Experimental Inferior Caval Replacement with Mesothelium

Thrombo-resistance of mesothelial grafts was evaluated by replacing the inferior vena cava in 16 dogs. In 10 dogs, treated by antiplatelet aggregation agents, uniform graft thrombosis happened within 15 days. In six other dogs, the addition of an arterio-venous fistula produced conditions of flow (1385 ± 178 ml/min; mean ± s.e.m.) and velocity (17.1 ± 4.5 cm/s) closer to human values and markedly improved the patency rates (four patent over six up to 6 months P < 0.02). Light microscopy and scanning electron microscopy studies performed on the patent grafts showed well preserved mesothelial cells. Mesothelial fibrinolytic activity was 1160 ± 257 tissue activator units/g tissue before and 846 ± 142 activator units/g tissue after implantation (P = n.s.). Prostaglandin synthesis by native mesothelium was respectively 252 ± 103 and 7 ± 3 pg/ml/mg wet tissue/min for 6-keto-PGF1α and TXB2. The synthesis was reduced for 6-keto-PGF1α in the patent grafts but unaltered for TXB2, This work puts forward the suggestion that mesothelium is a promising venous substitute in conditions of high flow.

[Transient bone marrow edema of the hip]

Transient bone marrow edema of the hip is characterized by moderate homogeneous low MR signal intensity with ill-defined margins that involves at least a portion of the femoral head. Spin echo T1-weighted images are helpful to exclude other underlying diseases (tumor, infection, necrosis from systemic origin…), for which marrow edema is secondary or no epiphyseal in location. High-resolution fat-suppressed T2-weighted or proton density images allow evaluation of the articular cartilage, subchondral bone and subchondal marrow: if the articular cartilage is abnormal, the lesion is irreversible (arthrosis or necrosis); if the subchondral bone is focally interrupted and/or if the femoral is no longer spherical, the lesion is irreversible (necrosis); if a focal linear fluid collection is present under the subchondral bone, the lesion is irreversible (necrosis). Finally, subchondral changes may provide useful prognostic information: the absence of any abnormality other than marrow edema typically indicates that complete resolution is likely; the presence of a focal T2-weighted hypointense lesion immediately next to the subchondral bone suggests an irreversible lesion, especially if it is equal to or thicker than 4mm or the joint space. In some instances, prognosis cannot be reliably determined requiring the need for follow-up imaging.

Hypoplasia of L5 and wedging and pseudospondylolisthesis in patients with spondylolysis: study with MR imaging

BACKGROUND AND PURPOSE

The association between L5 hypoplasia and bilateral spondylolysis was described earlier on conventional radiographs of the lumbar spine. The purpose of this study was to describe the findings on MR imaging in patients with hypoplasia of L5 and to correlate these findings with the presence of bilateral spondylolysis of L5.

MATERIAL AND METHODS

We studied the MR images of 22 patients with hypoplasia and posterior wedging of L5 and with bilateral spondylolysis at L5. The anteroposterior diameter of L4, L5, and S1 were measured and compared. The degree of posterior wedging of L5 was calculated. The degree of anterolisthesis was determined. The intervertebral disks of L4-L5 and L5-S1 were studied.

RESULTS

The mean difference between the anteroposterior diameter of L4 and L5 was 3.0 mm, or 8.8% shortening of L5 compared with L4. The mean difference between the anteroposterior diameter of L5 and S1 was 4.4 mm, or 12.3% shortening of L5 compared with S1. The mean percentage posterior wedging was 24.7%. In 13 patients, there was no anterior vertebral slipping. True anterolisthesis grade I was seen in 5 patients and anterolisthesis grade II in 4 patients. Diskarthrosis with disk dehydration of L4-L5 was seen in 20 of the 22 patients.

CONCLUSIONS

It is confirmed that hypoplasia of L5 can simulate anterolisthesis. Hypoplasia of the vertebral body of L5 can predict the presence of bilateral spondylolysis.

