Biomedical subjects

B Kreft

Publications and source records attributed to B Kreft.

At least 37 records · Page 2Linked to original sources

PubMed2001

[Value of selective MIP reconstructions in respiratory triggered 3D TSE MR-cholangiography on a workstation in comparison with MIP standard projections and single-shot MRCP].

PURPOSE: Comparison of anatomical visualisation and diagnostic value of selective MIP reconstructions of respiratory triggered 3D-TSE-MRCP versus standard MIP reconstructions and single-shot MRCP. MATERIAL AND METHODS: 50 patients with pancreaticobiliary disease were examined at 1.5 Tesla (ACS NT II, Philips Medical Systems) using a breath-hold single-shot (SS) and a respiratory triggered 3D-TSE-MRCP technique in 12 standard MIP projections. Additional selective MIP reconstructions with different slice thickness (2, 4, 10 cm) and projections were performed on a workstation. Visualization of the pancreaticobiliary system and the diagnostic value of the examinations were analysed. RESULTS: Single-shot and 3D-TSE in standard projections showed comparable anatomical visualisation. On selective MIP reconstructions the biliary system (SS p < 0.002; 3D-TSE p < 0.000) and the periampullary region (SS p < 0.000; 3D-TSE p < 0.003) were more clearly seen than on SS and standard MIP reconstructions. Furthermore, superior visualisation of the pancreatic duct could be achieved with additional selective MIP reconstructions in contrast to standard MIP (p < 0.003). Sensitivity and diagnostic accuracy showed superior results for selective and standard MIP reconstructions, but no significant differences between the three techniques were found. CONCLUSION: SS and standard MIP reconstructions showed comparable anatomical visualisation. Selective MIP postprocessing on a workstation offers a better visualisation of the pancreaticobiliary system and is useful for detecting pathological alterations.

Artifacts↗

PubMed2001

[Follow-up in patients with head and neck tumors: evaluation of CT criteria for local tumor recurrence].

BACKGROUND: Aim of this study was to evaluate morphologic criteria for diagnosis of locally recurrent head and neck tumors in helical CT. METHODS: Retrospective study, 44 examinations with radiologically abnormal findings were re-read by two radiologists; findings were analysed and correlated with histological diagnosis and clinical findings. RESULTS: 25 cases of local tumor recurrence were confirmed histologically. The accuracy of helical-CT in our preselected examinations for a local tumor recurrence was 93.5 %, the specificity 83.3 %. But 13/44 cases showed radiologically equivocal findings, among them 6 tumor recurrences. The most common characteristics of the 25 proven tumor recurrences were: contrast medium enhancement (96 %), increased volume in comparison to previous examination (92 %), inhomogenity (72 %); however contrast medium-enhancement and increasing volume were also seen in 68.4 % and 63.1 % of the benign changes. CONCLUSION: Contrast medium enhancement and increasing volume are criteria with a high sensitivity but low specifity in predicting a local tumor recurrence in head and neck cancer.

Carcinoma, Squamous Cell↗

PubMed2001

1,25-dihydroxyvitamin D3 differentially regulates IL-1alpha-stimulated IL-8 and MCP-1 mRNA expression and chemokine secretion by human primary proximal tubular epithelial cells.

