Clinical significance of trochlear calcifications in the orbit.

BACKGROUND AND PURPOSE: Trochlear calcification is frequently seen on CT scans that include the orbits, but prior studies linking this finding to diabetes mellitus were based on selected populations by using relatively thick sections. We assessed the relationship between trochlear calcification and diabetes mellitus and other chronic medical conditions in an unrestricted population by using thin-section CT. MATERIALS AND METHODS: Noncontrast head CT studies performed consecutively on 1000 patients between January and February 2011 were retrospectively reviewed for the presence of trochlear calcifications. Axial 1.25-mm-thick images acquired by 64-detector row CT were reviewed. Medical records were reviewed for chronic medical conditions, including diabetes mellitus, chronic kidney disease, alcoholism, autoimmune conditions, endocrine disorders, serum calcium and alkaline phosphatase levels, and HIV status. Motion-limited studies and patients with limited clinical data were excluded. Statistical analyses were performed by using the Fisher exact test. RESULTS: Thirty-two patients were excluded from analysis. Of the remaining 968 patients, 128 had trochlear calcification (13%). No significant association was observed between diabetes mellitus and trochlear calcifications in patients of any age (P = .40). There was no significant correlation between trochlear calcifications and chronic kidney disease, alcoholism, endocrine disorders, or HIV infection. Statistically significant associations among trochlear calcification, autoimmune conditions, and elevated alkaline phosphatase levels were observed (P < .0001 and P < .0001, respectively). CONCLUSIONS: On the basis of a large unrestricted population with thin-section CT imaging of the orbit, no significant association was observed between trochlear calcifications and diabetes mellitus. A statistically significant association was observed between trochlear calcification and autoimmune disease and elevated alkaline phosphatase levels.

STATISTICAL SHAPE ANALYSIS OF BRAIN STRUCTURES USING SPHERICAL WAVELETS.

We present a novel method of statistical surface-based morphometry based on the use of non-parametric permutation tests and a spherical wavelet (SWC) shape representation. As an application, we analyze two brain structures, the caudate nucleus and the hippocampus, and compare the results obtained to shape analysis using a sampled point representation. Our results show that the SWC representation indicates new areas of significance preserved under the FDR correction for both the left caudate nucleus and left hippocampus. Additionally, the spherical wavelet representation provides a natural way to interpret the significance results in terms of scale in addition to knowing the spatial location of the regions.

The sense of consciousness.

I propose that consciousness might be understood as the property of a system that functions as a sense in the biological meaning of that term. The theory assumes that, as a complex system, the sense of consciousness is not a fixed structure but implies structure with variations and that it evolved, as many new functions do, through the integration of simpler systems. The recognized exteroceptive and enteroceptive senses provide information about the organism's environment and about the organism itself that are important to adaptation. The sense of consciousness provides information about the brain and thus about the organism and its environment. It senses other senses and processes in the brain, selecting and relating components into a form that "makes sense"-where making sense is defined as being useful to the organism in its adaptation to the environment. The theory argues that this highly adaptive organizing function evolved with the growing complexity of the brain and that it might have helped resolve discrepancies created at earlier stages. Neural energies in the brain that are the input to the sense of consciousness, along with the processing subsystem of which they are a part, constitute the base of consciousness. Consciousness itself is an emergent effect of an organizing process achieved through the sense of consciousness. The sense of consciousness thus serves an organizing function although it is not the only means of organization in the brain. Its uniqueness lies in the character of the organization it creates with consciousness as a property of that organization. The paper relates the theory to several general conceptions-interactionism, epiphenomenalism and identity theory-and illustrates a number of testable hypotheses. Viewing consciousness as a property of a sense provides a degree of conceptual integration. Much of what we know about the evolution and role of the conventionally recognized senses should help us understand the evolution and role of the sense of consciousness, and of consciousness itself.

On the psychophysics of the shape triangle.

