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C H Thng

Publications and source records attributed to C H Thng.

18 recordsLinked to original sources
PubMed2005

Clinical mimicry of hepatocellular carcinoma: imaging-pathological correlation.

This pictorial essay aims to show the clinical mimicry of hepatocellular carcinoma (HCC) and its diagnostic difficulty, and to create awareness among clinicians and radiologists of potential diagnostic pitfalls. A selected consecutive series of hepatectomies with proven HCC over a three-year period, identifying clinical presentation, blood results and imaging of patients with difficult preoperative diagnosis, was reviewed. The imaging of the focal liver lesions is presented pictorially with pathological correlation. Six patients out of 34 cases of resected HCC were diagnosed to have benign (three liver abscesses) and neoplastic (one Klatskin tumour, one colorectal liver metastasis, one gallbladder cancer) conditions. Compared to the rest in the series, all six patients had normal serum alpha fetoprotein levels. On computed tomography, the mosaic appearance of HCC mimicked locules of liver abscess while HCC with pseudocapsule (rim enhancement) was misdiagnosed as unilocular abscess or metastatic lesion. Arterial enhancement on contrast-enhanced triphasic computed tomography was useful in diagnosis of HCC. In summary, HCC can mimic benign and neoplastic clinical syndromes. The diagnosis of liver abscess can delay subsequent diagnosis of HCC and potentially complicate the treatment plan. Contrast-enhanced triphasic computed tomography or magnetic resonance imaging is useful to resolve difficult diagnosis, especially when the serum alpha fetoprotein level is not raised.

Aged↗
PubMed2005

Focal nodular hyperplasia presenting as acute abdomen.

Focal nodular hyperplasia (FNH) is a benign liver tumour with an asymptomatic course, rarely causing complications. When the diagnosis is certain, only watchful observation is necessary. We highlight an interesting case of a 42-year-old woman with a FNH that ruptured and became haemorrhagic, thus presenting as an acute surgical abdomen. The diagnosis was only established after surgical resection with histopathological confirmation. Although haemorrhage of hepatic FNH is extremely rare, this case highlights the small risk of rupture in large lesions.

Abdomen, Acute↗
PubMed2005

Sclerosing haemangioma mimicking hepatocellular carcinoma.

Sclerosing haemangioma is a rare variant of hepatic haemangioma. The radiological features on computed tomography and magnetic resonance imaging may not be typical for haemangioma and can be confused with hepatocellular carcinoma. We report sclerosing haemangioma occurring in a 65-year-old woman where the radiological features raise the possibility of hepatocellular carcinoma.

Aged↗
PubMed2004

Endorectal magnetic resonance imaging and spectroscopy for the detection of tumor foci in men with prior negative transrectal ultrasound prostate biopsy.

PURPOSE: We determined the ability of combined endorectal magnetic resonance imaging (MRI) and magnetic resonance spectroscopic imaging (MRSI) to detect prostate cancer foci prospectively in men with prior negative transrectal ultrasound (TRUS) prostate biopsy. MATERIALS AND METHODS: Endorectal MRI with spectroscopy was performed in 24 consecutive patients with 1 or more prior negative TRUS prostatic biopsies for persistently increased prostate specific antigen and/or abnormal digital rectal examination. All studies were interpreted by a dedicated radiologist who reported areas of interest in the peripheral zone as normal, equivocal or suspicious on MRI and MRSI separately. Equivocal and suspicious areas were then correlated with a 3-dimensional prostate model. All patients underwent a standard TRUS 10-core peripheral zone biopsy with up to 4 additional biopsies targeted at the equivocal or suspected sites. RESULTS: Prostate cancer was detected in 7 of 24 subjects (29.2%). Considering the equivocal category as test negative the sensitivity, specificity, positive and negative predictive values, and the accuracy of MRI, MRSI and combined MRI/MRSI for the detection of prostate cancer were 57.1%, 57.1% and 100.0%, 88.2%, 82.4% and 70.6%, 66.7%, 57.1% and 58.3%, 83.3%, 82.1% and 100%, and 79.2%, 75.0% and 79.2%, respectively. The site of positive biopsy correlated correctly in 50% and 28.6% of MRI and MRSI labeled suspicious cores, respectively. CONCLUSIONS: MRI and MRSI have the potential to identify cancer foci and direct TRUS in patients with a previous negative TRUS biopsy. Further, larger studies are required to quantify the amount of benefit.

Aged↗
PubMed2003

Radiologists' detection of mammographic abnormalities with and without a computer-aided detection system.

