Cesarean section scar ectopic pregnancy: a clinical case series.

Cesarean scar implantation represents a rare, though growing subset of potentially life-threatening ectopic pregnancy. Because of the global increase in cesarean sections as well as the improved diagnostic abilities of transvaginal ultrasound, incidence rates have continued to rise since the first reported case in 1978. Uterine rupture and catastrophic hemorrhage can ensue when diagnosis is delayed. Additionally, a higher rate of concurrent trophoblastic myometrial invasion may increase the incidence of retained products of conception or post procedural bleeding. Endovaginal ultrasound has a reported sensitivity of 85 % for detection. In difficult cases, magnetic resonance imaging is often useful as a problem solving exam in confirming diagnostic suspicions and guiding therapeutic decisions. We present a series of five illustrative cases illustrating the range of clinical and imaging findings.

Sonography of placental abnormalities: a pictorial review.

Often overlooked during routine ultrasound evaluation of a normal pregnancy, the placenta forms the biologic interface between the mother and fetus and is critical to fetal growth and development. Malformations in development, positioning, and vascularity can have profound implications for both maternal and fetal well-being. As such, a judicious inspection of the placenta is warranted as an integral part of every screening or emergent prenatal ultrasound. Herein, we present a pictorial review of a variety of placental pathologic conditions including abnormalities in positioning, adherence, vascularity, and hemorrhage as well as potential peri-placental masses and gestational trophoblastic disease, all of which are readily encountered in a busy emergency radiology practice.

New algorithm for quantifying vascular changes in dynamic contrast-enhanced MRI independent of absolute T1 values.

In this work, we present a new method for predicting changes in tumor vascularity using only one flip angle in dynamic contrast-enhanced (DCE) imaging. The usual DCE approach finds the tissue initial T1 value T1(0) prior to injection of a contrast agent. We propose finding changes in the tissue contrast agent uptake characteristics pre- and postdrug treatment by fixing T1(0). Using both simulations and imaging pre- and postadministration of caffeine, we find that the relative change (NR50) in the median of the cumulative distribution (R50) is almost independent of T1(0). Fixing T1(0) leads to a concentration curve c(t) more robust to the presence of noise than calculating T1(0). Consequently, the NR50 for the tumor remains roughly the same as the ideal NR50 when T1(0) is exactly known. Further, variations in eating habits are shown to create significant changes in the R50 response for both liver and muscle. In conclusion, analyzing data with fixed T1(0) leads to a more stable measure of changes in NR50 and does not require knowledge of T1(0). Both caffeine and eating introduce major changes in blood flow that can significantly modify the NR50 and lead to incorrect conclusions regarding drug treatment.