S.C.H. Chan

Queen Elizabeth Hospital, Hong Kong, Hong Kong

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Publications (29)9 Total impact

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    ABSTRACT: Vesicoureteric reflux has been associated with paediatric urinary tract infection. Fluoroscopic micturating cystourethrography (MCU) has been the gold standard of diagnostic test for decades; however, it has been criticized owing to its lower detection rate and radiation dose to children. Therefore, new radiation-free reflux imaging modalities have been developed, in which ultrasound-based contrast-enhanced voiding urosonography (ceVUS) is a good example. However, ultrasonography has been considered as an operator-dependent examination. Therefore, our study aimed to examine the inter-observer agreement of this sonographic technique, which has not been evaluated before. Moreover, the second-generation ultrasound contrast SonoVue has been recently marketed, and the data on its efficacy on intravesical use in ceVUS is relatively scarce. Thus, we also aimed to investigate the diagnostic performance and safety profile of SonoVue-enhanced VUS in the diagnosis of vesicoureteric reflux. Our prospective comparative study compared the diagnostic performance of ceVUS with MCU in young children presenting with first episode of urinary tract infection. We performed sequential ceVUS and MCU examinations in 31 patients (62 pelvi-ureter units). Perfect inter-observer agreement (Cohen's kappa statistics = 1.0, p < 0.001) was achieved in ceVUS, suggesting its good reliability in reflux detection and grading. Using MCU as reference, ceVUS had 100 % sensitivity and 84 % specificity and carried higher reflux detection rate than MCU (p < 0.001). There was no complication encountered. Conclusion: Voiding urosonography is a reliable, sensitive, safe and radiation-free modality in the investigation of vesicoureteric reflux in children. It should be incorporated in the diagnostic algorithm in paediatric urinary tract infection.
    No preview · Article · Mar 2014 · European Journal of Pediatrics
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    ABSTRACT: Sclerosing adenosis belongs to the group of benign proliferative breast diseases. The imaging and histological findings of sclerosing adenosis can mimic invasive ductal carcinoma. The diagnosis of sclerosing adenosis is challenging, and requires the combination of clinical, radiological, and pathological findings. Sclerosing adenosis is associated with a small risk of subsequent breast carcinoma. This report is of two patients with incidentally detected and biopsy-proven sclerosing adenosis. The clinical history, serial mammogram, breast ultrasonography, and preoperative breast magnetic resonance imaging findings are reviewed and the histological slides of the biopsy and surgical specimens are presented. In both patients, serial follow-up ultrasonography 7 years after the initial diagnosis showed mild increase in vascularity in the lesions. Repeat biopsies were performed, which showed invasive ductal carcinoma and ductal carcinoma in situ in patient 1 and patient 2, respectively. The authors recommend long-term follow-up for a sclerosing adenosis because of the risk of breast carcinoma with a long latency period. If any suspicious feature or change in morphology is detected in follow-up imaging, a biopsy should be performed to exclude carcinoma.
    No preview · Article · Mar 2014 · Hong Kong Journal of Radiology
  • J.W.C. Wai · K.C. Lai · M.K. Chan · S.C.H. Chan
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    ABSTRACT: Peroneal tenosynovitis in association with hypertrophy of the peroneal tubercle is part of the differential diagnosis of lateral foot and ankle pain. When the peroneal tubercle is enlarged, it can be a source of discomfort when wearing shoes, but it rarely causes tenosynovitis of the peroneal tendons. We report on a 63-year-old man who had stenosing tenosynovitis of peroneus tendon in association with hypertrophy of the peroneal tubercle. Illustrative features on ultrasonography and computed tomography will be demonstrated in this report.
    No preview · Article · Dec 2012 · Hong Kong Journal of Radiology
  • J.W.C. Wai · M.K. Chan · K.W. Tang · S.C.H. Chan
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    ABSTRACT: Infiltration of the peripheral nervous system by lymphoma is termed neurolymphomatosis. Prior to identification of the causative B lymphocyte, neurolymphomatosis was the least common clinical presentation of nervous system lymphoma. Neurolymphomatosis can easily be misdiagnosed as neurogenic tumour from imaging at the first presentation. This report describes two patients with neurolymphomatosis with characteristic sonographic, magnetic resonance imaging, and positron emission tomography features.