The aim of this study was to to evaluate the role of a computer-aided program (CAD) in assisting detection of mammographic lesions by radiologists not specifically trained in mammography and its potential utility in breast screening. Mammograms were evaluated by radiologists not specifically trained in mammography first without, and then with, the CAD. Finally, the mammograms were evaluated by experienced mammographers who formed the reference standard. Two hundred and ninety four breasts were studied. In 257 breasts (87.4%), the CAD system did not help with the detection of abnormalities. It assisted radiologists in detecting abnormalities in 21 breasts (7.1%) with potential for detecting abnormalities in a further 13 breasts (4.4%). Only in three cases (1%) did it cause confusion in interpretation. There is overall increased sensitivity in detecting mammographic abnormalities with the aid of the CAD system from 74.4 to 87.2%, which is statistically significant. However, it failed to detect suspicious abnormalities in 71 breasts (24.1%). The CAD system improved detection of suspicious mammographic abnormalities by radiologists who are not specifically trained in mammography. However, there is also a substantial failure to detect suspicious mammographic features that cautions against over-reliance on the system, emphasizing its role as a second reader at best.

Breast Neoplasms↗
PubMed2003

Current status in imaging of colorectal liver metastases.

Colorectal cancer is a common malignancy that often metastasizes to the liver. Evaluation of the liver for metastases is important for staging and prognosis. Resection of limited hepatic metastases can result in prolonged survival. Imaging is vital to select appropriate patients to avoid unnecessary surgery. A variety of modern imaging tools can be used to detect and characterise hepatic lesions. These include contrast enhanced helical computed tomography (CT), CT arterial portography, magnetic resonance imaging (MRI) and intraoperative ultrasound (IOUS). Each has their advantages as well as disadvantages. Besides accuracy, availability, cost and presence of expertise determine the optimal modality or combination of modalities to use. The appearance of metastases on imaging can be correlated with histopathological abnormalities. Though metastases can often be distinguished from benign lesions, their appearances are by no means pathognomonic. Follow-up imaging for interval change and for assessment of response is often required.

Colorectal Neoplasms↗
PubMed2003

Computed tomographic appearance of colorectal hepatic metastases.

INTRODUCTION: This article reviews the various computed tomography (CT) appearances of hepatic metastases from colorectal primaries and assesses the frequency of occurrence of the various patterns. MATERIALS AND METHODS: This is a retrospective study of the CT appearances of histologically proven colorectal hepatic metastases in a group of 52 patients who had undergone surgical hepatic resection between January 1994 and December 2001. A total of 74 hepatic metastatic lesions were reviewed. All lesions were examined in the portal venous phase. RESULTS: A discernible rim was seen in 54 lesions (73%). Thick rim was present in 36 lesions (48.6%) and thin rim in 18 lesions (24.3%). Enhancement of the rim was present in 62 cases (83.8%). Increased central attenuation was seen in 38 lesions (51.4%). Of these, the centre was heterogeneous in 76.3% and scar-like in 23.7%. A non-enhancing rim was seen in 12 lesions (16.2%) which appeared as lesions with "bevelled edge". Thick enhancing rim with non-enhancing centre was the most common combination in 15 lesions (20.3%). CONCLUSION: An enhancing rim could be seen in 83.8% of lesions. Increased central attenuation was present in 51.4% of the lesions. Familiarity with the various CT appearances may facilitate identification and diagnosis of colorectal liver metastases.

Adult↗
PubMed2003

Breath-hold fast recovery fast spin echo versus conventional non-breath-hold fast spin echo T2-weighted MR imaging of focal liver lesions.

INTRODUCTION: We compare the breath-hold fast recovery fast spin echo (BHFRFSE) T2-weighted and non-breath-hold fast spin echo (NBHFSE) T2-weighted sequences in image quality and lesion characterisation of focal liver lesions. MATERIALS AND METHODS: Fat-suppressed T2-weighted magnetic resonance (MR) images obtained with the 2 sequences (BHFRFSE and NBHFSE) in 79 patients with 113 liver lesions were analysed retrospectively. The image quality and nature of the lesions were evaluated by 2 experienced radiologists. RESULTS: Based on receiver operating characteristic curve analysis, lesion characterisation was comparable for both sequences. The image quality of BHFRFSE was significantly better than that of NBHFSE. The NBHFSE missed 4 malignant lesions while BHFRFSE missed 2 malignant lesions. CONCLUSION: BHFRFSE performs similarly to NBHFSE in image quality and liver lesion characterisation.

Adult↗
PubMed2003

MR imaging and MR spectroscopy of adenocarcinoma of the prostate.

