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Biomedical subjects

P Knesewitsch

Publications and source records attributed to P Knesewitsch.

At least 19 recordsLinked to original sources
PubMed2005

[Guideline on radiation protection in medicine requires documentation of radioiodine therapy and follow-up: What are the benefits of an electronic database?].

AIM: The lately updated German guideline on radiation protection in medicine (Richtlinie Strahlenschutz in der Medizin) requires the physician who administers radioactive substances for therapy, to perform and document follow-ups. In order to decrease the administrative burden, an electronic database was developed that interfaces with a word processing software to generate written reports and statistic analysis. METHODS: Based on Microsoft Access and Microsoft Visual Basic a database was created to monitor patients with benign and malignant thyroid disorders after radioiodine therapy. It permits automatic creation of therapy documents and necessary patient reports in Microsoft Word. Intuitive handling, third level of normalization in database architecture and automatic plausibility checks guarantee integrity of the data and the efficacy of the database. RESULTS, CONCLUSION: The new software has been a success in over 1500 patients and over 3800 in- and outpatient therapies and visits. The effort of data entry is easily offset by the automatic generation of the necessary patient reports. The required supervision of the follow-up appointments is now also user-friendly and efficient.

Databases, Factual↗
PubMed2003

[Stunning effects in radioiodine therapy of thyroid carcinoma: existence, clinical effects and ways out].

In radioiodine therapy for malignant thyroid disease, the pre-therapeutically administered iodine-131-dose can reduce the potential of thyroid or thyroid carcinoma cells to absorb the following therapeutic iodine-131-dose, possibly leading to its failure. This so called stunning effect is controversially discussed in the scientific community. Here we summarize and evaluate publications with regard to the existence and the effects of stunning as well as possible countermeasures.

Humans↗
PubMed2002

The use of [18 F]fluorodeoxyglucose positron emission tomography to differentiate between synovitis, loosening and infection of hip and knee prostheses.

Pain is a common unspecific symptom in orthopaedic prosthetics. The accurate differentiation between synovitis, loosening or infection is often difficult with conventional X-rays, arthrography or bone scintigraphy. Because of the high glucose uptake of inflammatory cells, [18F]fluorodeoxyglucose (18F-FDG) is an appropriate tracer for the evaluation of suspected inflammation or infection. In this preliminary study we describe 18F-FDG PET findings in patients referred for evaluation of painful hip or knee prostheses. We studied 23 patients with 28 prostheses, 14 hip and 14 knee prostheses, who had a complete operative or clinical follow-up. 18F-FDG PET scans were obtained with an ECAT EXACT HR+ PET scanner. High glucose uptake in the bone prostheses interface was considered as positive for infection, an intermediate uptake as suspect for loosening, and uptake only in the synovia was considered as synovitis. The imaging results were compared with operative findings or clinical outcome. PET correctly identified three hip and one knee prostheses as infected, two hip and two knee prostheses as loosening, four hip and nine knee prostheses as synovitis, and two hip and one knee prostheses as unsuspected for loosening or infection. In three patients covered with an expander after explantation of an infected prosthesis PET revealed no further evidence of infection in concordance with the clinical follow-up. PET was false negative for loosening in one case. Our preliminary results suggest that FDG PET could be a useful tool for differentiating between infected and loose orthopaedic prostheses as well as for detecting only inflammatory tissue such as synovitis.

Adult↗
PubMed2000

[Myocardial perfusion at rest and during stress. MR signal characteristics of persistent and reversible myocardial ischemia].

AIM: Performance of combined rest/stress MR perfusion studies and the analysis of qualitative signal intensity parameters in comparison with 99mTc-SestaMIBI SPECT in patients with known coronary artery disease (CAD). METHODS: Sixteen patients with CAD underwent MR myocardial perfusion assessment at rest and after dipyridamole-induced hyperemia. Qualitative parameters (SI increase, SI upslope) of the SI time-curves were evaluated and characteristics of normal, reversible and persistent hypoperfused myocardium as assessed by 99mTc-SestaMIBI SPECT were compared. RESULTS: Compared with the rest values, normal myocardium showed a significant increase of the SI upslope during hyperemia (P < 0.001), whereas persistent (P = 0.07) and reversible (P = 0.15) hypo-perfusions showed only minor changes. SI increase over baseline also showed a significant increase only in normal myocardium (P < 0.001). At rest, reversible ischemic areas showed no significant differences from normal myocardium, whereas during hyperemia SI increase was significantly lower (P = 0.02). CONCLUSIONS: Qualitative SI parameters of a combined rest/stress MR myocardial perfusion study allow to differentiate normal from reversibly or persistently hypoperfused myocardium.

