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  • 1
    Online Resource
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    Repeat it without me: Crowdsourcing the T 1 mapping common ground via the ISMRM reproducibility challenge
    Wiley ; 2024
    In:  Magnetic Resonance in Medicine Vol. 92, No. 3 ( 2024-09), p. 1115-1127
    Details
    In: Magnetic Resonance in Medicine, Wiley, Vol. 92, No. 3 ( 2024-09), p. 1115-1127
    Abstract: T 1 mapping is a widely used quantitative MRI technique, but its tissue‐specific values remain inconsistent across protocols, sites, and vendors. The ISMRM Reproducible Research and Quantitative MR study groups jointly launched a challenge to assess the reproducibility of a well‐established inversion‐recovery T 1 mapping technique, using acquisition details from a seminal T 1 mapping paper on a standardized phantom and in human brains. Methods The challenge used the acquisition protocol from Barral et al. (2010). Researchers collected T 1 mapping data on the ISMRM/NIST phantom and/or in human brains. Data submission, pipeline development, and analysis were conducted using open‐source platforms. Intersubmission and intrasubmission comparisons were performed. Results Eighteen submissions (39 phantom and 56 human datasets) on scanners by three MRI vendors were collected at 3 T (except one, at 0.35 T). The mean coefficient of variation was 6.1% for intersubmission phantom measurements, and 2.9% for intrasubmission measurements. For humans, the intersubmission/intrasubmission coefficient of variation was 5.9/3.2% in the genu and 16/6.9% in the cortex. An interactive dashboard for data visualization was also developed: https://rrsg2020.dashboards.neurolibre.org . Conclusion The T 1 intersubmission variability was twice as high as the intrasubmission variability in both phantoms and human brains, indicating that the acquisition details in the original paper were insufficient to reproduce a quantitative MRI protocol. This study reports the inherent uncertainty in T 1 measures across independent research groups, bringing us one step closer to a practical clinical baseline of T 1 variations in vivo.
    Type of Medium: Online Resource
    ISSN: 0740-3194 , 1522-2594
    URL: Issue
    URL: Article
    DOI: 10.1002/mrm.v92.3
    DOI: 10.1002/mrm.30111
    Language: English
    Publisher: Wiley
    Publication Date: 2024
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  • 2
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    Comparison of methods for intravoxel incoherent motion parameter estimation in the brain from flow‐compensated and non‐flow‐compensated diffusion‐encoded data
    Wiley ; 2024
    In:  Magnetic Resonance in Medicine Vol. 92, No. 1 ( 2024-07), p. 303-318
    Details
    In: Magnetic Resonance in Medicine, Wiley, Vol. 92, No. 1 ( 2024-07), p. 303-318
    Abstract: Joint analysis of flow‐compensated (FC) and non‐flow‐compensated (NC) diffusion MRI (dMRI) data has been suggested for increased robustness of intravoxel incoherent motion (IVIM) parameter estimation. For this purpose, a set of methods commonly used or previously found useful for IVIM analysis of dMRI data obtained with conventional diffusion encoding were evaluated in healthy human brain. Methods Five methods for joint IVIM analysis of FC and NC dMRI data were compared: (1) direct non‐linear least squares fitting, (2) a segmented fitting algorithm with estimation of the diffusion coefficient from higher b‐values of NC data, (3) a Bayesian algorithm with uniform prior distributions, (4) a Bayesian algorithm with spatial prior distributions, and (5) a deep learning‐based algorithm. Methods were evaluated on brain dMRI data from healthy subjects and simulated data at multiple noise levels. Bipolar diffusion encoding gradients were used with b ‐values 0–200 s/mm 2 and corresponding flow weighting factors 0–2.35 s/mm for NC data and by design 0 for FC data. Data were acquired twice for repeatability analysis. Results Measurement repeatability as well as estimation bias and variability were at similar levels or better with the Bayesian algorithm with spatial prior distributions and the deep learning‐based algorithm for IVIM parameters and , and for the Bayesian algorithm only for , relative to the other methods. Conclusion A Bayesian algorithm with spatial prior distributions is preferable for joint IVIM analysis of FC and NC dMRI data in the healthy human brain, but deep learning‐based algorithms appear promising.
