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Results for “computed tomography”

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At least 181 records · Page 10Linked to original sources

PubMed1983

Radiological evaluation of the peri- and pararenal spaces by computed tomography.

Computed tomography (CT) gives an excellent opportunity to revisit normal anatomy and to understand pathological aspects. Renal fascia alterations, on CT scans, are a sensitive sign of local lesion. While a thin renal fascia has no pathological significance, any thickening may be considered abnormal although nonspecific. It is found in pancreatitis as well as in cancer of the pancreas, in renal tumors as well as in pyelonephritis. It may persist as a scar. On the other hand, lack of fascial thickening allows us to rule out renal extension of a neighboring lesion or to decide that a renal mass is an ancient slowly-growing benign one.

Abscess↗

PubMed1978

Differentiation of orbital cellulitis from preseptal cellulitis by computed tomography.

Computed tomography (CT) was used in the management of four patients with periorbital inflammation. These patients were selected for CT scanning because of the difficulty, on clinical examination alone, in determining the degree of orbital disease. The CT scans confirmed the presence and defined the location of an orbital abscess in three patients and eliminated the presence of an abscess in the fourth. On the basis of this experience, CT scanning is recommended in the evaluation of children with periorbital inflammation in whom proptosis, ophthalmoplegia, or loss of visual acuity develops, or in whom severe eyelid edema prevents adequate eye examination.

Adolescent↗

PubMed1980

A comparison between abdominal ultrasonography and computed tomography.

Computed tomography (CT) and ultrasonography are based on entirely different physical principles. In the abdomen the two techniques have similar diagnostic applications. Whereas CT is in many instances more informative, it is also a more time-consuming and much more costly procedure. For clinicians who practise in areas where these techniques are available, this article may be useful as a quick guide to the choice of procedure.

Abdomen↗

PubMed1981

Diagnosis of lipoid pneumonia by computed tomography.

Computed tomography (CT) can establish the diagnosis of lipoid pneumonia in lung masses by detecting fat. In this case report, the diagnosis of lipoid pneumonia was first suggested by CT, supported by a long history of mineral oil ingestion, and confirmed by needle aspiration biopsy of the larger of two lung lesions and specific stains. In the future, the detection of fat in lung masses by CT will warrant intermittent follow-up by routine chest x-ray films. Needle aspiration biopsy or surgery would be needed only if a mass showed signs of growth.

Aged↗

PubMed1993

[Intraarticular fractures of the calcaneus: pathological description. Contribution of x-ray computed tomography].

Computed tomography (CT) is of cardinal importance in the study of displaced intra-articular fractures of the calcaneus, as with this imaging technique the primary fracture line of Palmer can be followed and its various locations visualised. If the three-stage classification system of these fractures as vertical, horizontal or mixed fractures, based on their radiological appearance, is adopted, a correlation can be established between the location of Palmer's line and these three anatomical types. The fundamental fracture line is medial in the vertical types, lateral in the horizontal types and is located in the centre of the posterior facet in the mixed types. It can be seen that the fundamental fracture line separates a laterally detached fragment which is always tilted, giving a vertical slope to the surface of the posterior facet which it supports and thus giving a vertical image. This fragment is itself separated from a medially detached fragment which is tilted horizontally and produces a horizontal image on the lateral view. The CT sections must be examined for the presence of a secondary sagittal line completely isolating the horizontally tilted fragment. The importance of the location of the fundamental fracture line, which is on the borderline between tilting and horizontalisation, suggests that pronation-supination of the foot is a factor in the causal mechanism of these fractures. A clear understanding of the three-dimensional position of the fragments and of their displacement, essentially defined by the location of the fracture line, is a prequisite before attempting surgical reduction of calcaneal fractures.

Calcaneus↗

PubMed2005

Improved detection of second primary cancer using integrated [18F] fluorodeoxyglucose positron emission tomography and computed tomography for initial tumor staging.

