CONTRAST MEDIA - FINALS

• in 1918 Walter dandy - used air to study cerebral ventricles in children with hydrocephalus.

  
  

  this technique is called PNEUMOENCEPHALOGRAPHY (PEG)

  
  

  CARBON DIOXIDE, NITROUS OXIDE AND OXYGEN CAME INTO USE
• Hydrocephalus is a chronic, neurological condition caused by an abnormal accumulation of cerebrospinal fluid (CSF) within cavities of the brain called ventricles, resulting in pressure on the brain
• what do you call this abnormality

  A) dandy-walker malformation

  
• 1896 LEAD SUBACETATE - WAS USED TO STUDY THE DIGESTIVE SYSTEM OF THE GUINEA PIG WHICH LATER PROVED TO BE TOXIC

  WALTER CANNON USED BISMUTH SUBNITRATE IN HIS SERIES OF EXPERIMENTS TO STUDY THE DIGESTIVE SYSTEM
• THOROTRAST - WHICH INCORPORATED THORIUM PROVED TO BE RADIOACTIVE 1910,

  
  

  ARTICLES ABOUT THE ADVANTAGES OF THE INERT (non-reactive in the body) IN INSOLUBLE COMPOUND,

  THIS BEGAN TO APPEAR IN THE MEDICAL LITERATURE BARIUM SULFATE WAS USED RAPIDLY DUE TO LOW TOXICITY , COST AND AVAILABILITY
• 1927 - EGAS MONIZ – HE INJECTED SODIUM IODIDE INTO THE CEREBROVASCULAR CIRCULATION VIA CAROTID ARTERIES WHICH PROVED TO BE A BLOOD VESSEL IRRITANT
• 1930 ATOMS WITH HIGH ATOMIC NUMBERS COULD BE PLACED ON A NON TOXIC WATER SOLUBLE CARRIER MOLECULES
• 1950 - HOW MANY IODONE ATOMS PER CARRIER MOLECULE?

  3
• Why contrast agents are used

  ■ Different tissues within the body attenuate the beam of X-rays to different degrees.

  ■ What is one of the major variables influencing the degree of attenuation of an X-ray beam by an element, considering its complexity, particularly in terms of electron interaction along the beam's path?

  -number of electrons

  ■ The number of electrons in the path of the beam is dependent upon three factors:

  -The thickness of the substance being studied

  - Its density

  - The number of electrons per atom of the element (which is equal to its atomic number)
• CONTRAST MEDIA - AGENTS THAT ARE INSTILLED INTO BODY ORIFICES OR INJECTED INTO THE VASCULAR SYSTEM JOINTS AND DUCTS TO ENHANCE SUBJECT CONTRAST IN ANATOMIC AREAS WHERE LOW SUBJECT CONTRAST EXISTS
• NEGATIVE CONTRAST MEDIA

  ■ RADIO LUCENT

  ■ APPEAR DARK (BLACK) ON RADIOGRAPHS

  ■ COMPOSED OF LOW ATOMIC NUMBER ELEMENTS

  ■ ADMINISTERED AS GAS OR GAS PRODUCING TABLETS, CRSYTAL OR SODA WATER

  ■ AIR, CARBON DIOXIDE, OXYGEN

  ■ RARELY USED ALONE AS CONTRAST AGENT
• POSITIVE CONTRAST MEDIA

  ■ RADIOPAQUE

  ■ APPEAR WHITE ON RADIOGRAPH

  ■ COMPOSED OF ELEMENTS WITH HIGH ATOMIC NUMBERS

  ■ BARIUM SULFATE, IODINATED CONTRAST (2 example)
• MRI - gadolinium diethylenetriaminepentaacetic acid (gadolinium-DTPA)

  -This contrast agent is a metallic and magnetic agent that will affect the signal intensity used to image the anatomic area of interest
• ULTRASOUND - in this radiographic examination, contrast agents are generally gas-filled microbubbles that affect the sound wave to enhance ultrasound contrast.
• DOUBLE CONTRAST STUDIES

  POSITIVE AND NEGATIVE CONTRAST AGENTS ARE USED TOGETHER.

