Gadolinium Based Contrast
Contrast agents occur as one of the pharmaceutical products that increase the visibility of the data contained in diagnostic magnetic resonance imaging (MRI). Furthermore, the contrast agents play a significant role in improving the specificity and sensitivity of diagnostic images during the MRI scans by techniques of interfering with properties of the tissue hence impacting the vital mechanism of contrast. In most cases, the MRI occur as unique in the diagnostic imaging technologies based on facts that it uses more than one intrinsic properties of the tissues under imaging. Moreover, the gadolinium-based contrast agents (GBCA) occur as the chemicals injected in the body, which enhances and improves the quality of the image while using MRI scans. Equally, the gadolinium contrast agents comprise complex molecules as well as patterns of the atoms held together by chemical bonds which maintain its stability. Notably, using GBCA in MRI scanning of tissues in patients under different conditions requires to follow various policies and precautions as stipulated by multiple organizations such as Food and Drug Agency (FDA). The ways of administration of GBCA differ; hence they can be administered through injection or oral depending on the patients and tissue of imaging. Gadolinium contrast media contain various effects on the image and the tissue. It improves the quality of the image produced, and when accumulated in the body, it could result in multiple negative impacts on the tissues. The use of GBCA possesses diverse effects on patients with GFR and could result in nephrogenic systemic fibrosis in the individuals have various kidney problems.
Policies on Gadolinium Contrast Agents in MRI
The policies offer the guidelines for the radiologist to perform safe, effective and quality MRI scanning while using the GBCAs. As per iFood and Drug Administration (2018), the qualification of the patients should occur as the first step by radiologist through the examination of the individuals. Going through the patient medical history occur as mandatory for the radiologist to identify any adverse reaction towards such chimerical or allergies hence making the necessary recommendations (Food and Drug Administration, 2018). Moreover, polices requires that lactating mother should have various discussions with the radiologist before administering GBCAs. b, GBCAs are not recommended for pregnant women unless they possess an extreme condition that requires an urgent MRI scan using these media (Food and Drug Administration, 2018). For instance, FDA policy indicates that use of the intravenous gadolinium-based contrast agents explains that administering radiologist should check the history of an allergic reaction related such medication before administration and consider some exceptional cases like children, lactating mothers and pregnant women (Food and Drug Administration, 2018). The general policy explains that department dealing with MRI scan should possess a trained healthcare provider who can offer emergency or long term recognition and treatments of the severe contrast reactions. Notably, the patent should never be left alone after administration of the GBCAs and facility for treating acute contrast reactions should be readily available for handling such cases (Food and Drug Administration, 2018). Similarly, the patient should always access information and get informed about the entire procedures and possible outcomes. FDA approved brand of gadolinium-based contrast agents (GBCA) such as gadodiamide, gadobenate dimeglumine, and gadoversetamide as well as gadopentetate dimeglumine, to name a few.
Gadolinium Contrast Media
The gadolinium contrast media used in MRI scan contains complex molecules held together by chemical bonds in their atoms. According to Ariyani et al. (2018), The chemical bond found in these media form as a result of interaction between the gadolinium ion and carrier molecule, also known as the chelating agent. Notably, the chelating agent performs one fundamental function of prevention of the gadolinium toxicity and maintaining the properties of its contrast at the same time (Gale et al., 2017). Moreover, multiple brands of the gadolinium agents employ various chelating molecules. In most cases, administration of the GBCAs occurs as intravenous during the MRI scan and removed from the body by the kidney. Nevertheless, oral administration could occur more so when conducting the MRI scans on the gastrointestinal tract. Gadolinium contrast medium significantly assists in the increasing accuracy of the MRI scan as well as improving the quality of the images (Ariyani et al., 2018). For instance, GBCAs improves the visibility of tumors, organs, blood vessels and inflammations.
