Diffusion tensor tractography imaging in pediatric epilepsy – A systematic review

Purpose Recent years brought several experimental and clinical reports applying diffusion tensor tractography imaging (DTI) of the brain in epilepsy. This study was aimed to evaluate current evidence for adding the DTI sequence to the standard diagnostic magnetic resonance imaging (MRI) protocol in pediatric epilepsy. Material and methods Rapid and qualitative systematic review (RAE, Rapid Evidence Assessment), aggregating relevant studies from the recent 7 years. The PubMed database was hand searched for records containing terms “tractography AND epilepsy.” Only studies referring to children were included; studies were rated using “final quality of evidence.” Results Out of 144 screened records, relevant 101 were aggregated and reviewed. The synthesis was based on 73 studies. Case-control clinical studies were the majority of the material and comprised 43.8% of the material. Low ‘confirmability’ and low ‘applicability’ referred to 18 and 17 articles (29.5% and 27.9%), respectively. The sufficient quality of evidence supported performing DTI in temporal lobe epilepsy, malformations of cortical development and prior to a neurosurgery of epilepsy. Conclusions The qualitative RAE provides an interim estimate of the clinical relevance of quickly developing diagnostic methods. Based on the critical appraisal of current knowledge, adding the DTI sequence to the standard MRI protocol may be clinically beneficial in selected patient groups with childhood temporal lobe epilepsy or as a part of planning for an epilepsy surgery

Nowoczesne techniki rezonansu magnetycznego w obrazowaniu guzów mózgu

  Modern MR imaging with advanced techniques such as diffusion, perfusion and spectroscopy as well as functional imaging have improved the characterization of brain tumors. Conven­tional imaging providing mainly anatomical or structural information. Novelty imaging techniques can reflect structural integrity (diffusion imaging), capillary density (perfusion techniques), and tissue biochemistry (MR spectroscopy). These advanced applications give insight into the microstructure, vascularity and metabolism of brain tumors. These techniques not only aid in the imaging diagnosis and treatment planning of brain tumors, but they also play a role in clinical management and monitoring treatment effect. Contemporary methods of magnetic resonance imaging were described in the article.Współczesne obrazowanie metodą rezonansu magnetycznego wraz z nowoczesnymi technikami MR, takimi jak dyfuzja, perfuzja i spektroskopia, a także obrazowanie funkcjonalne pozwalają na dokładną ocenę guzów mózgu wraz z ich szczegółową charakterystyką. Obrazowanie standardowe MR dostarcza głównie informacji anatomicznych i strukturalnych. Nowoczesne techniki obrazowania odzwierciedlają integralność strukturalną (obrazowanie dyfuzyjne), gęstość włośniczek (techniki perfuzyjne) oraz cechy biochemiczne tkanki (spektroskopia MR). Te zaawansowane sekwencje pozwalają uwidocznić mikrostrukturę, unaczynienie i metabolizm guzów mózgu. Techniki te nie tylko wspomagają diagnozowanie obrazowe i planowanie leczenia guzów mózgu, lecz także odgrywają istotną rolę w prowadzeniu terapii oraz monitorowaniu efektów leczenia. W artykule przedstawiono współcześnie stosowane metody obrazowania MR

Tractography-guided surgery of brain tumours: what is the best method to outline the corticospinal tract?

Background: Diffusion tensor imaging (DTI) is the imaging technique used in vivo to visualise white matter pathways. The cortico-spinal tract (CST) belongs to one of the most often delineated tracts preoperatively, although the optimal DTI method has not been established yet. Considering that various regions of interests (ROIs) could be selected, the reproducibility of CST tracking among different centres is low. We aimed to select the most reliable tractography method for outlining the CST for neurosurgeons. Materials and methods: Our prospective study consisted of 32 patients (11 males, 21 females) with a brain tumour of various locations. DTI and T1-weighed image series were acquired prior to the surgery. To draw the CST, the posterior limb of the internal capsule (PLIC) and the cerebral peduncle (CP) were defined as two main ROIs. Together with these main ROIs, another four cortical endpoints were selected: the frontal lobe (FL), the supplementary motor area (SMA), the precentral gyrus (PCG) and the postcentral gyrus (POCG). Based on these ROIs, we composed ten virtual CSTs in DSI Studio. The fractional anisotropy, the mean diffusivity, the tracts’ volume, the length and the number were compared between all the CSTs. The degree of the CST infiltration, tumour size, the patients’ sex and age were examined. Results: Significant differences in the number of tracts and their volume were observed when the PLIC or the CP stood as a single ROI comparing with the two- ROI method (all p < 0.05). The mean CST volume was 40054U (SD ± 12874) and the number of fibres was 259.3 (SD ± 87.3) when the PLIC was a single ROI. When the CP was a single ROI, almost a half of fibres (147.6; SD ± 64.0) and half of the CST volume (26664U; SD ± 10059U) was obtained (all p < 0.05). There were no differences between the various CSTs in terms of fractional anisotropy, mean diffusivity, the apparent diffusion coefficient, radial diffusivity and the tract length (p > 0.05). The CST was infiltrated by a growing tumour or oedema in 17 of 32 patients; in these cases, the mean and apparent diffusion of the infiltrated CST was significantly higher than in uncompromised CSTs (p = 0.04). CST infiltration did not alter the other analysed parameters (all p > 0.05). Conclusions: A universal method of DTI of the CST was not developed. However, we found that the CP or the PLIC (with or without FL as the second ROI) should be used to outline the CST

