Quantification of [(18)F]FDG uptake in the normal liver using dynamic PET: impact and modeling of the dual hepatic blood supply.

UNLABELLED: For quantification of hepatic [(18)F]FDG uptake, the dual blood supply to the liver must be considered. In contrast to the arterial input, however, the portal venous blood supply to the liver cannot be monitored directly by PET because of the inaccessibility of the portal vein on PET scans. In this study, we investigated whether the dual hepatic input can be predicted from the measurable arterial input. Moreover, we assessed the effect of different input models on the rate constants of the standard 3-compartment model describing regional uptake of FDG. METHODS: Dynamic FDG PET scanning was performed on 5 foxhounds. Activity concentrations in blood from the aorta and the portal vein were measured simultaneously using external circuits. After image reconstruction, time--activity courses were determined from the aorta and the liver. The venous input was approximated by convolving the arterial input with a notional system function describing the dispersion of the arterial input on its way through the gastrointestinal tract. On the basis of these data, 5 different hepatic input models, which pertain to a single-input as well as a dual-input scenario, were statistically compared with regard to the adequacy of the model fits to liver data and to differences in the estimated rate constants. RESULTS: Portal venous input to the liver could be approximated by convolving the arterial input function with a system function. From this function, a mean transit time of 25 s was computed for FDG to pass through the gastrointestinal tract. According to the statistical analysis, dual-input models were superior to their single-input counterparts. However, differences in the rate constants estimated for the 5 input models were in the same order as interindividual variations within the different model groups. For the dephosphorylation rate constant, a consistent value of 0.05 +/- 0.01 min(-1) was found. CONCLUSION: Dual-input models proved to be superior to single-input models with respect to the adequacy of FDG model fits to normal liver data. However, the hepatic blood supply may be approximated by the arterial input function as well, especially for the evaluation of liver lesions mainly fed by the hepatic artery.

New clinical aspects of hereditary mucoepithelial dysplasia.

Hereditary mucoepithelial dysplasia (HMD) is a multiepithelial disorder. It is transmitted as an autosomal dominant trait (McKusick: Mendelian Inheritance in Man-Catalogs of Autosomal Dominant, Autosomal Recessive, and X-Linked Phenotypes, 8th edition. Baltimore: The Johns Hopkins University Press, pp 499, 1988). HMD is characterized by variable combinations of lesions of skin, hair, orificial mucosa, gingiva, eyes, and lungs. In some previously described patients, the corneal and pulmonary lesions were progressive and led to blindness, recurrent pneumonia, and/or premature death. On light microscopy, the lesion is characterized by dyskeratosis, and, on electron microscopy, by a paucity of gap junctions and desmosomes. Here, we describe a new 5-generation kindred in which affected individuals had the same histologic characteristics but a somewhat different clinical spectrum and a more benign course. HMD should be considered in the differential diagnosis of childhood alopecia, follicular hyperkeratosis, keratoconjunctivitis, juvenile cataracts, gingival hyperemia, restrictive lung disease, and esophageal stenosis or webs.

Determination of regional pulmonary blood flow with systemically injected nonentrapped microspheres.

Radioactive microspheres (MS) injected into the systemic circulation shunt to the venous side of the circulation and are trapped in the lung vasculature. We hypothesized that regional pulmonary perfusion could be determined by using systemically injected shunted MS. In seven anesthetized mechanically ventilated foxhounds, regional pulmonary perfusion was measured at baseline and during experimental acute respiratory distress syndrome with MS injected into both the right and left atrium (protocol 1). Methodological error of the MS technique was assessed by simultaneous injection of two different batches of MS into the right atrium (protocol 2). Measurement of perfusion during baseline and during experimental acute respiratory distress syndrome with shunted MS had a mean bias of 0.8 and 5.6% and mean precision of 19.2 and 34.7% (r = 0.94 and r = 0.95), respectively, compared with data from nonshunted MS. Simultaneous perfusion measurements displayed bias of -2.7 and 6% and precision of 8.2 and 5.3% (r = 0.98 and r = 0.99), respectively. Systemic shunt should be high for this method to prevent bronchial circulation from imposing significant error. We conclude that systemically injected MS can be used for simultaneous measurement of regional systemic and regional pulmonary perfusion, provided that MS that shunted in the first pass are measured in lung tissue.

