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Capsule Endoscopy (CE) is a unique technique for facilitating non-invasive and practical visualization of the entire small intestine. It has attracted a critical mass of studies for improvements. Among numerous studies being performed in capsule endoscopy, tremendous efforts are being made in the development of software algorithms to identify clinically important frames in CE videos. This thesis presents a computer-assisted method which performs automated detection of CE video-frames that contain bleeding. Specifically, a methodology is proposed to classify the frames of CE videos into bleeding and non-bleeding frames. It is a Support Vector Machine (SVM) based supervised method which classifies the frames on the basis of color features derived from image-regions. Image-regions are characterized on the basis of statistical features. With 15 available candidate features, an exhaustive feature-selection is followed to obtain the best feature subset. The best feature-subset is the combination of features that has the highest bleeding discrimination ability as determined by the three performance-metrics: accuracy, sensitivity and specificity. Also, a ground truth label annotation method is proposed in order to partially automate delineation of bleeding regions for training of the classifier. The method produced promising results with sensitivity and specificity values up to 94%. All the experiments were performed separately for RGB and HSV color spaces. Experimental results show the combination of the mean planes in red and green planes to be the best feature-subset in RGB (Red-Green-Blue) color space and the combination of the mean values of all three planes of the color space to be the best feature-subset in HSV (Hue-Saturation-Value).

Capsule Endoscopy (CE) is a unique technique for facilitating non-invasive and practical visualization of the entire small intestine. It has attracted a critical mass of studies for improvements. Among numerous studies being performed in capsule endoscopy, tremendous efforts are being made in the development of software algorithms to identify clinically important frames in CE videos. This thesis presents a computer-assisted method which performs automated detection of CE video-frames that contain bleeding. Specifically, a methodology is proposed to classify the frames of CE videos into bleeding and non-bleeding frames. It is a Support Vector Machine (SVM) based supervised method which classifies the frames on the basis of color features derived from image-regions. Image-regions are characterized on the basis of statistical features. With 15 available candidate features, an exhaustive feature-selection is followed to obtain the best feature subset. The best feature-subset is the combination of features that has the highest bleeding discrimination ability as determined by the three performance-metrics: accuracy, sensitivity and specificity. Also, a ground truth label annotation method is proposed in order to partially automate delineation of bleeding regions for training of the classifier. The method produced promising results with sensitivity and specificity values up to 94%. All the experiments were performed separately for RGB and HSV color spaces. Experimental results show the combination of the mean planes in red and green planes to be the best feature-subset in RGB (Red-Green-Blue) color space and the combination of the mean values of all three planes of the color space to be the best feature-subset in HSV (Hue-Saturation-Value).

Lange Zeit galt der Dünndarm als „Blackbox“ des Gastrointestinaltraktes. Seit Einführung der Videokapselendoskopie im Jahr 2001 eröffnete sich eine Methode, den Dünndarm zu visualisieren. An einem Kollektiv von 203 Patienten habe ich Indikationen, Ergebnisse und klinischen Nutzen von Dünndarmkapselendoskopien in einem Zeitraum von 4 Jahren untersucht. Der Dünndarm ist in der Gastroduodeno- und Koloskopie nicht komplett zugänglich, so dass bei entsprechender Indikation die nicht-invasive Videokapselendoskopie vorgenommen werden kann. Sie ist in der Lage 2-4 Bilder pro Sekunde in einem Zeitraum von 8-9 Stunden aufzunehmen, die als Film von ca. 50.000 Bildern zusammengestellt und interpretiert werden kann. Die Daten zur diagnostischen Ausbeute dieser Untersuchung variieren und sind abhängig von der entsprechenden Indikation. Zur Überprüfung des klinischen Nutzens habe ich daher in meiner Arbeit speziell die Passagezeiten und die erhobenen Befunde, wie Erosionen, Ulzerationen, Angiodysplasien, Petechien, Venektasien, Lymphangiektasien, Erytheme, Ödeme, Zottenreliefveränderungen, extrinsische Engen und Erhabenheiten im Hinblick für ihre diagnostische Bedeutung ausgewertet. Berücksichtigt wurden die Auswertbarkeit, Komplikationsrate sowie Vor- und Nachuntersuchungen. Das Aufklärungsgespräch erfolgte mindestens einen Tag vor der Videokapselendoskopie. Die Abführmaßnahmen entsprachen einer Koloskopievorbereitung. Das Studienkollektiv (203 Patienten) bestand aus 58% männlichen und 42% weiblichen Patienten. Der Altersdurchschnitt betrug 58 Jahre, die Altersspanne reichte von 8-90 Jahren. Über 93% nahmen die Videokapsel selbstständig ein, eine Applikation erfolgte bei 7% der Patienten in den Bulbus duodeni. Folgende Indikationen führten bei unserer Patientenklientel zu der Videokapselendoskopie: unklare gastrointestinale Blutung (45,3%), unklare abdominelle Schmerzen (24,1%), unklare Anämie (11,3%), Verdacht auf/ oder Komplikation bei Morbus Crohn (6,5%), unklare Diarrhoe (6,4%), Polyp- und Tumorsuche (5,4%), rezidivierendes unklares Erbrechen und Eiweißverlustsyndrom (jeweils 0,5%). Eine komplette Dünndarmpassage konnte innerhalb der Aufzeichnungszeit von 8-9 Stunden bei 84% der Patienten erreicht werden. Der Mittelwert der Magenpassagezeit lag bei 21 Minuten und der Dünndarmpassagezeit bei 6 Stunden. Die Komplikation Kapselretention trat bei 2% auf. Pathologische Befunde im Dünndarm wurden bei 85% detektiert. Die höchste diagnostische Ausbeute ergab sich bei der Abklärung der unklaren gastrointestinalen Blutung (80%) und bei der unklaren Anämie (78%), als häufigste Ursache wurden Schleimhautläsionen (43%) gefunden. Unklare abdominelle Schmerzen wiesen eine niedrigere diagnostische Ausbeute (41%) auf. Therapeutische Maßnahmen resultierten bei 73% der untersuchten Patienten aus den Kapselergebnissen. Eine medikamentöse Therapie wurde bei 66% eingeleitet oder verändert, Endoskopien wurden bei 4% und eine operative Therapie bei 4,4% durchgeführt. Damit ist die Dünndarmkapselendoskopie bei klarer Fragestellung und guter Darmvorbereitung eine sichere und sinnvolle Untersuchungsmethode, insbesondere zur Klärung unklarer gastrointestinaler Blutungen. Spezifische Dünndarmerkrankungen, wie der M. Crohn oder Tumore können relativ sicher ausgeschlossen werden.