Beside its role in calcium homeostasis, 1,25-D3 modulates multiple immunological functions in cells of the immune system. In tubular epithelial cells, it increases the expression of HLA-DR and ICAM-1 molecules. Since production of chemokines, such as IL-8 and MCP-1, by tubular epithelial cells is crucial for the inflammatory response in acute transplant rejection and interstitial nephritis, we tested whether 1,25-D3 influences the production of IL-8 and MCP-1 by primary human tubular epithelial cells (TEC). For chemokine detection we used enzyme-linked immunosorbent assays. We differentiated between chemokine secretion directed to the apical and basolateral environment by using cell culture inserts as a model for the tubular basement membrane. mRNA of IL-8 and MCP-1 after stimulation of TEC with IL-1alpha and/or 1,25-D3 was isolated and compared by competitive RT-PCR. We found that basolateral production of IL-8 was higher than luminal secretion. 1,25-D3 (10(-8) M) alone and in combination with IL-1alpha suppressed IL-8 production after 48 h. Basolateral compared to luminal MCP-1 secretion was higher after stimulation either with IL-1alpha alone or combined with 1,25-D3. After 72 h, 1,25-D3 enhanced the IL-1alpha-stimulated MCP-1 secretion. Increased IL-8 mRNA expression after stimulation with IL-1alpha was suppressed by coincubation with 1,25-D3, while MCP-1 mRNA synthesis was enhanced by 1,25-D3 alone and in combination with IL-1 alpha. We conclude that 1,25-D3 differently modulates the expression of CXC-chemokine IL-8 and CC-chemokine MCP-1 by human TEC. The differential effects of 1,25-D3 on renal tubular cytokine secretion have to be considered in therapeutic dials on this hormone, e.g. in renal transplant rejection.

Calcitriol↗

PubMed2001

Absence of cytokine response to bacterial challenge in human tubuloepithelial cells.

In acute bacterial renal infections, which are most frequently caused by Escherichia coli, tubuloepithelial cells are involved with respect to bacterial adherence, invasion and cytotoxicity. In addition, cytokines expressed by tubuloepithelial cells may be relevant for the recruitment of inflammatory cells and tissue damage in bacterial interstitial nephritis. We asked which inflammatory cytokines are produced by primary human tubuloepithelial cells following in vitro exposure to E. coli and found no release of IL-6, IL-8 and TNF-alpha by tubular cells challenged by bacteria. Purified virulence factors (fimbriae, lipopolysaccharide) from E. coli were also without effects on cytokine release by tubular cells. Since lymphocytic infiltration is a characteristic feature in the chronic form of interstitial nephritis, MHC class II expression by tubular cells in response to bacterial coincubation was analyzed. Exposure to both IFN-gamma and E. coli enhanced MHC class II expression on tubuloepithelial cells. In conclusion, tubuloepithelial cells may play an active role in the local defense against bacteria, e.g. by expressing MHC class II molecules. However, in vitro inflammatory cytokines are not induced by E. coli in this cell population.

Bacterial Proteins↗

PubMed2000

[Necrotizing enterocolitis: a historical and current review].

Enteritis necroticans, locally called "Darmbrand", is a severe and life threatening infectious disease which was epidemic in Northern Germany after World War II. Darmbrand had a limited appearance, occurring only for a few years. In Lübeck many cases were diagnosed in 1946/1948 and the book "Darmbrand, Enteritis necroticans" was published in 1949 by clinicians and pathologists. Enteritis necroticans is also known as a tropical cause of bloody diarrhea and is caused by Clostridium perfringens Type C (type beta-toxin). The disease is related to pig feasts in Papua New Guinea. Although necrotizing enterocolitis is now a rather rare disease we must be aware of the appearance of this fulminant entity. This paper represents a review on the historic and current aspects of enteritis necroticans and discusses the epidemiology, pathogenesis and treatment of this disease.

Clostridium Infections↗

PubMed2000

p120 catenin regulates the actin cytoskeleton via Rho family GTPases.

