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Biomedical subjects

M Chui

Publications and source records attributed to M Chui.

At least 19 recordsLinked to original sources
PubMed2001

Intracarotid abciximab injection to abort impending ischemic stroke during carotid angioplasty.

BACKGROUND: Abciximab, a platelet glycoprotein IIb/IIIa receptor antagonist, prevents ischemic complications during percutaneous transluminal coronary angioplasty and was recently shown to open occluded vessels in patients with acute myocardial infarction when used alone or in combination with other thrombolytic agents. In an animal model of arterial thrombosis, abciximab was found to be safe and effective for the prevention of carotid artery thrombosis. However, the safety and efficacy of abciximab in the treatment of acute ischemic cerebrovascular events is unknown at present. CASE DESCRIPTION: We describe 3 patients who experienced ischemic cerebrovascular events with symptoms involving the middle cerebral artery territory while undergoing percutaneous angioplasty and stenting to their internal carotid arteries. Abciximab was administered to each patient within 10 min of symptom onset as a bolus (0.25 mg/kg) into the ipsilateral common carotid artery followed by continuous intravenous infusion (9 microg/min) for 12 h. All patients' symptoms resolved completely (by 25 min, 40 min and 5 h, respectively) with no further neurological complications. CONCLUSIONS: Our preliminary observation suggests that abciximab may improve neurological outcome following middle cerebral artery ischemic events associated with carotid angioplasty and stenting. Large prospective studies are warranted to establish the safety and efficacy of abciximab in acute ischemic stroke, either as a primary treatment modality or an adjunct to carotid angioplasty and stenting.

Abciximab↗
PubMed2001

Multivessel spasm during coronary and peripheral angiography.

The development of an infected aortic (pseudo)aneurysm which occurred after placement of a coronary artery stent is reported. Complications of cardiac catheterization and coronary artery stent placement are infrequent and this complication has not yet been reported in the literature.

Aged↗
PubMed1998

Integrated and interactive position tracking and imaging of interventional tools and internal devices using small fiducial receiver coils.

A method is described of tracking the position of a rigid device within an MR scanner and imaging with the image slice position determined by the current position of the device, such that the manipulation of the device can be achieved in a robust, interactive manner. The device can be either external or internal to the patient. The position tracking is performed by means of two or three small MR receiver coils attached to individual receiver channels. Each coil contains a small sample that acts as a fiducial (MR-visible marker point). The imaging is performed by any suitable receiver coil attached to a further receive channel. This method has a large number of applications, both in the field of MR-guided procedures and in MR imaging using endocavitary coils. In particular, two devices are described, the first being a device for MR-guided biopsies and the second being one for dynamic endorectal imaging of the anal sphincter.

Anal Canal↗
PubMed1995

Endoscopic laser ablation of the prostate: MR appearances during and after treatment and their relation to clinical outcome.

