Publications by authors named "Martijn Froeling"

81 Publications

Quantitative magnetic resonance imaging of the brachial plexus shows specific changes in nerve architecture in chronic inflammatory demyelinating polyneuropathy, multifocal motor neuropathy and motor neuron disease.

Eur J Neurol 2021 May 1. Epub 2021 May 1.

Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands.

Background: The immunological pathophysiologies of chronic inflammatory demyelinating polyneuropathy (CIDP) and multifocal motor neuropathy (MMN) differ considerably, but neither has been elucidated completely. Quantitative magnetic resonance imaging (MRI) techniques such as diffusion tensor imaging, T2 mapping, and fat fraction analysis may indicate in vivo pathophysiological changes in nerve architecture. Our study aimed to systematically study nerve architecture of the brachial plexus in patients with CIDP, MMN, motor neuron disease (MND) and healthy controls using these quantitative MRI techniques.

Methods: We enrolled patients with CIDP (n = 47), MMN (n = 29), MND (n = 40) and healthy controls (n = 10). All patients underwent MRI of the brachial plexus and we obtained diffusion parameters, T2 relaxation times and fat fraction using an automated processing pipeline. We compared these parameters between groups using a univariate general linear model.

Results: Fractional anisotropy was lower in patients with CIDP compared to healthy controls (p < 0.001), patients with MND (p = 0.010) and MMN (p < 0.001). Radial diffusivity was higher in patients with CIDP compared to healthy controls (p = 0.015) and patients with MND (p = 0.001) and MMN (p < 0.001). T2 relaxation time was elevated in patients with CIDP compared to patients with MND (p = 0.023). Fat fraction was lower in patients with CIDP and MMN compared to patients with MND (both p < 0.001).

Conclusion: Our results show that quantitative MRI parameters differ between CIDP, MMN and MND, which may reflect differences in underlying pathophysiological mechanisms.
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http://dx.doi.org/10.1111/ene.14896DOI Listing
May 2021

Quantitative Muscle-MRI Correlates with Histopathology in Skeletal Muscle Biopsies.

J Neuromuscul Dis 2021 Mar 27. Epub 2021 Mar 27.

Department of Neurology, Heimer Institute for Muscle Research, University Hospital Bergmannsheil, Ruhr University Bochum, Bochum, Germany.

Background: Skeletal muscle biopsy is one of the gold standards in the diagnostic workup of muscle disorders. By histopathologic analysis, characteristic features like inflammatory cellular infiltrations, fat and collagen replacement of muscle tissue or structural defects of the myofibers can be detected. In the past years, novel quantitative MRI (qMRI) techniques have been developed to quantify tissue parameters, thus providing a non-invasive diagnostic tool in several myopathies.

Objective: This proof-of-principle study was performed to validate the qMRI-techniques to skeletal muscle biopsy results.

Methods: Ten patients who underwent skeletal muscle biopsy for diagnostic purposes were examined by qMRI. Fat fraction, water T2-time and diffusion parameters were measured in the muscle from which the biopsy was taken. The proportion of fat tissue, the severity of degenerative and inflammatory parameters and the amount of type 1- and type 2- muscle fibers were determined in all biopsy samples. The qMRI-data were then correlated to the histopathological findings.

Results: The amount of fat tissue in skeletal muscle biopsy correlated significantly with the fat fraction derived from the Dixon sequence. The water T2-time, a parameter for tissue edema, correlated with the amount of vacuolar changes of myofibers and endomysial macrophages in the histopathologic analysis. No significant correlations were found for diffusion parameters.

Conclusion: In this proof-of-principle study, qMRI techniques were related to characteristic histopathologic features in neuromuscular disorders. The study provides the basis for further development of qMRI methods in the follow-up of patients with neuromuscular disorders, especially in the context of emerging treatment strategies.
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http://dx.doi.org/10.3233/JND-210641DOI Listing
March 2021

No need to detune transmitters in 32-channel receiver arrays at 7 T.

NMR Biomed 2021 Jun 10;34(6):e4491. Epub 2021 Feb 10.

Department of Radiology, University Medical Center Utrecht, Utrecht, the Netherlands.

Ultrahigh field magnetic resonance imaging facilitates high spatiotemporal resolution that benefits from increasing the number of receiver elements. Because high-density receiver arrays have a relatively small element size compared with the transmitter, a side effect is that such setups cause low flux coupling between the transmitter and receiver. Moreover, when transmitters are designed in a multitransmit configuration, their relative size is much smaller than the sample, reducing coupling to the sample and thereby potentially also the coupling to the receivers. Transmitters are traditionally detuned during reception. In this study, we investigate, for a 32-channel receiver head array at 7 T, if transmitter detuning of a quadrature birdcage or of an eight-channel transmit coil can be omitted without substantially sacrificing signal-to-noise ratio (SNR). The transmit elements are operated once with and once without detuning and, in the latter, the received signals are either merged with the array or excluded for image reconstruction. For each of the three measurements, SNR and 1/g-factor maps are investigated. The tuning of the quadrature and eight-channel transmit coils during signal reception introduced a 10.1% and 6.5% penalty in SNR, respectively, relative to the SNR received with detuned transmitters. When also incorporating the signal of the transmit coils, the SNR was regained to 98.5% or 101.4% for the quadrature and eight-channel coil, respectively, relative to the detuned transmitters, while the 1/g-factor maps improved slightly. For the 32-channel receive coil used the SNR penalty can become negligible when omitting detuning of the transmit coils. This not only simplifies transmit coil designs, potentially increasing their efficiency, but also enables the transmitters to be used as receivers in parallel to the receiver array, thus increasing parallel imaging performance.
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http://dx.doi.org/10.1002/nbm.4491DOI Listing
June 2021

PCA denoising and Wiener deconvolution of P 3D CSI data to enhance effective SNR and improve point spread function.

Magn Reson Med 2021 06 1;85(6):2992-3009. Epub 2021 Feb 1.

Department of Radiology, Imaging Division, University Medical Center Utrecht, Utrecht, The Netherlands.

Purpose: This study evaluates the performance of 2 processing methods, that is, principal component analysis-based denoising and Wiener deconvolution, to enhance the quality of phosphorus 3D chemical shift imaging data.

Methods: Principal component analysis-based denoising increases the SNR while maintaining spectral information. Wiener deconvolution reduces the FWHM of the voxel point spread function, which is increased by Hamming filtering or Hamming-weighted acquisition. The proposed methods are evaluated using simulated and in vivo 3D phosphorus chemical shift imaging data by 1) visual inspection of the spatial signal distribution; 2) SNR calculation of the PCr peak; and 3) fitting of metabolite basis functions.

