Multispectral analysis of magnetic resonance images

Magnetic resonance (MR) imaging systems produce spatial distribution estimates of proton density, relaxation time, and flow, in a two dimensional matrix form that is analogous to that of the image data obtained from multispectral imaging satellites. Advanced NASA satellite image processing offers sophisticated multispectral analysis of MR images. Spin echo and inversion recovery pulse sequence images were entered in a digital format compatible with satellite images and accurately registered pixel by pixel. Signatures of each tissue class were automatically determined using both supervised and unsupervised classification. Overall tissue classification was obtained in the form of a theme map. In MR images of the brain, for example, the classes included CSF, gray matter, white matter, subcutaneous fat, muscle, and bone. These methods provide an efficient means of identifying subtle relationships in a multi-image MR study.     

A phase II trial of gefitinib (Iressa, ZD1839) in stage IV and recurrent renal cell carcinoma.

PURPOSE: The epidermal growth factor receptor (EGFR) is overexpressed in 75 to 90% of renal cell carcinomas and may play a role in tumor initiation and progression. Gefitinib (Iressa, ZD1839) is a potent, selective EGFR-tyrosine kinase inhibitor. This trial was undertaken to assess the efficacy and toxicity of gefitinib in advanced renal cell carcinoma. EXPERIMENTAL DESIGN: Oral gefitinib, 500 mg once daily, was given continuously. A single-dose reduction to 250 mg daily was allowed for toxicity. The primary end point was response rate (defined as complete remission + partial remission + stable disease). Secondary end points were progression-free survival, overall survival, toxicity, and correlation of response with EGFR status. RESULTS: Twenty-one patients were enrolled on this study, and all are evaluable for response and toxicity. Patient characteristics were median age 61 (range, 35-78 years); 17 males, 4 females; median performance status 0 (range 0-2); median number of prior systemic therapies 1 (range, 0-3). The median and mean number of cycles of therapy received was 3 and 4.7 (range, 1-14+). The best response was stable disease in eight patients (38%). Median progression-free survival was 2.7 months. Median overall survival was 8.3 months. The difference in overall survival was significantly different between patients with progressive disease versus stable disease (6.1 months versus 16+ months; Log-Rank test P value < 0.0001). Three patients required a dose reduction, all for grade 3 diarrhea. There was no apparent correlation between EGFR status and stability of disease or progression of disease. CONCLUSIONS: Gefitinib is without significant conventional activity in renal cell carcinoma. The relation of "stable disease" to treatment or to disease-related prognostic heterogeneity remains to be defined.     

Promoter methylation regulates Helicobacter pylori-stimulated cyclooxygenase-2 expression in gastric epithelial cells

Cyclooxygenase (COX)-2, the inducible form of the rate-limiting enzyme for prostaglandin synthesis, is up-regulated in gastrointestinal cancers and is a key mediator of epithelial cell growth. Helicobacter pylori is causally linked to gastric cancer. In H. pylori gastritis, COX-2 expression localizes to the subepithelial region, with variable levels in the epithelium. In contrast, in gastric cancer, COX-2 strongly predominates in the epithelium, suggesting that the transition to consistent epithelial COX-2 overexpression may be a critical molecular event in gastric carcinogenesis. Because aberrant promoter methylation inhibits expression of a variety of genes in gastrointestinal cancers, we sought to determine whether methylation of the COX-2 promoter could regulate the response to H. pylori in gastric epithelial cells. We assessed COX-2 expression and promoter methylation status in six gastric epithelial cell lines. In all four of the cell lines that exhibited basal expression of COX-2 and a significant increase in expression in response to H. pylori, the COX-2 promoter was unmethylated, whereas in the two cell lines that did not express COX-2, the COX-2 promoter was methylated. Treatment of COX-2-methylated cells with the demethylating agent 5-azacytidine had a modest effect on COX-2 expression, but when 5-azacytidine-treated cells were subsequently stimulated with H. pylori, there was a significant, 5-10-fold enhancement of both COX-2 mRNA and protein expression and release of the COX-2 product, prostaglandin E2. In contrast, in COX-2-expressing cell lines that were unmethylated at the COX-2 promoter, 5-azacytidine had no effect on H. pylori-stimulated COX-2 expression. These findings suggest that loss of COX-2 methylation may facilitate COX-2 expression and promote gastric carcinogenesis associated with H. pylori infection.     

Excretory urography with iohexol: evaluation in children

A multicenter clinical study was conducted using iohexol, a second-generation nonionic contrast medium, for excretory urography performed in 130 children. Doses of iohexol (300 mg iodine/ml) ranged between 150 and 660 mgI/kg (0.5 and 2.2 ml/kg). Iohexol was tolerated well, and no significant adverse reactions occurred. Sixty-five iohexol urograms were evaluated to determine the minimum dose for adequate visualization of the kidneys and collecting systems. A dose greater than 300 mgI/kg (1.0 ml/kg) always resulted in a urogram of diagnostic quality, while visualization was insufficient for diagnosis in 10% of studies done with doses of 150-300 mgI/kg (0.5-1.0 ml/kg). Another 65 iohexol urograms were compared in a blinded manner with a similar number of studies performed using iothalamate meglumine at comparable iodine concentration and dose. Visualization of calyces and pelvoinfundibular structures achieved with iohexol was rated better with statistical significance, but there was no difference in visualization of the renal parenchyma or ureters. Use of iohexol in excretory urography may be advantageous in children who are at greatest risk for an adverse reaction to contrast media or in those most likely to benefit from use of a low osmolality contrast agent.     

Subperiosteal orbital masses in children with orbital cellulitis: time for a reevaluation?

Conflicting reports have arisen in the literature regarding the diagnostic criteria and management of children with a suspected subperiosteal orbital abscess (SOA). To highlight the dilemmas that have arisen a child with a posterior subperiosteal mass, as demonstrated by computerized tomography, is presented. This case and others in the literature suggests a need for better radiographic criteria for distinguishing an SOA from reactive inflammatory edema. Until such criteria are developed, the management of suspected SOA in children should be based principally on clinical signs. Radiographic examinations should be used primarily to rule out the need for surgical intervention.