Automatic Rectum Limit Detection by Anatomical Markers Correlation

Several diseases take place at the end of the digestive system. Many of them can be diagnosed by means of different medical imaging modalities together with computer aided detection (CAD) systems. These CAD systems mainly focus on the complete segmentation of the digestive tube. However, the detection of limits between different sections could provide important information to these systems. In this paper we present an automatic method for detecting the rectum and sigmoid colon limit using a novel global curvature analysis over the centerline of the segmented digestive tube in different imaging modalities. The results are compared with the gold standard rectum upper limit through a validation scheme comprising two different anatomical markers: the third sacral vertebra and the average rectum length. Experimental results in both magnetic resonance imaging (MRI) and computed tomography colonography (CTC) acquisitions show the efficacy of the proposed strategy in automatic detection of rectum limits. The method is intended for application to the rectum segmentation in MRI for geometrical modeling and as contextual information source in virtual colonoscopies and CAD systems.Fil: Namias, Rafael. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Centro Internacional Franco Argentino de Ciencias de la Información y Sistemas; ArgentinaFil: Venere, Marcelo Javier. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Grupo de Plasmas Densos Magnetizados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: del Fresno, Mirta Mariana. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Grupo de Plasmas Densos Magnetizados; Argentina. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; ArgentinaFil: D'amato, Juan Pablo. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Exactas. Grupo de Plasmas Densos Magnetizados; Argentina. Comision Nacional de Energi­a Atomica. Centro Atomico Bariloche; Argentin

3D BrachyView System

Prostate cancer is quickly becoming the most common form of cancer across the globe, and is commonly treated with low dose rate brachytherapy due to its curative measures and highly conformal dose delivery. It is important to ensure there is a means of real time monitoring of the dose and seed placements when radioactive seeds are implanted in the prostate gland during a low dose rate brachytherapy treatment. The BrachyView system presents as a unique system that provides the capability of 3D seed reconstruction within an intraoperative setting. In this thesis the BrachyView system is tested for its suitability, accuracy and the system is further developed so that its application in real-time intraoperative dosime-try can become a reality. The system was tested with a clinically relevant number of seeds, 98, where previously the system had only been tested with a maximum number of 30 seeds. The BrachyView system was able to reconstruct 91.8% of implanted seeds from the 98 seed dataset with an average overall discrepancy of 3.65 mm without the application of the baseline subtraction algorithm, however with its application to the data the detection efficiency was improved to 100% and an overall positional accuracy of 11.5%, correlating to a reduced overall discrepancy of 3.23 mm, was noted. It was found that with seed numbers of 30 or lower that the addition of a background subtrac-tion algorithm was not necessary, whereas for datasets containing a clinically relevant number of seeds the application of a background subtraction algorithm was paramount to reducing the noise, scatter and means for identification of newly implanted seeds that may be masked by those seed previously implanted

Artifact Rejection Methodology Enables Continuous, Noninvasive Measurement of Gastric Myoelectric Activity in Ambulatory Subjects.

The increasing prevalence of functional and motility gastrointestinal (GI) disorders is at odds with bottlenecks in their diagnosis, treatment, and follow-up. Lack of noninvasive approaches means that only specialized centers can perform objective assessment procedures. Abnormal GI muscular activity, which is coordinated by electrical slow-waves, may play a key role in symptoms. As such, the electrogastrogram (EGG), a noninvasive means to continuously monitor gastric electrical activity, can be used to inform diagnoses over broader populations. However, it is seldom used due to technical issues: inconsistent results from single-channel measurements and signal artifacts that make interpretation difficult and limit prolonged monitoring. Here, we overcome these limitations with a wearable multi-channel system and artifact removal signal processing methods. Our approach yields an increase of 0.56 in the mean correlation coefficient between EGG and the clinical "gold standard", gastric manometry, across 11 subjects (p < 0.001). We also demonstrate this system's usage for ambulatory monitoring, which reveals myoelectric dynamics in response to meals akin to gastric emptying patterns and circadian-related oscillations. Our approach is noninvasive, easy to administer, and has promise to widen the scope of populations with GI disorders for which clinicians can screen patients, diagnose disorders, and refine treatments objectively

