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At least 199 records · Page 11Linked to original sources
PubMed1995

Mathematical determination of the tibial insertion of the patellar tendon using computed tomography images.

Misalignment of the extensor apparatus is an essential factor in impairment of the patellar-femoral joint. This may be partly or entirely responsible for patellar dislocation or lateral patellar-femoral arthrosis. One surgical method to correct the pathology is medial transposition of the patellar ligament on the tibial tuberosity (anteriorly or posteriorly, distally or ventrally). These interventions correct misalignment of the extensor apparatus relative to statistical norms. We propose a mathematical method based on the use of computed tomography (CT) images to determine the ideal tibial insertion for the patellar tendon. This method is based on biomechanical modeling and the use of equipressure criteria. It is the first step in allowing the use of mathematics to model correctly tibial insertion of the patellar ligament, an entirely new development. This is important because it will allow surgeons greater accuracy in distal correction of extensor apparatus misalignments.

Biomechanical Phenomena↗
PubMed1997

Three-dimensional computed tomography imaging of a frontal skull base fracture.

A 7-year-old boy presented with recurrent meningitis after head trauma. Coronal computed tomography (CT) revealed prolapse of the intracranial soft tissue into the right ethmoidal sinus, leading to the diagnosis of right frontal skull base fracture. Three-dimensional CT with bone windows provided a lifelike image of the fracture lateral to the right olfactory groove. This image was most useful in the preoperative planning of the repair surgery.

Child↗
PubMed1997

Cine magnetic resonance imaging, computed tomography and ultrasonography in the evaluation of chest wall invasion of lung cancer.

PURPOSE: To assess the usefulness of cine-magnetic resonance imaging (cine-MRI)in the evaluation of chest wall invasion, we compared the results of cine-MRI with those of computed tomography (CT) and ultrasonography (US). MATERIALS AND METHODS: Eleven patients were examined who had no pain and who were difficult to diagnose by routine examinations. MRI was performed with a Magnetom SP/4000, 1.5T unit (Siemens, Germany). For cine imaging, continuous turbo-FLUSH (ultra fast low angle shot) images were obtained at an orthogonal section to the chest wall during slow deep breathing. A CT scan was performed using a TCT 900S or Super Helix (Toshiba, Japan) at 1 cm intervals, with section thicknesses of 1 cm throughout the entire chest. US was performed with a model SSA-270A (Toshiba, Japan) with 7.5-MHz linear array scanners (PLF-705S; Toshiba, Japan). RESULTS: Sensitivity, specificity and accuracy were 67%, 75% and 73% for cine MRI, 67%, 63% and 64% for CT, 33%, 75% and 64% for US, respectively. CONCLUSIONS: These results indicate that cine MRI is potentially useful for the diagnosis of chest wall invasion of lung cancer.

Evaluation Studies as Topic↗
PubMed1978

Standardization of computed tomography images by means of a material-selective beam hardening correction.

Polychromaticity of the X-rays used in computed tomography (CT) has made it difficult to establish an absolute scale for CT values and has made quantitative comparisons between patients unreliable. The spectral shift of the X-rays depends on the material distribution within the structure measured and is significant if substantial amounts of bone, fat, or injected contrast material are present. A material-selective beam hardening correction procedure has been developed that allows the reconstruction of good approximations of linear attenuation coefficients with respect to a reference energy. With the aid of mathematical simulations and measurements on a physical phantom, the feasibility of the procedure and its insensitivity with regard to energy settings and other machine parameters are documented.

Humans↗
PubMed1986

Examination of epidural tumors of the spinal canal. Comparative study with magnetic resonance imaging, computed tomography and tomo-myelography.

To delimit the vertical extension of epidural tumors of the spinal canal, tomo-myelography and magnetic resonance imaging (MRI) are the most accurate examinations, MRI appearing to us to be even superior to tomo-myelography. To evaluate precisely the bone extension of tumor growth as compared with the epidural lesions, computed tomography (CT) is more accurate than the other methods mentioned. The choice between these three techniques is of great importance as an aid in selection the best therapeutic method in each particular case.

