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At least 307 records · Page 17Linked to original sources
PubMed1998

Pinhole SPECT imaging in normal and morbid ankles.

UNLABELLED: Pinhole SPECT can generate sectional nuclear images of a normal and morbid ankle and hindfoot with remarkably enhanced resolution by portraying the topography and pathological alterations in great detail. METHODS: Pinhole SPECT was performed using a commercially available single-head, rotating gamma camera system by replacing the parallel-hole collimator used for planar SPECT with a pinhole collimator. The images were reconstructed in the same way as in planar SPECT by using the filtered back-projection algorithm and a Butterworth filter. First, we compared the scan resolution between the planar and pinhole SPECT images of a thyroid phantom and a normal ankle and hindfoot by working out pinhole SPECT anatomy with CT validation. Second, the clinical usefulness was assessed in one case each of fracture, reflex sympathetic dystrophy syndrome and rheumatoid arthritis of the ankle with radiographic correlation. The resolution of the pinhole SPECT and planar pinhole images was compared for these diseases. RESULTS: The resolution of the pinhole SPECT of a thyroid phantom and of a normal ankle and hindfoot was significantly enhanced compared to the planar SPECT although image distortion was seen in the periphery of the field-of-view. The pinhole SPECT resolution was such that most of the anatomical landmarks were sharply delineated in the ankle and hindfoot and some useful diagnostic signs in the diseased ankle were visible. CONCLUSION: Pinhole SPECT can be performed using a single-head gamma camera system and filtered back-projection algorithm. It generates sectional scan images of both normal and morbid ankle and hindfoot with enhanced resolution portraying many anatomical landmarks and pathological signs in useful detail.

Adult↗
PubMed2005

The photography of bruises.

This pilot study demonstrates four different photographic lighting techniques (using visible, red free, infrared and ultraviolet) with digital technology to record a bruise. It is suggested that it may be possible to record accurately the size of a bruise at different stages from injury to healing, using one or more of these techniques.

Contusions↗
PubMed2006

Scatter radiation in cephalometric radiography: the effects of grid and collimation.

OBJECTIVES: To measure the scatter fraction in cephalometric radiography with and without a grid and to estimate the patient's dose reduction by using a specially fabricated collimator without a grid. METHODS: A 16 cm thick water-equivalent phantom was used to measure the scatter fraction. The projection geometry was the same as our conventional one, i.e. the distance from the X-ray source to the centre of the phantom was 200 cm. A photostimulable phosphor plate was used as an X-ray sensor and was 20 cm from the centre of the phantom. The measurements were performed in four combinations: with an antiscatter grid in place, with a specially fabricated collimator in place, with neither in place, and with both in place. The images of a human dried skull were obtained by using the above parameters and were subjectively assessed for a visibility of several reference points. RESULT: The scatter fraction in the regularly collimated geometry with the antiscatter grid in place was 0.35 for a relative exposure of 1. With the antiscatter grid removed, the scatter fraction increased to 0.68, but the relative exposure was reduced to 0.3. With a special collimator, the scatter fraction was reduced to some extent in all instances, but the exposure was reduced to 0.45. The visibility of the reference points was acceptable in all conditions. CONCLUSION: In cephalometric radiography, removal of the antiscatter grid yields a significant reduction in exposure with no significant loss of information.

Cephalometry↗
PubMed1988

Factors affecting visualization of posterior rib fractures in abused infants.

Rib fractures frequently are encountered in abused infants and commonly occur in the posterior rib arcs. Fractures occurring near the costovertebral articulations are rarely identified radiographically in the acute phase, and callus formation usually is the first indication of injury. To assess the factors influencing the visibility of fractures near the costovertebral articulations in abused infants, 103 posterior rib fractures occurring in 16 abused infants were studied radiologically. The plain radiologic studies were correlated with the pathologic findings in 15 ribs from four patients. The limited visibility of fractures relates to (1) the frequent superimposition of the transverse process over the rib fracture site, (2) a fracture line that crosses at an obliquity to the radiographic beam, and (3) nondisplacement of rib fragments due to preservation of the posterior periosteum. Fresh fractures invisible on a frontal projection are clearly defined when the rib is viewed axially with postmortem radiography. These findings explain the reported superior sensitivity of radionuclide bone scans vs radiography in the identification of fresh posterior rib fractures. A knowledge of the factors influencing the visibility of these important injuries is useful in planning an appropriate diagnostic evaluation in cases of suspected infant abuse.

