Magnetic resonance linear accelerator technology and adaptive radiation therapy: An overview for clinicians.

Radiation therapy (RT) continues to play an important role in the treatment of cancer. Adaptive RT (ART) is a novel method through which RT treatments are evolving. With the ART approach, computed tomography or magnetic resonance (MR) images are obtained as part of the treatment delivery process. This enables the adaptation of the irradiated volume to account for changes in organ and/or tumor position, movement, size, or shape that may occur over the course of treatment. The advantages and challenges of ART maybe somewhat abstract to oncologists and clinicians outside of the specialty of radiation oncology. ART is positioned to affect many different types of cancer. There is a wide spectrum of hypothesized benefits, from small toxicity improvements to meaningful gains in overall survival. The use and application of this novel technology should be understood by the oncologic community at large, such that it can be appropriately contextualized within the landscape of cancer therapies. Likewise, the need to test these advances is pressing. MR-guided ART (MRgART) is an emerging, extended modality of ART that expands upon and further advances the capabilities of ART. MRgART presents unique opportunities to iteratively improve adaptive image guidance. However, although the MRgART adaptive process advances ART to previously unattained levels, it can be more expensive, time-consuming, and complex. In this review, the authors present an overview for clinicians describing the process of ART and specifically MRgART.

Comparison of Positive Predictive Values of Biparametric MRI and Multiparametric MRI-directed Transrectal US-guided Targeted Prostate Biopsy.

Background Biparametric MRI (bpMRI) of the prostate is an alternative to multiparametric MRI (mpMRI), with lower cost and increased accessibility. Studies investigating the positive predictive value (PPV) of bpMRI-directed compared with mpMRI-directed targeted biopsy are lacking in the literature. Purpose To compare the PPVs of bpMRI-directed and mpMRI-directed targeted prostate biopsies. Materials and Methods This retrospective cross-sectional study evaluated men who underwent bpMRI-directed or mpMRI-directed transrectal US (TRUS)-guided targeted prostate biopsy at a single institution from January 2015 to December 2022. The PPVs for any prostate cancer (PCa) and clinically significant PCa (International Society of Urological Pathology grade ≥2) were calculated for bpMRI and mpMRI using mixed-effects logistic regression modeling. Results A total of 1538 patients (mean age, 67 years ± 8 [SD]) with 1860 lesions underwent bpMRI-directed (55%, 849 of 1538) or mpMRI-directed (45%, 689 of 1538) prostate biopsy. When adjusted for the number of lesions and Prostate Imaging Reporting and Data System (PI-RADS) score, there was no difference in PPVs for any PCa or clinically significant PCa (P = .61 and .97, respectively) with bpMRI-directed (55% [95% CI: 51, 59] and 34% [95% CI: 30, 38], respectively) or mpMRI-directed (56% [95% CI: 52, 61] and 34% [95% CI: 30, 39], respectively) TRUS-guided targeted biopsy. PPVs for any PCa and clinically significant PCa stratified according to clinical indication were as follows: biopsy-naive men, 64% (95% CI: 59, 69) and 43% (95% CI: 39, 48) for bpMRI, 67% (95% CI: 59, 75) and 51% (95% CI: 43, 59) for mpMRI (P = .65 and .26, respectively); and active surveillance, 59% (95% CI: 49, 69) and 30% (95% CI: 22, 39) for bpMRI, 73% (95% CI: 65, 89) and 38% (95% CI: 31, 47) for mpMRI (P = .04 and .23, respectively). Conclusion There was no evidence of a difference in PPV for clinically significant PCa between bpMRI- and mpMRI-directed TRUS-guided targeted biopsy. © RSNA, 2024 Supplemental material is available for this article.

Interventional device tracking under MRI via alternating current controlled inhomogeneities.