Multimodality Imaging in Prostate Cancer

ABSTRACT Prostate cancer is the most common cancer in men in Finland. Its aggressiveness varies widely, from indolent to fatal disease. Accurate characterization of prostate cancer is extremely essential to prevent overtreatment while sustaining good survivorship and high quality of life. This is feasible using novel technology in imaging and automatic tools in treatment planning. In the first part of this thesis work, the aim was to evaluate anti-1-amino-3-18Ffluorocyclobutane-1-carboxylic acid (18F-FACBC) PET/CT, PET/MRI, and multiparametric MRI (mpMRI) in detection of primary prostate cancer. The uptake of 18F-FACBC was significantly stronger in tumors with higher Gleason score and it may therefore assist in targeted biopsies when combined with MRI. 18F-FACBC PET/MRI outperformed PET/CT but did not demonstrate higher diagnostic performance than mpMRI performed separately. Furthermore, PET/MRI and mpMRI failed to detect pelvic lymph node metastasis measuring less than 8mm. 18F-FACBC PET/MRI is promising in characterization of primary prostate cancer, especially if ablative treatments are planned. It is not likely to replace mpMRI in clinical practice. The second study assessed multimodality imaging in detecting bone metastasis in high-risk prostate cancer and breast cancer patients. All patients underwent 99mTc-HDP bone scintigraphy (BS), 99mTc-HDP SPECT, 99mTc-HDP SPECT/CT, 18F-NaF PET/CT, and whole body (wb) MRI+DWI. 99mTc-HDP SPECT/CT, 18F-NaF PET/CT, and wbMRI+DWI had superior sensitivity compared to conventional nuclear imaging. In particular non-BS techniques showed less equivocal findings. wbMRI+DWI was as accurate as 18F-NaF PET/CT for detecting bone metastasis and may be considered a potential “single-step” imaging modality for detection of bone metastasis in high-risk patients with prostate and breast cancer. The purpose of the third study was to evaluate and validate the performance of a fully automated segmentation tool (AST) in MRI-based radiotherapy planning of prostate cancer. It showed high agreement for delineating prostate, bladder, and rectum, compared to manual contouring, and suggested adoption of AST in clinical practice. Finally, the fourth study investigated the long-term toxicity after biologically guided radiotherapy in men with localized prostate cancer. Carbon-11 acetate (11C-ACE) PET-CT was used to guide dose escalation into metabolically active intraprostatic lesions. 11C-ACE PET-guided radiotherapy was feasible and well tolerated. Although erectile dysfunction was relatively common, severe gastro-intestinal symptoms were very rare, and no grade 3 genitourinary symptoms were present at five years after radiotherapy. The findings of this thesis have potential to improve diagnostic imaging and radiotherapy planning in primary and metastatic prostate cancer. Eventually, they are likely to improve patients’ quality of life and survival. KEYWORDS: prostate cancer, magnetic resonance imaging, positron emission tomography, radiotherapy planning, toxicity, bone metastasisTIIVISTELMÄ Eturauhassyöpä on miesten yleisin syöpä Suomessa. Sen taudinkuva vaihtelee laajasti