Fernández-Seara, M.A. (María A.)
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- Systematic method for morphological reconstruction of the semicircular canals using a fully automatic skeletonization process(2019) Burguete-Mas, F.J. (Francisco Javier); Perez-Fernandez, N. (Nicolás); Cortés-Dominguez, I. (Iván); Fernández-Seara, M.A. (María A.)We present a novel method to characterize the morphology of semicircular canals of the inner ear. Previous experimental works have a common nexus, the human-operator subjectivity. Although these methods are mostly automatic, they rely on a human decision to determine some particular anatomical positions. We implement a systematic analysis where there is no human subjectivity. Our approach is based on a specific magnetic resonance study done in a group of 20 volunteers. From the raw data, the proposed method defines the centerline of all three semicircular canals through a skeletonization process and computes the angle of the functional pair and other geometrical parameters. This approach allows us to assess the inter-operator effect on other methods. From our results, we conclude that, although an average geometry can be defined, the inner ear anatomy cannot be reduced to a single geometry as seen in previous experimental works. We observed a relevant variability of the geometrical parameters in our cohort of volunteers that hinders this usual simplification.
- Comparison of myocardial blood flow quantification models for double ECG gating arterial spin labeling MRI: reproducibility assessment(Wiley Periodicals LLC, 2024) Solis-Barquero, S.M. (Sergio M.); Echeverría-Chasco, R. (Rebeca); Bastarrika, G. (Gorka); Aramendía-Vidaurreta, V. (Verónica); Vidorreta, M. (Marta); Fernández-Seara, M.A. (María A.); Ezponda, A. (Ana)Background: Arterial spin labeling (ASL) allows non-invasive quantification of myocardial blood flow (MBF). Double-ECG gating (DG) ASL is more robust to heart rate variability than single-ECG gating (SG), but its reproducibility requires further investigation. Moreover, the existence of multiple quantification models hinders its application. Frequency-offset-corrected-inversion (FOCI) pulses provide sharper edge profiles than hyperbolic-secant (HS), which could benefit myocardial ASL. Purpose: To assess the performance of MBF quantification models for DG compared to SG ASL, to evaluate their reproducibility and to compare the effects of HS and FOCI pulses. Study Type: Prospective. Subjects: Sixteen subjects (27 8 years). Field Strength/Sequence: 1.5 T/DG and SG flow-sensitive alternating inversion recovery ASL. Assessment: Three models for DG MBF quantification were compared using Monte Carlo simulations and in vivo experiments. Two models used a fitting approach (one using only a single label and control image pair per fit, the other using all available image pairs), while the third model used a T1 correction approach. Slice profile simulations were conducted for HS and FOCI pulses with varying B0 and B1. Temporal signal-to-noise ratio (tSNR) was computed for different acquisition/quantification strategies and inversion pulses. The number of images that minimized MBF error was investigated in the model with highest tSNR. Intra and intersession reproducibility were assessed in 10 subjects. Statistical Tests: Within-subject coefficient of variation, analysis of variance. P-value <0.05 was considered significant. Results: MBF was not different across acquisition/quantification strategies (P = 0.27) nor pulses (P = 0.9). DG MBF quantification models exhibited significantly higher tSNR and superior reproducibility, particularly for the fitting model using multiple images (tSNR was 3.46 2.18 in vivo and 3.32 1.16 in simulations, respectively; wsCV = 16%). Reducing the number of ASL pairs to 13/15 did not increase MBF error (minimum = 0.22 mL/g/min). Data Conclusion: Reproducibility of MBF was better for DG than SG acquisitions, especially when employing a fitting model. Level of Evidence: 2 Technical Efficacy: Stage 1
