Study protocol for a multicenter randomised controlled trial on the (cost)effectiveness of biopsy combined with same-session MR-guided LITT versus biopsy alone in patients with primary irresectable glioblastoma (EMITT trial).

BACKGROUND: Glioblastoma (GBM) is the most common primary, malignant brain tumour with a 5-year survival of 5%. If possible, a glioblastoma is resected and further treated with chemoradiation therapy (CRT), but resection is not feasible in about 30% of cases. Current standard of care in these cases is a biopsy followed by CRT. Magnetic resonance (MR) imaging-guided laser interstitial thermal therapy (LITT) has been suggested as a minimally invasive alternative when surgery is not feasible. However, high-quality evidence directly comparing LITT with standard of care is lacking, precluding any conclusions on (cost-)effectiveness. We therefore propose a multicenter randomized controlled study to assess the (cost-)effectiveness of MR-guided LITT as compared to current standard of care (EMITT trial). METHODS AND ANALYSIS: The EMITT trial will be a multicenter pragmatic randomized controlled trial in the Netherlands. Seven Dutch hospitals will participate in this study. In total 238 patients will be randomized with 1:1 allocation to receive either biopsy combined with same-session MR-guided LITT therapy followed by CRT or the current standard of care being biopsy followed by CRT. The primary outcomes will be health-related quality of life (HR-QoL) (non-inferiority) using EORTC QLQ-C30 + BN20 scores at 5 months after randomization and overall survival (superiority). Secondary outcomes comprise cost-effectiveness (healthcare and societal perspective) and HR-QoL of life over an 18-month time horizon, progression free survival, tumour response, disease specific survival, longitudinal effects, effects on adjuvant treatment, ablation percentage and complication rates. DISCUSSION: The EMITT trial will be the first RCT on the effectiveness of LITT in patients with glioblastoma as compared with current standard of care. Together with the Dutch Brain Tumour Patient association, we hypothesize that LITT may improve overall survival without substantially affecting patients' quality of life. TRIAL REGISTRATION: This trial is registered at ClinicalTrials.gov (NCT05318612).

MR-guided LITT therapy in patients with primary irresectable glioblastoma: a prospective, controlled pilot study.

PURPOSE: Laser interstitial thermal therapy (LITT) is increasingly being used in the treatment of brain tumors, whereas high-quality evidence of its effectiveness is lacking. This pilot examined the feasibility of conducting a randomized controlled trial (RCT) in patients with irresectable newly diagnosed glioblastoma (nGBM), and generated data on technical feasibility and safety. METHODS: We included patients with irresectable nGBM with KPS ≥ 70 and feasible trajectories to ablate ≥ 70% of the tumor volume. Patients were initially randomized to receive either biopsy combined with LITT or biopsy alone, followed by chemoradiation (CRT). Randomization was stopped after 9 patients as the feasibility endpoint with respect to willingness to be randomized was met. Main endpoints were feasibility of performing an RCT, technical feasibility of LITT and safety. Follow-up was 3 months. RESULTS: A total of 15 patients were included, of which 10 patients received a biopsy followed by LITT and 5 patients a biopsy. Most patients were able to complete the follow-up procedures (93% clinical, 86% questionnaires, 78% MRI). Patients were planned within 3 weeks after consultation (median 12 days, range 8-16) and no delay was observed in referring patients for CRT (median 37 days, range 28-61). Two CD ≥ 3 complications occurred in the LITT arm and none in the biopsy arm. CONCLUSION: An RCT to study the effectiveness of LITT in patients with an irresectable nGBM seems feasible with acceptable initial safety data. The findings from this pilot study helped to further refine the design of a larger full-scale multicenter RCT in the Netherlands. Protocol and study identifier: The current study is registered at clinicaltrials.gov (EMITT pilot study, NTR: NCT04596930).

Intraprocedural MRI-based dosimetry during transarterial radioembolization of liver tumours with holmium-166 microspheres (EMERITUS-1): a phase I trial towards adaptive, image-controlled treatment delivery.

