Patients diagnosed with mild cognitive impairment (MCI) have a higher risk of developing Alzheimer's disease (AD). However, not all such patients develop this kind of dementia. The purpose of this prospective study was to assess whether regional cerebral blood flow (rCBF) patterns measured with technetium-99m ethyl cysteinate dimer single-photon emission tomography ((99m)Tc-ECD SPET) in patients suffering from MCI are useful in predicting progression to AD. The study group comprised 42 patients who fulfilled MCI criteria according to the International Psychogeriatric Association and the Alzheimer's Disease Cooperative Study. rCBF was calculated in 16 regions of interest (ROIs). All patients were clinically assessed for 1-3 years. Twenty-one developed AD (group I) while the initial diagnosis of MCI was retained in the other 21 (group II). ROC curves were designed, and sensitivity, specificity, positive and negative predictive values, and positive and negative likelihood ratios were determined for each ROI. Compared with group II (MCI), group I (AD) showed a significant reduction of relative blood flow (RBF), ranging from 7% to 10%, in the following areas: right and left prefrontal, right and left frontal, right and left parietal, right and left temporal, right and left frontoparietotemporal and left posterior lateral temporal. Left prefrontal, left frontal and left parietal areas showed sensitivities and specificities higher than 75% and areas below the ROC curve close to 80%. This study shows that RBF patterns in the right and left prefrontal, right and left frontal and left parietal areas are sensitive early markers of progression towards AD. Reduction of rCBF in the medial temporal and anterior lateral temporal cortex has no value as a predictor since it also occurs in patients with MCI who remain stable.

The aim of this study was to assess the frequency and severity of respiration-induced curvilinear respiration artifacts (RICA) on coregistered positron emission tomography/computed tomography (PET/CT) images acquired on a combined PET/CT scanner before and after modifying the respiration protocol for CT scanning, with retrospective analysis of two groups of 100 patients each, before and after implementing a respiration protocol with breath-hold (BH) in the normal expiration position for the acquisition of the CT images. The CT data were used as attenuation map and for image co-registration. A ranking of co-registered PET/CT and PET images (including maximum intensity projection) was done by two observers in consensus using a scale from 0 to 3. Zero indicated that no RICA was visible and 1, 2, and 3 described artifact with increasing severity. A significant difference in RICA occurrence was found between the two groups (p<0.0001). There was a 45% decrease of artifact frequency when using the normal expiration protocol and a 68% decrease of grade-2 and grade-3 artifacts (p=0.004). The results of this study suggest that BH during the normal expiration position for CT scanning can be recommended to reduce the occurrence and the severity of RICA on PET/CT.

The combination of functional imaging and neuropsychological tests can diagnose with high sensitivity and specificity if a patient is suffering cognitive impairment in its early stages, and may aid in predicting the risk of developing dementia.

No abstract

No abstract

No abstract

No abstract

No abstract