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(123I)-MIBG SCAN 

iodine-123-meta-iodobenzylguanidine is injected and special gamma cameras finds or confirms the presence of neuroendocrine tumors. I-123 MIBG scintigraphy is used as screening procedures for suspected carcinoid tumors, evaluation of the adrenal medulla for disorders such as medullary hyperplasia in patients at risk of developing medullary disease and is used for diagnostic imaging of medullary thyroid carcinoma. After intravenous administration, there is rapid uptake of MIBG mainly in the liver. Although the uptake in normal adrenal glands is very low, hyperplastic adrenals and tumors have a relatively higher uptake.

 

 

 

 

 

*THYROID STUNNING: Numerous studies have shown that scanning with 131-Iodine in multimillicurie doses before radioablation therapy can stun the thyroid tissue. Stunned tissue then loses its iodine trapping function partially or completely and also temporarily or permanently.

 

*PHOTON FLUX: is just the amount of photons hitting the surface of a cell in a given time (the number of photons per second per square meter).

123 Iodine is a Designer Radioiodine for Thyroid Scanning!

FUTURE DEVELOPMENT

 

Indirect production methods of high-purity 123-Iodine are currently under development. If production were more economical, the potential use of 123-I would soar. In the future, I suspect 123-Iodine will become widely available at affordable prices and patients with thyroid cancers and diseases can truly reap the benefit from its uses.  At this time, the cost is estimated to be 3-4 times higher than 131-Iodine. Iodine-123 has been suggested as an alternate radiopharmaceutical to carry out whole-body scans, as its primary emissions are photons with minimal particulate radiation (which does not cause thyroid stunning and cell injury).

          Advantages                    Disadvantages

  • 159 keV, ideal for detection

  • much greater photon flux

  • gives approximately 20 times the counting rate of 131I for the same administered dose

  • The radiation burden to the thyroid is far less (1%) than that of 131I.

  • canning thyroid metastasis with 123I does not cause stunning because of its low radiation burden.

131-I is more affordable, although you run a risk with many drawbacks as a scanning agent, including the thyroid stunning effect.

WHY USE 123-IODINE over 131-IODINE?

131-Iodine, the “traditional tracer” and 123-iodine have been used for pre-therapy imaging, though the potentials of each are continuously deliberated by nuclear medical professionals. There are incomplete, but substantial, studies that suggest 123-Iodine has superiority to 131 as a diagnostic scanning agent.  When 123-Iodine decays, it releases 159 keV (81% of the time) and that is ideal for camera detection and high quality pictures. Next, 123-Iodine has a much greater photon flux and gives approximately 20x the counting rate of 131 Iodine for the same administered dose. Research has established that the radiation burden to the thyroid is far less than that of its isotope, 131. Upon further investigation, it has also concluded 123 Iodine does not cause stunning because of its low radiation.

 

Although 123-Iodine has been restricted by its elevated cost and restricted availability, many believe the difference in the cost is reasonably small considering the entire cost of the whole-body scanning procedure.

FOOD SOURCES OF IODINE AND DAILY INTAKE

Great food sources for iodine is the following: Sea Vegetables, beans, strawberries, prunes, bananas, potatoes, bread, flour, yogurt, cheese and milk.

Iodine intake in the United States range from 138 to 353 mcg/day across all age and gender groups . If a person's iodine intake falls below approximately 10–20 mcg/day, hypothyroidism occurs. 

Historically, iodine deficiency was found across the United States due to a lack of iodine found in the soil. Thanks to a more national food supply, iodized salt and other factors, iodine deficiency is now uncommon in North America. Unfortunately, iodine deficiency remains a public health problem in 47 countries and about 2.2 billion people!

The list of non-medical uses is astounding. The following are percentagesfor end uses of Iodine, based on a researching group in the year 1999. Sanitation (45%); animal feed (27%); pharmaceutical (10%); heat

catalyst (8%); stabilizers (5%); and other (5%) (USGS 1999). Other smaller uses included inks and

colorants, photographic chemicals, laboratory reagents, production of batteries, high-purity metals, motor

fuels, and lubricants.

 

 

DIAGNOSTIC TRACER
Radioactive 123-Iodine is absorbed by the thyroid gland and used to produce the hormones thyroxine just as if it were regular iodine. Paired with the ability to locate the radioisotopes in the body can be readily detected, making useful diagnostic and therapeutic medical applications. In diagnostic uses, radioisotopes are used as tracers to track progress through the body or view localization in specific organs.  
 
DaTscan FOR PARKINSON'S
In 2011, the FDA approved the use of DaTscan, which is an ioflupane iodine-123 injection. It is a contrast agent using SPECT that helps doctors determine how much dopamine is available in a person's brain, as it measures the amount and location of the drug in the brain. The results of a DaTscan can be used to help rule out other diseases that may have similar symptoms present an inconclusive or confusing diagnosis. What an awesome tool to have when facing uncurable diseases like Parkinson's.

 

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123-Iodine compared to 131-Iodine

The Journal of Nuclear Medicine has agreed:

"iodine-123 is an ideal agent

as it has a half-life of just 13.2 hours and provides only a low radiation dose, so it can be safely injected into patients in large quantities. Iodine-123 emits gamma radiation and is used in two radiopharmaceutical substances: sodium iodine-123 and labeled MIBG"

FANTASTIC TRACER ISOTOPE: SODIUM IODIDE I 123 (Na123I)

The thyroid scan and thyroid uptake provide essential information. Radiation that is emitted by iodine can be detected from outside the body to gain valuable information about a patients thyroid size, shape, structure, function and position. Pictures are taken to determine the size and location of thyroid tissues. The thyroid uptake is performed to evaluate the function of the gland. The lower dose (3.7 MBq) is recommended for uptake studies and the higher doses (11.1-14.8 MBq) for thyroid scintigraphy.Radioactive Iodide is also safe to use in individuals who have had allergic reactions to seafood or X-ray contrast agents. RAI is given by mouth in the form of pill or liquid form. 

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