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Biomedical subjects

B C Yung

Publications and source records attributed to B C Yung.

16 recordsLinked to original sources
PubMed2000

Aggressive thoracic actinomycosis complicated by vertebral osteomyelitis and epidural abscess leading to spinal cord compression.

STUDY DESIGN: Report of a successfully diagnosed and treated case of spinal cord compression due to epidural actinomycosis. OBJECTIVE: To illustrate that proper use of imaging strategy can greatly facilitate diagnosis and management of this rare condition. SUMMARY OF BACKGROUND DATA: Spinal actinomycosis causing epidural abscess and significant spinal cord compression is an uncommon condition. Although diagnosis is difficult, favorable results are widely reported when specific therapy is instituted. METHODS: A 32-year-old Chinese man had extensive dorsal thoracic soft tissue swelling and lower limb weakness. Collapse of the T5 vertebral body was found on plain radiographs with mediastinal infiltrates on chest radiograph. It took magnetic resonance imaging (MRI) to fully delineate the epidural abscess and dorsal muscular abscesses, which were not depicted by computed tomographic (CT) scan. Diagnosis was made by examination of CT-guided aspirate and tissue recovered during surgery by a microbiologist. The patient received high-dose intravenous penicillin and prompt spinal decompression once diagnosis of actinomycosis was confirmed. RESULTS: The dorsal muscular abscesses and upper thoracic epidural abscess resolved rapidly after intravenous antibiotics and surgical drainage. This was well documented by follow-up MRI and the full recovery of motor power and lower limb sensation in the patient. CONCLUSIONS: High clinical suspicion and proper use of imaging data led to timely diagnosis of this rare case of mediastinal, epidural, and intramuscular thoracic actinomycosis. Specific antibiotic therapy and timely, well-targeted surgical intervention greatly improve the outcome of this condition.

Actinomycosis↗
PubMed2000

Sporadic bilateral adrenal medullary hyperplasia: apparent false positive MIBG scan and expected MRI findings.

Adrenal medullary hyperplasia is a rare cause of clinical symptoms and biochemical findings identical to pheochromocytoma occurring mostly in multiple endocrine neoplasia patients. The scenario of positive MIBG scan, but no focal lesion found on CT and MRI led to diagnostic and management difficulties. Like pheochromocytoma, surgical excision can lead to clinical and biochemical recovery. We report this unusual case of sporadic bilateral adrenal medullary hyperplasia, with hypertension and biochemical abnormalities alleviated after surgical adrenalectomy. Based on T2 values reported in literature, high signal focal lesions may not appear on T2-weighted MRI images until development of frank pheochromocytoma. MIBG scan remains the most sensitive imaging modality for this condition.

3-Iodobenzylguanidine↗
PubMed2000

Angiomatosis of the hand demonstrated by contrast-enhanced magnetic resonance angiogram.

Contrast-enhanced digital subtraction dynamic MR angiography has been applied to lower limb arteries, with accuracy comparable to that of conventional angiography. Application of this technique to hands has not been reported. A 2-year-old girl with a diffuse haemangioma of the right hand elegantly demonstrated by MR angiogram is presented. The feeding vessel and the relationship with surrounding palmar blood vessels were clearly identified. This provided essential preoperative information facilitating surgical resection, yet without the technical difficulties and morbidity associated with conventional angiography.

Angiomatosis↗
PubMed2000

Acute suppurative thyroiditis due to foreign body-induced retropharyngeal abscess presented as thyrotoxicosis.

Acute suppurative thyroiditis is an uncommon condition. Most patients have preexisting oropharyngeal fistulae. Penetrating oropharyngeal injuries resulting from swallowed foreign bodies provide an acquired channel of infection spreading into the relatively resistant thyroid gland. The authors describe a patient with infective thyroiditis complicating retropharyngeal abscess caused by a chicken bone that perforated the upper esophagus. Transient thyrotoxicosis complicating acute suppurative thyroiditis is very rare. Pertechnetate and Ga-67 scans confirmed extensive inflammation of the thyroid gland and the release of hormones as the cause, as distinct from concurrent Graves' disease. Awareness of this unusual complication is important to avoid inappropriate treatment for hyperthyroid disease.

Acute Disease↗
PubMed1999

Negative captopril renography on patients with renin mediated hypertension due to page kidney and reninoma.

Through a mechanism similar to renal artery stenosis, patients with reninoma and page kidney also suffered from renin mediated hypertension. Captopril renograms performed on our patients with the latter two conditions, however, did not yield diagnostic findings. Therefore, equivocal or negative captopril renography cannot serve to rule out conditions with elevated renin other than renal artery stenosis.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1999

Important role of cardiac spect imaging in patients undergoing percutaneous transluminal coronary angioplasty.

