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Showing papers in "Journal of X-ray Science and Technology in 2013"


Journal ArticleDOI
TL;DR: It is found that the difficulty in generating accurate priors to be the predominant factor limiting the effectiveness of the state-of-the-art medical MAR techniques when applied to non-medical CT imagery.
Abstract: We present a survey of techniques for the reduction of streaking artefacts caused by metallic objects in X-ray Computed Tomography (CT) images. A comprehensive review of the existing state-of-the-art Metal Artefact Reduction (MAR) techniques, drawn predominantly from the medical CT literature, is supported by an experimental comparison of twelve MAR techniques. The experimentation is grounded in an evaluation based on a standard scientific comparison protocol for MAR methods, using a software generated medical phantom image as well as a clinical CT scan. The experimentation is extended by considering novel applications of CT imagery consisting of metal objects in non-tissue surroundings acquired from the aviation security screening domain. We address the shortage of thorough performance analyses in the existing MAR literature by conducting a qualitative as well as quantitative comparative evaluation of the selected techniques. We find that the difficulty in generating accurate priors to be the predominant factor limiting the effectiveness of the state-of-the-art medical MAR techniques when applied to non-medical CT imagery. This study thus extends previous works by: comparing several state-of-the-art MAR techniques; considering both medical and non-medical applications and performing a thorough performance analysis, considering both image quality as well as computational demands.

72 citations


Journal ArticleDOI
Ming Chang1, Liang Li1, Zhiqiang Chen1, Yongshun Xiao1, Li Zhang1, Ge Wang2 
TL;DR: This paper proposes a few-view reweighted sparsity hunting (FRESH) method for CT image reconstruction, and demonstrates the superior performance of this method, which performs significantly better than competing algorithms in terms of image quality and convergence speed.
Abstract: In recent years, the total variation (TV) minimization method has been widely used for compressed sensing (CS) based CT image reconstruction. In this paper, we propose a few-view reweighted sparsity hunting (FRESH) method for CT image reconstruction, and demonstrate the superior performance of this method. Specifically, the key of the purposed method is that a reweighted total variation (RwTV) measure is used to characterize image sparsity in the cost function, outperforming the conventional TV counterpart. To solve the RwTV minimization problem efficiently, the Split-Bregman method and other state-of-the-art L1 optimization methods are compared. Inspired by the fast iterative shrinkage/thresholding algorithm (FISTA), a predication step is incorporated for fast computation in the Split-Bregman framework. Extensive numerical experiments have shown that our FRESH approach performs significantly better than competing algorithms in terms of image quality and convergence speed for few-view CT. High-quality images were reconstructed by our FRESH method after 250 iterations using only 15 few-view projections of the Forbild head phantom while other competitors needed more than 800 iterations. Remarkable improvements in details in the experimental evaluation using actual sheep thorax data further indicate the potential real-world application of the FRESH method.

70 citations


Journal ArticleDOI
TL;DR: PVP is an effective technique in patients with BPH, when compared to TURP, producing equivalent improvements in IPSS, Qmax, Qol and PVR with the advantages of markedly reduced catheterization time, admission time and adverse events.
Abstract: The most recent advance in laser treatment of benign prostatic hyperplasia (BPH) is the introduction of a high-performance system (HPS) 120-W laser. The HPS laser beam at a wavelength of 532~nm is highly absorbed by oxyhemoglobin in the tissue and maintains focus with negligible divergence up to 3 mm from the fiber and with limited divergence at 5 mm. This study is designed to evaluate the three-year clinical efficacy and safety of photoselective vaporization of the prostate (PVP, n=100 cases) with GreenLight HPS laser compared with transurethral resection of the prostate (TURP, n=100 cases) for treatment of BPH. The results showed that the mean operating time, catheterization time and admission time were significantly shorter in the PVP group, respectively. There were dramatic improvements in International Prostate Symptom Score (IPSS), quality of life (Qol), maximum flow rate (Qmax) and postvoid residual (PVR) compared with preoperative values and the degree of improvements was comparable in both groups. The intraoperative complications were lower in PVP group. In summary, PVP is an effective technique in patients with BPH, when compared to TURP, producing equivalent improvements in IPSS, Qmax, Qol and PVR with the advantages of markedly reduced catheterization time, admission time and adverse events.