  ■ POSITIVE- COAT THE PART UNDER STUDY

  ■ NEGATIVE- FILLS THE SPACE AND PERMITS VISUALIZATION THROUGH THE GASEOUS MEDIUM (MUCOSAL LININGS ARE WELL VISUALIZED)
• COMMON DOUBLE CONTRAST STUDIES

  ■STOMACH

  CONTRAST AGENT: BARIUM SULFATE, CARBON DIOXIDE AS TABLET, CRYSTALS, OR SODA WATER

  METHOD OF ADMINISTRATION: ORAL

  PATIENT PREPARATIONS: NPO POST MIDNIGHT

  PATIENT INSTRUCTIONS: PATIENT SHOULD NOT BELCH AFTER CARBON DIOXODE HAS BEEN GIVEN

  this examination is called - upper gastrointestinal series
• LARGE INTESTINE

  CONTRAST AGENT: BARIUM SULFATE, AIR

  METHOD OF ADMINISTRATION: RECTAL

  PATIENT PREPARATIONS: FLUID DIET, NPO POST MIDNIGHT, CLEANSING ENEMA (cathartics)

  PATIENT INSTRUCTIONS: PROVIDE SUPPORTIVE COMMUNICATION

  this examination is called - Barium Enema

  this is a Retrograde procedure - (against the flow)
• ARTHROGRAPHY (SHOULDER, KNEE, HIP, WRIST)

  ■ CONTRAST AGENT: WATER SOLUBLE IODINE CONTRAST MEDIA, AIR

  ■ METHOD OF ADMINISTRATION: INJECTION INTO JOINT SPACE

  ■ PATIENT PREPARATIONS: NONE

  ■ PATIENT INSTRUCTIONS: PROVIDE SUPPORTIVE COMMUNICATION
• DESIRABLE FEATURES OF A CONTRAST AGENT

  ■ Easy to administer

  ■ No toxicity/carcinogenicity

  ■ Stable compound

  ■ Concentrates in area of interest

  ■ Proper demonstration of the organ system

  ■ Should have rapid elimination

  ■ Minimal distress to patients (viscosity - thickness of the liquid)

  ■ Cost effective
• BARIUM SULFATE CONTRAST MEDIA

  ■ ATOMIC NUMBER – 56

  ■ INERT POWDER COMPOSED OF CRYSTALS THAT IS USED FOR EXAMINING THE DIGESTIVE SYSTEM

  ■ CHEMICAL FORMULA BaSO4

  ■ NOT SOLUBLE IN WATER, THUS IT MUST BE MIXED OR SHAKEN INTO A SUSPENSION (vegetable gums, flavoring, and sweeteners to increase palatability)

  ■ FLOCCULATION (SODIUM CARBONATE AND SODIUM CITRATE) - tendency to clump
• Small Intestine Studies (small bowel series)

  ■ Oral formulations of Barium Sulfate and methylcellulose

  ■ These preparations give see through effect to better diagnose small lesions
• Lower GI Series

  ■ Barium sulfate mixed with cold tap water for;

  ■ Reduce irritation, aid the patient in holding the enema during the examination

  ■ Reduces spasm and cramping

  procedure is called - barium enema
• INTRODUCTION OF CONTRAST MEDIUM MAY RESULT IN INCREASED WATER ABSOPRTION BY THE COLON LEADING TO EXCESS FLUID ENTERING THE CIRCULATORY SYSTEM (hypervolemia)

  ■ THEREFORE, ADDITION OF 2 TEASPONS OF TABLE SALT PER LITER OF WATER IS APPLIED IN THE ENEMA CONCENTRATION
• BARIUM SULFATE IS CONTRAINDICATED TO PATIENTS WHO DOES NOT ABSORB BARIUM NATURALLY

  ■ BARIUM SULFATE COULD CAUSE PERITONITIS

  ■ WATER SOLUBLE IODINE CONTRAST AGENTS ARE USED IN PLACE OF BARIUM SULFATE
• barium sulfate could cause

  ■ OBSTRUCTION

  ■ PERFORATION (rupture or tear in the wall) OF THE COLON WITH EXTRAVASATION (leakage)

  -this COULD RESULT IN INFLAMMATION OF THE ABDOMINAL CAVITY (BARIUM PERITONITIS)

