PubMed Health⌕ Search

Biomedical subjects

B Kreft

Publications and source records attributed to B Kreft.

At least 73 records · Page 4Linked to original sources
PubMed1996

[MRI of the pancreas: value of standard versus fat-suppressed pulse sequence at 0.5 T].

PURPOSE: To compare five pulse sequences in 60 patients with pancreatic disease by means of MRI at 0.5 T. METHODS: T1 weighted Spin-Echo sequences (T1W SE) before and after i.v. contrast medium administration, fat-suppressed T1W SE sequences after i.v. contrast medium administration, T2 weighted Turbo-Spin-Echo sequences (T2W TSE), and fat-suppressed T2W TSE were evaluated within an ROC study. RESULTS: The standard sequences (T1W SE before and after i.v. contrast medium administration, T2W TSE) were superior to the fat-suppressed T1W and T2W (T)SE sequences in delineating the anatomy and for correct diagnosis. The T1W sequence with and without i.v. contrast media detected all anatomic structures best. In most instances the correct diagnosis and coexistent findings in the diseased pancreas were obtained with the T2W sequence. CONCLUSION: Fat-suppressed sequences are less useful in the diagnosis of pancreatic disease by MRI at medium field strength compared to the standard sequences.

Diagnosis, Differential↗
PubMed1996

[Magnetic resonance tomography of the kidney: the testing of new pulse sequences and comparison with CT in the differential diagnosis of space-occupying lesions].

PURPOSE: To evaluate new pulse sequences (turbo-spin-echo [TSE] and turbo-field-echo [TFE] sequences) for study protocol optimisation and to assess the role of MRI in the differential diagnosis of renal tumours. METHODS: In six volunteers MRI of the kidney was performed at 0.5 T using a conventional T2 weighted spin-echo (SE) sequence (TR/TE 1800/90 ms) and three different TSE sequences (TR 1800-5000 ms, TE 90-150 ms). Additionally CT and MRI was performed in 34 patients with 41 renal masses. Two readers evaluated both images regarding the differentiation between malignant and benign masses. RESULTS: The pilot study showed that the heavily T2-weighted TSE sequence (TR/TE 5500/150 ms) was superior to other sequences with regard to image quality and differentiation of the corticomedullary junction. In the clinical study malignant tumours were correctly classified with CT and MRI in 86.4% and 95.5% of the cases, whereas the accuracy in the diagnosis of benign lesions of CT and MRI was 73.7% and 89.5%, respectively. CONCLUSION: Using new puls sequences MRI is superior to CT in the differential diagnosis of renal tumours. MRI is superior to CT in the differentiation between complicated cysts and cystic or hypovascular renal cell carcinomas.

Diagnosis, Differential↗
PubMed1996

[Intramural hematoma of the thoracic aorta: diagnostic imaging and differential diagnosis].

PURPOSE: Aortic wall thickening due to intramural hemorrhage may be the only sign of aortic dissection. The aim of this study was to evaluate the incidence, imaging features and differential diagnoses of intramural hemorrhage (IMH) of the thoracic aorta. METHODS: 98 patients with clinically suspected aortic dissection were investigated via Spiral-CT and MRT. Diagnosis of IMH based on the presence of smooth crescentic or concentric wall thickening over a longer segment of the thoracic aorta without flow visualization and without compression or distortion of the aortic lumen. RESULTS: 69 patients had classic aortic dissections and 7 patients were diagnosed to have IMH of thoracic aorta. One patient with IMH of the ascending aorta died of aortic rupture and subsequent pericardial tamponade 12 hours after onset of symptoms. In one patient with IMH of the descending aorta on initial examination, there was a progression of overt aortic dissection at follow-up after three weeks. In two patients with IMH of the descending aorta, wall thickening decreased in size at follow-up (10-15 weeks), whereas in one patient it remained unchanged. CONCLUSION: IMH of the aorta should be considered a precursor of aortic dissection. At follow-up IMH may decrease in size, rupture or progress to overt aortic dissection.

Adult↗
PubMed1996

Influence of cloned tRNA genes from a uropathogenic Escherichia coli strain on adherence to primary human renal tubular epithelial cells and nephropathogenicity in rats.

The uropathogenic Escherichia coli strain 536 (O6:K15:H31) possesses pathogenicity islands which are incorporated into two tRNA genes, the selC and the leuX gene. The leuX gene influences the expression of different putative virulence factors. We demonstrate an effect of the leuX-specific tRNA on adherence and uropathogenicity.

