Biomedical subjects

M M Teng

Publications and source records attributed to M M Teng.

At least 55 records · Page 3Linked to original sources

PubMed1997

Intracranial ganglioglioma: CT and MRI findings.

Thirteen cases of pathologically proved intracranial gangliogliomas were reviewed in order to define the characteristic computed tomography (CT) and magnetic resonance image (MRI)-features. All patients were evaluated with CT and four of them were studied by MRI. Six tumors were cystic dominant mixed masses with remarkable focal contrast enhancement (6/13, 46%); and seven were solid in nature with variable contrast enhancement (7/13, 54%). Nine of them contained calcification (9/13, 69%). The temporal lobe was affected in six patients (6/13, 46%); the posterior fossa in four patients; the frontal lobe in two; the remaining huge one in the frontal, temporal and basal ganglion. On MRI, the findings were similar to those of the CT. Gangliogliomas do not have a characteristic CT and MRI features. They may appear as pure cystlike tumors, cystic dominant mixed tumors with remarkable focal contrast enhancement, solid tumors with variable contrast enhancement or diffuse involving the brain parenchyma and/or subarachnoid spaces. However, radiologists should include ganglioglioma in the differential diagnosis when we find patient has a long-standing process as well as a calcified tumor in the temporal lobe with following characteristic; cystic dominant mixed tumor with remarkable focal contrast enhancement, or a solid mass without hemorrhage or significant surrounding edema.

Adolescent↗

PubMed1997

Measuring tibial cortical bone status by ultrasonic velocity.

BACKGROUND: Post-menopausal osteoporosis has become a serious public health problem with the increase of the geriatric population. Dual energy x-ray absorptiometry (DEXA) is the most common method for diagnosis of osteoporosis by quantitative change of bone, but recently there is increasing interest in measuring both qualitative and quantitative changes of bone by ultrasound. This study measured ultrasound velocity of anterior tibial cortex to evaluate the feasibility of detecting cortical bone status by speed of sound (SOS). METHODS: SOS in anterior tibial cortex was measured on 205 females referred from clinicians for routine bone mineral density (BMD) measurement. These females were divided into 2 groups. Group 1 consisted of 170 females aged from 30 to 75 years (mean: 55.2 +/- 9.3 years), who never received estrogen therapy. Group 2 consisted of 35 females in the post-menopausal status aged ranged from 45 to 69 years (mean: 51.5 +/- 3.5 years), who had received estrogen gel or oral estrogen tablet (0.625 mg/day) replacement therapy for prevention of postmenopausal osteoporosis for a period of 6 to 68 months (mean: 25.3 +/- 2.3 months). For precision test, 3 volunteers whose SOS was measured by 2 different operators were also enrolled in our study. BMD by DEXA of L-spine and/or hip was also performed on the same day of SOS examination. We analyzed the precision of this new method, calculated mean value of SOS to see if there was any difference with respect to pre- at, and post-menopausal status between estrogen users and nonusers by SOS, and tried to find the relationship of SOS with body habitus and BMD. RESULTS: Mean value of SOS of group 1 females was 3852 +/- 150.3 m/s, with peak value in the fourth decade. There were inverse correlation of SOS with age (r = -0.36, p < 0.0005) and the period after menopause (r = -0.32, p < 0.0005). The decreasing rate of SOS per decade from 31 to 50 years of age was 1.7%, while that of 51 to 70 years was 4.3% in group 1 females. With regard to menopausal status, there was significant difference of SOS between pre- and post-menopausal females (p = 0.01, ANOVA test), between at and post-menopausal females (p = 0.02). Significant difference (p < 0.05, ANOVA test) between group 2 estrogen users and group 1 postmenopausal nonusers was also noted. There was no evidence of correlation of body weight or height with SOS. Both inter- and intra-operator precision of SOS was under or equal to 0.32%. Moderately correlation between SOS and BMD was noted. CONCLUSIONS: Our study demonstrated good precision in SOS measurement of tibial cortical status. It was inversely correlated with age and post-menopausal period; it also significantly discriminated estrogen users from nonusers, and pre-, at from post-menopausal subgroups. However, for further evaluation of the relationship between SOS and the most severe complication of osteoporosis, i.e. osteoporotic fracture, population-based long-term followup is still required.

