Contrast Computed Tomography Imaging Research Articles

Tantalum Sulfide Nanosheets as a Theranostic Nanoplatform for Computed Tomography Imaging-Guided Combinatorial Chemo-Photothermal Therapy.

Near-infrared (NIR)-absorbing metal-based nanomaterials have shown tremendous potential for cancer therapy, given their facile and controllable synthesis, efficient photothermal conversion, capability of spatiotemporal-controlled drug delivery, and intrinsic imaging function. Tantalum (Ta) is among the most biocompatible metals and arouses negligible adverse biological responses in either oxidized or reduced forms, and thus Ta-derived nanomaterials represent promising candidates for biomedical applications. However, Ta-based nanomaterials by themselves have not been explored for NIR-mediated photothermal ablation therapy. In this work, we report an innovative Ta-based multifunctional nanoplatform composed of biocompatible tantalum sulfide (TaS2) nanosheets (NSs) for simultaneous NIR hyperthermia, drug delivery, and computed tomography (CT) imaging. The TaS2 NSs exhibit multiple unique features including (i) efficient NIR light-to-heat conversion with a high photothermal conversion efficiency of 39%. (ii) high drug loading (177% by weight), (iii) controlled drug release triggered by NIR light and moderate acidic pH, (iv) high tumor accumulation via heat-enhanced tumor vascular permeability, (v) complete tumor ablation and negligible side effects, and (vi) comparable CT imaging contrast efficiency to the widely clinically used agent iobitridol. We expect that this multifunctional NS platform can serve as a promising candidate for imaging-guided cancer therapy and selection of cancer patients with high tumor accumulation.

Multi modality of hollow tube Gd2O3:Eu3+ nanoparticles by using nonpolar solvent

Gd2O3:Eu3+ is useful material in physics, chemical and biomedicine which can be applied to the magnetic resonance imaging (MRI) brightness, X-ray computed tomography (CT) as contrast agent and luminescence phenomenon as phosphor. In this paper, Gd2O3:Eu3+ was synthesized by one-step low cost solvothermal reaction with different ratio of solvents (De-ionized water (DI)/toluene (TL)). The alteration of solvent ratios affects the morphology (rod to hollow tube shape) and size of Gd2O3:Eu3+ which induce the property variation such as luminescence intensity, MR imaging and CT imaging brightness. The luminescence intensity of Gd2O3:Eu3+ nanoparticles with DI 40/TL 0 is much higher than the 1.48, 1.68, 1.73 and 1.75 times by others (DI 0/TL 40, DI 10/TL 30, DI 20/TL 20 and DI 30/TL 10), MR images of Gd2O3:Eu3+ with DI 0/TL 40 were shown to be 2.5 times brighter than that of the commercial contrast agent (Dotarem) and CT images of Gd2O3:Eu3+ with DI 0/TL 40 was 1.68 times brighter than Dotarem. Gd2O3:Eu3+ prepared with different solvent ratios can be selectively applied for potential applications as MRI, CT and FI multimodal imaging agent.

Paramedian Submandibular Approach for Removal of Foreign Bodies in the Pterygoid Muscle in Two Dogs.

The purpose of this report is to document a unique location of an oropharyngeal foreign body, diagnosed via contrast computed tomography (CT), as well as a novel surgical approach to the pterygoid muscle region. Oropharyngeal foreign objects are an uncommon but potentially serious disease that can lead to chronic abscessation and pain. Two dogs were presented with chronic complaints, including pain and inability to fully open the mouth for a 1 yr and 5 mo duration, respectively. There was no history or evidence of skin sinus or submandibular/cervical swelling on physical examination of either dog. Both dogs had normal oropharyngeal anatomy with the exception of an asymmetric contrast-enhancing lesion within the pterygoid muscle on CT imaging. As there were no gross abnormalities visible during surgery, the use of contrast CT was vital in order to isolate the focus of infection. A paramedian submandibular approach was used to explore this region, and in both cases, foreign material was successfully removed with subsequent resolution of clinical signs. The dogs were immediately free of clinical signs and showed no recurrence for at least 8 and 17 mo after the exploration, respectively. A novel surgical approach is described to remove oropharyngeal foreign objects and necrotic debris within the pterygoid muscle.

