Simon S M Ho

The Chinese University of Hong Kong, Hong Kong, Hong Kong

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Publications (23)32.88 Total impact

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    ABSTRACT: Both capsule endoscopy (CE) and angiography have been recommended as first investigation for patients with acute overt obscure gastrointestinal bleeding (OGIB). However, no studies have directly compared the two modalities in patients with overt OGIB. We compared the diagnostic yield and long-term outcomes of patients with overt OGIB randomized to CE or angiogram. Consecutive patients presented with acute melena or hematochezia, but nondiagnostic upper and lower endoscopy, were immediately randomized to receive small-bowel CE or angiography. All patients were monitored for rebleeding and anemia for up to 5 years. Primary end point was the diagnostic yield of the assigned investigation. Secondary end points included rebleeding, further transfusion, readmission for bleeding or anemia, and mortality. A total of 60 patients with overt OGIB were randomized. The mean follow-up was 48.5 months. The diagnostic yield of immediate CE was significantly higher than angiography (53.3% vs. 20.0%, P=0.016). The cumulative risk of rebleeding in the angiography and CE group was 33.3% and 16.7%, respectively (P=0.10, log-rank test). There was no significant difference in the long-term outcomes between the two groups including further transfusion, hospitalization for rebleeding, and mortality. In patients with overt OGIB, immediate CE has higher diagnostic yield and comparable long-term outcomes when compared with angiography.
    The American Journal of Gastroenterology 07/2012; 107(9):1370-6. · 7.55 Impact Factor
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    ABSTRACT: The reconstruction of three-dimensional (3D) ultrasound panorama from multiple ultrasound volumes can provide a wide field of view for better clinical diagnosis. Registration of ultrasound volumes has been a key issue for the success of this panoramic process. In this paper, we propose a method to register and stitch ultrasound volumes, which are scanned by dedicated ultrasound probe, based on an improved 3D Scale Invariant Feature Transform (SIFT) algorithm. We propose methods to exclude artifacts from ultrasound images in order to improve the overall performance in 3D feature point extraction and matching. Our method has been validated on both phantom and clinical data sets of human liver. Experimental results show the effectiveness and stability of our approach, and the precision of our method is comparable to that of the position tracker based registration.
    10/2008: pages 52-60;
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    ABSTRACT: The reconstruction of three-dimensional (3D) ultrasound panorama from multiple ultrasound volumes can provide a wide field of view for better clinical diagnosis. Registration of ultrasound volumes has been a key issue for the success of this panoramic process. In this paper, we propose a method to register and stitch ultrasound volumes, which are scanned by dedicated ultrasound probe, based on an improved 3D Scale Invariant Feature Transform (SIFT) algorithm. We propose methods to exclude artifacts from ultrasound images in order to improve the overall performance in 3D feature point extraction and matching. Our method has been validated on both phantom and clinical data sets of human liver. Experimental results show the effectiveness and stability of our approach, and the precision of our method is comparable to that of the position tracker based registration.
    Medical image computing and computer-assisted intervention : MICCAI ... International Conference on Medical Image Computing and Computer-Assisted Intervention. 02/2008; 11(Pt 2):52-60.
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    ABSTRACT: Ultrasound-guided biopsy is one of the most fundamental, but difficult, skills to acquire in interventional radiology. Intensive training, especially in the needle insertion, is required for trainee radiologists to perform safe procedures. In this paper, we propose a virtual reality simulation system to facilitate the training of radiologists and physicians in this procedures. Key issues addressed include a 3D anatomical model reconstruction, data fusion of multiple ultrasound volumes and computed tomography (CT), realistic rendering, interactive navigation, and haptic feedbacks in six degrees of freedom (DOF). Simulated ultrasound imagery based on real ultrasound data is presented to users, in real-time, while performing an examination on the needle placement into a virtual anatomical model. Our system delivers a realistic haptic feeling for trainees throughout the simulated needle insertion procedure, permitting repeated practices with no danger to patients.
    Medical image computing and computer-assisted intervention : MICCAI ... International Conference on Medical Image Computing and Computer-Assisted Intervention. 02/2008; 11(Pt 2):551-9.
  • J Qin, K S Choi, Simon S M Ho, P A Heng
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    ABSTRACT: A force prediction algorithm is proposed to facilitate virtual-reality (VR) based collaborative surgical simulation by reducing the effect of network latencies. State regeneration is used to correct the estimated prediction. This algorithm is incorporated into an adaptive transmission protocol in which auxiliary features such as view synchronization and coupling control are equipped to ensure the system consistency. We implemented this protocol using multi-threaded technique on a cluster-based network architecture.
