Non-Rigid Registration between Histological and MR Images of the Prostate: A Joint Segmentation and Registration Framework

This paper presents a 3D non-rigid registration algorithm between histological and MR images of the prostate with cancer. To compensate for the loss of 3D integrity in the histology sectioning process, series of 2D histological slices are first reconstructed into a 3D histological volume. After that, the 3D histology-MRI registration is obtained by maximizing a) landmark similarity and b) cancer region overlap between the two images. The former aims to capture distortions at prostate boundary and internal bloblike structures; and the latter aims to capture distortions specifically at cancer regions. In particular, landmark similarities, the former, is maximized by an annealing process, where correspondences between the automatically-detected boundary and internal landmarks are iteratively established in a fuzzy-to-deterministic fashion. Cancer region overlap, the latter, is maximized in a joint cancer segmentation and registration framework, where the two interleaved problems – segmentation and registration – inform each other in an iterative fashion. Registration accuracy is established by comparing against human-rater-defined landmarks and by comparing with other methods. The ultimate goal of this registration is to warp the histologically-defined cancer ground truth into MRI, for more thoroughly understanding MRI signal characteristics of the prostate cancerous tissue, which will promote the MRI-based prostate cancer diagnosis in the future studies

MEMS Technology for Biomedical Imaging Applications

Biomedical imaging is the key technique and process to create informative images of the human body or other organic structures for clinical purposes or medical science. Micro-electro-mechanical systems (MEMS) technology has demonstrated enormous potential in biomedical imaging applications due to its outstanding advantages of, for instance, miniaturization, high speed, higher resolution, and convenience of batch fabrication. There are many advancements and breakthroughs developing in the academic community, and there are a few challenges raised accordingly upon the designs, structures, fabrication, integration, and applications of MEMS for all kinds of biomedical imaging. This Special Issue aims to collate and showcase research papers, short commutations, perspectives, and insightful review articles from esteemed colleagues that demonstrate: (1) original works on the topic of MEMS components or devices based on various kinds of mechanisms for biomedical imaging; and (2) new developments and potentials of applying MEMS technology of any kind in biomedical imaging. The objective of this special session is to provide insightful information regarding the technological advancements for the researchers in the community

Molecular Imaging

The present book gives an exceptional overview of molecular imaging. Practical approach represents the red thread through the whole book, covering at the same time detailed background information that goes very deep into molecular as well as cellular level. Ideas how molecular imaging will develop in the near future present a special delicacy. This should be of special interest as the contributors are members of leading research groups from all over the world

New Techniques in Gastrointestinal Endoscopy

As result of progress, endoscopy has became more complex, using more sophisticated devices and has claimed a special form. In this moment, the gastroenterologist performing endoscopy has to be an expert in macroscopic view of the lesions in the gut, with good skills for using standard endoscopes, with good experience in ultrasound (for performing endoscopic ultrasound), with pathology experience for confocal examination. It is compulsory to get experience and to have patience and attention for the follow-up of thousands of images transmitted during capsule endoscopy or to have knowledge in physics necessary for autofluorescence imaging endoscopy. Therefore, the idea of an endoscopist has changed. Examinations mentioned need a special formation, a superior level of instruction, accessible to those who have already gained enough experience in basic diagnostic endoscopy. This is the reason for what these new issues of endoscopy are presented in this book of New techniques in Gastrointestinal Endoscopy

Endoscopic Fluorescence Imaging:Spectral Optimization and in vivo Characterization of Positive Sites by Magnifying Vascular Imaging