Adult↗

PubMed1996

Do we need conventional angiography? The role of magnetic resonance imaging in verifying obliteration of arteriovenous malformations after Gamma Knife surgery.

Sixteen cerebral arteriovenous malformations (AVMs) were examined to determine the role of magnetic resonance (MR) imaging in verifying obliteration. The AVMs (mean volume 7.5 cm3, range 2-17 cm3) were treated with Gamma Knife surgery between March 1993 and May 1994. Integration of stereotactic MR and stereotactic conventional X-ray angiography (XRA) was used for targeting in the Gamma Knife surgery. All MR examinations both for targeting and follow-up, were performed on a 1.5-Tesla superconductive MR scanner (Signa). Multiple pulse sequences (spin echo T1- and T2-weighted MR imaging, and three-dimensional time-of-flight MR angiography) were used. The mean maximum target dose was 37.4 Gy (range 25.0-44.0 Gy). The mean minimum target dose was 20.1 Gy (range 17.5-25.2 Gy). Follow-up imaging was performed about every 6 months or when clinically warranted. XRA was performed when the AVM was no longer seen on MR images. The time from the last MR image to the XRA was within 1 month in nine patients, and longer in seven. MR imaging demonstrated regressing AVMs in all patients as early as 3 months after Gamma Knife surgery. For seven of the nine patients total obliteration on MR was confirmed on XRA within 1 month. In the other two, previous hemorrhage and adverse radiation effects probably caused overestimation of AVM obliteration. In the remaining seven patients, XRA confirmed the MR observation although the time intervals were longer. It is concluded that, for medium- to large-volume AVMs, MR can demonstrate not only the regressing AVMs but also verify total obliteration. However, verification has to be based on an integration of MR imgaging and MR angiography. The use of MR reduces the invasiveness of Gamma Knife surgery for cerebral AVMs.

Adolescent↗

PubMed1995

Granular cell tumour of the neurohypophysis.

Granular cell tumours of the neurohypophysis are very rare. Their aetiology and nature are uncertain. Most investigators consider them to arise from pituicytes or Schwann cells of the posterior lobe of the hypophysis. They are found most commonly in older people. A surgically proven symptomatic case is reported.

Adult↗

PubMed1995

Embolization of carotid cavernous fistula by means of direct puncture through the superior orbital fissure.

PURPOSE: To embolize carotid cavernous fistulas (CCFs) by means of transorbital puncture of the cavernous sinus (CS) and the cavernous segment of the internal carotid artery (ICA) through the superior orbital fissure. MATERIALS AND METHODS: Five patients with CCF were treated with embolization of the CS, and six were treated with embolization of both the CS and the cavernous portion of the ICA after transorbital puncture. All except one had previously undergone occlusion of the ipsilateral proximal ICA before direct transorbital puncture. RESULTS: The fistulas in these cases were all obliterated completely. Only two patients had temporary ptosis. No other remarkable complications were noted. The patent ICA on the side of the fistula in one patient remained patent after embolization. CONCLUSION: Direct transorbital puncture through the superior orbital fissure is an alternate treatment for CCF, especially when the ipsilateral ICA has been occluded.

Adult↗

PubMed1995

Transorbital color Doppler flow imaging of the carotid siphon and major arteries at the base of the brain.