Rare Clinical Sign of Hodgkin's Lymphoma: Ocular Involvement.

Bilateral non-granulomatous anterior uveitis with left vitritis and macular edema were detected in a 19-year-old woman presenting with blurred vision in her left eye. Light microscopic study of the pathologic mediastinal lymph node that was detected via contrast computed tomography imaging during etiologic study revealed nodular sclerosing and mixed cellularity Hodgkin’s lymphoma (HL). Ocular findings completely resolved with adriablastin, bleomycin, vinblastine, dacarbazine chemotherapy treatment. Herein, it is emphasized that HL should be remembered as one of the differential diagnoses in patients with ocular inflammatory pathologies such as uveitis and vasculitis. The ocular findings of HL are discussed.

Single-energy computed tomography-based pulmonary perfusion imaging: Proof-of-principle in a canine model.

Purpose:Radiotherapy (RT) that selectively avoids irradiating highly functional lung regions may reduce pulmonary toxicity, which is substantial in lung cancer RT. Single-energy computed tomography (CT) pulmonary perfusion imaging has several advantages (e.g., higher resolution) over other modalities and has great potential for widespread clinical implementation, particularly in RT. The purpose of this study was to establish proof-of-principle for single-energy CT perfusion imaging.Methods:Single-energy CT perfusion imaging is based on the following: (1) acquisition of end-inspiratory breath-hold CT scans before and after intravenous injection of iodinated contrast agents, (2) deformable image registration (DIR) for spatial mapping of those two CT image data sets, and (3) subtraction of the precontrast image data set from the postcontrast image data set, yielding a map of regional Hounsfield unit (HU) enhancement, a surrogate for regional perfusion. In a protocol approved by the institutional animal care and use committee, the authors acquired CT scans in the prone position for a total of 14 anesthetized canines (seven canines with normal lungs and seven canines with diseased lungs). The elastix algorithm was used for DIR. The accuracy of DIR was evaluated based on the target registration error (TRE) of 50 anatomic pulmonary landmarks per subject for 10 randomly selected subjects as well as on singularities (i.e., regions where the displacement vector field is not bijective). Prior to perfusion computation, HUs of the precontrast end-inspiratory image were corrected for variation in the lung inflation level between the precontrast and postcontrast end-inspiratory CT scans, using a model built from two additional precontrast CT scans at end-expiration and midinspiration. The authors also assessed spatial heterogeneity and gravitationally directed gradients of regional perfusion for normal lung subjects and diseased lung subjects using a two-sample two-tailed t-test.Results:The mean TRE (and standard deviation) was 0.6 ± 0.7 mm (smaller than the voxel dimension) for DIR between pre contrast and postcontrast end-inspiratory CT image data sets. No singularities were observed in the displacement vector fields. The mean HU enhancement (and standard deviation) was 37.3 ± 10.5 HU for normal lung subjects and 30.7 ± 13.5 HU for diseased lung subjects. Spatial heterogeneity of regional perfusion was found to be higher for diseased lung subjects than for normal lung subjects, i.e., a mean coefficient of variation of 2.06 vs 1.59 (p = 0.07). The average gravitationally directed gradient was strong and significant (R2 = 0.99, p < 0.01) for normal lung dogs, whereas it was moderate and nonsignificant (R2 = 0.61, p = 0.12) for diseased lung dogs.Conclusions:This canine study demonstrated the accuracy of DIR with subvoxel TREs on average, higher spatial heterogeneity of regional perfusion for diseased lung subjects than for normal lung subjects, and a strong gravitationally directed gradient for normal lung subjects, providing proof-of-principle for single-energy CT pulmonary perfusion imaging. Further studies such as comparison with other perfusion imaging modalities will be necessary to validate the physiological significance.