PURPOSE: To introduce alternating current-controlled, conductive ink-printed marker that could be implemented with both custom and commercial interventional devices for device tracking under MRI using gradient echo, balanced SSFP, and turbo spin-echo sequences. METHODS: Tracking markers were designed as solenoid coils and printed on heat shrink tubes using conductive ink. These markers were then placed on three MR-compatible test samples that are typically challenging to visualize during MRI scans. MRI visibility of markers was tested by applying alternating and direct current to the markers, and the effects of applied current parameters (amplitude, frequency) on marker artifacts were tested for three sequences (gradient echo, turbo spin echo, and balanced SSFP) in a gel phantom, using 0.55T and 1.5T MRI scanners. Furthermore, an MR-compatible current supply circuit was designed, and the performance of the current-controlled markers was tested in one postmortem animal experiment using the current supply circuit. RESULTS: Direction and parameters of the applied current were determined to provide the highest conspicuity for all three sequences. Marker artifact size was controlled by adjusting the current amplitude, successfully. Visibility of a custom-designed, 20-gauge nitinol needle was increased in both in vitro and postmortem animal experiments using the current supply circuit. CONCLUSION: Current-controlled conductive ink-printed markers can be placed on custom or commercial MR-compatible interventional tools and can provide an easy and effective solution to device tracking under MRI for three sequences by adjusting the applied current parameters with respect to pulse sequence parameters using the current supply circuit.

Learning curve for fusion magnetic resonance imaging targeted prostate biopsy and three-dimensional transrectal ultrasonography segmentation.

OBJECTIVE: To report the learning curve of multiple operators for fusion magnetic resonance imaging (MRI) targeted biopsy and to determine the number of cases needed to achieve proficiency. MATERIALS AND METHODS: All adult males who underwent fusion MRI targeted biopsy between February 2012 and July 2021 for clinically suspected prostate cancer (PCa) in a single centre were included. Fusion transrectal MRI targeted biopsy was performed under local anaesthesia using the Koelis platform. Learning curves for segmentation of transrectal ultrasonography (TRUS) images and the overall MRI targeted biopsy procedure were estimated with locally weighted scatterplot smoothing by computing each operator's timestamps for consecutive procedures. Non-risk-adjusted cumulative sum (CUSUM) methods were used to create learning curves for clinically significant (i.e., International Society of Urological Pathology grade ≥ 2) PCa detection. RESULTS: Overall, 1721 patients underwent MRI targeted biopsy in our centre during the study period. The median (interquartile range) times for TRUS segmentation and for the MRI targeted biopsy procedure were 4.5 (3.5, 6.0) min and 13.2 (10.6, 16.9) min, respectively. Among the 14 operators with experience of more than 50 cases, a plateau was reached after 40 cases for TRUS segmentation time and 50 cases for overall MRI targeted biopsy procedure time. CUSUM analysis showed that the learning curve for clinically significant PCa detection required 25 to 45 procedures to achieve clinical proficiency. Pain scores ranged between 0 and 1 for 84% of patients, and a plateau phase was reached after 20 to 100 cases. CONCLUSIONS: A minimum of 50 cases of MRI targeted biopsy are necessary to achieve clinical and technical proficiency and to reach reproducibility in terms of timing, clinically significant PCa detection, and pain.

Magnetic resonance imaging-guided renal biopsy shows high safety and diagnostic yield: a tertiary cancer center experience.

OBJECTIVES: To evaluate the technical success and outcomes of renal biopsies performed under magnetic resonance imaging (MRI) using a closed-bore, 1.5-Tesla MRI unit. MATERIALS AND METHODS: We retrospectively reviewed our institutional biopsy database and included 150 consecutive MRI-guided biopsies for renal masses between November 2007 and March 2020. We recorded age, sex, BMI, tumor characteristics, RENAL nephrometry score, MRI scan sequence, biopsy technique, complications, diagnostic yield, pathologic outcome, and follow-up imaging. Univariate logistic regression was used to assess the association between different parameters and the development of complications. McNemar's test was used to assess the association between paired diagnostic yield measurements for fine-needle aspiration and core samples. RESULTS: A total of 150 biopsies for 150 lesions were performed in 150 patients. The median tumor size was 2.7 cm. The median BMI was 28.3. The lesions were solid, partially necrotic/cystic, and predominantly cystic in 137, eight, and five patients, respectively. Image guidance using fat saturation steady-state free precession sequence was recorded in 95% of the biopsy procedures. Samples were obtained using both fine-needle aspiration (FNA) and cores in 99 patients (66%), cores only in 40 (26%), and FNA only in three (2%). Tissue sampling was diagnostic in 144 (96%) lesions. No major complication developed following any of the biopsy procedures. The median follow-up imaging duration was 8 years and none of the patients developed biopsy-related long-term complication or tumor seeding. CONCLUSIONS: MRI-guided renal biopsy is safe and effective, with high diagnostic yield and no major complications. CLINICAL RELEVANCE STATEMENT: Image-guided renal biopsy is safe and effective, and should be included in the management algorithm of patients with renal masses. Core biopsy is recommended. KEY POINTS: • MRI-guided biopsy is a safe and effective technique for sampling of renal lesions. • MRI-guided biopsy has high diagnostic yield with no major complications. • Percutaneous image-guided biopsy plays a key role in the management of patients with renal masses.

