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Biomedical subjects

R Oyen

Publications and source records attributed to R Oyen.

At least 37 records · Page 2Linked to original sources
PubMed2000

Renal infarction as a cause of acute flank pain.

Renal infarction results from occlusion of the main renal artery or its distal branches. The clinical picture depends on the extent and the rapidity of the occlusion. Herein, the different imaging modalities (including ultrasonography, computed tomography, magnetic resonance imaging, intravenous urography, and angiography) for diagnozing renal infarction are discussed. The key-modality is computed tomography. Because of the limited warm ischemia time of the kidneys (1.5 hours?) and the time required for diagnosis, there is no real therapeutic relevance in most cases.

Acute Disease↗
PubMed1999

The contribution of magnetic resonance imaging to the three-dimensional treatment planning of localized prostate cancer.

PURPOSE: To investigate whether the use of transaxial and coronal MR imaging improves the ability to localize the apex of the prostate and the anterior part of the rectum compared to the use of transaxial CT alone, and whether the incorporation of MR could improve the coverage of the prostate by the radiotherapy field and change the volume of rectum irradiated. METHODS AND MATERIALS: Ten consecutive patients with localized prostate carcinoma underwent a CT and an axial and coronal MR scan in treatment position. The CT and MR images were mathematically aligned, and three observers were asked to contour independently the prostate and the rectum on CT and on MR. The interobserver variability of the prostatic apex location and of the delineation of the anterior rectal wall were assessed for each image modality. A dosimetry study was performed to evaluate the dose to the rectum when MR was used in addition to CT to localize the pelvic organs. RESULTS: The interobserver variation of the prostatic apex location was largest on CT ranging from 0.54 to 1.07 cm, and smallest on coronal MR ranging from 0.17 to 0.25 cm. The interobserver variation of the delineation of the anterior rectum on MR was small and constant along the whole length of the prostate (0.09+/-0.02 cm), while for CT it was comparable to that for the MR delineation at the base of the prostate, but it increased gradually towards the apex, where the variation reached 0.39 cm. The volume of MR rectum receiving more than 80% of the prescribed dose was on average reduced by 23.8+/-11.2% from the CT to the MR treatment plan. CONCLUSION: It can be concluded that the additional use of axial and coronal MR scans, in designing the treatment plan for localized prostate carcinoma, improves substantially the localization accuracy of the prostatic apex and the anterior aspect of the rectum, resulting in a better coverage of the prostate and a potential to reduce the volume of the rectum irradiated to a high dose.

Dose-Response Relationship, Radiation↗
PubMed1999

Pelvic floor descent in females: comparative study of colpocystodefecography and dynamic fast MR imaging.

The purpose of this study was to compare fast dynamic magnetic resonance imaging (MRI) with colpocystodefecography (CCD) in the evaluation of pelvic floor descent in women. Thirty-five women with clinical evidence of pelvic floor descent were studied. A fast single-shot MR sequence was performed in the supine position during pelvic floor relaxation and during maximal pelvic strain. On the same day, a dynamic CCD was performed with the patient seated on a stool-chair. The degree of descent of the bladder, vagina, and anorectal junction was evaluated as the vertical distance between the pubococcygeal line and the bladder base, the vaginal vault, and the anorectal junction, respectively. A bulge of more than 3 cm measured as the distance between the extended line of the anterior border of the anal canal and the tip of the rectocele was interpreted as a rectocele. MRI was compared with CCD during maximal pelvic strain (CCD 1) and during voiding and defecation (CCD II). CCD was considered as the gold standard. Compared with clinical examination, CCD I showed a larger number of involved compartments, except for the middle compartment. CCD II was superior to clinical examination in all cases. In comparison with CCD I and especially CCD II, MRI had a lower sensitivity, especially for the anterior and middle compartment. Even four enteroceles seen on CCD II were not detected by MRI. When CCD I and CCD II were compared, a cystocele, a vaginal vault prolapse, an enterocele, and a rectocele were more readily seen on CCD II than with CCD I. When compared with CCD, supine dynamic MRI is unreliable, especially in the anterior and middle compartment. Even in the detection of enteroceles CCD was superior to MRI. In general, the best results with MRI can be expected for evaluation of the rectum.