229-05: Signal density gradient of left atrial appendage on computed tomography correlates with left atrial appendage flow velocity on trans-esophageal echocardiography

Background: Cardiac contrast computed tomography (CT) is frequently performed for anatomical assessment before catheter ablation of atrial tachyarrhythmia. While the usefulness of this modality for detection of left atrial thrombus has been reported, the ability for risk stratification of thromboembolic events has not been elucidated. Methods: Total of 81 consecutive patients who underwent catheter ablation for atrial tachyarrhythmia at our institution from April 2014 to September 2015 were enrolled. Patients lacking the cardiac contrast CT or TEE data were excluded, leading to 53 patients (37 male, median age 69 years [interquartile range 62–75]) for analysis. From the CT image, the left atrial appendage [LAA] signal density gradient defined as the difference between the CT density of ostium and apex of LAA were obtained, and correlation with LAA flow velocity on TEE were analyzed. Results: In the correlation analysis, LAA signal density gradient showed significant relatively strong correlation with the LAA flow velocity (r = 0.551, P < 0.001). In multiple regression analysis, LAA signal density gradient remained to be independent predictor of LAA flow velocity, even after adjustment with other cofounders (b = 0.001, β = 0.381, P = 0.010). Conclusion: LAA signal density gradient of CT significantly correlates with LAA flow velocity of TEE in patients undergoing catheter ablation for atrial tachyarrhythmia. This variable may be used for risk stratification for future thromboembolic events in this patient population.

Development of a Novel Medial Synoviocentesis Approach to the Bicipital Bursa in an Equine Cadaver Model.

To describe the volume and dimensions of the bicipital bursa and its position in relation to bony and soft tissue structures, in order to develop a novel medial synoviocentesis approach to the bicipital bursa. Cadaveric study. Adult equine cadaver limbs (n=19). Bicipital bursa dimensions, volume, and relationship to bony structures were obtained from positive contrast computed tomography images after distension of the bursa (n=7). Following an intra-bursal injection of polyurethane resin, the bicipital bursa (n=4) was dissected and its relationship to soft tissue structures described. After computed tomography and dissection, a novel medial bicipital bursocentesis approach was investigated on intact cadavers (n=8). Median (range) of measurements were: length 9.02 cm (8.48-9.45 cm); width 7.06 cm (6.71-8.01 cm); and volume 51 mL (45-58 mL). The medial aspect of the bicipital bursa was located at the junction of the subclavius and biceps muscles, which corresponds with the externally visible lateral pectoral sulcus. Needle insertion 5-10 mm craniolateral to the center of the lateral pectoral sulcus midway between the palpable distal aspect of the deltoid tuberosity and the cranial part of the greater tubercle was found to be a reliable landmark for the novel medial bursocentesis approach. This approach was successful in all cadavers. The novel approach to the bicipital bursa provided access to the medial aspect of the bursa and is an alternative to the lateral approaches. Further validation in live horses is warranted to establish the safety and efficacy of this technique.

New Radiological Index for Evaluation of Pectus Deformities in Indian Population

Abstract Aim: To evaluate the effectiveness of new radiological index for the diagnosis of pectus deformities in Indian population using computed tomography (CT) imaging. Materials and methods: 60 subjects with mild to moderate pectus deformities and 100 controls with age group from 1 to 40 years were evaluated for the study. Non contrast CT images with sagittal, axial sections and 3D reconstructed images were utilized for the measurement of manubriosternal joint (MSJT) angulation as well as sterno-vertebral (SV) distance and transverse diameter (A) of chest. Results: In controls manubriosternal joint showed mean value of 166.6±5.27, in pectus carinatum (PC) MSJT measured about 170±5.2 and in pectus excavatum (PE) MSJT had a value of 157.6±14.57and internal thoracic dimensions like sterno-vertebral distance measured about mean of 91.3±18.12 in controls, 80.24±14.57 in PE and 99.13±15.6 in PC and transverse diameter with a mean of 208.72±33.9in controls, 223.14±28.92 in PE and 192.2±40.96 in PC. Conclusion: Inclusion of MSJT angulation as radiological index alongside of internationally accepted indices like sterno-vertebral distance and transverse diameter of chest would ensure comprehensive assessment of chest wall deformation and help in better understanding of sternal displacement during pectus deformities.