Adult↗
PubMed2000

Is a low-dose Tc-99m-MIBI protocol suitable for first-pass RNV?

Tc-99m-labelled radiopharmaceuticals, such as Tc-99m-sestamibi (Tc-99m-MIBI), offer the opportunity to measure myocardial perfusion and function with one injection only. The aim of this study was to evaluate whether first-pass (FP) radionuclide ventriculography (RNV) consecutively followed by myocardial perfusion single photon emission computed tomography (SPECT) may be performed according to a low-dose MIBI 1-day protocol using a multi-crystal gamma camera. Two hundred and seventy consecutive, predominantly obese [61% with a body mass index (BMI) of >25 kg x m(-2)] patients (169 male, 101 female), referred for myocardial perfusion SPECT with Tc-99m-MIBI [4 MBq x kg(-1) (>300 MBq) at stress; 9 MBq x kg(-1) (> 650 MBq) at rest], were studied with FP RNV prior to SPECT. Bicycle ergometry (29%), dobutamine (6%) or dipyridamole stress (65%) was performed. Adequate count (ct) statistics for FP RNV were defined as follows: (1) > 2000 cts within the background-corrected, end-diastolic (ED), left ventricular (LV) region of interest (ROI) of the representative cycle; and (2) >4 heart beats with > 1000 cts within the ED LV ROI (> 50% of maximal cts). A net mean dose of 318+/-64 MBq (4.3+/-1.1 MBq x kg(-1)) was injected during stress and 674+/-55 MBq (9.1+/-1.7 MBq x kg(-1)) during rest. There was no statistical difference among the three stress modalities concerning the net dose. Two hundred and fifty-six out of 270 (95%) stress and a basis for reliable all 270 (100%) rest FP RNV studies showed adequate count statistics as functional analysis. The 14 patients with insufficient count statistics were all obese and had received less than the planned dose. For the vast majority of patients, even a low-dose 1-day protocol with Tc-99m-MIBI is suitable for the assessment of FP RNV prior to SPECT. A minimum of 300 MBq and 4 MBq x (kg body weight)(-1) should be administered in order to obtain technically adequate results even in obese patients.

Coronary Disease↗
PubMed2000

Influence of thyroid-stimulating hormone levels on uptake of FDG in recurrent and metastatic differentiated thyroid carcinoma.

UNLABELLED: The objective of this prospective study was to determine the extent to which the levels of thyroid-stimulating hormone (TSH) influence the uptake of FDG by thyroid carcinoma tumors METHODS: Ten patients with follicular (n = 7) or papillary (n = 3) thyroid carcinoma underwent FDG PET during TSH suppression (<0.05 microU/mL) and TSH stimulation (>22 microU/mL) within an average interval of 42 d (range, 28-73 d). The findings were evaluated by visual criteria. In addition, a tumor-to-background ratio (TBR) was determined for 17 lesions that were visualized. RESULTS: In 15 of 17 lesions with positive FDG uptake, TSH stimulation was associated with an increase in the TBR from 3.85 +/- 2.53 (mean +/- SD) to 5.84 +/- 4.84, corresponding to an average increase of 63.1% (P < 0.001). Determination of absolute counting rates indicated that this increase was the result of a decrease in FDG metabolism in the background together with an increase in the tumor tissue. No relationship was found between the presence or absence of iodine storage capacity (5 versus 12/17 lesions) and increase in FDG accumulation. Seven of 10 patients had additional iodine-positive metastases that showed no accumulation of FDG. CONCLUSION: Most locally recurrent and metastatic follicular and papillary thyroid carcinomas exhibited a significant increase in FDG uptake on TSH stimulation. In 3 of 10 patients, TSH stimulation resulted in either detection of new lesions or classification of the FDG uptake pattern as typical for malignancy. These findings suggest that FDG uptake in recurrent and metastatic thyroid carcinoma depends on the TSH level. Therefore, we recommend that PET examinations be performed in patients with thyroid carcinoma under TSH stimulation and follow-up examinations be performed under identical TSH conditions to prevent erroneous interpretation.

Adenocarcinoma, Follicular↗
PubMed1999

Evaluation of the first automated thyroglobulin assay.

