Typical cerebral metabolic patterns in neurodegenerative brain diseases

The differential diagnosis of neurodegenerative brain diseases on clinical grounds is difficult, especially at an early disease stage. Several studies have found specific regional differences of brain metabolism applying [(18)F]-fluoro-deoxyglucose positron emission tomography (FDG-PET), suggesting that this method can assist in early differential diagnosis of neurodegenerative brain diseases.We have studied patients who had an FDG-PET scan on clinical grounds at an early disease stage and included those with a retrospectively confirmed diagnosis according to strictly defined clinical research criteria. Ninety-six patients could be included of which 20 patients with Parkinson's disease (PD), 21 multiple system atrophy (MSA), 17 progressive supranuclear palsy (PSP), 10 corticobasal degeneration (CBD), 6 dementia with Lewy bodies (DLB), 15 Alzheimer's disease (AD), and 7 frontotemporal dementia (FTD). FDG PET images of each patient group were analyzed and compared to18 healthy controls using Statistical Parametric Mapping (SPM5).Disease-specific patterns of relatively decreased metabolic activity were found in PD (contralateral parietooccipital and frontal regions), MSA (bilateral putamen and cerebellar hemispheres), PSP (prefrontal cortex and caudate nucleus, thalamus, and mesencephalon), CBD (contralateral cortical regions), DLB (occipital and parietotemporal regions), AD (parietotemporal regions), and FTD (frontotemporal regions).The integrated method addressing a spectrum of various neurodegenerative brain diseases provided means to discriminate patient groups also at early disease stages. Clinical follow-up enabled appropriate patient inclusion. This implies that an early diagnosis in individual patients can be made by comparing each subject's metabolic findings with a complete database of specific disease related patterns.

Direct comparison of FP-CIT SPECT and F-DOPA PET in patients with Parkinson's disease and healthy controls

PURPOSE

Diagnosing Parkinson's disease (PD) on clinical grounds may be difficult, especially in the early stages of the disease. F-DOPA PET and FP-CIT SPECT scans are able to determine presynaptic dopaminergic activity in different ways. The aim of this study was to determine and compare the sensitivity and specificity of the two methods in the detection of striatal dopaminergic deficits in the same cohort of PD patients and healthy controls.

METHODS

Movement disorder specialists recruited 11 patients with early-stage PD and 17 patients with advanced PD. The patients underwent both an FP-CIT SPECT scan and an F-DOPA PET scan. In addition, 10 FP-CIT SPECT scans or 10 F-DOPA PET scans were performed in 20 healthy controls. A template with regions of interest was used to sample tracer activity of the caudate, putamen and a reference region in the brain. The outcome parameter was the striatooccipital ratio (SOR). Normal SOR values were determined in the controls. The sensitivity and specificity of both scanning methods were calculated.

RESULTS

FP-CIT SPECT and F-DOPA PET scans were both able to discriminate PD patients from healthy controls. For the early phases of the disease, sensitivity and specificity of the contralateral striatal and putaminal uptake of FP-CIT and F-DOPA was 100%. When only caudate uptake was considered, the specificities were 100% and 90% for FP-CIT and F-DOPA, respectively, while the sensitivity was 91% for both scanning techniques.

CONCLUSION

FP-CIT SPECT and F-DOPA PET scans are both able to diagnose presynaptic dopaminergic deficits in early phases of PD with excellent sensitivity and specificity.

Comparison of FP-CIT SPECT with F-DOPA PET in patients with de novo and advanced Parkinson’s disease

PURPOSE

Diagnosis of Parkinson's disease (PD) can be difficult. F-DOPA PET is able to quantify striatal dopa decarboxylase activity and storage capacity of F-dopamine, but is expensive and not generally available. FP-CIT binds to the dopamine transporter, and FP-CIT SPECT is cheaper and more widely available, but has a lower resolution. The aim of this study was to compare these two methods in the same patients with different stages of PD to assess their power in demonstrating deficits of the striatal dopaminergic system.

METHODS

Thirteen patients with de novo PD and 17 patients with advanced PD underwent FP-CIT SPECT and static F-DOPA PET. After data transfer to standard stereotactic space, a template with regions of interest was used to sample values of the caudate, putamen and an occipital reference region. The outcome value was striato-occipital ratios. Patients were clinically examined in the "off state" (UPDRS-III and H&Y stage).

RESULTS

Good correlations were found between striatal F-DOPA uptake and striatal FP-CIT uptake (r = 0.78) and between putaminal F-DOPA uptake and putaminal FP-CIT uptake (r = 0.84, both p < 0.0001). Both striatal uptake of FP-CIT and that of F-DOPA correlated moderately with H&Y stage (rho = -0.52 for both techniques), UPDRS-III (rho = -0.38 for F-DOPA; rho = -0.45 for FP-CIT) and disease duration (rho = -0.59 for F-DOPA; rho = -0.49 for FP-CIT, all p < 0.05).

CONCLUSION

FP-CIT values correlate well with F-DOPA values. Both methods correlate moderately with motor scores and are equally able to distinguish patients with advanced PD from patients with de novo PD.

PET neuroimaging and mutations in the DJ-1 gene

Mutations in the DJ-1 gene lead to autosomal recessive early-onset parkinsonism. We performed F-DOPA and FDG PET neuroimaging in two parkinsonism patients homozygous for DJ-1 mutations, three relatives heterozygous for a DJ-1 mutation and one non-carrier, all from the originally described kindred from The Netherlands. Their characteristics were compared to those of typical Parkinson's disease patients and healthy controls. Both parkinsonism patients had reduced F-DOPA uptake concordant with typical Parkinson's disease. In the, clinically unaffected, heterozygous relatives, F-DOPA metabolism was unremarkable, thus not suggesting a dosage effect of the DJ-1 gene.