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Biomedical subjects

J Ahmadi

Publications and source records attributed to J Ahmadi.

At least 19 recordsLinked to original sources
PubMed1992

Cystic fluid in craniopharyngiomas: MR imaging and quantitative analysis.

A prospective study of cystic fluid in craniopharyngiomas in 10 patients was performed to correlate signal intensity on T1-weighted magnetic resonance (MR) images and biochemical analysis. Within 2 days before surgery, each patient underwent MR imaging before and after administration of gadopentetate dimeglumine. Five patients had cystic fluid lower in signal intensity than white matter, with protein levels less than 9,000 mg/dL (90.00 g/L) and no free methemoglobin. One of the five patients had the highest triglyceride concentration (84 mg/dL [0.95 mmol/L]) of all 10 patients; another of these five had the highest cholesterol concentration of all (270 mg/dL [6.98 mmol/L]). It is concluded that the increased signal intensity of cystic fluid in craniopharyngiomas on T1-weighted MR images can be caused by a protein concentration greater than or equal to 9,000 mg/dL (90.00 g/L), the presence of free methemoglobin, or both. In the ranges of concentrations measured in this study, cholesterol and triglyceride did not increase signal intensity.

Adolescent↗
PubMed1992

Magnetic resonance imaging of meningiomas.

MRI with gadolinium enhancement is the imaging modality of choice in the diagnosis of meningiomas. Various MRI features are described. MRI signal intensity characteristics in meningiomas contain information that could be correlated with the histopathology of the tumor. Hyperintensity on T2-weighted images indicates soft tumor consistency and microhypervascularity and is more often seen in aggressive, angioblastic, or meningothelial meningiomas. MRI is useful in demonstrating dural sinus involvement. Meningiomas in unusual locations and their mimics are also presented.

Brain↗
PubMed1991

Treatment of unresectable meningiomas with the antiprogesterone agent mifepristone.

The possibility that meningioma growth may be related to female sex hormone levels is suggested by several lines of evidence. Meningiomas are twice as common in women as in men, have been observed to wax and wane with pregnancy, and are positively associated with breast cancer. A physiological explanation for these phenomena is provided by the finding of steroid hormone receptors in meningiomas. However, unlike breast cancer, meningiomas are much more commonly positive for progesterone receptors than for estrogen receptors. The authors initiated a study on long-term oral therapy of unresectable meningiomas with the antiprogesterone mifepristone (RU486). Fourteen patients received mifepristone in daily doses of 200 mg for periods ranging from 2 to 31+ months (greater than or equal to 6 months in 12 patients). Five patients have shown signs of objective response (reduced tumor measurement on computerized tomography scan or magnetic resonance image, or improved visual field examination). Three have also experienced subjective improvement (improved extraocular muscle function or relief from headache). The side effects of long-term mifepristone therapy have been mild. Fatigue was noted in 11 of the 14 patients. Other side effects included hot flashes in five patients, gynecomastia in three, partial alopecia in two, and cessation of menses in two. Long-term therapy with mifepristone is a new therapeutic option that may have efficacy in cases of unresectable benign meningioma.

Adult↗
PubMed1989

Noninvasive monitoring of drug biodistribution and metabolism: studies with intraarterial Pt-195m-cisplatin in humans.

We have performed a comparative evaluation of systemic (i.v.) and intraarterial (i.a.) cisplatin by using a trace dose of the radiolabeled form of this drug [( 195mPt]cisplatin) to monitor the drug's biodistribution by dynamic scintigraphic imaging. We have analyzed the drug's metabolism using a compartmental model both following i.a. and i.v. administration in patients with gliomas. Significantly larger amounts of radioactivity (up to 10 times higher than in the uninvolved brain) were measured in tumors following i.a. administration, whereas the differential localization following i.v. drug administration was, at best, only twofold that of the uninvolved brain. On the other hand, no significant differences could be detected in the pharmacokinetics of either free cisplatin or platinated proteins in blood. The washout slope in tumors following i.a. administration may be an indicator of the higher local concentration of free cisplatin; no such washout could be observed in tumors following i.v. administration. The present noninvasive methods may help document the amount and the rate of (active) drug deposition at the desired target site. They may also assist in monitoring, prospectively and/or, on line, the probable effect of chemotherapy in an individual patient. In turn it may lead to novel methods for optimizing chemotherapeutic effectiveness at specific tumor-bearing sites and in defined treatment protocols.

