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Biomedical subjects

P Prasad

Publications and source records attributed to P Prasad.

At least 19 recordsLinked to original sources
PubMed1996

Blunt trauma abdomen: a study of 63 cases.

63 cases of blunt abdominal trauma were studied. It was more common in males and in the age group 21-30 years. Majority of the injuries were due to automobile accidents. Commonly presenting feature was pain abdomen and vomiting. Abdominal paracentesis revealed haemoperitoneum in 40 cases which was subsequently confirmed on laparotomy in all the cases. 40 cases had no visible external injury but subsequent laparotomy revealed internal visceral injury in 29 cases. Exploratory laparotomy was carried out in 43 cases, remaining were treated conservatively. Liver was found to be the commonest organ injured. Post operative complications developed in 5 cases and deaths occurred in 7 cases mainly due to associated extra-abdominal injuries, poor pre-operative general condition, delayed diagnosis and management. We conclude that a multipronged approach towards early diagnosis and vigorous management should be adopted to reduce the morbidity and mortality in patients with blunt abdominal trauma.

Abdominal Injuries↗
PubMed1995

Breath-hold 3D STAR MR angiography of the renal arteries using segmented echo planar imaging.

Three-dimensional (3D), cardiac triggered renal MR angiograms were acquired with excellent background suppression within a single breath-hold of 18 to 30 s using signal targeting with alternating radiofrequency (STAR), a subtraction time-of-flight MR angiography technique, and a 3D scheme combining echo planar imaging (EPI) readouts and k-space segmentation. The 3D STAR sequence was evaluated on 17 healthy individuals, 3 potential renal donors, and 2 patients with suspected renovascular hypertension. An inversion tag through the aorta was applied to produce the vascular contrast. After a suitable inflow time, 16 to 64 sections were encoded. An additional presaturation pulse applied over the imaging volume prior to tagging permitted improved background suppression by reducing signal variations from involuntary motion and changes in the cardiac period during breath-holding. Intrarenal branches were observed consistently in all healthy individuals. Longer inflow times provided better depiction of the intrarenal vessels while shorter delays delineated the proximal renal branches with better signal-to-noise ratio. Breath-hold and diastolic data collection reduced both blurring and flow related dephasing. Our results demonstrate excellent visualization of the renal arteries to the level of intrarenal branch vessels using the proposed technique.

Adult↗
PubMed1995

Coupling of a finite element human head model with a lumped parameter Hybrid III dummy model: preliminary results.

A skull-brain finite element model of the human head has been coupled with a multilink rigid body model of the Hybrid III dummy. The experimental coupled model is intended to represent anatomically a 50th percentile human to the extent the dummy and the skull-brain model represent a human. It has been verified by simulating several human cadaver head impact tests as well as dummy head 'impacts" during barrier crashes in an automotive environment. Skull-isostress and brain-isostrain response curves were established based on model calibration of experimental human cadaver tolerance data. The skull-isostress response curve agrees with the JARI Human Head Impact Tolerance Curve for skull fracture. The brain-isostrain response curve predicts a higher G level for concussion than does the JARI concussion curve and the Wayne State Tolerance Curve at the longer time duration range. Barrier crash simulations consist of belted dummies impacting an airbag, a hard and soft steering wheel hub, and no head contact with vehicle interior components. Head impact force, intracranial pressures and strains, skull stress, and head center-of-gravity acceleration were investigated as injury parameters. Head injury criterion (HIC) was also calculated along with these parameters. Preliminary results of the model simulations in those impact conditions are discussed.

Accidents, Traffic↗
PubMed1994

In vivo measurement of water diffusion in the human heart.

Existing magnetic resonance methods for diffusion imaging, including echo planar, are ineffective in the beating heart due to motion-induced signal attenuation. To overcome this problem, we used a diffusion-weighted stimulated echo-echo planar magnetic resonance imaging sequence. The two lobes of the diffusion-sensitizing gradient were synchronized to the same point in successive cardiac cycles in order to fix the cardiac position and avoid bulk motion effects. The apparent diffusion coefficients (ADCs) of the interventricular septum in 12 healthy subjects for diffusion gradients along the x-, y-, and z-directions were 1.40 +/- 0.27, 1.48 +/- 0.35, and 1.78 +/- 0.27 x 10(-3) mm2/s. The ADCs of the interventricular septum in a second group of 15 healthy subjects for diffusion gradients along the short axis, horizontal and vertical long axes were 0.92 +/- 0.15, 1.50 +/- 0.15, and 1.10 +/- 0.24 x 10(-3) mm2/s. Because the ADCs were less than the measured values for skeletal muscle and their standard deviations were low, it seems unlikely that bulk motion effects made the dominant contribution to the measured myocardial ADC for the interventricular septum, although motion and/or susceptibility artifacts frequently degraded measurements in the free wall of the left ventricle. Additional evidence that ADC was not predominantly determined by wall motion was obtained in a third group of patients with various cardiac abnormalities, in whom there was only a weak correlation between ADC and ejection fraction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1994

Abdominal diffusion mapping with use of a whole-body echo-planar system.

