2.Evaluation of imaging performance of major image guidance systems
Chan MF* ; Yang J ; Song Y ; Burman C ; Chan P ; Li S
Biomedical Imaging and Intervention Journal 2011;7(2):1-7
Purpose: The imaging characteristics of two popular kV cone-beam CT (CBCT) and two MVCT systems utilised in
image-guided radiation therapy (IGRT) were evaluated.
Materials and methods: The study was performed on Varian Clinac iX, Elekta Synergy S, Siemens Oncor, and
Tomotherapy. A CT phantom (Catphan-504, Phantom Laboratory, Salem, NY) was scanned for measurements of image
quality including image noise, uniformity, density accuracy, spatial resolution, contrast linearity, and contrast resolution.
The measurement results were analysed using in-house image analysis software. Reproducibility, position correction,
and geometric accuracy were also evaluated with markers in a smaller alignment phantom. The performance evaluation
compared volumetric image properties from these four systems with those from a conventional diagnostic CT (CCT).
Results: It was shown that the linearity of the two kV CBCT was fairly consistent with CCT. The Elekta CBCT
with half-circle 27-cm FOV had higher CT numbers than the other three systems. The image noises of the Elekta kV
CBCT, Siemens MV CBCT, and Tomotherapy fan-beam CT (FBCT) are about 2-4 times higher than that of the Varian
CBCT. The spatial resolutions of two kV CBCTs and two MV CBCTs were 8-11 lp/cm and 3-5 lp/cm, respectively.
Conclusion: Elekta CBCT provided a faster image reconstruction and low dose per scan for half-circle scanning.
Varian CBCT had relatively lower image noise. Tomotherapy FBCT had the best uniformity.
3.Large Volume Osteosarcomas of the Femur Treated with Total Femoral Replacement
Pan KL ; Chan WH ; Shanmugam P ; Ong GB ; Kamaruddin F ; Tan S
Malaysian Orthopaedic Journal 2014;8(1):32-36
Patients with extensive malignancies involving the femur
often require total femoral replacement when their limbs can
be salvaged. Reported series are small and involve
heterogeneity of tumours. We present nine patients with
osteosarcomas of the femur treated at our institution between
2003 and 2010 with a mean follow-up of 27 (6 to 56)
months. Their ages ranged from 9 to 17 (mean 14 years).
They had large volume tumours (mean 911 cm3
) and
presented late with a mean of 5.5 months from the onset of
symptoms to definitive treatment. All patients underwent
resection and total femur replacement. Six patients have
died and two are alive with good function at the time of this
report. One was lost to follow-up. These patients require a
high level of treatment care and have a guarded prognosis
Osteosarcoma
4.Life threatening and occult mediastinal haemorrhage secondary to acquired factor VIII deficiency.
Chieh Suai TAN ; Kenneth P CHAN ; Charles T CHUAH ; Heng Joo NG ; Foong Koon CHEAH ; Felicia S TEO ; Philip C T ENG
Annals of the Academy of Medicine, Singapore 2009;38(3):280-281
Aged
;
Female
;
Hemophilia A
;
complications
;
Hemorrhage
;
etiology
;
Humans
;
Mediastinal Diseases
;
etiology
5.Clinical functional magnetic resonance imaging for pre-surgical planning--the Singapore General Hospital experience with the first 30 patients.