Results: With the optimal order of processing steps, we show that the effective SNR of in vivo phosphorus 3D chemical shift imaging data can be increased. In simulations, we show we can preserve phosphorus-containing metabolite peaks that had an SNR < 1 before denoising. Furthermore, using Wiener deconvolution, we were able to reduce the FWHM of the voxel point spread function with only partially reintroducing Gibb-ringing artifacts while maintaining the SNR. After data processing, fitting of the phosphorus-containing metabolite signals improved.

Conclusion: In this study, we have shown that principal component analysis-based denoising in combination with regularized Wiener deconvolution allows increasing the effective spectral SNR of in vivo phosphorus 3D chemical shift imaging data, with reduction of the FWHM of the voxel point spread function. Processing increased the effective SNR by at least threefold compared to Hamming weighted acquired data and minimized voxel bleeding. With these methods, fitting of metabolite amplitudes became more robust with decreased fitting residuals.
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http://dx.doi.org/10.1002/mrm.28654DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7986807PMC
June 2021

Quantification of disease progression in spinal muscular atrophy with muscle MRI-a pilot study.

NMR Biomed 2021 Apr 22;34(4):e4473. Epub 2021 Jan 22.

Department of Neurology, UMC Utrecht Brain Center, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands.

Objectives: Quantitative MRI (qMRI) of muscles is a promising tool to measure disease progression or to assess therapeutic effects in neuromuscular diseases. Longitudinal imaging studies are needed to show sensitivity of qMRI in detecting disease progression in spinal muscular atrophy (SMA). In this pilot study we therefore studied one-year changes in quantitative MR parameters in relation to clinical scores.

Methods: We repeated quantitative 3 T MR analysis of thigh muscles and clinical testing one year after baseline in 10 treatment-naïve patients with SMA, 5 with Type 2 (21.6 ± 7.0 years) and 5 with Type 3 (33.4 ± 11.9 years). MR protocol consisted of Dixon, T mapping and diffusion tensor imaging (DTI). The temporal relation of parameters was examined with a mixed model.

Results: We detected a significant increase in fat fraction (baseline, 38.2% SE 0.6; follow-up, 39.5% SE 0.6; +1.3%, p = 0.001) in all muscles. Muscles with moderate to high fat infiltration at baseline show a larger increase over time (+1.6%, p < 0.001). We did not find any changes in DTI parameters except for low fat-infiltration muscles (m. adductor longus and m. biceps femoris (short head)). The T of muscles decreased from 28.2 ms to 28.0 ms (p = 0.07). Muscle strength and motor function scores were not significantly different between follow-up and baseline.

Conclusion: Longitudinal imaging data show slow disease progression in skeletal muscle of the thigh of (young-) adult patients with SMA despite stable strength and motor function scores. Quantitative muscle imaging demonstrates potential as a biomarker for disease activity and monitoring of therapy response.
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http://dx.doi.org/10.1002/nbm.4473DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7988555PMC
April 2021

Post-exercise intramuscular O supply is tightly coupled with a higher proximal-to-distal ATP synthesis rate in human tibialis anterior.

J Physiol 2021 03 13;599(5):1533-1550. Epub 2021 Jan 13.

Department of Medical Imaging/Radiology, Radboud university medical center, Nijmegen, The Netherlands.

Key Points: The post-exercise recovery of phosphocreatine, a measure of the oxidative capacity of muscles, as assessed by P MR spectroscopy, shows a striking increase from distal to proximal along the human tibialis anterior muscle. To investigate why this muscle exhibits a greater oxidative capacity proximally, we tested whether the spatial variation in phosphocreatine recovery rate is related to oxygen supply, muscle fibre type or type of exercise. We revealed that oxygen supply also increases from distal to proximal along the tibialis anterior, and that it strongly correlated with phosphocreatine recovery. Carnosine level, a surrogate measure for muscle fibre type was not different between proximal and distal, and type of exercise did not affect the gradient in phosphocreatine recovery rate. Taken together, the findings of this study suggest that the post-exercise spatial gradients in oxygen supply and phosphocreatine recovery are driven by a higher intrinsic mitochondrial oxidative capacity proximally.

Abstract: Phosphorus magnetic resonance spectroscopy ( P MRS) of human tibialis anterior (TA) revealed a strong proximo-distal gradient in the post-exercise phosphocreatine (PCr) recovery rate constant (k ), a measure of muscle oxidative capacity. The aim of this study was to investigate whether this k gradient is related to O supply, resting phosphorylation potential, muscle fibre type, or type of exercise. Fifteen male volunteers performed continuous isometric ankle dorsiflexion at 30% maximum force until exhaustion. At multiple locations along the TA, we measured the oxidative PCr resynthesis rate (V = k × PCr depletion) by P MRS, the oxyhaemoglobin recovery rate constant (k ) by near infrared spectroscopy, and muscle perfusion with MR intravoxel incoherent motion imaging. The k , k , V and muscle perfusion depended on measurement location (P < 0.001, P < 0.001, P = 0.032 and P = 0.003, respectively), all being greater proximally. The k and muscle perfusion correlated with k (r = 0.956 and r = 0.852, respectively) and V (r = 0.932 and r = 0.985, respectively), the latter reflecting metabolic O consumption. Resting phosphorylation potential (PCr/inorganic phosphate) was also higher proximally (P < 0.001). The surrogate for fibre type, carnosine content measured by H MRS, did not differ between distal and proximal TA (P = 0.884). Performing intermittent exercise to avoid exercise ischaemia, still led to larger k proximally than distally (P = 0.013). In conclusion, the spatial k gradient is strongly associated with the spatial variation in O supply. It cannot be explained by exercise-induced ischaemia nor by fibre type. Our findings suggest it is driven by a higher proximal intrinsic mitochondrial oxidative capacity, apparently to support contractile performance of the TA.
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http://dx.doi.org/10.1113/JP280771DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7986184PMC
March 2021

Evaluation of interrater reliability of different muscle segmentation techniques in diffusion tensor imaging.

NMR Biomed 2021 02 20;34(2):e4430. Epub 2020 Nov 20.

Department of Neurology, BG-University Hospital Bergmannsheil, Ruhr-University Bochum, Bochum, Germany.

Introduction: Muscle diffusion tensor imaging (mDTI) is a quantitative MRI technique that can provide information about muscular microstructure and integrity. Ultrasound and DTI studies have shown intramuscular differences, and therefore separation of different muscles for analysis is essential. The commonly used methods to assess DTI metrics in muscles are manual segmentation and tract-based analysis. Recently methods such as volume-based tractography have been applied to optimize muscle architecture estimation, but can also be used to assess DTI metrics.

Purpose: To evaluate diffusion metrics obtained using three different methods-volume-based tractography, manual segmentation-based analysis and tract-based analysis-with respect to their interrater reliability and their ability to detect intramuscular variance.

