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At least 217 records · Page 12Linked to original sources
PubMed2007

Low tube voltage improves computed tomography imaging of delayed myocardial contrast enhancement in an experimental acute myocardial infarction model.

OBJECTIVE: We sought to evaluate the influence of tube voltage on the visualization of acute myocardial infarction (MI) in cardiac multislice spiral computed tomography (MSCT). MATERIALS AND METHODS: Acute MI was induced in 12 domestic pigs by a 45-minute balloon occlusion of the left anterior descending artery. Delayed enhancement magnetic resonance imaging was performed 15 minutes after the injection of 0.2 mmol/kg Gd-DTPA. On the same day, retrospectively ECG-gated MSCT was performed at 120, 100, and 80 kV (16x0.75mm, 550mAseff.) 15 minutes after the injection of 140 mL of iopromide (1 g/iodine/kg). The pigs were killed and the hearts were excised and stained with 2,3,5-triphenyltetrazolium chloride. The area of acute MI, contrast-to-noise ratio (CNR), and percent signal difference were compared among the different imaging techniques by applying Bland-Altman plots and 2-way analysis of variance. RESULTS: On MSCT at 120, 100, and 80 kV, the respective mean acute MI sizes were 18.4+/-11.4%, 19.3+/-11.5%, and 20.5+/-11.6%. The mean MI sizes were 20.8+/-12.2% and 20.1+/-12.4% on magnetic resonance imaging and 2,3,5-triphenyltetrazolium chloride staining. Analysis of variance did not show any statistically significant differences between the different techniques with respect to the size of acute MI (P=0.9880). Comparing the different kV settings on MSCT, the highest percent signal difference (74.7+/-12.1%) and the highest CNR (6.7+/-1.8) between infarcted and healthy remote myocardium were achieved at 80 kV. CONCLUSIONS: When compared with routine scan protocols, low tube voltage MSCT allows for the assessment of the MI size with an improved CNR and contrast resolution. This technique appears to be advantageous for assessing myocardial viability from contrast enhanced late-phase MSCT.

Animals↗
PubMed1998

Successful minimally invasive surgery in primary hyperparathyroidism after combined preoperative ultrasound and computed tomography imaging.

The hypothesis that due to the high prevalence of solitary adenoma and the accuracy of modern imaging techniques it should be possible to cure a considerable number of patients by direct adenomectomy through a minimally invasive approach was tested in a consecutive series of 66 patients with primary hyperparathyroidism. Preoperative parathyroid imaging consisted of a combination of (Doppler) ultrasound and spiral computed tomography with cine-loop reconstruction potentiality. If only one parathyroid adenoma was identified preoperatively, a minimally invasive approach was advised. If more than one adenoma was located, or when the imaging results were equivocal, the patient was advised to undergo a conventional bilateral neck exploration. Sixty-six patients (54 female, 12 male) with a median age of 60 years and a median serum calcium of 2.90 mmol L(-1) were studied. Fifty-one of these patients underwent minimally invasive surgery, which was successful in 49 patients, while conversion to conventional neck exploration was necessary in two patients. Conventional neck exploration was chosen for the other 15 patients. Six of these proved to have multiglandular disease or a retro-sternal adenoma, while in nine patients only one parathyroid adenoma was found. All patients became normocalcaemic postoperatively. Morbidity consisted of a transient unilateral vocal cord paralysis in one patient. These results support the original hypothesis: successful minimally invasive surgery was possible in 74% (49 of 66) of patients, thus avoiding conventional neck exploration. This strategy further simplifies the operative treatment of primary hyperparathyroidism without loss of efficiency.

Female↗
PubMed1998

Medial canthus single-injection episcleral (sub-tenon anesthesia): computed tomography imaging.

UNLABELLED: Single-injection medial canthus periocular anesthesia is a promising regional anesthesia technique for ophthalmic surgery. The purpose of this computed tomography (CT) study was to confirm that this technique is an episcleral injection and to explain why it provides a good akinesia of the globe. Four fresh nonpreserved cadavers (eight eyes) were injected with fractioned various volumes of a contrast media using a previously described technique. For each injection and each eye, CT scans were performed in three planes of the space, and the site and spread of the injection was observed. We confirm that single-injection medial canthus periocular anesthesia is, in fact, an episcleral anesthesia, which explains the good sensory block of the globe. When larger volumes are injected, the contrast media spreads to the lids and extraocular muscle sheaths. We believe that this may explain why this technique provides good sensory and motor block of the globe and eyelids. This technique is a promising alternative to both retro- and peribulbar anesthesia. IMPLICATIONS: We describe medial canthus single-injection periocular anesthesia by a computed tomography injection study in eight human cadaver eyes. It was confirmed to be an episcleral injection. Akinesia of the eyeball is provided by spreading of the local anesthetic solution from the episcleral space to the rectus muscle sheaths.

