Ka-Tak Wong

Prince of Wales Hospital, Hong Kong, Chiu-lung, Kowloon City, Hong Kong

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Publications (15)73.17 Total impact

  • Gastroenterology 05/2014; 79(5):AB113. · 12.82 Impact Factor
  • Gastroenterology 05/2014; 79(5):AB113. · 12.82 Impact Factor
  • Article: Response.
    Gastrointestinal endoscopy 08/2011; 74(2):450. · 6.71 Impact Factor
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    ABSTRACT: In patients with bleeding peptic ulcers in whom endoscopic hemostasis fails, surgery usually follows. Transarterial embolization (TAE) has been proposed as an alternative. To compare the outcomes of TAE and salvage surgery for patients with peptic ulcers in whom endoscopic hemostasis failed. Retrospective study. A university hospital. Patients with peptic ulcer bleeding in whom endoscopic hemostasis failed. TAE and surgery as salvage of peptic ulcer bleeding. All-cause mortality, rebleeding, reintervention, and complication rate. Thirty-two patients underwent TAE and 56 underwent surgery. In those who underwent TAE, the bleeding vessels were gastroduodenal artery (25 patients), left gastric artery (4 patients), right gastric artery (2 patients), and splenic artery (1 patient). Active extravasation was seen in 15 patients (46.9%). Embolization was attempted in 26 patients, and angiographic coiling was successful in 23 patients (88.5%). Bleeding recurred in 11 patients (34.4%) in the TAE group and in 7 patients (12.5%) in the surgery group (P=.01). More complications were observed in patients who underwent surgery (40.6% vs 67.9%, P=.01). There was no difference in 30-day mortality (25% vs 30.4%, P=.77), mean length of hospital stay (17.3 vs 21.6 days, P=.09), and need for transfusion (15.6 vs 14.2 units, P=.60) between the TAE and surgery groups. Retrospective study. In patients with ulcer bleeding after failed endoscopic hemostasis, TAE reduces the need for surgery without increasing the overall mortality and is associated with fewer complications.
    Gastrointestinal endoscopy 02/2011; 73(5):900-8. · 6.71 Impact Factor
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    ABSTRACT: Little is known about the virological and inflammatory responses of severe pandemic 2009 influenza A(H1N1) virus pneumonia during antiviral treatment. In a prospective observational study, we recruited consecutive adults hospitalized with confirmed pandemic 2009 H1N1 infection during a 16-week period. Nasopharyngeal aspirate and non-respiratory samples (blood, stool and urine) were collected at presentation, and serial nasopharyngeal flocked swabs (NPFS) and tracheal aspirates (TA) were collected after initiating oseltamivir treatment for quantitative viral RNA assay, using real-time reverse transcriptase-PCR. Serial plasma samples were collected for cytokine/chemokine assay using cytometric bead array. Patients with severe pneumonia (lung infiltrates and hypoxaemia) were compared to those with milder illnesses. A total of 66 patients were studied (mean age 43 ±20 years); 28 (42%) developed severe pneumonia, of whom 10 (15%) required intubation. Severe pneumonia was associated with older age, dyspnoea, delayed presentation >2 days from onset, extrapulmonary virus detection (13-28%) and higher viral concentration despite late-presentation (multiple linear regression, β=0.94, 95% confidence interval 0.15-1.74; P=0.02). Patients with severe pneumonia exhibited slow viral clearance with oseltamivir treatment, particularly in the lower respiratory tract (median [interquartile range] durations of RNA positivity after antiviral initiation were NPFS 6.0 days [3.0-8.0], TA 11.0 days [7.8-14.3] versus milder illness group NPFS of 2.0 days [1.0-3.0] days; P<0.01). High viral load in lower respiratory tract despite upper-tract RNA negativity and viral rebound after stopping treatment were noted in some patients. H275Y mutation was absent. High plasma levels of interleukin (IL)-6, CXCL-8 (IL-8), CCL2 (monocyte chemoattractant protein-1) and soluble tumour necrosis factor receptor-1 were observed, which correlated with the extent and progression of pneumonia in hospital. In severe 2009 H1N1 pneumonia, viral clearance is slow with treatment, particularly in the lower respiratory tract. A more sustained antiviral regime appears warranted.
