I'm afraid I have to disagree with you here.
I agree 100% that the general term for 'scan' is 'exploració' - as it happens, I couldn't think of what the general term for 'scan' was in Catalan late last night and was sure that someone would provide it -which you did - thank you!
However, an 'ecografia' is either called an 'ultrasound' or a 'scan'. I can speak with absolute confidence on this point as I am indeed pregnant at the moment, as Margarita suggested a while back, and am going for my 'scan' / 'ecografia' in a few weeks' time
e.g. 'Will the scan reveal the sex of my baby?'
'Viability scans are easily performed at 7-11 weeks of pregnancy'
I guess the full term would be 'ultrasound scan' but doctors and midwives just talk about 'scans' as we all know what type they are referring to and are unlikely to think they are sending us for brain scans
The terms 'echography' and 'ultrasonography' that Termcat suggest refer to the technique itself rather than the actual process.
'Aquest migdia m'han fet la meva primera ecografia com a embarassada per veure com pintava la cosa'
would be 'They did my first scan (or ultrasound)...'