    No preview · Article · Sep 2012 · Hong Kong Journal of Radiology
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    ABSTRACT: Objective: To retrospectively assess the sensitivity and specificity of ultrasound-guided fine-needle aspiration of axillary lymph nodes for preoperative breast cancer staging, using histological findings as a reference standard. Methods: This was a retrospective study involving 95 consecutive adult patients having ultrasound-guided fine-needle aspiration of axillary lymph nodes performed from January to December 2010. In all, 45 (47%) of the patients had newly diagnosed carcinoma of breast. Four (4%) had axillary lymph node recurrences from a breast or lung tumour. The remainder (n = 46; 48%) did not have malignancy, showing incidentally enlarged reactive axillary lymph nodes only. Results: The ages of the 45 women in the study group ranged from 30 to 78 (mean, 51) years. The mean primary breast cancer tumour size was 2.8 cm (range, 0.4-11.0 cm). Regarding the 45 axillary biopsies in this study, only six samples (13%) gave inconclusive results. Among these, four underwent surgery and three had positive lymph nodes. In all, 25 (56%) yielded positive fine-needle cytology findings, whilst in the remainder (n = 14; 31%), cytology was negative for malignancy. Twenty-three (51%) yielded metastatic carcinoma in the sentinel node biopsy or dissected axillary lymph node. Patients with positive ultrasound-guided fine-needle aspiration results and those with negative results were further analysed with their pathological results. Lymph nodes were more likely to be positive for metastatic disease with increased pathological tumour size. Ultrasound-guided fine-needle aspiration of axillary lymph nodes for preoperative staging is highly sensitive and specific, with satisfactory 95% confidence intervals. Conclusion: Ultrasound-guided fine-needle aspiration of axillary lymph nodes was a highly sensitive and specific non-surgical means of staging breast cancer. Positive cytology for metastatic disease is sufficient to replace sentinel node biopsy and proceed to axillary lymph node dissection, and thus decrease the duration of anaesthesia and associated morbidity.
    No preview · Article · Mar 2012 · Hong Kong Journal of Radiology
  • J.W.C. Wai · J.L.F. Chiu · T.S. To · K.H. Lai · C.W. Siu · K.Y. Kwok · S.C.H. Chan
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    ABSTRACT: Breast cancer is the most common malignancy and the third most common cause of cancer death in Hong Kong women. Ultrasound imaging and contrast-enhanced magnetic resonance imaging are useful adjuncts to mammography. The advantage of breast magnetic resonance imaging is its high sensitivity for invasive breast cancer. Therefore indications for and use of breast magnetic resonance imaging have increased over the past decade. In this article, we illustrate the current protocol for dynamic contrast-enhanced breast magnetic resonance imaging in our centre, by reference to cases with different indications for such imaging. We also review the common artefacts and pitfalls in breast magnetic resonance imaging. Contrast-enhanced breast magnetic resonance imaging is a powerful imaging modality for breast diseases. An awareness of proper technique, potential pitfalls, and artefacts is critical to achieving accurate image interpretation. When breast magnetic resonance imaging is performed with the required technical finesse and in the appropriate clinical setting, it is a highly sensitive and reasonably specific means of detecting breast cancer.
    No preview · Article · Mar 2012 · Hong Kong Journal of Radiology
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    ABSTRACT: Objective: To review the mammographic and sonographic features of common benign and malignant lesions of the male breast. Methods: This was a retrospective institutional review. A total of 72 consecutive male patients having breast imaging performed between 1 July 1999 and 30 June 2010 were included. The clinical data and electronic radiological images were retrieved from the electronic patient record, radiology information system, and Advantage Workstation (GE Healthcare). Results: The mean age of the patients was 57 (range, 12-86) years. Indications for breast imaging included: breast mass (83%), breast tenderness (10%), nipple discharge (5%), and inverted nipple (3%). Mammographic examination was performed in 49 patients, and sonographic examination in 71. Biopsies were obtained from 19 patients. In 18 patients, no abnormality was found. The imaging I pathological diagnoses in the remainder were categorised as benign or malignant. Benign lesions included: gynaecomastia (n = 42), lipoma (n = 2), fibrocystic change (n = 2), and epidermal inclusion cyst (n = 1). Malignant lesions included: carcinoma (n = 6) and Paget's disease (n = 1). The clinical presentations and salient imaging features of these patients are discussed. Conclusion: Based on knowledge of mammographic and sonographic features of the common benign and malignant lesions of the male breast, accurate radiological diagnoses can be achieved and unnecessary biopsy procedures can be avoided.
