Third, it remains unclear whether widespread neuroimaging in psychiatry will be cost-effective. Unless imaging results are tied to effective treatments, neuroimaging is unlikely to result in cost savings. Presently, patients who can afford out-of-pocket care might be able to access neuroimaging. If neuroimaging were shown to improve clinical outcomes but remains costly, this unequal distribution of resources would create an ethical quandary.
Finally, neuroimaging is complex and almost certainly not as objective as one might hope. Interpreting images will require specialized knowledge and skills that are beyond those of currently certified general psychiatrists.12 Because there is a great deal of overlap in brain anomalies across psychiatric illnesses, it is unclear whether using neuroimaging for diagnostic purposes will eclipse a thorough clinical assessment. For example, the amygdala and insula show activation across a range of anxiety disorders. Abnormal amygdala activation has also been reported in depression, bipolar disorder, schizophrenia, and psychopathy.13
In addition, psychiatric comorbidity is common. It is unclear how much neuroimaging will add diagnostically when a patient presents with multiple psychiatric disorders. Comorbidity of psychiatric and neurologic disorders also is common. A neurologic illness that is detectable by structural neuroimaging does not necessarily exclude the presence of a psychiatric disorder. This poses yet another challenge to developing reliable, valid neuroimaging techniques for clinical use.
Areas of controversy
First-episode psychosis. Current practice guidelines for neuroimaging in patients with FEP are inconsistent. The Canadian Choosing Wisely Guidelines recommend against routinely ordering neuroimaging in first-episode psychoses in the absence of signs or symptoms that suggest intracranial pathology.14 Similarly, the American Psychiatric Association’s Practice Guideline for the Treatment of Patients with Schizophrenia recommends ordering neuroimaging in patients for whom the clinical picture is unclear or when examination reveals abnormal findings.15 In contrast, the Australian Clinical Guidelines for Early Psychosis recommend that all patients with FEP receive brain MRI.16 Freudenreich et al17 describe 2 philosophies regarding the initial medical workup of FEP: (1) a comprehensive medical workup requires extensive testing, and (2) in their natural histories, most illnesses eventually declare themselves.
Despite this inconsistency, the overall evidence does not seem to support routine brain imaging for patients with FEP in the absence of neurologic or cognitive impairment. A systematic review of 16 studies assessing the clinical utility of structural neuroimaging in FEP found that there was “insufficient evidence to suggest that brain imaging should be routinely ordered for patients presenting with first-episode psychosis without associated neurological or cognitive impairment.”18
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