Biomedical subjects

T Balzer

Publications and source records attributed to T Balzer.

32 records · Page 2Linked to original sources

PubMed1996

Magnetic resonance imaging of focal liver lesions. Comparison of the superparamagnetic iron oxide resovist versus gadolinium-DTPA in the same patient.

RATIONALE AND OBJECTIVES: The authors assess the efficacy of static and dynamic magnetic resonance (MR) imaging using the superparamagnetic iron oxide SHU-555A (Resovist) versus standard dose of gadolinium (Gd)-DTPA in patients with focal liver lesions. METHODS: Magnetic resonance imaging was performed in 30 patients suffering from histopathologically verified malignant (n = 22) and benign (n = 8) liver lesions. T2-weighted conventional and fat-suppressed as well as T1-weighted sequences were used before, during, and after fast intravenous administration of Resovist (1 mL/minute) at three doses of 4, 8, and 16 mumol/kg body weight. One week before the Resovist-enhanced MR imaging study 20 patients underwent Gd-DTPA-enhanced MR imaging. RESULTS: Detection rate was improved for metastatic lesions revealing 36 lesions unenhanced versus 53 focal lesions using Resovist-enhanced MR imaging. Gadolinium-DTPA-enhanced scans showed no additional lesion versus unenhanced and Resovist-enhanced MR imaging. Static and dynamic imaging demonstrated no measurable percentage signal intensity loss (PSIL) using Resovist-enhanced MR imaging versus a percentage enhancement of 79.7% in Gd-DTPA enhanced scans. In the dynamic T2-weighted sequences, hepatocellular carcinoma nodules (n = 4) showed a rapid decrease in signal intensity starting at 44 seconds. Postinfusion of Resovist followed by a low, constant increase in signal intensity. Gadolinium-DTPA enhanced scans showed a percentage enhancement of 73.4 focal nodular hyperplasia (FNH) and hemangioma revealed a strong and early dose-dependent PSIL 44 to 60 seconds postinfusion with a prolonged signal loss for the FNH in the late study. Statistical evaluation revealed a statistically significant superiority of Resovist-enhanced MR imaging concerning the detection and delineation of focal liver lesions compared with unenhanced and Gd-DTPA enhanced scans (P < 0.05). CONCLUSIONS: The fast infusion of the new superparamagnetic contrast agent Resovist shows advantages for dynamic and static MR imaging of focal liver lesions.

Carcinoma, Hepatocellular↗

PubMed1996

Phase II clinical evaluation of Gd-EOB-DTPA: dose, safety aspects, and pulse sequence.

PURPOSE: To investigate the efficacy of gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid (Gd-EOB-DTPA) in the detection of focal liver lesions with respect to dose, side effects, and pulse sequence. MATERIALS AND METHODS: A randomized double-blinded trial was performed in 33 patients with focal solid liver lesions. A bolus of Gd-EOB-DTPA, a liver-specific contrast agent, was intravenously administered at three different doses (12.5, 25, and 50 mumol per kilogram of body weight). Magnetic resonance imaging with different T1-weighted techniques was performed 20 and 45 minutes after administration of Gd-EOB-DTPA. Changes in liver signal intensity, lesion-liver contrast-to-noise ration (C/N), detectable liver lesions, side effects, and adverse events were evaluated. RESULTS: Gd-EOB-DTPA significantly (P < .05) increased liver signal intensity and lesion-liver C/N within the dose range tested. Lesion detection was improved 20 and 45 minutes after administration of Gd-EOB-DTPA. A dose of 12.5 mumol was sufficient for the detection of focal liver lesions, and the breath-hold, T1-weighted, fast low-angle shot pulse sequence was the most useful. No significant changes in vital signs, clinical laboratory test results, and urinalysis were observed. CONCLUSION: Gd-EOB-DTPA is an efficient, diagnostically useful, and safe contrast agent.

Contrast Media↗

PubMed1996

Liver tumors: comparison of MR imaging with Gd-EOB-DTPA and Gd-DTPA.

