It is now 47 and 38 years respectively, since the first CT and MRI scanners were installed in India. Despite the passage of decades and these scans becoming part of common lexicon, there is still a lopsided distribution of the 2,500 CT and 900 MRI scanners in India.
The compound annual growth rate of CT scanners is 25%, (10% in metros), driven by expansion of diagnostic chains and availability of affordable, refurbished scanners. A total of 880 scanners were installed in 2024 alone. Around 30% of CT scanners are in Tier 2 and Tier 3 cities – suburban India contributes 40% of India’s total diagnostic sector revenue.
The criteria for scans
There is a conflict of interest between deploying hardcore, evidence-based, absolute criteria for a CT/ MRI brain scan and paying attention to return on investment (RoI). “We are answerable to our investors” is the oft-repeated statement of hospital managements. Non-indicated scanning is preceded with statements such as: “Just to be sure, what if something is picked up. It is a simple test; is your life not important.” Faced with such statements, it takes a bold or very knowledgeable patient to say “No”.
It is true that medicine is not mathematics. Healthcare is never black or white. Indications for a brain scan are not always absolute. Ideally, they need to be customised for the individual’s clinical presentation at that time. It is often forgotten that a scan only reflects the discernible structural condition of the brain during the 5 to 15 minutes that the patient is in the gantry. A scan done immediately after a brain injury could differ from a scan done later. A “normal” scan could lead to complacency and a false sense of security for patient and doctor. Clinical re-evaluation plays a far more important role.
The findings
A 3T MRI scan is so sophisticated that if various state -of-the-art imaging protocols are deployed, “incidentalomas” will be picked up. We still do not know what MRI brain findings in very elderly Indians are clinically relevant — many people for instance, die with a brain tumour not of one. For patients, the confusion can be immense on reading a scan report and they may not understand what can be discounted and what must not be.More damage is done with self-referral scans. Well-meaning but ill-informed friends and relatives also contribute: “What, a brain scan was not done even after you fell down?”. “You have had a headache for 30 years, you should be investigated, your last scan was 2 years ago.”
Excessive diagnostics
There is no incentive for a diagnostic centre in the private sector to reduce expenditure; it is in fact, the opposite. Worldwide, incentives increase referrals. Physician-owners of diagnostic centres would find it difficult to be truly objective as to whether a test is needed or not. There is also another side to this: excessive diagnostic testing is also done due to unjustified fears of medico-legal implications and patient insistence. It is not realised by most that exposure to multiple CT scans before the age of 20 increases brain cancer risk. One study from Australia attributed 4% of brain cancers to CT scans.
If the Canadian CT Head Rule, which lists criteria that require a CT scan, is implemented, 33% of CT brain scans can be reduced, without any increase in missed brain injuries or adverse outcomes. This is now incorporated in decision support protocols in several countries. Clinical judgement depends on knowledge, experience and detailed history and examination of findings.
In the properly-chosen patient, the probability of a normal CT should be low. Purely from a clinical management perspective, an investigation is generally required, only if the findings are likely to significantly alter the line of management. In large Indian studies, 78% of CT brain scans were normal. In international reports, 83% of MRI brain scans were normal. About 80% of MRI brain scans in children with developmental delays however, showed some abnormality.
A global problem
The real world is different from Utopia. It is difficult to say if patients and their families could be convinced to forego testing even with the results of double-blind randomised studies or how such convincing could be done sensitively. India remains a paradox: hundreds of millions still do not have access to life saving CT/ MRI studies, while at the same time thousands of unnecessary brain scans are being done. The problem is not limited to India alone: studies have shown that this phenomenon is global, highlighting the need for more conversations amongst medical professionals, patients and societies.
(Dr. K. Ganapathy is a distinguished professor at the Tamil Nadu Dr. MGR Medical University and past president of the Neurological Society of India and the Telemedicine Society of India. Email: drkganapathy@gmail.com)
Published – October 02, 2025 09:14 pm IST
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