Assessing Changes in Dementia Diagnostic Category in Patients with Dementia with Lewy Bodies

Single-photon emission computed tomography (SPECT) imaging with the radiopharmaceutical DaTscan™ (Ioflupane¹²³I) can help physicians assess diagnostic category and improve diagnostic confidence for patients with dementia with Lewy bodies (DLB), according to research presented at the 65^th Annual Meeting of the American Academy of Neurology.

Dementia with Lewy bodies, a progressive type of dementia, is the third most common cause of dementia after Alzheimer’s disease and vascular dementia and accounts for 10% to 25% of dementia cases. Lewy bodies are also found in other disorders, such as Alzheimer’s disease and Parkinson’s disease, and there is significant symptom overlap between conditions. Currently available diagnostic techniques for DLB have good specificity but low sensitivity, leading investigators to look for additional imaging techniques that may improve the confidence of diagnoses and allow clinicians to accurately assess changes in dementia over time.

DaTscan™ (Ioflupane¹²³I), a radiopharmaceutical used in single-photon emission computed tomography (SPECT) brain imaging, is the first US FDA-approved radiopharmaceutical specifically designed to allow visualization of striatal dopamine transporters located on the presynaptic terminals of dopaminergic neurons. It is used to evaluate adult patients with suspected Parkinsonian syndrome and assist in the differential diagnosis of tremor associated with Parkinsonian syndromes but can differentiate among the Parkinsonian syndromes.

Zuzana Walker, MD, of the UCL Medical Health Science Center at the University College of London, and colleagues conducted a randomized, open-label, comparative phase 4 study involving 187 patients from 23 centers in six European countries with a diagnosis of possible DLB to assess the impact of DaTscan™ SPECT imaging on dementia diagnostic category and on the diagnostic confidence of clinicians in patients with a diagnosis of possible DLB. DaTscan is a radiopharmaceutical that is administered intravenously as a single dose.

Compared with control patients, patients in the group who underwent DaTscan™ imaging showed a significantly higher change in diagnostic category after eight weeks (62% vs. 4%, P<0.0001) and 24 weeks (69% vs. 16%, P<0.0001). Patients who underwent DaTscan™ imaging also were given more confident diagnoses at both time points. If the DaTscan™ was abnormal, 82% of clinicians were likely to change the patient’s diagnostic category compared with only 48% if the results were normal.

"DaTscan™ SPECT imaging significantly contributed to change diagnostic category and improve diagnostic confidence, proving to be a useful adjunct in the diagnosis of dementia in patients with possible DLB. Changes in diagnostic category were less frequent in the control group despite a six-month prospective follow-up," the authors concluded.

This study was supported by GE Healthcare.