Feasibility of PET Template-Based Analysis on F-18 FP-CIT PET in Patients with De Novo Parkinson's Disease

Imaging Procedure and Clinical Studies of [18F]FP-CIT PET

N-3-[18F]fluoropropyl-2β-carbomethoxy-3β-4-iodophenyl nortropane ([18F]FP-CIT) is a radiopharmaceutical for dopamine transporter (DAT) imaging using positron emission tomography (PET) to detect dopaminergic neuronal degeneration in patients with parkinsonian syndrome. [18F]FP-CIT was granted approval by the Ministry of Food and Drug Safety in 2008 as the inaugural radiopharmaceutical for PET imaging, and it has found extensive utilization across numerous institutions in Korea. This review article presents an imaging procedure for [18F]FP-CIT PET to aid nuclear medicine physicians in clinical practice and systematically reviews the clinical studies associated with [18F]FP-CIT PET.

Dual-phase 18 F-FP-CIT positron emission tomography and cardiac 123 I-MIBG scintigraphy of Parkinson's disease patients with GBA mutations: evidence of the body-first type?

BACKGROUND AND PURPOSE

Parkinson's disease (PD) with glucocerebrosidase (GBA) gene mutation (GBA-PD) is known to show more rapid clinical progression than sporadic PD without GBA mutation (sPD). This study was performed to delineate the specific patterns of cortical hypoperfusion, dopamine transporter uptake and cardiac meta-iodobenzylguanidine (MIBG) uptake of GBA-PD in comparison to sPD.

METHODS

Through next-generation sequencing analysis targeting 41 genes, a total of 16 GBA-PD and 24 sPD patients (sex, age matched) were enrolled in the study, and the clinical, dual-phase [¹⁸ F]-N-(3-fluoropropyl)-2β-carboxymethoxy-3β-(4-iodophenyl) nortropane (^{1 8} F-FP-CIT) positron emission tomography (PET) and cardiac ¹²³ I-MIBG scintigraphy results were compared between the two groups.

RESULTS

The GBA-PD group had higher rates of rapid eye movement sleep behavior disorder, orthostatic hypotension and neuropsychiatric symptoms than the sPD group. Early-phase ¹⁸ F-FP-CIT PET showed significantly lower standard uptake value ratio on bilateral posterior parietal cortex (0.94 ± 0.05 vs. 1.02 ± 0.04, p = 0.011) and part of the occipital cortex (p < 0.05) in the GBA-PD group than the sPD group. In striatal dopamine transporter uptake, the regional standard uptake value ratio, asymmetry index and caudate-to-putamen ratio were similar between the two groups. The GBA-PD group had a lower heart-to-mediastinum uptake ratio in ¹²³ I-MIBG scintigraphy than the sPD group.

CONCLUSIONS

The GBA-PD patients showed decreased regional perfusion in the bilateral posterior parietal and occipital cortex. Cardiac sympathetic denervation and non-motor symptoms (orthostatic hypotension, rapid eye movement sleep behavior disorder) were more common in GBA-PD than sPD. These findings suggest that GBA-PD patients have more widespread peripheral (extranigral) α-synuclein accumulation, representing a body-first PD subtype.

First Clinical Report on the Treatment of Parkinson's Disease with Fetal Midbrain Precursor Cells

BACKGROUND

Because human fetal ventral mesencephalic tissue grafts provide promising results in ameliorating Parkinson's disease-implicated motor dysfunctions, human fetal midbrain-derived dopamine neuronal precursor cells are considered good candidates for cell-based therapy for Parkinson's disease in that large quantities of cells can be supplied through a good manufacturing practice-compliant system.

OBJECTIVE

We conducted a prospective, phase I/IIa, dose-escalation, open-label "first-in-human" clinical trial with fetal neural precursor cells to assess their safety and therapeutic efficacy in patients with idiopathic Parkinson's disease.

METHODS

Fifteen patients were assigned to receive three different doses of cells (4 × 10⁶ , 12 × 10⁶ , and 40 × 10⁶ cells) and completed a 12-month follow-up. The primary outcome was safety, by measuring the presence of grade 3 or higher cells according to National Cancer Institute guidelines and any contaminated cells. Secondary outcomes assessed motor and neurocognitive function, as well as the level of dopamine transporters, by positron emission tomography-computed tomography.

