Value of 99mTc-ECD SPET for the diagnosis of dementia with Lewy bodies

Abstract

Despite improved diagnostic accuracy, differentiation of dementia with Lewy bodies (DLB) and Alzheimer's disease (AD) on the basis of clinical findings remains problematic. The purpose of this retrospective study was to evaluate the utility of technetium-99m ethyl cysteinate dimer (ECD) single-photon emission tomography (SPET) as a potential tool for the diagnosis of DLB and discrimination from AD. Cerebral perfusion patterns detected by (99m)Tc-ECD SPET were compared in patients presenting with a probable diagnosis of DLB ( n=34) or AD ( n=28). Tracer distribution was quantified using the region of interest technique in eight symmetrical paired zones and expressed as a perfusion index (ratio of mean uptake in a brain region to that in the cerebellum). Comparison of findings in the DLB and AD groups demonstrated significant differences in mean perfusion indexes in the right occipital region ( P=0.004), left occipital region ( P=0.005) and left medial temporal region ( P=0.013). Mean perfusion indexes in the right and left occipital regions were lower in DLB than in AD patients. Conversely, the mean perfusion index in the left medial temporal region was lower in AD than in DLB patients. DLB was correctly identified in 22 patients (sensitivity, 65%) while AD was correctly identified in 20 patients (specificity, 71%). In the DLB group, right and left occipital perfusion indexes were 0.95 or more in all eight non-hallucinating patients, and bilateral occipital hypoperfusion was observed in 15 of the 26 patients with visual hallucinations (57.7%). To our knowledge, this is the first study in which (99m)Tc-ECD SPET has been used exclusively for the diagnosis of DLB. The results suggest that brain perfusion scintigraphy could be helpful in distinguishing DLB from AD if diagnosis based on clinical criteria alone is difficult. The findings also support a link between visual hallucinations and structural/functional changes in the occipital region in DLB patients.

Multivariate Spatial Covariance Analysis of 99MTc-Exametazime SPECT Images in Dementia with Lewy Bodies and Alzheimer'S Disease: Utility in Differential Diagnosis

“…The studies showed a variable DLB sensitivity and AD specificity of 65% to 85% and 71% to 87%, respectively. 10,11,13,14,33 Studies using 18 F-fluorodeoxyglucose positron emission tomography have largely shown greater diagnostic accuracy than perfusion SPECT in distinguishing DLB from AD. 34,35 The DLB sensitivity and AD specificity are quoted as ranging from 86% to 92% and from 80% to 92%, respectively, although such results should be viewed with caution because of the relatively small samples studied and indeed larger more recent AD DLB positron emission tomography study was found to be less accurate (sensitivity 64%, specificity 65%).…”

“…Using region of interest methods, occipital, frontal, and parietal lobe perfusion deficits have been observed in DLB relative to AD, with relative preservation of temporal lobe perfusion. [9][10][11] Using voxelwise procedures, reduced rCBF in occipital cortex as well as in the precuneus has been shown in DLB compared with AD. [12][13][14] Results from visual rating are less consistent, 15,16 with some even reporting similar patterns of hypoperfusion between DLB and nonDLB cases.…”

Diagnosis of dementia with Lewy bodies: can 123I-IMP and 123I-MIBG scintigraphy yield new core features?

“…Pasquier et al, 18 who used 99m Tc-labelled ethylcysteinate dimer as a tracer in their brain perfusion SPECT study, found that the sensitivity for the diagnosis of DLB was 65% and specificity was 71%. Similarly, each hypoperfusion of the posterior cingulate, praecuneus and occipital lobe was a meaningful index in the univariate analysis in our study.…”

“…[13][14][15][16][17] The value of 123 I-MIBG myocardial scintigraphy in the early diagnosis of DLB and in the differential diagnosis between DLB and other dementias has been studied; scintigraphic findings are reported to yield independent diagnostic predictors of DLB. [18][19][20][21] In their metaanalysis, Treglia and Cason 22 demonstrated that MIBG scintigraphy is an accurate diagnostic imaging method to differentiate DLB from other dementias; they reported a pooled sensitivity and specificity of 98% and 94%, respectively. In addition, 123 I-MIBG scintigraphy appears to be of higher sensitivity than brain perfusion SPECT for the diagnosis of DLB.…”

Efficacy of Single Photon Emission Computed Tomography in Differentiating Dementia with Lewy Bodies - A Review of Neurotransmitter and Perfusion Imaging

“…Perfusion SPECT studies (see Table 3) have assessed regional cerebral blood flow, a marker of brain function, using 99m Tc-hexamethylpropylene amine oxime (HMPAO), 13,26-29 99m Tc-ethyl cysteinate dimer (ECD) 13,16,30 AD. Combining these two measures gave good sensitivity of 95% and modest specificity of 65% (see Table 3).…”