36 citations


Journal ArticleDOI
TL;DR: These data can be helpful for the development of new and more specific GNP-based radiosensitizers of potential interest in radiotherapy, exploiting the combined benefit of anti-angiogenic and cytotoxic dose enhancement effects.
Abstract: Gold nanoparticles (GNPs) are a promising radiosensitizer agent in radiotherapy. Through a simulation performed with the Geant4 Monte Carlo code, we evaluated the dose enhancement effect of GNPs during therapies with an x-ray tube operating at 150 kV (E = 55 keV and E(max) = 150 keV) and we studied the impact of GNP diffusion out of the tumour vessels, in terms of antiangiogenic and cytotoxic effects. Firstly, a single x-ray beam was assumed to irradiate a parallelepiped volume of soft tissue, in which a GNP-doped "target" volume was placed at different depths. Average dose enhancement factors (DEF) in presence of GNPs were obtained as a function of the target depth and GNP concentration, uniformly distributed; values ranging between 1.6 for 10 mg Au/g at 0 cm and 7.2 for 200 mg Au/g at 5 cm were determined. Furtherly, a second geometry was adopted, in which a blood capillary vessel (10 μm thick and 10 μm of inner radius) was placed at the centre of a cubic volume of soft tissue; doses and DEFs to the capillary endothelium as well as to the surrounding viable tumour were evaluated, for different models of GNP diffusion. Our results indicate that the radial DEF profiles around the vessel are in close relationship with the radial profiles of GNP concentration assumed, except for at sharp gradients of concentration. DEFs at the endothelium ranged from 1.6 to 6.5, for GNP concentrations in the blood of 10 and 200 mg/ml, respectively. These data can be helpful for the development of new and more specific GNP-based radiosensitizers of potential interest in radiotherapy, exploiting the combined benefit of anti-angiogenic and cytotoxic dose enhancement effects.

30 citations


Journal ArticleDOI
TL;DR: A new MAR method that uses the Laplacian operator to reveal background projection data hidden in regions containing data from metal, which improves image quality and increases the standard of 3D reconstruction images of the teeth and mandible.
Abstract: There is increasing demand in the field of dental and medical radiography for effective metal artifact reduction (MAR) in computed tomography (CT) because artifact caused by metallic objects causes serious image degradation that ob- scures information regarding the teeth and/or other biological structures. This paper presents a new MAR method that uses the Laplacian operator to reveal background projection data hidden in regions containing data from metal. In the proposed method, we attempted to decompose the projection data into two parts: data from metal only (metal data), and background data in the absence of metal. Removing metal data from the projections enables us to perform sparsity-driven reconstruction of the metal component and subsequent removal of the metal artifact. The results of clinical experiments demonstrated that the proposed MAR algorithm improves image quality and increases the standard of 3D reconstruction images of the teeth and mandible.

29 citations


Journal ArticleDOI
Wenxiang Cong1, Haiou Shen1, Guohua Cao1, Hong Liu, Ge Wang1 
TL;DR: A new design of x-ray fluorescence CT imaging system is presented for detecting fuorescence signals of gold nanoparticles in-vivo, multiple spectroscopic detectors are arranged and rotated orthogonal to an excited region of interest so that a localized scan can be acquired with a maximized efficiency.
Abstract: In this paper, we presented a new design of x-ray fluorescence CT imaging system. For detecting fuorescence signals of gold nanoparticles in-vivo, multiple spectroscopic detectors are arranged and rotated orthogonal to an excited region of interest so that a localized scan can be acquired with a maximized efficiency. Excitation filtration was employed to minimize the effects of low-energy x-rays and background scattering for lowering radiation dose to the object. Numerical simulations showed that the radiation dose is less than 300 mGy/second for a complete 30 views tomographic scan; and the sensitivity of 3D fluorescence signal detection is up to 0.2% contrast concentrations of nanoparticles. The x-ray fluorescence computed tomography is an important molecular imaging tool. It can be used directly in samall animal research. It has great translational potential for future clinical applications.

28 citations


Journal ArticleDOI
TL;DR: This paper presents a novel segmentation approach based on wavelet density model (WDM) for a particular interest in the outer surface of anterior wall of maxilla that can achieve 0.25 ± 0.2 mm of surface error from ground truth of bone surface.
Abstract: Recent advances in cone-beam computed tomography (CBCT) have rapidly enabled widepsread applications of dentomaxillofacial imaging and orthodontic practices in the past decades due to its low radiation dose, high spatial resolution, and accessibility. However, low contrast resolution in CBCT image has become its major limitation in building skull models. Intensive hand-segmentation is usually required to reconstruct the skull models. One of the regions affected by this limitation the most is the thin bone images. This paper presents a novel segmentation approach based on wavelet density model (WDM) for a particular interest in the outer surface of anterior wall of maxilla. Nineteen CBCT datasets are used to conduct two experiments. This mode-based segmentation approach is validated and compared with three different segmentation approaches. The results show that the performance of this model-based segmentation approach is better than those of the other approaches. It can achieve 0.25 ± 0.2mm of surface error from ground truth of bone surface.

27 citations


Journal ArticleDOI
TL;DR: It is shown that one can further reduce the number of projections, resulting in a super-sparse scan, for a good quality image reconstruction with the aid of a prior data, and both numerical and experimental results are provided.
Abstract: Computed tomography (CT) is widely used in medicine for diagnostics or for image-guided therapies, and is also popular in industrial applications for nondestructive testing. CT conventionally requires a large number of projections to pro- duce volumetric images of a scanned object, because the conventional image reconstruction algorithm is based on filtered- backprojection. This requirement may result in relatively high radiation dose to the patients in medical CT unless the radiation dose at each view angle is reduced, and can cause expensive scanning time and efforts in industrial CT applications. Sparse- view CT may provide a viable option to address both issues including high radiation dose and expensive scanning efforts. However, image reconstruction from sparsely sampled data in CT is in general very challenging, and much efforts have been made to develop algorithms for such an image reconstruction problem. Image total-variation minimization algorithm inspired by compressive sensing theory has recently been developed, which exploits the sparseness of the image derivative magnitude and can reconstruct images from sparse-view data to a similar quality of the images conventionally reconstructed from many views. In successive CT scans, prior CT image of an object and its projection data may be readily available, and the current CT image may have not much difference from the prior image. Considering the sparseness of such a difference image between the successive scans, image reconstruction of the difference image may be achieved from very sparsely sampled data. In this work, we showed that one can further reduce the number of projections, resulting in a super-sparse scan, for a good quality image reconstruction with the aid of a prior data. Both numerical and experimental results are provided.

