Biomedical subjects

H Schicha

Publications and source records attributed to H Schicha.

At least 127 records · Page 7Linked to original sources

PubMed1997

Fluorine-18 fluorodeoxyglucose positron emission tomography and iodine-131 whole-body scintigraphy in the follow-up of differentiated thyroid cancer.

Metastases of differentiated thyroid cancer may show different uptake patterns for fluorine-18 fluorodeoxyglucose and [131I]NaI. FDG positron emission tomography (PET), iodine-131 whole-body scintigraphy (131I WBS) and magnetic resonance imaging were performed in 58 unselected patients, and spiral computed tomography (CT) of the lung in 25 patients. Thirty-eight patients presented with papillary carcinomas, 15 patients with follicular carcinomas and five patients with variants of follicular carcinoma. Primary tumour stage (pT) was pT1 in 3, pT2 in 19, pT3 in 11 and pT4 in 25 cases. For the detection of metastases, FDG PET was found to have a sensitivity of 50%, 131I WBS a sensitivity of 61%, and the two methods combined a sensitivity of 86%. When FDG PET was limited to patients with elevated thyroglobulin (Tg) levels and negative 131I WBS, the sensitivity of this algorithm was 82%. Of the 21 patients with lymph node metastases, seven presented with FDG uptake but no iodine uptake. In four of them, a second FDG hot spot appeared in a lymph node metastasis of normal size. Five of the seven patients underwent surgery. None of the eight patients with pulmonary metastases smaller than 1 cm exhibited FDG uptake, while five of them had iodine uptake. All had positive results on spiral CT. In conclusion, FDG PET cannot be substituted for 131I WBS. If the Tg level is elevated and 131I WBS is negative, FDG PET can be used to detect lymph node metastases and complements anatomical imaging. A spiral CT of the lung is useful to exclude pulmonary metastases before planning a dissection of iodine-negative lymph node metastases.

Adult↗

PubMed1997

[Non-transmural anterior wall infarct: changes in myocardial energy metabolism in remaining vital myocardium].

To characterize energy metabolism in vivo after nontransmural anterior myocardial infarction, patients (group A, n = 19) with a stenosis of left anterior descending artery (LAD) and anterior wall hypokinesia by levocardiography were examined by phosphorus magnetic resonance spectroscopy (MRS). Spectra were compared to those of healthy volunteers (n = 15). The volume of interest was placed into the anterior myocardial wall by magnetic resonance imaging. Phosphorus spectra were recorded under optimal antiischemic medication. To separate the influence of coronary stenosis from that of the ischemic insult, additional patients (group B, n = 4) with LAD-stenosis but without left ventricular dysfunction were examined. The effect of antiischemic medication on the phosphorus spectra was evaluated in patient group C (n = 4), who had the same clinical features as group A. In these patients, MRS was first performed without antiischemic medication (washout period > one day) and then repeated during intravenous application of glyceroltrinitrate (GTN). Mean PCr/ATP-ratio was significantly lower in group A patients (1.24 +/- 0.18) than in healthy volunteers (1.74 +/- 0.23; p < 0.01 unpaired t-test). Patients with normal left ventricular function (group B) showed PCr/ATP-ratios (1.64 +/- 0.22) similar to those of normal controls (p = 0.23). After GTN infusion PCr/ATP-ratio of group C rose from 1.12 +/- 0.08 to 1.32 +/- 0.13 (p < 0.01 paired t-test). Thus, hypokinetic myocardium after nontransmural infarction is characterized by a larger decrease of the cellular energy buffer PCr compared to the myocardial ATP-content. These findings may reflect degenerative changes of myocytes due to disturbed microperfusion in viable areas of the infarct or remodeling processes of viable myocytes in the infarct region. Both mechanisms may lead to adaptive changes of cellular enzyme concentrations resulting in a reduced PCr content of the myocytes.

Adenosine Triphosphate↗

PubMed1997

Magnetic resonance imaging in valvular heart disease.