OBJECTIVE: Endoscopic laser ablation is a new treatment for benign prostatic hypertrophy. The objectives of this study were to determine the appearances of the prostate on MR images obtained during, 1 week after, and 3 months after this procedure and to determine if a correlation exists between the MR findings and the clinical outcome. Such appearances could then be used to guide the application of laser energy during the procedure in order to optimize the clinical result. SUBJECTS AND METHODS: Eight consecutive men 58-74 years old with symptoms of bladder outflow obstruction caused by benign prostatic hypertrophy underwent endoscopic laser ablation of the prostate under spinal or epidural anaesthesia. Imaging was done on a 0.5-T Picker Asset system with an endorectal receiver coil and conventional T1-weighted spin-echo, T2-weighted spin-echo, and gradient-recalled-echo sequences. T1-weighted magnetization transfer images were obtained in three patients. Images were obtained preoperatively, after ablation of the left-sided quadrants, immediately after completion of the procedure, and 1 week and 3 months later. Preoperative and 3-month postoperative symptom scores, peak urine flow rates, and bladder residual volumes were studied. Images were visually assessed for signal-intensity changes and the presence of cavitation by three radiologists in conference. The results were quantitatively analyzed by measuring prostatic volumes on the gradient-recalled-echo images and by measuring the width and area of regions of signal-intensity change on the T2-weighted images. RESULTS: MR images made immediately after treatment showed an increase in the volume of the prostate (mean, 34%) and a poorly defined, low-signal-intensity region around the urethra on the T2-weighted images in six patients. This probably represented coagulative necrosis. The prostate was smaller on MR images made 1 week after treatment, and after 3 months the prostate returned to its preoperative size. After 1 week, the low-signal-intensity periurethral region on the T2-weighted images was less obvious, and at 3 months it was replaced in four patients by a well-demarcated low-signal-intensity ring on the T2-weighted and gradient-recalled-echo images. No evidence of cavity formation in the prostate was seen on MR images in any patient. Symptom scores and peak urinary flow rates improved after 3 months, with a significant difference between the mean increase in symptom scores in the patients with and without the periurethral changes seen immediately after treatment. However, we found no significant difference between the mean increase in peak urinary flow rates in the patients with and without periurethral changes seen either immediately or at 3 months after treatment. No statistically significant correlation was found between the amount of prostatic swelling and the improvement in symptom scores or peak urine flow rates. CONCLUSION: In patients who have had laser prostatectomy, MR imaging shows significant immediate glandular swelling, which may account for the delayed improvement in symptoms reported with this technique. The presence of the periurethral changes immediately after treatment was correlated with a subsequent improvement in symptom scores. After 3 months, no cavity could be seen in the prostate. This may account for the poorer long-term clinical outcome reported with endoscopic laser ablation of the prostate compared with transurethral prostatectomy.

Aged↗
PubMed1993

Dural cavernous hemangioma: an under-recognized lesion mimicking meningioma.

We report a 77-year-old woman who presented with partial seizures and was found to have an enhancing dural-based parietal convexity mass. The lesion enlarged on serial examination by computed tomography (CT) over a one year period. The clinical features and radiologic appearance were compatible with a pre-operative diagnosis of meningioma; however, pathologic findings were typical of a dural cavernous hemangioma. Accumulating evidence suggests that these lesions are an uncommon but distinct type of vascular malformation most often arising from the cavernous sinus, tentorium, or cerebello-pontine angle. With CT, magnetic resonance imaging and angiography, these lesions can closely resemble meningioma in terms of signal characteristics, enhancement pattern, and location. This is of importance both in the practical management of meningiomas where the diagnosis is often based on radiologic studies alone, and in clinical trials where incorrect entry diagnosis should be avoided.

Aged↗
PubMed1989

Fibromatosis of the brachial plexus and shoulder girdle.

Fibromatosis is a term which encompasses a group of non-metastasizing fibroblastic tumors which tend to invade locally and recur after attempted excision. Although it frequently involves the shoulder region and brachial plexus, it has seldom been reported in the radiological literature. Five patients with disease involving this location are described. On computed tomograms the tumors appear as isodense irregular masses infiltrating adjacent muscles, especially the serratus anterior and the scalene muscles, without cystic or necrotic changes. The appearances are not specific but the diagnosis should be considered in such brachial plexus lesions. Computed tomography plays an important part in the preoperative management and follow-up of this entity.

Adult↗
PubMed1987

Fenestration of the supraclinoid internal carotid artery.

A twenty-eight year old woman presenting with subarachnoid hemorrhage was found at angiography to have a left anterior cerebral-anterior communicating artery aneurysm. Also identified was a fenestration of the right supraclinoid internal carotid artery with an associated accessory middle cerebral artery. This appears to be the second reported case of fenestration of the intracranial internal carotid artery. Fenestrations of cerebral vessels and their possible embryologic origins are briefly reviewed.

Adult↗
PubMed1987

Giant-cell tumor of the middle cranial fossa. Case report.

The authors report the case of a 23-year-old man with a giant-cell tumor of the right middle cranial fossa floor. His presentation and management are described, and some aspects of this rare neoplasm of the skull base are reviewed. The role of adjuvant radiotherapy is discussed.

Adult↗
PubMed1985

High resolution CT of Meckel's cave.