Materials And Methods: 30 volunteers underwent an MRI examination in a 3 T scanner using a 16-channel Torso XL coil. Diffusion-weighted images were acquired to obtain DTI metrics. These metrics were evaluated in six thigh muscles using volume-based tractography, manual segmentation and standard tractography. All three methods were performed by two independent raters to assess interrater reliability by ICC analysis and Bland-Altman plots. Ability to assess intramuscular variance was compared using an ANOVA with muscle as a between-subjects factor.

Results: Interrater reliability for all methods was found to be excellent. The highest interrater reliability was found for volume-based tractography (ICC ≥ 0.967). Significant differences for the factor muscle in all examined diffusion parameters were shown in muscles using all methods (main effect p < 0.001).

Conclusions: Diffusion data can be assessed by volume tractography, standard tractography and manual segmentation with high interrater reliability. Each method produces different results for the investigated DTI parameters. Volume-based tractography was superior to conventional manual segmentation and tractography regarding interrater reliability and detection of intramuscular variance, while tract-based analysis showed the lowest coefficients of variation.
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http://dx.doi.org/10.1002/nbm.4430DOI Listing
February 2021

Can sodium MRI be used as a method for mapping of cartilage stiffness?

MAGMA 2021 Jun 12;34(3):327-336. Epub 2020 Nov 12.

Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands.

Objective: Sodium concentration is responsible for (at least part of) the stiffness of articular cartilage due to the osmotic pressure it generates. Therefore, we hypothesized that we could use sodium MRI to approximate the stiffness of cartilage to assess early cartilage degeneration.

Methods: Four human tibial plateaus were retrieved from patients undergoing total knee replacement (TKR), and their cartilage stiffness mapped with indentation testing, after which samples were scanned in a 7 T MRI to determine sodium concentration. The relation of biomechanical parameters to MRI sodium and glycosaminoglycan (GAG) concentration was explored by a linear mixed model.

Results: Weak correlations of GAG concentration with apparent peak modulus (p = 0.0057) and apparent equilibrium modulus (p = 0.0181) were observed and lack of correlation of GAG concentration versus MRI sodium concentration was observed. MRI sodium concentration was not correlated with apparent peak modulus, though a moderate correlation of MRI sodium concentration with permeability was shown (p = 0.0014).

Discussion And Conclusion: Although there was correlation between GAG concentration and cartilage stiffness, this was not similar with sodium concentration as measured by MRI. Thus, if the correlation between MRI sodium imaging and GAG concentration could be resolved, this strategy for assessing cartilage functional quality still holds promise.
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http://dx.doi.org/10.1007/s10334-020-00893-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8154796PMC
June 2021

MRI of Skeletal Muscles in Participants with Type 2 Diabetes with or without Diabetic Polyneuropathy.

Radiology 2020 12 13;297(3):608-619. Epub 2020 Oct 13.

From the Departments of Neurology and International Diabetic Neuropathy Consortium (A.S., K.S.K., H.A.), Clinical Neurophysiology and International Diabetic Neuropathy Consortium (A.G.K.), Clinical Neurophysiology (H.T.), and Neurology (M.V.), Neurologisk Afdeling, Aarhus University Hospital, Nørrebrogade 44, 8000 Aarhus, Denmark; Image Division, Department of Radiology, University Medical Center Utrecht, Utrecht, the Netherlands (L.S., M.F.); and Department of Neurology, BG-University Hospital Bergmannsheil, Ruhr-University Bochum, Bochum, Germany (L.S.).

BackgroundDiabetic polyneuropathy (DPN) is associated with loss of muscle strength. MRI including diffusion-tensor imaging (DTI) may enable detection of muscle abnormalities related to type 2 diabetes mellitus (DM2) and DPN.PurposeTo assess skeletal muscle abnormalities in participants with DM2 with or without DPN by using MRI.Materials and MethodsThis prospective cross-sectional study included participants with DM2 and DPN (DPN positive), participants with DM2 without DPN (DPN negative), and healthy control (HC) participants enrolled between August 2017 and June 2018. Muscle strength at the knee and ankle was determined with isokinetic dynamometry. MRI of the lower extremities included the Dixon sequence, multicomponent T2 mapping, and DTI calculated fat fractions (FFs), T2 relaxation of muscle (T2), fractional anisotropy (FA), and diffusivity (mean, axial, and radial). One-way analysis of variance and Tukey honestly significant difference were applied for comparison between groups, and multivariate regression models were used for association between MRI parameters, nerve conduction, strength, and body mass index (BMI).ResultsTwenty participants with DPN (mean age, 65 years ± 9 [standard deviation]; 70% men; mean BMI, 34 kg/m ± 5), 20 participants without DPN (mean age, 64 years ± 9; 55% men; mean BMI, 30 kg/m ± 6), and 20 HC participants (mean age, 61 years ± 10; 55% men; mean BMI, 27 kg/m ± 5) were enrolled in this study. Muscle strength adjusted for age, sex, and BMI was lower in participants with DPN than in DPN-negative and HC participants in the upper and lower leg (plantar flexors [PF], 62% vs 78% vs 89%; < .001; knee extensors [KE], 73% vs 95% vs 93%; < .001). FF was higher in leg muscle groups of participants with DPN than in DPN-negative and HC participants (PF, 20% vs 10% vs 8%; < .001; KE, 13% vs 8% vs 6%; < .001). T2 was prolonged in leg muscle groups of participants with DPN when compared with HC participants (PF, 33 msec vs 31 msec; < .001; KE, 32 msec vs 31 msec; = .002) and in the lower leg when compared with participants without DPN (PF, 33 msec vs 32 msec; = .03). In multivariate regression models, strength was associated with FA ( = -0.0004), T2 ( = -0.03 msec), and FF ( = -0.1%) at thigh level ( < .001). Furthermore, FA ( = -0.007), T2 ( = -0.53 msec), and FF ( = -4.0%) were associated with nerve conduction at calf level ( < .001).ConclusionMRI of leg muscle groups revealed fat accumulation, differences in water composition, and structural changes in participants with type 2 diabetes mellitus and neuropathy. Abnormalities were most pronounced in the plantar flexors.© RSNA, 2020See also the editorial by Sneag and Tan in this issue.
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http://dx.doi.org/10.1148/radiol.2020192647DOI Listing
December 2020

The YOUth cohort study: MRI protocol and test-retest reliability in adults.

Dev Cogn Neurosci 2020 10 8;45:100816. Epub 2020 Jul 8.

