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Biomedical subjects

D L Collins

Publications and source records attributed to D L Collins.

70 records · Page 4Linked to original sources
PubMed1982

CT screening of the abdomen in von Hippel-Lindau disease.

Patients with von Hippel-Lindau disease often develop asymptomatic abdominal manifestations including renal cysts and carcinomas, pheochromocytomas, and pancreatic tumors and cysts. Early detection of renal carcinoma and pheochromocytoma is particularly important. Accordingly, periodic abdominal screening of affected individuals and at-risk family members is necessary. Abdominal computed tomography (CT) was performed in 31 subjects from three families. Fifteen had asymptomatic abdominal manifestations of von Hippel-Lindau disease including renal cysts in 13, renal carcinoma in four, pancreatic cysts in five, and pheochromocytomas in two. CT constitutes an excellent noninvasive screening technique for patients with possible abdominal involvement by von Hippel-Lindau disease.

Adenocarcinoma↗
PubMed1980

Familial joint instability syndrome.

We describe a family in which many persons have generalized joint laxity frequently complicated by dislocation of major joints. The condition is an autosomal dominant trait, with high penetrance. The disorder observed in this family and in others from the literature appears to be a specific syndrome that can be distinguished from other familial forms of joint laxity such as simple familial joint laxity and the Ehlers-Danlos syndromes. It has been designated the familial joint instability syndrome.

Adolescent↗
PubMed1977

A new approach to congenital posterolateral diaphragmatic hernia.

The theory is advanced that increased pulmonary vascular resistance, resulting in a state of fetal circulation, with right-to-left shunting through the ductus arteriosus, is the main reason that many patients do not survive after repair of a diaphragmatic hernia. Three patients are presented (who, by Raphaely's criteria, were destined for a fatal outcome) in whom the ductus was ligated, and vasodilator drugs were infused into the pulmonary artery. All three demonstrated definite improvement in oxygenation. Two expired after 6 days, one of whom was found at autopsy to have intestinal volvulus and gangrene, and the other multiple plumonary emboli. One case, so managed, survived. The suggestion is made that pulmonary hypoplasia is not the main reason for the high mortality rate after diaphragmatic hernia repair, and that additional laboratory and clinical investigation of the pulmonary circulation may lead to significant improvement in results.

Acetylcholine↗
PubMedDate not supplied

Multimodality image integration for stereotactic surgical planning.

A method is presented for integrating stereotactic projection and tomographic image data to give composite 3-D images (stereo pairs) of cerebral anatomy and vasculature. The technique serves to combine complementary information from each modality and allows the imaged volume to be viewed directly. The procedure is largely automated and requires no additional apparatus or information beyond that which is ordinarily employed during stereotactic surgical planning. The two types of data are combined by superimposing the projection angiogram (DSA) onto a translucent volume rendered CT or MR image. Since the rendering algorithm employs an orthographic projection technique, the tomographic volume must first be reshaped and oriented to yield a perspective view that matches the DSA projection. During this process, the data undergo various interpolations which consequently affect the accuracy of target identification based on the resulting images. The integrity of the matching procedure was assessed using simulated data sets. Also, calculations were performed to estimate the resolution of measurements made from digitized stereoscopic images. The resulting sub-pixel accuracy of the matched images suggests that the technique has potential for stereotactic applications. Preliminary results are presented illustrating combined CT-DSA and MR-DSA data sets.

Angiography, Digital Subtraction↗
PubMedDate not supplied

Analysis of projection geometry for few-view reconstruction of sparse objects.

