3D Prostate Models Research Articles

Impact of Relative Volume Difference Between Magnetic Resonance Imaging and Three-dimensional Transrectal Ultrasound Segmentation on Clinically Significant Prostate Cancer Detection in Fusion Magnetic Resonance Imaging–targeted Biopsy

BackgroundSegmentation of three-dimensional (3D) transrectal ultrasound (TRUS) images is known to be challenging, and the clinician often lacks a reliable and easy-to-use indicator to assess its accuracy during the fusion magnetic resonance imaging (MRI)-targeted prostate biopsy procedure. ObjectiveTo assess the effect of the relative volume difference between 3D-TRUS and MRI segmentation on the outcome of a targeted biopsy. Design, setting, and participantsAll adult males who underwent an MRI-targeted prostate biopsy for clinically suspected prostate cancer between February 2012 and July 2021 were consecutively included. InterventionAll patients underwent a fusion MRI-targeted prostate biopsy with a Koelis device. Outcome measurements and statistical analysisThree-dimensional TRUS and MRI prostate volumes were calculated using 3D prostate models issued from the segmentations. The primary outcome was the relative segmentation volume difference (SVD) between transrectal ultrasound and MRI divided by the MRI volume (SVD = MRI volume − TRUS volume/MRI volume) and its correlation with clinically significant prostate cancer (eg, International Society of Urological Pathology [ISUP] ≥2) positiveness on targeted biopsy cores. Results and limitationsOverall, 1721 patients underwent a targeted biopsy resulting in a total of 5593 targeted cores. The median relative SVD was significantly lower in patients diagnosed with clinically significant prostate cancer than in those with ISUP 0–1: (6.7% [interquartile range {IQR} –2.7, 13.6] vs 8.0% [IQR 3.3, 16.4], p < 0.01). A multivariate regression analysis showed that a relative SVD of >10% of the MRI volume was associated with a lower detection rate of clinically significant prostate cancer (odds ratio = 0.74 [95% confidence interval: 0.55–0.98]; p = 0.038). ConclusionsA relative SVD of >10% of the MRI segmented volume was associated with a lower detection rate of clinically significant prostate cancer on targeted biopsy cores. The relative SVD can be used as a per-procedure quality indicator of 3D-TRUS segmentation. Patient summaryA discrepancy of ≥10% between segmented magnetic resonance imaging and transrectal ultrasound volume is associated with a reduced ability to detect significant prostate cancer on targeted biopsy cores.