Helmut RUMPEL ; Ling Ling CHAN ; Judy S P TAN ; Ivan H B NG ; Winston E H LIM
Annals of the Academy of Medicine, Singapore 2009;38(9):782-786
<p>INTRODUCTIONFunctional magnetic resonance imaging (fMRI) is a neuroradiological technique for the localisation of cortical function. FMRI made its debut in cognitive neuroscience and then eventually to other clinical applications. We report our experience with pre-surgical fMRI on a high field scanner, based purely on a clinical platform.p><p>MATERIALS AND METHODSThe protocols included motor, auditory, visual and language fMRI. The choice of protocols was dependant on clinical request and lesion locale.p><p>RESULTSRetrospective analysis and audit of the fi rst 30 consecutive patients over a 12-month period revealed that about 85% of patients had a successful examination. In a pictorial essay, we demonstrate that patients with weakness in performing a motor task showed abnormal activations of the pre-motor and supplementary motor areas.p><p>CONCLUSIONFMRI data greatly enhances the pre-surgical planning process and the conduct of surgery when it is incorporated into the surgical navigation system in the operating theatre.p>
Adult
;
Aged
;
Diagnostic Techniques, Neurological
;
Female
;
Hospitals, General
;
Humans
;
Magnetic Resonance Imaging
;
methods
;
Male
;
Middle Aged
;
Preoperative Period
;
Psychomotor Performance
;
physiology
;
Retrospective Studies
;
Singapore
6.Imaging Features of Soft-Tissue Calcifications and Related Diseases: A Systematic Approach.
Zhen An HWANG ; Kyung Jin SUH ; Dillon CHEN ; Wing P CHAN ; Jim S WU
Korean Journal of Radiology 2018;19(6):1147-1160
Soft-tissue calcification refers to a broad category of lesions. Calcifications are frequently identified by radiologists in daily practice. Using a simple algorithm based on the distribution pattern of the lesions and detailed clinical information, these calcified lesions can be systematically evaluated. The distribution pattern of the calcific deposits enables initial division into calcinosis circumscripta and calcinosis universalis. Using laboratory test results (serum calcium and phosphate levels) and clinical history, calcinosis circumscripta can be further categorized into four subtypes: dystrophic, iatrogenic, metastatic, and idiopathic calcification. This pictorial essay presents a systematic approach to the imaging features of soft-tissue calcifications and related diseases.
Calcinosis
;
Calcium
7.Pandemic (H1N1) 2009: clinical and laboratory findings of the first fifty cases in Singapore.
Monica CHAN ; Mark I CHEN ; Angela CHOW ; Caroline P S LEE ; Adriana S H TAN ; David Chien LYE ; Yee Sin LEO
Annals of the Academy of Medicine, Singapore 2010;39(4):267-266
<p>INTRODUCTIONSince the fi rst imported case on 26 May 2009, pandemic (H1N1) 2009 has spread from travellers and has resulted in sustained community transmission. Singapore began with a strict containment policy where all suspected and confirmed cases of pandemic (H1N1) 2009 were admitted for testing. We describe here the clinical and laboratory characteristics of the fi rst 50 adult cases with confirmed pandemic (H1N1) 2009.p><p>MATERIALS AND METHODSA review was conducted of medical notes of adult patients with confirmed pandemic (H1N1) 2009 by polymerase chain reaction assay from combined nasal and throat swabs admitted to the Communicable Disease Centre, Tan Tock Seng Hospital.p><p>RESULTSFrom 26 May to 18 June 2009, 50 patients with a median age of 27 years old were admitted at a median of 3 days from illness onset. Half were male and all were travellers arriving in Singapore. Non-Singaporean citizens (38%) and other ethnic groups (40%) were over-represented. History of fever was reported in 90% and respiratory symptoms in 92%. Gastrointestinal symptoms were uncommon, present in 4% only. Temperatures on presentation of >or=38.0 degrees C, >or=37.8 degrees C and >or=37.5 degrees C were present in 48%, 56% and 76%, respectively. Only 46% of patients met the United States Centers for Disease Control and Prevention (US CDC) case definition of influenza-like illness (ILI). Clinical and laboratory findings were unremarkable for the majority. All cases were treated with oseltamivir and had uncomplicated recovery.p><p>CONCLUSIONPandemic (H1N1) 2009 had mild clinical and laboratory findings in immunocompetent patients. Use of the US CDC ILI criteria alone would have detected less than half of confirmed cases.p>
Adult
;
Communicable Diseases, Emerging
;
epidemiology
;
Disease Outbreaks
;
Female
;
Humans
;
Influenza A Virus, H1N1 Subtype
;
isolation & purification
;
Influenza, Human
;
diagnosis
;
epidemiology
;
Male
;
Medical Audit
;
Middle Aged
;
Polymerase Chain Reaction
;
Singapore
;
epidemiology
;
Young Adult
8.Electrocardiographic Criteria for Left Ventricular Hypertrophy in Asians Differs from Criteria Derived from Western Populations--Community-based Data from an Asian Population.
