Publications by authors named "Xiongbiao Luo"

36 Publications

DDA-Net: Unsupervised cross-modality medical image segmentation via dual domain adaptation.

Comput Methods Programs Biomed 2022 Jan 14;213:106531. Epub 2021 Nov 14.

Fujian Key Laboratory of Sensing and Computing for Smart Cities, Department of Computer Science, School of Informatics, Xiamen University, Xiamen 361005, China. Electronic address:

Background And Objective: Deep convolutional networks are powerful tools for single-modality medical image segmentation, whereas generally require semantic labelling or annotation that is laborious and time-consuming. However, domain shift among various modalities critically deteriorates the performance of deep convolutional networks if only trained by single-modality labelling data.

Methods: In this paper, we propose an end-to-end unsupervised cross-modality segmentation network, DDA-Net, for accurate medical image segmentation without semantic annotation or labelling on the target domain. To close the domain gap, different images with domain shift are mapped into a shared domain-invariant representation space. In addition, spatial position information, which benefits the spatial structure consistency for semantic information, is preserved by an introduced cross-modality auto-encoder.

Results: We validated the proposed DDA-Net method on cross-modality medical image datasets of brain images and heart images. The experimental results show that DDA-Net effectively alleviates domain shift and suppresses model degradation.

Conclusions: The proposed DDA-Net successfully closes the domain gap between different modalities of medical image, and achieves state-of-the-art performance in cross-modality medical image segmentation. It also can be generalized for other semi-supervised or unsupervised segmentation tasks in some other field.
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http://dx.doi.org/10.1016/j.cmpb.2021.106531DOI Listing
January 2022

Reamed versus unreamed intramedullary nailing for the treatment of femoral shaft fractures among adults: A meta-analysis of randomized controlled trials.

J Orthop Sci 2021 Jul 21. Epub 2021 Jul 21.

Xiamen University, Xiamen, Fujian, China.

Background: The purpose of this meta-analysis is to compare the merits and drawbacks between reamed intramedullary nailing (RIN) and unreamed intramedullary nailing (URIN) among adults.

Methods: We comprehensively searched PubMed, MEDLINE database through the PubMed search engine, Google Scholar, Cochrane Library, Embase, VIPI (Database for Chinese Technical Periodicals), and CNKI (China National Knowledge Infrastructure) from inception to March 2020. Outcomes of interest included nonunion rates, implant failure rates, secondary procedure rates, blood loss, acute respiratory distress syndrome (ARDS) rates, and pulmonary complications rates.

Results: Eight randomized controlled trials were included. The result of nonunion rates shows that the nonunion rate is significantly lower in the RIN group (RR = 0.20, 95% CI = 0.09-0.48, Z = 3.63, P = 0.0003). There were no significant differences for the risk of implant failure rates (RR = 0.55, 95% CI = 0.18-1.69, Z = 1.04, P = 0.30). The secondary procedure rates were significantly lower in the RIN group (RR = 0.28, 95% CI = 0.12-0.66, Z = 2.91, P = 0.004). The result shows that the blood loss of URIN group is significantly lower (RR = 145.52, 95% CI = 39.68-251.36, Z = 2.69, P = 0.007). The result shows that there was no significant difference in the ARDS rates (RR = 1.53, 95% CI = 0.37-6.29, Z = 0.59, P = 0.55) and the pulmonary complications rates between RIN group and URIN group (RR = 1.59, 95% CI = 0.61-4.17, Z = 0.94, P = 0.35).

Conclusions: Reamed intramedullary nailing would lead to lower nonunion rate, secondary procedure rate and more blood loss. Unreamed intramedullary nailing is related to a higher nonunion rate, secondary procedure rate and less blood loss. No significant difference is found in implant failure rate, ARDS rate and pulmonary complication rate between the two groups.
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http://dx.doi.org/10.1016/j.jos.2021.03.022DOI Listing
July 2021

A deep learning model for detection and tracking in high-throughput images of organoid.

Comput Biol Med 2021 07 25;134:104490. Epub 2021 May 25.

Fujian Key Laboratory of Sensing and Computing for Smart City, School of Informatics, Xiamen University, Xiamen, 361005, China. Electronic address:

Organoid, an in vitro 3D culture, has extremely high similarity with its source organ or tissue, which creates a model in vitro that simulates the in vivo environment. Organoids have been extensively studied in cell biology, precision medicine, drug toxicity, efficacy tests, etc., which have been proven to have high research value. Periodic observation of organoids in microscopic images to obtain morphological or growth characteristics is essential for organoid research. It is difficult and time-consuming to perform manual screens for organoids, but there is no better solution in the prior art. In this paper, we established the first high-throughput organoid image dataset for organoids detection and tracking, which experienced experts annotate in detail. Moreover, we propose a novel deep neural network (DNN) that effectively detects organoids and dynamically tracks them throughout the entire culture. We divided our solution into two steps: First, the high-throughput sequential images are processed frame by frame to detect all organoids; Second, the similarities of the organoids in the adjacent frames are computed, and the organoids on the adjacent frames are matched in pairs. With the help of our proposed dataset, our model achieves organoids detection and tracking with fast speed and high accuracy, effectively reducing the burden on researchers. To our knowledge, this is the first exploration of applying deep learning to organoid tracking tasks. Experiments have demonstrated that our proposed method achieved satisfactory results on organoid detection and tracking, verifying the great potential of deep learning technology in this field.
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http://dx.doi.org/10.1016/j.compbiomed.2021.104490DOI Listing
July 2021

ApodNet: Learning for High Frame Rate Synthetic Transmit Aperture Ultrasound Imaging.

IEEE Trans Med Imaging 2021 11 27;40(11):3190-3204. Epub 2021 Oct 27.

