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Dynamic Probabilistic Atlas of Functional Brain Regions for Transcranial Magnetic Stimulation [chapter]

Juha Koikkalainen, Mervi Könönen, Jari Karhu, Jarmo Ruohonen, Eini Niskanen, Jyrki Lötjönen
2008 Lecture Notes in Computer Science  
Transcranial Magnetic Stimulation (TMS) is a technique to stimulate the brain non-invasively. The applications range from accurate localization of the primary motor areas to potential treatment of disorders such as tinnitus, severe depression, and pain. Stereotactic guidance requires individual MR images of the subject's head, which is in some applications typically omitted due to financial motivations. In this paper, we introduce a method that offers improved TMS pulse targeting also to those
more » ... ubjects who do not have MR examinations. A probabilistic brain model was constructed by spatially normalizing the locations of the functional brain areas in a study population, and modeling the distributions and estimates of the locations of the functional brain regions using probabilistic methods. The application of the probabilistic brain model to the target subject was based on a point set determined from the scalp and facial skin of the target subject. The methods were evaluated using data from four functional brain areas from 56 healthy subjects. The accuracy of the estimates of the locations of the functional brain regions was about nine millimeters.
doi:10.1007/978-3-540-85988-8_65 fatcat:2t4jyodi5bbhhjtjb43hzvmlna

A characteristic time sequence of epileptic activity in EEG during dynamic penicillin-induced focal epilepsy—A preliminary study

Minna J. Silfverhuth, Jukka Kortelainen, Jyrki Ruohonen, Kalervo Suominen, Jaakko Niinimäki, Eila Sonkajärvi, Vesa Kiviniemi, Seppo Alahuhta, Ville Jäntti, Osmo Tervonen, Tapio Seppänen
2011 Seizure  
doi:10.1016/j.seizure.2011.03.006 pmid:21511498 fatcat:6t47bztrtfaa5ezjfbzanz4u3a

In vivo quantification of delayed gadolinium enhancement in the nucleus pulposus of human intervertebral disc

