Classical Computed Tomography Research Articles

Predictive Value of Quantitative Parameters of 18F-FDG PET/CT in Patients with Liposarcoma.

The purpose of this study was to evaluate the predictive features of baseline F-18-fluorodeoxy-D-glucose positron emission tomography (18F-FDG PET)/computed tomography (CT) parameters in patients with dedifferentiated liposarcomas (DDLPSs) and well-differentiated liposarcomas (WDLPSs) receiving systemic treatment. A total of 24 patients with liposarcoma who underwent longitudinal 18F-FDG PET/CT in systemic therapy were included. All volumetric segmentation of each tumor section and semiquantitative imaging parameters were extracted from the axial field of view from both PET and CT images. Maximum, mean, and minimum standardized uptake values (SUVmax, SUVmean, and SUVmin), Hounsfield units (HUs), and their respective changes from baseline and posttreatment were calculated. The voxel values from unenhanced CT images were correlated with PET-derived parameters. The 18F-FDG uptake decreased by more than 56% on average in responders for both SUVmax and SUVmean in DDLPS. There was a decrease in HUmax in DDLPS among responders. Using AUC > 0.8 as a reasonable predictor, we found that the ratios of SUVmaxD/HUmean, SUVmaxD/HUmedian, and SUVmeanD/HUmedian at baseline were significant indicators of the response to treatment in patients with liposarcoma. The changes in SUVmean and not just SUVmax parameters could be considered as accurate tumor response indicators. For the first time, we introduced baseline SUV/HU ratios as a valuable diagnostic tool in predicting liposarcoma treatment outcomes. This ability was not revealed by classic semiquantitative PET or CT parameters at baseline.

Novel FBP based sparse-view CT reconstruction scheme using self-shaping spatial filter based morphological operations and scaled reprojections

Computed tomography (CT) has been a major contributor in revolutionizing and commercializing the medical imaging industry. However, most of the commonly used CT reconstruction algorithms need sufficiently dense angular sampling views or a substantial dose of hazardous X-ray radiations. Reducing the radiation dose causes degradation in the quality of the reconstructed image, due to additional artifacts. The paper presents a novel algorithm for efficient CT reconstruction from under-sampled projections; which leads to radiation dose reduction with quality image reconstruction. The Sparse-View projection data is enhanced using a series of post-processing algorithms and computer based reprojection. The process involves enhancement through self-shaping/amoeba based morphological spatial filtering. The use of self-shaping spatial filter kernel in the area of under-sampled CT reconstruction is a novel contribution. The scheme is supported by computer simulations using fan-beam projections of clinically reconstructed and simulated head CT phantoms. The proposed scheme is compared with classical reconstruction techniques for reconstruction image quality, accuracy, speed, and robustness in the presence of noise. Promising results indicate the efficacy of proposed scheme. An efficient scheme for image enhancement of Sparse-View CT is presented. The results demonstrate that the proposed scheme is visually and statistically better than classical CT reconstruction techniques, as evaluated using various image quality matrices. The presented scheme is more robust to noise in CT projections and effective for enhancing few-views reconstruction.

ProMeSCT: A Proximal Metric Algorithm for Spectral CT

The acquisition of a set of spectral photon-counting computed tomography (spectral PC-CT) measurements aims at uncovering both the spatial and energetic characteristics of the imaged body, which widens the potential of tomography compared to classical computed tomography (CT). In the preclinical context, the use of polychromatic beams induces spectral mixing and, as a consequence, the reconstruction procedure requires specific algorithmic tools more complex than the standard ones used in CT. In this article, we propose a one-step inversion method to simultaneously separate and reconstruct the physical materials of an object observed in the context of spectral PC-CT. To do so, we carefully consider the underlying polychromatic model of the X-ray beam and combine it with a priori on the materials of the object to reconstruct. The simultaneous separation and reconstruction of materials is done by minimizing the resulting nonconvex ill-posed inverse problem. The dimensionality of the data and object materials worsens the computational complexity of the problem. We propose an efficient optimization algorithm based on a proximal forward-backward algorithm that is accelerated by a metric, which is specifically designed for spectral PC-CT. The efficiency of our method called ProMeSCT is demonstrated on results obtained on 3-D synthetic data with a simple regularization that encompasses the positivity of the quantities of interest.