Since several decades, the physicians are able to access hollow organs with endoscopic methods, which serve both as diagnostic and surgical means in a wide range of disciplines of the modern medicine (e.g. urology, pneumology, gastroenterology). Unfortunately, white light (WL) endoscopy displays a limited sensitivity to early pre-cancerous lesions. Hence, several endoscopic methods based on fluorescence imaging have been developed to overcome this limitation. Both endogenous and exogenously-induced fluorescence have been investigated, leading to commercial products. Indeed, autofluorescence bronchoscopy, as well as porphyrin-based fluorescence cystoscopy, are now on the market. As a matter of fact, fluorescence-based endoscopic detection methods show very high sensitivity to pre-cancerous lesions, which are often overlooked in WL endoscopy, but they still lack specificity mainly due to the high false-positive rate. Although most of these false positives can easily be rejected under WL observation, tissue abnormalities such as inflammations, hyperplasia, and metaplasia are more difficult to identify, often resulting in supplementary biopsies. Therefore, the purpose of this thesis is to study novel, fast, and convenient method to characterize fluorescence positive spots in situ during fluorescence endoscopy and, more generally, to optimize the existing endoscopic setup. In this thesis, several clinical evaluations were conducted either in the tracheo-bronchial tree and the urinary bladder. In the urinary bladder, fluorescence imaging for detection of non-muscle invasive bladder cancer is based on the selective production and accumulation of fluorescing porphyrins, mainly protoporphyrin IX (PpIX), in cancerous tissues after the instillation of Hexvix® during one hour. In this thesis, we adapted a rigid cystoscope to perform high magnification (HM) cystoscopy in order to discriminate false from true fluorescence positive findings. Both white light and fluorescence modes are possible with the magnification cystoscope, allowing observation of the bladder wall with magnification ranging between 30× – for standard observation – and 650×. The optical zooming setup allows adjusting the magnification continuously in situ. In the high magnification regime, the smallest diameter of the field of view is 600 microns and the resolution is 2.5 microns, when in contact with the bladder wall. With this HM cystoscope, we characterized the superficial vascularization of the fluorescing sites in WL (370–700 nm) reflectance imaging in order to discriminate cancerous from non-cancerous tissues. This procedure allowed us to establish a classification based on observed vascular patterns. 72 patients subject to Hexvix® f luorescence cystoscopy were included in the study. Comparison of HM cystoscopy classification with histopathology results confirmed 32/33 (97%) cancerous biopsies, and rejected 17/20 (85%) non-cancerous lesions. No vascular alteration could be observed on the only positive lesion that was negative in HM mode, probably because this sarcomatoid carcinoma was not originating in the bladder mucosa. We established with this study that a magnification ranging between 80× and 100× is an optimal tradeoff to perform both macroscopic PDD and HM reflectance imaging. In order to make this approach more quantitative, different algorithms of image processing (vessel segmentation and skeletonisation, global information extraction) were also implemented in this thesis. In order to better visualize the vessels, we improved their contrast with respect to the background. Since hemoglobin is a very strong absorber, we targeted the two hemoglobin absorption peaks by placing appropriate bandpass filters (blue 405±50 nm, green 550±50 nm) in the light source. HM cystoscopy was then performed sequentially with WL, blue and green illumination. The two latter showed higher vessel-to-background contrast, identifying different layers of vascularization due to the light penetration depth. During fluorescence cystoscopy, we often observed that the images are somehow "blurred" by a greenish screen between endoscope tip and bladder mucosa. Since this effect is enhanced by the urine production, it is more visible with flexible scopes (lower flushing capabilities) and imaging systems that collect only autofluorescence as background. Indeed, when the bladder is not flushed regularly, greenish flows coming out of the ureters can easily be observed. For this reason, it is supposed that some fluorophores contained in the urine are excited by the photodetection excitation light, and appear greenish on the screen. This effect may impair the visualization of the bladder mucosa, and thus cancerous lesions, and lowers sensitivity of the fluorescence cystoscopy. In this thesis, we identified the main metabolites responsible for the liquid fluorescence, and optimized the spectral design accordingly. In the tracheo-bronchial tree, the fluorescence contrast is based on the sharp autofluorescence (AF) decrease on early cancerous lesions in the green spectral region (around 500 nm) and a relatively less important decrease in the red spectral region (> 600 nm) when excited with blue-violet light (around 410 nm). It has been shown over the last years, that this contrast may be attributed to a combined effect of epithelium thickening and higher concentration of hemoglobin in the tissues underneath the (pre-)cancerous lesions. In this thesis, we contributed to the definition of the input design of several new prototypes, that were subsequently tested in the clinical environment. We first showed that narrow-band excitation in the blue-violet could increase the tumor-to-normal spectral contrast in the green spectral region. Then, we quantified the intra- and inter-patient variations in the AF intensities in order to optimize the spectral response of the endoscopic fluorescence imaging system. For this purpose, we developed an endoscopic reference to be placed close to the bronchial mucosa during bronchoscopy. Finally, we evaluated a novel AF bronchoscope with blue-backscattered light on 144 patients. This new device showed increased sensitivity for pre-neoplastic lesions. Similar to what we observed in the bladder, it is likely that developing new imaging capabilities (including vascular imaging) will facilitate discriminating true from false positive in AF bronchoscopy. Here, we demonstrated that this magnification allowed us to resolve vessels with a diameter of about 30 µm. This resolution is likely to be sufficient to identify Shibuya's vascular criteria (loops, meshes, dotted vessels) on AF positive lesions. This criteria allow him to recognize pre-cancerous lesions, and thus can potentially decrease the false-positive rate with our AF imaging system. This magnification was also showed to be better for routine bronchoscopy, since it delivers sharper and more structured images to the operator

XXIV congreso anual de la sociedad española de ingeniería biomédica (CASEIB2016)

En la presente edición, más de 150 trabajos de alto nivel científico van a ser presentados en 18 sesiones paralelas y 3 sesiones de póster, que se centrarán en áreas relevantes de la Ingeniería Biomédica. Entre las sesiones paralelas se pueden destacar la sesión plenaria Premio José María Ferrero Corral y la sesión de Competición de alumnos de Grado en Ingeniería Biomédica, con la participación de 16 alumnos de los Grados en Ingeniería Biomédica a nivel nacional. El programa científico se complementa con dos ponencias invitadas de científicos reconocidos internacionalmente, dos mesas redondas con una importante participación de sociedades científicas médicas y de profesionales de la industria de tecnología médica, y dos actos sociales que permitirán a los participantes acercarse a la historia y cultura valenciana. Por primera vez, en colaboración con FENIN, seJane Campos, R. (2017). XXIV congreso anual de la sociedad española de ingeniería biomédica (CASEIB2016). Editorial Universitat Politècnica de València. http://hdl.handle.net/10251/79277EDITORIA