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Biomedical subjects

F E Lecouvet

Publications and source records attributed to F E Lecouvet.

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

The lumbar vertebral body and diskovertebral junction. Radio MR imaging anatomic correlations.

Radiographs and MR images of spine specimens provide superb tomographic views of changes that involve the mineralized network and the medullary content of vertebral bodies. By illustrating changes in the balance between bone resorption and formation and between fat and nonfat marrow cells, these frozen images of the reality help us to understand normal variants and lesions that develop in osseous and articular diseases of the lumbar spine.

Bone Marrow↗
PubMed2000

Dual-detector spiral CT arthrography of the knee: accuracy for detection of meniscal abnormalities and unstable meniscal tears.

PURPOSE: To determine the sensitivity and specificity of dual-detector spiral computed tomographic (CT) arthrography of the knee in the detection of meniscal abnormalities and unstable meniscal tears. MATERIALS AND METHODS: The meniscal changes in 50 consecutive patients who underwent dual-detector spiral CT of the knee after intraarticular injection of iodinated contrast material (0.55-mm effective section thickness, 0.75 pitch value, 0.3-mm increment reconstruction, 0.43-mm in-plane resolution, 0.3-mm longitudinal resolution) were determined by two observers and were compared with arthroscopic findings. The sensitivity and specificity of CT arthrography for the detection of meniscal abnormalities and unstable meniscal tears and the kappa statistics for assessing interobserver reproducibility were determined. RESULTS: The sensitivity and specificity for the detection of meniscal abnormalities were 98% and 94%, respectively. The sensitivity and specificity for the detection of unstable meniscal tears were 97% and 90%, respectively. Interobserver agreement was excellent for the detection of meniscal abnormalities (kappa = 0.899) and of unstable meniscal tears (kappa = 0.885). CONCLUSION: Dual-detector spiral CT arthrography of the knee is an accurate and reproducible method for detecting meniscal abnormalities and unstable meniscal tears.

Adult↗
PubMed1999

Resolution of early diffusion-weighted and FLAIR MRI abnormalities in a patient with TIA.

We report a patient with a clinical history and neurologic examination consistent with acute stroke. Diffusion-weighted and fast fluid-attenuated inversion recovery MRI obtained 4 hours after stroke onset detected focal abnormalities suggestive of acute ischemic brain damage. The neurologic deficit and the imaging abnormalities both resolved completely at follow-up. This patient illustrates complete resolution of early changes observed with diffusion-weighted MRI at the hyperacute phase in a TIA.

Aged↗
PubMed1999

Ferumoxides-enhanced quantitative magnetic resonance imaging of the normal and abnormal bone marrow: preliminary assessment.

The purpose of our study was to assess the effects of intravenous administration of ferumoxides on normal and abnormal vertebral bone marrow T1 and T2 relaxation times. Changes in bulk T1 and T2 relaxation times induced by intravenous administration of ferumoxides were determined in the normal vertebral marrow of two healthy subjects and four patients. In the four patients, changes in bulk T1 and T2 values induced by furomoxides injection were also determined in 12 vertebral metastases. Relative to precontrast relaxation time values, bulk T1 and T2 values of normal bone marrow had declined by a mean of 24% and 19%, respectively, in the two subjects and the four patients 45 minutes after ferumoxides administration. Relative to precontrast values, bulk T1 and T2 values of abnormal bone marrow had decreased by a mean of 16% and 2%, respectively. Decreases in bulk T1 and T2 values in normal bone marrow and in bulk T1 values in metastases were statistically significant (P<0.001). Changes in bulk T2 values observed in metastases were not statistically significant. Quantitative MRI demonstrates that ferumoxides infusion induces a decrease in bulk T1 and T2 relaxation times of normal bone marrow. It also suggests a lack of T2 shortening in bone metastases.

Adult↗
PubMed1999

Fat conversion of femoral marrow in glucocorticoid-treated patients: a cross-sectional and longitudinal study with magnetic resonance imaging.

