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P Herzog

Publications and source records attributed to P Herzog.

At least 19 recordsLinked to original sources
PubMed2006

Dose reduction in multidetector CT of the urinary tract. Studies in a phantom model.

A novel ureter phantom was developed for investigations of image quality and dose in CT urography. The ureter phantom consisted of a water box (14 cm x 32 cm x 42 cm) with five parallel plastic tubes (diameter 2.7 mm) filled with different concentrations of contrast media (1.88-30 mg iodine/ml). CT density of the tubes and noise of the surrounding water were determined using two multidetector scanners (Philips MX8000 with four rows, Siemens Sensation 16 with 16 rows) with varying tube current-time product (15-100 mAs per slice), voltage (90 kV, 100 kV, 120 kV), pitch (0.875-1.75), and slice thickness (1 mm, 2 mm, 3.2 mm). Contrast-to-noise ratio as a parameter of image quality was correlated with dose (CTDI) and was compared with image evaluation by two radiologists. The CT densities of different concentrations of contrast media and contrast-to-noise ratio were significantly higher when low voltages (90 kV versus 120 kV, 100 kV versus 120 kV) were applied. Smaller slice thickness (1 mm versus 2 mm) did not change CT density but decreased contrast-to-noise ratio due to increased noise. Contrast phantom studies showed favourable effects of low tube voltage on image quality in the low dose range. This may facilitate substantial dose reduction in CT urography.

Phantoms, Imaging↗
PubMed2006

[Magnetic resonance imaging in the evaluation of pneumonia].

Magnetic resonance imaging (MRI) of the lung is challenging because of substantial drawbacks. However, lung pathologies that are associated with increased attenuation values in CT enhance visualization in MRI: proton density is increased and tissue-air interfaces, resulting in susceptibility artifacts, are reduced in pneumonia, pneumonitis, edema, and carcinoma. On the other hand, many lung diseases result in shortness of breath, so that patients cannot hold their breath for long periods. Therefore, fast imaging techniques are required which should also allow for high spatial resolution so that small lesions can be detected. Calcifications and air pockets within lesions are not readily recognized with MRI. Thin section CT is standard for the diagnosis of pneumonia. With parallel imaging techniques, MRI examination of the lungs can be performed with short periods of breath holding, which allow for sub-centimeter resolution in the z-axis. Especially for follow-up examinations in immunocompromised patients and, in some instances, for the staging of malignant diseases (malignant pleural mesothelioma, lung cancer, respectively), MRI is very promising and may contribute to a decrease in the radiation exposure of the patients.

Humans↗
PubMed2004

Aorto-iliac multidetector-row CT angiography with low kV settings: improved vessel enhancement and simultaneous reduction of radiation dose.

The aim of the study was to implement an abdominal CT angiography protocol using 100 kVp and to compare SNR and CNR, as well as subjective image quality, to a standard CT angiography protocol using 120 kVp on a 16 detector-row CT scanner. Forty-eight patients were referred for routine abdominal CT angiography on a 16 detector-row CT scanner. Patients were scanned using either 120 or 100 kVp at constant mAs settings. Vessel opacification was provided by automated contrast injection using similar injection protocols. Density measurements were performed along the aorto-iliac axis with SNR and CNR calculation. In addition, the estimated effective patient radiation dose was calculated. Results of both protocols were compared. The 100-kVp protocol (432+/-80 HU) showed a significantly higher vessel density than the 120-kVp (333+/-90 HU; P<0.001) protocol, corresponding to an average increase in signal intensity of 30.7%. SNR (36.0 vs 37.0) and CNR (31.1 vs 31.7) for the 100-kV protocol were not significantly lower that those for the standard protocol (P=0.79 and P=0.87), whilst the average estimated dose was significantly lower using the 100-kVp protocol (6.7+/-0.4 vs 10.1+/-1.2 mSv; P<0.0001). Tube kVp reduction from 120 to 100 kVp allows for significant reduction of patient dose in abdominal CT angiography, without significant change in SNR,CNR and image quality.

Adult↗
PubMed2004

[PET-CT interventional tumour therapy].

Multifocal metastatic spread of solid tumours is often a diagnostic and therapeutic challenge. Those patients often cannot undergo curative surgery. Since several years, various types of interventional tumour therapy have been introduced, which may represent a promising option in those cases. In some cases morphological imaging is not able to assess the viability of a previously treated lesion. The combination of computed tomography and positron emission tomography has the potential to ease planning and guiding of interventional procedures and to improve postinterventional control. Due to its higher sensitivity and specificity, PET/CT enables for a more precise selection of patients for interventional tumor therapy. The success of a particular therapy could be assessed with greater accuracy using PET/CT as compared with the separate modalities. PET/CT was also able to improve planning and guiding interventional therapy. As of yet, no data are available concerning the success rate and long-term survival of PET/CT associated interventional procedures.

