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Biomedical subjects

C Van Ongeval

Publications and source records attributed to C Van Ongeval.

18 recordsLinked to original sources
PubMed2006

Evaluation of the diagnostic value of a computed radiography system by comparison of digital hard copy images with screen-film mammography: results of a prospective clinical trial.

The purpose of the study was to determine prospectively the diagnostic value of a computed radiography (CR) system by comparing mammographic hard copy images with screen-film mammography (SFM). A series of 100 patients, who came for diagnostic investigation, underwent two-view SFM (Lorad M-IV Platinum) and digital mammography with a CR system (AGFA CR system). The images were obtained by double exposure, i.e. same view without removing compression of the corresponding breast. The CR images were processed with dedicated processing for mammography. Six radiologists read sets of SFM and CR images. The primary efficacy parameter was the overall diagnostic value. The secondary efficacy parameters were lesion conspicuity and lesion details (for masses and micro-calcifications), tissue visibility at chest wall and at skin line, axillary details, overall density and sharpness impression and the overall noise impression. These parameters were scored by a 7-point scoring system. "CR non-inferior to SFM" was concluded if the lower confidence interval bound exceeded 80%. The confidence interval for the overall diagnostic value was between 96.4% and 100%. Pooled analysis of the ten features for image quality comparison demonstrated for all but one feature (lesion details of the calcifications) CR non-inferiority to SFM.

Adult↗
PubMed2006

Image quality measurements and metrics in full field digital mammography: an overview.

This paper gives an overview of test procedures developed to assess the performance of full field digital mammography systems. We make a distinction between tests of the individual components of the imaging chain and global system tests. Most tests are not yet fully standardised. Where possible, we illustrate the test methodologies on a selenium flat-panel system.

Contrast Media↗
PubMed2006

Current challenges of full field digital mammography.

Full field digital mammography (FFDM) has advantages over screen-film mammography (SFM), but some important challenges remain. The first challenge is related to the specific characteristics of FFDM. It remains unclear, which shape and limiting values of the modulation transfer function have the most influence on the performance of a detector, such as the effect of the image display on the overall image quality and the effect of processing on cancer detection. In order to assess the image quality of FFDM, we have set up a scoring system. The second challenge is related to screening mammography: is the quality of an image the same when it is viewed on different monitors and with different processing algorithms? Is Computer Aided Diagnosis necessary in a screening environment? In FFDM, the effect of different detectors, processing and display possibilities on the image and on cancer detection are not clearly investigated.

Breast Neoplasms↗
PubMed2000

MR imaging of the breast--present indications.

MRI of the breast has proved its role in the diagnosis of breast cancer. Despite the amount of studies with MRI, the technique has not been standardised yet. This is one of the reasons for the huge difference in specificity the reported in the different studies (from 30% to 95%). Because the many pitfalls of the technique, the specificity of MRI of the breast is correlated to the experience of the investigator. When the established indications are respected, specificity increases. Presently accepted indications are: differentiation between postoperative fibrosis and tumor recurrence, multifocality or contralateral breast carcinoma, evaluation of prosthesis, discrepancy between the different diagnostic techniques, high risk patients with dense breasts. Less frequently but nevertheless a good indication is proven axillary lymph node metastases from an unknown primary tumor. Microcalcifications still are not a good indication for MRI of the breast. MRI is still inferior to mammography in detecting ductal in-situ carcinoma or very small carcinomas because the neo-angiogenesis of these tumors is too faint to be detected by contrast-enhanced MRI. MRI instead of mammography or to solve a problem resulting from a bad mammographical examination is certainly not advised. New sequences, including diffusion and perfusion, and new contrast agents are keenly awaited.

Breast↗
PubMed2000

Review of MR mammography techniques.

Many of the new techniques of MRI have promising characteristics for the further improvement of sensitivity and specificity but there remains a large place for clinical trials to evaluate the practical value of the different new approaches. The authors review the general MRI rules that determine image quality and comment on the use-fullness of innovations in MR mammography.

Breast Diseases↗
PubMed1997

Idiopathic granulomatous mastitis.

A case of idiopathic granulomatous mastitis mimicking breast carcinoma clinically and radiographically is reported with mammography, sonography and MR images.

Adult↗
PubMed1995

[Mammographic symptomatology of malignant breast lesions].

Malignant breast images may include opacities (stellar--rounded with blurred margins), microcalcifications, opacities with microcalcifications, asymmetric fibroglandular tissue, or distortion of the mammographic pattern. Secondary signs may also be present, such as skin thickening, skin or nipple retraction, prominent vascularisation, axillary lymph nodes. The aim of this paper is to describe the different aspects and to make the differential diagnosis from benign tumors and normal tissue.

Breast↗
PubMed1995

[Galactography].

