Head to head comparison of [18F] AV-1451 and [18F] THK5351 for tau imaging in Alzheimer's disease and frontotemporal dementia

PURPOSE

Tau accumulation is a core pathologic change in various neurodegenerative diseases including Alzheimer's disease and frontotemporal lobar degeneration-tau. Recently, tau positron emission tomography tracers such as [¹⁸F] AV-1451 and [¹⁸F] THK5351 have been developed to detect tau deposition in vivo. In the present study, we performed a head to head comparison of these two tracers in Alzheimer's disease and frontotemporal dementia cases and aimed to investigate which tracers are better suited to image tau in these disorders.

METHODS

A cross-sectional study was conducted using a hospital-based sample at a tertiary referral center. We recruited eight participants (two Alzheimer's disease, four frontotemporal dementia and two normal controls) who underwent magnetic resonance image, amyloid positron emission tomography with [¹⁸F]-Florbetaben and tau positron emission tomography with both THK5351 and AV-1451. To measure regional AV1451 and THK5351 uptakes, we used the standardized uptake value ratios by dividing mean activity in target volume of interest by mean activity in the cerebellar hemispheric gray matter.

RESULTS

Although THK5351 and AV-1451 uptakes were highly correlated, cortical uptake of AV-1451 was more striking in Alzheimer's disease, while cortical uptake of THK5351 was more prominent in frontotemporal dementia. THK5351 showed higher off-target binding than AV-1451 in the white matter, midbrain, thalamus, and basal ganglia.

CONCLUSIONS

AV-1451 is more sensitive and specific to Alzheimer's disease type tau and shows lower off-target binding, while THK5351 may mirror non-specific neurodegeneration.

Human Radiation Dosimetry of [(18)F]AV-1451(T807) to Detect Tau Pathology

PURPOSE

[(18)F]AV-1451 is a positron emission tomography (PET) radioligand for detecting paired helical filament tau. Our aim was to estimate the radiation dose of [(18)F]AV-1451 in humans.

PROCEDURES

Whole-body PET scans were acquired for six healthy volunteers (three male, three female) for 128 min after injection of [(18)F]AV-1451 (268 ± 31 MBq). Radiation doses were estimated using the OLINDA/EXM software.

RESULTS

The estimated organ doses ranged from 7.81 to 81.2 μSv/MBq. The critical organ for radiation burden was the liver. Radiation doses to the reproductive and blood-forming organs were 14.15, 8.43, and 18.35 μSv/MBq for the ovaries, testes, and red marrow, respectively. The mean effective dose was 22.47 ± 3.59 μSv/MBq.

CONCLUSIONS

A standard single injection of 185 MBq (5 mCi) results in an effective dose of 4.7 mSv in a healthy subject. Therefore, [(18)F]AV-1451 could be used in multiple PET scans of the same subject per year.

18F-AV-1451 PET Imaging in Three Patients with Probable Cerebral Amyloid Angiopathy

Cerebrovascular deposition of amyloid-β, known as cerebral amyloid angiopathy (CAA), is associated with MRI findings of lobar hemorrhage, cerebral microbleeds, and cortical superficial siderosis. Although pathological studies suggest that tau may co-localize with vascular amyloid, this has not yet been investigated in CAA in vivo. Three patients with probable CAA underwent 11C-Pittsburgh Compound B (PiB) PET or 18F-florbetaben PET to evaluate amyloid burden, and 18F-AV-1451 PET to evaluate paired helical filament tau burden. Regions that had cerebral microbleeds or cortical superficial siderosis largely overlapped with those showing increased 18F-AV-1451. Our preliminary study raised the possibility that lobar cerebral microbleeds, and cortical superficial siderosis, which are characteristic markers of vascular amyloid, may be associated with local production of paired helical filament tau.

18F-AV-1451 binds to motor-related subcortical gray and white matter in corticobasal syndrome

OBJECTIVE

To investigate tau distribution in patients with corticobasal syndrome (CBS) using ¹⁸F-AV-1451 PET.

METHODS

Six consecutively recruited patients with CBS and 20 age-matched healthy controls underwent 2 PET scans with ¹⁸F-AV-1451 (for tau) and ¹⁸F-florbetaben (for β-amyloid). We compared standardized uptake value ratio maps of the ¹⁸F-AV-1451 PET images between the patients with CBS and controls.

RESULTS

Compared to controls, patients with CBS exhibited asymmetrically increased ¹⁸F-AV-1451 binding in the putamen, globus pallidus, and thalamus contralateral to the clinically more affected side and in the ipsilateral globus pallidus and dentate nucleus. Voxel-based comparison additionally showed asymmetrically increased ¹⁸F-AV-1451 binding in the focal regions of the precentral gray and white matter and in the midbrain, predominantly in the contralateral side. ¹⁸F-AV-1451 binding in the precentral white matter correlated with motor severity.

CONCLUSIONS

¹⁸F-AV-1451 asymmetrically binds to motor-related subcortical gray and white matter structures in patients with CBS. This pattern corresponds to tau pathology distribution in postmortem studies, and motor deficit in patients with CBS may be associated with tau accumulation predominantly in the subcortical white matter underlying the motor cortex, leading to disruptions in motor-related networks.

Off-Target 18F-AV-1451 Binding in the Basal Ganglia Correlates with Age-Related Iron Accumulation

Off-target binding in the basal ganglia is commonly observed in the ¹⁸F-AV-1451 PET studies of the elderly. We sought to investigate the relationship between this phenomenon in the basal ganglia and iron accumulation using iron-sensitive R₂* MRI. Methods: Fifty-nine healthy controls and 61 patients with Alzheimer disease and mild cognitive impairment underwent ¹⁸F-AV-1451 PET and R₂* MRI studies. A correlation analysis was performed for age, ¹⁸F-AV-1451 binding, and R₂* values. Results: There was an age-related increase in both ¹⁸F-AV-1451 binding in the basal ganglia and R₂* values in the putamen in both the controls and the Alzheimer disease/mild cognitive impairment patients. ¹⁸F-AV-1451 binding in the basal ganglia increased with R₂* values. Conclusion: Off-target ¹⁸F-AV-1451 binding in the basal ganglia is associated with the age-related increases in iron accumulation. Postmortem studies are required to further investigate the nature of this association.