Two-way dynamic focusing in synthetic transmit aperture (STA) beamforming can benefit high-quality ultrasound imaging with higher lateral spatial resolution and contrast resolution. However, STA requires the complete dataset for beamforming in a relatively low frame rate and transmit power. This paper proposes a deep-learning architecture to achieve high frame rate STA imaging with two-way dynamic focusing. The network consists of an encoder and a joint decoder. The encoder trains a set of binary weights as the apodizations of the high-frame-rate plane wave transmissions. In this respect, we term our network ApodNet. The decoder can recover the complete dataset from the acquired channel data to achieve dynamic transmit focusing. We evaluate the proposed method by simulations at different levels of noise and in-vivo experiments on the human biceps brachii and common carotid artery. The experimental results demonstrate that ApodNet provides a promising strategy for high frame rate STA imaging, obtaining comparable lateral resolution and contrast resolution with four-times higher frame rate than conventional STA imaging in the in-vivo experiments. Particularly, ApodNet improves contrast resolution of the hypoechoic targets with much shorter computational time when compared with other high-frame-rate methods in both simulations and in-vivo experiments.
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http://dx.doi.org/10.1109/TMI.2021.3084821DOI Listing
November 2021

Comparison of treatment results between surgical and conservative treatment of distal radius fractures in adults: A meta-analysis of randomized controlled trials.

Acta Orthop Traumatol Turc 2021 Mar;55(2):118-126

Xiamen University, Xiamen, Fujian, China.

Objective: This meta-analysis study aims to determine the efficacy and safety of surgical and conservative treatments for distal radius fractures (DRFs) in adults.

Methods: Reports of randomized controlled trials were retrieved from the Web of Science, Pubmed, Google Scholar, EMBASE, Cochrane Library, Medline, Ovid, and BIOSIS for studies that met the eligibility criteria. The search was limited to human subjects and had no language limits. The search strategy was check by two independent reviewers. If there was any dispute, a third reviewer was consulted. Primary outcomes were: (1) the active wrist range of motion including flexion, extension, pronation, supination, radial, and ulnar deviation; (2) the Disabilities of the Arm, Shoulder, and Hand (DASH) score; and (3) radiological outcomes including radial inclination and ulnar variance. Secondary outcomes were the number of complications including non-infectious and infectious. Quality assessment was performed using the Cochrane Risk of Bias Tool provided by the Cochrane Review Manager 5.3.

Results: A total of 10 randomized controlled trials were included. The meta-analysis detected no statistically significant difference in pooled data for complications not included infection (MD 0.64, CI: 0.33 to 1.23, Z=1.34, p=0.18). Surgical treatment achieved a better range of motion (MD 3.76, CI: 1.58 to 5.95, Z=3.37, p=0.0007), DASH score (MD -6.57, CI: -9.08 to -4.06, Z=5.12, p<0.00001), and radiographic outcomes (MD 3.75, CI: 2.75 to 4.74, Z=7.37, p<0.00001) compared with conservative treatment. In contrast, the conservative treatment achieved less infection rate compared with surgical treatment (MD 4.09, CI: 1.18 to 14.21, Z=2.21, p=0.03).

Conclusion: Findings of this study reveal that when compared with conservative treatment, surgical treatment can ensure better clinical and radiological results for the treatment of DRFs in adults. Although similar complication rates can be encountered with both treatment modalities, it should be taken into account that the rate of infection may be higher in surgical treatment.

Level Of Evidence: Level I, Therapeutic Study.
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http://dx.doi.org/10.5152/j.aott.2021.20168DOI Listing
March 2021

Diagnostic value of bronchoalveolar lavage fluid cryptococcal antigen-lateral flow immunochromatographic assay for pulmonary cryptococcosis in non-HIV patients.

Diagn Microbiol Infect Dis 2021 Mar 26;99(3):115276. Epub 2020 Nov 26.

Department of Computer Science, Xiamen University, Xiamen, Fujian, China.

Background: The aim of this study was to investigate the diagnostic value of cryptococcal antigen-lateral flow immunochromatographic assay (CrAg-LFA) in bronchoalveolar lavage fluid (BALF) of patients with pulmonary cryptococcosis (PC).

Methods: A total of 308 patients were divided into the PC group (n = 72) and the non-PC group (n = 236). The clinical data, pathogen detection, radiological imaging, and the detection of the cryptococcal antigen in blood and BALF samples were analyzed.

Results: The sensitivity, specificity, positive, and negative predicted values of CrAg-LFA in the serum were 75.0%, 99.6%, 98.2%, and 92.9%, respectively, while those in the BALF were 93.1%, 100.0%, 100.0%, and 97.9%, respectively. The sensitivity of the CrAg-LFA in BALF was significantly higher than that in the serum of the patients in the PC group (P < 0.05).

Conclusion: CrAg-LFA has a higher diagnostic value for PC when analyzing BALF samples compared to serum samples.
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http://dx.doi.org/10.1016/j.diagmicrobio.2020.115276DOI Listing
March 2021

D-Dimer Combined with Fibrinogen Predicts the Risk of Venous Thrombosis in Fracture Patients.

Emerg Med Int 2020 23;2020:1930405. Epub 2020 Sep 23.

Department of Orthopedic Surgery, Fuzhou Second Hospital Affiliated to Xiamen University, The Teaching Hospital of Fujian Medical University, Fuzhou, Fujian, China.

Objective: While D-dimer can successfully diagnose venous thrombosis due to its excellent negative predictive value (NPV), it cannot be used to detect venous thromboembolism (VTE) because of its low positive predictive value (PPV). This study aims to investigate if a combination of using D-dimer and fibrinogen can improve PPV in the VTE diagnosis.

Methods: We retrospectively analyzed various data including D-dimer, fibrinogen, C-reactive protein, ultrasound, and others collected from 10775 traumatic fracture patients and categorized them into two groups of VTE and non-VTE. By comparing the difference between the two groups, we employ multiple logistic regression to find risk factors that are useful to detect VTE. The receiver operating characteristic (ROC) curve was used to evaluate the diagnostic yield of using fibrinogen, D-dimer, and their combination, respectively. Also, these data were classified into quartiles by patient age. We perform the same analysis on the quartiles and find if the patient's age has an impact on diagnosing VTE.

