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Photon-counting detector computed tomography (PCD-CT) is a modern spectral imaging technique utilizing photon-counting detectors (PCDs). PCDs detect individual photons and classify them into fixed energy bins, thus enabling energy selective imaging, contrary to energy integrating detectors that detects and sums the total energy from all photons during acquisition. The structure and composition of the articular cartilage cannot be detected with native CT imaging but can be assessed using contrast-enhancement. Spectral imaging allows simultaneous decomposition of multiple contrast agents, which can be used to target and highlight discrete cartilage properties. Here we report, for the first time, the use of PCD-CT to quantify a cationic iodinated CA4+ (targeting proteoglycans) and a non-ionic gadolinium-based gadoteridol (reflecting water content) contrast agents inside human osteochondral tissue (n = 53). We performed PCD-CT scanning at diffusion equilibrium and compared the results against reference data of biomechanical and optical density measurements, and Mankin scoring. PCD-CT enables simultaneous quantification of the two contrast agent concentrations inside cartilage and the results correlate with the structural and functional reference parameters. With improved soft tissue contrast and assessment of proteoglycan and water contents, PCD-CT with the dual contrast agent method is of potential use for the detection and monitoring of osteoarthritis.

Tiivistelmä. Tutkin pro gradu -tutkielmassani Simonkylän vesistönimien muuttumista. Tutkielman tarkoituksena oli selvittää, kuinka nimistö muuttuu ajan kuluessa sekä analysoida muutokseen vaikuttavia syitä. Tutkimusaineistona ovat alueelta vuosina 1870, 1915, 1952 ja 1987 kerätyt vesistönimet. Kaksi vanhinta aineistoa on peräisin kartoista. Kaksi muuta on kerätty kotimaisten kielten keskuksen paikannimikokoelmaan osana systemaattista nimistönkeruuta. Uusimman vertailuaineiston keräsin itse vuonna 2018. Laskin tutkielmassa, kuinka suuri osa vesistönimistä on säilynyt, kadonnut, muuttunut tai vaihtunut vuoteen 2018 mennessä. Vertaamalla vanhoja aineistoja uusimpaan sain selville 150 vuoden aikana tapahtuneen muutoksen. Muutoksen määrän lisäksi analysoin, miten nimien tarkoite tai rakenne vaikuttaa muutokseen eli muuttuvatko eri tyyppiset nimet eri tavoin. Nimistön muutokseen on olemassa vain vähän tutkimusmenetelmiä. Pelkästään vesistönimien tutkimiseen tehtyä menetelmää ei ole, joten kehitin tutkielmaan oman menetelmän. Metodissa määritetään jokaisen nimen tarkoite, ja analysoidaan ne syntaktis-semanttisella rakenneanalyysillä, joka on perinteinen suomalainen nimistöntutkimusmenetelmä. Kvalitatiivisen osan tuloksena jokaisesta nimestä saadaan analysoitavaksi tarkoitteet ja neljä eri rakennepiirrettä tutkielman kvantitatiiviseen osuuteen. Tutkielman kvantitatiivisessa osuudessa laskin, kuinka nimen tarkoite ja rakenteelliset ominaisuudet vaikuttavat muutokseen. Selvitin, kuinka esimerkiksi saarennimet ovat muuttuneet lahtien tai niemien nimiin verrattuna. Samoin vertailin muuttumista eri rakennetyyppien välillä. Tutkielman perusteella nimistöstä ei säily sellaisenaan edes 30 vuotta kuin kolmannes. Vuosien 1870 ja 1952 nimistä on säilynyt vuoteen 2018 reilu puolet, vuoden 1987 nimistä 70 %. Sellaisenaan säilyneitä nimiä on siis sitä vähemmän, mitä enemmän aikaa kuluu. Katoaminen ei vaikuta kiihtyvän kovinkaan paljon: Vanhimmista nimistä on vuoteen 2018 mennessä kadonnut noin viidennes, kahdesta uudemmasta aineistosta taas noin neljäsosa. Sen sijaan nimien vaihtuminen ja muuttuminen lisääntyvät. Muuttuneiden nimien määrä vaihtelee vanhimman aineiston viidesosasta uusimman aineiston alle viiteen prosenttiin. Määrään vaikuttaa osin tutkimusalueen sijainti maankohoamisalueella, sillä nimien tarkoitteet vaihtuvat maan noustessa, jolloin nimikin muuttuu. Nimen tarkoite ja rakenteelliset seikat näyttävät vaikuttavan nimien muuttumiseen jonkin verran. Varmoja johtopäätöksiä ei voi tehdä, sillä tutkielman aineisto on melko pieni, ja nimet painottuvat vahvasti muutamiin ryhmiin. Saarten nimet vaikuttaisivat kuitenkin säilyvän paremmin kuin muiden tarkoitteiden. Yksiosaiset nimet säilyvät kaksiosaisia paremmin, ja sijainnin mukaan nimetyt sekä toisen paikannimen sisältävät nimet katoavat herkemmin kuin muut. Aihetta kannattaisi kuitenkin tutkia laajemmalla aineistolla.

