Browsing by Author "Koikkalainen, Juha"
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- Associations of cognitive reserve and psychological resilience with cognitive functioning in subjects with cerebral white matter hyperintensities
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2021-08) Arola, Anne; Laakso, Hanna M.; Pitkanen, Johanna; Koikkalainen, Juha; Lotjonen, Jyrki; Korvenoja, Antti; Erkinjuntti, Timo; Melkas, Susanna; Jokinen, HannaBackground and purpose: Cerebral small vessel disease is characterized by progressive white matter hyperintensities (WMH) and cognitive decline. However, variability exists in how individuals maintain cognitive capabilities despite significant neuropathology. The relationships between individual cognitive reserve, psychological resilience and cognitive functioning were examined in subjects with varying degrees of WMH. Methods: In the Helsinki Small Vessel Disease Study, 152 subjects (aged 65–75 years) underwent a comprehensive neuropsychological assessment, evaluation of subjective cognitive complaints and brain magnetic resonance imaging with volumetric WMH evaluation. Cognitive reserve was determined by education (years) and the modified Cognitive Reserve Scale (mCRS). Psychological resilience was evaluated with the Resilience Scale 14. Results: The mCRS total score correlated significantly with years of education (r = 0.23, p < 0.01), but it was not related to age, sex or WMH volume. Together, mCRS score and education were associated with performance in a wide range of cognitive domains including processing speed, executive functions, working memory, verbal memory, visuospatial perception and verbal reasoning. Independently of education, the mCRS score had incremental predictive value on delayed verbal recall and subjective cognitive complaints. Psychological resilience was not significantly related to age, education, sex, WMH severity or cognitive test scores, but it was associated with subjective cognitive complaints. Conclusions: Cognitive reserve has strong and consistent associations with cognitive functioning in subjects with WMH. Education is widely associated with objective cognitive functioning, whereas lifetime engagement in cognitively stimulating leisure activities (mCRS) has independent predictive value on memory performance and subjective cognitive complaints. Psychological resilience is strongly associated with subjective, but not objective, cognitive functioning. - Tähtimäisten rakenteiden tunnistaminen TACT-3D mammografiakuvista
Helsinki University of Technology | Master's thesis(2005) Lohman, HenrikRintasyöpä on länsimaiden yleisin naisten syöpä. Mitä aikaisemmin rintasyöpä havaitaan, sitä todennäköisemmin se onnistutaan parantamaan. Paras keino rintasyövän toteamiseksi sen varhaisessa vaiheessa on mammografia, eli rinnan röntgenkuvaus. Mammografiakuvia tulkitsevat niiden lausumiseen erikoistuneet radiologit. Osa mammografiakuvissa näkyvistä syövistä jää heiltä kuitenkin havaitsematta, koska syövän aiheuttamat muutokset ovat pieniä ja kätkeytyvät terveen kudoksen joukkoon. Radiologien työtä helpottamaan on kehitetty useita tietokoneavusteisia järjestelmiä. Osa järjestelmistä pyrkii tunnistamaan rintasyövät automaattisesti mammografiakuvista ja esittää löydöksensä radiologille. Osa taas korostaa kuvien tähtimäisiä, pallomaisia tai ryynimäisiä rakenteita, jotka ovat mammografiakuvien tärkeimpiä syöpään viittaavia muutoksia. Diplomityössä kehitettiin järjestelmä tähtimäisten rakenteiden tunnistukseen TACT-mammografiakuvista. Tavoitteena oli, että tähtimäisiä rakenteita korostava kuvanparannusmenetelmä voitaisiin kohdistaa vain kuviin, joissa kyseisiä rakenteita todella esiintyy. Kehitetty järjestelmä etsii TACT mammografiakuvista säiemäisten rakenteiden leikkauspisteet, jotka se luokittelee tähtimäisten rakenteiden keskustoiksi. Järjestelmä estimoi aluksi kuvien säierakenteiden suunnat viivatunnistinmenetelmällä. Suuntien perusteella se muodostaa jokaiselle kuvan pisteelle sen naapuruston säierakenteiden suuntien jakaantumista kuvaavat suuntahistogrammit. Suuntahistogrammeista järjestelmä laskee kaksi piirrettä kuvan jokaiselle pisteelle. Toinen piirteistä kuvaa pistettä kohti suuntautuneiden säikeiden lukumäärää ja toinen säikeiden suuntien jakaantumisen tasaisuutta. Lopuksi järjestelmä laskee Bayesmenetelmällä jokaiselle kuvan pisteelle todennäköisyyden sen kuulumisesta tähtimäisen rakenteen keskustaan. Järjestelmän antamia tuloksia verrattiin kahden henkilön suorittamiin tähtimäisyysluokituksiin ROC- ja FROC-analyyseillä. Tuloksista kävi ilmi, että tähtimäisyys on subjektiivinen arvo, joten tulokset riippuivat Siitä, kumman luokituksiin järjestelmää verrattiin. FRX-analyysin perusteella järjestelmä löysi parhaimmillaan 80 % kaikista kasvaimista, tuottaen keskimäärin yhden väärän hälytyksen kuvaa kohden. - Global Burden of Small Vessel Disease-Related Brain Changes on MRI Predicts Cognitive and Functional Decline
