Search results for "TOMOGRAPHY"

A rare case of acute idiopathic colocolic intussusception in an adult patient

2020

Abstract Adult intussusception is a rare condition that is frequently associated with malignancy and requires surgical approach. Symptoms are often non-specific and of subacute or chronic character. Therefore, computerized tomography (CT) scan is the most commonly used modality for identifying adult intussusception. A 51-year-old female presented with a 1-day history of increasing abdominal pain. Abdominal ultrasound and CT scan revealed intussusception. Intra-operatively, colocolic intussusception was present and laparoscopically reduced. A lead point was found neither intra-operatively nor in post-operative ileocolonoscopy and resection of involved bowel segments was not necessary.

Abel transforms with low regularity with applications to X-ray tomography on spherically symmetric manifolds

2017

We study ray transforms on spherically symmetric manifolds with a piecewise $C^{1,1}$ metric. Assuming the Herglotz condition, the X-ray transform is injective on the space of $L^2$ functions on such manifolds. We also prove injectivity results for broken ray transforms (with and without periodicity) on such manifolds with a $C^{1,1}$ metric. To make these problems tractable in low regularity, we introduce and study a class of generalized Abel transforms and study their properties. This low regularity setting is relevant for geophysical applications.

Odontogenic abscess complicated by descending necrotizing mediastinitis: evidence of medical and dental malpractice

2016

Non-destructive automatic determination of aspect ratio and cross-sectional properties of fibres

2015

A novel method for computerised estimation of the aspect ratio distribution and various cross-sectional geometrical properties of fibres in short-fibre reinforced composites is proposed. The method, based on X-ray micro-computed tomography, is non-destructive and does not require user intervention. Based on results on specially fabricated model material, the accuracy and precision of the method seems adequate. The method is applied in analysing a manufacturing process of wood fibre reinforced thermoplastic composite. The results indicate a significant decrease of the aspect ratio of fibres during the processing steps. Finally, the feasibility of the method is assessed by estimating paramete…

The Bi sulfates from the Alfenza Mine, Crodo, Italy: An automatic electron diffraction tomography (ADT) study

2014

We report about three bismuth sulfates from mineralized quartz dikes from Alfenza (Crodo, Italy), two new phases and a rare mineral, cannonite, all growing on bismuthinite. The first new phase occurs as white, "hortensia-like" aggregates of pseudo-hexagonal platelets, with perfect basal cleavage, similar to 20 mu m wide and few micrometers thick. The approximate composition is Bi2O2(SO4), and cell parameters and symmetry, as determined by automatic diffraction tomography, are a = 22.0(4), b = 16.7(3), c = 15.9(3) angstrom, beta = 102.9(5)degrees, space group Pc or P2/c. A major stacking disorder is detected by HR-SEM images and electron diffraction data.The second new phase was detected onl…

253. An accurate and operator independent method for biological tumour volume segmentation

2018

Purpose The aim of this paper is to develop an operator independent method for biological tumour volume (BTV) delineation from Positron Emission Tomography (PET) images. BTV delineation is challenging because of the low spatial resolution and high noise level in PET images. In addition, BTV varies substantially depending on the method used to segment. Manual delineation is widely-used, but it is strongly user dependent. Methods The proposed method starts with the automatic identification of the PET slice with maximum Standardized Uptake Value (SUV). Then, a user- independent mask is obtained by a rough pre-segmentation step and it is used to perform the local active contour segmentation on …

Cardiac Computed Tomography Angiography Follow-Up of Resorbable Magnesium Scaffolds.

2021

Abstract Introduction An ancillary advantage of bioresorbable scaffolds is the possibility of non-invasive imaging assessment of the treated coronary segment. Cardiac computed tomography angiography (CCTA) studies of resorbable magnesium scaffolds (RMS) are scarce. Methods In this collaborative, international study, nine patients who had an RMS implanted underwent CCTA as part of follow-up assessment. Core-lab blinded quantitative and qualitative assessment was performed by an independent CCTA investigator. Results Eight studies were amenable for quantitative analysis, and the blinded CT investigator successfully located and evaluated patency of RMS in all cases. The CCTA follow-up in-scaff…

Virtual reality system for planning minimally invasive neurosurgery

2008

Object The authors report on their experience with a 3D virtual reality system for planning minimally invasive neurosurgical procedures. Methods Between October 2002 and April 2006, the authors used the Dextroscope (Volume Interactions, Ltd.) to plan neurosurgical procedures in 106 patients, including 100 with intracranial and 6 with spinal lesions. The planning was performed 1 to 3 days preoperatively, and in 12 cases, 3D prints of the planning procedure were taken into the operating room. A questionnaire was completed by the neurosurgeon after the planning procedure. Results After a short period of acclimatization, the system proved easy to operate and is currently used routinely for pre…

Contribution of thallium-201-SPECT to the grading of tumorous alterations of the brain

1992

Single photon emission computed tomography (SPECT) with thallium-201-chloride (201Tl) was used in 22 patients to assess the grade of malignancy of brain tumors. Low- and high-grade malignant gliomas could be well differentiated by calculating the Grade Index (GI), i.e., 201Tl uptake in the tumor area relative to a contralateral brain region. Low-grade gliomas (WHO-grade I-II) usually showed a GI of1.5. Tumors classified histologically as high-grade malignant (WHO-grade III-IV) had GI values greater than 1.42 and a mean value of 1.89. Until labelled amino-acid tracers for gamma-cameras become commercially available, thallium-201 brain-SPECT can provide an independent and complementary method…

CT and MR Imaging Evaluation of Hepatic Adenoma

2006

Hepatic adenoma is a rare benign epithelial tumor that is usually encountered in young women who use oral contraceptives. It is clinically significant because of the risk of hemorrhage and of its low-grade malignancy potential. Adenomas usually are mildly hypervascular at contrast-enhanced CT and MR imaging, and heterogeneous due to the presence of hemorrhage, necrosis, calcifications and fat. The objective of our study was to illustrate the CT and MR imaging findings of hepatic adenoma.