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At least 397 records · Page 22Linked to original sources
PubMed1996

Computed tomography slice-by-slice target-volume delineation for stereotactic proton irradiation of large intracranial arteriovenous malformations: an iterative approach using angiography, computed tomography, and magnetic resonance imaging.

PURPOSE: Target-volume delineation for stereotactic irradiation is problematic for large and irregularly shaped arteriovenous malformations (AVMs). The purpose of this report is to quantify modifications in the target volume that result from iterative treatment planning that incorporates multimodality imaging data. METHODS AND MATERIALS: Stereotactic neuroimaging procedures were performed for 20 consecutive patients with AVM volumes > 10 cm3. Angiographically defined extrema were transformed into computed tomography (CT) space. The resulting target contours were then modified by a multidisciplinary treatment planning team after iterative review of angiographic, CT, and magnetic resonance imaging (MRI) data. Volumes of interest and dose-volume histograms for proton irradiation were calculated before and after iterative target delineation. RESULTS: Initial (angiographically defined) target volumes ranged from 15.3 to 96.1 cm3 (mean, 43.6 cm3). Final (iteratively defined) target volumes ranged from 10.7 to 114.0 cm3 (mean, 38.4 cm3). The volume of presumed normal tissue excluded by iterative planning ranged from 2.6 to 47.0 cm3 (mean, 15.5 cm3). Initially untargeted AVM, most commonly obscured by embolization material, was identified in all cases (range, 0.3 to 57.8 cm3; mean, 10.3 cm3). Corresponding dose-volume histograms demonstrated marked differences regarding lesion coverage and sparing of normal tissue structures. CONCLUSIONS: Iterative target-volume delineation resulted in significant modifications from initial, angiographically defined target volumes. Substantial amounts of apparently normal tissue were excluded from the final target, and additional abnormal vascular structures were identified for incorporation. We conclude that an iterative multimodality approach to target-volume delineation may improve the overall results for stereotactic irradiation of large and complex AVMs.

Humans↗
PubMed1992

Computed cranial tomography, magnetic resonance imaging and single photon emission computed tomography in hemorrhagic shock and encephalopathy syndrome: a report of three cases.

Three different neuro-imaging studies were performed in 3 infants with hemorrhagic shock and encephalopathy syndrome (HSE). Areas of cerebral infarction were noted on CT. Single photon emission computed tomography (SPECT) showed decreased perfusion in these areas in one infant. Magnetic resonance imaging (MRI) also identified the areas of infarction, noted on CT, but provided additional information showing non-haem iron deposition in the thalami and basal ganglia.

Brain↗
PubMed1988

Single photon emission computed tomography and transmission computed tomography in the evaluation of liver disease.

To assess the relative strengths of hepatic SPECT and transmission computed tomography (TCT), a comparison of these methods was made in 88 patients during a 20-month period. The scans were classified into four categories: normal, solitary focal, multifocal, or diffuse hepatocellular patterns. The final disease category was determined by histologic evaluation-biopsy/autopsy, surgery, or a combination of ultrasound, laboratory, and clinical follow-up for a minimum of 6 months. Both SPECT and TCT were normal in the 47 patients classified as normal. Of the 16 patients with diffuse hepatocellular disease, SPECT correctly identified 16 and TCT identified two patients. Eleven patients had solitary focal disease; 11 were detected by SPECT and 10 by TCT. Fourteen patients were in the multifocal disease group; 13 were detected by SPECT and 10 by TCT. Overall, SPECT and TCT findings were in agreement in 68 (77%) of the cases. This study demonstrates that SPECT is equal to TCT in the assessment of the liver parenchyma in normal and focal disease states and that SPECT is superior in the assessment of diffuse disease.

Adult↗
PubMed1994

Comparison of spiral computed tomography versus conventional computed tomography multiplanar reconstructions of a fracture displacement phantom.

PURPOSE: The capabilities of spiral computed tomography (CT) versus conventional CT to represent minimal fracture displacements on multiplanar reconstruction images in a phantom model were evaluated. MATERIALS AND METHODS: A displacement phantom was created from Teflon and was scanned with conventional and spiral CT, at slice collimations of 2 mm, 3 mm, and 5 mm. Three Z-axis interpolation algorithms (360_LI, 180_LI and 180_HI) were employed to process the spiral image data into planar images. Displacements of 5 mm or less were represented in the phantom, and the resultant multiplanar reconstructions were analyzed for the precision of displacement representation. Specifically, the edge profiles of the reconstructed images were measured and compared. RESULTS: Spiral CT reconstruction edge profiles were similar to those of conventional CT when minimal table increments (3 mm/sec or less), and an advanced interpolation algorithm (180_LI) was employed. Images obtained with 360_LI interpolation manifested the effect of widened slice profile even when employing minimal table speeds. CONCLUSIONS: With minimal table increment (3 mm/sec or less) and a high-order interpolation algorithm (180_LI), spiral-CT-derived reconstructions demonstrate similar edge profile resolution to reconstructions obtained from conventional CT.

