Feature article

Trends of MR in the U.S.A.

The trends of magnetic resonance imaging (MRI) may often occur because of a need within the market. The latest changes in magnetic resonance in the U.S. are underway to answer a need within the market. Some of the challenges that MR radiologists face include the fact that about 30% of patients undergoing MRI experience anxiety reacts and that roughly 20% of all MR exams require a repeated sequence.1,2 The trends addressing these and other issues provide a chance to address the need for contrast-free imaging, decrease scan times across the board and allow for imaging in more situations.

Contrast imaging

In 2018, about 36% of MR procedures used contrast.1 Some studies have shown that the contrast used for magnetic resonance imaging (MRI) may be retained for a period of time after being scanned.3 The basis for this contrast is gadolinium. Patients with abnormal kidney function should avoid having an MR scan using a GBCA to minimize the risk of nephrogenic systemic fibrosis.4 In some rare cases, allergic reaction to GBCAs may occur. Contrast enhanced MRI does not expose the patient to radiation like CT and PET scans do.

Although gadolinium retention is not currently associated with adverse reactions, researchers have been searching for ways to reduce the need for GBCAs during MRI scans. One group of researchers found that imaging produced with less gadolinium may be obtained with the same quality as normal dose contrast enhanced images when paired with deep learning techniques, sometimes referred to as machine learning.5 More research into this theory is underway, but machine learning techniques have already begun assisting radiologists in their work.

Scan times

Another strong trend that can be seen in radiology in the United States comes from the need to reduce scan times. MRI scans can take a while to complete, because the computer has to collect an ample amount of data in order to produce clear images. About 20% of all MRI exams require a repeated sequence that require roughly 10% additional time.2 Not only would shorter scan times improve the patient experience by reducing the amount of time the patient has to lie still, it would also help radiology departments complete more scans in a day.

Some abbreviation techniques that are used to shorten MR scans are compressed sensing, parallel imaging and fast spin echo scans. These techniques enable the faster scans that MR departments desire without sacrificing the the adequate image quality necessary for excellent images. Alongside the acceleration techniques, research is being conducted into speeding up MRI by using machine learning from millions of images.6

Sports injuries

Recognition does not seem to be an issue for MRI in America, since many injuries to professional athletes are being evaluated by MRI. Numerous sports injuries can be assessed using MRI, including injuries to the soft tissue, sprains, strains and tears. As a result, some companies have partnered up and are working to achieve better scanning and treatment planning for these injuries.

One collaboration with the National Basketball Association (NBA) has led to a large variety of research. University of Wisconsin School of Medicine and Public Health, for example, has been researching methods to identify potential risk factors for hamstring (a muscle in the back of the thigh) injury through ultrasound and MRI exams.7 This study could lead to a better understanding of what causes the injuries as well as how to prevent and treat them.

Pain imaging

Recent advances in PET/MR have led to advances in a relatively unexplored area: pain imaging. This specialty focuses primarily on understanding chemical changes that occur when a patient is in pain. These chemical changes occurred in the areas causing the pain, and the research team was able to see an increase in the absorption of the PET/MR contrast agent.8 The research was conducted on a small study of only nine patients with chronic conditions and five healthy controls, so additional research is needed. However, this study may lead to insight about the body's reaction to pain.

Conclusion

Magnetic resonance imaging is an excellent, non-invasive form of medical imaging that can be done with or without contrast. In some cases, contrast is necessary, but it is often associated with little risk. MRI provides an alternative to CT and PET exams that expose patients to ionizing radiation when used. One of the complaints about MRI imaging, the length of the exam, is being improved through the research that is being done in the United States and around the world. This type of exam can provide additional information about the risk and treatment of many injuries, including those that occur during athletics, as well as assisting physicians in understanding their patients' pain.

References

  1. Reduction of anxiety during MR imaging: a controlled trial. Magn Reson Imaginghttps://www.ncbi.nlm.nih.gov/pubmed/10745145. Last accessed June 26, 2019.
  2. Toward Quantifying the Prevalence, Severity, and Cost Associated With Patient Motion During Clinical MRI Examinations. JACRhttps://www.jacr.org/article/S1546-1440(15)00144-1/abstract. Last accessed June 26, 2019.
  3. FDA Drug Safety Communication: FDA warns that gadolinium-based contrast agents (GBCAs) are retained in the body; requires new class warnings. FDA.govhttps://www.fda.gov/drugs/drug-safety-and-availability/fda-drug-safety-communication-fda-warns-gadolinium-based-contrast-agents-gbcas-are-retained-body Last accessed June 26, 2019.
  4. FDA Drug Safety Communication: New warnings for using gadolinium-based contrast agents in patients with kidney dysfunction. FDA.govhttps://www.fda.gov/drugs/drug-safety-and-availability/fda-drug-safety-communication-new-warnings-using-gadolinium-based-contrast-agents-patients-kidney. Last accessed June 26, 2019.
  5. Deep learning enables reduced gadolinium dose for contrast-enhanced brain MRI." Journal of Magnetic Resonance. doi: 10.1002/jmri.25970. Last accessed June 25, 2019.
  6. Facebook and NYU School of Medicine launch research collaboration to improve MRI. code.fb.comhttps://code.fb.com/ai-research/facebook-and-nyu-school-of-medicine-launch-research-collaboration-to-improve-mri/. Last accessed June 25, 2019.
  7. UW Teams Up with NBA and GE Healthcare to Study Hamstring Injuries. University of Wisconsin - Madisonhttps://obe.wisc.edu/uw-teams-up-with-nba-and-ge-healthcare-to-study-hamstring-injuries. Last accessed June 25, 2019.
  8. 18F-FDG PET/MRI in Chronic Sciatica: Early Results Revealing Spinal and Nonspinal Abnormalities. Journal of Nuclear Medicinehttp://jnm.snmjournals.org/content/59/6/967.full.pdf+html. Last accessed June 25, 2019.