ROCM

• RADIOPAQUE CONTRAST MEDIA - High density pharmacologic agents used to visualize low contrast tissues in the body such as vasculature, kidneys, GI tract and biliary tree\
• Most frequently prescribed ROCM- iodine and barium
• RADIOPAQUE CONTRAST MEDIA - Available in parenteral and enteral, ionic and non ionic, low osmolality and high osmolality forms
• OSMOSIS

  -MOVEMENT OF WATER ACROSS A SEMIPERMEABLE MEMBRANE

  -MEMBRANE MUST BE PERMEABLE TO WATER THAN SOLUTE

  -CONTROLS THE DISTRIBUTION AND MOVEMENT OF WATER BETWEEN BODY COMPARTMENTS
• INTRAVASCULAR RADIOPAQUE CONTRAST MEDIA- USED TO ADD DENSITY TO VASCULAR STRUCTURES
• CATEGORIES:

  1. HIGH OSMOLALITY, IONIC
  2. LOW OSMOLALITY NON IONIC
  3. LOW OSMOLALITY IONIC
• IONIC ROCM - EXIST IN SALT FORMS CONSISTING OF SODIUM AND MEGLUMINE
• NON IONIC ROCM - SUPPLIED AS NON SALT FORMS
• HIGH OSMOLALITY IONIC ROCM - Contain three iodine atoms per molecule and dissociate into two osmotic active particles when injected into the blood stream
• Intravascular Radiopaque Contrast Media - consists of large molecules with molecular weights ranging between 600 to 1700. These molecules possess poor lipid solubility, which means they cannot easily pass through cellular membranes.

  Due to their inability to cross cellular membranes, this are primarily distributed into the bloodstream upon administration.
• The blood-brain barrier, formed by specialized cells lining brain blood vessels, regulates substance passage into the brain to maintain stability. Intravascular Radiopaque Contrast Media (ROCM) are typically unable to cross due to their size and solubility. Though limited, some ROCM may enter the cerebrospinal fluid via the choroid plexus, which produces CSF.
• Contrast enhancement of the brain may require up to 40 minutes for the ROCM to reach the site
• Upon injection, ROCM first opacify the renal parenchyma (the functional tissue of the kidneys). Subsequently, they move through the tubular structures of the kidneys, then into the renal calyces and pelvis, and finally into the ureter and bladder. This process allows for visualization of the entire urinary tract on imaging studies,
• Excretion Timeline: In individuals with normal renal function, 100% of an intravascular dose of ROCM is typically excreted within 24 hours through the urine. However, a very small percentage may also be excreted in the intestines through the hepatobiliary tract (HBT)
• Iodide meglumine - is primarily used as a contrast agent for imaging procedures called cholecystography (imaging of the gallbladder) and cholangiography (imaging of the bile ducts). These procedures help diagnose conditions related to the gallbladder and bile ducts, such as gallstones or blockages.
• After administration, iodide meglumine is mainly eliminated from the body through the hepatobiliary tract (HBT). This means it is excreted via the liver and ultimately ends up in the intestines, where it may be eliminated through the feces.
• Iodide meglumine - is replaced by other Radiopaque Contrast Media (ROCM) due to the advent of safer imaging methods such as ultrasonography and computed tomography (CT). These modern imaging techniques offer non-invasive alternatives for visualizing the gallbladder and bile ducts without the need for contrast agents like iodide meglumine. As a result, the use of iodide meglumine has declined over time in favor of these safer and more advanced imaging modalities.
• Enteric Radiopaque Contrast Media - are substances utilized in medical imaging to diagnose and assess disorders of the gastrointestinal (GI) system. They aid in visualizing the structure and function of the stomach, intestines, and related organs. Additionally, these contrast agents can assist in defining the cardiac shadow, providing information about the size and shape of the heart.
• Forms of Enteric Radiopaque Contrast Media

  • Aqueous Solutions
  • Suspensions
  • Tablets
• Aqueous Solutions


  • Liquid contrast agents typically ingested orally
  • Mix with contents of digestive tract to enhance visibility during imaging procedures such as fluoroscopy or X-ray
• Suspensions


  • Contrast agents consisting of solid particles suspended in a liquid medium
  • Usually administered orally
  • Provide improved visualization of the gastrointestinal tract when ingested
• Tablets


  • Enteric contrast media in tablet form
  • Swallowed and dissolve in the digestive tract
  • Release contrast material to help highlight the structures being examined
• Diatrizoate Meglumine and Diatrizoate Sodium- Used orally and rectally for diagnosing GI tract disorders

  -Preferred when barium sulfate is risky (e.g., GI perforation)

  -High osmolality may cause adverse effects like iodine dilution, diarrhea, hypovolemia, dehydration, and electrolyte imbalance.

