Como dizer "Exame de imagem" em inglês

Okay, fine Rakell, "scans" would be better . "I'm going to the hospital for some scans" should cover every type of medical Imaging.

Medical Imaging( Medical Imaging procedure)
Medical imaging is the technique and process used to create images of the human body (or parts and function thereof) for clinical purposes (medical procedures seeking to reveal, diagnose, or examine disease) or medical science (including the study of normal anatomy and physiology). Although imaging of removed organs and tissues can be performed for medical reasons, such procedures are not usually referred to as medical imaging, but rather are a part of pathology.
Medical imaging refers to several different technologies that are used to view the human body in order to diagnose, monitor, or treat medical conditions. Each type of technology gives different information about the area of the body being studied or treated, related to possible disease, injury, or the effectiveness of medical treatment.
Types of imaging tests:
Computed tomography scan
Magnetic resonance imaging scan
Radiographic studies
Mammography
Nuclear scans
Ultrasound

Computed tomography (CT), sometimes called "computerized tomography" or "computed axial tomography" (CAT), is a noninvasive medical examination or procedure that uses specialized X-ray equipment to produce cross-sectional images of the body. Each cross-sectional image represents a “slice” of the person being imaged, like the slices in a loaf of bread. These cross-sectional images are used for a variety of diagnostic and therapeutic purposes.
CT scans can be performed on every region of the body for a variety of reasons (e.g., diagnostic, treatment planning, interventional, or screening). Most CT scans are performed as outpatient procedures.

http://en.wikipedia.org/wiki/Medical_imaging
http://www.fda.gov/Radiation-EmittingPr ... efault.htm
http://www.fda.gov/Radiation-EmittingPr ... 5317.htm#1

Ok, então mesmo quando não sei qual "exame de imagem" é, eu devo usar CAT ou CT scan para me referir a todos eles? Independentemente de qual seja?

Sim, mas "medical imaging" não é um termo que as pessoas usam. É mais rapido dizer "I'm going in for a CT scan" than "I'm going to have a medical imaging procedure done".

Muitas vezes, um termo específico é utilizado para se referir a algo geral, como "computed tomography" (ou CT scan/CAT scan) para dizer "medical imaging".

Sim, a tomografia é CAT scan, mas de um modo geral os procedimentos com imagem, dos quais a topografia faz parte, são Medical Imaging ou Medical Imaging procedures.

O nome comum para isso é "CAT Scan" ou "CT Scan", como dizem no artigo de Rakell.

Eu diria "The doctor asked me to have/get a CAT scan".

E acho que falamos to have a Medical Imaging procedure done/performed, pois não fazemos, mas sim o procedimento que é feito em nós.