Determination of the R2* relaxation rate constant for estimating hepatic iron concentration: A customized approach that considers liver fat infiltration.

PURPOSE: Α customized approach to determine R2* relaxation rate for hepatic iron concentration (HIC) estimation is presented, and is evaluated in the context of concurrent liver fat infiltration. METHODS: The proposed method employs a customized acquisition protocol, featuring a 16-echo, gradient-echo sequence, and a bi-exponential least squares fitting that considers baseline noise and uses a cosine function to correct for fat-induced signal oscillation. 193 patients with wide-ranging HIC and liver fat fraction (FF) were imaged at 1.5 T. In severely iron-overload patients, a four-echo train technique was applied to enforce all 16 echoes in the 1.2-4.0 ms range. Acquired data were compared to corresponding results obtained with the IDEAL IQ method. RESULTS: Techniques employed to counter the rapid signal decay in iron-overloaded liver, such as the offset and the truncation methods, have to be combined with the appropriate calibration curve to provide reliable HIC estimation. When high grade steatosis and siderosis co-exist, fat-suppression may downgrade siderosis. A high correlation was observed between data obtained with the proposed technique and the IDEAL IQ method, except from the high R2* region. However, systematic differences were detected. In the concurrent presence of high FF and non-severe iron overload, it is postulated that the bi-exponential model may attribute patient siderosis grading more accurately than IDEAL IQ, while simultaneously providing reliable FF estimation. CONCLUSIONS: The proposed approach is widely available and seems capable of providing reliable R2* measurements regardless of liver steatosis grading, whilst it succeeds in averting significant R2* underestimation in severely iron-overloaded liver.

Association between Siesta (Daytime Sleep), Dietary Patterns and the Presence of Metabolic Syndrome in Elderly Living in Mediterranean Area (Medis Study): The Moderating Effect of Gender.

OBJECTIVES: Several lifestyle parameters including diet, physical activity and sleep were associated in isolation with the presence of Metabolic Syndrome (MetS) in adults, to date there is a paucity of studies which evaluated their combined role aging populations and especially with respect to gender. Therefore, the aim of the present study was to provide a global consideration of the lifestyle factors associated with MetS among elderly individuals. DESIGN: Cross-sectional observational study. SETTING: 21 Mediterranean islands and the rural Mani region (Peloponnesus) of Greece. PARTICIPANTS: during 2005-2015, 2749 older (aged 65-100 years) from were voluntarily enrolled in the study. MEASUREMENTS: Dietary habits, energy intake, physical activity status, socio-demographic characteristics, lifestyle parameters (sleeping and smoking habits) and clinical profile aspects were derived through standard procedures. The presence of MetS was defined using the definition provided by NCEP ATP III (revised) and cluster analysis was used to identify overall dietary habit patterns. RESULTS: The overall prevalence of MetS in the study sample was 36.2%, but occurred more frequently in females (40.0% vs. 31.8%, respectively, p=0.03). Individuals with MetS were more likely to sleep during the day (89.4% vs. 76.8% respectively, p=0.039) and frequent 'siesta' was positively linked to the odds of MetS presence in females (Odds Ratio (OR) =3.43, 95% Confidence Intervals (CI): 1.08-10.9), but not for men (p=0.999). The lower carbohydrate (i.e., 45.2% of total daily energy, 120±16gr/day) dietary cluster was inversely associated with the odds for MetS presence, but only for men (OR=0.094, 95%CI: 0.010-0.883). CONCLUSIONS: Lifestyle parameters including sleep and diet quality are strongly associated with the presence of MetS in elderly cohort, but different their level of influence appears to be different, depending on gender. Further research is needed to better consider the role of lifestyle characteristics in the management of MetS in clinical practice.

Diffusion tensor imaging (DTI) in the detection of white matter lesions in patients with mild cognitive impairment (MCI).