- Consensus‑based technical recommendations for clinical translation of renal ASL MRI(2020) Alsop, D.C. (David C.); Zhang, J.L. (Jeff L.); Sourbron, S. (Steven); Taso, M. (Manuel); Golay, X. (Xavier); Thomas, D.L. (David L.); Laustsen, C. (Christoffer); Pedrosa, I. (Ivan); Wang, D.J.J. (Danny J.J.); Buchanan, C.E. (Charlotte E.); Nery, F. (Fabio); Harteveld, A.A. (Anita A.); Gutberlet, M. (Marcel); Odudu, A. (Aghogho); Cox, E.F. (Eleanor F.); Madhuranthakam, A. (Ananth); Ljimani, A. (Alexandra); Gach, H.M. (H. Michael); Bane, O. (Octavia); Fernández-Seara, M.A. (María A.); Fain, S.B. (Sean B.); Robson, P.M. (Philip M.); Sharma, K. (Kanishka); Prasad, P.V. (Pottumarthi V.); Francis, S.T. (Susan T.); Derlin, K. (Katja)Objectives This study aimed at developing technical recommendations for the acquisition, processing and analysis of renal ASL data in the human kidney at 1.5 T and 3 T feld strengths that can promote standardization of renal perfusion measurements and facilitate the comparability of results across scanners and in multi-centre clinical studies. Methods An international panel of 23 renal ASL experts followed a modifed Delphi process, including on-line surveys and two in-person meetings, to formulate a series of consensus statements regarding patient preparation, hardware, acquisition protocol, analysis steps and data reporting. Results Fifty-nine statements achieved consensus, while agreement could not be reached on two statements related to patient preparation. As a default protocol, the panel recommends pseudo-continuous (PCASL) or fow-sensitive alternating inversion recovery (FAIR) labelling with a single-slice spin-echo EPI readout with background suppression and a simple but robust quantifcation model. Discussion This approach is considered robust and reproducible and can provide renal perfusion images of adequate quality and SNR for most applications. If extended kidney coverage is desirable, a 2D multislice readout is recommended. These recommendations are based on current available evidence and expert opinion. Nonetheless they are expected to be updated as more data become available, since the renal ASL literature is rapidly expanding.
- Multiparametric renal magnetic resonance imaging: A reproducibility study in renal allografts with stable function(Wiley, 2023) Martín-Moreno, P.L. (Paloma L.); Echeverría-Chasco, R. (Rebeca); Bastarrika, G. (Gorka); Aramendía-Vidaurreta, V. (Verónica); Cano, D. (David); Vidorreta, M. (Marta); Fernández-Seara, M.A. (María A.); Garcia-Fernandez, N. (Nuria); Villanueva, A. (Arantxa)Monitoring renal allograft function after transplantation is key for the early detection of allograft impairment, which in turn can contribute to preventing the loss of the allograft. Multiparametric renal MRI (mpMRI) is a promising noninvasive technique to assess and characterize renal physiopathology; however, few studies have employed mpMRI in renal allografts with stable function (maintained function over a long time period). The purposes of the current study were to evaluate the reproducibility of mpMRI in transplant patients and to characterize normal values of the measured parameters, and to estimate the labeling efficiency of Pseudo-Continuous Arterial Spin Labeling (PCASL) in the infrarenal aorta using numerical simulations considering experimental measurements of aortic blood flow profiles. The subjects were 20 transplant patients with stable kidney function, maintained over 1 year. The MRI protocol consisted of PCASL, intravoxel incoherent motion, and T1 inversion recovery. Phase contrast was used to measure aortic blood flow. Renal blood flow (RBF), diffusion coefficient (D), pseudo-diffusion coefficient (D*), flowing fraction ( f ), and T1 maps were calculated and mean values were measured in the cortex and medulla. The labeling efficiency of PCASL was estimated from simulation of Bloch equations. Reproducibility was assessed with the within-subject coefficient of variation, intraclass correlation coefficient, and Bland-Altman analysis. Correlations were evaluated using the Pearson correlation coefficient. The significance level was p less than 0.05. Cortical reproducibility was very good for T1, D, and RBF, moderate for f , and low for D*, while medullary reproducibility was good for T1 and D. Significant correlations in the cortex between RBF and f (r = 0.66), RBF and eGFR (r = 0.64), and D* and eGFR (r = -0.57) were found. Normal values of the measured parameters employing the mpMRI protocol in kidney transplant patients with stable function were characterized and the results showed good reproducibility of the techniques.
