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Biomedical subjects

M De Roo

Publications and source records attributed to M De Roo.

At least 19 recordsLinked to original sources
PubMed1998

Comparison of total and compartmental gastric emptying and antral motility between healthy men and women.

There is increasing evidence of gender-related differences in gastric emptying. The purpose of this study was first, to confirm the difference in gastric emptying for both solid and liquid test meals between healthy men and women, and secondly, to investigate the origin of this difference by studying regional gastric emptying and antral motility. A standard gastric emptying test with additional compartmental (proximal and distal) evaluation and dynamic imaging of the antrum was performed in 20 healthy women studied during the first 10 days of the menstrual cycle, and in 31 healthy age-matched men. In concordance with previous reports, women had a longer half-emptying time for solids as compared to men (86. 2+/-5.1 vs 52.2+/-2.9 min, P<0.05). In our observations this seemed to be related to a significantly prolonged lag phase and a significant decrease in terminal slope. Dynamical antral scintigraphy did not show a significant difference. The distribution of the test meal within the stomach (proximal vs distal) showed more early proximal retention in women as compared to men. The terminal slope of the distal stomach was significantly lower in women. We did not observe a significant difference in gastric emptying of the liquid test meal between men and women. Gastric emptying of solids is significantly slower in healthy women as compared to men. These findings emphasise the importance of using different normal values for clinical and research purposes in gastric emptying scintigraphy in men and women. The difference could not be explained by antral motility alone. Increased proximal retention and a lower terminal emptying rate in women are observations to be further investigated.

Adult↗
PubMed1998

Measurement of skeletal flow with positron emission tomography and 18F-fluoride in femoral head osteonecrosis.

Positron emission tomography (PET) with 18F-fluoride was utilized to determine the regional blood flow to the femoral head in early osteonecrosis. Five patients with a history of unilateral hip trauma and a normal contralateral side were selected. Skeletal flow and fluoride uptake in the abnormal and normal hips were compared directly, and the relation between bone blood flow and final outcome, i.e., surgical replacement or conservative treatment, was evaluated. In this pilot study, a flow ratio of at least 2 between the abnormal and normal femoral head was necessary to predict a successful outcome with a conservative regimen. A minimum flow of 0.04 ml/min/ml was measured in one patient whose affected femoral head healed conservatively. Our preliminary study indicates that this type of highly technical investigation appears feasible in clinical practice and permits prediction of the outcome depending upon regional skeletal flow measurements in vivo.

Adult↗
PubMed1998

Pulmonary tumor microembolism.

Pulmonary tumor embolism is an often missed antemortem diagnosis in patients with cancer and respiratory failure. Although rare, this complication is an important cause of additional morbidity. Referred for radionuclide pulmonary perfusion and ventilation scintigraphy, a typical pattern of multiple subsegmental peripheral defects on perfusion lung scanning without matching ventilation defects, suggesting a high probability of pulmonary thromboembolism, often leads to false conclusions. We present a case of bilateral multiple subsegmental mismatched defects in lung ventilation perfusion scintigraphy, where autopsy confirmed the diagnosis of pulmonary tumor embolism, secondary to an undifferentiated ductal type adenocarcinoma of the pancreas. Pulmonary tumor embolism is an entity to keep in mind in patients treated for carcinoma presenting with (sub) acute dyspnea.

Adenocarcinoma↗
PubMed1998

Three-phase bone scan and dynamic vascular scintigraphy in algoneurodystrophy of the upper extremity.

