Biomedical subjects

R Piepenburg

Publications and source records attributed to R Piepenburg.

11 recordsLinked to original sources

PubMed1995

Technetium-99m mercaptoacetyltriglycine clearance: reference values for infants and children.

Six hundred and thirty-nine clearance studies performed in children aged 7 days to 19 years utilizing technetium-99m mercaptoacetyltriglycine (MAG 3) were retrospectively analysed. Standardized conditions for the investigation included: parenteral hydration (60 ml/hxm2 body surface) in addition to normal oral fluid intake, weight-related dose of 99mTc-MAG 3 (1 MBq/kg body weight, minimum 15 MBq) and calculation of clearance according to Bubeck et al. Of the 513 children, 169 included in this analysis could be classified as "normal" with regard to their renal function. Normal kidney function was judged by the following criteria: normal GFR for age, normal tubular function (absence of proteinuria and glucosuria), normal renal parenchyma (on ultrasonography, MAG 3 scan and intravenous pyelography), absence of significant obstruction and gross reflux (>grade I), no single kidney and no difference in split renal function >20%. Results showed increasing MAG 3 clearance values for infants during the first months of life, reaching the normal range for older children and adults between 7 and 12 months.

Adolescent↗

PubMed1995

[CT compared with SPECT in chronic recurrent pulmonary embolism: hyperdensities as signs of pulmonary artery hyperperfusion?].

UNLABELLED: Purpose of this study was to assess the aetiology of inhomogeneous lung parenchymal attenuation in patients with chronic pulmonary thromboembolism, presenting as sharply demarcated areas of increased and decreased density on computed tomography. MATERIAL AND METHODS: In 52 patients with chronic pulmonary thromboembolism, computed tomography (CT) was compared with perfusion scintigraphy (including SPECT) and agreement was assessed: "good" (all hyperdense CT segments are perfused on scan), "moderate" or "poor" (one or two resp. three or more hyperdense CT segments are not perfused). RESULTS: 44 of the 52 patients showed an inhomogeneous pulmonary attenuation on CT. Correlation of hyperdense areas with perfused lung parenchyma was graded as "good" in 26 cases, "moderate" in 14 and "poor" in 4 cases. In 40 of these 44 patients, scintigraphy revealed additional perfusion defects in homogeneously lucent areas on CT. In 6 of 8 patients with entirely homogeneous lung density on CT, SPECT revealed perfusion defects. CONCLUSION: In patients with chronic pulmonary thromboembolism, increased lung density on CT is caused by hyperperfused lung parenchyma distally to patent pulmonary arteries. SPECT proves to be more sensitive in diagnosing perfusion inhomogeneities.

Adult↗

PubMed1994

Pulmonary arteries and lung parenchyma in chronic pulmonary embolism: preoperative and postoperative CT findings.

PURPOSE: To evaluate the role of computed tomography (CT) in diagnosis of chronic thromboembolic pulmonary hypertension, assessment of surgical operability, and follow-up after surgery. MATERIALS AND METHODS: Seventy-five patients with chronic thromboembolism were examined with CT; 63 underwent thromboendarterectomy, and postoperative CT scans were acquired in 23. CT scans were analyzed for vascular and parenchymal changes, and findings were compared with those on lung scintigrams and with surgical results. RESULTS: CT findings allowed confirmation of the diagnosis of chronic thromboembolism and ensured technical operability (sensitivity, 77%; specificity, 100%; overall accuracy, 80%) by means of direct visualization of thrombi in central pulmonary arteries in 53 patients. CONCLUSION: CT enables demonstration of pulmonary thromboembolism with criteria pertaining to pulmonary arteries and to lung parenchyma and enables assessment of technical operatibility and confirmation of surgical success.

Adult↗

PubMed1993

[99mTc-MAG3-kidney function scintigraphy without and with captopril in the diagnosis of renovascular hypertension].

In this study, the diagnostic value of renal function scintigraphy performed both without and with ACE inhibition has been evaluated using the new radiopharmaceutical 99mTc-MAG3. In cases of decompensated renal artery stenoses, the typical scan finding with this tubular excreted agent was shown to be a distinct parenchymal nuclide retention in combination with a delayed appearance of the radiotracer in the pelvic system. Using this criterion in 43 patients with suspected renovascular hypertension, sensitivity and specificity were 89 and 88%, respectively. Bilateral positive findings were non-specific; excluding them from the study, specificity increased to 100%. In renal insufficiency, captopril scans seem to be of reduced diagnostic value. Summarising our experiences, renal function scintigraphy using 99mTc-MAG3 without and with captopril was proved to be a reliable non-invasive method to detect or exclude haemodynamically relevant renal artery stenosis.