Magnetic resonance techniques can be employed to depict valvular abnormalities but are especially helpful in quantifying regurgitant or stenotic lesions which cannot be quantitatively assessed by other noninvasive techniques. Gradient echo techniques and phase velocity mapping are the most important magnetic resonance pulse sequences employed for these purposes. Valvular regurgitation can be quantitated by measuring the area of signal void on conventional gradient-echo images, by calculating stroke volume differences from k-space segmented gradient echo images, by measuring the proximal convergence zone from velocity encoded images or by comparing stroke volumes of the ventricles from velocity measurements. In contrast to this variety of possibilities in regurgitant lesions, stenotic lesions can only be quantitated by using velocity mapping techniques. Magnetic resonance spectroscopy can be used to assess myocardial metabolism in chronic valvular lesions. However, this tool needs further development and more clinical data before its use can be recommended to assess the necessity and optimal timing of surgical intervention.

Aortic Valve Insufficiency↗

PubMed1997

Dipyridamole scintigraphy and intravascular ultrasound after successful coronary intervention.

UNLABELLED: Despite angiographically successful interventions, perfusion defects are not uncommonly observed in postinterventional perfusion scintigrams. The aim of this study was to test the hypothesis that perfusion defects after coronary intervention are associated with a significant residual stenosis in the treated vessel segment detectable by intravascular ultrasound but not by angiography. METHODS: Forty consecutive patients with angiographically successful coronary interventions were prospectively studied by intravascular ultrasound immediately after the intervention. Within 48 hr after the intervention all patients had myocardial scintigraphy using 99mTc-methoxyisobutyl-isonitrile SPECT after dipyridamole stress. Myocardial perfusion defects in the scintigram were assigned to a segmental left ventricular model and compared to the perfusion territory of the treated vessel estimated from the coronary angiogram. RESULTS: Twenty of 40 patients had reversible myocardial perfusion defects. Mean ultrasound area stenosis was 50% in these patients and 33% in patients without perfusion defects (p < 0.002); ultrasound percent plaque area was 75% versus 63% (p < 0.0001), respectively. The best concordance between residual area stenosis and perfusion defects was found for an ultrasound area stenosis > or = 40%. CONCLUSION: Patients with stress-induced myocardial perfusion defects immediately after successful coronary intervention show high-grade residual stenoses that are more pronounced in patients with perfusion defects than in patients with normal postinterventional scintigrams. In addition, vessels serving myocardial regions with perfusion defects showed a significantly higher plaque burden indicating diffuse atherosclerotic changes in the vessel. The evaluation of the postprocedural result by intravascular ultrasound contributes to a better understanding of the discrepancy between the angiographic finding of a widely patent vessel but scintigraphic evidence of impaired perfusion.

Adult↗

PubMed1997

[Influence on extratumoral organ activities of tumor-affinity samarium-153 preparations].

AIM: Possibilities to exercise an influence on the biodistribution of a tumor-affine 153Sm-preparation, samarium-153-nitrilotriacetate (NTA), were tested. METHODS: Animals experiments on tumor-bearing mice after additional application of EDTMP (ethylenediamine tetramethylene phosphonate) for the reduction of extratumorale liver-radioactivity and yttrium chloride for the reduction of unwanted underground radioactivity in bone were carried out. Furthermore, the combination of both measurements was tested. RESULTS: The biodistribution of 153Sm-NTA showed a rather low tumor-radioactivity of app. 0.72%/g. The additional EDTMP-application caused a dose-dependent decrease of the underground-radioactivity in liver especially if given 2 h in advance or simultaneously. The additional application of the stable yttrium salt reduced the bone radioactivity on simultaneous increase of liver- and spleen-radioactivity and practically unchanged tumor-radioactivity. The combined use of EDTMP together with the bone-affine metal salt led to a reduction of liver radioactivity on simultaneous reduction of bone radioactivity. CONCLUSIONS: The background radioactivity can be reduced on unchanged tumor-radioactivity by combined Na-EDTMP/YCl3-application. The present results do not allow a therapeutic exploitation because of the low tumor accumulation.

Animals↗

PubMed1997

[Effect of antithyroid medication on the effective half-life and uptake of 131-iodine following radioiodine therapy].

