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Biomedical subjects

A H Lam

Publications and source records attributed to A H Lam.

At least 19 recordsLinked to original sources
PubMed1997

Acinic cell carcinoma of the parotid in children.

The imaging findings of two children with acinic cell carcinoma of the parotid gland are presented. Ultrasonic features are emphasized. One of these children, a 6-year-old boy, suffers from the oculocerebrorenal syndrome of Lowe, a rare congenital, inherited condition manifested by defects of the nervous system (mental retardation, hypotonia), eyes (cataracts, glaucoma) and kidneys. To date, no known association exists between these two rare entities. The other child, a 10-year-old girl, was otherwise well. The ultrasound findings of both cases demonstrate features more classic for a benign intraparotid mass than for a potentially malignant lesion. The possibility of acinic cell carcinoma should be considered if a well-defined, relatively homogenously hypo-echoic intraparotid mass is encountered in a child, especially if cystic spaces are present.

Carcinoma, Acinar Cell↗
PubMed1996

Chest radiograph abnormalities in very low birthweight survivors of chronic neonatal lung disease.

OBJECTIVE: To determine whether the neonatal chest radiograph (CXR) at 28 days in very low birthweight (VLBW) infants who develop chronic neonatal lung disease (CNLD) predicts oxygen therapy duration or CXR abnormalities in early childhood. Also, to assess the inter-observer reliability of the radiologists scoring the CXR. METHODOLOGY: Clinically well survivors of CNLD (n = 46) had neonatal CXR scored (mean age 28.5 days) and compared with current CXR (mean age 40 months). The CXR were scored independently and 'blindly' by two paediatric radiologists using a standardized scoring system (range 0-10). RESULTS: There was no correlation between neonatal CXR scores and current CXR scores for either radiologist. There was no association between CXR severity scores and duration of oxygen therapy for either neonatal or current CXR. Radiologist A scored the current CXR significantly more abnormal than radiologist B [medians (range): 3 (1-6) vs 1 (0-5), P < 0.001] with reasonable correlation (r = 0.593, P < 0.005) but worse than chance agreement (kappa = -0.034). The median scores for the neonatal CXR were similar [1.5 (0-8) vs 2 (0-8), P = 0.789] and again there was good correlation (r = 0.760, P < 0.0005) although poor individual agreement (kappa = 0.243) between radiologists. CONCLUSIONS: Follow-up CXR abnormalities in VLBW infants with CNLD are usually minor and are not predictive of the duration of oxygen therapy that will be required nor of the CXR appearance in early childhood. Considerable inter-observer variation exists in the interpretation of the CXR in CNLD.

Bronchopulmonary Dysplasia↗
PubMed1995

Doppler imaging of superior sagittal sinus thrombosis.

Three cases of neonatal superior sagittal sinus thrombosis diagnosed by Doppler imaging and confirmed with either computed tomography, magnetic resonance imaging, or digital subtraction angiography are described. One infant died and the others had uneventful recovery. Young infants with superior sagittal sinus thrombosis rarely are seen for diagnostic imaging; the nonspecificity of the clinical presentation of this disorder and the difficulties with its investigation owing to the invasiveness of the radiologic procedures lead to its underdiagnosis. Magnetic resonance imaging is a sensitive, noninvasive diagnostic modality, but it is not always available and practical for the very sick infants in the critical care unit. In the cases described here, Doppler imaging proved to be diagnostic and useful in the management of superior sagittal sinus thrombosis and should be used in the initial assessment of the condition, as it is the most convenient and least traumatic diagnostic modality.

Angiography, Digital Subtraction↗
PubMed1994

Sonographic findings in bladder haematoma.

The medical imaging and clinical histories of three cases of haematoma of the urinary bladder in paediatrics were reviewed retrospectively. The sonographic findings are unique and diagnostic. Three distinctive sonographic features were observed. The haematomas were large, occupying most of the bladder lumen. They showed an echogenic thick, smooth rim and, in two cases, a laminated appearance with concentric layers of alternating hyperechogenicity and hypo-echogenicity.

Child↗
PubMed1993

Hereditary tyrosinaemia (HT) type 1A.

Two infants, aged 5 and 6 months, with the chronic form of HT Type 1 A were studied with sonography and CT. The imaging findings mirrored the pathological process. The sonographic findings included marked hepatomegaly, the parenchyma being of increased echogenicity due to fibrosis and fatty infiltration, and containing multiple hypoechoic regenerating nodules of varying sizes. There was marked nephromegaly, with uniform thickening of the renal cortices. Apart from the density measurement of the hepatic nodules and the perfusion status of the liver and kidney, no additional information was added by CT imaging. The diagnosis of HT Type 1 A should be excluded in an infant presented with the described typical sonographic features.

Amino Acid Metabolism, Inborn Errors↗
PubMed1992

Value of sonography including color Doppler in the diagnosis and management of long standing intussusception.