Chang Fen XU ; Eugene S J TAN ; Liang FENG ; Rajalakshmi SANTHANAKRISHNAN ; Michelle M Y CHAN ; Shwe Zin NYUNT ; Tze Pin NG ; Lieng Hsi LING ; A Mark RICHARDS ; Carolyn S P LAM ; Toon Wei LIM
Annals of the Academy of Medicine, Singapore 2015;44(8):274-283
<p>INTRODUCTIONElectrocardiographic (ECG) criteria for left ventricular hypertrophy (LVH), such as the Cornell and Sokolow-Lyon voltage criteria were derived from Western populations. However, their utility and accuracy for diagnosing echocardiographic LVH in Asian populations is unclear. The objective of this study was to assess the accuracy of ECG criteria for LVH in Asians and to determine if alternative gender-specific ECG cut-offs may improve its diagnostic accuracy.p><p>MATERIALS AND METHODSECG and echocardiographic assessments were performed on 668 community-dwelling Asian adults (50.9% women; 57 ± 10 years) in Singapore. The accuracy of ECG voltage criteria was compared to echocardiographic LVH criteria based on the American Society of Echocardiography guidelines, and Asian ethnicity and gender-specific partition values.p><p>RESULTSEchocardiographic LVH was present in 93 (13.6%) adults. Cornell criteria had low sensitivity (5.5%) and high specificity (98.9%) for diagnosing LVH. Modified gender specific cut-offs (18 mm in women, 22 mm in men) improved sensitivity (8.8% to 17.5%, 0% to 14.7%, respectively) whilst preserving specificity (98.2% to 94.2%, 100% to 95.8%). Similarly, Sokolow-Lyon criteria had poor sensitivity (7.7%) and high specificity (96.1%) for diagnosing LVH. Lowering the cut-off value from 35 mm to 31 mm improved the sensitivity in women from 3.5% to 14% while preserving specificity at 94.2%. A cut-off of 36 mm was optimal in men (sensitivity of 14.7%, specificity of 95.5%).p><p>CONCLUSIONCurrent ECG criteria for LVH derived in Western cohorts have limited sensitivity in Asian populations. Our data suggests that ethnicity- and gender-specific ECG criteria may be needed.p>
Aged
;
Asian Continental Ancestry Group
;
statistics & numerical data
;
Dimensional Measurement Accuracy
;
Echocardiography
;
methods
;
Female
;
Humans
;
Hypertrophy, Left Ventricular
;
diagnosis
;
ethnology
;
Male
;
Middle Aged
;
Sensitivity and Specificity
;
Sex Factors
;
Singapore
;
epidemiology
9.Demographic profile and risk factors of patients with benign vocal fold lesions diagnosed through laryngeal videoendoscopy and stroboscopy.
Tracy Camille P CHAN ; Ma. Clarissa S FORTUNA ; Patrick S ENRIQUEZ
Philippine Journal of Otolaryngology Head and Neck Surgery 2017;32(1):27-29
<p style="text-align: justify;">OBJECTIVE: To determine the prevalence of benign vocal cord lesions among Filipino patients in a tertiary institution and identify the demographic characteristics and possible risk factors found among these patients.
