Age-Related Metabolic Profiles in Cognitively Healthy Elders: Results from a Voxel-Based [(18)F]Fluorodeoxyglucose-Positron-Emission Tomography Study with Partial Volume Effects Correction

BACKGROUND AND PURPOSE: Functional brain variability has been scarcely investigated in cognitively healthy elderly subjects, and it is currently debated whether previous findings of regional metabolic variability are artifacts associated with brain atrophy. The primary purpose of this study was to test whether there is regional cerebral age-related hypometabolism specifically in later stages of life. MATERIALS AND METHODS: MR imaging and FDG-PET data were acquired from 55 cognitively healthy elderly subjects, and voxel-based linear correlations between age and GM volume or regional cerebral metabolism were conducted by using SPM5 in images with and without correction for PVE. To investigate sex-specific differences in the pattern of brain aging, we repeated the above voxelwise calculations after dividing our sample by sex. RESULTS: Our analysis revealed 2 large clusters of age-related metabolic decrease in the overall sample, 1 in the left orbitofrontal cortex and the other in the right temporolimbic region, encompassing the hippocampus, the parahippocampal gyrus, and the amygdala. The division of our sample by sex revealed significant sex-specific age-related metabolic decrease in the left temporolimbic region of men and in the left dorsolateral frontal cortex of women. When we applied atrophy correction to our PET data, none of the above-mentioned correlations remained significant. CONCLUSIONS: Our findings suggest that age-related functional brain variability in cognitively healthy elderly individuals is largely secondary to the degree of regional brain atrophy, and the findings provide support to the notion that appropriate PVE correction is a key tool in neuroimaging investigations.

The Relationship between Intraocular Pressure Reduction and Rates of Progressive Visual Field Loss in Eyes with Optic Disc Hemorrhage

Purpose: To evaluate rates of visual field progression in eyes with optic disc hemorrhages and the effect of intraocular pressure (IOP) reduction on these rates. Design: Observational cohort study. Participants: The study included 510 eyes of 348 patients with glaucoma who were recruited from the Diagnostic Innovations in Glaucoma Study (DIGS) and followed for an average of 8.2 years. Methods: Eyes were followed annually with clinical examination, standard automated perimetry visual fields, and optic disc stereophotographs. The presence of optic disc hemorrhages was determined on the basis of masked evaluation of optic disc stereophotographs. Evaluation of rates of visual field change during follow-up was performed using the visual field index (VFI). Main Outcome Measures: The evaluation of the effect of optic disc hemorrhages on rates of visual field progression was performed using random coefficient models. Estimates of rates of change for individual eyes were obtained by best linear unbiased prediction (BLUP). Results: During follow-up, 97 (19%) of the eyes had at least 1 episode of disc hemorrhage. The overall rate of VFI change in eyes with hemorrhages was significantly faster than in eyes without hemorrhages (-0.88%/year vs. -0.38%/year, respectively, P < 0.001). The difference in rates of visual field loss pre- and post-hemorrhage was significantly related to the reduction of IOP in the post-hemorrhage period compared with the pre-hemorrhage period (r = -0.61; P < 0.001). Each 1 mmHg of IOP reduction was associated with a difference of 0.31%/year in the rate of VFI change. Conclusions: There was a beneficial effect of treatment in slowing rates of progressive visual field loss in eyes with optic disc hemorrhage. Further research should elucidate the reasons why some patients with hemorrhages respond well to IOP reduction and others seem to continue to progress despite a significant reduction in IOP levels. Financial Disclosure(s): Proprietary or commercial disclosure may be found after the references. Ophthalmology 2010; 117: 2061-2066 (C) 2010 by the American Academy of Ophthalmology.