    Antiviral therapy 01/2011; 16(2):237-47. · 3.07 Impact Factor
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    ABSTRACT: To evaluate real-time qualitative ultrasound elastography as an adjunct to conventional sonography for evaluation of non-nodal neck masses identified in routine clinical practice, 52 consecutive masses in 49 patients underwent both techniques. Lesion stiffness was graded visually on chromatic-scale elastograms from ES0-3 (low to high). Diagnosis was based on (cyto)pathology (11), corroborative cross-sectional imaging (18) or characteristic conventional sonography (23). There were 16 lipomas, 15 lymphatic/venous vascular malformations (LVVMs), six neurogenic tumours/neuromas, five thyroglossal duct cysts (TGCs), five (epi)dermoids, three abscesses, one second-arch branchial cleft cyst (BCC), and one soft-tissue metastasis. In general terms, lesion stiffness was high (ES2-3) for neurogenic tumours/neuromas, (epi)dermoids and metastasis, and low (ES0-1) for lipomas, LVVM, TGCs and BCC. Abscesses displayed variable stiffness according to fluid content. Technical limitations and artefacts of elastograms were identified. Data from real-time qualitative ultrasound elastography may be a useful adjunct to sonography for diagnosis of non-nodal neck masses.
    Ultrasound in medicine & biology 10/2010; 36(10):1644-52. · 2.46 Impact Factor
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    ABSTRACT: To evaluate qualitative ultrasound elastography for focal salivary gland masses identified during routine clinical practice. Sixty-five parotid or submandibular masses in 61 patients underwent real-time qualitative ultrasound elastography and were scored on colour-scaled elastograms in terms of their stiffness relative to adjacent normal salivary parenchyma from ES 1 (soft) to ES 4 (stiff). This was correlated with diagnosis from aspiration cytology or histology. There were 29 Warthin's tumours (WTs), 23 pleomorphic adenomas (PAs), 2 adenoid cystic carcinomas, 1 adenosquamous carcinoma, 1 nodal metastasis from nasopharyngeal carcinoma, 1 lymphoma (2 deposits), 3 Kuttner tumours and 4 cases of Kimura's disease. ES scores showed clustering according to pathological condition. In this respect, PAs were firmer than WTs (P < 0.004, Fisher's exact test). Nine, 19, 14 and 17 of the benign masses and 0, 1, 2 and 3 of the malignant masses were ES 1, 2, 3 and 4 respectively. All three primary salivary malignancies were ES 4 compared with 1/29 WTs and 16/23 PAs. These preliminary findings suggest that qualitative real-time ultrasound elastography, although an ancillary technique to conventional ultrasound in the salivary glands, is likely to have a poor ability to discriminate benign lesions (particularly PAs) from malignant disease.
    European Radiology 08/2010; 20(8):1958-64. · 4.34 Impact Factor
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    ABSTRACT: Background: Despite accumulated experience and improved understanding of the tools, endovascular treatment of cerebral aneurysms still has risks associated with the technique itself and with the specificity of the pathology treated. An important risk is parent vessel Guglielmi detachable coil herniation. Here we review and illustrate our experiences in using a stent to manage this complication.Methods: We reviewed our experiences in 142 intracranial aneurysm embolizations over a four and a half year period and identified 13 cases with intravascular stent deployment. Three cases were unique in using a stent for salvage of coil herniation into the parent vessel.Results: We reported these cases and reviewed the literature for the management of parent vessel coil herniation.Conclusion: Parent vessel coil herniation was an uncommon but important complication of endovascular coiling of intracranial aneurysm. Intravascular stent placement provided a tool to sequester herniated coils from the lumen of the parent artery to minimize thromboembolic complications and restore flow.