PURPOSE: To describe and evaluate an application of sonography, transorbital color Doppler flow imaging of the carotid siphon and major intracranial arteries, and to compare it with transtemporal color Doppler flow imaging. METHODS: The carotid siphon and major arteries at the base of the brain of 50 healthy volunteers were screened using the transorbital color Doppler flow sonography. These arteries were also studied by a transtemporal approach for comparison. In 5 volunteers, MR images in special inclination planes were obtained and compared with the transorbital color-coded Doppler flow images. RESULTS: The B-mode image of the orbit and intracranial anatomic structures, in addition to the color-coded flow images, provided an unambiguous identification of the carotid siphon and major intracranial arteries. The failure rate was lower when using the transorbital approach than when using the transtemporal approach in identifying the anterior cerebral artery (17% versus 32%). Color Doppler flow imaging using the transtemporal approach was better for the middle cerebral artery, whereas color Doppler flow imaging using the transorbital approach was better for the anterior cerebral artery (contralateral). The Doppler incident angles using the transorbital approach were better for the carotid siphon and anterior cerebral artery (contralateral). CONCLUSION: Transorbital color Doppler flow imaging, when used in conjunction with the transtemporal examination, can add information concerning the major arteries at the base of the brain.

Adult↗

PubMed1994

N-butyl-2-cyanoacrylate for embolisation of carotid aneurysm.

We report the use of an N-butyl-2-cyanoacrylate (NBCA) mixture for embolisation of six cases of carotid aneurysm after detachable balloons, and/or microcoils had been placed in the aneurysm. The mixture was injected into the aneurysm to prevent delayed bleeding or distal migration of the balloons, or microcoils. No subarachnoid haemorrhage or distal migration of the balloons or microcoils occurred up to 4.5 years after embolisation. Reflux of the NBCA mixture into the parent artery occurred in one patient, who had a neurological deficit which recovered in a month. NBCA mixture may be useful in embolisation of intracranial or skull base arterial aneurysms, for reducing the size of remaining lumen in an aneurysm at high risk of rebleeding which accommodate no more balloons or microcoils, or preventing possible delayed migration of balloons or microcoils. However, prevention of leakage of the mixture into the parent artery remains a problem.

Adult↗

PubMed1994

Syncope as the presenting symptom of nasopharyngeal carcinoma.

Syncope is a rare symptom of nasopharyngeal carcinoma, a common tumor in Taiwan. We describe two patients with nasopharyngeal carcinoma who presented with frequent syncopal attacks five months before the diagnosis was made. We postulate that the mechanism of syncope is involvement of the glossopharyngeal or vagal nerve by para-pharyngeal extension of the tumor.

Aged↗

PubMed1994

Duplex ultrasound of extracranial carotid artery in a male patient of Takayasu's arteritis: a case report.

Takayasu's arteritis is a chronic inflammatory disease of artery. Its etiology is still uncertain. The disease mostly involves aorta and its major branches. We recently examined a young male patient using duplex Doppler ultrasound (DUS). High resolution real-time ultrasound revealed long-segment stenosis over common carotid arteries on both sides and internal carotid arteries, mostly due to adventitia thickening. Doppler ultrasound showed increased blood velocity of bilateral common carotid arteries with spectral broadening. B-mode findings correlated well with those of Doppler's, and all the information obtained from DUS was compatible with those of angiography. DUS is helpful in diagnosis of Takayasu's arteritis and provides hemodynamic data of the diseased carotid arteries. It can also be used as an effective tool for follow-up in patients with Takayasu's arteritis.

Adult↗

PubMed1994

Computed tomography evaluation of chronic paranasal sinusitis.

BACKGROUND: Although chronic paranasal sinusitis has been recognized and diagnosed more frequently in recent years, it is still one of the most frequently overlooked disease and a significant source of morbidity and economic loss. Therefore, a further detailed analysis of its clinical pictures and computed tomographic (CT) presentations is necessary for better understanding. METHODS: We collected 230 cases in recent two years and studied their CT manifestations. RESULTS: The pathological changes of sinusitis on CT were classified into four groups: mucosal thickening, mucosal thickening combined with fluid level, fluid level only, and total sinus opacification, in increasing frequency. Maxillary sinus was the most commonly involved sinus. Focal high density areas were noted in 17 sinuses. Ten of them were operated and revealed only thick mucous without evidence of calcification or fungal infection. There was no correlation between the disease duration and the number of sinuses involved. CONCLUSIONS: CT is the image modality of choice in evaluating patients with chronic paranasal sinusitis.

Adolescent↗

PubMed1993

Posterior cranial fossa tumours in childhood.

