Purpose: To investigate MRI of the fetal heart by way of a novel triggering method with the use of an MR-compatible cardiotocography (CTG) in an animal model. Materials and Methods:Fetal cardiac MRI was performed on four pregnant ewes on a 1.5 Tesla (T) MR system. A CTG was rendered MR compatible and its signal was used for the triggering of the fetal heart to perform cardiac cine MRI of the fetal heart with maternal freebreathing with cine steady-state free precession. The left ventricular volume and function were measured from the short-axis (view). The image quality of anatomical structures was assessed.Results: All cardiac valves and the foramen ovale could be visualized. Myocardial contraction was depicted in cine sequences. The average blood volume at the end systole was 1.7 mL (SD 6 0.12). The average volume at the end diastole was 4.6 mL (6 0.4); thus the average stroke volumes of the left ventricle were 2.87 mL (6 0.31) with ejection fractions of 60.53% (6 4.17). Conclusion:The newly developed MR compatible CTG could be used as a tool for cardiac triggering method of the fetal heart. This novel device might help fetal cardiac MRI technology in the future. THE RAPID DEVELOPMENT of cardiac MR imaging in the past few years has enabled many different investigations, for example investigations into coronary arteries and myocardial infarctions. In practice, twodimensional (2D) CINE steady-state free precession (SSFP) imaging is the most reliable and frequently used technique for left ventricular (LV) function assessment. To assess the LV function correctly, speed as well as synchronization of data acquisition with the cardiac cycle are required, so that artifacts due to cardiac motion and flow constraints that dictate the viable window for data acquisition are avoided. To avoid the artifacts caused by cardiac motion, it is customary that either finger pulse oximetry or electrocardiography (ECG) triggering/gating techniques are used so that data acquisition can be synchronized with the cardiac cycle.Although the use of MR imaging during pregnancy is limited to the second and third trimester, its diagnostic value has been increasing in recent years. In the field of fetal MR imaging, the evaluation of the fetal heart is one of the greatest challenges. Nowadays, the gold standard in fetal cardiac imaging is the use of ultrasound (US), because it can be obtained during the entire pregnancy; it is easy to use and thus more practicable. Both the measurement of the cardiac volume and the evaluation of volumetric changes with US are possible, and the technology has been improving. Because cardiac chambers do not lend themselves to geometric assumptions, it has always been difficult to calculate their dimensions, even though studies have shown that 3D US has a better reproducibility than 2D (1-4). To be able to do so, it is necessary to trace the volume of the cardiac chambers manually, due to the appearance of various US specific artifacts, such as speckles and acoustic shadowing, which appear when traced automaticall...

Both self-gating and pulse-wave triggered cardiac MRI of the fetal heart allowed the evaluation of anatomical structures and functional information. Images obtained by self-gating technique were slightly inferior than the pulse-wave triggered MRI.

The aim of this study was to perform fetal cardiac magnetic resonance imaging (MRI) with triggering of the fetal heart beat in utero in a sheep model. All experimental protocols were reviewed and the usage of ewes and fetuses was approved by the local animal protection authorities. Images of the hearts of six pregnant ewes were obtained by using a 1.5-T MR system (Philips Medical Systems, Best, Netherlands). The fetuses were chronically instrumented with a carotid catheter to measure the fetal heart frequency for the cardiac triggering. Pulse wave triggered, breath-hold cine-MRI with steady-state free precession (SSFP) was achieved in short axis, two-, four- and three-chamber views. The left ventricular volume and thus the function were measured from the short axis. The fetal heart frequencies ranged between 130 and 160 bpm. The mitral, tricuspid, aortic, and pulmonary valves could be clearly observed. The foramen ovale could be visualized. Myocardial contraction was shown in cine sequences. The average blood volume at the end systole was 3.4 + or - 0.2 ml (+ or - SD). The average volume at end diastole was 5.2 + or - 0.2 ml; thus the stroke volumes of the left ventricle in the systole were between 1.7 and 1.9 ml with ejection fractions of 38.6% and 39%, respectively. The pulse wave triggered cardiac MRI of the fetal heart allowed evaluation of anatomical structures and functional information. This feasibility study demonstrates the applicability of MRI for future evaluation of fetuses with complex congenital heart defects, once a noninvasive method has been developed to perform fetal cardiac triggering.

For over a decade now, I have been accumulating some fascinating data on the images of American history that my students have carried around in their heads before entering my classroom. The term data may be misleadingly scientific, and I am not even sure my hunting and gathering process deserves to be called research, since it began playfully, as little more than a tonic designed to fortify student recruits setting out on their uncertain trek across the arid reaches of the standard survey course. Increasingly, however, I have come to sense that there may be some broader meaning, or at least interest, in the picture gradually emerging from this experimentation.That sense has been recently sharpened by loud alarums -the very lively debate about American education's role in the ominously accelerating historical amnesia reportedly afflicting high school and college students. As it happens, my modest experiments in what can be called "empirical iconography," conducted well before that debate emerged, address its concerns quite directly, providing a certain reassurance in the face of the jeremiads while raising some disturbing questions of a rather different sort.Let me begin with some brief frame-setting observations about the problem at hand. I will then turn to a straightforward unfolding of my quasi-scientific data combined with some unlicensed flights of exegetical excess. I will conclude by returning to the contemporary debate about American education and historical memory, in order to see how different it may appear after our excursion into the realm ofthe collective historical subconscious, or at least that portion ofit embodied in the responses of over one thousand students at the State University of New York at Buffalo (SUNY-Buffalo) over the past decade.As a general matter, discussions of historical memory have not been very clear about the relation of individual-level processes-what and how we remember, whether about our own or more broadly historical experience-and the processes of collective memory, those broader patterns through which culture may shape the Michael Frisch is professor of history and