123I-FP-CIT striatal binding ratios do not decrease significantly with age in older adults

Different z-score cut-offs for striatal binding ratio (SBR) of DaT SPECT are needed to support the diagnosis of Parkinson's Disease (PD) and dementia with Lewy bodies (DLB)

PURPOSE

A cut-off of -2 z-score for striatal or putaminal SBR has been to date arbitrarily used to define an abnormal DaT SPECT in patients with suspected neurodegenerative parkinsonism. We aimed to experimentally identify the most accurate z-score cut-offs for SBR of striatal and substriatal regions to independently discriminate PD and DLB, with respect to essential tremor (ET) and Alzheimer's disease (AD) respectively.

METHODS

Two-hundred twenty-five patients undergoing DaT SPECT were enrolled (seventy-five de novo PD, eighty ET, fifty DLB, and twenty AD). Semiquantification was computed by means of Datquant® software which returns measures of striatal SBR and z-scores with respect to 118 healthy volunteers belonging to the Parkinson's Progression Markers Initiative (PPMI). ROC analysis was used to identify most accurate cut-offs for z-score for striatum and substriatal regions (clinical diagnosis at follow-up as gold standard).

RESULTS

Posterior putamen of the most affected hemisphere (MAH) with a z-score cut-off of  - 1.27 demonstrated the highest accuracy to differentiate between PD and ET (sensitivity 0.97, specificity 0.94). The whole putamen (z-score cut-off  - 0.96) was the most accurate parameter to support the diagnosis of DLB (sensitivity 0.74, specificity 0.95). Putamen to caudate ratio was accurate to detect PD (especially in early stages) while not DLB patients.

CONCLUSION

We experimentally demonstrated that different substriatal regions and cut-offs for z-score of SBR should be considered to support the diagnosis of either PD or DLB. The identified less conservative cut-offs showed higher sensitivity without a measurable reduction in specificity with respect to the arbitrary  - 2 z-score.

Diagnosis of Parkinson syndrome and Lewy-body disease using 123I-ioflupane images and a model with image features based on machine learning

OBJECTIVES

¹²³I-ioflupane has been clinically applied to dopamine transporter imaging and visual interpretation assisted by region-of-interest (ROI)-based parameters. We aimed to build a multivariable model incorporating machine learning (ML) that could accurately differentiate abnormal profiles on ¹²³I-ioflupane images and diagnose Parkinson syndrome or disease and dementia with Lewy bodies (PS/PD/DLB).

METHODS

We assessed ¹²³I-ioflupane images from 239 patients with suspected neurodegenerative diseases or dementia and classified them as having PS/PD/DLB or non-PS/PD/DLB. The image features of high or low uptake (F1), symmetry or asymmetry (F2), and comma- or dot-like patterns of caudate and putamen uptake (F3) were analyzed on 137 images from one hospital for training. Direct judgement of normal or abnormal profiles (F4) was also examined. Machine learning methods included logistic regression (LR), k-nearest neighbors (kNNs), and gradient boosted trees (GBTs) that were assessed using fourfold cross-validation. We generated the following multivariable models for the test database (n = 102 from another hospital): Model 1, ROI-based measurements of specific binding ratios and asymmetry indices; Model 2, ML-based judgement of abnormalities (F4); and Model 3, features F1, F2 and F3, plus patient age. Diagnostic accuracy was compared using areas under receiver-operating characteristics curves (AUC).

RESULTS

The AUC was high with all ML methods (0.92-0.96) for high or low uptake. The AUC was the highest for symmetry or asymmetry with the kNN method (AUC 0.75) and the comma-dot feature with the GBT method (AUC 0.94). Based on the test data set, the diagnostic accuracy for a diagnosis of PS/PD/DLB was 0.86 ± 0.04 (SE), 0.87 ± 0.04, and 0.93 ± 0.02 for Models 1, 2 and 3, respectively. The AUC was optimal for Model 3, and significantly differed between Models 3 and 1 (p = 0.027), and 3 and 2 (p = 0.029).

CONCLUSIONS

Image features such as high or low uptake, symmetry or asymmetry, and comma- or dot-like profiles can be determined using ML. The diagnostic accuracy of differentiating PS/PD/DLB was the highest for the multivariate model with three features and age compared with the conventional ROI-based method.

