Do CT and MRI scans lie? Yes they do!
Three months ago, a 42-year-old man saw a family physician for low backache of two weeks duration. He had no sciatica (pain radiating to buttocks or legs) and no tenderness on pressing that area. After a quick cursory examination of the back and spine, the family physician ordered a MRI scan of the lumbo-sacral spine.
Pic courtesy Reuters
It was reported by the radiologist, who had not seen the patient but only the MRI films, as protrusion of the L3/L4 disc protrusion (uncommon site for disc prolapse). However, on the MRI reported abnormality, the patient was promptly referred to a surgeon, who advised admission the next day. The patient was asked to bring Rs. 350,000 for surgical and hospital expenses.
Sensibly, he did not take the surgeon’s advice, but took a few paracetamols a day and avoided movements causing pain and applied an analgesic cream for a week. He was well in a week and continued working at his desk job without a break
Was the MRI scan or radiologist’s report wrong?
No, neither. A MRI scan shows the anatomy of the spine, discs and nerves. There was no compression of the nerves to indicate a need for surgery. In fact there was no indication for a MRI scan or even a plain x ray. MRI shows the anatomy including the ageing process. As the neck and lumbar spine move hundreds of times for a day there is a certain amount of disc degeneration and even displacement with advancing age. Just as much as the face, skin and hair show changes with age so does the spine – seen in MRI. Often the MRI of a dead person is the same as that of a live person of the same age. In short a MRI shows changes of ageing – other changes need to be correlated to the complaint or symptoms by an experienced neurologist or physician. What was incorrect was the decision by the clinician to advise surgery entirely on the MRI – which only shows anatomy and not impairment of function or activity
What is the indication for a MRI?
The absolute indication for a MRI is when surgery is indicated for backache or neck pain. The patient, and sometimes the clinician may request a MRI as a reference point for the future or to document a more complete diagnosis or for medico-legal or insurance purposes. Surgery is indicated for neck and back pain, when:
- There is demonstrable weakness in a nerve compressed or impinged by a displaced disc
- Objective sensory loss in the distribution of the nerve
- Loss of a reflex innervated by the particular nerve root
- Very severe pain not responding to non-surgical treatment
- Patient insists after explaining natural course and other treatments available. This applies to professional sportsmen and others who cannot do their job or leisure activities
It is essential that the clinician reviews the MRI in relation to the complaint, if necessary together with the reporting radiologist.
Do CT scans also ‘lie’?
MRI scans are preferred for the spine and back of head housing the cerebellum, brain stem and the lower cranial nerves dealing with the eyes, face, and speech and swallowing. Plain CT head scans are best suited for head injuries and acute strokes. Unlike MRI scans, they have the disadvantage of exposure to radiation. CT abnormalities have also to be interpreted in relation to the symptoms, as there can be benign longstanding tumours which are appropriately termed ‘incidentaloma’.
The presence of a tumour or blood does not necessarily mean it has to be removed by surgery. Removal of blood may save a life but quality of life may be severely impaired. Within the cranial cavity, surgery needs consideration for large superficial bleeds inside and outside the brain with deteriorating consciousness and clinical condition.
What activity should be avoided?
Bending the spine and lifting objects may worsen backache, and should be avoided. With neck and arm pain, moving the neck should be avoided. The simple rule is not to do anything that causes pain. A lumbosacral support may help in maintaining the correct posture and a comfortable neck collar too may be helpful for neck pain.
(The writer is a Senior Consultant Neurologist)