26 citations


Journal ArticleDOI
TL;DR: The study motivates the adoption of advanced reconstruction techniques to allow faster scanning, lower dosage, and reduced data size in high-resolution micro-CT.
Abstract: High-resolution micro-CT offers 3D non-destructive imaging but scan times are prohibitively large in many cases. Advancements in image reconstruction offer great reduction in number of views while maintaining reconstruction accuracy; yet filtered back projection remains the de facto standard. An extensive study of few-view reconstruction using compressed-sensing based iterative techniques is carried out. Also, a novel 3D micro-CT phantom is proposed, and used for analyzing reconstruction accuracy. Numerical tests, and studies on real micro-CT data show that if measurement noise in projections is not extremely high, the number of views may be reduced to 1/8^{th} of the typically acquired view numbers. The study motivates the adoption of advanced reconstruction techniques to allow faster scanning, lower dosage, and reduced data size in high-resolution micro-CT.

24 citations


Journal ArticleDOI
TL;DR: An acceleration approach integrating GPU acceleration, empty space skipping and multi-resolution technique is proposed, which significantly improves the performance of iterative reconstruction while maintaining a high image quality, compared to conventional GPU-based approaches.
Abstract: Iterative reconstruction of high-resolution cone-beam CT data is still a difficult task due to the demand for vast amounts of computer cycles and associated memory. In order to improve the performance of iterative algorithms for cone-beam CT reconstruction, an acceleration approach integrating GPU acceleration, empty space skipping and multi-resolution technique is proposed. The approach divides the reconstructed volume into equally sized blocks, and empty blocks are identified by reconstructing an initial low-resolution volume and segmenting it with threshold method. Then all non-empty blocks are packed into a new volume, which is initialized by interpolating the low resolution volume and reconstructed at full resolution using iterative algorithms. Finally these non-empty blocks are rearranged to get the reconstructed high-resolution volume. The whole process is implemented in parallel based on GPU. Since only the voxels in non-empty blocks are calculated, the number of considered voxels is greatly reduced, which translates directly into substantial computation, memory requirements and data transfer savings. The method is evaluated by reconstructing images from simulated projection data of phantom and CT datasets. The results indicate that our approach significantly improves the performance of iterative reconstruction while maintaining a high image quality, compared to conventional GPU-based approaches.

24 citations


Journal ArticleDOI
TL;DR: The 120W-HPS KTP laser as a safe and feasible procedure provids an alternative for the patients with non-muscle invasive bladder cancer, especially for those on anticoagulation therapy.
Abstract: OBJECTIVE:We evaluated the safety and efficacy of 120W potassium–titanyl-phosphate (KTP) laser vaporization on patients with non-muscle invasive bladder cancer compared with standard transurethral resection of bladder tumor (TUR-BT). MATERIALS AND METHODS: One hundred and fifty-eight patients of non-muscle invasive bladder cancer who underwent either 120W potassium–titanyl-phosphate (KTP) laser vaporization (HPS group, n = 74) or transurethral resection of the bladder tumor (TUR-BT group, n = 84) were analyzed respectively. The preoperative, intraoperative and postoperative clinical data were recorded and compared in two groups. RESULTS: All patients were successfully treated with 120W-KTP laser vaporization or TUR-BT. No significant differences were observed in operative time, perioperative and postoperative serum sodium and hemoglobin levels between two groups. Importantly, HPS had less specific side effects of TURBT, such as obturator nerve reflex, postoperative bladder irrigation and catheterization time, which shows statistic difference significantly ( p< 0.05). Recurrence rate was lower in HPS group than those in TUR-BT group. CONCLUSION: The 120W-HPS KTP laser as a safe and feasible procedure provids an alternative for the patients with nonmuscle invasive bladder cancer, especially for those on anticoagulation therapy.

Journal ArticleDOI
TL;DR: Aspiration-sclerotherapy, as well as laparoscopic decortication are effective and safe therapy for symptomatic simple renal cysts, while LaparoscopicDecortication is superior to the cysts in large sizes.
Abstract: Purpose To perform a retrospective study to compare the efficiency, safety and costs using aspiration-sclerotherapy with 95% ethanol vs. laparoscopic decortications in management of symptomatic simple renal cysts. Materials and methods Patients with simple renal cysts (diamante > 4 cm) were recruited from our hospital between October 2008 and October 2012. A total of 986 patients (Group 1) underwent aspiration-sclerotherapy with 95% ethanol and 208 patients (Group 2) underwent laparoscopic decortication. All patients were followed up with ultrasonography or computerized tomography (CT) for one year. Regression rates, recurrence rates and costs were compared. Results Similarity in symptoms (back pain, cloudy urine or mass in abdomen), renal cyst size, and cyst distribution, complete regression rate after treatment between the two groups; A higher recurrence rate, but shorter procedure times and lower cost in Group 1 compared to Group 2. The procedures used for both groups were safe and had minimum complications. Conclusion Aspiration-sclerotherapy, as well as laparoscopic decortication are effective and safe therapy for symptomatic simple renal cysts. Aspiration-sclerotherapy is more suitable for medium size of renal cysts, while Laparoscopic decortication is superior to the cysts in large sizes.