    Surgical Practice 10/2009; 13(4):114 - 118. · 0.11 Impact Factor
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    ABSTRACT: To investigate the prognostic value of HER2 and p63 expression in head and neck squamous cell carcinoma (HNSCC). A case review of 186 HNSCCs from the oral tongue, palate, maxillary sinus, floor of mouth, oropharynx, hypopharynx, and larynx. All primary tumor specimens were evaluated by immunohistochemistry for HER2 and p63 expressions, which were correlated with clinical parameters including age, sex, grade, lymph node metastases, stage, and survival. One hundred forty-one patients had stage III-IV disease and 109 had lymph node metastases. For all cases, T and N stages were significant prognostic predictors for both overall and disease-free survivals. In the node-positive subgroup, T stage and HER2 expression were significant prognostic predictors for both overall and disease-free survivals. HER2 may be associated with longer survival in node-positive patients with HNSCC.
    Otolaryngology Head and Neck Surgery 10/2009; 141(4):467-73. · 1.73 Impact Factor
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    ABSTRACT: We investigated the role of noncontrast computerized tomography in predicting the treatment outcome of shock wave lithotripsy on upper ureteral stones to formulate a clinical algorithm to facilitate clinical management. Adult patients with upper ureteral stones confirmed by noncontrast computerized tomography and scheduled for primary in situ shock wave lithotripsy were prospectively recruited. Standardized treatment was performed on each patient. The primary end point was stone-free status at 3 months. Pretreatment noncontrast computerized tomography was assessed by a single radiologist blinded to the clinical parameters. Predictive values of computerized tomography measurements on the treatment outcome were then assessed. Between October 2004 and July 2007 a total of 94 patients (60 male and 34 female) were recruited for the study. Logistic regression showed that stone volume, mean stone density and skin-to-stone distance were potential predictors of successful treatment. From ROC curves the optimum cutoff for predicting treatment outcomes for stone volume, mean stone density and skin-to-stone distance was 0.2 cc, 593 HU and 9.2 cm, respectively. A simple scoring system was constructed based on the 3 factors of stone volume less than 0.2 cc, mean stone density less than 593 HU or skin-to-stone distance less than 9.2 cm. The stone-free rate for patients having 0, 1, 2 and 3 factors was 17.9%, 48.4%, 73.3% and 100%, respectively (linear-by-linear association test 22.83, p <0.001). Stone volume, mean stone density and skin-to-stone distance were potential predictors of the successful treatment of upper ureteral stones with shock wave lithotripsy. A scoring system based on these 3 factors helps separate patients into outcome groups and facilitates treatment planning.
    The Journal of urology 01/2009; 181(3):1151-7. · 3.75 Impact Factor
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    ABSTRACT: Head and neck squamous cell carcinoma (HNSCC) has high morbidity and mortality, and its relationship with tumor angiogenesis as measured by microvessel density (MVD) or vascular endothelial growth factor (VEGF) expression has shown mixed results, with some, but not others, reporting correlation with outcome. A retrospective study of 186 patients with HNSCC was performed. Patients were evaluated for MVD and VEGF and to correlate the levels with clinical parameters, including age at diagnosis, sex, site of tumor, stage, survival (disease free and overall), pathological tumor grade, and the presence of lymph node metastases. The 186 cancers included the following sites: oral tongue (n = 69), palate (n = 9), maxillary sinus (n = 8), floor of mouth (n = 13), oropharynx (n = 27), hypopharynx (n = 26) and larynx (n = 34). Over three-quarters of patients had advanced tumor (stage III/IV) and 58.6% had lymph node metastases. MVD and VEGF were assessed in 166 and 164 cases, respectively, but these were not correlated with site and grade. The 3-year overall and disease-free survival rates were 55.4% and 53.2%, respectively. Both univariate and multivariate survival analysis showed that advanced T stage, nodal metastasis, and strong VEGF intensity were independent adverse predictors for overall and disease-free survival. In stage IV disease, strong VEGF immunoreactivity was found to be the single adverse factor affecting the overall survival and a contributory factor for disease-free survival. VEGF immunoreactivity is a strong predictor of adverse outcome, particularly in locoregionally advanced disease.