Folic acid-modified Fe3O4@Au core/shell nanostars for multimode imaging and photothermal therapy of tumors

Event Abstract Back to Event Folic acid-modified Fe3O4@Au core/shell nanostars for multimode imaging and photothermal therapy of tumors Xiangyang Shi1, Yong Hu1, Ruizhi Wang2 and Mingwu Shen1 1 Donghua University, College of Chemistry, Chemical Engineering and Biotechnology, China 2 Zhongshan Hospital, Fudan University,, Interventional Radiography, China Iron oxide (Fe3O4) nanoparticles (NPs) have been generally used as T2-negative magnetic resonance (MR) imaging contrast agents because of their ability to shorten the T2 relaxation time of water protons[1]. On the other hand, gold (Au) NPs have been widely used as CT imaging contrast agents due to their high X-ray attenuation coefficient[2]. In addition, AuNPs with particular shapes such as nanorods, nanocages, or nanostars (NSs) display strong surface plasmon resonance (SPR) absorption in near infrared (NIR) region, enabling their uses for photoacoustic (PA) imaging, thermal imaging and photothermal therapy of cancer[3],[4]. In this work, a facile mild reduction method was employed to synthesize Fe3O4@Ag nanoparticles (NPs)[1] and the thus-prepared NPs were used as seeds to form Fe3O4@Au NSs in the Au growth solution. Further sequential modification of polyethyleneimine (PEI) and folic acid (FA)-conjugated polyethylene glycol (PEG-FA) affords the NSs with excellent colloidal stability, good biocompatibility, and targeting specificity to cancer cells over-expressing FA receptors. With the Fe3O4 core NPs and the star-shaped Au shells, the formed Fe3O4@Au-PEI.Ac-PEG-FA NSs are able to be used as a nanoprobe for efficient of MR and computed tomography (CT) imaging of cancer cells in vitro and the xenografted tumor model in vivo. Likewise, the NIR absorption property enables the developed Fe3O4@Au-PEI.Ac-PEG-FA NSs to be used as a nanoprobe for PA and thermal imaging of tumors in vivo and photothermal ablation of cancer cells in vitro and the xenografted tumor model in vivo. This study fully demonstrates a unique multifunctional theranostic nanoplatform for multimode imaging and photothermal therapy of tumors. National Natural Science Foundation of China (21273032, 81341050, and 81371623); Sino-German Center for Research Promotion (GZ899); Program for Professor of Special Appointment (Eastern Scholar) at Shanghai Institutions of Higher Learning; Fundamental Research Funds for the Central Universities; Innovation Funds of Donghua University Master Dissertation of Excellence

A comparative dosimetric study of volumetric-modulated arc therapy vs. fixed field intensity-modulated radiotherapy in postoperative irradiation of stage IB-IIA high-risk cervical cancer.

The aim of the present study was to compare the dosimetry features of volumetric-modulated arc therapy (VMAT) and fixed field intensity-modulated radiotherapy (f-IMRT) in postoperative irradiation of stage IB-IIA high-risk cervical cancer. Fifteen patients exhibiting stage IB-IIA high-risk cervical cancer, who had been treated with postoperative adjuvant concurrent radiochemotherapy, were selected. The clinical target volume (CTV) and organs at risk (OARs) were delineated according to contrast computed tomography images. The planning target volume (PTV) was subsequently produced by using 1 cm uniform expansion of the CTV. The treatment plans were intended to deliver 50 Gy in 25 fractions. The OARs that were contoured included the bladder, rectum, small bowel and femoral heads. Dose volume histograms were used to evaluate the dose distribution in the PTV and OARs. VMAT and f-IMRT treatment plans resulted in similar dose coverage of the PTV. VMAT was superior to f-IMRT in conformity (P<0.05), and resulted in a reduction of OARs irradiated at high dose levels (V40 and V50) compared with f-IMRT (P<0.05), particularly for the bladder. However, the doses of low levels (V10 and V20) delivered to OARs with f-IMRT were slightly reduced compared with VMAT (P<0.05). For ambilateral femoral heads, VMAT demonstrated improved sparing compared with f-IMRT, with regard to D5 (P<0.05). Furthermore, VMAT treatment plans revealed a significant reduction in monitor units (MU) and treatment time. VMAT techniques exhibited similar PTV coverage compared with f-IMRT. At doses of high levels delivered to OARs, VMAT demonstrated improved sparing compared with f-IMRT, particularly for the bladder, while significantly reducing treatment time and MU number.

Yb³⁺/Er³⁺-Codoped Bi₂O₃ Nanospheres: Probe for Upconversion Luminescence Imaging and Binary Contrast Agent for Computed Tomography Imaging.