PD27-04 AURORA A 3D MODEL GUIDED NERVE SPARING TECHNIQUE IN ROBOTIC RADICAL PROSTATECTOMY

You have accessJournal of UrologyCME1 Apr 2023PD27-04 AURORA A 3D MODEL GUIDED NERVE SPARING TECHNIQUE IN ROBOTIC RADICAL PROSTATECTOMY Christian Engesser, Brantner Philip, Julian Gehweiler, Matthias Walter, Christian Wetterauer, Helge Seifert, Svetozar Subotic, Cyrill Rentsch, Lukas Bubendorf, Tatjana Vlajnic, Abolfazl Hosseini, and Jan Ebbing Christian EngesserChristian Engesser More articles by this author , Brantner PhilipBrantner Philip More articles by this author , Julian GehweilerJulian Gehweiler More articles by this author , Matthias WalterMatthias Walter More articles by this author , Christian WetterauerChristian Wetterauer More articles by this author , Helge SeifertHelge Seifert More articles by this author , Svetozar SuboticSvetozar Subotic More articles by this author , Cyrill RentschCyrill Rentsch More articles by this author , Lukas BubendorfLukas Bubendorf More articles by this author , Tatjana VlajnicTatjana Vlajnic More articles by this author , Abolfazl HosseiniAbolfazl Hosseini More articles by this author , and Jan EbbingJan Ebbing More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000003305.04AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Nerve-sparing (NS) procedures in radical prostatectomy have gained importance as they show better functional outcomes in terms of erectile function. It is recommended that the neurovascular bundle (NVB) should be removed if residual tumor is suspected. Alternatively, intraoperative fresh frozen section (FFS) may help in this decision. However, standard FFS techniques do not provide a direct visual impression of the positive surgical margin (PSM) for guidance regarding secondary resection (SR) at the GNB. We therefore intend to optimize precision for SR using a personalized 3D printed prostate model in robotic-assisted radical prostatectomy (RARP). METHODS: We prospectively included 100 patients in which NS-RARP was performed between September 2018 and August 2021 at the University Hospital Basel and Cantonal Hospital Basel-Land. Image data of the preoperative pelvic MRI scan were used to render and print a personalized 3D prostate model. PIRADS lesions (>grade 3) and potential capsular involvement were color-characterized in the model. The model was used during surgery to allow the pathologist to mark a positive surgical margin (PSM) on the model and to help guide the surgeon for selective SR (SSR). Functional outcome was assessed using IIEF-5 prior and one year after surgery. RESULTS: 17.0% (17/100) of all patients had PSM in final histology with a rate of 15.4% in pT2 and 25% in pT3 tumors, respectively. PSM was identified during FFS in 23.0% (23/100) of patients, and SSR achieved a tumor-free surgical margin on final histology in 19 of these 23 patients (82.6%), with SSR containing tumor tissue in 9 of 23 patients (39.1%). Intraoperative PSM was associated with a PIRADS lesion in 11 patients (48%). PSA was undetectable 6 weeks postoperatively in 18/19 (94.7%) patients with successful SSR but only in 76.5 % of patients with PSM in final pathology. False negative rate of FFS was 16.9% (13/77). Despite 6/8 (75%) patients with biochemical recurrence (BCR) having a PSM successfully converted, only 1 had imageproven local recurrence in PSMA PET CT. CONCLUSIONS: 3D printed prostate models are a promising approach to precision SSR and improve communication between surgeons and pathologists. Successful conversion rates (82.6%) were similar to procedures using NEUROSafe (86%). The sensitivity of MRI, the false-negative rate of conventional FFS and cost effectiveness remain critical limitations. Source of Funding: Intuitive Surgical © 2023 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 209Issue Supplement 4April 2023Page: e742 Advertisement Copyright & Permissions© 2023 by American Urological Association Education and Research, Inc.MetricsAuthor Information Christian Engesser More articles by this author Brantner Philip More articles by this author Julian Gehweiler More articles by this author Matthias Walter More articles by this author Christian Wetterauer More articles by this author Helge Seifert More articles by this author Svetozar Subotic More articles by this author Cyrill Rentsch More articles by this author Lukas Bubendorf More articles by this author Tatjana Vlajnic More articles by this author Abolfazl Hosseini More articles by this author Jan Ebbing More articles by this author Expand All Advertisement PDF downloadLoading ...

3D-Reconstructed Contact Surface Area and Tumour Volume on Magnetic Resonance Imaging Improve the Prediction of Extraprostatic Extension of Prostate Cancer.

This study is to determine whether the volume and contact surface area (CSA) of a tumour with an adjacent prostate capsule on MRI in a three-dimensional (3D) model that can predict side-specific extraprostatic extension (EPE) at radical prostatectomy (RP). Patients with localised prostate cancer (PCa) who underwent robot-assisted RP between July 2015 and March 2021 were included in this retrospective study. MRI-based 3D prostate models incorporating the PCa volume and location were reconstructed. The tumour volume and surface variables were extracted. For the prostate-to-tumour and tumour-to-prostate CSAs, the areas in which the distances were ≤ 1, ≤ 2, ≤ 3, ≤ 4, and ≤ 5mm were defined, and their surface (cm2) were determined. Differences in prostate sides with and without pathological EPE were analysed. Multivariable logistic regression analysis to find independent predictors of EPE. Overall, 75/302 (25%) prostate sides showed pathological EPE. Prostate sides with EPE had higher cT-stage, higher PSA density, higher percentage of positive biopsy cores, higher biopsy Gleason scores, higher radiological tumour stage, larger tumour volumes, larger prostate CSA, and larger tumour CSA (all p < 0.001). Multivariable logistic regression analysis showed that the radiological tumour stage (p = 0.001), tumour volume (p < 0.001), prostate CSA (p < 0.001), and tumour CSA (p ≤ 0.001) were independent predictors of pathological EPE. A 3D reconstruction of tumour locations in the prostate improves prediction of extraprostatic extension. Tumours with a higher 3D-reconstructed volume, a higher surface area of tumour in contact with the prostate capsule, and higher surface area of prostate capsule in contact with the tumour are at increased risk of side-specific extraprostatic extension.

Development and clinical applicability of MRI-based 3D prostate models in the planning of nerve-sparing robot-assisted radical prostatectomy.