Journal ArticleDOI
TL;DR: In this paper, a dynamic bowtie is proposed to shape an x-ray beam and equalize its flux reaching different detector channels for spectral CT with energy discriminating photon counting (EDPC) detectors.
Abstract: A bowtie is a filter used to shape an x-ray beam and equalize its flux reaching different detector channels. For development of spectral CT with energy discriminating photon-counting (EDPC) detectors, here we propose and evaluate a dynamic bowtie for performance optimization based on a patient model or a scout scan. With a mechanical rotation of a dynamic bowtie and an adaptive adjustment of an x-ray source flux, an x-ray beam intensity profile can be modulated. First, a mathematical model for dynamic bowtie filtering is established for an elliptical section in fan-beam geometry, and the contour of the optimal bowtie is derived. Then, numerical simulation is performed to compare the performance of the dynamic bowtie in the cases of an ideal phantom and a realistic cross-section relative to the counterparts without any bowtie and with a fixed bowtie respectively. Our dynamic bowtie can equalize the expected numbers of photons in the case of an ideal phantom. In practical cases, our dynamic bowtie can effectively reduce the dynamic range of detected signals inside the field of view. Although our design is optimized for an elliptical phantom, the resultant dynamic bowtie can be applied to a real fan-beam scan if the underlying cross-section can be approximated as an ellipse. Furthermore, our design methodology can be applied to specify an optimized dynamic bowtie for any cross-section of a patient, preferably using rapid prototyping technology.

Journal ArticleDOI
TL;DR: The results show that the spectral CT has a good energy-discriminative performance and provides more attenuation information than the conventional CT.
Abstract: Experiments were performed to evaluate the energy-discriminative performance of a spectral (multi-energy) micro-CT system. The system, designed by MARS (Medipix All Resolution System) Bio-Imaging Ltd. (Christchurch, New Zealand), employs a photon-counting energy-discriminative detector technology developed by CERN (European Organization for Nuclear Research). We used the K-edge attenuation characteristics of some known materials to calibrate the detector's photon energy discrimination. For tomographic analysis, we used the compressed sensing (CS) based ordered-subset simultaneous algebraic reconstruction techniques (OS-SART) to reconstruct sample images, which is effective to reduce noise and suppress artifacts. Unlike conventional CT, the principal component analysis (PCA) method can be applied to extract and quantify additional attenuation information from a spectral CT dataset. Our results show that the spectral CT has a good energy-discriminative performance and provides more attenuation information than the conventional CT.

Journal ArticleDOI
Hongda Shao1, Baoping Li1, Xiao Zhang1, Zhaoming Xiong1, Yong Liu1, Guangyu Tang1 
TL;DR: The combination of two or three methods significantly improved the diagnostic sensitivity for breast cancer in Chinese women and the area under the Receiver Operating Characteristic curve (AUC) was significantly higher for MRI alone than for either XRM alone or US alone.
Abstract: To compare the respective diagnostic efficiency for breast cancer in Chinese women with x-ray mammography (XRM), ultrasound (US), magnetic resonance imaging (MRI; standard dynamic contrasted-enhanced MRI with diffusion-weighted imaging), and different combinations of these imaging modalities, ninety Chinese women patients with clinically suspected breast cancer underwent prospective breast XRM, US, and MRI. The diagnostic performance of each imaging method and different combinations of methods was compared, with the pathological report serving as the gold standard. In this cohort study 54.4% cases with age of 53.2 ± 7.6 years old were categorized as ACR 3 or 4 tissue density. In the diagnosis of breast cancer, sensitivity and diagnostic accuracy [area under the Receiver Operating Characteristic curve (AUC)] were significantly higher for MRI alone than for either XRM alone or US alone (P< 0.05). Of the misdiagnosed cases on XRM, up to 86.7% cancers were located in dense breasts. US and MRI can play important role in screening young Chinese women. The diagnostic sensitivity was significantly higher for combined MRI+US+XRM (98.2%, χ2=25.9, P< 0.001), MRI+US (94.5%, χ2 53.3, P=0.002) and MRI+XRM (92.9%, χ2 = 41,9, P < 0.001). The combination of two or three methods significantly improved the diagnostic sensitivity for breast cancer in Chinese women. When the results based on different imaging modalities or their combinations are inconsistent, further pathological diagnosis is very important for arriving at a correct diagnosis.

