The total entropy for evaluating 31P-magnetic resonance spectra of the liver in healthy volunteers and patients with metastases.

RATIONALE AND OBJECTIVES: The authors describe the clinical status of liver tissue with only a single numerical quantity (total entropy) derived from spectroscopic data of 31P-magnetic resonance (MR) spectra. METHODS: Twenty-four patients with liver metastases and 20 volunteers were investigated with image-guided volume selective 31P-MR spectroscopy on a 1.5-T whole body scanner. From each in vivo 31P-MR spectrum, the ratios of phosphomonoester (PME)/beta-adenosine triphosphate (ATP), inorganic phosphate (Pi)/beta-ATP and phosphodiester (PDE)/ beta-ATP and the total entropy (H*) were calculated. Mean values and standard deviations were determined and significance of the differences were tested with Student's t test. RESULTS: For patients, the H* = 4.7 +/- 4.3, PME/beta-ATP 0.72 +/- 0.28, Pi/beta-ATP = 1.00 +/- 0.39, PDE/beta-ATP = 1.68 +/- 0.59. For the volunteers, H* = 7.6 +/- 2.5, PME/beta-ATP = 0.39 +/- 0.15, Pi/beta-ATP = 0.90 +/- 0.19, PDE/beta-ATP = 1.25 +/- 0.28. The total entropy of patients' spectra showed significantly lower values compared with those of volunteers. PME/beta-ATP and PDE/beta-ATP of the patients increased and differed significantly from volunteer data. CONCLUSIONS: It was demonstrated that the results of in vivo 31P-MR spectroscopy may be described with a single criterion by means of the total entropy.

Spiral CT angiography for preoperative planning in patients with epigastric tumors: comparison with arteriography.

PURPOSE: Spiral CT angiography (CTA) was performed on 22 patients for the preoperative assessment of epigastric tumors in comparison with intraarterial angiography. METHODS: One hundred fifty milliliters of contrast material was administered with a flow of 4 ml/s. After a delay of 30 s, a spiral CT examination of the epigastrium was performed (slice thickness 3 mm, table feed 6 mm/s). Axial images were reconstructed at 2 mm increments. Postprocessing was performed with a maximum intensity projection and shaded surface display imaging program. Plain film arteriography was performed via a catheter inserted transfemorally and placed into the epigastric arteries. The following parameters were evaluated: visualization of the arteries and the portal vein and involvement of these vessels by disease. RESULTS: The vessels (22/22 = 100%) and variations (1/22 = 4.5%) were clearly identified with both techniques. Involvement was diagnosed by angiography 15 times compared with 22 findings by CTA. CONCLUSION: Concerning vessel anatomy, the correlation between both techniques was excellent and vessel involvement showed good correlation, especially when using the axial slices additionally. CTA has the potential to become a minimally invasive diagnostic tool for preoperative planning in epigastric tumors.

[Quantitative computed tomography of the lung in the early diagnosis of asbestosis: initial results in asbestos-exposed navy personnel]. / Die quantitative Computertomographie der Lunge in der Frühdiagnostik der Asbestose: Erste Erfahrungen an asbestexponierten Marinesoldaten.

AIM: To evaluate the diagnostic role of respiratory gated quantitative CT of the lung with regard to the early detection of asbestos-induced lung fibrosis. MATERIAL AND METHODS: 29 navy personnel with a mean asbestos exposure of 21.3 years and exclusively low profusion stages with regard to plain film X-ray (0/1 and 1/0, ILO 1980) were examined using high resolution CT and respiratory gated quantitative CT of the lung. RESULTS: A low but significant increase of the global lung density with -816 HU (range -844 to -749 HU) was found in comparison with the age-matched reference values of -829.8 HU (range -834 to -819 HU). In individual cases the histogram analysis demonstrated a shift of the density distribution towards higher density intervals without corresponding findings in HRCT. No alterations in lung function were observed. There was no correlation between the latency period or length of exposure and density values. CONCLUSION: The respiratory gated quantitative CT of the lung may potentially develop into an accessory parameter for monitoring dust exposed personnel.

[Spiral CT of the thorax with double table feed in relation to slice thickness]. / Spiral-CT des Thorax mit doppeltem Tischvorschub in Relation zur Schichtdicke.

PURPOSE: The aim of the study was to reduce investigation time, radiation dose, and contrast material when performing spiral-CT of the thorax. METHODS: 50 patients with different clinical diagnoses underwent spiral-CT of the thorax with double table feed and 45 ml contrast material (lopentol) were injected. Density measurements were performed as follows: main pulmonary artery without contrast injection, carotid artery, subclavian artery, ascending and descending aorta, aortic arch, main pulmonary artery and thoracic aorta after contrast injection. RESULTS: In comparison to the density of the main pulmonary artery without contrast injection there was an increase of density of 134 HU. 45 ml of the contrast agent were sufficient in all cases for delineation of the mediastinal vessels. Investigation time was 16-18 s and all patients were able to hold their breath during this time, so no artifacts were seen. Radiation dose was cut in half. CONCLUSION: Spiral-CT with double table feed enables investigations of the thorax in less than 20s. 45 ml of a contrast agent are sufficient for performing this examination. There are no essential diagnostic deficits with this technique.

In vivo P-31-MR-spectroscopy of focal hepatic lesions. Effectiveness of tumor detection in clinical practice and experimental studies of surface coil characteristics and localization technique.

RATIONALE AND OBJECTIVES: The influence of partial tumor sampling in a volume of interest (VOI) on the ratios of phosphorus metabolites was examined by localized phosphorus magnetic resonance spectroscopy (P-31-MRS). Experiments were performed to investigate the characteristics of the surface coil used and precession of spatial localization. METHODS: A total of 24 patients with liver metastases and 20 volunteers were studied by P-31-MRS. Patients were divided in two groups: VOI < 50% (n = 8) and VOI > 50% (n = 16) occupied by tumor. For evaluation of the surface coil and localization method (image selected in vivo spectroscopy), phantom studies were performed. RESULTS: Superficial focal liver tumors were detectable with a surface coil at a distance within the coil radius. The image selected in vivo spectroscopy permitted the study of phosphorus metabolism in a defined VOI, phosphomonoester/beta-adenosine triphosphate and phosphodiester/beta-adenosine triphosphate were elevated significantly in spectra of both patient groups. CONCLUSIONS: Detection of small tumor volumes within a VOI filled by less than 50% of the tumor is possible, with results statistically different from that in normal volunteers.

An investigation of the allergenic constituents of Cladonia stellaris (Opiz) Pous & Vezda ('silver moss', 'reindeer moss' or 'reindeer lichen').

The sensitizing potency of Cladonia stellaris ('reindeer lichen', 'silver moss') extracts was determined in guinea pigs by a modified FCA (Freund's complete adjuvant) test. The lichen showed a moderate sensitizing potency. Similar investigations with pure common lichen constituents revealed a moderate sensitizing potency for fumarprotocetraric acid and atranorin and a weak one for evernic acid, stictic acid and both forms of usnic acid. Although generally weak, (-)-usnic acid was at least 2 x stronger than (+)-usnic acid. After separation of the Cladonia ether extract into 'usnic-acid-free' and 'usnic-acid-containing' fractions, perlatolic acid was identified as the main allergenic constituent of the 'usnic-acid-free' fraction. Stictic, evernic, fumarprotocetraric acid and atranorin were not detectable. Lichens and lichen products generally possess a weak to moderate sensitizing capacity. Compared with common sensitizers of occupational and environmental importance, these products play only a minor rôle.