[Principles of analysis for sacroiliac joints imaging]

Interpretation of sacroiliac joints imaging is uneasy. Simultaneous erosions, hyperostosis, and ankylosis together make the diagnosis of inflammatory lesions. Articular abnormalities may also be induced by mechanical stress or ligament ossifications. Distribution of the lesions can help to establish a precise diagnosis. Inflammatory lesions may be located in any part of the articulation, including the posterior and inferior part. Mechanical lesions as in osteitis condensans ilii are commonly located in the anterior middle part of the joint. Ligament ossification in case of idiopathic skeletal hyperostosis is located at the margins of joint. The basic for the interpretation of sacroiliac joints is to look at high quality plain radiographs. When diagnosis is uncertain, complementary methods must be considered. CT is useful for analysis of subacute or chronic lesions and MRI is to be preferred for acute lesions, in young patients and when searching for signs of inflammatory activity in an already known chronic disease.

Bone marrow edema of the femoral head

This article addresses the MR features of the bone marrow edema syndrome (BMES) of the femoral head with emphasis on the prevalence and clinicopathology of the disorder and description of the current concepts on diagnosis and prognosis. BMES can be observed in self resolving conditions such as transient osteoporosis of the hip, spontaneous fracture of the femoral head, or post traumatic lesions. Rapidly destructive coxarthrosis, necrosis of the femoral head as well as certain forms of spontaneous fracture of the femoral head may present a similar MR pattern, though prognosis is definitely less favourable. The challenging role of the radiologist is to recognize BMES at an early stage and to provide adequate prognosis on the lesion outcome.

MR appearance of cartilage defects of the knee: preliminary results of a spiral CT arthrography-guided analysis

The aim of this study was to determine signal intensity patterns of cartilage defects at MR imaging. The MR imaging (3-mm-thick fat-suppressed intermediate-weighted fast spin-echo images) was obtained in 31 knees (21 male and 10 female patients; mean age 45.5 years) blindly selected from a series of 252 consecutive knees investigated by dual-detector spiral CT arthrography. Two radiologists determined in consensus the MR signal intensity of the cartilage areas where cartilage defects had been demonstrated on the corresponding reformatted CT arthrographic images. There were 83 cartilage defects at spiral CT arthrography. In 52 (63%) lesion areas, the MR signal intensity was higher than that of adjacent normal cartilage with signal intensity equivalent to (n=31) or lower than (n=21) that of articular fluid. The MR signal intensity was equivalent to that of adjacent normal cartilage in 17 (20%) lesion areas and lower than that of adjacent cartilage in 8 (10%) lesion areas. In 6 (7%) lesion areas, mixed low and high signal intensity was observed. The MR signal intensity of cartilage defects demonstrated on spiral CT arthrographic images varies from low to high on fat-suppressed intermediate-weighted fast spin-echo MR images obtained with our equipment and MR parameters.

[Cardiac imaging by means of four-detector row computed tomography and cardiac gating]

Electrocardiographically-assisted imaging is a recent development in multislice spiral computed tomography. In this article, we summarize the principles of four-detector row CT for cardiac applications. Following is an overview of the potential of this technique to evaluate the heart, the thoracic aorta, and the paracardiac pulmonary parenchyma. Technical considerations for optimal imaging are highlighted.

Spiral CT arthrography of the knee: technique and value in the assessment of internal derangement of the knee

Computed tomography imaging has achieved excellent multiplanar capability and submillimeter spatial resolution due to the development of the spiral acquisition mode and multidetector row technology. Multidetector spiral CT arthrography (CTA) yields valuable information for the assessment of internal derangement of the joints. This article focuses on the value of spiral CTA of the knee in the assessment of the meniscus, anterior cruciate ligament, and hyaline cartilage lesions. Advantages and disadvantages of spiral CTA with respect to MR imaging are presented.

[Atypical ganglion cysts]

Intra- or para-articular ganglion cysts are frequent and can develop at some distance from the joints. The authors describe examples of typical and atypical ganglion cysts, namely meniscal cyst, intra-articular cyst, intraosseous cyst, intraneural cyst of tibial nerve, adventitial cyst of popliteal artery, and para-articular cyst of the hip, filled with gas of presumed articular origin. The diagnosis of a ganglion cyst can be difficult when there is no evident articular communication. If demonstration of communication is necessary (in case of uncertain diagnosis or for preoperative assessment), the best procedure is arthrography followed by a CT scan 1-2 hours after the injection.

