Evaluation of a new predictive equation for automated calculation of size-specific dose estimate (SSDE) in CT imaging.

INTRODUCTION: The adoption of size-specific dose estimate (SSDE) in clinical practice is still limited owing to the tedious and complex manual measurement of individual patient size for the clinical calculation of SSDE. Thus, the automation of SSDE is imperative. This study aims to evaluate a predictive equation for the automated calculation of SSDE. METHODS: A user-friendly software was developed to accurately predict the individual size-specific dose estimation of paediatric patients undergoing computed tomography (CT) scans of the head, thorax, and abdomen. The software includes a calculation equation developed based on a novel SSDE prediction equation that used a population's pre-determined percentage difference between volume-weighted computed tomography dose index (CTDIvol) and SSDE with age. American Association of Physicists in Medicine (AAPM RPT 204) method (manual) and segmentation-based SSDE calculators (indoseCT and XXautocalc) were used to assess the proposed software predictions comparatively. RESULTS: The results of this study show that the automated equation-based calculation of SSDE and the manual and segmentation-based calculation of SSDE are in good agreement for patients. The differences between the automated equation-based calculation of SSDE and the manual and segmentation-based calculation are less than 3%. CONCLUSION: This study validated an accurate SSDE calculator that allows users to enter key input values and calculate SSDE. IMPLICATION FOR PRACTICE: The automated equation-based SSDE software (PESSD) seems a promising tool for estimating individualised CT doses during CT scans.

A study of the factors related to intima-media thickness of the common carotid artery amongst rural middle age individuals in Hospital Universiti Sains Malaysia.

There is very little data regarding the factors related to intima-media thickness (IMT) of the common carotid artery in normal individuals in those with non-insulin diabetes mellitus and perimenopausal women in Southeast Asian countries. Ultrasound imaging evaluating the carotid artery IMT in those with diabetes and those on hormone replacement therapy (HRT) was performed beginning in August 2000 for a period of nearly two years at the Department of Radiology, Hospital Universiti Sains Malaysia, Kubang Kerian, Kelantan, Malaysia. A total of 153 participants were included. Significant differences between the women on HRT and not on HRT were IMT and systolic blood pressure. When comparing those with non-insulin dependent diabetes mellitus (NIDDM) and normal individuals, the significant differences were IMT, total cholesterol level, systolic blood pressure and diastolic blood pressure. IMT was high in those with NIDDM but not in those on HRT. Both those with NIDDM and those on HRT had associated dyslipidemia and systolic hypertension.

Computed tomography perfusion of ischaemic stroke patients in a rural Malaysian tertiary referral centre.

INTRODUCTION: Computed tomography (CT) perfusion is a new method to diagnose ischaemic stroke especially in developing countries. It identifies the area and is useful to predict the size of final infarction. The aim of this study was to assess cerebral ischaemia with CT perfusion (CTP) among patients with acute ischaemic stroke in Hospital Universiti Sains Malaysia, a tertiary referral centre in a rural setting. METHODS: 42 consecutive unenhanced CT and CTP examinations of the brain in adult patients were evaluated prospectively. Unenhanced CT images were divided into normal, suspicious or frank infarction. CTP images was classified as normal or ischaemic. Subgroup analysis was carried out with a limit of six hours from time of ictus. RESULTS: Out of 42 patients, 20 had frank infarction on unenhanced CT, 15 had suspicious CT studies, while seven were normal. There was no significant association of demographical, clinical and radiological parameters to CTP in the whole group among acute stroke patients without frank infarction. Among the subgroup of patients without frank infarction, there was no significant association between unenhanced CT and CTP in patients who were studied less than six hours after stroke (p-value is 0.063) as well as those after six hours (p-value is 0.317). The prevalence of a normal unenhanced CT and positive CTP for ischaemia was 22.7 percent (95 percent confidence interval 7.8, 45.4). CONCLUSION: CTP may be a useful imaging tool for determining cerebral infarction in a rural-based community population, especially in cases where the unenhanced CT is normal. Thrombolysis is a therapeutic option, even when the history of onset of stroke is unclear.

Referral of epileptic patients in North East Coast of West Malaysia an area with poor MRI coverage: an analysis.