UMCU Brain Center, University Medical Center Utrecht, University Utrecht, Utrecht, the Netherlands. Electronic address:

The YOUth cohort study is a unique longitudinal study on brain development in the general population. As part of the YOUth study, 2000 children will be included at 8, 9 or 10 years of age and planned to return every three years during adolescence. Magnetic resonance imaging (MRI) brain scans are collected, including structural T1-weighted imaging, diffusion-weighted imaging (DWI), resting-state functional MRI and task-based functional MRI. Here, we provide a comprehensive report of the MR acquisition in YOUth Child & Adolescent including the test-retest reliability of brain measures derived from each type of scan. To measure test-retest reliability, 17 adults were scanned twice with a week between sessions using the full YOUth MRI protocol. Intraclass correlation coefficients were calculated to quantify reliability. Global brain measures derived from structural T1-weighted and DWI scans were reliable. Resting-state functional connectivity was moderately reliable, as well as functional brain measures for both the inhibition task (stop versus go) and the emotion task (face versus house). Our results complement previous studies by presenting reliability results of regional brain measures collected with different MRI modalities. YOUth facilitates data sharing and aims for reliable and high-quality data. Here we show that using the state-of-the art YOUth MRI protocol brain measures can be estimated reliably.
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http://dx.doi.org/10.1016/j.dcn.2020.100816DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7365929PMC
October 2020

Proton nuclear magnetic resonance J-spectroscopy of phantoms containing brain metabolites on a portable 0.05 T MRI scanner.

J Magn Reson 2020 11 24;320:106834. Epub 2020 Sep 24.

C. J. Gorter Center for High Field MRI, Department of Radiology, Leiden University Medical Center, Leiden, the Netherlands.

We examined approaches for obtaining H NMR spectra of brain metabolites on a low-field (B = 0.05 T) portable MRI scanner, which was developed in our laboratory with the aim of bringing cost-effective radiological services to populations in underserved, remote regions. The low static magnetic field B dictates low signal to noise ratio for metabolites in the mM concentration range, and results in an overall spectral region for the H resonances of these metabolites narrower than the linewidth obtainable in our scanner. The narrow spectral range also precludes the possibility of suppressing the large contribution of the water resonance at the acquisition stage. We used a spectroscopic Carr-Purcell-Meiboom-Gill (CPMG) sequence to acquire multiecho data from solutions of J-coupled brain metabolites, focusing on lactic acid, a metabolite whose concentration is negligible in the healthy brain and increases significantly in several disease conditions. The J spectra we obtained for lactate from the Fourier transformation of the multiecho data are spectrally well-resolved for a range of echo spacing values. We show that the J spectra at different echo spacings fit well with simulations of the evolution of echo train signal of the lactate under the same conditions. Applying a J-refocused variant of the CPMG sequence, the J modulation of the echo decay is removed, providing a way for subtracting the large contribution of the non-modulated component in the J spectrum in conditions where notching it using post-processing methods is impossible. We also demonstrate by means of experimental data and simulations that in our experimental conditions, J-spectra of other prominent brain metabolites, such as the neurotransmitter glutamate, do not yield discernible peaks and only contribute to a broad peak at zero frequency.
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http://dx.doi.org/10.1016/j.jmr.2020.106834DOI Listing
November 2020

Quantitative assessment of brachial plexus MRI for the diagnosis of chronic inflammatory neuropathies.

J Neurol 2021 Mar 23;268(3):978-988. Epub 2020 Sep 23.

Department of Neurology and Neurosurgery, University Medical Center Utrecht Brain Center, Utrecht, The Netherlands.

Objective: This study aimed at developing a quantitative approach to assess abnormalities on MRI of the brachial plexus and the cervical roots in patients with chronic inflammatory demyelinating polyneuropathy (CIDP) and multifocal motor neuropathy (MMN) and to evaluate interrater reliability and its diagnostic value.

Methods: We performed a cross-sectional study in 50 patients with CIDP, 31 with MMN and 42 disease controls. We systematically measured cervical nerve root sizes on MRI bilaterally (C5, C6, C7) in the coronal [diameter (mm)] and sagittal planes [area (mm)], next to the ganglion (G) and 1 cm distal from the ganglion (G). We determined their diagnostic value using a multivariate binary logistic model and ROC analysis. In addition, we evaluated intra- and interrater reliability.

Results: Nerve root size was larger in patients with CIDP and MMN compared to controls at all predetermined anatomical sites. We found that nerve root diameters in the coronal plane had optimal reliability (intrarater ICC 0.55-0.87; interrater ICC 0.65-0.90). AUC was 0.78 (95% CI 0.69-0.87) for measurements at G and 0.81 (95% CI 0.72-0.91) for measurements at G. Importantly, our quantitative assessment of brachial plexus MRI identified an additional 10% of patients that showed response to treatment, but were missed by nerve conduction (NCS) and nerve ultrasound studies.

Conclusion: Our study showed that a quantitative assessment of brachial plexus MRI is reliable. MRI can serve as an important additional diagnostic tool to identify treatment-responsive patients, complementary to NCS and nerve ultrasound.
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http://dx.doi.org/10.1007/s00415-020-10232-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7914242PMC
March 2021

Validation of multiparametric MRI by histopathology after nephrectomy: a case study.

MAGMA 2021 Jun 20;34(3):377-387. Epub 2020 Sep 20.

Department of Nephrology and Hypertension, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands.

Objectives: Renal multiparametric MRI (mpMRI) is a promising tool to monitor renal allograft health to enable timely treatment of chronic allograft nephropathy. This study aims to validate mpMRI by whole-kidney histology following transplantectomy.

Materials And Methods: A patient with kidney transplant failure underwent mpMRI prior to transplantectomy. The mpMRI included blood oxygenation level-dependent (BOLD) MRI, T and T mapping, diffusion-weighted imaging (DWI), 2D phase contrast (2DPC) and arterial spin labeling (ASL). Parenchymal mpMRI measures were compared to normative values obtained in 19 healthy controls. Differences were expressed in standard deviations (SD) of normative values. The mpMRI measures were compared qualitatively to histology.

Results: The mpMRI showed a heterogeneous parenchyma consistent with extensive interstitial hemorrhage on histology. A global increase in T (+ 3.0 SD) and restricted diffusivity (- 3.6 SD) were consistent with inflammation and fibrosis. Decreased T (- 1.8 SD) indicated fibrosis or hemorrhage. ASL showed diminished cortical perfusion (- 2.9 SD) with patent proximal arteries. 2DPC revealed a 69% decrease in renal perfusion. Histological evaluation showed a dense inflammatory infiltrate and fibrotic changes, consistent with mpMRI results. Most interlobular arteries were obliterated while proximal arteries were patent, consistent with ASL findings.

Discussion: mpMRI findings correlated well with histology both globally as well as locally.
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http://dx.doi.org/10.1007/s10334-020-00887-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8154819PMC
June 2021

Marathon running transiently depletes the myocardial lipid pool.

Physiol Rep 2020 09;8(17):e14543

Department of Radiology and Nuclear Medicine, Amsterdam University Medical Centers, University of Amsterdam, Amsterdam, The Netherlands.