Animals↗
PubMed1996

Aortic dissection: a comparative study of diagnosis with spiral CT, multiplanar transesophageal echocardiography, and MR imaging.

PURPOSE: To compare the usefulness of spiral computed tomography (CT), multiplanar transesophageal echocardiography (TEE), and magnetic resonance (MR) imaging in the diagnosis of thoracic aortic dissection and arch vessel involvement. MATERIALS AND METHODS: Forty-nine symptomatic patients with clinically suspected aortic dissection were examined with contrast material-enhanced spiral CT, multiplanar TEE, and 0.5-T MR imaging (T1-weighted, cardiac-gated, spin-echo sequences). Imaging results were confirmed at autopsy (five patients), intraoperative exploration (23 patients), angiography (nine patients), and follow-up (12 patients). RESULTS: Sensitivity in the detection of thoracic aortic dissection was 100% for all techniques. Specificity was 100%, 94%, and 94% for spiral CT, multiplanar TEE, and MR imaging, respectively. In the assessment of aortic arch vessel involvement, sensitivity was 93%, 60%, and 67%, respectively, and specificity was 97%, 85%, and 88%, respectively. CONCLUSION: Spinal CT and multiplanar TEE are as valuable as MR imaging in the detection of thoracic aortic dissection. In the assessment of the supraaortic branches, spiral CT is superior (P<.05).

Adult↗
PubMed1996

1,25-dihydroxycholecalciferol enhances the expression of MHC class II antigens and intercellular adhesion molecule-1 by human renal tubular epithelial cells.

PURPOSE: Beside its role in calcium and phosphorus metabolism, 1,25-dihydroxycholecalciferol (1,25-D3) exerts multiple effects on cytokine and major histocompatibility complex (MHC) class II expression in monocytes and lymphocytes. In different renal diseases tubular epithelial cells express MHC class II molecules and cell adhesion molecules,, such as intracellular adhesion molecule-1 (ICAM-1). Therefore, modulation of MHC class II and ICAM-1 expression in renal tubular epithelial cells by 1,25-D3 may be relevant to lymphocyte adhesion to tubular epithelial cells and immune mediated renal injury. However, the expression of MHC class II antigens and cellular adhesion molecules by renal tubular epithelial cells in response to 1,25-D3 has not been investigated. MATERIALS AND METHODS: We generated human renal tubular epithelial cells and SV40 transfected tubular epithelial cells to investigate immune modulation of 1,25 on renal epithelial cells. Major histocompatibility complex class II molecules and ICAM-1 were detected by a specific enzyme linked immunoassay. RESULTS: We found a dose-dependent increase of both constitutive and induced MHC class II and ICAM-1 expression in tubular epithelial cells stimulated with 1,25-D3. Dose-dependent stimulation of MHC class II and ICAM-1 expression was not restricted to primary human renal tubular epithelial cells but was also detected in SV40 transfected cells. CONCLUSIONS: Expression of MHC class II and ICAM-1 is crucial for antigen presentation by and lymphocyte adhesion to renal tubular epithelial cells. Modulatory effects of 1,25-D3 on immune accessory function of renal tubular epithelial cells may be of clinical significance in renal diseases.

Calcitriol↗
PubMed1995

[45,X/46,XY/47,XXY chromosome mosaicism as a cause of hypergonadotropic hypogonadism diagnosed in late middle age].

UNLABELLED: HISTORY AND FINDINGS ON EXAMINATION: A 62-year-old man complaining of increasingly painful swelling in both breasts over the previous 6 months was admitted to hospital because an endocrine tumour or paraneoplasia was suspected. Unmarried and childless he had always been well except for mild diabetes treated with glibenclamide. On examination both breasts were enlarged with easily palpable glandular tissue; the testes were small and atrophic. Hair growth and distribution were normal. LABORATORY TESTS: Serum testosterone concentration was low (1.3 ng/ml), while luteinizing and follicle-stimulating hormones (27.3 mU/ml and 95 mU/ml, respectively) were raised. Chromosome analysis revealed 45,X/46,XY/47,XYY mosaicism without evidence of structural aberrations. Mammography showed true gynecomastia without signs of malignancy. TREATMENT AND COURSE: Hypergonadotrophic hypogonadism having been diagnosed the patient was given substitution treatment with 250 mg testosterone, 250 mg i.m. every 3 weeks. The concentrations of luteinizing and follicle-stimulating hormones became normal and the gynecomastia regressed over the subsequent 6 months. CONCLUSION: Mosaicism of the sex chromosomes should be considered in the differential diagnosis of late-onset hypogonadism, even in phenotypically unremarkable men.