Comparison of standardized uptake value of 18F-FDG-PET-CT with 21-gene recurrence score in estrogen receptor-positive, HER2-negative breast cancer

BACKGROUND

We investigated the relationship between 18F-fluorodeoxyglucose positron emission tomography-computed tomography (18F-FDG-PET-CT) standardized uptake value (SUV) and 21-gene recurrence score (RS) in estrogen receptor (ER)-positive/HER2-negative breast cancer.

MATERIALS AND METHODS

One hundred sixty-seven patients were identified among those who underwent preoperative 18F-FDG-PET-CT and had RS. Maximum SUV was obtained from 18F-FDG-PET-CT; the cut-off point was 4.

RESULTS

The continuous RS and SUV correlated positively (Pearson's R = 0.555; P < 0.001). An inverse correlation was found between progesterone receptor (PR) expression by reverse transcriptase-polymerase chain reaction, and SUV (Pearson's R = -0.408; P < 0.001). Good agreement between dichotomized RS (<26 vs. ≥26) and SUV (<4 vs. ≥4) was observed in 137 of 167 patients (82.0%; 95% confidence interval [CI], 76.2-87.9). Among patients with low SUV, 114 of 115 (99.1% [95% CI, 97.4-100.0]) had tumors with lower RS (<26). Although 23 of 52 women (44.2% [95% CI, 30.7-57.7]) with high SUV had higher RS (≥26), all 13 women with high RS (≥31) had high-SUV tumors. Most cases with disagreements between SUV and RS (n = 30) were classified as high SUV/lower RS (n = 29). The discordant group had higher grade or elevated Ki67 expression (≥20%) compared with the low SUV/lower RS group (n = 109), but higher PR expression compared with the high SUV/higher RS group (n = 23). Multiple logistic regression analysis showed that high SUV were associated with higher RS (≥26).

CONCLUSIONS

SUV, as a biologic parameter represented using a continuous variable, was found to associate with RS in ER-positive, HER2-negative breast cancer. Further studies may reveal the biology underlying the discordance between the markers.

Tau Accumulation in Primary Motor Cortex of Variant Alzheimer's Disease with Spastic Paraparesis

We studied topographic distribution of tau and amyloid-β in a patient with variant Alzheimer's disease with spastic paraparesis (VarAD) by comparing AD patients. The proband developed progressive memory impairment, dysarthria, and spastic paraparesis at age 23. Heterozygous missense mutation (L166P) was found in exon 6 of presenilin-1 gene. The proband showed prominently increased amyloid binding in striatum and cerebellum and asymmetrical tau binding in the primary sensorimotor cortex contralateral to the side more affected by spasticity. We suspect that upper motor neuron dysfunctions may be attributed to excessive abnormal tau accumulation rather than amyloid-β in the primary motor cortex.

Environmental enrichment enhances synaptic plasticity by internalization of striatal dopamine transporters

Environmental enrichment (EE) with a complex combination of physical, cognitive and social stimulations enhances synaptic plasticity and behavioral function. However, the mechanism remains to be elucidated in detail. We aimed to investigate dopamine-related synaptic plasticity underlying functional improvement after EE. For this, six-week-old CD-1 mice were randomly allocated to EE or standard conditions for two months. EE significantly enhanced behavioral functions such as rotarod and ladder walking tests. In a [¹⁸F]FPCIT positron emission tomography scan, binding values of striatal DAT were significantly decreased approximately 18% in the EE mice relative to the control mice. DAT inhibitor administrated to establish the relationship of the DAT down-regulation to the treatment effects also improved rotarod performances, suggesting that DAT inhibition recapitulated EE-mediated treatment benefits. Next, EE-induced internalization of DAT was confirmed using a surface biotinylation assay. In situ proximity ligation assay and immunoprecipitation demonstrated that EE significantly increased the phosphorylation of striatal DAT as well as the levels of DAT bound with protein kinase C (PKC). In conclusion, we suggest that EE enables phosphorylation of striatal DAT via a PKC-mediated pathway and causes DAT internalization. This is the first report to suggest an EE-mediated mechanism of synaptic plasticity by internalization of striatal DAT.

In vivo cortical spreading pattern of tau and amyloid in the Alzheimer disease spectrum

OBJECTIVE

To determine the in vivo cortical spreading pattern of tau and amyloid and to establish positron emission tomography (PET) image-based tau staging in the Alzheimer disease (AD) spectrum.

METHODS

We included 195 participants (53 AD, 52 amnestic mild cognitive impairment [MCI], 23 nonamnestic MCI, and 67 healthy controls) who underwent 2 PET scans ((18) F-florbetaben for amyloid-β and (18) F-AV-1451 for tau). We assumed that regions with earlier appearances of pathology may show increased binding in a greater number of participants and acquired spreading order of tau accumulation by sorting the regional frequencies of involvement. We classified each participant into image-based tau stage based on the Z score of the composite region for each stage.

RESULTS

Tau accumulation was most frequently observed in the medial temporal regions and spread stepwise to the basal and lateral temporal, inferior parietal, posterior cingulate, and other association cortices, and then ultimately to the primary cortical regions. In contrast, amyloid accumulation was found with similar frequency in the diffuse neocortical areas and then finally spread to the medial temporal regions. The image-based tau stage correlated with the general cognitive status, whereas cortical thinning was found only in the advanced tau stages: medial temporal region in stage V and widespread cortex in stage VI.

INTERPRETATION

Our PET study replicated postmortem spreading patterns of tau and amyloid-β pathologies. Unlike the diffuse accumulation of amyloid throughout the neocortex, tau spreading occurred in a stepwise fashion through the networks. Image-based tau staging may be useful for the objective assessment of AD progression. Ann Neurol 2016;80:247-258.

Tau PET in Alzheimer disease and mild cognitive impairment

OBJECTIVE

To investigate the topographical distribution of tau pathology and its effect on functional and structural changes in patients with Alzheimer disease (AD) and mild cognitive impairment (MCI) by using (18)F-AV-1451 PET.

METHODS

We included 20 patients with AD, 15 patients with MCI, and 20 healthy controls, and performed neuropsychological function tests, MRI, as well as (18)F-florbetaben (for amyloid) and (18)F-AV-1451 (for tau) PET scans. By using the regional volume-of-interest masks extracted from MRIs, regional binding values of standardized uptake value ratios and volumes were measured. We compared regional binding values among 3 diagnostic groups and identified correlations among the regional binding values, performance in each cognitive function test, and regional atrophy.