PURPOSE: Transarterial radioembolization (TARE) is a treatment for liver tumours based on injection of radioactive microspheres in the hepatic arterial system. It is crucial to achieve a maximum tumour dose for an optimal treatment response, while minimizing healthy liver dose to prevent toxicity. There is, however, no intraprocedural feedback on the dose distribution, as nuclear imaging can only be performed after treatment. As holmium-166 (166Ho) microspheres can be quantified with MRI, we investigate the feasibility and safety of performing 166Ho TARE within an MRI scanner and explore the potential of intraprocedural MRI-based dosimetry. METHODS: Six patients were treated with 166Ho TARE in a hybrid operating room. Per injection position, a microcatheter was placed under angiography guidance, after which patients were transported to an adjacent 3-T MRI system. After MRI confirmation of unchanged catheter location, 166Ho microspheres were injected in four fractions, consisting of 10%, 30%, 30% and 30% of the planned activity, alternated with holmium-sensitive MRI acquisition to assess the microsphere distribution. After the procedures, MRI-based dose maps were calculated from each intraprocedural image series using a dedicated dosimetry software package for 166Ho TARE. RESULTS: Administration of 166Ho microspheres within the MRI scanner was feasible in 9/11 (82%) injection positions. Intraprocedural holmium-sensitive MRI allowed for tumour dosimetry in 18/19 (95%) of treated tumours. Two CTCAE grade 3-4 toxicities were observed, and no adverse events were attributed to treatment in the MRI. Towards the last fraction, 4/18 tumours exhibited signs of saturation, while in 14/18 tumours, the microsphere uptake patterns did not deviate from the linear trend. CONCLUSION: This study demonstrated feasibility and preliminary safety of a first in-human application of TARE within a clinical MRI system. Intraprocedural MRI-based dosimetry enabled dynamic insight in the microsphere distribution during TARE. This proof of concept yields unique possibilities to better understand microsphere distribution in vivo and to potentially optimize treatment efficacy through treatment personalization. REGISTRATION: Clinicaltrials.gov, identifier NCT04269499, registered on February 13, 2020 (retrospectively registered).

Current State of MRI-Guided Endovascular Arterial Interventions: A Systematic Review of Preclinical and Clinical Studies.

BACKGROUND: MRI guidance of arterial endovascular interventions could be beneficial as it does not require radiation exposure, allows intrinsic blood-tissue contrast, and enables three-dimensional and functional imaging, however, clinical applications are still limited. PURPOSE: To review the current state of MRI-guided arterial endovascular interventions and to identify the most commonly reported challenges. STUDY TYPE: Systematic review. POPULATION: Pubmed, Embase, Web of Science, and The Cochrane Library were systematically searched to find relevant articles. The search strategy combined synonyms for vascular pathology, endovascular therapy, and real-time MRI guidance. FIELD STRENGTH/SEQUENCE: No field strength or sequence restrictions were applied. ASSESSMENT: Two reviewers independently identified and reviewed the original articles and extracted relevant data. STATISTICAL TESTS: Results of the included original articles are reported. RESULTS: A total of 24,809 studies were identified for screening. Eighty-eight studies were assessed for eligibility, after which data were extracted from 43 articles (6 phantom, 33 animal, and 4 human studies). Reported technical success rates for animal and human studies ranged between 42% to 100%, and the average complication rate was 5.8% (animal studies) and 8.8% (human studies). Main identified challenges were related to spatial and temporal resolution as well as safety, design, and scarcity of current MRI-compatible endovascular devices. DATA CONCLUSION: MRI guidance of endovascular arterial interventions seems feasible, however, included articles included mostly small single-center case series. Several hurdles remain to be overcome before larger trials can be undertaken. Main areas of research should focus on adequate imaging protocols with integrated tracking of dedicated endovascular devices.

Safety aspects of the PiCCO thermodilution-cardiac output catheter during magnetic resonance imaging at 3 Tesla.

Thermodilution cardiac output monitoring, using a thermistor-tipped intravascular catheter, is used in critically ill patients to guide hemodynamic therapy. Often, these patients also need magnetic resonance imaging (MRI) for diagnostic or prognostic reasons. As thermodilution catheters contain metal, they are considered MRI-unsafe and advised to be removed prior to investigation. However, removal and replacement of the catheter carries risks of bleeding, perforation and infection. This research is an in vitro safety assessment of the PiCCO™ thermodilution catheter during 3 T Magnetic Resonance Imaging (3T-MRI).  In a 3T-MRI environment, three different PiCCO™ catheter sizes were investigated in an agarose-gel, tissue mimicking phantom. Two temperature probes measured radiofrequency-induced heating; one at the catheter tip and one at a reference point. Magnetically induced catheter dislocation was assessed by visual observation as well as by analysis of the tomographic images. For all tested catheters, the highest measured temperature increase was 0.2 °C at the center of the bore and 0.3 °C under "worst-case" setting for the tested MRI pulse sequences. No magnetically induced catheter displacements were observed. Under the tested circumstances, no heating or dislocation of the PiCCO™ catheter was observed in a tissue mimicking phantom during 3T-MRI. Leaving the catheter in the critically ill patient during MRI investigation might pose a lower risk of complications than catheter removal and replacement.