Magnetic Resonance Imaging-Guided Cryoablation of Prostate Cancer Lymph Node Metastasis.

PURPOSE: To evaluate the safety and effectiveness of magnetic resonance (MR) imaging-guided cryoablation of prostate cancer metastatic lymph nodes (LNs). MATERIALS AND METHODS: Fifty-two patients with prostate cancer who underwent MR imaging-guided LN ablation from September 2013 to June 2022 were retrospectively reviewed. Of these, 6 patients were excluded because adequate ablation margins (3-5 mm) could not be achieved secondary to adjacent structures. The remaining 46 patients (mean age, 70 years [SD ± 7]) underwent 55 MR imaging-guided cryoablation procedures of metastatic LNs (25 in the pelvic sidewall, 20 within the pelvic region, and 10 in the abdomen) with procedural intent of complete ablation. Locoregional tumor control (ie, technical success in the target LN) was evaluated on initial follow-up positron emission tomography (PET) scans at a mean of 4 months (SD ± 2). Preablation and postablation prostate-specific antigen (PSA) levels were recorded. Imaging follow-up continued until a median of 27.5 months (range: 3-108 months). RESULTS: Ninety-five percent (52/55) of treated LNs demonstrated no considerable activity on PET scans at initial follow-up at 4 months (SD ± 2). PSA decreased to an undetectable level of <0.1 ng/mL after cryoablation in 14 of 46 (30.4%) patients with corresponding lack of activity in 13 of 46 (28.2%) patients on continued PET imaging follow-up. Only 6 of 55 (10.9%) patients had transient adverse events, which all resolved with no long-term sequelae. CONCLUSIONS: MR imaging-guided percutaneous cryoablation of metastatic LNs is a safe and technically effective technique for treating metastatic prostate cancer in LNs.

Prototype Description and Ex Vivo Evaluation of a System for Combined Endorectal Magnetic Resonance Imaging and In-Bore Biopsy of the Prostate.

ABSTRACT: We describe early ex vivo proof-of-concept testing of a novel system composed of a disposable endorectal coil and converging multichannel needle guide with a reusable clamp stand, embedded electronics, and baseplate to allow for endorectal magnetic resonance (MR) imaging and in-bore MRI-targeted biopsy of the prostate as a single integrated procedure. Using prostate phantoms imaged with standard T 2 -weighted sequences in a Siemens 3T Prisma MR scanner, we measured the signal-to-noise ratio in successive 1-cm distances from the novel coil and from a commercially available inflatable balloon coil and measured the lateral and longitudinal deviation of the tip of a deployed MR compatible needle from the intended target point. Signal-to-noise ratio obtained with the novel system was significantly better than the inflatable balloon coil at each of five 1-cm intervals, with a mean improvement of 78% ( P < 0.05). In a representative sampling of 15 guidance channels, the mean lateral deviation for MR imaging-guided needle positioning was 1.7 mm and the mean longitudinal deviation was 2.0 mm. Our ex vivo results suggest that our novel system provides significantly improved signal-to-noise ratio when compared with an inflatable balloon coil and is capable of accurate MRI-guided needle deployment.

Update on musculoskeletal applications of magnetic resonance-guided focused ultrasound.

Magnetic resonance-guided focused ultrasound (MRgFUS) is a noninvasive, incisionless, radiation-free technology used to ablate tissue deep within the body. This technique has gained increased popularity following FDA approval for treatment of pain related to bone metastases and limited approval for treatment of osteoid osteoma. MRgFUS delivers superior visualization of soft tissue targets in unlimited imaging planes and precision in targeting and delivery of thermal dose which is all provided during real-time monitoring using MR thermometry. This paper provides an overview of the common musculoskeletal applications of MRgFUS along with updates on clinical outcomes and discussion of future applications.