Adult↗
PubMed2002

[CT angiography of the coronary arteries with a 16-row spiral tomograph. Effect of spatial resolution on image quality].

PURPOSE: To evaluate image quality of coronary CT angiography with retrospectively ECG-gated 16 multi-slice spiral CT (MSCT), reconstructed with 0.75 mm slice thickness for optimal spatial resolution and with 1.3 mm slice thickness, to produce spatial resolution comparable to a 4-MSCT. MATERIALS AND METHODS: Ten patients underwent coronary CT angiography with a 16-MSCT (Siemens Sensation 16, Forchheim, Germany) with 0.75 mm detector collimation. Raw helical CT data were retrospectively reconstructed using two different settings. Setting A: B20f smooth kernel, axial MPR with 1.3 mm slice thickness and 0.7 mm increment. Setting B: B35f "HeartView" medium-smooth kernel, 0.75 mm slice thickness, 0.5 mm increment. In the axial slices two regions of interest (ROIs) were placed in the area of the aortic root (AR) and more caudal in the area of the left ventricle (LV). Image noise was determined by the standard deviation of the CT numbers.Two readers determined visibility of coronary arteries by standardized maximum intensity projections (MIP) post-processing in left, right anterior and left anterior oblique projection plane from setting A and B. Each projection was rated on a five point rating scale concerning plaque delineation. Points determined for each data set were summed up and used for comparison. RESULTS: No significant difference between the CT-numbers was found for setting A and B (A: 283.0 in AR/295.9 in LV and B: 282,9 in AR/297.2 in LV; p >0.2). However, the image noise was significantly different for setting A and B (A: 4.46 in AR/1.67 in LV and B: 8.16 in AR/7.38 in LV; p <0.01). Better delineation of the coronary arteries and atherosclerotic lesions could be achieved from MIP projections in setting B compared to setting A. CONCLUSION: Higher image noise is present in coronary 16-MSCT with thin-slice reconstruction compared to simulated 4-MSCT. However the MIP-reconstructions benefit most from the higher spatial resolution.

Coronary Angiography↗
PubMed2002

[Radiation dose and dose reduction in multidetector row CT (MDCT)].

Since its introduction a few years ago, multidetector row CT (MDCT) has become a widely used diagnostic procedure and has been proven to be a valuable tool for various indications. A major issue using this new modality is the inherent risk of applying increased radiation exposure, when compared to single-slice CT or other imaging modalities.However, MDCT offers some valuable options to save radiation exposure, such as choosing optimized exposure parameters or its superior dose efficiency in comparison to single-slice CT. Multi-phasic examinations should be restricted to indications where definitely necessary. Modern scanners offer intelligent tools for further reduction of radiation dose, such as ECG- or bodyshape-based realtime dose modulation. A new field of applications is the low-dose CT for early detection of diseases. While acquiring thin slices with high spatial resolution, the dose can be reduced to similar values as in conventional radiography, especially when examining under high-contrast conditions. Using all these various options available, radiation exposure can sometimes even be lower than using a conventional single-slice helical CT.

Artificial Intelligence↗
PubMed2002

[New abdominal CT angiography protocol on a 16 detector-row CT scanner - first results].

PURPOSE: Purpose of this study was the implementation of a new abdominal CT angiography protocol on a 16 detector-row CT scanner and the comparison to selective catheter angiography. METHODS: 76 patients with various vascular disorders underwent abdominal CT angiography on a recently developed 16 detector-row CT scanner using submillimeter slice collimation (16 x 0.75 mm). Results were compared with mesenteric and/or hepatic angiography in 17 patients performed during tumor embolization. Opacification was provided using individually tailored contrast application with a test bolus setting. To evaluate the contrast injection protocol density measurements within the vessel lumen were performed. RESULTS: Diagnostic image quality was achieved in all patients with angiographic comparison (n = 17). Within the hepatic and mesenteric vasculature up to 4th generation vessels could be identified. Compared to selective angiography CT angiography provided equivalent morphologic information up to the detectable vessel generation. With the applied contrast application regimen there were no significant differences in vessel enhancement along the abdominal aorta and iliac arteries. CONCLUSION: 16 detector-row CT enables whole abdominal angiographic studies with submillimeter resolution in a single breath-hold. The improved spatial resolution enables for high quality 3D visualization. Compared to invasive angiography, 16 detector-row CT reveals equivalent morphologic information.