The interpretation of conventional MRI may be limited by the two-dimensional presentation of the images. To develop patient-specific MRI prostate-based virtual and three-dimensional (3D)-printed models. To assess the association between 3D imaging and the pathological outcome of RARP specimen. To assess the clinical applicability of 3D models to guide nerve-sparing robot-assisted radical prostatectomy (RARP). We created virtual 3D and 3D-printed 3D models of 20 prostate cancer patients retrospectively. A comparison was made between conventional MRI and 3D-reconstructed images. The concordance between tumour lesion location in 3D models and pathology reporting of RARP specimens was assessed. Seven urologists assessed the side-specific extent of nerve-sparing based on (1) conventional MR images, (2) virtual 3D models, and (3) 3D-printed models. Clinically relevant changes in nerve-sparing and the absolute agreement between observers was analyzed using the Chi-square test and intra-class correlation coefficient (ICC). The index lesion was correctly visualized in 19/20 (95%) 3D models and the expected location of extraprostatic extension was correctly visualized in all 3D models. Clinically relevant changes in the planned extent of nerve-sparing between MRI and virtual 3D models and MRI and 3D-printed models were found in 25% and 26%. The ICC of the planned extent of nerve-sparing between urologists was 0.40 (95% CI 0.28-0.55) for conventional MRI, 0.52 (95% CI 0.39-0.66) for virtual 3D models and 0.58 (95% CI 0.45-0.71) for 3D-printed models. 3D models of the MRI prostate to guide RARP could aid urologists in the planning of nerve-sparing surgery as shown by a higher inter-observer agreement.

PD61-01 THE USE OF 3D VIRTUAL MODELS DURING ROBOT ASSISTED RADICAL PROSTATECTOMY ENSURES A REDUCTION OF POSITIVE SURGICAL MARGINS RATE

You have accessJournal of UrologyProstate Cancer: Localized: Surgical Therapy V (PD61)1 Sep 2021PD61-01 THE USE OF 3D VIRTUAL MODELS DURING ROBOT ASSISTED RADICAL PROSTATECTOMY ENSURES A REDUCTION OF POSITIVE SURGICAL MARGINS RATE Enrico Checcucci, Angela Pecoraro, Sabrina De Cillis, Daniele Amparore, Federico Piramide, Alberto Piana, Gabriele Volpi, Paolo Alessio, Michele Sica, Stefano Granato, Stefano Piscitello, Beatrice Carbonaro, Giovanni Cattaneo, Matteo Manfredi, Cristian Fiori, and Francesco Porpiglia Enrico CheccucciEnrico Checcucci More articles by this author , Angela PecoraroAngela Pecoraro More articles by this author , Sabrina De CillisSabrina De Cillis More articles by this author , Daniele AmparoreDaniele Amparore More articles by this author , Federico PiramideFederico Piramide More articles by this author , Alberto PianaAlberto Piana More articles by this author , Gabriele VolpiGabriele Volpi More articles by this author , Paolo AlessioPaolo Alessio More articles by this author , Michele SicaMichele Sica More articles by this author , Stefano GranatoStefano Granato More articles by this author , Stefano PiscitelloStefano Piscitello More articles by this author , Beatrice CarbonaroBeatrice Carbonaro More articles by this author , Giovanni CattaneoGiovanni Cattaneo More articles by this author , Matteo ManfrediMatteo Manfredi More articles by this author , Cristian FioriCristian Fiori More articles by this author , and Francesco PorpigliaFrancesco Porpiglia More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002098.01AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Positive surgical margins (PSM) after radical prostatectomy represent a worrying circumstance for both surgeons and patients, leading to a higher rate of biochemical recurrence (BCR). The aim of this study was to investigate the role of 3D model during robot assisted radical prostatectomy (RARP) in reducing the PSM rate. METHODS: We prospectively enrolled patients with localised prostate cancer (cT1–3, cN0, cM0) undergoing preoperative Multiarametric Magnetic Resonance Imaging (mpMRI) and subsequent RARP at our Centre from January 2016 to January 2020. Thanks to the support of bioengineers, starting from mpMRI bidimensional images, hyper accuracy 3D (HA3DTM) prostate models were realized. The first surgeon had the opportunity to use the models during the intervention in a cognitive or augmented reality setting. Demographic and perioperative variables were collected. The nerve sparing (NS) approach according to Pasadena classification and the PSM rate were evaluated both in 3D and non-3D groups. Modelling relied on multivariable logistic regression (MLR) models predicting the presence of PSM in the overall population and in 4 specific subgroups of patients: extra capsular extension patients, D’Amico high risk category, positive Digital Rectal Exam (DRE), cT3 patients. RESULTS: 757 patients were enrolled. 3D technology was used in 160 patients during the procedure. In particular, both 3D cognitive (n=56, 35%) and 3D augmented reality (n=104, 65%) procedure were performed. No differences were observed in terms of preoperative and demographic characteristics and complications rates between 3D and non-3D groups. 3D patients were treated more often with full NS approach (20.6 vs. 12.7%, p <0.05) and had lower PSM rates (25 vs. 35.3%, p=0.01), compared to their non-3D counterpart. A subgroup analysis according to the type of NS showed no difference in terms of PSM rates between the two groups (33% vs. 36.8%, 22.9% vs. 32.1% and 22.7% vs.37.4% for respectively full, intermediate and standard NS approach, p >0.05). Finally, at MLR, the availability of 3D technology (OR: 0.5, CI:0.3-0.8, p=0.005) and the absence of extracapsular extension (ECE, OR: 0.6, CI:0.4-0.9, p=0.004) at mpMRI were independent predictors of lower rates of PSM. CONCLUSIONS: The use of 3D models during RARP allows to decrease the PSM rates. Moreover, it grants a more conservative NS approach, without compromising the PSM rate. However, the low sample size does not allow to identify a specific subgroup of patients in whom the advantage of 3D technology is maximized. Source of Funding: None © 2021 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 206Issue Supplement 3September 2021Page: e1066-e1066 Advertisement Copyright & Permissions© 2021 by American Urological Association Education and Research, Inc.MetricsAuthor Information Enrico Checcucci More articles by this author Angela Pecoraro More articles by this author Sabrina De Cillis More articles by this author Daniele Amparore More articles by this author Federico Piramide More articles by this author Alberto Piana More articles by this author Gabriele Volpi More articles by this author Paolo Alessio More articles by this author Michele Sica More articles by this author Stefano Granato More articles by this author Stefano Piscitello More articles by this author Beatrice Carbonaro More articles by this author Giovanni Cattaneo More articles by this author Matteo Manfredi More articles by this author Cristian Fiori More articles by this author Francesco Porpiglia More articles by this author Expand All Advertisement Loading ...