To 1000 Gy and back again: a systematic review on dose-response evaluation in selective internal radiation therapy for primary and secondary liver cancer.

PURPOSE: To systematically review all current evidence into the dose-response relation of yttrium-90 and holmium-166 selective internal radiation therapy (SIRT) in primary and secondary liver cancer. METHODS: A standardized search was performed in PubMed (MEDLINE), Embase, and the Cochrane Library in order to identify all published articles on dose-response evaluation in SIRT. In order to limit the results, all articles that investigated SIRT in combination with other therapy modalities (such as chemotherapy) were excluded. RESULTS: A total of 3038 records were identified of which 487 were screened based on the full text. Ultimately, 37 studies were included for narrative analysis. Meta-analysis could not be performed due to the large heterogeneity in study and reporting designs. Out of 37 studies, 30 reported a 'mean dose threshold' that needs to be achieved in order to expect a response. This threshold appears to be higher for hepatocellular carcinoma (HCC, 100-250 Gy) than for colorectal cancer metastases (CRC, 40-60 Gy). Reported thresholds tend to be lower for resin microspheres than when glass microspheres are used. CONCLUSION: Although the existing evidence demonstrates a dose-response relationship in SIRT for both primary liver tumours and liver metastases, many pieces of the puzzle are still missing, hampering the definition of standardized dose thresholds. Nonetheless, most current evidence points towards a target mean dose of 100-250 Gy for HCC and 40-60 Gy for CRC. The field would greatly benefit from a reporting standard and prospective studies designed to elucidate the dose-response relation in different tumour types.

Focal Salvage MR Imaging-Guided Cryoablation for Localized Prostate Cancer Recurrence after Radiotherapy: 12-Month Follow-up.

PURPOSE: To evaluate safety, quality of life (QoL), and local cancer control after focal salvage MR imaging-guided cryoablation in patients with local recurrence of prostate cancer (PCa) after radiotherapy. MATERIALS AND METHODS: A retrospective, single-center study was performed in 62 patients with radiorecurrent PCa who underwent MR imaging-guided cryoablation since May 2011 with a follow-up ≥12 months in December 2017. Rates and descriptions of adverse events were reported. Ablation complications were classified according to the Clavien and SIR systems. Validated questionnaires were used to observe functional outcomes and QoL before therapy and 6 and 12 months after therapy. Cancer control was defined as no biochemical failure according to Phoenix criteria and no other clinical evidence for local or metastatic disease. RESULTS: All procedures were technically feasible. The number of complications requiring major therapy (Clavien grade 3b/4 or SIR grade D/E/F) was low (2 [3.2%] and 1 [1.6%], respectively). After 12 months, the International Consultation of Incontinence Questionnaire-Short Form (P < .001) and 5-item International Index of Erectile Function (P = .001) scores became significantly worse, indicating increased symptoms of incontinence and diminished erectile function, without compromising QoL. Six patients developed metastases within 6 months. After 12 months, 36 patients (63%) were disease-free. CONCLUSIONS: Focal salvage MR imaging-guided cryoablation is safe and is associated with a high technical success rate, preservation of QoL, and local PCa control. This treatment can be a reasonable alternative to salvage radical prostatectomy in properly selected patients with low morbidity and preservation of QoL; however, longer follow-up is needed.

MRI evaluation of vulvar squamous-cell carcinoma in fresh radical local excision specimens for cancer localization and prediction of surgical tumor-free margins.

