Institutional review board (IRB) approval was received for this retrospective study. Written informed consent was obtained from the patients and any accompanying images. Patients gave consent for their personal or clinical details along with any identifying images to be published in this study. A review of the electronic medical records (EMR) from a single medical center was conducted on all patients (529) whom underwent PAE for severe LUTS between January 2016 and January 2020. Severe LUTS was classified as International Prostate Symptom Score (IPSS) greater than 18 points, urinary quality of life (QoL) greater than 3 points, and peak flow rate (Qmax) less than 12mL/sec. Patients were evaluated in this investigation if they underwent PAE for severe LUTS from GPH. GPH is defined as prostate volume greater than 200 mL. Patients that did not have GPH (prostate volumes less than 200 mL) were not evaluated in this investigation. Of the 529 patients that underwent PAE for severe LUTS, 72 patients had GPH and were evaluated in this investigation. At our institution, multiparametric MR imaging is performed on all patients before PAE for prostate volume (PV) measurements and to ensure the absence of any lesions suspicious for clinically significant cancers according to version 2.1 of Prostate Imaging-Reporting and Data System (PI-RADS) (29). No patients underwent PAE if MR imaging revealed lesions suspicious for clinically significant cancer. MR imaging was also used to measure prostate volumes at 12 months and 24 months after PAE. Patients underwent PAE if they did not respond to 5-alpha-reductase inhibitor and/or alpha-1-adrenergic receptor antagonist medical therapy for at least 6 months or longer and were not eligible for surgery or refused surgery. Patients were not eligible for surgical treatment due to comorbidities and/or contraindications to surgery and/or general anesthesia 49 (68%) patients with cardiovascular disease on anticoagulation/antiplatelet therapy and 23 (32%) patients with chronic lung disease. IPSS, QoL, Qmax, PV, postvoid residual volume (PVR), and PSA were measured and collected before PAE and 12 months and 24 months after PAE. Because MR imaging is performed on all patients before PAE to ensure the absence of any lesions suspicious for clinically significant cancers in our institution, patients with PSA levels above 4 ng/mL were examined in this investigation. Before PAE, 5-alpha-reductase inhibitor therapy was stopped and alpha-1-adrenergic receptor antagonist therapy was tapered and stopped after one month after PAE. No patients underwent additional interventions after PAE.
Clinical assessment was performed in all patients before PAE and 12 months and 24 months after PAE with history and physical examination, IPSS and QoL questionnaires, uroflowmetry Qmax, PVR, and PSA levels measurements. These clinical metrics are routinely recorded for patient care, to optimize patient outcomes, and for quality improvement and performance.
Prostate MR Imaging and Volume Measurement
The protocol at our institution is to perform multiparametric MR imaging for all patients before PAE for prostate gland volume measurements and to ensure the absence of clinically significant cancers before PAE. Prostate volumes were calculated using MR imaging obtained before PAE and 12 months and 24 months after PAE. At our institution, multiparametric prostate MR imaging is performed using 3.0 Tesla magnet systems (Siemens Healthcare, Erlangen, Germany). Exams are performed with phased array torso coils using the following protocol (Table 1): axial, sagittal, and coronal T2-weighted turbo spin echo images; axial b50, b500, and b800 s/mm2 diffusion-weighted images; synthetic extrapolated b1200, b1500, b2000, and b2500 diffusion-weighted images; apparent diffusion coefficient (ADC) map; axial T1 pre-contrast fat saturated volumetric interpolated breath-hold examination (VIBE) images; coronal T1-precontrast fat-saturated MR angiographic VIBE images of the pelvis; serial dynamic axial T1 pre-contrast fat saturated VIBE images obtained after intravenous gadolinium contrast injection (Gadavist 0.1mmol/kg; Bayer Healthcare Pharmaceuticals, Wayne, New Jersey, U.S.A.); axial fat-saturated T1-weighted delayed postcontrast VIBE images.
