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Biomedical subjects

M Osteaux

Publications and source records attributed to M Osteaux.

At least 19 recordsLinked to original sources
PubMed2005

Sonography of a rupture of the tendon of the extensor pollicis longus muscle: initial clinical experience and correlation with findings at cadaveric dissection.

OBJECTIVE: The objectives of our study were to report our initial clinical experience with sonography of the wrist for diagnosing a proximal rupture of the tendon of the extensor pollicis longus (EPL) muscle and to perform sonographic-anatomic correlation of the EPL tendon. MATERIALS AND METHODS: Clinical and imaging files of five patients who underwent sonography and subsequent open wrist surgery were reviewed retrospectively. Imaging was performed by four radiologists experienced in musculoskeletal sonography. Tendon retraction was evaluated on sonography and at surgery. In cadavers, sonography was performed in concert by two musculoskeletal radiologists during progressive stages of dissection of four embalmed specimens. One specimen was sliced in the transverse plane. RESULTS: In cadavers, the EPL tendon was located on or adjacent to Lister's tubercle and extended to the base of the thumb. The EPL tendon crossed over the extensor carpi radialis tendons where it exhibited a flattened aspect. In the five patients in the study, a tubular-shaped hypoechoic area was evident at the position of the ruptured EPL tendon on sonograms. At surgery, this area corresponded to fluid, hemorrhage, and scar tissue in the EPL tendon sheath. The assessment of tendon retraction on sonography correlated with findings at surgery. CONCLUSION: Sonography may aid in diagnosing a rupture of the EPL tendon and in the preoperative assessment of gap size and position of the retracted tendon ends. A characteristic tubular hypoechoic area may be seen crossing over the extensor carpi radialis tendons.

Aged↗
PubMed2003

Can bone marrow edema be seen on STIR images of the ankle and foot after 1 week of running?

PURPOSE: To evaluate whether initiation of running in sedentary individuals would lead to bone marrow edema on MR images, within the time span of 1 week. MATERIALS AND METHODS: The feet of 10 healthy volunteers were imaged by MR imaging before and after running during 30 min a day for 1 week. The images were evaluated by consensus of 2 musculoskeletal radiologists who graded the presence of bone marrow edema on a 4-point scale. Edema scores and number of bones involved before and after running were compared statistically. RESULTS: Edema was present on the baseline images in 3 subjects. After running edema showed an increase or was present in 5 subjects. The changes after running were statistically significant. Bones involved were the talus, calcaneus, navicular bone, cuboid bone, and 5th metatarsal. CONCLUSION: Edema patterns can be seen in the feet of asymptomatic individuals. During initiation of running an increase of edema or development of new edema areas can be seen.

Adult↗
PubMed2003

Comparison of surface coil and knee coil for evaluation of the patellar cartilage by MR imaging.

PURPOSE: The aim of this work was to compare the knee coil and the surface coil for the visualisation of the patellar cartilage. MATERIALS AND METHODS: In 28 patients (17 women, 11 men) with an average age of 40 years (range 14-76) with knee pain MR was performed. Transverse images were obtained using a fast spin echo proton density weighted sequence on a Philips Gyroscan Intera 1.5 T clinical system. Transverse images were obtained at the level of the patellar cartilage using both the surface and the knee coil. All images were evaluated by consensus of two radiologists. They evaluated a number of quality criteria on a 4-point scale. Criteria for artefacts were also graded on a 4-point scale. RESULTS: For the visualisation of fluid there was no significant difference between the knee coil and the surface coil (P=0.021). For all other criteria regarding image quality and presence of imaging artefacts there was a significant difference between both coils (P<0.001) with the surface coil obtaining the better result. CONCLUSION: The use of the surface coil in the visualisation of the patellar cartilage can be recommended at knee MR.

Adolescent↗
PubMed2003

CT doses in children: a multicentre study.

We evaluated examination protocols used for common CT procedures of paediatric patients at different hospitals in Belgium in order to determine whether adjustments related to patient size are made in scanning parameters, and to compare patient doses with proposed reference levels. Three paediatric hospitals and one non-paediatric hospital participated in the study. Weighted CT dose-index (CTDI(w)), dose-length product (DLP) and effective dose (E) were evaluated for three patient ages (1 year, 5 years and 10 years) and three common procedures (brain, thorax and abdomen). CTDI(w) and DLP values higher than the reference levels were found for all types of evaluated examination. E ranged from 0.4 mSv to 2.3 mSv, 1.1 mSv to 6.6 mSv, and 2.3 mSv to 19.9 mSv for brain, thorax and abdomen examinations, respectively. All centres but one adapted their protocols as a function of patient size. However, no common trend in the selection of protocols was observed. Some centres divided the whole range of patient size into only two/three groups by age, while others classified the patients into six groups by weight. It was also observed that some centres used the same mAs for the total range of patient sizes and decreased the pitch factor for small children, which resulted in higher doses. This indicates the importance of careful selection of technical scan parameters. If CT parameters used for paediatric patients are not adjusted on the basis of examination type, age and/or size of the child, then some patients will be exposed to an unnecessarily high radiation dose during CT examinations.

