Biomedical subjects

Zarir P Khademian

Publications and source records attributed to Zarir P Khademian.

3 recordsLinked to original sources

PubMed2005

Diffusion-weighted MR imaging of early methotrexate-related neurotoxicity in children.

BACKGROUND AND PURPOSE: Methotrexate is a major cause of treatment-related acute neurotoxicity in children with hematologic malignancies. The purpose of this study was to investigate whether diffusion-weighted MR imaging (DWI) detects acute methotrexate white matter neurotoxicity in this patient population. METHODS: Six children-three female and three male-with hematologic malignancies were studied at time of onset of neurologic dysfunction during the delayed intensification or consolidation phase of therapy, when intensive intrathecal methotrexate is given. MR imaging including DWI was performed on 1.5 T MR scanners. RESULTS: DWI demonstrated abnormal restriction of motion of water in the centrum semiovale in all six patients. This finding correlated to the acute onset of hemiparesis or aphasia. Fluid-attenuated inversion recovery imaging was not positive at this time, but it was positive in all five patients in whom follow-up imaging was performed. CONCLUSION: Early detection of methotrexate white matter injury by DWI has the potential to alert the oncologist to this event and provide a technique by which treatment of neurotoxicity can be monitored.

Adolescent↗

PubMed2004

Choroid plexus carcinomas in children: MRI features and patient outcomes.

Choroid plexus carcinomas (CPC) are rare malignant intracranial neoplasms usually occurring in young children. The objectives of this study were to characterize the preoperative MRI features of CPC, determine the frequency of disseminated disease in the CNS at diagnosis, and assess patient outcomes. The preoperative cranial MR images of 11 patients with CPC were retrospectively reviewed for lesion location, lesion size, un-enhanced and enhanced MRI signal characteristics, and presence of disseminated intracranial tumor. Postoperative cranial and spinal MRI images were reviewed for residual, recurrent, and/or disseminated tumor. The study group included six male and five female patients ranging in age from 5 months to 5.3 years (median= 1.8 years). CPC were located in the lateral (n = 8), fourth (n = 1), and third (n = 1) ventricles, and foramen of Luschka (n = 1). Mean tumor size was 5.2 cm x 4.9 cm x 5.0 cm. On short-TR images, CPC had heterogeneous, predominantly intermediate signal with foci of high signal in 45% of lesions from areas of hemorrhage. On long-TR/long-TE images, solid portions of CPC typically had heterogeneous, intermediate-to-slightly-high signal. Small zones of low signal on long-TR/long-TE images were seen in 55% of the lesions secondary to areas of hemorrhage and/or calcifications. Tubular flow voids representing blood vessels were seen in 55% of the lesions. Zones of high signal comparable to CSF were seen in 64% of CPC secondary to cystic/necrotic zones. All CPC showed prominent contrast enhancement. Irregular enhancing margins suggesting subependymal invasion were seen in 73% of the lesions. Findings consistent with edema in the brain adjacent to the enhancing lesions were seen in 73% of CPC. CPC caused hydrocephalus in 82% of patients at diagnosis. Two patients died from hemorrhagic complications from surgical biopsies. Disseminated tumor in the leptomeninges was present in 45% of patients at diagnosis and was associated with a poor prognosis. The 1-year and 5-year survival probabilities were 55% and 45%, respectively. In conclusion, MRI features commonly associated with CPC include large intraventricular lesions with irregular enhancing margins; heterogeneous signal on long TR/long TE images and short-TR images; edema in adjacent brain; hydrocephalus; and presence of disseminated tumor. MRI evidence of disseminated tumor at diagnosis is associated with a poor prognosis.

Carcinoma↗

PubMed2002

Dose reduction fluoroscopy in pediatrics.

BACKGROUND: It is essential that we find ways to reduce radiation exposure to children and maintain image quality. OBJECTIVES: We compared radiation dose, image quality, and spatial resolution when continuous and pulse fluoroscopy with a full and half dose are applied to a phantom. The film-screen technique was compared to fluoroscopy with the digitized spot technique (fluoro grab image) in procedures such as voiding cystourethrogram (VCUG). MATERIALS AND METHODS: Using a 15.1-cm Plexiglas phantom, we obtained dosimetry in milligrays (mGy), spatial resolution in number of line pairs per millimeter (lp/mm), and threshold contrast resolution in number of visible holes. To measure total radiation dose, we calculated the average elapsed fluoroscopy time for VCUG to be approximately 3 min and estimated the average number of exposures as 10. Dosimetry was obtained for full dose and half dose continuous, for 15 pulses per second (pps), 7.5 pps, and 3.75 pps. These were also calculated with normal, magnification 1, and magnification 2 factors. RESULTS: Results of the two most relevant parameters are shown: continuous full-dose fluoroscopy, 3 min, 10 photo spots, total dose of 28.7 mGy with 2 lp/mm of resolution and a threshold contrast of 2.2%, versus 3.75 pps half-dose fluoroscopy, 3 min, grab images, total dose of 3.7 mGy with 1.9 lp/mm of resolution and a threshold contrast of 2.3%. CONCLUSION: With minimal loss of resolution there is significant dose reduction (87%) when using 3.75 pps with digitized imaging.

Fluoroscopy↗