Child Abuse↗
PubMed1999

A case of reconstruction of saddle nose deformity in leprosy.

A case of reconstructive surgery for saddle nose deformity is presented in this paper. A 22 year-old Bengali female who had completed WHO/MB regimen for 27 months underwent reconstructive surgery for saddle nose deformity. Since a saddle nose is one of the symbols of leprosy, it often causes serious psychological and social troubles to patients. This happens more often when the patient is a young unmarried woman. In this case the saddle nose seemed to be very serious. After being discharged from hospital she got married and had a baby. This operation gave the patient great relief to live in the community, because she no longer had serious visible evidence of leprosy on the body. Though the correction of the deformity without any dysfunction does not always have priority over other surgeries at a busy leprosy control project in Bangladesh, it has merit both in patients themselves and in the society around them because it leads to the elimination of the stigma of leprosy.

Adult↗
PubMed1999

MR high-resolution blood oxygenation level-dependent venography of occult (low-flow) vascular lesions.

A new technique for detecting vascular malformations, high-resolution BOLD venography (HRBV), is described. This technique relies on the BOLD principle for detecting deoxygenated blood in low-flow malformations. HRBV images are acquired using a modified 3D gradient-echo with voxel volumes of 0.5 x 0.5 x 2 mm3. The magnitude data are masked with the phase images to enhance visibility of the venous structures and are displayed using the minimum intensity projection. Preliminary results for 10 patients show that HRBV is more sensitive in detecting cavernomas than is T2-weighted imaging, and lesions that are presumed to be telangiectasias are detected only with this technique.

Brain↗
PubMed2005

Visibility of normal thoracic anatomic landmarks on storage phosphor digital radiography versus conventional radiography.

BACKGROUND: Chest radiography is still the most frequently performed radiologic imaging study. Digital radiography is gradually replacing the conventional systems. OBJECTIVES: To compare the subjective visibility of normal anatomic landmarks in the chest on storage phosphor-based digital radiographs versus conventional screen-film radiographs. METHODS: Digital phosphor-based and screen-film posteroanterior chest radiographs were obtained during 1 year in 140 asymptomatic patients without any known pulmonary disease (119 men, 21 women; mean age 52.1 years, range 23-86). Both sets of films were independently compared by two experienced radiologists in different sessions. The visibility of each of the following anatomic landmarks was graded from 1 to 3: pulmonary fissures, carina, bronchi to left upper lobe, right upper lobe and left lower lobe, bronchus intermedius, anterior and posterior junctional lines, and vessels behind the heart and diaphragm. Additionally, subjective general quality impression of each radiograph was graded similarly. Statistical analyses were performed using the chi-square test. A P value less than 0.05 was considered significant. RESULTS: Visibility with the digital images was statistically significantly higher for the carina, left lower lobe bronchus, bronchus intermedius, and vessels behind the heart and diaphragm. Subjective general quality impression of digital radiographs was also higher (P < 0.001). No significant visibility differences were found for pulmonary fissures or junctional lines. CONCLUSION: Subjective visibility of anatomic structures behind the heart and diaphragm and at the hilae is significantly improved with phosphor-based digital radiography compared with conventional screen-film radiography. This suggests that pathologic processes such as pulmonary nodules, masses or consolidations projected over those structures may be more easily and reliably depicted on digital than on conventional chest X-rays.

Adult↗
PubMed2006

Visual stimulus-induced changes in human near-infrared fundus reflectance.

PURPOSE: Imaging studies from anesthetized feline, primate, and human retinas have revealed near-infrared fundus reflectance changes induced by visible light stimulation. In the present study, the spatial and temporal properties of similar changes were characterized in normal, awake humans. METHODS: Five normal human subjects were studied. A modified fundus camera was used to image changes in retinal reflectance of 780-nm near-infrared light imaged onto a 12-bit charge-coupled device (CCD) camera in response to a green (540 nm) visual stimulus. During 60 seconds of recording (frame rate, 3 Hz) 10 cycles were recorded, during each of which 3 seconds of blank and then 3 seconds of either vertical bar or blank stimulus was projected. The change in the average near-infrared reflectance of the stimulated retinal region relative to an equal-sized nonstimulated region (r is the ratio of reflectance between the two retinal areas) was analyzed with a mixed model for repeated measures. RESULTS: The mixed model showed a significant average decrease in r of 0.14% (95% CI, -0.25 to -0.03) over all subjects induced by bar stimulus cycles, with a gradual return to baseline after stimulus offset, compared with only a 0.04% (95% CI, -0.11-+0.20) decrease in r induced by blank, nonstimulated cycles. The mixed model for individuals showed a decreasing linear trend in r over time during bar stimulation, but no decrease for blank cycles in three of five subjects. CONCLUSIONS: There was a localized decrease in reflectance in response to 780-nm near-infrared light in the retinal region exposed to a visual stimulus, which was significant in three of five subjects. It is presumed that the reflectance change represents the functional activity of the retina in response to a visual stimulus.

