9,649 research outputs found
Usefulness of (Ti)-T-201 Spect/Ct Relative to F-18-Fdg Pet/Ct in Detecting Recurrent Skull Base Nasopharyngeal Carcinoma
No full textBackground. This study was designed to compare (TI)-T-201 single photon emission computed tomography (SPECT)/CT with 18-fluoro-2-deoxyglucose (F- 18-FDG) PET/CT in diagnosing recurrent skull base nasopharyngeal carcinoma (NPC). Methods . Twenty-seven patients were recruited. Both (TI)-T-201 SPECT/CT and F-18-FDG PET/CT for each patient were performed at least 4 months later after initial therapy. Results. The sensitivity and specificity for (TI)-T-201 SPECT/CT were 66 .7% and 100%, and those for F- 18-FDG PET/CT were 86.7% and 75.0%. Lesion/background ratios were obtained for the 10 lesions that were both SPECT and PET true positive. For the 8 patients with recurrences in nasopharyngeal regions, PET lesion/background ratios were all higher than SPECT lesion/ background ratios. For the 2 patients with intracranial metastases, SPECT lesion/background ratios were higher than PET lesion/background ratios. Conclusion. (TI)-T-201 SPECT/ CT is as effective as F-18-FDG PET/CT in detecting recurrent NPC. For intracranal recurrence, (TI)-T-201 SPECT, because of its high intracranial lesion/background ratio, is probably better than F-18-FDG PET
Application of CT in Diagnosing Carcinoma of the Maxillary Sinuses : PART 2: An Experimental Study of Pitfalls Encountered when Diagnosing Carcinoma of the Maxillary Sinuses with CT
Full text link1982-03A phantom simulating the transverse section of the maxillary sinuses was constructed for experimentation with various CT scanners to study the following: (1) the occasional inability to image the very thin posterior-lateral walls which have no real bone defects, and (2) to verify whether or not the bony walls surrounding the maxillary sinuses are actually as thick as they appear on CT. The phantom was made of an acrylic cylinder containing three cavities simulating the maxillary sinuses and the nasal cavity and filled with water. The walls, made of thin aluminum and acrylic plates and placed between water and air, disappeared in some CT images. The thickness of the walls calculated from CT values was greater than the true thickness imaged by each CT scanner. The author stresses that in CT images, either experimentally or clinically, thin bony walls placed between water and air or fat tend to disappear, and that bony walls tend to appear thicker than their true thickenss.departmental bulletin pape
Efficacy and safety of CT-guided percutaneous pulsed radiofrequency treatment of the Gasserian ganglion in patients with medically intractable idiopathic trigeminal neuralgia
No full textMeng Lan, Jia Zipu, Shen Ying, Ren Hao, Luo Fang Department of Anesthesiology and Pain Management, Beijing Tiantan Hospital, Capital Medical University, Beijing, PR China Background: There is a lack of prospective studies for the long-term results of percutaneous pulsed radiofrequency (PRF) of the Gasserian ganglion in the treatment of patients with medically refractory trigeminal neuralgia (TN).Methods and results: We prospectively observed the outcomes of 28 idiopathic TN patients (between July 2013 and July 2016) who received CT-guided percutaneous PRF treatment of the Gasserian ganglion. All of the patients had stopped responding to drug therapy before PRF treatment. The effective treatment standard was a reduction in the pain numeric rating scale (NRS) by ≥50% after the procedure. The postoperative NRS score decreased gradually from preoperative 7.6±0.8 months to 1.5±2.4, 0.2±0.4, 0.2±0.4, 0.1±0.4, and 0.1±0.4 at 1, 3, and 6 months and 1 and 2 years after the PRF treatment. The response rates at 1, 3, and 6 months were 85.7%, and the rates at 12 months and 2 years were maintained at 78.6%. No serious side effects were observed.Conclusion: CT-guided PRF invention is an effective and safe technique for medically intractable idiopathic TN patients. This minimally invasive alternative treatment has the potential as a first-line therapy for TN. Keywords: trigeminal neuralgia, pulsed radiofrequency, efficacy, safet
Damage characterizations and simulation of selective laser melting fabricated 3D re-entrant lattices based on in-situ CT testing and geometric reconstruction
