18F-Florbetaben PET/CT to Assess Alzheimer's Disease: A new Analysis Method for Regional Amyloid Quantification.

BACKGROUND AND PURPOSE: While AD can be definitively confirmed by postmortem histopathologic examination, in vivo imaging may improve the clinician's ability to identify AD at the earliest stage. The aim of the study was to test the performance of amyloid PET using new processing imaging algorithm for more precise diagnosis of AD. METHODS: Amyloid PET results using a new processing imaging algorithm (MRI-Less and AAL Atlas) were correlated with clinical, cognitive status, CSF analysis, and other imaging. The regional SUVR using the white matter of cerebellum as reference region and scores from clinical and cognitive tests were used to create ROC curves. Leave-one-out cross-validation was carried out to validate the results. RESULTS: Forty-four consecutive patients with clinical evidence of dementia, were retrospectively evaluated. Amyloid PET scan was positive in 26/44 patients with dementia. After integration with 18F-FDG PET, clinical data and CSF protein levels, 22 of them were classified as AD, the remaining 4 as vascular or frontotemporal dementia. Amyloid and FDG PET, CDR 1, CSF Tau, and p-tau levels showed the best true positive and true negative rates (amyloid PET: AUC = .85, sensitivity .91, specificity .79). A SUVR value of 1.006 in the inferior frontal cortex and of 1.03 in the precuneus region was the best cutoff SUVR value and showed a good correlation with the diagnosis of AD. Thirteen of 44 amyloid PET positive patients have been enrolled in clinical trials using antiamyloid approaches. CONCLUSIONS: Amyloid PET using SPM-normalized SUVR analysis showed high predictive power for the differential diagnosis of AD.

Analyzing histopathological features of rare charcot-marie-tooth neuropathies to unravel their pathogenesis.

BACKGROUND: Charcot-Marie-Tooth (CMT) neuropathies are very heterogeneous disorders from both a clinical and genetic point of view. The CMT genes identified so far encode different proteins that are variably involved in regulating Schwann cells and/or axonal functions. However, the function of most of these proteins still remains to be elucidated. OBJECTIVE: To characterize a large cohort of patients with demyelinating, axonal, and intermediate forms of CMT neuropathy. DESIGN: A cohort of 131 unrelated patients were screened for mutations in 12 genes responsible for CMT neuropathies. Demyelinating, axonal, and intermediate forms of CMT neuropathy were initially distinguished as usual on the basis of electrophysiological criteria and clinical evaluation. A sural nerve biopsy was also performed for selected cases. Accordingly, patients underwent first-level analysis of the genes most frequently mutated in each clinical form of CMT neuropathy. RESULTS: Although our cohort had a particularly high percentage of cases of rare axonal and intermediate CMT neuropathies, we found mutations in 40% of patients. Among identified changes, 7 represented new mutations occurring in the MPZ, GJB1, EGR2, MFN2, NEFL, and HSBP1/HSP27 genes. Histopathological analysis performed in selected cases revealed morphological features, which correlated with the molecular diagnosis and provided evidence of the underlying pathogenetic mechanism. CONCLUSION: Clinical and pathological analysis of patients with CMT neuropathies contributes to our understanding of the molecular mechanisms of CMT neuropathies.

Structural and metabolic changes in the brain of patients with upper motor neuron disorders: a multiparametric MRI study.

Our objective was to assess and compare the diagnostic sensitivity of conventional MRI (cMRI), magnetization transfer imaging (MTI), diffusion-weighted imaging (DWI), and proton magnetic resonance spectroscopic imaging ((1)H-MRSI) in patients with amyotrophic lateral sclerosis (ALS) and primary lateral sclerosis (PLS). Thirty-eight ALS patients, nine PLS patients, and 22 healthy controls were enrolled. cMRI, MTI, DWI and (1)H-MRSI were obtained. ALS patients were classified as advanced phase (Ap)-ALS (definite+probable) and early phase (Ep)-ALS (possible+probable-laboratory supported). cMRI was highly sensitive in detecting corticospinal tract (CST) hyperintensities in Ap-ALS (63.4%) and PLS (71.9%), but it was poorly sensitive in Ep-ALS (17.1%). Hyperintensity on proton density-weighted images correlated with ALS severity (p=0.02). CST apparent diffusion coefficient was significantly increased in ALS (p<0.01) and PLS (p=0.02) versus controls. The N-acetylaspartate/creatine ratio was significantly reduced in the motor cortex of patients versus controls (p< or = 0.01 in PLS, p=0.02 in Ap-ALS). The study shows the utility of cMRI for diagnosing ALS. Nevertheless, MRI sensitivity is limited at the early stages of the disease. In these cases, DWI and (1)H-MRSI seem to have the potential to ameliorate the patients' work-up and estimate the nature and extent of the underlying pathological damage.

Extrapyramidal stiffness in patients with amyotrophic lateral sclerosis.

There is accumulating evidence that ALS is a multisystem degenerative disease, raising the question of whether some symptoms are of extrapyramidal origin. The objective was to better characterize the type of stiffness in a series of ALS patients and to study correlations with balance and postural impairment. We studied ALS patients who exhibited stiffness without noticeable motor deficit in the lower limbs. We analyzed the response to manual stretch velocity to differentiate between extrapyramidal (rigidity) or pyramidal (spasticity) stiffness, shortening reaction in the tibialis anterior muscles (abolished in pyramidal diseases and exaggerated in extrapyramidal diseases) and balance and posture impairment (UPDRS and Berg's scale). After a preliminary inter-rater reliability study, 39 consecutive ALS patients were prospectively recruited. Each patient was randomly assigned to one or other of two investigators who evaluated either stiffness or balance impairment. In the lower limbs, rigidity was observed in at least one muscle in 27/39 patients (69%), and shortening reaction was exaggerated in 20/39 patients (51%). Both were correlated with balance and posture impairment (UPDRS and Berg's scale, P < 0.001). This study suggests that extrapyramidal involvement plays a role in stiffness and balance impairment in a subset of ALS patients.