We earlier introduced an approach to categorical shape description based on the singularities (shocks) of curve evolution equations. We now consider the simplest compositions of shocks, and show that they lead to three classes of parametrically ordered shape sequences, organized along the sides of a shape triangle. By conducting several psychophysical experiments we demonstrate that shock-based descriptions are predictive of performance in shape perception. Most significantly, the experiments reveal a fundamental difference between perceptual effects dominated by when shocks form with respect to one another, versus those dominated by where they form. The shock-based theory provides a foundation for unifying tasks as diverse as shape bisection, recognition, and categorization.

Nondistorting flattening maps and the 3-D visualization of colon CT images.

In this paper, we consider a novel three-dimensional (3-D) visualization technique based on surface flattening for virtual colonoscopy. Such visualization methods could be important in virtual colonoscopy because they have the potential for noninvasively determining the presence of polyps and other pathologies. Further, we demonstrate a method that presents a surface scan of the entire colon as a cine, and affords the viewer the opportunity to examine each point on the surface without distortion. We use certain angle-preserving mappings from differential geometry to derive an explicit method for flattening surfaces obtained from 3-D colon computed tomography (CT) imagery. Indeed, we describe a general method based on a discretization of the Laplace-Beltrami operator for flattening a surface into the plane in a conformal manner. From a triangulated surface representation of the colon, we indicate how the procedure may be implemented using a finite element technique, which takes into account special boundary conditions. We also provide simple formulas that may be used in a real-time cine to correct for distortion.

Successful sealing of perforation of saphenous vein graft by coronary stent.

Coronary artery perforation is a rare occurrence during angioplasty and could lead to major complications requiring emergency surgical intervention. We describe a case of perforation of a saphenous vein graft during stenting. The perforation was successfully sealed by a second coronary stent.

Postradiation therapy adenosquamous cell carcinoma of the prostate.

The objective of this study was to present two cases of adenosquamous cell carcinoma of the prostate following radiation therapy. Two patients with history of prostate cancer treated with radiation therapy presented with rectal bleeding and a large ulcerated rectal mass. The rectal biopsy revealed on both cases squamous cell carcinoma. The initial diagnosis was invasive squamous cell carcinoma from anal origin. Both patients underwent pelvic exenteration with continent urinary diversion. After extensive histological sampling and immuno-histochemisty, they were correctly diagnosed of adenosquamous cell carcinoma of the prostate with invasion of the rectum. The patients died 6 and 16 months after surgery with widespread metastases. A review of the literature is presented. Adenosquamous cell carcinoma of the prostate is an unusual histological variant of prostate cancer. To our knowledge, only three cases of adenosquamous cell carcinoma of the prostate following radiation therapy have been reported. The unusual clinical and histopathological features of the two cases reported here led to an initial mistaken diagnosis. Adenosquamous cell carcinoma of the prostate should be considered in the differential diagnosis when a patient with prostate cancer develops a rectal mass or rectal bleeding following radiation therapy and the rectal biopsy reveals squamous cell carcinoma. Prostate Cancer and Prostatic Diseases (2000) 3, 53-56

Knowledge-based segmentation of SAR data with learned priors.

An approach for the segmentation of still and video synthetic aperture radar (SAR) images is described. A priori knowledge about the objects present in the image, e.g., target, shadow and background terrain, is introduced via Bayes' rule. Posterior probabilities obtained in this way are then anisotropically smoothed, and the image segmentation is obtained via MAP classifications of the smoothed data. When segmenting sequences of images, the smoothed posterior probabilities of past frames are used to learn the prior distributions in the succeeding frame. We show with examples from public data sets that this method provides an efficient and fast technique for addressing the segmentation of SAR data.

Improved detection of posterior myocardial wall ischemia with the 15-lead electrocardiogram.

