Biomedical subjects
Publications and source records attributed to F L Chan.
Invasive cystic thymoma is reported in two siblings (an 11-year-old girl and a 9-year-old boy) and the radiographic, CT and ultrasonographic features are described. The tumours were removed by thoracotomy. Familial thymic masses are reviewed, and the imaging differential diagnosis of cystic anterior mediastinal mass in a child is discussed.
Development of typical pseudoarthrosis from an acute fracture in the spine of a patient with ankylosing spondylitis is documented by serial radiographs. The magnetic resonance imaging appearances of pseudoarthrosis are correlated with histological findings of the surgical specimen.
The purpose of this study was to search for constant and reliable reference points on the computed tomographic scans of scoliotic spines to measure vertebral rotation. Several methods using different sets of reference points on computed tomographic scans were tested for reliability. Two methods that gave minimum variation between the readings are presented here with interobserver and intraobserver reliability on 17 girls with adolescent idiopathic scoliosis. The selection of reference points for the two methods were as follows: In method 1, the vertebral rotation was an angle formed by two lines; one, a line joining the junction of the inner surfaces of two laminae and the midpoint of the posterior surface of the vertebral body and second, the vertical plane of the computed tomographic machine. In method 2, three datum points were marked; one at the junction of the inner surfaces of the laminae, and the other, one each at the junction of the inner surfaces of the lamina and the pedicle. A line bisecting this angle is drawn by the computer and the vertebral rotation was an angle between this line and the vertical plane. The 95% confidence intervals of these two methods for intraobserver variation were between 1.2 to 4.4 degrees. There was no significant difference between the readings obtained by each observer except on three occasions for observer 1. When these methods were tested for interobserver reliability, method 1 showed significant statistical differences between the readings obtained by the two observers. However, the readings obtained using method 2 were not significantly different between the two observers (95% confidence intervals = 3.2 to 5.8 degrees).(ABSTRACT TRUNCATED AT 250 WORDS)
BACKGROUND AND PURPOSE: This clinical trial investigates the effectiveness of intravenous glycerol therapy in patients with acute cortical infarction in whom intracerebral hemorrhage was rigorously excluded. METHODS: Within 48 hours of symptoms from their first ischemic stroke, 113 hospital inpatients were randomized into the trial, provided that hemorrhage was excluded by computed tomography and informed consent was obtained. Patients were stratified into alert, semicoma, and coma groups using the Glasgow Coma Scale. Treatment was allocated according to a double-blind, randomized protocol; 56 patients received 500 mL of 10% glycerol in saline over 4 hours on 6 consecutive days, and 57 patients received corresponding placebo treatment with saline. Using a variety of objective scoring systems, patient follow-up was up to 6 months. RESULTS: Corresponding measures of outcome in the glycerol and placebo groups were similar. At 6 months, respective mortality rates were 17 of 56 and 16 of 57, and mean +/- SD improvements in scores were 9.98 +/- 14.40 vs 10.51 +/- 12.68 (long-term), 1.12 +/- 7.20 vs 1.57 +/- 6.30 (prognostic), -1.94 +/- 5.53 vs -2.06 +/- 5.34 (Glasgow Coma Scale), and 21.72 +/- 23.40 vs 11.94 +/- 18.10 (Barthel Index rating in survivors). Hemolysis (generally subclinical) was the only adverse effect. CONCLUSIONS: There was no clinically or statistically significant difference in outcome between the groups; a trend toward greater functional recovery among survivors was evident after treatment with glycerol.
Stridor implies partial airway obstruction, resulting from intrinsic or extrinsic abnormalities of the upper respiratory tract. In a neonate whose airway is small, soft and easily occluded this may be potentially life threatening. Its immediate diagnosis with prompt therapy is a rewarding challenge. When stridor occurs in a neonate with congenital hypothyroidism, surgically amenable cause of obstruction due to an ectopic thyroid or thyroglossal cyst has to be seriously considered. We report a case of neonatal stridor caused by a lingual thyroid, and discuss the imaging approach.