In the surgical treatment of vulvar squamous-cell carcinoma (VSCC), tumor-free margins of 8 mm or more are considered adequate. However, limited perioperative information on the tumor-free margins other than the surgeon's own estimation is available. The purpose of this study was therefore to investigate the feasibility of ex vivo MRI in localizing VSCC and to assess the surgical tumor-free margins in fresh radical local excision (RLE) specimens to guide the surgeon during resections. Nine patients with biopsy-proven VSCC scheduled for RLE were prospectively included. Intact fresh specimens were scanned using a 7 T preclinical MR-scanner. Whole mount H&E-stained slides were obtained every 3 mm and correlated with ex vivo MRI. A pathologist annotated VSCC and minimal tumor-free margins (3 o'clock, 9 o'clock, basal) on the digitalized histological slides. An observer with knowledge of histology (the non-blinded annotation) and a radiologist blinded to histology (the blinded annotation) separately performed annotation of the same features on ex vivo MRI. Linear correlation and agreement of the ex vivo MRI measurements with histology were assessed. Diagnostic performance for VSCC localization and identification of margins less than 8 mm was expressed as positive and negative predictive values (PPV, NPV). In 153 matched ex vivo MRI slices, the observer correctly identified 79/91 margins as less than 8 mm (PPV 87%) and 110/124 margins as 8 mm or greater (NPV 89%). The radiologist correctly annotated absence of VSCC in 73/81 (NPV 90%) and presence in 65/72 (PPV 90%) slices. Sixty-four of 90 margins were correctly identified as less than 8 mm (PPV 71%) and 83/102 margins as 8 mm or greater (NPV 81%). Both non-blinded and blinded annotations were linearly correlated and demonstrated good agreement with histology. Accurate localization of VSCC and measurements of the surgical tumor-free margins in fresh RLE specimens using ex vivo MRI seems feasible. High diagnostic performance in VSCC localization and identification of margins less than 8 mm suggest ex vivo MRI to be clinically applicable.

Multiparametric magnetic resonance imaging and follow-up to avoid prostate biopsy in 4259 men.

OBJECTIVE: To determine the proportion of men avoiding biopsy because of negative multiparametric magnetic resonance imaging (mpMRI) findings in a prostate MRI expert centre, and to assess the number of clinically significant prostate cancers (csPCa) detected during follow-up. PATIENTS AND METHODS: Retrospective study of 4259 consecutive men having mpMRI of the prostate between January 2012 and December 2017, with either a history of previous negative transrectal ultrasonography-guided biopsy or biopsy naïve. Patients underwent mpMRI in a referral centre. Lesions were classified according to Prostate Imaging Reporting And Data System (PI-RADS) versions 1 and 2. Negative mpMRI was defined as an index lesion PI-RADS ≤2. Follow-up until 13 October 2018 was collected by searching the Dutch Pathology Registry (PALGA). Gleason score ≥3 + 4 was considered csPCa. Kaplan-Meier analysis and univariable logistic regression models were used in the cohort of patients with negative mpMRI and follow-up. RESULTS: Overall, in 53.6% (2281/4259) of patients had a lesion classified as PI-RADS ≤2. In 320 patients with PI-RADS 1 or 2, follow-up mpMRI was obtained after a median (interquartile range) of 57 (41-63) months. In those patients, csPCa diagnosis-free survival (DFS) was 99.6% after 3 years. Univariable logistic regression analysis revealed age as a predictor for csPCa during follow-up (P < 0.05). In biopsied patients, csPCa was detected in 15.8% (19/120), 43.2% (228/528) and 74.5% (483/648) with PI-RADS 3, 4 and 5, respectively. CONCLUSION: More than half of patients having mpMRI of the prostate avoided biopsy. In those patients, csPCa DFS was 99.6% after 3 years.

Fast 3-T MR-guided transrectal prostate biopsy using an in-room tablet device for needle guide alignment: a feasibility study.