Anesthesia, Conduction↗
PubMed2002

Estimation of distal radius failure load with micro-finite element analysis models based on three-dimensional peripheral quantitative computed tomography images.

There is increasing evidence that, in addition to bone mass, bone microarchitecture and its mechanical load distribution are important factors for the determination of bone strength. Recently, it has been shown that new high-resolution imaging techniques in combination with new modeling algorithms based on the finite element (FE) method can account for these additional factors. Such models thus could provide more relevant information for the estimation of bone failure load. The purpose of the present study was to determine whether results of whole-bone micro-FE (microFE) analyses with models based on three-dimensional peripheral quantitative computer tomography (3D-pQCT) images (isotropic voxel resolution of 165 microm) could predict the failure load of the human radius more accurately than results with dual-energy X-ray absorptiometry (DXA) or bone morphology measurements. For this purpose, microFE models were created using 54 embalmed cadaver arms. It was assumed that bone failure would be initiated if a certain percentage of the bone tissue (varied from 1% to 7%) would be strained beyond the tissue yield strain. The external force that produced this tissue strain was calculated from the FE analyses. These predictions were correlated with results of real compression testing on the same cadaver arms. The results of these compression tests were also correlated with results of DXA and structural measurements of these arms. The compression tests produced Colles-type fractures in the distal 4 cm of the radius. The predicted failure loads calculated from the FE analysis agreed well with those measured in the experiments (R(2) = 0.75 p < 0.001). Lower correlations were found with bone mass (R(2) = 0.48, p < 0.001) and bone structural parameters (R(2) = 0.57 p < 0.001). We conclude that application of the techniques investigated here can lead to a better prediction of the bone failure load for bone in vivo than is possible from DXA measurements, structural parameters, or a combination thereof.

Aged↗
PubMed2005

Intraperitoneal administration of an iodine-based contrast agent to improve abdominal micro-computed tomography imaging in mice.

The purpose of this study was to estimate the optimal volume of an iodine-based contrast agent to administer to mice via intraperitoneal injection and the optimal time after injection to perform micro-computed tomography for maximal enhancement of abdominal organs. Eight mice were paired randomly; three pairs underwent imaging after receiving intraperitoneal injections of 125, 250, or 500 microl of contrast agent, and the fourth pair underwent imaging without receiving an injection. Each mouse was scanned three consecutive times, and each scan lasted 25 min so that we could observe the clearance of the contrast agent from the abdomen. We determined that introducing 250 microl of contrast agent into the abdominal cavity of the mice and then having the mice undergo micro-computed tomography 15 min after injection provided the optimal degree of contrast enhancement needed to distinguish the abdominal organs. These results may lead to expanded use of this imaging modality to assess abdominal organ margins in small-animal studies in vivo.

Animals↗
PubMed1993

A new method for computed tomography image compression using adjacent slice data.

RATIONALE AND OBJECTIVES: The authors developed and subjectively evaluated an interslice compression algorithm that explores the redundancy among adjacent slices of an x-ray computed tomography (CT) scan. This algorithm has been compared to an intraslice compression algorithm based on the two-dimensional discrete cosine transform. METHODS: Nine x-ray CT head images from three patients were compressed with this interslice method at compression ratios of 5:1, 10:1, and 15:1. The same images were also compressed with the intraslice method at the same ratios. Six radiologists judged quality of randomly selected compressed and decompressed images compared to that of the originals. The evaluation data were analyzed statistically with the analysis of variance and Tukey's multiple comparison. Kappa-like statistics (Williams index and O'Connell and Dobson indexes) were also calculated to measure the agreement among readers beyond the amount expected by chance. RESULTS: The interslice coding algorithm showed significantly better quality than the intraslice method at significance level 0.05, even though there was no difference in the objective distortion measure (signal-to-noise ratio). Also, the quality of 10:1 compressed images with the interslice coding algorithm was not significantly different from that of the originals at level 0.05. While large variations in agreement occurred among readers, the overall agreement was statistically significant. CONCLUSIONS: By using adjacent slice information in compressing x-ray CT images, significantly better quality in compressed and decompressed images was achieved. While 10:1 compressed images with the interslice algorithm were not significantly different from the originals in quality at level 0.05, effect on diagnostic accuracy remains to be investigated.