Journal ArticleDOI
TL;DR: Endovascular therapy provides an alternative therapy with satisfactory long-term clinical and imaging results for symptomatic patients with nutcracker syndrome.
Abstract: The nutcracker syndrome is a rare clinic condition associated with severe hematuria and left flank pain due to the entrapment of the left renal vein between the superior mesenteric artery and the aorta. Its diagnostic criteria are not well defined, often causing delayed or misdiagnosis. Although surgical repair has been the standard of care, more recently endovascular stenting of the renal vein has been proposed. We presented six patients (aged 7 to 31 years old; median age, 16.5 years old) with nutcracker syndrome who were endovascularly managed from June 2002 to July 2011. All patients underwent laboratory test and computed tomography (CT) or ultrasound examination before and after endovascular procedures. Self-expandable stents were successfully placed in all cases. The diameter of the left renal vein at aorto-superior mesenteric artery portion significantly increased from 1.88 ± 0.95 mm pre-procedure to 5.24 ± 0.61 mm post-procedure (p< 0.01). Left renal vein pressure significantly decreased from 11.00 ± 4.34 mmHg pre-procedure to 6.00 ± 2.55 mmHg post-procedure (p< 0.01). Severe gross hematuria completely subsided within 2 months to 6 months and left flank pain completely subsided within 7 days to 1 month after treatment. Endovascular therapy provides an alternative therapy with satisfactory long-term clinical and imaging results for symptomatic patients with nutcracker syndrome.

Journal ArticleDOI
TL;DR: A new method is developed, which isolates and reduces artifacts in an intermediate image, based on a numerical optimization that de-emphasizes metal and has a novel constraint for beam hardening and scatter.
Abstract: In aviation security, checked luggage is screened by computed tomography (CT) scanning, followed by automatic target recognition from the CT images. Metal objects in the bags cause image artifacts that degrade object representation, leading to increased false alarms. We develop a new method, which isolates and reduces artifacts in an intermediate image, based on a numerical optimization that de-emphasizes metal and has a novel constraint for beam hardening and scatter. Results on test bags showed excellent artifact reduction, even for multiple metal objects.

Journal ArticleDOI
TL;DR: Streak artifacts of sparsely acquired CBCT were decreased by the proposed method and image blur induced by interpolation was constrained to below other interpolation methods.
Abstract: Cone-beam (CB) computed tomography (CT) is widely used in the field of medical imaging for guidance Inspired by Betram's directional interpolation (BDI) methods, directional sinogram interpolation (DSI) was implemented to generate more CB projections by optimized (iterative) double-orientation estimation in sinogram space and directional interpolation A new CBCT was subsequently reconstructed with the Feldkamp algorithm using both the original and interpolated CB projections The proposed method was evaluated on both phantom and clinical data, and image quality was assessed by correlation ratio (CR) between the interpolated image and a gold standard obtained from full measured projections Additionally, streak artifact reduction and image blur were assessed In a CBCT reconstructed by 40 acquired projections over an arc of 360 degree, streak artifacts dropped 207% and 67% in a thorax phantom, when our method was compared to linear interpolation (LI) and BDI methods Meanwhile, image blur was assessed by a head-and-neck phantom, where image blur of DSI was 201% and 243% less than LI and BDI When our method was compared to LI and DI methods, CR increased by 44% and 31% Streak artifacts of sparsely acquired CBCT were decreased by our method and image blur induced by interpolation was constrained to below other interpolation methods

Journal ArticleDOI
TL;DR: Using a rational combination of different imaging methods can improve the accuracy of diagnosis for traumatic urethral strictures.
Abstract: Urethral injures, pelvic trauma, and certain congential abnormalities in male can often cause urethral strictures and scarring. Adequate and accurate imaging diagnosis of urethral strictures is critial to select a surgical approach. Although urethrography is commonly used in evaluating male urethral injury and strictures, its limitation is that the contrast offers images only at the urethral lumen but not of the periurethral structures. Sonourethrography (SUG) has the ability to define the periurethral tissues and without the radiation exposure, the degree of periurethral fibrosis can be shown with a view to guiding surgery especially in bulbar urethra. Computed tomography (CT) urethrography has the advantage of examining patients only in one position, and by generating three-dimensional images; it can accurately measure the stricture length. Magnetic resonance imaging (MRI) provide useful information in certain clinical situations, particularly posterior urethral trauma and in the evaluation of the periurethral soft tissues. However, both CT and MRI are relative high cost. The selection of imaging methods should depend on the etiology, sites, patient's general condition and the type of urethral injury, using a rational combination of different imaging methods can improve the accuracy of diagnosis for traumatic urethral strictures.

Journal ArticleDOI
TL;DR: Surgical exploration ruled out malignancy, extratesticular scrotal mass with affected testicle was removed and orchiectomy should be performed when contralateral testicle is normal and the affected testicular appeared significantly atrophy.
Abstract: Splenogonadal fusion is a rare congenital anomaly where the spleen is attached to either testicular or ovarian tissues. In present case, splenogonadal fusion presents as a large mass consciously connected to atrophic testis in left scrotum. The diagnosis of splenic gonadal fusion relies on radiologic and pathologic findings. Uniform density and vessels connection originating from splenic hilum between principle spleen and let testicle were observed with ultrasound and X-ray computed tomography (CT). Surgical exploration ruled out malignancy, extratesticular scrotal mass with affected testicle was removed. Pathologic examination demonstrated that ectopic spleen tissue and ipsilateral atrophic testis. Our data suggested that orchiectomy should be performed when contralateral testicle is normal and the affected testicular appeared significantly atrophy.

