Focal Laser Ablation Research Articles

P015 - Predicting out bore prostate cancer focal laser ablation failure and biochemical relapse using the correlation with the surrounding tissue temperature parameters during treatment

P015 - Predicting out bore prostate cancer focal laser ablation failure and biochemical relapse using the correlation with the surrounding tissue temperature parameters during treatment

T2*-weighted MRI as a non-contrast-enhanced method for assessment of focal laser ablation zone extent in prostate cancer thermotherapy.

To evaluate utility of T2*-weighted (T2*W) MRI as a tool for intra-operative identification of ablation zone extent during focal laser ablation (FLA) of prostate cancer (PCa), as compared to the current standard of contrast-enhanced T1-weighted (T1W) MRI. Fourteen patients with biopsy-confirmed low- to intermediate-risk localized PCa received MRI-guided (1.5T) FLA thermotherapy. Following FLA, axial multiple-TE T2*W images, diffusion-weighted images (DWI), and T2-weighted (T2W) images were acquired. Pre- and post-contrast T1W images were also acquired to assess ablation zone (n = 14) extent, as reference standard. Apparent diffusion coefficient (ADC) maps and subtracted contrast-enhanced T1W (sceT1W) images were calculated. Ablation zone regions of interest (ROIs) were outlined manually on all ablated slices. The contrast-to-noise ratio (CBR) of the ablation site ROI relative to the untreated contralateral prostate tissue was calculated on T2*W images and ADC maps and compared to that in sceT1W images. CBRs in ablation ROIs on T2*W images (TE = 32, 63ms) did not differ (p = 0.33, 0.25) from those in sceT1W images. Bland-Altman plots of ROI size and CBR in ablation sites showed good agreement between T2*W (TE = 32, 63ms) and sceT1W images, with ROI sizes on T2*W (TE = 63ms) strongly correlated (r = 0.64, p = 0.013) and within 15% of those in sceT1W images. In detected ablation zone ROI size and CBR, non-contrast-enhanced T2*W MRI is comparable to contrast-enhanced T1W MRI, presenting as a potential method for intra-procedural monitoring of FLA for PCa. • T2*-weighted MR images with long TE visualize post-procedure focal laser ablation zone comparably to the contrast-enhanced T1-weighted MRI. • T2*-weighted MRI could be used as a plausible method for repeated intra-operative monitoring of thermal ablation zone in prostate cancer, avoiding potential toxicity due to heating of contrast agent.

In vivo two-photon microscopic observation and ablation in deeper brain regions realized by modifications of excitation beam diameter and immersion liquid.

In vivo two-photon microscopy utilizing a nonlinear optical process enables, in living mouse brains, not only the visualization of morphologies and functions of neural networks in deep regions but also their optical manipulation at targeted sites with high spatial precision. Because the two-photon excitation efficiency is proportional to the square of the photon density of the excitation laser light at the focal position, optical aberrations induced by specimens mainly limit the maximum depth of observations or that of manipulations in the microscopy. To increase the two-photon excitation efficiency, we developed a method for evaluating the focal volume in living mouse brains. With this method, we modified the beam diameter of the excitation laser light and the value of the refractive index in the immersion liquid to maximize the excitation photon density at the focal position. These two modifications allowed the successful visualization of the finer structures of hippocampal CA1 neurons, as well as the intracellular calcium dynamics in cortical layer V astrocytes, even with our conventional two-photon microscopy system. Furthermore, it enabled focal laser ablation dissection of both single apical and single basal dendrites of cortical layer V pyramidal neurons. These simple modifications would enable us to investigate the contributions of single cells or single dendrites to the functions of local cortical networks.

Monitoring Focal Laser Ablation with Interstitial Fluence Probes: Monte Carlo Simulation and Phantom Validation.

Focal laser ablation offers a minimally invasive method of treating solid organ tumors via hyperthermia. Real-time monitoring of the induced tissue damage is critical for clinical success, and is typically accomplished using thermal measurements and Arrhenius models. In this manuscript, the utility of interstitial fluence probes in assessing coagulation directly in real-time was assessed through a Monte Carlo simulation and an experimental study in tissue mimicking prostate phantoms. In the simulation results, fluence increases greater than 100% were observed inside the coagulation zone, as coagulation effectively acts as a 'light trap'. Moreover, the passing of the coagulation boundary at any given point was shown to correspond with an inflection in fluence with a mean absolute difference of 0.1mm and 0.4mm observed for the simulation and phantom respectively. These results suggest that interstitial fluence probes may be capable of providing real-time feedback during focal laser ablation.