OBJECTIVE: To examine the utilization and contribution of cardiac perfusion scans to patients undergoing percutaneous transluminal coronary angioplasty. METHODS: From July 1996 to January 1998, 34 patients underwent percutaneous transluminal coronary angioplasty and cardiac SPECT imaging was studied. Twenty-five patients had pre-procedure SPECT scans. The agreement between angioplasty strategies and SPECT findings of ischemia and hypokinesia was examined. RESULTS: When radionuclide imaging was performed before revascularization procedures, 84% of the patients had intervention strategies guided by scan findings. Perfusion scan findings including extent and severity of ischemia, degree of hypokinesia directed the selection of target vessel for angioplasty in the patient subgroup with multi-vessel disease. Post-angioplasty radionuclide cardiac scans were performed only on symptomatic patients, demonstrating ischemia and hypokinesia in most of them, conceivably reflected the selection bias. CONCLUSION: We recommend routine pre- and post-angioplasty radionuclide imaging with multigated scans for wall motion assessment for all patients receiving coronary intervention.

Aged↗
PubMed1998

Spinal cord compression caused by thoracic vertebral hemangioma involving only the posterior elements of two contiguous vertebrae.

An unusual case of symptomatic thoracic vertebral hemangioma involving two contiguous vertebrae but confined to the posterior elements is presented. The lesion displaced and compressed the cord. The diagnosis was not considered prior to biopsy. There was uncontrolled bleeding at biopsy. Only partial surgical resection was performed, with incomplete relief of motor weakness after initial surgery. The patient refused further surgical resection. Motor power was gradually recovered after a course of postoperative radiotherapy.

Hemangioma, Capillary↗
PubMed1997

Cerebral glucose utilization is reduced in second test session.

Cerebral glucose utilization was higher during the first positron emission tomography (PET) session than during the second session, as assayed using the PET [18F]fluorodeoxyglucose method in male human volunteers. This difference was due largely to data from subjects with low-trait anxiety, since subjects with high anxiety showed similar metabolism in both PET sessions. High-anxiety subjects showed greater right/ left ratios of cerebral metabolism than low-anxiety subjects, particularly during the second PET session. These findings suggest that the level of anxiety may be an important variable to consider in PET studies using multiple sessions.

Adult↗
PubMed1995

Cerebral glucose utilization in polysubstance abuse.

Regional cerebral glucose metabolism in subjects with histories of polysubstance abuse was compared to that in control subjects who were drawn from the same community. The substance abuse group showed lower absolute metabolic rates for glucose in lateral occipital gyrus and higher normalized metabolic rates in temporal and frontal areas, including orbitofrontal cortex. It is suggested that some patterns of brain function associated with polysubstance abuse may represent consequences of drug exposure, or they could reflect pre-existing differences that may be relevant to the etiology and maintenance of polysubstance abuse.

Adult↗
PubMed1994

Kidney-to-liver ratio. A simple scintigraphic parameter for routine individual renal function assessment in children.

DTPA renography is commonly used for measuring relative renal function. However, in patients with bilateral renal disease or solitary kidneys, split function studies are of no value. Available techniques to quantify individual renal function are either time consuming or inaccurate. The authors validate the kidney-to-liver ratio at 3 minutes (K3/L3) as an index of renal function, showing excellent correlation with GFR. Normal K3/L3 ranges were then computed in 113 pediatric kidneys (age 2 days to 16 years) and 24 adults. Indicative of renal maturation, the K3/L3 rapidly rose from a value of 1.32 at birth to 2.02 at 6 months. Subsequently, it increased slowly to reach a peak of 2.34 at age 2, followed by gradual decline to adult values after age 5. This decrease is due likely to continued growth of the hepatic blood pool after renal maturation. GFR followed the same maturation pattern to reach a plateau around 2 years of age. K3/L3 reflects individual kidney function, and it requires no blood sampling or urine collection. By establishing normal values at different stages of maturity, this method provides identification and quantification of renal dysfunction in infants, children, and adults.

Adolescent↗
PubMed1993

Comparison of left anterior oblique, anterior, and geometric mean methods in gastric emptying assessment of postpancreaticoduodenectomy patients.

