Positive And Negative Contrast Media Biology Essay

In the field of radiology, some probe or process on a patient in demand of contrast into the patient ‘s organic structure through a vena, arteria, oral cavity or anus, which is located in the organic structure. Since the innovation of the epoch of the 1950s, I contrast media ( ICM ) is seemingly more unafraid have been used extensively, about day-to-day usage and is a widely used drug in medical history. Assorted signifiers and types of contrast media was used for the development of medical imagination. Most current diagnostic imagination contrast agents depends on this. Such as pharmaceutical drugs most others, this contrast agent was about no negative effects even with a good safety record and proved medical specialty / drug is safe for usage.

If seen on x-ray movie, there are normally images of the anatomy such as bone, and at that place besides appears a white colored gas that surrounds around the variety meats. The existent purpose is the usage of contrast media to increase the denseness of the organ is normally non seeable on radiogram, such as transition of piss or blood vass, which originally did non look at regular chest x-ray contrast media are non used. After application of contrast media, the ensuing image will be white demoing a concealed organ. Contrast media is composed of two types of Attic and non Attic

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contrast media devided into two classs

Positive contrast media

Negative contrast media

Positive contrast media

Positive contrast agents are agents that have the atomic mass and a high rate of obstructor ( fading ) high. So these agents are so radio-opaque stuff. Positive contrast media are as I, Br, and Ba.

Typically, these stuffs will be incorporated into the organic structure ( harmonizing to appropriate processs ) and contrast agents will run into the mark organ. Effectss ensuing radiopaque would explicate the state of affairs and construction of the organ / tissue targeted at radiographic images. By and large, a positive contrast agent is the key to guaranting that the patient has allergic reactions or non for the choice of the contrast media can be tailored to the patient to avoid the effects of anaphylactic daze.

Negative contrast media

one of x-ray soaking up is the weight of the atomic mass of a substance. If the atomic mass is low, the consequence of obstructions ( attenuate ) is low and the contrary occurs when the atomic mass additions. When the mass of the atom is high, it will bring forth an consequence of denseness / contrast skiagraphy of the image because the image will go more permeable and dark. This characteristic is utile when an anatomical construction is shown with a background of really permeable and the big difference in contrast between the image and the background ( without bring forthing blur the boundaries between image and background ) .

contrast media such as air ( O, C dioxide, etc. ) are good illustrations as negative contrast agents. Negative contrast agents frequently used in concurrence with contrast agents positf and one common processs frequently incorporate the usage of these agents were negative dual Ba clyster.

Examples of gas used to bring forth negative contrast in radiographic images:

Carbon dioxide

Produced in the GI piece of land ( GIT ) with Ba sulphate to show mucosal form. Double contrast Ba repast for illustration. Carbon dioxide can besides be produced by the colon when given dual contrast media, as it reduces hurting and cut downing tummy uncomfortableness instantly.


Produced in the organic structure pits such as in the articulatio genus when analyzing arteriogram to show the articulatio genus articulation.


Produced by the patient during the radiographic scrutiny, for illustration, took a deep breath and clasp during chest scrutiny.

Basic I contrast media

Several probes in the radiology demands of this contrast into the patient ‘s organic structure through a arteria or a vena. A frequent illustration is the endovenous urogram. Normally merely the castanetss and the air current will be seeable on x-ray images. To separate the way of blood in the piss or blood vass, contrast media incorporating I to be added to increase the strength of blood or piss. Then, this will do the construction to look ‘white ‘ in movies such as the castanetss of patients in x-ray images.

Categorization of Contrast Media

There are two parts: the Attic and non Attic.

Ionic compound is divided into two parts ; high degree of osmolar contrast media ( hocm ) , and low degree of osmolar contrast media ( locm ) . This categorization is based on the iodine concentration of atoms ( by and large as elements of contrast media is often used in the process IVU ) absorbed / dissolved into the blood. If the rate of soaking up of I is excessively high, it can decelerate the blood flow into the cardinal nervous system ( hyperosmolality ) . This state of affairs is a major factor many negative reactions to patients due to contrast media that are non appropriate.


Rate of osmolality ( mOsm/kg )

High-osmolar contrast media


low-osmolar contrast media


Non-ionic compounds




Cerebrospinal Fluids



Contented molecules tightly to the anion and cation ( positive and negative ) in the blood doing high osmolality – toxic / reaction high.Properties of molecules incorporating benzine rings, for illustration – salt compound meglumine diatrizoate and diatrizoate Na ( Renografin 60 and Hypaque 76 – osmolaliti high )

Features of iodine contrast agents ;

one Osmolality ( no liquid particles in 1 kilogram of H2O )

two viscousness – the size of the rejection of ( immune ) to the flow of fluids ( viscousness / concentration )

three Toxicity – ( poisoning / hurt ) , it is based on the molecular constellation.


Molecules are non resolved in the fluid / blood.For illustration, a compound of Na diatrizoate ( iopamidol, isovue, iohexol / omnipaque )

– Measures of attention ;

I. Can non transcend the dosage.

two. Stay off from the Sun.

three. Stored at room temperature.