    Type of Medium: Online Resource
    ISSN: 0740-3194 , 1522-2594
    URL: Issue
    URL: Article
    DOI: 10.1002/mrm.v92.1
    DOI: 10.1002/mrm.30042
    Language: English
    Publisher: Wiley
    Publication Date: 2024
    detail.hit.zdb_id: 605774-3
    detail.hit.zdb_id: 1493786-4
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  • 3
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    [OA018] Improved absolute metabolite quantification by localized magnetic resonance spectroscopy simulations
    Elsevier BV ; 2018
    In:  Physica Medica Vol. 52 ( 2018-08), p. 7-8
    Details
    In: Physica Medica, Elsevier BV, Vol. 52 ( 2018-08), p. 7-8
    Type of Medium: Online Resource
    ISSN: 1120-1797
    URL: Article
    DOI: 10.1016/j.ejmp.2018.06.090
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2018
    detail.hit.zdb_id: 1122650-X
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  • 4
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    72287 - MRI protocol for rapid identification of sentinel lymph nodes using iron nanoparticles - Fast Acquisition Sentinel lymph node Tracking MRI (FAST-MRI)
    Oxford University Press (OUP) ; 2024
    In:  British Journal of Surgery Vol. 111, No. Supplement_7 ( 2024-08-02)
    Details
    In: British Journal of Surgery, Oxford University Press (OUP), Vol. 111, No. Supplement_7 ( 2024-08-02)
    Abstract: Determining sentinel lymph node (SLN) status is crucial for treatment decisions in patients with melanoma. Superparamagnetic iron oxide nanoparticles (SPIO) combined with MRI have emerged as an alternative to technetium and lymphoscintigraphy for preoperative mapping of SLN. The MRI protocols so far are extensive with long in-camera time. This study aimed to evaluate an optimized MRI protocol for rapid identification of SLNs using SPIO as a tracer without compromising diagnostic quality, the Fast Acquisition Sentinel lymph node Tracking MRI (FAST-MRI). Method Patients with confirmed melanoma on the trunk or limbs, without clinically suspected lymph node metastasis, were eligible. All patients received an injection of 0.1 mL SPIO divided into four quadrants around the scar. The 5-minute FAST-MRI protocol, using only T1-sequences over the axillary and/or inguinal basins, was conducted no earlier than 30 minutes post-injection. Technetium and lymphoscintigraphy were used according to routine. SLN-biopsy was performed using a magnetometer and gamma probe for SLN-detection. Result Twenty patients were enrolled, and SLNs were successfully identified in all with both methods. The FAST-MRI protocol detected more SLNs than lymphoscintigraphy (50 vs 39 SLNs), but the number of SLNs identified during surgery was similar (46 vs 44) (Table 1). Out of 53 SLNs removed, four had metastases, all identified by both methods. Discussion The novel FAST-MRI protocol, with a 5-minute scan time, was feasible in detecting SLNs without compromising diagnostic quality. Both the preoperative SLN-mapping and intraoperative SLN-detection using the magnetic technique proved comparable to the radioactive technique.
    Type of Medium: Online Resource
    ISSN: 0007-1323 , 1365-2168
    URL: Article
    DOI: 10.1093/bjs/znae175.037
    Language: English
    Publisher: Oxford University Press (OUP)
    Publication Date: 2024
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    detail.hit.zdb_id: 2006309-X
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  • 5
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    Sentinel lymph node localization and staging with a low-dose of superparamagnetic iron oxide (SPIO) enhanced MRI and magnetometer in patients with cutaneous melanoma of the extremity - The MAGMEN feasibility study
    Elsevier BV ; 2022
    In:  European Journal of Surgical Oncology Vol. 48, No. 2 ( 2022-02), p. 326-332
    Details
    In: European Journal of Surgical Oncology, Elsevier BV, Vol. 48, No. 2 ( 2022-02), p. 326-332
    Type of Medium: Online Resource
    ISSN: 0748-7983
    URL: Article
    DOI: 10.1016/j.ejso.2021.12.467
    Language: English
    Publisher: Elsevier BV
    Publication Date: 2022
    detail.hit.zdb_id: 2135606-3
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  • 6