Lipids, stored as intracellular triacylglycerol droplets within the myocardium, serve as an important source of energy, particularly in times of prolonged increased energy expenditure. In only a few studies, the acute effects of exercise on such ectopic myocardial lipid storage were investigated. We studied the dynamic behavior of the myocardial lipid pool in response to completing the 2017 Amsterdam Marathon using proton magnetic resonance (MR) spectroscopy ( H-MRS). We hypothesized that the prolonged increased myocardial energy demand of running a marathon could shift the balance of myocardial triacylglycerol turnover from triacylglycerol synthesis toward lipolysis and mitochondrial fatty acid β-oxidation, and decrease the myocardial lipid pool. We employed two 3 Tesla MR systems in parallel to noninvasively examine endurance-trained healthy men (n = 8; age 50.7 [50.1-52.7] y) at 1 week prior (baseline), <6 hr after finishing the marathon (post-marathon), and 2 weeks thereafter (recovery). Exercise intensity was 89 ± 6% of the age-predicted maximal heart rate, with a finish time of 3:56 [3:37-4:42] h:min. Myocardial lipid content was 0.66 [0.58-0.87]% of the total myocardial water signal at baseline, was lower post-marathon (0.47 [0.41-0.63]% of the total myocardial water signal), and had restored to 0.55 [0.49-0.83]% of the total myocardial water signal at recovery, representing a transient marathon running-induced depletion of 29 ± 24% (p = .04). The magnitude of this myocardial lipid pool depletion did not correlate with exercise intensity (r = -0.39; p = .39), nor with marathon finishing time (ρ = 0.57; p = .15). Our data show that prolonged high-intensity exercise can induce a transient depletion of the myocardial lipid pool, reinforcing the dynamic nature of ectopic triacylglycerol storage under real-life conditions of extreme endurance exercise.
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http://dx.doi.org/10.14814/phy2.14543DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7460059PMC
September 2020

Multi-parametric MR in Becker muscular dystrophy patients.

NMR Biomed 2020 11 5;33(11):e4385. Epub 2020 Aug 5.

C.J. Gorter Center, Department of Radiology, Leiden University Medical Center, Leiden, The Netherlands.

Quantitative MRI and MRS of muscle are increasingly being used to measure individual pathophysiological processes in Becker muscular dystrophy (BMD). In particular, muscle fat fraction was shown to be highly associated with functional tests in BMD. However, the muscle strength per unit of contractile cross-sectional area is lower in patients with BMD compared with healthy controls. This suggests that the quality of the non-fat-replaced (NFR) muscle tissue is lower than in healthy controls. Consequently, a measure that reflects changes in muscle tissue itself is needed. Here, we explore the potential of water T relaxation times, diffusion parameters and phosphorus metabolic indices as early disease markers in patients with BMD. For this purpose, we examined these measures in fat-replaced (FR) and NFR lower leg muscles in patients with BMD and compared these values with those in healthy controls. Quantitative proton MRI (three-point Dixon, multi-spin-echo and diffusion-weighted spin-echo echo planar imaging) and 2D chemical shift imaging P MRS data were acquired in 24 patients with BMD (age 18.8-66.2 years) and 13 healthy controls (age 21.3-63.6 years). Muscle fat fractions, phosphorus metabolic indices, and averages and standard deviations (SDs) of the water T relaxation times and diffusion tensor imaging (DTI) parameters were assessed in six individual leg muscles. Phosphodiester levels were increased in the NFR and FR tibialis anterior, FR peroneus and FR gastrocnemius lateralis muscles. No clear pattern was visible for the other metabolic indices. Increased T SD was found in the majority of FR muscles compared with NFR and healthy control muscles. No differences in average water T relaxation times or DTI indices were found between groups. Overall, our results indicate that primarily muscles that are further along in the disease process showed increases in T heterogeneity and changes in some metabolic indices. No clear differences were found for the DTI indices between groups.
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http://dx.doi.org/10.1002/nbm.4385DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7687231PMC
November 2020

Spherical deconvolution with tissue-specific response functions and multi-shell diffusion MRI to estimate multiple fiber orientation distributions (mFODs).

Neuroimage 2020 11 1;222:117206. Epub 2020 Aug 1.

PROVIDI Lab, Image Sciences Institute, UMC Utrecht, Heidelberglaan 100, 3584CX, Utrecht, the Netherlands.

In diffusion MRI, spherical deconvolution approaches can estimate local white matter (WM) fiber orientation distributions (FOD) which can be used to produce fiber tractography reconstructions. The applicability of spherical deconvolution to gray matter (GM), however, is still limited, despite its critical role as start/endpoint of WM fiber pathways. The advent of multi-shell diffusion MRI data offers additional contrast to model the GM signal but, to date, only isotropic models have been applied to GM. Evidence from both histology and high-resolution diffusion MRI studies suggests a marked anisotropic character of the diffusion process in GM, which could be exploited to improve the description of the cortical organization. In this study, we investigated whether performing spherical deconvolution with tissue specific models of both WM and GM can improve the characterization of the latter while retaining state-of-the-art performances in WM. To this end, we developed a framework able to simultaneously accommodate multiple anisotropic response functions to estimate multiple, tissue-specific, fiber orientation distributions (mFODs). As proof of principle, we used the diffusion kurtosis imaging model to represent the WM signal, and the neurite orientation dispersion and density imaging (NODDI) model to represent the GM signal. The feasibility of the proposed approach is shown with numerical simulations and with data from the Human Connectome Project (HCP). The performance of our method is compared to the current state of the art, multi-shell constrained spherical deconvolution (MSCSD). The simulations show that with our new method we can accurately estimate a mixture of two FODs at SNR≥50. With HCP data, the proposed method was able to reconstruct both tangentially and radially oriented FODs in GM, and performed comparably well to MSCSD in computing FODs in WM. When performing fiber tractography, the trajectories reconstructed with mFODs reached the cortex with more spatial continuity and for a longer distance as compared to MSCSD and allowed to reconstruct short trajectories tangential to the cortical folding. In conclusion, we demonstrated that our proposed method allows to perform spherical deconvolution of multiple anisotropic response functions, specifically improving the performances of spherical deconvolution in GM tissue.
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http://dx.doi.org/10.1016/j.neuroimage.2020.117206DOI Listing
November 2020

Untangling the diffusion signal using the phasor transform.

NMR Biomed 2020 12 23;33(12):e4372. Epub 2020 Jul 23.

Center for Image Sciences, UMC Utrecht, Utrecht, the Netherlands.

