Whole-body magnetic resonance imaging and when it’s needed

Technology & Trends Article 3 Minute Read GE Healthcare Global

There are a number of routine uses for magnetic resonance imaging (MRI). For example, athletic patients may be scanned to assess for ACL tears or patients with dementia, especially Alzheimer’s, may need to be monitored to assess the rate of deterioration of their brain tissue. MRIs can be used for a wide range of reasons in the medical field, including cancer. Oncologists may even use whole-body magnetic resonance instead of imaging a single area of the body.

What is oncology and multiple myeloma?

Oncology is the branch of the medical field that involves the study of cancer. Because cancer is such a wide field and because it may be extremely harmful, patients who are believed to have cancer are typically referred to a cancer center. These cancer centers may have teams of people for the patient to work with, some of whom will work with a patient more closely than others.1 Oncologists are the physicians that specialize in diagnosing and treating cancer. There are three main types of oncologist: medical, surgical and radiation oncologists. Oncologists also supervise the oncology nurse practitioner who may meet with the patient individual and report back to the oncologist. Oncology nurses serve in a variety of different roles and may have specialized certification.

There are a number of different tests that an oncologist may request, including lab work, biopsy, computed tomography (CT) and MRI.1 Each type of test may show a different aspect of the disease. The lab work may be used to look for tumor markers in the blood, urine, or body tissue or to check the levels of different substances in the blood. A biopsy may be taken to examine the cells in the cancerous area. This helps to determine malignancy and possibly diagnose cancer. CT scans may be used to stage cancer, guide biopsy or plan radiation therapy. This particular test involves ionizing radiation. MRI can also be used to stage cancer, guide biopsy or plan radiation therapy, but it does not involve ionizing radiation and is non-invasive.

Magnetic resonance imaging (MRI) involves the use of a super-conducting magnet and pulse sequences to alter the magnetic field around the scanner. As the field changes, it affects the signals emitted by the body, which are used to create MR images. The signals are then transmitted to a computer through the use of a device called a coil. Additional coils may be placed near the body to boost the reception of these signals.

Buyers Guide_950x250.jpg

What is whole-body magnetic resonance imaging used for in oncology?

Whole-body MRI is a useful tool in assessing hematologic or metastatic cancers. Hematologic cancer is cancer that involves blood. This can be easily remembered due to the fact that hemo- or hema- comes from the Greek word for blood and can be found in words like hemophilia or hemoglobin. Metastatic cancer is defined as cancer which has spread into other areas than the original location of the cancer. It is characterized by the fact that it retains the form of whatever cancer the origin was. For example, bone metastases in breast cancer is still breast cancer.

Some examples of hematologic cancer include leukemia, lymphoma and multiple myeloma. Multiple myeloma can be seen as bone lesions even though it is a blood-related cancer. This is due to the fact that the blood originates in the marrow, which is the soft, blood-producing tissue that is found in the center of most bones. For multiple myeloma, MRI has been shown to have a higher sensitivity for early detection of bone lesions compared to both skeletal survery and whole-body low-dose CT.2 Additionally, it may have a higher sensitivity, specificity and positive predictive value than FDG PET/CT.2 This allows radiologists and oncologist to get a more detailed view of possible lesions.

Oncologists may use a whole-body MRI to scan for metastatic cancer in a variety of different patients. This is due to the chance that the cancer may spread to the bone. Whole-body MRI may have a higher positive predictive value and greater sensitivity compared to bone scintigraphy, or bone scan, for the detection of bone metastases.3 Scans conducted to check for metastases may require the use of diffusion-weighted imaging (DWI), which is a technique that can be used during MRI. DWI measures the random motion of water molecules to determine the tissue structures in the body. This technique may be useful for detection of lesions, especially those in pediatric patients.3

Cancer patients may have to have a whole-body MRI scan to stage and monitor hematologic cancers, especially multiple myeloma, or to assess possible bone metastases. This scan may have an advantage over other imaging methods for imaging these cancers. Because of this, oncology assessment may be added to the long list of uses for MRI.

References

1. ASCO. “Cancer Basics.” Cancer.Net. Web. 2 April 2019. <https://www.cancer.net/navigating-cancer-care/cancer-basics>.

2. Mario Morone, et al. “Whole-Body MRI: Current Applications in Oncology.” American Journal of Roentgenology. 2017; 209: W336-W349. Web. 27 March 2019. doi: 10.2214/AJR.17.17984.

3. Marcos Duarte Guimarães, et al. “Whole-body MRI in pediatric patients with cancer.” Cancer Imaging. 10 February 2017; 7: 6. Web. 27 March 2019. doi: 10.1186/s40644-017-0107-7.