Cadherins are calcium-dependent adhesion molecules responsible for the establishment of tight cell-cell contacts. p120 catenin (p120ctn) binds to the cytoplasmic domain of cadherins in the juxtamembrane region, which has been implicated in regulating cell motility. It has previously been shown that overexpression of p120ctn induces a dendritic morphology in fibroblasts (Reynolds, A.B. , J. Daniel, Y. Mo, J. Wu, and Z. Zhang. 1996. Exp. Cell Res. 225:328-337.). We show here that this phenotype is suppressed by coexpression of cadherin constructs that contain the juxtamembrane region, but not by constructs lacking this domain. Overexpression of p120ctn disrupts stress fibers and focal adhesions and results in a decrease in RhoA activity. The p120ctn-induced phenotype is blocked by dominant negative Cdc42 and Rac1 and by constitutively active Rho-kinase, but is enhanced by dominant negative RhoA. p120ctn overexpression increased the activity of endogenous Cdc42 and Rac1. Exploring how p120ctn may regulate Rho family GTPases, we find that p120ctn binds the Rho family exchange factor Vav2. The behavior of p120ctn suggests that it is a vehicle for cross-talk between cell-cell junctions and the motile machinery of cells. We propose a model in which p120ctn can shuttle between a cadherin-bound state and a cytoplasmic pool in which it can interact with regulators of Rho family GTPases. Factors that perturb cell-cell junctions, such that the cytoplasmic pool of p120ctn is increased, are predicted to decrease RhoA activity but to elevate active Rac1 and Cdc42, thereby promoting cell migration.

Actins↗

PubMed2000

[Analysis of serum zinc level in patients with atopic dermatitis, psoriasis vulgaris and in probands with healthy skin].

BACKGROUND AND OBJECTIVE: The significance of zinc in the pathogenesis of different dermatological conditions is controversial. Using our own patient collective, the present study aimed to determine variations in serum zinc levels in patients with atopic dermatitis and psoriasis as compared to levels in the normal population. PATIENTS/METHODS: The serum zinc levels of 97 patients with atopic dermatitis and 88 patients with psoriasis were compared to those in 22 healthy subjects and subjected to statistical analysis. RESULTS: In contrast to the data given in the literature, no statistically significant difference was found between the populations investigated. CONCLUSIONS: Zinc replacement therapy in patients with atopic dermatitis and psoriasis appears to be indicated only in those with a documented zinc deficiency.

Adult↗

PubMed2000

The impaired immune response to diphtheria vaccination in elderly chronic hemodialysis patients is related to zinc deficiency.

Zinc deficiency causes abnormalities of the immune response. In chronic hemodialysis therapy abnormalities in zinc metabolism as well as an impaired immune response to vaccination have been reported. Therefore we performed a vaccination study against diphtheria and hypothesized that the response to diphtheria vaccination is related to serum zinc deficiency in hemodialysis patients. Serum zinc concentrations were assayed in 16 chronic hemodialysis patients (10 male, 6 female; mean age 65 years) without a documented vaccination history against diphtheria. Nine of these patients were triple immunized against diphtheria while seven received a single vaccination. The response to diphtheria vaccination was measured by ELISA detecting specific antibodies to diphtheria-toxoid. Seroconversion 6 and 12 months after vaccination was defined as the doubling of antibody titers in patients > or = 0.1 IU/ml prior to vaccination or as titers > 0.1 IU/ml in all other patients. Only 6/16 hemodialysis patients responded to immunization against diphtheria by specific antibody production (> 0.1 IU/ml). Twelve months after the single injection 3/7 patients seroconverted while six months after the triple vaccination 3/9 patients responded to immunization. This was not age-dependent, whereas in non-responders we detected significantly decreased serum zinc levels. In contrast, responders showed similar serum zinc levels as age-matched controls. Furthermore, we measured a decreased alpha 2-macroglobulin concentration only in the responders amongst the hemodialysis patients. Protection against diphtheria and the immune response to diphtheria vaccination in hemodialysis patients is poor. The failure to respond to active diphtheria vaccination is related to a significantly decreased serum zinc concentration in hemodialysis patients.

Aged↗

PubMed2000

Hypoxia and interleukin-1beta stimulate vascular endothelial growth factor production in human proximal tubular cells.

