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Biomedical subjects

S H Ng

Publications and source records attributed to S H Ng.

At least 37 records · Page 2Linked to original sources
PubMed2001

Proton magnetic resonance spectroscopy of cerebral glioma after irradiation.

BACKGROUND: Conventional magnetic resonance imaging (MRI) is commonly employed to assess cerebral gliomas after radiotherapy, but it cannot always differentiate tumor regrowth from post-irradiation changes. In this study, we utilized magnetic resonance spectroscopy (MRS) to evaluate changes in cerebral metabolites in patients with a cerebral glioma after irradiation. METHODS: Over a period of 3 years, we performed MRS after MRI whenever soft tissue masses were found on magnetic resonance (MR) images. A total of 122 MR spectra of 58 patients was used for analysis. Spectral interpretations were based on integral values of the N-acetylaspartate (NAA) and choline (Cho) compounds relative to phosphocreatine/creatine (Cr). RESULTS: Our MRS study showed that higher Cho/Cr ratios occurred in regrowing gliomas than for stable diseases (range, 0.9 to 9.5 vs. 0.4 to 2.1; mean, 3.0 vs. 1.2). A greater increment in the Cho/Cr ratio between successive studies was also noted in regrowing gliomas than for stable disease (range, 41% to 87% vs. < 32%). No significant differences in NAA/Cr ratios or lactate were found between these 2 groups. None of our patients exhibited abnormal MR spectra in the mirror area of the contralateral brain. CONCLUSION: MRS provides valuable information about the metabolism of irradiated gliomas and can be used to exclude radiation encephalopathy of the contralateral brain. Cho is the most reliable indicator of a regrowing glioma. A high Cho/Cr ratio or substantial elevation in the Cho/Cr ratio between serial studies increases the likelihood of tumor regrowth. However, lower Cho/Cr ratios were inconclusive for determining if tumor regrowth or a stable process was occurring.

Brain↗
PubMed2000

Sonographic and pathologic findings in typical and atypical medullary carcinomas of the breast.

PURPOSE: We investigated whether there was a relationship between the sonographic and histologic appearances of medullary carcinomas of the breast to determine whether sonography is helpful in the differentiation of typical and atypical medullary carcinomas. METHODS: We retrospectively reviewed the histologic slides and sonograms of 20 patients who had been diagnosed with medullary carcinoma of the breast. We then classified the carcinomas as typical or atypical based on strict histologic criteria. We also evaluated the relationship between sonographic findings and the histologic reclassification. RESULTS: Eight (40%) of the 20 medullary carcinomas were classified as typical, and 12 (60%) were classified as atypical. On sonography, a smooth outline was visualized in 6 (75%) of the 8 typical medullary carcinomas but in none of the 12 atypical carcinomas. A jagged margin was sonographically visualized in 10 (83%) of the 12 atypical carcinomas, and a focal irregularity in the margin was visualized in 2 (17%) of the 12 atypical carcinomas. Four of the typical medullary carcinomas had posterior enhancement, and 9 of the atypical medullary carcinomas showed retrotumoral shadowing. The difference in tumor-margin regularity between typical and atypical medullary carcinomas was found to be statistically significant (p < 0.001) using the 2-tailed Fisher's exact test. CONCLUSIONS: To prevent overdiagnosis of medullary carcinoma, a thorough pathologic review of the entire tumor is recommended if sonography shows a jagged margin or a margin with focal irregularity.

Adult↗
PubMed2000

Locally recurrent nasopharyngeal carcinoma.

