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Biomedical subjects

A M De Schepper

Publications and source records attributed to A M De Schepper.

At least 109 records · Page 6Linked to original sources
PubMed1996

Unusual presentation of ovarian pathology on CT.

A prospective study including seventy-seven consecutive patients suspected of having ovarian tumoral or pseudotumoral pathology on CT was carried out. Fifty-nine patients had surgery with histological diagnosis. When comparing the CT and histological findings in benign and malignant lesions we obtained an overall accuracy of 95% with only three misdiagnosed cases on CT. False positive diagnosis of malignancy was established in a case of abdominal actinomycotic infection, a case of chronic appendicitis, and in a ruptured ectopic pregnancy. These three cases are discussed in detail.

Adult↗
PubMed1995

Postmortem MRI of the brain with neuropathological correlation.

We prospectively correlated in vitro MRI of the brain with the neuropathological findings in patients with suspected intracranial disease. In vitro MRI was performed on 91 consecutive formalin-fixed whole-brain specimens. In 60 cases, the images were correlated with the neuropathological findings (number of lesions, lesion boundaries, spread of oedema and type of lesions). As compared with neuropathology, MRI showed an equal number of lesions in 50 cases, more in 5, and less in 5 specimens, resulting in a sensitivity of 83.3%. The extent of perilesional oedema was better seen on in vitro MRI than on gross pathology. Microscopic extent of glial tumours was underestimated on both T2-weighted images and macroscopic examination. Neuropathology remains the reference study, since on in vitro MRI primary brain tumours, metastatic deposits and non-neoplastic space-occupying lesions cannot be differentiated. However, in our study MRI had a specificity of 76.6%. MRI of postmortem specimens is sensitive to focal brain lesions, and can focus the attention of the neuropathologist to abnormal regions.

Adolescent↗
PubMed1995

Chondrosarcoma in a patient with relapsing polychondritis.

A case of a chondrosarcoma in a patient with relapsing polychondritis was presented. The association of these two unusual disorders of cartilaginous tissue has never been described before. The clinical presentation and radiologic and histologic features were discussed.

Bone Neoplasms↗
PubMed1995

Low-field versus high-field MR imaging of the knee: a comparison of signal behaviour and diagnostic performance.

A prospective study was undertaken to compare MR imaging of the knee obtained with low-field and high-field systems. In 10 subjects, MR imaging of the knee was performed on a 0.2 T permanent magnet and on a 1.5 T superconductive system. Similar spin echo (SE) and 3D-FISP (3D Fourier transform with steady state precession) acquisitions were obtained. Comparative image analysis was performed independently by four radiologists. Results show that the image quality and diagnostic performance delivered by state-of-the-art 0.2 T and 1.5 T systems is equivalent. Advantages of the 1.5 T system included: better signal-to-noise ratio, shorter scan times, better visualization of asymptomatic grade 1 meniscal degeneration on SE images. Advantages of 0.2 T images were: decreased chemical shift, susceptibility and flow artifacts, improved evaluation of subchondral bone on 3D-FISP images, slightly better patient tolerance. We conclude that, for MR imaging of the knee, a low-field system is a cost-effective alternative to more expensive superconducting units.

Adult↗
PubMed1995

Magnetic resonance imaging of cartilaginous tumors: a retrospective study of 79 patients.

OBJECTIVE: Hyaline cartilaginous tumors are characterized by extremely high signal intensity on T2-weighted images. Recently, some distinctive MR features of cartilaginous bone tumors were reported in small series. Low signal intensity septa surrounding high signal intensity cartilage lobules were seen on T2-weighted images in low-grade chondrosarcomas. On spin-echo T1-weighted images after Gd contrast injection, marked 'septal' or 'ring-and-arc' enhancement was observed in low-grade chondrosarcomas and enchondromas. The purpose of this study was to determine sensitivity and specificity of these MR findings in diagnosis of cartilaginous tumors, and to assess the value of MR in diagnostic workup of these lesions. MATERIALS AND METHODS: Retrospective evaluation of MR findings in 79 cartilaginous tumors and in 79 non-cartilaginous tumors. All lesions were biopsy proven. Each MR examination was independently reviewed by two experienced radiologists without knowledge of clinical data, radiographic and/or CT findings, or histological diagnosis. All lesions were evaluated for morphology (lobular or non-lobular), presence of a high signal intensity mass on T2-weighted images, presence of low signal intensity septa separating high signal intensity lobules on T2-weighted images, and evidence of septal ('ring-and-arc') enhancement. RESULTS: None of the reviewed parameters is useful in diagnosing osteochondromas. Since osteochondromas have a characteristic appearance on plain radiography, the value of MR imaging in the workup of these lesions remains limited. MR findings in enchondromas have a low specificity and a low sensitivity. Low-grade chondrosarcomas, often hard to diagnose on plain radiography and difficult to differentiate from enchondromas, are characterized by the MR tandem of 'low signal intensity septa on T2-weighted images' together with 'septal or ring-and-arc enhancement' (sensitivity 92.3%, specificity 76.5%). High-grade chondrosarcomas are easily recognized on plain radiography. CONCLUSIONS: In differentiating cartilaginous from non-cartilaginous tumors, MR features are highly specific but lack sensitivity. Grading potentials of MR parameters are promising due to the high accuracy in diagnosing low-grade chondrosarcomas.