Abdomen↗
PubMed2001

Multislice CT imaging of pulmonary embolism.

In recent years CT has been established as the method of choice for the diagnosis of central pulmonary embolism (PE) to the level of the segmental arteries. The key advantage of CT over competing modalities is the reliable detection of relevant alternative or additional disease causing the patient's symptoms. Although the clinical relevance of isolated peripheral emboli remains unclear, the alleged poor sensitivity of CT for the detection of such small clots has to date prevented the acceptance of CT as the gold standard for diagnosing PE. With the advent of multislice CT we can now cover the entire chest of a patient with 1-mm slices within one breath-hold. In comparison with thicker sections, the detection rate of subsegmental emboli can be significantly increased with 1-mm slices. In addition, the interobserver correlation which can be achieved with 1-mm sections by far exceeds the reproducibility of competing modalities. Meanwhile use of multislice CT for a combined diagnosis of PE and deep venous thrombosis with the same modality appears to be clinically accepted. In the vast majority of patients who receive a combined thoracic and venous multislice CT examination the scan either confirms the suspected diagnosis or reveals relevant alternative or additional disease. The therapeutic regimen is usually chosen based on the functional effect of embolic vascular occlusion. With the advent of fast CT scanning techniques, also functional parameters of lung perfusion can be non-invasively assessed by CT imaging. These advantages let multislice CT appear as an attractive modality for a non-invasive, fast, accurate, and comprehensive diagnosis of PE, its causes, effects, and differential diagnoses.

Humans↗
PubMed2000

Pulmonary embolism: comprehensive diagnosis by using electron-beam CT for detection of emboli and assessment of pulmonary blood flow.

PURPOSE: To comprehensively assess thoracic anatomy and pulmonary microcirculation in pulmonary embolism by using computed tomographic (CT) angiography of the pulmonary arteries combined with functional CT imaging of blood flow. MATERIALS AND METHODS: Twenty-two patients suspected of having acute pulmonary embolism underwent contrast material-enhanced thin-section electron-beam CT angiography of the pulmonary arteries. In addition, in each patient, a dynamic multisection blood flow CT study was performed on a 7.6-cm lung volume with electrocardiographic gating. Pulmonary blood flow was calculated, and perfusion parameters were visualized on color-coded maps. The color-coded maps and CT angiograms were independently evaluated, segment by segment, by two readers for perfusion deficits and the presence of clots, respectively. The results were compared. RESULTS: Mean pulmonary blood flow was 0.63 mL/min/mL in the occluded segments versus 2.27 mL/min/mL in the nonoccluded segments (P: =.001). The sensitivity and specificity of perfusion maps for the presence of segmental pulmonary embolism compared with those of CT angiography were 75.4% and 82.3%, respectively, with positive and negative predictive values of 79.6% and 84.7%, respectively. The false-negative findings were caused mainly by partial occlusion of vessels. In eight patients, a substantial alternative or additional pathologic entity was diagnosed. CONCLUSION: By combining CT angiography and dynamic CT imaging, a comprehensive and noninvasive diagnosis of thoracic structure and function is feasible with a single modality.

Acute Disease↗
PubMed1996

Different inducibility of expression of the two xylanase genes xyn1 and xyn2 in Trichoderma reesei.

Regulation of formation of the extracellular xylanase system of Trichoderma reesei QM 9414 during growth on xylan, cellulose, and replacement onto a number of soluble inducers was investigated by Northern analysis of xyn1 and xyn2 transcripts and by the use of the Escherichia coli hph (hygromycin B-phosphotransferase-encoding) gene as a reporter. Whereas the xyn1 promoter is active in the presence of xylan and xylose, and virtually silenced in the presence of glucose, the xyn2 promoter enables basal transcription at a low level, but is enhanced in the presence of xylan and xylobiose and also of sophorose or cellobiose. The respective regulatory nucleotide regions were localized on a 221-base pair fragment and a 55-base pair fragment of the xyn1 and xyn2 5'-upstream noncoding sequences, respectively. Electrophoretic mobility shift assays, using cell-free extracts, identified induction-specific protein-DNA complexes: one complex of high mobility was observed under basal, noninduced conditions (glucose) with xyn2, which was in part replaced by a slow-migrating complex upon induction by xylan or sophorose. Both complexes bound to a CCAAT box. With xyn1, the induced complex also binds to a CCAAT box, but this binding is not observed in the presence of the carbon catabolite repressor Cre1, which binds to a nearby located consensus motif.