Advances in neuroimaging techniques, particularly Magnetic Resonance Imaging (MRI), have proved invaluable in detecting structural brain lesions in patients with epilepsy in developed countries. In Malaysia, a few electroencephalography facilities available in rural district hospitals run by trained physician assistants have Internet connections to a government neurological center in Kuala Lumpur. These facilities are more commonly available than MRI machines, which require radiological expertise and helium replacement, which may problematic in Southeast Asian countries where radiologists are found in mainly big cities or towns. We conducted a cross-sectional study over a two year period begining January 2001 on rural patients, correlating EEG reports and MRI images with a clinical diagnosis of epilepsy to set guidelines for which rural patients need to be referred to a hospital with MRI facilities. The patients referred by different hospitals without neurological services were classified as having generalized, partial or unclassified seizures based on the International Classification of Epileptic Seizures proposed by the International League Against Epilepsy (ILAE). The clinical parameters studied were seizure type, seizure frequency, status epilepticus and duration of seizure. EEG reports were reviewed for localized and generalized abnormalities and epileptiform changes. Statistical analysis was performed using logistic regression and area under the curve. The association between clinical and radiological abnormalities was evaluated for sensitivity and specificity. Twenty-six males and 18 females were evaluated. The mean age was 20.7 +/- 13.3 years. Nineteen (43.2%) had generalized seizures, 22 (50.0%) had partial seizures and 3 (6.8%) presented with unclassified seizures. The EEG was abnormal in 30 patients (20 with generalized abnormalities and 10 localized abnormalities). The MRI was abnormal in 17 patients (38.6%); the abnormalities observed were cerebral atrophy (5), hippocampal sclerosis (4), infarct/gliosis (3), cortical dysgenesis (2) and tumors (2). One patient had an arachnoid cyst in the right occipital region. Of the 17 patients with an abnormal MRI, 14 had an abnormal EEG, this difference was not statistically significant. There was no significant associaton between epileptographic changes and MRI findings (p = 0.078). EEG findings were associated with MRI findings (p = 0.004). The association between an abnormal EEG and an abnormal MRI had a specificity of 82.4%, while epileptogenic changes had a specificity of 64.7% in relation to abnormal MRI findings. This meants that those patients in rural hospitals with abnormal EEGs should be referred to a neurology center for further workup and an MRI to detect causes with an epileptic focus.

CT scan in minor head injury: a guide for rural doctors.

Minor head injury in a developing country like Malaysia is managed by primary care physicians and/or medical assistants in district hospitals. These patients are seen initially in their local hospitals, which have at least an X-ray machine for the purpose of screening. This study aimed to guide these physicians to manage these patients at a primary care level. A cross-sectional study was conducted and the study revealed significant predictors of significant computed tomographic (CT) findings. The presence of a Glasgow coma scale (GCS) score of 14 or 13 was associated with the risk of developing significant CT findings compared to patients with a GCS of 15 (p<0.001). Thirty-seven out of 50 patients with GCS of 14 or 13 developed clinically significant brain injury on CT scan. Similarly, the presence of skull fracture was associated with the risk of developing CT abnormalities (p<0.001). Forty-two out of 51 patients with skull fracture developed clinically significant CT findings. Vomiting was associated with developing CT abnormalities (p=0.017). Twenty-seven out of 40 patients with vomiting showed significant CT findings. Soft tissue injury was also found to be associated with developing CT abnormalities (p=0.007). Therefore, we propose reclassifying minor head injury based on the GCS score. Patients with a GCS score of 15 were classified as having mild head injury, while patients with a GCS score of 13 or 14 were at higher risk of developing brain injury and therefore categorized as high risk mild head injury. This group requires emergency CT scan examination, especially when associated with non-motor vehicle accidents, abnormal central nervous system (CNS) examination, craniofacial injuries or skull fractures. They should be referred to a general surgical unit which can treat head injuries or a neurosurgical tertiary centre.

Natural history of giant cell tumour of the bone.

The clinical presentation and behaviour of giant cell tumours of bone vary. The progression of the disease and metastases are unpredictable, but the overall prognosis is good. We describe the natural history and different clinical presentations of two cases of giant cell tumour of bone where the patients had refused the initial treatment and presented several years later with the disease.

The effect of propranolol in malay patients with liver cirrhosis - a pharmacodynamic evaluation.

The pharmacodynamics of propranolol were studied in 12 cirrhotic Malay patients. Fifteen healthy Malay volunteers were selected and several clinical parameters were obtained. The effects of three doses of propranolol in reducing the heart rate (HR) of these patients were observed to be significantly different. These differences were seen at dosing of 10 mg vs 20 mg and 10 mg vs 30 mg (P<0.001 and P<0.01, respectively). However, no significant difference was seen for doses between 20 mg vs 30 mg. At 20 mg the reduction in HR is more pronounced than the effect seen with the other two doses. The effects of propranolol in reducing V(max) and V(mean) of portal vein blood flow were found to be not significant at doses of 10 mg vs 30 mg, but between 10 mg vs 20 mg and 20 mg vs 30 mg there was significant difference (P<0.05 and P<0.01, respectively). Reduction of V(max) of more than 10% of baseline was achieved at doses of 10 mg and 20 mg. However, at a dose of 20 mg a more significant reduction was observed than at a dose of 10 mg. Dose-concentration-effect relationship was seen to be significantly different between HR reduction and propranolol concentration of the three steady-state levels (P<0.001). Similar results were obtained with V(max) and V(mean). The V(max) was found to be a reliable parameter for the assessment of therapeutic effect of the drugs in conferring changes in portal haemodynamics of liver cirrhotic patients. Further, Child-Pugh score is thought to be an important supporting factor in evaluating prognosis. The results of this pharmacodynamics studies suggest that the optimal dose of propranolol may be 20 mg propranolol thrice daily for cirrhotic Malay patients.

