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  • 1
    Keywords: carcinoma ; Germany ; human ; MODEL ; FOLLOW-UP ; IMAGES ; imaging ; TISSUE ; TUMORS ; TIME ; kidney ; MR ; SEQUENCE ; SEQUENCES ; treatment ; MAGNETIC-RESONANCE ; magnetic resonance imaging ; LESIONS ; RESECTION ; RENAL-CELL CARCINOMA ; renal cell carcinoma ; PHASE ; SIZE ; human renal cell carcinoma ; EXTENT ; PORCINE MODEL ; viability ; CLINICAL-EXPERIENCE ; RADIO-FREQUENCY ABLATION ; THERMAL ABLATION
    Abstract: Background and Purpose: Radiofrequency ablation (RFA) is an attractive minimally invasive treatment option for small renal masses. The purpose of this study was to investigate the morphologic imaging appearance of RF lesions immediately after the ablation of kidney tissue using standard clinical MR sequences, as well as to investigate the correlation between MR and gross lesion size. Materials and Methods: Ablations were performed 17 times in a standardized model of ex-vivo perfused porcine kidneys using a resistance-controlled RF device (250 W, 470 kHz) and a nonexpandable bipolar applicator inserted into the center of healthy renal parenchyma. The RF current was applied for 9 minutes at 20 W. Imaging was performed after ablation using standard clinical MR sequences: morphologic T-1/T(2-)weighted images and an isotropic post-contrast T-1 high-resolution measurement (VIBE). Maximum lesion diameters were measured in three directions and were compared with the measurements of the gross lesions. Histologic (hematoxylin + eosin and nicotinamide adenine dinucleotide staining) and statistical analyses were performed. Results: The gross pathologic examination showed a firm, white-yellow ablation zone sharply demarcated from the untreated tissue. The histologic examination confirmed cellular viability outside but not in the treatment zone. The RF lesions were hyperintense on T-1-weighted images and hypointense on T-2-weighted images. The lesion size measured in the VIBE images correlated best with the macroscopic lesion size (N = 16). Conclusions: Morphologic MR T-1 and T-2 sequences of RF lesions immediately after ablation produce reliable and consistent imaging characteristics. The post-contrast, high-resolution sequence (VIBE) enables the extent of the lesion to be determined accurately. The potential uses of this imaging strategy in clinical practise warrant further investigation on human renal-cell carcinoma
    Type of Publication: Journal article published
    PubMed ID: 16724901
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  • 2
    Keywords: IN-VITRO ; Germany ; IN-VIVO ; imaging ; SYSTEM ; SYSTEMS ; SURGERY ; kidney ; EXPERIENCE ; TRACKING ; CHOLECYSTECTOMY ; ultrasound ; INVITRO ; review ; USA ; navigation ; AUGMENTED-REALITY ; MINIMALLY INVASIVE SURGERY ; PARTIAL NEPHRECTOMY ; ENDOSURGERY ; LAPAROSCOPIC RADICAL PROSTATECTOMY ; soft tissue navigation
    Abstract: Background and Purpose: One of the next frontiers of minimally invasive surgery is natural orifice translumenal endoscopic surgery (NOTES). This article focuses on the perspectives and limitations of imaging and navigation in NOTES soft-tissue surgery. Materials and Methods: Based on our in-vitro and in-vivo studies, with the applicability of different systems for image-guided soft-tissue endoscopic surgery, early experience with NOTES, and long-term experience with advanced endoluminal, laparoscopic robot-assisted endoscopic surgery, we performed a review of the literature. The aim was a critical analysis of the current role of imaging during NOTES. Results: There are several steps/problems with NOTES that might be significantly alleviated by use of imaging and soft-tissue navigation. One has to distinguish between preoperative planning and intraoperative imaging or navigation. NOTES represents a hybrid technique of laparoscopy and endoscopy with similar limitations in perception and two-dimensional imaging; however, the use of flexible instruments increases the complexity with respect to the spatial orientation. This applies not only for the surgeon, but also for tracking devices for surgical navigation systems. Unlike optical navigation systems, electromagnetic and endoscopic (inside-out) tracking devices might be best suited to NOTES. Conclusion: The safe realization and standardization of NOTES represents a real challenge that necessitates close and effective interdisciplinary collaboration of surgeon, technicians, informatics, and endoscopic and applied industries. Image-guided soft-tissue navigation may be very helpful to minimize the hazards of the technically challenging procedure