Cost Effectiveness of Positron Emission Tomography in Patients With Hodgkin`s Lymphoma in Unconfirmed Complete Remission or Partial Remission After First-Line Therapy

Purpose To assess the cost effectiveness of fluorine-18-fluorodeoxyglucose positron emission tomography (FDG-PET) in patients with Hodgkin`s lymphoma (HL) with unconfirmed complete remission (CRu) or partial remission (PR) after first-line treatment. Patients and Methods One hundred thirty patients with HL were prospectively studied. After treatment, all patients with CRu/PR were evaluated with FDG-PET. In addition, PET-negative patients were evaluated with standard follow-up, and PET-positive patients were evaluated with biopsies of the positive lesions. Local unit costs of procedures and tests were evaluated. Cost effectiveness was determined by evaluating projected annual economic impact of strategies without and with FDG-PET on HL management. Results After treatment, CRu/PR was observed in 50 (40.0%) of the 127 patients; the sensitivity, specificity, and positive and negative predictive values of FDG-PET were 100%, 92.0%, 92.3%, and 100%, respectively (accuracy of 95.9%). Local restaging costs without PET were $350,050 compared with $283,262 with PET, a 19% decrease. The incremental cost-effectiveness ratio is -$3,268 to detect one true case. PET costs represented 1% of total costs of HL treatment. Simulated costs in the 974 patients registered in the 2008 Brazilian public health care database showed that the strategy including restaging PET would have a total program cost of $56,498,314, which is $516,942 less than without restaging PET, resulting in a 1% cost saving. Conclusion FDG-PET demonstrated 95.9% accuracy in restaging for patients with HL with CRu/PR after first-line therapy. Given the observed probabilities, FDG-PET is highly cost effective and would reduce costs for the public health care program in Brazil.

Quantitative myocardial contrast echocardiography during pharmacological stress for diagnosis of coronary artery disease: a systematic review and meta-analysis of diagnostic accuracy studies

Aims We conducted a meta-analysis to evaluate the accuracy of quantitative stress myocardial contrast echocardiography (MCE) in coronary artery disease (CAD). Methods and results Database search was performed through January 2008. We included studies evaluating accuracy of quantitative stress MCE for detection of CAD compared with coronary angiography or single-photon emission computed tomography (SPECT) and measuring reserve parameters of A, beta, and A beta. Data from studies were verified and supplemented by the authors of each study. Using random effects meta-analysis, we estimated weighted mean difference (WMD), likelihood ratios (LRs), diagnostic odds ratios (DORs), and summary area under curve (AUC), all with 95% confidence interval (0). Of 1443 studies, 13 including 627 patients (age range, 38-75 years) and comparing MCE with angiography (n = 10), SPECT (n = 1), or both (n = 2) were eligible. WMD (95% CI) were significantly less in CAD group than no-CAD group: 0.12 (0.06-0.18) (P < 0.001), 1.38 (1.28-1.52) (P < 0.001), and 1.47 (1.18-1.76) (P < 0.001) for A, beta, and A beta reserves, respectively. Pooled LRs for positive test were 1.33 (1.13-1.57), 3.76 (2.43-5.80), and 3.64 (2.87-4.78) and LRs for negative test were 0.68 (0.55-0.83), 0.30 (0.24-0.38), and 0.27 (0.22-0.34) for A, beta, and A beta reserves, respectively. Pooled DORs were 2.09 (1.42-3.07), 15.11 (7.90-28.91), and 14.73 (9.61-22.57) and AUCs were 0.637 (0.594-0.677), 0.851 (0.828-0.872), and 0.859 (0.842-0.750) for A, beta, and A beta reserves, respectively. Conclusion Evidence supports the use of quantitative MCE as a non-invasive test for detection of CAD. Standardizing MCE quantification analysis and adherence to reporting standards for diagnostic tests could enhance the quality of evidence in this field.

