Biomedical subjects

Celina Imielinska

Publications and source records attributed to Celina Imielinska.

7 recordsLinked to original sources

PubMed2006

A framework for evaluating image segmentation algorithms.

The purpose of this paper is to describe a framework for evaluating image segmentation algorithms. Image segmentation consists of object recognition and delineation. For evaluating segmentation methods, three factors-precision (reliability), accuracy (validity), and efficiency (viability)-need to be considered for both recognition and delineation. To assess precision, we need to choose a figure of merit, repeat segmentation considering all sources of variation, and determine variations in figure of merit via statistical analysis. It is impossible usually to establish true segmentation. Hence, to assess accuracy, we need to choose a surrogate of true segmentation and proceed as for precision. In determining accuracy, it may be important to consider different 'landmark' areas of the structure to be segmented depending on the application. To assess efficiency, both the computational and the user time required for algorithm training and for algorithm execution should be measured and analyzed. Precision, accuracy, and efficiency factors have an influence on one another. It is difficult to improve one factor without affecting others. Segmentation methods must be compared based on all three factors, as illustrated in an example wherein two methods are compared in a particular application domain. The weight given to each factor depends on application.

Algorithms↗

PubMed2005

Toward objective quantification of perfusion-weighted computed tomography in subarachnoid hemorrhage: quantification of symmetry and automated delineation of vascular territories.

RATIONALE AND OBJECTIVES: Perfusion-weighted computed tomography (CTP) is a relatively recent innovation that estimates a value for cerebral blood flow (CBF) using a series of axial head CT images tracking the time course of a signal from an intravenous contrast bolus. MATERIALS AND METHODS: CTP images were obtained using a standard imaging protocol and were analyzed using commercially available software. A novel computer-based method was used for objective quantification of side-to-side asymmetries of CBF values calculated from CTP images. RESULTS: Our method corrects for the inherent variability of the CTP methodology seen in the subarachnoid hemorrhage (SAH) patient population to potentially aid in the diagnosis of cerebral vasospasm (CVS). This method analyzes and quantifies side-to-side asymmetry of CBF and presents relative differences in a construct termed a Relative Difference Map (RDM). To further automate this process, we have developed a unique methodology that enables a computer to delineate vascular territories within a brain image, regardless of the size and shape of the brain. CONCLUSIONS: While both the quantification of image symmetry using RDMs and the automated assignment of vascular territories were initially designed for the analysis of CTP images, it is likely that they will be useful in a variety of applications.

Adult↗

PubMed2005

A novel drill set for the enhancement and assessment of robotic surgical performance.

BACKGROUND: There currently exist several training modules to improve performance during video-assisted surgery. The unique characteristics of robotic surgery make these platforms an inadequate environment for the development and assessment of robotic surgical performance. METHODS: Expert surgeons (n=4) (>50 clinical robotic procedures and >2 years of clinical robotic experience) were compared to novice surgeons (n=17) (<5 clinical cases and limited laboratory experience) using the da Vinci Surgical System. Seven drills were designed to simulate clinical robotic surgical tasks. Performance score was calculated by the equation Time to Completion + (minor error) x 5 + (major error) x 10. The Robotic Learning Curve (RLC) was expressed as a trend line of the performance scores corresponding to each repeated drill. RESULTS: Performance scores for experts were better than novices in all 7 drills (p<0.05). The RLC for novices reflected an improvement in scores (p<0.05). In contrast, experts demonstrated a flat RLC for 6 drills and an improvement in one drill (p=0.027). CONCLUSION: This new drill set provides a framework for performance assessment during robotic surgery. The inclusion of particular drills and their role in training robotic surgeons of the future awaits larger validation studies.

Clinical Competence↗

PubMed2004

New views of male pelvic anatomy: role of computer-generated 3D images.

There is considerable controversy concerning the role of cadaveric dissection in teaching gross anatomy and the potential of using 3D computer-generated images to substitute for actual laboratory dissections. There are currently few high-quality 3D virtual models of anatomy available to evaluate the utility of computer-generated images. Existing 3D models are frequently of structures that are easily examined in three dimensions by removal from the cadaver, i.e., the heart, skull, and brain. We have focused on developing a 3D model of the pelvis, a region that is conceptually difficult and relatively inaccessible for student dissection. We feel students will benefit tremendously from 3D views of the pelvic anatomy. We generated 3D models of the male pelvic anatomy from hand-segmented color Visible Human Male cryosection data, reconstructed and visualized by Columbia University's in-house 3D Vesalius trade mark Visualizer.(1) These 3D models depict the anatomy of the region in a realistic true-to-life color and texture. They can be used to create 3D anatomical scenes, with arbitrary complexity, where the component anatomical structures are displayed in correct 3D anatomical relationships. Moreover, a sequence of 3D scenes can be defined to simulate actual dissection. Structures can be added in a layered sequence from the bony framework to build from the "inside-out" or disassembled much like a true laboratory dissection from the "outside-in." These 3D reconstructed anatomical models can provide views of the structures from new perspectives and have the potential to improve understanding of the anatomical relationships of the pelvic region (http://www.cellbiology.lsuhsc.edu/People/Faculty/Venuti_Figures/movie_index.html).

Anatomy, Cross-Sectional↗

PubMed2003

Adipose tissue quantification by imaging methods: a proposed classification.

Recent advances in imaging techniques and understanding of differences in the molecular biology of adipose tissue has rendered classical anatomy obsolete, requiring a new classification of the topography of adipose tissue. Adipose tissue is one of the largest body compartments, yet a classification that defines specific adipose tissue depots based on their anatomic location and related functions is lacking. The absence of an accepted taxonomy poses problems for investigators studying adipose tissue topography and its functional correlates. The aim of this review was to critically examine the literature on imaging of whole body and regional adipose tissue and to create the first systematic classification of adipose tissue topography. Adipose tissue terminology was examined in over 100 original publications. Our analysis revealed inconsistencies in the use of specific definitions, especially for the compartment termed "visceral" adipose tissue. This analysis leads us to propose an updated classification of total body and regional adipose tissue, providing a well-defined basis for correlating imaging studies of specific adipose tissue depots with molecular processes.

Adipose Tissue↗

PubMed2003

Augmented Reality for teaching endotracheal intubation: MR imaging to create anatomically correct models.

Clinical procedures have traditionally been taught at the bedside, in the morgue and in the animal lab. Augmented Reality (AR) technology (the merging of virtual reality and real objects or patients) provides a new method for teaching clinical and surgical procedures. Improved patient safety is a major advantage. We describe a system which employs AR technology to teach endotracheal intubation, using the Visible Human datasets, as well as MR images from live patient volunteers.

Computer Simulation↗

PubMed2003

Development of a training tool for endotracheal intubation: distributed augmented reality.

The authors introduce a tool referred to as the Ultimate Intubation Head (UIH) to train medical practitioners' hand-eye coordination in performing endotracheal intubation with the help of augmented reality methods. In this paper we describe the integration of a deployable UIH and present methods for augmented reality registration of real and virtual anatomical models. The assessment of the 52 degrees field of view optics of the custom-designed and built head-mounted display is less than 1.5 arc minutes in the amount of blur and astigmatism, the two limiting optical aberrations. Distortion is less than 2.5%. Preliminary results of the registration of a physical phantom mandible on its virtual counterpart yields less than 3mm rms. in registration. Finally we describe an approach to distributed visualization where a given training procedure may be visualized and shared at various remote locations. Basic assessments of delays within two scenarios of data distribution were conducted and reported.

Computer Simulation↗