The difference in Contrast Medium
MRI oral contrast agents occur as the most appropriate for the gastrointestinal track scans. Such agents originate from natural prepared fruits such as green, medlar and blueberry. Moreover, artificial oral contrast agents are made from artificial material such as gadolinium, manganese (II) and (III) as well as iron (III) (Shokrollahi, 2013). Equally, ionic intravenous contrast medium includes the Gd combined with ethylenediaminetetraacetic acid (EDTA). Notably, intravenous contrast medium comprises the chelates originating from paramagnetic ions which include nonionic and ionic (Food and Drug Administration, 2018). They get confined to the particular tumor and blood pool.
Benefits of Gadolinium-Based Contrast Agents
Administration of the gadolinium contrast agents acts as a significant factor in improving the diagnostics accuracy of the MRI scans. GBCAs enhances the diagnosis of infectious and inflammatory conditions like spine, bones, soft tissues and brain hence offering the radiologist with a clear vision of the problem (Kobi et al., 2028). For instance, the nature of some types of cancer tumours gent viewed clearly by the radiologist after administration of the GBCAs. The gadolinium contrast media offers significant benefits in assessing the heart abnormalities as well as indicating the functioning of the blood vessels in real-time.
GBCA magnetic and ionic properties and effects on imaging
The contrast agents used in the MRI scanning occurs in two distinct groups based on the magnetic properties such as paramagnetic gadolinium ion complexes or superparamagnetic, which consist of the magnetite particles. The paramagnetic media using originates from the Dysprosium (Dy3+), transition metal such as manganese (Mn2+) or lanthanide metal gadolinium (Gd3+)( Ariyani wt al., 2018). Moreover, most of the manufacturers used the lanthanide ion gadolinium (III) due to its critical properties such as its stable ion nature since it possesses unpaired electrons and high magnetic moments. According to Xiao et al. (2016), the gadolinium (III) holds characteristic such as weakly bounding to the serum hence easily displaced by the ligands. The gadolinium (III) uses various chelates that give it different ionic properties. For instance, the ionic gadolinium contrast agents comprise gadolinium (III) diethylenetriamine pentaacetate also referred to gadopentate dimeglumine and gadoterate and polyaspartate (Gale et al., 2017). Such ionic forms of gadolinium occur as hydrophilic complexes. Moreover, the nonionic, as well as hydrophilic compounds of gadolinium (III), include the methylamide, gadodiamide and gadoteridol (Xiao et al., 2016). However, some of the gadolinium complexes exist as both ionic and lipophilic such as gadobenate dimeglumine and gadoxetate.
Most of the paramagnetic contrast medium exists as positive agents hence imposing the same impact on the T1 and T2 imaging procedures. Moreover, paramagnetic ones possess effects on T1b tissues, therefore, higher than T2. As a result, the tissues absorbing these agents occurs as brighter on T1 images as compared to T2 ones (Xiao et al., 2016). On the other hand, GBCA such as ferromagnetic and superparamagnetic persist as the negative medium which holds reduction effects of T2 signal due to restriction of the T2 relaxation time (Xiao et al., 2016). Notably, such agents can get converted to T1 ones based on their coating and size of their particles. Generally, paramagnetic contrast media of GBCA occur as positive agents hence impacting the same outcome on the T1 and T2 imaging.
Precautions
All the patients receiving the GBCA administration for the first time should receive a medication guide hence possessing critical, required information. Despite the existence of the data on the use of the GBCAs on pregnant, most of the institutions and organization cautions the healthcare providers not to administer these agents on pregnant women unless the conditions of the patients require such media (Kobi et al., 2019). Moreover, breastfeeding mothers’ administration of the GBCAs requires discussion and permission by the radiologist in charge. On the same note, the cessation or continuation of breastfeeding should be 24 hours in which it should be communicated to the mothers, which involve consultation with the clinician (Food and Drug Administration, 2018). Such interaction should aim radiologist informing the patient about the risks and benefits of undergoing GBCAs administration. On the same note, radiologist and clinicians should take the precaution of monitoring the patient after the injection for at least 15 minutes (Food and Drug Administration, 2018). Equally, caution should be taken while dealing with allergies in which doctor could track the medical information to specify any allergies or contraindications related to the patients and GBCAs. The radiologist should take precaution on the patients with a documented allergic reaction such as asthma or the chronic obstructive pulmonary disease (Food and Drug Administration, 2018). Similarly, various precautions should be taken into considering while dealing with various renal disorders or impairments. Such patients could result in acute kidney injuries if precautions are not observed. Nevertheless, radiologists should take precautions while dealing with patients who have renal failure, which can result in conditions such as nephrogenic systemic fibrosis.