Jaakko L. Niinimäki, Outi Parviainen, Jyrki Ruohonen, Risto O. Ojala, Mauno Kurunlahti, Jaro Karppinen, Osmo Tervonen, Miika T. Nieminen
2006 Journal of Magnetic Resonance Imaging  
INTRODUCTION Diffusion through the end plates is the primary nutritional pathway of intervertebral disks. Deterioration of this pathway is known to be an important factor in the process of disk degeneration [1] Transfer of nutrients through the end plate can be simulated in vivo by measuring transfer of intravenously administered paramagnetic contrast agent into the nucleus pulposus of intervertebral disk from circulation. Previous animal and human studies have investigated disk enhancement
more » ... g paramagnetic contrast agents [2] [3] [4] [5] , however, these studies have only assessed signal intensity changes. The present study was conducted to quantify the delayed enhancement of the nucleus pulposus in vivo using a non-ionic contrast agent and T1 relaxation time measurements before and after contrast agent injection. Finally, the quantitative enhancement data were correlated with the Pfirrmann visual grading of disk degeneration [6] . METHODS Twenty male volunteers (mean age 49±5, range 40-55 ) were studied. A routine spine examination was conducted at 1.5T (two GE Signa 1.5T scanners, Milwaukee, WI), including T2-weighted sagittal images, that were used to score the intervertebral disk degeneration according to the Pfirrmann grading [6] . For T1 relaxation time measurements of intervertebral disks (between L1 and S1 vertebrae) a series of sagittal single slice inversion recovery measurements were conducted (TR=3400ms, TI=100, 200, 400, 800, 1600 and 3200ms, 4-mm slice thickness, in-plane resolution of 0.78mm). This was followed by an intravenous injection of 0.2mM/kg of non-ionic GdDTPA-DMA (Omniscan, Amersham Health AS, Oslo, Norway) and a T1 measurement series 90min after the injection. For each disk, T1 relaxation times were averaged from elliptical regions of interest (45±4mm 2 ) that were manually segmented into the nucleus pulposus. RESULTS Altogether 93 disks were analyzed. A statistically significant decrease in T1 relaxation time of nucleus pulposus was observed as a result of contrast agent intake (Wilcoxon signed ranks test, p<0.0001) ( Fig. 1 and 2) , the percentual change of T1 relaxation time for individual disks ranging between 0 and 60%. The T1 relaxation times varied between 440-980ms (mean 780 ± 120ms) and 350-940ms (690 ± 160ms) before and after the injection, respectively. A positive trend was observed between the change in the T1 relaxation rate (∆R1) and the Pfirrmann grading of disk degeneration (Fig. 3) . A statistically significant difference in ∆R1 was observed between samples in all Phirrmann grades except between grades II and III (Mann-Whitney U test, p<0.0001-0.02). DISCUSSION For a single compartment model the change in the R1 relaxivity rate (∆R1) is directly proportional to the contrast agent concentration within the pulposus if a constant relaxivity (R) is assumed, i.e. [GdDTPA-BMA] = R ∆R1. Absolute concentrations could be estimated if relaxivity of the gadolinium complex in the disk was known. A previous study suggests that the relaxivity between the pulposus and annulus may be different [7] . Since there is considerable variation in the T1 relaxation time without contrast agent it may not be possible to quantify the enhancement without a T1 measurement prior to contrast agent administration. Contrast agent intake is a dynamic process which is likely to depend on the nutritional pathway (blood vessels -vertebral sinusoids -endplate -annulus fibrosusnucleus pulposus) and the diffusional properties of these tissues. A previous study reported a decreased enhancement (signal intensity change) in degenerated disks minutes after contrast agent injection. The present results with a longer delay are not consistent with this finding, and it is anticipated that a longer delay may be less sensitive to short time-scale differences in contrast agent intake between normal and degenerated disks. Further studies are necessary to understand the observed relationship between the significant increase of ∆R1 (reflecting contrast agent concentration) and disk degeneration. Iatridis et al. suggested that the dGEMRIC-technique (delayed Gadolinium Enhanced MRI of Cartilage), designed to indirectly quantify the fixed charge density by using an ionic contrast agent, could possibly be applied for the intervertebral disk [7] . The present results show considerable variation in the diffusion of contrast agent into the disks that may provide a competing mechanism for contrast agent intake and therefore may cause inaccuracy to the dGEMRIC measurement of the disk. The present results suggest that delayed enhancement of the interverbral disk may be used to study the nutritional pathway into the disk. The quantative method to measure disk enhancement may be a sensitive parameter to assess degeneration, and may provide a means to investigate the etiology of degenerative disk disease. 200 400 600 800 1000 before after T1 (ms) II (n=19) III (n=28) IV (n=42) V (n=4) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 p<0.0001 p<0.001 ∆R1 (s -1 ) Pfirrmann grade REFERENCES 1. Boos N et al.
doi:10.1002/jmri.20693 pmid:16929532 fatcat:g2tmhoikv5holpu6ubk6bkkb5e

Comparison of 3D endoanal ultrasound and external phased array magnetic resonance imaging in the diagnosis of obstetric anal sphincter injuries