Cisplatin↗
PubMed1989

Head trauma.

Computed tomography is currently the modality of choice in imaging acutely traumatized patients. This is based upon CT's documented ability to detect surgically significant lesions. Furthermore, the use of MRI is limited by a lack of bone detail, the degradation of MR images in frequently uncooperative patients, and a limited supply of nonferromagnetic monitoring equipments. CT and MRI are largely equivalent in their ability to diagnose epidural hematoma, but CT is readily available and quick. MRI provides information in addition to that obtained by CT in many instances, such as subacute and chronic subdural hematomas, contusions, and intracerebral hematomas.

Brain Injuries↗
PubMed1987

Short-latency somatosensory evoked potentials correlate with the severity of the neurological deficit and sensory abnormalities following cerebral ischemia.

Short-latency somatosensory evoked potentials (SSEPs) were studied in 49 patients who had suffered hemispheric or thalamic ischemia, including 6 patients with transient ischemic attacks (TIAs) and 3 patients with reversible ischemic neurological deficits (RINDs). SSEPs were abnormal in 30 patients (61%). SSEP abnormalities correlated with the presence of sensory deficit and the degree of neurological deficit. SSEPs were normal following TIA but were abnormal in 2 of 3 patients with RINDs. SSEPs were abnormal in some patients without sensory deficits suggesting that sensory pathways may be affected when clinically inapparent.

Adult↗
PubMed1987

Variability in arteriographic assessment of the carotid bifurcation.

We evaluated interobserver and intraobserver variability in the arteriographic assessment of the carotid bifurcation. Two neuroradiologists evaluated area stenosis and lumen surface morphology for 60 biplane carotid arteriograms in two reading sessions. Absolute interobserver differences for area stenosis averaged 8.8%, and interobserver differences were statistically significant for arteries of at least 50% stenosis. Analysis of observations for lumen surface morphology revealed statistically significant interobserver differences, averaging 29.5% disagreement. Intraobserver differences were not statistically significant. Observer variability for arteriography should be considered in the process of evaluating patients for carotid endarterectomy.

Carotid Arteries↗
PubMed1986

Intracranial arterial aneurysms in childhood: more recent considerations.

Nineteen children with congenital, mycotic, traumatic and tumoral arterial aneurysms were studied neuroradiologically. The important role of computed tomography (CT) was shown in two traumatic aneurysm cases where bleeding was clinically inapparent. Among the unique cases described was a boy with a pituitary tumor in whom an aneurysm was discovered incidentally; coexistence of these lesions in childhood has not been documented previously. Nor has a tumoral aneurysm been mentioned (the case reported had a surrounding primary anaplastic sarcoma). Rare cases included a cavernous carotid mycotic aneurysm and infants with hemorrhage from congenital distal middle cerebral artery aneurysms. Marked cellular responses within the aneurysm walls, believed to be a reaction to hemorrhage, were noted in both infants.

Adolescent↗
PubMed1986

Cavernous sinus invasion by pituitary adenomas.

One hundred ninety-eight surgically explored pituitary adenomas were evaluated preoperatively by high-resolution computed tomography (CT). At surgery, evidence of direct cavernous sinus invasion was demonstrated in 19. CT findings in these cases included cavernous sinus expansion (17 patients) and visible encasement of the internal carotid artery (14 patients). The invasive tumor often enhanced to a lesser degree than the cavernous sinuses and ipsilateral internal carotid artery. Intracavernous cranial nerve compression, obliteration, or displacement (14 patients), invasion of the lateral wall of the cavernous sinus (seven patients), and diffuse bone destruction (seven cases) were other findings. Magnetic resonance imaging in three patients provided excellent demonstration of intracavernous internal carotid artery encasement, but displacement and obliteration of intracavernous cranial nerves was not shown as well as it was with CT. Histologically, only three patients showed anaplastic features and only one of them had distant metastases. There was no correlation between histologic features, hormone assays, and invasiveness. This experience indicates any type of pituitary adenoma, regardless of its endocrinologic activity, can invade the cavernous sinus. Cavernous sinus involvement makes complete surgical removal difficult. Preoperative recognition of invasive behavior of these tumors has prognostic value and aids in designing appropriate management. CT is the most useful technique generally available for evaluation and follow-up.