Adult↗
PubMed2004

Magnetic resonance and computed tomography imaging of arrhythmogenic right ventricular dysplasia.

Arrhythmogenic right ventricular dysplasia (ARVD) is a familial cardiomyopathy that causes fibro-fatty replacement of the right ventricle (RV), leading to sudden death due to ventricular arrhythmias. The disease is an important cause of sudden death in individuals younger than 35 years of age. Structural and functional abnormalities of the RV constitute an important diagnostic criterion for the disease. Diagnosis of ARVD is often a challenge as conventional imaging modalities have significant limitations to visualize the RV. Recently, magnetic resonance imaging (MRI) and computed tomographic (CT) imaging have emerged as robust clinical tools for evaluation of myocardial pathology. In addition to providing morphologic and functional information, both imaging modalities have the ability to demonstrate intramyocardial fat, which is the pathological hallmark in ARVD. This article discusses the current status and role of MRI and CT imaging in the diagnosis of ARVD.

Arrhythmogenic Right Ventricular Dysplasia↗
PubMed1998

Functional anatomy and computed tomography imaging of the paranasal sinuses.

Standard radiographs are suboptimal in the display of the regional morphology in the nasal cavity and paranasal sinuses, especially the ethmoid sinus. The preferred radiographic modality for the evaluation of the nasal cavity and paranasal sinuses is computed tomography (CT). Coronal CT imaging perpendicular to the bony palate affords the best display of the ostiomeatal channels and facilitates the surgeon's perception of this regional morphology because it most closely resembles the endoscopic view. The purpose of this article is to familiarize the reader with the regional anatomy of the nasal cavity and paranasal sinuses, specifically the 14 anatomic structures the examiner must understand and systematically check in the evaluation of this morphologic area. A description of the most commonly found anatomic variations that influence the patency of the ostiomeatal channels as well as specific relationships between the paranasal sinuses, the orbits, and the intracranial compartment are also detailed. Although less helpful in the display of paranasal sinus chronic inflammatory disease, magnetic resonance imaging is beneficial in the diagnosis of fungal disease, neoplastic disease, and the display of inflammatory extension into the intracranial and intraorbital compartments.

Humans↗
PubMed2003

Computed tomography imaging of the temporal bone--normal anatomy.

This review describes the fundamental anatomical structures of the temporal bone as depicted on high-resolution computed tomography, and the clinical significance of these structures. It is not an encyclopaedic atlas, but provides the junior radiology/otorhinolaryngology resident with sufficient knowledge for interpretation of most of the imaging studies encountered in daily clinical practice.

Ear Canal↗
PubMed1996

Comparison of computed tomography imaging before and after functional treatment of bilateral condylar fractures in adults.

Bilateral condylar fractures in 10 adult patients were successfully treated nonsurgically. The patients were studied with computed tomography (CT). In all patients, the pretreatment images of both condyles showed medially displaced or dislocated condyles which were accompanied clinically by an anterior open bite. In all patients, the anterior open bite was eliminated and the occlusion was normal 2-3 months after treatment, while jaw function was normal and the patients were free of pain. Follow-up CT images showed that the fractured condyles had healed by bony consolidation but were still displaced or dislocated. The relationships with the glenoid fossa had not improved. The reestablishment of occlusion and function appears to occur not as a result of anatomic restitution of condylar height, but as a result of adaptation of the masticatory muscles.

Adaptation, Physiological↗
PubMed2007

Displacement of serotonin and dopamine transporters by venlafaxine extended release capsule at steady state: a [123I]2beta-carbomethoxy-3beta-(4-iodophenyl)-tropane single photon emission computed tomography imaging study.