  -Preferred over barium sulfate for CT due to fewer artifacts.
• Radiopacity Timing of Diatrizoate Meglumine and Diatrizoate Sodium

  • Immediate radiopacity in the esophagus and stomach post-oral administration.
  • Duodenum visibility may take 15-90 minutes.
  • Immediate radiodensity occurs in the rectum and colon post-rectal administration.
  • Gastrointestinal ROCM remain in the GI lumen and aren't absorbed through the GI wall.
  • Excreted through the GI tract into feces
• Barium Sulfate

  – suspension used for oral and rectal administration to aid in the diagnosis of GI tract disorders

  - generally preferred: provides more thorough visualization of structures (mucosa) without adverse effects

  - may produce significant artifact in CT
• (Suspension)

  BARIUM- Radio dense in the same manner as iodine

  Radio density occurs immediately in the esophagus and stomach after oral administration but may take 15-90 minutes in the duodenum
• Iocetamic Acid - is an oral radiopaque contrast media (ROCM) used specifically for opacifying the gallbladder. This means it's used to make the gallbladder visible on imaging studies such as X-rays or CT scans.

  tablet form - Cholebrine
• After oral administration of the Cholebrine (iocetamic acid) - the gallbladder becomes visible on imaging studies approximately 10-15 hours later.

  -Most of the iocetamic acid is eliminated from the body through urine within 48 hours after administration. Some of it, however, is also excreted via the biliary system into the feces.
• For a regular X-ray film to effectively visualize the vascular system, the ROCM needs to have a serum iodine concentration ranging from 280 to 370 mg/ml. This concentration ensures that there is sufficient contrast between the blood vessels and surrounding tissues to make them visible on the X-ray film.

  -to achieve this high iodine concentration in the bloodstream, the ROCM must contain a large proportion of iodine. Additionally, it needs to be injected directly into the bloodstream (intravascularly) at a rate that matches or exceeds the flow rate of blood.
• CT Scan or Digital Subtraction Angiography (DSA): for more advanced imaging techniques like CT scans or DSA, lower serum iodine concentrations are sufficient. The passage mentions serum iodine concentrations of 2 to 8 mg/ml for these techniques.
• ADVERSE EFFECTS OF ROCM

  OSMOLALITY EFFECTS

  High-osmolality contrast media (HOCM) have a significantly higher concentration of solute particles compared to the blood. When these solutions are injected into the bloodstream, they create an osmotic gradient that draws water from the surrounding tissues into the blood vessels. This sudden shift in fluid balance can lead to dehydration of tissues and alter the osmolality of the blood.
• CHELATION EFFECTS •

  ROCM can chelate ( bind to ) calcium ions in the cardiovascular system after injection

  Can cause - pulseless electrical activity (PEA), cardia arrest, sudden death
• CHELATION EFFECTS

  • Pulseless electrical activity - heart rhythm disturbance characterized by electrical impulses without cardiac contraction

  • Cardiac arrest - sudden loss of blood flow resulting from the failure of the heart to pump effectively

  • Sudden Death – usually the result of a heart rhythm that cannot sustain life
• Anaphylaxis - Type I hypersensitivity reaction which requires a first time exposure to the antigen at some time in the patients’ history
• RENAL DYSFUNCTION

  •ROCM- responsible for 10% of all the acute renal failure (ARF) events and third most common cause of hospital acquired ARF

  • Angiography – 2%

  • IVP – 2-25%

  • Renal Nephropathy - 50-100 %
• DRUGS USED IN RADIOLOGY PATIENTS TO ASSIST IN PREVENTING RENAL DYSFUNCTION

  • Half normal Saline or normal Saline

  • Fenoldopam

  • Acetylcysteine

  • Sodium Bicarbonate