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Objective: We correlate and evaluate the accuracy of accepted anthropometric methods of percent body fat (%BF) quantification, namely, hydrostatic weighing (HW) and air displacement plethysmography (ADP), to 2 automatic adipose tissue quantification methods using computed tomography (CT)., Methods: Twenty volunteer subjects (14 men, 6 women) received head-to-toe CT scans. Hydrostatic weighing and ADP were obtained from 17 and 12 subjects, respectively. The CT data underwent conversion using 2 separate algorithms, namely, the Schneider method and the Beam method, to convert Hounsfield units to their respective tissue densities. The overall mass and %BF of both methods were compared with HW and ADP., Results: When comparing ADP to CT data using the Schneider method and Beam method, correlations were r = 0.9806 and 0.9804, respectively. Paired t tests indicated there were no statistically significant biases. Additionally, observed average differences in %BF between ADP and the Schneider method and the Beam method were 0.38% and 0.77%, respectively. The %BF measured from ADP, the Schneider method, and the Beam method all had significantly higher mean differences when compared with HW (3.05%, 2.32%, and 1.94%, respectively)., Conclusions: We have shown that total body mass correlates remarkably well with both the Schneider method and Beam method of mass quantification. Furthermore, %BF calculated with the Schneider method and Beam method CT algorithms correlates remarkably well with ADP. The application of these CT algorithms have utility in further research to accurately stratify risk factors with periorgan, visceral, and subcutaneous types of adipose tissue, and has the potential for significant clinical application.

Background: Central adipose tissue is appreciated as a risk factor for cardiometabolic disorders. The purpose of this study was to determine the efficacy of a volumetric 3D analysis of central adipose tissue in predicting disease. Full body computerized tomography (CT) scans were obtained from 1225 female (518) and male (707) subjects, aged 18-88. Percent central body fat (%cBF) was determined by quantifying the adipose tissue volume from the dome of the liver to the pubic symphysis. Calcium score was determined from the calcium content of coronary arteries. Relationships between %cBF, BMI, and several cardiometabolic disorders were assessed controlling for age, sex, and race., Results: Higher %cBF was significantly greater for those with type 2 diabetes and hypertension, but not stroke or hypercholesterolemia. Simple anthropometric determination of BMI equally correlated with diabetes and hypertension as central body fat. Calcium scoring significantly correlated with all measurements of cardiovascular health, including hypertension, hypercholesterolemia, and heart disease., Conclusions: Central body fat and BMI equally and highly predict incidence of hypertension and type 2 diabetes.

Objective: The objective of this study was to determine the gadolinium (Gd) concentration remaining in human bone tissue after administration of standard clinical doses of 2 Gd-based contrast agents: ProHance and Omniscan., Materials and Methods: After administration of 0.1 mmol/kg of Gd chelate to patients undergoing hip replacement surgery, bone specimens were collected and analyzed, and compared with an age-matched control population without a history of Gd chelate administration. Bone specimens were collected fresh, refrigerated, and subsequently frozen. After grinding and freeze-drying, tissue digestion was performed using Teflon bombs and concentrated nitric acid. A method for analysis of Gd in bone specimens was developed and validated using inductively coupled plasma mass spectroscopy (ICP-MS)., Results: Results were compared with a previous study using a different technique for analysis of the same tissue specimens. Tissue retention was 1.77+/-0.704 microg Gd/g bone (n=9) for Omniscan and 0.477+/-0.271 microg Gd/g bone (n=10) for ProHance measured by ICP-MS. These findings confirmed results from the previous ICP-AES study., Conclusion: Omniscan (Gd[DTPA-BMA]) left approximately 4 times (previous study 2.5 times) more Gd behind in bone than did ProHance (Gd[HP-DO3A]).