[Myositis ossificans and other ossifying lesions of the soft tissues]

Knowledge of the clinical history and typical imaging characteristics of myositis ossificans is important as identification of this entity will avoid unnecessary and invasive work-up. Conversely, the radiologist must pay attention to any atypical clinical or imaging finding, which will warrant further investigations.

Spiral CT arthrography of the postoperative knee

Computed tomography (CT) has gained multiplanar capability and submillimeter spatial resolution due to the development of spiral acquisition mode and multidetector row technology. Multidetector spiral CT arthrography of the knee is a valuable imaging modality for the assessment of lesions of the meniscus, anterior cruciate ligament (ACL), and articular cartilage. This article presents the value of spiral CT arthrography in the assessment of the postoperative knee with emphasis on the postoperative meniscus, articular cartilage, and ACL graft. This technique may be proposed as an alternative to magnetic resonance arthrography.

[Hip imaging: what is the best modality?]

Conventional radiography plays a key-role in the assessment of symptomatic hips. A well-performed radiographic examination (comparative A-P views with straight or ascending X-Ray beam, off-lateral view of Lequesne) enables to recognise most bone (fractures, transient osteoporosis, epiphyseal osteonecrosis) and articular lesions (osteoarthritis). In some situations (incoherent radio-clinical findings, need of a confident diagnosis), joint aspiration or additional imaging procedures are needed. Serial radiographs are obtained when no specific treatment can be immediately offered. Bone scintigraphy is obtained to confidently exclude bone or articular disorders or in case of suspected disseminated bone disease. The majority of bone, articular and abarticular lesions can be diagnosed by using MRI. It should be obtained when results are likely to influence the final outcome of the disease.

Lesions of the menisci of the knee: value of MR imaging criteria for recognition of unstable lesions

OBJECTIVE

This study aimed to determine the value of four MR imaging criteria for evaluating unstable meniscal lesions.

MATERIALS AND METHODS

Criteria for unstable meniscal lesions were the presence of a displaced meniscal fragment, visibility on more than three 3-mm-thick coronal and two 4-mm-thick sagittal images, having more than one orientation plane or more than one pattern (contour irregularity, peripheral separation, tear), and having intrameniscal high signal intensity on T2-weighted spin-echo images. Sensitivity, specificity, and positive and negative predictive values for recognition of instability among all meniscal lesions were determined for the presence of each individual criterion and for the presence of at least one criterion in 50 consecutive patients (mean age, 46 years) who underwent MR imaging and subsequent arthroscopy.

RESULTS

Sensitivities and specificities of these four criteria ranged between 18% and 54% and between 94% and 100%, respectively. Positive and negative predictive values ranged between 92% and 100% and between 39% and 52%, respectively. The presence of at least one criterion enabled recognition of unstable lesions with a sensitivity and specificity of 82% and with positive and negative predictive values of 90% and 70%, respectively.

CONCLUSION

The four MR imaging criteria have high specificities and positive predictive values and low sensitivities and negative predictive values when evaluating unstable meniscal lesions.

Costal cartilage fractures as revealed on CT and sonography

OBJECTIVE

We describe the CT and sonographic appearance of 15 costal cartilage fractures observed in eight patients.

CONCLUSION

On CT, fracture was seen as a low-density area through the costal cartilage, with surrounding calcifications present near old fractures, and gas density within the cleft in some cases. On sonography, cartilage fracture appeared as an interruption of the smooth anterior aspect of the cartilage.

[Normal bone marrow: dynamic aspects in magnetic resonance imaging]

The bone marrow is a complex organ that contains fat and nonfat cells, the proportion of which varies greatly with age and in the different bones of the skeleton. Magnetic resonance 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. The wide spectrum of appearances of the normal bone marrow at MR imaging will be reviewed. The purpose of this paper is to determine the MR appearance of the bone marrow, to illustrate the phenomenon of marrow conversion and to familiarize the readers with the complex parameters that interfere with the MR appearance of normal bone marrow.

