For many years, magnetic resonance imaging (MRI) has produced qualitative imaging. The technique provided excellent visual detail, and radiologists could provide estimates for quantitative assessments. However, both the visual detail and the quantitative assessments relied heavily on the radiographer conducting the exam and the radiologist reading the images. This information may not have been consistent or reproducible enough for long-term studies. With the addition of helpful software programs and artificial intelligence, MRI has seen a shift to more quantifiable imaging that can further elevate radiology.
What is the difference between qualitative and quantitative magnetic resonance imaging?
Qualitative imaging and quantitative imaging can overlap in some ways. They can both be obtained in the same scan and image. They often are measured simultaneously, and one may even affect the other. For example, if the image has a lower quality, then the quantification may be hindered by the image. There is a difference between the two that must be understood, however.
Qualitative imaging is a way of looking at MR images and assessing disease. This perspective looks at the quality of the organ or tissue being imaged and determines abnormalities. It helps to characterize the tissue in a certain area, whether it is benign or malignant. Qualitative assessment may be used in neurology, for example, to monitor the effects of dementia on brain tissue. In dementia cases, brain tissue may atrophy, or deteriorate, leaving gaps in previously occupied areas.1
Quantitative imaging assesses images in a way that provides more numerical outputs. It measures the size of a tumor or fracture. In some cases, it may also help determine whether a fracture is benign or malignant.2 This information can be used to compare new scans to older ones, possibly monitoring disease progress and reaction to therapy.
How does improved quantification elevate radiology?
Quantitative imaging currently helps to provide more actionable and consistent information for one-time and longitudinal assessment. Before the new technology came along, this data was obtained by radiologists, which meant it could be subjective. One radiologist could have measured differently than others. Since the introduction of these software programs, the data can be obtained using the computer, which eliminates some of the variability.
Dr. Reda Darweesh from the Darweesh Scan Center in Alexandria, Egypt, has experienced the improvements in quantification first hand.3 In the case of a patient with multiple sclerosis and a worsening of symptoms, the MR exam showed the same lesion volume and location. Upon further investigation, the measurement showed a reduction in the volume of total grey matter.3 This change was not able to be seen with the naked eye, and the measurement prompted the physician to change the patient's treatment. Thus, the MR exam provided more personalized care.
The increased accuracy and consistency of quantification may continue to push toward precision health, elevating radiology along the way. The computer may allow for the measurements to be more consistent. Ultimately, this could enable long-term monitoring and show the changes caused by disease, without having to rely so much on the radiologist reading the scan.
For more information from Dr. Reda Darweesh, please read SIGNA Pulse "Advanced neuro imaging propels leadership of Darweesh Scan Center across North Africa and the Middle East."
1. Mina Park and Won-Jin Moon. "Structural MR Imaging in the Diagnosis of Alzheimer's Disease and Other Neurodegenerative Dementia: Current Imaging Approach and Future Perspectives." Korean J Radiol. November-December 2016; 17(6): 827-845. Web. 4 April 2019. doi: 10.3348/kjr.2016.17.6.827.
2. "Tobias Geith, et al. "Comparison of Qualitative and Quantitative Evaluation of Diffusion-Weighted MRI and Chemical-Shift imaging in the Differentiation of Benign and Malignant Vertebral Body Fractures." AJR. November 2012; 199: 1083-1092. Web. 4 April 2019. <https://www.ajronline.org/doi/pdf/10.2214/AJR.11.8010>.
3. Reda Darweesh. "Advanced neuro imaging propels leadership of Darweesh Scan Center across North Africa and the Middle East." SIGNA Pulse. Spring 2018. Web. 4 April 2019. <http://www.gesignapulse.com/signapulse/spring_2018/MobilePagedReplica.action?pm=2&folio=32#pg32>.