    No preview · Article · Jan 2011 · Hong Kong Journal of Radiology
  • S.Q.H. Chou · K.S. Tse · W.K. Wong · S.C.H. Chan
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    ABSTRACT: Gastrointestinal stromal tumours are specifically diagnosed by the demonstration of a specific marker profile with the expression of c-kit and CD34. It is the most common mesenchymal tumour of the gastrointestinal tract. Extragastrointestinal stromal tumours are rare and those with bone metastases are even rarer.
    No preview · Article · Jan 2010 · Journal of the Hong Kong College of Radiologists
  • K.Y. Kwok · H.S. Fung · L.F. Chiu · K.M. Chu · J.C.W. Siu · K.H. Lai · T.S. To · S.C.H. Chan
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    ABSTRACT: Immunoglobulin G4-related sclerosing disease is a recently advocated disease entity. Though initially described as giving rise to autoimmune pancreatitis, this condition was subsequently found to involve extra-pancreatic tissues as well. In this report, we present a case of extra-pancreatic immunoglobulin G4-related sclerosing disease of the breast, with relevant imaging features on mammography, ultrasound, and magnetic resonance imaging.
    No preview · Article · Jan 2010 · Journal of the Hong Kong College of Radiologists
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    ABSTRACT: Objectives: Malignant spinal cord compression is an uncommon complication in patients with cancer. It is frequently diagnosed late and causes irreversible damage to spinal cord. Malignant spinal cord compression is an oncological emergency, requiring a prompt imaging diagnosis and immediate treatment. Magnetic resonance imaging has a vital role in the management of such patients. Our audit was to assess whether patients with malignant spinal cord compression were recognised, investigated, and treated appropriately in our hospital. Large international audits of malignant spinal cord compression, such as clinical resource and audit group, were used as our reference standards. We also compared the level of spinal cord compression inferred clinically and based on magnetic resonance imaging findings, and evaluated whether localised spinal magnetic resonance imaging based on clinical assessment as adopted in our routine magnetic resonance imaging protocol was appropriate. Methods: From January to December 2008, 1087 patients underwent magnetic resonance imaging scans of the spine in our hospital. Of these, 106 patients presented with clinical features suspicious of malignant spinal cord compression and urgent magnetic resonance imaging spine was performed. The demographic factors, primary tumour pathology, Tokuhashi score, clinical symptoms, clinical suspicion of the level of cord compression, magnetic resonance imaging findings, treatment response, and prognosis were assessed retrospectively from the medical records, the electronic Patient Record, and imaging reports from the Radiology Information System. Results: Among the patients with a clinical suspicion of malignant spinal cord compression, prevalence rates were higher in males (61%) and older persons (mean age, 63 years; standard deviation, 14 years). Lung cancer was the most common responsible primary tumour in males (38%), whereas breast cancer was the most common primary tumour in females (32%). Spinal cord compression was the initial presentation of malignancy in 6 (8%) patients. Most patients showed evidence of bone metastasis (53%) and metastasis in major internal organs (51%) prior to the clinical presentation of malignant spinal cord compression. The most common clinical symptoms of malignant spinal cord compression were back pain (77%), limb weakness (94%) and numbness (90%). Of the 106 patients, 43% showed a low Tokuhashi score (<5) during admission. 77% of patients with a clinical suspicion of malignant spinal cord compression had magnetic resonance imaging spine in our hospital within 24 hours; the upper thoracic spine was the most common level of cord compression among these patients, and multilevel compression occurred in 8% of them. There was considerable discrepancy between the level of spinal cord compression inferred clinically and that determined by magnetic resonance imaging (57%); the average level of discrepancy being 5 vertebral bodies (95% confidence interval, 4-6). A greater degree of discrepancy was evident in patients with multiple spinal metastases (p < 0.05). 89% of patients with a clinical suspicion of malignant spinal cord compression had received steroids. The mean time required for starting definitive treatment after confirmation of the diagnosis by magnetic resonance imaging was 1.3 (standard deviation, 0.5) days; 74% were treated within 24 hours of the imaging. Patients with malignant spinal cord compression had an unsatisfactory survival rate of 75% at hospital discharge; the median survival time from first clinical presentation was 37 days (range, 9-884 days). The majority (57%) of patients showed clinical improvement after radiotherapy. Conclusion: Patients with malignant spinal cord compression in our hospital were recognised, investigated, and treated appropriately. Our results were comparable to those reported in the literature. We found a great discrepancy between the level of spinal cord compression inferred clinically and by magnetic resonance imaging, particularly when multiple spinal metastases were present. We concluded that localised magnetic resonance imaging of the spine based on clinical findings was inadequate. Our magnetic resonance imaging protocol for malignant spinal cord compression patient was modified based on the results of this study.