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2020-01-01) Jokinen, Hanna; Koikkalainen, Juha; Laakso, Hanna M.; Melkas, Susanna; Nieminen, Tuomas; Brander, Antti; Korvenoja, Antti; Rueckert, Daniel; Barkhof, Frederik; Scheltens, Philip; Schmidt, Reinhold; Fazekas, Franz; Madureira, Sofia; Verdelho, Ana; Wallin, Anders; Wahlund, Lars Olof; Waldemar, Gunhild; Chabriat, Hugues; Hennerici, Michael; O'Brien, John; Inzitari, Domenico; Lötjönen, Jyrki; Pantoni, Leonardo; Erkinjuntti, TimoBackground and Purpose- Cerebral small vessel disease is characterized by a wide range of focal and global brain changes. We used a magnetic resonance imaging segmentation tool to quantify multiple types of small vessel disease-related brain changes and examined their individual and combined predictive value on cognitive and functional abilities. Methods- Magnetic resonance imaging scans of 560 older individuals from LADIS (Leukoaraiosis and Disability Study) were analyzed using automated atlas- and convolutional neural network-based segmentation methods yielding volumetric measures of white matter hyperintensities, lacunes, enlarged perivascular spaces, chronic cortical infarcts, and global and regional brain atrophy. The subjects were followed up with annual neuropsychological examinations for 3 years and evaluation of instrumental activities of daily living for 7 years. Results- The strongest predictors of cognitive performance and functional outcome over time were the total volumes of white matter hyperintensities, gray matter, and hippocampi (P<0.001 for global cognitive function, processing speed, executive functions, and memory and P<0.001 for poor functional outcome). Volumes of lacunes, enlarged perivascular spaces, and cortical infarcts were significantly associated with part of the outcome measures, but their contribution was weaker. In a multivariable linear mixed model, volumes of white matter hyperintensities, lacunes, gray matter, and hippocampi remained as independent predictors of cognitive impairment. A combined measure of these markers based on Z scores strongly predicted cognitive and functional outcomes (P<0.001) even above the contribution of the individual brain changes. Conclusions- Global burden of small vessel disease-related brain changes as quantified by an image segmentation tool is a powerful predictor of long-term cognitive decline and functional disability. A combined measure of white matter hyperintensities, lacunar, gray matter, and hippocampal volumes could be used as an imaging marker associated with vascular cognitive impairment. - Image databases in medical applications
Doctoral dissertation (article-based)(2006-03-17) Koikkalainen, JuhaThe number of medical images acquired yearly in hospitals increases all the time. These imaging data contain lots of information on the characteristics of anatomical structures and on their variations. This information can be utilized in numerous medical applications. In deformable model-based segmentation and registration methods, the information in the image databases can be used to give a priori information on the shape of the object studied and the gray-level values in the image, and on their variations. On the other hand, by studying the variations of the object of interest in different populations, the effects of, for example, aging, gender, and diseases on anatomical structures can be detected. In the work described in this Thesis, methods that utilize image databases in medical applications were studied. Methods were developed and compared for deformable model-based segmentation and registration. Model selection procedure, mean models, and combination of classifiers were studied for the construction of a good a priori