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Results for “computed tomography imaging”

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PubMedDate not supplied

Coregistration of magnetic resonance and single photon emission computed tomography images for noninvasive localization of stem cells grafted in the infarcted rat myocardium.

This paper demonstrates the application of mutual information based coregistration of radionuclide and magnetic resonance imaging (MRI) in an effort to use multimodality imaging for noninvasive localization of stem cells grafted in the infarcted myocardium in rats. Radionuclide imaging such as single photon emission computed tomography (SPECT) or positron emission tomography (PET) inherently has high sensitivity and is suitable for tracking of labeled stem cells, while high-resolution MRI is able to provide detailed anatomical and functional information of myocardium. Thus, coregistration of PET or SPECT images with MRI will map the location and distribution of stem cells on detailed myocardium structures. To validate this coregistration method, SPECT data were simulated by using a Monte Carlo-based projector that modeled the pinhole-imaging physics assuming nonzero diameter and photon penetration at the edge. Translational and rotational errors of the coregistration were examined with respect to various SPECT activities, and they are on average about 0.50 mm and 0.82 degrees , respectively. Only the rotational error is dependent on activity of SPECT data. Stem cells were labeled with (111)Indium oxyquinoline and grafted in the ischemic myocardium of a rat model. Dual-tracer small-animal SPECT images were acquired, which allowed simultaneous detection of (111)In-labeled stem cells and of [(99m)Tc]sestamibi to assess myocardial perfusion deficit. The same animals were subjected to cardiac MRI. A mutual-information-based coregistration method was then applied to the SPECT and MRIs. By coregistration, the (111)In signal from labeled cells was mapped into the akinetic region identified on cine MRIs; the regional perfusion deficit on the SPECT images also coincided with the akinetic region on the MR image.

Animals↗

PubMed2005

Multidetector row computed tomography: imaging congenital coronary artery anomalies in adults.

The quality of the imaging of the main coronary arteries and side branches provided by multidetector row computed tomography (MDCT) may have importance when assessing congenital coronary artery anomalies. This review discusses the rationale for using MDCT for this indication and examines the advantages and disadvantages of the technique. Examples of MDCT imaging of congenital coronary artery anomalies are presented. These images provide persuasive evidence to support clinical use of MDCT cardiac imaging in the context of suspected congenital coronary artery anomalies as a first line investigation.

Adult↗

PubMed2000

Rectal methohexital sedation for computed tomography imaging of stable pediatric emergency department patients.

OBJECTIVE: Rapid onset of sleep, brief duration of action, and ease of administration are properties that make rectal methohexital (MXT) an attractive choice for sedating stable pediatric emergency department (ED) patients for computed tomography (CT) imaging. METHODOLOGY: One hundred stable patients between 3 and 60 months of age who presented to any of 3 participating EDs and required sedation to undergo CT scanning were given 25 mg/kg of rectal MXT approximately 15 minutes before their imaging. Vital signs and oxygen saturation were recorded at regular intervals. Data collected included indication for CT imaging, time to achieve sleep, time to reach discharge criteria, adequacy of sedation, adverse effects, and parental satisfaction. RESULTS: Ninety-five percent of the patients were adequately sedated with rectal MXT. It took an average of 8 minutes to achieve full sedation and the duration of action averaged 79.3 minutes. Ten percent had transient side effects, but all recovered completely. None required intubation. Parental satisfaction was 90%. CONCLUSION: Rectal MXT compares favorably to other methods of nonintravenous sedation for CT scanning of stable pediatric ED patients in terms of rapidity of onset and reliability but does cause a significant amount of transient respiratory depression. Its use requires careful monitoring of oxygen saturation and should be used only in a setting where physicians skilled in airway management are present. If these requirements are met, it may be a good choice for the relatively noninvasive sedation of pediatric ED patients undergoing painless but anxiety-provoking procedures.methohexital, pediatric procedure sedation, rectal administration, computerized tomography imaging.

Administration, Rectal↗

PubMed1989

Measurement of acute Q-wave myocardial infarct size with single photon emission computed tomography imaging of indium-111 antimyosin.