PURPOSE: To compare the usefulness of gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid (Gd-EOB-DTPA) and gadolinium diethylenetriaminepentaacetic acid (Gd-DTPA) in the diagnosis of focal liver lesions. MATERIALS AND METHODS: Thirty-one patients with focal liver lesions underwent T2- and T1-weighted spin-echo magnetic resonance (MR) imaging and fast low-angle shot two-dimensional MR imaging before, during, and after intravenous administration of three different doses of Gd-EOB-DTPA (12.5, 25, and 50 mumol per kilogram body weight). Gd-DTPA-enhanced imaging (dose, 0.1 mmol per kilogram body weight) was performed in the same patients within 1 week of Gd-EOB-DTPA imaging. RESULTS: During the perfusion phase (the 3 minutes after injection of contrast material), the dynamic enhancement characteristics seen after injection of 25 and 50 mumol of Gd-EOB-DTPA were similar to those seen with Gd-DTPA. At the lowest dose of Gd-EOB-DTPA (12.5 mumol), the dynamic enhancement characteristics were not comparable to those seen with Gd-DTPA. During the hepatobiliary phase (1.5 minutes to 4 hours after injection), Gd-EOB-DTPA-enhanced images yielded a dose-independent, statistically significant improvement in the detection rate of additional metastases, hepatocellular carcinomas, and hemangiomas compared with unenhanced and Gd-DTPA-enhanced images (P < .05). CONCLUSION: Gd-EOB-DTPA-enhanced MR imaging enables improved detection of hepatic lesions over Gd-DTPA-enhanced MR imaging while providing comparable differential diagnostic information.

Adult↗

PubMed1995

Application of a superparamagnetic iron oxide (Resovist) for MR imaging of human cerebral blood volume.

The authors describe the feasibility of dynamic MRI using a novel superparamagnetic iron oxide contrast agent. Resovist was injected as a bolus at doses of 4, 8, and 16 mumol Fe/kg bodyweight in three consented patients participating in a Phase 2 clinical multicenter trial for hepatic MRI. Dynamic images of the brain were obtained with a conventional FLASH sequence. Results were analyzed by evaluation of dynamic images, cerebral blood volume maps, and normalized signal intensity time curves. Resovist enabled rapid injections and a dose-dependent strong reduction in gray and white matter signal intensity. The small injection volume and good tolerability may enable Resovist to serve as a perfusion agent. Dedicated clinical trials are warranted to assess the potentials of Resovist for perfusion MRI and fMRI.

Blood Volume↗

PubMed1995

Clinical results with Resovist: a phase 2 clinical trial.

PURPOSE: To investigate the superparamagnetic iron oxide (Resovist) designed for contrast material-enhanced magnetic resonance imaging of the liver. MATERIALS AND METHODS: A phase 2 trial was performed in 33 patients with no more than five known focal solid liver lesions. Resovist was administered intravenously at doses of 4, 8, and 16 mumol of iron per kilogram of body weight. Postcontrast 1.0-T imaging was started 30 minutes after injection. RESULTS: Resovist significantly (P < or = .05) decreased liver signal intensity and increased lesion-to-liver contrast-to-noise ratio (C/N) and the number of detectable liver lesions: fast spin-echo (SE) (echo time, 90 msec) precontrast C/N, 11.7 +/- 7.9 [standard deviation]; postcontrast [8-mumol Fe/Kg] C/N, 29.2 +/- 14.2). The dose of 8 mumol Fe/kg was sufficient for the detection of focal liver lesions, and T2-weighted fast SE with an echo time of 90 msec was the overall best pulse sequence. CONCLUSION: Resovist is a safe contrast agent, and a dose of 8 mumol Fe/kg is sufficient to enhance detection of focal liver lesions at T2-weighted fast SE MR imaging.

Contrast Media↗

PubMed1995

[New super-paramagnetic iron particles for MRI. Phase II study of malignant liver tumors].