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Despite recent instrumentation advancement in morphologic imaging, venous sampling remains a sensitive physiological investigation for functional localization of hormonal hypersecretion. The test requires technical expertise and reliable laboratory support, and should be selectively applied to address individual clinical problems in coordination with other imaging modalities. Depending on the venous anatomy, sampling may achieve regional localization or lateralization of the endocrine tumour. Adrenal venous sampling serves to lateralize functioning tumour, and to differentiate it from hyperplasia. Inferior petrosal sinus sampling confirms pituitary Cushing's disease and lateralizes the adenoma. Systemic venous sampling identifies the site of ectopic hormonal secretion. In the localization of pancreatic islet cell tumours, the test is further enhanced by sampling after intraarterial injection of hormonal secretagogue. The experience of venous sampling in a regional referral hospital is discussed, including the patient selection, its technical details, pitfalls and effectiveness in achieving tumour localization for patient management.
The very rare complication of rectal perforation during the barium enema of an immunocompetent Chinese man with cytomegalovirus (CMV) colitis is described. Rectal biopsy performed over three weeks earlier was unlikely to have been related to the perforation. Histopathological examination of the colonic mucosa showed features of active chronic colitis and CMV infection. After treatment with Ganciclovir, there was cessation of symptoms with eradication of the virus on repeat biopsy samples. It is suggested that presence of CMV colitis predisposed to rectal perforation. The clinical presentation, course of disease and response to treatment supported the concept of CMV as a primary aetiological agent. This complication should be borne in mind when performing barium enemas in patients with clinical features of colitis, especially if they are immunocompromised.
A case of secondary hypertension due to an aldosteronoma coexisting with renal artery stenosis is reported. Tumor resection resulted in an immediate but short-lived clinical relief. Follow-up aortography revealed progressive arterial stenosis and infrarenal aortic occlusion. Differential renal venous renin and renal scintigraphy suggested renovascular hypertension. It is necessary to search for a second curable lesion if hypertension remains uncontrollable after surgical correction of an apparent cause.
Hypoglycaemia as a result of insulin secreting tumours can be treated effectively by surgery. However pre-operative localization is desirable as the majority of these tumours are small and in 20% of the cases may be multiple. We describe a 1 cm insulinoma being localized pre-operatively by selective arterial stimulation with calcium and venous sampling for insulin. This technique is sensitive and relatively non-invasive. We believe that it is potentially very valuable in pre-operative localization of occult insulinomas.
In 137 normal CT scans of the nasopharynx, the parapharyngeal spaces at the nasopharynx level were asymmetrical in 30%. Their difference in width and distance from the midline was greater than 1 mm in 51% and 44% respectively. Fat was absent in the interpterygoid fascia in 20%, in the alar fascia in 28%, in the prevertebral space in 35%, and in the retropharyngeal space in 99% of patients. Assessment of tumour extension to the paranasopharyngeal space usually relies on symmetry and fascial fat planes. As either feature may not be present in the normal person, the relation of the tumour to two lines representing two fascial planes is proposed as a complementary method for the evaluation of tumour extension.
Pneumatocele of the infratemporal fossa caused by herniation of air through a break in the wall of the aerated maxillary sinus is rare. Two cases are reported: one arising from a maxillary pneumocele with a defect in the wall of the zygomatic recess and one associated with maxillary radionecrosis with pathological fracture complicated by infection. Computed tomography can clearly demonstrate the extent of the pneumatocele, and can show the maxillary pathology and the causative bony defect in the sinus. Treatment depends on the clinical conditions of the patient, the pathology and the size of the bony defect.
Seventeen patients with post-renal transplant erythrocytosis and 17 non-erythrocytotic controls, matched in age, sex, serum creatinine and source of donor kidney, were studied to determine the role of erythropoietin, male sex hormones (testosterone, FSH, LH), and various patient risk factors in post-transplant erythrocytosis. Serum erythropoietin was significantly greater in erythrocytotic patients (35.6 +/- 5.7 mU/ml) than non-erythrocytotic patients (18.8 +/- 2.6 mU/ml) (P less than 0.05) and normal subjects (22.5 +/- 0.95 mU/ml) P less than 0.05). Serum testosterone was similar between the male study (13.2 +/- 6.2 nmol/l) and control (13.1 +/- 6.0 nmol/l) patients. This might be due to the greater basal LH in the male control subjects (13.9 +/- 11.7 IU/l versus 8.0 +/- 3.3 IU/l in erythrocytotic males, P = 0.084). Basal FSH in the male controls was greater than that in the study group (13.7 +/- 14 IU/l versus 6.8 +/- 2.9 IU/l, P = 0.067). Among the demographic risk factors, only the smoking history was important. There were more smokers among the erythrocytotic patients than controls (P = 0.051).