Results: The univariate analysis demonstrated that five factors of age, D-dimer, fibrinogen, C-reactive protein, and high-density lipoprotein cholesterol were significant to predict VTE. ROC showed that D-dimer was more useful than fibrinogen for the diagnosis of VTE, while the area under the curve (AUC) was 0.7296 for D-dimer and 0.5209 for fibrinogen. The cutoff point of D-dimer and fibrinogen was 424.89 ng/ml and 3.543 g/L, respectively. The specificity of fibrinogen was 0.777 which was better than D-dimer, while the sensitivity of fibrinogen was lower than that of D-dimer. Both PPV and NPV were similar in D-dimer and fibrinogen. The PPV of combining D-dimer and fibrinogen in ages Q3 (60 < age ≤ 70) and Q4 (age > 70) was better than using either D-dimer or fibrinogen.

Conclusions: Fibrinogen is a promising strategy for the diagnosis of subclinical VTE and postoperative VTE. In particular, a combination of D-dimer and fibrinogen can improve the PPV to successfully diagnose VTE in traumatic fracture patients who are more than 60 years old. . This assay is a diagnostic test at level II.
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http://dx.doi.org/10.1155/2020/1930405DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7530481PMC
September 2020

Optic disc and optic cup segmentation based on anatomy guided cascade network.

Comput Methods Programs Biomed 2020 Dec 27;197:105717. Epub 2020 Aug 27.

Fujian Key Laboratory of Sensing and Computing for Smart Cities, Department of Computer Science, School of Informatics, Xiamen University, Xiamen 361005, China.

Background And Objective: Glaucoma, a worldwide eye disease, may cause irreversible vision damage. If not treated properly at an early stage, glaucoma eventually deteriorates into blindness. Various glaucoma screening methods, e.g. Ultrasound Biomicroscopy (UBM), Optical Coherence Tomography (OCT), and Heidelberg Retinal Scanner (HRT), are available. However, retinal fundus image photography examination, because of its low cost, is one of the most common solutions used to diagnose glaucoma. Clinically, the cup-to-disk ratio is an important indicator in glaucoma diagnosis. Therefore, precise fundus image segmentation to calculate the cup-to-disk ratio is the basis for screening glaucoma.

Methods: In this paper, we propose a deep neural network that uses anatomical knowledge to guide the segmentation of fundus images, which accurately segments the optic cup and the optic disc in a fundus image to accurately calculate the cup-to-disk ratio. Optic disc and optic cup segmentation are typical small target segmentation problems in biomedical images. We propose to use an attention-based cascade network to effectively accelerate the convergence of small target segmentation during training and accurately reserve detailed contours of small targets.

Results: Our method, which was validated in the MICCAI REFUGE fundus image segmentation competition, achieves 93.31% dice score in optic disc segmentation and 88.04% dice score in optic cup segmentation. Moreover, we win a high CDR evaluation score, which is useful for glaucoma screening.

Conclusions: The proposed method successfully introduce anatomical knowledge into segmentation task, and achieve state-of-the-art performance in fundus image segmentation. It also can be used for both automatic segmentation and semiautomatic segmentation with human interaction.
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http://dx.doi.org/10.1016/j.cmpb.2020.105717DOI Listing
December 2020

Automatic and Accurate Epilepsy Ripple and Fast Ripple Detection via Virtual Sample Generation and Attention Neural Networks.

IEEE Trans Neural Syst Rehabil Eng 2020 08 23;28(8):1710-1719. Epub 2020 Jun 23.

About 1% of the population around the world suffers from epilepsy. The success of epilepsy surgery depends critically on pre-operative localization of epileptogenic zones. High frequency oscillations including ripples (80-250 Hz) and fast ripples (250-500 Hz) are commonly used as biomarkers to localize epileptogenic zones. Recent literature demonstrated that fast ripples indicate epileptogenic zones better than ripples. Thus, it is crucial to accurately detect fast ripples from ripples signals of magnetoencephalography for improving outcome of epilepsy surgery. This paper proposes an automatic and accurate ripple and fast ripple detection method that employs virtual sample generation and neural networks with an attention mechanism. We evaluate our proposed detector on patient data with 50 ripples and 50 fast ripples labeled by two experts. The experimental results show that our new detector outperforms multiple traditional machine learning models. In particular, our method can achieve a mean accuracy of 89.3% and an average area under the receiver operating characteristic curve of 0.88 in 50 repeats of random subsampling validation. In addition, we experimentally demonstrate the effectiveness of virtual sample generation, attention mechanism, and architecture of neural network models.
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http://dx.doi.org/10.1109/TNSRE.2020.3004368DOI Listing
August 2020

Correction to: Telmisartan attenuates kidney apoptosis and autophagy-related protein expression levels in an intermittent hypoxia mouse model.

Sleep Breath 2020 09;24(3):1259-1260

Department of Computer Science, Xiamen University, Xiamen, Fujian, China.

In the article that appeared on Page: 341-348, Vol 23 (15 September 2018) of the Sleep and breathing [1], one error was discovered in Figure 3. The picture of Normoxia and CIH in 100X is the same one. The corrected version of Figure 3 is presented here.
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http://dx.doi.org/10.1007/s11325-020-02136-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7645563PMC
September 2020

Sodium Tanshinone IIA Sulfonate Attenuates Tumor Oxidative Stress and Promotes Apoptosis in an Intermittent Hypoxia Mouse Model.

Technol Cancer Res Treat 2020 Jan-Dec;19:1533033820928073

Department of Computer Science, Xiamen University, Xiamen, Fujian, People's Republic of China.

Objective: Intermittent hypoxia, a significant feature of obstructive sleep apnea, has pro-tumorigenic effects. Here, we investigated the effect of sodium tanshinone IIA sulfonate on oxidative stress and apoptosis in a mouse model of Lewis lung carcinoma with intermittent hypoxia.