In this work, water-soluble Yb(3+)/Er(3+) codoped Bi2O3 upconversion (UC) nanospheres with uniform morphology have been successfully synthesized via a solid-state-chemistry thermal decomposition process. With 980 nm near-infrared irradiation, the Bi2O3:Yb(3+)/Er(3+) nanospheres have bright UC luminescence (UCL). Moreover, multicolor UC emissions (from green to red) can be tuned by simply changing the Yb(3+) ions doping concentration. After citric acid molecules were grafted on the surface of Bi2O3:20% Yb(3+)/2% Er(3+) nanospheres, the MTT assay on HeLa cells and CCK-8 assay on osteoblasts show that the UC nanospheres exhibit excellent stability and biocompatibility. The possibility of using these nanoprobes with red UCL for optical imaging in vivo has been demonstrated. Furthermore, Bi(3+) and Yb(3+) containing nanospheres as binary contrast agent also exhibited significant enhancement of contrast efficacy than iodine-based contrast agent via X-ray computed tomography (CT) imaging at different voltage setting (80-140 kVp), indicating they have potential as CT imaging contrast agent. Thus, Yb(3+)/Er(3+) codoped Bi2O3 nanospheres could be used as dual modality probe for optical and CT imagings.

Effective staging of fibrosis by the selected texture features of liver: Which one is better, CT or MR imaging?

PurposeTexture patterns of hepatic fibrosis are one of the important biomarkers to diagnose and classify chronic liver disease from initial to end stage on computed tomography (CT) or magnetic resonance (MR) images. Computer-aided diagnosis (CAD) of liver cirrhosis using texture features has become popular in recent research advances. To date, however, properly selecting effective texture features and image parameters is still mostly undetermined and not well-defined. In this study, different types of datasets acquired from CT and MR images are investigated to select the optimal parameters and features for the proper classification of fibrosis. MethodsA total of 149 patients were scanned by multi-detector computed tomography (MDCT) and 218 patients were scanned using 1.5T and 3T superconducting MR scanners for an abdominal examination. All cases were verified by needle biopsies as the gold standard of our experiment, ranging from 0 (no fibrosis) to 5 (cirrhosis). For each case, at least four sequenced phase images are acquired by CT or MR scanners: pre-contrast, arterial, portal venous and equilibrium phase. For both imaging modalities, 15 texture features calculated from gray level co-occurrence matrix (GLCM) are extracted within an ROI in liver as one set of input vectors. Each combination of these input subsets is checked by using support vector machine (SVM) with leave-one-case-out method to differentiate fibrosis into two groups: non-cirrhosis or cirrhosis. In addition, 10 ROIs in the liver are manually selected in a disperse manner by experienced radiologist from each sequenced image and each of the 15 features are averaged across the 10 ROIs for each case to reduce the validation time. The number of input items is selected from the various combinations of 15 features, from which the accuracy rate (AR) is calculated by counting the percentage of correct answers on each combination of features aggregated to determine a liver stage score and then compared to the gold standard. ResultsAccording to the accuracy rate (AR) calculated from each combination, the optimal number of texture features to classify liver fibrosis degree ranges from 4 to 7, no matter which modality was utilized. The overall performance calculated by the average sum of maximum AR value of all 15 features is 66.83% in CT images, while 68.14%, and 71.98% in MR images, respectively; among the 15 texture features, mean gray value and entropy are the most commonly used features in all 3 imaging datasets. The correlation feature has the lowest AR value and was removed as an effective feature in all datasets. AR value tends to increase with the injection of contrast agency, and both CT and MR images reach the highest AR performance during the equilibrium phase. ConclusionsComparing the accuracy of classification with two imaging modalities, the MR images have an advantage over CT images with regards to AR performance of the 15 selected texture features, while 3T MRI is better than 1.5T MRI to classify liver fibrosis. Finally, the texture analysis is more effective during equilibrium phase than in any of the other phased images.

X-ray phase contrast tomography by tracking near field speckle.