PURPOSE: This study evaluated prospectively the value of integrated whole-body positron emission tomography and computed tomography (PET/CT) using [18F] fluorodeoxyglucose (FDG) in detecting a second primary cancer at the time of the initial staging in comparison with a conventional staging work-up (CSW). METHODS: The participants were 547 patients diagnosed with cancer who underwent FDG PET/CT imaging for the initial staging. An additional diagnostic evaluation was performed when there were abnormal findings indicative of a second primary cancer on either PET/CT or CSW considering the site and the biologic behavior of the alleged primary tumor. RESULTS: A total of 27 second primary malignant tumors were identified in 26 of the 547 patients (4.8%). FDG PET/CT found 45 lesions indicative of a second primary cancer, of which 24 lesions were proved to be a second primary cancer, seven were clinically unexpected metastases, and 14 lesions were benign. Therefore, sensitivity and positive predictive value of FDG PET/CT in detecting a second primary cancer or an unexpected metastasis were 91% (31 of 34) and 69% (31 of 45), respectively. In contrast, CSW could not identify 16 second primary cancers and one metastatic lesion. CONCLUSION: FDG PET/CT at the time of the initial staging is useful for screening a second primary cancer with a high sensitivity. An additional diagnostic work-up is essential when abnormal findings, which are indicative of a second primary cancer, are obtained on PET/CT images to rule out the presence of either a second primary cancer or an unexpected metastasis.

Aged↗

PubMed2004

[Value of integrated positron-emission tomography and computed tomography in gross tumor volume delineation for radiotherapy for bone metastasis].

OBJECTIVE: To evaluate the role of integrated positron-emission tomography and computed tomography (PET/CT) in gross tumor volume (GTV) delineation for three-dimensional conformal radiotherapy for bone metastasis. METHODS: Three patients with multiple bone metastases were enrolled in this study, whose primary tumors were pathologically identified as lung cancer, liver cancer and renal cell carcinoma. In each case, 6 sites of bone metastases were selected, labeled as BM1 to BM6 which located in the lumbar, thoracic vertebra, rib, ilium, scapula and thighbone respectively. The GTVs of the 6 bone metastases were delineated on the CT scans for treatment planning by 8 radiation oncologists, and the results were compared with the delineation obtained on the basis of integrated CT and PET/CT for analyzing the interobserver variability. RESULTS: For BM1-5 with obvious bone cortex lesions by the carcinoma, the GTV delineated on the basis of CT was greater than that derived from PET/CT (P<0.05), whereas for BM6 with intact bone cortex, the contrary result was observed (P<0.05). For any of these bone metastasis, the interobserver variability in GTV delineation with PET/CT was less than that with CT. CONCLUSION: PET/CT is useful for improving the accuracy of GTV delineation for the protection of the normal tissues during radiotherapy.

Bone Neoplasms↗

PubMedDate not supplied

Continuous time-dependence in computed tomography.

Computed tomography is sensitive to changes in the imaged distribution during acquisition of the projection data. Previous investigations have emphasized discrete or discontinuous changes in the imaged object. Recent advances have motivated our investigation of object time-dependence characterized by a continuous function in time at each point. Formal mathematical and computer simulation approaches have been developed, and are presented along with simple examples of their applications. Further applications in three distinct ongoing studies are outlined.

Computers↗

PubMed1978

[Spontaneous intracerebral hematomas. New aspects since the introduction of computer tomography].

Computed tomography has extended the diagnostic possibilities in intracerebral haemorrhages in a decisive manner. Owing to the more exact computer-tomographical diagnosis, especially with regard to the extension and localisation of the haemorrhage as well as the experience gained with simultaneous cerebral pressure measurement, surgical treatment of the haemorrhage can in most cases be carried out through a drilled hole in local anaesthesia. The prognosis of intracerebral haemorrhages is by no means unfavourable from the first, in case of haemorrhages of an unknown etiology in young adults it is even very good. That is why the operation should be carried out in good time. But even patients in a bad condition and cases with additional massive intraventricular bleeding are as such no contraindications.

Adult↗

PubMed2003

Is informed consent necessary for paediatric computed tomography?