Algorithms↗
PubMed1997

Usual interstitial pneumonia. Quantitative assessment of high-resolution computed tomography findings by computer-assisted texture-based image analysis.

RATIONALE AND OBJECTIVES: The authors developed a texture-based pattern recognition and segmentation tool for the quantitation of high-resolution computed tomography (HRCT) findings in usual interstitial pneumonia (UIP). METHODS: In HRCT images of five patients with UIP and five patients without UIP, 1022 regions of interest (ROIs) of 5 x 5 pixels were classified by the examiner to be normal, emphysematous, ground-glass lesion, intralobular fibrosis, vessel, or bronchus section. The classes and the texture parameters calculated in the ROIs were the basis for the decision rule, using a multivariate discrimination analysis. The classification was compared with the examiner's diagnosis in 1889 new randomly selected ROIs. RESULTS: Depending on the structure, the sensitivity (the probability that a structure would be recognized correctly) was 68.7% to 80.7%. If the system classified a structure as normal, ground glass or fibrotic region, this was correct in 77.3% to 88.1%. However, the system's diagnosis of a bronchus section was correct in only 16.2%. The overall accuracy was 70.7%. CONCLUSIONS: Texture-based segmentation may be a valuable tool to aid the quantitative assessment of parenchymal disease in HRCT images.

Adult↗
PubMed2004

The potential contribution of a computer-aided detection system for lung nodule detection in multidetector row computed tomography.

RATIONALE AND OBJECTIVES: We sought to evaluate the potential benefits of a computer-aided detection (CAD) system for detecting lung nodules in multidetector row CT (MDCT) scans. METHODS: A CAD system was developed for detecting lung nodules on MDCT scans and was applied to the data obtained from 15 patients. Two chest radiologists in consensus established the reference standard. The nodules were categorized according to their size and their relationship to the surrounding structures (nodule type). The differences in the sensitivities between an experienced chest radiologist and a CAD system without user interaction were evaluated using a chi2 analysis. The differences in the sensitivities also were compared in terms of the nodule size and the nodule type. RESULTS: A total of 309 nodules were identified as the reference standard. The sensitivity of a CAD system (81%) was not significantly different from that of a radiologist (85%; P > 0.05). The sensitivities of the CAD system for detecting nodules < or = 5 mm in diameter as well as detecting isolated nodules were higher than those of a radiologist (83% vs. 75%, P > 0.05; 93% vs. 76%, P < 0.001). The sensitivities of a radiologist for detecting nodules >5 mm and the nodules attached to other structures were higher than those of a CAD system (98% vs. 79%, P < 0.001; 91% vs. 71%, P < 0.001). There were 28.8 false-positive results of CAD per CT study. CONCLUSION: The CAD system developed in this study performed the nodule detection task in different ways to that of a radiologist in terms of the nodule size and the nodule type, which suggests that the CAD system can play a complementary role to a radiologist in detecting nodules from large CT data sets.

Adult↗
PubMedDate not supplied

Computed tomography urography with 16-channel multidetector computed tomography: a pictorial review.

Excretory phase computed tomography (CT) urography obtained with a 16-slice multidetector CT scanner using thin-section images (slice thickness = 0.75 mm, reconstruction increment = 0.5 mm) combined with interactive reformatted and 3-dimensional reconstruction techniques, high spatial resolution images of the urinary tract similar to those of classic intravenous urography can be produced. The purpose of this pictorial essay is to review the early experience of the authors and to show the wide range of abnormalities of the urinary tract detected with this technique.

Humans↗
PubMedDate not supplied

Comparison of cerebral blood flow between perfusion computed tomography and xenon-enhanced computed tomography for normal subjects: territorial analysis.