Magnetic Resonance Appearance of Uncomplicated Paget's Disease of Bone

Paget's disease is a disorder of the bone mesenchyma of the skeleton and is a unique condition in which active bone changes can occur without concomitant significant marrow alteration. When present, marrow changes involve predominantly the paratrabecular and endosteal areas, where bone metabolism is increased. At magnetic resonance (MR) imaging, marrow alterations can become prominent and hence confusing in bones with high trabecular content including vertebrae and pelvis. This article addresses the MR appearance of uncomplicated Paget's disease, including normal pagetic bone, predominantly lytic or sclerotic pagetic bone, and unusual partial involvement of the vertebral body. We will emphasize the added diagnostic value of the combination of imaging techniques that depict either osseous changes including radiographs, computed tomography, and bone scintigraphy, or marrow changes, including MR imaging, to contribute to a noninvasive presumptive diagnosis of Paget's disease in atypical presentations.

Bone marrow transplantation in patients with multiple myeloma: prognostic significance of MR imaging

OBJECTIVE

This study in myeloma patients treated with myeloablative therapy and bone marrow transplantation assessed the prognostic value of MR imaging before and after treatment of the bone marrow and the prognostic value of an index reflecting changes on MR images obtained before and after treatment.

SUBJECTS AND METHODS

MR images (T1-weighted images before and after injection of gadolinium and T2(*)-weighted images) of the spine and pelvis were obtained 1 month before and 1 month after marrow transplantation in 25 consecutive patients with stage III myeloma. Pre- and posttreatment MR imaging patterns of marrow involvement (normal, focal, diffuse), number of focal lesions, and a "marrow evolution index" (0-8 on the basis of comparison of the lesions [number, size, contrast enhancement] and of the surrounding marrow background on pre- and posttreatment MR images) were determined. Hematologic and MR imaging parameters were correlated with the quality of response to treatment (complete versus partial remission) and with relapse-free and overall survival.

RESULTS

Response quality did not differ among categories of patients determined on the basis of MR images. Individual MR imaging parameters did not correlate with response duration and survival. Patients with a low marrow evolution index had significantly longer relapse-free (p < 10(-3)) and overall survival (p = 0.005) than patients with a high index.

CONCLUSION

Individual MR imaging parameters before and after treatment had no prognostic significance in our series of myeloma patients treated with marrow transplantation. Comparison of MR images before and after treatment using a marrow evolution index may help predict response duration and survival.

Magnetic Resonance Imaging and Differential Diagnosis of Epiphyseal Osteonecrosis

This article addresses imaging features of epiphyseal osteonecrosis that have been highlighted by the use of magnetic resonance imaging, including better depiction of marrow infarcts, better knowledge of their natural history, and better understanding of the different patterns of epiphyseal osteonecrosis. Imaging features that enable differentiation between irreversible lesions, including epiphyseal osteonecrosis and rapidly progressive osteoarthritis, and spontaneously transient lesions, including transient osteoporosis and epiphyseal fractures, are emphasized.

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.

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.

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.

Retrodural cysts bridging a bilateral lumbar spondylolysis: a report of two symptomatic cases

We report the MR features in two patients presenting with symptomatic thecal impingement by posterior epidural cysts linking a bilateral lumbar spondylolysis. Large fluid-filled channels bridging the ruptured partes interarticulares were present in spite of the absence of significant arthritic changes within the adjacent facet joints.

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.

[Radiology and emergency medicine: state of the art]

Emergency medicine has emerged as a specific medical specialty for 30 years. To be efficient, the emergency clinician frequently needs the contribution of radiological examinations. This is the reason why emergency radiology has emerged as a new radiologic subspecialty. The aim of this paper is to review the recent history of emergency medicine and to summarize the present state of the radiological organisation for emergency care in the Western countries.

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.

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.

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.

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.

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.

[Ultrasonography of dorsal elastofibroma. Apropos of 6 cases]

Elastofibroma dorsi is a benign soft-tissue tumor. Its sub- and pre-scapular location and its appearance on CT and MRI generally lead to the diagnosis. We have analyzed with sonography 6 elastofibromas in 4 patients; the diagnosis was confirmed with CT scan or MRI. Some sonography imaging features supported the diagnosis of elastofibroma dorsi. In all the cases, (1) the tumor occurred typically in a sub- and pre-scapular location, and (2) showed a streaky echostructure (3). A similar symptomatic or asymptomatic mass in the opposite subscapular location is highly suggestive.

