Journal of Vascular and Interventional Radiology

Intra-Arterial and Intravenous Contrast-Enhanced Ultrasonography (CEUS) in Prostate Artery Embolization: A Case Series

General Topic

Disease: Benign prostatic hyperplasia (BPH) is a common problem among older population. In this condition, the prostate gland enlarges due to inflammation and/or increased division of prostatic cells. This can result in obstruction for urethra, and even interfere with the muscles controlling the bladder.
Anatomy: The prostate gland is located below bladder and in front of the rectum. It also surrounds the urethra, which is the pathway for the urine after passing the bladder.
Treatment: There are three parts to treating BPH - lifestyle, medical, and surgical. Lifestyle modifications involve limiting fluids traveling through the urethra, such as drinking less fluids before bed, scheduling urination, and strengthening pelvic muscles to help with a sense of urgency (Kegel exercises).

Medical treatments involve alpha-adrenergic receptor blockers: tamsulosin, silodosin, doxazosin (main side effect: hypotension).
Traditional surgery involves traveling through the urethra and cutting out the prostate gland, called TURP (Trans-Urethral Resection of the prostate). Lasers can also be used to vaporize the gland
The newer technology that Interventional Radiology uses is a procedure called Prostate Artery Embolization. By cutting off the blood supply to the prostate gland, it naturally shrivels up and dies.

This paper focuses on assessing the effectiveness of the contrast-enhanced ultrasound in visualizing the completeness of the prostate artery embolization procedure. CT is used during the procedure to verify the artery being embolized. This can lead to excessive radiation for the patient - hence this study, to see if we can use ultrasound instead.

Design

8 patients are recorded in this paper, who have consented to the procedure with Intra-Arterial and Intravenous CEUS.

Embolization: Using a microcatheter, interventional radiologist reaches the prostatic arteries.
Angiography (imaging of the vasculature) was then done to confirm the position, followed by IA CEUS as well.
Then, the vessel was blocked by injecting suspension of microspheres to block the vessels.
IA CEUS is taken again to visualize the cessation of blood flow.
- IA CEUS would confirm appropriate placement of the microcatheter, when its contrast enhanced ('brightened') half the prostate on that side of the artery and nowhere else.
- IA AND IV CEUS would confirm embolization by showing that the contrast is highlighting nothing (which makes sense because contrast travels through blood vessels).

Conclusion

15 prostatic arteries, when injected with contrast, enhanced that half of the prostate as demonstrated by IA CEUS. All 15 again demonstrated decreased enhancement after embolization of the arteries. IV CEUS is used for 4 patients, and this also demonstrated decreased enhancement for 100% of the arteries after the embolization. All patients reported improvement in symptoms in 6-week follow-up, implying that the procedures are likely all successful.

Key Points

Prostate artery embolization is a new minimally invasive procedure to treat BPH.
IA/IV CEUS (Contrast-Enhanced Ultrasound) accurately demonstrated the correct placement of microcatheters and appropriate endpoint for embolization.
Because IA/IV CEUS do not emit radiation, this study shows that it can serve as a reliable and safe substitute for CT during the procedure.

Significance and Future Steps

This study is limited by the small number of patients. However, it is a promising investigation that makes the new prostatic artery embolization even safer. Replacing the cone-beam CT with CEUS will be beneficial for patients with limited renal function especially (less contrast needed), and minimizes radiation exposure for them.
Future Directions:

Increasing patient cohort for more reliable data
Using IV CEUS to monitor complications (prostate ischemia) and predict clinical improvement

References

Nzekwu E, Mirakhur A, Lee A, Bakshi D. Intra-Arterial and Intravenous Contrast-Enhanced Ultrasonography in Prostate Artery Embolization: A Case Series. J Vasc Interv Radiol. 2018. 29(10):1399-1402.