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B S Tan

Publications and source records attributed to B S Tan.

At least 19 recordsLinked to original sources
PubMed2003

Clinical utility of selective intra-arterial calcium-stimulated hepatic venous sampling in regionalisation of insulinomas--the Singapore experience.

INTRODUCTION: To evaluate the efficacy and safety of selective intra-arterial calcium-stimulated hepatic venous sampling (ASVS) as a preoperative regionalisation modality for insulinomas. DESIGN AND METHODS: Four patients with biochemically-proven endogenous hyperinsulinism and negative spiral computed tomographic (CT) pancreas were subjected to ASVS between October 1999 to May 2001. Results obtained from ASVS were compared with localisation studies using either magnetic resonance imaging (MRI) or endoscopic ultrasonography (EUS); and these were confirmed surgically whenever possible. RESULTS: ASVS led to a definitive regionalisation in all 4 patients evaluated; the predicted location of the insulinoma matched the findings intraoperatively in all 3 patients who were operated upon. These were all proven to be insulinoma histologically. However, 1 patient showed a positive ASVS result in samples obtained from the left hepatic vein only. In the patient who was unable to undergo surgical resection due to other co-morbid factors, his ASVS findings were corroborated by localisation obtained from the MRI study. Conversely, EUS was found to give an incorrect localisation of insulinoma in 1 patient. Adverse effects were encountered in 3 patients (2 with mild hypotension and 1 with transient atrial fibrillation); however, premature termination of the procedure was not necessary in any of the patients. CONCLUSION: ASVS is accurate and reliable for regionalisation of insulinoma, especially in patients who do not have an obvious, unequivocal tumour using high quality current-generation MRI scans.

Adult↗
PubMed2003

Colorectal hepatic metastases: Role of radiofrequency ablation.

INTRODUCTION: Radiofrequency ablation (RFA) is a new minimally invasive treatment that has been increasingly used in the treatment of liver metastases. This review aims to outline the principles governing the use of RFA and to examine its role when applied to the management of colorectal liver metastases. METHODS: A Medline search of experimental and clinical studies relating to the use of RFA in the management of colorectal hepatic metastasis was carried out. RESULTS: RFA is currently used as an alternative to surgery in patients with unresectable disease, and sometimes as its companion, allowing patients hitherto considered unsuitable for resection to become surgical candidates. RFA has been shown to be safe and well tolerated, with few major complications and minimal patient discomfort. Although its use is unlikely to achieve cure in such patients, it has a definite role in palliation and relief of symptoms. Long-term data, when these become available, may also show improved survival. However, because RFA is a local ablative therapy, it does not address the progressive and systemic nature of colorectal carcinoma. CONCLUSIONS: RFA is an important alternative/complimentary tool in the management of colorectal hepatic metastases. Combining RFA with surgery or chemotherapy may reduce the incidence of local and systemic relapse.

Catheter Ablation↗
PubMed2002

Outcome of percutaneous nephrostomy for the management of pyonephrosis.

OBJECTIVE: The aim of this study was to evaluate the efficacy of percutaneous nephrostomy (PCN) drainage for the interim management of pyonephrosis. METHODS: Ninety-two consecutive patients [29 men, 63 women; mean age, 57 years; range, 23 to 88] who underwent PCN for the treatment of pyonephrosis from 1996 to 1999 were evaluated retrospectively. The clinical presentation, bacteriology and patient outcomes were analyzed. RESULTS: The majority [77%] of patients had underlying obstructing urinary calculi. Other causes of obstruction included strictures [9%], papillary necrosis [7%], pelvi-ureteric junction obstruction [4%] and malignant stricture [3%]. The microorganisms cultured were Escherichia coli [30%], Klebsiella [19%], Proteus [8%], Pseudomonas [5%], Enterococcus [5%], and Candida spp [5%]. The microorganisms were sensitive to gentamicin [79%], ceftriaxone [71%], cephalexin [54%], nitrofurantoin [40%], cotrimoxazole [35%], nalidixic acid [32%] and ampicillin [29%]. Only 30% of bladder urine cultures were positive for microorganisms; the addition of PCN cultures improved this yield to 58%. The antibiotic regimen was revised according to the PCN culture whenever there was a discrepancy. After PCN, 69% of patients underwent minimally invasive procedures as definitive treatment of the obstructing lesion. Only 14% of patients required open surgery. There was low procedure-related morbidity [14%] and low overall mortality [2%]. CONCLUSIONS: PCN cultures yield important bacteriological information. The procedure is associated with minimal morbidity, facilitates definitive treatment and provides therapeutic benefit.