  ■ OLDER PATIENTS WITH LONG TERM USE OF STEROIDS RISK FOR COLON PERFORATION (rupture or tear in the wall of the colon)

  ■ PATIENTS WITH DIVERTICULITIS AND ULCERATIVE COLITIS – RESULT IN INFLAMMATION AND DEGREDATION OF THE COLON

  ■ PATIENTS WITH TOXIC MEGACOLON SHOULD NOT HAVE LOWER GI PROCEDURES

  
  

  – RUPTURE (breaking)
• Barium sulfate could cause

  barium sulfate/ could cause

  • RECENT BIOPSY OF THE COLON IS CONTRAINDICATED
  • VAGINAL RUPTURE
  • SEDATED PATIENTS SHOULD NOT UNDERGO UGIS EXAMINATIONS; ASPIRATION (yung dapat magsulod sa esophagus magsulod sa bag) can cause (BARIUM PNUEMONIA)
  • MENTALLY HANDICAPPED PATIENTS can cause ASPIRATION
• OSMOLALITY

  ■ MEASURE OF THE NUMBER OF DISSOLVED PARTICLES IN A MEDIUM

  ■ MEASURE OF THE NUMBER OF PARTICLES (MOLECULES, IONS, CATIONS)

  A) solvent

  B) solute

  
• ION - ATOM OR MOLECULE HAVING A NEGATIVE CHARGE OR A POSITIVE CHARGE
• IONIC IODINE CONTRAST MEDIA

  • ATOMIC NUMBER OF IODINE 53
  • DISSOCIATE INTO TWO MOLECULAR PARTICLES IN WATER OR BLOOD PLASMA
  • ANION- NEGATIVE
  • CATION- POSITIVE
• label this

  A) 1- cation

  B) 2- iodine

  C) 3- Anion

  D) 4-iodine

  E) 5-anion

  F) 6- iodine

  
• Anion

  -negative charged ions

  -responsible for detoxifying and stabilizing the contrast

  THERE ARE 3 PRIMARY ANIONS EMPLOYED:

  • DIATRIZOATE
  • IOTHALAMATE
  • METRIZOATE
• CATIONS

  -positively charged ions

  -increases the solubility of the medium
• 2 types of iodine contrast material

  • anions
  • cations
• NON IONIC IODINE CONTRAST MEDIA

  -MOLECULES THAT DO NOT DISSOCIATE INTO ANION AND CATION (NONIONICS) OR IONIC BUT ARE TOO BIG TO HAVE OSMOTIC EFF ECTS (IOXAGLATE)

  -LOWER OSMOLALITY CONTRAST MEDIA

  -MAS PREFFERABLE KAY WALANG ALLERGIC REACTION
• ADVANTAGE OF LOWER OSMOLALITY – HYDROPHILIC (WATER SOLUBLE) WHICH MAKE IT LESS LIKELY TO BE REACTIVE WITH CELLS THAT CAN TRIGGER ALLERGIC EFFECTS
• IOXAGLATE- IONIC MOLECULE COMPOSED OF TWO CONNETED BENZENE HEXAGONS

  IT FORMS DIMER- COMPOSED OF TWO IDENTICAL SIMPLER MOLECULES , LARGE MOLECULES , HIGH MOLECULAR WEIGHTS

  -CARRIES SIX IODINE ATOMS PER MOLECULE

  -IONIC
• IODIXANOL (VISIPAQUE)

  - NONIONIC DIMER

  -ISOMOLAL ( SAME NUMBER OF PARTICLES TO BLOOD PLASMA BY THE ADDITION OF ELECTROLYTES, SMALL ANIONS AND CATIONS WHICH ARE NORMALLY PRESENT IN THE BLOOD PLASMA
• ADVANTAGE OF LOWER OSMOLALITY – HYDROPHILIC (WATER SOLUBLE) WHICH MAKE IT LESS LIKELY TO BE REACTIVE WITH CELLS THAT CAN TRIGGER ALLERGIC EFFECTS
• increase in temperature = decrease in viscocity
• METFORMIN (GLUCOPHAGE) SHOULD BE DISCONTINUED 48 HOURS AND 48 HOURS AFTER THE USE OF CONTRAST MEDIA

  -LACTIC ACIDOSIS MAY DEVELOP