Algorithms↗
PubMed2006

Multidetector-row computed tomography imaging of splenic trauma.

The spleen is the intra-abdominal organ most often injured as a result of blunt trauma. Multidetector-row computed tomography (MDCT) plays an important role in the detection and characterization of splenic injury. It has been shown to be highly accurate and can detect splenic vascular lesions, the presence of which has been shown to be a predictor of failure of nonoperative management. The increased use of angiography and splenic artery embolization in the management of such injuries has led to improved success rates with nonoperative management. This article reviews the various appearances of the injured spleen and discusses the use of MDCT in the initial evaluation of injury. The indications for angiography and embolization are reviewed, with examples of appearances of the postembolization spleen.

Angiography↗
PubMed2005

Serial high-resolution computed tomography imaging in patients with Wegener granulomatosis: differentiation between active inflammatory and chronic fibrotic lesions.

PURPOSE: To evaluate pulmonary pathologies in Wegener granulomatosis with sequential computed tomography (CT) in order to differentiate active inflammatory lesions from chronic fibrotic lesions. MATERIAL AND METHODS: Serial CT findings in 38 patients with Wegener granulomatosis were retrospectively analyzed (mean follow-up period, 21 months). The presence, extension, and distribution of the following findings were evaluated with CT: parenchymal nodules, masses, ground-glass attenuation, airspace consolidation, bronchial wall-thickening, bronchiectasis, linear areas of attenuation, pleural irregularities, pleural effusions, hilar and mediastinal lymphadenopathy. RESULTS: Observed in 92% of patients, nodules were the most common CT pathology. Areas of ground-glass attenuation, consolidation, masses of linear attenuation, and tracheal/bronchial wall-thickening were detected in 24%, 26%, 32%, 39%, and 68% of patients. At follow-up, the clearance of lesions was most consistent for areas of ground-glass attenuation (89%), masses (87%), and cavitated nodules (85%). In the follow-up scan, 58% of all nodules, 47% of pulmonary consolidations, and 66% of bronchial wall-thickening were completely resolved. Areas of bronchiectasis and septal/non-septal lines remained stable in 70% and 71% of patients. CONCLUSION: The majority of the lesions decreased or resolved completely with or without areas of linear attenuation. Ground-glass attenuation, cavitated nodules and masses appear to represent active inflammatory lesions. In most probability, areas of bronchiectasis and septal/non-septal lines more often represent chronic fibrotic changes rather than active inflammatory changes. In combination with clinical evaluation and bronchoscopy, CT assists in the assessment of disease activity.

Adult↗
PubMed2006

Role of computed tomography imaging in predicting response of nasopharyngeal carcinoma to definitive radiation therapy.

PURPOSE: The purpose of this study was to investigate the role of posttreatment computed tomography (CT) scans in assessing response of nasopharyngeal carcinoma (NPC) to definitive radiotherapy. MATERIAL AND METHODS: Between March 1999 and October 2003, a total of 132 consecutive patients with newly diagnosed NPC were studied. Sixty-one patients with AJCC stage I or II NPC were treated with radiation only; 71 patients with stage III or IV disease but no evidence of distant metastasis were treated with concurrent chemoradiotherapy. All patients received CT scans of the head and neck, nasopharyngoscopy, and biopsies of primary sites at 4 to 6 months after completion of radiotherapy. Clinical response of the primary tumor as determined by comparison of pre- and posttreatment CT scans was correlated to pathology results. RESULTS: The median follow-up time for all patients was 25 months (range, 9-40 months). Radiologic progression was seen in five patients, stable disease in 18 patients, and radiographic partial (rPR) and complete responses (rCR) were seen in 67 and 42 patients, respectively, at 4 to 6 months of follow up. Biopsies of the nasopharynx were positive in six patients. For patients with rCR, two patients (4.8%) had positive biopsies. Four patients with residual disease (rPR, stable, or progressive disease) after treatment had positive biopsies. The positive and negative predictive values, sensitivity, and specificity of CT scans in evaluating the NPC response to radiotherapy were 0.04, 0.95, 0.67, and 0.32, respectively. CONCLUSIONS: Pathologic CR for nasopharyngeal carcinoma is usually evident at 4 to 6 months after definitive radiotherapy; however, there is no correlation between pathologic and radiographic response. Although longer follow up is required to define the relationship between radiographic and pathologic responses with respect to disease control, we find CT scan at 4 to 6 months after radiotherapy to be neither sensitive nor specific in predicting the response of primary NPC to radiotherapy.