Electrophysiological Cardiovascular Magnetic Resonance (EP-CMR)-Guided Interventional Procedures: Challenges and Opportunities.

PURPOSE OF REVIEW: Cardiovascular magnetic resonance (CMR) imaging excels in providing detailed three-dimensional anatomical information together with excellent soft tissue contrast and has already become a valuable tool for diagnostic evaluation, electrophysiological procedure (EP) planning, and therapeutical stratification of atrial or ventricular rhythm disorders. CMR-based identification of ablation targets may significantly impact existing concepts of interventional electrophysiology. In order to exploit the inherent advantages of CMR imaging to the fullest, CMR-guided ablation procedures (EP-CMR) are justly considered the ultimate goal. RECENT FINDINGS: Electrophysiological cardiovascular magnetic resonance (EP-CMR) interventional procedures have more recently been introduced to the CMR armamentarium: in a single-center series of 30 patients, an EP-CMR guided ablation success of 93% has been reported, which is comparable to conventional ablation outcomes for typical atrial flutter and procedure and ablation time were also reported to be comparable. However, moving on from already established workflows for the ablation of typical atrial flutter in the interventional CMR environment to treatment of more complex ventricular arrhythmias calls for technical advances regarding development of catheters, sheaths and CMR-compatible defibrillator equipment. CMR imaging has already become an important diagnostic tool in the standard clinical assessment of cardiac arrhythmias. Previous studies have demonstrated the feasibility and safety of performing electrophysiological interventional procedures within the CMR environment and fully CMR-guided ablation of typical atrial flutter can be implemented as a routine procedure in experienced centers. Building upon established workflows, the market release of new, CMR-compatible interventional devices may finally enable targeting ventricular arrhythmias.

Magnetic resonance-guided focused ultrasound versus percutaneous thermal ablation in local control of bone oligometastases: a systematic review and meta-analysis.

BACKGROUND: The percutaneous thermal ablation techniques (pTA) are radiofrequency ablation, cryoablation, and microwave ablation, suitable for the treatment of bone oligometastases. Magnetic resonance-guided focused ultrasound (MRgFUS) is a noninvasive ablation technique. OBJECTIVES: To compare the effectiveness and safety of MRgFUS and pTA for treating bone oligometastases and their complications. METHODS: Studies were selected with a PICO/PRISMA protocol: pTA or MRgFUS in patients with bone oligometastases; non-exclusive curative treatment. Exclusion criteria were: primary bone tumor; concurrent radiation therapy; palliative therapy; and absence of imaging at follow-up. PubMed, BioMed Central, and Scopus were searched. The modified Newcastle-Ottawa Scale assessed articles quality. For each treatment (pTA and MRgFUS), we conducted two separate random-effects meta-analyses to estimate the pooled effectiveness and safety. The effectiveness was assessed by combining the proportions of treated lesions achieving local tumor control (LTC); the safety by combining the complications rates of treated patients. Meta-regression analyses were performed to identify any outcome predictor. RESULTS: A total of 24 articles were included. Pooled LTC rate for MRgFUS was 84% (N = 7, 95% CI 66-97%, I2 = 74.7%) compared to 65% of pTA (N = 17, 95% CI 51-78%, I2 = 89.3%). Pooled complications rate was similar, respectively, 13% (95% CI 1-32%, I2 = 81.0%) for MRgFUS and 12% (95% CI 8-18%, I2 = 39.9%) for pTA, but major complications were recorded with pTA only. The meta-regression analyses, including technique type, study design, tumor, and follow-up, found no significant predictors. DISCUSSION: The effectiveness and safety of the two techniques were found comparable, even though MRgFUS is a noninvasive treatment that did not cause any major complication. Limited data availability on MRgFUS and the lack of direct comparisons with pTA may affect these findings. CONCLUSIONS: MRgFUS can be a valid, safe, and noninvasive treatment for bone oligometastases. Direct comparison studies are needed to confirm its promising benefits.

