MRI Equipment, Protocols, and Radiologists’ Expertise May Create Variability in Imaging Quality
Commentary by Richard J. Herzog, MD, FACR and Peter G. Whang, MD, FACS
In an examination of the variability in quality of magnetic resonance imaging (MRIs) in the diagnosis of spine disorders, Richard J. Herzog, MD, FACR, identified 3 factors that can contribute to the accuracy and diagnostic utility of MRIs: 1) the type of imaging equipment used, 2) imaging protocols, and 3) expertise of the radiologist. The report was published in the October 1 issue of The Spine Journal.
“The factors identified in [this review] reflect whether or not the study was performed under the optimal conditions necessary for correctly diagnosing the patient,” said Richard J. Herzog, MD, Director of Spinal Imaging, and Chief of the Division of Teleradiology at the Hospital for Special Surgery. “For any disease or injury, accurately arriving at the correct diagnosis is paramount to formulating the proper treatment plan. If the diagnosis is incorrect, then the treatment may be ineffective and result in a poor outcome for the patient,” Dr. Herzog said.
“In the past, our decision making process as to where our patients get their MRI studies was largely determined by things like cost or convenience; however, as Dr. Herzog points out, it is clear that the variability in MRI quality inevitably affects the diagnostic accuracy of these studies, our treatment decisions, and ultimately patient outcomes,” commented Peter G. Whang, MD, FACS, an Associate Professor of Orthopaedics and Rehabilitation at the Yale University School of Medicine in New Haven, CT.
High-Field MRI May Improve Detection of Pathology
Use of high-field MRI allows for improved spatial resolution in part because of thinner slice sections, higher scan matrices, and faster scan times that reduce the impact of motion. While low-field MRI may be adequate to diagnose disorders such as spinal stenosis or central disc herniations, Dr. Herzog noted that this equipment may not have adequate resolution to diagnose such conditions as small sequestered disc fragments and foraminal or extraforaminal disc herniations; small synovial cysts; compression of conjoined nerve roots; detecting early stages of inflammatory or infectious spondylitis; leptomeningeal pathology; and assessment of tumor infiltration.
Optimal Imaging Protocols Facilitate Detection of the Pain Generator
In addition, poor imaging protocols, including the suboptimal section thickness and imaging planes, as well as lack of training and experience among radiology technologists may contribute to inaccurate readings, Dr. Herzog said. He suggests using stacked axial sequences (taken perpendicular to the spinal central canal) that cover from T12–L1 to L5–S1 to completely assess the entire spine and the paraspinal tissues.
He added that a fat-saturated sagittal sequence is necessary to detect a stress reaction, some fractures, and early tumor infiltration. A coronal sequence is routinely performed at his institution to visualize the relationship of spinal pathology to the adjacent nerves, which may aid in the determination of the optimal surgical approach for removal of a foraminal disc herniation and facet cyst aspirations or rupture, Dr. Herzog said.
Subspecialization of Radiologists Improves Accuracy of Diagnosis
Radiologists lacking subspecialized training and experience with spine cases may misdiagnose conditions, even with the best MRI technology and imaging protocols, Dr. Herzog noted. He added that his experience in musculoskeletal radiology fellowship training programs shows that radiologists have “markedly superior” diagnostic capabilities following the subspecialty training.
“In general, I prefer to have my patients’ MRI studies performed at Yale for the same reasons that Dr. Herzog referred to in his commentary,” Dr. Whang said. “Certainly, the equipment at Yale is state of the art, and I work closely with the musculoskeletal radiologists who read my studies, and I trust them to use protocols that are most appropriate for my patients,” Dr. Whang noted.
“However, when I see patients who either are being seen for the first time who bring in imaging studies obtained at other facilities, I not uncommonly run into the issues that Dr. Herzog described, where the quality of the MRI is just not as good as I would like,” Dr. Whang said.
Dr. Whang added that taking the time to educate patients may help them understand why their physician may recommend a certain imaging facility for their MRI. “The last thing you want to do is have to repeat a study or risk being given a wrong diagnosis that leads to inappropriate treatment. I think most patients will understand the importance of maximizing quality even if, at least initially, it is at the expense of things like cost or convenience,” Dr. Whang said.
Development of MRI Quality Measures
Dr. Herzog noted a lack of objective MRI quality measures, and that quantifying the 3 factors identified in his study may allow for more informed decision making, rather than relying on factors such as price and convenience.
To help fill these gaps in knowledge, Dr. Herzog is embarking on an MRI quality study at Hospital for Special Surgery that is sponsored by the Spreemo Quality Research Institute. The study will involve sending a single patient with back and leg pain to 10 imaging centers and evaluating how the variability in MRI interpretations may impact treatment pathways.
“The study is anticipated to be completed and submitted for publication in early 2016,” Dr. Herzog said. “The study, which is the first of its kind, will demonstrate that MRI is a not a commodity—despite being incorrectly perceived as such. The facility a patient selects for having imaging performed can have a profound impact on whether or not they ultimately get better. This study marks a meaningful first step in the development of evidence-based objective quality metrics, which can help providers and payers make informed referral decisions, and ultimately achieve better outcomes for their patients,” Dr. Herzog said.
“In this era of the Affordable Care Act with limited health care resources, hospitals and surgeons are judged and soon will even be reimbursed based on the quality of care we provide. It follows that imaging centers and radiologists also should be held to the same standards,” Dr. Whang commented.
“I think the challenge for all practitioners in every field of modern medicine is going to be figuring out how we define, identify, measure, and ultimately reward quality care. In the future, we need to establish what actually constitutes a “quality” MRI, and then we have to make sure that we reward radiologists and MRI facilities that consistently deliver higher quality care relative to other centers,” Dr. Whang concluded.