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Biomedical subjects

K Schelstraete

Publications and source records attributed to K Schelstraete.

At least 19 recordsLinked to original sources
PubMed1993

A comparison of iodine-123 meta-iodobenzylguanidine scintigraphy and single bone marrow aspiration biopsy in the diagnosis and follow-up of 26 children with neuroblastoma.

In staging neuroblastomas, the demonstration of tumoural invasion of the bone marrow is an important criterion with regard to the therapeutic prospects and the prognosis. Iliac crest aspiration sampling has been used routinely for the detection of bone marrow metastases in neuroblastoma. However, due to the limited character of the sampling, it sometimes leads to false-negative results. Another procedure which is used to determine the extent of neuroblastoma is metaiodobenzylguanidine (mIBG) scintigraphy. In order to establish the respective merits of both diagnostic techniques retrospectively, 148 iodine-123 mIBG scans of 26 children with neuroblastoma have been re-evaluated and compared with the results of routine bone marrow samples obtained within a 4-week period before or after scanning. Three types of mIBG uptake in the bone/bone marrow could be differentiated: (1) no visualization of the skeleton; (2) diffuse uptake in the skeleton with or without focally increased uptake, which indicates massive, diffuse bone marrow invasion by the tumour; and (3) focal tracer accumulation in one or several bones. No tracer uptake was observed in the skeleton in 91 scans. In 89 of the 91 the bone marrow biopsy was negative. Twenty-four scans showed diffuse skeletal uptake with or without foci. The bone marrow biopsies were negative for eight of those 24 scans. Hyperactive foci in one or more bones without diffuse tracer accumulation in the skeleton were detected in 33 scans. In only 7 of these 33 scans did bone marrow biopsy specimens from the iliac MDP crest contain neuroblastoma cells.(ABSTRACT TRUNCATED AT 250 WORDS)

3-Iodobenzylguanidine↗
PubMed1993

Visualization of a parathyroid adenoma with Tc-99m MIBI in a case with iodine saturation and impaired thallium uptake.

A case of a parathyroid adenoma is presented in which the conventional Tl-201 minus Tc-99m subtraction technique failed to localize the adenoma because of prior iodide administration and a low Tl-201 uptake. Ultrasonography and CT could not provide useful data either. However, a Tc-99m methoxylisobutylisonitrile (MIBI) scintigram clearly delineated the adenoma and the thyroid tissue.

Adenoma↗
PubMed1992

Measurement of short-term 11C-thymidine activity in human head and neck tumours using positron emission tomography (PET).

Tumour uptake of 11C-thymidine labeled in the methyl position was assessed after intravenous injection in 13 patients with head and neck tumours. This activity was compared to other tracers such as C15O, 13NH3 and C15O2. In every single case a 'positive' tumour image after injection of 11C-thymidine was obtained. Time-activity curves showed the initial activity to be followed by a rapid decrease over the first 10-15 min with an apparent plateau thereafter. A similar level of uptake was found in normal salivary gland regions and myocardium, while higher activities were noted in liver and kidney parenchyma. It is suggested that both blood flow and cellular metabolism can influence 11C-thymidine imaging in this class of human tumours.

Adult↗
PubMed1992

Technetium-99m-diphosphonate, gallium-67 and labeled leukocyte scanning techniques in tibial nonunion.

On the technetium-99m bone scan the vast majority of nonunion cases show an intense tracer uptake at the fracture site, as do fractures undergoing normal healing. Therefore static bone scintigraphy usually does not contribute to the diagnosis of nonunion. One of the main causes of delayed fracture healing is infection. Increased blood flow and blood pool as demonstrated during the first and second phases of a 3-phase bone scan are consistent with an inflammatory reaction but are not pathognomonic for infection. A gallium-67 scan is indicative of infection if Ga-67 uptake exceeds Tc-99m uptake on the bone scan. The most specific tracers for infection however are leukocytes labeled with indium-111 or technetium-99m.

Citrates↗
PubMed1991

Intestinal mucosal permeability in inflammatory rheumatic diseases. I. Role of antiinflammatory drugs.