OBJECTIVES: To assess the feasibility of adding a tablet device inside the scanner room to assist needle-guide alignment during magnetic resonance (MR)-guided transrectal prostate biopsy. METHODS: Twenty patients with one cancer-suspicious region (CSR) with PI-RADS score ≥ 4 on diagnostic multiparametric MRI were prospectively enrolled. Two orthogonal scan planes of an MR fluoroscopy sequence (~3 images/s) were aligned to the CSR and needle-guide pivoting point. Targeting was achieved by manipulating the needle-guide under MR fluoroscopy feedback on the in-room tablet device. Technical feasibility and targeting success were assessed. Complications and biopsy procedure times were also recorded. RESULTS: Needle-guide alignment with the in-room tablet device was technically successful in all patients and allowed sampling after a single alignment step in 19/20 (95%) CSRs (median size 14 mm, range: 4-45). Biopsy cores contained cancer in 18/20 patients. There were no per-procedural or post-biopsy complications. Using the tablet device, the mean time to first biopsy was 5.8 ± 1.0 min and the mean total procedure time was 23.7 ± 4.1 min. CONCLUSIONS: Use of an in-room tablet device to assist needle-guide alignment was feasible and safe during MR-guided transrectal prostate biopsy. Initial experience indicates potential for procedure time reduction. KEY POINTS: • Performing MR-guided prostate biopsy using an in-room tablet device is feasible. • CSRs could be sampled after a single alignment step in 19/20 patients. • The mean procedure time for biopsy with the tablet device was 23.7 min.

Simultaneous slice excitation for accelerated passive marker tracking via phase-only cross correlation (POCC) in MR-guided needle interventions.

OBJECTIVE: To accelerate a passive tracking sequence based on phase-only cross correlation (POCC) using simultaneous slice excitation. METHODS: For magnetic resonance (MR)-guided biopsy procedures, passive markers have been proposed that can be automatically localized online using a POCC-based tracking sequence. To accelerate the sequence, a phase-offset multiplanar (POMP) excitation technique was implemented to acquire tracking images. In a phantom experiment, the POMP-POCC sequence was tested and compared with the sequential non-accelerated version in terms of duration and accuracy. Further, technical feasibility of the POMP-POCC sequence was tested in a patient undergoing a prostate biopsy. RESULTS: The temporal resolution of the POMP-POCC tracking sequence is accelerated by 33% compared with the sequential approach. In phantom experiments, the POMP-POCC and sequential sequences yielded the same targeting accuracy of 1.6 ± 0.7 mm. Technical proof of concept of the new sequence could be demonstrated in a successful in vivo prostate biopsy. CONCLUSION: POMP-POCC tracking can substantially reduce the duration of localization of passive markers in MR-guided needle interventions without compromising targeting accuracy.

Percutaneous MR-guided focal cryoablation for recurrent prostate cancer following radiation therapy: retrospective analysis of iceball margins and outcomes.

OBJECTIVES: To evaluate iceball margins after magnetic resonance (MR)-guided focal salvage prostate cryoablation and determine the correlation with local outcome. METHODS: A retrospective review was performed on 47 patients that underwent percutaneous MR-guided focal cryoablation for biopsy-proven locally recurrent prostate cancer after primary radiotherapy. Preprocedural diagnostic and intraprocedural MR images were analysed to derive three-directional iceball margins. Local tumour progression after cryoablation was defined as evident tumour recurrence on follow-up MRI, positive MR-guided biopsy or biochemical failure without radiological evidence of metastatic disease. RESULTS: Mean iceball margins were 8.9 mm (range -7.1 to 16.2), 10.1 mm (range 1.1-20.3) and 12.5 mm (range -1.5 to 22.2) in anteroposterior, left-right and craniocaudal direction respectively. Iceball margins were significantly smaller for tumours that were larger (P = .008) or located in the posterior gland (P = .047). Significantly improved local progression-free survival at 1 year post focal cryoablation was seen between patients with iceball margin >10 mm (100%), 5-10 mm (84%) and <5 mm (15%) (P < .001). CONCLUSIONS: Iceball margins appear to correlate with local outcome following MR-guided focal salvage prostate cryoablation. Our initial data suggest that freezing should be applied at minimum 5 mm beyond the border of an MR-visible recurrent prostate tumour for successful ablation, with a wider margin appearing desirable. KEY POINTS: • Shortest iceball margin most often occurred in anteroposterior direction • Margins were smaller in tumours that were larger or posteriorly located • Minimum iceball margin was a predictor of early local tumour progression • A minimum 5-mm margin seems required for effective cryoablation of recurrent PCa.

Percutaneous MR Imaging-Guided Cryoablation of Small Renal Masses in a 3-T Closed-Bore MR Imaging Environment: Initial Experience.