    Type of Publication: Journal article published
    PubMed ID: 19397427
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  • 3
    Keywords: CANCER ; TIME ; MRI ; EXPERIENCE ; ultrasound ; GUIDANCE ; GUIDED BIOPSY
    Abstract: Abstract Purpose: To determine the targeting error of a novel stereotactic prostate biopsy system that integrates preinterventional MRI with peri-interventional ultrasonography (US) for perineal navigated prostate biopsies. Materials and Methods: We performed stereotactic biopsies on five prostate phantoms (one CIRS 053-MM and four CIRS 066). Phantom 053-MM incorporates three MRI- and transrectal ultrasonography (TRUS)-visible lesions, while lesions within phantom 066 are only detectable on MRI. In both phantoms, the 0.5 cc volume lesions are placed randomly. The phantoms were examined by 3T-MRI preinterventionally. Then three stereotactic biopsies from one lesion in phantom 053-MM and from all US-invisible lesions in the 066 phantoms were taken under live-fusion imaging guidance. During intervention, a mix of blue ink and gadobutrol was injected into each biopsy channel. Afterward, another 3T-MRI was obtained. These MRI images were then fused again with the intraoperative TRUS data. Thus, the targeting error (TE) between the planned and performed biopsy cores could be measured. In addition, the procedural targeting error (PTE) between the virtually planned biopsy trajectory and the manually registered three-dimensional needle position of every single biopsy core taken was calculated. Results: The overall TE of the 39 biopsy cores taken was 0.83 mm (standard deviation [SD]: 0.48 mm) with the highest TE in the sagittal plane (1.09+/-0.54 mm), followed by the coronal (0.72+/-0.43 mm) and axial (0.69+/-0.34 mm) planes. The procedural TE, which is provided intraoperatively, was 0.26 mm on average (SD: 0.46 mm). Comparing PTE and TE, there was no statistically significant difference (P=0.39). Conclusion: The TE of stereotactic biopsies using our novel perineal prostate biopsy system is below 1 mm and can be estimated in vivo by the automatically calculated procedural TE. Thus, stereotactic prostate biopsies guided by the combination of MRI and US allow effective and precise examination of MRI lesions.
    Type of Publication: Journal article published
    PubMed ID: 22283184
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    Keywords: CANCER ; SYSTEM ; ACCURACY ; MRI ; GUIDANCE ; TRANSRECTAL ULTRASOUND ; TRUS ; FUSION BIOPSY
    Abstract: Objective: To show the benefit of trocar-sharpened needles for image-guided prostate biopsy compared with standard bevelled needles in patients. Materials and Methods: Twenty-four men underwent magnetic resonance imaging-targeted fusion-guided transperineal saturation prostate biopsy, each with half standard bevelled and half trocar-sharpened needles. All taken biopsies were scored (1=worse to 5=best) by one urologist for the following criteria. (1) Accuracy of matching between planned and performed biopsy. (2) Histologic quality of the sample. (3) Elegance, which is the easiness to take the biopsy in proper time, planned position, and best histologic quality. Afterward, the histologic sample quality was evaluated by a blinded pathologist. To show a possible training effect, blinded untrained junior residents performed biopsies in four men (103 cores). Results: Overall, 600 single biopsies were analyzed. The trocar-sharpened needles demonstrated a significantly (p〈0.05) better scoring for accuracy and elegance rated by the urologist. The histologic quality scored by the pathologist was superior. Moreover, significantly lower target errors with trocar-sharpened needles were achieved by untrained residents, but not by the experienced user. Conclusion: Using trocar-sharpened needles helps urologists to perform targeted prostate biopsy more elegantly and accurately. In addition, the histopathologic sample quality was superior, which may directly improve diagnostic certainty. There is an undeniable training effect in image-guided biopsy and unexperienced users can significantly reduce target errors with trocar-sharpened needles.