Chemical reactions to contrast agents – I:

Use of Iodine contrast media ( ICM ) can do unwanted side effects and manifestations of anaphylaxis. Symptoms include sickness, purging, erythema country, by and large a hot esthesis, concern, rhinitis or voice box hydrops, febrility, sudating, astenia, giddiness, lividness, dyspnea and moderate low blood force per unit area. more acute reactions in such as vasodilatation cardiovasluar system with marked peripheral hypotension, tachycardia, dyspnea, action, blue tegument status ( cynosis ) and deficiency of consciousness, needs exigency intervention. On behalf of this ground the usage of contrast media should be limited in instances of diagnostic processs must be shown. Side effects associated with usage of intravascular contrast medium is changeless iodinated of natural visible radiation to chair and impermanent, and less frequently by non-ionic than ionic readyings. Side effects to ICM are classified as particular and nonidiosyncratic. The pathogenesis of these inauspicious reactions may affect direct effects of nomadic phone ; enzyme initiation, and activation of quinine, fibrinolytic complement, and other systems.


First, look into the history of the patient.Make sure the reading of the BUN-blood urea N ( 8-25mg/dl kretinin ) – ( 0.6-1.5 milligram / deciliter ) .Actions taking steroid / anti-histamine before contrast scrutiny. Check patient bosom condition.If the patient have Multiple myeloma or myelo dysplastic syndrome or terrible diabetes ( preferable drink a batch of H2O ) .

Anaphylactic daze.

The other name is Vasogenic daze. Histamine is released in response to an antigen ( foreign substance ) . They give consequence to ; smooth muscle – doing bronchial cramp ( bronchospasm ) respiratory ( sneezing, wheezing, a pilot ) . Increased vascular permeableness – ( urticaria, hydrops of the mucous membrane, ruddy musca volitanss ( roseola ) . Increased secernment of mucose secretory organs ( sickness, purging ) .

Sign of the symptom ( anaphylactic daze ) are patients will get down to be Agitated. Rate of pulsation will be increased dramatically.The patient appeared pale and weak and exanimate body.They do non hold the ability to believe excessively long.The patient feels cold, gluey and antsy skin.skin of the patient will be ruddy and spotted ( urticaria ) . Patient ‘s cervix like a choking / choking and Trouble external respiration.

Mild symptoms

Weak symptoms include the undermentioned disease: spread urtication, which is the really normally stated as inauspicious reaction ; illness of pruritus ; rhinorrhea ; brief retching or sickness or emesis ; giddiness, perspiration ; coughing. Patients with mild symptoms should be noticed about the patterned advance or development of a more terrible consequence, which needs treament.

Moderate symptoms

medium symptoms include the undermentioned: changeless emesis ; diffuse urtications ; hurting in caput ; facial hydrops ; laryngeal hydrops ; weak bronchospasm or trouble in take a breathing ; palpitations, rapid bosom round ( tachycardia ) , or awkwardness of bosom round ( bradycardia ) ; high blood force per unit area ; and abdominal cramps or spasms.

Severe symptoms

Acute symptoms include the undermentioned: dangerous arrhythmias ( in illustration ; ventricular tachycardia ) , laryngeal hydrops, swoon, over bronchospasm, pneumonic hydrops, cramp, low blood force per unit area, and decease.

Comparison of contrast agents:

Ionic agent

Non-ionic agent

Toxicity – high hazard of allergic reaction

Toxicity – less / low hazard



Osmolality high

low Osmolality

High viscousness

low viscousness

Contrast media needed for Radiological scrutiny:

To separate the way of blood in the piss or blood vass, normally merely the castanetss and the air will be seeable on x-ray and to better the denseness of piss or blood.

Advantages of contrast media:

easy dissolved.


Provide better mucosal item

There is no osmotic consequence, so the wireless denseness is durable.


Relatively delightful

Disadvantages of contrast media:

Aspiration pneumonia if inhaled.

If got escape into the pit or variety meats of the organic structure. It can & amp ; acirc ; ˆ™t last indefinitely and may do granulomatous reactions.

contrast media direction

Chemical reactions that occur while the process of contrast media are non predictable, and the patient should be observed carefully during the process. The followers is general advice to be given by an x-ray contrast media every bit good as introduced to the patient.

explain to the patient about the process in item

the patient and medical history

approved by finishing the patient consent signifier

look into the consecutive figure or codification and expiry day of the month of contrast stuff

free virus cheque on each contraption and packaging that will be used

guarantee that exigency equipment used are provided

patients are encouraged to imbibe plentifulness of H2O and do certain the patient ‘s organic structure desiccation. Most of the contrast media will be out through the piss after four hours

do certain the contrast agent used was based on organic structure temperature

demand to take particular protection and be qui vive of extra hazards that can be derived as terrible cardiovascular disease, terrible nephritic damage, asthma or a history of allergic reactions, suspected a high sensitiveness of I, a really old ( & A ; gt ; 65 old ages ) and really immature ( & A ; lt ; 6 months ) , terrible respiratory diseases, diabetes and had suffered a reaction to the medicine.