Using the 51Cr-EDTA resorption test, gut permeability was measured in 129 patients with inflammatory joint diseases and in 97 control patients (42 patients with no inflammatory rheumatic disorders taking antiinflammatory medication and 55 healthy controls). Thirty-two patients (30 arthritis and 2 control patients) taking nonsteroidal antiinflammatory drugs (NSAID) as well as corticosteroids were excluded from statistical analysis. The intake of NSAID significantly increased gut permeability in controls but not in the arthritis groups. The same applied to corticosteroid intake. This could be due to the restricted number of arthritis patients who had never taken antiinflammatory drugs or to a disease related increased permeability. There was no statistically significant difference in altered gut permeability between patients taking NSAID and patients taking corticosteroids. Our findings suggest that drug induced alteration of gut permeability may not only be accounted for by an inhibition of mucosal cyclooxygenase activity, but that other enzymatic pathways in the arachidonic cascade might be implicated.

Adrenal Cortex Hormones↗
PubMed1991

Intestinal mucosal permeability in inflammatory rheumatic diseases. II. Role of disease.

Gut permeability as measured by the 51Cr-EDTA resorption test was determined in 56 patients with rheumatoid arthritis (RA), 73 patients with spondyloarthropathies (SpA), 18 patients with inflammatory bowel disease (IBD) and 97 controls (42 patients with no inflammatory rheumatic diseases and 55 healthy controls). Gut permeability was found to be increased in the 3 patient groups, partially due to the intake of antiinflammatory drugs. When only patients not taking these drugs were considered, an increased gut permeability was found in patients with SpA and IBD. In patients with RA gut permeability could not be evaluated as they were all taking antiinflammatory medication. Ileocolonoscopy with biopsies of the gut was performed in 62 of the 73 patients with SpA and disclosed subclinical gut inflammation in 21. No difference in gut permeability was found between patients with or without gut inflammation. However, when the type of gut inflammation was considered, a significant increase of gut permeability was found in patients with chronic gut inflammation compared with patients presenting acute lesions. Our findings again suggest that the chronic gut inflammation seen in SpA is fundamentally different from acute gut inflammation and possibly related to the gut inflammation of IBD.

Adult↗
PubMed1990

Scintigraphic, spirometric, and roentgenologic effects of radiotherapy on normal lung tissue. Short-term observations in 14 consecutive patients with breast cancer.

The effects of radiotherapy on lung function, ventilation/perfusion scans, and chest radiography were studied prospectively in 15 patients who underwent either modified radical mastectomy or tumorectomy, followed by radiotherapy for breast cancer. In all patients, pulmonary function studies, chest x-ray films, and lung scintigraphic studies were performed prior to and at the end of radiotherapy as well as three months later. No consistent or significant alteration in either parameter was detected. No patient developed clinical symptoms suggestive of radiation-induced lung changes, although in one of them, major radiologic features were found that were consistent with radiation pneumonitis; those changes disappeared completely in the course of the subsequent months. It is concluded that the tangential beam technique for postoperative irradiation as used in these patients is largely safe as regards pulmonary function, perfusion, and ventilation.

Adult↗
PubMed1988

Cyclotron production of carrier-free 66Ga as a positron emitting label of albumin colloids for clinical use.

A method for producing carrier free 66Ga (T1/2:9.4 h; beta +) by 4He bombardment of natural copper targets is presented. 66Ga is formed by means of the 63Cu (4He, n) 66Ga reaction. Production yields are given in the 17.5 to 8 MeV 4He energy range. Chemical purification of 66Ga from the copper target is described. The only radionuclidic impurity found in the final product was 67Ga. Albumin colloids from commercially available kits designed for use with 99mTc could easily be labeled with 66Ga and employed for studies of the lymphatic system by positron emission tomography.

Animals↗
PubMed1988

Comparison of different volume markers in peritoneal dialysis.