Computed tomography (CT) is a valuable examination in children, but the lifetime cancer mortality attributed to CT radiation in children is an order of magnitude higher than in adults. Therefore, it is important that radiologists and referring clinicians ensure that parents are fully informed of the radiation risks, the appropriateness of the examination is considered and imaging protocols are tailored to reduce the radiation burden.

Adult↗

PubMed2003

Computer-assisted simulations in orthodontic diagnosis and the application of a new cone beam X-ray computed tomography.

Computational simulations which include three-dimensional (3-D) image processing and biomechanical calculations should provide useful information to our research and orthodontic clinic as a clinical tool defined as 'thinking'. In this review, 1) biomechanical simulations applied to predict the mandibular growth; 2) mathematical models of virtual bone cells and 3) 3-D images and solid model simulations for surgical planning are introduced. In biomechanical simulation, biting force, electromyographic (EMG) activity and cephalograms of 32 subjects were applied. Computational results of mathematical model were compared with actual bone growth in a rat. Three-dimensional image and solid model of 14 patients were utilized for their treatment planning. From the results, several concepts of our simulations were confirmed: 1) reaction forces generated by masticatory muscles at the condyle control the direction of mandibular growth; 2) some mathematical models have the possibility to describe the process of bone growth; 3) 3-D image processing software and solid models are necessary for diagnosis and planning of orthognathic surgery. We also believe that the orthodontists can more accurately predict the affects of surgical procedures and orthodontic tooth movement using the new cone beam X-ray computed tomography (CT) (CB MercuRay; Hitachi Medico Technology, Tokyo, Japan) and its advanced application software.

Animals↗

PubMed1998

Basic principles and clinical applications of neuronavigation and intraoperative computed tomography.

Computed tomography (CT) images in combination with a navigation device enable three-dimensional (3-D) localization of intracranial lesions. Furthermore, CT scanning can be adapted for intraoperative application to actualize the image data and to check the anatomical situation during the operation. Frameless navigation was used in 100 patients. The procedure was performed in 46 cases with an optical navigation system, in 38 cases with a sensory arm, and in 16 cases with a navigated microscope. Six skin markers were used for registration. Mean fiducial registration error was 2.18 mm with a standard deviation of 1.03 mm. The indication for navigation was tumor localization and planning of the craniotomy in 81 cases, stereotactic biopsy in eight cases, and endoscopic procedures in 11 cases. Technical problems with the navigation system were observed in nine cases. In two additional cases the tumor was not found by navigation. All eight biopsy cases were successful, and histologically relevant specimens were obtained without complications. Navigation was helpful in 11 endoscopic cases for choosing an optimal trajectory through the foramen of Monro or for connecting multiple intraventricular cysts. For intraoperative CT imaging, the mobile Philips Tomoscan M was adapted to the needs of the operating environment. The mobile CT was used in 78 cases in the operating room: 16 patients who underwent a stereotactic procedure had only preoperative CT scans, 36 patients had an intraoperative CT during tumor surgery, and 26 patients during the test period of the device had only a postoperative CT investigation. In 10 cases (28%) of the intraoperative group the remaining tumor tissue could be demonstrated on the CT scans. The tumor remnants that were not visible in the microscopical surgical field were subsequently removed. According to our results, intraoperative navigation seems superior for the localization of intracranial lesions and intraoperative CT is more useful when considering the radicality of tumor removal.

Brain Neoplasms↗

PubMed2003

Unusual causes of colonic wall thickening on computed tomography.

Computed tomography (CT) appearances in "colitis" are often non-specific, and include mural thickening and mesenteric fat stranding. In the western world, the majority of cases will have, or be subsequently diagnosed with, inflammatory bowel disease, pseudomembranous colitis or ischaemic colitis. However, other rare conditions may also produce these rather non-specific signs. We present a number of cases demonstrating colonic wall thickening on CT due to rarer diagnoses, which are correlated with the histopathological features. Some of these CT appearances have not been described previously in the literature.

Adult↗

PubMedDate not supplied

Effect of contrast medium dose and image acquisition timing on ureteral opacification in the normal dog as assessed by computed tomography.

