Comparison of edge analysis techniques for the determination of the MTF of digital radiographic systems

The modulation transfer function (MTF) is well established as a metric to characterize the resolution performance of a digital radiographic system. Implemented by various laboratories, the edge technique is currently the most widespread approach to measure the MTF. However, there can be differences in the results attributed to differences in the analysis technique employed. The objective of this study was to determine whether comparable results can be obtained from different algorithms processing identical images representative of those of current digital radiographic systems. Five laboratories participated in a round-robin evaluation of six different algorithms including one prescribed in the International Electrotechnical Commission (IEC) 62220-1 standard. The algorithms were applied to two synthetic and 12 real edge images from different digital radiographic systems including CR, and direct- and indirect-conversion detector systems. The results were analysed in terms of variability as well as accuracy of the resulting presampled MTFs. The results indicated that differences between the individual MTFs and the mean MTF were largely below 0.02. In the case of the two simulated edge images, all algorithms yielded similar results within 0.01 of the expected true MTF. The findings indicated that all algorithms tested in this round-robin evaluation, including the IEC-prescribed algorithm, were suitable for accurate MTF determination from edge images, provided the images are not excessively noisy. The agreement of the MTF results was judged sufficient for the measurement of the MTF necessary for the determination of the DQE.     

The Vasculitis in IBD Is Associated with the Degree of Inflammation

The role of vasculitis in the pathogenesis of IBD remains unclear. The aim of this study was to evaluate the detection rate of vasculitis in patients with IBD, its location in the intestinal wall layers and whether it occurs dependent of the degree of inflammation. Immunohistological staining with the endothelial cell marker CD31 and the pan-T cell marker CD3 was performed in 56 colonic specimens of Crohn’s disease, in 43 of ulcerative colitis, and in 5 of colon cancer. Quantification of the degree of inflammation was done using a histological colitis score. There was no sign of vasculitis in the healthy intestinal wall layers. In Crohn’s disease, specimens with minor inflammatory activity (score 0–2) disclosed no vasculitis. Vasculitis was observed in 82% of the specimens with an inflammatory degree of 3 and in 100% with an inflammatory degree of 4. Vasculitis was detected in all intestinal wall layers altered by inflammation. A direct association between vasculitis and granulomas was observed in only 5% of the specimens with an inflammatory degree of 4. All ulcerative colitis specimens evidenced an inflammatory degree between 2 and 4. No vasculitis was found in specimens with an inflammatory degree of 2, but in 57% with an inflammatory degree of 3 and in 100% with an inflammatory degree of 4. Vasculitis is only detectable in the mucous membrane changed by inflammation. Thus, the vasculitis in IBD is exclusively observed in the intestinal wall layers altered by inflammation. The extent of vasculitis depends on the degree of inflammation. An association between vasculitis and granuloma in Crohn’s disease is seen in 5% of the cases.     

Diabetes mellitus and coronary disease--common problems in long-term care]

With the help of a comparative analysis of the cardiovascular risk profile of 150 patients with diabetes mellitus, 62 patients with condition after myocardial infarction and 50 control patients of a rural district with 30,000 inhabitants was established that the spectre of the risk factors widely corresponds. According to a point valuation the diabetics on an average reached 3.36 points and the patients with a condition after myocardial infarction reached 2.66 points. In comparison of the curves a nearly identical course with "a shift to the right" of the patients with diabetes mellitus about the factor of the disturbance of the glucose metabolism could be proved. Concluding from this a general conception of the treatment was described. In this case the aim is a balanced therapy of the factors of risk and a preventive physical conditioning of diabetics with a high risk of infarction. In our investigations was furthermore conspicuous, deviating from literature, a very large proportion of patients with a hyperuricaemia (33.3% of the diabetics, 41.9% of the patients with infarction).     

A new perspective on the mechanism of corpus luteum regression.

Wide angle x-ray diffraction has been used to examine the phase behavior of microsomal membranes from regressing corpora lutea of prepubertal pseudopregnant rats. During periods of optimal progesterone secretion, all of the membrane lipid was in the liquid-crystalline phase at physiological temperature and, therefore, was fluid. However, mixtures of liquid-crystalline and gel phase lipid were observed under identical conditions in microsomal membrane preparations from animals undergoing spontaneous or prostaglandin F2 alpha-induced regression. This was accompanied by a parallel rise in the lipid phase transition temperature. In addition, the proportion of lipid in the gel phase increased with time after prostaglandin F2 alpha treatment. These results indicate that the mechanism of corpus luteum regression may involve phase changes in the phospholipid bilayer of cellular membranes. The resulting presence of gel phase lipid in the membrane matrices could contribute to the loss of tissue function.     