Adolescent↗
PubMed2002

Patient and staff exposure during endoscopic retrograde cholangiopancreatography.

Despite a number of efforts being put into the radiological protection of both patient and staff during interventional radiological (IR) procedures during recent years, information about radiation exposure during endoscopic retrograde cholangiopancreatography (ERCP) procedures remains scarce. The purpose of this study was to estimate both patient and staff radiation doses during therapeutic ERCP procedures by direct measurement and to compare these results with data from other IR procedures. For 54 patients, effective dose and skin dose were estimated by measuring the dose-area product. For staff, entrance surface doses to the lens of the eye, thyroid and hands were estimated by thermoluminescent dosemeters. A median effective dose of 7.3 mSv and a median entrance surface dose of 271 mGy per procedure were estimated for patients. The gastroenterologist received a median dose of 0.34 mGy to the lens of the eye, 0.30 mGy to the skin at the level of the thyroid and 0.44 mGy to the skin of the hands, per procedure. When comparing the dosimetric quantities presented in this study with data from other IR procedures, it is clear that patient skin doses and doses to staff are high owing to the use of inappropriate X-ray equipment. ERCP requires the same radiation protection practice as all IR procedures. It should be consistently included in future multicentre IR patient and staff dose survey studies at national or international level.

Adult↗
PubMed2002

[Radiological differential diagnosis of focal liver lesions with anatomo-pathological correlations].

Starting from the macroscopic, microscopic and circulatory characteristics of focal liver lesions, we aimed at assessing the possibilities and the limits of their radiological differential diagnosis. We compared the normal hepatic parenchyma (in terms of: general morphology, cellularity, necrosis, macro- and micro-circulation) and the lesions, assessed following the radiological features of echoreflectivity, RX density, contrast dynamics and specific contrast uptake. The association of morphologic and dynamic features can sometimes lead to an excellent diagnostic specificity (by example: angioma); in other fields, interesting results are noted, but the limits of every modality require further evaluation. This study applies to the following focal lesions: angioma, focal hyperplasia, adenoma, regeneration nodule, hepatocarcinoma, metastasis.

Aged↗
PubMed2001

Echo planar magnetic resonance imaging of anisotropic diffusion in asparagus stems.

MR diffusion-weighted imaging (DWI) uses the signal loss associated with the random thermal motion of water molecules in the presence of magnetic field gradients to derive a number of parameters that reflect the translational mobility of the water molecules in tissues. In highly organized but asymmetric structures, this mobility may be affected by the obstacles present and this in a direction-dependent way. Important examples of this are white brain matter and the stem of certain plants, both containing fibrous components where diffusion of water molecules across fibers is much more restricted than along the fibers. Diffusion that exhibits such directional dependence is said to be anisotropic, and diffusion tensor magnetic resonance imaging allows localized characterization of this behavior. Interpretation of the information obtained in terms of the underlying tissue structure is often hampered by the complexity of factors that can produce the observed behavior. A phantom that exhibits well-defined anisotropic diffusion and yields sufficient signal can help the experimental testing of the relevant methods and models. In this paper, we have used a phantom consisting of asparagus stems as a test object for assessing the value of the acquisition and postprocessing techniques commonly used in the clinic for this kind of investigation. Because of its strongly fibrous and cylindrically symmetric morphology, exhibiting a well-defined sub-classification of cells on the basis of size and shape, asparagus allows a relatively simple interpretation of the results obtained in the diffusion experiments. Our experiments show that the known structural information about the main cell types encountered correlates well with the behavior patterns of the diffusion parameters.

Algorithms↗
PubMed2001

Posterolateral supporting structures of the knee: findings on anatomic dissection, anatomic slices and MR images.