Unusual Neuroimaging in a Case of Rapidly Progressive Juvenile-Onset Krabbe Disease

Krabbe disease is a progressive neurologic disorder caused by deficiency of the lysosomal enzyme galactocerebrosidase. The disease commonly has an early-infantile onset, but can have late-infantile, juvenile, or adult-onset phenotypes. Classic computed tomography (CT) and magnetic resonance imaging (MRI) findings in Krabbe have been well described. We report a patient, ultimately diagnosed with juvenile-onset Krabbe, who presented with atypical CT imaging and rapid disease progression. Our patient was a previously healthy and developmentally appropriate female who presented at 3 years 4 months of age with ataxia and motor regression that had progressed over the course of 6 weeks without an identifiable catalyst. CT, performed in the emergency setting, demonstrated extensive white matter hyperdensity. Subsequent MRI showed T2 hyperintensity of the white matter corresponding to the areas of hyperdensity on the CT, as well as enhancement of multiple cranial nerves bilaterally, suggestive of Krabbe disease. Enzymatic testing demonstrated low galactocerebrosidase activity and molecular testing of GALC revealed compound heterozygosity for 2 known pathogenic mutations, consistent with a diagnosis of Krabbe Disease. This included the common 30-kb deletion and a known pathogenic mutation associated with juvenile/adult-onset disease. Our patient's diffuse hyperdensity on CT offers a new radiographic finding to include in the repertoire of Krabbe imaging, and thus aide in the diagnostic evaluation. The rapidity of progression our patient demonstrated is additionally unique and should be considered in the identification of juvenile Krabbe as well as the complicated decision-making process regarding potential treatments.

Research progress on amyopathic dermatomyositis associated with interstitial lung disease.

Research progress on amyopathic dermatomyositis associated with interstitial lung disease.

Evaluation of interleukin-6 and its association with the severity of disease in COVID-19 patients

Background: The present study was undertaken to determine the levels of interleukin-6 (IL-6) and evaluate its association with clinical presentation, severity, radiological imaging, management, and outcome in coronavirus disease (COVID-19) infection. Methods: The present study included 132 admitted COVID-19 patients, categorized into three groups. Group 1 had IL-6 within the normal reference range, Group 2 had IL-6 raised up to ten times the upper normal limit (UNL), and Group 3 had IL-6 level raised > ten times the UNL. The patient's data concerning medical history, clinical manifestations, laboratory findings, radiological imaging, management, and outcome were extracted from their medical records for subsequent evaluation, interpretation, and association among the groups. Results: COVID-19 patients with raised IL-6 levels exhibited frequent symptomatic presentations, severity, and critical illness, especially with extremely high IL-6 levels (P < 0.001). Radiological findings in terms of a digital chest radiograph and high-resolution computed tomography (CT) chest indicated severe lung involvement in patients with extremely high IL-6 levels (P < 0.05). The majority of patients with extremely raised IL-6 levels were associated with the classic COVID-19 CT images (P = 0.014). Patients with extremely raised IL-6 levels required intensive treatment as compared to normal IL-6 group in terms of tocilizumab therapy (P = 0.008), noninvasive ventilation (P < 0.001), and intensive care unit care (P = 0.009) associated with higher mortality (P = 0.046). Conclusion: Raised IL-6 levels in COVID-19 patients should be considered a risk factor for the severity of the disease, inflammatory storm, and rapid pulmonary invasion. There is an urgent need for establishing a treatment protocol in patients with extremely raised IL-6 levels.

Promising Generative Adversarial Network Based Sinogram Inpainting Method for Ultra-Limited-Angle Computed Tomography Imaging.