- Perspectives on the role of magnetic resonance imaging (Mri) for noninvasive evaluation of diabetic kidney disease(2021) Echeverría-Chasco, R. (Rebeca); Fernández-Seara, M.A. (María A.); Mora-Gutiérrez, J.M. (José María); Garcia-Fernandez, N. (Nuria)Renal magnetic resonance imaging (MRI) techniques are currently in vogue, as they provide in vivo information on renal volume, function, metabolism, perfusion, oxygenation, and microstructural alterations, without the need for exogenous contrast media. New imaging biomarkers can be identified using these tools, which represent a major advance in the understanding and study of the different pathologies affecting the kidney. Diabetic kidney disease (DKD) is one of the most important diseases worldwide due to its high prevalence and impact on public health. However, its multifactorial etiology poses a challenge for both basic and clinical research. Therefore, the use of novel renal MRI techniques is an attractive step forward in the comprehension of DKD, both in its pathogenesis and in its detection and surveillance in the clinical practice. This review article outlines the most promising MRI techniques in the study of DKD, with the purpose of stimulating their clinical translation as possible tools for the diagnosis, follow-up, and monitoring of the clinical impacts of new DKD treatments.
- Cortical hypoperfusion in Parkinson's disease assessed using arterial spin labeled perfusion MRI(Academic Press Inc Elsevier Science, 2012-02-01) Vidorreta, M. (Marta); Loayza, F.R. (Francis R.); Aznárez-Sanado, M. (Maite); Fernández-Seara, M.A. (María A.); Villagra, F. (Federico); Pastor, M.A. (María A.); Mengual, E. (Elisa); Irigoyen, J. (Jaione)Alterations in cerebral perfusion and metabolism in Parkinson's disease have been assessed in several studies, using nuclear imaging techniques and more recently magnetic resonance imaging. However, to date there is no consensus in the literature regarding the extent and the magnitude of these alterations. In this work, arterial spin labeled perfusion MRI was employed to quantify absolute cerebral blood flow in a group of earlyto- moderate Parkinson's disease patients and age-matched healthy controls. Perfusion comparisons between the two groups showed that Parkinson's disease is characterized by wide-spread cortical hypoperfusion. Subcortically, hypoperfusion was also found in the caudate nucleus. This pattern of hypoperfusion could be related to cognitive dysfunctions that have been previously observed even at the disease early stages. The present results were obtained by means of whole brain voxel-wise comparisons of absolute perfusion values, using statistical parametric mapping, thus avoiding the potentially biased global mean normalization procedure. In addition, this work demonstrates that between-group comparison of relative perfusion values after global mean normalization, introduced artifactual relative perfusion increases, where absolute perfusion was in fact preserved. This has implications for perfusion studies of other brain disorders.
