Imaging of traumatic injury and impingement of anterior knee fat

Fat is not just used by the body as bulk tissue. In addition to its role in storing energy and regulating hormone action, fat is used in some parts of the body for its mechanical properties. The anatomy of anterior knee fat is more complex than it appears at first sight and is capable of withstanding considerable compressive and shear stress. Specific lesions occur when such mechanical stress exceeds the physiological limits and are yet little known. Superficial fat can be the site of either acute injury by closed degloving called the Morel-Lavallée lesion or chronic injury, when subject to repeat excessive shear forces, due to more complex and less well-defined disruptions that result in pseudo-bursitis. There are three main anterior, intracapsular and extrasynovial fat pads in the knee joint, which are the infrapatellar fat pad (IFP) or Hoffa's fat pad, the quadriceps fat pad and the prefemoral fat pad. The IFP plays an important role as a mechanical shock absorber and guides the patella tendon and even the patella itself during flexion-extension movements. In response to repeated excessive stress, an inflammatory reaction and swelling of the IFP is first observed, followed by a fibrotic reaction with metaplastic transformation into fibrous, cartilaginous or bone tissue. More rarely, the two other deep fat pads (quadriceps and prefemoral) can, if subject to repeated stress, undergo similar restructuring inflammatory reactions with metaplasia resulting in tissue hardening, anterior pain and partial loss of function.

[Evolution of the pelvis and hip throughout history: from primates to modern man]

The evolution to a bipedal mode of locomotion was accompanied by a verticalization of the spine and a modification in the shape of the pelvis: horizontal curvature and sagittal rotation. Phylogenesis meets ontogenesis: flat bones in fetuses similar to the monkey, australopithecus features at birth and "human-like" features by 7 or 8years of age. These anatomical modifications explain the characteristics of human bipedalism: stable, economical, with hip and knee extension in the standing position with little lateral motion. Some pathologies induce a regression to a more archaic mode of bipedal locomotion.

[Lumbar panniculitis with subcutaneous abscess revealing pyonephrosis]

BACKGROUND

A clinical picture of hypodermitis in the lumbar region may reveal an abscess arising from infection due to pyonephrosis. We report a case below.

CASE REPORT

A 58 year-old woman consulted for an area of inflammation in the left lumbar region that had been present for two months. The area of inflammation appeared two days after physiotherapy sessions prescribed for lower back pain. Laboratory examinations revealed inflammation associated with moderate renal failure. A skin biopsy sample taken from around the inflamed area showed septal hypodermitis. Ultrasound examination revealed a pocket of liquid measuring 7 x 2 x 2 cm; Proteus mirabilis was isolated following ultrasound-guided needle aspiration,. Magnetic resonance imaging (MRI) and uroscan revealed pyonephrosis with suffusion into the hypodermis and left lumbar fossa.

DISCUSSION

This was a case of bacterial hypodermitis with abscesses secondary to pyonephrosis. Pyonephrosis may be transferred to the skin, causing fistulas and subcutaneous pus collection. In such rare and potentially misleading clinical settings, the diagnosis can be established by imaging.

[Strict anteroposterior radiography of the shoulder: value of the assessment of rotator cuff tears]

PURPOSE

To compare the contribution of various radiographic projections in the evaluation of impingement syndrome and rotator cuff tears. Materials and method. We realized a prospective study in 53 patients with suspected rotator cuff tear, evaluated by plain radiographs and arthrography (gold standard). 31 patients were men and 22 were women (mean age 51 years). In all patients, anteroposterior radiograph, strict anteroposterior straight-beam decubitus view and anteroposterior radiograph during Leclercq's maneuver of the affected shoulder were obtained. The population was divided into three groups: group 1: normal arthrography (n=19), group 2: isolated supraspinatus tendon tear (n=23), group 3: rupture of the supraspinatus and infraspinatus tendons (n=11). The acromio-humeral space was measured on all these views and differences between the three groups were statistically analyzed.

RESULTS

There is a significant statistical difference between the height of the acromio-humeral space found in patients with isolated tear of the supraspinatus tendon and those with a tear extending to the infraspinatus tendon (p=0.0001). The ROC methodology showed a better accuracy of the strict anteroposterior straight-beam decubitus view in cases of wide ruptures of the rotator cuff, and this for a selected threshold value of 6 mm.