Both positron emission tomography and single photon emission computed tomography (SPECT) studies suggest that saturation of serotonin transporters (SERT) is present during treatment with therapeutic doses of selective serotonin reuptake inhibitors (SSRIs). Selective serotonin reuptake inhibitors also appear to increase the availability of dopamine transporters (DAT). The current study measured SERT occupancy and modulation of DAT by the serotonin/norepinephrine reuptake inhibitor (SNRI) venlafaxine using [123I]2beta-carbomethoxy-3beta-(4-iodophenyl)-tropane SPECT. Eight healthy subjects were administered open-label venlafaxine extended release capsules (75 mg/d for 4 days followed by 150 mg/d for 5 days). Venlafaxine significantly inhibited [123I]beta-CIT binding to SERT in the brainstem (55.4%) and the diencephalon (54.1%). In contrast, venlafaxine increased [123I]beta-CIT binding to DAT in the striatum (10.1%) after 5 days of administration of 150 mg/d. The displacement of [123I]beta-CIT from brain SERT and the increase in striatal [123I]beta-CIT binding to DAT appear similar to previous work with the SSRI citalopram (40 mg/d). A literature review of SERT occupancy by marketed SSRIs and the SNRI venlafaxine using SPECT ([123I]beta-CIT) or positron emission tomography ([11C](N, N-Dimethyl-2-(2-amino-4-cyanophenylthio)-benzylamine) imaging suggests that therapeutic doses of SNRI are associated with virtual saturation of the serotonin transporter.

Adult↗
PubMed1998

Detection of coronary vasospasm by posthyperventilation technetium-99m sestamibi single-photon emission computed tomography imaging in patients with coronary artery disease.

Forced hyperventilation is simple, safe to perform, and can be used as a provocative test for coronary vasospasm. This study assesses whether a vasospastic component of angina might be detected in patients with angiographically "nonobstructive" coronary artery disease by posthyperventilation technetium-99m (Tc-99m) sestamibi single-photon emission computed tomography (SPECT) cardiac imaging. Eleven patients with angiographically nonobstructive coronary artery disease underwent Tc-99m sestamibi SPECT imaging at rest and after forced hyperventilation. Vessel diameters were measured by quantitative angiography before and after forced hyperventilation, and posthyperventilation SPECT images were compared with dipyridamole Tc-99m sestamibi stress images. Forced hyperventilation resulted in a 15% reduction in coronary artery diameter in stenotic segments (p <0.01), and a 17% reduction in adjacent nonstenotic segments (p <0.001). Myocardial uptake of Tc-99m sestamibi in segments perfused by vessels with angiographically nonobstructive stenoses was reduced by 24% following forced hyperventilation (p <0.001) compared with only 4% following dipyridamole (p <0.02). These findings suggest that posthyperventilation Tc-99m sestamibi SPECT imaging in patients with angina pectoris and nonobstructive coronary artery disease may be useful in identifying a vasospastic component of angina.

Angina Pectoris↗
PubMed2005

Performance characterization of megavoltage computed tomography imaging on a helical tomotherapy unit.

Helical tomotherapy is an innovative means of delivering IGRT and IMRT using a device that combines features of a linear accelerator and a helical computed tomography (CT) scanner. The HI-ART II can generate CT images from the same megavoltage x-ray beam it uses for treatment. These megavoltage CT (MVCT) images offer verification of the patient position prior to and potentially during radiation therapy. Since the unit uses the actual treatment beam as the x-ray source for image acquisition, no surrogate telemetry systems are required to register image space to treatment space. The disadvantage to using the treatment beam for imaging, however, is that the physics of radiation interactions in the megavoltage energy range may force compromises between the dose delivered and the image quality in comparison to diagnostic CT scanners. The performance of the system is therefore characterized in terms of objective measures of noise, uniformity, contrast, and spatial resolution as a function of the dose delivered by the MVCT beam. The uniformity and spatial resolutions of MVCT images generated by the HI-ART II are comparable to that of diagnostic CT images. Furthermore, the MVCT scan contrast is linear with respect to the electron density of material imaged. MVCT images do not have the same performance characteristics as state-of-the art diagnostic CT scanners when one objectively examines noise and low-contrast resolution. These inferior results may be explained, at least partially, by the low doses delivered by our unit; the dose is 1.1 cGy in a 20 cm diameter cylindrical phantom. In spite of the poorer low-contrast resolution, these relatively low-dose MVCT scans provide sufficient contrast to delineate many soft-tissue structures. Hence, these images are useful not only for verifying the patient's position at the time of therapy, but they are also sufficient for delineating many anatomic structures. In conjunction with the ability to recalculate radiotherapy doses on these images, this enables dose guidance as well as image guidance of radiotherapy treatments.