Interactive DICOM image transmission and telediagnosis over the European ATM network

The European High-Performance Information Infrastructure in Medicine, n(o)B3014 (HIM3) project of the Trans-European Network--Integrated Broadband Communications (TEN-IBC) program, started on March 1996 and finished on February 1997, aimed to test the medical usability of the European asynchronous transfer mode (ATM) network in medical image transmission. The Department of Radiology, University of Pisa, Pisa, Italy, and St-Luc University Hospital, Brussels, Belgium, involved in the project as healthcare partners in the radiological domain, established several connection sessions finalized to test the usability of Digital Imaging and Communication (DICOM) image transmission and interactive telediagnosis tools in the daily radiological practice. The Pisa site was connected to the Italian ATM pilot (Sirius Network) through the Tuscany metropolitan area network (MAN), while St-Luc University Hospital was connected to Belgium ATM network through the Brussels MAN. By means of international connections provided by the European JAMES project, a link between the two sites was established, connecting both national ATM networks. Due to the large variety of hardware present in the medical centers, multiplatform software tools were used and tested: central test node (CTN) release 2.8 [3], VAT [6], NV-3.3 [7], and IDI (UCL homemade multiplatform teleradiology tool for interactive visualization and processing of DICOM images). During the telediagnosis session, lead by radiologists in both hospitals, each site submitted neuroradiological clinical cases to the other for remote consultation. The connection, available for a period of two weeks, at 2-Mbit/s bandwidth, allowed the transmission of MR images (256 x 256 x 12 bit) and simultaneous multimedia interactive discussion of the cases. Both off-line transmission and review of the images, using the CTN DICOM transfer routines, and on-line interactive image discussion, using the IDI telediagnosis software, were tested successfully from the technical and medical point of view.

MR imaging of bone infarction and epiphyseal osteonecrosis

No single musculoskeletal disorder has generated more passionate discussion than bone osteonecrosis. Surprisingly, its physiopathogenesis remains largely unknown despite in-depth studies. Its treatment is still debated, and its wide range of clinical manifestations which vary from totally asymptomatic to the catastrophic event of irreversible epiphyseal collapse remains a fascinating question for the clinicians (1-4). Magnetic Resonance (MR) imaging has given a large tribute to the discussion during the last decade by allowing detection of marrow infarcts at a presymptomatic period of the disease, thus providing data on its natural history. Unfortunately, MR imaging has also contributed to increase the confusion among various epiphyseal disorders. The aim of the current paper is to provide an overview of the current knowledge of imaging features by stressing accepted data and delineating blind areas.

MR assessment of red marrow distribution and composition in the proximal femur: correlation with clinical and laboratory parameters

OBJECTIVE

To correlate the MR appearance of the proximal femur marrow with clinical and blood parameters.

DESIGN AND PATIENTS

The proportion of the femoral neck surface area occupied by red marrow was determined on T1-weighted magnetic resonance (MR) images of the hip in a series of 120 subjects, aged from 15 to 75 years, with ten females and ten males per decade, and correlated with clinical data. This parameter and the bulk T1 values of femoral red marrow were determined in 30 other subjects 25-46 years of age and correlated with their blood parameters.

RESULTS

In the series of 120 subjects, the proportion of red marrow surface area decreased with age (P < 10(-4)) and was higher in female than male subjects (P < 10(-4)). Within each decade, the proportion of red marrow surface area was higher in females than in males between 25 and 65 years but neither before 25 nor after 65 years. In the series of 30 subjects, the proportion of red marrow surface area and bulk T1 values of femoral red marrow were significantly negatively correlated with hemoglobin blood levels but not with blood cell counts.

CONCLUSION

The MR appearance of proximal femur red marrow is influenced by age and sex. A relationship with hemoglobin blood level is demonstrated.