BACKGROUND: Vascular endothelial growth factor (VEGF) promotes angiogenesis and inflammatory reactions. VEGF mRNA is detectable in the proximal tubules of inflamed kidneys but not in normals. In other organs VEGF gene expression is induced by hypoxia and cytokines such as interleukin 1 (IL-1). To identify the cellular mechanisms in control of tubular VEGF production, we studied effects of hypoxia and IL-1beta in VEGF mRNA levels, VEGF secretion, and activity of the hypoxia-inducible dimeric transcription factor 1 (HIF-1alpha/beta) in human proximal tubular epithelial cells (PTECs) in primary culture. METHODS: PTECs were grown in monolayers from human kidneys. Hypoxia was induced by incubation at 3% O2. VEGF mRNA was quantitated by competitive polymerase chain reaction following reverse transcription. VEGF was measured by enzyme-linked immunoassay. HIF-1alpha was demonstrated by Western blot analysis and HIF-1 DNA binding by gel shift assay. RESULTS: Significant amounts of VEGF mRNA and VEGF protein were measured in PTEC extracts and culture media, respectively. Stimulation of VEGF synthesis at low O2 tension and following IL-1beta treatment was detectable at the protein level only. Nuclear HIF-1alpha protein levels and HIF-1 binding to DNA were also increased under these conditions. CONCLUSIONS: PTECs in culture produce VEGF. One mechanism of induction appears to be increased DNA binding of HIF-1 to hypoxia-responsive elements in the VEGF gene promoter. In inflammatory diseases of the kidney, tubular cell-derived VEGF may contribute to microvascular leakage and monocyte extravasation.

Animals↗

PubMed2000

Interleukin-8 secretion of cortical tubular epithelial cells is directed to the basolateral environment and is not enhanced by apical exposure to Escherichia coli.

In upper urinary tract infections, tubular epithelial cells (TEC) may play a pivotal role in the initiation of the renal inflammatory response. They exert crucial immunological functions such as processing and presentation of foreign antigen, secretion of proinflammatory cytokines (interleukin-6 [IL-6] and tumor necrosis factor alpha) and chemokines (IL-8, MCP-1, ENA-78, and RANTES). Since monolayer cultures are a limited model for polarized tubular epithelial cells, we studied the side-dependent IL-8 secretion of TEC by using cell culture inserts as a basement membrane imitation. Primary cultures of proximal TEC were stimulated with differently fimbriated mutants of Escherichia coli, E. coli LPS, S-fimbria isolates, and IL-1alpha. IL-8 protein was measured by enzyme-linked immunosorbent assay, and IL-8-like biological activity was tested by measuring elastase release from polymorphonuclear cells in supernatants of the upper and lower compartments. IL-8 mRNA was compared by competitive PCR. IL-8 secretion by TEC into the basolateral environment was significantly higher than secretion into the apical compartment, representing the tubular lumen. However, stimulation of IL-8 secretion by TEC was restricted to IL-1alpha and was not inducible by E. coli mutants, S fimbriae, or lipopolysaccharide. With this in vitro model of polarized TEC, we show that luminal contact of TEC with uropathogenic E. coli does not result in enhanced IL-8 secretion. The basolaterally directed production of the neutrophil chemotactic factor IL-8 by TEC after stimulation with IL-1alpha might play an important role in the initiation of inflammatory cell influx into the renal parenchyma.

Base Sequence↗

PubMed2000

Detection of thrombosis in the portal venous system: comparison of contrast-enhanced MR angiography with intraarterial digital subtraction angiography.

PURPOSE: To determine whether intraarterial digital subtraction angiography (DSA) can be replaced by contrast material-enhanced magnetic resonance (MR) angiography in the assessment of patency or thrombosis of the portal venous system in patients with portal hypertension. MATERIALS AND METHODS: Thirty-six patients with portal hypertension underwent contrast-enhanced MR angiography and intraarterial DSA for assessment of the portal venous system. The images were evaluated for vessel patency or thrombosis of the portal, splenic, or superior mesenteric vein. RESULTS: Of the 101 vessels evaluated, 42 were thrombosed. Overall sensitivity, specificity, and accuracy for the detection of thrombosis were 100%, 98%, and 99%, respectively, for MR angiography and 91%, 100%, and 96%, respectively, for DSA; differences between the imaging methods were not statistically significant. Only in four patients with six vessels (6%) were there discordant findings between MR angiography and DSA. CONCLUSION: Noninvasive contrast-enhanced MR angiography has the potential to replace intraarterial DSA as the standard method to assess the whole portal venous system.