RESULTS

Although a pronation-supination and hand/arm movement performance was remarkably enhanced in all three groups (all P < 0.05), the medium- and high-dose-treated groups exhibited significant improvement in Unified Parkinson's Disease Rating Scale Part III only up to 26.16% and 40%, respectively, at 12 months after transplantation without any serious clinical complications or graft-induced dyskinesia in all patients. However, the motor improvements did not correlate with increase in the dopamine transporter on positron emission tomography images.

CONCLUSIONS

Our results primarily demonstrate the safety and plausible dose-dependent efficacy of human fetal midbrain-derived dopamine neuronal precursor cells for idiopathic Parkinson's disease. © 2023 International Parkinson and Movement Disorder Society.

Spatial normalization and quantification approaches of PET imaging for neurological disorders

Quantification approaches of positron emission tomography (PET) imaging provide user-independent evaluation of pathophysiological processes in living brains, which have been strongly recommended in clinical diagnosis of neurological disorders. Most PET quantification approaches depend on spatial normalization of PET images to brain template; however, the spatial normalization and quantification approaches have not been comprehensively reviewed. In this review, we introduced and compared PET template-based and magnetic resonance imaging (MRI)-aided spatial normalization approaches. Tracer-specific and age-specific PET brain templates were surveyed between 1999 and 2021 for ¹⁸F-FDG, ¹¹C-PIB, ¹⁸F-Florbetapir, ¹⁸F-THK5317, and etc., as well as adaptive PET template methods. Spatial normalization-based PET quantification approaches were reviewed, including region-of-interest (ROI)-based and voxel-wise quantitative methods. Spatial normalization-based ROI segmentation approaches were introduced, including manual delineation on template, atlas-based segmentation, and multi-atlas approach. Voxel-wise quantification approaches were reviewed, including voxel-wise statistics and principal component analysis. Certain concerns and representative examples of clinical applications were provided for both ROI-based and voxel-wise quantification approaches. At last, a recipe for PET spatial normalization and quantification approaches was concluded to improve diagnosis accuracy of neurological disorders in clinical practice.

Distinctive regional asymmetry in dopaminergic and serotoninergic dysfunction in degenerative Parkinsonisms

PURPOSE

This study aimed to identify regional asymmetry in dopaminergic and serotoninergic dysfunction in degenerative parkinsonisms, using dopamine transporter single-photon emission computed tomography images.

MATERIAL AND METHODS

This study included 213 consecutive participants (Parkinson's disease [n = 111], dementia with Lewy bodies [n = 64], progressive supranuclear palsy with Richardson's syndrome [n = 18], and healthy participants [n = 20]) who underwent both magnetic resonance imaging and ¹²³I-labelled 2β-carbomethoxy-3β-(4-iodophenyl)-N-(3-fluoropropyl) nortropane single-photon emission computed tomography/computed tomography. Using normalized specific binding ratio images, we created voxel-wise regional asymmetry index images to identify the regional specific pattern of regional asymmetries in degenerative parkinsonisms.

RESULTS

Compared with healthy controls, patients with Parkinson's disease showed a regional asymmetry index increase in the nigrostriatal dopaminergic pathway, and those with dementia with Lewy bodies showed a regional asymmetry index increase confined to the bilateral caudate. Individuals with progressive supranuclear palsy exhibited a distinct regional asymmetry index increase in the pallido-subthalamic pathway. Notably, the regional asymmetry index increase in the subthalamic nucleus was significantly greater in progressive supranuclear palsy than in Parkinson's disease.

CONCLUSION

The current study revealed distinctive regional asymmetry in dopaminergic and serotoninergic dysfunction in degenerative parkinsonisms. The present findings highlight the potential application of visual diagnosis in degenerative parkinsonisms.

Spatial Normalization Using Early-Phase [18F]FP-CIT PET for Quantification of Striatal Dopamine Transporter Binding

Purpose

The precise quantification of dopamine transporter (DAT) density on N-(3-[¹⁸F]Fluoropropyl)-2β-carbomethoxy-3β-(4-iodophenyl) nortropane positron emission tomography ([¹⁸F]FP-CIT PET) imaging is crucial to measure the degree of striatal DAT loss in patients with parkinsonism. The quantitative analysis requires a spatial normalization process based on a template brain. Since the spatial normalization method based on a delayed-phase PET has limited performance, we suggest an early-phase PET-based method and compared its accuracy, referring to the MRI-based approach as a gold standard.