The aim of this study was to investigate technical and analytical performance of the first automated thyroglobulin (Tg) assay (DPC-Immulite; Diagnostic Products Corporation, Los Angeles, USA). In imprecision studies using several human serum pools ranging from 21 to 58 replicates, a coefficient of variation of 9.0% was obtained at a mean Tg concentration of 0.84 ng/ml and of 6.1% at a Tg concentration of 62.1 ng/ml. In a method comparison with a non-automated assay (BRAHMS LUMItest Tg, BRAHMS, Berlin, Germany) using 383 sera of 303 patients with thyroid carcinoma, regression analysis according to Passing and Bablock yielded in the following equation: Immulite Tg = 1.6 x BRAHMS Tg-0.1 ng/ml (Pearson's r = 0.979). Sera obtained from 59 patients with thyroid carcinoma enabled comparative follow-up studies; in all cases qualitative agreement was found with regard to increase or decrease of serum Tg; in eight cases, however, Tg was detected with the Immulite assay but not with the BRAHMS assay. Further follow-up proved the presence of thyroid tissue in these patients. From these and further methodological data (dilution linearity, interference studies, carry-over study, high-dose hook properties, and short report time) it is concluded that the DPC-Immulite Tg assay meets the requirements of routine diagnostic use.

Automation↗
PubMed1997

Functional EEG mapping and SPECT in detoxified male alcoholics.

Fifteen alcoholics diagnosed according to DSM-III-R, who were detoxified for at least 2 weeks and showed no clinical withdrawal signs, were investigated with 16 channel EEG mapping during resting, manumotor and music perception conditions, and were compared with 13 control persons. Single photon emission computed tomography (SPECT) using hexa-methyl-propilene-amine-oxime (HMPAO) labeled with 99m-technetium (99mTc) as tracer was performed separately (in patients only) and submitted to semiquantitative region of interest (ROI) analysis in 2 slices, 6 and 10 cm above canthomeatal line, respectively. Resting EEG showed increased power values in fast beta frequency band for the detoxified alcoholics. On cortical stimulation, patients showed signs of pathological EEG reactivity. Correlations of EEG parameters to cerebral blood flow (CBF) values (patients only) yielded coefficients around zero for all frequency bands (signs of uncoupling). All findings point to organic brain dysfunctions in these patients which extend beyond the period of withdrawal.

Adult↗
PubMed1996

[201Tl myocardial SPECT. First experiences with a simultaneous transmission-emission acquisition protocol for patient-specific attenuated correction].

AIM: In this study our first clinical experiences with simultaneous transmission and emission acquisition in 201 TI myocardial SPECT (T/E-SPECT) are discussed. METHODS: The non-uniform attenuation (AK) was carried out with a triple-head camera (PRISM 3000, Picker Inc.) correction equipped with fanbeam collimators. A line source of 750 MBq 99mTc was used to construct the transmission profile. Prior to investigation patients got 80-120 MBq 201TI-chloride intravenously injected. RESULTS: The study comprises the evaluation of 40 patients, derived from the clinical routine. The investigation followed an usual one day protocol. Our results using T/E-SPECT reveal an almost equilibrated activity distribution between anterior and posterior myocardial wall. CONCLUSION: For this reason it is to be expected that T/E-SPECT provides more reliable information about the posterior myocardial wall, than the usual SPECT technique without attenuation correction.

Gamma Cameras↗
PubMed1993

Functional results of radioiodine therapy with a 300-Gy absorbed dose in Graves' disease.

The aim of this study was to assess the results of high-dose radioiodine therapy given to 43 patients with recurrent hyperthyroidism due to Graves' disease between 1986 and 1992. We chose an intrathyroidal absorbed dose of 300 Gy and determined the applied activity individually, which ranged from 240 to 3120 MBq with a median of 752 MBq. Hyperthyroidism was eliminated in 86% of cases after 3 months and in 100% after 12 months. No patient required a second radioiodine treatment. The incidence of hypothyroidism was 63% after 3 months and 93% after 18 months. Neither the pretherapeutic thyroid-stimulating immunoglobulin level nor the degree of co-existing endocrine ophthalmopathy was correlated with the time at which hypothyroidism developed. Patients with previous radioiodine therapy developed hypothyroidism earlier than patients with previous thyroid surgery. The results show that ablative radioiodine therapy with a 300-Gy absorbed dose is a very effective treatment of hyperthyroidism in Graves' disease, but it should be restricted to patients with recurrent hyperthyroidism combined with severe co-existing disorders or episodes of unfavourable reactions to antithyroid drugs.

Female↗
PubMed1990

67Ga-scintigraphy for evaluation of AIDS-related intestinal infections.