X-ray imaging techniques that capture variations in the x-ray phase can yield higher contrast images with lower x-ray dose than is possible with conventional absorption radiography. However, the extraction of phase information is often more difficult than the extraction of absorption information and requires a more sophisticated experimental arrangement. We here report a method for three-dimensional (3D) X-ray phase contrast computed tomography (CT) which gives quantitative volumetric information on the real part of the refractive index. The method is based on the recently developed X-ray speckle tracking technique in which the displacement of near field speckle is tracked using a digital image correlation algorithm. In addition to differential phase contrast projection images, the method allows the dark-field images to be simultaneously extracted. After reconstruction, compared to conventional absorption CT images, the 3D phase CT images show greatly enhanced contrast. This new imaging method has advantages compared to other X-ray imaging methods in simplicity of experimental arrangement, speed of measurement and relative insensitivity to beam movements. These features make the technique an attractive candidate for material imaging such as in-vivo imaging of biological systems containing soft tissue.

Computed Tomography Image Enhancement Using Cuckoo Search: A Log Transform Based Approach

Medical image enhancement is an essential process for superior disease diagnosis as well as for detection of pathological lesion accurately. Computed Tomography (CT) is considered a vital medical imaging modality to evaluate numerous diseases such as tumors and vascular lesions. However, speckle noise corrupts the CT images and makes the clinical data analysis ambiguous. Therefore, for accurate diagnosis, medical image enhancement is a must for noise removal and sharp/clear images. In this work, a medical image enhancement algorithm has been proposed using log transform in an optimization framework. In order to achieve optimization, a well-known meta-heuristic algorithm, namely: Cuckoo search (CS) algorithm is used to determine the optimal parameter settings for log transform. The performance of the proposed technique is studied on a low contrast CT image dataset. Besides this, the results clearly show that the CS based approach has superior convergence and fitness values compared to PSO as the CS converge faster that proves the efficacy of the CS based technique. Finally, Image Quality Analysis (IQA) justifies the robustness of the proposed enhancement technique.

A case of extraperitoneal bladder rupture in which a surgical operation was necessary

We treated a case of traumatic extraperitoneal bladder rupture and achieved a good clinical outcome via surgical operation. The patient, a 70-year-old female, had jumped from the 2nd floor of a building in order to commit suicide. Contrast computed tomography images showed disruption of the bladder wall, and extravasation of contrast medium was observed. After tests, the vital signs showed that the patient had gone into shock, and emergency surgery was performed. We repaired an 8-cm-long injury of the anterior bladder wall. The postoperative course was favorable. A contrasted cystogram was obtained 3 weeks postoperatively. We confirmed that there was no leakage of contrast medium from the bladder wall. The patient had extraperitoneal bladder rupture complicating a pelvic fracture, and a pessary may have caused enlargement of the injury site. We selected surgical operation for this case of extraperitoneal bladder rupture and achieved a favorable clinical outcome. Language: ja

The Feasibility Study of MRI-Based Dose Calculation With Look-up Table in Radiation Treatment Planning

Computed tomography (CT) has been the basis for the radiation treatment planning (RTP) because of converted Hounsfield units. In the brain regions, an accurate delineation of the target volume, however, has been difficult with only the CT data due to the poor soft tissue contrast of CT images. Therefore, the magnetic resonance images (MRI) for the delineation of the target volumes were used. In this study, MRI-based treatment planning was developed by generated electron density through the use of diagnostic MRI.

Lymph node shape in computed tomography imaging as a predictor for axillary lymph node metastasis in patients with breast cancer.

The aim of the present study was to evaluate whether preoperative computed tomography (CT) is a useful modality for the diagnosis of axillary lymph node metastasis. The axillary lymph node status was examined in patients with primary breast cancer who had undergone surgery. In total, 75 patients were analyzed with preoperative contrast CT images, following which the patients underwent an intraoperative sentinel lymph node biopsy to determine possible predictors of axillary lymph node metastasis. The lymph node shape was classified into three groups, which included fat-, clear-and obscure-types. Multivariate analysis revealed that clear-type lymph nodes in preoperative contrast CT imaging may be an independent predictor of lymph node metastasis (odds ratio, 15; P=0.003). Therefore, the results indicated that preoperative CT examination is useful to predict axillary lymph node metastasis.