Limited-angle computed tomography (CT) image reconstruction is a challenging problem in the field of CT imaging. In some special applications, limited by the geometric space and mechanical structure of the imaging system, projections can only be collected with a scanning range of less than 90°. We call this kind of serious limited-angle problem the ultra-limited-angle problem, which is difficult to effectively alleviate by traditional iterative reconstruction algorithms. With the development of deep learning, the generative adversarial network (GAN) performs well in image inpainting tasks and can add effective image information to restore missing parts of an image. In this study, given the characteristic of GAN to generate missing information, the sinogram-inpainting-GAN (SI-GAN) is proposed to restore missing sinogram data to suppress the singularity of the truncated sinogram for ultra-limited-angle reconstruction. We propose the U-Net generator and patch-design discriminator in SI-GAN to make the network suitable for standard medical CT images. Furthermore, we propose a joint projection domain and image domain loss function, in which the weighted image domain loss can be added by the back-projection operation. Then, by inputting a paired limited-angle/180° sinogram into the network for training, we can obtain the trained model, which has extracted the continuity feature of sinogram data. Finally, the classic CT reconstruction method is used to reconstruct the images after obtaining the estimated sinograms. The simulation studies and actual data experiments indicate that the proposed method performed well to reduce the serious artifacts caused by ultra-limited-angle scanning.

High spatial resolution computed tomography of chemiluminescence with densely sampled parallel projections.

Computed tomography of chemiluminescence (CTC) is an effective tool for combustion diagnostics by using optical detectors to capture the projections of luminescence from multiple views and realizing the three-dimensional (3D) reconstruction by computed tomography (CT) theories. In the existing CTC, ordinary commodity lenses were employed in the system for imaging, the imaging effects complicate the projection model and the low sampling rate decreases the spatial resolution and reconstruction accuracy. In classical CT techniques, parallel projection based on 2D Radon transform is the simplest model, which has been widely used in CT applications. In this work, double telecentric lens is introduced in CTC to realize the acquisition of parallel projection with high sampling rate. Despite the parallel projection CT theories have been well studied, there are still a few theoretical and technological drawbacks need to be solved when utilizing double telecentric lens in CTC. Firstly, a simple method based on bilinear interpolation is studied to improve the calculation accuracy of the weight matrix. Secondly, the exact reconstruction condition for parallel projections is studied based on the discrete Radon transform theory. It establishes the theoretical relationship of the reconstruction quality and the sampling rate of the projections, the number of views, the range and the spatial resolution of the reconstructed region. In experiment, camera calibration technique for double telecentric lens is studied, and the results of which are used for projection correction. The tomographic reconstructions of an axisymmetric flame demonstrate the feasibility and accuracy of the studies.

Lesion Detection of Computed Tomography and Magnetic Resonance Imaging Image Based on Fully Convolutional Networks

Computed tomography (CT) and Magnetic resonance imaging (MRI) are two kinds of important medical images, simply namely CT and MRI. Automatic lesion detection of CT and MRI is an important step for accurate clinical diagnosis. The classical CT and MRI lesion segmentation methods have bad performance due to the complex background noise, various illumination, and uneven color on CT image. In this paper, an improved fully convolutional network (FCN) model is proposed for lesion detection of CT and MRI image. The structure is same as FCN, and the lesion information from a deep layer is combined with appearance information from a shallow layer. First, we labeled all of the images from training set manually, the lesion and background labeled as 1 and 0, respectively. Then, the whole CT and MRI image dataset is fed to FCN. After 100 epochs training iterations, the model after the last iteration is selected as the final model, and then test dataset is put into the final model to obtain the detection results. The experimental results show that the proposed method can effectively detect and segment the lesion of CT and MRI images and greatly improve the segmentation accuracy, and can be used for the automatic lesion detection of CT and MRI images.