882 - Focal laser ablation versus radical prostatectomy for localized prostate cancer: Survival outcomes from a matched cohort

882 - Focal laser ablation versus radical prostatectomy for localized prostate cancer: Survival outcomes from a matched cohort

Comparative Effectiveness of Radiotherapy versus Focal Laser Ablation in Patients with Low and Intermediate Risk Localized Prostate Cancer

At present, focal laser ablation (FLA) as a new PCa local treatment has attracted attention. We aim at comparing the survival outcomes between radiotherapy (RT) and FLA to reveal whether FLA can be used as an alternative to RT for patients with low and intermediate-risk localized PCa.We conducted analyses with data from the SEER database (2004–2015). Propensity score matching and instrumental variate (IV) were used to reduce the influence of bias and unmeasured confounders maximally.In the adjusted multivariate regression, FLA had lower overall survival (OS) benefits (HR = 1.49; 95%CI: 1.18–1.87; p < 0.001). After propensity score matching, RT still had better OS (HR = 1.50; 95%CI: 1.17–1.93; p = 0.001). The outcomes of IV-adjusted analysis showed FLA was significantly inferior to RT in OS (HR = 1.49; 95%CI: 1.18–1.87). In the subgroup analyses, for those with PSA < 4 ng/mL, FLA showed markedly worse OS and cancer-specific mortality (CSM) outcomes (OS HR = 1.89; 95%CI: 1.01–3.53; p = 0.0466 and CSM HR = 4.25; 95%CI: 1.04–17.43; p = 0.044).FLA is a promising focal therapy of PCa. But our research demonstrated RT still had an obvious advantage in survival benefits over FLA. Using FLA as an alternative treatment for RT requires careful consideration by clinicians.

PD17-11 PHASE II CLINICAL TRIAL: SHORT-TERM ONCOLOGIC OUTCOMES OF NANOPARTICLE-DIRECTED FOCAL PHOTOTHERMAL LASER ABLATION

You have accessJournal of UrologyProstate Cancer: Localized: Ablative Therapy I (PD17)1 Apr 2020PD17-11 PHASE II CLINICAL TRIAL: SHORT-TERM ONCOLOGIC OUTCOMES OF NANOPARTICLE-DIRECTED FOCAL PHOTOTHERMAL LASER ABLATION Mahir Maruf*, Arvin George, Steven Canfield, Vahara Tamisetti, Ethan Wajswol, Alex Zhu, Matthew S. Davenport, Sara C. Lewis, and Ardeshir R. Rastinehad Mahir Maruf*Mahir Maruf* More articles by this author , Arvin GeorgeArvin George More articles by this author , Steven CanfieldSteven Canfield More articles by this author , Vahara TamisettiVahara Tamisetti More articles by this author , Ethan WajswolEthan Wajswol More articles by this author , Alex ZhuAlex Zhu More articles by this author , Matthew S. DavenportMatthew S. Davenport More articles by this author , Sara C. LewisSara C. Lewis More articles by this author , and Ardeshir R. RastinehadArdeshir R. Rastinehad More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000000860.011AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Whole gland treatment of low and intermediate risk prostate cancer (PCa) results in substantial morbidity with variable survival benefit. Focal therapy of PCa may be an alternative that provides cancer control while preserving quality of life. Nanoparticle directed focal photothermal laser ablation (FLA) is a novel ablative modality causing thermal ablation via laser excitation of gold nanoparticles. We aim to report short term oncologic efficacy of nanoparticle FLA. METHODS: In a single-arm multi-center Phase 1/2 clinical trial (NCT02680535), men with organ-confined Gleason Grade group (GGG) ≤ 3 PCa with an MRI visible lesion were prospectively enrolled. Prior to therapy, patients received an intravenous infusion of AuroShellsTM followed by laser excitation under MRI/US fusion guidance. A repeat MRI and fusion biopsy was performed 3 and 12 months post-ablation. The primary outcome of this study was presence of any PCa in the ablation zone at biopsy. Secondary outcome was success defined by the Delphi consensus criteria of any Gleason pattern 4 or GG1 >3mm cancer core length. RESULTS: In total, 45 patients were enrolled. After one patient withdrew, 44 patients (median age 69 years, PSA 8.7ng/ml, gland volume 48.5ml3, and PSA density 0.135 ng/ml2) with 45 lesions underwent nanoparticle directed FLA. At 3 months, 45 biopsies were performed, of which 30 (66.7%) were negative for any PCa. At 3 months, 25/41 patients (61%) had a PSA response >50%. A higher proportion of those with a negative biopsy at 3 months had a PSA response >50% when compared to those with a positive biopsy (64.3% vs 53.8%, p=0.524). Neither age, GGG, pre-treatment PSA, gland volume, or PSA density were associated with biopsy results at 3 months. At 12 months, 25 biopsies were performed of which 18 (72%) were negative for PCa. At 3 months, 35 of 45 (77.8%) lesions met Delphi consensus criteria for success following focal ablation. CONCLUSIONS: Nanoparticle-directed FLA is a feasible and promising ablative modality with acceptable short-term oncologic outcomes. Source of Funding: Philips Healthcare and Nanospectra Biosciences © 2020 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 203Issue Supplement 4April 2020Page: e373-e374 Advertisement Copyright & Permissions© 2020 by American Urological Association Education and Research, Inc.MetricsAuthor Information Mahir Maruf* More articles by this author Arvin George More articles by this author Steven Canfield More articles by this author Vahara Tamisetti More articles by this author Ethan Wajswol More articles by this author Alex Zhu More articles by this author Matthew S. Davenport More articles by this author Sara C. Lewis More articles by this author Ardeshir R. Rastinehad More articles by this author Expand All Advertisement PDF downloadLoading ...