Although left anterior oblique (LAO) gastric emptying studies appear to be an adequate alternative to geometric mean (GM) measurements in patients with normal gastric anatomy, it is not clear whether they can be used after gastric or duodenal surgery. In this study, dual-phase gastric emptying studies with combined solid-liquid meal were performed in 54 patients who had undergone pancreaticoduodenectomy (Whipple procedure). Gastric emptying was studied with GM, LAO, and anterior (ANT) methods. T1/2 and percent gastric retention at 10, 30, 60, 90, and 120 minutes were calculated. Results from the three methods were compared using correlation analysis and the t test. The t test showed no significant difference in T1/2 and percent retention values between the GM and LAO or ANT views. The solid emptying T1/2 showed a better correlation between GM and LAO values (r = 0.824) than between GM and ANT (r = 0.589). For the liquid T1/2, the reverse was true. Correlation between GM and ANT (r = 0.939) was better than between GM and LAO (r = 0.839); however, both LAO and ANT views correlated well with GM liquid emptying. It is concluded that the LAO view can replace GM gastric emptying methods in postpancreaticoduodenectomy patients for evaluation of both solid and liquid emptying, although the ANT view appears completely adequate for the study of liquid emptying.

Adenocarcinoma↗
PubMed1993

Sensitivity to subjective effects of cocaine in drug abusers: relationship to cerebral ventricle size.

OBJECTIVE: The purpose of this study was to assess the functional significance of ventricle-brain ratio (VBR) in terms of how it might affect sensitivity to cocaine, an indirect dopamine agonist. METHOD: Relationships between VBR and subjective responses to acute intravenous cocaine hydrochloride were examined in 20 male polydrug abusers. Tests were performed in conjunction with positron emission tomography scans to measure cerebral glucose metabolism. RESULTS: Subjective measures of effects of cocaine, including self-report ratings of intensity of the drug effect, scores on the morphine-benzedrine scale of the Addiction Research Center Inventory, and several items on visual analogue scales, correlated negatively with VBR. VBR also differed significantly among subjects who were grouped according to scores on items ("rush" and "crash") of the Cocaine-Sensitive Scale (larger VBR in subjects with weaker responses). VBR was not correlated with cocaine-induced changes in cerebral metabolic rates for glucose. CONCLUSIONS: Relative insensitivity to the subjective effects of cocaine in polydrug abusers with ventricle enlargement suggests that ventriculomegaly may reflect changes in periventricular brain regions that mediate these effects of cocaine.

Adult↗
PubMed1993

Lag phase in solid gastric emptying: comparison of quantification by physiological and mathematical definitions.

Lag phase is considered an important parameter of solid gastric emptying studies. However, different methodologies with their own normal values and physiologic implications are advocated for lag phase measurements. We applied both physiologic and mathematic approaches to quantify lag phases from identical image data sets for direct comparison of these two approaches. Gastric emptying studies were performed on 22 patients using a standard solid meal to calculate the lag phase in each using three different methods: (1) visual analysis to determine time when activity first appeared in the duodenum (LagPh); (2) time-activity curves to determine time of 2% decrease from peak stomach activity (LagCu); and (3) a mathematical definition using the modified power exponential method (TLAG). In addition, time of peak antral activity (AntPk) was calculated. The values for LagPh and LagCu were very similar (mean: 14.6 versus 15.2 min) and correlated well with each other (r = 0.89). TLAG using the power exponential showed different values (mean: 34.7 min) and correlated well only with AntPk (mean: 35.1 min; r = 0.92). We conclude that LagPh and LagCu estimate the time of onset of gastric emptying; the time when the smaller particles in the meal (< 1-2 mm) begin to leave the stomach (onset of variable emptying phase). On the other hand, TLAG and AntPk estimate total trituration time (time for most of meal to be processed) and signal the beginning of the constant gastric emptying phase.

Adult↗
PubMed1993

Normalized clearance-to-uptake slope ratio: a method to minimize false-positive diuretic renograms.

The success of diuretic renography in the evaluation of children with renal outflow tract obstruction has been hampered by a high incidence of false-positive and indeterminate results. The main causes of interpretative errors are collecting system dilatation and impaired renal function. In this prospective study, we introduce a parameter with the potential to overcome these two problems: the normalized slope ratio (SRn). This ratio is calculated from the division of the maximum renal clearance slope by the maximum renal uptake slope, both normalized to peak renal activity. Fifty-one children (94 renal units) were evaluated. Traditional parameters such as diuretic half-time and percentage of retention at 30 min showed specificities of 77% and 85%, respectively. However, the normalized clearance slope increased specificity to 94% and SRn further improved it to 98%. The SRn takes into account the renal uptake curve, whose slope is dependent on glomerular function, and thus may correct for renal dysfunction. It also differentiates obstructed from patent kidneys even in cases with significant collecting system dilatation. As shown by regression analysis, it is independent of collecting system size. We recommend the routine use of this parameter to reduce false-positive and indeterminate results of diuretic renograms.

Adolescent↗