Age Factors↗
PubMed1995

[The von Hippel-Lindau syndrome. Its differential diagnosis from cystic kidneys in adulthood].

A 51-year-old patient with severe back pain had undergone resection of a benign cerebellar tumour when aged 15 years. In addition, polycystic kidney disease was diagnosed 24 years ago, bilateral phaeochromocytoma 2 years ago, and for 4 months before the present admission he had been on haemodialysis. The family history indicated autosomal dominant inheritance of the polycystic renal disease. His general condition was found to have deteriorated, he had pain on pressure over the upper thoracic and lower lumbar vertebrae, and the kidneys were enlarged on palpation. There were increased concentrations of calcium (3.01 mmol/l), parathormone (2.0 ng/l), carcinoembryonic antigen (13.5 micrograms/l) and TPA (69 U/l). Computed tomography demonstrated cystic and solid parts of much enlarged kidneys. Biopsy revealed a poorly differentiated clear-cell renal carcinoma. Further information concerning the previously removed brain tumour showed this to have been an haemangioblastoma of the cerebellar tonsils indicating the diagnosis of v. Hippel-Lindau disease. Nine other family members had been affected, but none had the full-blown picture of the disease. The patient died 3 weeks later from the rapidly advancing tumour. Autopsy showed the bilateral renal carcinoma, bilateral phaeochromocytoma and metastases to the sternum, femurs, vertebrae and liver.

Adrenal Gland Neoplasms↗
PubMed1995

[Differential diagnosis of commonplace upper abdominal symptoms: hepatic echinococcosis].

A 17-year-old girl from Turkey had for 6 years been suffering from right-sided upper abdominal symptoms not usually related to food intake. Treatment of suspected gastritis remained ineffective. Laboratory tests were unremarkable, except for an accelerated erythrocyte sedimentation rate (12/30 mm), eosinophilia (6.4%) and albumin concentration of 52.6 g/l. Upper abdominal sonography revealed a cyst, about 10 cm in diameter, in the right liver lobe. Computed tomography showed the 8 x 8.5 cm cyst which was septated at its caudal portion and compressed the vena cava for 5.6 cm. The antibody titre against echinococcus antigen was 1:3200. At laparotomy the echinococcal cyst was found to have extended to the left adrenal gland, renal fat capsule and left part of the diaphragm. There was a pressure necrosis on the right lateral aspect of the vena cava. The affected parts were resected and the patient quickly recovered. Postoperative treatment consisted of the administration of mebendazole (1.5 g daily) for 18 months. The patient had come from an area where echinococcal infection is endemic. The disease could have been quickly and easily diagnosed and cured if sonography had been undertaken early, sparing the patient major surgery.

Adolescent↗
PubMed1995

Biphasic increase in circulating and renal TNF-alpha in MRL-lpr mice with differing regulatory mechanisms.

Tumor necrosis factor (TNF)-alpha contributes to expansion of lymphocytes in neonatal mice and can accelerate renal injury. T cells induced by the lpr gene promote renal injury. However, the lpr gene alone is insufficient to cause renal damage, since MRL-lpr, but not C3H-lpr mice develop lupus nephritis. In this study, we examined the temporal expression of TNF-alpha in the kidney and circulation of mice (MRL and C3H) with the lpr gene and their congenic counterparts (++). We measured a bioactive TNF-alpha using L929 cells and tissue expression with an avidin-biotin immunoperoxidase method. A biphasic increase in circulating TNF-alpha in MRL-lpr mice was detected. There was an initial peak in neonatal mice (703 +- 208 pg/ml) which normalized by two months of age (87 +- 13 pg/ml) and reascended proportional to the severity of renal injury (non-proteinuric 570 +/- 87, proteinuric; 1255 +/- 135 pg/ml). In addition, there was only a single peak in neonatal C3H-lpr mice (1270 +/- 318 pg/ml) with a nadir by six weeks of age (434 +/- 52 pg/ml). In contrast, serum TNF-alpha was low in MRL-(++) and C3H-(++) mice (80 +/- 3 and 95 +/- 30 pg/ml), respectively. TNF-alpha expression in kidneys paralleled the serum pattern in MRL-lpr mice. Enhanced TNF-alpha expression was restricted to tubular epithelial cells (TEC) in neonatal MRL-lpr and C3H-lpr mice, and not detected in congenics. In adult mice, intrarenal TNF-alpha expression was more ubiquitous and was detected in glomeruli, vascular smooth muscle and perivascular infiltrating cells as well as TEC.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

[Animal experiment studies on the influence of fatty infiltration of liver cells on tissue relaxation times and signal changes in magnetic resonance tomography].