Two diagnostic radiologists with twelve and six years of experience in interpreting multiparametric prostate MR imaging, respectively, independently reviewed the MR imaging exams before and after PAE. The radiologists used DynaCAD software (InVivo, Philips Healthcare, Amsterdam, Netherlands) on two separate workstations to perform semiautomated prostatic volumetric measurements of the prostate using the MR T2-weighted images. Prostatic volumes were manually confirmed by calculation of the ellipsoid volume formula (L x W x H x π/6). Discordant measurements were resolved by consensus agreement. The diagnostic radiologists also reviewed MR imaging before and after PAE for any prostate gland lesions suspicious for clinically significant cancer according to version 2.1 of Prostate Imaging-Reporting and Data System (PI-RADS) (29).
Prostate Artery Embolization
All PAE procedures were performed by a single operator with thirteen years of angiographic and embolization experience and four years of experience performing PAE. All patients received one dose of ciprofloxacin 400 mg administered intravenously for infection prophylaxis. All procedures were performed under moderate (conscious) sedation with local anesthesia in a therapeutic angiography unit. A unilateral left trans-radial arterial approach was utilized in all patients. Real time ultrasound was used to visualize patency and access of the left radial artery, which entered with a micropuncture set, 21-gauge needle, and a 5-French (-F) sheath. Patients underwent digital subtraction angiography (DSA) and PAE with a digital flat-panel detector fluoroscopy system (Innova 4100 IQ; General Electric Healthcare, Chicago, Illinois, U.S.A.) with nonionic intravenous contrast (Omnipaque 350 mg/mL; General Electric Healthcare, Chicago, Illinois, U.S.A.). Internal iliac arterial angiography in the ipsilateral oblique projection was performed to identify the right and left prostatic arteries, accessory prostatic arteries, and variant anatomy. Pelvic and prostatic arteries were catheterized using a combination of wires and catheters: 5-F Cobra 2 catheter (Cook Medical, Bloomington, Indiana, U.S.A.), 4-F Berenstein catheter (Merit Medical Systems, Incorporated, South Jordan, Utah, U.SA.), 2.4-F Progreat microcatheter (Terumo Interventional Systems, Tokyo, Japan) and 0.014-inch Transend microguide wire (Stryker Neurovascular, Fremont, California, U.S.A.). The prostatic arteries were identified with DSA. Advanced imaging was performed with localized intraoperative cone-beam computed tomography (CT) with intravenous contrast (100 mL Isovue 370, Bracco Diagnostics, Milan, Italy) prior to embolization. Cone-beam CT images were transmitted, reconstructed in three dimensions, and reviewed to confirm prostatic arterial vascular anatomy, prostate gland vascular supply, and ensure the absence of vascular supply to adjacent anatomical structures, such as the urinary bladder, penis, and rectum. Bilateral PAE was then performed to stasis with a primary embolic agent: 100 μm to 250 μm Embospheres (Merit Medical Systems, Incorporated, South Jordan, Utah, U.S.A.) and a secondary embolic agent: 2 mm and 3 mm CX coils (Boston Scientific, Marlborough, Massachusetts, U.S.A.). A band compression device was utilized to achieve radial arterial vascular access closure in all patients.
DSA, which was performed with a flat panel detector fluoroscopy system, and cone-beam CT both utilize photoelectric x-rays with ionizing radiation to visualize, identify, and catheterize the prostatic arteries during PAE. In accordance with the American College of Radiology, European Union of Radiology, and Society of Interventional Radiology, ionizing radiation was used in a fashion as low as reasonably achievable (ALARA) to minimize exposure of patients to radiation (30). Low radiation doses to patients were maintained and further reduced with intraprocedural cone-beam CT in combination with three dimensional reconstruction that in turn abbreviated procedure times (30).
The Quality Improvement Guidelines for Percutaneous Transcatheter Embolization were used to classify complications after PAE; major complications are complications that require inpatient treatment and/or surgery and minor complications are complications that can be treated with conservative and/or outpatient treatment (31).
The clinical metrics of IPSS, QoL, Qmax, PVR, PV, and PSA were expressed as quantitative values with means and standard deviations (SD). These quantitative values were analyzed with a Wilcoxon signed rank test using SAS software, version 9.4 (SAS Institute Incorporated, Cary, North Carolina, U.S.A.). A probability value of P < 0.05 or lower was considered statistically significant. We had no missing information for the patients and data that were presented in this study.