Adult↗
PubMed1990

Using the Sensory Integration and Praxis Tests to measure change: a pilot study.

Nineteen boys aged 6 through 8 years were pretested with the preliminary edition of the Sensory Integration and Praxis Tests (SIPT) (Ayres, 1984). They subsequently received 6 months of twice weekly occupational therapy with sensory integration intervention in a school setting and were then posttested with the preliminary edition of the SIPT. Significant improvement was seen in scores of grouped data on tests of praxis, somatovestibular functioning, and bilateral integration and sequencing. Individual improvement was visible in the Western Psychological Services ChromaGraphs of 17 of the 19 boys. Although preliminary, these findings suggest that the SIPT, unlike the Southern California Sensory Integration Tests (Ayres, 1972a), may be used to document improvement in children who have received occupational therapy with sensory integrative techniques.

Child↗
PubMed1952

Observations with the electron microscope on cells of the chick chorio-allantoic membrane infected with influenza virus.

Preparations of influenza-infected chick chorio-allantoic membrane made by two types of tissue culture and by sectioning, have been studied in the electron microscope. Comparisons have been made of influenza A' (FM1), influenza A (PR8), and swine influenza (V15), three strains which produce different relative numbers of filaments. Normal surface projections which may be confused with influenza filaments are described. Extruded products of degenerating cells, usually bleb-shaped, may also be found both in uninfected allantoic fluid and tissue cultures. It appears that the filaments and spheres of influenza virus, concurrently projecting from the free cell surface, represent the only visible change in the cells until late in the infection,-how late the present work does not tell. No definite evidence of a generalized infection throughout the cytoplasm or of inclusions was found. Additional evidence is presented for the assumption that the filaments have a significant role in the final development of the free virus.

Allantois↗
PubMed1984

Concentric reduction of the dislocated hip. Computed-tomographic evaluation.

Concentric reduction of a dislocated hip can be evaluated by anteroposterior views or linear tomography. Anterior relationships, however, may be difficult to evaluate from a frontal radiograph despite good visibility. Computed tomography (CT), because of its cross-sectional imaging capabilities, is superior in demonstrating these relationships. The CT appearance of two types of dislocations (posterior and lateral) is described. A posterior dislocation should be suspected if the femoral metaphysis approximates the acetabulum, a mass projects behind the ischium, or the fat plane anterior to the gluteus maximus is deformed or displaced posteriorly.

Female↗
PubMedDate not supplied

Interactive voxel surface rendering in medical applications.

Semi-boundary (SB) data structure is a compact voxel surface representation of the structure from the medical images. It represents only the boundary of the extracted structure and only an opaque object boundary involved in a 3D dataset can be visualized. Its computational complexity is in proportion to the number of SB voxels. In this paper, we propose schemes to reduce the number of projections in two ways. First, in conjunction with neighboring code, we exploit a set of visibility tables to cull some of the invisible SB voxels. Second, we exploit three pass rotations and an incremental approach to quickly determine the projection position for each SB voxel during rendering. With these two combinations, we significantly improve SB rendering performance. As a result, we can achieve an interactive rendering speed on general purpose workstations for our medical applications.

Algorithms↗
PubMed1979

Measurement of vessel tortuosity on fundus photographs.

Quantitative measurement of vessel tortuosity and its variation on fundus photographs is a sensitive means of obtaining information about the course of an asphyctic event in newborns, virtually independent of bias produced by the photographic process. We subdivide a tortuous vessel into single arcs and measure the chord length and the arrow height (Pfeilhöhe) of every arc on a projected image of the film. From these figures, a fairly accurate value for the relative length increase of the arc, as compared with the chord, can be derived by a simple approximation formula [Eq. (5)]. It is shown that neglect of the third dimension, not visible on an ordinary photograph, entails only a small error. Trained observers achieve results reproducible to about 1% in relative length variation.

