$262 Tuesday, November 8, 2005 Poster Abstracts

where S is the signal intensity, TE is the echo time, and 5" is the proton gyromagnetic ratio (1, 2). M F C maps are generated by fitting the signal intensities as a function of the pulse shifts on a pixel- by-pixel basis, to Eqn. [2]. The validity of tiffs equation for biological tissues has been confirmed both with Monte Carlo simulations (1) and suspensions of yeast cells containing a paramagnetic contrast agent (12). Methods: ASE images were acquired using a se~nented EPI sequence from six normal volunteers on a Siemens Allegro 3 Tesla scanner. Four echo times were used (TE -- 26,32,50,69 ms) with five refocusing pulse shifts (0.0, 3.0, 6.0, 9.0, and 12.0 ms) for each TE. Using a repetition time of 2000 ms, FOV of 230 mm, 10 averages and a matrix size of 128 x128, M F C data was acquired from 20 slices (1.8 m_m thick). Signal intensities were measured from brain regions including putamen (PUT), globus pallidus (GP), substantia uiagra (SN), thalanms (THL), caudate head (CHD), frontal white matter (FWM) and cortical gray matter (CGM). MFC maps were extracted as explained above. The transverse relaxation rate R.2 was calculated by fitting the signal intensifies (corresponding to the four TEs) as a function of TE. Single-shot diffusion-weighted EPI was also performed using the following parameters: TR 2000 ms, TE 88 ms, slice thickness 1.2 mm with 10 averages. SE images were obtained using three b values (300, 600 and 900 seconds/mm2), comprised of 128×96 pixels and covered an FOV of 230 nmt from which ADC maps were extracted. Results: A strong correlation (r - 0.975) was observed between MFC and established age-related iron concentrations (13), suggesting that MFC imaging is sensitive to iron-induced differences in brain-tissue susceptibility. It was observed that the regional variation in MFC values is higher than both A D C and T2 values. A typical MFC map acquired at an echo time of 50 ms showed that the most interesting structures are near the center of the image, associated with the globus pallidus, a region knovat for its high iron content. The MFC was found to decrease with increasing TE, reflecting the diffusion of water molecules through microscopic gradients.

0639 Brain MRI in elderly population - retrospective study

Semnic, R ~, Semnic, M ~, Kozic, D 1 , Ostojic, J 1, Ocic, G ~, Djilas Ivanovic, D 1, Popovic, S 1, Bogdanovic, D 1, Miucin Vukadinovic, I ~, Prvulovic, N ~. ~Institute Of Oncology; 2Institute of Neurology, Novi Sa& 3Institute of Neurology, Belgrade

Purpose: To evaluate brain pathology in elderly patients using Magnetic Resonance Imaging/MR angiography and to compare findings in two age groups: group A (range, 65-74 years) and group B (aged 75 and more). Methods: Retrospective study of 1805 brain MRI in period 1994-2002 was done. Routine M R I / M R A brain protocol was performed on 1.5 Tesla imager. Results: Group A in our study represents 0.08% (11602 patients) of all M R neurocases (118000 patients) and group B 0.01% only (1202 patients). After age of 72, number of examined patients was siguificantly lower. Pathological changes in brain parenchyma were revealed in 80"/o of cases. Ischemic changes dominated (48.5%) followed by vascular degenerative changes (18.5%) and intracranial hemorrhage (ICH) - 4.7%. Brain metastases and glial brain tumors were equally distributed (13.9"/o and 3.6%). Pathoguomonic diseases for eldery population as cortical dementias, diffuse brain atrophy, Parkinson disease and normotensive hydrocephalus were presented rarely (18 cases, 6%, 1% and 1% respectively). Comparison between two observed groups showed cummulation trend for ischemic encephalopathy (4% of all patients for group A and 8% for group B), common ischemic lesions (42%:50%), brain atrophy (5.6%:7%) and ICH (4.6%:6%). Number of cases with normal brain MRI was consecutively lower in group B.

Conclusion: Number of elderly patients who underwent MRI in period 1994-2002 is low which may reflects level of living standard in our country. IschemJc changes (including ICH) are dominant pathology in our population and brain atrophy is second most frequent. Pts with brain diseases typical for aging are uncommlon M R finding. Expectance of new cases with ischemJc changes is significantly high after the age of 75 and equally represented for newcomming patients with brain atrophy and ICH.

0640 Clinicoradiological correlation and response to treahnent in Acute Transeverse Myelitis

Sharma, CM l, Sharma, AK 1, Singh, R ~, Kankane, AK 1, Kumawat, BL 1. 1Department of neurology, SMS Medical College, Jaipur, India

Aim: Tiffs study was carried out to lffghlight dinico-radiological correlation in transverse myelitis and response to treatment. Material and Methods: Twenty five patients were diagnosed as transverse myelitis on the basis of criteria by Jeffery et al. Detailed neurological examination was carried out and all patients were subjected to 1.5 Tesla superconducting magnetic resonance imaging. Other relevant investigations were done to rule out other causes of non compressive myelopathy.Twenty patients were treated with intravenous methylpreduisolone at a dose of lgm/day and followed for one year. Results: The study included 15 females and 10 males (F:M::I.5:I). Mean age of onset was 40 (range 15-50). The presenting features were quadriparesis in 15 patients (60%), Paraparesis in 10 (40%). Bladder and bowel involvement was seen in 22 patients (88"/o) and definite sensory level in 18(72%).A11 the patients had acute onset of symptoms which peaked in 6.5(range 1-15) days.Cerebrospinal fluid was normal in all patients. High signal intensity on T2 weighted magnetic resonance imaging was seen in 23 (180"/o), 2 patients showed only cord expansion. Three patients showed hypointensity on T1. The lesion extended for a mean of 6 spinal segments (range 4-12 segments).The high signal intensity on mxial T2 weighted images was centrally located in all patients and occupied more than 2/3 "a of the cross sectional area of the cord in 21 (1847,'8) patients. 20 patients showed central dot sign. Conclusion: Prognosis is poor in the patients having long hyperintense signals and necrosis and there is a beneficial effect of methylpredni- solone.

0641 Brain responses to Hypoxia in the intrauterine growth restricted piglet uleasuxed by magnetic resonance spectroscopy and diflilsion weighted hnaging

Sinclair, K 1, Rose, S 3, Cowin, G 3, Burke, C 2, Colditz, p2. ~Brain Research Institute, Melbourne, Australia; 2Perinatal Research Centre; 3Centre for Magnetic Resonance, University of Queensland, Australia

Background: Intrauterine growth restriction (IUGR) is associated with chronic fetal hypoxia and an increased incidence of neurodevelop- mental disability. The pathophysiology linking IUGR and brain injury is not well understood. Hypothesis: Newborn I U G R piglets, compared to appropriately grown (AGA) littermates, have a different acute cellular and metabolic response to hypoxia. Methods: Eight pairs o f piglet littermates < 24 h age were selected by weight, ( IUGR < 5th percentile, AGA > 25th percentile). Piglets were anaesthetised, ventilated, physiological parameters monitored and normothermia maintained. Proton magnetic resonance spectroscopy (~H-MRS) was performed in a aT magnet to measure brain lactate, and diffusion weighted imaging (DWI) performed to calculate the apparent diffusion coefficient (ADC), wlffch reflects cellular edema associated with hypoxic primary energy failure. Measurements were