MRI-guided transrectal prostate laser ablation for benign prostatic hypertrophy: a retrospective cohort study.

PURPOSE: To investigate whether MRI-guided transrectal laser ablation is safe and effective for the treatment of lower urinary tract symptoms caused by BPH. MATERIALS AND METHODS: This single-center retrospective cohort study evaluated men who underwent MRI-guided transrectal laser ablation for BPH between February 2017 and July 2021. Age, prostate-specific antigen, prostate volume, prior surgical BPH treatments if any, International Prostate Symptom Score (IPSS) and Sexual Health Inventory of Men (SHIM) were collected. The primary outcome measures assessed were change in IPSS and SHIM 6, 12 and 24 months after laser ablation and adverse events. RESULTS: Fifty-two patients were included, having completed at least one follow-up survey. The mean patient age was 62.9 ± 5.7 years, and mean prostate volume was 80.2 ± 39.2 cc. Eighteen patients (34.6%) had received a prior BPH treatment. The IPSS scores dropped an average of 16.7 ± 7.0 (p < 0.001), 16.9 ± 7.5 (p < 0.001) and 17.1 ± 7.2 (p < 0.001) points from baseline at 6, 12 and 24 months, respectively. There was no statistically significant difference in IPSS score drop between patients who had received a prior BPH procedure and those who had not (p = 0.628). The SHIM scores showed a statistically insignificant increase at all time points. Nineteen patients (36.5%) reported a complication. There were 12 grade II complications (23%) and seven grade I complications (13.5%). There were no grade III or higher complications. CONCLUSION: Transrectal MRI-guided focal laser ablation is safe and effective for the treatment of lower urinary tract symptoms caused by BPH, with a significant improvement in symptom severity after 2 years.

Long-term outcome of 9G MRI-guided vacuum-assisted breast biopsy: results of 293 single-center procedures and underestimation rate of high-risk lesions over 12 years.

PURPOSE: Breast magnetic resonance imaging (MRI) can detect some malignant lesions that are not visible on mammography (MX) or ultrasound (US). If a targeted, second-look fails, MRI-guided breast biopsy is the only available tool to obtain a tissue sample and pathological proof of these "MRI-only lesions". The aim of this study is to report the performance and underestimation rate of 9G MRI-guided vacuum-assisted breast biopsy (VABB) over 12 years at a single center. MATERIAL AND METHODS: All 9G MRI-VABB procedures performed from January 2010 to December 2021 were retrospectively reviewed. Two MRI scanners (1.5 T and 3 T) were used with the same image resolution and contrast media. All suspicious lesions detected only by breast MRI underwent biopsy. Reference standard was histological diagnosis or at least 1-year negative follow-up. All malignant and atypical lesions underwent surgery, which was used as the reference standard. RESULTS: A total of 293 biopsies were retrospectively reviewed. Histopathological VABB results revealed 142/293 (48.4%) benign lesions, 77/293 (26.2%) high-risk lesions, and 74/293 (25.2%) malignant lesions. No significant complications were observed. Surgical pathology results allowed for the reclassification of n = 7/48 B3b lesions: n = 4 were ductal carcinoma in situ, while n = 3 presented invasive features at surgical histology (2 IDC; 1 ILC). B3b underestimation occurred overall in 14.6% of B3 cases. Breast follow-up was achieved for all benign VABB results, and only one false-negative case was observed. CONCLUSION: Our results confirm that 1.5 T and 3 T MRI-guided VABB is an accurate and safe procedure for histopathologic final diagnosis of MRI-only lesions. Critical issues remain the potential high-risk underestimation rate of B3b VABB results and management of follow-up of benign lesions.

Transperineal versus Transrectal MRI/TRUS fusion-guided prostate biopsy in a large, ethnically diverse, and multiracial cohort.