UNLABELLED: Algoneurodystrophy (AND) is a complex disorder with a wide spectrum of clinical presentations. Patients referred for a work-up of unilateral upper extremity AND were reviewed, and 50 patients were enrolled with sufficient documentation on history, causal event, clinical stage, and final outcome. There were 27 females, 23 males, mean age 44 years. The affected area was: shoulder 5, arm 3, elbow 3, wrist 26 and hand 13. Main precipitating events were fracture, contusion, or prior surgery. Three-phase bone scintigraphy was performed followed by a 2-phase vascular scintigraphy on another day. Typical periarticular uptake on the delayed bone scan was used to diagnose AND. Staging was done with the dynamic phase of the vascular scan. The clinicians diagnosed 30 patients positive for AND, 14 negative, and 6 equivocal. Bone scintigraphy yielded 25 positive, 20 negative, and 5 equivocal scans, i.e. sensitivity 73% and specificity 86%. Of the positive bone scans, 21 had all 3 phases positive, and 16 were concordant on vascular scintigraphy. The remaining 5 vascular scans classified 3 patients in transition (stage I-->II) and 2 in stage II. In other words, in 24% of patients vascular scintigraphy indicated restaging. CONCLUSION: dynamic bone scintigraphy is an accurate method to diagnose AND. Vascular scintigraphy changed AND stage in one quarter of the patients. Therefore, a combination of both studies is indicated in the work-up and treatment monitoring of AND.

Adult↗
PubMed1997

Sumatriptan, a selective 5-HT1 receptor agonist, induces a lag phase for gastric emptying of liquids in humans.

Sumatriptan, a 5-hydroxytryptamine1 (5-HT1) receptor agonist at enteric neuronal 5-HT receptors, causes a relaxation of the gastric fundus and inhibition of antral contractile activity. The present study examined the effect of sumatriptan on gastric emptying of solids and liquids in humans. In eight healthy subjects the gastric emptying rate for liquids and solids was measured using the carbon-labeled glycine and octanoic acid breath test after subcutaneous administration of placebo or sumatriptan. Sumatriptan increased the gastric half-emptying time of liquids (P < 0.0005) and induced a prolonged lag phase for liquids (P < 0.0005) in all subjects. Sumatriptan increased gastric half-emptying time (P < 0.005) and the lag phase of solids (P < 0.05) in all subjects. In two healthy subjects gastric emptying of liquids and solids after subcutaneous administration of sumatriptan was studied by radioscintigraphy. Radioscintigraphy confirmed the delayed emptying and the prolonged lag phases after sumatriptan. In conclusion, sumatriptan delays gastric emptying of solids and liquids in healthy subjects. Moreover, sumatriptan induces a lag phase for liquids. The mechanism by which sumatriptan alters gastric emptying remains to be studied.

Adult↗
PubMed1997

Normal brain perfusion pattern of technetium-99m-ethylcysteinate dimer in children.

UNLABELLED: The purpose of this study was to assess the normal perfusion pattern of the pediatric brain with 99mTc-ethylcysteinate dimer (99mTc-ECD). METHODS: Tomographic imaging was performed with a dedicated system with high sensitivity and resolution. Sixteen children, referred for brain imaging in the workup of seizure disorder, were included since they turned out negative after a 1-yr follow-up. A standardized brain presentation was obtained after reslicing and reorienting of the three-dimensional volumetric dataset. RESULTS: Quantitative analysis did not reveal significant left-right uptake differences per patient. Three age clusters were investigated that showed differences in regional uptake, mainly a relatively increased uptake in basal ganglia, visual and motor cortex. An uptake ratio or perfusion index was calculated after normalization. Normal limits were established for the children in the three groups. CONCLUSION: Technetium-99m-ECD is a safe agent for children and should be the radiopharmaceutical of choice for brain perfusion studies because of favorable radiation dosimetry and stability. The age dependence of perfusion necessitates a database comparison before concluding that the observed perfusion pattern is normal.

Adolescent↗
PubMed1997

Fluoride kinetics of the axial skeleton measured in vivo with fluorine-18-fluoride PET.

UNLABELLED: The aim of this study was to quantify regional bone blood flow and influx rate with PET and [18F]fluoride in patients with metabolic bone disorders. METHODS: Dynamic imaging of the spine or pelvis was performed after administration of 300-370 MBq of 18F-. Plasma clearance of 18F- was determined in blood sampled from the radial artery. A three-compartment model was used to estimate the regional flow and fluoride influx rate. RESULTS: In this preliminary study, fluoride flux (in micromol/min/liter) could be measured regionally. The flux was consistent with the pathophysiology of the studied metabolic disorders and allowed the various disease states to be distinguished. Bone blood flow and influx rate were low in osteoporosis (in the "normal-appearing" bone) and high in Paget's disease. CONCLUSION: With PET and [18F]fluoride, local bone blood flow and fluoride influx rate can be quantified in patients in vivo. Metabolically active zones have an increased influx rate and an accordingly increased flow. In principle, this technique permits classification of bone disorders and has potential for the monitoring of therapy response in metabolic bone disease.