Jaan Kirss, Heikki Huhtinen, Eini Niskanen, Jyrki Ruohonen, Marja Kallio-Packalen, Sarita Victorzon, Mikael Victorzon, Tarja Pinta
2019 European Radiology  
The gold standard of postpartum anal sphincter imaging has been the 3D endoanal ultrasound (EAUS). Development of magnetic resonance imaging (MRI) has allowed anal sphincter evaluation without the use of endoanal coils. The aim of this study is to compare these two modalities in diagnosing residual sphincter lesions post obstetric anal sphincter injury (OASI). Forty women were followed up after primary repair of OASI with both 3D EAUS and external phased array MRI. Details of the anal sphincter
more » ... injury and sphincter musculature were gathered and analysed. There was a moderate interrater reliability (κ = 0.510) between the two imaging modalities in detecting sphincter lesions, with more lesions detected by MRI. There was a moderate intraclass correlation (ICC) between the circumference of the tear (κ = 0.506) and a fair ICC between the external anal sphincter thickness measurements at locations 3 and 9 on the proctologic clock face (κ = 0.320) and (κ = 0.336). The results of our study indicate that the use of external phased array MRI is feasible for detecting obstetric anal sphincter lesions postpartum. This allows for imaging of the sphincter defects in centres where EAUS imaging is not available. • A two centre prospective study that showed external phased array MRI to be a valid imaging modality for diagnosing obstetric anal sphincter injuries.
doi:10.1007/s00330-019-06125-8 pmid:30915565 pmcid:PMC6717181 fatcat:gu56sbiyerbe7bj7khgu2e3jzy

Geenitekniikalla muunnettujen organismien ympäristövaikutusten seuranta

Anu Kemppinen, Jyrki Pitkäjärvi, Marja Ruohonen-Lehto
. ○ ○ ○ ○ Finnish Environment Institute Anu Kemppinen, Jyrki Pitkäjärvi and Marja Ruohonen-Lehto Geenitekniikalla muunnettujen organismien ympäristövaikutusten seuranta (Monitoring environmental effects  ... 

Effects of navigated TMS on object and action naming

Julio C. Hernandez-Pavon, Niko Mäkelä, Henri Lehtinen, Pantelis Lioumis, Jyrki P. Mäkelä
2014 Frontiers in Human Neuroscience  
Both navigation systems calculate the strength of the maximum electric field that is overlaid on-line on the 3-D reconstruction of the individual's brain (Ruohonen and Karhu, 2010) .  ...  ., 2009; Ruohonen and Karhu, 2010) . The information provided by nTMS is useful for surgical planning, and it can be transferred into the operating theater via surgical neuronavigation systems.  ... 
doi:10.3389/fnhum.2014.00660 pmid:25228868 pmcid:PMC4151040 fatcat:b4b7b7esorfgjomsts6gljddgm

Localization of Sensorimotor Cortex Using Navigated Transcranial Magnetic Stimulation and Magnetoencephalography

Minna Pitkänen, Shogo Yazawa, Katja Airaksinen, Pantelis Lioumis, Jussi Nurminen, Eero Pekkonen, Jyrki P. Mäkelä
2019 Brain Topography  
To our knowledge, only one study has compared MEG and TMS motor mappings in a healthy subject (Ruohonen et al. 1996) . The study involved only one subject and mapped MEG motor readiness fields.  ... 
doi:10.1007/s10548-019-00716-w pmid:31093863 pmcid:PMC6707977 fatcat:huoudd32rbgblnva5yi6l2zv3i

Lehtiketjut ja lehdistön "uusi normaali": Keskittymisen mittaaminen ja sanomalehdistön keskittyminen Suomessa 2009–2019

Heikki Hellman
2021 Media & viestintä  
Oligopolisoitumisen riskinä on myös se, että se vaikeuttaa kilpailijoiden pääsyä markkinoille tai menestystä niillä ( Jyrki äinen 1994, 23-26; Picard 1988, 61) .  ...  Esimerkin välillisemmistä seurauksista tarjoaa "konsernijournalismi", jossa lehtitalon omistamien leh tien toimituksia yhdistetään ja sisältöä yhdenmukaistetaan, jolloin myös näkökulmat kaven tuvat (Ruohonen  ... 
doi:10.23983/mv.109861 fatcat:elpodafco5gdphqvn7n4634ytq

Structure and evolution of a European Parliament via a network and correlation analysis

