Sound evidence of gadolinium accumulation in brain has been recently provided after repeated administrations of linear gadolinium-based contrast agents (GBCAs), especially at the cerebellum level. ...Although data regarding brain accumulation of macrocyclic GBCAs are more reassuring, there is now a genuine concern (“gadolinium-phobia”) about possible long-term consequences of gadolinium deposits, especially in terms of cerebellar sequelae. We, therefore, questioned about the clinical impact of serial administration of gadoterate meglumine, a macrocyclic GBCA. In this retrospective study (2000–2016) of medical files of patients who received more than 20 administrations of gadoterate, we searched for cerebellar symptoms and signs developing during the regular follow-up. We reviewed medical files of ten patients (mean age 34.4 ± 20.8 years; 4 males, 6 females) who received 28.2 ± 5.3 doses of gadoterate (average total dose of GBCA 518 ± 226 ml; range 185–785 ml). Patients were examined by at least two medical specialists depending on initial diagnosis, and at least once by a neurosurgeon. Mean follow-up time was 91 months (range 49–168) and six out of ten patients experienced new symptoms or signs. No clinician reported the appearance of a rising cerebellar syndrome, nor newly appeared symptoms or signs suggested cerebellar toxicity. This retrospective clinical study shows no de novo clinical cerebellar syndrome following repeated administrations of gadoterate. Our results argue against a cerebellar toxicity of this macrocyclic agent. Still, confirmation in a larger number of subjects is required, as well as clinical studies concerning linear GBCAs whose structure and in vivo stability are distinct.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Objectives
Multicenter oncology trials increasingly include MRI examinations with apparent diffusion coefficient (ADC) quantification for lesion characterization and follow-up. However, the ...repeatability and reproducibility (R&R) limits above which a true change in ADC can be considered relevant are poorly defined. This study assessed these limits in a standardized whole-body (WB)-MRI protocol.
Methods
A prospective, multicenter study was performed at three centers equipped with the same 3.0-T scanners to test a WB-MRI protocol including diffusion-weighted imaging (DWI). Eight healthy volunteers per center were enrolled to undergo test and retest examinations in the same center and a third examination in another center. ADC variability was assessed in multiple organs by two readers using two-way mixed ANOVA, Bland-Altman plots, coefficient of variation (CoV), and the upper limit of the 95% CI on repeatability (RC) and reproducibility (RDC) coefficients.
Results
CoV of ADC was not influenced by other factors (center, reader) than the organ. Based on the upper limit of the 95% CI on RC and RDC (from both readers), a change in ADC in an individual patient must be superior to 12% (cerebrum white matter), 16% (paraspinal muscle), 22% (renal cortex), 26% (central and peripheral zones of the prostate), 29% (renal medulla), 35% (liver), 45% (spleen), 50% (posterior iliac crest), 66% (L5 vertebra), 68% (femur), and 94% (acetabulum) to be significant.
Conclusions
This study proposes R&R limits above which ADC changes can be considered as a reliable quantitative endpoint to assess disease or treatment-related changes in the tissue microstructure in the setting of multicenter WB-MRI trials.
Key Points
• The present study showed the range of R&R of ADC in WB-MRI that may be achieved in a multicenter framework when a standardized protocol is deployed.
• R&R was not influenced by the site of acquisition of DW images.
• Clinically significant changes in ADC measured in a multicenter WB-MRI protocol performed with the same type of MRI scanner must be superior to 12% (cerebrum white matter), 16% (paraspinal muscle), 22% (renal cortex), 26% (central zone and peripheral zone of prostate), 29% (renal medulla), 35% (liver), 45% (spleen), 50% (posterior iliac crest), 66% (L5 vertebra), 68% (femur), and 94% (acetabulum) to be detected with a 95% confidence level.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, VSZLJ, ZAGLJ
Introduction
There is emerging evidence that brain atrophy is a part of the pathophysiology of Multiple Sclerosis (MS) and correlates with several clinical outcomes of the disease, both physical and ...cognitive. Consequently, brain atrophy is becoming an important parameter in patients' follow‐up. Since in clinical practice both 1.5Tesla (T) and 3T magnetic resonance imaging (MRI) systems are used for MS patients follow‐up, questions arise regarding compatibility and a possible need for standardization.
Methods
Therefore, in this study 18 MS patients were scanned on the same day on a 1.5T and a 3T scanner. For each scanner, a 3D T1 and a 3D FLAIR were acquired. As no atrophy is expected within 1 day, these datasets can be used to evaluate the median percentage error of the brain volume measurement for gray matter (GM) volume and parenchymal volume (PV) between 1.5T and 3T scanners. The results are obtained with MSmetrix, which is developed especially for use in the MS clinical care path, and compared to Siena (FSL), a widely used software for research purposes.