Adult↗
PubMed2002

Single centre review of radiologically-guided percutaneous nephrostomies: a report of 273 procedures.

INTRODUCTION: To evaluate the technical success and complications associated with radiologically-guided percutaneous nephrostomies (PCNs) in a single centre. MATERIALS AND METHODS: A total of 273 PCNs performed in 190 patients in our hospital over a 3-year period from January 1997 to December 1999 were retrospectively reviewed. The study population consisted of 97 males and 93 females, ranging in age from 13 to 91 years. The main indications were urinary obstruction (77.7%), pyonephrosis (18.3%) and urinary diversion (4%). Demographic variables, technical and risk factors related to the procedure, complications, effect on urine cultures and body temperature; and subsequent patient management were examined. RESULTS: The technical success rate was 99%. The 30-day mortality was 7.2%, none of which were procedure related. Haemorrhage requiring transfusion occurred in 4.3% while septicaemia affected 3.2% of patients. Drainage catheter complications included catheter dislodgement and blockage which were 11.9% and 4.1%, respectively. Thirty-one per cent of PCNs subsequently underwent ureteric stenting as the definitive treatment modality. CONCLUSION: Radiologically-guided PCN is a safe procedure with a high technical success rate.

Adolescent↗
PubMed2002

A case of uterine artery pseudoaneurysms.

Uterine artery pseudoaneurysms is a rare cause of haemorrhage but is potentially life-threatening and can occur after common gynaecological operations such as a Caesarean section or a hysterectomy. A 33-year-old woman who developed secondary postpartum haemorrhage after a Caesarean section was diagnosed to have uterine artery pseudoaneurysms on ultrasound scan. She was treated with bilateral uterine artery embolisation via selective catherisation of uterine arteries. Good outcome with the aneurysms remaining obliterated was obtained. Angiographic embolisation is a safe and effective method of treating postpartum haemorrhage in haemodynamically stable patients and should be an option before resorting to surgery in appropriately selected cases.

Adult↗
PubMed2001

Health beliefs in oral cancer: Malaysian estate Indian scenario.

This is a study to describe the health beliefs related to oral cancer (OC) in a high-risk group in Malaysia, a predominantly Indian community living in an agricultural setting called an estate. The study population was a convenient sample of 112 adults, above 20 years of age, attending oral cancer screening in two estates. The subjects consisted of 106 (94.6%) Indians and six (5.4%) Malays. Using the Health Belief Model, the perceptions of susceptibility to OC, its severity, and the benefits of and barriers to preventive actions, as well as beliefs underlying OC aetiology were investigated. About half of the subjects (n=57, 50.9%) felt susceptible to oral cancer. A majority of subjects (n=93, 83.0%) felt that oral cancer is a severe disease. Thirty four people (30.4%) perceived OC as a preventable disease, while 56 (50%) did not, and the remaining 22 (19.6%) did not know if OC was preventable or not. The majority of subjects (84.8%) believed that modifications to the betel quid habit could be beneficial. The information solicited can be used as a starting point to design health-education activities aimed at this group in particular and the population in general.

Adult↗
PubMed2001

Diagnostic accuracy of focused appendiceal CT in clinically equivocal cases of acute appendicitis.

PURPOSE: To determine the diagnostic accuracy of modified focused appendiceal computed tomography (CT) to exclude or confirm appendicitis in patients who presented with equivocal symptoms and signs of appendicitis. MATERIALS AND METHODS: One hundred patients (age range, 14-81 years; mean age, 30.6 years) with equivocal symptoms and signs of acute appendicitis were included in this prospective study. Patients were given 30 mL of diatrizoate meglumine and diatrizoate sodium and 60 mL of sorbitol mixed in 1 L of water orally over 1 hour. CT was performed 1.5 hours after the commencement of oral contrast material administration. The criteria used for the diagnosis of appendicitis were (a) appendix greater than 6 mm in maximum diameter, (b) no contrast material in the appendiceal lumen, and (c) inflammatory changes in the periappendiceal fat. CT results were compared with histopathologic findings at appendectomy. Patients with negative CT findings were followed up by telephone or clinically. RESULTS: Of 100 cases, 30 were positive at CT and 70 were negative. There were 28 true-positive cases; two false-positive cases, one cecal diverticulitis and one pelvic peritonitis with periappendicitis; and two false-negative cases, one perforated appendix and one mucosal and submucosal inflammation of the appendix but no transmural inflammation. Sensitivity was 93%, specificity was 97%, and accuracy was 96%. CONCLUSION: Focused appendiceal CT in which oral contrast material is used alone yields high levels of accuracy in clinically equivocal cases of acute appendicitis.