Myocardial infarct size was measured by single photon emission computed tomography (SPECT) following injection of indium-111 antimyosin in 27 patients (18 male and 9 female; mean age 57.4 +/- 10.5 years, range 37 to 75) who had acute transmural myocardial infarction (MI). These 27 patients represent 27 of 35 (77%) consecutive patients with acute Q-wave infarctions who were injected with indium-111 antimyosin. In the remaining 8 patients either tracer uptake was too faint or the scans were technically inadequate to permit infarct sizing from SPECT reconstructions. In the 27 patients studied, infarct location by electrocardiogram was anterior in 15 and inferoposterior in 12. Nine patients had a history of prior infarction. Each patient received 2 mCi of indium-111 antimyosin followed by SPECT imaging 48 hours later. Infarct mass was determined from coronal slices using a threshold value obtained from a human torso/cardiac phantom. Infarct size ranged from 11 to 87 g mean 48.5 +/- 24). Anterior infarcts were significantly (p less than 0.01) larger (60 +/- 20 g) than inferoposterior infarcts (34 +/- 21 g). For patients without prior MI, there were significant inverse correlations between infarct size and ejection fraction (r = 0.71, p less than 0.01) and wall motion score (r = 0.58, p less than 0.01) obtained from predischarge gated blood pool scans. Peak creatine kinase-MB correlated significantly with infarct size for patients without either reperfusion or right ventricular infarction (r = 0.66). Seven patients without prior infarcts had additional simultaneous indium-111/thallium-201 SPECT studies using dual energy windows.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed2000

Use of three-dimensional computed tomography images in deciding the approach for ministernotomy operations.

BACKGROUND: In ministernotomy operations for valvular and congenital heart diseases, several approaches exist. Because topographical relationships of the sternum, ribs, heart, and great vessels differ slightly with each patient, three-dimensional (3D) computed tomography (CT) images are valuable in deciding the best approach for each patient. METHODS: Ministernotomy patients were studied preoperatively using 3D-CT images. By subtracting some parts of the sternum and the ribs from the 3D images, the topographical relationships of the structures were revealed. RESULTS: Different methods of approach (ie, the site, shape, and length of partial sternotomy) were compared on the 3D images of each patient to decide the most appropriate incision. The images were shown to resemble closely the actual operative field. CONCLUSIONS: Three-dimensional CT images are valuable in preoperative planning of ministernotomy, and are essential to individualized planning for each operation.

Humans↗

PubMedDate not supplied

Thallium-201 single-photon emission computed tomography imaging in a pediatric brain tumor. A case report.

Thallium brain single-photon emission computed tomography (SPECT) may be useful for differentiation of tumor recurrence from scar tissue and radiation necrosis and to predict low or high grade brain tumors. We report a case of an 11-year-old boy with recurrent oligodendroglioma who showed increased focal uptake of thallium-201 at the site of recurrence after surgery and radiotherapy on a SPECT imaging of the brain. This indicates viable tumor mass as opposed to radiation necrosis.

Brain Neoplasms↗

PubMed2001

Fractal analyses of osseous healing using tuned aperture computed tomography images.

The aim of this study was to evaluate osseous healing in mandibular defects using fractal analyses on conventional radiographs and tuned aperture computed tomography (TACT; OrthoTACT, Instrumentarium Imaging, Helsinki, Finland) images. Eighty test sites on the inferior margins of rabbit mandibles were subject to lesion induction and treated with one of the following: no treatment (controls); osteoblasts only; polymer matrix only; or osteoblast-polymer matrix (OPM) combination. Images were acquired using conventional radiography and TACT, including unprocessed TACT (TACT-U) and iteratively restored TACT (TACT-IR). Healing was followed up over time and images acquired at 3, 6, 9, and 12 weeks post-surgery. Fractal dimension (FD) was computed within regions of interest in the defects using the TACT workbench. Results were analyzed for effects produced by imaging modality, treatment modality, time after surgery and lesion location. Histomorphometric data were available to assess ground truth. Significant differences (p < 0.0001) were noted based on imaging modality with TACT-IR recording the highest mean fractal dimension (MFD), followed by TACT-U and conventional images, in that order. Sites treated with OPM recorded the highest MFDs among all treatment modalities (p < 0.0001). The highest MFD based on time was recorded at 3 weeks and differed significantly with 12 weeks (p < 0.035). Correlation of FD with results of histomorphometric data was high (r = 0.79; p < 0.001). The FD computed on TACT-IR showed the highest correlation with histomorphometric data, thus establishing the fact TACT is a more efficient and accurate imaging modality for quantification of osseous changes within healing bony defects.