METHODS:
Design: Retrospective Case Series
Setting: Private Tertiary Hospital
Participants: Records of 2,375 patients who underwent laryngeal video endoscopy and stroboscopy from 2012-2014 were reviewed.
RESULTS: There were 632 records of patients with benign vocal fold lesions, of which nodules were most common (211, 33.38%) followed by Reinke's edema (165, 26.10%), cysts (122, 19.30%) and polyps (74, 11.70%) with hoarseness as the most common symptom (542, 85.76%). More than half (336, 53.16%) were aged 21-40 years and almost two-thirds (469, 74.21%) were female. The most common associated factors were caffeine intake (445, 70.41%) and inadequate water intake (370, 58.54%), followed by alcohol (253, 40.03%). Smoking was only present in 146 (23.19%).
CONCLUSIONS: Baseline evidence on the prevalence of benign vocal fold lesions in this institution as well as baseline data on the common characteristics and associated factors seen in the sample population may assist us in current practices and guide future studies directed toward treatment and prevention.p>
Human
;
Male
;
Female
;
Stroboscopy
;
Vocal Cords
;
Hoarseness
;
Caffeine
;
Risk Factors
;
Smoking
;
Tertiary Care Centers
;
Laryngeal Edema
;
Polyps
;
Larynx
;
Cysts
;
Alcohols
;
Endoscopy
;
Edema
10.Improved median survival for glioblastoma multiforme following introduction of adjuvant temozolomide chemotherapy.
Michael F BACK ; Emily L L ANG ; Wai-Hoe NG ; Siew-Ju SEE ; C C Tchoyoson LIM ; S P CHAN ; Tseng-Tsai YEO
Annals of the Academy of Medicine, Singapore 2007;36(5):338-342
<p>INTRODUCTIONThe use of adjuvant temozolomide (TMZ) in patients managed with surgery and adjuvant radiation therapy (RT) for glioblastoma multiforme (GBM) has been demonstrated to improve median and 2-year survival in a recent large international multicentre study. To confirm this result in routine clinical practice, an audit of the management and outcome of patients with GBM at The Cancer Institute Radiation Oncology was performed.p><p>MATERIALS AND METHODSAll patients with GBM managed radically at The Cancer Institute Radiation Oncology from May 2002 to 2006 were entered into a prospective database. Patient, tumour and treatment factors were analysed for association with the outcome of median survival (MS). Survival was calculated using the Kaplan-Meier technique and correlation was assessed using Cox proportional hazards regression.p><p>RESULTSForty-one patients with GBM were managed with radical intent over the 4- year period. The median age was 54 years and 66% were Eastern Cooperative Oncology Group (ECOG) 0-1 performance status. Macroscopic, subtotal and biopsy alone procedures were performed in 61%, 29% and 10% of patients, respectively. The median time from surgery to RT was 26 days. Adjuvant TMZ was used in 44% of patients (n = 18). The MS of the total group was 13.6 months, with a 24% 2-year overall survival. The use of TMZ was associated with improved MS (19.6 versus 12.8 months; P = 0.035) and improved 2-year survival (43% versus 0%). A requirement of dexamethasone dose greater than 4 mg at the end of RT (P = 0.012) was associated with worse survival, but there was no association of MS with age, ECOG, tumour size or extent of surgery.p><p>CONCLUSIONThe median and 2-year survival outcomes are comparable to the results of the European Multicentre Study and justify the continued use of TMZ in routine clinical practice.p>
Antineoplastic Agents, Alkylating
;
administration & dosage
;
therapeutic use
;
Brain Neoplasms
;
drug therapy
;
radiotherapy
;
surgery
;
Chemotherapy, Adjuvant
;
Dacarbazine
;
administration & dosage
;
analogs & derivatives
;
therapeutic use
;
Female
;
Glioblastoma
;
drug therapy
;
radiotherapy
;
surgery
;
Humans
;
Male
;
Middle Aged
;
Prospective Studies
;
Singapore
;
Survival Analysis