Optimal Virtual Monochromatic Images for Evaluation of Normal Tissues and Head and Neck Cancer Using Dual-Energy CT.

BACKGROUND AND PURPOSE: Dual-energy CT is not used routinely for evaluation of the head and neck, and there is no consensus on the optimal virtual monochromatic image energies for evaluating normal tissues or head and neck cancer. We performed a quantitative evaluation to determine the optimal virtual monochromatic images for visualization of normal tissues, head and neck squamous cell carcinoma, and lymphadenopathy. MATERIALS AND METHODS: Dual-energy CT scans from 10 healthy patients and 30 patients with squamous cell carcinoma were evaluated at different virtual monochromatic energy levels ranging from 40 to 140 keV. The signal-to-noise ratios of muscles at 6 different levels, glands (parotid, sublingual, submandibular, and thyroid), 30 tumors, and 17 metastatic lymph nodes were determined as measures of optimal image quality. Lesion attenuation and contrast-to-noise ratios (compared with those of muscle) were evaluated to assess lesion conspicuity. RESULTS: The optimal signal-to-noise ratio for all the tissues was at 65 keV (P < .0001). However, tumor attenuation (P < .0001), attenuation difference between tumor and muscles (P = .03), and lesion contrast-to-noise ratios (P < .0001) were highest at 40 keV. CONCLUSIONS: The optimal image signal-to-noise ratio is at 65 keV, but tumor conspicuity compared with that of muscle is greatest at 40 keV. Optimal evaluation of the neck may be best achieved by a multiparametric approach, with 65-keV virtual monochromatic images providing the best overall image quality and targeted use of 40-keV virtual monochromatic images for tumor evaluation.

Different spectral hounsfield unit curve and high-energy virtual monochromatic image characteristics of squamous cell carcinoma compared with nonossified thyroid cartilage.

BACKGROUND AND PURPOSE: The attenuation of normal nonossified thyroid cartilage can be similar to that of head and neck squamous cell carcinoma on CT. We compared dual-energy CT spectral Hounsfield unit attenuation characteristics of nonossified thyroid cartilage with that of squamous cell carcinoma to determine the optimal virtual monochromatic image reconstruction energy levels for distinguishing tumor from normal nonossified thyroid cartilage. MATERIALS AND METHODS: Dual-energy CT scans from 30 patients with histopathology-proved squamous cell carcinoma at different primary sites (laryngeal and nonlaryngeal) and 10 healthy patients were evaluated. Patients were scanned with a 64-section single-source scanner with fast-kilovolt (peak) switching, and scans were reconstructed at different virtual monochromatic energy levels ranging from 40 to 140 keV. Spectral attenuation curves of tumor and nonossified thyroid cartilage were quantitatively evaluated and compared. Any part of the tumor invading the cartilage, when present, was excluded from ROI analysis to avoid cross-contamination from areas where there could be a mixture of cartilage and invading tumor. RESULTS: Normal nonossified thyroid cartilage had a characteristic, predictable spectral attenuation curve that was different from that of tumors. The greatest difference in attenuation of nonossified cartilage compared with tumor was on virtual monochromatic images of ≥95 keV (P < .0001), with sharp contrast between the relatively high attenuation of nonossified cartilage compared with that of tumor. CONCLUSIONS: Head and neck squamous cell carcinoma has significantly different attenuation on virtual monochromatic images of ≥95 keV, compared with nonossified thyroid cartilage.

High resolution MRI in the detection of an intrathymic parathyroid adenoma.

The most common cause of primary hyperparathyroidism is parathyroid adenoma. Of these, up to 20% have been reported to be in ectopic locations. Multiple imaging techniques have been utilized in the detection of ectopic adenoma and are discussed. We report on a case of an intrathymic parathyroid adenoma that was detected through the novel use of a breast coil in performing a high resolution MRI. The accurate localization permitted minimally invasive surgery, obviating morbidity associated with a sternotomy.

Isolated trigeminal neuropathy due to trigeminal nerve root hemorrhage.