Multi-colour extrusion fused deposition modelling: a low-cost 3D printing method for anatomical prostate cancer models

Three-dimensional (3D) printed prostate cancer models are an emerging adjunct for urological surgical planning and patient education, however published methods are costly which limits their translation into clinical practice. Multi-colour extrusion fused deposition modelling (FDM) can be used to create 3D prostate cancer models of a quality comparable to more expensive techniques at a fraction of the cost. Three different 3D printing methods were used to create the same 3D prostate model: FDM, colour jet printing (CJP) and material jetting (MJ), with a calculated cost per model of USD 20, USD 200 and USD 250 respectively. When taking into account the cost, the FDM prostate models are the most preferred 3D printing method by surgeons. This method could be used to manufacture low-cost 3D printed models across other medical disciplines.

V14-05 MRI FUSION GUIDED PROSTATE PARTIAL GLAND CRYOABLATION AIDED BY A VIRTUAL 3D MODELING: A STEP BY STEP ILLUSTRATION

You have accessJournal of UrologyProstate Cancer (V14)1 Apr 2020V14-05 MRI FUSION GUIDED PROSTATE PARTIAL GLAND CRYOABLATION AIDED BY A VIRTUAL 3D MODELING: A STEP BY STEP ILLUSTRATION Ezequiel Becher*, Nicole Wake, Zachary Tano, Nermarie Velazquez, Herbert Lepor, and James Wysock Ezequiel Becher*Ezequiel Becher* More articles by this author , Nicole WakeNicole Wake More articles by this author , Zachary TanoZachary Tano More articles by this author , Nermarie VelazquezNermarie Velazquez More articles by this author , Herbert LeporHerbert Lepor More articles by this author , and James WysockJames Wysock More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000000982.05AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: To describe our technique for prostate partial gland cryoablation (PGCy) aided by a virtual 3D model and with magnetic resonance imaging (MRI)- ultrasound (US) fusion guidance. METHODS: Preoperatively, multiparametric prostate MRI imaging is used to develop a 3D virtual prostate model defining tumor location and planned treatment margin as well as critical structures such as the urethra, neurovascular bundle and rectum. This model also allows pre-treatment simulation using 3D virtual cryoprobes. Planning for number of treatment probes and probe configuration/location are simulated using this model to ensure confluent treatment volume. The cryoablation procedure is performed under general anesthesia with the patient in dorsal lithotomy position. A biplanar transrectal ultrasound probe is used to visualize the prostate. The Navigo® transperineal MRI-US fusion system creates 3D ultrasound segmentation and performs MRI registration prior to cryoprobe placement. A 1 cm tumor margin is employed. Combining the fusion image guidance and 3D virtual planning, cryoprobe and thermocouple placement planning is performed. After placement of a urethral warming catheter, two freeze-thaw cycles are performed. Treatment temperatures and US monitoring of ice development are performed in real-time. The procedure is completed after adequate treatment volume and a target freeze temperature has been achieved. An additional third freeze-thaw cycle may be performed on a case-by-case basis. RESULTS: This case illustrates PGCy using 3D pre-ablation modeling. The pretreatment model based upon mpMRI and assuming a 1 cm margin predicted use of 3 cryoprobes to achieve confluent treatment volume. The use of MRI-US fusion and execution of the 3D modeling is demonstrated. PGCy was safely done with 2 freeze / thaw cycles. CONCLUSIONS: Our virtual 3D model and MRI fusion guidance allowed us to plan for a more accurate and oncologically safe PGCy. This video also serves to show our technique to approaching PGCy. Source of Funding: Department of Urology, NYU Langone Health. © 2020 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 203Issue Supplement 4April 2020Page: e1307-e1307 Advertisement Copyright & Permissions© 2020 by American Urological Association Education and Research, Inc.MetricsAuthor Information Ezequiel Becher* More articles by this author Nicole Wake More articles by this author Zachary Tano More articles by this author Nermarie Velazquez More articles by this author Herbert Lepor More articles by this author James Wysock More articles by this author Expand All Advertisement PDF downloadLoading ...