This study was designed to evaluate the role of 67Ga-scintigraphy in AIDS-related intestinal infections. Seventeen out of twenty-five HIV-positive patients (68%) primarily investigated with 67Ga-scans to screen for opportunistic pneumonia presented pathologic abdominal 67Ga-uptake which was, in most cases, due to proven opportunistic intestinal infection (cytomegalovirus, atypical mycobacteria, cryptosporidiosis etc.). The correlation of abdominal with pulmonary findings has shown that AIDS-related intestinal infections and opportunistic pneumonia may occur concomitantly in the majority cases (11/17). In 6/17 patients positive abdominal findings were observed without opportunistic pneumonia at the same time. Gallium imaging of the abdomen has shown to identify successfully the most common extrapulmonary sites of HIV-related infections. Thus, abdominal imaging or whole body scintigraphy should be a mandatory part of each 67Ga-scan in patients with HIV infection, even if it was primarily performed to screen for opportunistic pneumonia only. Knowledge of multilocular opportunistic infections, usually caused by different pathogens, is clinically important for further diagnostic and therapeutic management.

AIDS-Related Complex↗
PubMed1990

TcTU before and after exogeneous TSH suppression in diagnosing thyroid autonomy.

In 104 euthyroid patients with goiter and suspected thyroid autonomy two thyroid scintiscans with quantification of the TcTU were performed before (TcTUo) and after exogeneous TSH suppression (TcTUs). In 15 patients with subnormal TSH before suppression the TcTUs revealed no difference to the TcTUo. In contrast to the TcTUo, in euthyroid patients the TcTUs is not relevantly influenced by individual iodine supply. In euthyroid goitreous patients with normal TSH a TcTUo less than 2.0% resulted in a TcTUs less than 1.1% in all 22 cases and, therefore, in these patients a scintiscan after TSH suppression is not necessary, because no relevant mass of functional autonomous tissue can be expected. In all other patients with normal TSH only the TcTUs is relevant for identification of thyroid autonomy. Autonomy with a TcTUs greater than 1.5% and, consequently, with a suspected higher risk of hyperthyroidism after iodine contamination was found in 19% (17/89) of the goitreous patients with normal TSH.

Euthyroid Sick Syndromes↗
PubMed1990

[Global 99mTc uptake in the differential diagnosis of a normal thyroid,goiter with euthyroidism and thyroid autonomy in an area of iodine deficiency].

Global TcTU was determined in 568 patients without any specific thyroid drug intake--54 with normal thyroid, 274 with goitre and euthyroidism and 240 with thyroid autonomy. 57 patients with autonomy and overt hyperthyroidism were the only group with TcTU values significantly higher than normals. Common to all groups was a large scatter of the TcTU values. In 332, the effects of individual iodine supply were studied by measuring the iodine concentration in spot urine samples. There was a significant inverse correlation between the TcTU values and the urinary iodine excretion in the groups of normal thyroids and of goitres with euthyroidism. In the group with autonomy an effect of iodine supply could only be seen in cases of greatly increased urinary iodine excretion, resulting in very low TcTU values. Out of 20 patients with autonomy and iodine contamination, only 4 showed overt hyperthyroidism. The large scatter of TcTU values in all groups may be explained by the persistent iodine deficiency as well as by the frequent exposure to unknown amounts of iodine in patients with thyroid disease. Therefore, the spontaneous TcTU alone cannot identify a small group of patients with autonomy and high risk of iodine-induced hyperthyroidism, from a very large group of patients with goitre.

Adult↗
PubMed1989

[Echocardiography with angiotensin administration in the diagnosis of adriamycin-induced cardiomyopathy].

Noninvasive assessment of early cardiotoxicity of doxorubicin is still a problem of clinical concern. We studied whether echocardiography during afterload stress induced by angiotensin II (1,000-3,000 ng/min) allows earlier detection of left ventricular impairment than echo at rest. We compared 30 normals (N) to 30 patients with carcinoma, who had received doxorubicin at a cumulative dose of at least 360 mg/sqm. At rest echocardiograms of patients were either normal (P1; n = 24) or abnormal (P2; n = 6; fractional shortening less than 28%, distance of mitral E-point to septum greater than 7 mm). Best parameter for separation of P1 vs N was the slope K of the regression line of the relation between endsystolic diameter and systolic blood pressure (cuff-method). 38% of P1 and 100% of P2 had K-values below the range of N (less than 4.7 mm Hg/mm). Four of five patients with reduced ejection fraction assessed by scintigraphy (less than 55%) after continued therapy with doxorubicin have had, in previous echocardiographic studies, normal resting parameters but abnormal K-values. We conclude that afterload-stress increases the sensitivity of echocardiography in detecting cardiotoxicity due to doxorubicin.