Frontal aslant tract projections to the inferior frontal gyrus

Background: Frontal aslant tract (FAT) is a white matter bundle connecting the pre-supplementary motor area (pre-SMA) and the supplementary motor area (SMA) with the inferior frontal gyrus (IFG). The purpose of the present study was to evaluate the anatomical variability of FAT. Materials and methods: Total number of fibres and the lateralisation index (LI) were calculated. We attempted to find factors contributing to the diversity of FAT regarding IFG terminations to the pars opercularis (IFG-Op) and to the pars triangularis (IFG-Tr). Magnetic resonance imaging of adult patients with diffusion tensor imaging (DTI) with total number of 98 hemispheres composed a cohort. V-shaped operculum was the most common (60.5%). Results: Total number of FAT fibres had widespread and unimodal distribution (6 to 1765; median: 160). Left lateralisation was noted in 64.3% of cases and was positively correlated with total number of FAT fibres and the bundle projecting to IFG-Op (p < 0.01). LI correlated with total number of FAT fibres (r = 0.43, p < 0.01). FAT projected predominantly to IFG-Op (88.9%; 88 of 99). Only in 3 (3.1%) cases more fibres terminated in IFG-Tr than in IFG-Op. Total number of FAT fibres and number of fibres terminating at IFG-Op did not correlate with the ratio of fibre numbers: FAT/IFG-Op, FAT/IFG-Tr and IFG-Op/IFG-Tr (p > 0.05). The greater total number of fibres to IFG-Tr was, the higher were the ratios of IFG-Tr/ /FAT (r = 0.57, p < 0.01) and IFG-Tr/IFG-Op (r = 0.32, p = 0.04). Conclusions: Among the IFG, the major termination of FAT is IFG-Op. Whereas the IFG-Tr projection seems to be related to the expansion of the entire FAT bundle regardless of side, domination and handedness. Nevertheless, FAT features a significant anatomical variability which cannot be explained in terms of DTI findings

Badanie rezonansem magnetycznym przeprowadzone bez powikłań u chorego z wszczepionym kardiowerterem-defibrylatorem

The number of patients with cardiac pacemakers (PM), implantable cardioverter-defibrillators (ICD) and cardiac resynchronisationtherapy PM systems is increasing. The number of magnetic resonance imaging (MRI) examinations is also growingand amounts to about 60 million tests per year worldwide. The presence of an ICD is still considered to be an absolute contraindicationto MRI by most experts. We present a patient with an implanted ICD who successfully underwent brain MRIwith use of special precautions

Reliability of diffusion tensor tractography of facial nerve in cerebello-pontine angle tumours

Aim of the study. This study aimed to verify the accuracy of preoperative visualisation of the facial nerve (FN) by magnetic resonance-based (MR) diffusion tensor imaging-fibre tracking (DTI-FT) with neuronavigation system integration in patients with cerebello-pontine angle (CPA) tumours.Clinical rationale for the study. Complete excision with preservation of the FN remains the critical goal of today’s vestibular schwannoma (VS) surgery. DTI-FT of the FN with neuronavigation is yet to be fully evaluated, and could make surgery safer.Materials and methods. This was a prospective cohort study in which 38 consecutive patients with a CPA tumour (32 VSs, five meningiomas and one epidermoid cyst) were operated on via the retrosigmoid route from 2013 to 2019. The course of the FN was simulated before surgery using StealthViz and the images were transferred to the Medtronic S7 neuronavigation system. The FN location reconstructed by DTI-FT was verified during the surgery.Results. MR acquisition was inappropriate in three patients (7.9%). DTI-FT correctly predicted the course of the FN in 31 of the 38 patients; the discordance rate was 18.4%. The accuracy of DTI-FT was 81.6% (95% CI: 65.67-92.26), sensitivity 88.57% (95% CI: 73.26-96.80) and positive predictive value was 91.18% (95% CI: 90.17-92.09). The reliability of the neuronavigation-integrated visualisation of the FN did not depend on the tumour size (p = 0.85), but the method was more accurate when the nerve was compact in shape (p = 0.03, area under curve (AUC) 0.87, 95% CI: 0.60-1.00) and in females (p = 0.04, AUC 0.78, 95% CI: 0.56-1.00). Following surgery, 86.5% of the patients presented with useful facial function (House-Brackmann grades I-III). Correct simulation of the FN did not prevent postoperative facial palsy (p = 0.35).Conclusions. The accuracy of DTI-FT of the FN integrated with neuronavigation remains unsatisfactory. This method does not provide any clinical benefit over non-integrated DTI-FT in terms of nerve function preservation.Clinical implications. Due to the low reliability of the predictions, further technical advances in predicting the course of the FN are awaited by clinicians. However, DTI-FT images in the operating theatre would make tumour excision more comfortable for the surgeon

Controlling the Bureaucracy of the Antipoverty Program

Rapid progress made in various areas of regenerative medicine in recent years occurred both at the cellular level, with the Nobel prize-winning discovery of reprogramming (generation of induced pluripotent stem (iPS) cells) and also at the biomaterial level. The use of four transcription factors, Oct3/4, Sox2, c-Myc, and Klf4 (called commonly "Yamanaka factors") for the conversion of differentiated cells, back to the pluripotent/embryonic stage, has opened virtually endless and ethically acceptable source of stem cells for medical use. Various types of stem cells are becoming increasingly popular as starting components for the development of replacement tissues, or artificial organs. Interestingly, many of the transcription factors, key to the maintenance of stemness phenotype in various cells, are also overexpressed in cancer (stem) cells, and some of them may find the use as prognostic factors. In this review, we describe various methods of iPS creation, followed by overview of factors known to interfere with the efficiency of reprogramming. Next, we discuss similarities between cancer stem cells and various stem cell types. Final paragraphs are dedicated to interaction of biomaterials with tissues, various adverse reactions generated as a result of such interactions, and measures available, that allow for mitigation of such negative effects