Super- resolution of 3D MRI corrupted by heavy noise with the median filter transform

The acquisition of 3D MRIs is adversely affected by many degrading factors including low spatial resolution and noise. Image enhancement techniques are commonplace, but there are few proposals that address the increase of the spatial resolution and noise removal at the same time. An algorithm to address this vital need is proposed in this presented work. The proposal tiles the 3D image space into parallelepipeds, so that a median filter is applied in each parallelepiped. The results obtained from several such tilings are then combined by a subsequent median computation. The convergence properties of the proposed method are formally proved. Experimental results with both synthetic and real images demonstrate our approach outperforms its competitors for images with high noise levels. Moreover, it is demonstrated that our algorithm does not generate any hallucinations.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Multiobjective optimization of deep neural networks with combinations of Lp-norm cost functions for 3D medical image super-resolution

In medical imaging, the lack of high-quality images is present in many areas such as magnetic resonance (MR). Due to many acquisition impediments, the generated images have not enough resolution to carry out an adequate diagnosis. Image super-resolution (SR) is an ill-posed problem that tries to infer information from the image to enhance its resolution. Nowadays, deep learning techniques have become a powerful tool to extract features from images and infer new information. In MR, most of the recent works are based on the minimization of the errors between the input and the output images based on the Euclidean norm. This work presents a new methodology to perform three-dimensional SR based on the combination of Lp-norms in the loss layer. Two multiobjective optimization techniques are used to combine two cost functions. The proposed loss layers were trained with the SRCNN3D and DCSRN networks and tested with two MR structural T1-weighted datasets, and then compared with the traditional euclidean loss. Experimental results show significant differences in terms of Peak Signal-to-Noise Ratio (PSNR), Structural Similarity Index (SSIM) and Bhattacharyya Coefficient (BC), while the residual images show refined details

Deep learning-based super-resolution of 3D magnetic resonance images by regularly spaced shifting

The image acquisition process in the field of magnetic resonance imaging (MRI) does not always provide high resolution results that may be useful for a clinical analysis. Super-resolution (SR) techniques manage to increase the image resolution, being especially effective those based on examples that determine a correspondence between patterns of low resolution and high resolution. Deep learning neural networks have been applied in recent years to estimate this association with very competitive results. In this work, the starting point is a convolutional neuronal network to which a regularly spaced shifting mechanism over the input image is applied, with the aim of substantially improving the quality of the resulting image. This hybrid proposal has been compared with several SR techniques using the peak signal-to-noise ratio, structural similarity index and Bhattacharyya coefficient metrics. The results obtained on different MR images show a considerable improvement both in the restored image and in the residual image without an excessive increase in computing time

Language as a Threat: Multimodal Evaluation and Interventions for Overwhelming Linguistic Anxiety in Severe Aphasia

Linguistic anxiety (LA) is an abnormal stress response induced by situations that require the use of verbal behavior, and it is accentuated during language testing in persons with aphasia (PWA). The presence of LA in PWA may jeopardize the interpretation of cognitive evaluations, leading to biased conclusions about the severity of the language alteration and the effectiveness of the treatments. In the present study, we report the case of a woman (Mrs. A) with severe chronic mixed transcortical aphasia due to left frontal and parietal hemorrhages that partially spared the perisylvian area. Mrs. A was treated with the dopamine agonist Rotigotine alone and combined with Intensive Language-Action Therapy (ILAT). Complementary evaluations included autonomic reactivity during the performance of different language tasks, resting state functional magnetic resonance imaging (rs-fMRI) and [18F]-fluorodeoxyglucose positron emission tomography (18F-FDG-PET). We found that formal language testing in a clinical setting triggered a dramatic increase of automatic echolalia, perseverations and frustration, making the task completion difficult. The treatment improved aphasia, but gains were more robust when evaluation was performed by Mrs. A’s husband at home than by clinicians. Autonomic evaluation under Rotigotine revealed higher reactivity during tasks tapping an impaired function in comparison with a task evaluating a preserved function (verbal repetition). Baseline 18F-FDG-PET analysis showed decreased metabolic activity in left limbic-paralimbic areas, whereas rs-fMRI revealed compensatory activity in the right hemisphere. We also analyzed the different factors (e.g., premorbid personality traits, task difficulty) that may have contributed to LA in Mrs. A during language testing. Our findings emphasize the usefulness of implicating adequately trained laypersons in the evaluation and treatment of PWA showing LA. Further studies using multidimensional evaluations are needed to disentangle the interplay between anxiety and abnormal language as well as the neural mechanisms underpinning LA in PWA

Repetitive verbal behaviors are not always harmful signs: compensatory plasticity within the language network in aphasia