Mild cognitive impairment (MCI) is recognized as a precursor to dementia. The amnestic MCI progresses usually to Alzheimer disease. Amnestic MCI multiple domain (md-MCI) seems to progress more rapidly than amnestic MCI single domain (a-MCI). In an attempt to identify patients at risk, we examined white matter changes in MCI subtypes using diffusion tensor imaging (DTI). We also tried to correlate DTI findings to neuropsychological tests. Forty-four amnestic single domain (a-MCI) patients, 19 amnestic multi domain (md-MCI), and 25 cognitively normal (NC) controls were included in the present study. All participants were assessed clinically using a battery of cognitive tests. DTI was performed to measure fractional anisotropy (FA) and apparent diffusion coefficient (ADC). Areas studied were corpus callosum, posterior cingulum (PC), anterior cingulum (AC), and superior longitudinal fasciculus (SLF). ADC and FA of the above areas were related to the scores of certain neuropsychological tests that evaluate visual and verbal memory. No difference in DTI measurements was found between the two MCI subtypes. ADC in MCI cases was increased in comparison with NC in the genu, PC, right SLF, and left AC. FA was spared. Verbal memory was related to ADC of the genu, PC, right AC and right SLF, and to FA of the left SLF. Visual memory was related to ADC of the genu, PC, right AC, and SLF. The strongest correlation found was between the visual memory and the ADC of the right PC (Spearman ρ = 0.45, p < 0.001). DTI revealed that ADC was increased in certain brain areas in MCI patients. No difference in DTI measurements was found between the two MCI subtypes. DTI indices correlate with cognitive performance.

Nutrient intake in relation to central and overall obesity status among elderly people living in the Mediterranean islands: the MEDIS study.

BACKGROUND AND AIM: The aim of the present work was to evaluate the relationship between energy-generating nutrients and the presence of central and overall obesity after correcting for socio-demographic, lifestyle and clinical characteristics, among healthy elders. METHODS AND RESULTS: During 2005-2007, 553 elderly men and 637 elderly women (mean age 74±7years) from eight Mediterranean islands in Greece and Cyprus, were enrolled. The retrieved information included demographic, bio-clinical and dietary characteristics. MedDietScore assessed adherence to the Mediterranean dietary pattern. The prevalence of obesity was 27% in males and 39% in females (p<0.001), while 73% of males and 87% of females had central obesity. The prevalence of diabetes, hypercholesterolemia and hypertension was higher in the obese than in the non-obese participants (p<0.01). After adjusting for various confounders, a 1% increase in carbohydrate consumption was associated with a 12% (95% CI 0.78-0.99) lower likelihood of having central obesity, while a 1% increase in carbohydrate and protein consumption was associated with a 14% (95% CI 0.78-0.95) and 16% (95% CI 0.72-0.97) lower likelihood of being obese, respectively. Vegetable protein was found to be associated with a 15% (95% CI 0.77-0.93) lower likelihood of being obese while, only low glycemic index carbohydrates seem to be associated with a 6% (95% CI 0.90-0.98) lower likelihood of having central obesity. CONCLUSIONS: The presented findings suggest that a diet high in carbohydrates and vegetable protein is associated with a lower likelihood of being obese and may help elderly people to preserve normal weight.

Long-term animal-protein consumption is associated with an increased prevalence of diabetes among the elderly: the Mediterranean Islands (MEDIS) study.

AIM: The role of animal-protein consumption on the prevalence of diabetes is not yet fully understood. For this reason, this study investigated the relationship between long-term animal-protein intake and diabetes in elderly individuals with no known cardiovascular disease. METHODS: During 2005-2007, 1190 men and women, aged 65-100 years, from Cyprus, Mitilini, Samothraki, Cephalonia, Crete, Lemnos, Corfu and Zakynthos were enrolled into the study. Diabetes was defined as fasting blood glucose ≥ 125 mg/dL or the use of antidiabetic medication. All participants were asked about their dietary habits through a semiquantitative food-frequency questionnaire. Assessment of protein and energy intakes was performed using food-composition tables. RESULTS: After adjusting for age, gender, obesity, history of hypertension, hypercholesterolaemia and dietary habits, a 5% increase in protein intake from meat and meat products was associated with a 34% (OR=1.338, 95% CI: 1.02-1.76) greater likelihood of diabetes, while a 5% increase in total protein intake was associated with a 29% (OR=1.288, 95% CI: 1.00-1.69) greater likelihood of diabetes. No significant associations between diabetes and protein intakes from vegetables and cereals were observed. CONCLUSION: Animal-protein consumption was associated with a higher prevalence of diabetes among the elderly, whereas protein intakes, especially from plant sources, within the recommended range appear to confer considerable protection. This suggests that reducing or controlling the burden of diabetes through dietary means in the elderly should include monitoring their daily protein intake.