High resolution CT of the parasellar region was carried out in 50 patients studied for suspected pituitary microadenoma, but who showed normal pituitary gland or microadenoma on CT. This control group of patients all showed an ellipsoid low-density area in the posterior parasellar region. Knowledge of the gross anatomy and correlation with metrizamide cisternography suggest that the low density region represents Meckel's cave, rather than just the trigeminal ganglion alone. Though there is considerable variation in the size of Meckel's cave in different patients as well as the two sides of the same patient, the rather constant ellipsoid configuration of the cave in normal subjects will aid in diagnosing small pathological lesions, thereby obviating more invasive cisternography via the transovale or lumbar route. Patients with "idiopathic" tic douloureux do not show a Meckel's cave significantly different from the control group.

Adult↗
PubMed1985

Preoperative Gelfoam embolization of supratentorial meningiomas.

Intracranial meningiomas are often highly vascular and a successful outcome depends upon surgical resection. Preoperative embolization of supratentorial meningiomas, which have a major blood supply from the external carotid artery, has been advocated to reduce intraoperative bleeding and thus facilitate surgical extirpation. The authors carried out transfemoral, Gelfoam embolization preoperatively in eight patients with supratentorial meningiomas. In seven of the cases, post-embolization, contrast-enhanced, computerized tomography was carried out. Areas of low-density tumour necrosis were identified in five. In three of the eight patients, post-embolization angiography demonstrated elimination of the tumour blush and in the other five, the blush was reduced in intensity. Histologic evidence of tumour embolization was identified in each case to a varying degree. Preoperative embolization resulted in an identifiable radiologic change in the majority of these tumours, but the authors could not determine, in this small series, whether intraoperative bleeding was reduced.

Adult↗
PubMed1982

Computed tomography of sellar and parasellar lesions: indications for metrizamide cisternography.

Sixty-four patients with intrasellar and suprasellar lesions on conventional computed tomography (CT) have been studied retrospectively to determine the indications for metrizamide CT cisternography (MCTC). Enhancing or calcified lesions, like a craniopharyngioma, pituitary adenoma, meningioma or aneurysm are adequately evaluated by conventional CT and MCTC is usually not needed. Determination of the exact suprasellar extent of an enhancing pituitary adenoma is best accomplished with coronal thin-section conventional CT alone. However, for isodense or hypodense suprasellar and intrasellar lesions, MCTC is indicated if conventional CT does not define their extent accurately. Differentiation of an empty sella from the occasional entirely lucent pituitary adenoma or other low density intrasellar lesions remains difficult by conventional CT at times, especially when the infundibulum is not identified. Then MCTC will also be indicated.

Adenoma↗
PubMedDate not supplied

Test method for MR image slice profile.

This article describes a method of constructing the slice profile of a magnetic resonance image, using an acrylic ramp in doped water as a phantom. The method can also be used to define the absolute slice position and is equally applicable to single and multiple slices.

Image Enhancement↗
PubMedDate not supplied

Epileptic seizures attributed to cerebral hyperperfusion after percutaneous transluminal angioplasty and stenting of the internal carotid artery.

Cerebral hyperperfusion syndrome as a complication of carotid endarterectomy (CEA) has been widely reported in the surgical literature. It may occur within hours to 3 weeks after CEA and is characterized by symptoms ranging from headaches, fits, confusion, focal neurological signs to intracerebral hemorrhage. Although percutaneous transluminal angioplasty (PTA) and stenting are increasingly performed as an alternative to CEA in the treatment of carotid artery stenosis, few cases of cerebral hyperperfusion injury following carotid stenting have been reported. We describe 2 cases of cerebral hyperperfusion syndrome following PTA and stenting for high-grade internal carotid artery (ICA) stenosis. Both cases involved a lesion of 95% in severity. The first case was a 73-year-old man who developed generalized convulsion 7 h following stenting to the left ICA. The second case was an 80-year-old woman who developed recurrent right periorbital headache and confusion 16 h after stenting to the right ICA, followed by left upper limb seizure 14 days later. Both patients fully recovered without any intracerebral hemorrhage or infarction. To our knowledge, this is the first report of cerebral hyperperfusion injury after carotid stenting without associated intracranial hemorrhage and with full recovery. In the patient with neurological symptoms following carotid stenting, it is important to consider cerebral hyperperfusion syndrome as a differential diagnosis to embolic or hemorrhagic stroke since early recognition and meticulous control of blood pressure may prevent progression to cerebral hemorrhage and death.

Aged↗