Los comportamientos verbales repetitivos como la conduite d’approche (CdA) y la ecolalia mitigada (ME) son fenómenos bien conocidos desde las primeras descripciones de las afasias. Sin embargo, no existe un conocimiento sustancialmente nuevo sobre sus características clínicas, correlatos cerebrales e intervenciones terapéuticas. En el presente estudio aprovechamos tres casos índice de afasia fluida crónica que muestran CdA, ME o ambos síntomas para diseccionar sus características clínicas y neuronalescerebrales. Utilizando neuroimagen multimodal (resonancia magnética estructural y tomografía por emisión de positrones con [1-fluorodesoxiglucosa] en estado de reposo), encontramos que, a pesar de las lesiones heterogéneas en términos de etiología (ictus, traumatismo craneoencefálico), volumen y ubicación, la CdA estaba presente cuando la lesión afectaba en mayor medida la vía dorsal del lenguaje en el hemisferio izquierdo, mientras que ME resultaba de un daño preferencial en la vía ventral izquierda. La coexistencia de CdA y ME se asoció con la afectación de áreas que se superponen con las lesiones estructurales y las alteraciones metabólicas descritas en los sujetos que mostraban uno de estos síntomas (CdA o ME). Estos hallazgos sugieren que CdA y ME representan la expresión clínica de cambios plásticos que ocurren dentro de la red del lenguaje preservada y sus áreas interconectadas, como una forma de compensar las funciones lingüísticas que previamente dependían de la actividad de la vía dañada. Discutimos los resultados a la luz de esta idea y consideramos redes neuronales alternativas no dañadas que podrían sustentar la CdA y la ME

Ecolalia mitigada y conducta de aproximación: plasticidad compensatoria en los circuitos cerebrales de lenguaje

Introducción. Las descripciones tradicionales de afasia atribuyen las alteraciones lingüísticas a daño de tejido cerebral, principalmente en el hemisferio izquierdo. Esta es una explicación lógica para aquellos síntomas que implican alteración de las funciones lingüísticas previas (capacidad de comprensión reducida, anomia, etc.). Sin embargo, los síntomas caracterizados por errores (parafasias, perseveraciones, etc.) o repetición verbal excesiva (ecolalia), no pueden emanar de áreas totalmente disfuncionales. Dentro de estos, hay dos síntomas que se observan con frecuencia en personas con afasia (PcA): conduite d´approach (aproximaciones sucesivas a la palabra objetivo, [CdA]) y ecolalia mitigada (EM). Objetivo. Explorar los mecanismos funcionales y estructurales que sustentan la CdA y EM, y cómo estos se relacionan con cambios plásticos dentro de la red del lenguaje. Para este fin, presentamos datos comportamentales y de neuroimagen de 3 PcA crónica. El paciente 1 presentaba un lenguaje caracterizada por múltiples instancias de CdA, el paciente 2 presentaba predominantemente EM y el paciente 3 instancias de ambos síntomas. Conclusiones. La CdA parece reflejar actividad de la vía ventral del lenguaje tras daño de la vía dorsal, mientras que la EM refleja hiperactividad de la vía dorsal en un intento por compensar un daño en la vía ventral.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Language as a threat: multimodal evaluation and interventions for overwhelming linguistic anxiety in severe aphasia

Linguistic anxiety (LA) is an abnormal stress response to verbal tasks, often heightened during language testing in people with aphasia (PWA), affecting the accuracy of cognitive evaluations. This study examined a woman with severe chronic mixed transcortical aphasia, caused by left frontal and parietal hemorrhages, treated with the dopamine agonist Rotigotine and Intensive Language-Action Therapy (ILAT). During formal language testing, LA triggered echolalia, perseverations, and frustration, complicating task completion. However, improvements were greater when her husband conducted evaluations at home. Autonomic measures showed higher reactivity during impaired tasks versus preserved ones. Imaging revealed decreased left-side brain activity and compensatory right hemisphere engagement. The findings suggest that involving trained laypersons in evaluating and treating PWA with LA can enhance outcomes and highlight the need for multidimensional approaches to understand the interplay between anxiety and language deficits

Is the emergence of speech errors in chronic post-stroke aphasia a result of ongoing compensatory brain plasticity mechanisms?

Traditional descriptions of aphasia have ascribed language disturbances to tissue damage but symptoms expressed as repetitive verbal behaviors such as echolalia, perseverations and so forth, cannot emanate from fully dysfunctional. We propose that in aphasia, repetitive verbal behaviors (such as conduite d’approche (CdA) and mitigated echolalia (ME)) may be compensatory behaviors emerging from ongoing plastic changes occurring in the preserved tissue. CdA is the repetitive and self-initiated approximation to a target word during spontaneous speech or naming tasks. ME refers to the echoing of a just heard sentence introducing a subtle change. At brain level, language deficits usually result from lesions affecting the dorsal and the ventral streams. Damage to the main dorsal pathway is related to deficits in verbal repetition and fluency, while lesions affecting the ventral pathway are related to comprehension deficits. Thus, we propose that ME may emerge from spared dorsal stream when the ventral system is compromised, while CdA may result as an attemp of the ventral stream to compensate dorsal damage. In this study we analysed three cases of aphasia at linguistic and structural (MRI and PET) levels. In patient 1, speech was predominantly characterized by instances of CdA, patient 2 presented predominantly ME instances, and patient 3 had both CdA and ME. Results showed that patient 1 had a disconnection pattern that greatly overlapped with the dorsal language pathway, while patient 2 ́s lesion location bisected the ventral pathway discontinuing the projection of fibers that run through it. Patient 3 presented a disconnection pattern in-between the two previous ones. These findings suggest that symptoms as CdA and ME, that frequently appear in the chronic stage of aphasia may represent the behavioral expression of plastic changes occurring within the preserved language network in an attempt to compensate the linguistic functions associated to the damaged pathway.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Aphasia with anatomical isolation of the language area: A reanalysis on the light of modern neuroimaging techniques