In this article we study the ligaments and tendons of the posterolateral corner of the knee by anatomic dissection, MR-anatomic correlation, and MR imaging. The posterolateral aspect of two fresh cadaveric knee specimens was dissected. The MR-anatomic correlation was performed in three other specimens. The MR images of 122 patients were reviewed and assessed for the visualization of different posterolateral structures. Anatomic dissection and MR-anatomic correlation demonstrated the lateral collateral, fabellofibular, and arcuate ligaments, as well as the biceps and popliteus tendons. On MR images of patients the lateral collateral ligament was depicted in all cases. The fabellofibular, arcuate, and popliteofibular ligaments were visualized in 33, 25, and 38% of patients, respectively. Magnetic resonance imaging allows a detailed appreciation of the posterolateral corner of the knee.

Aged↗
PubMed2001

Quiz case. Symptomatic type II accessory navicular.

A 17 year old boy, who twisted his left foot while playing soccer a few days earlier, presented with pain and swelling along the medial aspect of the left foot. Clinical examination revealed an area of swelling and tenderness anteroinferiorly to the medial malleolus. Radiographs were considered normal and the patient was treated with a topical anti-inflammatory agent. During the following seven months the patient continued to experience pain on the medial side of the left foot, especially after a prolonged activity and when putting on shoes. Focal redness and tenderness was also evident.

Adolescent↗
PubMed2001

MR imaging of meniscal cysts: evaluation of location and extension using a three-layer approach.

PURPOSE: To analyze the extension of medial and lateral meniscal cysts relative to the capuloligamentous planes of the knee. MATERIALS AND METHODS: The MR images of 32 patients with meniscal cysts were reviewed. The location and extension of the meniscal cysts with reference to the capsule and ligaments were recorded. RESULTS: Most medial meniscal cysts were located posteromedially. Posteromedial meniscal cysts usually penetrated the capsule and were located between layer I and the fused layers II+III. From this site some extended anteriorly and then became located superficial to the superficial MCL. The location of lateral meniscal cysts was more varied. Anteriorly the cysts were located deep to the iliotibial band, whereas posterolateral cysts were located deep to the lateral collateral ligament. CONCLUSION: Although the site of capsular penetration of meniscal cysts is determined by the location of meniscal tears, the possible pathways of extension appear to be determined by the capsuloligamentous planes of the knee.

Adolescent↗
PubMed2001

Diffusion and perfusion MRI: basic physics.

Diffusion and perfusion MR imaging are now being used increasingly in neuro-vascular clinical applications. While diffusion weighted magnetic resonance imaging exploits the translational mobility of water molecules to obtain information on the microscopic behaviour of the tissues (presence of macromolecules, presence and permeability of membranes, equilibrium intracellular-extracellular water, ellipsis), perfusion weighted imaging makes use of endogenous and exogenous tracers for monitoring their hemodynamic status. The combination of both techniques is extremely promising for the early detection and assessment of stroke, for tumor characterisation and for the evaluation of neurodegenerative diseases. This article provides a brief review of the basic physics principles underlying the methodologies followed.

Cerebrovascular Disorders↗
PubMed2001

Actual trends in diagnosis/thrombolytic therapy of acute cerebral stroke.

The recent reports confirm the idea that the selection of cerebral stroke patients for thrombolysis should be performed by MRI. These studies suggested that DWI/PWI/MRA may be able to identify patients who are most likely to benefit from thrombolytics, and that the PWI>DWI pattern in particular is associated with an improved outcome from thrombolytic therapy. However, many questions remain unanswered and a lot of work is necessary before MRI guided thrombolysis in acute cerebral stroke becomes a part of the standard care.

Acute Disease↗
PubMed2001

b matrix errors in echo planar diffusion tensor imaging.

Diffusion-weighted magnetic resonance imaging (DW-MRI) is a recognized tool for early detection of infarction of the human brain. DW-MRI uses the signal loss associated with the random thermal motion of water molecules in the presence of magnetic field gradients to derive parameters that reflect the translational mobility of the water molecules in tissues. If diffusion-weighted images with different values of b matrix are acquired during one individual investigation, it is possible to calculate apparent diffusion coefficient maps that are the elements of the diffusion tensor. The diffusion tensor elements represent the apparent diffusion coefficient of protons of water molecules in each pixel in the corresponding sample. The relation between signal intensity in the diffusion-weighted images, diffusion tensor, and b matrix is derived from the Bloch equations. Our goal is to establish the magnitude of the error made in the calculation of the elements of the diffusion tensor when the imaging gradients are ignored.

Brain Infarction↗
PubMed2001

MR imaging of the medial collateral ligament bursa: findings in patients and anatomic data derived from cadavers.