Application of U-shaped convolutional neural network in auto segmentation and reconstruction of 3D prostate model in laparoscopic prostatectomy navigation

To investigate the efficacy of intraoperative cognitive navigation on laparoscopic radical prostatectomy using 3D prostatic models created by U-shaped convolutional neural network (U-net) and reconstructed through Medical Image Interaction Tool Kit (MITK) platform. A total of 5 000 pieces of prostate cancer magnetic resonance (MR) imaging discovery sets with manual annotations were used to train a modified U-net, and a set of clinically demand-oriented, stable and efficient full convolutional neural network algorithm was constructed. The MR images were cropped and segmented automatically by using modified U-net, and the segmentation data were automatically reconstructed using MITK platform according to our own protocols. The modeling data were output as STL format, and the prostate models were simultaneously displayed on an android tablet during the operation to help achieving cognitive navigation. Based on original U-net architecture, we established a modified U-net from a 201-case MR imaging training set. The network performance was tested and compared with human segmentations and other segmentation networks by using one certain testing data set. Auto segmentation of multi-structures (such as prostate, prostate tumors, seminal vesicles, rectus, neurovascular bundles and dorsal venous complex) were successfully achieved. Secondary automatic 3D reconstruction had been carried out through MITK platform. During the surgery, 3D models of prostatic area were simultaneously displayed on an android tablet, and the cognitive navigation was successfully achieved. Intra-operation organ visualization demonstrated the structural relationships among the key structures in great detail and the degree of tumor invasion was visualized directly. The modified U-net was able to achieve automatic segmentations of important structures of prostate area. Secondary 3D model reconstruction and demonstration could provide intraoperative visualization of vital structures of prostate area, which could help achieve cognitive fusion navigation for surgeons. The application of these techniques could finally reduce positive surgical margin rates, and may improve the efficacy and oncological outcomes of laparoscopic prostatectomy.

Histology core‐specific evaluation of the European Society of Urogenital Radiology (ESUR) standardised scoring system of multiparametric magnetic resonance imaging (mpMRI) of the prostate

To evaluate the Prostate Imaging Reporting and Data System (PIRADS) in multiparametric magnetic resonance imaging (mpMRI) based on single cores and single-core histology. To calculate positive (PPV) and negative predictive values (NPV) of different modalities of mpMRI. We performed MRI-targeted transrectal ultrasound-guided perineal prostate biopsies on 50 patients (mean age 66 years, mean PSA level of 9.9 ng/mL) with suspicion of prostate cancer. The biopsy trajectories of every core taken were documented in three dimensions (3D) in a 3D-prostate model. Every core was evaluated separately for prostate cancer and the performed biopsy trajectories were projected on mpMRI images. PIRADS scores of 1177 cores were then assessed by a histology 'blinded' uro-radiologist in T2-weighted (T2W), dynamic contrast-enhanced (DCE), diffusion-weighted imaging (DWI) and magnetic resonance spectroscopy (MRS). The PIRADS score was significantly higher in cores positive for cancer than in negative cores. There was a significant correlation between the PIRADS score and histopathology for every modality. Receiver operating characteristic (ROC) analysis showed excellent specificity for T2W (90% peripheral zone/97% transition zone) and DWI (98%/97%) images regardless of the prostate region observed. These numbers decreased for DCE (80%/93%) and MRS (76%/83%). All modalities had NPVs of 99%, if a PIRADS score threshold of 2 (for T2W, DCE, and MRS) or 3 (for DWI) was used. However, PPVs were low. Our results show that PIRADS scoring is feasible for clinical routine and allows standardised reporting. PIRADS can be used as a decision-support system for targeting of suspicious lesions. mpMRI has a high NPV for prostate cancer and, thus, might be a valuable tool in the initial diagnostic evaluation.