Elena Puccio, Antti Pajala, Jyrki Piilo, Michele Tumminello
2016 Physica A: Statistical Mechanics and its Applications  
PS PS SDP VAS VAS VIHR Reciprocity top 3 scores Surname Party Signatures Tiilikainen KESK 3,002 Ruohonen PS 1,412 Kalmari KESK 292 Communities in the I parliament N C Party District  ... 
doi:10.1016/j.physa.2016.06.062 fatcat:mamcbg6iejezrd4z33wyioxs2m

Structure and Evolution of a European Parliament via a Network and Correlation Analysis

Elena Puccio, Antti Pajala, Jyrki Piilo, Michele Tumminello
2016 Social Science Research Network  
PS PS SDP VAS VAS VIHR Reciprocity top 3 scores Surname Party Signatures Tiilikainen KESK 3,002 Ruohonen PS 1,412 Kalmari KESK 292 Communities in the I parliament N C Party District  ... 
doi:10.2139/ssrn.2731304 fatcat:7dmjene4dzhinmcz6m2wpmcgza

Jäänmurtajat kansakunnan palveluksessa Koulu-uudistuksen käyn-tiinpanon unohdetut arkki-tehdit Kokemukset näkymät-tömästä ja oppiminen Antibioottiresistenssi-missä mennään?

Lauri Keskinen, Mari Riipinen, Ja Marjaana, Suorsa Kirjallisuus, Aaro Sahari, Markku Niemi, Eva-Mari Aro, Pirjo Kristiina Virtanen, Anni Leskelä, Heikki Saxén
Jyrkimmil lään ideologiakammo taisi olla Jyrki Kataisen hal lituksen aikana vuonna 2012, kun pääministeri lau sui vaalikeskustelussa kuuluisat sanansa: "Meillä ei ole hallituksessa kenelläkään ideologiaa  ...  Naiskirjailijoiden vahva panos kotimaisen arvoitusdek- Dekkarikentän inventaario Paula Arvas ja Voitto Ruohonen: Alussa oli murha -johtolankoja rikoskirjallisuuteen. Gaudeamus 2016.  ...  Onneksi Arvas ja Ruohonen pitävät lajien suuret linjat ja trendit otteessaan ja tuovat ne nykyaikaan asti.  ... 

Modernismin jälkeinen runous

Vesa Haapala, Päivi Koivisto
2020 Joutsen/Svanen: Yearbook of Finnish Literary Research  
Sevänen 2011: 26-39; Ruohonen 2011: 85-98) .  ...  Jyrki Kiiskinen puolestaan erittelee Puhuva kirjailija -haastattelussa runoutensa kehitystä tavalla, joka on käytännöllinen versio Anna Helteen tässä julkaisussa esittelemästä siirtymästä postmodernismista  ... 
doi:10.33346/joutsen-svanen.90988 fatcat:mj3rx7stefbwxfsrci6ndsl4lm


Leena Nissilä, Viron Kielen, Vaikutus Suomen, Kielen Verbien, J Niiden, Rektioiden Oppimiseen
Keskusteluun liittyviä tutkimuksia on tehty jo runsaasti (esimerkiksi Jyrki Kalliokoski, Minna Suni, Salla Kurhila ja Niina Lilja) .  ...  Venäjän kielen verbeillä perusmuoto on infinitiivi (Ruohonen−Strengell-Kämper 1996: 44) . Venäjän verbeillä on myös aktiivi ja passiivi. Kaikki verbimuodot kuuluvat jompaankumpaan kategoriaan.  ... 


Similarly, Finnish prime minister Jyrki Katainen declared: 'Too many EU Member States have been getting loans too cheaply for too long.  ...  An amendment tabled by Finnish ECR MEP Pirkko Ruohonen-Lerner and German ECR MEP Bernd Lucke is explicit in this regard: …proposals for a shock absorption function at euro area level reflect the dominance  ... 
doi:10.13130/corti-francesco_phd2020-05-21 fatcat:zpwtugftdvdkrpujsywanugoce