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Results for “computed tomography imaging”

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At least 145 records · Page 8Linked to original sources

PubMed2003

Magnetic resonance imaging, computed tomography, and cross-sectional views of the anatomy of normal nasal cavities and paranasal sinuses in mesaticephalic dogs.

OBJECTIVE: To use computed tomography (CT) and magnetic resonance imaging (MRI) to provide a detailed description of the nasal cavities and paranasal sinuses in clinically normal mesaticephalic dogs. ANIMALS: 2 clinically normal Belgian Shepherd Dogs that weighed 25 and 35 kg, respectively. PROCEDURE: The first dog was anesthetized and positioned in ventral recumbency for CT and MRI examinations, and transverse slices were obtained from the caudal part of the frontal sinuses to the nares. For MRI, T1-weighted, T2-weighted, and proton-density sequences were obtained. The second dog was anesthetized and positioned in dorsal recumbency with the head perpendicular to the table, and CT and MRI examinations were again conducted. At the completion of the MRI examination, each dog received an i.v. injection of heparin and then was euthanatized. A 4% solution of formaldehyde was perfused i.v. immediately after each dog was euthanatized. The skull was prepared, decalcified, embedded with gelatin, and sectioned into 5-mm-thick sections by use of a stainless-steel knife. Each anatomic section was photographed and compared with the corresponding CT and MRI views. RESULTS: Structures on the CT and MRI views matched structures on the corresponding anatomic sections. The CT scans provided good anatomic detail of the bony tissues, and MRI scans were superior to CT scans for determining soft-tissue structures. CONCLUSIONS AND CLINICAL RELEVANCE: CT and MRI provide a means for consistent evaluation of all structures of the nasal cavities and frontal sinuses. Both techniques could be useful for evaluation of diseases that affect the nasal region.

Animals↗

PubMedDate not supplied

The peanut orbit: a modified elliptical orbit for single-photon emission computed tomography imaging.

The front collimator surface of a conventional single-photon emission computed tomography (SPECT) detector system transcribing an elliptical orbit to approximate body contour could, under certain circumstances, penetrate the ellipse and make patient contact. The problem is associated both with the large front surface dimensions of tomographic cameras and the need to maintain the camera perpendicular to a radius through the axis of rotation. To aid in the development of an improved body contour orbit, software has been developed to simulate SPECT imaging systems. A major feature of the algorithms is a spatially calibrated graphic representation of the pallet, patient and orbit of the camera head. Based on computer simulations performed with this software, a modified elliptical orbit has been proposed for patient contour SPECT scanning on two different types of tomographic acquisition systems: a dual camera, rotating ring system and a single camera, multimotion stand system. This peanut orbit has the advantage of minimizing collimator patient distance, as does the elliptical orbit, but also compensates for camera motion that could potentially produce patient contact. Versions of the peanut orbit algorithms have been installed and are operational on clinical systems similar to those that were simulated. The ring-based gantry system (with cameras mounted on cantilevered arms) requires additional software to correct for translational shift in the field of view as a function of radial distance from the center of the system. This is done during uniformity correction. Standard unmodified backprojection software is used for reconstruction. The peanut orbit may represent an improved approach to body contour imaging in rotational SPECT.

Algorithms↗

PubMed2002

A comparison of conventional panoramic radiographs with volumetric computed tomography images in the preoperative assessment of impacted mandibular third molars.

