Biomedical subjects

H Poptani

Publications and source records attributed to H Poptani.

23 records · Page 2Linked to original sources

PubMed1993

Magnetic resonance imaging and localized in vivo proton spectroscopy in patients with fulminant hepatic failure.

Magnetic resonance imaging (MRI) and in vivo proton spectroscopic changes in the brain in three patients with fulminant hepatic failure are described. MRI showed cerebral atrophy in two and changes somewhat similar to what have been described in chronic hepatic encephalopathy. MR spectroscopy showed low myoinositol with high glutamine in grade IV coma, which returned to normal as patient showed clinical recovery. We conclude that these techniques will be useful in understanding the complex pathophysiology of fulminant hepatic failure.

Adult↗

PubMed1992

Cine MR voiding cystourethrogram in adult normal males.

Cine voiding cystourethrogram was performed in 15 normal subjects using T1-weighted Turbo FLASH sequence. It showed the sequence of emptying of bladder, detrusor muscle contraction, opening of the sphincters, and various parts of urethra. It was found to be a good noninvasive test to study the dynamics of lower urinary tract without disturbing the state of the physiology.

Adult↗

PubMedDate not supplied

Non-invasive magnetic resonance thermometry using thulium-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate (TmDOTA(-)).

Non-invasive thermometry is pivotal to the future advances of regional hyperthermia as a cancer treatment modality. Current magnetic resonance (MR) thermometry methods suffer from poor thermal resolution due to relatively weak dependence of chemical shift of the (1)H water signal on temperature. This study evaluated the feasibility of using thulium-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate (TmDOTA(-)) for MR thermometry. TmDOTA(-) is non-toxic and the gadolinium complex of DOTA(4-) is widely used as a MR contrast agent. The results demonstrate that the temperature dependence of the TmDOTA(-) proton shifts are about two orders of magnitudes higher than the water proton and, thus, provide excellent accuracy and resolution. In addition, TmDOTA(-) proton shifts are insensitive to the paramagnetic complex concentration, pH, Ca(2+) or presence of plasma macromolecules and ions. Because hyperthermia is known to produce changes in tissue pH and other physiological parameters, these properties of TmDOTA(-) greatly simplify the procedures for using the lanthanide complex for MR thermometry. Application of TmDOTA(-) for measurement of temperature in a subcutaneously implanted human melanoma xenograft is demonstrated. Finally, the feasibility of imaging one of the (1)H resonances of the lanthanide complex is demonstrated in phantom experiments. Overall, TmDOTA(-) appears to be a promising probe for MR thermometry in vivo.

Animals↗

PubMedDate not supplied

Diffusion tensor imaging in amyotrophic lateral sclerosis: volumetric analysis of the corticospinal tract.

BACKGROUND AND PURPOSE: Diffusion tensor imaging (DTI) allows direct visualization and volumetric analysis of the corticospinal tract (CST). The purpose of this study was to determine whether color maps and fiber tracking derived from DTI data are valuable in detecting and quantifying CST degeneration in patients with amyotrophic lateral sclerosis (ALS). METHODS: Sixteen patients with ALS with clinical signs of upper motor neuron (UMN) involvement and 17 healthy subjects were studied with the use of DTI. Disease severity was determined by means of the ALS Functional Rating Scale-Revised (ALSFRS-R) and an UMN involvement score. DTI was acquired with a 12-direction, single-shot, spin-echo echo-planar sequence. The CST from the lower pons to the corona radiata at the level of the corpus callosum on 4 contiguous coronal sections was manually segmented by using color maps generated from the DTI data. The left and right CST volumes were measured separately and normalized to the total intracranial volume. Normalized CST volumes were compared between patients with ALS and healthy subjects. RESULTS: The CST volumes of patients with ALS were significantly reduced (P < .01, unpaired t test) compared with healthy subjects, in both affected and nonaffected hemispheres. No significant correlation was found between CST volumes and any of the clinical parameters, including disease duration, ALSFRS-R, or UMN involvement score. CONCLUSION: This study shows that volumetric analysis by using DTI-based color maps is valuable in detecting and monitoring structural degeneration of the CST. This will lead to objective and quantitative assessment of axonal degeneration in ALS.

Adult↗

PubMedDate not supplied

Monitoring thymidine kinase and ganciclovir-induced changes in rat malignant glioma in vivo by nuclear magnetic resonance imaging.

We have used high resolution magnetic resonance imaging to monitor malignant rat BT4C gliomas in vivo following herpes simplex virus thymidine kinase gene and ganciclovir (GCV) treatment. Twenty-six female BDIX rats were used for the study including four controls. Serial magnetic resonance imaging was performed every 72 hours to quantify tumor volume, transverse relaxation time (T2) ,and apparent diffusion constant (ADC) of water in the tumors and in the contralateral brain. GCV treatment was given twice a day, intraperitoneally, for 21 days. The gliomas exhibited low T2 and ADC values (before treatment), compared to normal brain, indicating the presence of high cell density tumors. Following GCV treatment, a regional increase in T2 and ADC was observed as early as day 4 of the treatment, even though the tumor volume was still increasing. These observations suggested evolution of local necroses which were confirmed by histology. In a group of five tumor bearing rats, retrovirus-producing packaging cell injections were given intratumorally to mimic clinically relevant gene therapy. In these cases, only small and short-lasting T2 and ADC elevations were found following GCV treatment without an effect on the overall tumor growth and outcome. Our results show that quantitative magnetic resonance imaging including T2 and ADC, is superior to robust volume measurements in predicting an early response to retrovirus-mediated gene therapy in vivo.

Animals↗