INTRODUCTION: We examined the impact of magnetic resonance (MR) imaging and MR spectroscopy on the diagnosis and management of prostate cancer. METHODS: A Medline search was performed and the relevant articles reviewed. The salient points are discussed and summarised. RESULTS: MR imaging with phased-array and endorectal coils is not recommended for routine staging. It has a complementary role in improving the accuracy of local staging in patients with intermediate risk based on Partin's normogram. MR spectroscopy can be performed in conjunction with high-resolution anatomic MR imaging of the prostate. It exploits the increased choline and decreased citrate levels within malignant prostatic tissue compared with normal prostatic tissue, and can potentially improve the assessment of cancer location and extent within the prostate, as well as extracapsular spread in small retrospective studies. It also has the potential of providing a measure of the presence and extent of prostate cancer after therapy. CONCLUSION: MR imaging is indicated in staging patients with intermediate risk based on Partin's normogram. Combined MR imaging and MR spectroscopy of the prostate is a promising imaging tool which can contribute to the diagnosis and management of prostate cancer when combined with clinical, biochemical and histological data. Large prospective studies must be performed to ascertain the true clinical value of combined MR imaging/MR spectroscopy for the management of prostate cancer patients.

Adenocarcinoma↗
PubMed2003

Clinical applications of MR cholangiopancreatography.

INTRODUCTION: We review the clinical applications of magnetic resonance cholangiopancreatography (MRCP) and illustrate them with clinical examples. METHODS: A literature search was performed in MedLine using the keywords "MR cholangiopancreatography" and "MRCP". The relevant articles were reviewed. The radiology information system was searched for MRCP examinations performed from July 1999 to December 2002. A surgical database of resected cases was also referenced. Illustrative cases were chosen in consultation with surgical authors to show the clinical applications of MRCP. RESULTS: MRCP is useful for assessment of choledocholithiasis, choledochal cysts, pancreas divisum, primary sclerosing cholangitis, pancreatitis and anatomical variation of the biliary ducts. When complemented with dynamic gadolinium-enhanced studies, MRCP is useful for assessment of ductal cholangiocarcinoma, pancreatic and gall bladder neoplasms. Illustrative cases are provided. CONCLUSION: MRCP is an important modality for the clinical assessment of biliary and pancreatic disorders.

Bile Duct Neoplasms↗
PubMed2003

Percutaneous drainage of liver abscess complicated by hepato-venous fistula.

Severe systemic sepsis after percutaneous drainage of liver abscess is rare. We report two cases of hepato-venous fistulas between hepatic abscesses and hepatic/portal veins documented on abscessography during percutaneous drainage of liver abscesses, which resulted in severe sepsis and a stormy post drainage clinical course. Liver abscesses can rupture into the portal and hepatic veins causing worsening of systemic sepsis especially when they are in close proximity to each other. During percutaneous drainage, care must also be taken to avoid overinjection of the abscess, which can worsen the fistula. The ensuing sepsis is severe and requires aggressive intensive medical care and ventilatory support to tide the patient over the septic episode.

Aged↗
PubMed2002

Diffusion weighted MR imaging in acute stroke: the SGH experience.

Cerebrovascular accident (CVA) is a leading cause of death and disability in many countries. Diffusion-weighted (DW) magnetic resonance (MR) imaging has been reported to be useful in the detection of acute strokes and as an investigative tool evaluating the therapeutic effects of neuroprotective and thrombolytic agents. The objectives of this study are to share our experience using the commercially available isotropic DW scan in imaging of acute stroke, assess its usefulness over conventional T2-weighted (T2W) scans in a busy clinical radiology unit and highlight it pitfalls. We found the rapid sub-minute DW technique well suited for ill and restless stroke patients and superior to T2W scans in many ways. It was highly sensitive to acute ischaemic lesions, made lesions easily identifiable and readily differentiated the acute lesion from a background of multiple chronic infarcts. However, there are potential pitfalls in the evaluation of small hyperacute posterior fossa strokes and venous infarcts. The major strength of this MR technique lies in its ability to diagnose hyperacute strokes and thence the potential for therapeutic thrombolysis, but unfortunately patients qualifying for the "therapeutic window" were a minority. More efforts need to be focused on public education in order for this powerful imaging modality to find its true value and contribute to viability of an effective thrombolytic programme.

Adult↗
PubMed2000

Retreatment with chimeric CD 20 monoclonal antibody in a patient with nodal marginal zone B-cell lymphoma.

A patient with advanced and chemotherapy-refractory nodal marginal zone B-cell lymphoma was given a course of chimeric CD 20 monoclonal antibody Rituximab. Partial response was observed without any major toxicities. Retreatment with Rituximab for disease progression six months after the first course led to partial remission. Adjuvant radiotherapy was given for the residual disease and, currently, patient's disease remains stable eight months after the second course of Rituximab. This case demonstrates the therapeutic efficacy and feasibility of retreatment with Rituximab for relapsed or refractory low grade lymphoma.