PURPOSE: In the present study, we evaluated the geometric, topographic, and anatomic reliability of volumetric computed tomography (VCT) images by comparing conventional panoramic radiographs with reconstructed VCT panoramic and paraxial images before performing third molar surgery. PATIENTS AND METHODS: A total of 6 anatomic sites on 10 patients who showed a topographic relationship between the apices of the third molar root and the mandibular canal were preoperatively assessed by 5 oral surgeons using conventional panoramic radiographs; these were complemented and compared with secondary reconstructed paraxial and panoramic VCT images. RESULTS: The position of the apices in relation to the mandibular canal could be revealed on 94% of VCT reconstructed paraxial images. Assessment of VCT paraxial images could be facilitated by using a toolbar marker in 70% of the paraxial images. In 90% of the paraxial images, it was possible to assess the relationship of the mandibular canal and its adjacent anatomy. The visual grading scores for conventional panoramic images were significantly better on all 7 assessed anatomic sites compared with the reconstructed VCT panoramic images. CONCLUSION: The results showed that the VCT paraxial images gave a significantly clearer perception of the mandibular nerve than conventional panoramic radiographs. However, conventional panoramic radiographs were shown to be better than the VCT reconstructed panoramic images and were therefore an invaluable tool in the "expert-derived" assessment and posed the potential for identifying the need for further VCT diagnostic procedures.

Adult↗

PubMed1992

Computed tomography imaging of abdominal trauma in children.

The authors discuss the role of computed tomography (CT) in the evaluation of children following blunt abdominal trauma. Appropriate techniques for scanning children are described, as well as clinical indications that place children at high risk and low risk for abdominal injury. Examples of both solid organ and bowel injuries are shown, with special emphasis on the correlation of CT appearance and clinical outcomes. The authors conclude that CT is an effective tool for the diagnosis of abdominal injury in the pediatric patient, and that the clinical impact of CT appears to be changing with the increasing use of nonoperative therapy for solid organ injury.

Abdominal Injuries↗

PubMed1987

Regional brain hematocrit in stroke by single photon emission computed tomography imaging.

Nineteen studies on 18 subjects were performed by single photon emission computed tomography (SPECT) of the head after the successive intravenous administration of a plasma label (99mTc-human serum albumin [HSA]) and 99mTc-labeled autologous red blood cells (RBC). Two sets of cerebral tomographic sections were generated: for cerebral 99mTc-HSA alone and for combined 99mTc-HSA and 99mTc-RBC. By relating counts in regions of interest from the cerebral tomograms to counts from blood samples obtained during each tomographic acquisition, regional cerebral haematocrit (Hct) was calculated by the application of a simple formula. Results show 1) lower cerebral Hct than venous Hct (ratio of HCT brain/Hct venous 0.65-0.90) in all subjects, and 2) comparison between right and left hemisphere Hct in 3/3 normal subjects, 6/6 patients with transient ischaemic attacks and 3/8 patients with stroke showed no significant difference. However, in 3/8 patients with stroke (most recent strokes) significant differences were found, the higher Hct value corresponding to the affected side.

Adult↗

PubMedDate not supplied

Three-dimensional computed tomography imaging evidence of regeneration of the semitendinosus tendon harvested for anterior cruciate ligament reconstruction: a comparison with hamstring muscle strength.

OBJECTIVE: The purpose of this study was to evaluate the regeneration of semitendinosus tendons harvested for anterior cruciate ligament (ACL) reconstruction using 3-dimensional (3D) computed tomography (CT) imaging and to compare the degree of regeneration with hamstring strength. METHODS: Twenty-nine patients who underwent ACL reconstruction using ipsilateral autogenous semitendinosus tendons were examined before surgery and 6 and 12 months after surgery by 3D CT imaging. The types of regenerated tendons and the proximal shift of the muscle-tendon junction were evaluated. RESULTS: The types of regenerated semitendinosus tendons varied from case to case. There was a positive correlation between the peak torque ratio of the hamstring muscle strength and the proximal shift of the muscle-tendon junction 6 months after surgery. The proximal shift did not affect the peak torque ratio 12 months after surgery, however. CONCLUSIONS: A proximal shift of the muscle-tendon junction may help to explain the individual differences in early postoperative hamstring muscle strength recovery.

Adolescent↗

PubMed2004

Volume variation of mastoid pneumatization in different age groups: a study by three-dimensional reconstruction based on computed tomography images.