    No preview · Article · Jan 2010 · Journal of the Hong Kong College of Radiologists
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    H S Fung · S Lau · M K Chan · K W Tang · YL Cheung · S C H Chan
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    ABSTRACT: A persistent sciatic artery is a rare embryological anomaly. We report a case of a persistent sciatic artery with aneurysm formation and thrombosis in a patient with rheumatoid arthritis/systemic lupus erythematosus overlap syndrome and Raynaud's phenomenon. The diagnosis and complete, accurate evaluation of the arterial anatomy of the lower limb were achieved using computed tomographic angiography.
    Preview · Article · Jan 2009 · Hong Kong medical journal = Xianggang yi xue za zhi / Hong Kong Academy of Medicine
  • S.S.M. Lo · Y.L. Cheung · K.W. Tang · C.M. Chan · C.W. Siu · K.Y. Kwok · S.C.H. Chan
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    ABSTRACT: Developmental venous anomaly (also known as venous angioma or venous malformation) is one of the 4 main vascular malformations. Developmental venous anomaly is usually benign and clinically silent. This report is of a patient with cerebellar developmental venous anomaly with draining vein thrombosis, complicated by non-haemorrhagic venous infarct of the midbrain.
    No preview · Article · Jan 2009 · Journal of the Hong Kong College of Radiologists
  • H.S. Fung · S. Lau · K.S. Tse · J.W.C. Wai · W.K. Wong · K.W. Tang · S.C.H. Chan
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    ABSTRACT: Focal fatty replacement of the pancreas is a rare benign disease that has been associated with obesity, diabetes mellitus, chronic pancreatitis, hereditary pancreatitis, and obstruction of the pancreatic duct. This report of a 48-year-old woman with focal fatty replacement of the pancreas illustrates the typical imaging findings on chemical shift magnetic resonance imaging. The differential diagnosis and a review of literature are discussed.
    No preview · Article · Jan 2009
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    ABSTRACT: Head injury is common and can be associated with significant morbidity and mortality. We report a 71-year-old man with typical imaging findings of depressed skull fracture on plain film and computed tomography with images in multi-planar reformat and 3-dimensional volume rendering technique, followed by a brief review of the literature.
    No preview · Article · Apr 2008 · Hong Kong Journal of Emergency Medicine
  • H.S. Fung · S. Lau · J.C.W. Siu · C.M. Chan · S.C.H. Chan
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    ABSTRACT: Objective: To determine the utility and accuracy of ultrasonography for the diagnosis of acute appendicitis. Methods: In this retrospective study, 242 of 286 patients undergoing ultrasonography of the appendix from 1 June 2006 to 31 December 2006 were included. The ultrasonography report, pathology report, and clinical notes were reviewed. The pathology report was used as the gold standard for a diagnosis of acute appendicitis. Results: The overall rate of visualisation of the appendix was 41.7%. Fifty six patients (23%) had a positive diagnosis of acute appendicitis by ultrasonography, 45 (19%) had a negative diagnosis, and 141 (58%) had an inconclusive diagnosis; 17 patients (7%) had an alternative diagnosis suggested by ultrasonography. Twenty nine patients (12%) underwent computed tomography on the basis of the ultrasonography report, 6 of whom had a positive diagnosis for acute appendicitis, 5 had a negative diagnosis, and 18 had an alternative diagnosis suggested by computed tomography. The sensitivity, specificity, positive predictive value, and negative predictive value of ultrasonography for acute appendicitis were 75.9%, 89.7%, 73.2%, and 91.0%, respectively, after adjusted calculation for the group with an inconclusive ultrasonography diagnosis. Conclusions: The performance of ultrasonography for investigation of acute appendicitis at the Queen Elizabeth Hospital, Hong Kong, is comparable to the data reported in the literature. Ultrasonography is a useful and safe imaging modality for investigation of acute appendicitis, and computed tomography has a complementary role for the diagnosis of acute appendicitis and management of patients with right lower quadrant pain.
    No preview · Article · Jan 2008 · Journal of the Hong Kong College of Radiologists
  • H.S. Fung · S. Lau · A.M.W. Wai · A.K.H. Lai · M.K. Chan · W.K. Wong · S.C.H. Chan
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    ABSTRACT: Gunshot injury is a serious but uncommon type of trauma in Hong Kong. This report describes 2 cases of gunshot injury, 1 by a handgun and 1 by a shotgun. The literature is reviewed, with emphasis on important imaging features and associated forensic implications.