Journal ArticleDOI
TL;DR: Digital subtraction angiography combined with the OFM is a feasible parametric method for intracranial blood flow measurements in patients with moderate to severe carotid stenosis.
Abstract: OBJECTIVE We analyzed intracranial regional blood flows using an optical flow method (OFM) and digital subtraction angiography in patients with internal carotid artery (ICA) stenosis. We also retrospectively explored the correlation between the patients' diagnoses and the severity of the ICA stenoses. MATERIALS AND METHODS OFM, an image-processing algorithm to estimate motion, was applied to determine the mean velocity V(mean) in the vessels. A group of 40 patients without vascular anomalies acted as the control group. The patients were classified as having either moderate stenosis ( 80%, n=23). RESULTS The V(mean) of the ICAs was significantly lower in the stenotic group compared with the control group (p< 0.01). The V(mean) of the ICAs was inversely correlated with the severity of the stenosis (p< 0.05). The receiver operating characteristic curve of the V(mean) in an AP view showed substantial discriminatory power, with an optimal cutoff value of 3.48 pixels/frame for the detection of patients with carotid stenosis. The sensitivity and specificity were 84% and 50%, respectively. On a lateral view, the best cutoff for the V(mean) was 4.01 pixels/frame, and the sensitivity and specificity were 92% and 43%, respectively. CONCLUSIONS Digital subtraction angiography combined with the OFM is a feasible parametric method for intracranial blood flow measurements in patients with moderate to severe carotid stenosis.

Journal ArticleDOI
TL;DR: It is recommended that ejaculatory duct diameter of > 2 mm can be used as a diagnostic criterion with MRI image analyses for ejaculatoryduct dilation with respect to surgical planning of minimally invasive procedures treating prostate cancer.
Abstract: This study aims to analyze magnetic resonance imaging (MRI) features of ejaculatory duct obstruction, and to provide an accurate diagnostic imaging approach for surgical planning of minimally invasive procedures treating ejaculatory duct obstruction. A total of 18 men with ejaculatory duct obstruction were enrolled in the study. The patients were admitted to our hospital and had undergone MRI examination and surgical treatment from January 2003 to February 2011. The data was collected by searching keywords ('ejaculatory duct obstruction') from our PACS. Patients suspected having ejaculatory duct obstruction according to the manifestations through MRI examinations and further being confirmed by surgery were included. The MRI features of ejaculatory duct obstruction in these patients were summarized. Five cases with ejaculatory duct cysts were detected by MRI, ranging in size from 4 mm × 4 mm × 7 mm to 4 mm × 4 mm × 9 mm and located in the paramedian line; ejaculatory duct dilation near the median line, with the internal diameter ranging from 5 mm to 30 mm was detected in nine cases; and among thirteen cases who underwent both non-contrast enhanced and contrast enhanced MRI scanning, significant enhancement of the wall of the ejaculatory duct on enhanced scanning was observed in three cases. Mullerian duct cysts complicated with dilation of the ejaculatory duct and seminal vesicles were detected in four cases; in these cases, the cysts were located in the median line, ranging in size from 4 mm × 5 mm × 6 mm to 34 mm × 35 mm × 44 mm, tear-drop appearance, with the tip pointing toward the area of the seminal colliculus. Findings of MRI were confirmed by the observations during the surgery. MRI is more accurate at displaying the ejaculatory duct. We recommend that ejaculatory duct diameter of > 2 mm can be used as a diagnostic criterion with MRI image analyses for ejaculatory duct dilation.

Journal ArticleDOI
TL;DR: The proposed method significantly reduces the radiation dose and scanning time to achieve the high quality images compared to the 4D CBCT imaging based on the conventional FDK technique and the existing CS techniques.
Abstract: In four-dimensional (4D) cone-beam computed tomography (CBCT), there is a spatio-temporal tradeoff that currently limits the accuracy. The aim of this study is to develop a Bregman iteration based formalism for high quality 4D CBCT image reconstruction from a limited number of low-dose projections. The 4D CBCT problem is first divided into multiple 3D CBCT subproblems by grouping the projection images corresponding to the phases. To maximally utilize the information from the under-sampled projection data, a compressed sensing (CS) method with Bregman iterations is employed for solving each subproblem. We formulate an unconstrained optimization problem based on least-square criterion regularized by total-variation. The least-square criterion reflects the inconsistency between the measured and the estimated line integrals. Furthermore, the unconstrained problem is updated and solved repeatedly by Bregman iterations. The performance of the proposed algorithm is demonstrated through a series of simulation studies and phantom experiments, and the results are compared to those of previously implemented compressed sensing technique using other gradient-based methods as well as conventional filtered back-projection (FBP) results. The simulation and experimental studies have shown that artifact suppressed images can be obtained with as small as 41 projections per phase, which is adequate for clinical 4D CBCT reconstruction. With such small number of projections, the conventional FDK failed to yield meaningful 4D CBCT images, and CS technique using conjugate gradient was not able to recover sharp edges. The proposed method significantly reduces the radiation dose and scanning time to achieve the high quality images compared to the 4D CBCT imaging based on the conventional FDK technique and the existing CS techniques.