model. Statistical and probabilistic shape models were generated to constrain the deformations in segmentation and registration so that only the shapes typical to the object studied were accepted. In the shape analysis of the striatum, both volume and local shape changes were studied. The effects of aging and gender, and also the asymmetries were examined. The results proved that the segmentation and registration accuracy of deformable model-based methods can be improved by utilizing the information in image databases. The databases used were relatively small. Therefore, the statistical and probabilistic methods were not able to model all the population-specific variation. On the other hand, the simpler methods, the model selection procedure, mean models, and combination of classifiers, gave good results also with the small image databases. Two main applications were the reconstruction of 3-D geometry from incomplete data and the segmentation of heart ventricles and atria from short- and long-axis magnetic resonance images. In both applications, the methods studied provided promising results. The shape analysis of the striatum showed that the volume of the striatum decreases in aging. Also, the shape of the striatum changes locally. Asymmetries in the shape were found, too, but any gender-related local shape differences were not found. - Image databases in medical image processing
Helsinki University of Technology | Licentiate thesis(2004) Koikkalainen, Juha - Kanadan energiapolitiikka ja energiantuotanto
Insinööritieteiden korkeakoulu | Bachelor's thesis(2015-11-26) Koikkalainen, Juha - Magneettiresonanssikuvien piirreirrotus ja sen käyttö Alzheimerin taudin tunnistamisessa
Helsinki University of Technology | Master's thesis(2008) Tölli, TuomasMagneettiresonanssikuvauksella (MRI) on sen hyvän kudoskontrastin vuoksi keskeinen rooli neurodegeneratiivisten sairauksien diagnoosissa. Kokeneellekin radiologille saattaa kuitenkin olla mahdotonta irrottaa riittävästi tietoa kolmiulotteisesta kuvasta. Lisäksi diagnoosia vaikeuttaa se, että MRI-kuvissa esiintyvien piirteiden ja patologioiden välisistä korrelaatioista saattaa olla liian vähän tietoa. Tässä työssä kehitettiin menetelmiä ihmisaivojen MRI-kuvien piirreirrotukseen. Työn sovelluskohteena käytettiin Alzheimerin taudin tunnistamista samanikäisistä kognitiivisesti terveistä kontrollihenkilöistä. Työssä tehtiin morfometrinen kuva-analyysi suurelle MRI-aineistolle (127 Alzheimer- potilasta ja 155 kontrollia). Tämän jälkeen työssä kehitettiin piirreirrotusmenetelmä, joka hyödynsi kuva-analyysin tuloksena saatuja muunnoskenttiä Alzheimerin taudin tunnistamisessa. Muunnoskenttiä lähestyttiin kolmella eri tavalla: työssä kehitettiin piirreirrotusalgoritmi, joka etsi vokselikohtaisesti merkitsevästi poikkeavia piirteitä; työssä toteutettiin anatomisten rakenteiden muotoanalyysi, jonka perusteella lokaaleja, Alzheimerin taudin tunnistamisen kannalta relevantteja muodonmuutoksia irrotettiin piirteiksi; työssä käytettiin aivojen anatomisille rakenteille ominaisia piirteitä (mm. tilavuuden muutos). Lopulta kehitetyn menetelmän irrottamat piirteet yhdistettiin, ja niiden soveltuvuutta evaluoitiin Alzheimerin taudin tunnistamiseen. Menetelmän validointiin käytettiin sen rakentamisen suhteen täysin erillistä ja riippumatonta MRI-aineistoa. Työn tuloksena saatiin yksinkertainen menetelmä, joka automaattisesti löysi Alzheimerin taudille tyypillisiä piirteitä. Lisäksi tulokset osoittivat, että kehitetyn piirreirrotusalgoritmin tuottamat piirteet paransivat merkittävästi Alzheimerin taudin tunnistamiskykyä. - Mallikirjaston käyttäminen MR-leikekuvien segmentoinnissa
Helsinki University of Technology | Master's thesis(2002) Koikkalainen, Juha - Modelling of transcritical CO2 process in a wholesale building
Insinööritieteiden korkeakoulu | Master's thesis(2018-02-05) Koikkalainen, Juha - Neurofilament light level correlates with brain atrophy, and cognitive and motor performance