AIM: A radioiodine therapy (RIT) in thyrotoxic patients receiving antithyroid drugs (ATD) leads in comparison to nonpretreated patients either to higher therapeutic doses or to higher treatment failure rates. Aim of this study was to optimize the effect of RIT in patients pretreated with ATD. METHODS: Therefore, the influence of ATD was assessed in 109 patients with shortened effective half-life of 131I. RIT was performed under stationary conditions. Radioiodine activity of the thyroid gland was measured twice a day. In 77 patients antithyroid medication was stopped three days after RIT. The progress of the first RIT and of a second radioiodine application, which still was necessary in 29 patients, was compared to 32 patients receiving ATD, continuously. RESULTS: Values of effective half-life for 131I rose significantly from 3.2 +/- 0.2 to 5.7 +/- 0.2 days (Graves' disease: 3.4 to 5.7 days; toxic goiters' disease: multifocal autonomy 3.2 to 6.2 days; unifocal autonomy 2.5 auf 5.0 days) 2-3 days after stopping ATD. There was an increase of the 131I-uptake of a second after stopping ATD, too. In contrast, 131I-uptake of a second RIT decreased significantly in patients receiving ATD, continuously. CONCLUSION: Effective half-life and uptake of 131I was affected significantly by ATD. The stop taking of ATD after RIT is useful to improve an apparent insufficient RIT in thyrotoxic patients receiving ATD.

Adult↗

PubMed1997

[Radioiodine therapy in differentiated thyroid gland carcinoma].

The current level of knowledge about radioiodine therapy (RITh) for well-differentiated thyroid carcinoma under consideration of the recent literature is summarised. In RITh for thyroid carcinoma two major fields can be distinguished: the ablation of the thyroid remnant and the therapy of recurrences resp. local and distant metastases. New large American studies indicate, that the prophylactic post operative ablation of the thyroid remnant in primary tumours over 1.5 cm in diameter is linked with a distinct improvement of the long-term prognosis. The RITh is effective also in distant metastases, if applied early, when the tumour volume is still small. The prerequisite is an appropriate follow-up. Surveys about the application of RITh for well-differentiated thyroid carcinoma in Europe and in the USA reveal that uniform treatment recommendations designed to conform interdisciplinary demands are urgently required.

Adolescent↗

PubMed1997

[Nuclear medicine diagnosis--principles and indications].

Diagnostic procedures in nuclear medicine are functional studies of localized processes. The gathered informations are generally different to those acquired by imaging methods such as ultrasound and x-ray. Frequently, both methods are complementary. This review provides survey about the scintigraphic diagnostic procedures of following organs: Endocrine organs, especially the thyroid gland; heart, especially myocardial perfusion and viability, functional studies of the kidney, lung ventilation and perfusion, bone, bone marrow and inflammation, brain, gastrointestinal tract diagnostics and tumour scintigraphy.

Equipment Design↗

PubMed1997

[Cost minimization analysis for the definitive therapy of hyperthyroidism: comparison of goiter resection with radioiodine therapy].

AIM: Cost-analysis of strumaresection and radioiodine treatment in patients with hyperthyreosis. METHOD: Matched by age, sex, comorbidity, volume of goiter, and entity of hyperthyreosis 18 patients of a clinic of surgery, and 28 patients of a clinic of nuclear medicine were analysed by the reimbursed costs, and by a retrospective calculation of the real costs. RESULTS: Based on the rate for the reimbursed costs the radioiodine treatment (6450 DM) was more favourably than the strumaresection (7562 DM); based on the calculation of the real costs including regional specialities there was a minimal difference in favour of the strumaresection (5185 DM versus 5562 DM) because of the selection of large goiters (median 53 ml), the longer hospitalisation after radioiodine treatment due to legal reasons (12.5 days), and the frequent controls before and after the radioiodine treatment. Most important cost-factor of the radioiodine treatment was the volume of goiter, most important cost-factor of the strumaresection was the age of the patient. The treatment of Graves disease was more expensive than that of autonomy in surgery as well as in nuclear medicine. CONCLUSION: In order to achieve cost-minimization, radioiodine treatment should be prefered in cases of small goiters or in older patients.

Cost-Benefit Analysis↗

PubMed1997

[99m-Tc-MIBI SPECT parathyroid gland scintigraphy for the preoperative localization of small parathyroid gland adenomas].

