Biomedical subjects
Publications and source records attributed to F L Chan.
A woman survived venous intravasation of barium complicating an abdominal barium study. Barium deposition in the reticuloendothelial system was evident by an increase in density in the liver, spleen, and bones on plain radiographs and marked elevation of attenuation values of these organs on computed tomographic scans. The literature on barium intravasation is reviewed.
Two patients with toxaemia of pregnancy presented with cortical blindness. Immediate cranial computed tomography (CT) demonstrated bilateral hypodense areas in the occipital lobes. Both patients underwent Caesarean section for delivery. There was gradual and complete recovery of vision, together with CT documentation of resolution of the cerebral changes, indicative of the reversible nature of the ischaemic lesion.
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Retroaortic left renal vein is an uncommon variant in the renal venous system. Recently a patient with such anomaly presented to us with hematuria.
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Prominent periportal echogenicity was detected during sonographic examination of patients suffering from recurrent pyogenic cholangitis, hepatocellular carcinoma and acute cholecystitis. To document the finding, 140 normal individuals were studied to establish a norm for the evaluation of the periportal echogenicity. The significance of this sonographic finding and its possible aetiology are discussed.
A case of mucocele of the posterior ethmoid sinus presenting as unilateral blindness without pain, proptosis, or diplopia is reported. Computerized tomography (CT) demonstrated the precise anatomical relationship of the mucocele to the optic nerve inside the optic canal. It is proposed to use the term "optic canal syndrome" for patients with such clinical and CT presentation. Combined transcranial excision and transnasal drainage resulted in dramatic recovery of vision.
Fifty consecutive Chinese patients with primary hyperaldosteronism were studied. All were considered to have an adrenal cortical adenoma, this being proven by surgery in 46 cases. In contrast to other reports, periodic paralysis was a presenting feature in 42 per cent of patients. Other notable symptoms were palpitations (30 per cent) and syncope (12 per cent). Vascular complications were present in 20 per cent of cases. Mean serum potassium level at presentation was 2.1 +/- 0.1 (mean +/- SEM) and sodium 145.0 +/- 0.1 mmol/l. Serum potassium was significantly lower and plasma aldosterone higher in patients with periodic paralysis. Adrenal venography in order to localise the tumour was unreliable and was misleading in two cases. Adrenal venous sampling for steroid analysis was much more helpful, despite the difficulty of obtaining right adrenal venous blood. The side of the adenoma could be predicted in 97 per cent of cases from measurements of left adrenal venous and vena caval aldosterone levels. The use of high resolution CT gave 100 per cent accuracy in all 18 patients who underwent surgery, the smallest detected tumour being 0.8 cm in diameter. Surgery corrected hypokalaemia in all cases, and 37 of the 46 patients required no further antihypertensive treatment.
Traumatic acute arterial subdural hematomas are rare and are associated with a high mortality rate. The authors report a case in which the initial computed tomographic (CT) scan examination failed to reveal a hematoma. Within the subsequent 4 hours, while recovering from anesthesia given so that hemostasis of bleeding soft tissue injuries could be obtained, the patient suddenly developed bilaterally dilated pupils, both nonreactive to light. A repeat CT scan then revealed large subdural and intracerebral hematomas. The case is discussed and the pertinent literature is reviewed.
The clinical, radiological and pathological findings are presented of a Chinese girl with sclerosing osteosarcomatosis. The findings strongly support multicentricity in a subclass of multiple osteosarcoma in the young. The unusual features in clinical presentation are emphasized.
One hundred and fifteen Chinese patients with mitral-valve prolapse were evaluated for skeletal abnormalities, to determine their prevalence and interrelation. Measurements of thoracic dimensions from radiographs differed significantly from the normal population. The commonest thoracic abnormality was the straight back, being present in 37.5% of the male and 26.9% of the female patients. Accurate quantitation of thoracic kyphosis was difficult. Either the ratio between antero-posterior and transverse thoracic diameters or a vertebral index characterised the straight back. Other abnormalities included scoliosis, sternal and rib deformities. The mean of metacarpal indices for the patients was also significantly higher than the normal mean. An abnormal metacarpal index was present in 20.9%. There was dissociation between peripheral and thoracic skeletal abnormalities. The diagnostic, aetiological and prognostic implications of associated skeletal abnormalities were discussed.