    Type of Publication: Journal article published
    PubMed ID: 24935738
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  • 6
    Abstract: PURPOSE: To investigate the value of multiparametric magnetic resonance imaging (mpMRI) and to predict extracapsular extension (ECE), seminal vesicle (SV) infiltration, and a negative surgical margin (SM) status at radical prostatectomy (RP) for different prostate cancer (PC) risk groups. PATIENTS AND METHODS: In the study, 805 men underwent 3 tesla mpMRI without endorectal coil before MRI/transrectal ultrasonography-fusion guided prostate biopsy. MRIs were analyzed using the prostate imaging reporting and data system. The cohort was classified into risk groups according to National Comprehensive Cancer Network (NCCN) criteria. Of 132 men who subsequently underwent RP, pathologic stage and SM status at RP were used as reference. Retrospectively, we investigated a European Society of Urogenital Radiology (ESUR) score for ECE and SV-infiltration. Statistical analyses included regression analyses, receiver operating characteristics (ROC), and Youden Index to assess an ESUR-score cutoff. RESULTS: Area under the curve in ROC curve analyses was 0.82 for ESUR-ECE score to detect pT3a-disease and 0.77 for ESUR-SV score for pT3b. Using a cutoff of 4 for ECE and of 2 for SV, the positive predictive value of the ECE-score for harboring pT3 was 50.0%, 90.0%, and 88.8% for the low-, intermediate- and high-risk cohort. Retrospectively, the use of the ESUR-ECE score preoperatively would have changed the initial surgical plan, according to NCCN criteria, in 31.1% of patients. In the high-risk subgroup, 9/35 (25.7%) patients were correctly assessed as not harboring pT3 by imaging (ECE score 〈4), and would have allowed secure robot-assisted radical prostatectomy and nerve-sparing surgery (NSS). When T3 suspicion on preoperative MRI would be taken into account, intraoperative frozen-sections (IFS) might avoid positive SM in 12/18 high-risk patients and an oncologic secure NSS in 8/20 intermediate-risk patients. CONCLUSION: Prediction of pT3 disease is crucial to plan NSS and to achieve negative SM in RP. Standardized ECE scoring on mpMRI is an independent predictor of pT3 and may help to plan RP with oncologic security, even in high-risk patients. In addition, it allows more accurate selection of a subgroup of patients for systematic and MRI-guided IFS.
    Type of Publication: Journal article published
    PubMed ID: 26154571
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  • 7
    Keywords: IN-VITRO ; Germany ; IN-VIVO ; MODEL ; VITRO ; VIVO ; VOLUME ; EXPOSURE ; TISSUE ; TIME ; kidney ; animals ; LESIONS ; PARAMETERS ; pathology ; ultrasonic therapy ; ultrasound ; EX-VIVO ; ABLATION ; SWITZERLAND ; methods ; in vivo ; DINUCLEOTIDE ; Swine ; Transducers
    Abstract: PURPOSE: To investigate strategies to achieve confluent kidney-tissue ablation by high-intensity focused ultrasound (HIFU). MATERIALS AND METHODS: Our model of the perfused ex-vivo porcine kidney was used. Tissue ablation was performed with an experimental HIFU device (Storz Medical, Kreuzlingen, Switzerland). Lesion-to-lesion interaction was investigated by varying the lesion distance (5 to 2.5 mm), generator power (300, 280, and 260 W), cooling time (10, 20, and 30 seconds), and exposure time (4, 3, and 2 seconds). The lesion rows were analyzed grossly and by histologic examination (hematoxylin-eosin and nicotinamide adenine dinucleotide staining). RESULTS: It was possible to achieve complete homogeneous ablation of a clinically relevant tissue volume but only by meticulous adjustment of the exposure parameters. Minimal changes in these parameters caused changes in lesion formation with holes within the lesions and lesion-to-lesion interaction. CONCLUSIONS: Our preliminary results show that when using this new device, HIFU can ablate a large tissue volume homogeneously in perfused ex-vivo porcine tissue under standardized conditions with meticulous adjustment of exposure parameters. Further investigations in vivo are necessary to test whether large tissue volumes can be ablated completely and reliably despite the influence of physiologic tissue and organ movement
    Type of Publication: Journal article published
    PubMed ID: 17144867