Adenoma↗
PubMed1986

Penetrating vascular injuries of the face and neck: clinical and angiographic correlation.

A retrospective review was made of 139 clinically stable patients who had sustained penetrating trauma to the face and neck. The study was done to learn more about the indications for angiography and the impact of angiography upon patient management. Some relationship between the physical examination and the angiographic findings was found. In the presence of any one of four physical signs or symptoms (absent pulse, bruit, hematoma, or alteration of neurologic status) there was a 30% incidence of vascular injury. However, it is unlikely that a clinically significant traumatic vascular lesion will be missed if angiography is not obtained when these clinical signs and symptoms are not present. In the group of 78 patients who presented with only a wound penetrating the platysma and no other findings or symptoms, just two had vascular injuries on angiograms; one of these lesions was minor and the other did not affect the patient's management. There was a substantially higher rate (50%) of vascular injury in patients with trauma cephalad to the angle of the mandible compared with 11% of patients who had neck trauma. Gunshot wounds were associated with vascular damage more frequently than were stab wounds.

Angiography↗
PubMed1985

Computed tomography in the diagnosis of intracranial neoplasms in children.

The authors discuss their original observations using computed tomography (CT) in the diagnosis of posterior fossa neoplasms in children. The subject of CT diagnosis of childhood supratentorial tumors is also reviewed. However, despite the documented value of CT, the authors believe that magnetic resonance imaging (MRI) will eventually offer certain advantages that will make MRI the primary imaging modality for intracranial neoplasms in children.

Astrocytoma↗
PubMed1985

Arteriography of the carotid bifurcation: oblique projections.

Atherosclerotic plaques may not be demonstrated adequately by standard anteroposterior (AP)-lateral projections of carotid arteriography. We evaluated selective carotid arteriography in oblique projections for 60 individual carotid arteries. Two neuroradiologists evaluated arteriograms in four separate sessions devoted to AP-lateral views alone and in combination with oblique projections. The lumen surface was characterized as "smooth," "irregular," or "ulcerated." When oblique projections were added to AP-lateral views, there was a significant shift of radiologic diagnosis from smooth to irregular or ulcerated. Addition of oblique projections to standard AP-lateral views increases the radiographic diagnosis of carotid artery lesions that may be the source of emboli.

Angiography↗
PubMed1985

Thoracic spinal angiomyolipoma: case report and literature review.

A rare case of thoracic spinal angiomyolipoma presenting with evidence of vertebral body infiltration and concurrent epidural spinal cord compression is described. Clinicopathological correlates, aspects of radiological diagnosis, considerations for surgical management, and histopathological features denoting possible unique attributes of biological behavior for this entity are discussed in conjunction with a review of the previous literature on angiolipomas in general.

Adult↗
PubMed1985

Evaluation of cerebrospinal fluid rhinorrhea by metrizamide computed tomographic cisternography.

Seven interesting and instructive cases of cerebrospinal fluid rhinorrhea evaluated by metrizamide computed tomographic cisternography are presented. The rhinorrhea was spontaneous in three patients and was related to previous head trauma or surgical procedures in four patients. The anatomical site and the extent of the fistula were demonstrated precisely by directly showing metrizamide passing through the bony defect. A combination of bone dehiscence and metrizamide within the adjacent paranasal sinuses or the nasal cavity is also useful in localization. Distortion of the interhemispheric fissure, sylvian fissure, or basal sulci indicates the probability of brain herniation through the defect.

Adolescent↗
PubMed1978

A new device for myelography.

A new device based on the principle of the concentric system has been constructed for myelography and certain other procedures. It consists of biplane tube-image amplifier systems with 105-mm cameras in both planes. The system gives superior visualization of water-soluble media, particularly when tomography is used. The radiation dose to the patient is low.

Humans↗
PubMedDate not supplied

Evidence for transventricular absorption in the hydrocephalic dog.

Hydrocephalus was induced in 10 mongrel dogs by injection of a silastic mixture into the basal cisterns. The posterior part of the left lateral ventricle was isolated from the remainder of the ventricular system by introducing Pantopaque into both lateral ventricles and the third ventricle with the animals in prone positions. Labeled albumin injected into the posterior part of the left lateral ventricle was shown to enter the blood stream before it was shown in the fourth ventricle or vallecula. This provides qualitative evidence of transventricular absorption.

Absorption↗