Three patients with lumbar anterior spinal fusion (two with Dwyer instrumentation) developed retroperitoneal fibrosis in relation to the operative site. This complication is possibly a reaction to the retroperitoneal insult. Haematoma, low-grade infection and metallic implant are other likely contributory factors. Its occurrence is affected by the laterality of surgical approach and extent of dissection. Radiologists should be aware of such a complication when investigating post-fusion patients. Early diagnosis and treatment prevent further renal damage.
Familial prevalence of mitral valve prolapse in a Chinese population was determined in 22 propositi of whom 10 had straight back (group A), three had abnormally high metacarpal index (group B), and nine had neither (group C). Of 71 (32 male and 39 female subjects) first degree relatives screened, mitral valve prolapse was found in 19 (seven male and 12 female subjects) (26.8%). The familial prevalence among groups A, B, and C was 20%, 30%, and 38.5%, respectively. Our study indicates that the familial occurrence of mitral valve prolapse does not depend on its association with the straight back syndrome.
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Choriocarcinoma is the most malignant tumor of gestational trophoblastic neoplasia. It grows rapidly and metastasizes to the lung, liver, and, less frequently, to the brain. Renal involvement is rare. Magnetic resonance imaging (MRI) is a useful modality to image the affected tissues; it contributes to the evaluation and management of the disease. One case of renal choriocarcinoma with MRI evaluation is reported.
Spinal cord ganglioglioma is a rare tumor most often encountered in the first three decades. Scanty computed tomography (CT) reports on the tumor describe it as a hypodense or cerebrospinal fluid (CSF) dense area with little contrast enhancement despite its solid nature. We report two cases of spinal ganglioglioma both involving almost the whole spinal cord. On magnetic resonance imaging (MRI), the tumors appear hypointense to the spinal cord on T1 and hyperintense to the cord on T2 images, and were mainly solid at exploration. It is important to recognize these tumors as long survival can be achieved after surgical resection.
The usefulness of computed tomography (CT) in guiding the management of 43 patients who had a complicated clinical course of acute pancreatitis was retrospectively studied. The CT scans were performed when patients had persistent fever, leucocytosis, hyperamylasaemia, palpable abdominal masses or when there was organ failure. The CT scans showed normal findings in six patients, features of pancreatic abscess in three patients, pseudocysts in three patients and inflammatory masses (a mixture of sterile inflammation and necrosis) in 31 patients. Patients with pancreatic abscesses underwent emergency laparotomy, drainage and debridement; patients with pseudocysts had delayed drainage unless complication occurred; patients with normal CT scan or findings of inflammatory masses were managed conservatively. For patients undergoing conservative management, repeated CT scanning and percutaneous aspiration of the inflammatory mass was performed when pancreatic sepsis was strongly suspected. By this approach, basing on careful clinical and CT scan surveillance, five patients with pancreatic sepsis (pancreatic abscess and localized abscess collection in pseudocyst) underwent emergency surgery and four survived, while 25 patients with inflammatory masses were successfully managed conservatively and some who may have been operated on clinical grounds were spared unnecessary early debridement surgery.
Over a period of 16 months, a total of 175 patients with newly diagnosed nasopharyngeal carcinoma (NPC) were evaluated with plain radiography and computed tomography (CT) of nasopharynx and base of skull. 54 of 175 patients (30.9%) had CT evidence of skull base erosion. Plain radiography failed to demonstrate the skull base erosion in 22 of 54 patients (40.7%) and underestimated the extent of bony involvement in another 21 patients (38.9%). In 14 of 54 patients (25.9%), there was also false suspicion of bony erosion in the plain films in one or more regions of the skull base which was not substantiated by CT and subsequent clinical course. The present study shows that plain radiography lacks sensitivity and specificity in detecting skull base erosion by NPC. CT evaluation of NPC patients should include thin CT sections of base of skull for detection of subtle bone erosion, and this would allow better decision concerning the shielding of the pituitary-hypothalamic axis during radiotherapy for improvement in therapeutic ratio. For the investigation of individuals highly suspicious of harboring NPC, even when the plain radiography is negative, CT should still be performed as this may give the only clue to the presence of a small submucosally spreading NPC.