No idea. I also thought medical at first, but my thinking ended there. To clarify EKG... I hope I get this right!!

EKG = ElectroCardioGram and hence = ECG just about everywhere except the US. Provides a readout of electrical activity in the heart.

EEG = ElectroEncephaloGram, and I think it = EEG everywhere. Provides a readout of the electrical activity in the brain.

And while we're being medical... the difference between dilated and dilatated?

And on another topic... the difference between ~ic and ~ical?