Biomedical subjects

C van de Wiele

Publications and source records attributed to C van de Wiele.

5 recordsLinked to original sources

PubMed2003

Biodistribution and dosimetry study of 123I-rh-annexin V in mice and humans.

This study reports on the optimization of the labelling procedure of clinical grade 123I-rh-annexin V and on the investigation of the biodistribution and dosimetry of 123I-rh-annexin V, a tracer proposed for the study of apoptosis in mice and humans. Research grade 123I-rh-annexin V was prepared as described previously, whereas clinical grade 123I-rh-annexin V was prepared according to a modified IodoGen method. NMRI mice, 3-4 weeks of age, received research grade 123I-rh-annexin V (74.0+/-3.7 kBq/mouse) by intravenous (i.v.) injection and killed at preset time points. Afterwards, the collected organs, blood, urine and faeces were counted for radioactivity and determined as %ID/g tissue or %ID over time. Secondly, six volunteers with normal liver and kidney function underwent whole-body scans up to 21 h after i.v. injection of clinical grade 123I-rh-annexin V (345+/-38 MBq). Time-activity curves were generated for the organs of interest, e.g., thyroid, heart, liver, kidneys and whole body, by fitting the organ specific geometric mean counts, obtained from region of interest analysis of acquired images in humans. The MIRD formulation was applied to calculate the absorbed radiation doses for various organs. Clinical grade 123I-rh-annexin V was obtained in radiochemical yields of 87.0+/-6.5% and radiochemical purities >98%. In mice, research grade 123I-rh-annexin V accumulated primarily in liver, kidney, stomach and lung tissue, limiting its usefulness for imaging of ongoing apoptosis in the abdominal and thoracic region. Clearance was predominantly urinary. In humans, acquired images with the clinical grade radioligand showed low lung uptake, resulting in good imaging conditions for the thoracic region. On the other hand, delayed imaging of the abdominal region was impeded due to extensive bowel activity. The highest absorbed doses were received by the thyroid, the kidneys, the heart wall, the liver and bone surfaces. The average effective dose of 123I-rh-annexin V was estimated to be 0.02 mSv.MBq-1. The amount of 123I-rh-annexin V required for in vivo imaging, results in an acceptable effective dose to the patient.

Adult↗

PubMed2001

Fluorine-18 fluorodeoxyglucose-position emission tomography: a highly accurate imaging modality for the diagnosis of chronic musculoskeletal infections.

BACKGROUND: The noninvasive diagnosis of chronic musculoskeletal infections remains a challenge. Recent studies have indicated that fluorine-18 fluorodeoxyglucose-positron emission tomography is a highly accurate imaging technique and is significantly more accurate than the combination of a bone scan and a white blood-cell scan for the diagnosis of chronic infection in the central skeleton (p < 0.05). However, patients who had had surgery within the previous two years were excluded from study. It was our aim to evaluate the technique in an unselected, clinically representative population. METHODS: Sixty patients with a suspected chronic musculoskeletal infection involving the central skeleton (thirty-three patients) or the peripheral skeleton (twenty-seven patients) were studied with fluorine-18 fluorodeoxyglucose-positron emission tomography. Thirty-five patients had had surgery within the previous two years. The fluorine-18 fluorodeoxyglucose-positron emission tomography studies were read in a blinded, independent manner by two experienced readers. The final diagnosis was based on histopathological studies or microbiological culture (eighteen patients) or on clinical findings after at least six months of follow-up (forty-two patients). RESULTS: On the final composite assessment, twenty-five patients had infection and thirty-five did not. All twenty-five infections were correctly identified by both readers. There were four false-positive findings; in two of these cases, surgery had been performed less than six months prior to the study. The sensitivity, specificity, and accuracy were 100%, 88%, and 93% for the whole group; 100%, 90%, and 94% for the subgroup of patients with a suspected infection of the central skeleton; and 100%, 86%, and 93% for the subgroup of patients with a suspected infection of the peripheral skeleton. Interobserver agreement was excellent (kappa = 0.97). CONCLUSIONS: Fluorine-18 fluorodeoxyglucose-positron emission tomography is highly accurate as a single technique for the evaluation of chronic musculoskeletal infections. It is especially valuable in the evaluation of the central skeleton, where white blood-cell scans are less useful. Because of its simplicity and high degree of accuracy, it has the potential to become a standard technique for the diagnosis of chronic musculoskeletal infections. Further studies are needed to assess its ability to identify infections at the sites of total joint replacements and to distinguish infection from aseptic loosening of these prostheses.

Adolescent↗

PubMed1999

Absolute 24 h quantification of 99Tcm-DMSA uptake in patients with severely reduced kidney function: a comparison with 51Cr-EDTA clearance.