The clinical tolerability and diagnostic value of Resovist as a new superparamagnetic iron oxide contrast medium was studied in 30 patients with malignant focal liver lesions (28 metastases, 2 HCC) within a phase II multicenter study. Magnetic resonance imaging (MRI) was performed at 1.0 Tesla with T1-weighted FLASH- and T2-weighted spin echo sequences before and following intravenous injection of Resovist at three different dose groups (4, 8 and 16 mumol Fe/kg). Liver signal intensity was significantly reduced on post-contrast images, while malignant focal liver lesions showed no signal changes. Resovist improved tumor liver contrast and lesion-conspicuity, especially for lesions smaller than 1 cm. The dose of 8 mumol Fe/kg was sufficient to achieve diagnostic tumor-liver contrast. Compared to images directly after injection, the number of detected lesions did not improve until 70 min later. There were no significant changes in vital signs (heart rate, blood pressure) or laboratory values until 72 h post-injection.

Adult↗

PubMed1995

[Diagnosis of cerebral metastasis with standard dose gadobutrol vs. a high dose protocol. Intraindividual evaluation of a phase II high dose study].

PURPOSE: To assess the effectiveness and safety of normal and high doses of Gadobutrol versus a standard dose of Gadolinium DTPA in the MR evaluation of patients with brain metastases. MATERIAL AND METHODS: In a clinical phase-II study 20 patients who had been diagnosed as having brain metastases with CT or MRT were studied prospectively with Gadobutrol, a new nonionic, low osmolality contrast agent. Each patient received an initial injection of 0.1 mmol/kg body weight and an additional dose of 0.2 mmol/kg Gadobutrol 10 min later. Spin-echo images were obtained before and after the two applications of Gadobutrol. Dynamic scanning (Turbo-FLASH) was performed for 3 min after each injection of the contrast agent. Both quantitative and qualitative data were intraindividually evaluated. The primary tumor was a bronchial carcinoma in 11 cases; in 9 other cases there were different primary tumors. RESULTS: Forty-eight hours after the use of Gadobutrol there were no adverse signs in the clinical examination, vital signs or blood and urine chemistry. Statistical analysis (Friedman test and Wilcoxon test) of the C/N ratios between tumor and white matter, percentage enhancement, and visual assessment rating revealed statistically significant superiority of high-dose Gadobutrol injection in comparison to the standard dose. The percentage enhancement increased on average from 104% after 0.1 mmol/kg to 162% after 0.3 mmol/kg Gadobutrol. Qualitative delineation and contrast of the lesions increased significantly. The use of high-dose Gadobutrol improved the detection of 36 additional lesions in 6 patients. CONCLUSION: The first in vivo results prove the excellent contrast capacity of the nonionic contrast agent Gadobutrol for the diagnosis of intracerebral metastases.

Adult↗

PubMed1991

Identification of patients at high risk for colorectal carcinoma from biopsy studies of the apparently normal colorectal mucosa. A multivariate analysis.

A number of phenotypic abnormalities of the colorectal mucosa which appears normal have been described to be biomarkers of cancer development. To improve their sensitivity and specificity, we simultaneously determined 10 morphological and histochemical parameters in biopsies from the colonoscopically normal mucosa of the descending colon, sigmoid, and rectum. The results were analysed by multivariate statistical methods. We tested the discriminating power of proliferative, morphometric, enzyme and mucin histochemical parameters from 80 patients either at average risk (controls), with an increased risk for colorectal carcinoma (high-risk), or with a manifest carcinoma. The following parameters were investigated: number of mitotic figures per crypt, crypt length, apical, medial and basal crypt diameter, crypt surface, activity of succinate dehydrogenase (EC 1.3.99.1), activity of acid beta-galactosidase (EC 3.2.1.23), sulpho- and sialomucin contents. Univariate statistical analyses revealed that crypt length, crypt diameter and crypt surface were significantly increased in the high-risk group, the carcinoma carriers having intermediate values between average-risk and high-risk patients. In a two-group discriminant analysis, high-risk or carcinoma patients could be separated from average-risk patients with a sensitivity of 92.9% and a specificity of 100%. When the analysis was repeated for three groups (carcinoma carriers separated from high-risk patients), sensitivity and specificity were 100% for each group. We conclude that identification of patients at risk for colorectal carcinoma is possible from the normal-appearing left colonic and rectal mucosa by morphometric and cytochemical analysis of biopsies.