Adult↗
PubMed1999

Time-resolved MR angiography of the upper abdomen: initial clinical experience.

In this study, thirty-eight patients with a variety of upper abdominal diseases were examined with three-dimensional time-resolved MR angiography (7 sec/data set). Visualisation of arterial and venous anatomy was excellent in the majority of patients. Moreover, subtraction images could be calculated and organ perfusion could be assessed. It is concluded that this technique opens new perspectives for a comprehensive evaluation of vascular and parenchymal disease.

Abdomen↗
PubMed1999

Production and characterization of anti-kell monoclonal antibodies using transfected cells as the immunogen.

Monoclonal antibodies (Mabs) to blood group antigens are valuable as diagnostic reagents for typing red blood cells (RBCs) in the clinical setting, and for structure-function studies of proteins. Here, we report a powerful system that enabled us to produce Mabs to blood group antigens. A murine erythroleukaemia (MEL) cell line expressing Kell protein, a transmembrane glycoprotein that carries a number of clinically relevant antigens, was used as a novel immunogen. Mabs with different specificities to the Kell protein were produced from a single mouse fusion: an anti-Jsb (MIMA-8), and two antibodies (MIMA-9 and MIMA-10) with novel specificities, that reacted with RBCs with the common Kell phenotype but not with RBCs with K+k- or Kp(a+b-) or K0 phenotypes. The non-reactivity with both K+k- or Kp(a+b-) RBCs implied that the epitope was influenced by the molecular changes associated with an absence of the k or Kpb antigens. MIMA-8 is the first example of a Mab anti-Jsb and was used in the clinical laboratory for screening donor RBCs for Js(b-) blood and for typing RBCs from patients even when the RBCs were coated with anti-IgG as is the case in autoimmune haemolytic anaemia. Heavy and light chain variable regions of MIMA-8 were cloned and the sequence is given. This study illustrates the potential of this novel immunization approach for making monoclonal antibodies to blood group antigens.

Animals↗
PubMed1999

Cervical carcinoma: optimized local staging with intravaginal contrast-enhanced MR imaging--preliminary results.

Ten patients suspected of having cervical carcinoma underwent magnetic resonance (MR) imaging before and after opacification of the vagina with a mixture of barium, water, and maltodextrin/calcium lactate. Use of vaginal contrast medium resulted in improved visualization of the vaginal wall, lumen, and fornices in all patients and in a change in local tumor stage in two patients (20%). This technique may contribute to improved noninvasive staging of cervical carcinoma.

Adult↗
PubMed1998

Transitional cell carcinoma in a renal allograft.

A large urothelial tumor was detected by ultrasonography in the dilated collecting system of a well-functioning renal allograft 15 years after transplantation. The tumor was confirmed at computed tomography. Nephrectomy showed a transitional cell carcinoma. The occurrence of malignant tumors in renal allografts is a well known but rare complication.

Carcinoma, Transitional Cell↗
PubMed1998

Acute obstruction of the renal collecting system: the intrarenal resistive index is a useful yet time-dependent parameter for diagnosis.

The aim of this study was to determine whether the intrarenal resistive index (RI) can be used for the diagnosis of acute obstruction in patients with renal colic and to determine whether the index is time-related. Seventy patients referred to the Emergency Department with acute renal colic and without known associated renal disease underwent duplex Doppler ultrasonography to determine the intrarenal RI at the symptomatic and asymptomatic side. The age range of the patients was 18-72 years. An RI greater than 0.68 and/or an interrenal difference in RI greater than 0.06 and/or an increase in RI of more than 11% compared with the normal side proved reliable cut-off values to diagnose acute renal obstruction. In addition, time dependency of the increase in RI was noted. No significant differences were observed within the first 6 h after the onset of symptoms. From 6 to 48 h, however, the mean RI in the affected kidney (0.70 +/- 0.06; mean +/- SD) was significantly different from that in the normal kidney (0.59 +/- 0.04) (P < 0.001). In the same period the mean difference in RI was 0.08-0.13 (P < 0.001). After 48 h the sensitivity of RI dropped substantially. It is concluded that renal duplex Doppler ultrasonography is useful for diagnosing acute renal obstruction between 6 and 48 h after the onset of symptoms.