Acute Disease↗
PubMed2001

188rhenium-TDD-lipiodol in treatment of inoperable primary hepatocellular carcinoma--a case report.

INTRODUCTION: The aim of this study was to investigate the potential of using 188Re Lipiodol for selective internal radiation therapy of inoperable hepatocellular carcinoma (HCC). CLINICAL PICTURE: A 33-year-old female with poorly-differentiated multicentric HCC, elevated alpha-fetoprotein (AFP) and increased serum alkaline phosphatase. TREATMENT: Over a 2-month interval, the patient was treated twice with 4GBq of 188Re-TDD-Lipiodol. OUTCOMES: There was good localisation of 188Re Lipiodol in the tumours, but also in thyroid (first treatment) and gastrointestinal tract (both treatments). So far (5 months post-treatment), the patient remains well with stable disease. CONCLUSIONS: 188Re Lipiodol can be an effective radiopharmaceutical for the treatment of HCC; however, more work must be done to minimise the uptake in bowel.

Adult↗
PubMed2001

Acute renal colic: value of unenhanced spiral computed tomography compared with intravenous urography.

OBJECTIVE: The objective of this study was to compare the efficacy of plain spiral computed tomographic (CT) scan with intravenous urography (IVU) in the evaluation of patients with suspected urinary calculi/obstruction. MATERIALS AND METHODS: Twenty consecutive patients with acute signs of renal colic were prospectively examined with unenhanced spiral CT followed by an IVU within the same day. The CT scans were reviewed jointly by 2 radiologists blinded to the IVU and a consensus was reached for each finding. The IVU was similarly reviewed by another 2 separate radiologists. RESULTS: Eleven of the 20 patients had signs of urinary obstruction on CT and IVU. Of these 11 patients, 7 had a ureteric calculus that was demonstrated on CT and IVU and 4 had a calculus that was demonstrated on CT only. Two patients had a urinary calculus seen on CT and IVU with no signs of urinary obstruction. One patient had a calculus seen on CT alone with no urinary obstruction. Two patients only had signs of urinary obstruction on CT. The remaining 4 cases had normal findings on CT and IVU. CONCLUSION: Unenhanced CT is more effective than IVU in identifying ureteric calculi and is equally effective in detecting urinary obstruction. CT is also useful in detecting secondary signs of obstruction even in the absence of any calculus.

Acute Disease↗
PubMed2000

Cold sweats.

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Adult↗
PubMed2000

DNA testing for fragile X syndrome in 255 males from special schools in Singapore.

INTRODUCTION: Fragile X syndrome, the most common cause of inherited mental retardation, results from unstable expansion of a trinucleotide (CGG)n repeat in the FMR1 gene. Phenotypic expression is variable making clinical diagnosis difficult, while diagnosis by Southern blotting is relatively expensive and labour intensive. The prevalence in Singapore has not been studied. MATERIALS AND METHODS: We developed a rapid screening test using a PCR analysis. We studied 255 males with unexplained cause for learning difficulties from 8 special schools. A clinical scoring system based on characteristic features described was devised. RESULTS: PCR analysis showed absence of the band for the normal allele in 11 samples, 6 of which were confirmed by Southern blotting to be positive for FMR1 expansion, giving a 2% false-positive rate with PCR. Sensitivity of the PCR test was evaluated by performing Southern blotting in all PCR-normal samples; all of which were confirmed to be normal. This PCR test was shown to be highly reproducible. Clinical criteria were not predictive. CONCLUSIONS: Six (2.4%) new cases of fragile X syndrome were detected. There is a need to incorporate fragile X testing in routine screening of patients with developmental delay and learning difficulties. The use of PCR could eliminate the need for Southern blotting in up to 95% of cases. PCR analysis provides a simple, reliable and rapid tool for screening.

Adolescent↗
PubMed1999

Partial nephrectomy for renal tumours: the Singapore General Hospital experience.