In 2008 Ontario implemented a screening program for colorectal cancer, which drew attention to the increasing demand for colonoscopies in the province. This trend and the forecasted demand of the new screening program created a need to increase capacity in hospital endoscopy suites. This thesis addresses this need by investigating throughput gains from scheduling according to physician specific procedure durations in endoscopy suites. This is accomplished through the development of a scheduler and a generic discrete event simulation. Case study results show that physician specific scheduling can increase throughput in the endoscopy suite while reducing undertime and only slightly increasing overtime. They further indicate the trade off between a 1:2 and 1:1 physician to room ratio, finding that while a 1:1 ratio increases throughput by 33% over a 1:2 ratio, physicians are 1.5 times more productive under a 1:2 ratio.

In 2008 Ontario implemented a screening program for colorectal cancer, which drew attention to the increasing demand for colonoscopies in the province. This trend and the forecasted demand of the new screening program created a need to increase capacity in hospital endoscopy suites. This thesis addresses this need by investigating throughput gains from scheduling according to physician specific procedure durations in endoscopy suites. This is accomplished through the development of a scheduler and a generic discrete event simulation. Case study results show that physician specific scheduling can increase throughput in the endoscopy suite while reducing undertime and only slightly increasing overtime. They further indicate the trade off between a 1:2 and 1:1 physician to room ratio, finding that while a 1:1 ratio increases throughput by 33% over a 1:2 ratio, physicians are 1.5 times more productive under a 1:2 ratio.

Diss. (sammanfattning) Uppsala : Uppsala universitet, 2007. / Härtill 4 uppsatser.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2006. / Härtill 4 uppsatser.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2006. / Härtill 4 uppsatser.

Laparoscopic surgery or minimally invasive surgery has great advantages compared with the conventional open surgery, such as reduced pain, shorter recovery time and lower infection rate. It has become a standard clinical procedure for cholecystectomy, appendectomy and splenectomy. The state-of-the-art laparoscopic technologies suffer from several significant limitations, one of which is the tradeoff of the limited instantaneous field of view (FOV) for high spatial resolution versus the wide FOV for situational awareness but with diminished spatial resolution. Standard laparoscopes lack the ability to acquire both wide-angle and high-resolution images simultaneously through a single scope. During the surgery, a trained assistant is required to manipulate the laparoscope. The practice of frequently maneuvering the laparoscope by a trained assistant can lead to poor or awkward ergonomic scenarios. This type of ergonomic conflicts imposes inherent challenges to laparoscopic procedures, and it is further aggravated with the introduction of single port access (SPA) techniques to laparoscopic surgery. SPA uses one combined surgical port for all instruments instead of using multiple ports in the abdominal wall. The grouping of ports raises a number of challenges, including the tunnel vision due to the in-line arrangement of instruments, poor triangulation of instruments, and the instrument collision due to the close proximity to other surgical devices. A multi-resolution foveated laparoscope (MRFL) was proposed to address those limitations of the current laparoscopic surgery. The MRFL is able to simultaneously capture a wide-angle view for situational awareness and a high-resolution zoomed-in view for fine details. The high-resolution view can be scanned and registered anywhere within the wide-angle view, enabled by a 2D optical scanning mechanism. In addition, the high-resolution probe has optical zoom and autofocus capabilities, so that the field coverage can be dynamically varied while keep the same focus distance as the wide-angle probe. Moreover, the MRFL has a large working distance compared with the standard laparoscopes, the wide-angle probe has more than 8x field coverage than a standard laparoscope. On the other hand, the high-resolution probe has 3x spatial resolution than a standard one. These versatile capabilities are anticipated to have significant impacts on the diagnostic, clinical and technical aspects of minimally invasive surgery. In this dissertation, the development of the multi-resolution foveated laparoscope was discussed in detail. Starting from the refinement of the 1st order specifications, system configurations, and initial prototype demonstration, a customized dual-view MRFL system with fixed optical magnifications was developed and demonstrated. After the in-vivo test of the first generation prototype of the MRFL, further improvement was made on the high-resolution probe by adding an optical zoom and auto-focusing capability. The optical design, implementation and experimental validation of the MRFL prototypes were presented and discussed in detail.