Base Sequence↗
PubMed1996

Immunomodulatory effects of interleukin-2 and interleukin-4 in patients with malignancy.

A phase I trial of simultaneously administered recombinant interleukin-2 (rIL-2) and recombinant human IL-4 (rHuIL-4) was conducted to evaluate the toxicity and the clinical and immunologic effects of this cytokine combination. Thirty-nine eligible patients with refractory malignancy were treated at eight different dose levels (1A to 3B): 1-3 of rIL-2 [3.0, 12.0, and 48.0 x 10(6) IU/m(2) i.v. three times weekly (TIW)] and A-C of rHuIL-4 (40, 120, and 400 mu g/m(2) s.c. TIW). The toxicity of these two cytokines was moderate and was comparable with that seen with rIL-2 alone. The maximal tolerated dose (MTD) of the combination was not reached because of lack of sufficient rHuIL-4 but is at least 48.0 x 10(6) IU/m(2) of rIL-2 and 120 mu g/m(2) of rHuIL-4. Two patients with melanoma had partial responses. The immunologic effects included increases in absolute lymphocyte numbers, and the CD3- /CD56+/ CD2+, total CD56+, CD8+, and CD16c+ lymphocyte subsets with increasing rIL-2 dose levels, but not with rHuIL-4. This increase in natural killer (NK) cells in the peripheral blood was accompanied by an increase over baseline in NK lytic activity against K562 targets; however, concomitant increases in lymphokine-activated killer (LAK) activity (Daudi targets) were not seen. The CD3+, CD4+, and CD3+/CD25+/HLA-Dr+ T-cell subsets also increased, and these increases were related to both increasing rIL-2 and rRuIL-4 doses. Finally, in four of six patients, serial tumor biopsies demonstrated increases in major histocompatibility complex (MHC) class I or II antigen expression on tumor cells or increasing T-cell infiltrates during cytokine therapy or both. This trial demonstrated that rIL-2 and rHuIL-4 can be administered simultaneously with acceptable toxicity. The immunologic findings demonstrated the expected rIL-2-associated increases of CD56+ and CD16c+ lymphocytes and NK activity, and interestingly, no development of LAK activity. These findings suggest regulatory effects of rHuIL-4 on rIL-2-related effects in vivo.

Adjuvants, Immunologic↗
PubMed1996

Glucose-induced secretion of Trichoderma reesei xylanases.

To produce two xylanases with Trichoderma reesei grown on glucose, recombinant strains which carry either the xyn1 or the xyn2 (xylanase I and II [XYN I and XYN II]-encoding) structural genes under the expression signals of the homologous pki1 (pyruvate kinase-encoding) gene were constructed. The two types of transformants secreted XYN I or II, respectively, during growth on glucose, as demonstrated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunostaining. The corresponding specific xylanase activities of the best transformants on glucose were 76 and 145 U/mg of protein for XYN I and XYN II, respectively, as opposed to that obtained by the parent strain (26 U/mg of protein). When related to the amount of biomass formed, however, they produced only about 4 to 5 U/g, in contrast to much higher activities (10 to 12 U/g) during growth on xylan. The ultrastructural location of XYN II in the transformant strain producing the highest constitutive XYN II formation (ATX2-12) was investigated by immunoelectron microscopy and compared with that in the wild-type strain growing on xylan. Cell extracts from both types of transformants grown on glucose exhibited a higher intracellular xylanase activity than did the parent strain grown on xylan. By using electron microscopy and immunogold labelling, XYN II was detected in the endoplasmic reticulum, Golgi-like vesicles, secretory vesicles, vacuoles, and cell walls. The immunolabel in the vacuoles was detected preferentially in subapical cells. When a recombinant strain which expressed xyn2 from the pki1 promoter was compared with the parent strain during growth on xylan, the former exhibited a less proliferated endoplasmic reticulum and a smaller number of secretory vesicles; however, a higher density of labelling was observed. The relationship of these findings to the efficacy of protein secretion during growth on glucose is discussed.

Base Sequence↗
PubMed1995

Complex replication error causes p53 mutation in a Li-Fraumeni family.