Adolescent↗

PubMed2000

Measurement of fluid volume shifts during hemodialysis by A-mode ultrasonography.

BACKGROUND: The rate of intercompartmental fluid volume changes during hemodialysis (HD) is a major determinant of dialysis-induced hypotension and lacks direct monitoring. The aim of the study was to evaluate the feasibility of tissue thickness (TT) measurement in monitoring the mobilization of interstitial fluids during HD. METHODS: We studied the intradialytic changes in forehead TT and inferior vena cava diameter (IVCD) in 20 patients. Plasma refilling was calculated from changes in hematocrit (Hct) and ultrafiltration rates. RESULTS: During ultrafiltration of 2,437 +/- 117 ml (mean +/- SEM), Hct increased significantly from 27.9 +/- 0.7 to 30.0 +/- 0.9%. IVCD decreased significantly from 9.7 +/- 0.2 to 6.1 +/- 0.4 mm/m(2). We found a simultaneously pronounced reduction in TT from 4. 46 +/- 0.12 to 3.78 +/- 0.12 mm (> or =15.3%) with a significant correlation to plasma refilling (0.613). CONCLUSION: Volume changes in the peripheral shell tissues during HD can be monitored directly and noninvasively by A-mode ultrasound.

Adult↗

PubMed1999

Defective immune response to tetanus toxoid in hemodialysis patients and its association with diphtheria vaccination.

The incidence of infectious diseases is increased in patients with chronic renal failure. This is thought to be due to an impaired T cell stimulation by antigen presenting cells. Immunization programs are of great significance in the prevention of infections in immunocompromised individuals. However, the immune response to various vaccinations is impaired in patients with chronic renal failure. So far only few studies have focused on seroresponse to tetanus toxoid. Therefore we measured the levels of antitetanus toxoid antibodies in 71 hemodialysis patients with unknown vaccination history. The antibody levels were detected prior to and twelve months after a single "Td" or "Td-d-d" vaccination. Initially only 31 (44%) of the patients had a sufficient protection against tetanus. Of the unprotected patients 15 (38%) seroconverted after immunization, while 25 (63%) did not respond. We found a high association (p < 0.04, Fisher's exact test) between the efficacy of vaccination against diphtheria and tetanus. Out of 38 initially unprotected patients 27 (71%) showed a similar response to both vaccines: 9 (24%) individuals seroconverted, while 18 (47%) did not. Our data clearly demonstrate the need for frequent monitoring of antibody levels after immunization against tetanus and diphtheria in hemodialysis patients.

Antibodies, Bacterial↗

PubMed1999

Enhanced tumor detection in the presence of liver cirrhosis: experimental study on the diagnostic value of a superparamagnetic iron oxide MR imaging contrast agent (NSR 0430).

The purpose of this study was to determine the diagnostic value of the superparamagnetic iron oxide NSR 0430 for the detection of focal liver lesions in the presence of advanced cirrhosis. Cirrhosis and growth of cholangiofibromas were induced in 22 rats by administration of thioacetamide. Sixteen non-cirrhotic animals served as controls. T1 and T2 relaxation times of liver and tumor tissue of 12 animals were measured spectroscopically. In 10 animals in vivo MRI was performed before and 1 hour after contrast administration, and then the tumor-to-liver contrast-to-noise ratio (CNR) was calculated. All specimens were evaluated histologically. After contrast administration, T1 and T2 values of liver tissue showed a significant decrease of 18% (P = 0.01) and 31% (P = 0.009), respectively, whereas relaxation times of tumor tissue did not change. On precontrast turbo spin-echo images, 40 tumors could be identified; after contrast administration, 95 lesions were visible. CNR increased significantly after contrast administration by 297% at a TE of 50 msec and by 254% at a TE of 90 msec. In conclusion, our in vitro and in vivo results demonstrate that administration of NSR 0430 substantially improves liver-to-tumor CNR and lesion detection on T2-weighted magnetic resonance images even in the presence of severe cirrhosis.