A variational proximal alternating linearized minimization in a given metric for limited-angle CT image reconstruction

• A nonconvex and nonsmooth optimization model is investigated for limited-angle CT imaging. • The proposed method can avoid computing the inverse of a large system matrix. • We show that each bounded sequence generated by our method globally converges to a critical point. • The results by our method are shown superior than some classical CT reconstruction methods by real data experiments. Due to the restriction of computed tomography (CT) scanning environment, the acquired projection data may be incomplete for exact CT reconstruction. Though some convex optimization methods, such as total variation minimization based method, can be used for incomplete data reconstruction, the edge of reconstruction image may be partly distorted for limited-angle CT reconstruction. To promote the quality of reconstruction image for limited-angle CT imaging, in this paper, a nonconvex and nonsmooth optimization model was investigated. To solve the model, a variational proximal alternating linearized minimization (VPALM) method based on proximal mapping in a given metric was proposed. The proposed method can avoid computing the inverse of a huge system matrix thus can be used to deal with the larger-scale inverse problems. What’s more, we show that each bounded sequence generated by VPALM globally converges to a critical point based on the Kurdyka–Lojasiewicz property . Real data experiments are used to demonstrate the viability and effectiveness of VPALM method, and the results show that the proposed method outperforms two classical CT reconstruction methods.

Error bounds and stability in the $l_{0}$ regularized for CT reconstruction from small projections

Due to the restriction of the scanning environment and the energy of X-ray, few projections of an object can be obtained in some practical applications of computed tomography (CT).In these situations, the projection data are incomplete and inconsistent, and the conventional analytic algorithm such as filtered backprojection (FBP) algorithm will not work.The streak artifacts can be significantly reduced in few-view reconstruction if the total variation minimization (TVM) based CT reconstruction algorithm is used.However, in the premise of preserving the resolution of image, it will not effectively suppress slope artifacts and metal artifacts when dealing with some few-view of the limited-angle reconstruction problems.To solve this problem, we focus on the image reconstruction algorithm base on $\ell_{0}$ regularized of wavelet coefficients. In this paper, the error bound between the reference or desire image and the reconstructed result, and the stability of solution were shown in theoretical and experimental, a reconstruction experiment on metal laths from few-view of the limited-angle projections was given. The experimental results indicate that this algorithm outperforms classical CT reconstruction algorithms in preserving the resolution of reconstructed image and suppressing the metal artifacts.

Subacute Subdural Hematoma mimicking Epidural Hematoma in Infant Patient

ABSTRACT Subacute subdural hematoma (SDH) is one of the most common clinical entities encountered in daily neurosurgical practice. The imaging of computed tomography (CT) has made a major impact on the diagnosis of subacute SDH. Although unilateral chronic lesion of SDH as a result of a space-occupying lesion is usually easily recognizable on CT scan, subacute SDH appearing in lenticular form may cause considerable difficulty, particularly when its appearance mimics the classic CT scan appearance of an epidural hematoma (EDH). Pathognomonic findings on CT scan are usually sufficient to establish a correct diagnosis, though the presence of such appearance can also be a misleading finding, especially in an infant patient. How to cite this article Yudoyono F, Faried A, Wirjomartani BA, Arifin MZ. Subacute Subdural Hematoma mimicking Epidural Hematoma in Infant Patient. Panam J Trauma Crit Care Emerg Surg 2016;5(2):113-115.

Primary Cavernous Haemangioma of the Frontal Bone: Computed Tomography Features.

Primary Cavernous Haemangioma of the Frontal Bone: Computed Tomography Features.