Adult↗
PubMed1985

Clinical evaluation of computed tomography images in esophageal cancer after submucosal injection of iodized oil.

A submucosal injection of iodized oil (Lipiodol) was administered to patients with esophageal cancer and computed tomography scanning was performed. Infiltration to the surrounding organs, especially the aorta, vertebra, trachea, bronchi, heart, and lymph nodes was examined and the results compared with those from plain computed tomography. Compared with plain computed tomography findings, invasion to the submucosa, adventitia, and surrounding organs was much more clearly demonstrated. This method accurately delineated the oral side of mucosal lesions, which could be useful in establishing a plan for radiotherapy.

Aged↗
PubMedDate not supplied

Correction of scatter in computed tomography images of bone.

A cylindrical aluminum/Plexiglas phantom representing trabecular bone surrounded by various amounts of cortical bone was constructed. Measurements of this phantom using a computed tomography scanner with a 125I photon source demonstrated errors of 0% to 28% in the density of trabecular bone. Two contributing factors are identified: scatter and exponential edge-gradient effect. A simple first-order correction is developed to correct for the scatter-induced error. Relative to the exponential edge-gradient effect, which contributes up to 3.4% error over the range of cortical thicknesses measured, the correction procedure reduces the scatter-induced error to a level of -0.66% to +0.61%. The consistency of the optimized correction parameters with the physical model as well as the effect of scatter measured by the same phantom on a GE 8800 scanner are shown.

Bone and Bones↗
PubMed2006

Computed tomography imaging of vena cava filter complications: a pictorial review.

Caval filters are widely used in the prevention of pulmonary embolism. Filters have proved to be effective, but the complication rate is not negligible. Computed tomography (CT) provides a complete evaluation of the filter, including both caval and extracaval complications. In this review, we describe the normal CT aspect of cava filters, the classification of complications and their CT findings. Technical considerations for adequate CT imaging are also highlighted.

Humans↗
PubMed2004

Analysis of cerebral infarction pattern in computed tomography images of patients with internal carotid artery stenosis.

RATIONALE AND OBJECTIVES: An unbiased and quantitative analysis of lesion patterns in patient groups is described and applied to the analysis of infarction patterns. MATERIALS AND METHODS: One hundred forty-two computed tomographic images of patients with ischemic stroke were registered to an average computed tomographic brain image, which was used as template. Lesions were segmented manually and averaged per category of internal carotid artery (ICA) stenosis. Thus, patterns of lesion distribution were formed. Differences then were analyzed using nonparametric statistics. This analysis was compared with the traditional classification of lesions. RESULTS: The nonparametric analysis showed an increased involvement of the territory of the middle cerebral artery in infarctions in patients with ICA occlusion compared with patients with mild or severe ICA stenosis. These differences did not show when classification of infarctions was used. CONCLUSIONS: The presented method is more sensitive to differences in lesion patterns than traditional lesion classification and showed a different infarction pattern for ICA occlusion.

Aged↗
PubMed1992

Technetium-99m HM-PAO single photon emission computed tomography imaging in transient global amnesia.

Five right-handed patients with pure transient global amnesia were evaluated with technetium-99m hexamethylpropyleneamine oxime single photon emission computed tomography after the amnesic attack. Independent of the interval between the procedure and the amnesic episode, single photon emission computed tomography demonstrated a decreased cerebral blood flow in the left temporal lobe in one patient and in the left parietotemporal region in three patients, with a more marked reduction in the temporal lobe. The remaining three patients were normal. A control single photon emission computed tomographic study was carried out in one patient 3 months after the amnesic attack and showed a left-sided persistent temporal hypoperfusion. These findings suggest that in some patients, transient global amnesia can be due to a vascular mechanism requiring strong investigations for vascular risk factors and appropriate treatment. During a follow-up period of 12 to 32 months, none of the patients with regional hypoperfusion suffered cerebrovascular events, suggesting that single photon emission computed tomography has no predictive value for further stroke.

Aged↗