Transcutaneous Ablation of Lung Tissue in a Porcine Model Using Magnetic-Resonance-Guided Focused Ultrasound (MRgFUS).

Focused ultrasound (FUS) is a minimally invasive treatment that utilizes high-energy ultrasound waves to thermally ablate tissue. Magnetic resonance imaging (MRI) guidance may be combined with FUS (MRgFUS) to increase its accuracy and has been proposed for lung tumor ablation/debulking. However, the lungs are predominantly filled with air, which attenuates the strength of the FUS beam. This investigation aimed to test the feasibility of a new approach using an intentional lung collapse to reduce the amount of air inside the lung and a controlled hydrothorax to create an acoustic window for transcutaneous MRgFUS lung ablation. Eleven pigs had one lung mechanically ventilated while the other lung underwent a controlled collapse and subsequent hydrothorax of that hemisphere. The MRgFUS lung ablations were then conducted via the intercostal space. All the animals recovered well and remained healthy in the week following the FUS treatment. The location and size of the ablations were confirmed one week post-treatment via MRI, necropsy, and histological analysis. The animals had almost no side effects and the skin burns were completely eliminated after the first two animal studies, following technique refinement. This study introduces a novel methodology of MRgFUS that can be used to treat deep lung parenchyma in a safe and viable manner.

MRI in-bore biopsy following MRI/US fusion-guided biopsy in patients with persistent suspicion of clinically significant prostate cancer.

PURPOSE: Patients with suspicion of clinically significant prostate cancer (csPC) on multiparametric prostate MRI (mpMRI) but negative or inconclusive MRI/US fusion-guided biopsy (FB) can be challenging in clinical practice. To assess the utility of MRI in-bore biopsy (IB) in patients with discordant imaging and histopathological findings after FB. METHODS: Consecutive patients with Prostate Imaging Reporting and Data System (PI-RADS) category 4 or 5 on mpMRI at 3T after FB without histologically confirmed csPC who underwent IB between 01/2014 and 05/2022, were retrospectively included. The primary objective was to assess the detection rate of csPC. Secondary objectives were to analyze clinical parameters, MRI parameters, and lesion localization. RESULTS: In the final cohort of 51 patients, the IB resulted in an overall detection rate of 71% for PC and 47% for csPC. Furthermore, in 55% of cases with initial low-grade PC, the Gleason score was upgraded after IB. CsPC was often detected apical and/or anterior. The detection rate for PC was 58% in PI-RADS category 4 and 94% in PI-RADS category 5 (csPC 39% and 61%, respectively). Patients with csPC had statistically significant smaller prostate volumes, a higher PI-RADS category, a higher prostate-specific antigen density (PSAD), and were older. CONCLUSIONS: For a relevant proportion of patients with PI-RADS category 4 or 5 and negative or inconclusive findings on previous FB, but with persistent suspicion of csPC, a subsequent IB verified the presence of csPC. Therefore, IB can be a backup in cases of uncertainty.

Development of an MR-Guided Focused Ultrasound (MRgFUS) Lesioning Approach for the Fornix in the Rat Brain.

OBJECTIVE: High-intensity magnetic resonance-guided focused ultrasound (MRgFUS) is a non-invasive therapy to lesion brain tissue, used clinically in patients and pre-clinically in several animal models. Challenges with focused ablation in rodent brains can include skull and near-field heating and accurately targeting small and deep brain structures. We overcame these challenges by creating a novel method consisting of a craniectomy skull preparation, a high-frequency transducer (3 MHz) with a small ultrasound focal spot, a transducer positioning system with an added manual adjustment of ∼0.1 mm targeting accuracy, and MR acoustic radiation force imaging for confirmation of focal spot placement. METHODS: The study consisted of two main parts. First, two skull preparation approaches were compared. A skull thinning approach (n = 7 lesions) was compared to a craniectomy approach (n = 22 lesions), which confirmed a craniectomy was necessary to decrease skull and near-field heating. Second, the two transducer positioning systems were compared with the fornix chosen as a subcortical ablation target. We evaluated the accuracy of targeting using histologic methods from a high-frequency transducer with a small ultrasound focal spot and MR acoustic radiation force imaging. RESULTS: Comparing a motorized adjustment system (∼1 mm precision, n = 17 lesions) to the motorized system with an added micromanipulator (∼0.1 mm precision, n = 14 lesions), we saw an increase in the accuracy of targeting the fornix by 133%. CONCLUSIONS: The described work allows for repeatable and accurate targeting of small and deep structures in the rodent brain, such as the fornix, enabling the investigation of neurological disorders in chronic disease models.