Adult↗
PubMed1996

Nuclear medicine and cardiology: the position of the Union of European Medical Specialists/Section of Nuclear Medicine.

This paper summarizes a communication presented at the Second International Conference of Nuclear Cardiology, held in Cannes on 23-26 April 1995. The general evolution of nuclear medicine in Europe is examined within the context of European Union Directives, and the role of the Union of European Medical Specialists/Section of Nuclear Medicine is discussed. Thereafter consideration is given to the technical aspects of cardiovascular nuclear medicine procedures, and the situation with respect to such procedures in European countries is examined. In most European countries, nuclear medicine is a recognized specialty, while "nuclear cardiology" does not exist in its own right. In general, only nuclear medicine specialists have the responsibility for radionuclide studies, and most cardiovascular studies are performed under the direct responsibility of a licensed nuclear medicine specialist.

Cardiology↗
PubMed1995

Regional myocardial blood flow, glucose utilization and contractile function before and after revascularization and ultrastructural findings in patients with chronic coronary artery disease.

In patients with chronic coronary artery disease, follow-up measurements of myocardial blood flow, metabolism and function were correlated with histology. In 41 patients with chronic coronary artery disease and a severely stenosed left anterior descending coronary artery, a positron emission tomographic (PET) flow/metabolism study and nuclear angiography were performed immediately before and 3 months after bypass surgery. Biopsies were taken from the left ventricular anterior wall at the time of surgery. Control biopsies were taken from donor hearts for cardiac transplantation and from hearts of patients with a defect of the atrial septum. A significant improvement of flow (P<0.01) and regional contractile function (P<0.01) was observed in the mismatch group. Glucose utilization was significantly lower (P<0.001) as compared to preoperative values. The group with preserved flow and the PET match group revealed no significant changes in flow, metabolism or function. Control biopsies revealed significantly less myolytic cells as compared to biopsies taken from both match and mismatch groups (P<0.01) and less fibrosis as compared to biopsies taken from the match group (P<0.01). Postoperatively, linear relationships were found between flow and both % fibrosis (r = 0.71, P<0.001) and regional anterior ejection fraction (r = 0.7, P<0.001). Only mismatch areas revealed significant recovery of both flow and function after revascularization with a disappearance of enhanced glucose uptake. The better linear correlation between flow and % fibrosis after surgery as compared to preoperatively was probably due to improvement of flow values in the mismatch group.

Coronary Artery Bypass↗
PubMed1995

Metabolism of nitrogen-13 labelled ammonia in different conditions in dogs, human volunteers and transplant patients.

To investigate the rate of metabolism of nitrogen-13 labelled ammonia (13NH3) in different conditions, we have determined the relative amount of unchanged 13NH3 in the blood of dogs, volunteers and transplant patients at different times following injection. In dogs, the determinations were made under basal conditions, during adenosine administration and after coronary occlusion. The results show that adenosine administration increases the metabolic rate whereas coronary occlusion does not affect 13NH3 metabolism. For both human volunteers and transplant patients the metabolic rate of 13NH3 was assessed under basal conditions and during adenosine administration. 13NH3 metabolism proceeds faster in transplant patients than in volunteers under both conditions. Adenosine administration causes a faster 13NH3 turnover in volunteers but not in transplant patients. Application of individual metabolite correction resulted in a 16% decrease in the calculated blood flow compared to uncorrected values. A smaller difference (5%) was observed between correction with mean metabolite values and individually acquired metabolite values.

Adenosine↗
PubMed1995

Investigation of the labelling characteristics of 99mTc-mercaptoacetyltriglycine.

