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At least 73 records · Page 4Linked to original sources
PubMed1994

Computed tomography after laminectomy for lumbar spinal stenosis. Patients' pain patterns, walking capacity, and subjective disability had no correlation with computed tomography findings.

OBJECTIVES: The purpose of this study was to evaluate the relationship between postoperative computed tomography findings and patients' pain patterns, walking capacity, and subjective disability after laminectomy for lumbar spinal stenosis. SUMMARY OF BACKGROUND DATA: Recent improvements in computed tomography have enabled this tool to reveal changes in a patient after an operation, but there is a paucity of comparative examinations regarding the lumbar spinal canal of asymptomatic and symptomatic patients after laminectomy for lumbar spinal stenosis. METHODS: Ninety-two patients (42 women, and 50 men) with a mean age of 55 years were operated upon. Mean follow-up time was 3.5 years. Based on computed tomography findings of the operative area, three patient groups were formed: 1) no stenosis, 2) moderate stenosis, 3) and severe stenosis. During treadmill testing, each patient's pain was evaluated by visual analogue scale. The patients were divided into four pain pattern groups: 1) pain in the back and leg, 2) pain in the back only, 3) pain in the leg only, and 4) no pain in the back and leg. Subjective disability was measured by the Oswestry disability score. RESULTS: The structural changes revealed by computed tomography, and the patients' pain patterns, walking capacity, and subjective disability did not correlate significantly with each other. CONCLUSIONS: Postoperative computed tomography has only limited value because asymptomatic and symptomatic patients yield similar findings after surgery for lumbar spinal stenosis.

Disability Evaluation↗
PubMed1985

[Imaging of the heart using nuclear magnetic resonance tomography. I: Tomography].

Magnetic resonance (MR) is a new concept in the diagnostics of the cardiovascular system. The basic principle of MR is nuclear magnetism. MR tomography is based on induction and spatial encoding of a nuclear magnetic resonance signal. Due to the high tissue concentration and MR sensitivity, medical MR imaging chiefly uses protons of water, 1H. MR tomography of protons presents highly contrasted images of soft tissue organs with spatial resolution in millimeters. Parametric analysis of the MR signal enables quantitative assessments of physico-chemical tissue properties, blood flow and perfusion. The method is noninvasive and without serious biological side effects. Ionising radiation or traditional contrast agents are not utilized. Using conventional ECG synchronized MR tomography the cardiac and great vessels anatomy are superbly resolved, exceptions being the resolution of coronary vasculature and cardiac valve apparatus. The excellent spatial resolution and flexible spatial image orientation are important advantages of quantitative assessment of cardiac function by MR imaging. Preliminary studies demonstrated clinical utility of tomographic assessments of T1 and T2 relaxation parameters as well as phase angle analysis for definition of myocardial ischemia, blood flow rates and wall motion dynamics. The first comparative studies between imaging modalities in diagnostics of specific cardiac disorders point to a superior anatomic resolution of the heart and vascular morphology by MR tomography. The utilization of MR tomography in cardiovascular medicine is new and it would be premature to assign a definite value to this costly technique in clinical evaluations of patients with heart disease. However, there is unequivocal evidence that MR technology will play a decisive role in cardiology in the future, and MR imaging already represents significant progress in the evaluation of patients with cardiac disease.

Aortic Diseases↗
PubMed1993

[Maxillofacial tomography (MT tomography) in the diagnosis of diseases on the middle 1/3 of the face].

Maxillofacial tomography apparatus (MT tomography) is a panoramic tomographic unit, radiographing in recumbent position. Its image can show most of the anatomic structures of maxillofacial bones. Through comparative examination between the conventional roentgenograms (general radiographs, pantomographs and laminagrams) and MT tomography of 48 patients, it is found that MT tomography has certain advantages for the diagnosis of the range, extent and quality of fracture, tumour and tumour like disease in maxillofacial bones and that MT tomography can serve as an effective auxillary method of diagnosis for the conventional roentgenograms used for maxillofacial bones.

Adolescent↗
PubMed1991

Computed tomography, magnetic resonance imaging and positron emission tomography with [18F]fluorodeoxyglucose in multiple system atrophy and pure autonomic failure.

We studied 45 patients who had autonomic failure with computed tomography, magnetic resonance imaging and positron emission tomography with [18F]fluorodeoxyglucose to characterize the neuroimaging features of multiple system atrophy and pure autonomic failure and determine the utility of these techniques in distinguishing multiple system atrophy from pure autonomic failure. There were 30 patients with multiple system atrophy and 15 with pure autonomic failure. In the multiple system atrophy group, eight patients had mainly cerebellar signs, seven extrapyramidal and 15 had combinations of cerebellar and extrapyramidal signs. Cerebellar atrophy on computerized tomography and magnetic resonance imaging, signal hypointensity in the posterolateral putamen on magnetic resonance imaging and a generalized reduction in glucose utilization rate with positron emission tomography with [18F]fluorodeoxyglucose, were the main findings and were seen only in the patients with multiple system atrophy. Decreased glucose utilization (hypometabolism) was most prominent in the cerebellum, brainstem, striatum and frontal and motor cortices. These results indicate clear differences, using neuroimaging studies, between multiple system atrophy and pure autonomic failure.