Computer Systems↗
PubMed1993

Accurate measurement of surface areas of anatomical structures by computer-assisted triangulation of computed tomography images.

There is a need for accurate surface area measurement of internal irregular anatomical structures in order to define light dosimetry in adjunctive intraoperative photodynamic therapy (AIOPDT). No satisfactory preoperative method exists of measuring this parameter. We have investigated whether computer-assisted triangulation of serial sections generated by computed tomography (CT) scanning can give an accurate assessment of the surface area of the walls of the true pelvis after anterior resection and before colorectal anastomosis. We have shown that the technique of paper density tessellation is an acceptable method of measuring the surface areas of phantom objects, with a maximum error of 0.5%, and is used as the gold standard. Computer-assisted triangulation of CT images of standard geometric objects and accurately-constructed pelvic phantoms gives a surface area assessment with a maximum error of 2.5% compared with the gold standard. The CT images of 20 patients' pelves have been analysed by computer-assisted triangulation and this shows that the surface area of the walls varies from 143 cm2 to 392 cm2. Simple step-like analysis of images and approximation to geometric shapes with subsequent calculation give unacceptably high errors. The surface area of an internal, rigid, irregular surface area for illumination in AIOPDT can be accurately measured preoperatively by computer-assisted triangulation of CT images.

Anthropometry↗
PubMed2005

Initial computed tomography imaging experience using a new macromolecular iodinated contrast medium in experimental breast cancer.

OBJECTIVE: The objective of this study was to evaluate computed tomography (CT) enhancement characteristics for a new iodinated macromolecular contrast medium (MMCM), PEG12000-Gen4-triiodo, for angiographic effect and for assessment of abnormal vascular permeability in cancer. MATERIALS AND METHODS: Time persistence of angiographic effect was evaluated on rat CT images acquired over 30 minutes using the iodinated polyethyleneglycol- (PEG) based macromolecule. Dynamic CT imaging after PEG12000-Gen4-triiodo-enhancement in tumor-bearing rats was used to quantitatively estimate plasma volume and microvascular transendothelial permeability for both tumor and normal soft tissue. Using identical doses of iodine, 300 mg iodine/kg, blood curves for this MMCM and iohexol were compared. RESULTS: Serial whole-body CT angiograms using PEG12000-Gen4-triiodo showed diagnostic vascular detail through 20 minutes, and the blood enhancement curve was higher and more persistent than with small-molecular iohexol. Permeability estimates were significantly (P<0.02; paired t test) higher in tumors (48.2+/-18.1 microL/min-1 100 mL) than in muscle (2.5+/-5.7 microL/min-1 100 mL). CONCLUSIONS: Use of PEG-based MMCM for experimental CT allowed for a persistent angiographic enhancement and for quantitative estimation of tumor microvascular characteristics.

Animals↗
PubMed2000

Use of three-dimensional spiral computed tomography imaging for staging and surgical planning of head and neck cancer.