Can transrectal needle biopsy be optimised to detect nearly all prostate cancer with a volume of ≥0.5 mL? A three‐dimensional analysis

To investigate whether transrectal needle biopsy can be optimised to detect nearly all prostate cancer with a tumour volume (TV) of ≥0.5 mL. Retrospectively analysed 109 whole-mounted and entirely submitted radical prostatectomy specimens with prostate cancer. All tumours in each prostate were outlined on whole-mount slides and digitally scanned to produce tumour maps. Tumour map images were exported to three-dimensional (3D) slicer software (http://www.slicer.org) to develop a 3D-prostate cancer model. In all, 20 transrectal biopsy schemes involving two to 40 cores and two to six anteriorly directed biopsy (ADBx) cores (including transition zone, TZ) were simulated, as well as models with various biopsy cutting lengths. Detection rates for tumours of different volumes were determined for the various biopsy simulation schemes. In 109 prostates, 800 tumours were detected, 90 with a TV of ≥0.5 mL (mean TV 0.24 mL). Detection rate for tumours with a TV of ≥0.5 mL plateaued at 77% (69/90) using a 12-core (3 × 4) scheme, standard 17-mm biopsy cutting length without ADBx cores. In all, 20 of 21 (95%) tumours with a TV of ≥0.5 mL not detected by this scheme originated in the anterior peripheral zone or TZ. Increasing the biopsy cutting length and depth/number of ADBx cores improved the detection rate for tumours with a TVof ≥0.5 mL in the 12-core scheme. Using a 22-mm cutting length and a 12-core scheme with additional volume-adjusted ADBx cores, 100% of ≥0.5 mL tumours in prostates ≤ 50 mL in volume and 94.7% of ≥0.5 mL tumours in prostates > 50 mL in volume were detected. Our 3D-prostate cancer model analysis suggests that nearly all prostate cancers with a TV of ≥0.5 mL can be detected by 14-18 transrectal needle-biopsy cores. Using longer biopsy cutting lengths and increasing the depth and number of ADBx cores (including TZ) according to prostate volume are necessary as well.

2054 VALUE OF TARGETED BIOPSY IN DETECTING PROSTATE CANCER USING AN OFFICE-BASED MR-US FUSION DEVICE

INTRODUCTION AND OBJECTIVES: Targeted biopsy (Bx) of prostate lesions identified on MRI may enhance detection of prostate cancer (CaP). We previously described the initial clinical use of a 3D Bx tracking and targeting device (Figure A) that fuses MRI with real-time ultrasound (US), permitting targeted prostate Bx (Artemis; Eigen, Grass Valley, CA; Urol. Oncol. 29: 334, 2011). We now evaluate CaP detection rates in 174 consecutive patients. METHODS: Subjects in this IRB-approved study were either in active surveillance (N 107) or had prior negative biopsies but persistently elevated PSA (N 67). Biopsies took place from 3/2010 to 9/2011. Prior to Bx, each man had multiparametric 3 Tesla MRI with T2-weighted imaging (T2WI), dynamic contrast enhancement (DCE), and diffusion-weighted imaging (DWI). No endorectal coil was used. Lesions (targets) on MRI were outlined in 3D and assigned increasing cancer suspicion levels (image grade 2 to 5) by a uro-radiologist. The Artemis device then fused the stored MRI with real-time US, generating a 3D prostate model on-the-fly (Figure B). Working from the 3D model, transrectal Bx of target lesions at 3 mm intervals and 12 systematic Bx were performed under local anesthesia in the clinic. RESULTS: 174 subjects (mean age 64.5) underwent 183 fusion biopsy sessions. At Bx, median PSA 4.9 ng/ml and prostate volume 42 cc. Mean time from probe insertion to last Bx was 20 minutes. Of 291 MRI targets, 263 were successfully sampled. CaP was found in 95 men, including 36% with Gleason 7. 7% of 1871 systematic cores revealed CaP vs 21% of 488 targeted cores (p 0.0001). Targeted Bx findings correlated with level of suspicion on MRI (Table). 16 of 17 men with an image grade 5 target (mean MRI lesion diameter 14 mm 6 mm) were found to have CaP, including 6 with Gleason 7. DWI (ADC 1000 m2/sec) and size of lesion on T2WI ( 1.0 cm dia) were the most powerful predictors of Gleason 7 CaP. CONCLUSIONS: Prostate lesions identified on MRI can be accurately targeted using MRI-US fusion Bx in a clinic setting. Bx findings correlate with level of suspicion on MRI.