Computed tomography (CT) excretory urography was performed in five adult female dogs after intravenous injection of a bolus of four different doses of water-soluble iodinated contrast medium (100, 200, 400, and 800 mgI/kg). CT images centered over the urinary bladder were performed before injection and 1, 3, 5, 7, 9, 11, 15, 20, 25, 30, 40, 50, and 60 minutes after injection. Opacification of both ureters was evaluated by measuring maximum CT number of individual ureters at each time. Time opacification curves were generated for each dose. Best opacification of the ureters was obtained with 400 and 800 mgI/kg, with a constant peak at 3 minutes and durable opacification for 1 hour. Insufficient opacification was obtained with lower dose of 100 and 200 mgI/kg.

Animals↗

PubMed2006

Computed tomography angiography and computed tomography perfusion in ischemic stroke: A step-by-step approach to image acquisition and three-dimensional postprocessing.

Recent technical advances in both image acquisition and postprocessing have enabled computed tomography angiography (CTA) with computed tomography perfusion to become front-line tools for acute stroke evaluation in many institutions. This article provides a step-by-step approach to utilizing these technologies, particularly in the rapid triage of appropriate stroke patients to reperfusion therapies. The specific contrast injection, image acquisition, and 3D postprocessing protocols for high-quality CTA, currently in use at our institution, are delineated. An important point of emphasis is how preliminary angiographic and cerebral perfusion observations can be made immediately at the scanner to expedite emergent therapy. Also explored is the manner in which a dedicated 3D lab can support a high clinical volume, including a large percentage of emergent studies. An accurate yet time-efficient approach for the neuroradiologist to integrate 3D interpretation with CTA source data review is offered. Several important imaging and interpretive pitfalls in stroke CTA are illustrated.

Angiography↗

PubMed2003

Three-dimensional edge-preserving image enhancement for computed tomography.

Computed tomography (CT) images exhibit a variable amount of noise and blur, depending on the physical characteristics of the apparatus and the selected reconstruction method. Standard algorithms tend to favor reconstruction speed over resolution, thereby jeopardizing applications where accuracy is critical. In this paper, we propose to enhance CT images by applying half-quadratic edge-preserving image restoration (or deconvolution) to them. This approach may be used with virtually any CT scanner, provided the overall point-spread function can be roughly estimated. In image restoration, Markov random fields (MRFs) have proven to be very flexible a priori models and to yield impressive results with edge-preserving penalization, but their implementation in clinical routine is limited because they are often viewed as complex and time consuming. For these practical reasons, we focused on numerical efficiency and developed a fast implementation based on a simple three-dimensional MRF model with convex edge-preserving potentials. The resulting restoration method provides good recovery of sharp discontinuities while using convex duality principles yields fairly simple implementation of the optimization. Further reduction of the computational load can be achieved if the point-spread function is assumed to be separable. Synthetic and real data experiments indicate that the method provides significant improvements over standard reconstruction techniques and compares well with convex-potential Markov-based reconstruction, while being more flexible and numerically efficient.

Algorithms↗

PubMed1976

Positional shift of intraventricular blood clots demonstrated by computed tomography.

Computed tomography with the patient in the prone position was employed to obtain information in a case of intraventricular hematoma secondary to arteriovenous maliformation. A gravitational shift in the position of the intraventricular blood clots was demonstrated by a scan obtained with the patient in the brow-down position. Consideration is given to the possible use of the "prone EMI scan" for other intracranial problems of differential diagnosis.

Adolescent↗

PubMed1976

Quantification of bone mineralization using computed tomography.

Computed tomography was used to find a sensitive parameter for bone mineralization. A precision scanning instrument was constructed for determination of the mineral distribution in sections of the forearm. The quality of the reconstructed images allows separate quantification of compact and spongy bone even when gamma rays are used. Computer simulation and measured of models and macerated human bones showed that under clinical conditions it is possible to quantify spongy bone density within an accuracy of +/-2%.

Adolescent↗