OBJECTIVE: The purpose of this study was to clarify the difference between cerebral blood flow (CBF) by perfusion computed tomography (CT) and that by xenon-enhanced CT (Xe-CT) through simultaneous measurement. METHODS: Xenon-enhanced CT and perfusion CT were continually performed on 7 normal subjects. Ratios of CBF by perfusion CT (P-CBF) to CBF by Xe-CT (Xe-CBF) were measured for 5 arterial territories; 3 were territories of 3 major arteries (the anterior [ACA], middle [MCA], and posterior [PCA] cerebral arteries), and the other 2 were areas of the thalamus and putamen. RESULTS: The ratios were 1.30 +/- 0.10, 1.26 +/- 0.15, 1.61 +/- 0.15, 0.801 +/- 0.087, and 0.798 +/- 0.080 for the ACA, MCA, PCA, thalamus, and putamen, respectively. Although a good correlation was observed between P-CBF and Xe-CBF for each territory, the ratios were significantly different (P < 0.0001) between 3 territory groups (group 1: ACA and MCA, group 2: PCA, and group 3: thalamus and putamen). CONCLUSIONS: The difference in the ratio of P-CBF to Xe-CBF between the 3 territory groups was considered to result principally from the features of P-CBF. To evaluate P-CBF properly, its territorial characteristics should be taken into account.

Adult↗
PubMed1986

Fast computer processing for tissue highlighting in computed tomographic cross-sectional imaging and digital scan projection radiography.

A simple, fast, computer method of simultaneously highlighting edge detail and emphasising soft-tissue contrast is discussed. An objective comparison is made with conventional blurred mask subtraction using the signal-to-noise ratio from phantom scans. The use of the algorithm for inner ear studies and digital scanned projection radiography is presented.

Computers↗
PubMed1994

Psychology of computer use: XXXII. Computer screen-savers as distractors.

The differences in performance of 16 male and 16 female undergraduates on three cognitive tasks were investigated in the presence of visual distractors (computer-generated dynamic graphic images). These tasks included skilled and unskilled proofreading and listening comprehension. The visually demanding task of proofreading (skilled and unskilled) showed no significant decreases in performance in the distractor conditions. Results showed significant decrements, however, in performance on listening comprehension in at least one of the distractor conditions.

Adolescent↗
PubMedDate not supplied

Application of computers in diabetes care--a review. II. Computers for decision support and education.

This paper concludes a review of the contribution of information technology to diabetes care. The role of decision support tools for planning insulin therapy using various clinical algorithms, knowledge-based approaches and interactive simulations is discussed, and certain telemedicine approaches to therapy are considered. The validation and clinical evaluation of these tools is reviewed, as is the likely impact of the routine clinical application of implantable/non-invasive blood glucose monitoring devices. Finally, the application of computers as teaching tools is considered, and ways in which such educational approaches might be applied for disseminating the benefits of the Diabetes Control and Complications Trial more widely are discussed.

Artificial Intelligence↗
PubMed2006

[Development of computer-aided diagnostic system for detection of lung nodules in three-dimensional computed tomography images].

We have developed an automated computerized method for the detection of lung nodules in three-dimensional (3D) computed tomography (CT) images obtained by helical CT. In this scheme, a lung segmentation technique for the determination of the nodule search area is performed based on a gray-level thresholding technique. To enhance lung nodules, we employed the 3D cross-correlation method by using a 3D Gaussian template with zero-surrounding as a model of lung nodule. False positives are then eliminated by using a rule-base with 53 features. For further reduction of false positives, we performed linear discriminant analysis using these 53 features. The average number of false positives was 6.7 per case at a percent sensitivity of 85.0%. This computerized scheme will be useful to radiologists by providing a "second opinion" in case of possible early lung cancer.

Diagnosis, Computer-Assisted↗
PubMed1999

[Assessment of left ventricular function by electrocardiogram-gated myocardial single photon emission computed tomography using quantitative gated single photon emission computed tomography software].

Electrocardiogram (ECG)-gated myocardial single photon emission computed tomography (SPECT) can assess left ventricular (LV) perfusion and function easily using quantitative gated SPECT (QGS) software. ECG-gated SPECT was performed in 44 patients with coronary artery disease under post-stress and resting conditions to assess the values of LV functional parameters, by comparison to LV ejection fraction derived from gated blood pool scan and myocardial characteristics. A good correlation was obtained between ejection fraction using QGS and that using cardiac blood pool scan (r = 0.812). Some patients with myocardial ischemia had lower ejection fraction under post-stress compared to resting conditions, indicating post-stress LV dysfunction. LV wall motion and wall thickening were significantly impaired in ischemic and infarcted myocardium, and the degree of abnormality in the infarcted areas was greater than in the ischemic area. LV functional parameters derived using QGS were useful to assess post-stress LV dysfunction and myocardial viability. In conclusion, ECG-gated myocardial SPECT permits simultaneous quantitative assessment of myocardial perfusion and function.