We have come full circle from spinning quarks to 3D medical images. The bulk of MRI is now performed using slice-selective gradients, during which RF energy is applied to excite the hydrogen nuclei. By stepping a phase-encoding gradient during each TR and using a frequency-encoding gradient as the data are sampled, the 3D human object can be reduced to many individual points or voxels. By acquiring multiple slices at once, the time efficiency of imaging can be vastly improved. Many newer strategies use variations of this technique to acquire multiple lines of data during a single echo, enshrining spin warp imaging as the most important method of signal acquisition for MRI.

Rationale and Objectives: Human bone tissue was collected following administration of a clinical dose of gadolinium chelate (0.1 mmol per kg) to patients undergoing hip joint replacement surgery to determine if measurable differences in Gd deposition occur between 2 widely available magnetic resonance contrast agents., Materials and Methods: Gd HP-DO3A (ProHance), Gd DTPA-BMA (Omniscan), and an age-matched control population without history of gadolinium chelate administration were compared. Bone samples were collected fresh, placed in refrigeration, and subsequently frozen. Tissue digestion was performed using a microwave tissue digester and concentrated nitric acid. A method of tissue analysis was created for gadolinium using inductivity coupled plasma atomic emission spectroscopy (ICP-AES)., Results: Tissue retention was 1.18 +/- .787 microg Gd/g bone (N = 10) for Omniscan and 0.466 +/- .387 microg Gd/g bone (N = 8) for ProHance measured by ICP-AES., Conclusion: Omniscan (Gd DTPA-BMA) left 2.5 times more Gd behind in bone than did ProHance (Gd HP-DO3A).

Rationale and Objectives: The authors compare in vivo transmetallation of three magnetic resonance contrast agents in humans in terms of their kinetic stability., Methods: Blood and urine samples were taken before and after the intravenous injection of gadolinium (Gd)-HP-DO3A, Gd-DTPA, or Gd-DTPA-BMA at 0.1 mmol/kg to healthy volunteers. Serum and urine were assayed for zinc, copper, and Gd, using inductively coupled plasma atomic emission spectrometer., Results: Gadolinium-DTPA-BMA caused the highest increase in zinc excretion among the three agents. Gadolinium-HP-DO3A did not cause a significant increase in zinc excretion. In serum, although Gd-DTPA-BMA exhibited a decrease in zinc concentration, the difference between the drugs was not statistically significant., Conclusions: The difference in observed zinc excretion among the chelates studied reflects in vivo transmetallation of the magnetic resonance contrast media and correlates with the respective kinetic inertia for transmetallation, rather than thermodynamic stability constants. Gadolinium-HP-DO3A was found to be the most kinetically inert among the three drugs tested.

Rationale and Objectives: The relative stability and selectivity of magnetic resonance (MR) imaging contrast agents were compared with in vitro transmetallation and ligand competition reactions., Materials and Methods: A gadolinium (Gd)-DTPA-BIGA, Gd-DTPA-BMA, Gd-DTPA, or Gd-HP-DO3A solution was mixed with an equimolar solution of zinc (Zn) citrate in 1:1 volume ratio at pH 7.4 in a transmetallation assay. In a ligand competition reaction, a DTPA or EDTA solution was mixed with an equimolar solution of Gd-DTPA-BIGA, Gd-DTPA-BMA, or Gd-HP-DO3A. The progress of the reactions was followed with high-performance liquid chromatography (HPLC) using fluorescence detection., Results: In the transmetallation study with Zn citrate, the order of kinetic stability is Gd-HP-DO3A > Gd-DTPA > Gd-DTPA-BIGA > Gd-DTPA-BMA. The order of stability in the ligand competition reaction is Gd-HP-DO3A > Gd-DTPA-BIGA > Gd-DTPA-BMA., Conclusions: Transmetallation kinetics shows major differences among currently used MR imaging contrast media. Equilibrium thermodynamic constants and selectivity constants calculated therefrom do not explain the relative kinetic stability and metal selectivity of MR contrast media in the presence of competing metal ions and ligands.