OBJECTIVE: The purpose of this work was to define the MR imaging findings of fluid collections confined to the medial collateral ligament (MCL) bursa and to correlate these findings with anatomic features shown in cadaveric specimens. MATERIALS AND METHODS: The anatomic location of the MCL bursa was investigated by MR-anatomic correlation in seven cadaveric knees. The MR imaging studies and clinical charts of six patients with fluid collections confined to the MCL bursa were reviewed. RESULTS: On anatomic sections, the MCL bursa was located between the superficial and deep portions of the MCL. Separate femoral and tibial compartments were seen in most specimens. CONCLUSION: The anatomy of the MCL bursa is shown with MR imaging in cadaveric specimens and patients. Understanding the compartmentlike distribution of fluid in the MCL bursa at MR imaging allows accurate diagnosis and differentiation from other conditions.

Adult↗
PubMed2001

Diffusion-weighted MR imaging of intracerebral masses: comparison with conventional MR imaging and histologic findings.

BACKGROUND AND PURPOSE: The purposes of this study were to find the role of diffusion-weighted MR imaging in characterizing intracerebral masses and to find a correlation, if any, between the different parameters of diffusion-weighted imaging and histologic analysis of tumors. The usefulness of diffusion-weighted imaging and apparent diffusion coefficient (ADC) maps in tumor delineation was evaluated. Contrast with white matter and ADC values for tumor components with available histology were also evaluated. METHODS: Twenty patients with clinical and routine MR imaging/CT evidence of intracerebral neoplasm were examined with routine MR imaging and echo-planar diffusion-weighted imaging. The routine MR imaging included at least the axial T2-weighted fast spin-echo and axial T1-weighted spin-echo sequences before and after contrast enhancement. The diffusion-weighted imaging included an echo-planar spin-echo sequence with three b values (0, 300, and 1200 s/mm(2)), sensitizing gradient in the z direction, and calculated ADC maps. The visual comparison of routine MR images with diffusion-weighted images for tumor delineation was performed as was the statistical analysis of quantitative diffusion-weighted imaging parameters with histologic evaluation. RESULTS: For tumors, the diffusion-weighted images and ADC maps of gliomas were less useful than the T2-weighted spin-echo and contrast-enhanced T1-weighted spin-echo images in definition of tumor boundaries. Additionally, in six cases of gliomas, neither T2-weighted spin-echo nor diffusion-weighted images were able to show a boundary between tumor and edema, which was present on contrast-enhanced T1-weighted and/or perfusion echo-planar images. The ADC values of solid gliomas, metastases, and meningioma were in the same range. In two cases of lymphomas, there was a good contrast with white matter, with strongly reduced ADC values. For infection, the highest contrast on diffusion-weighted images and lowest ADC values were observed in association with inflammatory granuloma and abscess. CONCLUSION: Contrary to the findings of previous studies, we found no clear advantage of diffusion-weighted echo-planar imaging in the evaluation of tumor extension. The contrast between gliomas, metastases, meningioma, and white matter was generally lower on diffusion-weighted images and ADC maps compared with conventional MR imaging. Unlike gliomas, the two cases of lymphomas showed hyperintense signal on diffusion-weighted images whereas the case of cerebral abscess showed the highest contrast on diffusion-weighted images with very low ADC values. Further study is required to find out whether this may be useful in the differentiation of gliomas and metastasis from lymphoma and abscess.

Adult↗
PubMed2001

Severe adverse reactions with contrast agents for magnetic resonance: clinical experience in 30,000 MR examinations.

We report on the frequency, manifestations and reactions to gadolinium contrast media in patients who underwent MR imaging at our institution between 1988 and 1998. During a 10-year period 30,000 patients received an intravenous injection of 0.1 mmol/kg gadoterate meglumine or gadopentetate dimeglumine for an MRI examination. When a reaction occurred a written report was made (the events were categorized into mild, moderate, and severe). In the period of 10 years we obtained three reports of moderate or severe reactions to the administration of gadolinium. This paper discusses the safety issues of intravenous contrast media in MR imaging, focusing on two gadolinium complexes, gadoterate meglumine, gadopentetate dimeglumine.

Adult↗
PubMed2001

Primary pancreatic and renal non-Hodgkin's lymphoma: CT and MR findings.

Primary malignant non-Hodgkin's lymphoma of the pancreas or the kidney is uncommon. We describe a case of primary non-Hodgkin's lymphoma of the pancreas consisting of 3 masses and causing acute pancreatitis, combined with a primary non-Hodgkin's lymphoma of the left kidney, without the presence of abdominal lymphadenopathies. Our case report is documented with CT as well as MR images.

Adult↗