Gamma Camera Examination of Pregnant Uterus and Placental Perfusion

Abstract

Abstiact. Radioactive """'Tc (300 &I) tracer and a gamma camera were used to study placental function between the 34th and 40th weeks of pregnancy in 10 women with a normal pregnancy, 34 with mild and two with severe pre-eclampsia. The placenta was first localised by the Doppler method and then the gamma camera was aimed at right angles to the site. After the injection the radioactivity over the placenta was counted and a series of radiographs was made at intervals of 30 sec for up to 12 m n . The two values correlated. When the material was grouped according to the week of pregnancy, perfusion was fastest in the 34th week (3.1k0.87 min) and slowest in the 40th week ( S . S i 1.27 min). The difference was significant. There was no significant difference when the material was divided into groups on the basis of normal and toxaemic pregnancies.

A method for the assessment of placental blood perfusion using99mTc pertechnetate

“…Recently, Laakso et al [8] introduced a gamma camera study for the measurement of uterine and placental perfusion, using 99mTc as a tracer. The appearance of the tracer was followed until it reached maximum activity and the time between injection and the maximum was recorded.…”

Assessment of Uteroplacental Hemodynamics in Complicated Pregnancy

“…Other authors have described their results in terms of uteroplacental turnover (24), initial slope and halftime of accumulation (1) and placental perfusion index (13). More empirical evaluation of the results from inflow measurements have also been reported (15,18,22). In the present work, times of the placental, heart and myometrial inflow phases have been the indices for assessing the hemodynamic situation, producing useful information and avoiding inaccurate assumptions.…”

“…Assali et al (2) demonstrated this in 1954 by direct sampling of the blood, and others, by measuring the inflow phase of radioactive isotopes (13,15,22,24). Applying a similar technique, Laakso et al (18) found no differences between a group of healthy patients and one with mild preeclampsia. However, in the same work two cases of severe preeclampsia gave prolonged times for maximal isotope concentration to be reached in the placenta.…”

Determination of Placental Blood Flow by External Monitoring of 113mIn

“…The results were given in units of min -1 . The placental perfusion index presented by Laakso et al (5) was calculated as the time interval from the appearance of the vascular phase to the equilibrium point during the accumulation phase.…”

“…To avoid these drawbacks several i.v. injection techniques based on detection of the appearance curve of the tracer at the placental site have been described (1,2,5).…”