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.

3.0-T MR-guided transgluteal in-bore-targeted prostate biopsy under local anesthesia in patients without rectal access: a single-institute experience and review of literature.

PURPOSE: To describe the technique and evaluate the performance of MRI-guided transgluteal in-bore-targeted biopsy of the prostate gland under local anesthesia in patients without rectal access. METHODS: Ten men (mean age, 69 (range 57-86) years) without rectal access underwent 13 MRI-guided transgluteal in-bore-targeted biopsy of the prostate gland under local anesthesia. All patients underwent mp-MRI at our institute prior to biopsy. Three patients had prior US-guided transperineal biopsy which was unsuccessful in one, negative in one, and yielded GG1 (GS6) PCa in one. Procedure time, complications, histopathology result, and subsequent management were recorded. RESULTS: Median interval between rectal surgery and presentation with elevated PSA was 12.5 years (interquartile range (IQR) 25-75, 8-36.5 years). Mean PSA was 11.9 (range, 4.8 -59.0) ng/ml and PSA density was 0.49 (0.05 -3.2) ng/ml/ml. Distribution of PI-RADS v2.0/2.1 scores of the targeted lesions were PI-RADS 5-3; PI-RADS 4-6; and PI-RADS 3-1. Mean lesion size was 1.5 cm (range, 1.0-3.6 cm). Median interval between MRI and biopsy was 5.5 months (IQR 25-75, 1.5-9 months). Mean procedure time was 47.4 min (range, 29-80 min) and the number of cores varied between 3 and 5. Of the 13 biopsies, 4 yielded clinically significant prostate cancer (csPca), with a Gleason score ≥ 7, 1 yielded insignificant prostate cancer (Gleason score = 6), 7 yielded benign prostatic tissue, and one was technically unsuccessful. 3/13 biopsies were repeat biopsies which detected csPCa in 2 out of the 3 patients. None of the patients had biopsy-related complication. Biopsy result changed management to radiation therapy with ADT in 2 patients with the rest on active surveillance. CONCLUSION: MRI-guided transgluteal in-bore-targeted biopsy of the prostate gland under local anesthesia is feasible in patients without rectal access.

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.

Significant prostate cancer risk after MRI-guided biopsy showing benign findings: Results from a cohort of 381 men.

BACKGROUND: MRI-guided biopsy (MGB) contributes to the diagnosis of clinically significant Prostate Cancer (csPCa). However, there are no clear recommendations for the management of men after a negative MGB. The aim of this study was to assess the risk of csPCa after a first negative MGB. METHODS: Between 2014 and 2020, we selected men with a PI-RADS score ≥ 3 on MRI and a negative MGB (showing benign findings) performed for suspected prostate cancer. MGB (targeted and systematic biopsies) was performed using fully integrated mobile fusion imaging (KOELIS). The primary endpoint was the rate of csPCa (defined as an ISUP grade ≥ 2) diagnosed after a first negative MGB. RESULTS: A total of 381 men with a negative MGB and a median age of 65 (IQR: 59-69, range: 46-85) years were included. During the median follow-up of 31 months, 124 men (32.5%) had a new MRI, and 76 (19.9%) were referred for a new MGB, which revealed csPCa in 16 (4.2%) of them. We found no statistical difference in the characteristics of men diagnosed with csPCa compared with men with no csPCa after the second MGB. CONCLUSION: We observed a risk of significant prostate cancer in 4% of men two years after a negative MRI-guided biopsy. Performing a repeat MRI could improve the selection of men who will benefit from a repeat MRI-guided biopsy, but a clear protocol is needed to follow these patients.