We reviewed clinical and CT findings in 133 posterior cranial fossa tumours in children. All had histological diagnosis, apart from 20 cases of brain stem glioma. The majority were intra-axial tumours, including 53 medulloblastomas (40%), 31 cerebellar astrocytomas (23%), 28 brain stem gliomas (21%), 14 ependymomas (11%), and single cases of ganglioglioma, haemangioblastoma and teratoma. Extra-axial tumours formed only 3%, including 2 chordomas and 2 schwannomas. The clinical data and CT findings are reviewed. Cerebellar astrocytoma involved the sexes equally, while medulloblastoma, brain stem glioma, and ependymoma were more common in males. Most cerebellar astrocytomas were in the midline, and presumably arose from the vermis. The frequency of calcification was similar to that in previous reports, being highest in ependymoma (69%), followed my medulloblastoma (29%), cerebellar astrocytoma (17%), and brain stem glioma (8%).

Astrocytoma↗

PubMed1993

Color Doppler imaging of orbital arteries for detection of carotid occlusive disease.

BACKGROUND AND PURPOSE: Distal to a hemodynamically significant stenosis, the Doppler effect becomes dampened. Thus, measuring the flow profile in the ophthalmic artery and the central retinal artery with color Doppler imaging may provide hemodynamic information about the carotid circulation. METHODS: To validate the flow profile measurement with color Doppler imaging in the ophthalmic and central retinal arteries and to determine the sensitivity and specificity of this examination in the detection of hemodynamically significant carotid stenosis, we compared color Doppler imaging examinations with ocular pneumoplethysmography and ophthalmodynamometry examinations in 66 patients with atherothrombotic ischemic cerebrovascular disease. The degree of carotid stenosis in these patients was determined by a duplex scan with color Doppler imaging, and 57 patients underwent angiography to verify the stenosis. RESULTS: The flow velocities (systolic peak velocity and end-diastolic velocity) and pulsatility indices (A/B ratio and resistance index) in the ophthalmic and central retinal arteries decreased as the degree of carotid stenosis increased. There is a statistically significant difference in the mean of systolic peak velocity and the mean of end-diastolic velocity of the ophthalmic and central retinal arteries among groups with various degrees of carotid stenosis (P < .02). Using the flow velocities of the ophthalmic and central retinal arteries to diagnose carotid stenosis (> or = 75% stenosis and occlusion), 8 cm/s for systolic peak velocity in the central retinal artery and 29 cm/s for systolic peak velocity plus flow direction reversal in the ophthalmic artery gave the maximum accuracy (sensitivities, 84% and 85.7% and specificities, 89.6% and 81.7%, respectively). The systolic peak velocity in the central retinal artery varied directly with the systolic pressure of the ophthalmic and central retinal arteries. CONCLUSIONS: The flow velocity and pulsatility in orbital arteries examined by color Doppler imaging provide further hemodynamic information; this test can be used to complement current sonographic examination of carotid disease.

Aged↗

PubMed1993

Relationship between periventricular lucencies on computed tomographic scans and vascular dementia.

We evaluated 48 consecutive patients with periventricular lucencies (PVL) on CT scan of brain to determine the clinical significance of this finding. Twenty-one (43.7%) patients were demented; 27 (56.3%) patients had no dementia but had various other diseases. PVL were frequently associated with hypertension and previous stroke. We used a PVL scoring system to evaluate the degree of PVL. When the score was greater than 3.5, the sensitivity and specificity in separating vascular dementia from other diseases with PVL were 78% and 67% respectively (Kappa = 0.42). We conclude that although mild PVL may be a frequent but non-specific finding in patients with hypertension or previous stroke, moderate and severe PVL should raise the possibility of vascular dementia.

Age Factors↗

PubMed1992

Aspergillosis of the paranasal sinuses.