Methods: Mice were randomly assigned to normoxia (control), normoxia plus sodium tanshinone IIA sulfonate (control + sodium tanshinone IIA sulfonate), intermittent hypoxia, and intermittent hypoxia + sodium tanshinone IIA sulfonate groups. Intermittent hypoxia administration lasted 5 weeks in the intermittent hypoxia groups. Lewis lung carcinoma cells were injected into the right flank of each mouse after 1 week of intermittent hypoxia exposure. Sodium tanshinone IIA sulfonate was injected intraperitoneally in the control + sodium tanshinone IIA sulfonate and intermittent hypoxia + sodium tanshinone IIA sulfonate groups. Tumor oxidative stress was evaluated by detection of malondialdehyde and superoxide dismutase. The apoptosis of tumor cells was evaluated by the terminal deoxynucleotidyl transferase dUTP nick-end labeling assay as well as by Western blot analysis of B-cell lymphoma 2-associated X protein and cleaved caspase-3 expression. Additionally, the expression of hypoxia-induced factor-1α, nuclear factor erythroid 2-related factor 2, and nuclear factor kappa B was also evaluated by Western blot.

Results: Compared with the control group, the intermittent hypoxia treatment significantly increased Lewis lung carcinoma tumor growth and oxidative stress (serum malondialdehyde) but decreased serum levels of SOD and pro-apoptotic markers (terminal deoxynucleotidyl transferase dUTP nick-end labeling staining, B-cell lymphoma 2-associated X protein, and cleaved caspase-3). These changes were significantly attenuated by intraperitoneal injection of sodium tanshinone IIA sulfonate. Lower nuclear factor erythroid 2-related factor 2 and higher nuclear factor kappa B levels in the intermittent hypoxia group were clearly reversed by sodium tanshinone IIA sulfonate treatment. In addition, sodium tanshinone IIA sulfonate administration decreased the high expression of hypoxia-induced factor-1α induced by intermittent hypoxia.

Conclusion: Intermittent hypoxia treatment resulted in high oxidative stress and low apoptosis in Lewis lung carcinoma-implanted mice, which could be attenuated by sodium tanshinone IIA sulfonate administration possibly through a mechanism mediated by the nuclear factor erythroid 2-related factor 2/nuclear factor kappa B signaling pathway.
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http://dx.doi.org/10.1177/1533033820928073DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7249596PMC
January 2021

Endoscopic video defogging using luminance blending.

Healthc Technol Lett 2019 Dec 6;6(6):280-285. Epub 2019 Dec 6.

Zhongshan Hospital, Xiamen University, Xiamen 361005, People's Republic of China.

Endoscopic video sequences provide surgeons with direct surgical field or visualisation on anatomical targets in the patient during robotic surgery. Unfortunately, these video images are unavoidably hazy or foggy to prevent surgeons from clear surgical vision due to typical surgical operations such as ablation and cauterisation during surgery. This Letter aims at removing fog or smoke on endoscopic video sequences to enhance and maintain a direct and clear visualisation of the operating field during robotic surgery. The authors propose a new luminance blending framework that integrates contrast enhancement with visibility restoration for foggy endoscopic video processing. The proposed method was validated on clinical endoscopic videos that were collected from robotic surgery. The experimental results demonstrate that their method provides a promising means to effectively remove fog or smoke on endoscopic video images. In particular, the visual quality of defogged endoscopic images was improved from 0.5088 to 0.6475.
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http://dx.doi.org/10.1049/htl.2019.0095DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6952256PMC
December 2019

Endoscopic Vision Augmentation Using Multiscale Bilateral-Weighted Retinex for Robotic Surgery.

IEEE Trans Med Imaging 2019 12 10;38(12):2863-2874. Epub 2019 May 10.

Endoscopic vision plays a significant role in minimally invasive surgical procedures. The visibility and maintenance of such direct in situ vision is paramount not only for safety by preventing inadvertent injury but also to improve precision and reduce operating time. Unfortunately, the endoscopic vision is unavoidably degraded due to the illumination variations during surgery. This paper aims to restore or augment such degraded visualization and quantitatively evaluate it during robotic surgery. A multiscale bilateral-weighted retinex method is proposed to remove non-uniform and highly directional illumination and enhance surgical vision, while an objective no-reference image visibility assessment method is defined in terms of sharpness, naturalness, and contrast, to quantitatively and objectively evaluate the endoscopic visualization on surgical video sequences. The methods were validated on surgical data, with the experimental results showing that our method outperforms existent retinex approaches. In particular, the combined visibility was improved from 0.81 to 1.06, while three surgeons generally agreed that the results were restored with much better visibility.
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http://dx.doi.org/10.1109/TMI.2019.2916101DOI Listing
December 2019

Surgical Navigation in Orthopedics: Workflow and System Review.

Adv Exp Med Biol 2018;1093:47-63

Department of Computer Science, Xiamen University, Xiamen, China.

Orthopedic surgery is a widely performed clinical procedure that deals with problems in relation to the bones, joints, and ligaments of the human body, such as musculoskeletal trauma, spine diseases, sports injuries, degenerative diseases, infections, tumors, and congenital disorders. Surgical navigation is generally recognized as the next generation technology of orthopedic surgery. The development of orthopedic navigation systems aims to analyze pre-, intra- and/or postoperative data in multiple modalities and provide an augmented reality 3-D visualization environment to improve clinical outcomes of surgical orthopedic procedures. This chapter investigates surgical navigation techniques and systems that are currently available in orthopedic procedures. In particular, optical tracking, electromagnetic localizers and stereoscopic vision, as well as commercialized orthopedic navigation systems are thoroughly discussed. Moreover, advances and development trends in orthopedic navigation are also discussed in this chapter. While current orthopedic navigation systems enable surgeons to make precise decisions in the operating room by integrating surgical planning, instrument tracking, and intraoperative imaging, it still remains an active research field which provides orthopedists with various technical disciplines, e.g., medical imaging, computer science, sensor technology, and robotics, to further develop current orthopedic navigation methods and systems.
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http://dx.doi.org/10.1007/978-981-13-1396-7_4DOI Listing
July 2019

Telmisartan attenuates kidney apoptosis and autophagy-related protein expression levels in an intermittent hypoxia mouse model.