Objective: The purpose of this study was to determine if orbital and cerebral CT can be used to distinguish normal patients from those with pseudotumor cerebri, and to correlate CT findings with the severity of visual impairment., Subjects and Methods: Seventeen patients with a clinical diagnosis of pseudotumor cerebri were compared with 20 age- and sex-matched control subjects. Thin-section coronal and axial CT scans of the orbit and whole-brain axial CT scans were available for all subjects. The diameter of the optic nerve sheath, the degree of reversal of the optic nerve head, the presence and degree of empty sellae, and ventricular and sulcal sizes were evaluated without knowledge of whether or not the subject had pseudotumor cerebri. The same parameters were compared for two subgroups of patients with pseudotumor cerebri: those with mild vision loss and those with severe vision loss., Results: Patients with pseudotumor cerebri had significantly larger optic nerve sheaths than did control subjects (6.5 +/- 0.83 mm vs 5.4 +/- 0.69 mm). Radiologic evidence of papilledema with reversal of the optic nerve head was found in 12 of 17 patients compared with one of 20 control subjects. An empty sella was seen more frequently and to a greater degree in patients with pseudotumor cerebri than in control subjects (16 vs seven). Eight of nine patients with severe vision loss and four of eight patients with mild to moderate vision loss had reversal of the optic nerve head; the degree was greater in the group with severe vision loss. No difference in ventricular size or sulcal enlargement was seen between any of the groups. The opening CSF pressures of the two groups with vision loss were not significantly different (348 +/- 80 mm H2O vs 391 +/- 98 mm H2O)., Conclusion: In addition to the role of CT in excluding intracranial disease as a basis for the clinical syndrome of pseudotumor cerebri, thin-section CT of the orbits reveals a constellation of findings, including enlarged optic nerve sheaths, reversal of the optic nerve head, and empty sellae in patients with pseudotumor cerebri. Furthermore, severe vision loss in these patients correlates with more frequent and more severe reversal of the optic nerve head.

In this article an overview of current and potential MR contrast agents is given. The mechanism of action of contrast agents and their relationship to both T1 and T2 relaxation are explored. Both paramagnetic and superparamagnetic substances are considered. Various physical states of these materials, including small ionic, lipophilic, and macromolecular forms are explored as possible contrast agents. Several clinical examples are given and speculation is made about the future potential of MR contrast agents.

The ability of the recently synthesized fluorescent analog of thiamin, 1,N6-ethenothiamin, to substitute for thiamin in rats in vivo has been studied. 50 micrograms of ethenothiamin/100 g body weight/day injected in rats allowed about one-half the weight gain with 50 micrograms/100g/day of thiamin. The activities of the pyruvate and alpha-keto-glutarate dehydrogenases of liver mitochondria were partially restored by 50 micrograms/100g/day of ethenothiamin. Ethenothiamin at this level did not appear to restore the branched-chain alpha-keto acid dehydrogenase activities to any extent. When 150 micrograms of ethenothiamin/100g body weight/day was injected, growth was optimum, but these enzyme activities still did not achieve normal levels.

Sympathetic axons have been shown to invade the rat hippocampal formation after lesions of the septohippocampal (cholinergic) projection. To test the generality of this type of transmitter-specific sprouting within the central nervous system, lesions were placed within the horizontal limb of the diagonal band in order to denervate the main olfactory bulb (MOB) of its cholinergic innervation. Some animals also received autologous transplants of the superior cervical ganglion to the region of the MOB. There was no evidence of sympathetic axon growth into the MOB under any circumstance as assessed with qualitative fluorescence histochemistry. In addition, retrograde fluorescent dye studies demonstrated that the basal forebrain neurons projecting to the neocortex, where sympathetic sprouting has also been reported, are a separate population from those which project to the MOB. Although it is difficult to unequivocally interpret negative results, these data indicate that cholinergic denervation does not induce sympathetic sprouting throughout the central nervous system. The availability of a brain region where sympathetic sprouting does not occur may provide clues to understanding the conditions which permit such neuronal plasticity in the hippocampal formation.