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At least 181 records · Page 10Linked to original sources
PubMedDate not supplied

A single-photon emission computed tomography imaging study of driving impairment in patients with Alzheimer's disease.

Single-photon emission computed tomography (SPECT) was used in this study to examine the neurophysiologic basis of driving impairment in 79 subjects with dementia. Driving impairment, as measured by caregiver ratings, was significantly related to regional reduction of right hemisphere cortical perfusion on SPECT, particularly in the temporo-occipital area. With increased severity of driving impairment, frontal cortical perfusion was also reduced. Clock drawing was more significantly related to driving impairment than the Mini-Mental State Examination (MMSE). Driving impairment in Alzheimer's disease is related to changes in cortical function which vary according to the severity of the disease. Cognitive tests of visuoperceptual and executive functions may be more useful screening tools for identifying those at greatest risk for driving problems than examinations like the MMSE that are weighted toward left-hemisphere-based verbal tasks.

Activities of Daily Living↗
PubMed2005

Evolving concepts in the pathology and computed tomography imaging of lung adenocarcinoma and bronchioloalveolar carcinoma.

PURPOSE: To review recent advances in pathology and computed tomography (CT) of lung adenocarcinoma and bronchioloalveolar carcinoma (BAC). METHODS: A pathology/CT review panel of pathologists and radiologists met during a November 2004 International Association for the Study of Lung Cancer/American Society of Clinical Oncology consensus workshop in New York. The purpose was to determine if existing data was sufficient to propose modification of criteria for adenocarcinoma and BAC as newly published in the 2004 WHO Classification of Lung Tumors, and to address the pathologic/radiologic concept of diffuse/multicentric BAC. RESULTS: Solitary small, peripheral BACs have an excellent prognosis. Most lung adenocarcinomas with a BAC pattern are not pure BAC, but rather adenocarcinoma, mixed subtype with invasive patterns. This applies to tumors presenting with a diffuse/multinodular as well as solitary nodule pattern. The percent of BAC versus invasive components in lung adenocarcinomas appears to be prognostically important. However, a consensus definition of "minimally invasive" BAC with a favorable prognosis could not be achieved. While recognition of a BAC component is possible, the diagnosis of BAC with exclusion of invasive adenocarcinoma cannot be made by small biopsy or cytology specimens. CONCLUSION: There is a need to work toward a mutual understanding and consensus between pathologists, clinicians, and researchers with the use of the term BAC versus adenocarcinoma. Future studies should make some attempt to quantitate these components and/or other features such as size of scar, size of invasive component, or pattern of invasion. Hopefully, this work will allow definition of a category of adenocarcinoma, mixed subtype with predominant BAC/minimal invasion and a favorable prognosis.

Adenocarcinoma↗
PubMed1999

New method of estimating myocardial infarct size using technetium-99m pyrophosphate and thallium-201 dual single photon emission computed tomography imaging.

A new method was devised to estimate infarct size using dual single photon emission computed tomography with thallium-201 and technetium-99m pyrophosphate. Designating the ratio of infarct area to whole myocardial volume as %MI, the correlation of %MI with other markers of left ventricular dysfunction was examined: peak creatine kinase, ejection fraction and left ventricular asynergy. As %MI correlated well with these markers, it is considered that %MI will be useful for estimating infarct size and predicting the severity of left ventricular dysfunction in the early stage of acute myocardial infarction.

Adult↗
PubMed2003

Characterization of the interstitial lung diseases via density-based and texture-based analysis of computed tomography images of lung structure and function.

RATIONALE AND OBJECTIVES: Efforts to establish a quantitative approach to the computed tomography (CT)-based character ization of the lung parenchyma in interstitial lung disease (including emphysema) has been sought. The accuracy of these tools must be site independent. Multi-detector row CT has remained the gold standard for imaging the lung, and it provides the ability to image both lung structure as well as lung function. MATERIAL AND METHODS: Imaging is via multi-detector row CT and protocols include careful control of lung volume during scanning. Characterization includes not only anatomic-based measures but also functional measures including regional parameters derived from measures of pulmonary blood flow and ventilation. Image processing includes the automated detection of the lungs, lobes, and airways. The airways provide the road map to the lung parenchyma. Software automatically detects the airways, the airway centerlines, and the branch points, and then automatically labels the airway tree segments with a standardized set of labels, allowing for intersubject as well intrasubject comparisons across time. By warping all lungs to a common atlas, the atlas provides the range of normality for the various parameters provided by CT imaging. RESULTS: Imaged density and textural changes mark underlying structural changes at the most peripheral regions of the lung. Additionally, texture-based alterations in the parameters of blood flow may provide early evidence of pathologic processes. Imaging of stable xenon gas provides a regional measure of ventilation which, when coupled with measures of flow, provide for a textural analysis regional of ventilation-perfusion matching. CONCLUSION: With the improved resolution and speed of CT imaging, the patchy nature of regional parenchymal pathology can be imaged as texture of structure and function. With careful control of imaging protocols and the use of objective image analysis methods it is possible to provide site-independent tools for the assessment of interstitial lung disease. There remains a need to validate these methods, which requires interdisciplinary and cross-institutional efforts to gather appropriate data bases of images along with a consensus on appropriate ground truths associated with the images. Furthermore, there is the growing need for scanner manufacturers to focus on not just visually pleasing images, but on quantitatifiably accurate images.