Journal ArticleDOI
Gui-Bing Chen1, Hua Wu1, Xiaojiang He1, Jinxiong Huang1, Dan Yu1, Wei-Yi Xu1, Hao Yu1 
TL;DR: It is demonstrated that adenosine stress myocardial perfusion imaging is a safe and reliable diagnostic method for an early stage of CAD and may provide a feasible alternative pharmacological stress method in myocardIAL SPECT for detection of CAD.
Abstract: The aims of this study were to evaluate the diagnostic value of adenosine thallium-201 myocardial perfusion imaging and to compare it with exercise stress thallium-201 myocardial perfusion imaging for detecting coronary artery disease (CAD) at an early stage. Forty-one patients suspected with CAD were randomly divided into two groups. In Group 1 (n=21) adenosine stress was undertaken; the exercise stress myocardial perfusion imaging was performed in Group 2 (n=20). Coronary angiography (CAG) was performed in each patient within 2 weeks before or after single photon emission computed tomography (SPECT). Adenosine stress group vs. exercise stress group, the sensitivity was 92.86% vs. 100.0%, specificity 57.14% vs. 60.0%, positive predictive value 81.25% vs. 71.43%, negative predictive value 80.0% vs. 100.0%, accuracy 80.95% vs. 80.0% respectively. Detection rates of vessels of coronary artery lesions were 66.67% in Group 1 and 72.22% in Group 2 (P> 0.05). The side effects were mild and transient. Our results demonstrated that adenosine stress myocardial perfusion imaging is a safe and reliable diagnostic method for an early stage of CAD. As a comparative sensitivity and accuracy with exercise stress thallium-201 myocardial perfusion imaging, adenosine stress testing may provide a feasible alternative pharmacological stress method in myocardial SPECT for detection of CAD.

Journal Article
TL;DR: In enrolled patients, the confocal microscopy identified multiple small intracellular hyper-reflective dots in the cytoplasm of corneal epithelial cells and stromal keratocytes, which suggests that in vivo confocal laser scanning microscopy provides a rapid, non-invasive, and high resolution scheme for diagnosing MK.
Abstract: As a rare cause of microbial keratitis, microsporidial keratitis (MK) is first described in a patient with acquired immunodeficiency syndrome. As increased use of topical steroid creates a localized immunosuppressive environment of the eyes, MK occurs more commonly than expected in immunocompetent patients nowadays. Owing to initial insidious growth of pathogens and nonspecific ocular symptoms of infected patients, its frequent misdiagnosis has posed a major clinical challenge in recent decades. Without appropriate treatments, MK can progress deeply into corneal stroma, anterior and posterior segments, subsequently deteriorating vision severely and ultimately requiring corneal transplant. Related risk factors for the occurrence of MK in immunocompetent individuals include contact lens wear, topical steroid use, previous corneal trauma, and a history of laser refractive surgery. The conventional standard of MK diagnosis is based on a tissue biopsy by superficial corneal scrapping. In vivo confocal laser scanning microscopy can obtain images through the cornea in a plane paralleling to the vertical axis. This approach provides an effective method of identifying tissue layers that correspond to corneal histologic structures. This current study investigates the efficacy of \textit{in vivo} confocal laser scanning microscopy in diagnosing MK in immunocompetent patients. The clinical presentations of enrolled patients, including features of slit lamp biomicroscopy and the histopathological results of corneal scrapping, were described. In these patients, the confocal microscopy identified multiple small intracellular hyper-reflective dots in the cytoplasm of corneal epithelial cells and stromal keratocytes. Additionally, the confocal microscopic images clearly revealed the enhanced cytoplasm of cell with intracellular round hyper-reflective dots. The size and morphology of hyper-reflective dots were compatible with the spores of microsporidia found in corneal tissue. Moreover, vision recovered after topical use of antimicrobial medicine. This observation suggests that in vivo confocal laser scanning microscopy provides a rapid, non-invasive, and high resolution scheme for diagnosing MK. In addition to diminishing the risk of secondary infection from epithelial defect created by superficial debridement, this approach facilitates early diagnosis and appropriate treatments. Furthermore, from a series of images taken during the clinical courses, this method is highly promising for use in monitoring treatment effects and identifying the recurrence of MK.

Journal ArticleDOI
Ying Long Sa1, Yue Min Xu1, Chao Feng1, Xu Xiao Ye1, Lu Jie Song1 
TL;DR: Three-dimensional spiral computed tomography/cysto-urethrography was more accurate, safer and provided more details of URFs and urethral defects than conventional urethrographY in patients with posterior Urethral strictures associated with U RFs.
Abstract: To evaluate the value of three-dimensional spiral computed tomography/cysto-urethrography (CTCUG) in diagnosing posterior urethral strictures associated with urethrorectal fistulas (URF). Between June 2008 and March 2012, 38 patients with posterior urethral strictures associated with URFs were examined by CTCUG, retrograde urethrography (RUG) and cysto-urethrography (CUG). Urethral reconstruction was undertaken and URFs were surgically repaired in all patients. The length of the urethral defect, location and size of URFs were recorded. Data from radiological examinations were compared with surgical findings. No statistically significant difference was found in the length of stricture measured using CTCUG (4.31 ± 2.28 cm) or conventional urethrography (4.02 ± 3.12 cm; p > 0.05), However, the accuracy in determining the location of the stricture was higher with CTCUG (93.12%) than with conventional urethrography (70.59%; p < 0.05). CTCUG identified URFs in all 38 patients (100%), whereas URFs were only observed in 27 patients (71%) using conventional urethrography. In conclusion, CTCUG was more accurate, safer and provided more details of URFs and urethral defects than conventional urethrography in patients with posterior urethral strictures associated with URFs.