Animals↗

PubMed1995

Evaluation of lymph nodes on computed tomography images in epidermoid lung cancer.

This study was undertaken to design the optimal criteria for practical guidelines for lymph node metastasis evaluation in epidermoid lung cancer. Resected lymph nodes (n = 214) were analyzed by preoperative computed tomography (CT) images and postoperative histopathological findings. Definite criteria were defined by efficiency, and possible criteria by receiver operating characteristic (ROC) analysis. Statistical values of highest efficiency in 214 lymph nodes revealed that the minor axis offered the best criteria (minor axis 13 mm; efficiency 93%). ROC curve using the minor axis which showed the highest values of sensitivity and specificity in the optimal criteria (minor axis 9.3 mm; sensitivity 76%, specificity 76%). The criteria of the paratracheal lymph nodes were smaller than those of tracheobronchial and subcarinal nodes. In conclusion, it is desirable to evaluate metastasis of lymph nodes by the minor axis, and criteria should be considered changeable to accommodate the anatomical location in epidermoid lung cancer.

Carcinoma, Squamous Cell↗

PubMed2003

Efficacy of iodine-123-15-(p-iodophenyl)-3-R, S-methylpentadecanoic acid single photon emission computed tomography imaging in detecting myocardial ischemia in children with Kawasaki disease.

To evaluate its efficacy in detecting myocardial ischemia in children, iodine-123-labeled 15-(p-iodophenyl)-3-R, S-methylpentadecanoic acid (BMIPP) myocardial single photon emission computed tomography (SPECT) imaging was performed in 16 pediatric patients with Kawasaki disease (KD, 11 male, 5 female; mean age and range: 13 years 8 months and 8 years 11 months to 17 years 7 months). Five children with chest pain and no cardiac disease were studied as controls (2 male, 3 female; mean age and range: 13 years 4 months and 9 years 4 months to 17 years 11 months). Selective coronary angiography was also performed in the 16 patients to evaluate the location of coronary stenosis and coronary aneurysms. The SPECT images were expressed as polar maps (Bull's eye maps) and the 'defect' area was defined as where the uptake of BMIPP was less than the standardized BMIPP images of the 5 control children. In the 16 patients, 33 segments had coronary aneurysms and 10 (10/33: 30.3%) had significant coronary stenosis on selective coronary angiography. Nine of the 10 (90%) segments with significant coronary stenosis showed a defect on the BMIPP image whereas only 6 of the 23 (26.1%) segments without coronary stenosis showed a defect on BMIPP imaging. The sensitivity of BMIPP SPECT imaging for detection of coronary stenosis was 90% (9/10) and its specificity was 73.9% (17/23), whereas the sensitivity of (201)Tl SPECT imaging was 80% (8/10) and its specificity was 60% (14/23). There was no significant difference between the BMIPP and 201Tl SPECT images in either the sensitivity or specificity for the detection of coronary stenosis. In the present series, only one case had discordant BMIPP uptake (BMIPP uptake < (201)Tl uptake) in which there was a large coronary aneurysm and re-canalization after complete obstruction at segment 1 of the right coronary artery. This discordant BMIPP uptake reflects the possibility of ischemic but viable myocardium after re-canalization of a large aneurysm in KD. In conclusion, BMIPP SPECT imaging is useful for detecting the areas of ischemic myocardium caused by coronary artery stenosis in children with KD.

Adolescent↗

PubMed1999

Direct identification of ventrointermediate nucleus of the thalamus on magnetic resonance and computed tomography images.

OBJECTIVE: The ventro-intermediate (Vim) nucleus of the thalamus is a commonly used target for the treatment of tremor. The thalamic fasciculus contains myelinated fibers, believed to play a role in the generation of tremor, that converge into a dense bundle at the inferior aspect of the Vim nucleus, making it visible on magnetic resonance (MR) and computed tomography (CT) images. This structure, therefore, can be visualized directly and targeted for thalamotomy. METHODS: Thalamotomies were performed on nine patients (who have a follow-up of 13-23 months) with parkinsonian and essential tremors using MR and CT images. The tremor target was hypointense on MR images obtained in inversion recovery sequence and hypointense on CT images. It was therefore visualized, directly targeted, and probed. Stimulation studies were done to physiologically confirm accuracy of the probe placement and then a radiofrequency lesion was made. RESULTS: Stimulation of the target identified as the Vim nucleus on MR and CT images produced responses similar to those expected from the Vim nucleus. After this site was lesioned tremor disappeared in all nine patients. CONCLUSION: The Vim nucleus of the thalamus is visible on MR and CT images. Destruction of this target abolishes parkinsonian and essential tremors.