Electrocardiography↗
PubMed2004

[Comparison of myocardial perfusion assessed by Tc99m MIBI single photon emission computer tomography (SPECT) with the Coronary Calcium Score (CS) assessed by multi-slice computer tomography (MSCT)].

BACKGROUND: There is growing evidence regarding evaluation of Coronary Artery Calcium Score (CS) using the multi-slice computer tomography (MSCT), but as a new method it still need for verification in comparison with other, non-invasive modalities, with established rationale. One of these is SPECT, which value in evaluation of patients with coronary artery disease is well known. We tried to compare these two studies and their usefulness in diagnosis of patients with confirmed coronary artery disease. MATERIAL AND METHODS: 72 patients (53 males and 19 females, mean age 59.9 +/- 8.66), all after coronary angiography, with coronary artery disease (CCS II or III) were included into our study. SPECT and exercise treadmill results were compared with the coronary artery calcium score (CS) as assessed by MSCT. Both studies were performed with maximal 7-days intervals at most between the studies. Image reconstruction was performed using the Autoperfusion protocol, with the VISUAL Score analysis (5-point scale) of extent of perfusion defect. MSCT was evaluated using the Calcium Score protocol. For the statistical analysis we used Student's T-test and Pearson correlation analysis. RESULTS: The correlation between total CS and the score of the reversible and non-reversible perfusion defects in Tc 99mMIBI SPECT was not found. Following the analysis for the 3 main coronary arteries separately, and number of perfusion defects, a correlation was observed for LAD and RCA perfusion regions. CONCLUSIONS: 1. Statistically significant correlation between CS by MSCT and SPECT perfusion deficiencies in the left descending artery (LAD) and right coronary artery (RCA) perfusion regions were found. 2. The correlation between high CS (>400) and the presence of hemodynamically significant changes in coronary angiography was found. 3. We conclude that CS by MSCT may be a screening-tool of some value for risk stratification.

Aged↗
PubMed2005

Developments in nuclear cardiology: transition from single photon emission computed tomography to positron emission tomography-computed tomography.

Recent advances in positron emission tomography (PET) instrumentation have paralleled those of multichannel computed tomography (CT) for cardiac applications. Whereas multichannel CT angiography provides information on the presence and extent of anatomical luminal narrowing of epicardial coronary arteries, stress myocardial perfusion PET provides information on the downstream functional consequences of such anatomic lesions. With the advent of hybrid PET/CT systems, such complementary information of anatomy and physiology can be realized immediately at the same imaging session. By acquiring dynamic, gated myocardial perfusion data, PET studies provide insight into impairment of regional coronary blood flow reserve and microvascular endothelial dysfunction. This paper presents recent developments in PET detector materials, acquisition modes, combined PET/CT scanners, rubidium-82 (Rb-82) gated myocardial perfusion studies and analysis methods for absolute myocardial blood flow quantification.

Coronary Disease↗
PubMedDate not supplied

[Changes in the brain of persons who participated in the cleaning-up of the Chernobyl AES accident based on the data of radiodiagnosis (single-photon emission-computed radionuclide tomography, x-ray computed tomography and magnetic resonance tomography)].

Presents the data of x-ray examinations of the brain in cleaner-ups of the consequences of the Chernobyl power plant accident who complained of headaches, ache in the bones, poor memory, giddiness, weakness, a drastic drop of performance ability, fits with loss of consciousness. Hypometabolic foci localized both in the white and gray matter of the brain were revealed. X-Ray computer-aided tomography and magnetic imaging showed dilatation of the ventricular system of the brain, dilatation of the subarachnoidal spaces, symmetrical reduction of the density of medullary tissue round the bodies and anterior and posterior horns of lateral ventricles, round the third ventricle, near semi-oval centers, as well as solitary or multiple focal reduction of medullary tissue density. Findings of x-ray methods of diagnosis permit a conclusion on a complex organic involvement of the brain in subjects who participated in liquidation of the consequences of the Chernobyl power plant accident. The most typical are signs of the hypertensive hydrocephalic syndrome with cerebrospinal fluid disturbances and of the vascular encephalic syndrome with development of focal postischemic malacia of the brain matter.

Adult↗