Spontaneous single duct discharge is the main indication for galactography. This abnormality has in most cases a benign aetiology (> 90%). With a meticulous technique and sufficient experience, the ducts can be cannulated in 95% of the cases. A nipple adenoma with a blood stained discharge is seldom to pass for cannulation. Because cytology of the nipple discharge is not always positive in case of intraductal proliferations, microdochectomy must be used to obtain the differential diagnosis. Galactography shows multiple normal duct variations, depending on age, surrounding tissue, and a possible history of lactation. Pathologic images can be seen in dystrophic breasts, solitary papillomas, (juvenile) papillomas or (intraductal) carcinomas. In addition to high frequency ultrasonography (> or = 10 MHz), which is able to visualise the retro-areolar and superficial ducts, galactography can give a more detailed and better overview of the pathology.

Adult↗
PubMed1993

Adamantinoma of the tibia: MRI documentation.

We report two cases of adamantinoma of the tibia, for which an MR examination was performed. Each patient was initially investigated with plain radiography and in case 2, a computerized tomography was also performed. The MR characteristics of this tumor are scarcely documented in the even few case reports of this tumor. MRI does not add to the (differential) diagnosis but does have significance in the preoperative staging because it allows adequate delineation of tumor, which is essential for a complete and curative resection of the tumor.

Adolescent↗
PubMed1993

Parosteal osteosarcoma.

A case of parosteal osteosarcoma is reported. In spite of the pathognomonic plain radiographic signs of parosteal osteosarcoma, it is very uneasy to differentiate it from myositis ossificans circumscripta in the mature stage. CT and MRI defined the extent of the tumor into the soft tissue, the medullary and cortical invasion and gave more information about the composition of the lesion.

Adult↗
PubMed1992

Ventricular enlargement, clinical correlates and treatment outcome in chronic schizophrenic inpatients.

The ventricle-brain ratio (VBR) of 42 chronic schizophrenic patients was compared with that of 42 age-matched medical controls. For the schizophrenics, the relationship of various clinical parameters to the VBR was assessed, and the outcome of 12 weeks of double-blind treatment with either risperidone or haloperidol. The results confirm that schizophrenic patients have slightly enlarged lateral ventricles compared with medical controls. Only for schizophrenics, an effect of age, but not of duration of illness, was noticed. This study does not support the validity of a clinical subdivision of chronic schizophrenic patients on the basis of the VBR. Neither negative, positive nor general psychopathological symptoms, as measured by the Positive and Negative Syndrome Scale for Schizophrenia (PANSS), were related to the VBR, nor were abnormal involuntary movements or extrapyramidal symptoms. No association between season of birth or a family history of major mental disorder and VBR could be demonstrated. Treatment response was predicted by the total PANSS score and the PANSS general psychopathology subscale score at baseline. There was a trend for patients with higher VBR to have a more or haloperidol). or haloperidol).

Adult↗
PubMed1991

NMR imaging study of the pharmacodynamics of polylysine-gadolinium-DTPA in the rabbit and the rat.

The pharmacodynamics of polylysine-(Gd-DTPA) (Schering, Berlin, Germany), a new blood pooling contrast agent for MRI, were studied in the rabbit and the rat. Polylysine-(Gd-DTPA) is a compound with high LD50. Due to its high molecular weight (50.000) and physico-chemical properties, it remains in the vascular system; during the first hour, the plasma level is three times higher than for Gd-DTPA. MRI was performed at 1.5 T using a SE sequence with TR/TE = 300/15 or 20 msec. Signal intensities of muscle, liver and kidney were measured before and after intravenous injection of the contrast agent (0.1 mmol/kg) during 8 hours in the rat (n = 3) and up to 2 wk in the rabbit (n = 3). A dose response study in three additional rabbits confirmed that the 0.1 mmol/kg dose was optimal. The pharmacodynamics results show that the effects of polylysine-(Gd-DTPA) are similar in both the rabbit and the rat. The liver signal is enhanced by about 60% immediately after injection in both species. This enhanced signal decays to half its maximal value in about one hour, which makes the contrast agent useful for clinical applications at a dose of 0.1 mmol/kg. In the kidney medulla and cortex the signals are enhanced by much larger factors (about 3 to 4); it takes at least one day for the kidney to clear the contrast agent in both species.

Animals↗
PubMedDate not supplied

Localized 1H NMR spectroscopy in fifty cases of newly diagnosed intracranial tumors.

Fifty patients with newly diagnosed, untreated intracranial tumors were examined with 1H nuclear magnetic resonance single-volume spectroscopy (MRS) using a 1.5 T whole-body MR system. Prior to the MRS, contrast enhanced MR and/or CT imaging studies were carried out. Histological verification was obtained in all patients except one. All tumor spectra revealed distinct abnormalities as compared with the normal brain spectra. Although most meningiomas showed a rather characteristic spectral pattern, generally features specific for the various tumor types were not observed. For instance, though a strong lactic acid signal was seen in most malignant tumors, this signal was also evident in five benign neoplasms.

Adult↗