In this paper certain projections are examined as to why they are better than others when used to reconstruct sparse objects from a small number of projections. At the heart of this discussion is the notion of "consistency," which is defined as the agreement between the object's 3-D structure and its appearance in each image. It is hypothesized that after two or more projections have been obtained, it is possible to predict how well as subsequent view will perform in terms of resolving ambiguities in the object reconstructed from only the first few views. The prediction is based on a step where views of the partial reconstruction are simulated and the use of consistency to estimate the effectiveness of a given projection is exploited. Here some freedom is presumed to acquire arbitrary as opposed to predetermined views of the object. The principles underlying this approach are outlined, and experiments are performed to illustrate its use in reconstructing a realistic 3-D model. Reflecting an interest in reconstructing cerebral vasculature from angiographic projections, the experiments employ simulations based on a 3-D wireframe model derived from an internal carotid arteriogram. It is found that for such an object, the predictions can be improved significantly by introducing a correction to account for the degree to which the object possesses some symmetry in shape. For objects sufficiently sparse, this correction is less important. It is concluded that when the number of projections is limited, it may be possible to favorably affect the reconstruction process in this manner.

Angiography, Digital Subtraction↗
PubMedDate not supplied

Automatic 3D intersubject registration of MR volumetric data in standardized Talairach space.

OBJECTIVE: In both diagnostic and research applications, the interpretation of MR images of the human brain is facilitated when different data sets can be compared by visual inspection of equivalent anatomical planes. Quantitative analysis with predefined atlas templates often requires the initial alignment of atlas and image planes. Unfortunately, the axial planes acquired during separate scanning sessions are often different in their relative position and orientation, and these slices are not coplanar with those in the atlas. We have developed a completely automatic method to register a given volumetric data set with Talairach stereotaxic coordinate system. MATERIALS AND METHODS: The registration method is based on multi-scale, three-dimensional (3D) cross-correlation with an average (n > 300) MR brain image volume aligned with the Talariach stereotaxic space. Once the data set is re-sampled by the transformation recovered by the algorithm, atlas slices can be directly superimposed on the corresponding slices of the re-sampled volume. the use of such a standardized space also allows the direct comparison, voxel to voxel, of two or more data sets brought into stereotaxic space. RESULTS: With use of a two-tailed Student t test for paired samples, there was no significant difference in the transformation parameters recovered by the automatic algorithm when compared with two manual landmark-based methods (p > 0.1 for all parameters except y-scale, where p > 0.05). Using root-mean-square difference between normalized voxel intensities as an unbiased measure of registration, we show that when estimated and averaged over 60 volumetric MR images in standard space, this measure was 30% lower for the automatic technique than the manual method, indicating better registrations. Likewise, the automatic method showed a 57% reduction in standard deviation, implying a more stable technique. The algorithm is able to recover the transformation even when data are missing from the top or bottom of the volume. CONCLUSION: We present a fully automatic registration method to map volumetric data into stereotaxic space that yields results comparable with those of manually based techniques. The method requires no manual identification of points or contours and therefore does not suffer the drawbacks involved in user intervention such as reproducibility and interobserver variability.

Algorithms↗
PubMedDate not supplied

Spatial disorientation episodes among F-15C pilots during Operation Desert Storm.

Spatial Orientation (SO) under flight conditions is the accurate "integration" of sensory inputs from the dynamic aviation environment that result in safe and effective goal-oriented performance. Insidious sensory mismatches routinely occur during flight, impeding pilot performance. When this sensory dissonance occurs, if not appropriately resolved, it will result in perceived or actual errors in aircraft control that are estimated to cost the Air Force between $150 and $200M per annum in aircraft accidents. A scientific survey was created and administered to 96 F-16C combat pilots after their return from Desert Storm. The survey sought to determine where in the flight profile, and under what conditions, spatial disorientation (SD) episodes occurred. The survey consisted of multiple choice and open-ended questions. The analyses of the data revealed that visual transitions from inside to outside the cockpit (or the reciprocal) under different conditions of flight were associated with the occurrence of SD episodes. The frequency of SD episodes varied depending on visual transitions (or no visual transitions) and types of flight conditions (for example, nighttime and bad weather). This SD survey provided flight information that allowed us to direct research to those areas that were problematic during combat operations.

Accidents, Aviation↗