Captopril↗

PubMed1993

[Evaluation criteria for captopril-kidney function scintigraphy using 99mTc-MAG3].

Renal function scintigraphy under ACE inhibition has gained an important role in the diagnosis of renovascular hypertension. Using the radiopharmaceutical 99mTc-MAG3, 54 kidneys with angiographically verified renal artery status were evaluated with respect to the following scintigraphic parameters: intraparenchymal tracer transport, urine drainage, kidney size, and functional side-to-side ratio. In cases of decompensated renal artery stenosis, the typical scan finding using MAG3 was shown to be a distinct parenchymal nuclide retention in combination with a delayed appearance of the radiotracer in the pelvic system. In our patients, the visual impression of the renal sequential scans was superior to quantitative evaluation methods. Using these criteria in 43 patients with suspected renovascular hypertension, sensitivity and specificity were 89% and 88%, respectively. Bilateral positive findings were nonspecific; when excluding them from the study, specificity increased to 100%.

Adult↗

PubMed1993

[Quantitative nuclear medicine kidney diagnosis with kidney tubule traversing radioisotopes].

In modern nuclear medicine, renal function scintigraphy has been improved and its range of applications extended by the development of new radiopharmaceuticals (iodine-123-hippuran, technetium-99m-MAG3) combining the properties of short half-life, favourable radiation energy and high renal clearance. Three significant advantages recommend the use of scintigraphic methods: 1. Being non-invasive and non-nephrotoxic, the examinations do not affect the patient. The radiation exposure the patient is subjected to is about the same as with a comparable X-ray investigation or, with respect to the reproductive glands, even lower. Allergic reactions do not occur. 2. In contrast to the situation with other imaging methods, the functional defect itself (and not only secondary changes in the morphology) can mostly be detected. Not only diffuse alterations, but also defined functional lesions of a small part of a kidney, can be diagnosed. 3. Various renal parameters can be calculated more accurately than with any other routine clinical method. The radioisotopic methods discussed yield reliable results with excellent reproducibility concerning glomerular filtration rate, effective renal plasma flow, side-to-side functional ratio, renal perfusion, and urine drainage. Most of these parameters can be obtained by means of a single investigation. These radioisotopic methods make it possible to detect or exclude a wide range of functional lesions of the kidneys and the urinary tract, which are often due to non-specific symptoms. In addition, they allow answers to highly specific clinical and scientific questions in nephrology and urology.

Humans↗

PubMed1993

[Nuclear medicine diagnosis and therapy in urology. Diagnosis of bone metastases].

Bone scintigraphy with 99mtechnetium-labelled polyphosphonates is the most sensitive test for early detection of skeletal metastases. Bone metastases are a major factor in prognosis and have a considerable influence on the therapy selected. In patients with prostate cancer, we recommend routine bone scintigraphy in the initial staging. Follow-up bone scans are indicated whenever a patient develops pain, an elevated level of acid phosphatase, or a rise in prostate specific antigen (PSA). Routine bone scans are not necessary for the initial staging of patients with renal cell carcinomas, bladder carcinomas and testicular tumours. Scans should be routinely performed, however, in patients with bone pain or elevated alkaline phosphatase or when radiological findings are inconclusive. Bone scanning is necessary in patients with neuroblastoma, both for the initial diagnosis and during follow-up in all cases with known skeletal involvement. In addition, bone scintigraphy should be performed in cases of recurrent or suspected malignant phaeochromocytoma as a complement to scintigraphy with iodine-123- or iodine-131-MIBG, respectively. Even though skeletal scintigraphy is a very sensitive test, it lacks specificity. This can be compensated, however, by careful interpretation of the scan in the light of the patient's history and the clinical findings. As a positive side-effect, bone scanning--especially in the form of multiphase scintigraphy--may detect renal abnormalities, concurrent diseases or complications in the upper or lower urinary tract. If scintigraphic findings are doubtful, plain film radiographs are required or, in selected cases, bone biopsy must be performed.

Adult↗

PubMed1992

A new principle to normalize plasma concentrations allowing single-sample clearance determinations in both children and adults.