Impact of 68Ga-PSMA-11 PET/CT on staging and management of prostate cancer patients in various clinical settings.

26 Background: The goal of this study was to determine the impact of 68Ga-PSMA-11 PET/CT on initial and subsequent management decisions in a cohort of PCa patients referred for various indications excluding the two main classical indications: BCR and pre-surgical staging. Methods: This is a prospective study of 197 patients that aimed to determine the impact of 68Ga-PSMA-11 PET/CT on PCa stage and management. Indications for PSMA PET/CT were initial staging of non-surgical candidates (30 patients) and re-staging after definitive treatment (n=168). The re-staging cohort comprised: patients re-staged with known advanced metastatic disease (n=103), after androgen deprivation therapy only (n=16), after surgery with serum PSA levels &lt;0.2 ng/ml (n=13), after radiation therapy (RT) not meeting the Phoenix criteria (n=22) and after other primary local treatments [i.e. HIFU, focal laser ablation, cryoablation, hyperthermia or irreversible electroporation] (n=13). Patients with BCR and candidates for curative surgery were excluded. Impact on management was assessed using pre- and post-PET questionnaires completed by referring physicians, electronic chart review and/or patient telephone encounters. Results: PSMA PET/CT changed disease stage in 135/197 (69%) patients (38% up-stage, 30% down-stage and no changes in stage in 32%). Management was affected in 104/182 (57%) patients. PSMA PET/CT had its greatest management impact in patients who were re-staged after RT. Conclusions: PSMA PET/CT has a profound impact on stage and management of PCa patients outside of the two main classical indications (BCR and presurgical staging) across all examined clinical scenarios. Clinical trial information: NCT04050215.

Abstract No. 468 Cost analysis of focal laser ablation for prostate cancer: in magnetic resonance imaging versus transrectal ultrasound fusion guidance outside magnetic resonance imaging

Abstract No. 468 Cost analysis of focal laser ablation for prostate cancer: in magnetic resonance imaging versus transrectal ultrasound fusion guidance outside magnetic resonance imaging

Magnetic resonance image-guided focal laser ablation in clinically localized prostate cancer: safety and efficacy.

