PubMed Health⌕ Search

Biomedical subjects

H W Mueller-Gaertner

Publications and source records attributed to H W Mueller-Gaertner.

8 recordsLinked to original sources
PubMed1999

Optimal scan time for fluorine-18 fluorodeoxyglucose positron emission tomography in breast cancer.

Fluorine-18 fluorodeoxyglucose positron emission tomography (FDG PET) has proven useful in the differentiation of various tumour entities, including breast cancer. In patients with primary breast cancer we performed a 3-h imaging protocol to examine possible improvements in tumour detectability and image contrast. Twenty-nine patients with primary breast cancer with a diameter of >/=2 cm that was demonstrated to be malignant by biopsy or surgery were injected with 370-740 MBq 18F-FDG and scanned in the prone position. Data were acquired 0-40 min, 1.5 h and 3.0 h after injection. After correction for measured attenuation, decay and scatter and iterative reconstruction, standardised uptake values (SUVs) and tumour-to-non-tumour and tumour-to-organ ratios were calculated. Visual analysis was performed using transverse, sagittal and coronal slices as well as 3D reprojection images. Tumour-to-non-tumour and tumour-to-organ ratios were significantly higher for the 3-h images than for the 1.5-h images. SUVs did not increase to the same extent. Lesion detectability was 83% in 1.5-h images compared to 93% in 3-h images. We conclude that tumour contrast in breast cancer is improved by starting the PET acquisition at 3 h p.i. rather than at 1.5 h p.i.

Adult↗
PubMed1995

Efficacy of simultaneous determination of bone alkaline phosphatase mass concentration in serum and urinary excretion of pyridinium cross-links for detection of bone metastases.

OBJECTIVES: To examine the diagnostic validity of bone alkaline phosphatase (BAP) in serum (a marker of bone formation) and of urinary excretion of pyridinium cross-links (PYR) (a marker of bone resorption) for detection of bone metastases. DESIGN AND METHODS: Two heterogeneous immunoassays were employed for determination of BAP mass concentrations (Tandem-R Ostase) in serum and the urinary excretion of PYR (Collagen Crosslinks) in a consecutive series of 89 tumor patients examined by bone scintigraphy (with 99mTc-methylene diphosphonate). RESULTS: The discrimination power (as determined by Z score analysis) and the accuracy (as assessed by the area under the receiver-operating characteristic curve) was higher for BAP (0.84) than for PYR (0.76). Combination of both markers yielded a further increase of accuracy (0.89). There was a correlation (r = +0.422; p < 0.001) between the urinary excretion of pyridinium cross-links and bone alkaline phosphatase mass concentrations in the whole of 89 patients examined. In 14 (16%) of 89 patients bone alkaline phosphatase values were within the reference interval in spite of total alkaline phosphatase activity being increased; this indicates a higher diagnostic specificity of bone alkaline phosphatase (compared with total alkaline phosphatase) with respect to detection of bone metastases. CONCLUSION: Simultaneous assessment of bone formation by BAP and of bone resorption by PYR provides a suitable tool for detection of bone metastases.

Adult↗
PubMed1995

Simultaneous assessment of bone collagen synthesis and degradation in patients with different malignant tumours. Comparison with the results of 99mTc-methylene bisphosphonate bone scintigraphy.

We report on the diagnostic validity of the serum concentrations of the C-terminal propeptide of type I procollagen (a marker of bone formation) and of the urinary excretion of deoxypyridinoline (a marker of bone resorption) in a consecutive series of 89 tumour patients who were routinely examined by 99mTc-methylene bisphosphonate bone scintigraphy for detection of bone metastases. Z score analysis reveals that the discriminating power of deoxypyridinoline is superior to that of calcium excretion whereas the discriminating power of the C-terminal propeptide concentrations is inferior to that of bone alkaline phosphatase values. Accuracy (as assessed by the area under the receiver-operating characteristic curve) was 0.75 for deoxypyridinoline and 0.82 for the C-terminal propeptide. Combination of both markers did not yield an increase of accuracy (0.82) compared with the determination of the C-terminal propeptide concentrations alone. There was a correlation (r = +0.398; p < 0.0001) between C-terminal propeptide concentrations and deoxypyridinoline excretion values in the group of 89 patients examined. Further studies should be done to elucidate whether the determination of bone collagen turnover is suitable as a screening procedure for detecting bone metastases.

Adult↗
PubMed1992

Improved positron emission tomography quantification by Fourier-based restoration filtering.