Humans↗
PubMed1978

Image quality in cranial computed tomography.

Image quality in cranial computed tomography (CT) was evaluated with phantom and patient studies on both a first (single beam) and a second (multiple beam) generation scanner. When comparable radiation doses were used, there were only minor differences in resolution, low contrast detectability, and noise level. The pattern of noise relative to the size of the area in which it was measured was somewhat different. On patient studies, no differences were found when contrast-material-filled vessel visibility and gray--white matter distinction were analyzed. A lesion was obscured by streak artifacts in one scanner in one of 22 patients scanned on both machines. The major factor in image quality as seen in the two scanners seemed to be in the production of artifacts. This was apparent in artifacts from motion, high contrast discontinuities, beam hardening, and edge enhancement. Multiple factors must be considered in assessing CT image quality. In particular, further studies to quantitatively evaluate noise quality and artifact production are needed.

Brain↗
PubMed2006

Non-invasive coronary angiography with 16-slice spiral computed tomography: image quality in patients with high heart rates.

The purpose of this study was to assess segment image quality at high heart rates using 16-slice computed tomography and differential reconstruction for major coronary vessels. According to the following protocol, 16-slice CT coronary angiography in 46 patients with a mean heart rate of 86.3+/-11.8 was reconstructed. At three transverse planes, preview series were obtained and motion artifacts evaluated in 5% increments from 0-95% within the cardiac cycle. Relying on image quality in the previews, reconstructions were performed at three z-positions for each patient. Segment image quality was assessed in terms of artifacts and visibility. The effects of heart rate and trigger delay on image quality were analyzed. Optimal image quality was achieved at 25 to 35% of the cardiac cycle for the left circumflex (CX) and right coronary artery (RCA) or 30 to 40% for the left main (LM) and left anterior descending artery (LAD). Sixteen-slice CT and differential reconstruction produced good image quality with a low percentage of motion-degraded proximal and middle segments (8.8%). Grades were 1.5 for the LM, 1.9 for the LAD, 2.0 for the CX and 2.3 for the RCA. At high heart rates, good image quality of the coronary arteries is achieved by 16-slice CT and a sophisticated reconstruction strategy at peak to late systole.

Algorithms↗
PubMed2005

[Diagnostic significance of multi-slice computed tomography imaging in congenital inner ear malformations].

OBJECTIVE: To evaluate the feasibility and usability of multi-slice computed tomography (MSCT) in congenital inner ear malformations. METHODS: Fourty-four patients with sensorineural hearing loss (SNHL) were examined by a Somatom Sensation 16 (siemens, Germany) CT scanner with following parameters: 120 kV, 100 mAs, 0.75 mm collimation, 1 mm reconstruction increment, a pitch factor of 1 and a field of view of 100 mm. The axial images of interested ears were reconstructed with 0.1 mm reconstruction increment, and a field of view of 50 mm. The 3D reconstructions were done with volume rendering technique (VRT) on the workstation (3D Virtuoso and Wizard,siemens). RESULTS: Twenty-five patients were normal and 19 patients (36 ears) were congenital inner ear malformations among 44 patients scanned with MSCT. Of the malformations, all the axial, MPR and VRT images can display the site and degree in 33 ears. VRT images were superior to the axial images in displaying the malformations in 3 ears with the small lateral semicircular canal malformations. The malformations were Michel deformity (1 ear), common cavity deformity (3 ears), incomplete partition I (3 ears), incomplete partition II (Mondini deformity, 5 ears), vestibular and semicircular canal malformations( 14 ears), vestibular aqueduct dilate( 16 ears, of which 6 ears accompanied by other malformations), the internal auditory canal malformation(8 ears, all accompanied by other malformations). CONCLUSION: MSCT allows a comprehensively assessing various congenital ear malformations through high quality MPR and VRT reconstructions. VRT images can display the site and degree of the malformations three-dimensionally and intuitionisticly. It is very useful to the cochlear implantation.