Results
The MSmetrix median percentage error of the brain volume measurement between a 1.5T and a 3T scanner is 0.52% for GM and 0.35% for PV. For Siena this error equals 2.99%. When data of the same scanner are compared, the error is in the order of 0.06–0.08% for both MSmetrix and Siena.
Conclusions
MSmetrix appears robust on both the 1.5T and 3T systems and the measurement error becomes an order of magnitude higher between scanners with different field strength.
Brain atrophy tends to become an important parameter in Multiple Sclerosis patients' follow‐up. Since in clinical practice both 1.5Tesla (T) and 3T magnetic resonance imaging (MRI) systems are used for MS patients follow‐up, questions arise regarding compatibility and a possible need for standardization. Therefore, in this study, brain volume measurements at 1.5T and 3T MRI are evaluated. Our results demonstrate that a small brain atrophy measurement error can be achieved, especially when data of the same scanner are compared, in the order of 0.06–0.08% for both MSmetrix and SIENA.
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FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Purpose
To characterize cardiac‐driven liver movements using a harmonic phase image representation (HARP) with an optical flow quantification and motion amplification method. The method was applied ...to define the cardiac trigger delay providing minimal signal losses in liver DWI images.
Methods
The 16‐s breath‐hold balanced‐SSFP time resolved 20 images/s were acquired at 3T in coronal and sagittal orientations. A peripheral pulse unit signal was recorded. Cardiac‐triggered DWI images were acquired after different peripheral pulse unit delays. A steerable pyramid decomposition with multiple orientations and spatial frequencies was applied. The liver motion field‐map was derived from temporal variations of the HARP representation filtered around the cardiac frequency. Liver displacements were quantified with an optical flow method; moreover the right liver motion was amplified.
Results
The largest displacements were observed in the left liver (feet‐head:3.70 ± 1.06 mm; anterior–posterior: 2.35 ± 0.51 mm). Displacements were statistically significantly weaker in the middle right liver (0.47 ± 0.11 mm; P = 0.0156). The average error was 0.013 ± 0.022 mm (coronal plane) and 0.021 ± 0.041 mm (sagittal plane). The velocity field demonstrated opposing movements of the right liver extremities during the cardiac cycle. DWI signal loss was minimized in regions and instants of smallest amplitude of both velocity and velocity gradient.
Conclusion
Cardiac‐driven liver movements were quantified with combined cardiac frequency‐filtered HARP and optical flow methods. A motion phase opposition between right liver extremities was demonstrated. Displacement amplitude and velocity were larger in the left liver especially along the vertical direction. Motion amplification visually emphasized cardiac‐driven right liver displacements. The optimal cardiac timing minimizing signal loss in liver DWI images was derived.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Purpose
To prospectively assess liver ADC (apparent diffusion coefficient) repeatability from cardiac‐triggered diffusion‐weighted images obtained with an individually predetermined optimal cardiac ...time window minimizing cardiac‐related effects and to evaluate a signal filtering method aimed at artifact elimination.
Materials and Methods
After Institutional Review Board approval and written informed consent, eight healthy volunteers underwent four repetitions of respiratory‐triggered diffusion‐weighted sequences (3T, b: 0,150,500 s/mm2) without (RTnoCT, 51 sec) and with individually optimized cardiac triggering (RTCT, 306 sec). The optimal cardiac delay was individually predetermined using a 5‐second breath‐hold sequence. Monoexponential liver ADC and left‐to‐right‐liver ADC ratio were computed from region of interest (ROI) signal measurements (two independent readers). A filtering method, excluding signal intensities lower than the mean intensity at fixed b‐value, provided ADC recalculation. Limits‐of‐agreement (LOAs) from 95% confidence intervals for differences across the four repetitions provided the variability range.
Results
For Reader 1 (Reader 2), left‐to‐right‐liver ADC ratios were significantly higher in RTnoCT 1.51 (1.52) than in RTCT 1.12 (1.15), P = 0.012 (P = 0.017). Respectively for RTnoCT and RTCT: left liver LOAs were ±835 (±775), ± 315 (±369) 10‐6mm2/s; right liver LOAs were ±392 (±445), ± 172 (±140) 10‐6mm2/s: LOAs were larger in the left than in the right lobe (both P < 0.001). After filtering, left liver ADC LOAs narrowed to ±650 (±367) 10‐6mm2/s, P = 0.17 (P < 0.001); ± 152 (±208) 10‐6mm2/s (both P < 0.002) and left‐to‐right‐liver ADC ratio decreased to 1.28 (1.20), P = 0.017 (P = 0.012); 1.09 (1.08), P = 0.106 (P = 0.105).