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    Data‐driven identification of tumor subregions based on intravoxel incoherent motion reveals association with proliferative activity
    Wiley ; 2019
    In:  Magnetic Resonance in Medicine Vol. 82, No. 4 ( 2019-10), p. 1480-1490
    Details
    In: Magnetic Resonance in Medicine, Wiley, Vol. 82, No. 4 ( 2019-10), p. 1480-1490
    Abstract: Intravoxel incoherent motion (IVIM) analysis gives information on tissue diffusion and perfusion and may thus have a potential for e.g. tumor tissue characterization. This work aims to study if clustering based on IVIM parameter maps can identify tumor subregions, and to assess the relevance of obtained subregions by histological analysis. Methods Fourteen mice with human neuroendocrine tumors were examined with diffusion‐weighted imaging to obtain IVIM parameter maps. Gaussian mixture models with IVIM maps from all tumors as input were used to partition voxels into k clusters, where k  = 2 was chosen for further analysis based on goodness of fit. Clustering was performed with and without the perfusion‐related IVIM parameter , and with and without including spatial information. The validity of the clustering was assessed by comparison with corresponding histologically stained tumor sections. A Ki‐67‐based index quantifying the degree of tumor proliferation was considered appropriate for the comparison based on the obtained cluster characteristics. Results The clustering resulted in one class with low diffusion and high perfusion and another with slightly higher diffusion and low perfusion. Strong agreement was found between tumor subregions identified by clustering and subregions identified by histological analysis, both regarding size and spatial agreement. Neither nor spatial information had substantial effects on the clustering results. Conclusions The results of this study show that IVIM parameter maps can be used to identify tumor subregions using a data‐driven framework based on Gaussian mixture models. In the studied tumor model, the obtained subregions showed agreement with proliferative activity.
    Type of Medium: Online Resource
    ISSN: 0740-3194 , 1522-2594
    URL: Issue
    URL: Article
    DOI: 10.1002/mrm.v82.4
    DOI: 10.1002/mrm.27820
    Language: English
    Publisher: Wiley
    Publication Date: 2019
    detail.hit.zdb_id: 605774-3
    detail.hit.zdb_id: 1493786-4
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  • 7
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    Signal drift in diffusion MRI of the brain: effects on intravoxel incoherent motion parameter estimates
    Springer Science and Business Media LLC ; 2024
    In:  Magnetic Resonance Materials in Physics, Biology and Medicine
    Details
    In: Magnetic Resonance Materials in Physics, Biology and Medicine, Springer Science and Business Media LLC
    Abstract: Signal drift has been put forward as one of the fundamental confounding factors in diffusion MRI (dMRI) of the brain. This study characterizes signal drift in dMRI of the brain, evaluates correction methods, and exemplifies its impact on parameter estimation for three intravoxel incoherent motion (IVIM) protocols. Materials and methods dMRI of the brain was acquired in ten healthy subjects using protocols designed to enable retrospective characterization and correction of signal drift. All scans were acquired twice for repeatability analysis. Three temporal polynomial correction methods were evaluated: (1) global, (2) voxelwise, and (3) spatiotemporal. Effects of acquisition order were simulated using estimated drift fields. Results Signal drift was around 2% per 5 min in the brain as a whole, but reached above 5% per 5 min in the frontal regions. Only correction methods taking spatially varying signal drift into account could achieve effective corrections. Altered acquisition order introduced both systematic changes and differences in repeatability in the presence of signal drift. Discussion Signal drift in dMRI of the brain was found to be spatially varying, calling for correction methods taking this into account. Without proper corrections, choice of protocol can affect dMRI parameter estimates and their repeatability.