PURPOSE: To compare transperineal (TP) vs transrectal (TR) magnetic resonance imaging (MRI) and transrectal ultrasound (TRUS) fusion-guided prostate biopsy (PBx) in a large, ethnically diverse and multiracial cohort. MATERIALS AND METHODS: Consecutive patients who underwent multiparametric (mp) MRI followed by TP or TR TRUS-fusion guided PBx, were identified from a prospective database (IRB #HS-13-00663). All patients underwent mpMRI followed by 12-14 core systematic PBx. A minimum of two additional target-biopsy cores were taken per PIRADS≥3 lesion. The endpoint was the detection of clinically significant prostate cancer (CSPCa; Grade Group, GG≥2). Statistical significance was defined as p<0.05. RESULTS: A total of 1491 patients met inclusion criteria, with 480 undergoing TP and 1011 TR PBx. Overall, 11% of patients were Asians, 5% African Americans, 14% Hispanic, 14% Others, and 56% White, similar between TP and TR (p=0.4). For PIRADS 3-5, the TP PBx CSPCa detection was significantly higher (61% vs 54%, p=0.03) than TR PBx, but not for PIRADS 1-2 (13% vs 13%, p=1.0). After adjusting for confounders on multivariable analysis, Black race, but not the PBx approach (TP vs TR), was an independent predictor of CSPCa detection. The median maximum cancer core length (11 vs 8mm; p<0.001) and percent (80% vs 60%; p<0.001) were greater for TP PBx even after adjusting for confounders. CONCLUSIONS: In a large and diverse cohort, Black race, but not the biopsy approach, was an independent predictor for CSPCa detection. TP and TR PBx yielded similar CSPCa detection rates; however the TP PBx was histologically more informative.

Silent active device tracking for MR-guided interventional procedures.

PURPOSE: To evaluate a silent MR active catheter tracking sequence that allows conducting catheter interventions with low acoustic noise levels. METHODS: To reduce the acoustic noise associated with MR catheter tracking, we implemented a technique previously used in conventional MRI. The gradient waveforms are modified to reduce the sound pressure level (SPL) and avoid acoustic resonances of the MRI system. The efficacy of the noise reduction was assessed by software-predicted SPL and verified by measurements. Furthermore, the quality of the catheter tracking signal was assessed in a phantom experiment and during interventional cardiovascular MRI sessions targeted at isthmus-related flutter ablation. RESULTS: The maximum measured SPL in the scanner room was 104 dB(A) for real-time imaging, and 88 dB(A) and 69 dB(A) for conventional and silent tracking, respectively. The SPL measured at different positions in the MR suite using silent tracking were 65-69 dB(A), and thus within the range of a normal conversation. Equivalent signal quality and tracking accuracy were obtained using the silent variant of the catheter tracking sequence. CONCLUSION: Our results indicate that silent MR catheter tracking capabilities are identical to conventional catheter tracking. The achieved acoustic noise reduction comes at no penalty in terms of tracking quality or temporal resolution, improves comfort and safety, and can overcome the need for MR-compatible communication equipment and background noise suppression during the actual interventional procedure.

An interventional MRI guidewire combining profile and tip conspicuity for catheterization at 0.55T.

PURPOSE: We describe a clinical grade, "active", monopole antenna-based metallic guidewire that has a continuous shaft-to-tip image profile, a pre-shaped tip-curve, standard 0.89 mm (0.035″) outer diameter, and a detachable connector for catheter exchange during cardiovascular catheterization at 0.55T. METHODS: Electromagnetic simulations were performed to characterize the magnetic field around the antenna whip for continuous tip visibility. The active guidewire was manufactured using medical grade materials in an ISO Class 7 cleanroom. RF-induced heating of the active guidewire prototype was tested in one gel phantom per ASTM 2182-19a, alone and in tandem with clinical metal-braided catheters. Real-time MRI visibility was tested in one gel phantom and in-vivo in two swine. Mechanical performance was compared with commercial equivalents. RESULTS: The active guidewire provided continuous "profile" shaft and tip visibility in-vitro and in-vivo, analogous to guidewire shaft-and-tip profiles under X-ray. The MRI signal signature matched simulation results. Maximum unscaled RF-induced temperature rise was 5.2°C and 6.5°C (3.47 W/kg local background specific absorption rate), alone and in tandem with a steel-braided catheter, respectively. Mechanical characteristics matched commercial comparator guidewires. CONCLUSION: The active guidewire was clearly visible via real-time MRI at 0.55T and exhibits a favorable geometric sensitivity profile depicting the guidewire continuously from shaft-to-tip including a unique curved-tip signature. RF-induced heating is clinically acceptable. This design allows safe device navigation through luminal structures and heart chambers. The detachable connector allows delivery and exchange of cardiovascular catheters while maintaining guidewire position. This enhanced guidewire design affords the expected performance of X-ray guidewires during human MRI catheterization.