According to the Food and Drug Administration (2018), various studies indicate different impacts of GBCA on the brain tissues due to accumulation resulting from repeated injection during the MRI scans on the head. As per the Food and Drug Administration (2018), deposition also occurs in parts of the cerebellar cortex while those deposited in cerebellum occurs in both insoluble and soluble forms. High deposition never directly affects body tissues, but studies indicate that they interfere with a function such as actions of the thyroid hormones which plays a crucial part in the development of cerebellar (Ariyani et al., 2018). The cases of deposition of GBCAs are high in liver, spleen tissues and kidney. Moreover, various studies indicate that accumulation of the compounds from gadolinium accumulates in the liver, which causes necrosis and apoptosis as a result of damages caused in the hepatocytes.
Gadolinium-based Contrast Agents Use and NSF Diseases
Nephrogenic systemic fibrosis (NSF) persists as uncommon conditions. NSF comprises the development of fibrous plaques in the dermis, which includes the deeper connective tissues. Moreover, the reported cases happen in the patients experiencing severe renal injuries, disorders or impairment. Woolen et al. (2010) explain that NSF results from uncontrolled or not taking in precautions in a while using the GBCAs media in MRI which could lead to the death of the individuals since currently, the situation lacks accurate drug for medication. As per Woolen et al. (2020), different studies indicate an association between nephrogenic systemic fibrosis (NSF) and the use of Gadolinium-Based Contrast Agents more so in patients with kidney disorders. In most cases, the risks of the NSF depends on the stage of the chronic kidney diseases with low chances in sate for and five of CKD while administering group II GBCA (Food and Drug Administration, 2018). For the patients under dialysis, the process should continue on the same day of GBCA administration which reduces the risk of the NSF. Moreover, patients with mild and moderate renal impairments can use GBCA without significant risks of NSF (Woolen et al., 2010). However, NSF cases could occur in any patient with both acute and chronic renal failure or impairment and chronic kidney disease more in the stages such 4 and 5 which possess glomerular filtration rate of ˂30 ml/min/1.73 m2 (Kobi et al., 2018). Some of the brands that possess high chances of causing NSF to persist as gadodiamide, gadopentetate and gadoversetamide. Some of the studies indicate that fibrocytes derive from the bone marrow occurs as pathogenesis of the NSF (Woolen et al., 2020). Such abnormal behaviors get triggered by the outcomes of loss gadolinium from the agents used in chelating media.
Gadolinium retention
Recent investigation indicates that a small amount of the GBCAs gets retained in the tissues and brain for a more extended period after the administration. In most cases, the retention happens in the globus pallidus and cerebellar dentate nucleus (Ramalho et al., 2016). Furthermore, retention could occur in the skin as well as bone marrow (Ramalho et al., 2016). The high rates of retention exist in the less stable chelates of the gadolinium agents. Moreover, the retention rate persists as higher in patients with renal, failure, disorders or impairment as compared to healthy individuals.