Separating the decay signal from diffusion-weighted scans into two or more components can be challenging. The phasor technique is well established in the field of optical microscopy for visualization and separation of fluorescent dyes with different lifetimes. The use of the phasor technique for separation of diffusion-weighted decay signals was recently proposed. In this study, we investigate the added value of this technique for fitting decay models and visualization of decay rates. Phasor visualization was performed in five glioblastoma patients. Using simulations, the influence of incorrect diffusivity values and of the number of b-values on fitting a three-component model with fixed diffusivities (dubbed "unmixing") was investigated for both a phasor-based fit and a linear least squares (LLS) fit. Phasor-based intravoxel incoherent motion (IVIM) fitting was compared with nonlinear least squares (NLLS) and segmented fitting (SF) methods in terms of accuracy and precision. The distributions of the parameter estimates of simulated data were compared with those obtained in a healthy volunteer. In the phasor visualizations of two glioblastoma patients, a cluster of points was observed that was not seen in healthy volunteers. The identified cluster roughly corresponded to the enhanced edge region of the tumor of two glioblastoma patients visible on fluid-attenuated inversion recovery (FLAIR) images. For fitting decay models the usefulness of the phasor transform is less pronounced, but the additional knowledge gained from the geometrical configuration of phasor space can aid fitting routines. This has led to slightly improved fitting results for the IVIM model: phasor-based fitting yielded parameter maps with higher precision than the NLLS and SF methods for parameters f and D (interquartile range [IQR] for f: NLLS 27, SF 12, phasor 5.7%; IQR for D: NLLS 0.28, SF 0.18, phasor 0.10 μm /s). For unmixing, LLS fitting slightly but consistently outperformed phasor-based fitting in all of the tested scenarios.
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http://dx.doi.org/10.1002/nbm.4372DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7685171PMC
December 2020

Quantitative MRI of skeletal muscle in a cross-sectional cohort of patients with spinal muscular atrophy types 2 and 3.

NMR Biomed 2020 10 18;33(10):e4357. Epub 2020 Jul 18.

Department of Radiology, University Medical Center Utrecht, Utrecht University, the Netherlands.

The aim of this study was to document upper leg involvement in spinal muscular atrophy (SMA) with quantitative MRI (qMRI) in a cross-sectional cohort of patients of varying type, disease severity and age. Thirty-one patients with SMA types 2 and 3 (aged 29.6 [7.6-73.9] years) and 20 healthy controls (aged 37.9 [17.7-71.6] years) were evaluated in a 3 T MRI with a protocol consisting of DIXON, T2 mapping and diffusion tensor imaging (DTI). qMRI measures were compared with clinical scores of motor function (Hammersmith Functional Motor Scale Expanded [HFMSE]) and muscle strength. Patients exhibited an increased fat fraction and fractional anisotropy (FA), and decreased mean diffusivity (MD) and T2 compared with controls (all P < .001). DTI parameters FA and MD manifest stronger effects than can be accounted for the effect of fatty replacement. Fat fraction, FA and MD show moderate correlation with muscle strength and motor function: FA is negatively associated with HFMSE and Medical Research Council sum score (τ = -0.56 and -0.59; both P < .001) whereas for fat fraction values are τ = -0.50 and -0.58, respectively (both P < .001). This study shows that DTI parameters correlate with muscle strength and motor function. DTI findings indirectly indicate cell atrophy and act as a measure independently of fat fraction. Combined these data suggest the potential of muscle DTI in monitoring disease progression and to study SMA pathogenesis in muscle.
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http://dx.doi.org/10.1002/nbm.4357DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7507182PMC
October 2020

Diffusion tensor imaging of the anterior cruciate ligament graft following reconstruction: a longitudinal study.

Eur Radiol 2020 Dec 14;30(12):6673-6684. Epub 2020 Jul 14.

Department of Radiology, University Medical Center Utrecht, Heidelberglaan 100, 3584 CX, Utrecht, The Netherlands.

Objective: To longitudinally monitor remodeling of human autograft following anterior cruciate ligament (ACL) reconstruction with DTI.

Methods: Twenty-eight patients underwent DTI follow-up at 3, 8, and 14 months after clinically successful ACL reconstruction with tendon autograft. Among these, 18 patients had a concomitant lateral extra-articular procedure (LET). DTI data from 7 healthy volunteers was also obtained. Diffusion parameters (fractional anisotropy, FA; mean diffusivity, MD; axial diffusivity, AD; and radial diffusivity, RD) were evaluated within the fiber tractography volumes of the ACL graft and posterior cruciate ligament (PCL) in all patients. Data were analyzed using a linear mixed-effects model with post hoc testing using Bonferroni-Holm correction for multiple testing. The effect of additional LET was studied.

Results: The ACL graft showed a significant decrease of FA over time (F = 4.00, p = 0.025), while the diffusivities did not significantly change over time. For PCL there were no significant DTI changes over time. A different evolution over time between patients with and without LET was noted for all diffusivity values of the ACL graft with reduced AD values in patients with LET at 8 months postoperatively (p = 0.048; adjusted p = 0.387). DTI metrics of the ACL graft differed largely from both native ACL and tendon at 14 months postoperatively.

Conclusion: Our study has shown the potential of DTI to longitudinally monitor the remodeling process in human ACL reconstruction. DTI analysis indicates that graft remodeling is incomplete at 14 months postoperatively.

Key Points: • DTI can be used to longitudinally monitor the remodeling process in human ACL reconstruction. • DTI analysis indicates that autograft remodeling is incomplete at 14 months postoperatively. • DTI may be helpful for evaluating new ACL treatments.
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http://dx.doi.org/10.1007/s00330-020-07051-wDOI Listing
December 2020

Diffusion tensor imaging reveals changes in non-fat infiltrated muscles in late onset Pompe disease.

Muscle Nerve 2020 10 31;62(4):541-549. Epub 2020 Jul 31.

Department of Neurology, Heimer Institute for Muscle Research, BG-University Hospital Bergmannsheil, Ruhr-University Bochum, Bochum, Germany.

MRI is a helpful tool for monitoring disease progression in late-onset Pompe disease (LOPD). Our study aimed to evaluate if muscle diffusion tensor imaging (mDTI) shows alterations in muscles of LOPD patients with <10% fat-fraction. We evaluated 6 thigh and 7 calf muscles (both legs) of 18 LOPD and 29 healthy controls (HC) with muscle diffusion tensor imaging (mDTI), T1w, and mDixonquant sequences in a 3T MRI scanner. The quantitative mDTI-values axial diffusivity (λ ), mean diffusivity (MD), radial diffusivity (RD), and fractional anisotropy (FA) as well as fat-fraction were analyzed. 6-Minute Walk Test (6-MWT) data were correlated to diffusion metrics. We found that mDTI showed significant differences between LOPD and HC in diffusion parameters (P < .05). Thigh muscles with <10% fat-fraction showed significant differences in MD, RD, and λ . MD positively correlated with 6-MWT (P = .06). To conclude, mDTI reveals diffusion restrictions in muscles of LOPD with and without fat-infiltration and reflects structural changes prior to fatty degeneration.
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http://dx.doi.org/10.1002/mus.27021DOI Listing
October 2020

T2* mapping in an equine articular groove model: Visualizing changes in collagen orientation.