The Pharmacokinetics of Single Dose vs Steady-State Doses of Propranolol in Cirrhotic Malay Patients.

Pharmacokinetics of propranolol (PRN) given orally were studied in twelve cirrhotic Malay patients [10 males, 2 females], aged 33-62 years [49.83±9.17], body weight 39-72 kg [58.0±8.46] and height 142-168 cm [158.8±7.89] following single 20 mg and steady-state 20 mg tds for 7 days dosing of PRN. Blood samples were withdrawn hourly up to 48 hours. PRN concentrations in the plasma were assayed by HPLC with oxprenolol as the internal standard. Pharmacokinetic parameters were analysed using a non-linear regression program MultiForte. Area under the curve (AUC) as performed using the linear trapezoidal rule. Student's t-test was used to test for statistical significance and AUC in Malay cirrhotic patients was found to be much bigger than that observed in Caucasians. Steady-state AUC was significantly increased following multiple dosing (961.31±7.47 vs 2954.19±1153.34 ng.hr/ml), however, the volume of distribution (V(d)) declined (543.89±292.91 vs 224.14±1003.12 L) significantly compared to that of a single dose. The apparent systemic clearance (CL) was significantly reduced at steady-state (436.04±209.4 vs 129.51±48.42 ml/min) in comparison to single dose therapy. The peak plasma concentration (Cp(max)) was greatly increased at steady-state (54.32±22.37 vs 136.10±38.63 ng/ml). Based on the AUC, PRN bioavailability was greater in cirrhotic Malay patients compared to Caucasians who took only 20 mg instead of 80 mg doses. The decline in drug clearance following steady-state was due to saturation of the metabolizing capacity of hepatic enzymes and a decreased portal blood flow. Reduced V(d) was believed to be caused by increased drug-receptor interactions and decreased tissue/protein binding of PRN in these patients.

Arteriovenous malformation or contusion : a diagnostic dilemma.

A young man was involved in a motor vehicle accident and sustained cerebral contusion in the right frontal and occipital lobes. Computed tomography (CT) scan done 2 weeks after the injury revealed multiple serpenginous structures which enhanced following intravenous contrast media administration. The possibility of arteriovenous malformation (AVM) was raised and angiography was suggested. However, he was managed conservatively and a repeat CT scan 4 months post trauma revealed encephalomalacia in the right frontal and occipital lobes with no more surrounding enhancement. The cause for the multiple serpenginous enhancement demonstrated previously confirmed those are areas of hyperperfusion in healing surface brain contusion. The aim of this case report is to discuss on the possible causes of focal enhancement following head injury versus the features of AVM on plain and post contrast CT scan with the effort to clear the doubt and to avoid future confusion.

Internal jugular phlebectasia--an unusual cause of neck swelling.

We describe a 7-year-old child who presented with a soft fluctuant swelling on the neck which became more prominent during the Valsalva manoeuvre. He underwent adeno-tonsillectomy based on a mistaken diagnosis of ballooning of the pharynx secondary to enlarged adenoids and tonsils obstructing the nasopharyngeal and oropharyngeal airways. Investigations revealed the swelling to be a markedly dilated internal jugular vein. We discuss the diagnostic features and mode of treatment of this condition so as to avoid unnecessary and dangerous surgical intervention.

Idiopathic CD4+ T-lymphocytopenia in a child with disseminated cryptococcosis.

We describe a Malay girl with disseminated cryptococcosis affecting the lungs, liver, lymph nodes and bones. The diagnosis was made by culture of the bone marrow. Tests of immune function showed that she was HIV-negative but the CD4 percentage was persistently low. Idiopathic CD4+ T-lymphocytopenia was diagnosed. The child died despite two courses of anti-fungal therapy.

Dense artery sign of the middle cerebral artery: traumatic cause.

Dense artery sign of the middle cerebral artery on non-enhanced computed tomography is recognized as an early sign of ensuing major cerebral infarction and is usually a consequence of thrombosis or embolism of an ischaemic stroke. A case is described resulting from trauma that correlated with angiographic and Doppler ultrasound findings and the significance of this sign in this case is discussed.