RESULTS

(18)F-AV-1451 binding was increased only in the entorhinal cortex in patients with MCI, while patients with AD exhibited greater binding in most cortical regions. In the 35 patients with MCI and AD, (18)F-AV-1451 binding in most of the neocortex increased with a worsening of global cognitive function. The visual and verbal memory functions were associated with the extent of (18)F-AV-1451 binding, especially in the medial temporal regions. The (18)F-AV-1451 binding also correlated with the severity of regional atrophy of the cerebral cortex.

CONCLUSIONS

Tau PET imaging with (18)F-AV-1451 could serve as an in vivo biomarker for the evaluation of AD-related tau pathology and monitoring disease progression. The accumulation of pathologic tau is more closely related to functional and structural deterioration in the AD spectrum than β-amyloid.

Relationship Between 18F-Fluorodeoxyglucose Uptake and V-Ki-Ras2 Kirsten Rat Sarcoma Viral Oncogene Homolog Mutation in Colorectal Cancer Patients: Variability Depending on C-Reactive Protein Level

To evaluate clinical values of clinicopathologic and 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography/computed tomography (PET/CT)-related parameters for prediction of v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) mutation in colorectal cancer (CRC) and to investigate their variability depending on C-reactive protein (CRP) levels. In total, 179 CRC patients who underwent PET/CT scans before curative resection and KRAS mutation evaluation following surgery were enrolled. Maximum standardized uptake value (SUV max), peak standardized uptake value (SUV peak), metabolic tumor volume, and total lesion glycolysis were determined semiquantitatively. Associations between clinicopathologic and PET/CT-related parameters and KRAS expression were analyzed. Elevated CRP (> 6.0 mg/L; n = 47) was associated with higher primary tumor size, higher SUV max, SUV peak, metabolic tumor volume, and total lesion glycolysis, compared with those for the group with a CRP lower than that the cutoff value (< 6.0 mg/L; n = 132). Interestingly, the CRC patients (having CRP < 6.0 mg/L) with KRAS mutations had significantly higher (P < 0.05) SUV max and SUV peak values than the patients expressing wild-type KRAS mutations. Multivariate analysis revealed SUV max and SUV peak to be significantly associated with KRAS mutations (odds ratio = 3.3, P = 0.005, and odds ratio = 3.9, P = 0.004), together with histologic grade and lymph node metastasis. 18F-FDG uptake was significantly higher in CRC patients with KRAS mutations and with normal CRP levels. A severe local inflammation with raised CRP levels, however, might affect accurate 18F-FDG quantification in CRC tumors. Positron emission tomography/computed tomography-related parameters could supplement genomic analysis to determine KRAS expression in CRC; however, care should be exercised to guarantee proper patient selection.

Standardized uptake value of ¹⁸F-fluorodeoxyglucose positron emission tomography for prediction of tumor recurrence in breast cancer beyond tumor burden

Introduction

¹⁸F-fluorodeoxyglucose positron emission tomography (FDG-PET) can reveal the metabolic activity of malignant tumors. Recent advances gained from molecular studies suggest that tumor biology can be a good predictor of prognosis in breast cancer. We compared the ability of maximum standardized uptake values (SUV_max) derived by FDG-PET with tumor burden in predicting tumor recurrence for patients with breast cancer.

Methods

496 patients with breast cancer who underwent preoperative FDG-PET between April 2004 and May 2009 were retrospectively identified. SUV_max was obtained by FDG-PET, and the cutoff point was defined using a time-dependent receiver operating characteristic curve for recurrence-free survival (RFS). The primary endpoint was RFS.

Results

In multivariate analysis for RFS, SUV_max carried independent prognostic significance (hazard ratio, 2.39; 95% confidence interval, 1.20 to 4.76; P = 0.012). When the patients were classified into four groups according to the combined factors of tumor size (≤2 cm versus >2 cm) and SUV_max (<4 versus ≥4), RFS differed significantly (P < 0.001). Similarly, SUV_max had prognostic value in combination with nodal status (negative versus positive) or stage (I versus II and III) (P < 0.001 and P = 0.001, respectively). In hormone receptor–positive disease, SUV_max remained a significant prognostic factor for RFS based on multivariate analysis.

Conclusions

Our results highlight the prognostic value of FDG-PET in prediction of tumor relapse for patients with breast cancer. Particularly in patients with hormone receptor–positive disease, the tumor metabolic information provided by FDG-PET is more significantly correlated with prognosis than tumor burden.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-014-0502-y) contains supplementary material, which is available to authorized users.

Optimal timing of [¹⁸F]Mefway PET for imaging the serotonin 1A receptor in healthy male subjects

To determine the optimal acquisition time of [(18)F]Mefway PET, we examined the regional specific-to-nonspecific binding ratios and evaluated the relationship between distribution volume ratios (DVRs) and standardized uptake value ratios (SUVRs) in various time windows. The specific-to-nonspecific binding ratios peaked after 40 min and there was a strong correlation between DVR and SUVR in the 60-80 min. Therefore, we recommend the use of a single time point between 60 and 80 min for [(18)F]Mefway static PET.

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.

[(18)F] FP-CIT PET study in parkinsonian patients with leukoaraiosis

BACKGROUNDS

Leukoaraiosis may present with slowly progressive parkinsonism indistinguishable from primary degenerative parkinsonism. Both leukoaraiosis and degenerative parkinsonism are an age-related disorder. Thus, comorbidity is expected to be common in elderly patients with parkinsonism. However, no systematic study has been reported on the clinical features indicating concomitant nigrostriatal dopaminergic denervation (NDD) in parkinsonian patients with leukoaraiosis.

METHODS

We performed [(18)F] FP-CIT positron emission tomography studies in 42 consecutive parkinsonian patients with diffuse leukoaraiosis, but no basal ganglia vascular lesions.

RESULTS

Twenty (48%) of the 42 patients had coexisting NDD. Compared to parkinsonian patients with isolated leukoaraiosis, those with coexisting NDD more frequently had asymmetric onset. They had similar degree of parkinsonian motor deficits in the legs, but greater rigidity and resting tremor in the arms. Consequently, they had less prominent lower body parkinsonism. They more frequently showed favorable response to levodopa treatment. They had similar burden of regional and total leukoaraiosis. Among a variety of clinical variables and MRI findings, only asymmetric onset and more than 30% improvement in UPDRS motor score by levodopa treatment were valuable indicators of coexisting NDD.

CONCLUSIONS

We would like to recommend dopaminergic functional imaging studies for all parkinsonian patients with leukoaraiosis. Further studies are needed to confirm sensitivity and specificity of asymmetric onset and good levodopa response for the prediction of coexisting NDD in a different group of parkinsonian patients with leukoaraiosis.

18F-Mefway PET imaging of serotonin 1A receptors in humans: a comparison with 18F-FCWAY

Introduction

The purpose of this research is to evaluate the prospects for the use of 4-(trans-¹⁸F-fluoranylmethyl)-N-[2-[4-(2-methoxyphenyl)piperazin-1-yl]ethyl]-N-pyridin-2-ylcyclohexane-1-carboxamide (¹⁸F-Mefway) in comparison to ¹⁸F-trans-4-fluoro-N-2-[4-(2-methoxyphenyl)piperazin-1-yl]ethyl]-N-(2-pyridyl)cyclohexanecarboxamide (¹⁸F-FCWAY) for the quantification of 5-HT_1A receptors in human subjects.

Method

Five healthy male controls were included for two positron emission tomography (PET) studies: ¹⁸F-FCWAY PET after the pretreatment with 500 mg of disulfiram and two months later, ¹⁸F-Mefway PET without disulfiram. Regional time-activity curves (TACs) were extracted from nine cortical and subcortical regions in dynamic PET images. Using cerebellar cortex without vermis as reference tissue, in vivo kinetics for both radioligands were compared based on the distribution volume ratio (DVR) calculated by non-invasive Logan graphical analysis and area under the curve ratio of the TACs (AUC ratio).

Result

Although the pattern of regional uptakes in the ¹⁸F-Mefway PET was similar to that of the ¹⁸F-FCWAY PET (highest in the hippocampus and lowest in the cerebellar cortex), the amount of regional uptake in ¹⁸F-Mefway PET was almost half of that in ¹⁸F-FCWAY PET. The skull uptake in ¹⁸F-Mefway PET was only 25% of that in ¹⁸F-FCWAY PET with disulfiram pretreatment. The regional DVR values and AUC ratio values for ¹⁸F-Mefway were 17—40% lower than those of ¹⁸F-FCWAY. In contrast to a small overestimation of DVR values by AUC ratio values (< 10%) in ¹⁸F-FCWAY PET, the overestimation bias of AUC ratio values was much higher (up to 21%) in ¹⁸F-Mefway PET.

Conclusion

As ¹⁸F-Mefway showed lower DVR values and greater overestimation bias of AUC ratio values, ¹⁸F-Mefway may appear less favorable than ¹⁸F-FCWAY. However, in contrast to ¹⁸F-FCWAY, the resistance to in vivo defluorination of ¹⁸F-Mefway obviates the need for the use of a defluorination inhibitor. Thus, ¹⁸F-Mefway may be a good candidate PET radioligand for 5-HT_1A receptor imaging in human.

A computed tomography-based spatial normalization for the analysis of [18F] fluorodeoxyglucose positron emission tomography of the brain

Objective

We developed a new computed tomography (CT)-based spatial normalization method and CT template to demonstrate its usefulness in spatial normalization of positron emission tomography (PET) images with [¹⁸F] fluorodeoxyglucose (FDG) PET studies in healthy controls.

Materials and Methods

Seventy healthy controls underwent brain CT scan (120 KeV, 180 mAs, and 3 mm of thickness) and [¹⁸F] FDG PET scans using a PET/CT scanner. T1-weighted magnetic resonance (MR) images were acquired for all subjects. By averaging skull-stripped and spatially-normalized MR and CT images, we created skull-stripped MR and CT templates for spatial normalization. The skull-stripped MR and CT images were spatially normalized to each structural template. PET images were spatially normalized by applying spatial transformation parameters to normalize skull-stripped MR and CT images. A conventional perfusion PET template was used for PET-based spatial normalization. Regional standardized uptake values (SUV) measured by overlaying the template volume of interest (VOI) were compared to those measured with FreeSurfer-generated VOI (FSVOI).

Results

All three spatial normalization methods underestimated regional SUV values by 0.3-20% compared to those measured with FSVOI. The CT-based method showed slightly greater underestimation bias. Regional SUV values derived from all three spatial normalization methods were correlated significantly (p < 0.0001) with those measured with FSVOI.

Conclusion

CT-based spatial normalization may be an alternative method for structure-based spatial normalization of [¹⁸F] FDG PET when MR imaging is unavailable. Therefore, it is useful for PET/CT studies with various radiotracers whose uptake is expected to be limited to specific brain regions or highly variable within study population.

Rebound thymic hyperplasia detected by 18F-FDG PET/CT after radioactive iodine ablation therapy for thyroid cancer

BACKGROUND

Rebound thymic hyperplasia (RTHP) is not an uncommon finding after radiation or chemotherapy in patients with various malignancies. However, there are limited case reports of this phenomenon after radioactive iodine ablation therapy (RIAT) in differentiated thyroid cancer (DTC). The goal of this study was to evaluate the incidence, patterns, and factors affecting RTHP after RIAT using (18)F-FDG PET/CT.

METHODS

The study design was a retrospective review of 2550 patients (568 men, 1982 women; age 13-79 years) who underwent FDG PET/CT imaging after total thyroidectomy and RIAT from June 2009 through June 2012. Patients were divided into four age-related subgroups. Overall incidence, age-related incidences, and sex distribution were evaluated in patients with thymic FDG uptake on PET/CT (RTHP+). The correlation between incidence of RTHP and age was assessed using the Cochran-Armitage trend test. The Wilcoxon rank-sum test and multiple regression were applied to investigate the effect of applied dose of radioactive iodine (RAI) and age on the incidence of RTHP. Correlations of standardized uptake value (SUV) and thymic volume with age and morphologic type were also evaluated.

RESULTS

Overall incidence of RTHP after RIAT was 1.49%, and all of the RTHP+ patients except one were female. The Cochran-Armitage trend test revealed significantly decreased incidence from the second to fifth decade (8.84%, 1.74%, 0.98%, and 0.39% respectively; p<0.001). In each age-related subgroup, the RAI dose was significantly higher in the RTHP+ than RTHP- group (p<0.001), while there was no difference in RAI dose in RTHP+ patients among age-related subgroups (p=0.838). SUVmean and SUVmax of RTHP revealed no meaningful correlation with RAI dose or age. There were no differences among morphologic patterns of RTHP in age distribution and ablation dose.

CONCLUSIONS

RTHP after RIAT showed a strong female predominance, despite the higher administration dose of RAI in male patients. Although the decreased incidence of RTHP after RIAT with age is similar to the pattern of RTHP induced by other causes, the fact that older patients, even sixth decade patients, can present with RTHP after RIAT is noteworthy in the management of DTC.

Role of diffusion-weighted MRI: predicting axillary lymph node metastases in breast cancer

BACKGROUND

Ultrasound (US) is probably the standard imaging procedure in most centers, and US-guided fine needle aspiration can be added if suspicious lymph nodes are found. However, US-guided fine needle aspiration is an invasive method to diagnose a metastasis and has showed relatively low sensitivity. In general, diffusion-weighted (DW) magnetic resonance imaging (MRI) has become an emerging technique for discriminating benign from malignant breast lesions in a short imaging acquisition time.

PURPOSE

To evaluate the potential for using DW MRI with an apparent diffusion coefficient (ADC) value to predict axillary lymph node metastases in patients with invasive breast cancer.

MATERIAL AND METHODS

This study enrolled 110 axillary lymph nodes from 110 consecutive women who were diagnosed with invasive breast cancer for preoperative breast MRI and US. The largest enhancing ipsilateral axillary lymph nodes were included in this study, and benign and metastatic axillary lymph nodes were compared according to the pathologic reports. The cut-off ADC value to differentiate between benign and metastatic axillary lymph nodes was evaluated with receiver-operating characteristic curve analysis. Diagnostic performance of ultrasound and DW MRI was calculated for enhancing lymph node in dynamic contrast-enhanced MRI.

RESULTS

Nodal metastases were documented in 68 (62%) axillary lymph nodes. The mean size of metastatic axillary lymph nodes was larger than that of benign axillary lymph nodes (15.5 mm vs. 10.9 mm, P < 0.001). The mean ADC value (0.69 × 10(-3 )mm(2)/s) of the metastases was significantly lower than that of the benign axillary lymph nodes (1.04 × 10(-3 )mm(2)/s) (P < 0.001). The ADC value cut-off between metastatic and benign axillary lymph nodes was 0.90 × 10(-3 )mm(2)/s. Using ADC cut-off, sensitivity, specificity, and accuracy of DW MRI were 100%, 83.3%, and 93.6%, respectively. The sensitivity, specificity, and accuracy of US showed 94.1%, 54.8%, and 79.1%, respectively.

CONCLUSION

DW MRI of axillary lymph nodes can provide reliable information for the differentiation of benign from metastatic axillary lymph nodes in invasive breast cancer patients.

Usefulness of (131)I-SPECT/CT and (18)F-FDG PET/CT in Evaluating Successful (131)I and Retinoic Acid Combined Therapy in a Patient with Metastatic Struma Ovarii

Metastatic struma ovarii is an extremely rare disease, and the treatment of choice has not been established. Here, we introduce the case of a 36-year-old female pregnant patient with metastatic struma ovarii. Initial treatment was an exploratory laparotomy to remove multiple peritoneal masses. After delivery, a total thyroidectomy was done for the further (131)I-therapy. (131)I-SPECT/CT and (18) F-FDG PET/CT showed multiple hepatic metastases and extensive peritoneal seeding nodules. Multiple (131)I and retinoic acid combination therapies were performed, resulting in marked improvement. (131)I-SPECT/CT and (18) F-FDG PET/CT were quite useful for evaluating the biologic characteristics of the metastases.

Prognostic significance of standardized uptake value on preoperative ¹⁸F-FDG PET/CT in patients with ampullary adenocarcinoma

PURPOSE

The purpose of this study was to investigate the prognostic value of (18)F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) in patients with ampullary adenocarcinoma (AAC) after curative surgical resection.

METHODS

Fifty-two patients with AAC who had undergone (18)F-FDG PET/CT and subsequent curative resections were retrospectively enrolled. The maximum standardized uptake value (SUVmax) and tumor to background ratio (TBR) were measured on (18)F-FDG PET/CT in all patients. The prognostic significances of PET/CT parameters and clinicopathologic factors for recurrence-free survival (RFS) and overall survival (OS) were evaluated by univariate and multivariate analyses.

RESULTS

Of the 52 patients, 19 (36.5%) experienced tumor recurrence during the follow-up period and 18 (35.8%) died. The 3-year RFS and OS were 62.3 and 61.5%, respectively. Preoperative CA19-9 level, tumor differentiation, presence of lymph node metastasis, SUVmax, and TBR were significant prognostic factors for both RFS and OS (p < 0.05) on univariate analyses, and patient age showed significance only for predicting RFS (p < 0.05). On multivariate analyses, SUVmax and TBR were independent prognostic factors for RFS, and tumor differentiation, SUVmax, and TBR were independent prognostic factors for OS.

CONCLUSION

SUVmax and TBR on preoperative (18)F-FDG PET/CT are independent prognostic factors for predicting RFS and OS in patients with AAC; patients with high SUVmax (>4.80) or TBR (>1.75) had poor survival outcomes. The role of and indications for adjuvant therapy after curative resection of AAC are still unclear. (18)F-FDG uptake in the primary tumor could provide additive prognostic information for the decision-making process regarding adjuvant therapy.

Risk factors for developing hyponatremia in thyroid cancer patients undergoing radioactive iodine therapy

Background

Due to the alarming increase in the incidence of thyroid cancer worldwide, more patients are receiving postoperative radioactive iodine (RAI) therapy and these patients are given a low-iodine diet along with levothyroxine withdrawal to induce a hypothyroid state to maximize the uptake of RAI by thyroid tissues. Recently, the reported cases of patients suffering from life-threatening severe hyponatremia following postoperative RAI therapy have increased. This study aimed to systematically assess risk factors for developing hyponatremia following RAI therapy in post-thyroidectomy patients.

Methods

We reviewed the medical records of all thyroid cancer patients who underwent thyroidectomy and postoperative RAI therapy from July 2009 to February 2012. Demographic and biochemical parameters including serum sodium and thyroid function tests were assessed along with medication history.

Results

A total of 2229 patients (47.0±11.0 years, female 76.3%) were enrolled in the analysis. Three hundred seven patients (13.8%) of all patients developed hyponatremia; 44 patients (2.0%) developed moderate to severe hyponatremia (serum Na⁺≤130 mEq/L) and another 263 (11.8%) patients showed mild hyponatremia (130 mEq/L<serum Na⁺≤135 mEq/L). In univariate analysis, old age, female sex, presence of hypertension, presence of diabetes, use of thiazide diuretics, use of angiotensin receptor blocker or angiotensin-converting enzyme inhibitors, lung metastasis, and hyponatremia and lower estimated glomerular filtration rate at the start of RAI therapy were significantly associated with hyponatremia in patients undergoing RAI therapy after total thyroidectomy. Multivariate analysis showed that old age, female sex, use of thiazide diuretics, and hyponatremia at the initiation of RAI therapy were independent risk factors for the development of hyponatremia.

Conclusion

Our data suggest that age greater than 60 years, female sex, use of thiazide, and hyponatremia at the initiation of RAI therapy are important risk factors for developing hyponatremia following RAI therapy in post-thyroidectomy patients.

[18F]-fluorodeoxyglucose positron emission tomography can contribute to discriminate patients with poor prognosis in hormone receptor-positive breast cancer

BACKGROUND

Patients with hormone receptor-positive breast cancer typically show favorable survival. However, identifying individuals at high risk of recurrence among these patients is a crucial issue. We tested the hypothesis that [18F]-fluorodeoxyglucose positron emission tomography (FDG-PET) scans can help predict prognosis in patients with hormone receptor-positive breast cancer.

METHODS

Between April 2004 and December 2008, 305 patients with hormone receptor-positive breast cancer who underwent FGD-PET were enrolled. Patients with luminal B subtype were identified by positivity for human epidermal growth factor receptor-2 (HER2) or high Ki67 (≥14%) according to criteria recently recommended by the St. Gallen panelists. The cut-off value of SUVmax was defined using the time-dependent receiver operator characteristic curve for recurrence-free survival (RFS).

RESULTS

At a median follow up of 6.23 years, continuous SUVmax was a significant prognostic factor with a hazard ratio (HR) of 1.21 (p = 0.021). The cut-off value of SUVmax was defined as 4. Patients with luminal B subtype (n = 82) or high SUVmax (n = 107) showed a reduced RFS (p = 0.031 and 0.002, respectively). In multivariate analysis for RFS, SUVmax carried independent prognostic significance (p = 0.012) whereas classification with immunohistochemical markers did not (p = 0.274). The Harell c-index was 0.729. High SUVmax was significantly associated with larger tumor size, positive nodes, HER2 positivity, high Ki67 (≥14%), high tumor grade, and luminal B subtype.

CONCLUSIONS

Among patients with hormone receptor-positive breast cancer, FDG-PET can help discriminate patients at high risk of tumor relapse.

Low iodine diet for one week is sufficient for adequate preparation of high dose radioactive iodine ablation therapy of differentiated thyroid cancer patients in iodine-rich areas

BACKGROUND

Most current guidelines suggest one or two weeks of low iodine diet (LID) before radioactive iodine ablation therapy (RAIT) to increase its efficacy in differentiated thyroid cancer (DTC) patients after total thyroidectomy. LID duration is particularly important for patients living in iodine excess areas. However, there is no standardized LID protocol and there are limited reports regarding the relationship between LID and ablation outcome. Therefore, we aimed to evaluate the optimal LID duration and define clinical features that affect ablation outcome.

METHODS

A total of 202 papillary thyroid cancer patients with total thyroidectomy preparing for RAIT were enrolled. All patients had undergone two weeks of LID before (131)I administration. Morning spot urine specimens were obtained twice (one week or two weeks after LID, respectively) from each patient. Urine iodine excretion (UIE) values were used to evaluate LID efficacy. Successful ablation was defined using two definitions: (i) no visible uptake on a follow-up diagnostic (131)I scans, and (ii) no visible uptake on a follow-up diagnostic (131)I scans and stimulated serum thyroglobulin (Tg) levels <1 ng/mL.

RESULTS

The UIE median values after LID for one and two weeks were lower than 50 μg/L, and the median UIE values were not significantly different according to the LID duration. Based on the first criterion for successful ablation, 175 of the 195 patients were successfully ablated. There were no significant differences in mean and median UIE levels between the ablated and non-ablated groups after LID for two weeks. The rate of ablation did not differ between the mild and moderate iodine deficient groups. Based on the second criterion for successful ablation, 149 of 188 patients were successfully ablated. The ablation success rate did not differ between UIE levels. When we analyzed clinical factors that affect ablation outcome, serum Tg level at the time of ablation was the only significant variable in multivariate logistic analysis.

CONCLUSION

Strict LID for one week was sufficient to achieve target UIE values for RAIT preparation, even in iodine-rich areas.

Translational possibility of [18 F]Mefway to image serotonin 1A receptors in humans: Comparison with [18 F]FCWAY in rodents

PURPOSE

To compare the cerebral uptake and binding potential of [¹⁸ F]FCWAY and [¹⁸ F]Mefway in the rodent to assess their potential for imaging serotonin 1A (5-HT_1A ) receptors.

MATERIALS AND METHODS

In vitro liver microsomal studies were performed to evaluate the degree of defluorination. Dynamic positron emission tomography (PET) studies were then conducted for 2 h with or without an anti-defluorination agent. The regions of interest were the hippocampus and frontal cortex (5-HT_1A target regions) and the cerebellum (5-HT_1A nontarget region). The in vivo kinetics of the radioligands were compared based on the brain uptake values and target-to-nontarget ratio. We also performed a comparison of binding potential (BP_ND ) as a steady-state binding parameter. Finally, binding affinities to 5-HT_1A receptors were assessed in Chinese hamster ovary cells (CHO-K1) cells expressing human recombinant 5-HT_1A receptors.

RESULTS

The radiochemical yield of [¹⁸ F]Mefway was slightly higher than that of [¹⁸ F]FCWAY (19 vs. 15%). With regard to metabolic stability against defluorination, both compounds exhibited similar stability in rat liver microsomes, but [¹⁸ F]Mefway displayed higher stability in the human microsome (defluorination ratio at 30 min: 32 vs. 29 in rat liver microsomes, 31 vs. 64 in human liver microsomes for [¹⁸ F]Mefway and [¹⁸ F]FCWAY, respectively). There were no significant differences in brain uptake, the target-to-nontarget ratios, and the BP_ND (at hippocampus, peak brain uptakes: 6.9 vs. 8.5, target-to-nontarget ratios: 6.9 vs. 8.5, BP_ND : 5.2 vs. 6.2 for [¹⁸ F]Mefway and [¹⁸ F]FCWAY). The binding affinity of [¹⁸ F]Mefway was considerably higher than that of [¹⁸ F]FCWAY (IC₅₀ : 1.5 nM vs. 2.2 nM).

CONCLUSION

[¹⁸ F]Mefway exhibits favorable characteristics compared to [¹⁸ F]FCWAY in rodents, and may be a promising radioligand for use in human subjects. Synapse 68:595-603, 2014. © 2014 Wiley Periodicals, Inc.

Acute physical stress induces the alteration of the serotonin 1A receptor density in the hippocampus

Stress affects the serotonergic system, which is associated with depression. Previous research has showed that chronic stress causes the deactivation of the limbic system. However, the influence of the acute physical stress on the serotonergic system in vivo was primarily unclear. The purpose of this research is to elucidate the effects of the acute physical stress in vivo using PET. For quantification of the 5-HT1A receptors in the brain, we measured [(18)F]Mefway uptake in the two experiment groups (control and despair rats). The despair group was subjected to the external stressful situation (i.e., forced swimming) and total duration time of immobility, refers to the despair severity, and was analyzed. In the intercomparison experiment, the resulting PET images of [(18)F]Mefway in the despair rat displayed a significant reduction of radioactivity in the hippocampus (HP) compared with the control. The nondisplaceable binding potential (BPND ) refers to the ratio of the concentration of radioligand in the receptor-rich region (i.e., HP) to the concentration of that in the receptor-free region (i.e., cerebellum). The hippocampal uptake and the BPND in the despair group were respectively about 25 and 18% lower than those of the control group. The ratio of specific binding to nonspecific binding in the despair group was 18% lower than that of the control. In the intracomparison experiments, the BPND and immobility in the despair group showed a strong negative correlation. Taken together, the data illustrates that an acute physical stress induces the change in the serotonergic system that correlates with the behavioral despair.

Determination of optimal acquisition time of [(18)F]FCWAY PET for imaging serotonin 1A receptors in the healthy male subjects

The purpose of this research is to find optimal acquisition time point of [(18)F]FCWAY PET for the assessment of serotonin 1A receptor (5-HT1A) density. To achieve this goal, we examined the specific-to-nonspecific ratios in various brain regions. The cerebellum has very few 5-HT1A receptors in the brain, so we set this region as the reference tissue. As a result, specific-to-nonspecific binding ratios in the frontal, temporal cortex and the hippocampus were steadily increased at 90 min after injection and remained stable at 120 min. In addition, the binding ratio of the late time was significantly higher than that of the previous time points. From these results, we recommend that 90 min p.i. is a better single time point for the analysis rather than previous time points for assessing [(18)F]FCWAY binding to 5-HT1A receptors.

Knowledge, Self-Efficacy, and Perceived Barriers on the Low-Iodine Diet among Thyroid Cancer Patients Preparing for Radioactive Iodine Therapy

The purposes of the study were to assess knowledge, self-efficacy, and perceived barriers on a low-iodine diet among thyroid cancer patients and to identify strategies for nutrition education. A self-administered questionnaire was developed based on a review of literature and pilot-tested. A total of 121 female thyroid cancer patients participated in a survey and 117 responses were used for data analysis. An average knowledge score of the thyroid cancer patients was 4.5 point (available score: 0-10 point). Majority of the respondents knew that seaweeds such as lavers, brown seaweeds, and sea tangles contain large amount of iodine. However they mistook the low iodine diet as a low salt diet and were not aware of foods and seasonings that are allowed on the low iodine diet. While self-efficacy related to consuming various fruits and vegetables, to choosing potatoes and sweet potatoes for snacks, and restricting consumption of eggs, milk and milk products, and processed foods was rated highly, self-efficacy for preparing foods without using sea salts was rated low. The self-efficacy score increased as their interest on the dietary life and perceived cooking skills were greater. Most perceived barriers toward practicing the low iodine diet were related to preparation of the low iodine menus. As their interest in the dietary life and cooking and perceived cooking skills were greater, the patients perceived barriers on practicing the low iodine diet less. While the patients showed higher self-efficacy and lower barrier perception on selecting foods low in iodine and restricting food high in iodine, they showed lower self-efficacy and higher barrier perceptions on preparing low iodine meals. Clinical dietitians should recognize the gap between what the patients should know and what they really know and identify strategies on how to improve self-efficacy and reduce perceived barriers on the low iodine diet. Recent literature and the findings of the study reveal that incorporating cooking classes into nutrition education for thyroid patients is effective to enhance self-efficacy and to reduce perceived barriers on the low iodine diet.

Determination of 5-HT receptor antagonists, MEFWAY and MPPF using liquid chromatography electrospray ionization tandem mass spectrometry in rat plasma and brain tissue

A simple, selective, and sensitive liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) method was validated for the determination of 4-fluoromethyl-N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-pyridyl)cyclohexane-1-carboxamide (MEFWAY) and 4-fluoro-N-[2-[4-(2-methoxyphenyl)-1-piperazinyl]ethyl]-N-(2-pyridyl)benzamide (MPPF) in rat plasma and brain samples, respectively. Plasma and brain samples were extracted with a mixture of acetonitrile and methanol (1:1, v/v) and then separated on a C(18) column (Gemini 3μm 110Å, 50×2.00mm ID, Phenomenex, USA). Quantitation was performed using LC-ESI-MS/MS in multiple-reaction monitoring (MRM) mode with positive ion electrospray ionization (ESI). The limit of quantification (LOQ) of 5ng/mL and 1ng/mL were obtained in 50μL brain homogenate and plasma, respectively. The analytical linear ranges of this method were 1-4000ng/mL in plasma and 5-4000ng/mL in brain homogenate with a correlation coefficients (R(2)) greater than 0.9993. The intra- and inter-day precision and accuracy values were within the assay validation guideline (lower than 13.0%). The analytes in plasma and brain samples were stable after three freeze-thaw cycles, long-term storage (one month at -80°C), and short-term (4h) storage at room temperature. The present method was successfully applied to plasma-brain pharmacokinetic studies to investigate brain penetration of a single dose of MEFWAY and MPPF in rats.

Evaluation of dopamine transporters and D2 receptors in hemiparkinsonian rat brains in vivo using consecutive PET scans of [18F]FPCIT and [18F]fallypride

The aim of this study was to investigate dopaminergic function in unilaterally lesioned 6-OHDA rats by dual PET radioligands: [(18)F]FPCIT (a dopamine transporter imaging radioligand) and [(18)F]fallypride (a dopamine D2 receptors imaging radioligand). As a result, the brain uptake of [(18)F]FPCIT was significantly reduced and that of [(18)F]fallypride was increased in the ipsilateral striatum (lesion side) of the 6-OHDA rats. These findings implicated that dopamine transporter is down-regulated and dopamine D2 receptor is up-regulated in this hemiparkinsonian rat model.

Initially non-diagnostic ultrasound-guided fine needle aspiration cytology of thyroid nodules: value and management

BACKGROUND

Ultrasound (US)-guided fine needle aspiration cytology (FNAC) is an accurate, reliable, and simple method to identify a thyroid nodule as benign or malignant. However, non-diagnostic cytology results for thyroid nodules are a major limitation of US-guided FNAC.

PURPOSE

To investigate the incidence of thyroid cancer among cases with non-diagnostic results on FNAC and to provide suggestions for the management of thyroid nodules that are initially non-diagnostic by FNAC according to ultrasonographic findings.

MATERIAL AND METHODS

From July 2006 to December 2009, 10,317 thyroid nodules in 6684 consecutive patients underwent US-guided FNAC at our institute. Among these, 871 thyroid nodules (8.4%) were diagnosed as non-diagnostic on initial cytologic evaluation and 196 underwent a second or third FNAC. Twenty-seven thyroid nodules (18.9%) underwent surgery, while 116 thyroid nodules were cytologically confirmed as benign with no remarkable change on follow-up US were included. We retrospectively reviewed the US findings for a total of 143 thyroid nodules (123 benign nodules and 20 malignant nodules). The US features that we compared included composition, echogenicity, margin, calcifications, shape, and underlying echogenicity.

RESULTS

In total, thyroid cancer was diagnosed in 20 nodules (14.0%). The size of the nodule was significantly associated with malignancy (P < 0.05). Most of the sonographically probable benign nodules were found to be benign (97.6%). Suspicious nodules on US were thyroid cancer in 43.2% of cases. Marked hypoechogenicity, microlobulated or irregular margin, microcalcifications, and taller-than-wide shape were significant US findings that correlated with malignancy (P < 0.05). The diagnostic performance of ultrasound for initially non-diagnostic thyroid nodules was as follows: sensitivity of 90.0%, specificity of 65.0%, positive predictive value of 29.5%, and negative predictive value of 97.6%.

CONCLUSION

In terms of management of thyroid nodules with non-diagnostic FNAC cytology, US evaluation is a feasible and useful method for predicting malignancy.

A spinal cord astrocytoma and its concurrent osteoblastic metastases at the time of the initial diagnosis: a case report and literature review

Bone metastasis from a spinal cord astrocytoma has been reported only twice in the English medical literature. It is generally known that bone metastasis is found after the initial diagnosis with/without intervening surgery rather than being found at the time of the diagnosis of astrocytoma. The purpose of this article is to report for the first time a case of concurrent bone metastasis from a spinal cord astrocytoma at the time of diagnosing the spinal cord astrocytoma.

The effect of age on motor deficits and cerebral glucose metabolism of Parkinson's disease

BACKGROUND

No systematic study has been made to separate age-related clinical deterioration and dysfunctional brain areas from those associated with Parkinson's disease (PD).

METHODS

This study included 73 de novo patients with PD and 43 age-matched controls. All subjects underwent [(18)F]-fluorodeoxy glucose (FDG) positron emission tomography studies. The severity of parkinsonian motor deficit was measured using unified PD rating scale (UPDRS) motor scores. Multiple linear regression analysis was used to identify those parkinsonian motor deficits for which severity was correlated with the age of the patients and to locate brain areas in which normalized FDG uptake values were inversely correlated with the age of the subjects.

RESULTS

Patient age was positively correlated with total UPDRS motor scores and with subscores for bradykinesia and axial motor deficits, but not with subscores for tremor and rigidity. In the control group, an age-related decline in glucose uptake was found only in the cingulate cortex. However, in the patient group, an inverse correlation between age and glucose uptake was observed in the prefrontal, cingulate, orbitofrontal, perisylvian areas, caudate, and thalamus.

CONCLUSIONS

In PD, widespread age-related decline in cerebral function may exaggerate the deterioration associated with bradykinesia and the axial motor deficits associated with nigral neuronal loss.

Cerebral cortical areas in which thickness correlates with severity of motor deficits of Parkinson's disease

The pathology of Parkinson's disease (PD) is not confined to the nigrostriatal dopaminergic pathway, but also involves widespread cerebral cortical areas. Such non-nigrostriatal lesions may contribute to disabling dopa-resistant parkinsonian motor deficits. We performed cortical thickness analysis to identify cerebral cortical brain areas in which thickness correlates with the severity of parkinsonian motor deficits. We performed T1-weighted brain magnetic resonance imaging studies in 142 PD patients. Motor scores on the Unified Parkinson's Disease Rating Scale (UPDRS) were measured, and subscores were calculated for bradykinesia, rigidity, tremor, and axial motor deficits. Using FreeSurfer software, we studied cortical areas in which thickness correlates with disease duration or the severity of parkinsonian motor deficits. The cortical thickness of the parieto-temporal association cortex, including the inferior parietal and posterior parietal cortices, showed a negative correlation with disease duration, total UPDRS motor score, and UPDRS subscores for bradykinesia and axial motor deficits. We found no cortical areas in which thickness correlated with subscores for tremor and rigidity. In addition to nigrostriatal dopaminergic deficit, progressive thinning of the parieto-temporal sensory association cortices related to disease duration seems to be related in part to the exacerbation of bradykinesia and the axial motor symptoms of PD.