Utility of Ictal Single Photon Emission Computed Tomography in Mesial Temporal Lobe Epilepsy With Hippocampal Atrophy: A Randomized Trial

BACKGROUND: The development of newer diagnostic technologies has reduced the need for invasive electroencephalographic (EEG) studies in identifying the epileptogenic zone, especially in adult patients with mesial temporal lobe epilepsy and hippocampal sclerosis (MTLE-HS). OBJECTIVE: To evaluate ictal single photon emission computed tomography (SPECT) in the evaluation and treatment of patients with MTLE-HS. METHODS: MTLE patients were randomly assigned to those with (SPECT, n = 124) and without ictal SPECT (non-SPECT, n = 116) in an intent-to-treat protocol. Primary end points were the proportion of patients with invasive EEG studies, and those offered surgery. Secondary end points were the length of hospital stay and the proportion of patients with secondarily generalized seizures (SGS) during video-EEG, postsurgical seizure outcome, and hospital cost. RESULTS: The proportion of patients offered surgery was similar in the SPECT (85%) and non-SPECT groups (81%), as well as the proportion that had invasive EEG studies (27% vs 23%). The mean duration of hospital stay was 1 day longer for the SPECT group (P < 0.001). SGS occurred in 51% of the SPECT and 26% of the non-SPECT group (P < 0.001). The cost of the presurgical evaluation was 35% higher for the SPECT compared with the non-SPECT group (P < 0.001). The proportion of patients seizure-free after surgery was similar in the SPECT (59%) compared with non-SPECT group (54%). CONCLUSION: Ictal-SPECT did not add localizing value beyond what was provided by EEG-video telemetry and structural MRI that altered the surgical decision and outcome for MTLE-HS patients. Ictal-SPECT increased hospital stay was associated with increased costs and a higher chance of SGS during video-EEG monitoring. These findings support the notion that a protocol including ictal SPECT is equivalent to one without SPECT in the presurgical evaluation of adult patients with MTLE-HS.

Ictal technetium-99 m ethyl cysteinate dimer single-photon emission tomographic findings in epileptic patients with polymicrogyria syndromes: A Subtraction of ictal-interictal SPECT coregistered to MRI study

Purpose To describe the ictal technetium-99 m-ECD SPECT findings in polymicrogyria syndromes (PMG) during epileptic seizures. Methods We investigated 17 patients with PMG syndromes during presurgical workup, which included long-term video-electroencephalographic (EEG) monitoring, neurological and psychiatry assessments, invasive EEG, and the subtraction of ictal-interictal SPECT coregistered to magnetic resonance imaging (MRI) (SISCOM). Results The analysis of the PMG cortex, using SISCOM, revealed intense hyperperfusion in the polymicrogyric lesion during epileptic seizures in all patients. Interestingly, other localizing investigations showed heterogeneous findings. Twelve patients underwent epilepsy surgery, three achieved seizure-freedom, five have worthwhile improvement, and four patients remained unchanged. Conclusions Our study strongly suggests the involvement of PMG in seizure generation or early propagation. Both conventional ictal single-photon emission computed tomography (SPECT) and SISCOM appeared as the single contributive exam to suggest the localization of the epileptogenic zone. Despite the limited number of resective epilepsy surgery in our study (n=9), we found a strong prognostic role of SISCOM in predicting surgical outcome. This result may be of great value on surgical decision-making of whether or not the whole or part of the PMG lesion should be surgically resected.

Micro-Positron Emission Tomography in the Evaluation of Trypanosoma cruzi-Induced Heart Disease: Comparison with Other Modalities

Noninvasive assessment of cardiac structure and function is essential to understand the natural course of murine infection with Trypanosoma cruzi. Magnetic resonance imaging (MRI) and echocardiography have been used to monitor anatomy and function; positron emission tomography (PET) is ideal for monitoring metabolic events in the myocardium. Mice infected with T. cruzi (Brazil strain) were imaged 15-100 days post infection (dpi). Quantitative (18)F-FDG microPET imaging, MRI and echocardiography were performed and compared. Tracer ((18)F-FDG) uptake was significantly higher in infected mice at all days of infection, from 15 to 100 dpi. Dilatation of the right ventricular chamber was observed by MRI from 30 to 100 dpi in infected mice. Echocardiography revealed significantly reduced ejection fraction by 60 dpi. Combination of these three complementary imaging modalities makes it possible to noninvasively quantify cardiovascular function, morphology, and metabolism from the earliest days of infection through the chronic phase.