PURPOSE: To measure apparent diffusion coefficients (ADCs) of water in liver, spleen, kidney, and muscle. MATERIALS AND METHODS: Ten volunteers (seven women and three men, aged 19-31 years [mean, 24 years]) and nine patients (five women and four men, aged 49-70 years [mean, 62 years]) (liver cyst, n = 3; liver hemangioma, n = 3; liver cirrhosis, n = 2; hepatocellular carcinoma, n = 1; and liver metastasis, n = 1) underwent magnetic resonance (MR) imaging. A stimulated-echo acquisition mode (STEAM)-type excitation and echo-planar imaging (EPI) readout was used in a 1.5-T echo-planar MR imaging system. RESULTS: ADCs measured in volunteers were liver, 1.39 x 10(-3) mm2/sec +/- 0.16; spleen, 0.95 x 10(-3) mm2/sec +/- 0.15; muscle, 1.99 x 10(-3) mm2/sec +/- 0.16; and kidney, 3.54 x 10(-3) mm2/sec +/- 0.47 (mean +/- standard deviation). Distinctive ADC values were found in organs with abnormalities. ADCs in patients with hepatic disease included liver cysts, 3.9-5.3; liver hemangiomas, 2.0-2.8; liver metastases from an islet cell tumor, 1.2; hepatocellular carcinoma, 1.7; and liver cirrhosis, 0.9-1.2 x 10(-3) mm2/sec. CONCLUSION: In vivo diffusion measurements of abdominal organs obtained with MR imaging may prove helpful in the identification and classification of abdominal disease.

Abdomen↗
PubMed1994

Congenital ocular motor apraxia: sporadic and familial. Support for natural resolution.

Four patients aged between 9 months and 17 years were detected to have congenital ocular motor apraxia (COMA) over a 10-month period. Three of them were siblings. All exhibited the classical signs of a horizontal saccadic palsy. However, the signs were less pronounced with increasing age of the patient. This supports the observations of other authors who have noted an age-related resolution. There was no evidence of other motor developmental delay in any of the patients and computed tomography revealed no abnormalities. Both these findings are in contradistinction to prior reports of central nervous system abnormalities and motor and speech difficulties in COMA. The family of three appears to be the largest sibling cluster reported so far.

Adolescent↗
PubMed1994

Physicianship.

Explore the source record for details and available documents.

History, 16th Century↗
PubMed1991

Quantification of midline shift as a predictor of poor outcome following head injury.

A retrospective study of patient outcome, based on admission computed tomography, was carried out in 75 consecutive patients with head injury. Computed tomography data collected included the type and extent of intracranial hemorrhage, the extent of midline shift, and the ratio of midline shift compared with the extent of intracranial hemorrhage. Midline shift was considered to be out of proportion to intracranial hemorrhage when the midline shift of the septum pellucidum exceeded the extent of the hemorrhage as measured radially from the inner table of the skull. When computed tomography data were analyzed by logistic regression, significant predictive factors for poor outcome were intracranial hemorrhage (34%), intracranial hemorrhage with midline shift (61%), and midline shift out of proportion to the extent of intracranial hemorrhage (88%). When patient outcome and mortality rates are considered, our study indicates that midline shift out of proportion to the extent of intracranial hemorrhage is a highly useful predictor of poor patient outcome following head injury.

Adult↗
PubMed1990

Accelerated ocular neovascularisation in diabetics following posterior chamber lens implantation.

Two well controlled non-insulin dependent diabetics with background retinopathy underwent endocapsular lens extraction with in-the-bag posterior chamber implantation. In the postoperative period rubeosis iridis set in abruptly. The fellow eyes showed no progression of retinopathy and the diabetic status showed no deterioration. The cause of neovascularisation and the role of intra- versus extracapsular extraction with implantation are discussed.

Aged↗