Implications of CT noise and artifacts for quantitative 99mTc SPECT/CT imaging

This paper evaluates the effects of computed tomography (CT) image noise and artifacts on quantitative single-photon emission computed-tomography (SPECT) imaging, with the aim of establishing an appropriate range of CT acquisition parameters for low-dose protocols with respect to accurate SPECT attenuation correction (AC). SPECT images of two geometric and one anthropomorphic phantom were reconstructed iteratively using CT scans acquired at a range of dose levels (CTDIvol = 0.4 to 46 mGy). Resultant SPECT image quality was evaluated by comparing mean signal, background noise, and artifacts to SPECT images reconstructed using the highest dose CT for AC. Noise injection was performed on linear-attenuation (μ) maps to determine the CT noise threshold for accurate AC. High levels of CT noise (σ ∼ 200-400 HU) resulted in low μ-maps noise (σ ∼ 1%-3%). Noise levels greater than ∼ 10% in 140 keV μ-maps were required to produce visibly perceptible increases of ∼ 15% in (99m)Tc SPECT images. These noise levels would be achieved at low CT dose levels (CTDIvol = 4 μGy) that are over 2 orders of magnitude lower than the minimum dose for diagnostic CT scanners. CT noise could also lower (bias) the expected μ values. The relative error in reconstructed SPECT signal trended linearly with the relative shift in μ. SPECT signal was, on average, underestimated in regions corresponding with beam-hardening artifacts in CT images. Any process that has the potential to change the CT number of a region by ∼ 100 HU (e.g., misregistration between CT images and SPECT images due to motion, the presence of contrast in CT images) could introduce errors in μ140 keV on the order of 10%, that in turn, could introduce errors on the order of ∼ 10% into the reconstructed (99m)Tc SPECT image. The impact of CT noise on SPECT noise was demonstrated to be negligible for clinically achievable CT parameters. Because CT dose levels that affect SPECT quantification is low (CTDIvol ∼ 4 μGy), the low dose limit for the CT exam as part of SPECT/CT will be guided by CT image quality requirements for anatomical localization and artifact reduction. A CT technique with higher kVp in combination with lower mAs is recommended when low-dose CT images are used for AC to minimize beam-hardening artifacts.

Investigation of gastric cancers in nude mice using X-ray in-line phase contrast imaging.

BackgroundThis paper is to report the new imaging of gastric cancers without the use of imaging agents. Both gastric normal regions and gastric cancer regions can be distinguished by using the principal component analysis (PCA) based on the gray level co-occurrence matrix (GLCM).MethodsHuman gastric cancer BGC823 cells were implanted into the stomachs of nude mice. Then, 3, 5, 7, 9 or 11 days after cancer cells implantation, the nude mice were sacrificed and their stomachs were removed. X-ray in-line phase contrast imaging (XILPCI), an X-ray phase contrast imaging method, has greater soft tissue contrast than traditional absorption radiography and generates higher-resolution images. The gastric specimens were imaged by an XILPCIs’ charge coupled device (CCD) of 9 μm image resolution. The PCA of the projective images’ region of interests (ROIs) based on GLCM were extracted to discriminate gastric normal regions and gastric cancer regions. Different stages of gastric cancers were classified by using support vector machines (SVMs).ResultsThe X-ray in-line phase contrast images of nude mice gastric specimens clearly show the gastric architectures and the details of the early gastric cancers. The phase contrast computed tomography (CT) images of nude mice gastric cancer specimens are better than the traditional absorption CT images without the use of imaging agents. The results of the PCA of the texture parameters based on GLCM of normal regions is (F1 + F2) > 8.5, but those of cancer regions is (F1 + F2) < 8.5. The classification accuracy is 83.3% that classifying gastric specimens into different stages using SVMs.ConclusionsThis is a very preliminary feasibility study. With further researches, XILPCI could become a noninvasive method for future the early detection of gastric cancers or medical researches.

Hybrid Treatment for Ruptured Diverticulum of Kommerell: A Minimally Invasive Option

Although aberrant right subclavian artery is the commonest aortic arch anomaly, it is a rare entity in clinical practice. While mostly asymptomatic, the rupture of an aneurysm of an aberrant right subclavian artery or Kommerell's diverticulum can be life threatening. A conventional open surgical approach involving sternotomy and resection of the abnormal vessels under circulatory support carries significant morbidity and mortality. We report a case of a ruptured diverticulum of Kommerell that was successfully treated with a hybrid debranching surgery, Amplatzer device embolization of the subclavian vessels, and thoracic aortic endovascular stenting.