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TL;DR: Endoscopic management is recommended to minimize morbidity and complications in treatment of ureteral fibroepithelial polyps that prolapse into the bladder.
Abstract: Objective Fibroepithelial polyps of ureter prolapsing into the bladder are a rare urological condition. We report the imaging findings and our experience with endoscopic treatment for ureteral fibroepithelial polyps prolapsing into the bladder. Patients and results Four patients with frank pain and hematuria were enrolled. Intravenous urography and computed tomography revealed a ureteral mass with filling defects in affected ureter and mild hydronephrosis. Endoscopic examination showed ureteral polyps prolapsing in the bladder. The histopathologic diagnosis on 4 cases was benign fibroepithelial polyps of ureter. The largest polyps (from 4-10 cm in length) were successfully resected and vaporized by Holmium: YAG laser. A double-pigtail ureteral stent at 7F was placed and left for 6 weeks after the procedure. Neither recurrence nor ureter stricture was observed after up to 12 years of follow-up. Conclusions Ureteral malignancy must be excluded in cases where a ureteral mass is detected. Endoscopic management is recommended to minimize morbidity and complications in treatment of ureteral fibroepithelial polyps that prolapse into the bladder.

Journal ArticleDOI
TL;DR: Bipolar plasma kinetic resection of ejaculatory duct appears to represent a promising endoscopic treatment alternative for ejaculatoryduct obstruction patients, with high efficacy, less complications, quicker recovery and satisfactory follow-up parameters.
Abstract: To evaluate the efficacy of transurethral bipolar plasma kinetic resection of ejaculatory duct for ejaculatory duct obstruction. The clinical information of 42 cases of ejaculatory duct obstruction was analyzed between July 2008 and June 2012. The diagnostic criteria included semen analysis, fructose and neutral α-glucosidase measurement in seminal plasma, transrectal ultrasonography, magnetic resonance imaging and vasography necessarily. Endoscopic procedure with bipolar plasma kinetic resection of ejaculatory duct was performed in all patients. Among these cases followed up 6 ≈ 24 months after operation, 38 patients (90.5%) had improved semen parameters, 23 azoospermic patients (60.5%) had sperm in the semen and 13 patients' wife (31%) achieved pregnancies in 42 cases of bipolar plasma kinetic resection of ejaculatory duct. Postoperative complications ensued as epididymitis in 1 case, watery ejaculate in 1, but no serious complication was observed. Bipolar plasma kinetic resection of ejaculatory duct appears to represent a promising endoscopic treatment alternative for ejaculatory duct obstruction patients, with high efficacy, less complications, quicker recovery and satisfactory follow-up parameters.

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TL;DR: An algorithm to reconstruct discrete (limited gray scale) images decomposed into individual tissue types from a small number of projections acquired over a limited view angle is developed.
Abstract: Relatively high radiation CT techniques are being widely used in diagnostic imaging raising the concerns about cancer risk especially for routine screening of asymptomatic populations. An important strategy for dose reduction is to reduce the number of projections, although doing so with high image quality is technically difficult. We developed an algorithm to reconstruct discrete (limited gray scale) images decomposed into individual tissue types from a small number of projections acquired over a limited view angle. The algorithm was tested using projection simulations from segmented CT scans of different cross sections including mid femur, distal femur and lower leg. It can provide high quality images from as low as 5-7 projections if the skin boundary of the cross section is used as prior information in the reconstruction process, and from 11-13 projections if the skin boundary is unknown.

Journal ArticleDOI
TL;DR: An optimized sequence chart was proposed by extending the rotation angle span to ensure the effective 2π-span projections were situated in the stable rotation stage and structure similarity (SSIM) index was used as a control parameter for extraction of the effective projection sequence which was exactly the complete projection data for image reconstruction.
Abstract: Fast-continuous-rotation is an effective measure to improve the scanning speed and decrease the radiation dose for cone-beam CT. However, because of acceleration and deceleration of the motor, as well as the response lag of the scanning control terminals to the host PC, uneven-distributed and redundant projections are inevitably created, which seriously decrease the quality of the reconstruction images. In this paper, we first analyzed the aspects of the theoretical sequence chart of the fastcontinuous- rotation mode. Then, an optimized sequence chart was proposed by extending the rotation angle span to ensure the effective 2 pi-span projections were situated in the stable rotation stage. In order to match the rotation angle with the projection image accurately, structure similarity (SSIM) index was used as a control parameter for extraction of the effective projection sequence which was exactly the complete projection data for image reconstruction. The experimental results showed that SSIM based method had a high accuracy of projection view locating and was easy to realize.