Anisakiasis presenting to the ED: clinical manifestations, time course, hematologic tests, computed tomographic findings, and treatment

BackgroundThe prevalence of anisakiasis is rare in the United States and Europe compared with that in Japan, with few reports of its presentation in the emergency department (ED). This study describes the clinical, hematologic, computed tomographic (CT) characteristics, and treatment in gastric and small intestinal anisakiasis patients in the ED. MethodsWe retrospectively reviewed the data of 83 consecutive anisakiasis presentations in our ED between 2003 and 2012. Gastric anisakiasis was endoscopically diagnosed with the Anisakis polypide. Small intestinal anisakiasis was diagnosed based on both hematologic (Anisakis antibody) and CT findings. ResultsOf the 83 cases, 39 had gastric anisakiasis and 44 had small intestinal anisakiasis based on our diagnostic criteria. Although all patients had abdominal pain, the gastric anisakiasis group developed symptoms significantly earlier (peaking within 6 hours) than the small intestinal anisakiasis group (peaking within 48 hours), and fewer patients with gastric anisakiasis needed admission therapy (5% vs 57%, P < .01). All patients in the gastric and 40 (91%) in the small intestinal anisakiasis group had a history of raw seafood ingestion. Computed tomographic findings revealed edematous wall thickening in all patients, and ascites and phlegmon of the mesenteric fat were more frequently observed in the small intestinal anisakiasis group. ConclusionsIn the ED, early and accurate diagnosis of anisakiasis is important to treat and explain to the patient, and diagnosis can be facilitated by a history of raw seafood ingestion, evaluation of the time-to-symptom development, and classic CT findings.

Isolated spontaneous dissection of a visceral artery: a rare cause of epigastric pain.

Isolated spontaneous dissection of the celiac trunk or superior mesenteric artery is rarely considered in patients with acute abdominal pain. However, with advances in computed tomography (CT) technology, more cases are being detected. The aim of this study was to describe the clinical manifestation and the classical CT features of isolated spontaneous celiac trunk and superior mesenteric artery (SMA) dissection. The records of seven patients were reviewed to assess demographic data, presenting symptoms, location of dissection, diagnostic modalities, imaging findings, complications, and treatment. Six patients were men. The average age was 57 years (range, 44-80). Six had epigastric pain and one was asymptomatic. All were diagnosed by CT. The location of dissection was the celiac trunk in three and SMA in four. In all cases, the diagnosis was made by identifying an intimal flap on contrast-enhanced CT images. Extension of dissection to the hepatic artery was found in three patients. A number of associated imaging findings were also present: infiltration of the fat surrounding the vessel (four cases), aneurysmal dilatation (six), thrombosed false lumen (four), significant stenosis (two), and additional aortic or visceral artery aneurysm (four). One patient had renal infarction 2 weeks after initial presentation. Extensive evaluation of all patients revealed no serologic evidence to support the presence of vasculitis or an inflammatory disorder. All were treated conservatively with antihypertensive drugs, anti-inflammatory drugs, steroids, and anticoagulants. Isolated spontaneous splanchnic artery dissection should be considered in the differential diagnosis of acute abdominal pain.

Imaging diagnosis of gallstone ileus

Gallstone ileus is a rare and potentially serious complication of cholelithiasis.Its clinical symptoms are nonspecific.From March 2005 to September 2012,19 patients with gallstone ileus confirmed by surgery or endoscopy were admitted to the Pudong New Area People's Hospital.The accuracies of X-ray,uhrasonography,CT and magnetic resonance imaging (MRI) were 0/10,0/5,19/19 and 9/9,respectively.CT examination might be the first choice for diagnosing gallstone ileus ; the classical computed tomography (CT) presentation of gallstone ileus was the Rigler triad,including pneumobilia,ectopic stone and mechanical ileus; MRI examination was superior to CT examination in exposing the fistula,and can provide abundant information,which is important for designing the surgical procedures and judging the prognosis; X-ray and ultrasonography are beneficial in screening the diseases. Key words: Cholelithiasis ; Bowel obstruction ; Imaging diagnosis

Comparative study between computed tomography guided superior hypogastric plexus block and the classic posterior approach: A prospective randomized study.