Animals↗

PubMed1999

1,25-dihydroxycholecalciferol stimulates ICAM-1 expression of human alveolar macrophages in healthy controls and patients with sarcoidosis.

Synthesis and release of 1,25-dihydroxycholecalciferol (1, 25-(OH)2D2) by alveolar macrophages (AM) have been shown to be increased in granulomatous lung disease. ICAM-1 plays a major part in leukocyte homing to sites of chronic inflammation, which is a crucial step during the inflammatory response. Whether 1,25-(OH)2D2 alters the ICAM-1 expression of AM in humans has not been studied. Bronchoalveolar lavage (BAL) was performed in 12 healthy volunteers, in 13 patients with sarcoidosis (active disease n = 8, inactive disease n = 5), and in 9 patients with chronic bronchitis. AM were incubated with different concentrations of 1,25-(OH)2D2 (10(-11) to 10(-6) M) with and without priming with interferon-gamma (IFN-gamma) and with and without preincubation with 10(-8) M dexamethasone. In addition, the metabolites of vitamin D, 24, 25-dihydroxycholecalciferol and 25-hydroxycholecalciferol, were used. The AM expression of ICAM-1 (cELISA) and the release of tumor necrosis factor-alpha (TNF-alpha) (bioassay) by AM were determined. In healthy volunteers the ICAM-1 expression on AM was significantly and dose-dependently increased by 1,25-(OH)2D2, but not by 24, 25-dihydroxycholecalciferol and 25-hydroxycholecalciferol. Priming with IFN-gamma resulted in an additive effect. Preincubation with dexamethasone inhibited ICAM-1 expression. Addition of 1,25-(OH)2D2 after inhibition by dexamethasone increased ICAM-1 expression significantly. TNF-alpha secretion of AM from healthy volunteers was significantly reduced by 1,25-(OH)2D2. In sarcoidosis patients ICAM-1 expression was significantly higher compared with healthy volunteers. Incubation with 1,25-(OH)2D2 resulted in a further significant increase of ICAM-1 expression. TNF-alpha secretion of AM was increased compared with healthy volunteers. 1,25-(OH)2D2 reduced TNF-alpha secretion; however, this difference was not significant. 1, 25-(OH)2D2 has an immunomodulating effect on human AM both in healthy volunteers and in sarcoidosis patients with enhanced expression of ICAM-1. It may serve as an autocrine mediator in inflammatory lung disease.

Adult↗

PubMed1999

[The MRT of focal liver lesions: the value of gadolinium-enhanced dynamic studies of the whole organ with a fast 3D-turbo-gradient echo sequence].

PURPOSE: To determine the value of a dynamic Gd-enhanced ultrafast T1-weighted 3D-turbo-gradient-echo sequence (3D-TFE) in the detection and characterization of focal liver lesions. MATERIALS AND METHODS: 51 patients with 124 focal liver lesions (35 hemangiomas, 30 HCC, 24 metastases, 22 cysts, 5 FNH/adenoma, 8 other lesions) were examined using a 1.5 T system. The dynamic 3D-TFE sequence, achieving 40 slices with a thickness of 4.5 mm in a 17-s breath-hold, was compared with a fat-suppressed T2-weighted fast-spin-echo sequence (TSE SPIR), unenhanced and Gd-enhanced T1-weighted spin-echo sequences (SE), and a T1-weighted gradient-echo sequence (FFE). RESULTS: On 3D-TFE images more lesions (107/124) were identified than on T1-weighted SE (101/124) and T1-weighted FFE images (106/124), but less compared to T2-weighted TSE SPIR images (115/124). The 3D-TFE-sequence provided additional information in 65/107 (61%) detected lesions by delineating the dynamic enhancement pattern, most valuable in patients with HCCs in 90%. CONCLUSIONS: On dynamic 3D-TFE images more lesions could be depicted than on conventional T1-weighted SE and T1-weighted FFE images. Visualization of the dynamic enhancement pattern provided additional information for tumor characterization in 61% of the detected lesions on the 3D-TFE images.

