Benign prostatic hyperplasia (BPH) is one of the most common urologic conditions, with a rising global prevalence paralleling the aging global population[
1,
2]. For patients who have failed conservative and medical management of BPH, there is an increasing number of surgical management options with a range of invasiveness, safety, and efficacy. Prostatic Urethral Lift (PUL) or UroLift (Neotract Inc., Pleasanton, California, USA), is unique among these procedures in that a permanent metallic implant is left within the prostate, which serves to retract the lateral lobes. Given the permanent nature of the clips, their impact on future prostate investigation and intervention must be considered.
As multiparametric prostate magnetic resonance imaging (MRI) has shifted from an investigational tool to a key step in the diagnostic paradigm for prostate cancer (PCa), there has been significant discourse regarding the impact of imaging quality on the diagnostic yield of prostate MRI[
3]. Brachytherapy seeds and radiotherapy fiducial markers have both been shown to generate imaging artifacts that can degrade the image quality, which raises the question of how large an impact the UroLift clips have on prostate imaging quality and, thus, on PCa diagnosis after PUL.
The UroLift clips are considered conditionally MRI safe, with safety requirements aligning with those specified in PI-RADS version 2.1[
4]. In terms of imaging characteristics, the inner and outer tabs of the implants can be visualized on both CT and MRI. Interestingly, the inner stainless steel tab results in more imaging artifact than the outer nitinol tab, resulting in a greater loss of signal in the periurethral prostate[
5]. However, the impact of the artifact created by the UroLift implant on the detection of PCa has not been thoroughly studied.
The only study published to date, a recent retrospective single institution analysis of 37 patients by Benidir et al.[
6] highlights key areas impacted by the implant. The group focused on qualitative assessments of the post-PUL images, using a 5-point Likert scale to grade individual prostate zones and the previously described PI-QUAL system to give an overall rating of image quality[
7]. They corroborated that there was a greater artifact (and thus poorer image quality) in the transition zone compared to the peripheral zone, at the base compared to the apex, and on diffusion-weighted imaging (DWI) sequences than T2 or dynamic contrast enhancement (DCE) sequences. Overall, the two readers in the above study believed that the images were of insufficient diagnostic quality 24% and 16% of the time, respectively. In addition, the group highlighted a quantitative assessment of the percentage of total gland volume obscured by imaging artifacts and most notably found that the UroLift implants obscured the Apparent Diffusion Coefficient (ADC) map and the DCE sequence more than T2-weighted sequences.
At our institution, we have performed over 300 multiparametric prostate MRIs on patients with UroLift implants. Our experience is similar to that of Benidir et al. We find the stainless-steel internal tabs of the UroLift implants cause more susceptibility artifact centrally compared to the outer nitinol tabs. This usually affects the transition zone adjacent to the tabs causing more distortion on DWI, resulting in non-diagnostic imaging through much of the transition zone (Figure 1). T2-weighted imaging is more robust to the artifact and usually only the transition zone adjacent to the tabs is affected. Since PI-RADS v2.1 uses T2-weighted imaging as the main driver of the final PI-RADS score and DWI as an ancillary feature to upgrade scores, the overall impact on the ability of MRI to detect and diagnose PCa may be less significant than initially expected. In addition, PCa typically arises in the peripheral zone more so than the transition zone. Despite these factors, the inability to visualize parts of the prostate gland ultimately limits the ability of MRI to detect PCa, especially in the prostate adjacent to the tabs. As multiparametric MRI is also used for targeting lesions for biopsy and focal therapy, UroLift negatively affects these procedures as well. Further investigation is needed to understand the extent of limitation.
Overall, the published study, along with our institutional experience to date, highlights the potential negative impact UroLift implants may have on prostate imaging quality. However, there are several key areas that have yet to be explored. Benidir and colleagues highlight one of these areas of particular interest to our institution, namely, the potential impact the implants may have on PCa focal therapy[
6]. Focal therapy for PCa has gained traction in recent years as an alternative to radical surgery or radiation that may spare sexual and urinary function without compromising cancer control in select cases[
8]. These goals theoretically align with one of the purported benefits of PUL, namely, that these patients have less sexual side effects than patients undergoing transurethral resection of the prostate. However, the artifact generated by the UroLift clips may negatively impact clinician's ability to map disease burden as they assess candidates for focal therapy. In addition, high-intensity focused ultrasound, one form of focal energy delivery, is impacted by calcification and other radiodensities, and so further work is needed to assess whether this technology can deliver sufficient energy in patients who have previously undergone PUL. Relatedly, given the potential greater negative impact on imaging the base and mid-gland, PUL may impact the ability of prostate MRI to adequately stage extraprostatic extension and seminal vesical invasion, though the clinical-pathologic correlation that would be needed to prove or disprove this finding may prove difficult.
Finally, given the theoretically increased risks for adverse outcomes with post-radiation outlet procedures, it is reasonable to consider that patients may choose Urolift as a minimally invasive option to manage LUTS after prostate radiotherapy. However, no studies have yet looked at the combined impact of Urolift implants and brachytherapy seeds or fiducial markers on imaging quality. Though it can be inferred that additional artifact will be incurred, the loss of diagnosis accuracy may limit the use of MRI in these patients for making decisions regarding salvage therapy.
2025 The Author(s). UroPrecision published by John Wiley & Sons Australia, Ltd on behalf of Higher Education Press.
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