A sufficiently accurate quantification of renal function requiring only one plasma sample without an additional gamma-camera study has, until now, only been possible in adults. A new principle will be presented here allowing the universal application of known algorithms, regardless of the clearance substance used, by normalizing the plasma concentrations with respect to the individual body dimensions of the patients--for infants as well as for adults. In this respect, algorithms are developed for clearance determinations using technetium-99m mercaptoacetyltriglycine (99mTc-MAG3), which are based on steady-state studies as the reference. They allow the calculation of quantitative clearance values in infants, requiring only one blood sampling at any time between the 25th and the 40th min postinjection. The comparison with a combined camera/two-plasma-sample technique performed in 46 children aged between 9 days and 14 years (mean 6.05 years) resulted in a standard error of 8.5% from the line of identity (r = 0.94). Moreover, this procedure also increases the accuracy of results in adults.

Adolescent↗

PubMed1992

[Importance of whole body skeletal scintigraphy within the scope of staging of neoplasms in the ENT area].

Concerning malignant tumours of the oral cavity, pharynx and larynx, bone metastases are in general rarely seen. For the specification to which patients the whole body bone scintigraphy as detection method should be applied, the findings of 370 patients were analysed retrospectively. In respect of primary staging, bone metastases could be found by scintigraphy in only 1.4% of the patients. On the other hand, there was a detection rate of 12% during the further course of the disease, especially in case of clinical symptoms pointing at spreading metastases or in tumour recurrences. Nevertheless, positive scan findings which were not due to metastases could be found in both groups with equal frequency (12 and 13%, respectively). Therefore the routine performance of whole body bone scintigraphy as a screening method does not seem to be useful in the primary staging of cancer of the mouth, pharynx and larynx. Contrary to this, in the follow-up of these tumours bone scanning proves to be a valuable and sensitive method for detecting skeletal metastases.

Bone Neoplasms↗

PubMed1992

[The clinical relevance of anti-CEA immunoscintigraphy with the 99mTc-labelled monoclonal antibody BW 431/26. A critical assessment after 119 studies].

The results of 119 radioimmunoscintigraphies (RIS) in 113 patients with the 99mTc-labeled monoclonal anti-CEA-antibody BW 431/26 (Behring) have been analysed. The aim of our study was the estimation of the method's sensitivity and specificity under different aspects to find out for which indications and questions the 99mTc-RIS is useful. Colorectal primary tumours in 19 patients were scintigraphically detected with a sensitivity of 83% and a specificity of 100%; 3 out of 7 other tumour sites were localised correctly. 55 patients were examined during the follow-up of colorectal cancer. There were 17 out of 22 true positive findings of local recurrences (sensitivity 77%, specificity 88%). Liver metastases were imaged as hot lesions with only 41% sensitivity and 86% specificity. The detection of extrahepatic tumour sites is difficult because of the persistently high blood-pool activity of the monoclonal antibody and, in the pelvic area, the unspecific bowel activity. Skeletal metastases were recognised in 7 out of 9 cases. In 14 patients with other non-colorectal carcinomas, RIS was successful in single cases. It is not helpful, however, when searching for tumours of unknown origin or for the screening of patients with elevated CEA levels without tumour history. The high technical, methodological and time effort required by RIS is justified in the follow-up of cancer patients when conventional diagnostic procedures are inconclusive or the status of morphological findings remains unclear. The use of RIS as an unspecific screening tool in tumour diagnosis must be rejected because of the not completely explored risks of the examination. Repeated applications of monoclonal antibodies require controls of the patients' HAMA titers before performing RIS.

Adult↗

PubMed1992

[Combined bilateral idiopathic necrosis of the humerus and femur heads: bone scintigraphy, x-ray, CT and MRT findings].

Aseptic bone necrosis in adults is usually caused by circulation defects or metabolic diseases but may also occur without any obvious reason. In these "idiopathic" cases, alcoholism seems to play a prominent role. In addition to the frequently affected femoral heads other bones may be involved. Here a remarkable pattern of localizations is reported: the bilateral idiopathic necroses of the heads of both humerus and femur. Untreated aseptic bone necroses close to a joint commonly leads to severe secondary arthrosis and destruction of the joint within a short time. Therefore, only a diagnosis in an early stage of the disease offers the chance of a successful joint-preserving therapy. In cases of clinically suspected aseptic bone necrosis but still negative or doubtful X-ray findings, bone scans or MRI are reliable methods of verifying the diagnosis.

Adult↗