Conclusion
Compared to noncardiac‐triggered acquisitions, individually optimized cardiac‐triggered acquisitions improved ADC repeatability in both liver lobes and reduced ADC differences between left and right liver. Left liver ADC repeatability was further improved after signal filtering. J. Magn. Reson. Imaging 2016;43:1100–1110.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Purpose
To improve multi‐atlas segmentation of the skeleton from whole‐body MRI. In particular, we study the effect of employing the atlas segmentations to iteratively mask tissues outside of the ...region of interest to improve the atlas alignment and subsequent segmentation.
Methods
An improved atlas registration scheme is proposed. Starting from a suitable initial alignment, the alignment is refined by introducing additional stages of deformable registration during which the image sampling is limited to the dilated atlas segmentation label mask. The performance of the method was demonstrated using leave‐one‐out cross‐validation using atlases of 10 whole‐body 3D‐T1 images of prostate cancer patients with bone metastases and healthy male volunteers, and compared to existing state of the art. Both registration accuracy and resulting segmentation quality, using four commonly used label fusion strategies, were evaluated.
Results
The proposed method showed significant improvement in registration and segmentation accuracy with respect to the state of the art for all validation criteria and label fusion strategies, resulting in a Dice coefficient of 0.887 (STEPS label fusion). The average Dice coefficient for the multi‐atlas segmentation showed over 11% improvement with a decrease of false positive rate from 28.3% to 13.2%. For this application, repeated application of the background masking did not lead to significant improvement of the segmentation result.
Conclusions
A registration strategy, relying on the use of atlas segmentations as mask during image registration was proposed and evaluated for multi‐atlas segmentation of whole‐body MRI. The approach significantly improved registration and final segmentation accuracy and may be applicable to other structures of interest.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Objective
To prospectively assess the early changes in the quadriceps and patellar tendons before and after total knee arthroplasty using ultrasound, shear wave elastography, and X-rays.
Materials ...and methods
Radiographs, ultrasound, and shear wave elastography were performed on 23 patients (16 women; aged 51–85, mean 66 ± 9 years) before and after surgery at 6 weeks and on 11 patients at 3 months. Patellar position and patellar tendon lengths were evaluated by radiography; joint effusion or synovitis, quadriceps and patellar tendon lengths, and thicknesses, echogenicity, vascularity, and stiffness were assessed with ultrasound and shear wave elastography.
Results
In the early postoperative period, 87% of the patients had joint effusion, and 43% had signs of synovitis. There was a significant thickening of the quadriceps tendon in 51.5% (
p
< .0001) and of the patellar tendon in 93.8% (
p
< .0001
)
of patients with a significant shortening of the patellar tendon in 7.8% (
p
< .0001). A hypoechoic defect on the medial aspect of the quadriceps tendon was found in 87% of the patients. There was a significant increase in Young’s modulus in the quadriceps tendon (
p
= .0006) but not in the patellar tendon.
Conclusion
The following should not be considered to be pathological findings at early postoperative imaging: joint effusion, synovitis, increasing of stiffness and thickening of quadriceps tendons by more than 50%, thickening of patellar tendon by more than 90%, focal defect through the medial aspect of the quadriceps tendon, and shortening of the patellar tendon by 8%.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, VSZLJ, ZAGLJ
Epilepsy is associated with genetic risk factors and cortico-subcortical network alterations, but associations between neurobiological mechanisms and macroscale connectomics remain unclear. This ...multisite ENIGMA-Epilepsy study examined whole-brain structural covariance networks in patients with epilepsy and related findings to postmortem epilepsy risk gene expression patterns. Brain network analysis included 578 adults with temporal lobe epilepsy (TLE), 288 adults with idiopathic generalized epilepsy (IGE), and 1328 healthy controls from 18 centres worldwide. Graph theoretical analysis of structural covariance networks revealed increased clustering and path length in orbitofrontal and temporal regions in TLE, suggesting a shift towards network regularization. Conversely, people with IGE showed decreased clustering and path length in fronto-temporo-parietal cortices, indicating a random network configuration. Syndrome-specific topological alterations reflected expression patterns of risk genes for hippocampal sclerosis in TLE and for generalized epilepsy in IGE. These imaging-transcriptomic signatures could potentially guide diagnosis or tailor therapeutic approaches to specific epilepsy syndromes.
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