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.

Prostate Cancer Detection and Complications of Transperineal Versus Transrectal Magnetic Resonance Imaging-fusion Guided Prostate Biopsies.

OBJECTIVE: To assess the rates of detection of clinically significant prostate cancer (csPCa) and complications associated with transperineal (TP) and transrectal (TR) biopsy approaches to magnetic resonance imaging (MRI)-fusion targeted biopsy. MATERIALS AND METHODS: We retrospectively identified men who underwent TP or TR MRI-targeted biopsy with concurrent systematic random biopsy from August 2020 to August 2021. Primary outcomes were detection rates of csPCa and 30-day complication rates between the 2 MRI-biopsy groups. Data were additionally stratified by prior biopsy status. RESULTS: A total of 361 patients were included in the analysis. No demographic differences were observed. No significant differences were observed between TP and TR approaches on any of the outcomes of interest. TR MRI-targeted biopsies identified csPCa in 47.2% of patients, and TP MRI-targeted biopsies identified csPCa in 48.6% of patients (P = .78). No significant differences were observed in csPCa detection between the 2 approaches for patients on active surveillance (P = .59), patients with prior negative biopsy (P = .34), and patients who were biopsy naïve (P = .19). Complication rates did not vary by approach (P = .45). CONCLUSION: Neither the identification of csPCa by MRI-targeted biopsy nor rates of complications differed significantly based on a TR or TP approach. No differences were seen between MRI-targeted approaches based on prior biopsy or active surveillance status.

Intra-practice Urologist-level Variation in Targeted Fusion Biopsy Outcomes.

OBJECTIVE: To examine the extent to which the urologist performing biopsy contributes to variation in prostate cancer detection during fusion-guided prostate biopsy. METHODS: All men in the Michigan Urological Surgery Improvement Collaborative (MUSIC) clinical registry who underwent fusion biopsy at Michigan Medicine from August 2017 to March 2019 were included. The primary outcomes were clinically significant cancer detection rate (defined as Gleason Grade ≥2) in targeted cores and clinically significant cancer detection on targeted cores stratified by PI-RADS score. Bivariate and multivariable logistic regression analyses were performed. RESULTS: A total of 1133 fusion biopsies performed by 5 providers were included. When adjusting for patient age, PSA, race, family history, prostate volume, clinical stage, and PI-RADS score, there was no significant difference in targeted clinically significant cancer detection rates across providers (range = 38.5%-46.9%, adjusted P-value = .575). Clinically significant cancer detection rates ranged from 11.1% to 16.7% in PI-RADS 3 (unadjusted P = .838), from 24.6% to 43.4% in PI-RADS 4 (adjusted P = .003), and from 69.4% to 78.8% in PI-RADS 5 (adjusted P = .766) lesions. CONCLUSION: There was a statistically significant difference in clinically significant prostate cancer detection in PI-RADS 4 lesions across providers. These findings suggest that even among experienced providers, variation at the urologist level may contribute to differences in clinically significant cancer detection rates within PI-RADS 4 lesions. However, the relative impact of biopsy technique, radiologist interpretation, and MR acquisition protocol requires further study.

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.

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.

Comparative Effectiveness of Magnetic Resonance Imaging-Ultrasound Fusion Versus In-bore Magnetic Resonance Imaging-targeted Prostate Biopsy.