Although there have been some reports that measured the size of mastoid pneumatization, only a few studies have reported the age-related variations in the mastoid air cell system using three-dimensional (3D) reconstruction techniques of computed tomography (CT) images. We performed a retrospective, cross-sectional study. A 3D reconstruction based on CT images was performed on 199 ears of 102 patients (age range 6-84 years) without otologic disease by a surface-rendering algorithm. The results showed that mastoid pneumatization continued to grow until the third decade. Thereafter, it declined slowly, and then rapidly after the seventh decade. No statistically significant difference was found between male and female or between right and left sides. There was a significant difference between the larger and smaller sides of individuals. The volume measurement technique based on the 3D reconstruction technique reported here is widely available, highly accurate and easy to perform.

Adolescent↗

PubMed2005

Magnetic resonance imaging, computed tomography, and conventional X-ray in 3 cases of symmelia.

BACKGROUND: Symmelia is a rare birth defect, often combined with severe malformations of the urogenital system and the lower gastrointestinal tract. Additionally, a deformed pelvis and various degrees of separation of the lower limbs are present. CASES: We report the examination findings of 3 autopsy specimens of symmelia using magnetic resonance imaging (MRI) and computed tomography (CT) with 3-dimensional (3D) reconstructions, and conventional X-ray. CONCLUSIONS: MRI and CT with the addition of 3D visualization can be used additionally with autopsy and conventional X-ray images in the investigation of such complex anatomical abnormalities.

Ectromelia↗

PubMed1999

Characterization of an Unusual Right Atrial Mass by Echocardiography, Magnetic Resonance Imaging, Computed Tomography, and Angiography.

A right atrial mass was discovered by echocardiography in a 53-year-old man. A work-up consisting of magnetic resonance imaging and computed tomography studies established the diagnosis of atrial lipoma. The echocardiographic features are compared with the radiological findings, and the characteristics permitting differentiation of lipoma from other causes of cardiac masses are discussed. In this case, echocardiography not only permitted the initial identification of the mass but also proved to be useful in follow-up of its evolution over time, thereby influencing the therapeutic management.

Journal Article↗

PubMed2006

Correlation between maxillary sinus floor topography and related root position of posterior teeth using panoramic and cross-sectional computed tomography imaging.

OBJECTIVE: This study correlated the topographic relationship of the maxillary sinus floor to the roots of posterior teeth imaged by panoramic radiography and cross-sectional computed tomography (CT). STUDY DESIGN: Paired panoramic radiographs and CT images of maxillae from 80 subjects were analyzed. A total of 422 maxillary roots were classified according to their topographic relationship to the maxillary sinus and measured according to their projection lengths on the sinus cavity for both imaging modalities. Correlations between the 2 radiographic techniques were examined statistically. RESULTS: Teeth roots that did not contact the sinus floor or contacted it but did not project on the sinus cavity (classifications 0 and 1) showed a high agreement of 86% to 96% when using the 2 imaging techniques. Only 39% of the teeth roots that projected on the sinus cavity in panoramic radiographs (classification 3) showed protrusion into the sinus with CT. The panoramic radiographs showed a statistically significant 2.1 times longer root projection on the sinus cavity in comparison to the root protrusion length into the sinus measured by using CT images (P < .001). CONCLUSION: For the majority of the roots projecting on the sinus cavity in panoramic radiographs, no vertical protrusion into the sinus was observed in CT images. Roots that did protrude into the sinus in the CT showed a protrusion length that was much shorter than the projection length appearance using panoramic radiography.

Bicuspid↗

PubMed2005

Multi-detector row computed tomography: imaging the coronary arteries.

Over the last 2 years, multi-detector row computed tomographic (MDCT) cardiac imaging has continued to rapidly develop and evolve from the experimental research setting to become a useful clinical tool. The increasing availability of MDCT presents today's clinicians with an additional non-invasive diagnostic cardiac imaging method, in particular for the coronary arteries. With the advent and increasing clinical use of 16-detector row machines, and now with the imminent clinical emergence of 64-channel machines, the improvements in spatial and temporal resolution and sophisticated ECG-gating are allowing motion-free, fast, accurate, detailed, contrast-enhanced cardiac imaging that begins to approach the accuracy of traditional invasive diagnostic techniques. Additional diagnostic information may also be provided.