Aged↗

PubMed2007

Fast retrospectively gated quantitative four-dimensional (4D) cardiac micro computed tomography imaging of free-breathing mice.

OBJECTIVE: We sought to demonstrate retrospectively gated dynamic 3D cardiac micro computed tomography (CT) of free-breathing mice. MATERIALS AND METHODS: Five C57Bl6 mice were scanned using a cone-beam scanner with a slip-ring-mounted flat-panel detector. After the injection of an intravascular iodinated contrast agent, projection images were acquired over the course of 50 seconds, while the scanner rotated through 10 complete rotations. The mouse respiratory and electrocardiogram signals were recorder simultaneously with image acquisition. After acquisition, the projection images were retrospectively sorted into projections belonging to different cardiac time points, occurring only during expiration. RESULTS: Dynamic 3D cardiac images, with isotropic 150-microm voxel spacing, were reconstructed at 12-millisecond intervals throughout the cardiac cycle in all mice. The average ejection fraction and cardiac output were 58.2+/-4.6% and 11.4+/-1.3 mL/min, respectively. The measured entrance dose for the entire scan was 28 cGy. Repeat scans of the same animals showed that intrasubject variability was smaller than intersubject variability. CONCLUSIONS: We have developed a high-resolution micro computed tomography method for evaluating the cardiac function and morphology of free-breathing mice in acquisition times shorter than 1 minute.

Animals↗

PubMed2002

Improved diagnostic performance of thallium-201 myocardial perfusion scintigraphy in coronary artery disease: from planar to single photon emission computed tomography imaging.

BACKGROUND: This study was performed to compare Tl-201 myocardial perfusion single photon emission computed tomography (SPECT) with planar scintigraphy in the diagnosis of coronary artery disease (CAD). METHODS: Retrospectively, 240 of 3262 patients, with exercise-redistribution Tl-201 myocardial perfusion scintigraphy performed between January 1990 and October 1997, were analyzed to compare Tl-201 scintigraphy and coronary arteriography. Within 30 days, all 240 patients underwent both coronary arteriography and exercise-redistribution Tl-201 myocardial perfusion scintigraphy with 86 SPECT and 154 planar images acquired. RESULTS: The sensitivities of Tl-201 myocardial perfusion scintigraphy in individual coronary arteries including left anterior descending (LAD) artery, left circumflex (LCX) artery, and right coronary artery (RCA), were 77%/72%, 31%/30%, and 77%/50% in the SPECT/planar study groups, respectively. The sensitivities of CAD detection in patients with single-vessel, double-vessel, and triple-vessel diseases were 96%/82%, 91%/85%, and 96%/90% in the SPECT/planar study groups, respectively. CONCLUSION: SPECT images provide greater advantages over planar images for better detection of the number, location, and extent of CAD. Cardiac SPECT does improve the accurate interpretation in abnormal Tl-201 distributions due to the higher contrast resolution and better separation of overlapping myocardial regions.

Adult↗

PubMed1994

A patient-to-computed-tomography image registration method based on digitally reconstructed radiographs.

An automatic method for the accurate registration of computed tomography (CT) data with two camera-calibrated radiographs is presented. The registration is based on the skull as visualized both in the plain radiographs and in radiographs digitally reconstructed from CT. A reference coordinate system is established based on the radiographic projection parameters obtained using an angiographic stereotactic localizer. The CT-derived reconstructed radiographs are aligned iteratively at multiple resolutions until a best match is found by adjusting the position and orientation of the CT data set relative to the reference coordinate system. The results of experiments with a skull phantom performed under stereotactic control which show that reliable registration is possible with an accuracy better than 1 mm are presented. Possible applications include intraoperative patient-to-CT frameless registration and registration of radiographic data with frameless CT for depth electroencephalogram electrode position confirmation.

Algorithms↗

PubMed1995

Neural network reconstruction of single-photon emission computed tomography images.