Asphyxia Neonatorum↗
PubMed2003

The effect of texture relief on perception of slant from texture.

Texture can be an effective source of information for perception of slant and curvature. A computational assumption required for some texture cues is that texture must be flat along a surface. There are many textures which violate this assumption, and have some sort of texture relief: variations perpendicular to the surface. Some examples include grass, which has vertical elements, or scattered rocks, which are volumetric elements with 3-D shapes. Previous studies of perception of slant from texture have not addressed the case of textures with relief. The experiments reported here test judgments of slant for textures with various types of relief, including textures composed of bumps, columns, and oriented elements. The presence of texture relief was found to affect judgments, indicating that perception of slant from texture is not robust to violations of the flat-texture assumption. For bumps and oriented elements, slant was underestimated relative to matching flat textures, while for columns textures, which had visible flat top faces, perceived slant was equal or greater than for flat textures. The differences can be explained by the way different types of texture relief affect the amount of optical compression in the projected image, which would be consistent with results from previous experiments using cue conflicts in flat textures. These results provide further evidence that compression contributes to perception of slant from texture.

Analysis of Variance↗
PubMedDate not supplied

Mentorship in physical medicine and rehabilitation residencies.

Mentorship is considered by many authorities as being possibly the most important developmental tool for the progression of a professional in training. In recent years, progressively increasing support of mentoring programs has been documented, especially in business, academia, and overall career development. Despite its recognized importance, there is a paucity of literature examining the needs of physicians in residency training programs in regard to mentorship. A 21-item questionnaire was sent to all physical medicine and rehabilitation (PM&R) residents in training in United States residency programs in May of 1993. The objectives of this survey were 3-fold: to assess interest in mentorship among PM&R residents, to determine the effect of preresidency mentorship on candidates choosing PM&R as a specialty, and to identify the factors that establish a successful mentorship in PM&R residency. A response rate of 36.2% (406/1123) was obtained. Analysis of the results indicated that 97.3% (390/401) of the respondents were interested in mentorship programs during PM&R residency; however, only 28.1% (114/406) had a mentor at the time of the survey. Before residency, 35.4% (143/404) of the respondents had a mentor, and of those, 75.9% (107/141) indicated that mentorship had a positive effect on their decision to choose PM&R as a specialty. Regarding the current mentorship, respondents benefited the most in the categories of increased knowledge of PM&R, 72.8% (83/114), and improved clinical skills, 65.8% (75/114). The least satisfaction was with the mentor's assistance with a research project, 46% (52/113), and with the effect of mentorship on the resident's visibility and reputation, 38.6% (44/114). Overall resident satisfaction with mentorship was significantly higher (P < 0.0001) in mentorships formed by free choice compared with those that were formally assigned by the residency program. Success of mentorship significantly correlated (P < 0.0001) with frequency of communication between mentor and protégé, while gender and ethnicity had no effect.

Female↗
PubMed2005

Panoramic views for virtual endoscopy.

This paper describes a panoramic projection designed to increase the surface visibility during virtual endoscopies. The proposed projection renders five faces of a cubic viewing space into the plane in a continuous fashion. Using this real-time and interactive visualization technique as a screening method for colon cancer could lead to significantly shorter evaluation time. It avoids having to fly through the colon in both directions and prevents the occlusion of potential polyps behind haustral folds.

Algorithms↗
PubMed2004

Augmented reality laser projection device for surgery.

We have developed an augmented reality system capable of projecting preoperative plans directly onto a patient using rapidly scanned laser beams. Projected contours can typically represent cut paths, tumors or delineate boundaries of interest. The system can be used as part of, or a replacement for, conventional robotic Telesurgery systems. Because the graphics are projected, there is no degradation in surgeon's view due to optical components interposed between the surgeon's eye and the patient. This system has been designed to work with a common infrared 3D camera system used in image-guided surgery, and projects both visible and infrared beams. The IR beam enables surface digitization functions to be carried out using the camera. The clinical accuracy is in the range required by CAS procedures, around 1-2mm. The device will be particularly useful for executing precise preoperative plans and for teleconsultation applications, where planned or live consultations can be efficiently communicated to a less skilled local caregiver.

Canada↗