RADIOGRAGHIC CONTRAST MEDIA

RAD 321

LEC (2)

Design/layout by E Bashir, CAMS, King Saud University, 2008

Radiographic Contrast Media

* The radiographic density of the tissues of the body depends on the atomic number of the substances of which the tissues are composed.

* Most of the body tissues (e.g. the skin, muscles and abdominal viscera) are composed of carbon, hydrogen and oxygen which have low atomic numbers and display very small differences in density. Bones have high atomic number and display very big differences in density.

• In simple or conventional radiograph, the outlines of many tissues or

organs are either:• Very poorly delineated

• Or• are not visible at all.

Vascular And Urographic C.M. * These are pharmaceuticals that alter tissue characteristics to enhance information obtained on diagnostic images. * They are organic iodine compounds * They form the major positive contrast media used in diagnostic imaging. * They are categorized as: (a) high osmolality, (b) low osmolality contrast media

The high osmolality contrast media

-(HOCM) have very high osmolalities (about 4-7 times the osmolality of cell and tissue fluid ) and are hypertonic. -They are solution of the salts.-These salts are dissociate, completely in solution, each molecule providing one cat ion and a large organic iodine containing an ion. Hence another name for these HOCM is “Ionic contrast media”. Both an ion and cat ion have equal osmolar effects, but the an ion is radio-paque -Many of the adverse effects of contrast media are the result of high osmolality.

The Low Osmolality Contrast Media -These are non- ionic dimmers which have a ratio of six iodine atoms for each molecule in the solution.

-The terms low osmolar and non-osmolar are not synonymous. The major difference between the two groups is that ionic C.M. cannot be used in the sub-arachnoids space.-The osmolality was eliminated or reduced by reducing the number of the cat ion in these contrast media which does not contribute to the radiopacity, but is responsible for up to 50% of the osmolitic effect (Toxicity of C.M.).

-The osmolality was eliminated or reduced by reducing the number of the cat ion in these contrast media which does not contribute to the radiopacity, but is responsible for up to 50% of the osmotic effect (Toxicity of C.M.)

- The ratio of iodine atom in the molecule to the number of particles in solution is 3:2 for HOCM compared to 3:1in LOCM.

Reactions to contrast media(1) Minor reaction:--Urticaria.-Sneezing.-Flushing.-Nausea.-Vomiting.No, treatment is usually required.

Major reaction:-Requires treatment.-They are life-threatening, severe reactions which cause real danger and for which swift treatment is so important. -Most such reactions occur within five minutes of the injection and the great majority within thirty minutes so that a doctor should be at hand for this period whenever an injection of C.M. has been given.

Major reactions include:-(a) Broncho spasm-wheezing.(b) Laryngeal angio neurotic oedema-Choking.(c ) Vascular collapse and lose of consciousness(d) Cardiac arrest.(e) Respiratory failure.

-Treatment of major reaction dependent on immediate availability of the following:-

* The necessary expertise. * Drugs. * Equipment.

The role of the radiographer in case of emergency

1) Know how to call for help without leaving the patient and the room. 2) Know where the nearest supply of oxygen and how to administer it. 3) Know how to call the “crash team” and to communicate with the radiologist. 4) Know where the emergency drugs and the key to the drug cupboard/trolley.

BASIC & Advanced life supports

and emergency equipment.- Basic life support (CPR) i.e. Cardio-Pulmonary Resuscitation.- Advance life support ( Endotracial &

Defibrillator).- Emergency equipment:-1) Oxygen and equipment for artificial

ventilation.2) Drugs.3) Equipment.

Thank you