الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
The human placenta is a vital organ during pregnancy. It links the developing fetus via the umbilical cord to the materanl blood supply to allow the exchange of oxygen, carbon dioxide, uptake of nutrients, and removal of waste products. It can produce many hormones and growth factors, such as progesterone and the human chorionic gonadotropin. Placental perfusion depends on both maternal blood supply and resistance of placenta to blood flow. Pathological development of the placenta can lead to intrauterine growth restriction (IUGR) and pre-eclampsia (PE) with subsequent fetal, materanl and long term complications of the siblings can occur. Ultrasound is the most commonly used non-invasive procedure for evaluation of placental site, maturation, any placental hematoma and assesse the site of cord insertion. Doppler techniques can provide useful information regarding fetal-maternal circulation through measurment of umbilical artery and midle cerebral artery resistive indices but ultrasound has its limitations being operator dependant. Magnetic resonanance techniques allow noninvasive assesement of placental structure and function. Arterial spin labeling ASL-MRI is a noninvasive, powerful imaging method for measuring tissue perfusion. It provides penificial information in assessment of placental function. ASL utilizes the water molecules in arterial blood as an endogenous contrast agent, making it optimal for examining placental perfusion in pregnancy. Our study aimed to evaluate the diagnostic role of pulsed ASL-perfusion MRI as a non-invasive technique for assessment of placental perfusion parameters with evaluation of its potential for early detection of placental insult. This prospective case control study was carried out at the Radio diagnosis Department, Tanta University Hospital, enrolled 30 patients with different causes of placental insufficiency & 30 volunteers with healthy pregnancy of matched age. Their age ranged from 21 to 42 years in the diseased group and from 24 to 37 years old in the control group. The current work studied different risk factors and found out a statistically significant relation between hypertension and reduced ASL-placental perfusion, with P-value=0.015. A statistically significant relation was noted too between preeclampsia and high umbilical artery resistive index, P-value= 0.047, and between preeclampsia and reduced MRI placental perfusion P-value= 0.045. Also, a statistically significant difference was detected between bad obstetric history, consanguinity and reduced placental perfusion P-value= 0.001. No statistically significant relation was noticed between diabetes mellitus and umbilical artery resistive index, middle cerebral artery resistive index and MRI placental perfusion. Moreover, no statistically significant relation was detected between hypertension and umbilical artery resistive, middle cerebral artery resistive indices. Also, no statistically significant relation was noted between pre-eclampsia and middle cerebral artery resistive index. There was a statistically significant difference between the high umbilical artery resistive index and MRI perfusion, with P-value= 0.005, while no statistically significant relation was detected between the middle cerebral artery RI and MRI perfusion, with P-value=0.973. Analysis of diagnostic accuracy of ASL-prefusion revealed a statistically significant performance, P-value< less than 0.001, with high area under curve=0.917, cut-off value=54.0, sensitivity= 90%, specificity=83.3%, PPV=84.4%, NPV=89.3% and accuracy 86.7.3%. Magnetic resonance Imaging MRI became an emerging, effective, and safe diagnostic tool, added to ultrasound and conventional MRI in diagnosis and assessment of placental tissue perfusion, with an excellent interobserver agreement providing additional important information on top of ultrasound of placental conditions.