J Orthop Res 2020 11 10;38(11):2383-2389. Epub 2020 Jun 10.

Department of Radiology, University Medical Center Utrecht, Utrecht, The Netherlands.

T2* mapping is promising for the evaluation of articular cartilage collagen. In this work, a groove model in a large animal is used as a model for posttraumatic arthritis. We hypothesized that T2* mapping could be employed to differentiate between healthy and (subtly) damaged cartilage. Eight carpal joints were obtained from four adult Shetland ponies that had been included in the groove study. In this model, grooves were surgically created on the proximal articular surface of the intermediate carpal bone (radiocarpal joint) and the radial facet of the third carpal bone (middle carpal joint) by either coarse disruption or sharp incision. After 9 months, T2* mapping of the entire carpal joint was carried out on a 7.0-T whole-body magnetic resonance imaging (MRI) scanner by means of a gradient echo multi-echo sequence. Afterwards, assessment of collagen orientation was carried out based on Picrosirius Red-stained histological sections, visualized by polarized light microscopy (PLM). The average T2* relaxation time in grooved samples was lower than in contralateral control sites. Opposite to the grooved areas, the "kissing sites" had a higher average T2* relaxation time than the grooved sites. PLM showed mild changes in orientation of the collagen fibers, particularly around blunt grooves. This work shows that T2* relaxation times are different in healthy cartilage vs (early) damaged cartilage, as induced by the equine groove model. Additionally, the average T2* relaxation times are different in kissing lesions vs the grooved sites.
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http://dx.doi.org/10.1002/jor.24764DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7687204PMC
November 2020

Vasogenic edema versus neuroplasticity as neural correlates of hippocampal volume increase following electroconvulsive therapy.

Brain Stimul 2020 Jul - Aug;13(4):1080-1086. Epub 2020 Apr 29.

University Groningen, University Medical Center Groningen, Department of Biomedical Sciences of Cells and Systems, Groningen, the Netherlands.

Background: Volume increases of the hippocampus after electroconvulsive therapy (ECT) are a robust finding, pointing into the direction of neurogenesis. However, such volumetric increases could also be explained by edema and/or neuroplastic changes (such as angiogenesis).

Objectives: If edema explains the volume increase of the hippocampus we hypothesize it would lead to increased mean diffusivity (MD). If neuroplastic would explain the volume increase, it would lead to decreased MD. To investigate angiogenesis as explanation we studied the perfusion fraction f and the pseudodiffusion component D∗ obtained from intravoxel incoherent motion (IVIM) data, and relative perfusion changes obtained from arterial spin labelling (ASL) data.

Methods: Using ultra-high field (7 tesla) MRI we acquired IVIM and ASL data. We compared MD, f, D∗ and ASL values for both hippocampi in 21 patients (before and after 10 ECT sessions) and 8 healthy controls (without ECT) in a linear mixed model adjusting for age and gender.

Results: We found a significant decrease in MD (which was absent in the healthy controls) in the left and right hippocampus (t = -3.98, p < 0.001). In addition, a decrease in f (t = -4.61, p < 0.001, but not in controls) and no differences in D∗ or ASL perfusion values (both p > 0.05) were found.

Conclusions: The decrease in MD in perfusion fraction f suggest that formation of edema nor angiogenesis are responsible for the ECT-induced volume increases in the hippocampus. Also, it supports the hypothesis that hippocampal volume increases might be due to neuroplastic changes.
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http://dx.doi.org/10.1016/j.brs.2020.04.017DOI Listing
December 2020

T relaxation-time mapping in healthy and diseased skeletal muscle using extended phase graph algorithms.

Magn Reson Med 2020 11 19;84(5):2656-2670. Epub 2020 Apr 19.

Department of Radiology, University Medical Center Utrecht, Utrecht, the Netherlands.

Purpose: Multi-echo spin-echo (MSE) transverse relaxometry mapping using multi-component models is used to study disease activity in neuromuscular disease by assessing the T of the myocytic component (T ). Current extended phase graph algorithms are not optimized for fat fractions above 50% and the effects of inaccuracies in the T calibration remain unexplored. Hence, we aimed to improve the performance of extended phase graph fitting methods over a large range of fat fractions, by including the slice-selection flip angle profile, a through-plane chemical-shift displacement correction, and optimized calibration of T .

Methods: Simulation experiments were used to study the influence of the slice flip-angle profile with chemical-shift and T estimations. Next, in vivo data from four neuromuscular disease cohorts were studied for different T calibration methods and T estimations.

Results: Excluding slice flip-angle profiles or chemical-shift displacement resulted in a bias in T up to 10 ms. Furthermore, a wrongly calibrated T caused a bias of up to 4 ms in T . For the in vivo data, one-component calibration led to a lower T compared with a two-component method, and T decreased with increasing fat fractions.

Conclusion: In vivo data showed a decline in T for increasing fat fractions, which has important implications for clinical studies, especially in multicenter settings. We recommend using an extended phase graph-based model for fitting T from MSE sequences with two-component T calibration. Moreover, we recommend including the slice flip-angle profile in the model with correction for through-plane chemical-shift displacements.
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http://dx.doi.org/10.1002/mrm.28290DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7496817PMC
November 2020

Multiparametric Renal MRI: An Intrasubject Test-Retest Repeatability Study.

J Magn Reson Imaging 2021 03 16;53(3):859-873. Epub 2020 Apr 16.

Department of Radiology, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands.

Background: Renal multiparametric magnetic resonance imaging (MRI) is a promising tool for diagnosis, prognosis, and treatment monitoring in kidney disease.

Purpose: To determine intrasubject test-retest repeatability of renal MRI measurements.

Study Type: Prospective.

Population: Nineteen healthy subjects aged over 40 years.

Field Strength/sequences: T and T mapping, R * mapping or blood oxygenation level-dependent (BOLD) MRI, diffusion tensor imaging (DTI), and intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI), 2D phase contrast, arterial spin labelling (ASL), dynamic contrast enhanced (DCE) MRI, and quantitative Dixon for fat quantification at 3T.

Assessment: Subjects were scanned twice with ~1 week between visits. Total scan time was ~1 hour. Postprocessing included motion correction, semiautomated segmentation of cortex and medulla, and fitting of the appropriate signal model.

Statistical Test: To assess the repeatability, a Bland-Altman analysis was performed and coefficients of variation (CoVs), repeatability coefficients, and intraclass correlation coefficients were calculated.