Positron emission tomography (PET) images are characterized by both poor spatial resolution and high statistical noise. Conventional methods to reduce noise, such as local weighted averaging, produce further deteriorations in spatial resolution, while the use of deconvolution to recover resolution typically amplifies noise to unacceptable levels. We studied the use of two-dimensional Fourier filtering to simultaneously increase quantitative recovery and reduce noise. The filter was based on inversion of the scanner's measured transfer function, coupled with high frequency roll-off. In phantom studies, we found improvements in both "hot" and "cold" sphere quantification. Compared with ramp-only filtering, improvements in hot spot recovery for the highest accuracy filter averaged 13.6% +/- 6.6% for spheres larger than 15 mm; improvements in cold spot recovery averaged 30.7% +/- 4.7%. At the same time, the noise was reduced by a factor of 3 compared with randomly filtering. Fourier-based image restoration filtering is thus capable of improving both accuracy and precision in PET.

Brain↗
PubMed1991

Prognostic indices for tumor relapse and tumor mortality in follicular thyroid carcinoma.

To establish an objective basis for therapeutic decisions and follow-up programs in patients with follicular thyroid cancer, the authors developed a prognostic scoring system. The prognostic impact of nine clinical, histologic, and therapeutic parameters was quantified retrospectively based on a multivariate analysis covering 149 patients. The relative relapse risk in follicular thyroid cancer (RR) was 6.8-fold increased in the presence of a moderate when compared with a high degree of histologic tumor differentiation. The RR rose with increasing age of the patient at time of tumor diagnosis by a factor of 1.8 per 20 years. The RR was reduced by a factor of 4.3 after the performance of a neck dissection and by a factor of 2.3 after percutaneous radiation therapy of the neck. The relative mortality risk in follicular thyroid cancer (RM) rose in the absence of a tumor capsule by a factor of 10, in the presence of a moderate compared with a high degree of histologic tumor differentiation by a factor of 5.9, in the presence of distant metastases by a factor of 3.2, and with increasing age of the patient at the time of tumor diagnosis by a factor of 2.2 per 20 years. From these data prognostic indices denoting the individual risk for tumor relapse (IRR index) and tumor mortality (IMR index) were calculated. The indices categorize patients into low-risk, medium-risk, or high-risk groups with regard to tumor relapse and tumor-related death. Consequently, the IRR and IMR indices contribute to select patients with follicular thyroid cancer who need an aggressive form of treatment and an intensive follow-up program. The indices may also be used for risk stratification in prospective therapy trials.

Adult↗
PubMed1988

3,5,3'-Triiodothyroacetic acid minimizes the pituitary thyrotrophin secretion in patients on levo-thyroxine therapy after ablative therapy for differentiated thyroid carcinoma.

The aim of this study was to examine the influence of 3,5,3'-triiodothyroacetic acid (TRIAC) on serum thyrotrophin (TSH) concentration in 25 patients on levo-thyroxine (L-T4) therapy after ablative therapy for differentiated thyroid carcinoma. The daily L-T4 intake amounted to 2.6 +/- 0.7 micrograms/kg body weight (+/- SD). Serum TSH concentration was determined by means of a sensitive radioimmunometric method (lower detection limit 0.03 mU/l). The median (means) basal TSH concentration under L-T4 amounted to 0.11 mU/l (range less than 0.03 mU/l-7.39 mU/l). During supplementary intake of 500 micrograms TRIAC daily the median basal TSH decreased to 0.04 mU/l range less than 0.03 mU/l-0.24 mU/l; P less than 0.0003). The TRIAC-induced decrease in 17 out of 20 basal TSH-concentrations exceeding 0.03 mU/l ranged from 38% to as much as 98%. TRIAC reduced the median TRH-stimulated TSH concentration from 0.25 mU/l (range less than 0.03 mU/l-47.3 mU/l) to 0.04 mU/l (range less than 0.03 mU/l-1.43 mU/l; P less than 0.0001). A blunted TSH-response to TRH occurred in 8.7% prior to and in 52% of the patients during TRIAC medication. Side effects such as nervousness, cardiac arrhythmia or tachycardia under supplementary TRIAC (500 micrograms daily) were observed in four patients. The conclusion is that the supplementary medication of 500 micrograms TRIAC daily in euthyroid patients on L-T4 medication after thyroid gland ablation for differentiated thyroid cancer is an effective means to minimize serum-TSH concentration.

Adult↗