From January 1991 to August 1998, 220 radical nephrectomies were performed for renal cell carcinoma (RCC). During the same period, 27 patients underwent partial nephrectomy for their renal tumours. These included 19 male and 8 female (mean age, 54; range, 35-75). Their clinical presentation, diagnostic modalities and surgical outcome were evaluated. The lesions included 18 RCCs, 7 angiomyolipomas (AMLs), 1 oncocytoma and 1 dysoncogenetic renal tumour. Only 8 patients had specific urological symptoms. Computerised tomography (CT) scan was diagnostic in 78% of cases. Tumour size ranged from 15-50 mm for RCC and 30-190 mm for AML, respectively. Operative time averaged 92 minutes (range: 35-145). The hospital stay ranged from 3 to 25 days (mean 11). Complications occurred in four cases (14.8%); there was one death (3.7%). No tumour recurrence was detected during a mean follow up of 20 months. None of the patients developed significant renal impairment. Partial nephrectomy is feasible in small RCC and some large AML, and can be offered in selected patients.

Adult↗
PubMed1999

Tissue microangiography using a simplified barium sulphate cadaver injection technique.

This study investigated the application of soft tissue X-ray imaging as a method of studying vascular anatomy in injected cadaveric specimens. The arterial system of the anatomical region of interest was perfused with a barium sulphate-gelatin suspension. After curing, the tissues were removed by meticulous dissection and examined using the soft tissue X-ray imaging system. This technique of microangiography was able to demonstrate the entire arterial system of the perfused specimen. This simplified technique shows great potential in the study of vascular anatomy of flaps.

Angiography↗
PubMed1999

Radiological placement of 211 central venous catheters: outcome and complications.

A prospective study of 211 central venous catheters consecutively placed in 186 patients under radiological guidance was conducted over an 18-month period. The majority (64%) of our patients were at risk for acute complications or failure. These risks included bleeding tendency, distorted anatomy, or previous complicated lines and failed "blind" percutaneous attempts. We employed the subtraction angiographic technique for venous mapping or ultrasound localisation to guide our initial puncture. The accumulated catheter experience was 15,295 days and the median catheter survival time was 166 days. The success rate was 100%. Our acute complications included 1 case of arterial puncture (0.5%), 2 pneumothoraces (1.0%), and 13 patients (6.1%) with haematoma or prolonged oozing at the puncture site. The calculated infection rate was 0.25 episodes per 100 catheter days at risk. These results are comparable to those reported in the literature. We conclude that central venous catheterisation using imaging guidance is accurate and safe, and should be the method of choice especially in high-risk patients.

Adolescent↗
PubMed1999

Outcome of tunnelled central venous haemodialysis catheters inserted by radiologists.

Radiologists have only recently been involved in the percutaneous placement of tunnelled central venous haemodialysis catheters. We report our initial experience with our first 60 catheters. All catheters were successfully inserted. Immediate complications encountered included puncture site haemorrhage in 3 patients (5%) and puncture of the left brachiocephalic vein in 1 patient (1.7%). These were managed conservatively without any clinical sequelae. About 80% of the catheters were uncomplicated and removed electively. Slightly more than 80% of the catheters were in place for more than 30 days. Infection and blocked catheters were the most common short-term complications. Ten catheters (17%) were infected resulting in premature removal of 9. There was 1 death from presumed line sepsis. Mean duration before the onset of infection was 53 days; the rate of infection was 0.28 episodes per 100 catheter days. Five catheters (8%) were blocked or had poor flow. The mean duration before the onset of blockage was 39 days and the rate of blockage was 0.14 episodes per 100 catheter days. A higher proportion of catheters inserted from the left encountered complications. In conclusion, percutaneous insertion of tunnelled haemodialysis catheters by radiologists is safe and effective. The right internal jugular vein should be the preferred access site. Precautions should be taken to avoid infectious complications given the high rate of catheter removal amongst infected catheters.

Catheters, Indwelling↗
PubMed1999

Clinics in diagnostic imaging (44). Testicular tumour with retroperitoneal lymphadenopathy and inferior vena cava thrombosis.

A 20-year-old Indian man presented with a two week history of non-specific abdominal pain. Abdominal ultrasonograpy incidentally detected a thrombus in the inferior vena cava (IVC). Computed tomography revealed the presence of extensive para-aortic lymph node disease as well as a filling defect in the IVC. Scrotal ultrasonography located a heterogeneous intra-testicular tumour in an otherwise palpably-normal testis. The extent of the IVC thrombus was evaluated by the use of magnetic resonance imaging. Inguinal orchidectomy was performed and histology revealed a non-seminomatous germ cell tumour. Combination chemotherapy led to complete resolution of lymph node disease and IVC thrombus. The patient remained well 9 months after diagnosis. The causes of IVC obstruction, role of imaging in investigating IVC obstruction and the management of tumour involvement of the IVC are discussed.

Adult↗