Adolescent↗
PubMedDate not supplied

Preoperative and postoperative assessment of rotational acetabular osteotomy for dysplastic hips in children by three-dimensional surface reconstruction computed tomography imaging.

The three-dimensional relationship between the acetabulum and femoral head was evaluated using three-dimensional computed tomography (CT) reconstruction before and after rotational acetabular osteotomy. This method provides exact anatomic information on acetabular coverage so that precise operative planning is more easily made. Evaluation of six dysplastic hips indicated the possible dangers of anterolateral rotational shift of the acetabulum when there is marked posterior deficiency, such as in the case of a high decree of subluxated femoral head covered by a shallow false acetabulum. In these circumstances, it may be safer and preferable to plan a lateral shift instead of an anterolateral shift.

Acetabulum↗
PubMed1988

Magnetic resonance imaging, computed tomography, and radionuclide scintigraphy in detection of liver metastases.

A series of 100 patients with suspected hepatic metastases was studied with magnetic resonance (MR), unenhanced computed tomography (CT), and radionuclide (RN) scintigraphy. Each set of images was read by three clinicians using a five-point scale to allow receiver operating characteristic (ROC) analysis using truth data derived from clinical review. Performance was measured by the areas under the ROC curves (0.940 +/- .018 for MR, 0.951 O +/- .013 for CT and 0.943 +/- .013 for RN) which were statistically not significantly different. We conclude that at their present level of development these three diagnostic examinations have equivalent performance and that MR is not superior in the detection of hepatic metastases.

Evaluation Studies as Topic↗
PubMed1997

Correlating sheet plastinated slices, computed tomography images and magnetic resonance images of the pelvic girdle: a teaching tool.

Sheet plastination is currently used to produce anatomical slices of different body structures, allowing one to study and teach their topography in an anatomically correct state. Correlation with computed tomography (CT) and magnetic resonance imaging (MRI) techniques gives more insight into their anatomy. Using two female cadaver pelvises CT and MRI were performed. One pelvis was used to prepare 2-mm-thick coronal plastinated slices according to the technique described by von Hagens. We found a good overall correlation between plastinated slices, CT and MRI images. This combined approach provides a unique anatomical insight and is a valuable addition to other teaching tools used by medical students, radiologists and anatomists.

Anatomy, Cross-Sectional↗
PubMed2005

Opacity transfer function optimization for volume-rendered computed tomography images of the prostate.

RATIONALE AND OBJECTIVES: The selection of an opacity transfer function is essential for volume visualization. Computed tomography (CT) scans of the pelvis were used to determine an optimal opacity transfer function for use in radiotherapy. MATERIALS AND METHODS: On sample datasets (a mathematical phantom and a patient pelvis CT scan), standard viewing orientations were selected to render the prostate. Opacity functions were selected via (1) trapezoidal manual selection, (2) trapezoidal semiautomatic selection, and (3) histogram volume-based selection. Using an established metric, the errors using each of these methods were computed. RESULTS: Trapezoidal manual opacity function optimization resulted in visually acceptable images, but the errors were considerable (6.3-9.1 voxel units). These errors could be reduced with the use of trapezoidal semiautomatic selection (4.9-6.2 voxel units) or with histogram volume-based selection (4.8-7.9 voxel units). As each visualization algorithm focused on enhancing the boundary of the prostate using a different approach, the scene information was considerably different using the three techniques. CONCLUSION: Improved volume visualization of soft tissue interfaces was achieved using automated optimal opacity function determination, compared with manual selection.

Algorithms↗
PubMed2002

Computed tomography image analysis of the calcaneus in male osteoporosis.