Urban environment, physical inactivity and unhealthy dietary habits correlate to depression among elderly living in eastern Mediterranean islands: the MEDIS (MEDiterranean ISlands Elderly) study.

AIMS: To evaluate factors associated with depression in elderly. METHODS: During 2005-2007, 553 men and 637 women (aged 65 to 100 yrs) living in various Greek islands and in Cyprus participated in the study. The sampling was random and multistage (according to age sex distribution of the referent population). Depressive symptoms were evaluated using the Geriatric Depression Scale (GDS). RESULTS: Twenty five per cent of men and 35% of women were classified in the highest GDS category (i.e. GDS score > 10), indicating intense depressive symptoms, while 54% of men and 70% of women scored above the depression cut-off (i.e. GDS score > 5) indicating mild-to-severe depressive symptoms. Among the investigated characteristics, living in urban environment, physical inactivity and history of hypertension were correlated with the presence of depressive symptoms (p < 0.05), after adjusting for various confounders. Moreover, the consumption of fish, vegetables and cereals is more prevalent among people with low or moderate depression (p < 0.05). CONCLUSIONS: The prevalence of depression is quite high between elderly people living in Greek islands and Cyprus. Urban environment that may also interact with sedentarism and unhealthy dietary habits seems to promote depression in the studied population. Efforts to lower the prevalence of depression in the elderly should target on the aforementioned factors that employ functional impairment, social environment and dietary habits.

Frontal brain lobe impairment in obstructive sleep apnoea: a proton MR spectroscopy study.

Patients with obstructive sleep apnoea syndrome frequently have cognitive deficits, especially related to executive functions, which cannot be fully explained by daytime sleepiness and are partial irreversible after nasal continuous positive airway pressure treatment. The causal mechanism of these cognitive deficits is not yet known, but it has been proposed that they are associated with chemical and structural brain cell injury. The aim of this study was to investigate brain metabolism in patients with sleep apnoea syndrome. Twenty-two patients with severe sleep apnoea and 10 healthy volunteers of comparable age were studied using single voxel proton magnetic resonance spectroscopy. Magnetic resonance spectra were obtained from prefrontal cortex, parieto-occipital and frontal periventricular white matter. N-acetylaspartate-to-creatine and choline-to-creatine ratios were significantly lower in the frontal white matter of obstructive sleep apnoea patients when compared to controls. Absolute concentrations of N-acetylaspartate and choline were also significantly reduced in the frontal white matter of patients with sleep apnoea. Frontal lobe white matter lesions are known to be associated with cognitive executive dysfunction. The findings of this study may offer an explanation for the sometimes irreversible cognitive deficits associated with sleep apnoea.

T2 relaxation time study of iron overload in b-thalassemia.