A comparative analysis of two methods of measuring vertebral rotation in adolescent idiopathic scoliosis is reported in this article. Nash and Moe's pedicle shift method (using plain anteroposterior radiographs) is compared with a new method using computed tomographic scans. The computed tomographic scans of the whole length of the major curve and the scout films obtained from seventeen girls aged 12.5-14 years were measured for rotation of each vertebra of the curve (total number of vertebrae measured by two methods = 173). This study has three interesting new findings: 1) Those vertebrae with Nash & Moe grade 0 had up to 11 degrees of vertebral rotation when measured using the computed tomographic method. Therefore, Nash & Moe's grade '0' is not a neutrally rotated vertebra; 2) For Nash & Moe grade 1 and 2, the computed tomographic method revealed statistically significantly greater rotation for lumbar vertebrae than thoracic vertebrae. There was a similar pattern for Nash & Moe grade 0 but these differences were not statistically significant; and 3) Simple formulae are reported to convert Nash & Moe's grades into angle of vertebral rotation as obtained by CT method separately for thoracic and lumbar vertebrae.
BACKGROUND AND PURPOSE: Hitherto, treatment of acute cerebral hemorrhage with intravenous glycerol has not been evaluated in rigorous clinical studies with sufficient patient numbers. METHODS: We undertook a double-blind, stratified and randomized, placebo-controlled clinical trial. Only patients with a first stroke admitted to the hospital within 24 hours after onset of symptoms were recruited, provided computed tomography confirmed hemorrhage and informed consent was obtained. After stratification into alert, semicoma, and coma subgroups using the Glasgow Coma Scale, 107 patients received active treatment (500 ml of 10% glycerol in saline by intravenous infusion over 4 hours on 6 consecutive days) and 109 were given corresponding saline treatment. Using a variety of objective scoring systems, patients were followed up for up to 6 months. RESULTS: At follow-up, all measures of outcome in the treated and control groups were very similar. At 6 months, respective mortality rates were 37 of 107 and 33 of 109. Corresponding mean +/- SD improvements in Scandinavian Stroke Study Group scores were 8.35 +/- 16.9 versus 11.55 +/- 15.6 (long-term) and 0.64 +/- 7.3 versus 2.40 +/- 6.9 (prognostic), and improvements in the Barthel Index ratings were 10.72 +/- 24.7 versus 13.95 +/- 23.3, respectively. Glasgow Coma Scale score improvements in the survivors were 0.81 +/- 1.5 and 1.16 +/- 1.7 in the treated and control groups, respectively. Hemolysis (generally subclinical) was the only adverse effect of glycerol noted. CONCLUSIONS: In the absence of any clinically or statistically significant difference in outcome between the treated and control groups, this trial provides no justification for glycerol therapy following acute cerebral hemorrhage.
We localized heparan sulfate proteoglycan (HSPG) in the basement membranes of ciliary epithelium and plantar epidermis, using Cuprolinic blue to stain its side chains and an immunogold procedure to detect its core protein. In accord with most of the literature, staining with Cuprolinic blue in glutaraldehyde fixative yielded three to five times as many reaction products along the two surfaces than along the center of the lamina densa, whereas immunogold labeling for the core protein after formaldehyde fixation yielded about twice as many gold particles over the center than along the surfaces of the lamina densa. It therefore appeared that HSPG side chains predominated outside, and the core protein within, the lamina densa. To find out whether the discrepancy was true or was an artifact caused by differences in processing, we attempted to combine the two approaches on the same material. This was found possible when Cuprolinic blue was used in formaldehyde fixative, embedding was in LR White, and immunogold labeling was performed on thin sections as usual. Under these conditions, both Cuprolinic blue reaction products and immunogold particles predominated over the lamina densa in the two basement membranes under study. Moreover, evidence was present that reaction products and immunogold particles either overlapped each other or were closely associated. The lens capsule (a thick basement membrane) also showed their co-localization. The discrepancy initially observed between side chains and core protein location was attributed to differences in processing, since Cuprolinic blue staining had been carried out in the course of glutaraldehyde fixation whereas immunogold labeling was done after formaldehyde fixation. The results lead to two conclusions. First, processing differences may alter the localization of HSPG and possibly other proteoglycans. Second, both HSPG side chains and core protein are localized in the same sites within basement membrane.
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