Sleep Breath 2019 Mar 15;23(1):341-348. Epub 2018 Sep 15.

Department of Computer Science, Xiamen University, Xiamen, Fujian, China.

Purpose: Obstructive sleep apnea (OSA) is associated with renal impairs. As a novel pathophysiological hallmark of OSA, chronic intermittent hypoxia (CIH) enhances apoptosis and autophagy. The present study aims to evaluate the effect of telmisartan on CIH-induced kidney apoptosis and autophagy in a mouse model of OSA.

Materials And Methods: Mice were randomly allocated to normoxia, CIH, and CIH+telmisartan groups (n = 12 in each group). The CIH exposure duration was 12 weeks. Mice in the CIH+telmisartan group received telmisartan administration. The terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay and western blotting of Bax and cleaved caspase-3 were conducted for evaluating apoptosis in kidney tissue. While the autophagy-related proteins, beclin-1 and LC3, were also observed via western blotting.

Results: The percentage of apoptotic cell in the CIH group was significantly higher than that of normoxia group; meanwhile, Bax and cleaved caspase-3 protein levels were increased in the CIH group than those of normoxia group (all p < 0.05). Compared with the normoxia group, mice in the CIH group had greater autophagy-related proteins (beclin-1 and LC3) expression. When compared to the CIH group, both the renal apoptosis and autophagy in the CIH+telmisartan group were decreased.

Conclusion: The CIH accelerates renal apoptosis and autophagy levels. Telmisartan ameliorating those levels suggests that it might prevent renal impairs from the CIH in OSA patients.
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http://dx.doi.org/10.1007/s11325-018-1720-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6418059PMC
March 2019

Advanced Endoscopic Navigation: Surgical Big Data, Methodology, and Applications.

Annu Rev Biomed Eng 2018 06 5;20:221-251. Epub 2018 Mar 5.

Robarts Research Institute, Western University, London, Ontario N6A 3K7, Canada; email:

Interventional endoscopy (e.g., bronchoscopy, colonoscopy, laparoscopy, cystoscopy) is a widely performed procedure that involves either diagnosis of suspicious lesions or guidance for minimally invasive surgery in a variety of organs within the body cavity. Endoscopy may also be used to guide the introduction of certain items (e.g., stents) into the body. Endoscopic navigation systems seek to integrate big data with multimodal information (e.g., computed tomography, magnetic resonance images, endoscopic video sequences, ultrasound images, external trackers) relative to the patient's anatomy, control the movement of medical endoscopes and surgical tools, and guide the surgeon's actions during endoscopic interventions. Nevertheless, it remains challenging to realize the next generation of context-aware navigated endoscopy. This review presents a broad survey of various aspects of endoscopic navigation, particularly with respect to the development of endoscopic navigation techniques. First, we investigate big data with multimodal information involved in endoscopic navigation. Next, we focus on numerous methodologies used for endoscopic navigation. We then review different endoscopic procedures in clinical applications. Finally, we discuss novel techniques and promising directions for the development of endoscopic navigation.
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http://dx.doi.org/10.1146/annurev-bioeng-062117-120917DOI Listing
June 2018

Three-Dimensional Intravascular Reconstruction Techniques Based on Intravascular Ultrasound: A Technical Review.

IEEE J Biomed Health Inform 2018 05 12;22(3):806-817. Epub 2017 May 12.

Intravascular ultrasound (IVUS) imaging provides two-dimensional (2-D) real-time luminal and transmural cross-sectional images of intravascular vessels with detailed pathological information. It has offered significant advantages in terms of diagnosis and guidance and has been increasingly introduced from coronary interventions into more generalized endovascular surgery. However, IVUS itself does not provide spatial pose information for its generated images, making it difficult to construct a 3-D intravascular visualization. To address this limitation, IVUS imaging-driven 3-D intravascular reconstruction techniques have been developed. These techniques enable accurate diagnosis and quantitative measurements of intravascular diseases to facilitate optimal treatment determination. Such reconstruction extends the IVUS imaging modality from pure diagnostic assistance to intraoperative navigation and guidance and supports both therapeutic options and interventional operations. This paper presents a comprehensive survey of technological advances and recent progress on IVUS imaging-based 3-D intravascular reconstruction and its state-of-the-art applications. Limitations of existing technologies and prospects of new technologies are also discussed.
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http://dx.doi.org/10.1109/JBHI.2017.2703903DOI Listing
May 2018

Vision-Based Surgical Field Defogging.

IEEE Trans Med Imaging 2017 10 11;36(10):2021-2030. Epub 2017 May 11.

Robarts Research Institute, Western University, London, ON, Canada.

Fogged surgical field visualization that is a common and potentially harmful problem can lead to inappropriate device use and incorrectly targeted tissue and increase surgical risks in endoscopic surgery. This paper aims to remove fog or smoke on endoscopic video sequences to augment and maintain a direct and clear visualization of the operating field. A new visibility-driven fusion defogging framework is proposed for surgical endoscopic video processing. This framework first recovers the visibility and enhances the contrast of hazy images. To address the color infidelity problem introduced by the visibility recovery, the luminances of the recovered and enhanced images are fused in the gradient domain, and the fused luminance is reconstructed by solving the Poisson equation in the frequency domain. The proposed method is evaluated on clinical videos that were collected from prostate cancer surgery. The experimental results demonstrate that the proposed framework defogs endoscopic images more robustly than currently available methods. Additionally, our method also provides an effective way to improve the visual quality of medical or high-dynamic range images.
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http://dx.doi.org/10.1109/TMI.2017.2701861DOI Listing
October 2017

Shape Sensing Techniques for Continuum Robots in Minimally Invasive Surgery: A Survey.

IEEE Trans Biomed Eng 2017 08 27;64(8):1665-1678. Epub 2016 Oct 27.