When should incidentalomas of the adrenal gland be surgically treated?

Between January 1981 and December 1988 a total of 95 patients underwent surgery for adrenal tumors. In 24 cases (25.3%) a so-called "incidentaloma" was found. While seven of these tumors showed hormonal activity, in seventeen patients the tumor was hormonal inactive. The size of the tumors ranged between 2 and 11 cm. Histologically all tumors were found to be benign neoplasms. Because of the lack of lethality and minimal morbidity we indicate surgery on incidentaloma of the adrenal gland for the following reasons: tumors with hormone activity, tumor size larger than 3 cm, suspecting malignoma or metastasis and finally in proven enlargement of small tumors. Only in adrenal tumors smaller than 3 cm we suggest a follow-up by ultrasound or computed tomography.     

Robo1/Robo4: differential expression of angiogenic markers in colorectal cancer

The family of roundabout (Robo) proteins is related to the transmembrane receptors and plays a major role in the process of axonal guidance in neurogenesis. It has recently been shown that Robo proteins are also associated with tumor angiogenesis with Slit2 acting as the corresponding ligand. The aim of this study was to validate the differential expression by means of microarray analysis and real-time PCR and to analyze the in situ expression of Robo1 and Robo4 in colorectal cancer. Quantitative analyses of Robo1, Robo4 and Slit2 mRNA expression measured by large scale gene expression studies (Affymetrix U133A) showed a significant up-regulation of Robo1 in tumor vs. normal tissue, whereas Robo4 and Slit2 showed no significant deregulation. For subsequent real-time PCR experiments, paired colorectal tissue samples from cancerous and corresponding non-cancerous tissues were obtained from 50 colorectal cancer patients who underwent surgical resection. Robo1 mRNA overexpression in cancerous tissue compared with normal counterparts was observed in 80% of the patients with a 4-fold expression in 45% and a 12-fold expression in 15%. For Robo4, an up-regulation was detected in >70% (36/50). For Slit2, no differential expression was observed. The overexpression of Robo1 and Robo4 in tumor vs. normal tissue was verified using real-time PCR. The histological analysis revealed an expression of Robo1 mainly in tumor cells, whereas Robo4 is located primarily in endothelial cells of tumor vessels. Therefore, the Robo proteins provide potential target structures for the anti-tumorigenic and anti-angiogenic therapy of colorectal carcinoma.     

The proliferation rate of intracranial tumors as defined by the monoclonal antibody KI 67. Application of the method to paraffin embedded specimens

60 intracranial tumors have been studied immunohistochemically to determine the proliferation rate by staining for the monoclonal antibody KI-67, which recognizes a nuclear antigen expressed by cells in proliferation. In gliomas a clear correlation of stained nuclei to the histologically determined degree of malignancy was found: slow growing astrocytomas and oligodendrogliomas had an average proliferation rate of 1%, more malignant forms of 7–10%. Glioblastomas were found to have a growth fraction of 15%. Metastases had an even higher rate of 20% proliferating cells. In meningiomas the proliferation rate was mainly about 1%, but in three cases it was between 5% and 7%. Whether this is indicative for a higher risk of tumor recurrence, remains to be correlated to the clinical course. Hemangiopericytomas had a proliferation rate of 9% and 16%, respectively, the latter recurring within four months. It may be concluded from the results of this study, that investigation of intracranial tumors with KI 67 may be of prognostic value and can possibly contribute to an individualized tumor therapy.     

Conversion from cyclosporin to FK 506 after liver transplantation

Thirty-seven liver-grafted patients with steroid-resistant acute or chronic graft rejection or with cyclosporin-related complications were converted from CyA to FK 506. The clinical outcome of the patients primarily depended on the degree of liver dysfunction present at initiation of FK 506 treatment. In patients switched to FK 506 for treatment of acute or early chronic graft rejection, CyA nephrotoxicity, or CyA malabsorption, the FK 506 therapy was associated with a clear improvement in the clinical course. In contrast, in patients with advanced chronic graft rejection, a lower response rate to the conversion in immunosuppression was observed. The lower response rate was associated with a higher patient mortality. These studies demonstrate that FK 506 represents a valuable alternative immunosuppressant for liver-grafted patients. The conversion from CyA to FK 506 should take place before serious — and potentially irreversible — disturbances in liver function are observed.