Atrophy↗
PubMed1995

Cholinergic neurotransmission studied in vivo using positron emission tomography or single photon emission computerized tomography.

During the past decade, considerable efforts have been made in the development of radiopharmaceuticals for the in vivo study of the cholinergic neurotransmission using positron emission tomography or single photon emission computerized tomography. The main cholinergic radioligands, labelled with positron- or gamma-photon-emitting radionuclides, are reviewed with respect to use as in vivo markers of either acetylcholinesterase, vesicular acetylcholine transporter, brain and heart muscarinic receptors, or cholinergic nicotinic receptors. The main results obtained in the in vivo study of the physiology, pharmacology or pathology of the different steps of the cholinergic neurotransmission using single photon emission computerized tomography and positron emission tomography are discussed.

Acetylcholine↗
PubMed2005

Single photon emission computerized tomography and reverse gantry computerized tomography findings in patients with back pain investigated for spondylolysis.

BACKGROUND: Athletes with low back pain may have sustained a bone stress injury in the lumbar neural arch, including spondylolysis. Single photon emission computerized tomography (SPECT) and reverse gantry computerized tomography (rg-CT) help localize bone stress response and spondylolyses. OBJECTIVES: To describe the SPECT and rg-CT findings in those patients suspected of suffering from a spondylolysis. STUDY DESIGN: Large retrospective case series. SETTING: Secondary and tertiary care center in England. PATIENTS: A total of 213 patients presenting to the Spinal Unit and Sports Medicine Clinics between 1995 and 2000 with low back pain and subsequently investigated for spondylolysis by SPECT and rg-CT. METHODS: An experienced consultant musculoskeletal radiologist reported the SPECT and rg-CT, and these results along with data from the patient's medical records were analyzed. MAIN OUTCOME MEASURES: Sites and sides of increased scintigraphic activity in the lumbar neural arch seen on SPECT and complete and incomplete spondylolyses were recorded. RESULTS: Single photon emission computerized tomography scan showed increased scintigraphic uptake in 145 patients, mostly (42.3%) at L5. Marked increase in scintigraphic uptake was noted on the left side of the neural arch in 31 patients and on the right in 17 (chi; P < 0.05). Spondylolysis was identified on rg-CT in 81 patients. Spondylolyses were bilateral on 44 occasions, but unilateral lesions occurred in the left pars 36 times and on the right 16 times (chi; P < 0.01) CONCLUSIONS: Spondylolyses were a frequent finding on rg-CT in young athletes with low back pain. The sports most commonly associated with this stress response in the pars interarticularis were cricket and soccer. The lower lumbar levels are more likely to show abnormalities on SPECT and computerized tomography. Among those investigated for spondylolysis, left-sided lower lumbar pain was more common than right, and a marked increase in scintigraphic uptake was noted on the left more often than the right. Although bilateral spondylolyses were common, left-sided spondylolyses were more common than right. The asymmetric repetitive movements of certain sports may be responsible. In particular, fast bowlers developed spondylolysis on the opposite side of the body to their bowling arm.

Adolescent↗
PubMed2000

Penalized weighted least-squares image reconstruction for dual energy X-ray transmission tomography.

We present a dual-energy (DE) transmission computed tomography (CT) reconstruction method. It is statistically motivated and features nonnegativity constraints in the density domain. A penalized weighted least squares (PWLS) objective function has been chosen to handle the non-Poisson noise added by amorphous silicon (aSi:H) detectors. A Gauss-Seidel algorithm has been used to minimize the objective function. The behavior of the method in terms of bias/standard deviation tradeoff has been compared to that of a DE method that is based on filtered back projection (FBP). The advantages of the DE PWLS method are largest for high noise and/or low flux cases. Qualitative results suggest this as well. Also, the reconstructed images of an object with opaque regions are presented. Possible applications of the method are: attenuation correction for positron emission tomography (PET) images, various quantitative computed tomography (QCT) methods such as bone mineral densitometry (BMD), and the removal of metal streak artifacts.

Algorithms↗
PubMed1989

[Radiation dosage and clinical value of conventional tomography and high resolution computerized tomography of the nose and ear].

