of the outcomes studied (p < 0.05), and none reported worsening of sexual function during follow-up.

Conclusion

Protective embolization can reduce nontarget embolization during prostatic artery embolization without affecting the results of the procedure. In addition, no adverse events other than those expected or previously reported were observed. Therefore, protective embolization of pudendal region is safe.

Using prostate contrast retention (PCR) as the procedural endpoint in prostatic artery embolization for benign prostatic hyperplasia

OBJECTIVES

The failure rate following prostate artery embolization (PAE) is around 20%, which may in part result from inadequate embolization. Prostate contrast retention (PCR) adequacy on immediate post-embolization cone-beam CT may provide better assessment of embolization completeness than arterial contrast stasis seen on fluoroscopy alone. The aim of this study was to evaluate outcomes of PAE using PCR adequacy as the procedural endpoint.

METHODS

A retrospective cohort study of all PAE cases using this technique at a single large volume center was conducted. Following initial embolization of the main prostatic arteries, if PCR was inadequate, additional embolization was performed. Technical success (adequate PCR) was defined as > 75% global prostate gland contrast staining. Clinical success was determined in accordance to CIRSE standards of practice.

RESULTS

One hundred sixty-five patients (mean age 68 ± 8.4 years) underwent PAE from June 2017 to March 2019. Technical and clinical success rates were 98.8% and 96.4% respectively. Clinical success rate was significantly higher in patients with adequate PCR. International Prostate Symptom Scores (IPSS) and Quality of Life (QoL) scores significantly improved at 1-, 3-, 6-, and 12-month follow-up when compared to baseline. Prostate volume (PV) and post-voiding residual bladder volume were significantly reduced at 3, 6, and 12 months in comparison to baseline. Mild (Clavien-Dindo grade I/II) and moderate (grade III) complication rates were 12.1% and 3.6% respectively.

CONCLUSIONS

By using PCR adequacy as a guide to determine the procedure endpoint for PAE, it may be possible to achieve more complete embolization and thus higher clinical success rates.

KEY POINTS

• By using PCR adequacy as a guide to determine the procedure endpoint for PAE, it may be possible to achieve more complete embolization and thus higher clinical success rates.

Prostate Arterial Anatomy: A Primer for Interventional Radiologists

Identification of the prostatic arteries (PAs) is one of the most challenging aspects of prostate artery embolization for treatment of benign prostatic hyperplasia-associated lower urinary tract symptoms. Operators require a detailed understanding of the prostate arterial anatomy to ensure technical and clinical success with minimal complications. Due to substantial variability in internal iliac artery branch patterns and specifically the origin of the PA, we focus on 3 clinically relevant classification systems used to categorize the pelvic vasculature. These include classification systems to understand the internal iliac artery branching pattern, PA origin variation, and intraprostatic branching.

Use of a steerable microcatheter during superselective angiography: impact on radiation exposure and procedural efficiency

Background/purpose

To study steerable microcatheter (SM) use in moderate and highly difficult vessel selection compared to conventional pre-shaped microcatheter (CM) use.

Material and methods

An IRB approved, single institution analysis of 40 complex angiographic procedures with and without superselective microcatheter use during an eight-month period in 2017 was performed. Target vessels were deemed moderate or highly difficult to select based on vessel size, tortuosity, and/or angulation during non-selective initial angiography. Data collected included type of microcatheter used (SM or CM), number of microcatheters and microwires used, procedure time, radiation exposure index (dose area product/DAP), target vessel location, and time to target vessel selection (TTVS; time from device placement to vessel selection). Comparison between the SM and CM groups was performed using Wilcoxon test.

Results

A SM (SwiftNinja, Merit Medical, South Jordan, UT, USA) was used to select 46 vessels in 20 patients. One or more CMs were used in 20 patients to select 34 vessels. Median TTVS, number of microwires used, total procedure time, and DAP (microGray^.m²) were 12 vs. 462.5 s (p < 0.0001), 0 vs. 2 (p < 0.001), and 26,948 vs. 30,904 (p = 0.15) in the SM vs. CM groups, respectively. When adjusted for body mass index (BMI) using a linear model for radiation exposure, patients in the SM group had lower radiation exposure than those in the CM group (p = 0.05).

Conclusions

Utilization of a steerable microcatheter, without or with a guidewire, leads to easier and faster target vessel selection with shorter procedure times in complex vessel anatomy.