AIM: It was the of this study to assess the value of the 99mTc-MIBI scintigraphy in SPECT technique in the preoperative lateral location of small parathyroid adenoma (PTA). METHODS: 25 consecutive patients (8 male, 17 female, mean age 63 +/- 13 years) with the established diagnosis of primary hyperparathyroidism and non-diagnostic ultrasonography were scanned preoperatively. After a thyroid examination to exclude radionuclide accumulating thyroid adenoma, planar and tomographic images were acquired 20 min. and 120 min. after i.v. injection of 740 MBq 99mTc-MIBI using a 3 head gamma camera (Picker Prism 3000). The first 10 patients underwent an additional 201Tl/99mTc subtraction scintigraphy in a 2 days protocol. RESULTS: All patients had small, solitary PTA (< 1 g). 201Tl/99mTc subtraction scintigraphy (n = 10) showed only a sensitivity of 50%. Using planar MIBI-scintigraphy lateral location of PTA was possible in 18 cases (sensitivity: 72%). There was an increase in sensitivity up to 96% using the SPECT technique and the 3D display (volume-rendered reprojection). CONCLUSION: In contrast to 201Tl/99mTc subtraction scintigraphy, which showed only a low sensitivity, a reliable lateral location of small PTA was obtained using the tomographic 99mTc-MIBI scintigraphy. This method offers e.g. the possibility for the surgeon to perform an unilateral parathyroidectomy.

Adenoma↗

PubMed1996

Comparison of dobutamine transesophageal echocardiography and dobutamine magnetic resonance imaging for detection of residual myocardial viability.

A dobutamine-induced contraction reserve in akinetic but viable myocardium, observed by echocardiography or magnetic resonance imaging (MRI), is a reliable indicator of myocardial viability. However, the comparative diagnostic accuracy of these 2 techniques is unknown. Therefore, 43 patients with myocardial infarction (infarct age > or = 4 months) and regional akinesia underwent dobutamine transesophageal echocardiography (TEE) and dobutamine MRI (10 microg dobutamine/ min/kg). Both imaging techniques were compared with the reference standard 18F-fluorodeoxyglucose positron emission tomography (FDG PET). An infarct region was considered viable if a dobutamine contraction reserve could be assessed visually by TEE or quantitatively by MRI in > or = 50% of segments graded "a" or dyskinetic at rest. Infarct regions were graded viable by PET if FDG uptake was > or = 50% of the maximal FDG uptake in a region with normal wall motion by left ventriculography. A dobutamine contraction reserve was found in 21 of 43 patients (49%) by TEE and MRI. A viable infarct region by FDG PET was diagnosed in 26 of 43 patients (60%). FDG uptake and dobutamine TEE were concordant in 36 of 43 patients (84%) and dobutamine MRI and FDG PET were concordant in 38 of 43 patients (88%). Sensitivity and specificity of dobutamine TEE and dobutamine MRI for FDG PET-defined myocardial viability were 77% versus 81% and 94% versus 100%, respectively. Both imaging techniques yielded similar results for the detection of myocardial viability as defined by FDG uptake, with a slightly higher sensitivity and specificity for the quantitatively evaluated dobutamine contraction reserve by MRI.

Adrenergic beta-Agonists↗

PubMed1996

Qualitative [18F]FDG positron emission tomography in primary breast cancer: clinical relevance and practicability.

Positron emission tomography (PET) using fluorine-18 2-deoxy-2-fluoro-d-glucose (FDG) is of potential value for the diagnosis of malignant tumours. The aim of this study was to evaluate the use of FDG PET in patients with breast tumours, appraising its applicability in visualising primary carcinomas and regional metastases in a clinical setting. Results of FDG PET were compared with those of mammography, breast ultrasonography and histology in 30 patients with inconclusive breast findings. For PET, transmission and emission images were taken in one or two scan positions, depending on the available time and the clinical status of patients. PET showed focal FDG uptake with high contrast in 21 of 23 primary carcinomas. In one patient, only PET correctly visualized multifocal disease (three foci, O 0.4-1 cm). The accuracy of PET in the detection of primary breast cancer was 90%, and in the detection of involved axillary lymph nodes, 94%. All metastases (lymph nodes, lungs, bones, soft tissues) covered by the field of view and demonstrated by other methods (X-ray, computed tomography, magnetic resonance imaging, bone scan) showed FDG uptake. In three patients, only PET initiated further diagnostic procedures. The results indicate that FDG PET can provide a rapid diagnostic study (45-60 min) and allows accurate tumour staging of several organ systems for primary tumour and metastases with a single imaging study in a routine clinical setting.