No full textIn recent years, metal additive manufacturing (AM) are widely employed for industrial applications, such as: biomedical, aerospace, automotive, marine and offshore sections. AM demonstrated superior manufacturing efficiencies and economic advantages for advanced lightweight industrial components with unlimited arbitrary topological layouts and complex internal microstructures, and are also employed for fabrication of auxetic materials and structures. In this paper, damage characterizations and mechanical behaviors of selective laser melting (SLM) fabricated 3D re-entrant lattices are investigated based on in-situ interrupted micro-CT test, and simulation based on geometric reconstructed models are performed for exploring the underlying failure mechanisms. Firstly, theoretical models for predicting the mechanical properties of 3D re-entrant lattice are developed, such as stiffness, Poisson's ratio and strength, etc. Secondly, the geometrical errors and fabrication defects of 3D reentrant lattices are analyzed based on 3D micro-CT scanning, in-situ micro-CT interrupted compression tests are performed for studying the deformation process and failure mechanisms. Finally, image finite element models with the detailed information of the shape, position and distribution of defects of the 3D reentrant lattices are constructed from 3D tomographic images, and numerical simulations are performed for studying the effects of the defects on the mechanical performances of the SLM additive manufactured 3D re-entrant lattice structures. It is shown that the failure behavior of the reentrant lattice is governed not only by its topology, but also by the geometric defects and surface defects. Moreover, the proposed interrupted in-situ micro-CT mechanical loading experiments and image finite element approaches can also shed lights on the relations between fracture failure around the edge and the powder adhesion. The damage evolution process is compared with the numerical simulation results to verify the materials failure modes
131i-6beta-Iodomethyl-19-Norcholesterol Spect/Ct for Primary Aldosteronism Patients with Inconclusive Adrenal Venous Sampling and Ct Results
No full textThe 2 main causes of primary aldosteronism (PA) are aldosterone-producing adenoma (APA) and idiopathic adrenal hyperplasia (IAH). Dexamethasone- suppression (131)I-6beta- iodomethyl-19-norcholesterol (NP-59) adrenal scintigraphy can assess the functioning of the adrenal cortex. This study evaluated the diagnostic usefulness of NP-59 SPECT/CT in differentiating APA from IAH and in predicting postadrenalectomy clinical outcome for PA patients who had inconclusive adrenal venous sampling (AVS) and CT results . METHODS: We retrospectively reviewed the 31 adrenal lesions of 27 patients (age range, 33-71 y; mean age +/- SD, 50.4 +/ - 10.9 y) who had been clinically confirmed (by saline infusion and captopril tests) to have PA, had inconclusive CT and AVS test results, and had undergone NP-59 imaging before adrenalectomy. The accuracy of NP-59 imaging was determined by comparison with histopathologic findings. RESULTS: NP-59 SPECT/CT gave us 18 true-positive, 3 false- positive, 6 true-negative, and 4 false- negative results. Compared with planar imaging, SPECT/CT significantly improved diagnostic accuracy and prognostic predicting ability (P = 0.0390 and P = 0.0141, respectively). The NP-59 results were negative for 7 of the 23 patients with unilateral adrenal lesions, and none of these 7 patients had shown postsurgical clinical improvement. CONCLUSION: NP-59 SPECT/CT is an effective imaging tool for differentiating APA from IAH in PA patients whose CT and AVS results are inconclusive. Our results suggest that patients with presurgically negative NP-59 results should be treated medically and that noninvasive NP-59 SPECT/CT may be suited for use as the first lateralization modality after CT in patients with clinically confirmed PA
An approach to increasing the resolution of industrial CT images based on an aperture collimator
No full textThe spatial resolution of CT images is dominated by the focal spot size when it is large relative to the detector cells. We propose an approach to increase the spatial resolution by utilizing an aperture collimator. The aperture collimator is specially designed and placed in front of the X-ray source so that the rays penetrating the collimator form a set of narrow fan beams. Then an iterative algorithm is introduced to reconstruct CT images from the data obtained by scanning the narrow fan beams. Numerical experiments show that the proposed approach could significantly increase the resolution of the CT images. Furthermore, this approach is also robust against some challenging cases, such as the examination of low contrast object, reconstruction based on multi-energy data and perturbation of geometric errors in CT systems. (C) 2013 Optical Society of AmericaOpticsSCI(E)EI1ARTICLE2327946-279632
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