CONCLUSION

Strict anteroposterior straight-beam decubitus view, seems to be easy to realize, cheap, reproducible and very powerful in the preoperative assessment of patients with suspected rotator cuff tendon tear. It allows an excellent visualization of the acromioclavicular joint.

[HASTE sequence and cine-MRI evaluation of the cervical spinal canal: evaluation in 11 healthy subjects]

PURPOSE

We studied 11 healthy subjects were evaluated using cine MR imaging comparing HASTE and gradient echo sequences. Materials and methods :HASTE is a high-speed turbo-spin echo T2-weighted sequence. All examinations were performed using dynamic MRI using a simple process allowing acquisition of images at different stages during flexion and extension. The cine MR evaluation was obtained by rebuilding a cine-loop sequence.

RESULTS

HASTE sequence provides a myelographic effect of the cervical spine. The size, the pattern and the movements of the cervical spine, the spinal cord, as well as the functional reserve of cerebro-spinal fluid are analysable.

CONCLUSION

Because of its very high speed, HASTE sequence is particularly useful for cine MR imaging.

Imaging of diffuse esophageal leiomyomatosis: two case reports and review of the literature

Diffuse esophageal leiomyomatosis is a rare disorder which may be found in association with leiomyomas in other locations or with other disorders. We report two cases in men, one with associated tracheobronchial involvement, which illustrate the value of imaging in differentiating this entity from other causes of dysphagia and in establishing a diagnosis.

Is capsular retraction a specific CT sign of malignant liver tumor?

The aim of this study was to assess if a liver capsular retraction is a specific CT sign in malignant hepatic tumors. The authors reviewed retrospectively 320 hepatic CT scans obtained in 300 patients during a 3-year period. These patients presented with benign (n = 64) or malignant (n = 236) hepatic tumors. In 7 patients we found retraction of the capsule surrounding the tumor. All these tumors were histologically proven as malignant lesions: 4 metastases (none being chemically treated), 2 peripheral cholangiocarcinomas, and 1 epithelioid hemangioendothelioma. The prevalence of this sign was 2.18% (7 of 320) in this series. This capsular retraction pattern has never been found in hepato-cellular carcinomas (no fibrolamellar in this series) and benign lesions. Liver capsular retraction is an uncommon but specific (100%) sign in malignant hepatic tumors; however, a larger and prospective series is needed.

Osteoid osteoma: CT-guided percutaneous resection and follow-up in 38 patients

PURPOSE

To reevaluate at medium term the results of computed tomography (CT)-guided percutaneous resection of osteoid osteomas.

MATERIALS AND METHODS

Thirty-eight patients who had undergone treatment by means of this technique were reexamined with a mean follow-up of 3.7 years. The short- and medium-term clinical course and histologic features of the resection specimens were analyzed.

RESULTS

The bone fragment could be analyzed in all cases, and the diagnosis of osteoid osteoma was confirmed in 28 patients (74%). A different diagnosis was made in six patients: mucoid cyst, subchondral arthritic geode, fibrous dysplastic lesion, focal osteochondritis, or focal chronic osteomyelitis. Cure was obtained in 32 patients (84%), whatever the cause. Complications, generally minor and transient, were observed in nine patients (24%). The most severe complications were two femoral fractures and one focal chronic osteomyelitis due to Staphylococcus aureus infection.

CONCLUSION

The results of this study confirm the efficacy of percutaneous resection of osteoid osteomas and the possibility of using this method for successful treatment of other small bone lesions.

[Percutaneous resection under computed tomography guidance of osteoid osteoma. Mid-term follow-up of 38 cases]

PURPOSE

To evaluate the mid-term outcome following CT-guided percutaneous resection of osteoid osteoma.

MATERIALS AND METHODS

38 patients who had been treated by CT-guided percutaneous resection were included. The mean follow-up of 3.7 years. Early and mid-term outcome and histology were analyzed.