15 cases of intussusception with presenting symptoms of more than 24 h duration were studied by sonography and Doppler. The aim of the study was to determine the validity of the sonographic criteria of peritonitis and bowel ischaemia in order to reduce the risk of colonic perforation and to increase confidence in achieving a successful hydrostatic reduction. The results were reviewed retrospectively and cases divided into 2 groups. Cases in group 1 were reducible by barium enema while those in group 2 required surgical intervention. Sonographic features of peritonitis were absent in all cases of group 1 and 3 cases of group 2. These 3 cases were reduced manually at surgery while the other 5 cases in group 2 with positive features of peritonitis required bowel resection. Blood flow was documented by colour flow Doppler in all cases except the 3 cases with gangrenous bowel in group 2. When sonographic features of peritonitis and loss of blood flow to the intussusception are present in late intussusception, surgical intervention is required. On the other hand, enema reduction should be pursued when such features are absent.

Child, Preschool↗
PubMed1992

Symptomatic third ventricular choroid plexus cysts.

We describe the imaging findings in 3 children with choroid plexus cysts (CPC) at the foramen of Monro. All CPC measured less than 2 cm and produced symptoms of raised intracranial pressure when located at the foramen of Monro where there was obstruction to the cerebrospinal fluid (CSF) flow. Among the imaging studies done on our patients, CPC were depicted best by cranial sonography and CT-ventriculography and missed by standard CT and MRI. Misdiagnosis can lead to inappropriate shunting with adverse effects. Two of our patients had relief of symptoms after resection of the cyst. One patient with inoperable cardiac defects died and had no surgery performed. Serial CT and sonographic studies in this patient showed progression in the size of the cyst and ventriculomegaly. Cranial sonography and CT-ventriculography are the modalities of choice in evaluating ventriculomegaly when the diagnosis of occult obstructive CPC is entertained in children. Cranial sonography is indicated in infants with an open fontanelle and CT-ventriculography is reserved for older children with hydrocephalus which is not responding to shunting.

Brain Diseases↗
PubMed1991

Ultrasound evaluation of subdural haematoma.

14 patients with subdural haematoma (SDH) diagnosed by ultrasonography (US) and confirmed by computerized tomography (CT) were reviewed. We describe the morphology of SDH on US and discuss the ultrasound findings which may suggest outcome. SDH appeared as a crescentic mass overlying the cerebral hemisphere and producing medial displacement of the Sylvian fissure, midline shift, ventricular compression, sutural diastasis, changes in the sulcal pattern and echogenicity of the ipsilateral side of the brain. Hydrocephalus was the most common complication. It was the presence of cerebral complications and not the midline shift or ventricular compression which correlated with poor outcome.

Child↗
PubMed1991

Ultrasound of intussusception with lead points.

Ultrasonography of 4 cases of intussusception in children with proven lead points were reviewed retrospectively. The lead points were due to lymphosarcoma, inverted Meckel's diverticulum, jejunal polyps and an inverted appendiceal stump. The lead points form a complex mass in the centre of the intussusception in both transverse and longitudinal sections, distinct from primary intussusception. The presence of such ultrasonographic findings are suggestive of secondary intussusception with a lead point and surgical reduction rather than hydrostatic reduction should be considered.

Child↗
PubMed1990

Imaging of ureteral duplication with a non-functioning component.

31 patients of ureteral duplication were selected when one moiety of the duplex system was poorly visualised with either IVU or DTPA studies. Both ultrasound and IVU were performed in all cases. DTPA scans were performed in 17 cases and MCUs in 26 cases. The cases were divided into 2 groups. Group 1 (28 patients), with hydronephrosis and hydroureter, was further subdivided into 1 A (18 patients) where the ureter terminated in an ureterocoele and 1 B (10 patients) where the ureter was ectopic. Group 2 (3 patients) were cases where the non-functioning moiety was hypoplastic or dysplastic and was drained by a small or normal size ureter. The diagnostic value of IVU, Ultrasound, DTPA scan and MCU was reviewed in each group.

Child, Preschool↗
PubMed1989

Imaging paediatric endocrine disorders.

Disorders of growth and development, including delayed and precocious puberty may be idiopathic, constitutional or due to a disorder of one of several endocrine systems including the hypothalamic-pituitary system, the adrenal and the thyroid. Sonography is of great importance in the classification of precocious puberty in children. Skeletal maturation assessment is useful to evaluate the severity of the growth disorder and to monitor subsequent therapy. Magnetic resonance imaging and computed tomography are essential in the study of the pituitary and central nervous system. MRI has special advantages in the imaging of the hypothalamic-pituitary region. The thyroid gland and its function are still best imaged with radionuclide scintigraphy. Sonography can play a complementary though less important role. Hypoparathyroidism, pseudohypoparathyroidism and pseudopseudohypoparathyroidism although rare are more common in children than primary hyperparathyroidism. Valuable clues as to the presence of these conditions can be gained by examination of the plain radiographs. Confirmation of their diagnosis still rests with the biochemical and endocrine profile.

Diagnostic Imaging↗
PubMed1987

Adrenocortical neoplasm in children. Ultrasound appearance.

The ultrasound appearances of three children presenting with virilization are described. All cases were also examined by computed tomography. The value of ultrasound in the initial detection of virilizing neoplasm and in follow-up studies for localization of tumor recurrence following initial surgery are outlined. The advantages of ultrasound include confirmation of extrarenal and extrahepatic location in longitudinal sections, and clear demonstration of invasion of hepatic veins, the inferior vena cava (IVC), and the right atrium on real-time scanning. Computed tomography is also useful, particularly in the localization of small lesions and the detection of pulmonary metastases.

Adenoma↗