Using a spectrometer (n = 60) in vitro and MRT imaging (n = 8) in vivo, we studied the influence of fatty changes of liver cells on the relaxation times of the liver (two animal models of fatty liver disease/orotic acid, L-ethionine). Induction of fatty degeneration of the liver by means of an orotic acid diet resulted in pure deposition of fat in the liver without any histological or serological proof of inflammatory changes. Although accumulation of triglyceride in the liver reduced the T1 relaxation time only relatively slightly (-15%), there was good correlation (r = 0.88) between fat content and T1. There was also good correlation (r = 0.92) between T2 and histological fat content. Inflammatory changes besides fatty deposition were seen both serologically and histologically in the L-ethionine model, so that the fatty content did not correlate with T1. In-vivo MRT imaging showed that spin-echo sequences are inappropriate for diagnosing fatty infiltration of the liver despite the relaxation time changes produced by the fatty deposition. On the other hand, chemical-shift imaging sequences are very sensitive to identify fatty deposits, and are also independent of any additionally existing inflammatory changes.

Alanine Transaminase↗
PubMed1995

[Turbo-spin-echo (TSE) sequences with selective fat suppression (SPIR) compared with chemical shift sequences in MRI for differentiation of adrenal tumors. Spectral Presaturation by Inversion Recovery].

AIM: The value of chemical-shift-gradient-echo sequences and turbo-spin-echo sequences with selective fat suppression (SPIR = Spectral Presaturation by Inversion Recovery) in the differentiation of benign and malignant adrenal tumours was investigated. METHODS: Both techniques were performed at 1.5 T in 22 patients with 24 tumours. The loss of signal intensity of the tumour or of the signal intensity ratio between tumour and liver or muscle on the opposed phase Fast-Field-Echo (FFE) sequence in comparison to the in phase FFE sequence or on the TSE-SPIR sequence compared to the TSE sequence was the criterion for intratumoral lipid, suggesting a benign mass. RESULTS: The sensitivity and specificity of the chemical shift technique was 62-77 and 100%, respectively. In adrenal tumours larger than 1.5 cm sensitivity of the chemical-shift technique was 89%. On the contrary sensitivity of the TSE-SPIR sequence was only 11-78%. Both techniques had a specificity of 100%. CONCLUSION: The chemical shift technique is more accurate in the differentiation of adrenal masses than the TSE-SPIR sequence.

Adenoma↗
PubMed1995

[Radiological diagnosis before and after laparoscopic cholecystectomies].

PURPOSE: To study the diagnostic value of radiological imaging modalities in patients undergoing endoscopic cholecystectomy. PATIENTS AND METHODS: In 286 patients with endoscopic cholecystectomy ultrasound and intravenous cholecystography was performed for preoperative work-up. Postoperatively all patients were examined with ultrasound. RESULTS: ERCP showed a stone in the common bile duct in 12 patients with suspected stones on ultrasound, cholecystography or laboratory values. All 12 patients were treated with papillotomy. Postoperative ultrasound detected increasing fluid in the peritoneal cavity in three patients. Laparotomy of one patient showed bleeding from the cystic artery, in the second patient, injury of the right bile duct. One patient showed an accessory hepatic duct, another patient demonstrated pancreatitis. CONCLUSION: Ultrasound and intravenous cholecystography are suitable for preoperative imaging. Postoperative ultrasound is useful in detecting complications.

Adult↗
PubMed1995

[Value of turbo-spin-echo sequences in cerebral magnetic resonance tomography in children].

AIM: The value of turbo-spin-echo (TSE) sequences was compared with conventional spin-echo (SE) and inversion-recovery (IR) sequences for cerebral MRT in 70 children at 0.5 T and 1.5 T. In addition we evaluated whether proton weighted sequences (PD) were diagnostically important and in what proportion of cases. METHOD: Conventional T1 and T2 weighted SE and T2 weighted TSE sequences were used in all children. An IR sequence was performed in 39 patients. The various sequences were analysed semiquantitatively with regard to image quality, artifacts and the demonstration of normal and anatomical structures and pathological findings. RESULTS: By any criteria, TSE sequences were superior to conventional T2 weighted SE sequences at 0.5T and 1.5 T, requiring a shorter examination time (35-53%). In 8.6% the pathological finding was best seen on PD-SE sequences (5 glial scars, 1 tumor). CONCLUSION: Although TSE sequences are better than T2 SE sequences with regard to image quality and the demonstration of abnormalities, conventional double-echo SE sequences (with PD and T2 weighted images) cannot be entirely replaced by T2 weighted TSE sequences in children.