36. Generation of 3D prostate models for computerized cryosurgery training

36. Generation of 3D prostate models for computerized cryosurgery training

Computerized planning of prostate cryosurgery using variable cryoprobe insertion depth

The current study presents a computerized planning scheme for prostate cryosurgery using a variable insertion depth strategy. This study is a part of an ongoing effort to develop computerized tools for cryosurgery. Based on typical clinical practices, previous automated planning schemes have required that all cryoprobes be aligned at a single insertion depth. The current study investigates the benefit of removing this constraint, in comparison with results based on uniform insertion depth planning as well as the so-called “pullback procedure”. Planning is based on the so-called “bubble-packing method”, and its quality is evaluated with bioheat transfer simulations. This study is based on five 3D prostate models, reconstructed from ultrasound imaging, and cryoprobe active length in the range of 15–35 mm. The variable insertion depth technique is found to consistently provide superior results when compared to the other placement methods. Furthermore, it is shown that both the optimal active length and the optimal number of cryoprobes vary among prostate models, based on the size and shape of the target region. Due to its low computational cost, the new scheme can be used to determine the optimal cryoprobe layout for a given prostate model in real time.

In vitro validation of a 3-dimensional transrectal ultrasound system for prostate biopsiess

Introduction: Transrectal ultrasound (TRUS) prostate biopsy (Bx) is currently confined to 2D information to both target and record 3D Bx locations. Accurate placement of Bx needles cannot be verified without 3D information, and recording Bx sites in 2D does not provide sufficient information to accurately guide the high incidence of repeat Bx. We have designed a 3D TRUS prostate Bx system that augments the current 2D TRUS system and provides tools for biopsy-planning, needle guidance, and recording of the biopsy core locations entirely in 3D.&#x0D; Methods: Our Bx system displays a 3D model of the patient’s prostate, which is generated intra-procedure from a collection of 2D TRUS images, representative of the particular prostate shape. Bx targets are selected, needle guidance is facilitated, and 3D Bx sites are recorded within the 3D context of the prostate model. The complete 3D Bx system was validated, in vitro, by performing standard ten-core Bx on anatomical phantoms of two patient’s prostates. The accuracy of the needle-guidance, Bx location recording, and 3D model volume and surface topology were validated against a CT gold standard. &#x0D; Results: The Bx system successfully reconstructed the 3D patient prostate models with a mean volume error of 3.2 ± 7.6%. Using the 3D system, needles were accurately guided to the pre-determined targets with a mean error of 2.26 ± 1.03 mm and the 3D locations of the Bx cores were accurately recorded with a mean distance error of 1.47 ± 0.79 mm. &#x0D; Conclusion: We have successfully developed a 3D TRUS prostate biopsy system and validated the system in vitro. A pilot study has been initiated to apply the system clinically.

Towards intra‐operative computerized planning of prostate cryosurgery

As part of ongoing efforts to develop computerized planning tools for cryosurgery, the current study provides a comparison between two recently developed methods for planning, known as bubble packing and force-field analogy. For the purpose of comparison, four 3D prostate models were reconstructed from ultrasound imaging. The quality of planning for each method was evaluated based on bioheat transfer simulations. Both methods are shown to be robust planning tools in 3D. Typical results show at least 75% of the target region volume having temperatures below a target temperature isotherm for planning. While the force-field analogy method yields superior planning results, it comes at the expense of an order of magnitude longer run time, with only moderate improvement. Due to time constraints in a clinical setup, bubble packing alone may be considered adequate for computerized planning. Furthermore, only bubble packing is demonstrated to be adequate for intra-operative planning.

3D prostate model formation from non-parallel 2D ultrasound biopsy images

Biopsy of the prostate using 2D transrectal ultrasound (TRUS) guidance is the current gold standard for diagnosis of prostate cancer; however, the current procedure is limited by using 2D biopsy tools to target 3D biopsy locations. We propose a technique for patient-specific 3D prostate model reconstruction from a sparse collection of non-parallel 2D TRUS biopsy images. Our method conforms to the restrictions of current TRUS biopsy equipment and could be efficiently incorporated into current clinical biopsy procedures for needle guidance without the need for expensive hardware additions. In this paper, the model reconstruction technique is evaluated using simulated biopsy images from 3D TRUS prostate images of 10 biopsy patients. All reconstructed models are compared to their corresponding 3D manually segmented prostate models for evaluation of prostate volume accuracy and surface errors (both regional and global). The number of 2D TRUS biopsy images used for prostate modeling was varied to determine the optimal number of images necessary for accurate prostate surface estimation.