We compare four different three-dimensional (3D) reconstruction methods of spiral computed tomography (CT) data for head and neck cancer to establish the method best suited for specific uses, eg, staging of lymph nodes and viewing of spatial relationships between the tumor, fascial spaces, adjacent soft tissues, and others structures. We evaluated a series of 10 patients (six men and four women), aged 32 to 60 years. Of these, five were histologically diagnosed with squamous cell carcinoma, two with lymphoma, one with thyroid cancer, one with Kikuchi's disease or necrotizing lymphadenitis, and one with esthesioneuroblastoma. All scans were obtained using high-resolution spiral CT (General Electric Medical Systems, Milwaukee, WI). The collimations used were 3 mm and 5 mm, matrix 512 x 512, and reconstruction interval not more than 3 mm. Scanning was performed from the skull base to the aortic arch. Iodinated contrast medium was injected so that the blood vessels were clearly differentiated from nodes. Different techniques of three-dimensional reconstruction were employed, including shaded surface display (SSD), multiplanar reconstructions (MPR), maximum intensity projection (MIP), 3D volume rendering (VR), and combined techniques. The reconstructions were performed in a variety of planes, including sagittal, coronal, and oblique views. In our series of selected patients, the technique of 3D VR showed potential advantages over other techniques. The MIP technique was useful in analyzing the patency of vessels and to exclude thrombus, compression, or displacement by tumor. The use of combined techniques such as SSD and MPR, accurately demonstrated the levels of lymph nodes and the relationship between the tumor projection of interest and various anatomic structures. In conclusion, 3D reconstruction of CT data is useful in the localization and staging of neck tumors and assists in surgical planning and radiation treatment.

Adult↗
PubMed2003

Three-dimensional computed tomography imaging in craniofacial surgery: morphological study and clinical applications.

Three-dimensional carniofacial CT imaging has been developed and progressed during the past two decades. The advancement of the hardware and software has made the imaging study more convenient, user friendly, and affordable. Processing and analysis of the imaging data are readily performed on personal computers. Accuracy of the 3-dimensional measurement has been validated. Collaborative study can be achieved with other departments or disciplines, such as orthopedic, otolaryngologic, and dental departments, as well as mechanical engineering department. All the data should be adequately archived as medical imaging data bank for later use. The data can be transferred for production of rapid prototyping models to enhance clinical application. Inter-center sharing of imaging data can be done through common image format. Comprehensive morphological study and clinical information may help to improve or refine treatment planning, which in turn yield better treatment outcome.

Craniofacial Abnormalities↗
PubMed2007

Low tube voltage improves computed tomography imaging of delayed myocardial contrast enhancement in an experimental acute myocardial infarction model.

OBJECTIVE: We sought to evaluate the influence of tube voltage on the visualization of acute myocardial infarction (MI) in cardiac multislice spiral computed tomography (MSCT). MATERIALS AND METHODS: Acute MI was induced in 12 domestic pigs by a 45-minute balloon occlusion of the left anterior descending artery. Delayed enhancement magnetic resonance imaging was performed 15 minutes after the injection of 0.2 mmol/kg Gd-DTPA. On the same day, retrospectively ECG-gated MSCT was performed at 120, 100, and 80 kV (16x0.75mm, 550mAseff.) 15 minutes after the injection of 140 mL of iopromide (1 g/iodine/kg). The pigs were killed and the hearts were excised and stained with 2,3,5-triphenyltetrazolium chloride. The area of acute MI, contrast-to-noise ratio (CNR), and percent signal difference were compared among the different imaging techniques by applying Bland-Altman plots and 2-way analysis of variance. RESULTS: On MSCT at 120, 100, and 80 kV, the respective mean acute MI sizes were 18.4+/-11.4%, 19.3+/-11.5%, and 20.5+/-11.6%. The mean MI sizes were 20.8+/-12.2% and 20.1+/-12.4% on magnetic resonance imaging and 2,3,5-triphenyltetrazolium chloride staining. Analysis of variance did not show any statistically significant differences between the different techniques with respect to the size of acute MI (P=0.9880). Comparing the different kV settings on MSCT, the highest percent signal difference (74.7+/-12.1%) and the highest CNR (6.7+/-1.8) between infarcted and healthy remote myocardium were achieved at 80 kV. CONCLUSIONS: When compared with routine scan protocols, low tube voltage MSCT allows for the assessment of the MI size with an improved CNR and contrast resolution. This technique appears to be advantageous for assessing myocardial viability from contrast enhanced late-phase MSCT.

Animals↗