The CT appearances of 13 cases of pathologically proven aspergillosis involving paranasal sinuses were reviewed. Symptoms included rhinorrhea, nasal obstruction, headache, facial pain and foul smell from the nose. At operation, these lesions appeared yellowish, brownish, grey or black in colour, and contained dirty or muddy material. Microscopic examination of the tissue removed showed an Aspergillus ball with chronic inflammation but without invasion of the nasal or sinus mucosa in 6 cases, and tissue invasion with necrosis and inflammation in 7. The structures involved, in order of frequency, were: maxillary sinus, nasal cavity, ethmoid sinus, orbit and cavernous sinus. The orbit was involved in 2 cases, therefore categorized as invasive; the other 11 cases were non-invasive as judged by CT. Calcification was seen in the lesions of 9 cases. In most cases the adjacent bony structures showed areas of erosion and sclerosis. Aspergillosis should be suspected in the presence of a mass in the paranasal sinuses or nasal cavity with calcification within it, which may not appear solid or dense and is separate from the walls of the sinus.

Aged↗

PubMed1992

Spinal dural arteriovenous anomalies.

The clinical data, radiologic findings, and treatment in 14 cases of spinal dural arteriovenous (AV) anomaly were reviewed. All patients had typical findings of feeding artery, nidus, and draining vein on spinal angiograms. Radiologic diagnosis of spinal AV malformation was first made after myelography in 13 cases and after magnetic resonance (MR) imaging in one case. Thirteen patients underwent embolization; one patient underwent repeat embolization 14 months after the first procedure. The other patient underwent surgical ligation. All patients had clinical improvement after treatment. A high index of clinical suspicion, a complete myelographic examination or an MR image of good quality, and a properly performed complete spinal angiographic study are important for early diagnosis. Embolization may be the treatment of choice. For best results, the feeding artery next to the nidus and the draining vein close to the nidus should be occluded, and the nidus itself should be obliterated.

Adult↗

PubMed1992

Cerebral infarction in young men with nephrotic syndrome.

BACKGROUND AND PURPOSE: Thrombosis is one of the main complications of nephrotic syndrome; however, cerebral infarction associated with nephrotic syndrome has been rarely reported. SUMMARY OF REPORT: We describe acute cerebral infarction in two young men with nephrotic syndrome. Both had a hypercoagulable state based on hemostatic studies. By retrospectively reviewing the medical records of the past 10 years at our hospital, we found an additional five cases of cerebral infarction with nephrotic syndrome. Two of the patients were found to have nephrotic syndrome during admission for stroke. CONCLUSIONS: Hypercoagulability may be the major contributing factor of cerebral infarction in patients with nephrotic syndrome.

Acute Disease↗

PubMed1991

Percutaneous reposition of dislodged coils in the treatment of a vertebral arteriovenous fistula--with CT follow-up.

We report a case of vertebral arteriovenous fistula in which embolization was complicated by migration of two coils and a partially inflated balloon. In order to relieve compression to the spinal cord, the displaced balloon was punctured percutaneously. For both relieving compression to the spinal cord and obliterating the residual fistula, the dislodged coils in the partially thrombosed epidural venous sinus were removed percutaneously and placed in the fistula, and more coils were implanted in the fistula percutaneously through the needle. CT follow-up half a year later showed complete resolution of compression of the spinal cord and complete recovery from myelopathy was clinically apparent.

Adult↗

PubMed1991

Intravenous double-dose contrast computed tomography in the diagnosis of spinal arteriovenous malformations: report of four cases.

Spinal IV double-dose computed tomography (DCT) followed by reformation imagings was performed on 4 patients. Three cases received double-dose contrast injections, one case received a conventional single dose contrast material. 'Dots' enhancement on axial CT scanning and 'vasculature-like' hyperdense enhancement on sagittal and coronal reformation imagings were found in four cases of spinal arteriovenous malformation (AVM). Two were at the cervical region and two at the thoracic level. Typical serpentine filling defects were noted in the myelogram of three cases of spinal AVM. One patient suffered from acute onset of paraplegia (case 2), requiring that she received immediate surgical intervention after DCT scanning without myelography. Time for the whole procedure lasted approximately 20 minutes. In addition DCT followed by reformation imaging may be used as a noninvasive preliminary screening procedure for spinal AVMs.

Adult↗