BACKGROUND: A routine 12-lead electrocardiogram is commonly obtained to evaluate for possible acute myocardial infarction during the initial screening of patients with chest discomfort. Posterior myocardial infarction is commonly missed because it is not usually visible in the standard leads. In this study, we compared the sensitivity and specificity of posterior chest leads (V(7), V(8), and V(9)) and 12-lead electrocardiography in detecting posterior injury pattern during single-vessel percutaneous transluminal coronary angioplasty. METHODS AND RESULTS: Three posterior chest leads in addition to the routine 12-lead electrocardiogram were monitored simultaneously during single-vessel percutaneous transluminal coronary angioplasty of the right, circumflex, and left anterior descending coronary arteries in a total of 223 patients. Posterior injury patterns (95%) were detected mostly during circumflex coronary occlusion. Posterior leads were able to detect injury pattern in 49% (36 of 74) of patients, whereas the 12-lead electrocardiogram was able to detect only 32% (P <.04). When all 15 leads were used to detect all ST elevations, sensitivity increased to 57%, with a specificity of 98% for the circumflex coronary artery. If maximal ST depressions in leads V(2) to V(3) are considered to be from posterior myocardial injury, then the overall sensitivity is increased to 69%. CONCLUSIONS: Posterior leads significantly increased the detection of posterior injury pattern compared with the standard 12-lead electrocardiogram. Using all 15 leads significantly further improved the detection of circumflex coronary-related injury pattern over the standard 12-lead electrocardiogram.

On the Laplace-Beltrami operator and brain surface flattening.

In this paper, using certain conformal mappings from uniformization theory, we give an explicit method for flattening the brain surface in a way which preserves angles. From a triangulated surface representation of the cortex, we indicate how the procedure may be implemented using finite elements. Further, we show how the geometry of the brain surface may be studied using this approach.

Area and length minimizing flows for shape segmentation.

A number of active contour models have been proposed that unify the curve evolution framework with classical energy minimization techniques for segmentation, such as snakes. The essential idea is to evolve a curve (in two dimensions) or a surface (in three dimensions) under constraints from image forces so that it clings to features of interest in an intensity image. The evolution equation has been derived from first principles as the gradient flow that minimizes a modified length functional, tailored to features such as edges. However, because the flow may be slow to converge in practice, a constant (hyperbolic) term is added to keep the curve/surface moving in the desired direction. We derive a modification of this term based on the gradient flow derived from a weighted area functional, with image dependent weighting factor. When combined with the earlier modified length gradient flow, we obtain a partial differential equation (PDE) that offers a number of advantages, as illustrated by several examples of shape segmentation on medical images. In many cases the weighted area flow may be used on its own, with significant computational savings.

Electroencephalogram activity in the anoxic turtle brain.

The anoxia-tolerant turtle brain slowly undergoes a complex sequence of changes in electroencephalogram (EEG) activity as the brain systematically downregulates its energy demands. Following N2 respiration, the root mean square voltage rapidly fell, reaching approximately 20% of normoxic levels after approximately 100 min of anoxia. During the first 20- to 40-min transition period, the power of the EEG decreased substantially, particularly in the 12- to 24-Hz band, with low-amplitude slow wave activity predominating (3-12 Hz). Bursts of high voltage rhythmic slow (approximately 3-8 Hz) waves were seen during the 20- to 100-min period of anoxia, accompanied by large sharp waves. During the next 400 min of N2 respiration, two distinct patterns of electrical activity characterized the anoxic turtle brain: 1) a sustained but depressed activity level, with an EEG amplitude approximately 20% of the normoxic control and with total EEG power reduced by one order of magnitude at all frequencies, and 2) short (3-15 s) periodic (0.5-2/min) bursts of mixed-frequency activity that interrupted the depressed activity state. We speculate that the EEG patterns seen during sustained anoxia represent the minimal or basic electrical activities that are compatible with the survival of the anoxic turtle brain as an integrated unit, which allow the brain to return to normal functioning when air respiration resumed.

Does inflammation contribute to the eradication of basal cell carcinoma following curettage and electrodesiccation?

