Particle size for prostate embolization: Is smaller better?

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Tiago Bilhim
Tiago Bilhim

Tiago Bilhim, interventional radiology, Saint Louis Hospital, Lisbon, Portugal, presented the results of a randomised prospective study which compared 100µm with 200µm polyvinyl alcohol particles (PVA) for prostatic artery embolization at the Society of Interventional Radiology Annual Meeting (13–18 April, New Orleans, USA).

In the study, Bilhim said, patients with benign prostatic hyperplasia, underwent prostatic artery embolization with either one of two different sizes (100µm and 200µm) of polyvinyl alcohol particles. The primary endpoint was to evaluate the clinical outcome; the secondary outcome was to evaluate the pain severity and the complication rates between the two sizes.

 

 

Eighty patients, from May to December 2011, underwent prostatic artery embolization.  Half of the cohort was embolized using 100µm and the other half was embolized using the 200µm particles. Bilhim told delegates that pain was measured on a scale of 0 to 10 during embolization, after four to eight hours after the procedure and a week post procedure.  The complication rates that occurred with the two particle sizes were also prospectively compared.

 

 

He reported that overall 16 patients were lost to follow-up. In the 100µm cohort, post embolization, the overall mean pain score was 0.1, mean improvement in the International Prostate Symptom Score (IPSS) and Quality of Life scores were 7.1 and 1.4, respectively. In the 200µm group, the mean post-embolization pain score was 0 and the IPSS and Quality of Life mean improvement scores were 10.8 and 1.9, respectively.

 

 

According to Bilhim there was no statistical significant difference between the groups with respect to the minor complication rates or pain. No major complications were observed in the study cohort.

 

 

“The clinical outcome at six months was better after prostatic artery embolization for benign prostatic hyperplasia with 200µm polyvinyl alcohol particles, but there was greater prostate volume and prostate-specific antigen reduction with 100µm polyvinyl alcohol particles. The combination of 100µm plus 200µm PVA particles may be the best option for prostatic artery embolization,” he said.

 

 

Bilhim told Interventional News, “Usually size is chosen based on the anatomy found, upsizing when large anastomoses between the prostatic and surrounding arteries are found. Larger PVA particles (200µm) could be expected to decrease the risk of untargeted embolization, pain and adverse events. Also, it is reasonable to assume that smaller-sized PVA particles (100µm) may lead to a better clinical outcome due to a greater ischaemia with a more distal penetration into the prostate.

 

 

However, there was no evidence until now that smaller PVA particles would lead to a better clinical outcome or to higher rates of pain or adverse events. This is the first study to show that smaller sized PVA particles are as safe as larger sized PVA particles for prostate embolization. Smaller sized PVA particles (100µm) probably induce greater prostatic necrosis that may explain the higher prostate volume and prostate-specific antigen reductions. Larger sized PVA particles (200µm) may prevent revascularisation and, hence, lead to better clinical outcomes. Starting prostate embolization with 100µm PVA particles and finishing with 200µm PVA particles is probably the best option with this type of embolic agent.”

 

 

Bilhim also noted that the results of this study are “in press” and scheduled for publication in one of the forthcoming issues of the Journal of Vascular and Interventional Radiology.

 

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