Algorithms↗

PubMedDate not supplied

Real-time 'computer-evaded' pseudo-holography of computed tomography images.

An off-line method of dynamic imaging has been developed to facilitate visualization of three-dimensional tomographic data during real-time manoeuvres. Stereo-pair projection of multiple contiguous cross-sectional images on a conventional 625 line 50 Hz television raster has been investigated and pseudo-holograms have been displayed. A Cartesian stereo-pair projection model incorporating three degrees of rotational freedom and perspective has been developed. Computer simulations of the model have been conducted and the feasibility of adopting a simplified model has been examined. A condensed solution with two degrees of freedom, retaining partial perspective effects, has been simulated and analysed for worst-case errors. Reasonable projection accuracy has been demonstrated for small orientation angles. Specialized display hardware has been developed and a departure has been made from conventional picture-element (pixel) display methodology. Elemental quadrilaterals (rho-pixels), varying in size, shape and screen position, have been considered as an alternative to static square pixels in a rigid matrix. Joystick-controlled rho-pixel arrays have been implemented with parallelogram-shaped rho-pixels incorporated as a simplified case of quadrilateral projection. Dynamic stereo-pair projections of 64 X 64 rho-pixel arrays have been generated from computed tomography (CT) images and the results of phantom studies on a four-plane system are discussed.

Computer Simulation↗

PubMed1997

Serial single photon emission computed tomography imaging in patients with cerebral lupus during acute exacerbation and after treatment.

Single photon emission computed tomography (SPECT) with [99mTc] HMPAO was performed sequentially every week in 4 patients with systemic lupus erythematosus (SLE), from the acute phase of neurologic involvement until normal cerebral blood flow (CBF) was detected by the scan. SPECT accurately reflects central nervous system (CNS) abnormalities in patients with SLE and correlates with subsequent improvement. Correlated with the patients' rapid clinical improvement, the brain SPECT blood flow scan demonstrated homogeneous distribution in 1 to 9 weeks. In these four patients, the defect in CBF could be reversed by optimal treatment. Brain SPECT blood flow scan may be used as a biologic marker of pathologic activity in the brain of patients with SLE.

Adolescent↗

PubMedDate not supplied

Increased radiodensity of the proximal pole of the scaphoid: a common finding in computed tomography imaging of the wrist.

OBJECTIVES: To determine whether the proximal pole (PP) of the scaphoid is denser than the distal pole (DP) in a diverse population of patients undergoing computed tomography (CT) imaging of the wrist. METHODS: Sixty-nine patients who had CT of the wrist were retrospective reviewed. We measured CT density of the medullary bone of PP and DP of the scaphoid and calculated PP/DP ratio. To evaluate the variability of PP/DP ratio, we compared the ratios of these 3 groups. These patients were separated into 3 groups based on their diagnoses: group 1, healed scaphoids treated by casting; group 2, scaphoid nonunions; group 3, intact scaphoids. RESULTS: Proximal pole was denser than DP in most subjects. Proximal pole/distal pole ratio was similar among groups (P < 0.05). Fracture healing, sex, and age did not affect this ratio. However, we did not study scaphoids with avascular necrosis. CONCLUSIONS: Proximal pole was denser than DP in most of our subjects, including those with intact scaphoids, healing scaphoid fractures, and nonunions.

Adult↗

PubMed1994

Technical note: evaluation of a region growing algorithm for segmenting pelvic computed tomography images during radiotherapy planning.