Segmentation of contrast-enhanced computed tomography (CECT) images enables quantitative evaluation of morphology of articular cartilage as well as the significance of the lesions. Unfortunately, automatic segmentation methods for CECT images are currently lacking. Here, we introduce a semiautomated technique to segment articular cartilage from in vivo CECT images of human knee. The segmented cartilage geometries of nine knee joints, imaged using a clinical CT-scanner with an intra-articular contrast agent, were compared with manual segmentations from CT and magnetic resonance (MR) images. The Dice similarity coefficients (DSCs) between semiautomatic and manual CT segmentations were 0.79–0.83 and sensitivity and specificity values were also high (0.76–0.86). When comparing semiautomatic and manual CT segmentations, mean cartilage thicknesses agreed well (intraclass correlation coefficient = 0.85–0.93); the difference in thickness (mean ± SD) was 0.27 ± 0.03 mm. Differences in DSC, when MR segmentations were compared with manual and semiautomated CT segmentations, were statistically insignificant. Similarly, differences in volume were not statistically significant between manual and semiautomatic CT segmentations. Semiautomation decreased the segmentation time from 450 ± 190 to 42 ± 10 min per joint. The results reveal that the proposed technique is fast and reliable for segmentation of cartilage. Importantly, this is the first study presenting semiautomated segmentation of cartilage from CECT images of human knee joint with minimal user interaction.

The aim of the present study was to evaluate the applicability of ultrasound imaging to quantitative assessment of human meniscus in vitro. Meniscus samples (n = 26) were harvested from 13 knee joints of non-arthritic human cadavers. Subsequently, three locations (anterior, center and posterior) from each meniscus were imaged with two ultrasound transducers (frequencies 9 and 40 MHz), and quantitative ultrasound parameters were determined. Furthermore, partial-least-squares regression analysis was applied for ultrasound signal to determine the relations between ultrasound scattering and meniscus integrity. Significant correlations between measured and predicted meniscus compositions and mechanical properties were obtained (R² = 0.38–0.69, p < 0.05). The relationship between conventional ultrasound parameters and integrity of the meniscus was weaker. To conclude, ultrasound imaging exhibited a potential for evaluation of meniscus integrity. Higher ultrasound frequency combined with multivariate analysis of ultrasound backscattering was found to be the most sensitive for evaluation of meniscus integrity.

Objective: The aim of this study was to investigate whether the concentration of the anionic contrast agent ioxaglate, as quantitated by contrast-enhanced computed tomography (CECT) using a clinical cone-beam CT (CBCT) instrument, reflects biochemical, histological, and biomechanical characteristics of articular cartilage imaged in an ex vivo, intact human knee joint. Design: An osteoarthritic human cadaveric knee joint (91 years old) was injected with ioxaglate (36 mg I/mL) and imaged using CBCT over 61 hours of ioxaglate diffusion into cartilage. Following imaging, the joint surfaces were excised, rinsed to remove contrast agent, and compressive stiffness (equilibrium and instantaneous compressive moduli) was measured via indentation testing (n = 17 sites). Each site was sectioned for histology and assessed for glycosaminoglycan content using digital densitometry of Safranin-O stained sections, Fourier transform infrared spectroscopy for collagen content, and morphology using both the Mankin and OARSI semiquantitative scoring systems. Water content was determined using mass change after lyophilization. Results: CECT attenuation at all imaging time points, including those

The beta-decay properties of the neutron-deficient nuclei Si-25 and P-26 have been investigated at the GANIL/LISE3 facility by means of charged-particle and gamma-ray spectroscopy. The decay schemes obtained and the Gamow-Teller strength distributions are compared to shell-model calculations based on the USD interaction. B(GT) values derived from the absolute measurement of the beta-decay branching ratios give rise to a quenching factor of the Gamow-Teller strength of 0.6. A precise half-life of 43.7 (6) ms was determined for (26)p, the beta-(2)p decay mode of which is described.

In an experiment performed at the GANIL LISE3 facility, radioactive S-27 isotopes have been produced by projectile fragmentation of a 95 AMeV Ar-36 primary beam. After selection by means of the LISE3 separator, the isotope of interest was implanted in a silicon-detector telescope where its half-life (T-1/2 = 15.5(15) ms) and its main decay branches were measured.

We have remeasured the decay of $^{31}$Ar with a setup sensitive to multiparticle decay branches and obtained a new limit of 1.1 × $10^{-3}$(99%C.L.) on the $\beta$-delayed three-proton branch between the isobaric analog state in $^{31}$Cl and the ground state of $^{28}$Si. This a factor of 17 below the previously reported first observation of $\beta$-delayed three-proton emission in $^{31}$Ar. The limit on a possible $\beta$-3p branch to the first excited state in $^{28}$Si is 2.9 × 10$^{-4}$.