Hypocycloidal (frontal and temporal) tomography of the base of the skull is compared with high resolution computed tomography (HR-CT) with respect to dose and clinical usefulness. In most cases HR-CT is indicated because of its better density resolution in comparison with conventional hypocycloidal tomography. As the X-ray beam is directed at the slice plane the dosage is noticeably less than when using conventional tomography. Slice thickness depends on the required geometric resolution. This is an additional factor in radiation protection.

Ear↗
PubMed1985

Low-dose transaxial tomography. An alternative to computed tomography for the evaluation of anteversion of the femur during childhood.

Low-dose transaxial tomography is a technique that can produce cross-sectional images of the hips and femurs in children to permit calculation of the angle of femoral anteversion. Transaxial tomography was compared with computed tomography in terms of measured radiation dose and image quality. Transaxial tomography was found to require at least 90% less radiation dose, and the images were judged to be acceptable for the determination of anteversion.

Child↗
PubMed1978

[The efficiency of computer-tomography and conventional tomography of processes of the skull and of the skullbase (author's transl)].

In 12 patients with tumorous or chronic-inflammatory diseases of the skull and the skullbase the results of conventional and computer-tomography were compared with the operative findings. The computer-tomography of the most important regions is demonstrated by individual examples. The preliminary results indicate, that computer-tomography is reliable in evaluation of the extend of pathological processes. Therefor follow-up data after treatment were obtained by computer-tomography only.

Carcinoma↗
PubMed1982

Conventional tomography and computed tomography-are both methods necessary for evaluation of facial lesions?

108 patients with verified traumatic, inflammatory and neoplastic lesions in the facial region and the pharyngeal space were evaluated both with conventional tomography and CT. Subsequently an analysis was made as to whether both methods were complementary or at least partially replaceable by each other. In traumatic lesions transverse axial CT combined with frontal tomography yielded optimal information. For the diagnosis of inflammatory and neoplastic lesions CT was superior to tomography with the exception of lateral tomograms which contributed additional information to diseases of the sphenoid sinus, the epipharynx, the pterygopalatine fossa and the orbital roof. The radiation dose to the eye is remarkably lower in CT than in tomography.

Eye↗
PubMed2001

Radiographic evaluation of cervical spine trauma. Plain radiography and conventional tomography versus computed tomography.

Different imaging modalities are available for the diagnosis of cervical spine injuries. There is a controversial discussion about whether plain radiography (PR), conventional tomography (CTO) or computed tomography (CT) should primarily be used. PR and CTO are more often available and less costly than CT. Especially in second-care hospitals, CT is not always available. The diagnostic work-up in these centres has to rely on conventional techniques. The aim of this study was to define the role of PR supplemented by CTO in the diagnosis of cervical spine trauma in comparison to CT. Twenty-five patients were identified who underwent plain radiography (PR), conventional tomography (CTO) and computed tomography (CT) for the diagnosis of a cervical fracture. In 19 patients a fracture of the cervical spine was identified. All images were reviewed by two independent observers to estimate the interobserver variability. The highest detection rate was achieved by CT (18/18 fractures detected for observer 1/2), followed by CTO (16/16 fractures) and then PR (15/14 fractures). When the detection rates of PR and CTO are combined, 18 fractures were detected by each of the observers. The results were analysed for the dens and the rest of the cervical spine independently. For PR and CTO the detection rates were lower for fractures of the dens than for the rest of the cervical spine. We conclude that the combination of PR and CTO accurately detects fractures of the cervical spine compared with CT. If a fracture of the dens is suspected, the patients should be referred to CT due to its superior accuracy in this region.

Adolescent↗
PubMed2001

Positron emission tomography using(18)F-fluoro-deoxyglucose and euglycaemic hyperinsulinaemic glucose clamp: optimal criteria for the prediction of recovery of post-ischaemic left ventricular dysfunction. Results from the European Community Concerted Action Multicenter study on use of(18)F-fluoro-deoxyglucose Positron Emission Tomography for the Detection of Myocardial Viability.

AIMS: To assess the accuracy of positron emission tomography to predict recovery of global cardiac function after revascularization in patients with coronary artery disease. METHODS AND RESULTS: One hundred and seventy-eight patients (157 male, 58+/-10 years) with coronary artery disease and left ventricular dysfunction (mean ejection fraction 39+/-14%) were enrolled in six European centres. They underwent a common protocol for the assessment of viability using(18)F-fluoro-2-deoxyglucose (FDG) positron emission tomography during a standardized euglycaemic hyperinsulinaemic glucose clamp before revascularization by either surgery (n=140) or angioplasty (n=38). Seven patients were excluded because of incomplete revascularization of a dysfunctional region. Based on the recovery of global ejection fraction 2-6 months after revascularization, patients were classified into two groups: 82 patients who had a >5% improvement in ejection fraction postoperatively, and 89 patients without postoperative ejection fraction improvement. Optimal cut-off points for postoperative improvement of global cardiac function were computed, using receiver operating curve analysis. The highest sensitivity (79%) and specificity (55%) for predicting postoperative ejection fraction improvement by positron emission tomography was found when three or more dysfunctional segments had a relative FDG uptake >45% of normal remote myocardium (overall accuracy 67%). CONCLUSIONS: In a large cohort of coronary patients with impaired ejection fraction, FDG positron emission tomography demonstrated high sensitivity and moderate specificity to predict improvement of cardiac function after coronary revascularization.