Prospective Five-Year Follow-Up of Patients with Schizophrenia Suspected with Parkinson's Disease

OBJECTIVE

It is difficult to distinguish patients with schizophrenia with neuroleptic-induced parkinsonism (NIP) from those with existing idiopathic Parkinson's disease when their striatal dopamine transporter uptake is reduced. There is a possibility of misdiagnosis of Parkinson's disease in patients with schizophrenia as schizophrenia with NIP, which leads to inappropriate treatment. This prospective study aimed at determining the underlying pathophysiology using detailed clinical and psychological assessments.

METHODS

We enrolled six patients with schizophrenia who had parkinsonism and were diagnosed with Parkinson's disease according to the Movement Disorder Society Clinical Diagnostic Criteria, except for the fifth absolute exclusion criteria.

RESULTS

Five patients had been treated with neuroleptics for 20 years. One patient refused treatment for schizophrenia. All patients had impaired cognitive function at enrolment, olfactory dysfunction, and constipation. All patients were treated with dopaminergic therapy, and their parkinsonism substantially improved; one woman in her 40s experienced a wearing-off effect and dyskinesia. The uptake of dopamine transporter in the striatum decreased by 13%/year during the study period.

CONCLUSION

Some patients with schizophrenia and parkinsonism benefit from dopaminergic therapy. Some of these patients may also exhibit Lewy pathology.

123I-Ioflupane SPECT and 18F-FDG PET Combined Use in the Characterization of Movement and Cognitive Associated Disorders in Neurodegenerative Diseases

BACKGROUND

Both movement (MD) and cognitive (CD) disorders can occur associated in some neurodegenerative diseases, such as Parkinson's disease (PD) and Alzheimer's disease (AD).

OBJECTIVE

We further investigated the usefulness of 123I-Ioflupane SPECT and 18F-FDG PET combined use in patients with these disorders in the early stage.

METHODS

We retrospectively enrolled twenty-five consecutive patients with MD and CD clinical symptoms of recent appearance. All patients had undergone neurologic examination, neuropsychological tests, and magnetic resonance imaging. 123I-Ioflupane SPECT was performed in all cases, followed by 18F-FDG PET two weeks later. In the two procedures, both qualitative (QL) and quantitative (QN) image analyses were determined.

RESULTS

In patients with both 123I-Ioflupane SPECT and 18F-FDG PET pathologic data, associated dopaminergic and cognitive impairments were confirmed in 56% of cases. Pathologic SPECT with normal PET in 16% of cases could diagnose MD and exclude an associated CD, despite clinical symptoms. On the contrary, normal SPECT with pathologic PET in 28% of cases could exclude basal ganglia damage while confirming CD. QN 123I-Ioflupane SPECT analysis showed better performance than QL since QN correctly characterized two cases of MD with normal QL. Moreover, correct classification of normal metabolism was made only by QN analysis of 18F-FDG PET in four cases, despite suspect areas of hypometabolism at QL.

CONCLUSION

The combined use of these imaging procedures proved a reliable diagnostic tool to accurately identify and characterize MD and CD in early stage. QN analysis was effective in supporting QL evaluation, and its routine use is suggested, especially with inconclusive QL.

Effect of white matter hyperintensity on dopamine transporter availability of striatum measured by F-18 FP-CIT PET

PURPOSE

We aimed to evaluate the white matter hyperintensity (WMH) effect on dopamine transporter availability (DAT) of striatum.

MATERIALS AND METHODS

A total of 48 patients who showed visually normal F-18 FP-CIT uptake were included in this study. Each FP-CIT image were pre-processed using SPM12. Co-registration and spatial normalization of FP-CIT image conducted using T1-weighted magnetic resonance imaging (MRI). And then smoothing of normalized FP-CIT image was performed. Intensity normalization was performed using cerebellum as a reference region. With pre-defined volume of interest template, the specific binding ratio (SBR) of both side of caudate nucleus and putamen was calculated. Fluid attenuated inversion recovery MRI scans were used to evaluate WMH number and volume.