    Annals of Surgical Oncology 01/2008; 14(12):3558-65. · 4.12 Impact Factor
  • The American journal of medicine 01/2008; 120(12):e7-10. · 5.30 Impact Factor
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    ABSTRACT: Magnetic resonance imaging of the breast is useful in assessing breast lesions. An understanding of the pathologic characteristics of the tumors may help to understand these magnetic resonance imaging observations.Large lesional size (>10 mm), ill-defined margin, and irregular outlines are associated with malignancy. These correlate with the pathological features of breast tumor, characterized by rapid growth rate, large size, and infiltrative growth pattern, invasion into stroma resulting in desmoplasia, and hence irregular outline and margin. The detection and estimation of tumor extent of invasive lobular carcinoma is problematic, even with magnetic resonance imaging, which is considered the most sensitivity. This inaccuracy likely derives from the characteristic linear, single cells infiltration growth pattern of the tumor, which is also often underestimated by clinical examination. Estimation of tumor extent after neoadjuvant chemotherapy is also essential but problematic by imaging, as the shrunken tumor becomes fibrotic, with stromal hyalinization, diminished microvasculature and tumor break up causing size underestimation. Non-enhancement of breast tumors occurs in about 8% of cases correlates with diffuse growth pattern, particularly of infiltrative lobular carcinoma. The observation of disproportionately high non-enhancing ductal carcinoma in situ remains an enigma. Finally, early rim enhancement correlates with small cancer nests, low ratio of peripheral to central fibrosis and high ratio of peripheral to central microvessel density. These may be related to increased vascular endothelial growth factor mediated increased microvessel density as well as increased permeability, which manifest as increased rapid contrast uptake and dissipation.
    Breast Cancer Research and Treatment 06/2007; 103(1):1-10. · 4.47 Impact Factor
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    ABSTRACT: To evaluate thin-section computed tomography findings of patients with severe acute respiratory syndrome (SARS) in the convalescent period and to correlate the results with clinical parameters and lung function tests. Ninety-nine severe acute respiratory syndrome patients with persistent changes on follow-up chest radiography were included. One hundred seventy computed tomography examinations at baseline (n=70), 3 months (n=56), and 6 months (n=44) were retrospectively evaluated to determine the extent of ground-glass opacification, reticulation, and total parenchymal involvement. Patients' demographic information, clinical information during treatment, and results of lung function tests at 3 and 6 months were correlated with computed tomography findings. A significant serial improvement in the extent of overall ground-glass opacification, overall reticulation, and total parenchymal involvement was observed (P <0.01). Advanced age, previous intensive care unit admission, mechanical ventilation, alternative treatment, higher peak lactate dehydrogenase, and peak radiographic involvement during treatment showed a positive correlation with overall reticulation and total parenchymal involvement at 6 months. There was a significant negative correlation between overall reticulation and total parenchymal involvement with diffusion capacity adjusted for hemoglobin at 3 and 6 months (P <0.01). Lung changes on thin-section computed tomography of severe acute respiratory syndrome patients improved with time during the convalescent period and showed a significant correlation with advanced age, parameters indicating severe illness, and diffusion capacity adjusted for hemoglobin on follow-up.
    Journal of Computer Assisted Tomography 10/2004; 28(6):790-5. · 1.58 Impact Factor
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    ABSTRACT: Vascular malformations arising from the wall of the external jugular vein are rare. This case series discusses the sonographic and MR imaging appearances of four such cases and reviews the literature. The diagnosis should be suggested preoperatively particularly because of the close relationship such malformations to the external jugular vein, as this helps surgeons to plan the operative procedure. The imaging appearances are similar to those of other vascular malformations elsewhere in the head and neck.
    American Journal of Neuroradiology 03/2004; 25(2):338-42. · 3.17 Impact Factor