Human error can be a factor in any medical diagnosis — even for highly trained experts and involving something as black and white as an MRI. Studies show that there may be a two per cent error rate in MRIs of the spine. The most common mistake is to label something as being on the right side when it was on the left.
With MRIs of the lumbar spine, it’s also possible to mislabel the level of the involved segment. Many times this is because there is an extra or transitional vertebra making it difficult to count the sements.
Efforts are being made to guide physicians in labeling MRIs of the spine consistently no matter who reads them. Orthopedic surgeons and other spine specialists have agreed that describing disc problems should be standardized. Several groups have proposed terms to describe disc pathology such as bulging, protrusion, extrusion, and sequestration.
The American Society of Spine Radiology, American Society of Neuroradiology, and the Combined Task Force of the North American Spine Society are included in the groups advocating the standardization of terms. Recent studies indicate that many times radiologist don’t describe the morphology at all. In cases where both the attending physician and the radiologist read the MRIs and described the abnormal disc, the clinician (attending physician) was more likely to give it a higher grade indicating a more severe progression of disease than the radiologist would give it.
For example, the examining physician would label the morphology as a disc extrusion when the radiologist would call it a protrusion. In cases where the radiologist didn’t see a herniation, the morphology was labeled as a bulge. The attending physician would interpret that as a herniation.
The reason for this difference in categorization may be because the clinicians are influenced by knowing the patient’s symptoms. It’s also possible that differences in training account for differences in the way clinicians interpret lumbar MRIs.
Labeling the side of involvement incorrectly (e.g., saying it was on the right when it was really on the left) can affect treatment and result in a less successful response than hoped for — sometimes even sending the patient to surgery when conservative care failed to resolve symptoms. Operating on the wrong side is also possible with misinterpreted MRIs.
Anyone reading MRIs (even experienced radiologists) can make this mistake. You are fortunate that your surgeon has a good standard practice to guard against this by reviewing the records for each individual patient.