OBJECTIVE: To examine the comparative effectiveness of magnetic resonance imaging-ultrasound (MRI-U/S) fusion biopsy and in-bore MRI-targeted biopsy. METHODS: We identified men aged 18-89 with a diagnosis of elevated prostate specific antigen (PSA) or Gleason 6 prostate cancer on active surveillance who underwent MRI-U/S fusion prostate biopsy (12-core + targeted) in the office or in-bore MRI-targeted biopsy (MRI-IB; targeted only). The cancer detection rate (CDR; Gleason 6-10) and clinically significant CDR (csCDR; Gleason 7-10) were compared across biopsy techniques, adjusted for patient and radiographic features. RESULTS: A total of 280 patients (346 lesions) were included, of whom 23.9% were on active surveillance for Gleason 6 prostate cancer. In the per-patient analyses, there was no statistically significant difference in adjusted overall CDR (64.1% vs 54.2%; P = .24) or csCDR (36.5% vs 37.9%; P = .85) between MRI-U/S and MRI-IB biopsy. In the per-lesion analyses, there was no statistically significant difference in adjusted overall CDR (45.7% vs 50.1%; P = .49) between MRI-U/S and MRI-IB biopsy, but MRI-IB biopsy was associated with a higher csCDR than MRI-U/S biopsy (32.8% vs 21.4%; P = .02). CONCLUSION: We observed no statistically significant differences in cancer detection rates between MRI-U/S fusion biopsy and MRI-IB biopsy in per-patient analyses. However, MRI-IB biopsy was associated with higher csCDR when considering targeted biopsy cores only. These results suggest that systematic cores should be obtained when performing MRI-U/S fusion biopsy.

Significance of non-standardized magnetic resonance imaging abnormalities and subsequent targeted prostate cancer biopsy for pathologists: A retrospective observational study.

Prostate biopsy is essential in diagnosing prostate cancer. The Prostate Imaging-Reporting and Data System (PI-RADS) and magnetic resonance imaging (MRI)-transrectal ultrasound fusion-guided biopsy are also useful for diagnosis. However, the burden of implementing and maintaining these techniques should be considered. Therefore, we investigated the significance of non-standardized pre-biopsy MRI abnormalities (conditions not in accordance with PI-RADS) and subsequent targeted biopsy. We collected clinicopathological data, including the presence or absence of MRI abnormalities, through biopsies from January 2017 to February 2022 at the Kanagawa Cancer Center and performed statistical analyses. We enrolled in 1086 cases: MRI abnormalities were observed in 861 cases (79.3%). In these 861 cases, the adenocarcinoma detection rate, number of positive cores, and length of the highest Grade Group (GG) lesions were significantly higher. In the multivariate analysis, MRI abnormalities were the most significant factor for detecting adenocarcinoma of ≥GG 2 (odds ratio: 4.52, 95% confidence interval: 3.08-6.63). Targeted biopsy showed a higher percentage of positive cores with ≥GG2 and longer highest GG lesion lengths than systematic biopsy. Furthermore, the highest GG was upgraded in 109 of 788 cases by targeted biopsy. However, several adenocarcinomas (125/788; 15.9%) could not be detected using only targeted biopsy. Non-standardized MRI abnormalities are powerful predictors of cancer and grading. Targeted biopsies based on MRI abnormalities provide several benefits. Owing to the relatively low implementation hurdle, these biopsies may serve as a bridge until the ideal approaches are popularized if the limitations are well understood.

Cytoreductive Surgical Treatment of Pleural Mesothelioma in a Porcine Model Using Magnetic-Resonance-Guided Focused Ultrasound Surgery (MRgFUS) and Radiofrequency Ablation (RFA).

A combination of surgery and chemotherapy is the most effective treatment available for Malignant Pleural Mesothelioma (MPM). However, both cause significant collateral damage and cannot eliminate residual microscopic disease. This investigation aimed to compare and determine the feasibility of utilizing Radiofrequency Ablation (RFA) and Magnetic-Resonance-guided Focused Ultrasound Surgery (MRgFUS) as alternative treatments for MPM. A large animal tumor model was developed in 13 Yorkshire female pigs using the MSTO211H cell line. Two pigs were initially used to determine the cyclosporine dose required for immunosuppression and tumor development. Subsequently, 11 other pigs underwent tumor development. Of these 11, 2 died during cell inoculation. Small tumor masses and adhesions were present in the other 9, indicating mesothelioma development. Five pigs then received RFA treatment, and 4 pigs received MRgFUS treatment. Tumor model development and effect of the two treatments were examined using MRI and by necropsy. RFA and MRgFUS both successfully ablated approximately the same sized area in the same treatment time. This study demonstrates that RFA and MRgFUS are feasible for tumor debulking, and while MRgFUS requires more pretreatment planning compared to RFA, MRgFUS is a completely noninvasive procedure.