BACKGROUND: Curettage and electrodesiccation (C&D) is probably the technique most frequently utilized by dermatologists to treat basal cell carcinomas (BCC). From histologic studies, it appears C&D does not completely mechanically remove all nests of BCC in a substantial number of cases. Nevertheless, the reported 5-year reoccurrence rate following C&D is significantly less than this histologically observed residual tumor frequency immediately following C&D. Among the multiple possibilities that exist to explain why these residual nests do not appear as recurrent tumor more frequently is the theory that inflammation developing after C&D clears residual tumor. OBJECTIVE: To test the hypothesis that inflammation developing after C&D clears residual tumor not mechanically removed by the procedure. METHODS: The frequency of residual BCC detected histologically immediately following C&D was compared with the frequency 1 month after the C&D, an amount of time in which an effect (if any) of inflammation could occur. RESULTS: Twenty-two of 29 primary BCC < 1 cm treated by C&D were tumor free immediately following the procedure (clearance rate, 75.9%). Eleven of 14 primary BCC < 1 cm treated by C&D then allowed to granulate 1 month before excision and histologic analysis were tumor free, for a clearance rate of 78.6%. Examination of larger tumors immediately following C&D revealed size is a significant variable for clearance rates. Eleven primary BCC > 1 cm but < 2 cm were examined histologically immediately following C&D; only three were tumor free for a clearance rate of 27.3%. Only one of five tumors > 2 cm thus treated was tumor free, for a clearance rate of 20%. Nine recurrent BCC of various sizes were treated by C&D and immediately examined histologically. Two were tumor free for a clearance rate of 22.2%. Two recurrent BCC were allowed to heal 1 month following C&D; one of these was tumor free when excised. CONCLUSION: For primary BCC < 1 cm, no evidence was found that inflammation occurring over 1 month following C&D clears residual tumor. It was also noted that C&D fails to completely remove tumor in a large majority of primary BCC > 1 cm, and in recurrent BCC.

A geometric snake model for segmentation of medical imagery.

In this note, we employ the new geometric active contour models formulated in [25] and [26] for edge detection and segmentation of magnetic resonance imaging (MRI), computed tomography (CT), and ultrasound medical imagery. Our method is based on defining feature-based metrics on a given image which in turn leads to a novel snake paradigm in which the feature of interest may be considered to lie at the bottom of a potential well. Thus, the snake is attracted very quickly and efficiently to the desired feature.

Optical flow: a curve evolution approach.

A novel approach for the computation of optical flow based on an L (1) type minimization is presented. It is shown that the approach has inherent advantages since it does not smooth the flow-velocity across the edges and hence preserves edge information. A numerical approach based on computation of evolving curves is proposed for computing the optical flow field. Computations are carried out on a number of real image sequences in order to illustrate the theory as well as the numerical approach.

Behavioral analysis of anisotropic diffusion in image processing.

In this paper, we analyze the behavior of the anisotropic diffusion model of Perona and Malik (1990). The main idea is to express the anisotropic diffusion equation as coming from a certain optimization problem, so its behavior can be analyzed based on the shape of the corresponding energy surface. We show that anisotropic diffusion is the steepest descent method for solving an energy minimization problem. It is demonstrated that an anisotropic diffusion is well posed when there exists a unique global minimum for the energy functional and that the ill posedness of a certain anisotropic diffusion is caused by the fact that its energy functional has an infinite number of global minima that are dense in the image space. We give a sufficient condition for an anisotropic diffusion to be well posed and a sufficient and necessary condition for it to be ill posed due to the dense global minima. The mechanism of smoothing and edge enhancement of anisotropic diffusion is illustrated through a particular orthogonal decomposition of the diffusion operator into two parts: one that diffuses tangentially to the edges and therefore acts as an anisotropic smoothing operator, and the other that flows normally to the edges and thus acts as an enhancement operator.

Verapamil in the treatment of maternal paroxysmal supraventricular tachycardia.

Paroxysmal supraventricular tachycardia (PSVT) is seen somewhat frequently in the emergency department but less frequently during pregnancy. Although verapamil is widely used as the drug of choice for PSVT with a narrow QRS complex in a hemodynamically stable patient, the acute IV use of verapamil during pregnancy has not been well studied. Only a limited number of case reports document its safety and efficacy in the treatment of maternal or fetal PSVT. In general, the use of medication during pregnancy requires careful assessment of both the maternal and fetal risks versus benefits and documentation of patient consent. Because it crosses the placenta, one of the major concerns with the acute use of IV verapamil centers around the drug's potential effect on fetal heart rate. The case we present describes the occurrence of PSVT on two separate occasions in a woman in the third trimester of pregnancy. In both episodes, as much as 10 mg IV verapamil was given with resulting successful conversion to normal sinus rhythm. Fetal heart monitoring during drug administration failed to show significant change in fetal heart rate.