MR thermometry characterization of a hyperthermia ultrasound array designed using the k-space computational method

BackgroundUltrasound induced hyperthermia is a useful adjuvant to radiation therapy in the treatment of prostate cancer. A uniform thermal dose (43°C for 30 minutes) is required within the targeted cancerous volume for effective therapy. This requires specific ultrasound phased array design and appropriate thermometry method. Inhomogeneous, acoustical, three-dimensional (3D) prostate models and economical computational methods provide necessary tools to predict the appropriate shape of hyperthermia phased arrays for better focusing. This research utilizes the k-space computational method and a 3D human prostate model to design an intracavitary ultrasound probe for hyperthermia treatment of prostate cancer. Evaluation of the probe includes ex vivo and in vivo controlled hyperthermia experiments using the noninvasive magnetic resonance imaging (MRI) thermometry.MethodsA 3D acoustical prostate model was created using photographic data from the Visible Human Project®. The k-space computational method was used on this coarse grid and inhomogeneous tissue model to simulate the steady state pressure wavefield of the designed phased array using the linear acoustic wave equation. To ensure the uniformity and spread of the pressure in the length of the array, and the focusing capability in the width of the array, the equally-sized elements of the 4 × 20 elements phased array were 1 × 14 mm. A probe was constructed according to the design in simulation using lead zerconate titanate (PZT-8) ceramic and a Delrin® plastic housing. Noninvasive MRI thermometry and a switching feedback controller were used to accomplish ex vivo and in vivo hyperthermia evaluations of the probe.ResultsBoth exposimetry and k-space simulation results demonstrated acceptable agreement within 9%. With a desired temperature plateau of 43.0°C, ex vivo and in vivo controlled hyperthermia experiments showed that the MRI temperature at the steady state was 42.9 ± 0.38°C and 43.1 ± 0.80°C, respectively, for 20 minutes of heating.ConclusionUnlike conventional computational methods, the k-space method provides a powerful tool to predict pressure wavefield in large scale, 3D, inhomogeneous and coarse grid tissue models. Noninvasive MRI thermometry supports the efficacy of this probe and the feedback controller in an in vivo hyperthermia treatment of canine prostate.

Evaluation of a prostate biopsy strategy for cancer detection using a computer simulation system with virtual needle biopsy for three‐dimensional prostate models

We evaluated a prostate biopsy strategy for cancer detection using a computer simulation system with virtual needle biopsy for three-dimensional (3D) prostate models. Two 3D prostate models with a volume of 25 cc or 50 cc were constructed from computed tomographic images of radical prostatectomy specimens. The peripheral zone (PZ) and transition zone (TZ) were arranged in the prostate models according to the anatomical information. Four thousand patterns of cancer lesions were automatically inserted into each prostate model with a proportion of 75% in PZ and 25% in TZ. Average hit rates (AHR) in prostate models were evaluated both with an increased number of biopsy cores and various angles of virtual needle biopsy. The influence of adding secondary tumors for hit rates was also evaluated. For both sizes, the laterally angled biopsy in 4-8 core biopsy schemes showed higher AHR than the vertical plane biopsy, while the vertical plane biopsy in 10-18 core biopsy schemes showed higher AHR than the laterally angled biopsy. A higher number of biopsy cores increased the AHR of secondary tumors. Our results suggest that it is important in prostate cancer detection to change the needle placement according to the number of biopsy cores and the size of the prostate.

Utilization of the k -Space Method in the Design of a Ferroelectric Hyperthermia Phased Array

This research utilizes the k-space computational method and a three-dimensional (3D), inhomogeneous, large scale, and coarse grid human prostate model to design and to fabricate an intracavitary probe for hyperthermia treatment of prostate cancer. A 3D acoustical prostate model was created utilizing photographic data from the Visible Human Project®. Ultrasound wave propagation of the designed phased array was simulated by means of the k-space computational method. Four stacked linear phased arrays composed the 80 elements hyperthermia array. Good agreement between the exposimetry and the k-space simulation results was obtained. As an example, the measured −3 dB distance of the focal volume in the propagation direction deviated by only 9% compared to simulated results.

3D simulation of needle-tissue interaction with application to prostate brachytherapy

This paper presents a needle-tissue interaction model that is a 3D extension of prior work based on needle and tissue models discretized using the Finite Element Method. The use of flexible needles necessitates remeshing the tissue during insertion, since simple mesh-node snapping to the tip can be detrimental to the simulation. In this paper, node repositioning and node addition are the two methods of mesh modification examined for coarse meshes. Our focus is on numerical approaches for fast implementation of these techniques. Although the two approaches compared, namely the Woodbury formula (matrix inversion lemma) and the boundary condition switches, have the same computational complexity, the Woodbury formula is shown to perform faster due to its cache-efficient order of operations. Furthermore, node addition is applied in constant time for both approaches, whereas node repositioning requires longer and variable computational times. A method for rendering the needle forces during simulated insertions into a 3D prostate model has been implemented. Combined with a detailed anatomical segmentation, this will be useful in teaching the practice of prostate brachytherapy. Issues related to discretization of such coupled (e.g., needle-tissue) models are also discussed.