Four peritoneal volume markers (carbon 14-labeled dextran, dextran blue, radioactive albumin, and hemoglobin) were compared. In six rabbits 14C-dextran was compared with dextran blue during a 4-hour "dwell" with a 4.25% dextrose solution. The recovery of 14C-dextran at the end of the dwell was 71% +/- 3% vs. 92% +/- 1% for dextran blue (P less than 0.001). In six other rabbits, radioactive albumin (RISA) was compared with dextran blue. The recovery of RISA was 78% +/- 4%, compared with 85% +/- 2% for dextran blue (P less than 0.05). The calculated peritoneal volumes, uncorrected for disappearance of the markers, were consistently higher than when correction was made. After correction, the calculated end volumes were similar to actually measured end volumes. In six patients with chronic ambulatory peritoneal dialysis, the intraperitoneal volume during a single dwell of 6 hours was estimated in paired observations with lactated Ringer's solution and 1.5% dextrose dialysate, using simultaneously autologous hemoglobin and RISA. In eight additional patients, a single dwell with 4.25% dextrose dialysate was studied. The recoveries of both markers were related to the osmotic strength of the dialysate. Recoveries were 66.7% +/- 2.3% and 69.6% +/- 0.9% in lactated Ringer's solution, and increased to 81% +/- 3% and 82% +/- 2% in 4.25% dextrose for hemoglobin and RISA, respectively. With each dialysate, after correction for disappearance of the marker, no differences in volume profiles or between calculated or measured end volumes could be found with either hemoglobin or RISA.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Clinical comparison of 11C-ACPC (aminocyclopentane carboxylic acid) and 13N-ammonia as tumour tracers.

Positron emission tomography is a potential method for exploring the biochemical behaviour of tumours. In 28 patients with known neoplastic lesions a comparison was made between two agents which are known to be accumulated in malignant tumours, viz. 13N-ammonia and 11C-aminocyclopentane carboxylic acid (ACPC). Absolute concentration of both agents in various tumoural tissues and normal organs was calculated. As a rule a parallelism was found between the two tracers as to their accumulation in a given tumour, although the concentration was often higher for ACPC. In normal tissues the ACPC accumulation was either lower or at most equal to NH3 levels. As tumour tracer ACPC is superior to NH3 because of its higher absolute accumulation in many neoplastic lesions and its lower uptake in various non-tumorous tissues. ACPC concentration in tumours seems to be largely independent of blood flow.

Abdominal Neoplasms↗
PubMed1986

Microscale synthesis of nitrogen-13-labeled cisplatin.

A microscale synthesis of [13N]cisplatin (cis-dichlorodiammineplatinum(II), cis-DDP) from cyclotron-produced [13N]ammonia is presented. Temperature, reaction time, ratios, and concentration of reactants have been optimized for each step of the synthesis. Purification is performed by ion exchange chromatography. Radiochemical purity and optimization processes are controlled by high performance liquid chromatography and high performance thin layer chromatography--22 mCi [13N]cisplatin in 10 ml of solution is produced. The entire procedure takes approximately 15 min and the specific activity is approximately 300 mCi/mumole at EOB.

Ammonia↗
PubMed1985

Kinetics of 13N-ammonia incorporation in human tumours.

After intravenous injection of 13N-labelled ammonia time-activity curves were obtained in a series of malignant neoplasms in man from serial cross-sectional scans through the tumour, using positron emission tomography. Low noise images with virtually no artefacts were obtained using a maximum likelihood reconstruction technique. Tracer concentration was expressed as a fraction of the injected dose ml-1 of tumour tissue. In a first group (eight observations) maximum activity [0.9 to 5.2 (mean: 3.3) X 10(-5) of administered dose ml-1 of tumour tissue] was attained approximately 1 to 3 min post injection. This peak was followed by a clearance phase with a half-time varying between 28.3 and 112 (mean: 73.1) min. In a second group (of six cases) after an initial rapid rise of the activity, no clearance was detectable during the time of observation, tracer concentration remaining in plateau or even continuing to rise slightly. Maximum activity in this group ranged from 1.1 to 5.3 (mean: 2.6) X 10(-5) of the administered dose ml-1 of tissue. So far no relation has been established between the height and/or shape of the 13NH3 time-activity curve and a particular tumour type.

Adult↗
PubMed1985

Demonstration of nodules in the normal thyroid by echography.

An ultrasound examination was performed of the normal thyroid in 300 patients (164 males and 136 females). Small echoic nodules were demonstrated in 19% of the patients and fluid-filled masses in 6%. Echoic nodules occurred frequently (greater than 40%) in the seventh decade. 71% of the nodules were situated in the right lobe.

Adolescent↗