Effects of riluzole on the evolution of focal cerebral ischemia: a magnetic resonance imaging study

The aim of this study was to investigate the effects of riluzole on the lesion induced by a permanent middle cerebral artery occlusion (MCAO) in rats. Riluzole at 4 or 8 mg/kg i.v. significantly reduced the cortical ischemic brain damage. With the most effective dose of 8 mg/kg, the time evolution of the lesion was assessed by T2-weighted magnetic resonance imaging (MRI) repeated on the same animals after MCAO. MRI obtained at 24, 48, and 72 hours after MCAO showed a progressive increase of the ischemic lesion, except in the cortex of the riluzole-treated rats (8 mg/kg i.v.). Furthermore, there was no difference between lesion volumes as measured by MRI or by histology. This study indicates that MRI may be a valuable method to quantify in vivo the neuroprotective profile of a drug.

[Radiologic aspects of the loosening of cemented hip prostheses: mechanical, septic or granulomatous etiology?]

Radiologic diagnosis of hip prosthesis loosening is based on the evaluation of each component (prosthesis, cement, bone) and of their interfaces. Both the prosthesis and the cement may deteriorate and the prosthesis/cement interface or cement/bone interface may become abnormal in prosthesis loosening of any etiology. In contrast, the aspect of the bone changes (erosion, periostitis) and their distribution vary according to the condition etiology. It appears from a retrospective study of 50 cases of chronic hip prosthesis loosening that the most specific signs for infection are unsharp bone resorption and acute-like or multifocal periostitis. In granulomatous loosening, bone resorption is sharp (as in mechanical loosening), but its distribution is not conform to the prosthesis shape (as in septic loosening), and periosteal changes are not observed.

Long-term effects of localized spinal radiation therapy on vertebral fractures and focal lesions appearance in patients with multiple myeloma

The occurrence of new vertebral fractures and focal marrow lesions was determined and compared in irradiated and nonirradiated vertebrae of 12 patients with multiple myeloma (MM), prospectively followed using magnetic resonance imaging (MRI) of the thoraco-lumbar spine after localized spinal radiation therapy. During follow-up (mean 35 months), fractures appeared in 5% of irradiated vertebrae and in 20% of nonirradiated vertebrae: new focal lesions appeared in 4% of irradiated vertebrae and in 27% of nonirradiated vertebrae. This study demonstrates a beneficial long-term effect of localized radiation therapy, consisting of a reduced incidence of vertebral fractures and focal marrow lesions in irradiated vertebrae.

Detection of reperfused ischemia of the rat intestine: value of magnetic resonance imaging with small-molecular-weight dysprosium and gadolinium chelates

RATIONALE AND OBJECTIVES

The authors assessed whether the small-molecular-weight magnetic resonance (MR) imaging contrast agents dysprosium diethylenetriamepentaacetic acid bismethylamide (sprodiamide injection), which enhances T2*, and gadolinium diethylenetriamepentaacetic acid bismethylamide (gadodiamide injection), which enhances T1, could improve the detection of reperfused ischemia of the rat intestine.

METHODS

Eighteen rats were subjected to vascular occlusion of the distal ileum for 30 minutes, followed by reperfusion. Ten minutes after reperfusion, T1- and T2-weighted spin-echo (SE) images were obtained before and after administration of sprodiamide, gadodiamide, or both. The same imaging protocol was applied in another group of 18 rats subjected to 10 minutes of occlusion and reperfusion. Histologic examination of the intestine was performed after MR imaging.

RESULTS

Villous injury (ie, denudation) was observed in most cases after 30 minutes of occlusion, but not after 10 minutes of occlusion. After 30 minutes of occlusion, the superficial part of the ischemic intestine was hyperintense to the normal intestine on unenhanced T2-weighted images. Administration of sprodiamide improved the contrast between the normal and ischemic intestine on T2-weighted images, and administration of both gadodiamide and sprodiamide improved the contrast on T1- and T2-weighted images. After 10 minutes of occlusion, no contrast was discernible before or after contrast material administration.

CONCLUSION

These results suggest that the detection of reperfused intestinal ischemia of sufficient duration to cause villous injury can be improved by using sprodiamide injection alone or in combination with gadodiamide.