PURPOSE: To assess the outcome of and determine prognostic factors for locally recurrent nasopharyngeal carcinoma (NPC) in patients treated with a second course of radiotherapy (RT). MATERIALS AND METHODS: From 1982 to 1995, 186 NPC patients, who had initially been treated in the Department of Radiation Oncology, Chang Gung Memorial Hospital-Linkou, developed local recurrence in the nasopharynx and were re-treated with RT (>/=20 Gy). The time from the initial RT to re-treatment ranged from 8 to 136 months (median: 23 months). All patients were treated with external RT and conformal radiotherapy was used in 35 patients after 1993. Fifteen received radiosurgery as a boost treatment. The RT dose at the nasopharyngeal tumor area ranged from 20 to 67.2 Gy (median 50 Gy). Eighty-two patients received one to eight courses of cisplatin-based chemotherapy in addition to RT. RESULTS: The 1-, 3- and 5-year survival was 54.9, 22. 1 and 12.4%, respectively. Patients whose tumor relapsed later than 2 years after the first treatment had a better survival than those with earlier relapse (3-year survival: 30.1 vs. 10.8%; P=0.015), but the difference became insignificant in patients who received >/=50 Gy. Patients without evidence of intracranial invasion or cranial nerve palsy had better survival than those with such lesions (3-year survival: 30.9 vs. 3.7%; P=0.006). A re-treatment dose >/=50 Gy yielded better survival (3-year survival: 22.8 vs. 18.5%; P=0.003). Addition use of radiosurgery may improve survival. The use of chemotherapy did not improve survival. Conformal radiotherapy resulted in significantly fewer severe complications than conventional RT. CONCLUSIONS: A repeat course of RT for locally recurrent NPC successfully prolongs survival in a significant number of patients. Intracranial invasion and/or cranial nerve palsy and re-treatment dose affect the prognosis, with a dose of >/=50 Gy significantly improving survival. Radiosurgery boost may also improve survival. Our preliminary data indicates that conformal radiotherapy may decrease the severity of radiation-induced complications. However; longer follow-up and larger sample size is necessary to document the findings.

Adult↗
PubMed2000

Magnetic resonance imaging versus clinical palpation in evaluating cervical metastasis from head and neck cancer.

We prospectively compared the value of MRI and clinical palpation for detecting cervical metastases in patients with primary cancer of the head and neck. Sixty patients with squamous cell carcinoma of the upper aerodigestive tract were evaluated with MRI and clinical palpation before undergoing a total of 81 neck dissections. The results of preoperative clinical palpation and MRI were compared with the histopathologic outcome. The sensitivity and specificity were 75.6% and 97.5%, respectively, for clinical palpation and 73.2% and 95%, respectively, for MRI. The rate of occult cervical metastasis was 24% with clinical palpation and 26.8% with MRI. The use of MRI did not improve the rate of early detection of occult metastasis, nor did it improve the detection of extracapsular spread. Our findings show that we could not depend on palpation or MRI alone to determine the need for elective neck dissection. However, MRI can be used to improve the preoperative grading of cervical lymph nodes. In selected cases, this may direct surgeons to convert the treatment plan to choose a more conservative neck dissection or, after sentinel node sampling and frozen-section control, to convert the treatment to a more radical dissection.

Head and Neck Neoplasms↗
PubMed2000

Values and beliefs of vegetarians and omnivores.

Following the claim by some anthropologists and sociologists that 1 symbolic meaning of meat is a preference for hierarchical domination (C. J. Adams, 1990; N. Fiddes, 1989; D. D. Heisley, 1990; J. Twigg, 1983), the authors compared the values and beliefs of vegetarians and omnivores in 2 studies conducted in New Zealand. They compared the full range of vegetarians and omnivores on right-wing authoritarianism, social dominance orientation, human values, and consumption values. The participants tending toward omnivorism differed from those leaning toward veganism and vegetarianism in 2 principal ways: The omnivores (a) were more likely to endorse hierarchical domination and (b) placed less importance on emotional states. Accordingly, the acceptance or rejection of meat co-varied with the acceptance or rejection of the values associated with meat; that finding suggests that individuals consume meat and embrace its symbolism in ways consistent with their self-definitions.

Authoritarianism↗
PubMed2000

Choledochal cyst associated with acute acalculous cholecystitis.

A 7-year-old girl underwent laparotomy for suspected acute appendicitis. Instead, bile peritonitis with hydrops of gallbladder and normal appendix were noted. Dilatation of the CBD was observed, and choledochal cyst was documented by intraoperative cholangiography. Cholecystectomy and T-tube placement were performed. Postoperative follow-up by ultrasound lasted for 9 months. The CBD remained the same size without clinical manifestation.

Acute Disease↗
PubMed2000

Embolization of a pulmonary arteriovenous fistula by electrolytic detachable coils: case report.

Transarterial embolization with detachable coils is a technique commonly used for the treatment of intracranial aneurysms. We report on a patient with a pulmonary arteriovenous fistula (PAVF) treated successfully with this technique. The patient presented with a history of intermittent hemoptysis, nasal bleeding, numbness of the upper extremities, and seizures. Computed tomographic angiography and magnetic resonance angiography demonstrated a single-hole arteriovenous fistular lesion in the left lower lung. Pre-embolization superselective pulmonary angiography revealed multiple fistulae communicating to the venous sac of the lesion. Eleven detachable coils were deployed into the venous sac, with resultant total occlusion of the pulmonary arteriovenous fistula. We conclude that venous sac embolization in treating this kind of patients is effective. The combined use of a microcatheter system and electrolytic detachable coils may be an excellent technique for achieving this kind of embolization. Superselective angiographic evaluation is essential before embolization, because many occult feeders can be present in cases of high-flow PAVF.