Adolescent↗
PubMed1994

Understanding chemical shift induced boundary artefacts as a function of field strength: influence of imaging parameters (bandwidth, field-of-view, and matrix size).

OBJECTIVE: To study the importance of chemical shift induced boundary artefact (CSA) at different field strengths and the implications for pulse sequence design with respect to receiver bandwidth (BW), field-of-view (FOV) and matrix size. MATERIALS AND METHODS: A fat-water phantom was examined in MR systems of different field strength (1.5 T, 1.0 T and 0.2 T), using pulse sequences with different receiver BW, FOV, and matrix size. The chemical shift was quantified by measuring the width of the bright and dark misregistration rims seen at the planar fat-water interface. The measured chemical shift was compared with the theoretically calculated chemical shift. RESULTS: Excellent correlations were found between predicted chemical shift and measurement results in our experiments. The width of the CSA (in millimetres) is directly proportional to field strength, inversely proportional to receiver BW and hence to the strength of the readout gradient, directly proportional to FOV, and inversely proportional to matrix size. CONCLUSION: CSA occurs at all magnetic field strengths, but given a certain BW it is more pronounced at higher fields. Although the CSA in Hz is directly proportional to field strength, the visible CSA at low-field was slightly higher than theoretically expected. The relative lack of CSA in low-field strength images permits the application of narrow receiver BW sequences, resulting in increased signal to noise ratio.

Artifacts↗
PubMed1993

MR imaging of eosinophilic granuloma: report of 11 cases.

The findings in 11 patients with histologically proven eosinophilic granuloma (EG) examined by magnetic resonance imaging (MRI) are described. In contrast with the variable appearance of EG on conventional radiography and computed tomography (CT), relatively constant features--intermediate to high signal intensity on T1-weighting, high signal intensity on T2-weighting, marked enhancement--were found on MRI. MRI was superior to other imaging methods in demonstrating bone marrow involvement and any accompanying soft tissue mass or inflammation. Intermediate to high signal intensity on T1-weighting and marked contrast enhancement could not be "explained" by histological findings. Prediction of the evolutionary phase of EG by MRI remains questionable because of the phase I (proliferative) histology of all 11 lesions.

Adolescent↗
PubMed1993

Epidural and subdural contrast in myelography and CT myelography.

A retrospective study of 624 lumbar myelographic and CT myelographic procedures was undertaken to evaluate the frequency, radiographic and clinical relevance of contrast medium outside the dural sac. Our findings indicate that epidural contrast is frequently identified on CT scans with highly sensitive window settings (in 35.4% of all CT myelographic studies). Standard myelographic films are less sensitive for the detection of epidural contrast (9.6%). Subdural contrast is far less often encountered (in 2.4% of CT myelographic studies and in 3.2% of standard myelographic films). We believe leakage of contrast to occur through the puncture site into the epidural and subdural space.

Adult↗
PubMed1993

Tuberous sclerosis: CT and MRI characteristics.

Tuberous sclerosis is a disease characterized by the presence of hamartomatous nodules in various organs, including the brain. Thirteen CT scans and four MR investigations were performed in 13 patients. CT is superior to MR in demonstrating the presence of subependymal nodules, thereby confirming or establishing the diagnosis of tuberous sclerosis. MR is superior to CT in demonstrating the peripheral lesions, which are characterized by a long T2-relaxation time. Differentiation between cortical tubers and subcortical lesions is not yet accurate.

Adolescent↗
PubMed1993

Ruptured balloon separation during percutaneous transluminal renal artery angioplasty.

A rare complication of percutaneous transluminal renal artery angioplasty is reported. Separation of a ruptured balloon was followed by embolism and acute limb ischaemia requiring emergency surgery. Both the renovascular hypertension and the complication of angioplasty were treated successfully. This case illustrates the need for close collaboration between interventional radiologists and vascular surgeons.

Adult↗
PubMed1993

MRI of acoustic schwannoma: a retrospective study of 89 tumours.

Magnetic resonance imaging (MRI) is now considered the diagnostic study of choice for evaluation of patients with suspected acoustic schwannoma. This retrospective study of 118 MR examinations presents an analysis of the MR findings of 89 acoustic tumours in 86 patients. The method of examination included precontrast and gadolinium(Gd)-enhanced MRI in 72 and plain MRI in 14 patients. The common MR-appearances of acoustic schwannomas were: on T1-weighted images (WI) isointense (36%) or slightly hypointense (64%) relative to the brainstem; intense and homogeneous contrast enhancement in 62%; the shape of the tumour was round or oval in 71%; the tumour was centred at/or located in the internal auditory canal (IAC) in 80%. The small acoustic schwannomas were mostly round or oval in shape and showed homogeneous signal intensity (SI) both before and after Gd. The larger acoustic tumours were more heterogeneous in morphology and SI. The significance of these and other signs, early diagnosis and differential diagnosis are discussed.

Adolescent↗