Utility of 4D CT Technology During Prostate Artery Embolization (PAE)

Nainesh Parikh, MD, MBA
Associate Member, Diagnostic Imaging & Interventional Radiology
H. Lee Moffitt Cancer Center & Research Institute, Tampa, FL with Florida, USA.

Yiemeng Hoi, PhD, Dale Marek, RT(R)
Mark Hohn, Andrew Kuhls-Gilcrist, PhD, DABR
Medical Affairs, Interventional X-ray Canon Medical Systems USA, Inc.
Dr. Nainesh Parikh, a Board-Certified Interventional Radiology, pioneers the PAE program at H. Lee Moffitt Cancer Center & Research Institute, Tampa, FL with Florida, USA. He focuses on utilizing PAE for men with lower urinary tract symptoms (LUTS) from benign prostatic hyperplasia (BPH) who may or may not have concurrent prostate cancer. Dr. Parikh earned his undergraduate degree from Columbia University in New York City, USA, and subsequently worked as an Investment Banker after graduation. After deciding that he wanted to have a significant impact on the daily lives of patients, he obtained MD and MBA degrees from Tufts University School of Medicine in Boston, Massachusetts, USA. He then completed diagnostic radiology residency at NYU Medical Center in New York City, and a fellowship in Angiography and Interventional Radiology at the Brigham and Women’s Hospital – Harvard Medical School Boston, Massachusetts, USA.

“4D CT is helpful during PAE for confirmation of PA origin, quantification of prostatic parenchyma, and identification of intra-prostatic collaterals. The ability to visualize these things with exceptional image quality allows for increased confidence during embolization with respect to safety and outcomes.”

Nainesh Parikh, MD, MBA

4D CT: True CT and Angiographic Imaging for Advanced Image Guided Therapy

The Canon Medical Alphenix 4D CT system combines two complimentary imaging modalities within the same environment - a sliding computed tomography (CT) scanner system with a state-of-the-art interventional fluoroscopic C-arm. This enables utilization of CT and fluoroscopic images during diagnostic and therapeutic interventions during the same procedure.
This potentially leads to more accurate image-guided interventions with reduced procedure time, providing on-demand true CT imaging during interventional procedures. 1, 2

BPH, sometimes referred to as ‘an enlarged prostate’, is one of the most common medical conditions in older men, effecting 70% of men in their 70s and 80% of men in their 80s.3 Recently, Prostate Artery Embolization (PAE) was recommended by four multidisciplinary medical societies as a “valuable minimally invasive option for patients who cannot tolerate or who have failed medical therapy, and those who are poor surgical candidates or refuse invasive surgery.”4 Detailed knowledge of prostatic arterial anatomy is necessary during PAE in order to minimize the risks of ‘non-target’ embolization that can cause ischemic complications to major pelvic organs, such as the urinary bladder, rectum and penis.5 Thus, identification of the prostatic artery origin as well as collaterals supplying pelvic viscera, is paramount.
Figure 1: Clinical improvement was significant in patients treated with PAE using the 4D CT system, with mean prostate volume reduced 21%, mean QoL enhanced 56%, and mean IPSS improved 63%.6
As part of the PAE program at Moffitt Cancer Center, Dr. Parikh and his team have treated over 150 patients for lower urinary tract symptoms. In order to specifically evaluate the utility of 4D CT during PAE, the team conducted a pilot study of 10 consecutive patients who underwent technically successful bilateral PAE in the 4D CT suite between September 2017 and February 2020 to evaluate short term clinical success, as well as to demonstrate efficiency of the 4D CT system during PAE.6 Short-term clinical success was evaluated by comparing prostate volume, International Prostate Symptom Score (IPSS) and Quality of Life (QOL) scores before treatment and at six-week follow-up. Efficiency of 4D CT was measured by calculating time required to perform 4D CT for each PA as a percentage of total procedure time. Results demonstrated that PAE with use of 4D CT was safe, clinically effective and efficient. Intraprocedural 4D CT of bilateral PAs is valuable for confirming PA origin, identifying pelvic visceral collaterals, and optimizing volume of embolic delivered. Acquisition of intraprocedural CTA of bilateral PAs consumed only 12% of total procedure time.6

Clinical Report

Nainesh Parikh, MD, MBA,
H. Lee Moffitt Cancer Center & Research Institute, Tampa, FL with Florida, USA.