    Studies in health technology and informatics 02/2008; 132:387-9.
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    ABSTRACT: This prospective trial aimed to evaluate the safety and effectiveness of transarterial ethanol ablation (TEA) of intrahepatic lesions of hepatocellular carcinoma (HCC) with a Lipiodol-ethanol mixture. Seventy-seven patients were recruited and 164 lesions (mean size, 5.2 cm +/- 3.0) were treated. Inclusion criteria included histologic proof of HCC, refusal of (n = 9) or contraindication to (n = 68) surgical resection, Eastern Cooperative Oncology Group performance status no greater than 2, and intrahepatic disease without vascular invasion. The mixture consisted of 33% ethanol by volume, with the total dose of Lipiodol-ethanol mixture limited to 60 mL for each treatment session. The primary endpoint was patient survival. Secondary endpoints were tumor response, adverse effects of treatment, and progression-free survival. Median follow-up time for the whole cohort was 2.3 years. Median overall survival was 2.2 years. Overall survival and progression-free survival rates at 1 year and 2 years were 77.9% and 50.1% and 63.6% and 46.3%, respectively. Complete ablation according to radiologic criteria was achieved in 61 patients (79.2%) and 86% of the 164 treated lesions. Mean tumor volume reduction was 65.22%. Patient survival was significantly better in patients with tumors no larger than 5 cm (Cox proportional-hazards regression, P = .0074). Treatment response was significantly better for patients with tumors no greater than 7 cm (chi2 test, P = .0462; Fisher exact test, P = .0326). Adverse effects included irreversible hepatic decompensation (0.6% of procedures), pain (4.8%), and fever (13.8%). TEA is a safe and effective means to establish local control of unresectable and resectable intrahepatic lesions of HCC.
    Journal of Vascular and Interventional Radiology 02/2008; 19(1):95-103. · 2.00 Impact Factor
  • J Qin, P A Heng, K S Choi, Simon S M Ho
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    ABSTRACT: Research on collaborative virtual surgery opens the opportunity for simulating the cooperative work during surgical operations. It is however a challenging task to design and implement a high performance collaborative surgical simulation system because of the difficulty in maintaining a high level of state consistency under limited network transmission capacity. In this paper, we present an adaptive framework using cluster-based hybrid architecture to support real-time collaboration in surgical simulation. In addition to the TCP communication protocol, the framework is also equipped with UDP for multicasting, allowing for a flexible strategy to reduce network latency. A set of techniques was proposed to assure reliable transmission on top of standard yet unreliable multicast protocols. Experimental results demonstrate that this framework can support collaborative surgical simulation with lower network latencies than traditional client-server architecture.
    Studies in health technology and informatics 02/2007; 125:367-72.
  • Simon S.M. Ho, Richard H. Pike
    Journal of Business Finance & Accounting 12/2006; 19(3):387 - 405. · 0.69 Impact Factor
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    ABSTRACT: Image diffusion can smooth away noise and small-scale structures while retaining important features, thereby enhancing the performances of many image processing algorithms such as image compression, segmentation and recognition. In this paper, we present a novel diffusion algorithm for which the filtering kernels vary according to the perceptual saliency of boundaries in the input images. The boundary saliency is estimated through a saliency measure which is generally determined by curvature changes, intensity gradient and the interaction of neighboring vectors. The connection between filtering kernels and perceptual saliency makes it possible to remove small-scale structures and preserves significant boundaries adaptively. The effectiveness of the proposed approach is validated by experiments on various medical images including the color Chinese Visible Human data set and gray MRI brain images.
    Medical image computing and computer-assisted intervention : MICCAI ... International Conference on Medical Image Computing and Computer-Assisted Intervention. 02/2006; 9(Pt 2):67-75.
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    ABSTRACT: A coaxial technique was introduced for successful embolization of a large fusiform splenic artery aneurysm in a vessel with a large caliber and a great degree of tortuosity. A standard 5-F angioplasty catheter was placed at the immediate afferent artery for occlusion of arterial inflow into the aneurysm, thereby preventing intraaneurysmal hypertension during embolization of the efferent segment. This was followed by coaxial microcatheterization of the immediate efferent segment for coil embolization, and then embolization of the afferent segment. It is postulated that this approach may improve the safety of embolization of large aneurysms with unfavorable morphology by decreasing the pressure on the aneurysm just after closure of the efferent segment.
    Journal of Vascular and Interventional Radiology 11/2005; 16(10):1373-7. · 2.00 Impact Factor
  • Simon S M Ho, Nigel C Cowan