An artificial neural network (ANN) trained on high-quality medical tomograms or phantom images may be able to learn the planar data-to-tomographic image relationship with very high precision. As a result, a properly trained ANN can produce comparably accurate image reconstruction without the high computational cost inherent in some traditional reconstruction techniques. We have previously shown that a standard backpropagation neural network can be trained to reconstruct sections of single photon emission computed tomography (SPECT) images based on the planar image projections as inputs. In this study, we present a method of deriving activation functions for a backpropagation ANN that make it readily trainable for full SPECT image reconstruction. The activation functions used for this work are based on the estimated probability density functions (PDFs) of the ANN training set data. The statistically tailored ANN and the standard sigmoidal backpropagation ANN methods are compared both in terms of their trainability and generalization ability. The results presented show that a statistically tailored ANN can reconstruct novel tomographic images of a quality comparable with that of the images used to train the network. Ultimately, an adequately trained ANN should be able to properly compensate for physical photon transport effects, background noise, and artifacts while reconstructing the tomographic image.

Algorithms↗

PubMedDate not supplied

Guidelines for the delineation of nodal regions of the head and neck on axial computed tomography images.

Delineation of target volumes is increasingly recognized as the most crucial step within the process of modern conformal radiotherapy. In the field of head and neck radiation oncology, the need for a standardized methodology in the delineation of nodal regions of the neck on computed tomography (CT) images has recently emerged. To address this issue, a consensus document has been prepared by the Head and Neck Working Party of the AIRO-Lombardia Cooperative Group, based on the proceedings of multidisciplinary meetings and on literature findings. The document contains detailed guidelines for the delineation on CT images of the nodal regions of the neck, including for each nodal region (1 to 7) the description of anatomical limits as seen on CT images.

Head and Neck Neoplasms↗

PubMed1984

Analysis of x-ray computed tomography images using the noise power spectrum and autocorrelation function.

A discrete representation of the reconstruction process, consistent with the method of data collection, has been used to derive expressions for the noise power spectrum, autocorrelation function and noise equivalent quanta (NEQ) of a computed tomography (CT) image. These parameters have been expressed in terms of basic scanning factors such as tube current, exposure time, slice width and number of detectors. Each of these factors affects the overall magnitude of the noise power spectrum, but the spatial frequency dependence is also determined by the type of reconstruction filter used in the computer algorithm. The noise power spectrum has been calculated for scanners employing either a ramp or Hanning weighted ramp filter. Predictions made from this theoretical analysis have been compared with experimental measurements made on various CT scanners. Measurements were made of the modulation transfer function (MTF) by techniques which permitted us to deduce the contributions of the algorithmic and non-algorithmic components to the overall MTF. NEQ values have been calculated for a number of CT scanners.

Humans↗

PubMed1981

The effect of mAs variation upon computed tomography image quality as evaluated by in vivo and in vitro studies.

The effect of different mAs settings on computed tomobraphy (CT) image quality was evaluated by a clinical study and phantom studies. In the clinical portion of this study, a number of CT images, obtained at various mAs settings, were reviewed by experienced CT interpreters. From these same images, graphs were charted of the root-mean-standard deviation (RMSD) vs. body size; there appeared to be a linear relationship between noise, as measured by RMSD, and body size. A performance phantom was used to evaluate the effect of the different mAs settings on resolution. There was some loss in low contrast resolution at 6 and 20 mAs; however, the resolution was identical at 40 and 100 mAs.

Humans↗

PubMedDate not supplied

Assessment of the diabetic foot using spiral computed tomography imaging and plantar pressure measurements: a technical report.

Persons with diabetes mellitus (DM) and peripheral neuropathy are at high risk for skin breakdown due to unnoticed excessive pressures to the plantar foot during walking. We developed methods that combined spiral x-ray computed tomography (SXCT) imaging and plantar pressure analysis to quantify internal foot structure and external pressure during plantar loading. Methods were tested using a subject with DM who had a plantar ulcer, and a healthy control. SXCT measurements were within 2 mm of truth and SXCT plantar recordings were within 6.5% of walking trials. Hammer toe deformity (second toe), severe atrophy of the intrinsic muscles and less contact area during plantar loading, and a peak plantar pressure three times greater at the site of the ulcer were measured in the diabetic foot as compared with the healthy control. This preliminary investigation suggests that these methods are accurate for structural and pressure measurements of diabetic and healthy feet.

Adult↗