Breast Neoplasms↗

PubMed1996

Predictive value of low dose dobutamine transesophageal echocardiography and fluorine-18 fluorodeoxyglucose positron emission tomography for recovery of regional left ventricular function after successful revascularization.

OBJECTIVES: This study was designed to assess the predictive value of myocardial viability diagnosed by dobutamine transesophageal echocardiography and fluorine (F)-18 fluorodeoxyglucose positron emission tomography for left ventricular functional recovery after revascularization in patients with chronic left ventricular dysfunction. BACKGROUND: The identification of akinetic but viable myocardium is of particular importance for the selection of patients with a compromised left ventricle who will benefit from coronary revascularization. METHODS: Multiplane rest and dobutamine transesophageal echocardiography (dobutamine, 5 and 10 microg/min per kg) studies and F-18 fluorodeoxyglucose positron emission tomographic studies at rest were performed in 2 patients with 1) previous myocardial infarction and regional akinesia, 2) a stenosed infarct-related coronary artery, and 3) a patent infarct-related vessel after revascularization. A basally akinetic segment was considered viable by transesophageal echocardiography if dobutamine-induced contractile reserve could be observed. Viability by positron emission tomography was defined as F-18 fluorodeoxyglucose uptake > or = 50% of the maximal uptake in a region with normal wall motion. Recovery of regional left ventricular function 4 to 6 months after revascularization was diagnosed by transesophageal echocardiography if > or = 50% of segments akinetic at baseline had improved wall thickening. RESULTS: Dobutamine transesophageal echocardiography identified viable infarct regions in 25 (59%) of 42 patients, and F-18 fluorodeoxyglucose positron emission tomography in 30 (71%) of 42 patients, yielding diagnostic agreement in 86% of patients. Sensitivity and specificity for prediction of left ventricular functional recovery in individual patients was 92% and 88%, respectively, for dobutamine transesophageal echocardiography versus 96% and 69% for F-18 fluorodeoxyglucose positron emission tomography. Segments remaining akinetic after revascularization had a significantly lower (p < 0.001) F-18 fluorodeoxyglucose uptake (48 +/- 15%) than that (73 +/- 15%) of segments with recovery of regional left ventricular function. CONCLUSIONS: Both dobutamine transesophageal echocardiography and F-18 fluorodeoxyglucose positron emission tomography were highly sensitive in predicting functional recovery of chronically kinetic or dyskinetic myocardium after successful revascularization. Thus, dobutamine transesophageal echocardiography is a clinically valuable alternative to F-18 fluorodeoxyglucose positron emission tomography for assessing residual viability and predicting functional recovery after revascularization.

Adrenergic beta-Agonists↗

PubMed1996

Congenital heart disease in adults and adolescents: comparative value of transthoracic and transesophageal echocardiography and MR imaging.

PURPOSE: To compare the diagnostic value of transesophageal echocardiography and magnetic resonance (MR) imaging with that of transthoracic echocardiography in the evaluation of congenital heart disease in adults and adolescents. MATERIALS AND METHODS: Corresponding transesophageal echocardiographic and MR images obtained in 61 patients (aged 14-74 years; 28 female, 33 male) with congenital cardiac abnormalities were analyzed retrospectively. Results were compared with those of transthoracic echocardiography in all patients and were confirmed by using cardiac catheterization (n = 41) and/or surgery (n = 41). RESULTS: of the 344 abnormalities detected with at least one imaging technique, 259 were demonstrated with transthoracic echocardiography. Transesophageal echocardiography depicted the atrioventricular junction and atrial structures the best. MR imaging was the only technique to fully depict 31 extracardiac abnormalities. In complex cardiac defects, the combination of all three imaging techniques was best. CONCLUSION: Transesophageal echocardiography and MR imaging are beneficial complementary imaging techniques in adults or adolescents with congenital heart disease.

Adolescent↗

PubMed1996

[Influence of physiological and pharmacological amounts of iodine on the 131I uptake of the thyroid gland--a model calculation].