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    ABSTRACT: To evaluate in a prospective study the use of a 4F Rosch inferior mesenteric (RIM) catheter for uterine artery embolisation (UAE). UAE was performed in 72 women over a 37-month period. A 4F RIM braided J-curve 65-cm catheter was used in combination with an angled hydrophilic 150 cm, 0.035" flexible tip guide-wire to catheterise the horizontal portion of both uterine arteries (UA) from a right common femoral artery (CFA) approach. Technical success was defined as successful catheterisation and embolisation of both uterine arteries. Fluorosocpic and procedure times were recorded. Mean subject age=43.7 years (range=25-57 years). Technical success was 98.6% (n=71/72). A single approach via the right CFA was used in 88.9% (n=64/72) and a bilateral CFA approach in 11.1% (n=8/72). Bilateral uterine artery catheterisation using a single 4F RIM catheter via the right CFA approach was successful in 79.2% (n=57/72). Microcatheters were used in 2.8% of patients (n=2/72). Mean fluoroscopic time=13.6+/-5.3 min (mean+/-SD). Mean procedure time=44.2+/-16.5 min. High technical success rate for UAE is possible using a single 4F RIM catheter via a unilateral right CFA approach, which obviates the need for Waltman loop formation, reversed curve catheters and complex suture-catheter arrangements.
    European Radiology 06/2005; 15(6):1168-72. · 4.34 Impact Factor
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    ABSTRACT: This study aims to compare the therapeutic effectiveness of continuous catheter drainage versus intermittent needle aspiration in the percutaneous treatment of pyogenic liver abscesses. Over a 5-year period, 64 consecutive patients with pyogenic liver abscess were treated with intravenous antibiotics (ampicillin, cefuroxime, and metronidazole) and randomized into two percutaneous treatment groups: continuous catheter drainage (with an 8F multi-sidehole pigtail catheter); and intermittent needle aspiration (18G disposable trocar needle). There was no statistically significant difference between the two groups regarding patient demographics, underlying coexisting disease, abscess size, abscess number, number of loculation of abscess, the presenting clinical symptoms such as fever, abdominal pain, and pretreatment liver function test. Although not statistically significant, the duration of intravenous antibiotics treatment before percutaneous treatment was longer with the catheter group, and the change of antibiotics after the sensitivity test was more frequent with the needle group. The needle group was associated with a higher treatment success rate, a shorter duration of hospital stay, and a lower mortality rate, although this did not reach statistical significance. In conclusion, this study suggests that intermittent needle aspiration is probably as effective as continuous catheter drainage for the treatment of pyogenic liver abscess, although further proof with a large-scale study is necessary. Due to the additional advantages of procedure simplicity, patient comfort, and reduced price, needle aspiration deserves to be considered as a first-line drainage approach.
    Hepatology 05/2004; 39(4):932-8. · 12.00 Impact Factor
  • Yaw M. Mensah, Xiaofei Song, Simon S. M. Ho
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    ABSTRACT: This study examines the effect of the implementation of conservative accounting policies by firms on analysts' annual earnings absolute forecast errors and forecast dispersion. Three aggregate accounting-based conservatism measures were used to estimate the level of conservatism in accounting practice. After controlling for the effects of industry, forecast age, number of analysts following the firm, firm size, earnings stability, and risk, accounting conservatism was found to be associated with higher forecast errors and forecast dispersion. Furthermore, the tests of robustness indicate that the above results are not driven by earnings predictability, the undue influence of outliers, or earnings management.
    Journal of Accounting, Auditing and Finance 04/2004; 19(2).
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    ABSTRACT: This paper provides evidence of the association between a firm's investment opportunity set (IOS), director ownership, and corporate policy choices. Using a sample of growth and non-growth firms in an emerging Asian market, we find that the IOS theory has significant explanatory power in the financing, dividend, executive compensation, and leasing aspects of corporate policies. Growth firms have lower debt-to-equity ratios and dividend yields, pay higher cash compensation and bonus amounts to their top executives, and finance a higher proportion of their asset acquisitions through operating leases. We also find that director ownership moderates and counteracts the association between IOS and corporate policies. Our results are consistent with contracting theory predictions that high director ownership mitigates the need for incentive or bonus compensation plans in growth firms.
    Journal of Corporate Finance. 02/2004; 10(3):383-408.
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    ABSTRACT: A woman with stage IIIb non-small cell lung cancer (NSCLC) developed disease progression with brain metastases during chemotherapy. Due to unusual circumstances, the patient received gefitinib alone, without the use of corticosteroid treatment or radiotherapy. There was a dramatic clinical improvement within 1 week. Follow-up magnetic resonance imaging of the brain 1 month later showed decreases in both the size and number of brain metastases. The patient remains well 9 months after initiation of gefitinib. It is proposed that gefitinib may have a role in treatment of brain metastases from NSCLC.
