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Biomedical subjects

L Talagala

Publications and source records attributed to L Talagala.

5 recordsLinked to original sources
PubMed1997

Magnetic resonance imaging and spectroscopy in offspring at risk for schizophrenia: preliminary studies.

1. Studies of first-degree relatives of persons with schizophrenia provide an opportunity to characterize risk factors for the development of this illness. In this report the authors will provide preliminary data from an ongoing study of neurobiological alterations in the offspring of schizophrenia patients. 2. A series of offspring of schizophrenic patients (OS) were compared with age and sex matched healthy controls (HC) without psychiatric history in first degree relatives on psychiatric, volumetric Magnetic Resonance Imaging (MRI) of whole brain and proton Magnetic Resonance Spectroscopy (1H MRS) evaluations of the ventral prefrontal cortex. 3. Compared with HC group, high risk subjects had reduced left amygdala volume, enlarged third ventricular volume, and smaller overall brain volume. 4. 1H MRS studies showed a trend for decreased NAA/choline ratios in the anterior cingulate region in the OS group as compared to HC subjects. 5. Follow-up studies of these subjects are needed to confirm the predictive value of these measures for future emergence of schizophrenia in subjects at risk for this illness.

Adolescent↗
PubMed1994

Stereotactic magnetic resonance angiography for targeting in arteriovenous malformation radiosurgery.

Because conventional stereotactic angiography provides only two-dimensional information for dose planning, we studied the accuracy and usefulness of stereotactic magnetic resonance angiography (sMRA) for arteriovenous malformation (AVM) radiosurgery in 28 consecutive patients. We hypothesized that the multidimensional data set provided by sMRA and the opportunity to image both blood vessels and brain parenchyma would improve the accuracy of AVM irradiation and improve the safety of radiosurgery. Twenty-eight patients with AVMs in different brain locations and with a variety of AVM sizes (range, 15-31 mm mean diameter) had sMRA followed by stereotactic angiography. The sMRA images only were used to construct an initial radiosurgical plan. This plan was then used to outline the AVM volume defined by conventional angiography. In 24 patients, sMRA information equaled that of conventional angiography. In 3 patients, sMRA was better, because conventional angiography overestimated the size of the AVM nidus. In one patient, the conventional angiogram showed a second separate nidus (10-mm diameter) that was not as well defined on MRA. There were no complications with any procedure. In 16 patients (57%), sMRA provided critical information on AVM shape that was not provided by conventional angiography alone. Stereotactic MRA is a fast, noninvasive, inexpensive, multidimensional imaging method for AVM radiosurgery that provides information on vascular and parenchymal brain anatomy important for optimal dose planning. We believe that it can be used with confidence as the sole imaging method for medium-size, compact-nidus AVMs.

Adolescent↗
PubMed1993

Magnetic resonance imaging can cause focal heating in a nonuniform phantom.

To test if the radiofrequency fields of a magnetic resonance imager could cause focal heating, two cylindrical phantoms were made from a mixture of agar and saline. The first phantom was uniform; the second was nonuniform in that a narrow bridge of agar was produced. Both phantoms were exposed to high levels of radiofrequency power (140 W) at 63 MHz and the temperature rises were measured. In the uniform phantom, the temperature increased as the radius increased. In the bridge phantom, the narrow bridge heated three times greater than at the opposite uniform periphery, and over five times the average of the uniform phantom. This experiment demonstrates that the radiofrequency fields of magnetic resonance imagers can cause focal heating if the exposed object is nonuniform. Since nonuniformity is present in the human body, as the radiofrequency power of magnetic resonance imaging techniques increases, focal heating in patients is a concern.

Hot Temperature↗
PubMed1990

Safety considerations in MR imaging.

The authors identify eight areas of potential safety concern during clinical magnetic resonance (MR) imaging. These include (a) biologic effects of the static magnetic field; (b) ferromagnetic attractive "projectile" effects of the static magnetic field; (c) potential effects of the relatively slowly time-varying magnetic field gradients; (d) effects of the rapidly varying radio-frequency (RF) magnetic fields, including RF power deposition concerns; (e) auditory considerations from noise caused by the rapidly pulsed magnetic field gradients; (f) safety considerations concerning superconductive systems, including quenches, use of cryogens, and cryogen storage and handling; (g) psychological effects, such as claustrophobia and anxiety induced because of the examination; and (h) possible effects of the intravenous use of the MR contrast agent gadopentetate dimeglumine. The concerns in each of these categories are elaborated upon, and the available data are presented to clarify their status.

Accident Prevention↗