PURPOSE: To assess the feasibility of percutaneous magnetic resonance (MR) imaging-guided cryoablation of small renal masses (SRMs) in a 3-T environment and to evaluate intraprocedural imaging, procedural safety, and initial outcomes. MATERIALS AND METHODS: The analysis included 9 patients (4 men; median age, 72 y; range, 70-82 y) with 9 SRMs (diameter, 12-30 mm). Lesions underwent biopsy, and cryoneedles were inserted under ultrasound guidance. Verification of needle positions and ice-ball monitoring were performed by T1-weighted volumetric interpolated breath-hold examination and T2-weighted half-Fourier acquired single-shot turbo spin-echo sequences. On image analysis, needle positioning was considered appropriate if the target lesion border was visible, the needle tip was inside the target lesion, and the ice ball was expected to cover the target lesion with a 5-mm margin. If these criteria could not be assessed, imaging was considered inadequate. Technical success was defined as tumor coverage with a 5-mm margin and no residual disease on 1-mo follow-up MR imaging. RESULTS: Median total procedure time was 170 min (range, 135-193 min). Intraoperative imaging allowed adequate needle visualization in 67% of acquired scans (4 of 7 T1-weighted and 6 of 8 T2-weighted). Appropriate positioning of two or three needles used for each procedure was confirmed in all cases on T1- or T2-weighted imaging. Ice-ball formation was adequately visualized in all patients. Technical success rate was 100%. No local recurrences were detected on follow-up imaging at a median of 12 mo (range, 3-22 mo). CONCLUSIONS: Percutaneous MR-guided cryoablation of SRMs in a 3-T MR imaging environment is safe and feasible, showing adequate intraoperative imaging capabilities with promising short-term clinical outcomes.

3D MR thermometry of frozen tissue: Feasibility and accuracy during cryoablation at 3T.

PURPOSE: To assess the feasibility and accuracy of 3D ultrashort echo time (UTE) magnetic resonance (MR) thermometry of frozen tissue during cryoablation on a clinical 3T MR system. MATERIALS AND METHODS: Ex vivo porcine muscle specimens (n = 4) were imaged during two cycles of 10:3 minutes freeze-thaw on a 3T clinical MR scanner. Continuous MR monitoring was performed using a 3D radial ramp-sampled UTE sequence with a shortest TE of 70 µs. Fiber optic sensors were used for temperature reference. Data of three experiments were used as reference sets. Signal intensity values were normalized to baseline before cooling and related to temperature. Data for subzero temperatures were fit to a monoexponential function. In the separate validation set, the obtained fit was used to generate 3D MR temperature maps of frozen tissue at each imaging timepoint. Statistical analysis was performed to assess accuracy of the MR temperature maps. RESULTS: With 3D UTE imaging, MR signal was measured from frozen tissue down to temperatures as low as -40°C. Temperatures predicted from the MR temperature maps strongly correlated with sensor recorded values (r = 0.977, P < 0.001). Bland-Altman analysis demonstrated a mean difference between MR-estimated temperatures and sensor readings of -1.2 ± 2.7°C with upper and lower limits of agreement of +4.1 and -6.5°C, respectively. CONCLUSION: 3D MR thermometry of frozen tissue using UTE signal intensity was feasible during cryoablation on a clinical 3T MR system. Down to temperatures as low as -40°C, accuracy of the MR temperature maps was within clinically acceptable limits. J. Magn. Reson. Imaging 2016;44:1572-1579.

Phantom and in vivo accuracy of frameless optical navigation in stereotactic laser interstitial thermal therapy.

OBJECTIVE: Targeting accuracy presents a key factor in achieving maximal safe ablation in laser interstitial thermal therapy (LITT). The VarioGuide system has proven precise for brain biopsies, but data showing its accuracy in combination with LITT are limited. The aim of this study was to determine the phantom and in vivo accuracy of LITT probe placement using the VarioGuide system and to evaluate the effect of targeting error on maximum possible ablation volume. METHODS: Stereotactic LITT probe placement was performed using the VarioGuide system in 3 phantom skulls. The same system was used in 10 patients treated with LITT, for which data were retrospectively analyzed. Target point error (TPE), target depth deviation (TDD), target lateral deviation (TLD), and angular deviation (AD) were derived from intraprocedural MRI scans of both the phantom and in vivo trajectories. In vivo, the effect of targeting error on the maximum reachable ablation was calculated as the difference between the planned maximal achievable tumor ablation (PTA) and the actual maximal achievable tumor ablation (ATA). RESULTS: In total, 24 phantom and 16 in vivo trajectories were analyzed. In the phantom setting, the median TPE was 3.3 mm and median AD was 1.9°. Targeting accuracy significantly decreased for longer trajectories and those less perpendicular to the skull. In patients, the authors observed a comparable median TPE of 4.0 mm but significantly higher AD of 3.2°. In vivo, targeting inaccuracy resulted in a median decrease in maximum achievable ablation volume of 6% as compared to the planned trajectory. CONCLUSIONS: The authors' study indicates that utilizing the VarioGuide system in combination with LITT yields an average targeting error as large as 4 mm, which was smaller for shorter and straighter trajectories. In patients, targeting inaccuracy resulted in a median 6% decrease of the planned tumor ablation volume. These are important factors that should be considered in optimal case planning and patient selection in LITT.