rauhallisesta aggressiiviseen ja tappavaan. On oleellista, että taudin luonne arvioidaan tarkasti, jotta vältytään sen liialliselta hoidolta, tinkimättä erinomaisista hoitotuloksista selviytymisessä ja elämän laadussa. Uudet kuvantamisteknologiat ja automaattityökalut mahdollistavat tämän. Tämän väitöskirjan ensimmäisessä osatyössä oli tavoitteena arvioida anti-1-amino-3-18Ffluorosyklobutaani-1-karboksyylihappo (18F-FACBC) PET-tietokonetomografiaa (TT), PET-magneettiresonanssikuvantamista (MRI) ja multiparametrista MRI-kuvantamista (mpMRI) eturauhassyövän diagnoosivaiheessa. 18F-FACBC-kertymät olivat tilastollisesti merkitsevästi voimakkaampia korkean Gleason-luokituksen kasvaimissa, joten yhdistettyä PET-MRI-kuvantamista voidaan käyttää hyväksi esimerkiksi kohdennetussa koepalojen otossa. 18F-FACBC PET-MRI oli parempi kuin PET-TT ja samanveroinen kuin mpMRI eturauhassyövän diagnostiikassa. PET-MRI ja mpMRI eivät havainneet alle 8 mm:n läpimittaisia imusolmukemetastaaseja. 18F-FACBC PET-MRI on lupaava kuvantamismuoto eturauhassyövän diagnostiikassa, erityisesti kajoavia hoitoja suunniteltaessa, mutta ei korvanne mpMRI:a kliinisessä käytössä. Toinen osatyö käsitteli luustoetäpesäkkeiden toteamista eri kuvantamismenetelmillä korkean uusiutumisriskin eturauhas- ja rintasyöpäpotilailla. Kaikille potilaille tehtiin 99mTc-HDP luustokarttakuvaus, 99mTc-HDP SPECT, 99mTc-HDP SPECT-TT, 18F-NaF PET-TT ja koko kehon MRI diffuusiopainotettuna (wbMRI+DWI). 99mTc-HDP SPECT-TT, 18F-NaF PET-TT ja wbMRI+DWI olivat perinteistä luustokarttaa herkempiä luustometastaasien toteamisessa, koska epäspesifeiksi määriteltyjä muutoksia oli vähemmän. wbMRI+DWI osoitti yhtäläistä tarkkuutta luustometastaasien diagnosoinnissa 18F-NaF PET-TT:n verrattuna, joten sitä voitaisiin hyödyntää, käytettäessä vain yhtä kuvantamistapaa näiden potilaiden luustometastaasien toteamiseen. Kolmas osatyö arvioi ja validoi täysin automaattisen piirtotyökalun käyttöä MRI-pohjaisen sädehoidon suunnittelussa eturauhassyöpäpotilailla. Työkalu suoriutui hyvin eturauhasen, virtsarakon ja peräsuolen rajauksesta asiantuntijan käsin tekemiin rajauksiin verrattuna, puoltaen työkalun käyttöä luotettavasti myös kliinisessä työssä. Viimeisenä, neljännessä osatyössä arvioitiin biologisesti ohjatun eturauhassyövän sädehoidon aiheuttamia pitkäaikaishaittoja. Hiili-11 asetaatti (11C-ACE) PET-TT-kuvantamisen avulla suunniteltiin sädehoito, jossa metabolisesti aktiivisiin eturauhasen sisäisiin muutoksiin kohdistettiin korkeammat sädeannokset. 11C-ACE-PET-TT-ohjattu sädehoito oli toteuttamiskelpoinen ja hyvin siedetty. Vaikka erektiohäiriöt olivat suhteellisen yleisiä, vakavat suoliston haittavaikutukset olivat hyvin harvinaisia, eikä kolmannen asteen virtsateiden haittavaikutuksia esiintynyt lainkaan viiden vuoden kuluttua sädehoidosta. Tämän väitöskirjan löydökset voivat parantaa eturauhassyövän primaaridiagnostiikan kuvantamista ja sädehoidon suunnittelua, sekä luustoetäpesäkkeiden diagnostiikkaa. Näin voidaan kohentaa potilaiden elämänlaatua ja selviytymistä. AVAINSANAT: Eturauhassyöpä, magneettikuvaus, positroniemissiotomografia, sädehoidon suunnittelu, haittavaikutukset, luuston etäpesäkkee