To evaluate the safety and efficacy of focal laser ablation (FLA) in low-intermediate risk prostate cancer. Inclusion criteria were men aged 50-75 years, prostate-specific antigen (PSA) ≤15 ng/mL, clinical stage T1c-T2a, one or two lesions (PI-RADS ≥3) on magnetic resonance imaging (MRI), and Gleason score 6 (>3 mm) or Gleason 7 on targeted biopsy. Treatment success was defined as no clinically significant cancer in ablated areas. The study is prospective. Under MRI guidance, laser ablation was applied to the visible lesion(s). International Prostate Symptoms Score, Sexual Health Inventory in Men score and PSA levels were assessed at baseline and repeated at 1, 3, 6, 12 and 18 months. MRI was repeated at 3 and 12 months. Cancer control was assessed at 6 months using targeted and systematic biopsies. FLA was performed in 49 patients. Gleason scores were 3 + 3 in 13 patients (26.5%), 3 + 4 in 29 (59.2%) and 4 + 3 in 7 (14.3%). No significant complications were noticed. International Prostate Symptoms Score measurements up to 18 months were not different from baseline (all P > 0.05). Sexual Health Inventory in Men scores dropped in the first year (all P < 0.05), but were not different from baseline levels at 18 months (P = 0.097). PSA levels dropped significantly at 3-18 months (all P < 0.05). Treatment was successful in 39 patients (79.6%). Persistent cancer in treated areas was found in 10 patients (20.4%). FLA is safe with no impact on urinary and sexual functions at 18 months follow-up. Oncologic control is encouraging. Larger scale studies and longer follow-up are required.

Focal Laser Ablation for the Treatment of Focal Low-Intermediate Risk Prostate Cancer

Focal Laser Ablation for the Treatment of Focal Low-Intermediate Risk Prostate Cancer

Utility of Multiparametric MRI for Predicting Residual Clinically Significant Prostate Cancer After Focal Laser Ablation.

OBJECTIVE. The purpose of this study was to compare in a multireader manner the diagnostic accuracies of 3-T multiparametric MRI interpretation and serial prostate-specific antigen (PSA) measurement in predicting the presence of residual clinically significant prostate cancer after focal laser ablation. MATERIALS AND METHODS. Eighteen men had undergone focal laser ablation for low- or intermediate-risk prostate cancer as part of two National Cancer Institute-funded phase 1 clinical trials. Multiparametric MRI was performed immediately after and 6 and 12 months after focal laser ablation. Serial PSA measurements after focal laser ablation were recorded, and MRI-ultrasound fusion biopsy was performed 6 and 12 months after ablation and served as the reference standard. Multiparametric MRI was performed at 3 T with pelvic phased-array coils. T2-weighted, DW, and dynamic contrast-enhanced MR images were retrospectively assessed by two blinded radiologists using a 3-point Likert scale (0-2). Inter-reader agreement was assessed with the Cohen kappa statistic. The diagnostic accuracies of multiparametric MRI and PSA measurement were compared. RESULTS. Residual clinically significant prostate cancer was identified in 11 of 18 (61%) men. Logistic regression analysis of serial PSA measurements yielded a correct classification rate of 61.1% (p > 0.05). Using a multiparametric MRI threshold score of 4 or greater, both radiologists made correct classifications for 16 of 18 men (89%) at 6 months and 15 of 17 men (88%) at 12 months. Interreader agreement was substantial to excellent for T2-weighted imaging, DWI, and dynamic contrast-enhanced MRI and improved uniformly from 6 to 12 months. Logistic regression analysis of the retrospectively reviewed multiparametric MR images yielded AUCs greater than 0.90 for each radiologist 6 and 12 months after focal laser ablation (p < 0.001). CONCLUSION. Multiparametric MRI 6 and 12 months after focal laser ablation significantly outperformed serial PSA measurements for predicting the presence of residual clinically significant prostate cancer.

Contemporary treatments in prostate cancer focal therapy

Radical treatments for prostate cancer are associated with significant morbidity, including incontinence and erectile dysfunction. Advances in the field of prostate MRI and desire to reduce treatment morbidities have led to a rapid growth in focal treatments for prostate cancer. Here, we review novel focal prostate cancer treatments and their associated recent clinical data, with a particular focus on data reported within the last 24 months. High-intensity focal ultrasound, focal laser ablation, irreversible electroporation, focal cryotherapy, and photodynamic therapy have been used as treatment modalities for localized prostate cancer treatment. Despite the great variety of treatment techniques, each of these modalities is characterized by a significant rate of prostate cancer persistence within treatment zones (6-50%) and the presence of residual cancer within the prostate on rebiopsy (24-49%). These treatments, however, are associated with very low rates of high-grade complications, rare incontinence, and only mild or transient reductions in erectile function. The most common adverse events are urinary tract infections, hematuria, and urinary retention. Prostate cancer focal therapy is an attractive option for well-selected patients because of its low complication profile; however, long-term oncologic outcome is still lacking and early recurrence rates are high, limiting the ability of most urologic associations from endorsing its routine use.