MR imaging-guided focal cryoablation in patients with recurrent prostate cancer.

PURPOSE: To assess the feasibility of magnetic resonance (MR) imaging-guided focal cryoablation in patients with locally recurrent prostate cancer after radiation therapy. MATERIALS AND METHODS: This was a prospective study, and informed consent was obtained from all patients. Ten consecutive patients with histopathologically proved recurrent prostate cancer after radiation therapy, without evidence of distant metastases, were treated while under general anesthesia in a 1.5-T MR unit. A urethral warmer was inserted. Cryoneedles were transperineally inserted under real-time MR imaging. Then, a rectal warmer was inserted. Ice ball growth was continuously monitored under MR imaging guidance. Two freeze-thaw cycles were performed. Follow-up consisted of a visit to the urologist, measurement of prostate-specific antigen level, and multiparametric MR imaging at 3, 6, and 12 months. Potential complications were recorded. RESULTS: All patients were successfully treated. In one patient, the urethral warmer could not be inserted and the procedure was cancelled. Two months later, the procedure was successfully repeated. Another patient had urinary retention. Follow-up data were available for all patients. A local recurrence or remnant tumor was found in two patients after 6 months and in another patient after 12 months. These three patients underwent successful retreatment with MR imaging-guided focal cryoablation. CONCLUSION: MR imaging-guided focal cryoablation of recurrent prostate cancer after radiation therapy is feasible and safe. Initial results are promising; however, longer follow-up is needed and more patients must be studied.

MRI-guided biopsy for prostate cancer detection: a systematic review of current clinical results.

In-bore magnetic resonance-guided biopsy (MRGB) has been increasingly used in clinical practice to detect prostate cancer (PCa). This review summarizes the current clinical results of this biopsy method. A systematic literature search was performed in the PubMed and Embase databases. Of 2,035 identified records, 49 required full review. In all, ten unique studies reporting clinical results of MRGB could be included. Reported PCa detection rates ranged from 8 to 59 % (median 42 %). The majority of tumors detected by MRGB were clinically significant (81-93 %). Most frequent complications of MRGB are transient hematuria (1-24 %) and short-term perirectal bleeding (11-17 %). Major complications are rare. Based on the reviewed literature, MRGB can be regarded an accurate and safe diagnostic tool to detect clinically significant PCa. However, as general availability is limited, this procedure should be reserved for specific patients. Appropriate indications will have to be determined.

Stereotactic laser ablation in neuro-oncology - A survey among European neurosurgeons.

Introduction: In the last decades, the application of stereotactic laser ablation (SLA) for the treatment of intracranial tumours has been growing, even though comparative trials are lacking. Our aim was to investigate the familiarity with SLA of neurosurgeons in Europe and their opinion regarding potential neuro-oncological indications. Furthermore, we investigated treatment preferences and variability for three exemplar neuro-oncological cases and willingness to refer for SLA. Material and methods: A 26-questions survey was mailed to members of the EANS neuro-oncology section. We presented three clinical cases of respectively deep-seated glioblastoma, recurrent metastasis and recurrent glioblastoma. Descriptive statistics was applied to report results. Results: 110 respondents completed all questions. Recurrent glioblastoma and recurrent metastases were regarded as the most feasible indications for SLA (chosen by 69% and 58% of the respondents) followed by newly diagnosed high-grade gliomas (31%). Seventy percent of respondents would refer patients for SLA. The majority of respondents would consider SLA as a treatment option for all three presented cases: 79% for the deep-seated glioblastoma case, 65% for the recurrent metastasis case and 76% for the recurrent glioblastoma case. Among respondents who wouldn't consider SLA, preference for standard treatment and lack of clinical evidence were reported as the main reasons. Conclusions: Most of respondents considered SLA as a treatment option for recurrent glioblastoma, recurrent metastases and newly diagnosed deep-seated glioblastoma. At the moment the current evidence to support such a treatment is very low. Comparative prospective trials are needed to support the use of SLA and determine proper indications.