Antibodies, Monoclonal↗
PubMed1999

Predicting the size of a double-lumen endobronchial tube using computed tomographic scan measurements of the left main bronchus diameter.

UNLABELLED: We investigated the use of chest computer tomographic (CT) scan measurement of the left mainstem bronchial diameter to predict the correct left-sided double-lumen endobronchial tube (DLT) size in Asian patients who may require smaller DLT sizes. Fifty consecutive Asian adults aged 17-80 yr with preoperative chest CT scans undergoing elective thoracic surgery were entered into the study. The measurements of the left main bronchus diameter were made by using the electronic calipers of the spiral scanner to the nearest millimeter. The sizes of DLT selected were 32F, 35F, 37F, 39F, and 41F for left main bronchus diameters of <10 mm, 10 mm, 11 mm, 12 mm, and >12 mm, respectively. All DLT placements were confirmed and positioned by using fiberoptic bronchoscopy. The tracheas of all patients were successfully intubated with the predicted DLT sizes. Thirty-four patients (68%) were predicted to require smaller DLTs (37F or smaller). Six patients were correctly predicted to receive 32F DLTs. Twelve patients (24%) received an oversized DLT, but none received an undersized DLT. The overall positive predictive value for the male and female patients was 84.4% and 61.1%, respectively. Our study showed that CT scan measurements of the diameter of the left bronchus were especially useful in choosing smaller DLTs. IMPLICATIONS: We used computer tomographic scans to measure the diameter of the left mainstem bronchus, then selected the size of the left-sided double-lumen endobronchial tube (DLT) accordingly. We found that we could predict the sizes of the DLT fairly accurately, especially the smaller DLTs.

Adolescent↗
PubMed1999

Magnetic resonance imaging of brain metastases: magnetisation transfer or triple dose gadolinium?

Magnetic resonance (MR) imaging of brain metastases relies on the neovascularity of metastases and the associated breach of blood-brain barrier manifesting as enhancement on T1-weighted images. There are 2 main strategies to improve the detection of brain metastases. One may increase the dose of gadolinium and increase the signal of the lesion. Alternatively, one may also lower the signal of the background (by magnetisation transfer suppression), in which case the enhancing lesion is rendered more conspicuous without increasing the dose of gadolinium. We aim to compare the efficacy of single-dose conventional spin-echo T1 scans with magnetisation transfer (MT) suppression with triple-dose conventional spin-echo T1 scans in the detection of brain metastases in 18 patients undergoing imaging for brain metastases. An incremental dose technique was employed. After administration of a single dose of gadolinium, MT suppressed T1-weighted scans were obtained, followed by a conventional T1 scan. Two doses of gadolinium were subsequently given, achieving a cumulative triple-dose, and a conventional T1-weighted scan was then performed. We found single-dose MT suppressed and triple-dose scans performed equally well and detected 26 metastatic lesions. They detected 5 (5/26, 19%) more lesions than the conventional single-dose T1 scans. Five (5/21, 24%) questionable lesions on single-dose conventional scans were confidently diagnosed on the single-dose MT suppressed and the triple-dose conventional scan. We conclude that single-dose MT suppressed scans are a cost-effective technique of detecting brain metastases.

Adult↗
PubMed1997

Abdominal computed tomography in systemic lupus erythematosus.

Sixty-five abdominal computed tomography (CT) scans of 54 systemic lupus erythrematosus (SLE) patients were retrospectively evaluated together with their clinical records. This was to assess the spectrum of CT findings and to determine the value of abdominal CT in this group of patients. Over a 3.5-year period, abdominal CT scans had been requested for suspected renal vein or inferior vena cava thrombosis (n = 52, 80%), sepsis, mesenteric ischaemia, Conn's syndrome, evaluation of hepatosplenomegaly, portal hypertension and hydronephrosis. The most frequent indication for CT was suspected renal vein thrombosis (RVT). An SLE patient with previously stable renal function who rapidly develops nephrotic syndrome with deteriorating renal function has an increased risk of thromboembolic phenomenon. Also, renal vein thrombosis is difficult to diagnose clinically and prompt anticoagulation can help preserve remaining renal function. Of these with suspected RVT, two had RVT only and five had thrombosis in both renal veins and inferior vena cava. Two patients had CT features strongly suggestive of mesenteric ischaemia, one had bilateral hydronephrosis thought to be secondary to lupus cystitis and CT confirmed two abdominal abscesses. Other incidental CT findings were: subscapular renal haematoma, overall enlargement or diminution of renal size, serositis, bowel wall thickening, splenic, hepatic and pancreatic enlargement and mild para-aortic lymphadenopathy. Abdominal CT revealed many diverse findings and aided the management of these SLE patients.

Adolescent↗