- Continuous performance of a novel motor sequence leads to highly correlated striatal and hippocampal perfusion increases(Elsevier, 2009-05-15) Loayza, F.R. (Francis R.); Aznárez-Sanado, M. (Maite); Fernández-Seara, M.A. (María A.); Pastor, M.A. (María A.); Mengual, E. (Elisa)The time course of changes in regional cerebral perfusion during a continuous motor learning task performed with the right hand was monitored using the arterial spin labeling (ASL) technique at high field (3 T). ASL allowed measuring explicit learning related effects in neural activity elicited throughout a 6 minute task period. During this time learning took place as demonstrated by performance improvement. Comparing the initial and final learning phases, perfusion decreases were detected in most of the cortical regions recruited during early learning. More interestingly however perfusion increases were observed in a few cortical and subcortical regions of the contralateral hemisphere: the supplementary motor area, the primary somatosensory area, the posterior insula and posterior putamen, the hippocampus and bilaterally the retrosplenial cortex. Moreover, perfusion increases in the posterior putamen and hippocampus were highly correlated during the learning period. These results support the hypothesis that the striatum and hippocampus form interactive memory systems with parallel processing
- Systematic method for morphological reconstruction of the semicircular canals using a fully automatic skeletonization process(MDPI AG, 2019) Burguete-Mas, F.J. (Francisco Javier); Perez-Fernandez, N. (Nicolás); Cortés-Dominguez, I. (Iván); Fernández-Seara, M.A. (María A.)We present a novel method to characterize the morphology of semicircular canals of the inner ear. Previous experimental works have a common nexus, the human-operator subjectivity. Although these methods are mostly automatic, they rely on a human decision to determine some particular anatomical positions. We implement a systematic analysis where there is no human subjectivity. Our approach is based on a specific magnetic resonance study done in a group of 20 volunteers. From the raw data, the proposed method defines the centerline of all three semicircular canals through a skeletonization process and computes the angle of the functional pair and other geometrical parameters. This approach allows us to assess the inter-operator effect on other methods. From our results, we conclude that, although an average geometry can be defined, the inner ear anatomy cannot be reduced to a single geometry as seen in previous experimental works. We observed a relevant variability of the geometrical parameters in our cohort of volunteers that hinders this usual simplification.
- Technical recommendations for clinical translation of renal MRI: a consensus project of the Cooperation in Science and Technology Action PARENCHIMA(Springer, 2020) Alsop, D.C. (David C.); Sourbron, S. (Steven); Boer, A. (Anneloes) de; Golay, X. (Xavier); Dekkers, I. (Ilona); Laustsen, C. (Christoffer); Pedrosa, I. (Ivan); Pohlmann, A. (Andreas); Buchanan, C.E. (Charlotte E.); Nery, F. (Fabio); Harteveld, A.A. (Anita A.); Odudu, A. (Aghogho); Pullens, P. (Pim); Caroli, A. (Anna); Ljimani, A. (Alexandra); Bane, O. (Octavia); Fernández-Seara, M.A. (María A.); Fain, S.B. (Sean B.); Sharma, K. (Kanishka); Prasad, P.V. (Pottumarthi V.); Francis, S.T. (Susan T.); Mendichovszky, I.A. (Iosif A.); Sigmund, E. (Eric)Purpose The potential of renal MRI biomarkers has been increasingly recognised, but clinical translation requires more standardisation. The PARENCHIMA consensus project aims to develop and apply a process for generating technical recommendations on renal MRI. Methods A task force was formed in July 2018 focused on fve methods. A draft process for attaining consensus was distributed publicly for consultation and fnalised at an open meeting (Prague, October 2018). Four expert panels completed surveys between October 2018 and March 2019, discussed results and refned the surveys at a face-to-face meeting (Aarhus, March 2019) and completed a second round (May 2019). Results A seven-stage process was defned: (1) formation of expert panels; (2) defnition of the context of use; (3) literature review; (4) collection and comparison of MRI protocols; (5) consensus generation by an approximate Delphi method; (6) reporting of results in vendor-neutral and vendor-specifc terms; (7) ongoing review and updating. Application of the process resulted in 166 consensus statements. Conclusion The process generated meaningful technical recommendations across very diferent MRI methods, while allowing for improvement and refnement as open issues are resolved. The results are likely to be widely supported by the renal MRI community and thereby promote more harmonisation.
- Systematic method for morphological reconstruction of the semicircular canals using a fully automatic skeletonization process(MDPI, 2019) Perez-Fernandez, N. (Nicolás); Cortés-Dominguez, I. (Iván); Fernández-Seara, M.A. (María A.); Burguete, J. (Javier)
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