Introduction : Goldstein (1948) and Geschwind (1968), based in data derived from anatomical post-mortem studies, postulated that the disconnection of the perisylvian language areas (PSLA) from other cortical areas was responsible for impairments in spontaneous speech and language comprehension with preservation of verbal repetition and echolalia (isolation of speech area). Nevertheless, other mechanisms (right hemisphere or bilateral hypotheses) underlying echolalic repetition have been proposed. Herein, we examined the structure and function of the PSLAs in two cases of aphasia with echolalic repetition and isolation of the left PSLA. Methods : Two patients with chronic post-stroke aphasia associated to isolation of the left PSLA were studied. Both patients underwent cognitive-language assessment and multimodal imaging. In patient 1 (p1), structural MRI, diffusion tensor imaging (DTI), functional MRI (fMRI) during repetition of words and non-words, resting state fMRI (rsfMRI) were acquired, whereas only structural MRI was performed in patient 2 (p2). The Tractotron software was used to examine the severity of disconnection in each language-related white matter tract in both patients. We quantified the severity of the disconnection by measuring the proportion of each tract that was affected. 18FDG-PET was also acquired in both patients. Results : P1 had a mixed transcortical aphasia and p2 had a transcortical sensory/anomic aphasia. In both, the MRI showed separate left anterior and posterior lesions with relative preservation of the PSLA. In both, 18FDG-PET revealed significant decrements of metabolic activity in areas of the left PSLA, although some parts showed normal metabolic activity. In p1 the left arcuate fasciculus (AF) and the inferior fronto-occipital fasciculi (IFOF) could not be reconstructed. fMRI showed perilesional activity in the left hemisphere and increased activity in the right during word repetition. rsfMRI showed compensatory activity in both hemispheres (right greater than left). Analysis with the Tractotron software revealed disconnection of both the AF and the IFOF in the left hemisphere of both patients. Discussion : Although some parts of the left PSLA had preserved metabolic activity in both patients, our neuroimaging data revealed that preserved repetition ability did not rely exclusively on the residual activity of the left PSLA. In support, the connectivity between different components of the left PSLA was severely affected. This coupled with the increased metabolic activity of the right PSLA supports the bilateral hypothesis of residual repetition in transcortical aphasias. References : Goldstein, K. (1948). Language and Language Disturbances. Geschwind, et al. (1968). Neuropsychologia 6, 327–340.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Beneficial effects of pharmacological treatment in post-stroke dynamic aphasia: a behavioural and neuroimaging study

Introduction : Dynamic Aphasia (DA) is a rare form of language disorder characterized by reduced spontaneous speech with preservation of other language functions. Two types of DA have been described: language-specific type (type I DA) and domain-general type (type II DA). In type I DA, deficits are selective for word and sentence generation, whereas in type II DA impairments affect discourse generation, narrative, fluency, and non-verbal generation tasks. There is little information on the treatment of DA. Although treatment with a cognitive enhancing drug (bromocriptine) improved outcome in previous studies, pharmacological interventions combining two drugs acting on other neurotransmitter systems in DA have not been reported so far. Methods : We report an open-label pharmacological single case study (n = 1) in a male patient with a chronic type I/II DA secondary to an ischemic infarction in the left fronto-opercular and insular regions. After baseline evaluation, the patient received donepezil 5 mg/day (2 months), donepezil 10 mg/day (2 months), donepezil 10 mg/day plus memantine 20 mg/day (4½ months) followed by a washout period (1½ months). No speech-language therapy was used. A comprehensive cognitive and language evaluation was carried out at baseline and at different endpoints. 18FDG-PET was performed at the four timepoints. Results : Donepezil (5 mg/day) significantly improved type I DA features (normalization of verbs generation, p = 0.01), whereas donepezil (10 mg/day) improved some type II features (normalizing spontaneous speech, verbal fluency and improving generation of novel thoughts, p = 0.004), along with improvement of executive-attentional functioning. Combined therapy further enhanced cognitive function, but did not additionally improved DA. 18 FDG-PET revealed significant reductions of perilesional hypometabolic activity mainly after donepezil (10 mg/day) and washout. Discussion : Treatment with donepezil improved language deficits in a patient with chronic post-stroke type I/II DA. Combined therapy (donepezil plus memantine) further enhanced executive-attentional functioning. Beneficial changes were associated with improvements in perilesional metabolic activity. References : Luria AR et al.Acta Neurologica et Psychiatrica (1967). Robinson G et al. Brain (1998). Keywords : Language; patients; single case study; adults; cerebrovascular; behavioural, functional imaging.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech