Visual-statistical interpretation of (18)F-FDG-PET images for characteristic Alzheimer patterns in a multicenter study: inter-rater concordance and relationship to automated quantitative evaluation.

BACKGROUND AND PURPOSE: The role of (18)F-FDG-PET in the diagnosis of Alzheimer disease is increasing and should be validated. The aim of this study was to assess the inter-rater variability in the interpretation of (18)F-FDG-PET images obtained in the Japanese Alzheimer's Disease Neuroimaging Initiative, a multicenter clinical research project. MATERIALS AND METHODS: This study analyzed 274 (18)F-FDG-PET scans (67 mild Alzheimer disease, 100 mild cognitive impairment, and 107 normal cognitive) as baseline scans for the Japanese Alzheimer's Disease Neuroimaging Initiative, which were acquired with various types of PET or PET/CT scanners in 23 facilities. Three independent raters interpreted all PET images by using a combined visual-statistical method. The images were classified into 7 (FDG-7) patterns by the criteria of Silverman et al and further into 2 (FDG-2) patterns. RESULTS: Agreement among the 7 visual-statistical categories by at least 2 of the 3 readers occurred in >94% of cases for all groups: Alzheimer disease, mild cognitive impairment, and normal cognitive. Perfect matches by all 3 raters were observed for 62% of the cases by FDG-7 and 76 by FDG-2. Inter-rater concordance was moderate by FDG-7 (κ = 0.57) and substantial in FDG-2 (κ = 0.67) on average. The FDG-PET score, an automated quantitative index developed by Herholz et al, increased as the number of raters who voted for the AD pattern increased (ρ = 0.59, P < .0001), and the FDG-PET score decreased as those for normal pattern increased (ρ = -0.64, P < .0001). CONCLUSIONS: Inter-rater agreement was moderate to substantial for the combined visual-statistical interpretation of (18)F-FDG-PET and was also significantly associated with automated quantitative assessment.

Integrating imaging findings in evaluating the post-chemotherapy brain.

Cognitive complaints following cancer and cancer therapy are common. Many studies have investigated the effects of chemotherapy on the brain. However, the mechanisms for the associated cognitive impairment are not well understood. Some studies have also included brain imaging to investigate potential neurological substrates of cognitive changes. This review examines recent neuroimaging studies on cancer- and chemotherapy-related cognitive dysfunction in non-central nervous system cancers and compares findings across imaging modalities. Grey matter volume reductions and decreases in white matter integrity are seen after exposure to adjuvant chemotherapy for breast cancer, and functional studies have illuminated both hypo- and hyperactivations in many of the same regions months to years following therapy. These comparisons can assist in further characterizing the dysfunction reported by patients and contribute to a better understanding of the mechanisms involved.

The association between pro-inflammatory cytokines, regional cerebral metabolism, and cognitive complaints following adjuvant chemotherapy for breast cancer.

To examine relationships following adjuvant chemotherapy between circulating pro-inflammatory cytokines, regional cerebral metabolism, and cognitive complaints in early stage breast cancer patients. 33 breast cancer patients who had completed initial treatment (surgery, ± radiation, 23 chemotherapy, 10 no chemotherapy) obtained resting (18)F-FDG PET/CT brain imaging at baseline and 1 year later. Pro-inflammatory cytokine markers (IL-1ra, sTNF-RII, CRP, and IL-6) and cognitive complaints were also assessed at both time points. At baseline, consistent correlations were seen between the left medial frontal and right inferior lateral anterior temporal cortices and inflammatory markers within the chemotherapy group, and not in the no chemotherapy group. After 1 year, correlations persisted in the medial frontal cortex and the temporal cortex, the latter shifting superiorly. Both of these regional correlations demonstrated the highest levels of significance when looking across the 1 year time frame (IL-1ra: peak voxel p < 0.0005; cluster size p < 0.0005, p = 0.001 after correction (medial prefrontal), p < 0.0005; cluster size p = 0.001, p = 0.029 corr. (anterior temporal), sTNF-RII: p < 0.0005; cluster size p = 0.001, p = 0.040 corr. (medial prefrontal)). Positive correlations were also seen within the chemotherapy group between baseline memory complaints and the medial frontal (p < 0.0005; cluster size p < 0.0005, p < 0.0005 corr.) and anterior temporal (p < 0.0005; cluster size p < 0.0005, p = 0.002 corr.) cortices at baseline and 1 year later. Metabolism in the medial prefrontal cortex and anterior temporal cortex was found to correlate with both memory complaints and cytokine marker levels in chemotherapy patients.

Does tumor necrosis factor-alpha (TNF-α) play a role in post-chemotherapy cerebral dysfunction?

Post-chemotherapy treated cancer patients frequently report cognitive difficulties. The biology of this phenomenon is poorly understood, with uncertainty about possible direct toxic effects on the brain, secondary effects from systemic inflammation, host factors/genetic predisposition to cognitive complaints, or hormonal changes influencing cognitive function. To elucidate possible mechanisms associated with post-treatment cognitive dysfunction among breast cancer survivors, in 2007 we established a prospective, longitudinal, observational cohort study of early stage breast cancer patients, recruited at the end of initial treatments (primary treatment exposure included surgery, ± radiation, ± chemotherapy), and prior to the initiation of adjuvant endocrine therapy. We assessed cognitive complaints, neuropsychological (NP) test performance, markers of inflammation, and brain imaging at baseline, 6 months and 12 months after enrollment. In this analysis of data from the first 93 patients enrolled in the cohort study, we focus on the relationship of circulating levels of proinflammatory cytokines to cerebral functioning and chemotherapy exposure. Among the proinflammatory cytokines tested (IL-1 ra, sTNF-RII, CRP, and IL-6) at baseline, only sTNF-RII was increased among chemotherapy exposed patients, with a significant decline in the year after treatment (p=0.003). Higher baseline sTNF-RII in chemotherapy patients was significantly associated with increased memory complaints. In chemotherapy exposed patients, the longitudinal decline in sTNF-RII was significantly correlated with fewer memory complaints over 12 months (r=-0.34, p=0.04). Higher baseline sTNF-RII was also associated with relatively diminished brain metabolism in the inferior frontal cortex (r=-0.55, p=0.02), as well as relatively increased inferior frontal metabolism after 1 year, in chemotherapy-exposed subjects. These preliminary findings suggest that post-chemotherapy increases in TNF-α may be playing an important role in the manifestations of cognitive complaints in breast cancer survivors.

Assessment of dementia risk in aging adults using both FDG-PET and FDDNP-PET imaging.

BACKGROUND: In a previous study, positron emission tomography (PET) with 2-(1-{6-[(2-[F-18]fluoroethyl)(methyl)amino]-2-naphthyl}ethylidene)malononitrile (FDDNP), a molecule that binds to plaques and tangles in vitro, identified three subgroups of non-demented subjects according to FDDNP binding patterns: low global (LG) binding; high frontal, parietal, medial temporal binding (HF/PA); and high medial and lateral temporal and posterior cingulate (HT/PC) binding. In this follow-up investigation, we compared 2-deoxy-2-[F-18]fluoro- d-glucose (FDG)-PET cerebral metabolic patterns in the three FDDNP-PET binding subgroups. METHODS: Fifty-four subjects with normal aging (N = 28) or amnestic forms of mild cognitive impairment (N = 26) underwent FDDNP-PET and FDG-PET scanning. Subjects in the LG, HF/PA, and HT/PC FDDNP subgroups were compared according to visual ratings, statistical parametric mapping, and automated region of interest analyses of their FDG-PET data. RESULTS: The FDDNP-PET subgroups demonstrated different glucose metabolic patterns according to visual ratings, region of interest, and statistical parametric mapping analyses of FDG-PET data. The LG FDDNP subgroup showed no areas of significant hypometabolism relative to the other subgroups and had low Alzheimer's disease risk by FDG-PET standards. The HF/PA FDDNP subgroup demonstrated hypometabolism in bilateral inferior parietal/parietotemporal, bilateral posterior cingulate, perisylvian, mid-temporal gyrus, and dorsolateral prefrontal regions, which is a pattern suggestive of high Alzheimer's disease risk. The HT/PC FDDNP subgroup demonstrated heterogeneous FDG-PET patterns with predominant anterior frontal and anterior temporal hypometabolism, suggestive of mixed etiologies, including fronto-temporal dementia risk. CONCLUSIONS: The FDG-PET data provided independent validation that different patterns of FDDNP-PET binding in non-demented individuals may be associated with differential dementia risk.

Brain glucose metabolism in hypothyroidism: a positron emission tomography study before and after thyroid hormone replacement therapy.

CONTEXT: Hypothyroidism is frequently associated with subtle behavioral and psychiatric symptoms. The consequences of inadequate thyroid hormone availability to brain metabolism are poorly understood. OBJECTIVE: This study assessed the relationships between neuropsychiatric symptoms and changes in relative regional cerebral glucose metabolism in hypothyroid patients undergoing thyroid hormone replacement therapy. DESIGN, SETTING, AND OUTCOME MEASURE: Relative regional cerebral glucose metabolism was compared in 13 previously untreated hypothyroid patients and 10 healthy control participants. Effects of thyroid hormone replacement therapy (levothyroxine, 3 months) were assessed using neuropsychiatric measures and positron emission tomography with [(18)F]fluorodeoxyglucose. RESULTS: Before treatment, hypothyroid patients exhibited lower regional activity than control subjects in the bilateral amygdala, hippocampus, and perigenual anterior cingulate cortex (ACC), left subgenual ACC, and right posterior cingulate cortex. Severity of depressive symptoms covaried negatively with pretreatment activity in the bilateral middle frontal gyrus and right subgenual and dorsal ACC. Thyroid hormone replacement therapy abolished pretreatment group differences in regional activity, robustly increased activity in the ventral ACC, and significantly reduced both clinician-rated and self-rated behavioral and psychiatric symptoms. Increased activity within the ventral ACC was associated with reduced somatic complaints, whereas increased activity within the dorsal ACC was associated with reduced depressive symptoms. CONCLUSIONS: Reduction of the behavioral complaints during thyroid hormone therapy is associated with a restoration of metabolic activity in brain areas that are integral to the regulation of affect and cognition. The findings suggest that thyroid hormone modulates regional glucose metabolism and psychiatric symptoms in the mature brain.

Computer simulations suggest that acute correction of hyperglycaemia with an insulin bolus protocol might be useful in brain FDG PET.

AIM: FDG PET in hyperglycaemic subjects often suffers from limited statistical image quality, which may hamper visual and quantitative evaluation. In our study the following insulin bolus protocol is proposed for acute correction of hyperglycaemia (>7.0 mmol/l) in brain FDG PET. (i) Intravenous bolus injection of short-acting insulin, one I.E. for each 0.6 mmol/l blood glucose above 7.0. (ii) If 20 min after insulin administration plasma glucose is