Myocardial iron deposition occurs as a result of blood transfusion therapy in b-thalassemia major patients. Since this deposition causes various cardiac complications, it is of interest to assess the iron content of the myocardium in relation to the clinical picture of the patients. Two different MRI indices were used to achieve this purpose: the T2 relaxation time and the heart/skeletal muscle signal intensity ratio. ECG gated spin echo images were obtained from 54 adult thalassemic patients, with a mean age of 26 (18-44) years, at TE = 22 ms and 60 ms, using a 1.5 T system. Patients were divided into 2 groups (A and B), according to their serum ferritin levels (> or < 2000 ng ml(-1)). Results were compared with nine controls, with a mean age of 25 (18-43) years. Heart T2 relaxation time in controls (44.3 +/- 3.5 ms) was higher than in group A (29.9 +/- 5.7 ms, P < 0.001) and group B (33.4 +/- 6.8 ms, P < 0.01). T2 was measurable in 66% of group A and 83% of group B patients. The heart/muscle signal intensity ratio in group A (0.45 +/- 0.27) was lower than in group B (0.82 +/- 0.33, P < 0.001) and the controls (1.15 +/- 0.20, P < 0.001). The heart/muscle signal intensity ratio was measurable in 94% of the patients and demonstrated an inverse relationship with the serum ferritin levels (r = -0.52, P < 0.01). This study indicates that the heart/muscle ratio is a sensitive index of iron overload and it can be measured in the majority of patients, irrespective of tissue iron concentration, thereby offering an advantage over the use of T2 relaxation time.

In vivo proton MR spectroscopy: the diagnostic possibilities of lipid resonances in brain tumors.

The lipid resonances detected in proton MR spectra of brain tumors were evaluated from the diagnostic point of view. Seventy five non-radiated brain tumors were examined in vivo and lipids were detected in 29% of anaplastic astrocytomas grade III, 60% of glioblastomas multiforme and 50% of metastatic tumors. Lipids were also detected in all brain abscesses and an epidermoid cyst. No lipids were detected in benign tumors (low grade and pilocytic astrocytomas, oligodendrogliomas, meningiomas, pituitary adenomas etc.). Thus, the presence of lipids in the MR spectra is indicative of malignancy (with a few exceptions).

Proton magnetic resonance spectroscopy in patients with glial tumors: a multicenter study.

The authors represent a cooperative group of 15 institutions that examined the feasibility of using metabolic features observed in vivo with 1H-magnetic resonance (MR) spectroscopy to characterize brain tumors of the glial type. The institutions provided blinded, centralized MR spectroscopy data processing long with independent central review of MR spectroscopy voxel placement, composition and contamination by brain, histopathological typing using current World Health Organization criteria, and clinical data. Proton 1H-MR spectroscopy was performed using a spin-echo technique to obtain spectra from 8-cc voxels in the tumor and when feasible in the contralateral brain. Eighty-six cases were assessable, 41 of which had contralateral brain spectra. Glial tumors had significantly elevated intensities of choline signals, decreased intensities of creatine signals, and decreased intensities of N-acetylaspartate compared to brain. Choline signal intensities were highest in astrocytomas and anaplastic astrocytomas, and creatine signal intensities were lowest in glioblastomas. However, whether expressed relative to brain or as intratumoral ratios, these metabolic characteristics exhibited large variations within each subtype of glial tumor. The resulting overlaps precluded diagnostic accuracy in the distinction of low-and high-grade tumors. Although the extent of contamination of the 1H-MR spectroscopy voxel by brain had a marked effect on metabolite concentrations and ratios, selection of cases with minimal contamination did not reduce these overlaps. Thus, each type and grade of tumor is a metabolically hetero-geneous group. Lactate occurred infrequently and in all grades. Mobile lipids, on the other hand, occurred in 41% of high-grade tumors with higher mean amounts found in glioblastomas. This result, coupled with the recent demonstration that intratumoral mobile lipids correlate with microscopic tumor cell necrosis, leads to the hypothesis that mobile lipids observed in vivo in 1H-MR spectroscopy may correlate independently with prognosis of individual patients.

Magnetic resonance angiography compared to intra-arterial digital subtraction angiography in patients with subarachnoid haemorrhage.