[Quality control in pediatric radiology]

The authors recall the fundamentals of an adequate use of the X-rays considering to the ALARA (As Low As Reasonably Achievable) principle. The article deals more specifically with radiation protection and quality control in radiopediatrics, as this age group is essentially concerned with stochastic hazards, i.e. cancer induction and genetic injurious effects. The major elements of X-ray equipment are reviewed, including the X-ray generator, device, film-screen, radiogenic tube, automatic exposure device, and so on... The influence of technical parameters on dosimetry in terms of radiation protection as well as dosis variation, according to the type of disorder, are demonstrated. Reference is made to the radiologic techniques proposed by the Lake Starnberg Group.

Apparent focal bone marrow ischemia in patients with marrow disorders: MR studies

OBJECTIVE

We sought to assess with MR the focal bone marrow abnormalities in patients with chronic marrow disorders and acute limb pain.

MATERIALS AND METHODS

We investigated and followed with MRI four patients with proliferative or dysplastic marrow disorders presenting with acute but spontaneously resolving hip or thigh pain.

RESULTS

Ten focal marrow lesions were demonstrated on T2-weighted images as high signal intensity (SI) areas. They remained undetected on T1-weighted images as they showed a low SI similar to the disease-related low SI of the entire marrow. Postcontrast images demonstrated lack of enhancement in the lesions. Follow-up enhanced MR images showed intense enhancement within the lesions, while unenhanced MR images remained unchanged. Later on, these focal marrow abnormalities completely resolved. These lesions most likely represent bone marrow ischemia, although histological proof is lacking.

CONCLUSION

Acute bone pain in patients with bone marrow disorders may be related to focal marrow lesions suggestive of bone marrow ischemia.

Epiphyseal impaction as a cause of severe osteoarticular pain of lower limbs after renal transplantation

A syndrome of severe osteoarticular pain of lower limbs occurring early after renal transplantation (TP) has been recently identified. We describe its prevalence, clinical presentation and outcome. Symptomatic patients have been studied with conventional X-rays, magnetic resonance (MR) imaging, and 99mTechnetium scintigrams of the painful areas. Among 86 patients transplanted over a two-year period, nine (4 men, 5 women; mean age of 40.4 years; range 32 to 59) developed unexplained severe spontaneous osteoarticular pain of lower limbs 19 to 105 (mean 58) days after TP. Pain affected hip(s), knee(s), and/or ankle(s). Clinical examination was usually unremarkable. Favorable outcome was the rule; mean duration of pain was 86 (range 19 to 175) days. Radiographs were abnormal (joint swelling, patchy osteoporosis and/or periosteal reactions) in 41%, MR (epiphyseal fatty marrow replacement by edema and/or hemorrhages) in 83%, and bone scans (one to several epiphyseal foci of increased uptake) in 81% of the symptomatic examined areas. Among joints re-examined 9 to 12 months after resolution of the symptoms, X-rays showed periosteal reactions in 31%, and the bone scans disclosed persistent increased uptake in 53% of the joints, whereas epiphyseal MR abnormalities had completely disappeared in 86%. There was no difference in dialysis duration, post-TP weight gain, evidence of hyperparathyroidism, and steroid and cyclosporine doses between symptomatic and an appropriately selected group of asymptomatic patients. By contrast, serum alkaline phosphatase levels were transiently higher (at the onset of symptoms) in the symptomatic group.(ABSTRACT TRUNCATED AT 250 WORDS)

Intravertebral vacuum cleft: changes in content after supine positioning

Sequential radiographic and magnetic resonance (MR) imaging examinations were performed in nine patients with an intravertebral vacuum cleft indicative of avascular necrosis. Progressive changes in the content of the cleft occurred within an hour after the patients were placed in a supine position. Initially, the cleft showed a gaslike pattern during extension of the spine, with a radiolucent band on radiographs and a signal void on MR images. Later, the vacuum phenomenon disappeared on radiographs, and a fluidlike high-signal-intensity pattern appeared on T2- or T2*-weighted MR images, suggestive of a slow fluid inflow within the intravertebral cleft. Because the recognition of a vacuum cleft in a collapsed vertebral body helps avoid confusion with malignancy or infection, it is important to search for this in examinations performed immediately after supine positioning.