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  • 8
    Keywords: MODEL ; PROSTATE ; IMAGES ; TRIALS ; REGISTRATION ; HEAD ; GUIDANCE ; navigation ; REAL ; TRANSRECTAL ULTRASOUND GUIDANCE
    Abstract: PURPOSE: We present an augmented reality (AR) navigation system that conveys virtual organ models generated from transrectal ultrasonography (TRUS) onto a real laparoscopic video during radical prostatectomy. By providing this additional information about the actual anatomy, we can support surgeons in their working decisions. This work reports the system's first in-vivo application. MATERIALS AND METHODS: The system uses custom-developed needles with colored heads that are inserted into the prostate as soon as the organ surface is uncovered. These navigation aids are once segmented in three-dimensional (3D) TRUS data that is acquired right after the placement of the needles and then continuously tracked in the laparoscopic video images by the surgical navigation system. The navigation system traces the navigation aids in real time and computes a registration between TRUS image and laparoscopic video based on the two-dimensional-three dimensional (2D-3D) point correspondences. With this registration, the system correctly superimposes TRUS-based 3D information on an additional AR monitor placed next to the normal laparoscopic screen. Surgical navigation guidance took place until the prostate was removed from the rectal wall. Finally, the navigation aids were removed together with the specimen inside the specimen bag. RESULTS: The initial human in-vivo application of the surgical navigation system was successful. No complications occurred, the prostate was removed together with the navigation aids, and the system supported the surgeons as intended with an AR visualization in real time. In case of tissue deformations, changes in the spatial configuration of the navigation aids are detected, which preserves the system from erroneous navigation visualization. CONCLUSIONS: Feasibility of the navigation system was shown in the first in-vivo application. TRUS information could be superimposed via AR in real time. To show the benefit for the patient, results obtained from a larger number of trials are needed.
    Type of Publication: Journal article published
    PubMed ID: 21970336
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  • 9
    Abstract: INTRODUCTION: Laparoscopic partial nephrectomy (LPN) remains challenging in endophytic and complex kidney tumors as the clear understanding of tumor location and spreading depends on a precise analysis of available imaging. The purpose of this study was to investigate navigated kidney surgery using intraoperative cone beam computed tomography (CBCT) images in conjunction with a previously proposed method for augmented reality (AR) guidance for safe LPN. MATERIALS AND METHODS: The concept proposed is based on using an intra-operative CBCT scan for (1) marker-based AR guidance for fast and reliable tumor access and (2) enhancement of real-time fluoroscopy images for accurate tumor resection. Workflow and accuracy of the system were assessed using a porcine kidney model. Ten patients with complex or endophytic tumor localization and R.E.N.A.L.-Nephrometry score of at least nine scheduled for LPN were included in this study. Patients received an intraoperative CBCT after marker placement. Defining the resection line was assisted by AR. Additionally, fluoroscopy imaging for depth perception was used for assistance during dissection. Feasibility and performance were assessed by histopathological results, peri- and postoperative data. RESULTS: Surgery was performed successfully and negative margins were found in all cases. Segmental branches of the renal artery shifted up to 10mm in the vertical and 11mm in the sagittal axis intraoperatively compared to preoperative imaging. Fluoroscopy to intraoperative CT image fusion enabled enhanced depth perception during dissection in all cases. Radiation dose area product was 4.8 mGym(2). CONCLUSIONS: The application of the navigation system is feasible and allows for safe and direct access to complex or endophytic renal masses. Radiation limits the application to selected indications.
    Type of Publication: Journal article published
    PubMed ID: 27530774
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