Adult↗
PubMed1986

[Magnetic resonance tomography of focal liver lesions in comparison with computed tomography and sonography].

The results of magnetic resonance tomography (MRT) performed in 37 patients with predominantly solitary intrahepatic space-occupying masses are presented. Examinations were carried out with a superconducting magnet operating at a field strength of 0.35 Tesla. The majority of intrahepatic masses exhibited a well distinguishable signal amplification compared to normal hepatic parenchyma when T2 weighted sequences were used. For a further differentiation of the lesion, however, T1 and T2 weighted sequences have to be performed. In all cases diagnostic value of MRT is compared to that of sonography and computed tomography. The assessment of magnetic resonance tomograms of focal hepatic lesions is based on the sequence-depending on the signal behaviour of the mass - especially with regard to morphological criteria. The high soft-tissue contrast of magnetic resonance tomography compensates for the low spatial resolution, thus resulting in a sensitivity of focal lesions comparable to that of sonography and computed tomography. The good visualisation of vessels is an advantage. With the exception of haemangioma, however, MRT does not seem to improve diagnosis of the type of focal hepatic lesions.

Adenoma, Bile Duct↗
PubMed1986

[Nuclear magnetic resonance tomography of the temporomandibular joint. Comparison with computerized tomography and arthrography].

79 patients aged 6 to 66 years (9 men and 70 women) with abnormalities of the TMJs were examined by magnetic resonance tomography (132 joints) and the results were compared with CT (16 joints) and arthrography (39 joints). Magnetic resonance tomography showed forward luxation of the meniscus in 82 joints (62%). In 34 joints (26%) the meniscus spontaneously resumed normal position when the mouth was open, but in 48 joints (36%) the displacement was permanent. The accuracy of resonance tomography was equal to that of arthrography and superior to CT. It was particularly suitable for follow-up examination after surgery (23 cases) when invasive arthrography would be contraindicated or difficult. Because of the high resolution of the soft tissue components in the TMJ, resonance tomography should be able to diagnose inflammatory and degenerative changes in the meniscus and ligaments.

Adolescent↗
PubMed1992

Review of convergent beam tomography in single photon emission computed tomography.

Investigation of convergent-beam single photon emission computed tomography (SPECT) is actively being pursued to evaluate its clinical potentials. Fan-beam, cone-beam, pin-hole and astigmatic collimators are being used with rotating gamma cameras having large crystal areas, to increase the sensitivity for emission and transmission computed tomography of small organs such as the thyroid, brain or heart. With new multi-detector SPECT systems, convergent-beam geometry offers the ability to simultaneously obtain emission and transmission data necessary to quantify uptake of radiopharmaceutical distributions in the heart. The development of convergent-beam geometry in SPECT requires the integration of hardware and software. In considering hardware, the optimum detector system for cone-beam tomography is a system that satisfies the data sufficiency condition for which the scanning trajectory intersects any plane passing through the reconstructed region of interest. However, the major development of algorithms has been for the data insufficient case of single planar orbit acquisitions. The development of these algorithms have made possible the preliminary evaluation of this technology and the imaging of brain and heart are showing significant potential for the clinical application of cone-beam tomography. Presently, significant research activity is pursuing the development of algorithms for data acquisitions that satisfy the data sufficiency condition and that can be implemented easily and inexpensively on clinical SPECT systems.

Brain↗
PubMed1999

Imaging modalities in x-ray computerized tomography and in selected volume tomography.

This review of different principles used in x-ray computerized tomography (CT) starts with attenuation (transmission) CT. The pros and cons of different geometrical solutions, single-ray, fan-beam and cone-beam, are discussed. Attenuation CT measures the spatial distribution of the linear attenuation coefficient, mu. The contributions of different interaction processes to mu have also been used for CT. Fluorescence CT is based on measurements of the contribution, cZtauZ/rho, from an element Z with concentration cZ, to the linear attenuation coefficient. Diffraction CT measures the differential coherent cross section d sigma (theta)(coh)/d omega, Compton CT the incoherent scatter cross section sigma. The usefulness of these modalities is illustrated. CT methods based on secondary photons have a competitor in selected volume tomography. These two tomography methods are compared. A proposal to perform Compton profile tomography is also discussed, as is the promising method of phase-contrast x-ray CT.

Algorithms↗