The present study aimed to characterize bone microarchitecture assessed by computed tomography (CT) at the calcaneus in male subjects suffering from osteoporosis. Seventy-nine subjects were assessed (45 with osteoporosis and 34 control subjects matched for age). Osteoporosis was defined according to the World Health Organization classification either at the lumbar spine or at the femoral neck. Thirty-three subjects (73%) had a past history of low-energy fracture mainly represented by vertebral fractures (24/33). Nine axial sections (1 mm in width and 2 mm apart) were selected for each subject. Bone microarchitecture analysis was performed using structural (binary and skeletonized images but also skeletonization from gray levels) and fractal analyses. Bone densitometry by dual-energy X-ray absorptiometry (DXA) at the calcaneus was also performed in 73 cases. Bone mineral density (BMD) was decreased in osteoporotic patients compared with controls both at the lumbar spine and hip and also at the calcaneus (p<0.01). Also 14 microarchitectural features among 25 measured were significantly different between the two groups (p<0.01). The odds ratio for fracture per 1 control group standard deviation decrease were also significant for 13 structural features but also for BMD at the calcaneus. The odds ratios after adjustment for BMD at the calcaneus were significant for the following features (p<0.05): number of valleys, 2.8 (1.2-6.9); trabecular partition, 3.3 (1.3-7.9); apparent trabecular spacing, 1.8 (1.0-3.1); trabecular bone pattern factor, 2.2 (1.1-4.3); Euler number, 3.0 (1.1-8.7); node-to-terminus strut count, 3.3 (1.4-7.8); terminus-to-terminus strut count, 2.9 (1.2-6.9); and fractal dimension, 3.7 (1.5-9.7). Few and weak correlations were found between BMD at the calcaneus measured with DXA and features obtained from CT, suggesting that these two methods give different information about bone status. In conclusion, male osteoporosis is a disease characterized by decreased bone mass but also by microarchitectural deterioration of bone tissue which is partly independent of BMD.

Absorptiometry, Photon↗
PubMed1996

Comparison of film, direct digital, and tuned-aperture computed tomography images to identify the location of crestal defects around endosseous titanium implants.

This study compared diagnostic performance obtained from two-dimensional and three-dimensional x-ray images. The latter were produced with a new tomosynthetic method based on aperture theory called tuned-aperture computed tomography. Seven human cadaver mandibular segments containing a total of 20 endosseous implants with a small randomly positioned alveolar crestal defect at each implant site were imaged in two dimensions with periapical film and with a charge-coupled digital detector, and digitally with the same detector in three dimensions with tuned-aperture computed tomography and subtracted tuned-aperture computed tomography techniques. Seven trained dentists viewed randomized displays of all modalities. Outcomes of the diagnostic task of identifying the locations of crestal defects were quantified with accuracy, confidence, and time performance measures. Analyses of variance demonstrated that differences between either three-dimensional technique and either two-dimensional modality were significant for all measures (p < 0.001). These findings suggest that clinically applied TACT methods hold promise as an improvement over the status quo.

Alveolar Bone Loss↗
PubMedDate not supplied

Angiomyolipoma of the kidney. Comparison between magnetic resonance imaging, computed tomography, and ultrasonography for diagnosis.

In six patients with angiomyolipoma of the kidney, five showed a typical pattern in T1, proton and T2 weighted images, with magnetic resonance imaging (MRI). Angiomyolipoma is recognized by its characteristic fatty tissue components, which result in high signal intensity in T1 and proton weighted images and a low signal in T2 weighted images. Five of the patients were also examined with ultrasonography (US); in four of these, the tumor could be recognized by its echodense pattern. Computed tomography (CT) was slightly less sensitive; three out of six examinations failed to produce a definite diagnosis. Instead of the typical low attenuation values of fat, Hounsfield units similar to either muscle or kidney tissue were observed in these 3 cases. In conclusion, the specific diagnosis of angiomyolipoma depends on the amount of fatty tissue present at MRI, CT, and sonography.

Adult↗
PubMed2003

[Three dimensional spiral computed tomography imaging in preop diagnosis of substernal goiter (preliminary study)].

The aim of the study was the estimation of substernal goiter by use of three-dimensional spiral computed tomography (3-D sCT) with the contrast agent. The size and anatomy of goiter as well as its relation to surrounding tissues, particularly blood vessels was evaluated. The examination allowed good visualization of both inferior thyroid arteries. The use of 3-D sCT may have a great meaning in preoperative examination in particular in technically difficult cases of substernal goiter.

Arteries↗
PubMed1994

Three-dimensional computed tomography imaging in the evaluation of craniofacial abnormalities.

A retrospective study was undertaken to assess the value of three-dimensional computed tomography (3-D CT) in evaluating craniofacial abnormalities. Over a 2-year period, 145 children evaluated with routine two-dimensional (2-D) CT had 3-D CT reformatted images assessing a variety of anomalies including craniosynostosis, midface clefts, trauma, and craniofacial syndromes. There were 62 females and 83 males ranging in age from 1 month to 17 years (median: 5 months). Both soft-tissue and bone algorithms were used. In all 145 cases, the 3-D CT images confirmed or provided additional information of depth perception, contours, volumes, and extent of an abnormality. This was especially important and useful in the settings of complex anomalies and preoperative planning. We concluded that 3-D CT reconstructed images in conjunction with routine 2-D CT should be an integral part of the examination in evaluating craniofacial abnormalities.

Adolescent↗