GBCA Side Effects
Side effects occur in the minority of patients after GBCA administration and the time of showing these impacts would differ based on the adverse outcomes. For instance, dizziness, headache and nausea would happen within a few minutes of injection or oral administration (Practic, 2018). Furthermore, use of the GBCAs has adverse allergic reactions which occur within several minutes of administration while the patients are still in the healthcare facilities. According to Practic (2018), such reactions allergies could result in sweating, rashes on the skin, facial edema, eye irritation and pain as well as taste abnormalities. On the same note, administration of the GBCAs in MRI could result in hypertension, syncope, pallor and tachycardia depending previous health conditions of the patient (Practic, 2018). Nevertheless, GBCAs causes various gastrointestinal adverse effects, such as abdominal discomfort and pain, fever, and vomiting (Practic, 2018). However, GBCAs have different side effects on the nervous system such as thirst, anxiety, loss of consciousness and paresthesia.
Conclusion
Gadolinium-based Contrast Agents plays a significant role in enhancing the quality of the image in MRI scan despite having many policies and precautions while administering to various categories of patients under diverse medical conditions. Moreover, the FDA and other healthcare institutions have multiple policies to be followed while using the GBCAs in patients with different conditions. Furthermore, gadolinium contrast media used in MRI scan contains complex molecules held together by chemical bonds in their atoms. Equally, The chemical bond found in these media form as a result of the interaction of gadolinium ion and carrier molecule, also known as the chelating agent. GBCAs contain various ionic and nonionic characteristic, but they get categorized mainly as paramagnetic gadolinium ion complexes or superparamagnetic. However, the radiologist must take precautions while handling patients under some condition such as pregnant women, lactating mothers, children and individuals with renal failure, impairment or injuries as well as those with acute and chronic kidney disorders. GBCAs offer various benefits in the healthcare system by improving image quality and diagnostics accuracy. Notably, the gadolinium-based agent’s usage in patients experiencing severe renal injuries, disorders or impairment could result in NSF cases. Therefore, Gadolinium-based Contrast Agents play a critical role in improving the image in MRI scans despite having various policies and precautions during their administration, depending on the health conditions of the patients.
References
Ariyani, W., Khairinisa, M. A., Perrotta, G., Manto, M., & Koibuchi, N. (2018). The Effects of Gadolinium-Based Contrast Agents on the Cerebellum: from Basic Research to Neurological Practice and from Pregnancy to Adulthood.
Food and Drug Administration. (2018). FDA drug safety communication: FDA warns that gadolinium-based contrast agents (GBCAs) are retained in the body; requires new class warnings.
Gale, E. M., Caravan, P., Rao, A. G., McDonald, R. J., Winfeld, M., Fleck, R. J., & Gee, M. S. (2017). Gadolinium-based contrast agents in pediatric magnetic resonance imaging. Pediatric radiology, 47(5), 507-521.
Xiao, Y. D., Paudel, R., Liu, J., Ma, C., Zhang, Z. S., & Zhou, S. K. (2016). MRI contrast agents: Classification and application. International journal of molecular medicine, 38(5), 1319-1326.
Shokrollahi, H. (2013). Contrast agents for MRI. Materials Science and Engineering: C, 33(8), 4485-4497.
Ramalho, J., Semelka, R. C., Ramalho, M., Nunes, R. H., AlObaidy, M., & Castillo, M. (2016). Gadolinium-based contrast agent accumulation and toxicity: an update. American Journal of Neuroradiology, 37(7), 1192-1198.
Practic, E. (2018). Immediate allergic reactions to gadolinium-based contrast agents: A Systematic Review and Meta-Analysis1. Radiology, 286, 471-482.
Kobi, M., Scheinfeld, M. H., Sprayregen, S., & Dym, R. J. (2018). Contrast controversies and confusion.
Woolen, S. A., Shankar, P. R., Gagnier, J. J., MacEachern, M. P., Singer, L., & Davenport, M. S. (2020). Risk of nephrogenic systemic fibrosis in patients with stage 4 or 5 chronic kidney disease receiving a group II gadolinium-based contrast agent: a systematic review and meta-analysis. JAMA Internal Medicine, 180(2), 223-230.