S-Benzyl-, S-benzamidomethyl- and S-benzoylmercaptoacetyltriglycine were synthesized and compared in exchange labelling experiments for the preparation of 99mTc-MAG3. The rate of exchange from 99mTc-tartrate to 99mTc-MAG3 starting from the respective precursors was determined in different conditions. Labelling proceeded most rapidly starting from the S-benzoyl protected precursor but efficient labelling was also accomplished using the more stable S-benzamidomethyl- and S-benzylmercaptoacetyltriglycine. 99mTc-MAG3 was also prepared by direct labelling of unprotected mercaptoacetyltriglycine at alkaline pH. Radiochemical purity in these conditions is mainly dependent on the pH during labelling.

Animals↗
PubMed1995

Comparative evaluation of 99Tcm-Hynic-HSA and 99Tcm-MAG3-HSA as possible blood pool agents.

Two strategies have been used to increase the 99Tcm binding strength of human serum albumin (HSA) and thus enhance its blood retention. In a first approach, HSA was derivatized with a varying number of hydrazino nicotinyl (Hynic) side-chains using N-hydroxysuccinimidyl hydrazino nicotinate. Labelling of this albumin derivative with 99Tcm resulted in labelling yields of 90-95%. On the other hand, a 99Tcm-MAG3-HSA conjugate was prepared using the preformed chelate approach. In this way, non-specific binding of 99Tcm to HSA could be excluded. The in vitro stability of both 99Tcm-HSA derivatives was evaluated by cysteine challenge experiments and revealed a much higher stability for 99Tcm-Hynic-HSA than for 99Tcm-MAG3-HSA. The biological behaviour of the preparations was evaluated in mice and a rabbit using 125I-HSA as an internal biological standard. The blood retention of 99Tcm-MAG3-HSA decreased more rapidly than that of 125I-HSA in both animal species, whereas 99Tcm-Hynic-HSA seemed to provide a quasi-perfect 99Tcm-labelled analogue for 125I-HSA and 99Tcm-red blood cells (99Tcm-RBCs). In addition, the blood retention of 99Tcm-Hynic-HSA appeared to be similar to that of 99Tcm-RBCs in a volunteer. These results clearly indicate the superiority of 99Tcm-Hynic-HSA over 99Tcm-MAG3-HSA as a possible blood pool agent.

Animals↗
PubMed1995

Dynamic antral scintigraphy to characterize gastric antral motility in functional dyspepsia.

UNLABELLED: We evaluated intragastric food distribution and antral motor activity in patients with functional dyspepsia. METHODS: A standard gastric emptying test and dynamic imaging of the antrum were used to characterize gastric antral motility disturbances and to correlate them with total and compartmental gastric emptying in 25 dyspeptic patients. RESULTS: We found a 40% prevalence of gastroparesis in functional dyspepsia. Solid gastric emptying delay is indicated by a prolonged lag phase and an increase in frequency and amplitude of gastric contractions, resulting in nonexpulsive antral contractions and/or antropyloric dyscoordination. Food retention in the distal stomach and antral distention appears to account for patients' dyspeptic symptoms. CONCLUSION: This study demonstrates that scintigraphy not only detects abnormalities of food distribution in the stomach but also provides information on antral motor activity noninvasively. Dynamic antral scintigraphy and compartmental gastric emptying are useful tools to define the pathophysiology of dyspeptic patients with or without gastroparesis.

Adult↗
PubMed1994

Clinical value of whole-body positron emission tomography with [18F]fluorodeoxyglucose in recurrent colorectal cancer.

To assess the clinical value of whole-body positron emission tomography (PET) with [18F]fluorodeoxyglucose (FDG) in recurrent colorectal cancer, 35 patients were studied: 15 had resectable liver metastases, one a resectable lung metastasis, eight resectable pelvic recurrence, eight a presacral mass with equivocal findings on imaging, and three increasing serum levels of carcinoembryonic antigen (CEA) without clinical or radiological signs of recurrent disease. PET affected management decisions in seven of 16 patients with metastatic disease. In one of eight patients with pelvic recurrence demonstrated by computed tomography (CT), PET detected unknown pulmonary metastases. In five of eight presacral masses with equivocal CT findings, PET was correct and unexpected distant metastases were detected in one of these patients. In two of three patients with increasing CEA levels and normal pelvic CT findings, pelvic recurrence was identified. Overall, whole-body PET affected management in 14 patients. PET is a valuable tool for staging local recurrence and metastatic disease.