Impact of operator expertise on transperineal free-hand mpMRI-fusion-targeted biopsies under local anaesthesia for prostate cancer diagnosis: a multicenter prospective learning curve.

PURPOSE: Transperineal mpMRI-targeted fusion prostate biopsies (TPFBx) are recommended for prostate cancer diagnosis, but little is known about their learning curve (LC), especially when performed under local anaesthesia (LA). We investigated how operators' and institutions' experience might affect biopsy results. METHODS: Baseline, procedure and pathology data of consecutive TPFBx under LA were prospectively collected at two academic Institutions, from Sep 2016 to May 2019. Main inclusion criterion was a positive MRI. Endpoints were biopsy duration, clinically significant prostate cancer detection rate on targeted cores (csCDR-T), complications, pain and urinary function. Data were analysed per-centre and per-operator (with ≥ 50 procedures), comparing groups of consecutive patient, and subsequently through regression and CUSUM analyses. Learning curves were plotted using an adjusted lowess smoothing function. RESULTS: We included 1014 patients, with 27.3% csCDR-T and a median duration was 15 min (IQR 12-18). A LC for biopsy duration was detected, with the steeper phase ending after around 50 procedures, in most operators. No reproducible evidence in favour of an impact of experience on csPCa detection was found at operator's level, whilst a possible gentle LC of limited clinical relevance emerged at Institutional level; complications, pain and IPSS variations were not related to operator experience. CONCLUSION: The implementation of TPFBx under LA was feasible, safe and efficient since early phases with a relatively short learning curve for procedure time.

Interventional cardiovascular magnetic resonance: state-of-the-art.

Transcatheter cardiovascular interventions increasingly rely on advanced imaging. X-ray fluoroscopy provides excellent visualization of catheters and devices, but poor visualization of anatomy. In contrast, magnetic resonance imaging (MRI) provides excellent visualization of anatomy and can generate real-time imaging with frame rates similar to X-ray fluoroscopy. Realization of MRI as a primary imaging modality for cardiovascular interventions has been slow, largely because existing guidewires, catheters and other devices create imaging artifacts and can heat dangerously. Nonetheless, numerous clinical centers have started interventional cardiovascular magnetic resonance (iCMR) programs for invasive hemodynamic studies or electrophysiology procedures to leverage the clear advantages of MRI tissue characterization, to quantify cardiac chamber function and flow, and to avoid ionizing radiation exposure. Clinical implementation of more complex cardiovascular interventions has been challenging because catheters and other tools require re-engineering for safety and conspicuity in the iCMR environment. However, recent innovations in scanner and interventional device technology, in particular availability of high performance low-field MRI scanners could be the inflection point, enabling a new generation of iCMR procedures. In this review we review these technical considerations, summarize contemporary clinical iCMR experience, and consider potential future applications.

Adverse events and complications after magnetic resonance-guided focused ultrasound (MRgFUS) therapy in uterine fibroids - a systematic review and future perspectives.

OBJECTIVES: The aim of this review was to analyze and summarize the most common adverse events (AEs) and complications after magnetic resonance-guided focused ultrasound (MRgFUS) therapy in uterine fibroids (UFs) and to establish the risk factors of their occurrence. METHODS: We searched for original research studies evaluating MRgFUS therapy in UFs with outcomes containing AEs and/or complications in different databases (PubMed/MEDLINE, SCOPUS, COCHRANE) until March 2022. Reviews, editorials, opinions or letters, case studies, conference papers and abstracts were excluded from the analysis. The systematic literature search identified 446 articles, 43 of which were analyzed. RESULTS: According to available evidence, the overall incidence of serious complications in MRgFUS therapy is relatively low. No AEs/complications were reported in 11 out of 43 analyzed studies. The mean occurrence of all AEs in the analyzed material was 24.67%. The most commonly described AEs included pain, skin burns, urinary tract infections and sciatic neuropraxia. Major AEs, such as skin ulcerations or deep vein thrombosis, occurred in 0.41% of cases in the analyzed material. CONCLUSION: MRgFUS seems to be safe in UF therapy. The occurrence of AEs, especially major ones, is relatively low in comparison with other methods. The new devices and more experience of their users seem to reduce AE rate. The lack of unification in AE reporting and missing data are the main issues in this area. More prospective, randomized studies with unified reporting and long follow-up are needed to determine the safety in a long-term perspective.