Aged↗

PubMed1990

[Physiologic and pathologic age related changes in the small intestine].

Age-related morphological or functional changes are known to occur in numerous organ systems. In the case of the small bowel, only mild impairment of such functions as carbohydrate absorption and in particular vitamin D and calcium absorption have so far been reported. The latter is possibly of significance for the pathogenesis and treatment of osteoporosis. Other disturbances appear to have no clinical relevance, since the considerable functional reserve capacity of the small bowel can largely compensate them. To date, no morphological correlate has been established for the known functional disorders.

Aging↗

PubMed1988

Characterization of stereomicroscopically identified preneoplastic lesions during dimethylhydrazine-induced colonic carcinogenesis.

Preneoplastic mucosal changes were studied at six different time-points during dimethylhydrazine (DMH)-induced colorectal carcinogenesis in the rat. After 40 weeks of treatment, seven of 10 animals were bearing a total of 11 colorectal adenocarcinomas. The crypt cell production rate in the normal mucosa of DMH-treated animals was greatly increased in the left colon and rectum and further rose with the duration of the experiment. Focal disturbances of the mucosal architecture could be detected as early as 4 weeks after the initiation of DMH-treatment using a stereomicroscope. Their incidence was greatest in the left colon and rectum and increased strongly with the duration of carcinogen exposure. Characterization of these mucosal alterations, by means of conventional histology, morphometry after microdissection, cell kinetics, mucin histochemistry and quantitative enzyme histochemistry performed with serial sections, revealed mild epithelial dysplasia, a considerable elongation and dilatation of the crypts and a marked increase of the crypt cell production, including a shift of the main proliferative compartment from the basal to the medial crypt segment as well as the occurrence of mitotic figures in the luminal epithelium. In affected crypts, the goblet cells completely lacked sulphomucins and exclusively contained sialomucins. The activities of the enzymes diaminopeptidase IV (brush-border), succinate dehydrogenase (mitochondria) and acid beta-galactosidase (lysosomes) were markedly reduced. We conclude that these early mucosal alterations are indeed preneoplastic lesions and indicate the existence of the adenoma-carcinoma sequence in this animal model.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenocarcinoma↗

PubMed1988

Changes in the lectin-binding pattern of PNA-agglutinin and UEA1 during the DMH-induced carcinogenesis in the normal appearing colonic mucosa of the rat.

The purpose of this study was the investigation of changes in the lectin-binding pattern prior to tumour formation in an experimental model. Female Wistar rats were treated with 1,2-dimethylhydrazine (DMH). After 4, 8, 16, 24, 32 and 40 weeks of treatment the lectin-binding-pattern of the colonic mucosa appearing morphologically normal was examined at the caecum, proximal colon, distal colon and rectum, using FITC-conjugated Peanut-agglutinin (PNA) and Ulex europaeus-agglutinin1 (UEA1). In contradistinction to what has been reported earlier by other authors, PNA did not indicate constant cancer-associated mucin changes. In addition, there was no difference in the UEA1-binding between the control animals and the DMH-treated rats. Thus, in the rat there is no specific PNA- and UEA1-binding pattern during tumour induction in the gut.

1,2-Dimethylhydrazine↗

PubMedDate not supplied

Assessment of reperfusion injury by means of MR contrast agents in rat liver.