OBJECTIVE: To study the changes in hematopoietic marrow in patients given glucocorticoid (steroid) therapy. METHODS: In a cross-sectional study, high-resolution T1-weighted magnetic resonance imaging (MRI) images of the proximal femur were obtained in an unselected series of 29 premenopausal female patients with systemic lupus erythematosus (SLE) and in a series of 29 age-matched healthy female subjects. In a longitudinal analysis, 2 MRI studies were performed 19 months apart in 11 patients with SLE (including 9 patients from the cross-sectional study who were evaluated before treatment) and in 7 patients with rheumatoid arthritis (RA). The percentage of fat marrow and the index of marrow conversion (IMC) were derived from the MRI images to estimate the degree of transformation of hematopoietic into fatty marrow in the area of the femoral neck. Values observed in the cross-sectional study and their changes over time were correlated with treatment data. RESULTS: The cross-sectional study performed in SLE patients indicated that their mean (+/- SD) percentage of fat marrow (48+/-36%) and IMC (82+/-12) were significantly more elevated than those in the healthy control subjects (18+/-16% and 75+/-6, respectively) (P<0.01). The magnitude of fat conversion correlated positively with the mean daily dose of oral prednisolone, and was higher in patients with ischemic bone lesions. The longitudinal study performed in SLE and RA patients revealed that IMC changes over time correlated positively with daily prednisolone intake (r = 0.71; P = 0.001), fat conversion occurring exclusively in patients receiving a mean prednisolone dose < or =7.5 mg/day. CONCLUSION: MRI indicates that fat conversion occurs in the proximal femur of steroid-treated patients. The magnitude of fat conversion correlates with steroid intake and is higher in patients with ischemic bone lesions.

Adolescent↗
PubMed1999

Skeletal survey in advanced multiple myeloma: radiographic versus MR imaging survey.

In an attempt to compare the sensitivity of bone radiographs and bone marrow magnetic resonance (MR) imaging for bone lesion detection in patients with stage III multiple myeloma (MM) and to evaluate the possible consequences of the replacement of the conventional radiographic skeletal survey (RSS) by an MR survey of the spinal and pelvic bone marrow in these patients, we obtained MR studies of the thoracic and lumbar spine, pelvis and proximal femurs in addition to the conventional RSS (including radiographs of the skull, entire spine, pelvis, ribs, humerus and femurs) in 80 consecutive patients with newly diagnosed stage III MM according to the Durie and Salmon staging system (based on blood tests and on the RSS). The performance of MR and radiographic studies to detect bone lesions in given anatomic areas and in given patients were compared. The consequences on MM staging following the substitution of the RSS by the MR survey were assessed. MR imaging was superior to radiographs for lesion detection in the spine (76% v 42% of patients) and pelvis (75% v 46% of patients). The RSS was superior to the limited MR imaging survey for the detection of bone involvement in the patient population (87.5% v 79% of patients). If the RSS had been replaced by the MR imaging survey for patient staging, 7/80 patients would have been categorized as stage I and one as stage II MM on the basis of normal MR findings and biological findings consistent with these stages. Substitution of the RSS by a limited spinal and pelvic marrow MR survey would lead to 'understaging' of 10% of patients with otherwise stage III MM on the basis of blood tests and the conventional RSS.

Adult↗
PubMed1999

Idiopathic bone marrow edema lesions of the femoral head: predictive value of MR imaging findings.

PURPOSE: To determine the frequency of several subchondral magnetic resonance (MR) imaging features observed in bone marrow edema lesions of the femoral head and to determine their value for differentiation of irreversible from transient lesions. MATERIALS AND METHODS: The authors reviewed MR images of 72 femoral head lesions in 42 men and 25 women (median age, 48 years) with equivocal radiographic findings and bone marrow edema seen at MR imaging (T1- and T2-weighted images in all patients and contrast material-enhanced T1-weighted images in 39 patients). Follow-up MR images showed 57 lesions to be transient and 15 to be irreversible. The presence and size of subtle subchondral features observed on initial MR images were compared for both types of lesion. RESULTS: Lack of any additional subchondral change on T2-weighted or contrast-enhanced T1-weighted images had 100% positive predictive value for transient lesions. For irreversible lesions, presence of a subchondral area of low signal intensity at least 4 mm thick or 12.5 mm long had positive predictive values of 85% and 73%, respectively, on T2-weighted images and 87% and 86%, respectively, on contrast-enhanced T1-weighted images. CONCLUSION: Careful assessment of subchondral changes enables confident differentiation between early irreversible lesions and transient bone marrow edema lesions.