Methods

A total of 39 referred patients from the movement disorder clinic who underwent dual-phase [¹⁸F]FP-CIT PET and took MRI within 1 year were retrospectively analyzed. The three spatial normalization methods were applied for quantification of [¹⁸F]FP-CIT PET-MRI-based anatomical normalization, PET template-based method based on delayed PET, and that based on early PET. The striatal binding ratios (BRs) were compared, and voxelwise paired t tests were implemented between different methods.

Results

The early image-based normalization showed concordant patterns of putaminal [¹⁸F]FP-CIT binding with an MRI-based method. The BRs of the putamen from the MRI-based approach showed higher agreement with early image- than delayed image-based method as presented by Bland-Altman plots and intraclass correlation coefficients (early image-based, 0.980; delayed image-based, 0.895). The voxelwise test exhibited a smaller volume of significantly different counts in putamen between brains processed by early image and MRI compared to that between delayed image and MRI.

Conclusion

The early-phase [¹⁸F]FP-CIT PET can be utilized for spatial normalization of delayed PET image when the MRI image is unavailable and presents better performance than the delayed template-based method in quantitation of putaminal binding ratio.

Extrastriatal SPECT-DAT uptake correlates with clinical and biological features of de novo Parkinson's disease

Striatal dopamine transporter (DAT) uptake assessment through I¹²³-Ioflupane Single-Pphoton Emission Computed Tomography (SPECT) provides valuable information about the dopaminergic denervation occurring in Parkinson's disease (PD). However, little is known about the clinical or biological relevance of extrastriatal DAT uptake in PD. Here, from the Parkinson's Progression Markers Initiative, we studied 623 participants (431 PD and 192 healthy controls) with available SPECT data. Even though striatal denervation was undoubtedly the imaging hallmark of PD, extrastriatal DAT uptake was also reduced in patients with PD. Topographically, widespread frontal but also temporal and posterior cortical regions showed lower DAT uptake in PD patients with respect to healthy controls. Importantly, a longitudinal voxelwise analysis confirmed an active one-year loss of extrastriatal DAT uptake within the PD group. Extrastriatal DAT uptake also correlated with the severity of motor symptoms, cognitive performance, and cerebrospinal fluid α-synuclein levels. In addition, we found an association between the Catechol-O-methyltransferase val¹⁵⁸met genotype and extrastriatal DAT uptake. These results highlight the clinical and biological relevance of extrastriatal SPECT-DAT uptake in PD.

Quantitative Research of 11C-CFT and 18F-FDG PET in Parkinson's Disease: A Pilot Study With NeuroQ Software

Dopamine transporter (DAT) and glucose metabolism imaging have been applied in the diagnosis of Parkinson’s disease (PD). We explored the possibility of evaluating for PD with NeuroQ software by analyzing ¹¹C-2β-carbomethoxy-3β-(4-fluorophenyl) tropane (¹¹C-CFT) and ¹⁸F-FDG PET/CT. We retrospectively analyzed brain ¹¹C-CFT and ¹⁸F-FDG PET/CT of 38 patients with parkinsonism, including 20 with PD, 10 with multiple system atrophy (MSA) and 8 with essential tremor (ET), and compared them with the PET/CT of 11 normal healthy controls (NC). PD patients were divided into mild and moderate-severe grade according to the Hoehn-Yahr (H&Y) scale. The ¹¹C-CFT uptake in the caudate nuclei (CN) and putamen (Pu) normalized with cerebellum (CN/Cb and Pu/Cb) were obtained with a manual method and NeuroQ software, and their diagnostic performance was compared.¹⁸F-FDG uptake of specific regions was also obtained with NeuroQ, and the enhancement effect for the differential diagnosis was evaluated. There was significant agreement between the manual method and the NeuroQ method for ¹¹C-CFT uptake by CN (r²= 0.680) and Pu (r²= 0.770). ¹¹C-CFT uptake by CN and Pu in PD and MSA patients was significantly lower compared to NC and ET patients. The cutoffs of CN/Cb and Pu/Cb for the distinction between PD and NC were 1.71 and 2.20, respectively. No difference in uptake ratios occurred between PD and MSA. ¹⁸F-FDG uptake by the pons and cerebellum in the MSA group was markedly decreased. It was highly accurate in distinguishing between PD and MSA when combined with analysis of ¹¹C-CFT uptake. Pu/Cb decreased significantly in mild grade PD compared to NC group (1.92 ± 0.33 vs. 2.82 ± 0.43); however no statistically significant decrease in CN/Cb was observed until moderate-severe grade PD (1.43 ± 0.11 vs. 2.23 ± 0.36). In early asymmetric PD, a statistically significant difference could be seen with Pu/Cb between the symptomatic and asymptomatic side (2.17 ± 0.30 vs. 1.95 ± 0.22). ¹¹C-CFT and ¹⁸F-FDG PET/CT can be analyzed quantitatively with NeuroQ software, which provides an accurate method for the diagnosis and severity evaluation of PD.