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2023-01-05) Kartau, Marge; Melkas, Susanna; Kartau, Joonas; Arola, Anne; Laakso, Hanna; Pitkänen, Johanna; Lempiäinen, Juha; Koikkalainen, Juha; Lötjönen, Jyrki; Korvenoja, Antti; Ahlström, Matti; Herukka, Sanna Kaisa; Erkinjuntti, Timo; Jokinen, HannaBackground: The usefulness of neurofilament light (NfL) as a biomarker for small vessel disease has not been established. We examined the relationship between NfL, neuroimaging changes, and clinical findings in subjects with varying degrees of white matter hyperintensity (WMH). Methods: A subgroup of participants (n = 35) in the Helsinki Small Vessel Disease Study underwent an analysis of NfL in cerebrospinal fluid (CSF) as well as brain magnetic resonance imaging (MRI) and neuropsychological and motor performance assessments. WMH and structural brain volumes were obtained with automatic segmentation. Results: CSF NfL did not correlate significantly with total WMH volume (r = 0.278, p = 0.105). However, strong correlations were observed between CSF NfL and volumes of cerebral grey matter (r = −0.569, p < 0.001), cerebral cortex (r = −0.563, p < 0.001), and hippocampi (r = −0.492, p = 0.003). CSF NfL also correlated with composite measures of global cognition (r = −0.403, p = 0.016), executive functions (r = −0.402, p = 0.017), memory (r = −0.463, p = 0.005), and processing speed (r = −0.386, p = 0.022). Regarding motor performance, CSF NfL was correlated with Timed Up and Go (TUG) test (r = 0.531, p = 0.001), and gait speed (r = −0.450, p = 0.007), but not with single-leg stance. After adjusting for age, associations with volumes in MRI, functional mobility (TUG), and gait speed remained significant, whereas associations with cognitive performance attenuated below the significance level despite medium to large effect sizes. Conclusion: NfL was strongly related to global gray matter and hippocampal atrophy, but not to WMH severity. NfL was also associated with motor performance. Our results suggest that NfL is independently associated with brain atrophy and functional mobility, but is not a reliable marker for cerebral small vessel disease. - Neuropsychiatric symptoms are associated with exacerbated cognitive impairment in covert cerebral small vessel disease
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2023-06-30) Arola, Anne; Levanen, Tuuli; Laakso, Hanna M.; Pitkanen, Johanna; Koikkalainen, Juha; Lotjonen, Jyrki; Korvenoja, Antti; Erkinjuntti, Timo; Melkas, Susanna; Jokinen, HannaObjectives: Neuropsychiatric symptoms are related to disease progression and cognitive decline over time in cerebral small vessel disease (SVD) but their significance is poorly understood in covert SVD. We investigated neuropsychiatric symptoms and their relationships between cognitive and functional abilities in subjects with varying degrees of white matter hyperintensities (WMH), but without clinical diagnosis of stroke, dementia or significant disability. Methods: The Helsinki Small Vessel Disease Study consisted of 152 subjects, who underwent brain magnetic resonance imaging (MRI) and comprehensive neuropsychological evaluation of global cognition, processing speed, executive functions, and memory. Neuropsychiatric symptoms were evaluated with the Neuropsychiatric Inventory Questionnaire (NPI-Q, n = 134) and functional abilities with the Amsterdam Instrumental Activities of Daily Living questionnaire (A-IADL, n = 132), both filled in by a close informant. Results: NPI-Q total score correlated significantly with WMH volume (r (s) = 0.20, p = 0.019) and inversely with A-IADL score (r (s) = -0.41, p < 0.001). In total, 38% of the subjects had one or more informant-evaluated neuropsychiatric symptom. Linear regressions adjusted for age, sex, and education revealed no direct associations between neuropsychiatric symptoms and cognitive performance. However, there were significant synergistic interactions between neuropsychiatric symptoms and WMH volume on cognitive outcomes. Neuropsychiatric symptoms were also associated with A-IADL score irrespective of WMH volume. Conclusions: Neuropsychiatric symptoms are associated with an accelerated relationship between WMH and cognitive impairment. Furthermore, the presence of neuropsychiatric symptoms is related to worse functional abilities. Neuropsychiatric symptoms should be routinely assessed in covert SVD as they are related to worse cognitive and functional outcomes. - Subjective vs informant-reported cognitive complaints have differential clinical significance in covert cerebral small vessel disease