The aim of this study was to determine whether absolute 24 h DMSA uptake measurements (%DMSA) correlate well with 51Cr-EDTA clearance measurements in patients with severely reduced kidney function (SRKF). Between 1990 and 1997, 55 of 482 patients who underwent EDTA clearance measurements also underwent %DMSA within 1 week. Of these, 31 were women and 24 were men (mean age 60 years; range 19-77 years). EDTA clearance was determined using the slope-intercept method. Absolute depth- and background-corrected %DMSA were determined 24 h following the injection of 185 MBq per 1.73 m2 freshly prepared 99Tcm-DMSA. All patients had EDTA clearance < or = 60 ml.min-1. Eighteen patients (group A: 9 men and 9 women, mean age 55.8 years, range 28-73 years) had EDTA clearance > 20 ml.min-1 (mean +/- S.D. = 30.9 +/- 13.8 ml.min-1), whereas 37 patients (group B: 22 women and 15 men, mean age 62.0 years, range 19-77 years) had EDTA clearance < 20 ml.min-1 (mean +/- S.D. = 10.2 +/- 6.6 ml.min-1). EDTA clearance correlated well with %DMSA for the patients as a whole and for group A (r = 0.87, P = 0.73; r = 0.79, P = 0.0001 respectively). The regression equation suggests that %DMSA is not a marker of early renal dysfunction. In group B, the r-value (r = 0.48, P = 0.004) suggests that %DMSA is reliable as a marker of severe renal dysfunction to the extent that it provides rough information. In conclusion, %DMSA may not be used as a marker of early renal impairment. Additionally, in patients with severely reduced kidney function (EDTA clearance < 20 ml.min-1), it only provides a rough estimate.

Adult↗

PubMed1997

201Tl scintigraphy does not allow visualization of the thyroid in euthyroid and hyperthyroid patients treated with amiodarone.

A retrospective study was performed to evaluate the usefulness of thallium scintigraphy for visualization of thyroid morphology and function. Moreover, applying absolute quantitation, we wished to confirm the qualitatively reduced 99Tc(m) uptake reported by Wiersinga et al. in both euthyroid and hyperthyroid patients treated with amiodarone. Over a period of 2 years (1995-96), 10 patients (group A; 2 females, 8 males, mean age 68.6 years, range 61-74 years) receiving amiodarone treatment for cardiac arrhythmias for at least 4 months were referred for exploration of either hyperthyroidism (n = 4) or for exclusion of parathyroid adenoma (n = 6). During the same period, 17 patients (group B; 10 females, 7 males, mean age 62 years, range 19-91 years) referred for Tc-Tl subtraction scintigraphy, and in whom follow-up revealed no thyroid or parathyroid pathology, were used as controls. In all patients, thyroid status was assessed by thyroid function tests. 201Tl and 99Tc(m) uptake was calculated as a percentage of the injected dose, taking account of net injected counts and background and isotope decay correction. Original images were scored using a 2-point scoring system (0 = poor, 1 = fair or good). Uptake of both 99Tc(m) and 201Tl was significantly reduced in group A (99Tc[m]: 0.16 +/- 0.21%; 201Tl: 0.30 +/- 0.21%; mean +/- S.D.) compared to group B (99Tc[m]: 1.58 +/- 1.07%; 201Tl: 0.72 +/- 0.37%) (P < 0.005). The mean relative reduction in 99Tc(m) uptake was more pronounced (90% decrease) than that of 201Tl (58% decrease). In group A, the 99Tc(m) and 201Tl image quality was poor in 10 of 10 and 8 of 10 patients respectively. In group B, the 99Tc(m) and 201Tl image quality was poor in 3 of 17 and 4 of 17 patients respectively. The decreased uptake of 201Tl may reflect the inhibitory effect of iodides on adenyl cyclase and its stimulation by TSH. In conclusion, the data presented confirm the qualitatively reduced pertechnetate uptake reported by Wiersinga et al. Furthermore, 201Tl uptake by the thyroid in euthyroid or hyperthyroid patients treated with amiodarone is also reduced. Although quantitatively less pronounced, it does not allow proper visualization of the thyroid.

Adult↗

PubMed1997

Differential renal function measured by 99Tcm-DTPA and 99Tcm-DMSA in a complete unilateral renal obstruction rat model.

We performed a prospective study to determine whether 99Tcm-DTPA differential renal function (DRF) in the case of acute obstruction in a unipapillary kidney rat model shows a similar pattern of results as 99Tcm-DMSA in a multipapillary kidney model, and to exclude recirculation or a block of tubular transport of DMSA which might explain the discrepancy reported by Kelleher et al. In 15 male and 4 female Wistar rats (weight 300-350 g), 99Tcm-DMSA renal uptake was measured 24 h before complete obstruction of the right ureter, which served as reference values. Twenty-four hours after obstruction, 99Tcm-DTPA (18.5 MBq) renography and 99Tcm-DMSA (111 MBq) non-depth-corrected renal uptake measurements were performed in the 15 male rats; in the 4 female rats, 740 MBq of 99Tcm-DMSA were injected and absolute, non-depth-corrected renal uptake measured at 24, 48 and 72 h. 99Tcm-DMSA DRF of the right kidney ranged from 48 to 55% (mu: 51%; sigma: 2%) before obstruction and from 14 to 35% (mu: 24%; sigma: 6%) after obstruction, whereas 99Tcm-DTPA DRF ranged from 16 to 30% (mu: 25%; sigma: 4%). No significant differences were found between DRF measured by 99Tcm-DMSA and 99Tcm-DTPA (P = 0.18), or between DRF of the obstructed kidney as measured by 99Tcm-DMSA at 24, 48 and 72 h (P > 0.2). Hypothetically, the discrepancy between our findings and those of Kelleher et al. may be due to intratubular pressure. In conclusion, the present findings and those of Kelleher et al. suggest the differences in DRF following complete unilateral renal obstruction, as determined by DTPA and DMSA, are probably species-specific. Furthermore, recirculation and block of tubular transport are unlikely to contribute significantly to differences in DRF as measured by the two radiopharmaceuticals.

Animals↗