    No preview · Article · Jan 2008 · Journal of the Hong Kong College of Radiologists
  • K.Y. Kwok · K.S. Tse · S.S.M. Lo · T.K. Tsang · A.M.W. Wai · H.S. Fung · S.C.H. Chan
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    ABSTRACT: Myocardial rupture is one of the major complications of myocardial infarction. This report is of a patient with myocardial rupture complicating myocardial infarction. As well as reviewing the clinical details of myocardial rupture, the ability of contrast computed tomography scan to diagnose acute myocardial infarction is discussed.
    No preview · Article · Jan 2007 · Journal of the Hong Kong College of Radiologists
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    ABSTRACT: To review the results of endovascular treatment of acute thoracic aortic diseases in a group of Chinese patients. Retrospective study. A tertiary referral hospital with a cardiothoracic surgery service. All 15 patients presenting with acute thoracic aortic diseases between September 2001 and October 2005 inclusive, of whom eight had traumatic rupture, four had complicated acute dissections, two had mycotic aneurysms, and one an aneurysm with an aortobronchial fistula. Thoracic aortic stent grafting. Immediate success, 6-month and 1-year survival rates. The median follow-up period was 20.6 months (range, 0-50.1 months). Stent grafts were deployed with immediate success in all patients. Two patients had ancillary bypass surgery for the supra-aortic branches. There were two in-hospital deaths. Four sustained access artery injury and needed graft repair. Computed tomography at 1 month showed complete thrombosis of the aneurysmal lumen or the thoracic aortic false lumen in 12 of 13 survivors. Computed tomography at 6 months showed complete thrombosis of the aneurysmal lumen or the false lumen in nine of 10 patients due for follow-up. Both 6-month and 1-year survival rates were 87%. Thoracic aortic stent grafting for acute thoracic aortic disease is feasible and has a high success rate, with good short-to-midterm results. However, the large size of the stent graft introducer set imposes a high risk of access artery injury, for which further improvements are necessary.
    Preview · Article · Nov 2006 · Hong Kong medical journal = Xianggang yi xue za zhi / Hong Kong Academy of Medicine
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    H L J Mak · P C H Kwok · H H L Chau · M K Chan · S C H Chan · S C S Chan
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    ABSTRACT: To evaluate the medium-term results of uterine fibroid embolisation in Chinese women with symptomatic uterine fibroids. Prospective case series study. Gynaecology and Interventional Radiology units in a public hospital, Hong Kong. Patients with symptomatic fibroids who underwent uterine fibroid embolisation in Queen Elizabeth Hospital from October 1998 to June 2004. Fifty women (mean age, 42.9 years; median follow-up period, 27.5 months) were recruited. Most (82%) had menorrhagia as the chief presenting symptom. Embolisation was successful in 49 (98%) women. Complications occurred in 12 (24%) patients, but were all self-limiting. Significant decrease in the median clinical uterine size (14 weeks vs 10 weeks) and median volume of the largest fibroid on magnetic resonance imaging (157.9 mL vs 45 mL) were observed during the first year. The reduction seemed to be maintained till the last follow-up. Menorrhagia improved in 34 (84%) patients, dysmenorrhoea in 28 (88%), pelvic pain in 18 (82%) and abdominal mass in 15 (83%). Poor response was found for urinary symptoms (29% improvement). Eight (16%) patients underwent hysterectomies after uterine fibroid embolisation. On logistic regression analysis, the only significant predictive factor for symptomatic improvement was fibroid volume reduction at 6 months (P=0.03). Uterine fibroid embolisation is an effective uterine-preserving therapy in patients with symptomatic fibroids; overall symptomatic improvement was estimated as 80%. Uterine or fibroid size reduction correlated well with clinical outcome. The impact of uterine fibroid embolisation on young women wishing to conceive is yet to be determined.
    Preview · Article · Nov 2006 · Hong Kong medical journal = Xianggang yi xue za zhi / Hong Kong Academy of Medicine
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    ABSTRACT: Foreign body ingestion is not uncommon but the majority of foreign objects ingested traverse the gastrointestinal tract without complications. We report a case of retroperitoneal abscess in a 38-year-old man following perforation of the colon by an ingested toothpick.
    No preview · Article · Jan 2005 · Journal of the Hong Kong College of Radiologists