    Oncology 01/2004; 67(2):174-8. · 2.17 Impact Factor
  • Simon S M Ho, Kar Shun Wong
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    ABSTRACT: This paper reports a study of the perceptions of preparers of corporate annual reports (mainly chief finance officers (CFOs)) on the usefulness and concerns of corporate disclosures in Asia's major international financial centre — Hong Kong. From a survey of 98 preparers, it was found that preparers are more inclined to satisfy the information needs of external institutional finance suppliers than those of individual investors and financial analysts or stockbrokers. CFOs and CEOs have more influence on corporate disclosure policies and decisions than board chairmen and company directors. The stock exchange, the Company Ordinance and the local accounting standards setter are more influential external bodies than external auditors and the Securities and Futures Commission. Although only a small percentage of preparers felt that the current disclosures were either effective or very effective in serving investors' needs, only a small number of them agreed to have more financial reporting and disclosure regulations. To close the communications gap and improve market efficiency, they suggested instead an improvement in investor relationships, developing more industry-specific disclosure guidelines and more voluntary disclosures. Implications of these findings are discussed.International Journal of Disclosure and Governance (2003) 1, 71-81; doi:10.1057/palgrave.jdg.2040014
    International Journal of Disclosure and Governance 11/2003; 1(1):71-81.
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    Simon S. M. Ho
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    ABSTRACT: This paper reviews the background, practice, core problems, effectiveness and prospects of corporate governance in Hong Kong. Areas discussed include the standard and core problems, legal and regulatory framework, owner-directors and conflicts with minority shareholders, directors' duties and board practice, accounting/disclosure standard setting and corporate reporting, auditor independence and accountability, market intermediaries and analysts, empowering minority shareholders and shareholder activism, and convergence of CG practice.
    08/2003;
  • Yaw M Mensah, Xiaofei Song, Simon S.M Ho
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    ABSTRACT: This paper examines evidence of the long-term payoff from an increase in corporate disclosures over time. The basic hypothesis examined is that increases in corporate disclosures (whether voluntary or mandatory) are associated with declines in analysts’ annual earnings forecast error (FE) and forecast dispersion (FD) at the aggregate level. Using the Prais–Winsten autoregressive approach and cointegration tests, we find evidence of such a long-term relationship in the United States from 1983 to 1998. However, only aggregate forecast dispersion declined during this period. Aggregate forecast error did not exhibit a secular downward trend, although its long-term secular movement was cointegrated with the corporate disclosure index developed for this study.
    Journal of Accounting and Public Policy 02/2003; · 1.05 Impact Factor
  • Simon S. M. Ho, Kar Shun Wong
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    ABSTRACT: The recent economic turmoil in Asia has led to a wider recognition of the importance of corporate transparency and disclosures in financial dealings. The objective of this study is to provide comprehensive and up-to-date evidence of current practice and perceived effectiveness of corporate disclosure of listed companies in an emerging economy—Hong Kong. The study compares the perceptions of chief financial officers (CFOs) and financial analysts about a variety of information flow, disclosure and capital market efficiency issues. It also seeks to determine whether there is a perceived need for increased financial reporting regulations and to what extent this and other alternative means might improve market functioning. While both subject groups believed that a majority of firms only adopt a conservative one-way disclosure strategy and the existence of a communication gap, analysts perceived a much higher need than CFOs for increased financial reporting regulations. Neither group thought that enhancing disclosure requirements alone would suffice to close this gap. Instead, they suggested an improvement in the quality of the communication and disclosure processes through means such as choosing more appropriate communication media, formulating a more proactive disclosure strategy, enhancing investor relationship, and voluntarily reporting more information desired by users.
    Journal of International Financial Management & Accounting 12/2002; 12(1):75 - 102. · 0.33 Impact Factor
  • Alicja Jaruga, Simon S. M. Ho
    Management Accounting Research. 01/2002; 13(4):375-378.

Publication Stats

281 Citations
32.88 Total Impact Points

Institutions

  • 1991–2007
    • The Chinese University of Hong Kong
      • • Department of Computer Science and Engineering
      • • School of Accountancy
      Hong Kong, Hong Kong
  • 2004
    • Temple University
      • Department of Accounting
      Philadelphia, Pennsylvania, United States
  • 2003
    • Hong Kong Baptist University
      Chiu-lung, Kowloon City, Hong Kong