Focal Laser Ablation of Prostate Cancer: Results in 120 Patients with Low- to Intermediate-Risk Disease

PurposeCan focal laser ablation (FLA) of low to intermediate risk prostate cancer preserve sexual and urinary function with low morbidity while providing adequate oncologic outcomes. Materials and MethodsTransrectal FLA was done in 120 patients with low- to intermediate-risk prostate cancer. MR imaging thermometry controlled ablation. At 6 and 12 months, patients had clinical and MR imaging follow-up with biopsy of suspicious areas. Patients submitted surveys of sexual and urinary function. Multivariate logistic regression identified determinants of positive imaging and biopsies. Two-sided Wilcoxon signed rank test evaluated scores and laboratory values. ResultsMedian patient age was 64 years, and median prostate-specific antigen (PSA) was 6.05 ng/mL. Median follow-up period was 34 months (range, 17–55 months). Gleason score was 3+3=6 in 37 (30.8%), 3+4=7 in 56 (46.7%), and 4+3=7 in 27 (22.5%) patients. Tumor stage was T1c in 89 (74.2%), T2a in 26 (21.7%), and T2b in 5 (4.2%) patients. Twenty (17%) patients had additional oncologic therapy 1 year after FLA when biopsy confirmed cancer following abnormal MR imaging. There was no difference between functional scores before and after ablation. Median PSA decreased to 3.25 at 12 months (P < .001). Tumor diameter above the median (odds ratio = 3.36; 95% confidence interval, 1.41–7.97) was the only significant predictor for positive MR imaging after treatment. ConclusionsOne year after FLA, selected patients had low morbidity, no significant changes in quality of life, and 83% freedom of retreatment rate. Sexual and urinary function did not significantly change after FLA.

Focal laser ablation as clinical treatment of prostate cancer: report from a Delphi consensus project

PurposeTo define the role of focal laser ablation (FLA) as clinical treatment of prostate cancer (PCa) using the Delphi consensus method.MethodsA panel of international experts in the field of focal therapy (FT) in PCa conducted a collaborative consensus project using the Delphi method. Experts were invited to online questionnaires focusing on patient selection and treatment of PCa with FLA during four subsequent rounds. After each round, outcomes were displayed, and questionnaires were modified based on the comments provided by panelists. Results were finalized and discussed during face-to-face meetings.ResultsThirty-seven experts agreed to participate, and consensus was achieved on 39/43 topics. Clinically significant PCa (csPCa) was defined as any volume Grade Group 2 [Gleason score (GS) 3+4]. Focal therapy was specified as treatment of all csPCa and can be considered primary treatment as an alternative to radical treatment in carefully selected patients. In patients with intermediate-risk PCa (GS 3+4) as well as patients with MRI-visible and biopsy-confirmed local recurrence, FLA is optimal for targeted ablation of a specific magnetic resonance imaging (MRI)-visible focus. However, FLA should not be applied to candidates for active surveillance and close follow-up is required. Suitability for FLA is based on tumor volume, location to vital structures, GS, MRI-visibility, and biopsy confirmation.ConclusionFocal laser ablation is a promising technique for treatment of clinically localized PCa and should ideally be performed within approved clinical trials. So far, only few studies have reported on FLA and further validation with longer follow-up is mandatory before widespread clinical implementation is justified.

Evaluation of tumor coverage after MR-guided prostate focal laser ablation therapy.