Continuum robots provide inherent structural compliance with high dexterity to access the surgical target sites along tortuous anatomical paths under constrained environments and enable to perform complex and delicate operations through small incisions in minimally invasive surgery. These advantages enable their broad applications with minimal trauma and make challenging clinical procedures possible with miniaturized instrumentation and high curvilinear access capabilities. However, their inherent deformable designs make it difficult to realize 3-D intraoperative real-time shape sensing to accurately model their shape. Solutions to this limitation can lead themselves to further develop closely associated techniques of closed-loop control, path planning, human-robot interaction, and surgical manipulation safety concerns in minimally invasive surgery. Although extensive model-based research that relies on kinematics and mechanics has been performed, accurate shape sensing of continuum robots remains challenging, particularly in cases of unknown and dynamic payloads. This survey investigates the recent advances in alternative emerging techniques for 3-D shape sensing in this field and focuses on the following categories: fiber-optic-sensor-based, electromagnetic-tracking-based, and intraoperative imaging modality-based shape-reconstruction methods. The limitations of existing technologies and prospects of new technologies are also discussed.
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http://dx.doi.org/10.1109/TBME.2016.2622361DOI Listing
August 2017

Towards Personalized Statistical Deformable Model and Hybrid Point Matching for Robust MR-TRUS Registration.

IEEE Trans Med Imaging 2016 Feb 1;35(2):589-604. Epub 2015 Oct 1.

Registration and fusion of magnetic resonance (MR) and 3D transrectal ultrasound (TRUS) images of the prostate gland can provide high-quality guidance for prostate interventions. However, accurate MR-TRUS registration remains a challenging task, due to the great intensity variation between two modalities, the lack of intrinsic fiducials within the prostate, the large gland deformation caused by the TRUS probe insertion, and distinctive biomechanical properties in patients and prostate zones. To address these challenges, a personalized model-to-surface registration approach is proposed in this study. The main contributions of this paper can be threefold. First, a new personalized statistical deformable model (PSDM) is proposed with the finite element analysis and the patient-specific tissue parameters measured from the ultrasound elastography. Second, a hybrid point matching method is developed by introducing the modality independent neighborhood descriptor (MIND) to weight the Euclidean distance between points to establish reliable surface point correspondence. Third, the hybrid point matching is further guided by the PSDM for more physically plausible deformation estimation. Eighteen sets of patient data are included to test the efficacy of the proposed method. The experimental results demonstrate that our approach provides more accurate and robust MR-TRUS registration than state-of-the-art methods do. The averaged target registration error is 1.44 mm, which meets the clinical requirement of 1.9 mm for the accurate tumor volume detection. It can be concluded that the presented method can effectively fuse the heterogeneous image information in the elastography, MR, and TRUS to attain satisfactory image alignment performance.
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http://dx.doi.org/10.1109/TMI.2015.2485299DOI Listing
February 2016

Robust electromagnetically guided endoscopic procedure using enhanced particle swarm optimization for multimodal information fusion.

Med Phys 2015 Apr;42(4):1808-17

School of Computing and Communications, University of Technology, Sydney, New South Wales 2007, Australia.

Purpose: Electromagnetically guided endoscopic procedure, which aims at accurately and robustly localizing the endoscope, involves multimodal sensory information during interventions. However, it still remains challenging in how to integrate these information for precise and stable endoscopic guidance. To tackle such a challenge, this paper proposes a new framework on the basis of an enhanced particle swarm optimization method to effectively fuse these information for accurate and continuous endoscope localization.

Methods: The authors use the particle swarm optimization method, which is one of stochastic evolutionary computation algorithms, to effectively fuse the multimodal information including preoperative information (i.e., computed tomography images) as a frame of reference, endoscopic camera videos, and positional sensor measurements (i.e., electromagnetic sensor outputs). Since the evolutionary computation method usually limits its possible premature convergence and evolutionary factors, the authors introduce the current (endoscopic camera and electromagnetic sensor's) observation to boost the particle swarm optimization and also adaptively update evolutionary parameters in accordance with spatial constraints and the current observation, resulting in advantageous performance in the enhanced algorithm.

Results: The experimental results demonstrate that the authors' proposed method provides a more accurate and robust endoscopic guidance framework than state-of-the-art methods. The average guidance accuracy of the authors' framework was about 3.0 mm and 5.6° while the previous methods show at least 3.9 mm and 7.0°. The average position and orientation smoothness of their method was 1.0 mm and 1.6°, which is significantly better than the other methods at least with (2.0 mm and 2.6°). Additionally, the average visual quality of the endoscopic guidance was improved to 0.29.

Conclusions: A robust electromagnetically guided endoscopy framework was proposed on the basis of an enhanced particle swarm optimization method with using the current observation information and adaptive evolutionary factors. The authors proposed framework greatly reduced the guidance errors from (4.3, 7.8) to (3.0 mm, 5.6°), compared to state-of-the-art methods.
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http://dx.doi.org/10.1118/1.4915285DOI Listing
April 2015

Observation-driven adaptive differential evolution and its application to accurate and smooth bronchoscope three-dimensional motion tracking.

Med Image Anal 2015 Aug 17;24(1):282-296. Epub 2015 Jan 17.

Information and Communications Headquarters, Nagoya University, Japan. Electronic address:

This paper proposes an observation-driven adaptive differential evolution algorithm that fuses bronchoscopic video sequences, electromagnetic sensor measurements, and computed tomography images for accurate and smooth bronchoscope three-dimensional motion tracking. Currently an electromagnetic tracker with a position sensor fixed at the bronchoscope tip is commonly used to estimate bronchoscope movements. The large tracking error from directly using sensor measurements, which may be deteriorated heavily by patient respiratory motion and the magnetic field distortion of the tracker, limits clinical applications. How to effectively use sensor measurements for precise and stable bronchoscope electromagnetic tracking remains challenging. We here exploit an observation-driven adaptive differential evolution framework to address such a challenge and boost the tracking accuracy and smoothness. In our framework, two advantageous points are distinguished from other adaptive differential evolution methods: (1) the current observation including sensor measurements and bronchoscopic video images is used in the mutation equation and the fitness computation, respectively and (2) the mutation factor and the crossover rate are determined adaptively on the basis of the current image observation. The experimental results demonstrate that our framework provides much more accurate and smooth bronchoscope tracking than the state-of-the-art methods. Our approach reduces the tracking error from 3.96 to 2.89 mm, improves the tracking smoothness from 4.08 to 1.62 mm, and increases the visual quality from 0.707 to 0.741.
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http://dx.doi.org/10.1016/j.media.2015.01.002DOI Listing
August 2015

Adaptive marker-free registration using a multiple point strategy for real-time and robust endoscope electromagnetic navigation.