Patient 1

History: A 70-year-old man presented with PI-RADS®4 MRI found to represent, Gleason 3+4 favorable intermediate risk prostate cancer (Gleason Grade Group 2) with a baseline IPSS of 29, QOL 3 and prostate volume 94 cc from radiation oncology clinic prior to definitive radiotherapy.
Procedure: Via right common femoral artery approach, both prostatic arteries (PA) were catheterized using a 2.4Fr microcatheter. The left PA (LPA) arose from the obturator artery and a clear intra-prostatic penile collateral was seen during Angiography (Figure 2). After successful coil embolization, the microcatheter was retracted into the main LPA and pelvic CTA was performed after hand injection of 3 cc contrast and 5 seconds delay (120kV, SUREExposure, 0.5s rotation time, 0.5 mm x 80, AIDR* 3D) using the 4D CT system. CT imaging was helpful for identifying persistent penile collateral (Figure 3) which was subsequently successfully coil embolized (Figure 3C). After retracting the microcatheter into the main LPA, 5 cc diluted embolic material (2cc 300-500 μm Embosphere® microspheres in 9 cc saline and 9 cc contrast) was delivered into the LPA under fluoroscopy. The right PA (RPA) was also successfully embolized with 5 cc of diluted embolic material, for a total of 10 cc. No access site or post-procedure complications were seen.
Figure 2: Digital subtraction Angiography (DSA, a) and 3D reconstruction of (b) of the left prostatic artery demonstrating an intra-prostatic penile collateral (yellow arrow)
Figure 3: Digital subtraction Angiography (DSA, a) showing persistent intra-prostatic penile collateral (yellow arrow) confirmed on 4D CT imaging (b). CT imaging was helpful for identifying and confirming persistent penile collateral which was subsequently successfully coil embolized (c, blue arrow).
Outcome: The patient’s IPSS and QOL improved to 4 and 1, respectively at 6 weeks; prostate volume decreased from 94 cc to 49 cc at 6 weeks. The patient had persistent continued improvement at 12 week follow up and successfully underwent 60 Gy image-guided radiotherapy (RT) in 20 fractions over 4 weeks without acute genitourinary toxicity.

*: Adaptive Iterative Dose Reduction

Patient 2

History: A 80-year-old man presented in urinary retention from long-standing BPH with a left total hip arthroplasty and was referred for PAE.

Procedure: Via right common femoral artery approach, both tortuous internal iliac systems were selected and both PAs were catheterized using a 2.4Fr microcatheter. Pelvic CTA of each PA was performed after hand injection of 3 cc contrast and 5 seconds delay (120kV, SUREExposure, 0.5s rotation time, 0.5 mm x 80, AIDR 3D) using the 4D CT system. Intraprocedural CT imaging was helpful for being able to exclude intra-prostatic penile collaterals in addition to evaluating the entire enlarged prostate even in the face of the significant streak artifact from the left total hip arthroplasty (Figure 4, 5). Successful embolization was performed under fluoroscopy with a total of 15 cc diluted embolic material (2cc 300-500 μm Embosphere® microspheres in 9 cc saline and 9 cc contrast) was injected. No access site or post-procedure complications were seen.

Outcome: The patient successfully passed voiding trial at 6 week follow up with mild LUTS (IPSS 6; QoL 1) post catheter removal.
Figure 4: Digital subtraction angiogram (DSA) (left) and CT (right) of left prostatic artery (top) and right prostatic artery (bottom). Intraprocedural 4D CT imaging was helpful for exclusion of intra-prostatic penile collaterals as well as for full evaluation an enlarged prostate given significant streak artifact from the left total hip arthroplasty.
Figure 5: 3D CT reconstruction after contrast injection into the right prostatic artery demonstrates excellent image quality for visualization of the right hemi-prostate in the face of significant streak artifact secondary to the left total hip arthroplasty

Patient 3

Figure 6: Digital subtraction Angiography (DSA, a), CT (b) and 3D reconstruction (c) after contrast injection into the right prostatic artery (blue arrow). Reflux into a cystic branch was clearly identified on both Angiography and CT (yellow arrows), resulting in very deliberate but complete embolization.
History: An 82-year-old man with a history of Gleason 4+4 high risk (Gleason Grade Group 4) prostate cancer status presented in acute urinary retention approximately 6 months post completion of radiotherapy. Baseline prostate volume was 68 cc.