Prostate cancer is the most common noncutaneous cancer among men in the USA. Focal laser thermal ablation (FLA) has the potential to control small tumors while preserving urinary and erectile function by leaving the neurovascular bundles and urethral sphincters intact. Accurate needle guidance is critical to the success of FLA. Multiparametric magnetic resonance images (mpMRI) can be used to identify targets, guide needles, and assess treatment outcomes. In this study, we evaluated the location of ablation zones relative to targeted lesions in 23 patients who underwent FLA therapy in a phase II trial. The ablation zone margins and unablated tumor volume were measured to determine whether complete coverage of each tumor was achieved, which would be considered a clinically successful ablation. Preoperative mpMRI was acquired for each patient 2-3 months preceding the procedure and the prostate and lesion(s) were manually contoured on 3T T2-weighted axial images. The prostate and ablation zone(s) were also manually contoured on postablation 1.5T T1-weighted contrast-enhanced axial images acquired immediately after the procedure intraoperatively. The lesion surface was nonrigidly registered to the postablation image using an initial affine registration followed by nonrigid thin-plate spline registration of the prostate surfaces. The margins between the registered lesion and ablation zone were calculated using a uniform spherical distribution of rays, and the volume of intersection was also calculated. Each prostate was contoured five times to determine the segmentation variability and its effect on intersection of the lesion and ablation zone. Our study showed that the boundaries of the segmented tumor and ablation zone were close. Of the 23 lesions that were analyzed, 11 were completely covered by the ablation zone and 12 were partially covered. A shift of 1.0, 2.0, and 2.6mm would result in 19, 21, and all tumors completely covered by the ablation zone, respectively. The median unablated tumor volume across all tumors was 0.1 with an IQR of 3.7 , which was 0.2% of the median tumor volume (46.5 with an IQR of 46.3 ). The median extension of the tumors beyond the ablation zone, in cases which were partially ablated, was 0.9mm (IQR of 1.3mm), with the furthest tumor extending 2.6mm. In all cases, the boundary of the tumor was close to the boundary of the ablation zone, and in some cases, the boundary of the ablation zone did not completely enclose the tumor. Our results suggest that some of the ablations were not clinically successful and that there is a need for more accurate needle tracking and guidance methods. Limitations of the study include errors in the registration and segmentation methods used as well as different voxel sizes and contrast between theregistered T2 and T1 MRI sequences and asymmetric swelling of the prostate postprocedurally.

MRI Robot for Prostate Focal Laser Ablation: An Ex Vivo Study in Human Prostate

Purpose: A novel grid-template-mimicking MR-compatible robot was developed for in-gantry MRI-guided focal laser ablation of prostate cancer. Method: A substantially compact robot was designed and prototyped to meet in-gantry lithotomy ergonomics and allow for accommodation in the perineum. The controller software was reconfigured and integrated with the custom-designed navigation and multi-focal ablation software. Three experiments were conducted: (1) free space accuracy test; (2) phantom study under computed tomography (CT) guidance for image-guided accuracy test and overall workflow; and (3) magnetic resonance imaging (MRI)-guided focal laser ablation of an ex vivo prostate. The free space accuracy study included five targets that were selected across the workspace. The robot was then commanded five times to each target. The phantom study used a gel phantom made with color changing thermos-chromic ink, and four spherical metal fiducials were deployed with the robot. Then, laser ablation was applied, and the phantom was sliced for gross observation. For an MR-guided ex vivo test, a prostate from a donor who died of prostate cancer was obtained and multi-focally ablated using the system within the MRI gantry. The tissue was sliced after ablation for validation. Results: free-space accuracy was 0.38 ± 0.27 mm. The overall system targeting accuracy under CT guidance (including robot, registration, and insertion error) was 2.17 ± 0.47 mm. The planned ablation zone was successfully covered in both acrylamide gel phantom and in human prostate tissue. Conclusions: The new robot can accurately facilitate fiber targeting for MR-guided focal laser ablation of targetable prostate cancer.

Evaluation of Focal Laser Ablation of Prostate Cancer Using High Spectral and Spatial Resolution Imaging: A Pilot Study.

Focal laser ablation (FLA) is a minimally invasive thermal ablation, guided by MRI through an optical fiber, to induce coagulative necrosis in cancer. To evaluate the feasibility of high spectral and spatial resolution imaging using multiecho gradient echo (MEGE) MRI for identification of ablation zones, after FLA of prostate cancers. Prospective. Fourteen patients with biopsy-confirmed localized prostate cancers. FLA was performed under monitored conscious sedation with a 1.5T MRI scanner. Axial MEGE images were acquired before and after the last FLA. Pre- and postcontrast enhanced T1 -weighted (pT1 W) images were acquired to assess the FLA zone as a reference standard. The maps and water resonance peak height (WPH) images were calculated from the MEGE data. Ablation area was outlined using an active contour method. The maximum ablation area and total ablation volume were calculated from and WPH images, and compared with the sizes measured from pT1 W images. Nonparametric Kruskal-Wallis tests were performed to determine whether there was significant difference in calculated ablation areas and volumes between , WPH, and pT1 W images. Average (38.9 ± 14.1 msec) in the ablation area was significantly shorter (P = 0.03) than the preablation area (57.8 ± 25.3 msec). The normalized WPH value over the ablation area (1.3 ± 0.6) was significantly decreased (P = 0.02) more than the preablation area (2.0 ± 0.9). The maximum ablation areas measured by (295.7 ± 96.4 mm2 ), WPH (312.2 ± 63.0 mm2 ), and pT1 W (320.3 ± 82.9 mm2 ) images were all similar. Furthermore, there was no significant difference (P = 0.31) for measured ablation volumes 3310.5 ± 649.5, 3406.4 ± 684.9, and 3672.5 ± 832.4 mm3 between , WPH, and pT1 W images, respectively. DATA CONCLUSION: and WPH images provide acceptable measurements of ablation zones during FLA treatment of prostate cancers without the need for contrast agent injection. This might allow repeated assessment following each heating period so that subsequent ablations can be optimized. 2 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2019;49:1374-1380.