Results: CoVs for relaxometry (T , T , R */BOLD) were below 6.1%, with the lowest CoVs for T maps and highest for R */BOLD. CoVs for all diffusion analyses were below 7.2%, except for perfusion fraction (F ), with CoVs ranging from 18-24%. The CoV for renal sinus fat volume and percentage were both around 9%. Perfusion measurements were most repeatable with ASL (cortical perfusion only) and 2D phase contrast with CoVs of 10% and 13%, respectively. DCE perfusion had a CoV of 16%, while single kidney glomerular filtration rate (GFR) had a CoV of 13%. Repeatability coefficients (RCs) ranged from 7.7-87% (lowest/highest values for medullary mean diffusivity and cortical F , respectively) and intraclass correlation coefficients (ICCs) ranged from -0.01 to 0.98 (lowest/highest values for cortical F and renal sinus fat volume, respectively).

Data Conclusion: CoVs of most MRI measures of renal function and structure (with the exception of F and perfusion as measured by DCE) were below 13%, which is comparable to standard clinical tests in nephrology.

Level Of Evidence: 2 TECHNICAL EFFICACY: Stage 1.
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http://dx.doi.org/10.1002/jmri.27167DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7891585PMC
March 2021

Diffusion tensor imaging of the anterior cruciate ligament following primary repair with internal bracing: A longitudinal study.

J Orthop Res 2021 Jun 15;39(6):1318-1330. Epub 2020 Apr 15.

Icometrix, Leuven, Belgium.

Diffusion tensor imaging (DTI) provides information about tissue microstructure and its degree of organization by quantifying water diffusion. We aimed to monitor longitudinal changes in DTI parameters (fractional isotropy, FA; mean diffusivity, MD; axial diffusivity, AD; radial diffusivity, RD) of the anterior cruciate ligament (ACL) following primary repair with internal bracing (IBLA). Fourteen patients undergoing IBLA were enrolled prospectively and scheduled for clinical follow-up, including instrumented laxity testing, and DTI at 3, 6, 12, and 24 months postoperatively. DTI was also performed in seven healthy subjects. Fiber tractography was used for 3D segmentation of the whole ACL volume, from which median DTI parameters were calculated. The posterior cruciate ligament (PCL) served as a control. Longitudinal DTI changes were assessed using a linear mixed model, and repeated measures correlations were calculated between DTI parameters and clinical laxity tests. At follow-up, thirteen patients had a stable knee and one patient sustained an ACL rerupture after 12 months postoperatively. The ACL repair showed a significant decrease of FA within the first 12 months after surgery, followed by stable FA values thereafter, while ACL diffusivities decreased over time returning towards normal values at 24 months postoperatively. For PCL there were no significant DTI changes over time. There was a significant correlation between ACL FA and laxity tests (r = -0.42, P = .017). This study has shown the potential of DTI to longitudinally monitor diffusion changes in the ACL following IBLA. The DTI findings suggest that healing of the ACL repair is incomplete at 24 months postoperatively.
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http://dx.doi.org/10.1002/jor.24684DOI Listing
June 2021

Quantitative MRI Reveals Microstructural Changes in the Upper Leg Muscles After Running a Marathon.

J Magn Reson Imaging 2020 08 7;52(2):407-417. Epub 2020 Mar 7.

Amsterdam University Medical Centers, University of Amsterdam, Department of Biomedical Engineering and Physics, Amsterdam Movement Sciences, Amsterdam, Netherlands.

Background: The majority of sports-related injuries involve skeletal muscle. Unlike acute trauma, which is often caused by a single traumatic event leading to acute symptoms, exercise-induced microtrauma may remain subclinical and difficult to detect. Therefore, novel methods to detect and localize subclinical exercise-induced muscle microtrauma are desirable.

Purpose: To assess acute and delayed microstructural changes in upper leg muscles with multiparametric quantitative MRI after running a marathon.

Study Type: Longitudinal; 1-week prior, 24-48 hours postmarathon and 2-week follow-up POPULATION: Eleven men participants (age: 47-68 years).

Field Strength/sequence: Spin-echo echo planar imaging (SE-EPI) with diffusion weighting, multispin echo, Dixon, and fat-suppressed turbo spin-echo (TSE) sequences at 3T. MR datasets and creatine kinase (CK) concentrations were obtained at three timepoints.

Assessment: Diffusion parameters, perfusion fractions, and quantitative (q)T values were determined for hamstring and quadriceps muscles, TSE images were scored for acute injury. The vastus medialis and biceps femoris long head muscles were divided and analyzed in five segments to assess local damage.

Statistical Tests: Differences between timepoints in MR parameters were assessed with a multilevel linear mixed model and in CK concentrations with a Friedman test. Mean diffusivity (MD) and qT for whole muscle and muscle segments were compared using a multivariate analysis of covariance (MANCOVA).

Results: CK concentrations were elevated (1194 U/L [166-3906], P < 0.001) at 24-48 hours postmarathon and returned to premarathon values (323 U/L [56-2216]) at 2-week follow-up. Most of the MRI diffusion indices in muscles without acute injury changed at 24-48 hours postmarathon and returned to premarathon values at follow-up (MD, RD, and λ3; P < 0.006). qT values (P = 0.003) and perfusion fractions (P = 0.003) were higher at baseline compared to follow-up. Local assessments of MD and qT revealed more pronounced changes than whole muscle assessment (2-3-fold; P < 0.01).

Data Conclusion: Marathon running-induced microtrauma was detected with MRI in individual whole upper leg muscles and even more pronounced on local segments.

Level Of Evidence: 2 TECHNICAL EFFICACY STAGE: 3 J. Magn. Reson. Imaging 2020;52:407-417.
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http://dx.doi.org/10.1002/jmri.27106DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7496541PMC
August 2020

Low interrater reliability of brachial plexus MRI in chronic inflammatory neuropathies.

Muscle Nerve 2020 06 21;61(6):779-783. Epub 2020 Feb 21.

Department of Neurology and Neurosurgery, University Medical Center Utrecht Brain Center, Utrecht University, The Netherlands.

Introduction: Magnetic resonance imaging of the brachial plexus shows nerve thickening in approximately half of the patients with chronic inflammatory demyelinating polyneuropathy (CIDP) and multifocal motor neuropathy (MMN). The reliability of qualitative evaluation of brachial plexus MRI has not been studied previously.

Methods: We performed an interrater study in a retrospective cohort of 19 patients with CIDP, 17 patients with MMN, and 14 controls. The objective was to assess interrater variability between radiologists by using a predefined scoring system that allowed the distinction of no, possible, or definite nerve thickening.

Results: Raters agreed in 26 of 50 (52%) brachial plexus images; κ-coefficient was 0.30 (SE 0.08, 95% confidence interval 0.14-0.46, P < .0005).

Discussion: Our results provide evidence that interrater reliability of qualitative evaluation of brachial plexus MRI is low. Objective criteria for abnormality are required to optimize the diagnostic value of MRI for inflammatory neuropathies.
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http://dx.doi.org/10.1002/mus.26821DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7317832PMC
June 2020