RESULTS

Histological samples were adequate in 92% of cases and a diagnosis of osteoid osteoma was confirmed in 73.7% of cases. In 6 cases, the lesion was not an osteoid osteoma: 2 mucoid cysts, 1 benign fibrous dysplasia, 1 fibromucoid lesion, 1 focal osteochondritis, 1 osteomyelitis. Cure was achieved in 84.2% of patients. Minor transient complications occurred in 23.7% of cases. The most serious complications included: 1 intramuscular hematoma, 2 femoral fractures, and 1 case of S. aureus osteomyelitis.

CONCLUSION

This study confirms that CT-guided percutaneous resection of osteoid osteomas is effective and shows that other small lesions can also be treated using this technique.

[Biliary colonic ileus: an unusual cause of colonic obstruction]

We report a rare case of colonic gallstone obstruction in a patient with cholecystocolic fistula. Diagnosis of this condition is usually difficult and only achieved at surgery. We review the radiological findings, particularly the CT findings, helpful for diagnosis: ectopic gallstone, biliary gas and fistula. Early preoperative diagnosis could reduce morbidity and mortality. Treatment is surgical with enterolithotomy. There is some controversy over the need to repair the fistula.

[Synovial sarcoma localized in the muscles]

We report three cases of synovial sarcoma strictly located in the muscles. Synovial sarcoma generally arises in the vicinity of joints, tendon sheaths, bursae, fascia, and ligaments. Strictly intramuscular locations are not well known and not described in the literature to our knowledge although they seem to be frequent. The different characteristics on the radiographic examinations are non specific, and this location may be misleading. MRI is considered the procedure of choice for staging this tumor and to visualize soft tissues and bone invasion. CT scans may be useful in detecting more specific small calcifications.

[Intramuscular hemangioma. Contribution of MRI]

The authors report one case of a relatively common benign tumor, hemangioma, although in an uncommon location, intra-muscular. The radiological exploration, principally MR imaging has a great interest to specify the diagnosis and the regional extension. Intramuscular hemangioma appears with a relatively low signal intensity on T1-weighted images, but demonstrates a clear delineation of the extent of the lesion on T2-weighted images, because of high contrast between hemangiomas and surrounding muscle. The informations obtained with MR imaging may be valuable clinically in planning surgical resection.

Kinematic MR imaging of the shoulder: normal patterns

OBJECTIVE

We performed this study to define the normal patterns of the glenohumeral joint with kinematic MR imaging in healthy volunteers.

SUBJECTS AND METHODS

Twenty healthy volunteers (39 shoulders) were studied with a 1.5-T imager. Successive fast low-angle shot images (75/11 [TR/TE], 15 degrees flip angle) were obtained in the axial plane from full internal to full external rotation at the superior, middle, and inferior glenoid levels.

RESULTS

The free margin of the anterior labrum was seen to be slightly mobile and its base was always fixed. The anterior labrum showed changes in shape and signal intensity during internal rotation (54%). The posterior labrum remained motionless in 97% of patients and no shape or signal-intensity changes were noted during internal rotation. The anterior joint capsule was taut during external and internal rotation, exhibited a slack pattern in 51% of patients, and a folded pattern in 14% of patients.

CONCLUSION

Kinematic MR imaging, which permits dynamic evaluation of the various anatomic components that may be involved in shoulder instability, also provides information on the labrocapsular ligamentous complex.

[Cine-MRI of the shoulder. Normal aspects]

PURPOSE

To define the normal patterns of gleno-humeral joint, with kinematic MR imaging in asymptomatic volunteers.

MATERIAL AND METHOD

Twenty asymptomatic volunteers (39 shoulders) were studied with a 1.5 Tesla imager. Successive acquisitions Flash (99, 18, 15 degrees) were obtained in the axial plane, from full internal to full external rotation, at the superior, mid and inferior glenoid level.

RESULTS

Free edge of the anterior labrum was noted slightly mobile, its base was always immobile. The anterior labrum exhibited modification of shape and increased signal intensity in internal rotation (54%). The posterior labrum remained motionless in 97% and neither shape or signal intensity changes were noted in internal rotation. Inferior labro-capsular ligamentous complex was visualised in all cases. The anterior capsular joint was taut in external rotation and exhibited a slack (51%) or folded (13.5%) pattern during internal rotation.

CONCLUSION

Kinematic MR imaging allows a dynamic assessment of the different anatomic components which may be implicated in shoulder instability. It provides information about the labro-capsular ligamentous complex.