A clinical evaluation of a computer segmentation algorithm was performed to determine whether the incorporation of such an algorithm into a radiotherapy treatment planning computer would increase the speed of segmentation and therefore increase user productivity. Six pelvic computed tomography (CT) data cubes were manually segmented akin to current radiotherapy practice on three occasions and the mean times for each data cube recorded to provide baseline measurements. The same images were then segmented using the new region growing algorithm, backed up by manual segmentation and contour editing tools where necessary, and the times compared with the baseline for each data cube. The results confirm that this algorithm can decrease segmentation times by a factor of 2.4 without compromising the quality of the final plan (p < 0.0001). Most of this time gain is from a rapid segmentation of the pelvic bones and external contour rather than the soft tissues of the pelvis. We conclude that such algorithms will be of value for segmenting large pelvic CT data cubes for radiotherapy planning by making the procedure less labour intensive.

Algorithms↗

PubMed1991

Magnetic resonance imaging detection of early experimental periostitis. Comparison of magnetic resonance imaging, computed tomography, and plain radiography with histopathologic correlation.

This study characterizes the appearance of periosteal reaction by magnetic resonance imaging (MRI), and evaluates the efficacy of MRI versus computed tomography (CT), and plain film radiography (PF) in detecting early, experimentally induced periostitis. Acute Staphylococcus aureus osteomyelitis was induced in 30 legs of 20 New Zealand white rabbits. The rabbits were then imaged with MR, contrast-unenhanced CT, and PF 4 days after infection. Histologically, periosteal elevation was present in 27 cases. Periosteal ossification was seen in 23 cases, and cellular reaction without ossification in 4 cases. Periosteal reaction was demonstrated by PF in 21 (78%) and by CT in 20 (74%) cases. Evidence of periostitis was seen by MR in all 27% (100%) cases. MR resulted in two false-positive diagnoses. Multiple concentric, alternating high and low signal arcs demonstrated by MR in 19 (70%) cases represented periosteal ossification surrounded by fibrous or granulation tissue. These findings demonstrate the ability of MR to detect periostitis despite the absence of periosteal ossification. MR was more sensitive than CT (P less than .05) or PF (P less than .05) in the detection of experimentally induced periostitis.

Acute Disease↗

PubMed1977

Radionuclide imaging, computed tomography, and gray-scale ultrasonography of the liver: a comparative study.

Transmission computed tomography (CT), gray-scale ultrasonography, and scinitillation-camera imaging were compared for detection of intrahepatic space-occupying processes. Fifty patients with suspected liver disease were studied by the three modalities. In the 35 cases with confirmed abnormalities, the madalities were rated on a scale of 0 to 5 in terms of their detection value; Each modality was found to have definite advantages and disadvantages. The mean score of ultrasound was highest (3.61), followed by nuclear medicine (3.11) and then CT (2.77). The combination of ultrasound and nuclear medicine identified all lesions, whereas CT alone or in combination with another technique occasionally failed to detect abnormal foci. In the future, the relative efficacy of these procedures may change with improved imaging technology and increased interpreter experience.

Carcinoma, Hepatocellular↗

PubMed2005

A new approach for the estimation of intervertebral disc volume using the Cavalieri principle and computed tomography images.

This study was carried out to describe a simple, accurate and practical technique for estimating the volume of intervertebral disc (ID) by the combination of the Cavalieri principle and computed tomography (CT) images. Total eight lumbar IDs from two cadavers were CT scanned in axial, sagittal and coronal sections. The consecutive sections with 5 and 3mm thickness were used to estimate the volume of the IDs by the Cavalieri principle. Three investigators estimated the volume of IDs independently to evaluate inter-observer differences. When the results were compared to the real volumes of IDs measured by the fluid displacement technique, there was no significant difference between the real volume measurements and the Cavalieri estimation results of ID volumes (P > 0.05). Moreover, findings of three investigators did not show significant variations (P > 0.05). Our results indicate that the section thickness and the section planes did not affect the accuracy of the disc volume estimation. Thus the combination of CT scanning with the Cavalieri principle may be used as a direct and reliable technique to estimate the volume of IDs with a mean of 4 min workload per ID.

Adult↗