RESULTS

SBRs of left and right caudate nucleus were correlated with age (r = - 0.615; p < 0.0001; n = 48, r = - 0.607; p < 0.0001; n = 48, respectively), high density lipoprotein cholesterol (r = 0.296; p = 0.041; n = 48, r = 0.29; p = 0.0455; n = 48, respectively), and WMH number (r = - 0.459; p = 0.001; n = 48, r = - 0.481; p = 0.0005; n = 48, respectively) and volume (r = - 0.407; p = 0.0041; n = 48, r = - 0.428; p = 0.0024; n = 48, respectively).

CONCLUSION

DAT availability of patients who showed visually normal F-18 FP-CIT uptake was correlated with number and volume of WMH.

Effect of sex on aging-related decline of dopamine transporter in healthy subjects

OBJECTIVE

Aging decreases dopamine transporter (DAT) availability of striatum both in humans and rodents. We aimed to investigate the relationship of DAT availabilities from ventral striatum, caudate nucleus, and putamen with aging in healthy subjects.

METHODS

123I-FP-CIT single photon emission computed tomography (SPECT) was performed in all subjects. Specific binding of 123I-FP-CIT regarding DAT was calculated using a volume-of-interest-based analysis of ventral striatum, caudate nucleus, putamen. The cerebellum was chosen as a reference region. Specific binding ratios (SBRs) were calculated as follows: SBR = (target- cerebellum)/cerebellum.

RESULTS

A total of 166 healthy subjects (109 males and 57 females) were included in this study. SBRs of ventral striatum, caudate nucleus, and putamen were negatively correlated with age. In young males, SBRs of ventral striatum and putamen were not correlated with aging. However, SBRs of caudate nucleus showed the trend toward negative correlation with age in the young group. In old males, SBR of caudate nucleus was negatively correlated with age and SBR of ventral striatum showed a trend toward negative correlation with age. Slopes of regression lines were not significantly different according to age groups in ventral striatum, caudate nucleus, or putamen. SBRs of ventral striatum, caudate nucleus, and putamen were negatively correlated with age in young females, but not in old females. Interestingly, slopes of regression line were significantly different between young and old females in ventral striatum, caudate nucleus, and putamen.

CONCLUSIONS

We have shown that slopes of regression lines of DAT availabilities and age were significantly different between young and old subjects in females, not in males. Therefore, sex has an impact on aging-related decline of striatal DAT availability.

Impact of age and sex correction on the diagnostic performance of dopamine transporter SPECT

Purpose

The specific binding ratio (SBR) of ¹²³I-FP-CIT (FP-CIT) in the putamen decreases with age by about 5% per decade and most likely is about 10% higher in females. However, the clinical utility of age and sex correction of the SBR is still a matter of debate. This study tested the impact of age and sex correction on the diagnostic performance of the putamen SBR in three independent patient samples.

Methods

Research sample: 207 healthy controls (HC) and 438 Parkinson’s disease (PD) patients. Clinical sample A: 183 patients with neurodegenerative parkinsonian syndrome (PS) and 183 patients with non-neurodegenerative PS from one site. Clinical sample B: 84 patients with neurodegenerative PS and 38 patients with non-neurodegenerative PS from another site. Correction for age and sex of the putamen SBR was based on linear regression in the HC or non-neurodegenerative PS, separately in each sample. The area under the ROC curve (AUC) was used as performance measure.

Results

The putamen SBR was higher in females compared to males (PPMI: 14%, p < 0.0005; clinical sample A: 7%, p < 0.0005; clinical sample B: 6%, p = 0.361). Age-related decline of the putamen SBR ranged between 3.3 and 10.4% (p ≤ 0.019). In subjects ≥ 50 years, age and sex explained < 10% of SBR between-subjects variance. Correction of the putamen SBR for age and sex resulted in slightly decreased AUC in the PPMI sample (0.9955 versus 0.9969, p = 0.025) and in clinical sample A (0.9448 versus 0.9519, p = 0.057). There was a small, non-significant AUC increase in clinical sample B (0.9828 versus 0.9743, p = 0.232).

Conclusion

These findings do not support age and sex correction of the putaminal FP-CIT SBR in the diagnostic workup of parkinsonian syndromes. This most likely is explained by the fact that the proportion of between-subjects variance caused by age and sex is considerably below the symptom threshold of about 50% reduction in neurodegenerative PS.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00259-020-05085-2.