CAT scan can be performed even without a dye.

Diagnostic imaging techniques are essential for confirming, assessing, and documenting the course of many diseases and response to treatment.  Here are some diagnostic imaging techniques: Mammography: An X-ray imaging method used to examine the breast for the early detection of cancer and other breast diseases. CT scans: A diagnostic imaging procedure that uses a combination of X-rays and computer technology to produce images of the inside of the body. MRI scans: A type of diagnostic imaging which uses powerful magnets and radio waves to produce detailed images of the inside of your... Show more

Diagnostic imaging techniques are essential for confirming, assessing, and documenting the course of many diseases and response to treatment. 

Here are some diagnostic imaging techniques:
Mammography: An X-ray imaging method used to examine the breast for the early detection of cancer and other breast diseases.
CT scans: A diagnostic imaging procedure that uses a combination of X-rays and computer technology to produce images of the inside of the body.
MRI scans: A type of diagnostic imaging which uses powerful magnets and radio waves to produce detailed images of the inside of your body.
Positron emission tomography: Also called a PET/CT scan, this is a combination of the Positron Emission Tomography (P.E.T.) and Computed Tomography (CT) technologies.
Fluoroscopy: A diagnostic imaging technique that uses X-rays to make moving images of the body.
Multinuclear imaging: The mainstay when diagnosing diseases of the retina.
Optical imaging: A crucial component of medical diagnosis and treatment.
Bone scan: A diagnostic test that uses nuclear imaging. 

Topics include: Ultrasound, echocardiography, x-ray, fluoroscopy, PET, SPECT, computerized axial tomography, MRI and FMRI.

Related: Clinical Sciences Practice Test: Diagnostic Investigation in Neurology and Cardiology

Show less