Artifacts↗

PubMed1999

Evaluation of different models of experimentally induced liver cirrhosis for MRI research with correlation to histopathologic findings.

RATIONALE AND OBJECTIVES: Three models of experimentally induced liver cirrhosis were evaluated for MRI research on chronic liver disease. The influence of different histopathologic changes in liver fibrosis and cirrhosis on relaxation times and signal intensities was studied in vitro and in vivo. METHODS: Liver fibrosis and cirrhosis in rats was induced by oral or subcutaneous administration of carbon tetrachloride (CCl4) or by thioacetamide (TAA) in drinking water. On histology, the degree of liver fibrosis and cirrhosis, fatty infiltration, iron accumulation, and inflammatory changes were measured semiquantitatively. The amount of connective tissue was quantitatively determined by morphometry. The results were correlated with T1 and T2 relaxation times and signal intensities of the liver studied in vitro by relaxometry and in vivo by MRI. RESULTS: In both groups with CCl4 administration, histology revealed different degrees of liver fibrosis and cirrhosis. Subcutaneous injection of CCl4 also resulted in increased fatty infiltration. On the contrary, TAA produced complete liver cirrhosis in all animals. Overall, there was a good correlation between the liver T2 relaxation time and the amount of connective tissue in liver fibrosis and cirrhosis. However, the degree of liver fibrosis and cirrhosis was also strongly correlated with the degree of inflammatory changes. In the group with CCl4 administration, there was a good correlation between the fatty infiltration and the T1 relaxation time, as well as with the liver signal intensity on the T1-weighted gradient echo sequence. An increased iron accumulation was also correlated with the degree of liver fibrosis/cirrhosis; however, there was no significant influence of the iron on relaxation times or signal intensities. CONCLUSIONS: The TAA model is easier to perform and more reliable in liver cirrhosis induction than the CCl4 models. Although there is a positive correlation between the T2 relaxation times and the degree of liver fibrosis/cirrhosis, this probably results from the associated inflammatory changes and is not caused by the increased amount of connective tissue.

Animals↗

PubMed1999

[The pathological/MR tomographic correlation and differential diagnosis of malignant kidney tumors].

PURPOSE: Evaluation of malignancy criteria in MRT of kidney tumors in correlation with the histopathological findings. MATERIALS AND METHODS: 41 patients with suspected malignant kidney tumors were examined using a T1 SE sequence (TR/TE 300/10 ms) before and after i.v. administration of 0.1 mmol/kg Gd-DTPA and a T2 SE sequence (TR/TE 5500/150 ms). The results were correlated with the pathological findings. RESULTS: 38 malignant tumors were found: 29 renal cell carcinomas (RCC), 13 with solid growth, 11 with tubulopapillary growth, and three with mixed growth forms, one cystic RCC, and one chromophobic RCC, in addition, 6 urothelial carcinomas and three other malignomas. Typical MRT criteria for RCC were an inhomogeneity of the tumor with regions of slightly increased signal intensity on the T1-weighted image (59%) and regions with reduced signal intensity on the T2-weighted image (96%) as compared with renal parenchyma; these were due to histomorphological hemorrhage and hemosiderin deposits, respectively. A further criterion for RCC was a hypointense pseudocapsule in the T2 TSE sequence in 79% of the cases. CONCLUSIONS: The low-signal nature of RCC in the T2-weighted image correlates with hemorrhage and hemosiderin deposits. The detection of a pseudocapsule is useful in the differential diagnosis of solid tumors in the kidney.

Carcinoma, Renal Cell↗