BACKGROUND: Isolated trigeminal neuropathy is uncommon; causes include trauma, inflammation, or neoplasm. METHODS: We report a patient who fell and struck his head during a myocardial infarction, was treated with streptokinase, and developed symptoms and signs of an isolated trigeminal sensory neuropathy. RESULTS: Imaging showed hemorrhage in the trigeminal nerve root; follow-up imaging showed resolution of the hemorrhage, but no underlying structural lesion. CONCLUSION: A combination of head trauma plus thrombolysis resulted in an isolated trigeminal neuropathy.

Three-dimensional ultrasonography of normal fetal heart: comparison with two-dimensional imaging.

Thirty-one high-risk patients (16 to 35 weeks' gestation) underwent two-dimensional and three-dimensional ultrasonography to compare two-dimensional and non-cardiac-gated three-dimensional ultrasonography of the normal fetal heart. After normal two-dimensional studies, three-dimensional sonographic volumes were acquired without cardiac gating in transverse and longitudinal planes. Standard cardiac views were derived from three-dimensional data, analyzed, and rated as follows: (1) not identifiable, (2) identifiable but inadequate for diagnosis, (3) adequate, and (4) excellent. Two-dimensional ultrasonography demonstrated better yields of diagnostically acceptable images of basic echocardiographic views (four-chamber view, 100% for two-dimensional sonography versus 10 to 71% for three-dimensional sonography; right ventricular outflow tract, 42% for two-dimensional versus 6 to 26% for three-dimensional ultrasonography; left ventricular outflow tract, 71% for two-dimensional versus 13 to 45% for three-dimensional sonography). In one subject three-dimensional ultrasonography was superior to two-dimensional sonography in demonstrating an outflow tract. Aortic and ductal arches were not imaged with the two-dimensional technique but were available from the acquired three-dimensional volumes in 3 to 32% and 23%, respectively. False-positive and false-negative findings were observed on three-dimensional ultrasonograms. Overall, compared to two-dimensional ultrasonography, non-cardiac-gated three-dimensional sonography yielded inadequate reconstructed image quality of basic echocardiographic views (four-chamber view, right ventricular outflow tract, left ventricular outflow tract). Three-dimensional ultrasonography, however, shows potential for allowing nonechocardiographers to acquire some diagnostically acceptable views of the aortic and ductal arches.

[Acid mucopolysaccharides in the postnatal maturation of the brain]. / Kislye mukopolisakharidy v postnatal'nom sozrevanii mozga.

Using the reliable method of separating cell fractions and myelin from the rat brain tissue during postnatal ontogenesis, we investigated changes in the content of acid mucopolysaccharides (AMPS) as macromolecular constituents in cell elements, neuronal and glial fractions, on one hand, and subcellular structures, myelin, on the other. During postnatal ontogenesis, the content of rat brain AMPS displays marked fluctuations not only in toto but also within all cell fractions and myelin. These changes were the highest in glial fractions, somewhat lower in neuronal fractions and the lowest in myelin fractions at the beginning of myelination. During the period of intensive myelination, the level of AMPS decreases markedly in glial fractions but increases in myelin fraction. In the late period of postnatal development, myelin contains 60% of the rat brain AMPS.

[Design and methodology in environmental acoustics]. / Conception et méthodologies en acoustique environnementale.

On the basis of many experiments of urban acoustics carried out in the canton of Geneva, the authors come to the conclusion that the normative values cannot be applied when the estimate of discomfort level is concerned. They must be applied to prevent the risk of auditive acuteness loss. In order to establish discomfort, it is necessary to use methods to measure and analyse the results which are suitable for each condition, and to take into account the acoustic charge, the noise dynamics, the acoustic spectrum and the socio-economic environment of the people concerned. The conception has been accepted by Court of Justice in Geneva, which is now legally accepted: one may consider a uncomfortable any increase of 4-6 dB(A) of the acoustic level, as compared to the previous situation or to the background noise. The ability to differentiate between two stimuli is based on the physiological mechanisms of hearing.

Sodium-potassium-activated adenosine triphosphatase activity as a measure of neuronal membrane characteristics in ethanol-tolerant mice.