Bone Marrow Diseases↗
PubMed1998

Magnetic resonance imaging of the normal bone marrow.

The bone marrow is a complex organ that contains fat and nonfat cells, the proportions of which vary greatly with age and in the different bones of the skeleton. Magnetic resonance (MR) imaging provides information on the composition of the medullary cavity of any given bone and on the distribution of red and yellow marrow in the skeleton. This article deals with the wide spectrum of appearances of the normal bone marrow at MR imaging.

Adipocytes↗
PubMed1998

Classification and detection of bone marrow lesions with magnetic resonance imaging.

A logical approach to bone marrow alterations is proposed that takes into account the high sensitivity and specificity of MR imaging for the detection of marrow fat. Marrow signal intensity on T1-weighted images is assumed to reflect the balance between fat and nonfat marrow components. Elementary patterns of marrow change include marrow depletion, infiltration, replacement and signal void. These patterns can be observed alone or in combination, and can be distributed in a focal or diffuse manner. Marrow depletion pattern shows high signal intensity reflecting increase in fat content and is frequently irrelevant clinically. Signal intensity is decreased in marrow infiltration, replacement and signal void patterns, which indicates partial or complete disappearance of fat. Focal marrow infiltration is frequently reactive to an adjacent abnormality, whereas focal marrow replacement more frequently indicates a more profound marrow alteration. The T1-weighted spin-echo sequence is satisfactory for lesion detection by virtue of its relatively high sensitivity in the detection of altered fat/nonfat marrow balance. T2-weighted sequences with saturation of the signal of fat protons or out-of-phase gradient-echo sequences improve lesion conspicuity in all situations in which the difference in fat/nonfat marrow balance between the abnormal area and the adjacent normal marrow is reduced.

Adult↗
PubMed1998

Treated plasma cell lesions of bone with MRI signs of response to treatment: unexpected pathological findings.

Two cases of treated plasma cell lesions of bone are reported for which contrast-enhanced MRI had suggested necrosis, based on lack of enhancement after gadolinium injection, and in which pathologic examinations revealed the presence of extensive viable neoplastic tissue. These cases highlight the need for cautious interpretation of contrast-enhanced MRI signs of response to treatment and inactivity of lesions in the setting of plasma cell neoplasms.

Adult↗
PubMed1998

Magnetic resonance imaging of normal bone marrow.

The appearance in magnetic resonance imaging (MRI) of the bones depends, to a large extent, on the unmineralized content of the bone cavities. Because yellow marrow contains a large number of fat protons and red marrow a significant number of water protons, MRI offers the opportunity to map the distribution of red and yellow marrow. In addition, red marrow MR appearance varies according to the relative proportion of fat and nonfat cells. Variations in the composition of red marrow and its distribution among normal subjects, mainly in relation to age and sex, contribute to creating a wide spectrum in bone MR appearance, which must be known in order to avoid confusion with bone marrow abnormalities.

Adipose Tissue↗
PubMed1998

Magnetic resonance imaging of the bone marrow in hematological malignancies.

Despite its lack of specificity, magnetic resonance imaging (MRI) of the bone marrow has the potential to play a role in the management of patients with primary neoplastic disorders of the hematopoietic system, including lymphomas, leukemias and multiple myeloma. In addition to its use in the assessment of suspected spinal cord compression, bone marrow MRI could be used as a prognostic method or as a technique to assess the response to treatment. The current review addresses the common patterns of bone marrow involvement observed in primary neoplasms of the bone marrow, basic technical principles of bone marrow MRI, and several applications of MRI in selected clinical situations.

Adolescent↗
PubMed1998

Stage III multiple myeloma: clinical and prognostic value of spinal bone marrow MR imaging.