Adolescent↗
PubMed1995

[Focal and diffuse lesions in dynamic MR-mammography of healthy probands].

PURPOSE: To evaluate the range of normal contrast enhancement behaviour in dynamic MR mammography of healthy breast parenchyma, and to reduce false-positive results caused by incidental contrast enhancing lesions. MATERIALS AND METHODS: We performed a prospective two-armed study on 20 healthy premenopausal volunteers who were examined four times within one month (Group 1) or during four consecutive months (Group 2). Incidence, prevalence, morphology, and contrast enhancement pattern of lesions were evaluated. RESULTS: 82% (9/11 of Group 1) and 78% (7/9 of Group 2) showed at least one of a total of 60 contrast enhancing lesions. In 54% or 33% (Group 1 or 2), lesions with enhancement velocity beyond the malignancy threshold were found. 72% or 75% of lesions resolved completely during follow-ups. 69% of lesions were focal with irregular border. Time/signal intensity diagrams were almost always not suspicious; no wash-out phenomenon was seen. CONCLUSION: In MR mammography of premenopausal breast parenchyma, focal contrast enhancing lesions-even with enhancement beyond the malignancy threshold-may occur without any underlying pathology.

Adult↗
PubMed1995

[Turbo-spin-echo sequences with selective fat suppression (SPIR) in the MRI of focal liver lesions at 0.5 tesla].

PURPOSE: The value of T2 weighted turbo-spin-echo sequences with selective fat suppression (TSE-SPIR) in the detection and differential diagnosis of focal liver lesions was compared to TSE sequences and conventional T1 weighted spin-echo (T1 SE) sequences at 0.5T. METHODS: In 50 patients with focal liver lesions T1 SE-TSE-, and TSE-SPIR sequences were performed. Two independent readers evaluated the sequences with regard to the image quality, fat suppression, and the number and conspicuity of liver lesions. Quantitative analysis was performed by tumour-liver contrast-to-noise (CNR) measurements. RESULTS: From a total of 118 liver lesions the T1 SE sequence, the TSE sequence, and the TSE-SPIR sequence showed 85.6%, 83.9%, and 91.5%, respectively (p < 0.05). The tumour-liver CNR of malignant liver lesions was 30.2-46.6% higher on the TSE-SPIR sequence compared to the TSE sequence (p < 0.01). With the exception of fat-containing lesions there was no significant difference of CNR in benign lesions on both TSE sequences. CONCLUSION: With regard to lesion detection the TSE-SPIR sequence is superior to the TSE sequence without fat suppression, whereas it is inferior to the TSE sequence in the differential diagnosis of benign and malignant lesions.

Adipose Tissue↗
PubMed1995

[Distribution of hematopoietic and fatty bone marrow in the proximal humerus and scapula: magnetic resonance tomography and macroscopic anatomy].

PURPOSE: To establish the distribution pattern of haematopoietic and fatty bone marrow on MRI of the proximal humerus and the scapula in correlation with age, gender and nutritive factors. MATERIAL AND METHODS: 32 shoulder MR examinations (T1-weighted spin-echo and opposed-phase gradient-echo sequences) from 24 patients and 8 volunteers were analysed retrospectively. The amount of haematopoietic bone marrow within the proximal humerus and scapula was classified into four groups and was correlated with age (H-test), gender (chi 2-Test), and thickness of subcutaneous fat (H-test). The marrow distribution within 10 scapulae of cadavers over 60 years of age at death was studied. RESULTS: With increasing age, the amount of haematopoietic bone marrow in the proximal humeral metaphysis tends to decrease from lateral towards medial (H-test, p = 0.3). Diaphysis and epiphysis did not show haematopoietic marrow. The amount of haematopoietic bone marrow within the paraglenoid region of the scapula also revealed a decrease with increasing age (H-test, p = 0.003). Females had higher amounts of haematopoietic marrow than males (chi 2-test, p = 0.03). The thickness of subcutaneous fat was independent of the marrow distribution. CONCLUSION: The amount of haematopoietic bone-marrow of the shoulder girdle decreases with increasing age. The knowledge of marrow distribution patterns based upon these changes is important for shoulder MRI interpretation to prevent confusion with infiltrative disease.

Age Factors↗