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2023-01) Arola, Anne; Laakso, Hanna M.; Heinonen, Heidi; Pitkänen, Johanna; Ahlström, Matti; Lempiäinen, Juha; Paajanen, Teemu; Virkkala, Jussi; Koikkalainen, Juha; Lötjönen, Jyrki; Korvenoja, Antti; Melkas, Susanna; Jokinen, HannaObjective: Subjective cognitive complaints are common in patients with cerebral small vessel disease (cSVD), yet their relationship with informant evaluations, objective cognitive functions and severity of brain changes are poorly understood. We studied the associations of subjective and informant reports with findings from comprehensive neuropsychological assessment and brain MRI. Method: In the Helsinki SVD Study, 152 older adults with varying degrees of white matter hyperintensities (WMH) but without stroke or dementia were classified as having normal cognition or mild cognitive impairment (MCI) based on neuropsychological criteria. The measures also included continuous domain scores for memory and executive functions. Cognitive complaints were evaluated with the subjective and informant versions of the Prospective and Retrospective Memory Questionnaire (PRMQ) and Dysexecutive Questionnaire (DEX); functional abilities with the Amsterdam Instrumental Activities of Daily Living Questionnaire (A-IADL); and depressive symptoms with the Geriatric Depression Scale (GDS-15). Results: Subjective cognitive complaints correlated significantly with informant reports (r=0.40–0.50, p<0.001). After controlling for demographics, subjective and informant DEX and PRMQ were not related to MCI, memory or executive functions. Instead, subjective DEX and PRMQ significantly associated with GDS-15 and informant DEX and PRMQ with WMH volume and A-IADL. Conclusions: Neither subjective nor informant-reported cognitive complaints associated with objective cognitive performance. Informant-evaluations were related to functional impairment and more severe WMH, whereas subjective complaints only associated with mild depressive symptoms. These findings suggest that awareness of cognitive impairment may be limited in early-stage cSVD and highlight the value of informant assessments in the identification of patients with functional impairment. - Synergistic associations of cognitive and motor impairments with functional outcome in covert cerebral small vessel disease
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä(2022-01) Jokinen, Hanna; Laakso, Hanna M.; Ahlström, Matti; Arola, Anne; Lempiäinen, Juha; Pitkänen, Johanna; Paajanen, Teemu; Sikkes, Sietske A.M.; Koikkalainen, Juha; Lötjönen, Jyrki; Korvenoja, Antti; Erkinjuntti, Timo; Melkas, SusannaBackground: Cognitive and motor impairments are the key clinical manifestations of cerebral small vessel disease (SVD), but their combined effects on functional outcome have not been elucidated. This study investigated the interactions and mediating effects of cognitive and motor functions on instrumental activities of daily living (IADL) and quality of life in older individuals with various degrees of white matter hyperintensities (WMH). Methods: Participants of the Helsinki Small Vessel Disease Study (n = 152) were assessed according to an extensive clinical, physical, neuropsychological and MRI protocol. Volumes of WMH and gray matter (GM) were obtained with automated segmentation. Results: Cognitive (global cognition, executive functions, processing speed, memory) and motor functions (gait speed, single-leg stance, timed up-and-go) had strong interrelations with each other, and they were significantly associated with IADL, quality of life as well as WMH and GM volumes. A consistent pattern on significant interactions between cognitive and motor functions was found on informant-evaluated IADL, but not on self-evaluated quality of life. The association of WMH volume with IADL was mediated by global cognition, whereas the association of GM volume with IADL was mediated by global cognition and timed up-and-go performance. Conclusion: The results highlight the complex interplay and synergism between motor and cognitive abilities on functional outcome in SVD. The combined effect of motor and cognitive disturbances on IADL is likely to be greater than their individual effects. Patients with both impairments are at disproportionate risk for poor outcome. WMH and brain atrophy contribute to disability through cognitive and motor impairment. - Tulot, onnellisuus ja hyöty.
School of Business | Master's thesis(2008) Koikkalainen, Juha