We demonstrated a germline p53 replication error in two generations of a Li-Fraumeni family affected with liposarcoma, adrenocortical carcinoma, and osteosarcoma. The trinucleotide repeat mutation changed 5'-AGT GTG GTG GTG-3' at codons 215-218 to 5'-AGT TGG TTG GTG GTG-3'. The predicted protein would be elongated by one amino acid (val216-->trp leu) without a change in charge. Detection of p53 in the adrenal tumor by immunostaining suggested that the mutant protein was expressed. Persistence of the mutation in the germline may suggest a defect in DNA repair in the family member first affected. This is the first report where germline transmission of replication-damaged p53 trinucleotide repeats is associated with the Li-Fraumeni syndrome.

Adrenal Cortex Neoplasms↗
PubMed1995

[Plasma endothelin concentration during cold provocation in primary Raynaud's syndrome].

Plasma endothelin concentration was measured separately in each hand before and after unilateral whole-hand cooling in 23 patients (5 men, 18 women; mean age 35.2 [19-52] years) thought to have primary Raynaud's syndrome (Raynaud's disease). The diagnosis was confirmed, after excluding other causes, by strain-gauge plethysmography demonstrating cold-induced vasospasm in 8, disproved in 15. In the Raynaud patients (but not in the others) the plasma concentration of endothelin on the cooled side increased from 5.13 +/- 0.18 to 6.34 +/- 0.35 pg/ml (P < 0.05). On the non-cooled side there occurred a brief rise in endothelin concentration from 5.10 +/- 0.18 to 6.23 +/- 0.35 pg/ml (P < 0.05), although there had been no evidence of vasospasm. There had been no difference between the two sides in endothelin concentration before the cold provocation. The results suggest that cold provocation in primary Raynaud's syndrome causes an increase in endothelin liberation and that this plays a role in the pathogenesis of the vasospasms. Apparently not only local but also reflex mechanisms contribute to this.

Adult↗
PubMed1995

[Adenomatous hypophyseal apoplexy. Clinical, diagnostic and therapeutic aspects of a frequently misdiagnosed emergency state].

Pituitary adenoma apoplexy was considered an acute life-threatening condition until more benign and even asymptomatic courses were found by advanced neuroimaging procedures. Necrosis and hemorrhage in the pituitary adenoma can cause acute enlargement of the tumor. sometimes with rupture of the tumor capsule and bleeding into the subarachnoid space and surrounding parts of the brain. Clinical symptoms include acute or subacute headache in combination with signs of meningeal irritation and neuroophthalmological and cerebral dysfunction. Severe panhypopituitarism may be an additional complication. Acute blindness due to compression of the optic chiasm and symptomatic compression of basal cerebral arteries require immediate transsphenoid tumor resection. If panhypopituitarism is suspected, immediate hormone substitution is necessary.

Adenoma↗
PubMed1994

[An unusual paternity dispute case: classical methods did not rule out either of the two possible fathers].

The author described an uncommon case when neither of two men (former husband and another man) who were considered possible fathers of the child, could be ruled out as potential fathers based on examination of signs of 19 erythrocyte, serum and enzyme systems and 59 HLA-A, B, C antigens and their subtypes. The eliminating capacity of the examination was 99.86%; paternity was, based on probability calculation, practically proved (p = 99.9925% and 99.90%). According to statements of parties in the dispute the other man is the child's father. The author discusses perspectives of DNA examinations.

Female↗
PubMed1994

Phase I/II trial of dipyridamole, 5-fluorouracil, leukovorin, and mitoxantrone in metastatic breast cancer.

Based upon the hypothesis that dipyridamole would potentiate the cytotoxicity of mitoxantrone and the combination of 5-fluorouracil (5-FU) and leukovorin, we performed a phase I/II trial of the combination of dipyridamole, 5-FU, leukovorin, and mitoxantrone in patients with metastatic breast cancer. The dose of dipyridamole was fixed at 175 mg/m2 by mouth every 6 h (700 mg/m2/day), based upon a previous phase I trial of oral dipyridamole with 5-FU and leukovorin. Dipyridamole therapy began 24 h prior to the first dose of chemotherapy and continued until 24 h after the last dose of chemotherapy for each course of treatment. At the initial dose level, leukovorin 200 mg/m2 was given intravenously immediately prior to 5-FU 375 mg/m2 intravenously on days 1-5. Mitoxantrone 6 mg/m2 was given as a single dose on day 3. Unacceptable toxicity was observed at this dose level, leading to successive dose decrements rather than dose increments. The maximum tolerated dose was leukovorin 200 mg/m2 days 1-2, 5-FU 375 mg/m2 days 1-2, mitoxantrone 6 mg/m2 on day 2, and dipyridamole 175 mg/m2 every 6 h on days 0-3. Two responses were produced in 15 patients. This regimen is not recommended for further investigation in the treatment of breast cancer.

Adult↗