Head-to-head comparison of 18 F-FP-CIT and 123 I-FP-CIT for dopamine transporter imaging in patients with Parkinson's disease: A preliminary study

¹²³ I-FP-CIT and ¹⁸ F-FP-CIT are radiotracers which are widely used to diagnose Parkinson's disease (PD). However, to our knowledge, no studies to date have made head-to-head comparisons between ¹²³ I-FP-CIT and ¹⁸ F-FP-CIT. Therefore, in this study, ¹²³ I-FP-CIT SPECT/CT was compared with ¹⁸ F-FP-CIT PET/CT in the same cohort of subjects. Patients with PD and essential tremor (ET) underwent ¹²³ I-FP-CIT SPECT/CT and ¹⁸ F-FP-CIT PET/CT. Visual and semiquantitative analyses were conducted. The specific binding ratio (SBR) and putamen to caudate ratio (PCR) were compared between subjects who underwent ¹²³ I-FP-CIT SPECT/CT and ¹⁸ F-FP-CIT PET/CT. Visual analysis showed that the striatal uptake of both radiotracers was decreased in the PD group, whereas striatal uptake was intact in the ET group. The SBR between ¹²³ I-FP-CIT SPECT/CT and ¹⁸ F-FP-CIT PET/CT showed a positive correlation (r = .78, p < .01). However, the mean SBRs on ¹⁸ F-FP-CIT PET/CT were higher than those on ¹²³ I-FP-CIT SPECT/CT (2.19 ± .87 and 1.22 ± .49, respectively; p < .01). The PCRs in these two modalities were correlated with each other (r = .71, p < .01). The mean PCRs on ¹⁸ F-FP-CIT PET/CT were not significantly higher than those on ¹²³ I-FP-CIT SPECT/CT (1.31 ± .19 and 0.98 ± .06, respectively; p = .06). These preliminary results indicate that the uptake of both ¹²³ I-FP-CIT and ¹⁸ F-FP-CIT was decreased in the PD group when compared with the ET controls. Visual analyses using both methods did not affect the diagnostic accuracy in this study. However, semiquantitative analysis indicated a better contrast of ¹⁸ F-FP-CIT PET/CT relative to ¹²³ I-FP-CIT SPECT/CT.

Functional volumetric analysis of striatum using F-18 FP-CIT PET in patients with idiopathic Parkinson's disease and normal subjects

OBJECTIVE

We applied a simple isocontour volume-of-interest (VOI) method to analyze the whole striatum in an F-18 FP-CIT PET image and to investigate the usefulness of the method in differentiating healthy subjects from idiopathic Parkinson's disease (IPD) patients and the correlation of the value of functional volume parameters with the motor symptoms in patients with IPD.

METHODS

Forty-three IPD patients and 23 age-matched healthy controls underwent F-18 FP-CIT PET. Using a dedicated workstation, VOIs for the whole striatum were drawn automatically with the gradient delineation method. The SUVmax, SUVmean, functional volume (FV), striatal volume activity (SVA), striatal-specific binding (SSB), and volume-specific uptake ratio (VSUR) were compared between the IPD patients and the normal subjects. In the IPD patients, the correlation between the clinical factor and the functional parameters was assessed.

RESULTS

The SUVmax, SUVmean, FV, SVA, SSB, and VSUR were significantly lower in the IPD patients than in the normal subjects. In the receiver operating characteristic analysis, those parameters had significant and good-to-excellent accuracy. In the patients with IPD, a moderate negative correlation was revealed between the SUVmax and H&Y stage, the SUVmean and H&Y stage, SVA and H&Y stage, the VSUR and H&Y stage, the FV and bradykinesia, and the SVA and bradykinesia.