AIM: The aim of this paper was to use a iodine metabolism model in order to analyze theoretically the different aspects of the iodine metabolism. METHOD: To perform this a three compartment model was developed. RESULTS: With this model we examined the influence of physiological and pharmacological iodine amounts on the iodine-131 uptake in the thyroid gland and additionally the excretion of Iodine-131 after radiotherapy. It can be said, that an in-patient admission for a duration of at least three days to perform a radiotherapy is sensible (wise) and a iodine-poor diet prior to the radiotherapy is of advantage. Regarding the iodine blockade of the thyroid gland after a reactor accident the effects (outcome) of the German recommendations were compared with the WHO-guidelines. CONCLUSION: The model of iodine metabolism is suited for analyses even if because of ethic or other limitations measurements at human beings are not possible.

Germany↗

PubMed1996

[Volume reduction of the thyroid after radioiodine therapy in patients with autonomous goiter and Basedow's goiter].

AIM: It is well known that radioiodine therapy (RITh) leads to a significant thyroid volume reduction (TVR). But until now only little data has been presented due to the course of time and the extent of TVR. METHOD: Therefore the data of 33 patients with Graves' disease (GD), 36 patients with multifocal (MAG) and 31 with solitary (SAG) autonomous goitre were analyzed retrospectively. RESULTS: All the patients showed a highly significant (p < 0.001) TVR, which continued up to 1 year after RITh. Receiving equal effective radiation doses, the extent of TVR was significantly greater for GD than for MAG. This difference developed within six weeks up to 3 months after RITh. CONCLUSION: This observation suggests that the underlying thyroid disease affects the therapeutic effect of RITh and may be partially explained by the total suppression of non-autonomous thyroid tissue in AG at the time of RITh. In patients with SAG with a 1.7 times higher effective radiation dose than in MAG relative TVR was about 1.6 times stronger in SAG than in MAG. This demonstrates a direct relation between the effective radiation dose and the extent of the TVR after RITh.

Female↗

PubMed1996

[Increase in TSH levels in thyroid carcinoma patients after withdrawal of suppressive levothyroxine medication].

AIM: In 76 patients with thyroid carcinoma (60 f., 16 m.; age 51 +/- 15 years; 52 with papillary, 22 with follicular, 2 with Hürthle cell thyroid carcinoma), three different schemes to withdraw LT4 before 131I whole body scintigraphy were compared. METHOD: In scheme I no interval LT3 medication is applied. Scheme II starts one week after withdrawal of LT4 with a two weeks lasting LT3 medication: 40-80 micrograms LT3/die in the first week and 20 micrograms LT3/die in the second week. Afterwards no further LT3 medication is given. Scheme III is identical to scheme II in the first three weeks but 20 micrograms LT3 medication is continued until 131I-application. Retrospectively 121 studies were evaluated concerning the scheme specific increase of TSH. Factors which may influence the increase of TSH were analysed, i.e. age, sex, thyreoglobuline, LT4 dose, duration of LT4 treatment, histological type of carcinoma, result of 131I whole body scanning. RESULTS: There was a significant relation between increase of TSH and the applied scheme. Schemes with interval LT3 medication are more comfortable for the patient but time to stimulate TSH to values > or = 30 microIU/ml is prolonged, especially using scheme III. Female patients needed a significantly longer time compared to male patients to reach a TSH value > or = 30 microIE/ml. Concerning repetitive withdrawal of LT4, there was a fair intraindividual reproducibility of the time period from LT4 withdrawal to TSH values > or = 30 microIE/ml. CONCLUSION: Every scheme has its specific field of indication depending on the compliance of the patients.

Adenoma, Oxyphilic↗

PubMed1996

[Relationship between properties of 131I therapy and radioiodine kinetics].

AIM: The reason of unreproducible data under diagnosis and therapy with radioiodine should be elucidated. METHODS: The iodine content of the capsules was tested by a colorimetric method and by activation analysis. Radiochemical purity was determined by HPLC and by electrophoresis. Solubility of the capsules was investigated under different conditions. RESULTS: The iodine content of the capsules varied between 0.8 and appr. 100 micrograms/capsule. The radiochemical purity of the capsule iodine varied between 75% and 99.5% (main contamination: iodate). The solubility of the capsules differed. CONCLUSION: Additional non-radioactive iodine in the therapy capsules could be one reason of the reduced radioiodine-uptake under therapy.

Capsules↗