    Type of Medium: Online Resource
    ISSN: 1352-8661
    URL: Article
    DOI: 10.1007/s10334-024-01183-6
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2024
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  • 8
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    Radioembolization Versus Bland Embolization for Hepatic Metastases from Small Intestinal Neuroendocrine Tumors: Short‐Term Results of a Randomized Clinical Trial
    Wiley ; 2018
    In:  World Journal of Surgery Vol. 42, No. 2 ( 2018-02), p. 506-513
    Details
    In: World Journal of Surgery, Wiley, Vol. 42, No. 2 ( 2018-02), p. 506-513
    Abstract: Radioembolization (RE) with intra‐arterial administration of 90 Y microspheres is a promising technique for the treatment of liver metastases from small intestinal neuroendocrine tumors (SI‐NET) not amenable to surgery or local ablation. However, studies comparing RE to other loco‐regional therapies are lacking. The aim of this randomized study was to compare the therapeutic response and safety after RE and bland hepatic arterial embolization (HAE), and to investigate early therapy‐induced changes with diffusion‐weighted MRI (DWI‐MRI). Methods Eleven patients were included in a prospective randomized controlled pilot study, six assigned to RE and five to HAE. Response according to RECIST 1.1 using MRI or CT at 3 and 6 months post‐treatment was recorded as well as changes in DWI‐MRI parameters after 1 month. Data on biochemical tumor response, toxicity, and side effects were also collected. Results Three months after treatment, all patients in the HAE group showed partial response according to RECIST while none in the RE group did ( p = 0.0022). After 6 months, the response rates were 4/5 (80%) and 2/6 (33%) in the HAE and RE groups, respectively (NS). DWI‐MRI metrics could not predict RECIST response, but lower pretreatment ADC (120–800) and larger ADC (0–800) increase at 1 month were related to larger decrease in tumor diameter when all tumors were counted. Conclusion HAE resulted in significantly higher RECIST response after 3 months, but no difference compared to RE remained after 6 months. These preliminary findings indicate that HAE remains a safe option for the treatment of liver metastases from SI‐NET, and further studies are needed to establish the role of RE and the predictive value of MR‐DWI.
    Type of Medium: Online Resource
    ISSN: 0364-2313 , 1432-2323
    URL: Article
    DOI: 10.1007/s00268-017-4324-9
    Language: English
    Publisher: Wiley
    Publication Date: 2018
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    detail.hit.zdb_id: 1463296-2
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  • 9
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    Comparison of methods for estimation of the intravoxel incoherent motion (IVIM) diffusion coefficient (D) and perfusion fraction (f)
    Springer Science and Business Media LLC ; 2018
    In:  Magnetic Resonance Materials in Physics, Biology and Medicine Vol. 31, No. 6 ( 2018-12), p. 715-723
    Details
    In: Magnetic Resonance Materials in Physics, Biology and Medicine, Springer Science and Business Media LLC, Vol. 31, No. 6 ( 2018-12), p. 715-723
    Type of Medium: Online Resource
    ISSN: 0968-5243 , 1352-8661
    URL: Article
    DOI: 10.1007/s10334-018-0697-5
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2018
    detail.hit.zdb_id: 1502491-X
    detail.hit.zdb_id: 1283133-5
    SSG: 11
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  • 10
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    Effects of bolus injection duration on perfusion estimates in dynamic CT and dynamic susceptibility contrast MRI
    Springer Science and Business Media LLC ; 2022
    In:  Magnetic Resonance Materials in Physics, Biology and Medicine Vol. 36, No. 1 ( 2022-09-17), p. 95-106
    Details
    In: Magnetic Resonance Materials in Physics, Biology and Medicine, Springer Science and Business Media LLC, Vol. 36, No. 1 ( 2022-09-17), p. 95-106
    Abstract: Estimates of cerebral blood flow (CBF) and tissue mean transit time (MTT) have been shown to differ between dynamic CT perfusion (CTP) and dynamic susceptibility contrast MRI (DSC-MRI). This study investigates whether these discrepancies regarding CBF and MTT between CTP and DSC-MRI can be attributed to the different injection durations of these techniques. Five subjects were scanned using CTP and DSC-MRI. Region-wise estimates of CBF, MTT, and cerebral blood volume (CBV) were derived based on oscillatory index regularized singular value decomposition. A parametric model that reproduced the shape of measured time curves and characteristics of resulting perfusion parameter estimates was developed and used to simulate data with injection durations typical for CTP and DSC-MRI for a clinically relevant set of perfusion scenarios and noise levels. In simulations, estimates of CBF/MTT showed larger negative/positive bias and increasing variability for CTP when compared to DSC-MRI, especially for high CBF levels. While noise also affected estimates, at clinically relevant levels, the injection duration effect was larger. There are several methodological differences between CTP and DSC-MRI. The results of this study suggest that the injection duration is among those that can explain differences in estimates of CBF and MTT between these bolus tracking techniques.
    Type of Medium: Online Resource
    ISSN: 1352-8661
    URL: Article
    DOI: 10.1007/s10334-022-01038-y
    Language: English
    Publisher: Springer Science and Business Media LLC
    Publication Date: 2022
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