(Na+-K+) activated adenosine triphosphatase of mouse synaptosomal membranes is inhibited by high concentrations of ethanol. When membranes were obtained from mice made tolerant to and physically dependent on ethanol by chronic exposure to an ethanol-containing liquid diet, the enzyme was resistant to the inhibitory effects of ethanol. Arrhenius plots of synaptosomal (Na+-K+) activated adenosine triphosphatase from control animals revealed that ethanol added in vitro lowered the transition temperature and altered the Arrhenius activation energies of this enzyme. Enzyme from ethanol-tolerant animals had a lower transition temperature than that from control animals, and ethanol added in vitro had no effect either on transition temperature or on activation energy of enzyme from ethanol-tolerant animals. The occurrence of lowered transition temperature and resistance to ethanol-induced alterations in transition temperature of the enzyme from ethanol-tolerant animals most likely reflects changes in membrane composition. Changes in Arrhenius plots correlated in time with resistance to the inhibitory effects of ethanol on (Na+-K+) activated adenosine triphosphatase activity and the time course of disappearance of these effects was similar to that of the disappearance of functional tolerance to ethanol. The resistance to the effects of ethanol on membrane function may be related to ethanol tolerance evidenced by behavioral and physiological measurements.

Receptor and membrane function in the alcohol tolerant/dependent animal.

Neurochemical changes which are associated with the development or expression of tolerance to or physical dependence on ethanol may be expected to display a time course of appearance and disappearance which correlates positively with the time course for tolerance or dependence. Previous studies of striatal dopaminergic receptor function indicated that ethanol-withdrawn mice displayed decreased physiological and biochemical responses to dopamine (DA) agonists, which could be best explained by postulating an inefficient coupling between DA receptors and various receptor-mediated processes, possibly as a result of ethanol-induced changes in neuronal membrane properties. The membrane-bound enzyme, (Na+-K+)ATPase, obtained from ethanol-withdrawn animals, displays an altered transition temperature and resistance to the effects of ethanol on enzyme activity. These changes also suggest compensatory alterations in neuronal membrane properties. All of these alterations show a time course of disappearance which corresponds to that for the disappearance of tolerance to the hypothermic and sedative effects of ethanol. Ethanol-withdrawn mice also display increased numbers of hippocampal muscarinic cholinergic receptors; however, the time course for the increase in receptor number appears to correlate with that of withdrawal symptomatology. Thus, compensatory changes in neuronal membrane properties in response to ethanol may be expressed via diverse functional changes.

35S-sulphate incorporation into myelin sulphated mucopolysaccharides during rat brain development.

Rat brain myelin acid mucopolysaccharides (AMPS) incorporate 15%, 8%, 5.5% and 4% of total associated 35S-sulphate, 14, 21, 30 and 75 days after birth, respectively. The course of 35S-sulphate incorporation into total rat brain mucopolysaccharides, as well in those from myelin, had a similar feature with peak on the 2nd week and a significant decrease on the 3rd and 4th week postnatally.

Rapid eye movement (rem) sleep deprivation: effect on acid mucopolysaccharides in rat brain.

The effect of rapid eye movement (REM) sleep deprivation on the total content and proportion of different mucopolysaccharides (AMPS) containing uronic acid in rat brain was studied. REM sleep deprivation was induced by the water tank methods. Five experimental groups of animals were used: control, stressed, REM sleep deprived, post-stress sleeping and post-deprivation sleeping rats. No changes of AMPS were observed in any of the experimental groups when the whole brain was analysed. A significant increase of AMPS was found in the cerebral hemispheres of stressed and REM deprived rats. A significant decrease of AMPS was observed in the cerebellum and brain stem. A further increase of AMPS was found in the cerebral hemispheres after the rebound of REM sleep following its deprivation, and after the recovery sleep following the stress. A significant increase of AMPS was found in the brain stem of rats allowed to recuperate after REM deprivation or stress as compared with the stressed and REM deprived animals. Recovery sleep induced a significant increase of AMPS in the cerebellum in previously stressed rats, while previously REM deprived rats exhibited a further decrease of AMPS from control values. The possible functional meaning of these results is discussed in relation to the role of REM sleep in protein synthesis and learning and memory processes. Intriguing, well-controlled positive findings and the fact that no experimental design is known where stress is minimal while REM deprivation is 100 per cent, justify and encourage continued efforts in studying the biochemical state of the brain during sleep and/or its alterations.