The MRI GOD is struck another blow – interpretation is so variable, the authors states “As a result, the authors conclude that where a patient obtains his or her MRI examination and which radiologist interprets the examination may have a direct impact on radiological diagnosis, subsequent choice of treatment, and clinical outcome.” Now that is a scary prospect.
Spine J. 2017 Apr;17(4):554-561. doi: 10.1016/j.spinee.2016.11.009.
Variability in diagnostic error rates of 10 MRI centers performing lumbar spine MRI examinations on the same patient within a 3-week period.
Herzog R, Elgort DR, Flanders AE, Moley PJ.
- 63 year old lady with l5 sciatica
- “mild weakness in right ankle dorsiflexion 4+/5 and right great toe extension 4
+/5, reflexes were diminished, but symmetrical bilaterally (1/4), and she had a
positive dural tension (seated slump) sign on the right”
- lead author considered expert in his field
- 49 findings 1/3 appeared only appeared once in 10 reports
- Fleiss kappa statistic value used to document agreement:
– 0 = no better than chance
– >0.75 excellent agreement
- “all reported interpretive findings was 0.20±0.03, indicating poor overall agreement on interpretive findings”
- “number of examinations reporting the presence of a disc herniation at a given
motion segment ranged from 70% at L3–L4 to 20% at L5–S1”
- “The number of study examinations reporting thecal sac compression due to a disc herniation ranged from 60% at L1–L2 to only one examination reporting thecal sac compression at L4–L5. Nerve root involvement due to a disc herniation was reported in 20% of the examinations at L2–L3, 40% of the examinations at L3–L4, and 30% of the examinations at L4–L5”
- The Fleiss kappa score for agreement on the presence of a disc herniation was −
0.02±0.23 across the five motion segments”.(POOR)
- Fleiss kappa score for agreement on the presence of central canal stenosis was 0.17 ±0.32 across the five lumbar motion segments.(POORER YET)
- “marked variability in the reported interpretive findings and an alarmingly high number of interpretive errors in the lumbar MRI reports. “
- “important pathologies are routinely underreported. For example,the study examinations demonstrated an average miss rate for disc herniation of 47.5%. “
- “high false-positive rates for specific pathologies indicate that diagnostic findings, such as central canal stenosis, may be routinely overcalled”
- overreliance on the MRI report for treatment could be disasterous
Comment – not only is serious pathology missed, I have found finding could be downplayed – ie “nerve root is only being touched by disc” – clinically this could be very important. If this was a insurance claim case, I would want my films viewed by more than one MRI site – anyone know good sites?