CONCLUSION

The functional volumetric analysis of the striatum based on simple isocontour VOI was a useful method of analyzing the F-18 FP-CIT PET image. Not only can it be easily applied in daily clinical practice, but it can also be used as a clinical parameter to discriminate IPD and to correlate it with the disease severity.

Feasibility of Computed Tomography-Guided Methods for Spatial Normalization of Dopamine Transporter Positron Emission Tomography Image

Background

Spatial normalization is a prerequisite step for analyzing positron emission tomography (PET) images both by using volume-of-interest (VOI) template and voxel-based analysis. Magnetic resonance (MR) or ligand-specific PET templates are currently used for spatial normalization of PET images. We used computed tomography (CT) images acquired with PET/CT scanner for the spatial normalization for [¹⁸F]-N-3-fluoropropyl-2-betacarboxymethoxy-3-beta-(4-iodophenyl) nortropane (FP-CIT) PET images and compared target-to-cerebellar standardized uptake value ratio (SUVR) values with those obtained from MR- or PET-guided spatial normalization method in healthy controls and patients with Parkinson’s disease (PD).

Methods

We included 71 healthy controls and 56 patients with PD who underwent [¹⁸F]-FP-CIT PET scans with a PET/CT scanner and T1-weighted MR scans. Spatial normalization of MR images was done with a conventional spatial normalization tool (cvMR) and with DARTEL toolbox (dtMR) in statistical parametric mapping software. The CT images were modified in two ways, skull-stripping (ssCT) and intensity transformation (itCT). We normalized PET images with cvMR-, dtMR-, ssCT-, itCT-, and PET-guided methods by using specific templates for each modality and measured striatal SUVR with a VOI template. The SUVR values measured with FreeSurfer-generated VOIs (FSVOI) overlaid on original PET images were also used as a gold standard for comparison.

Results

The SUVR values derived from all four structure-guided spatial normalization methods were highly correlated with those measured with FSVOI (P < 0.0001). Putaminal SUVR values were highly effective for discriminating PD patients from controls. However, the PET-guided method excessively overestimated striatal SUVR values in the PD patients by more than 30% in caudate and putamen, and thereby spoiled the linearity between the striatal SUVR values in all subjects and showed lower disease discrimination ability. Two CT-guided methods showed comparable capability with the MR-guided methods in separating PD patients from controls and showed better correlation between putaminal SUVR values and the parkinsonian motor severity than the PET-guided method.

Conclusion

CT-guided spatial normalization methods provided reliable striatal SUVR values comparable to those obtained with MR-guided methods. CT-guided methods can be useful for analyzing dopamine transporter PET images when MR images are unavailable.

Parametric Cerebrovascular Reserve Images Using Acetazolamide (99m)Tc-HMPAO SPECT: A Feasibility Study of Quantitative Assessment

PURPOSE

Basal/acetazolamide stress (99m)Tc-HMPAO single-photon emission computed tomography (SPECT) has been widely used for evaluation of hemodynamics; however, qualitative and subjective visual assessment of cerebrovascular reserve (CVR) has been performed in clinical settings. The aim of this study was to generate parametric CVR images and evaluate its feasibility of quantification.

METHODS

Basal/acetazolamide stress (99m)Tc-HMPAO SPECT data from 17 patients who underwent bypass surgery or percutaneous transluminal angioplasty were used. Spatial normalization was performed and parametric CVR images were generated using relative CVR (rCVR) of each voxel proportional to CVR of the whole brain. Binary parametric maps to show area of relatively reduced CVR were generated also using threshold of rCVR < 90 %. We calculated rCVR of internal carotid artery (ICA) using the parametric CVR images and probabilistic maps for ICA territory. Pre- and postprocedural parametric CVR images were obtained and quantitative rCVRs were compared. The rCVRs were evaluated according to visual grades for regional decreased CVR.

RESULTS

Postprocedural rCVR obtained from parametric CVR images increased significantly from preprocedural rCVR. The rCVR was significantly correlated with visual grades of reduced CVR for each side of ICA territories.

CONCLUSIONS

We generated parametric CVR images for basal/acetazolamide stress (99m)Tc-HMPAO SPECT. As a quantitative measurement, rCVR obtained from the parametric image was feasibly assessed hemodynamic abnormalities with preserved anatomical information.