Greater use of SPECT in psychiatric care could help diagnose neurological conditions, remove the stigma of mental illness, and end the practice of psychiatrists "flying blind" when treating patients, according to psychiatrist and SPECT proponent Dr. Daniel Amen.
A controversial figure, Amen is a New York Times best-selling author and the CEO and founder of the Amen Clinics, which use brain SPECT for various purposes, including the evaluation of traumatic brain injury.
In a February talk at the Canadian Association of Nuclear Medicine (CANM) annual meeting, Amen encouraged nuclear medicine physicians to partner with psychiatrists in an effort to improve psychiatric diagnoses, make appropriate therapeutic choices, and observe the impact of treatment.
Amen pointed to a clinical study which found that increased regional cerebral blood flow (rCBF) in the subgenual cingulate and prefrontal cortex as determined by technetium-99m (Tc-99m) hexamethyl-propylene-aminoxime (HMPAO) SPECT was predictive of which depressed patients would better respond to the selective serotonin reuptake inhibitor citalopram (Psychiatry Research: Neuroimaging, August 30, 2009, Vol. 173:2, pp. 107-112).
Highlighting another investigation, Amen discussed a prospective case series in which he and colleagues demonstrated that the use of SPECT altered diagnosis or treatment in 86 of 109 psychiatric patients (Journal of Psychoactive Drugs, April-June 2012, Vol. 44:2, pp. 96-106).
Contemporary psychiatric practice fails to offer the underlying biology of a disorder to a patient, and 3D SPECT, in particular, can offer that insight by looking at areas of blood flow in the brain, Amen said. Citing a systematic review published last year, Amen noted that SPECT has been shown to improve lesion detection compared to CT and MRI for traumatic brain injury (TBI), in particular mild TBI (PLOS One, March 19, 2014, Vol. 9:3, pp. e91088).
Psychiatric diagnosis remains largely based on "educated guessing" and determining if patients meet the American Psychiatric Association's Diagnostic and Statistical Manual of Mental Disorders (DSM-5) criteria for particular conditions, Amen maintained.
"We [psychiatrists] are condemned to fly blind, and that is not OK with me," he said. "We are not stuck with [the brains] we have. We can make them better and improve them. But how would you know [what a brain is like], if you did not look?"
The most serious consequence of "ineffectively treated mental illness" can be death, Amen told CANM attendees.
The use of brain SPECT imaging has shed light on how playing football can affect brain function, with scans displaying global decreased perfusion in various areas of the brain in present and former players of the National Football League (Journal of Neuropsychiatry and Clinical Neurosciences, Winter 2011, Vol. 23:1, pp. 98-106).
Another benefit of a more systematic incorporation of brain imaging into clinical psychiatry would be the destigmatization of psychiatric disorders.
"Imaging decreases the stigma," Amen said. "It changes the discourse around mental health. It makes it something medical and not moral. No one wants to be labeled abnormal. It decreases the shame and guilt, and families have more compassion for the person who is affected."
The best tool for the job
But is SPECT the best tool for the job? The lay press has been skeptical of Amen's research, with a 2012 article in the Washington Post quoting psychiatric and imaging experts who believe that his claims of SPECT's effectiveness for mental disorders aren't borne out by the wider body of peer-reviewed research.
Indeed, Dr. Jean-Paul Soucy, a nuclear medicine physician and director of the PET unit at the Montreal Neurological Institute and Hospital, described Amen's approach as allowing too much room for error in diagnosis.
"The technique he uses can easily lead to over- or underreading [of brain scans]," Soucy said in an interview.
He said that SPECT, in particular, is a low-resolution imaging modality that does not provide enough information to allow clinicians to arrive at a diagnosis, while PET does.
"PET gives you information about anatomical location, and the tracers [used] allow you to study neurotransmission," Soucy said.
Dr. Philip Cohen, clinical director of the department of medicine at Lions Gate Hospital in North Vancouver, British Columbia, where SPECT is used in collaboration by nuclear medicine physicians and psychiatrists, agreed with Soucy that PET produces finer images than SPECT does. He also acknowledged that Amen's current approach lacks coregistration and normalization to verify the accuracy of what is imaged.
But he offered that SPECT technology costs about one-tenth the price of PET, making it much more accessible in clinical healthcare.
"PET has higher count rates and produces finer images than SPECT, based on the current detectors," explained Cohen. "PET and SPECT are not in the same ballpark in terms of cost."
But SPECT can be enhanced in terms of accuracy and used as an approximation for PET, he said.
"With the right hardware and attention to detail, and focused collimators, SPECT produces images that I would say are very close [85% to 90%] to PET, at a substantially reduced cost," Cohen said.