The purpose of this study was to investigate whether extracellular MR contrast agents or intracellular liver-specific MR contrast agents may enable the assessment of liver reperfusion injury. Ischemia-related reperfusion was induced in 32 rats using Pringle's maneuver. Pringle's maneuver consisted of cross-clamping of the complete hepatoduodenal ligament for 45 minutes followed by 90 minutes of reperfusion. Two extracellular (gadopentetate dimeglumine and gadobutrol) and two intracellular gadoxetic acid and SH U 555 A) MR contrast agents were evaluated as model agents. Control animals and animals with liver ischemia were used to calculate changes in liver signal enhancement after Pringle's maneuver. Significant changes in liver signal after reperfusion injury were observed only with reticuloendothelial system (RES)-specific SH U 555 A. Liver signal enhancement after Pringle's maneuver with RES-specific SH U 555 A was decreased by 25.4% as compared with the control group. RES-specific contrast agents such as SH U 555 A seem to be more sensitive to ischemia-related dysfunction of the liver than hepatobiliary contrast agents such as gadoxetic acid or extracellular gadolinium chelates at different concentrations because Kupffer cells are more sensitive to liver ischemia than hepatocytes.

Analysis of Variance↗

PubMedDate not supplied

SPIO-enhanced 2D-TOF MR angiography of the portal venous system: results of an intraindividual comparison.

The purpose of this study was to investigate whether MR angiography (MRA) of the portal venous system may be improved by means of superparamagnetic iron oxides (SPIOs) during accumulation phase imaging and to study the underlying contrast mechanisms. MRA of the portal venous system was performed on 48 patients before and after intravenous injection of a new SPIO (Resovist, Schering AG, Berlin, Germany). Resovist, as a predominantly liver parenchymal darkening agent on T2-weighted MR images with uptake into the reticuloendothelial cell system, was administered intravenously by bolus injection of 8 to 12 micromol Fe/kg body weight. Patients were scanned with breath-hold coronal and axial two-dimensional (2D) time of flight (TOF) MRA (TR = 31.0 msec, TE = 9.8 msec, flip angle (FA) = 50 degrees, and 6.9-second acquisition time per section) sequences. Signal intensity values of liver parenchyma, the portal venous system, and background were obtained for quantitative analysis. The clinical relevance of additional plain and contrast-enhanced MRA studies for surgical planning was assessed by independent reading of three readers. Liver signal-to-noise ratio (SNR) significantly decreased following iv injection of Resovist; however, SNR values of the portal veins or hepatic veins did not change significantly. Visibility of the portal venous system improved significantly (tertiary branches visible: pre in 15.2% versus post in 87.0% of patients). Resovist-enhanced 2D-TOF MRA may improve planning of liver resections by better demonstrating the relationship of central liver lesions and vessels on source images. The decrease in liver SNR at a constant vessel SNR after iv injection of Resovist improves MRA of the liver. SPIO-enhanced 2D-TOF MRA scans are superior to plain 2D-TOF MRA studies and may be added for the workup of preoperative patients.

Contrast Media↗

PubMedDate not supplied

MR enhancement of brain lesions: increased contrast dose compared with magnetization transfer.

PURPOSE: To compare image contrast and lesion conspicuity of enhancing intracranial lesions obtained with T1-weighted and magnetization transfer T1-weighted spin-echo sequences after administration of standard (0.1 mmol/kg body weight) and triple doses of gadobutrol. METHODS: Twenty-four patients with a total of 34 enhancing intracranial lesions were studied with T1-weighted and magnetization transfer T1-weighted spin-echo MR imaging. An incremental dose technique was used with intravenous injections of 0.1 and 0.2 mmol/kg body weight gadobutrol. Lesion-to-white matter contrast and white matter-to-edema contrast were calculated. RESULTS: The lesion-to-white matter contrast of the magnetization transfer T1-weighted studies was significantly higher than that of the T1-weighted studies when identical doses of gadobutrol were compared. The lesion-to-white matter contrast was not significantly different on the triple-dose T1-weighted study and the standard-dose magnetization transfer T1-weighted study. Two lesions were visible only on the standard-dose magnetization transfer T1-weighted and the triple-dose studies. CONCLUSION: Standard-dose magnetization transfer T1-weighted and triple-dose T1-weighted spin-echo MR studies are equally well suited to increase the lesion-to-white matter contrast in patients with enhancing intracranial lesions. Triple-dose magnetization transfer T1-weighted studies further increase lesion-to-white matter contrast but do not show additional lesions.

Adult↗