Adult↗
PubMed2000

The value of MRI in the diagnosis and management of neurocysticercosis.

The clinical manifestation of neurocysticercosis is quite protean and variable making it the 'great imitator' of almost any neurological disorder. In the last decade, developments in diagnostic imaging and effective anticysticercus drug therapy have changed the outlook of the disease. Two cases investigated with CT scan and MRI are reported here. One case was treated effectively with antihelminthic therapy. In both cases MRI was found to be much more sensitive than CT scan in picking up the multiple cystic lesions. In addition, 'protoscoleces' and 'differential ring enhancements' not apparent in CT scan were well shown in MRI hence enabling the demonstration of different activity stages. In the treated patient, repeat MRI showed degeneration of the cyst. These illustrate that MRI is superior to CT scan in both the diagnosis and management of the illness.

Adult↗
PubMed2000

Limb myorhythmia in association with hypertrophy of the inferior olive: report of two cases.

We report on 2 patients who uncommonly developed isolated limb myorhythmia in association with inferior olive hypertrophy (IOH) after an acute stroke in the brain stem. A slow tremor presented in the proximal upper limbs predominantly when at rest. It was aggravated by outstretched arms and by active hand movements. The surface electromyogram (EMG) recorded simultaneous activities over the agonist and antagonist muscles with a rate of 3.5 Hz and 2.5 Hz in 2 patients respectively. In the first patient, bilateral limb myorhythmia presented 12 months after the brain stem stroke, and both inferior olives were hypertrophic. In the second patient, unilateral limb myorhythmia developed in the left hand 7 months after right pontine hemorrhage, and only the right inferior olive was hypertrophic. These findings indicate that limb myorhythmia commencing after brain stem insult is anatomically and temporally related to hypertrophy of the contralateral inferior olive. Based on our 2 patients and previously reported cases, we propose that a possible causal relationship exists between limb myorhythmia and contralateral IOH, although its pathophysiological mechanisms remain to be established. We suggest that, similar to palatal myoclonus, isolated limb myorhythmia is within the clinical spectrum of IOH.

Brain Stem↗
PubMed1999

MRI in recurrent nasopharyngeal carcinoma.

In this study, we retrospectively reviewed the MRI features of recurrent nasopharyngeal carcinoma (NPC) in 72 patients who underwent MRI before and after gadolinium injection. Recurrent NPC exhibited a high degree of regional spread and a variety of signal intensities and contours. MRI showed a nasopharyngeal mass in 50 patients (69.4 %); other sites of involvement included the parapharyngeal space (44.4 %), nasal cavity (12.5 %), paranasal sinuses (27.8 %), oropharynx (4.2 %), orbit (8.3 %), infratemporal fossa (18.1 %), skull base (59.8 %), intracranial area (51.4 %) and regional lymph nodes (15.3 %). On T2-weighted images, the nasopharyngeal mass gave high signal in 9 of 50 cases (18 %), intermediate in 27 (54 %), mixed in 8 (16 %) and low signal in 6 (12 %). Contrast enhancement was strong in 12 cases (24 %), moderate in 29 (58 %) and heterogeneous in 9 (18 %). The lesion was convex in 31 cases (62 %) and concave or straight in 19 (38 %). Recognition of the distribution and the appearance of recurrent NPC on MRI is essential for timely diagnosis and appropriate treatment.

Adult↗
PubMed1999

Magnetic resonance imaging of nasopharyngeal carcinoma.

Nasopharyngeal carcinoma (NPC) is a malignant tumor that shows distinct distributions into geographical and into well-defined high-risk ethnic groups. Radiation therapy is the mainstay of treatment, and imaging plays a central role in tumor mapping and post-treatment follow-up. Magnetic resonance imaging is better than computed tomography in demonstrating tumor extent, tumor recurrence, and postradiation complications. However, differentiating postradiation changes from tumor recurrence may be difficult using magnetic resonance imaging. Mucosal recurrence is best detected with endoscopy.

Adolescent↗