Dermatologic photography.

Particularly for the beginning clinical photographer, the details of contour light, texture light, flat light, and fill lights may be intimidating. A physician-photographer may elect to choose a name brand system that has manual exposure capability. The system should include a ring light (or ring light equivalent) and a point source with a guide number of at least 80 (feet with ISO 100 film). Standard exposures may be determined, as has been described above. The ring light should be used for reproduction ratios between 1:1 and 1:20; the point source is saved for ratios of 1:20 and below. As confidence and skill increase, the photographer may choose to use additional light sources, facilitating more subtle forms of lighting. Criteria for choosing equipment have been examined in great detail. The importance of using standardized manual strobe lighting at set reproduction ratios as opposed to automated systems using through the lens flash metering has been stressed. Flat, contour, and texture lighting with techniques to decrease shadow density was also addressed at length. Standard views of body areas, lesion photography, and image storage methods were discussed as well.

Magnolia grandiflora dermatitis.

A patient is described who had allergies to several sesquiterpene lactone-containing plants, but the reaction to Magnolia grandiflora was extremely severe. The condition was a chronic lichenified dermatitis that was unresponsive to treatment but cleared with protective measures. Primary allergy to Magnolia is rarely reported, even though some studies of cross-reactivity suggest that sensitivity is far from rare.

Heterogeneity of left ventricular perfusion during pulmonary edema and microembolism treated with positive end-expiratory pressure and norepinephrine.

Regional left ventricular myocardial blood flow was studied in an experimental model of pulmonary edema and microembolization (PEM) ventilated with positive end-expiratory pressure (PEEP). The analysis was based on a 3-dimensional extension of the autocorrelation function used to assess the spatial correlation (rspat) of myocardial perfusion. Experiments were performed on 8 premedicated, anesthetized and mechanically ventilated dogs. PEM was induced with oleic acid (0.01 mg/kg) and glass beads. Successive PEEP values of 10, 15 and 20 cm H2O (P20) were applied and norepinephrine (NE, 0.2-1.0 microgram min-1 kg-1) was administered after P20. Regional perfusion was measured with radioactive microspheres. The left ventricle (LV) was dissected into 256 samples. rspat was computed as the correlation of regional perfusions of samples p units apart in the apex-to-base, endo-epicardial and angular directions. Analysis was performed after anesthesia and instrumentation (control, C), P20 and NE. Control values of rspat were around 50% in the apex-to-base and angular directions and the sign was inverted in the endo-epicardial direction. A reduction of rspat to values close to zero was observed in all directions for P20 and NE. This is the typical pattern of independent distribution. Thus, the results indicate that, under the experimental conditions used, there is some degree of neighborhood dependence of regional LV myocardial blood flow. This dependence is not observed under PEM, mechanical ventilation with PEEP and NE.

A local area network for medical research; planning, realization and experience.

This report focuses on the planning and realization of an interdisciplinary local area network (LAN) for medical research at the University of Heidelberg. After a detailed requirements analysis, several networks were evaluated by means of a test installation, and a cost-performance analysis was carried out. At present, the LAN connects 45 (IBM-compatible) PCs, several heterogeneous mainframes (IBM, DEC and Siemens) and provides access to the public X.25 network and to wide-area networks for research (EARN, BITNET). The network supports application software that is frequently needed in medical research (word processing, statistics, graphics, literature databases and services, etc.). Compliance with existing "official" (e.g., IEEE 802.3) and "de facto" standards (e.g., PostScript) was considered to be extremely important for the selection of both hardware and software. Customized programs were developed to improve access control, user interface and on-line help. Wide acceptance of the LAN was achieved through extensive education and maintenance facilities, e.g., teaching courses, customized manuals and a hotline service. Since requirements of clinical routine differ substantially from medical research needs, two separate networks (with a gateway in between) are proposed as a solution to optimally satisfy the users' demands.

A comparison of JPEG and FIF compression of color medical images for dermatology.