Comput Methods Programs Biomed 2015 Feb 23;118(2):147-57. Epub 2014 Dec 23.

Information and Communications Headquarters, Nagoya University, Japan. Electronic address:

Registration of pre-clinical images to physical space is indispensable for computer-assisted endoscopic interventions in operating rooms. Electromagnetically navigated endoscopic interventions are increasingly performed at current diagnoses and treatments. Such interventions use an electromagnetic tracker with a miniature sensor that is usually attached at an endoscope distal tip to real time track endoscope movements in a pre-clinical image space. Spatial alignment between the electromagnetic tracker (or sensor) and pre-clinical images must be performed to navigate the endoscope to target regions. This paper proposes an adaptive marker-free registration method that uses a multiple point selection strategy. This method seeks to address an assumption that the endoscope is operated along the centerline of an intraluminal organ which is easily violated during interventions. We introduce an adaptive strategy that generates multiple points in terms of sensor measurements and endoscope tip center calibration. From these generated points, we adaptively choose the optimal point, which is the closest to its assigned the centerline of the hollow organ, to perform registration. The experimental results demonstrate that our proposed adaptive strategy significantly reduced the target registration error from 5.32 to 2.59 mm in static phantoms validation, as well as from at least 7.58 mm to 4.71 mm in dynamic phantom validation compared to current available methods.
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http://dx.doi.org/10.1016/j.cmpb.2014.11.008DOI Listing
February 2015

Enhanced differential evolution to combine optical mouse sensor with image structural patches for robust endoscopic navigation.

Med Image Comput Comput Assist Interv 2014 ;17(Pt 2):340-8

Endoscopic navigation generally integrates different modalities of sensory information in order to continuously locate an endoscope relative to suspicious tissues in the body during interventions. Current electromagnetic tracking techniques for endoscopic navigation have limited accuracy due to tissue deformation and magnetic field distortion. To avoid these limitations and improve the endoscopic localization accuracy, this paper proposes a new endoscopic navigation framework that uses an optical mouse sensor to measure the endoscope movements along its viewing direction. We then enhance the differential evolution algorithm by modifying its mutation operation. Based on the enhanced differential evolution method, these movement measurements and image structural patches in endoscopic videos are fused to accurately determine the endoscope position. An evaluation on a dynamic phantom demonstrated that our method provides a more accurate navigation framework. Compared to state-of-the-art methods, it improved the navigation accuracy from 2.4 to 1.6 mm and reduced the processing time from 2.8 to 0.9 seconds.
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http://dx.doi.org/10.1007/978-3-319-10470-6_43DOI Listing
January 2015

Real-time bronchoscope three-dimensional motion estimation using multiple sensor-driven alignment of CT images and electromagnetic measurements.

Comput Med Imaging Graph 2014 Sep 23;38(6):540-8. Epub 2014 Jun 23.

Information and Communications Headquarters, Nagoya University, Japan. Electronic address:

Bronchoscope three-dimensional motion estimation plays a key role in developing bronchoscopic navigation systems. Currently external tracking devices, particularly electromagnetic trackers with electromagnetic sensors, are increasingly introduced to navigate surgical tools in pre-clinical images. An unavoidable problem, which is to align the electromagnetic tracker to pre-clinical images, must be solved before navigation. This paper proposes a multiple sensor-driven registration method to establish this alignment without using any anatomical fiducials. Although current fiducially free registration methods work well, they limit to the initialization of optimization and manipulating the bronchoscope along the bronchial centerlines, which could be failed easily during clinical interventions. To address these limitations, we utilize measurements of multiple electromagnetic sensors to calculate bronchoscope geometric center positions that are usually closer to the bronchial centerlines than the sensor itself measured positions. We validated our method on a bronchial phantom. The experimental results demonstrate that our idea of using multiple sensors to determine bronchoscope geometric center positions for fiducial-free registration was very effective. Compared to currently available methods in bronchoscope three-dimensional motion estimation, our method reduced fiducial alignment error from at least 6.79 to 4.68-5.26 mm and significantly improved motion estimation or tracking accuracy from at least 5.42 to 3.78-4.53 mm.
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http://dx.doi.org/10.1016/j.compmedimag.2014.06.013DOI Listing
September 2014

A discriminative structural similarity measure and its application to video-volume registration for endoscope three-dimensional motion tracking.

IEEE Trans Med Imaging 2014 Jun;33(6):1248-61

Endoscope 3-D motion tracking, which seeks to synchronize pre- and intra-operative images in endoscopic interventions, is usually performed as video-volume registration that optimizes the similarity between endoscopic video and pre-operative images. The tracking performance, in turn, depends significantly on whether a similarity measure can successfully characterize the difference between video sequences and volume rendering images driven by pre-operative images. The paper proposes a discriminative structural similarity measure, which uses the degradation of structural information and takes image correlation or structure, luminance, and contrast into consideration, to boost video-volume registration. By applying the proposed similarity measure to endoscope tracking, it was demonstrated to be more accurate and robust than several available similarity measures, e.g., local normalized cross correlation, normalized mutual information, modified mean square error, or normalized sum squared difference. Based on clinical data evaluation, the tracking error was reduced significantly from at least 14.6 mm to 4.5 mm. The processing time was accelerated more than 30 frames per second using graphics processing unit.
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http://dx.doi.org/10.1109/TMI.2014.2307052DOI Listing
June 2014

A bronchoscopic navigation system using bronchoscope center calibration for accurate registration of electromagnetic tracker and CT volume without markers.