The Effect of Different Types of Prostate Biopsy Techniques on Post-Biopsy Infectious Complications.

PURPOSE: The aim of our study was to compare infectious complication rates between different prostate biopsy techniques with various number of biopsy cores. MATERIALS AND METHODS: In this retrospective study, all patients from 2 hospitals who underwent prostate biopsy between 2012 and 2019 were identified. Cohorts with different types of prostate biopsies were compiled within these hospitals. Primary outcome measure was any registered infectious complication within 7 days post-biopsy. Secondary outcomes were infectious complications within 30 days, hospitalization and bacteremia. To compare the risk of infection following different prostate biopsy techniques, data was fitted into a logistic regression model adjusting for potential confounders. RESULTS: In total, 4,233 prostate biopsies in 3,707 patients were included. After systematic transrectal ultrasound-guided prostate biopsy (TRUSPB; 12±1.4 biopsy cores), 4.0% (2,607) of all patients had infectious complications within 7 days post-biopsy. Transperineal magnetic resonance imaging (MRI)-ultrasound fusion guided prostate biopsy (16±3.7 biopsy cores) was associated with significantly lower infection rates than systematic TRUSPB (adjusted OR: 0.29 [0.09-0.73] 95% confidence interval [CI]). Transrectal targeted MRI-ultrasound fusion guided prostate biopsy (3.1±0.8 biopsy cores) and transrectal targeted in-bore MRI guided prostate biopsy (2.8±0.8 biopsy cores) also showed fewer infectious complications than systematic TRUSPB (adjusted OR: 0.41 [0.12-1.12] 95% CI and 0.68 [0.37-1.20] 95% CI, respectively). CONCLUSIONS: Transperineal prostate biopsy, or transrectal prostate biopsy with reduced number of biopsy cores, could lower the risk of infectious complications.

Optimizing Combined Magnetic Resonance Imaging (MRI)-Targeted and Systematic Biopsy Strategies: Sparing the Multiparametric MRI-Negative Transitional Zone in Presence of Exclusively Peripheral Multiparametric MRI-Suspect Lesions.

PURPOSE: We assessed whether sampling of the transitional zone can be spared in patients with exclusively peripheral prostate cancer (PCa)-suspicious multiparametric magnetic resonance imaging (mpMRI) lesions who undergo combined mpMRI targeted (TBx) and systematic prostate biopsies (SBx). MATERIALS AND METHODS: Of 1,685 patients who underwent extended SBx including transitional zone sampling and had TBx of ≥1 lesion in the peripheral and/or transitional zone, we selected 863 patients with exclusively peripheral PCa-suspicious lesions and negative transitional zone mpMRI. Clinically significant PCa (csPCa) was defined as Gleason score (GS) ≥3+4. Within the selected cohort we performed a retrospective head-to-head comparison of csPCa detection rates between biopsy protocols: A) combination of peripheral TBx plus extended SBx including transitional zone sampling vs B) peripheral TBx plus SBx without any transitional zone sampling. Analyses were complemented with multivariable logistic regression models (LRMs) in the total cohort for predicting csPCa in SBx transitional zone sampling. RESULTS: Compared to the extended protocol (A), omission of systematic transitional zone sampling (B) yielded similar PCa detection for csPCa (48% vs 47%) and GS 3+3 (21% vs 20%). Only 2.0% csPCa was additionally detected with transitional zone SBx sampling (A). LRM confirmed that intraprostatic zonal distribution of mpMRI lesions independently influences csPCa detection rates of transitional zone SBx sampling. CONCLUSIONS: A peripheral TBx plus SBx without any transitional zone sampling protocol (B) yields similar csPCa detection rates as the standard extended protocol (A) but may reduce biopsy-related morbidity. This zone-dependent biopsy strategy warrants prospective evaluation to optimize the extent of systematic biopsies in presence of suspicious mpMRI lesions.