Context:The classic posterior approach to superior hypogastric plexus block (SHPB) is sometimes hindered by the iliac crest or a prominent transverse process of L5. The computed tomography (CT) – guided anterior approach might overcome these difficulties.Aims:This prospective, comparative, randomized study was aimed to compare the CT guided anterior approach versus the classic posterior approach.Settings and Design:Controlled randomized study.Materials and Methods:A total of 30 patients with chronic pelvic cancer pain were randomized into either classic or CT groups where classic posterior approach or CT guided anterior approach were done, respectively. Visual analog score, daily analgesic morphine consumed and patient satisfaction were assessed just before the procedure, then, after 24 h, 1 week and monthly for 2 months after the procedure. Duration of the procedure was also recorded. Adverse effects associated with the procedure were closely observed and recorded.Statistical Analysis Used:Student's t-test was used for comparison between groups.Results:Visual analog scale and morphine consumption decreased significantly in both groups at the measured times after the block compared with the baseline in the same group with no significant difference between both groups. The procedure was carried out in significantly shorter duration in the CT group than that in the classic group. The mean patient satisfaction scale increased significantly in both groups at the measured times after the block compared with the baseline in the same group. The patients in the CT groups were significantly more satisfied than those in classic group from day one after the procedure until the end of the study.Conclusions:The CT guided approach for SHPB is easier, faster, safer and more effective, with less side-effects than the classic approach.

Piecewise-Constant-Model-Based Interior Tomography Applied to Dentin Tubules

Dentin is a hierarchically structured biomineralized composite material, and dentin's tubules are difficult to study in situ. Nano-CT provides the requisite resolution, but the field of view typically contains only a few tubules. Using a plate-like specimen allows reconstruction of a volume containing specific tubules from a number of truncated projections typically collected over an angular range of about 140°, which is practically accessible. Classical computed tomography (CT) theory cannot exactly reconstruct an object only from truncated projections, needless to say a limited angular range. Recently, interior tomography was developed to reconstruct a region-of-interest (ROI) from truncated data in a theoretically exact fashion via the total variation (TV) minimization under the condition that the ROI is piecewise constant. In this paper, we employ a TV minimization interior tomography algorithm to reconstruct interior microstructures in dentin from truncated projections over a limited angular range. Compared to the filtered backprojection (FBP) reconstruction, our reconstruction method reduces noise and suppresses artifacts. Volume rendering confirms the merits of our method in terms of preserving the interior microstructure of the dentin specimen.

Can interior tomography outperform lambda tomography?

Whereas classic computed tomography (CT) theory targets the exact reconstruction of a whole cross-section or entire volume from complete projections, a real-world application often focuses on a region of interest (ROI). It has been a long-standing challenge to reconstruct an internal ROI only from truncated projections collected with a radiative beam through the ROI because this “interior problem” does not have a unique solution (1). When a traditional CT algorithm such as “filtered backprojection” is applied for an interior reconstruction from truncated projections, features outside the ROI may create artifacts overlapping inside features, rendering the images inaccurate or useless. On the other hand, over past decades, lambda tomography has been developed as a branch of applied mathematics that recovers gradient-like features within an ROI from truncated projections. With lambda tomography, the outcomes are not always the most appealing because of their nonquantitative nature. Recently, Quinto et al. (2) demonstrated the utility and limitation of electron lambda tomography and pointed out that “unless prior knowledge is being used…structures in the specimen cannot be exactly recovered even if we have access to noise-free continuum data….”

Volumetric spectral analysis of materials using terahertz-tomography techniques

We present for the first time a system and new algorithms for spectral THz-tomography. The electric field of single cycle ultra short THz-pulses can be measured time resolved in amplitude and phase. By focusing ultra short THz-pulses to a sample and analyzing the transmitted or reflected beams the inner structure of the sample can be investigated with a resolution up to 0.4 mm by evaluating the time resolved data. Thus a spectrum of every scanned THz-pulse can be calculated with the usage of the fast Fourier transform. In contrast to classical computed tomography (CT) with X-rays a higher amount of information can be obtained. Based on the characteristic absorption spectra of varying materials it is now possible to identify different substances inside a sample by terahertz-tomography with probabilities that are higher than 80%.