In order to evaluate the sensitivity and specificity of magnetic resonance angiography (MRA) in spontaneous subarachnoid haemorrhage, 14 patients with recent haemorrhage verified by CT or lumbar puncture were investigated with both selective intra-arterial digital subtraction angiography (IA-DSA) and MRA by two independent teams, each having the same preangiographic information. The results were compared with each other and whenever possible (all positive cases except one) with those of surgical intervention. Seven patients were identified by MRA and IA-DSA as having a single aneurysm on the circle of Willis, 1 an aneurysm of the posterior inferior cerebellar artery 1 an aneurysm of the internal carotid artery (siphon) and 2 patients with two aneurysms on the circle of Willis. MRA and IA-DSA both failed to demonstrate aneurysms in 2 cases. Three patients had negative results on both methods and no surgical intervention was attempted. The aneurysms ranged from 0.3 to 1.5 cm in size. In most cases there was agreement between MRA and DSA, leading us to believe that, if the proper protocols are followed, MRA is a powerful alternative to other established methods in the detection of intracranial aneurysms. At this stage it will not replace IA-DSA prior to surgery, but the ability to obtain various projections using 3D MRA may improve surgical planning.

Proton nuclear magnetic resonance spectroscopy of plasma lipoproteins in head and neck cancer patients.

Proton nuclear magnetic resonance spectroscopy was used to evaluate changes in plasma lipoproteins in patients with squamous cell head and neck cancer. Plasma from 14 patients was analyzed by proton nuclear magnetic resonance spectroscopy, and line widths and fast and slow methyl and methylene transverse relaxation values were obtained. In addition, the lipid and lipoprotein concentrations in the sera of these patients were measured by standard biochemical techniques. Preliminary results suggested that squamous cell carcinomas of the head and neck with nodal metastases are associated with measureable changes in slow methylene transverse relaxation values, as compared with controls. These findings indicate the presence of a new lipoprotein complex in patients with squamous cell carcinomas of the head and neck with nodal metastases.

Magnetic resonance imaging versus computed tomography of leukocoric eyes and use of in vitro proton magnetic resonance spectroscopy of retinoblastoma.

To evaluate the usefulness of magnetic resonance imaging (MRI) in the evaluation of leukocoric eyes, the authors studied 28 patients with either leukocoria or intraocular mass with a 1.5-tesla (T) MRI imager. Retinoblastomas were reliably distinguished from Coats' disease, toxocariasis, and persistent hyperplastic primary vitreous on the basis of MRI findings. Calcification cannot be reliably detected on MRI scans. Lesions elevated less than 4 mm may not be detected reliably by MRI at this time. Computed tomography (CT) can detect calcification with a high degree of accuracy. Retinoblastomas appeared as moderately hyperintense masses on T1- and proton-weighted MRIs. They became hypointense in T2-weighted MRIs. This MRI characteristic is similar to that of uveal melanoma. Intraocular calcification in children especially younger than 3 years of age is highly suggestive of retinoblastoma. In the diagnosis of retinoblastoma, MRI is not as specific as CT because of its lack of sensitivity in detecting calcification. However, MRI, because of its superior contrast resolution, offers more information in the differentiation of pathologic intraocular conditions responsible for leukocoria. The authors also describe their preliminary work of in vitro proton magnetic resonance spectroscopy of eyes with retinoblastoma and an eye with uveal melanoma in an 18-year-old black woman.

Potential use of in vivo proton spectroscopy for head and neck lesions.

Early experience with in vivo MRS has shown its potential for obtaining biochemical information, thus enhancing the diagnostic sensitivity of MRI studies. Further work on combined MRI and in vivo MRS is needed, with the goal of characterization and abnormal conditions according to their spectral patterns and for identification of tumor markers. We presented in this communication our preliminary results. It seems that the resonance from melanin can be used as a marker for melanotic tumors.

17O NMR investigation of the hydration of L-alanine and L-proline in water/Me2SO mixtures.

The hydration state of L-Alanine and L-Proline has been assessed via 17O NMR. At neutral and basic pH, two water molecules are hydrogen bonded at the carboxylate group, one to each oxygen, whereas a third water molecule is hydrogen bonded to the protonated COOH group at acidic pH, via the hydroxyl hydrogen. The possible formation of dimers and/or higher complexes in DMSO is indicated not only from the chemical shift but also from the linewidth of the amino acids.