MRI-Guided Salvage Focal Cryoablation: A 10-Year Single-Center Experience in 114 Patients with Localized Recurrent Prostate Cancer.

Patients with localized recurrent prostate cancer (PCa) are eligible for androgen-deprivation therapy, salvage radical prostatectomy (RP) or radiation therapy. These treatments are associated with serious side-effects, illustrating the need for alternative local treatment options with lower morbidity rates. All patients who underwent magnetic resonance imaging (MRI)-guided salvage focal cryoablation (SFC) with localized recurrent PCa between 2011-2021 (n = 114) were included. Two subgroups were formed: patients without (n = 99) and with prior RP (n = 15). We assessed the recurrence- (RFS) and treatment-free survival (TFS), measured from date of treatment to date of recurrence or initiation of additional salvage treatment, using Kaplan-Meier plots. Complications were reported using the Clavien-Dindo (CD) scale. Overall 1-year and 5-year RFS were 76.0% and 25.1%, and overall 1-year and 5-year TFS were 91.5% and 58.2%, respectively. Patients without prior RP showed a significantly higher 1-year (78.5% vs. 52.5%) and 5-year RFS (28.1% vs. 0.0%; p = 0.03), and a trend towards a higher 1-year (92.6% vs. 79.0%) and 5-year TFS (60.2% vs. 23.0%; p = 0.10) compared to those with prior RP. A total of 46 complications occurred in 37 patients, and the overall complication rate was 32.4% (37/114 patients). The majority (41/46; 89.1%) of complications were minor (CD 1-2). Overall (31.3 vs. 40.0%) and major (3.0 vs. 13.3%) complication rates were lower in patients without compared to those with prior RP, respectively. MRI-guided SFC is an effective and safe therapy for patients with recurrent PCa, and has proved to delay and potentially prevent the initiation of salvage treatments. Patients with locally recurrent PCa after prior RP had an increased risk of recurrence, a shortened time to additional treatment, and more complications compared to those without prior RP, which should be considered when selecting patients for SFC.

Intraoperative MRI-derived volumetric ablation margins and initial correlation with local outcome after MRI-guided cryoablation of renal tumors.

PURPOSE: To assess volumetric ablation margins derived from intraoperative pre- and post-ablation MRI after magnetic resonance imaging (MRI)-guided percutaneous cryoablation of renal tumors and explore its correlation with local treatment success. METHODS: Retrospective analysis was performed on 30 patients (mean age 69y) who underwent percutaneous MRI-guided cryoablation between May 2014 and May 2020 for 32 renal tumors (size: 1.6-5.1 cm). Tumor and ice-ball volumes were segmented on intraprocedural pre- and post-ablation MR images using Software Assistant for Interventional Radiology (SAFIR) software. After MRI-MRI co-registration, the software automatically quantified the minimal treatment margin (MTM),defined as the smallest 3D distance between the tumor and ice-ball surface. Local tumor progression (LTP) after cryoablation was assessed on follow-up imaging. RESULTS: Median follow-up was 16 months (range: 1-58). Local control after cryoablation was achieved in 26 cases (81%) while LTP occurred in 6 (19%). The intended MTM of ≥5 mm was achieved in 3/32 (9%) cases. Median MTM was significantly smaller for cases with (- 7 mm; IQR:-10 to - 5) vs. without LTP (3 mm; IQR:2 to 4) (P < .001). All cases of LTP had a negative MTM. All negative treatment margins occurred in tumors > 3 cm. CONCLUSIONS: Determination of volumetric ablation margins from intraoperative MRI was feasible and may be useful in predicting local outcome after MRI-guided renal cryoablation. In our preliminary data, an intraoperative MRI-derived minimal margin extending at least 1 mm beyond the MRI-visible tumor led to local control and this was more difficult to achieve in tumors > 3 cm. Ultimately, online margin analysis may be a valuable tool to intraoperatively assess therapy success, but larger prospective studies are needed to establish a reliable threshold for clinical use.