PURPOSE: To determine the clinical and prognostic value of spinal bone marrow magnetic resonance (MR) imaging in stage III multiple myeloma. MATERIALS AND METHODS: In 80 patients with untreated, newly diagnosed stage III multiple myeloma, initial MR imaging patterns of spinal bone marrow involvement were correlated with hematologic parameters and response to induction chemotherapy. The influence of these patterns on survival was studied in 57 patients who did not undergo cytotoxic therapy with stem cell transplantation. RESULTS: MR imaging patterns of marrow involvement were normal in 19 (24%) patients, focal in 35 (44%), and diffuse in 26 (32%). Patients with the diffuse pattern had higher marrow plasmacytosis (P < or = .003) and cellularity (P < or = .001), higher serum calcium (P < or = .005) and beta 2-microglobulin (P < or = .008) levels, and lower hemoglobin values (P < or = .001) than did those with the normal or focal patterns. Patients with the normal pattern responded better to therapy (P = .007) and survived longer than patients with an abnormal pattern (P = .026). MR imaging findings and C-reactive protein level were the best independent prognostic indicators of survival. CONCLUSION: MR imaging patterns of spinal bone marrow involvement are correlated with several clinical parameters of disease severity and have prognostic value in stage III multiple myeloma.

Adult↗
PubMed1998

Early irreversible osteonecrosis versus transient lesions of the femoral condyles: prognostic value of subchondral bone and marrow changes on MR imaging.

OBJECTIVE: The purpose of this study was to determine the MR imaging features that enable differentiation between early irreversible osteonecrosis and transient lesions in nontraumatic lesions of the femoral condyle having the "bone marrow edema" pattern on MR imaging. MATERIALS AND METHODS: We reviewed 23 nontraumatic painful lesions of the femoral condyle in 23 patients (12 men and 11 women; mean age, 62 years). All patients had undergone radiography of the knee with findings that were normal or inconclusive. Also, all patients underwent MR imaging that revealed the bone marrow edema pattern in a condyle. Lesions observed after trauma, surgery, or glucocorticoid medication, or with epiphyseal collapse or degenerative joint disease on initial plain radiographs, were excluded from this study. Of the 23 lesions, 14 showed complete resolution (and were designated as transient epiphyseal lesions). The remaining nine lesions were irreversible and, on follow-up radiographic and MR imaging studies, evolved to collapsed osteonecrosis (and were designated as early osteonecrosis). The presence and size of the subchondral features observed by two radiologists on initial MR studies were compared for both irreversible and transient epiphyseal lesions. RESULTS: Initial MR imaging characteristics indicative of an early irreversible osteonecrosis included a subchondral area of low signal intensity on T2-weighted images with a thickness of more than 4 mm (sensitivity, 100% and 100%; specificity, 82% and 74% for the two observers) or a length of more than 14 mm (sensitivity, 89% and 88%; specificity, 93% and 87% for the two observers), focal epiphyseal contour depressions, and lines of low signal intensity located deep in the affected condyle. The extent of edema was similar for both transient epiphyseal lesions and early osteonecrosis. CONCLUSION: Careful assessment of MR imaging changes occurring in the subchondral area can enable confident differentiation between transient epiphyseal lesions and early irreversible osteonecrosis of the femoral condyle.

Bone Marrow↗
PubMed1998

Ganglion cysts of the knee: articular communication revealed by delayed radiography and CT after arthrography.

OBJECTIVE: The diagnosis of ganglion cysts of articular origin may sometimes be uncertain when communication with the joint is not evident. Because we have observed that opacification of ganglion cysts revealed by arthrography can be significantly delayed, the purpose of this study was to determine retrospectively in 20 cases the time delay needed to show with arthrography a communication between the articular cavity and ganglion cysts of the knee. CONCLUSION: Arthrographic evidence of a communication between the articular cavity of the knee and communicating ganglion cysts requires delayed radiography performed at least 1 hr after intraarticular injection of contrast material. The best results are obtained with additional CT performed 1-2 hr after injection.

Adult↗