Aged↗
PubMed1994

Histological alterations in chronically hypoperfused myocardium. Correlation with PET findings.

BACKGROUND: In patients with chronic coronary artery disease (CAD) and left ventricular dysfunction, flow/metabolic studies of the myocardium with positron emission tomography (PET) are able to distinguish viable but dysfunctional myocardium from irreversible ischemic injury and scar tissue. In this study, PET findings of blood flow and metabolism in chronically hypoperfused myocardium were correlated with histology. METHODS AND RESULTS: We studied 33 patients suffering from CAD. In each patient, myocardial blood flow and metabolism were measured with PET 1 or 2 days before revascularization. During surgery, transmural biopsies were taken from the left ventricular anterior wall and planimetrically scored for the degree of myolysis (sarcomere loss). The amount of connective tissue was calculated using morphometric techniques. Contrast ventriculography demonstrated abnormal wall motion in 23 patients. Fourteen patients with a mismatch pattern (decreased flow with preserved metabolism) in the biopsy region after quantitative analysis of the PET data showed 11 +/- 6 vol% fibrosis and 25 +/- 13% cells with sarcomere loss. The space formerly occupied by sarcomeres was mainly replaced by glycogen and mitochondria. A significant wall motion improvement was noted 3 months after surgery. Nine patients showed a match pattern (concordant flow/metabolism defects). The biopsies revealed 35 +/- 25% fibrosis and 24 +/- 15% glycogen-storing cells. The biopsies of the 10 patients with normal anterior wall motion showed 8 +/- 4% fibrosis and 12 +/- 8% glycogen-accumulating cells. CONCLUSIONS: It can be concluded that areas with impaired wall motion and a PET match pattern show extensive fibrosis. Regions with reduced flow and preserved FDG metabolism, however, contain predominantly viable cells. In these regions, significant recovery of wall motion is found after revascularization. Regions with normal wall motion contain predominantly viable cells. Cells with reduced contractile material and increased glycogen content are mainly found in areas with wall motion impairment but are also present in areas with normal wall motion and a severe stenosis of the coronary vessel.

Biopsy↗
PubMed1994

Labelling of poly-L-lysine with 99mTc and evaluation as a possible tracer agent for ventriculography.

A stable 99mTc-labelled compound that is easy to prepare and that is retained for a long period of time in the blood would constitute an ideal replacement for 99mTc-HSA (limited by its rapid diffusion) and 99mTc-erythrocytes (lengthy and risky in vitro labelling) as tracer agent for ventriculography. We investigated whether 99mTc-labelled polymers would be suitable for this purpose. Four types of poly-L-lysine (PL) (Mw 41,000 to 377,000) were used either in underivatized form labelled at pH 12, or derivatized with a varying number of mercaptoacetyl (MA) substituents by reaction with N-hydroxysuccinimidyl-S-acetylmercaptoacetate followed by deprotection with hydroxylamine and labelling at pH 7.5. A high labelling yield was obtained in all cases. HPLC-purified 99mTc-PLs and 99mTc-MA-PLs were evaluated in mice, with 125I-HSA as an internal biological standard. The retention in the blood at 10 minutes and 60 minutes p.i. was not higher than about 30% for any of the tested compounds versus 84% for 125I-HSA, and was only 10% for the smallest 99mTc-labelled PL and MA-PL. Liver uptake was high for the 99mTc-PLs, whereas the 99mTc-MA-PL's were excreted in significant amounts to the urine. It is concluded that 99mTc-labelled poly-L-lysines or polymercaptoacetyl-poly-L-lysines are not suitable as blood pool tracer agents.

Animals↗