Dermatologists were shown digitized images of skin lesions compressed by Joint Photographic Expert Group (JPEG) and fractal image format (FIF) algorithms and asked to make a diagnostic assessment and rate the image quality in displaying the features necessary for that assessment. Dermatologists performance in the diagnostic assessment was not affected by the level of compression (up to 40X) using either algorithm, but ratings of image quality for all compressed images were significantly lower than for uncompressed images and for the original photographic slides. There were no significant differences in dermatologists' performance or ratings between the two compression algorithms.

Unilateral keratosis follicularis.

Unilateral keratosis follicularis is considered a localized variant of Darier's disease and should be included in the differential diagnosis of zosteriform keratotic eruptions. The authors present a case report and review the treatment; topical retinoic acid appears to be the treatment of choice.

Squamous cell carcinoma of the scrotum.

A patient with psoriasis was found to have a large mass on his scrotum. He was at increased risk for the occurrence of skin cancer, both from the treatments he received for control of his psoriasis and from previous occupational exposure. We present his case and review the risk factors involved.

MIC-III--an integrated software package to support experiments using the radioactive microsphere technique.

MIC-III is a versatile program system to support gamma spectrometry data management and data collection for experiments using the radioactive microsphere technique. It is mainly written in PASCAL and running on a minicomputer. Hierarchical organ dissection schemes are used for unique classification and identification of samples. For each series of experiments, up to 12 different nuclides and up to 20 different organ dissection schemes can be handled simultaneously. Sample weights are collected on-line and sample radioactivities are measured automatically by gamma spectrometry under process control. The spectra with a resolution of 1022 channels are analyzed using a modified linear regression technique and a strategy to compensate for global spectrum shifts. The spectrum deconvolution algorithm was evaluated by calculating the recovery indices for known nuclide mixtures and compared to the stripping method, matrix method and a linear regression technique using window counts. Recovery values produced by MIC-III are better balanced than those of the other methods. MIC-III showed the smallest dispersion of the recovery index and exhibited least error accumulation in case of spectrum shift. MIC-III computes regional blood flow and arterio-venous shunt, and provides interfaces to customized programs or statistical software packages for further analysis. It has successfully been employed in more than 140 experiments.

The evaluation of radioactive microsphere data: remarks on the use of the BMDP and SAS statistical software packages.

We investigated the suitability of BMDP and SAS as an integrated tool for the evaluation of regional blood flow data obtained from the radioactive microsphere technique. Both packages were applied to a recent study on muscle blood flow with a 3-factorial design. The organization of data and files, the strategy of data reduction, and the evaluation by means of statistical and graphical techniques are shown. The method may be applied to any microsphere study design. A considerable amount of time can be saved and data integrity may be improved. The statistical quality of the results may benefit from the broad spectrum of statistical tests available.

Risk/benefit evaluation of drugs: the role of the pharmaceutical industry in Germany.

Drugs that are efficacious have usually also undesired side effects. When applying for marketing authorization of a drug, demonstration of a positive risk/benefit ratio is a prerequisite for approval by the competent authorities. Once on the market, risk/benefit evaluation has to be continued in order to determine whether the risk/benefit ratio is still positive or not. The German Drug Law, by means of article 5, poses this responsibility on the pharmaceutical entrepreneur. Specific instructions on how to perform the risk/benefit evaluation can be derived from article 5, and a decision matrix was developed to support taking action if the risk/benefit ratio has changed. Historical and current examples are presented to illustrate changes of the risk/benefit ratio, problems associated with detecting risk signals, and the resulting regulatory actions.

Chronic ulcerative stomatitis associated with stratified epithelial specific antinuclear antibodies. A case report of a newly described disease entity.

A case of erosive oral lesions associated with an unusual direct and indirect immunofluorescent pattern is presented. Rather than a submucosal band or intramucosal intercellular deposition, the pattern is that of an antinuclear antibody that reacts only with stratified epithelium. The clinical similarity of this case to erosive lichen planus is discussed. The usefulness of direct and indirect immunofluorescence techniques in the diagnosis of erosive oral lesions is stressed.

Becker's melanosis and hypoplasia of the breast and pectoralis major muscle.

Becker's melanosis can be associated with hypoplastic abnormalities. In our patient (the first case report), it occurred in association with an absent pectoralis major muscle. Although more common in males, this patient demonstrates that Becker's melanosis can occur in females and may be congenital.