Authors:
Xiongbiao Luo

Med Phys 2014 Jun;41(6):061913

Robarts Research Institute, Western University, London, Ontario N6A 5K8, Canada.

Purpose: Various bronchoscopic navigation systems are developed for diagnosis, staging, and treatment of lung and bronchus cancers. To construct electromagnetically navigated bronchoscopy systems, registration of preoperative images and an electromagnetic tracker must be performed. This paper proposes a new marker-free registration method, which uses the centerlines of the bronchial tree and the center of a bronchoscope tip where an electromagnetic sensor is attached, to align preoperative images and electromagnetic tracker systems.

Methods: The chest computed tomography (CT) volume (preoperative images) was segmented to extract the bronchial centerlines. An electromagnetic sensor was fixed at the bronchoscope tip surface. A model was designed and printed using a 3D printer to calibrate the relationship between the fixed sensor and the bronchoscope tip center. For each sensor measurement that includes sensor position and orientation information, its corresponding bronchoscope tip center position was calculated. By minimizing the distance between each bronchoscope tip center position and the bronchial centerlines, the spatial alignment of the electromagnetic tracker system and the CT volume was determined. After obtaining the spatial alignment, an electromagnetic navigation bronchoscopy system was established to real-timely track or locate a bronchoscope inside the bronchial tree during bronchoscopic examinations.

Results: The electromagnetic navigation bronchoscopy system was validated on a dynamic bronchial phantom that can simulate respiratory motion with a breath rate range of 0-10 min(-1). The fiducial and target registration errors of this navigation system were evaluated. The average fiducial registration error was reduced from 8.7 to 6.6 mm. The average target registration error, which indicates all tracked or navigated bronchoscope position accuracy, was much reduced from 6.8 to 4.5 mm compared to previous registration methods.

Conclusions: An electromagnetically navigated bronchoscopy system was constructed with accurate registration of an electromagnetic tracker and the CT volume on the basis of an improved marker-free registration approach that uses the bronchial centerlines and bronchoscope tip center information. The fiducial and target registration errors of our electromagnetic navigation system were about 6.6 and 4.5 mm in dynamic bronchial phantom validation.
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http://dx.doi.org/10.1118/1.4876381DOI Listing
June 2014

Beyond current guided bronchoscopy: a robust and real-time bronchoscopic ultrasound navigation system.

Med Image Comput Comput Assist Interv 2013 ;16(Pt 1):388-95

Information and Communications Headquarters, Nagoya University, Japan.

This paper develops a new bronchoscopic ultrasound navigation system that fuses multimodal sensory information including preoperative images, bronchoscopic video sequences, ultrasound images, and external position sensor measurements. To construct such a system, we must align these information coordinate systems. We use hand-eye calibration to align the video camera and its attached external sensor and introduce a phantom-free method to calibrate the ultrasonic probe and its fixed external sensor. More importantly, we propose a marker-free registration method that uses the bronchoscope and the bronchial tree center information to register the sensor and the pre-operative coordinate systems. We constructed a bronchial phantom to validate our system, whose navigation accuracy was about 2.6 mm. Furthermore, compared to the current navigated bronchoscopy, the main advantage of our system is that it navigates the bronchoscope and the ultrasonic mini probe simultaneously and provides bronchial structures inside and outside the bronchial walls, particularly lymph node structures in ultrasonic images.
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http://dx.doi.org/10.1007/978-3-642-40811-3_49DOI Listing
February 2014

Robust endoscope motion estimation via an animated particle filter for electromagnetically navigated endoscopy.

IEEE Trans Biomed Eng 2014 Jan 7;61(1):85-95. Epub 2013 Aug 7.

Electromagnetically navigated endoscopy, which is increasingly applied in endoscopic interventions, utilizes an electromagnetic sensor attached at the endoscope tip to measure the endoscope movements and to navigate the endoscope in the region of interest in the body. Due to patient motion and magnetic field distortion, sensor electromagnetic tracking (EMT) measurement inaccuracy and dynamic jitter errors remain challenging for electromagnetic navigation. This paper proposes a new tracking framework of an animated particle filter that integrates adaptive particle swarm optimization into a generic particle filter to significantly boost electromagnetic trackers. We validate our method on a dynamic phantom and compare it to state-of-the-art EMT methods. Our experimental results demonstrate the effectiveness and robustness of our method, which provides position and orientation accuracy of 2.48 mm, 4.69° that significantly outperformed previous methods at least with tracking error of 4.19 mm, 7.75°. The tracking smoothness was improved from 4.09 mm, 3.37° to 1.84 mm, 2.52°. Our method successfully tackled the particle impoverishment better than standard particle filters.
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http://dx.doi.org/10.1109/TBME.2013.2277609DOI Listing
January 2014

Externally navigated bronchoscopy using 2-D motion sensors: dynamic phantom validation.

IEEE Trans Med Imaging 2013 Oct 15;32(10):1745-64. Epub 2013 May 15.

The paper presents a new endoscope motion tracking method that is based on a novel external endoscope tracking device and our modified stochastic optimization method for boosting endoscopy navigation. We designed a novel tracking prototype where a 2-D motion sensor was introduced to directly measure the insertion-retreat linear motion and also the rotation of the endoscope. With our developed stochastic optimization method, which embeds traceable particle swarm optimization in the Condensation algorithm, a full six degrees-of-freedom endoscope pose (position and orientation) can be recovered from 2-D motion sensor measurements. Experiments were performed on a dynamic bronchial phantom with maximal simulated respiratory motion around 24.0 mm. The experimental results demonstrate that our proposed method provides a promising endoscope motion tracking approach with more effective and robust performance than several current available tracking techniques. The average tracking accuracy of the position improved from 6.5 to 3.3 mm, which further approaches the clinical requirement of 2.0 mm in practice.
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http://dx.doi.org/10.1109/TMI.2013.2263152DOI Listing
October 2013
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