Procedure: Via right common femoral artery approach, both prostatic arteries (PA) were catheterized using a 2.4Fr microcatheter. Both PAs arose from a common cysto-prostatic trunk. Pelvic CTA of only the right PA was performed after hand injection of 3 cc contrast and 5 seconds delay (helical scan, 120kV, SUREExposure, 0.5s rotation time, 0.5 mm x 80, AIDR 3D) using the 4D CT system. CT imaging was helpful for identifying reflux into the cystic branches resulting in very deliberate embolization (Figures 6). A total of 9 cc diluted embolic material (2cc 300-500 μm Embosphere® microspheres in 9 cc saline and 9 cc contrast) was injected under fluoroscopy between both PAs. No access site or post-procedure complications were seen.

Outcome: The patient successfully passed voiding trial at 6 week follow up with mild LUTS (IPSS 5; QoL 0) post catheter removal.
Figure 6: Digital subtraction Angiography (DSA, a), CT (b) and 3D reconstruction (c) after contrast injection into the right prostatic artery (blue arrow). Reflux into a cystic branch was clearly identified on both Angiography and CT (yellow arrows), resulting in very deliberate but complete embolization.

Multimodality For Better Patient Care

PAE is a complex, technically challenging procedure that requires intimate knowledge of the pelvic arterial anatomy. Intra-procedural CT is helpful to confirm prostatic artery origin in addition to intra-prostatic collateral vasculature, particularly to the penis. Visualization of these details allows for safe, effective, optimal treatment. For example, identification of PA origin in conjunction with confirmation of the lack of intra-prostatic penile collateral allows for embolization with the maximal amount of embolic material resulting in optimal clinical outcome. Streamlined 4D CT allows for full visualization of the pelvic viscera, particularly in large or tall patients; conversely, cone-beam CT is limited by the detector panel size in addition to patient size. In addition, 4D CT allows for excellent image quality during the procedure.
Dr. Parikh would like to extend his warmest thanks to the staff of the Department of Interventional Radiology at H. Lee Moffitt Cancer Center & Research Institute for their continued support in the development of the prostatic artery embolization program. //
References
1 O Ahmed et al., “Maximum efficiency, prioritized patient safety and increased revenue with Canon Medical’s 4D CT technology.” Canon Medical Systems White Paper VLWP13517US, 2020.
2 N Feinberg et al. “Improved utilization following conversion of a fluoroscopy suite to hybrid CT/Angiography system.” J Vasc Interv Radiol. 2020 Oct 8;S1051-0443(20)30574-1.
3 JT Wei et al. “Urologic diseases in America project: benign prostatic hyperplasia.” J Urol. 2005; 173:1256–1261.
4 JP McWilliams et al. “Society of Interventional Radiology Multisociety Consensus Position Statement on Prostatic Artery Embolization for Treatment of Lower Urinary Tract Symptoms Attributed to Benign Prostatic Hyperplasia: From the Society of Interventional Radiology, the Cardiovascular and Interventional Radiological Society of Europe, Société Française de Radiologie, and the British Society of Interventional Radiology: Endorsed by the Asia Pacific Society of Cardiovascular and Interventional Radiology, Canadian Association for Interventional Radiology, Chinese College of Interventionalists, Interventional Radiology Society of Australasia, Japanese Society of Interventional Radiology, and Korean Society of Interventional Radiology.” J Vasc Interv Radiol 2019; 30:627–637.
5 T Bilham et al. “Prostatic arterial supply: demonstration by multirow detector Angio CT and catheter Angiography.” Eur Radiol 2011; 21:1119–1126.
6 A Bibok et al. “Does the use of a hybrid 4D Angio CT system significantly impact procedure time for prostate artery embolization?” J Vasc Interv Radiol 2021; 32(5): S18.