Adolescent↗
PubMed1988

[The place of 67Ga scintigraphy in the primary diagnosis and follow-up evaluation of opportunistic pneumonia in patients with AIDS].

Opportunistic pneumonias are a life-threatening complication in patients with AIDS. Early diagnosis and therapy is necessary to improve prognosis. This study was designed to assess the value of 67Ga scintigraphy in the primary detection and follow-up of these special pneumonias. 67Ga scintigraphy was performed in 40 patients: 10 normal controls and 30 HIV-positive patients with AIDS or AIDS-related complex (ARC). 67Ga scan results were compared with current chest radiographs and the results of pathogen detection. The evaluation of positive scans was based on a quantification of the pulmonary uptake, expressed as a pulmonary/soft-tissue uptake ratio. Only 8/30 patients had a normal scan, 22/30 showed diffuse (13/22) or focal (9/22) increases of pulmonary uptake. In 7/8 patients with normal scans the chest radiograph was negative as well. The one patient with negative scan but positive chest radiograph had pulmonary Kaposi's sarcoma. In 11/22 patients the 67Ga scan and chest radiograph were positive simultaneously. In the other 11/22 patients with positive scans chest radiographs were initially negative but showed pathology in 5 cases within 1-2 weeks. The reason for positive scans in most cases was an opportunistic lung infection; other forms of pneumonia were only observed in two cases. The defined uptake ratio demonstrated to be a highly sensitive parameter for monitoring pneumonia and the effects of therapy in follow-up studies. In conclusion, quantitative 67Ga scintigraphy proved to be a reliable and highly sensitive method for primary detection and follow-up of opportunistic pneumonias in patients with AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1988

[Results of radioiodine treatment of patients with immunogenic and non-immunogenic hyperthyroidism using different focal doses].

The aim of this study was to check the efficacy of radioiodine (131I) therapy (RIT) in a large number of patients (n = 506) suffering from immunogenic or non-immunogenic hyperthyroidism (Graves' disease, Plummer's disease). Since there is no causal cure for immunogenic hyperthyroidism RIT provides, like all other modalities, only a moderate rate of success which is clearly dose-related. Applying 60 Gy, normal thyroid function can be achieved in only 54% of the cases. A dose of 150 Gy succeeds in 86% of the cases. The solitary decompensated autonomous adenoma (DAA) can be eliminated surgically as well as by RIT with a high degree of success (95%). Contrary to surgery, RIT does not have any noticeable early or late morbidity. The high rate of success of RIT in patients with DAA could be confirmed in two groups with different follow-up periods (16 and 65 months). As expected, the rate of hypothyroidism increased from 11% in the early group to 23% in the late group. Multinodular autonomous adenomas can be eliminated successfully using RIT as well. The concept to apply a dose of 400 Gy to the total functional autonomous tissue as determined by ultrasound yields better results (95%) than 150 Gy to the whole thyroid gland as measured by ultrasound (88%). The rate of hypothyroidism as shown by these results (up to a maximum of 62% after RIT of Graves' disease using 150 Gy) is the lesser evil compared to remaining or recurrent hyperthyroidism since these patients can be treated with thyroid hormones without problems.

Adenoma↗
PubMed1987

Combined evaluation of first pass radionuclide angiography and equilibrium radionuclide ventriculography in the diagnosis of coronary artery disease. II. Results during exercise.

Results of 203 patients who underwent first pass radionuclide angiography (FP) and quantitative equilibrium radionuclide ventriculography (qERNV) were stored in a data base system and evaluated statistically. Eighty eight of these patients also underwent exercise equilibrium radionuclide ventriculography (E-qERNV). In patients with coronary artery disease (CAD) without previous myocardial infarction (MI), evaluation of global and regional ejection fraction (gEF, rEF) at rest revealed a poor sensitivity of 64%, the specificity was about 71% (qERNV). FP at rest revealed similar values of sensitivity (69%) and specificity (83%). Additional assessment of stress induced changes of gEF, significantly (P less than 0.05) improved sensitivity of qERNV in CAD patients without a history of previous MI to 84% (specificity 86%). In patients with one previous MI, however, similar values of sensitivity were found (R-FP: 87%, R-qERNV: 84%, E-qERNV: 93%). In patients with several MI's, sensitivity was above 90% at rest and during exercise (R-FP: 96%, R-qERNV: 93%, E-qERNV: 100%).

Coronary Disease↗