CT-based image-guided brachytherapy in uterine cervical cancer: Effect of tumor dose and volume on local control.

BACKGROUND AND PURPOSE: To determine the optimal primary tumor dose for cervical cancer treatment using computed tomography (CT)-based image-guided brachytherapy (IGBT). MATERIALS AND METHODS: We retrospectively reviewed 171 patients with cervical cancer who underwent both external beam radiation therapy (EBRT) and IGBT between May 2015 and December 2019. Majority of EBRT plan included central shielding technique. CT-based IGBT was performed weekly a median of three times. Magnetic resonance imaging preceded the first and third session of IGBT for target delineation. RESULTS: The median age of the patients was 64 years (range: 30-91 years). The median follow-up time for living patients was 43 months (range: 6-76 months). The 3-year local control rates according to the International Federation of Gynecology and Obstetrics (FIGO, 2008) stages were 89%, 100%, 92%, 89%, 78%, and 100% for stages IB, IIA, IIB, IIIA, IIIB, and IVA, respectively. The median EBRT dose to the central pelvis and parametrium/pelvic wall was 41.4 Gy and 50.4 Gy, respectively. Patients who received a cumulative 2 Gy equivalent dose (EQD2) (α/ß = 10 Gy) of high-risk clinical target volume (HR CTV) D90% ≥ 75 Gy achieved a long-term local control rate of 93%, compared with 80% in those who received <75 Gy (p = 0.02). CONCLUSION: This is one of the largest CT-based IGBT series examining the treatment of cervical cancer based on the tumor dose-volume relationship. An HR CTV D90% ≥75 Gy was significantly associated with favorable local control in this study.

Interventional cardiac magnetic resonance imaging: current applications, technology readiness level, and future perspectives.

BACKGROUND: Cardiac magnetic resonance (CMR) provides excellent temporal and spatial resolution, tissue characterization, and flow measurements. This enables major advantages when guiding cardiac invasive procedures compared with X-ray fluoroscopy or ultrasound guidance. However, clinical implementation is limited due to limited availability of technological advancements in magnetic resonance imaging (MRI) compatible equipment. A systematic review of the available literature on past and present applications of interventional MR and its technology readiness level (TRL) was performed, also suggesting future applications. METHODS: A structured literature search was performed using PubMed. Search terms were focused on interventional CMR, cardiac catheterization, and other cardiac invasive procedures. All search results were screened for relevance by language, title, and abstract. TRL was adjusted for use in this article, level 1 being in a hypothetical stage and level 9 being widespread clinical translation. The papers were categorized by the type of procedure and the TRL was estimated. RESULTS: Of 466 papers, 117 papers met the inclusion criteria. TRL was most frequently estimated at level 5 meaning only applicable to in vivo animal studies. Diagnostic right heart catheterization and cavotricuspid isthmus ablation had the highest TRL of 8, meaning proven feasibility and efficacy in a series of humans. CONCLUSION: This article shows that interventional CMR has a potential widespread application although clinical translation is at a modest level with TRL usually at 5. Future development should be directed toward availability of MR-compatible equipment and further improvement of the CMR techniques. This could lead to increased TRL of interventional CMR providing better treatment.

[Image-guided biopsy of the prostate gland]. / Bildgesteuerte Biopsie der Prostata.

The recommendations on carrying out a multiparametric magnetic resonance imaging (mpMRI) for the primary diagnostics and during active surveillance of prostate cancer, include as a consequence an image-guided sampling from conspicuous areas. In doing so, the information on the localization provided by mpMRI is used for a targeted biopsy of the area suspected of being a tumor. The targeted sampling is mainly performed under sonographic control and after fusion of MRI and ultrasound but can also be (mostly in special cases) carried out directly in the MRI scanner. In an ultrasound-guided biopsy, it is vital to coregister the MR images with the ultrasound images (segmentation of the contour of the prostate and registration of suspect findings). This coregistration can either be carried out cognitively (transfer by the person performing the biopsy alone) or software based. Each method shows specific advantages and disadvantages in the prioritization between diagnostic accuracy and resource expenditure.