Acute Disease↗
PubMed1998

Partial nephrectomy for renal cell carcinoma can achieve long-term tumor control.

PURPOSE: Partial nephrectomy is becoming more widely accepted as alternative treatment for small renal cell carcinoma. To analyze its value in tumor control and its complication rate a retrospective study was done. MATERIALS AND METHODS: A total of 76 patients underwent kidney sparing surgery, which was required in 25 and in the presence of a normal contralateral kidney in 51. Tumor size varied between 0.9 and 15 cm. Simple enucleation was done in 4 and partial nephrectomy in all other cases. The patients were followed every 3 months during year 1, every 4 months during years 2 and 3, and every 6 months during years 4 and 5 postoperatively. Mean followup is 75 months. RESULTS: Eight patients had postoperative complications, most often hemorrhage. None of the patients had local recurrence, although in 3 systemic disease developed. CONCLUSIONS: Nephron sparing surgery is more challenging than radical nephrectomy and, therefore, can be more complicated. The selection of suitable candidates is the key to success. Many patients can benefit from nephron sparing surgery for small easily resectable renal cell carcinoma even in presence of a normal contralateral kidney. Randomized trials are needed to establish the definitive role of this approach in kidney cancer treatment.

Aged↗
PubMed1998

[Primary retroperitoneal extragonadal germ cell tumor].

A case is presented of a primary extragonadal retroperitoneal germ cell tumor (seminoma) in a 51-year-old male. The ultimate diagnosis was only achieved after curative surgical resection of the tumor. There was no demonstrable testicular neoplasm.

Germinoma↗
PubMed1997

Cell kinetic measurements in prostate cancer.

PURPOSE: Two approaches have been suggested for escalating the total dose in radiotherapy treatment of prostate cancer. One is conformal radiotherapy; the other is hyperfractionation using many small fractions. Both imply some possible prolongation in overall treatment time. To judge whether prolonged treatment schedules would be detrimental, it is necessary to know the proliferation rates in human prostate tumors, specifically, the potential doubling time (Tpot). There is a lack of data on this parameter in the literature. METHODS AND MATERIALS: Seven patients with adenocarcinoma of the prostate were studied. A tracer dose of 100 mg/m2 of IUdR was infused intravenously 4-12 h before biopies were taken. Biopsies were fixed in 70% ethanol, stored at 4 degrees C, and later prepared and stained by standard methods for flow cytometry, using the red fluorescence signal for DNA and the green fluorescence signal (fluorescein isothiocyanate) for 5-iodo-2'-deoxyuridine. The duration of DNA synthesis (Ts) was determined by the relative movement (RM) method, knowing the interval between tracer administration and biopsy. Tpot was calculated as the quotient of Ts by labeling index (LI). RESULTS: In two of the seven tumors the LI was too low (<0.6%) for a reliable estimate of RM to be made, so no determination of Tpot was possible for these tumors. The mean LI values in the other five tumors were 2.4%, 1.4%, 1.0%, 3.0%, and 0.9%. The durations of Ts were 13.2, 9.5, 10.0, 11.7, and 12.7 h, respectively. The resulting values of Tpot were 23, 28, 42, 16, and 61 days, respectively. CONCLUSION: The low labeling indices in prostate tumors, also reported by others, made estimation of Ts by RM impossible in about a third of these tumors. However, five tumors yielded long estimates for Tpot, implying that prolongation from 6 to about 8 weeks should not be detrimental.

Adenocarcinoma↗
PubMed1997

Non-Hodgkin's lymphoma of the prostate in a young male.

A case of non-Hodgkin's lymphoma (NHL) involving the prostate and the urinary bladder in a 24-year-old male is reported. Although none of the currently available imaging modalities is specific for the diagnosis of NHL of the prostate, this diagnosis must be considered because of its amenability to treatment. The heterogeneity of the mass at CT and MRI might be suggestive of high-grade NHL. The patient was treated with intensive combination chemotherapy.

Adult↗