MRI Findings After MRI-Guided Focal Laser Ablation of Prostate Cancer.

The purpose of this study is to describe the quantitative and qualitative findings of multiparametric prostate MRI performed after MRI-guided focal laser ablation of prostate cancer. A total of 27 consenting patients met the study inclusion criteria, which included but were not limited to the presence of clinical category T1c-T2a prostate cancer with a Gleason score of 7 or less, having undergone prostate biopsy before and after focal laser ablation, and having undergone MRI before ablation, immediately after ablation, and 3 and 12 months after ablation. Signal changes were evaluated both qualitatively and quantitatively and were then correlated with the results of subsequent biopsy performed at 3 and 12 months after ablation. MRI performed immediately after ablation revealed a hypovascular defect in the ablation zone, with patchy or bandlike decreased T2 signal most commonly noted at 3 months (in 66.7% of ablated lesions) and T2 scarring observed in most lesions (66.7%) at 12 months. Patchy or bandlike decreased apparent diffusion coefficient signal and scarlike changes were most prevalent at 3 months after ablation (50.0% of lesions), and these features remained the most commonly observed findings at 12 months after ablation (27.8% of lesions). At 12 months after ablation, 10 patients were found to have recurrent tumor, with three patients found to have persistent cancer when biopsy was performed at the ablation site. All postablation biopsy cases with positive results showed suspicious T2 and apparent diffusion coefficient characteristics, which were considered to be a well-defined nodular intermediate signal on both of these sequences. Two of the patients for whom positive biopsy findings were noted had focal enhancement of the ablation zone. A significant reduction in the forward volume transfer constant after ablation was found at the ablation site on follow-up examination. Multiparametric MRI can reveal postablation changes in the prostate and can be a valuable tool for monitoring patients who have undergone MRI-guided focal laser ablation.

Two-year Outcomes Following Focal Laser Ablation of Localized Prostate Cancer

BackgroundThere is no consensus regarding how to assess oncological control following focal ablation of prostate cancer. ObjectiveTo assess quality of life and in-field recurrence following focal laser ablation (FLA). Design, setting, and participantsOf 34 men participating in a prospective outcomes study following FLA, 32 underwent prostate-specific antigen (PSA) testing and magnetic resonance imaging (MRI) at 6 mo and 2 yr. All underwent assessment of urinary and sexual function at 1 yr. InterventionFLA and MRI-targeted biopsy of the ablation zone. Outcome measurements and statistical analysisThe American Urological Association Symptom Score and the Sexual Health Inventory for Men at baseline and 12 mo were compared using a two-sided Wilcoxon signed-rank test with a significance level of p=0.05. The percentage of positive and negative in-field biopsies was calculated for suspicious and nonsuspicious post-ablation MRI scans. Results and limitationsFLA was associated with no adverse impact on urinary or sexual function. For men with suspicious MRI (MRI+) findings, in-field disease recurrence of intermediate and low risk disease was detected in 75% and 25% of cases, respectively. For men with nonsuspicious MRI (MRI−) findings, in-field disease recurrence of intermediate- and low-risk disease was detected in 22.4% and 50% of cases, respectively. The change in PSA from baseline did not discriminate cases with MRI− findings with and without cancer at 2 yr. ConclusionsMRI reliably identifies in-field recurrence of only intermediate-risk prostate cancer at 2 yr after FLA. A biopsy of the ablation zone must be performed for MRI+ findings. The decision to perform an ablation-zone biopsy for men with MRI− scans should be influenced by whether detection of low-risk disease would influence management. Patient summaryOur study provides compelling evidence that men should undergo interval magnetic resonance imaging to assess the probability of intermediate-risk disease in the ablation zone following focal laser ablation of localized prostate cancer.