The American College of Physicians' position paper on magnetic resonance imaging (MRI) of the brain and spine [1] fails to mention several clinical disease processes that require MRI for diagnostic clarification.

The article states, for example, that neither computed tomography (CT) nor MRI is helpful for patients with typical Alzheimer disease. It implies that a plain CT scan is sufficient to rule out mass lesions. Although this is true, only MRI can establish the diagnosis of Binswanger subcortical dementia. Similarly, the periventricular hydrocephalic edema seen with normal-pressure hydrocephalus is easily detected by MRI but not by CT.

The article suggests that carotid Doppler evaluation is the test of choice to detect transient ischemic attack. Unfortunately, I have seen patients who had carotid endarterectomies for "transient ischemic attacks" that were actually partial seizures, one from a glioblastoma multiforme and the other from a breast cancer metastasis. Failure to do brain imaging studies before carotid endarterectomy results in a 2% or 3% rate of missed intracranial lesions causing transient ischemic attack-like symptoms.

Finally, the statement that the "imaging with MRI and CT has not been useful in the evaluation of headache and dizziness (in the absence of focal signs)" is ludicrous. Generations of clinical neurologists have found that patients with bilateral subdural hematomas (and even large brain tumors) have headache and no focal signs. These patients require CT for diagnosis, and detection of the insidious Arnold-Chiari malformation in headache evaluation requires MRI to locate the cerebellar tonsils.

The reason that "little evidence is available to define any impact of MRI on overall patient outcomes" can probably be attributed to the fact that the benefit is so obvious to every practicing private and academic physician that such studies would represent only redundant platitudes.

If this position paper in any way deters valuable or necessary scanning of sick patients, a study (probably by trial attorneys) may later prove the adverse clinical effect of officious administrative opinionating of this type.