Lateral ankle ligaments: MR arthrography with anatomic correlation in cadavers

Objective

The purpose of our study was to use magnetic resonance (MR) imaging and MR arthrography to demonstrate the anatomy of the lateral ankle ligaments using standard and oblique imaging planes in cadavers.

Material and methods

MR imaging of ten cadaveric ankles was performed before and after intra-articular administration of contrast solution. Proton-density MR images were acquired in standard and oblique imaging planes. MR imaging was correlated with anatomic sections. Measurements using oblique imaging planes were obtained to characterize the morphology of the lateral ligaments.

Results

The anterior talofibular ligament (ATFL) had a variable number of bands in all specimens, separated by fat signal oriented obliquely parallel to the long axis of the ligament. The fibular attachment of ATFL was located in close proximity to the fibular attachment of the distal band of the anterior tibiofibular ligament (AITFL). The angle formed by the calcaneofibular ligament (CFL) and the fibular shaft varied with different ankle positions. Special axial oblique plane best demonstrated the CFL. The posterior talofibular ligament (PTFL) was multi-fasciculated in appearance. Dorsiflexion of the ankle joint helped elongate the PTFL and best depicted this ligament in its entirety in the axial plane.

Conclusion

Oblique imaging planes parallel to the long axis of the individual ligaments may improve visualization of the anatomy of the lateral ankle ligaments. The orientation of the lateral ankle ligaments is affected by the position of the talocrural and subtalar joints. Understanding the morphology of the lateral ankle ligaments can help radiologists diagnose abnormalities of these ligaments.     

Anterior diaphragm: variations in the CT appearance

The anterior portion of the diaphragm has three typical appearances on computed tomographic (CT) scans, depending on the cephalocaudal relation of the xiphoid to the central tendon of the diaphragm. The anterior diaphragm most often appears as a relatively smooth or slightly undulating soft-tissue curve, concave posteriorly and continuous across the midline with the lateral diaphragmatic arcs. In the next most frequent CT appearance, the diaphragmatic line is discontinuous in the midline. On each of these images, the muscular line diverges rather than converges as it approaches the anterior chest wall. Less commonly, the anterior portions of the diaphragm are imaged on CT not as a thin line but instead as a broad band with irregular, ill-defined, or angular margins. Occasionally, the anterior diaphragmatic muscle is not identified on CT because the muscle fibers are inseparable from adjacent structures, or are extremely short or even absent. An understanding of these anatomic variations permits the correct diagnosis of Morgagni hernias and explains previously described variants of plain radiographic configurations of pneumoperitoneum.     

Imaging of invasive thymoma in the costophrenic recess presenting as thickening of arcuate ligaments of the diaphragm

Imaging findings in a patient with invasive thymoma in the costophrenic recess are presented, in whom computed tomography (CT) and MRI revealed lateral arcuate ligament thickening. Increased fluoro-deoxy-glucose (FDG) uptake on subsequent positron emission tomography (PET)/CT was helpful in suggesting the correct diagnosis. A second patient with much more obvious invasive thymoma occurring in the costophrenic recess is presented for comparison. It is a well-known fact that thymic malignancies can metastasize to the pleura even years after resection. Rarely, they may present as focal thickening of the diaphragmatic lateral arcuate ligament.     

Sarcoidosis: abdominal manifestations at CT

There are few data in the literature on the abdominal manifestations of sarcoidosis at computed tomography (CT). To determine whether differences in nodal distribution and appearance can be reliably used to distinguish between sarcoidosis and non-Hodgkin lymphoma (NHL), the authors retrospectively reviewed the abdominal and pelvic CT scans of 16 patients with biopsy-proved sarcoidosis and 20 patients with biopsy-proved NHL. Eleven of the 16 patients with sarcoidosis had abdominal and/or pelvic lymphadenopathy, which was common at all nodal sites except for the retrocrural and pelvic locations. There was a statistically significant lower frequency of retrocrual adenopathy in sarcoidosis than in NHL. Mean nodal size was significantly greater in NHL. Nodes tended to be confluent in NHL and discrete in sarcoidosis. Hepatomegaly was seen in six of the 16 patients (38%) with sarcoidosis and splenomegaly was present in nine of 15 (60%). CT depicted hepatic lesions in only three of eight patients (38%) with biopsy-proved hepatic involvement. Splenic lesions were seen at CT in five of the 15 patients (33%). The authors believe that the overlap in nodal appearance and distribution poses a limitation for use of these criteria in accurate disease characterization.     

Neural foraminal ligaments of the lumbar spine: appearance at CT and MR imaging.

Axial and parasagittal computed tomographic (CT) scans and magnetic resonance (MR) images and exactly corresponding sections obtained with the freezing microtome in 18 human cadavers were examined to characterize the radiologic appearance of the lumbar neural forminal ligaments, which have been thought to contribute to nerve root compression. In the CT component of this study, 114 neural foramina at 57 spinal levels were studied; in the MR component, 27 neural foramina were studied. The ligaments originated from the posterolateral margin of the intervertebral disk and attached to the inferior pedicle, superior articular process, transverse process, or ligamentum flavum. On CT scans, they appeared as linear structures with higher attenuation coefficients than those of the adjacent fat and areolar tissue; on MR images, as linear structures with lower signal intensities than those of the adjacent fat and areolar tissue in the neural foramina. It is concluded that the ligaments in the neural foramen can be effectively depicted with CT or MR imaging.     

Pediatric blunt abdominal trauma: periportal tracking at CT.

Periportal zones of decreased attenuation at computed tomography (CT) have been described in a variety of disorders. In the setting of blunt abdominal trauma, the zones have been attributed to dissection of blood along the portal tracts. Because of the observation of isolated periportal tracking (PPT) in children after blunt trauma, the authors retrospectively reviewed CT scans of the abdomen obtained in 114 children to determine the frequency of PPT, liver injury, and peritoneal fluid. PPT was present in 22% of patients (25 of 114); it was associated with liver injury in 10 and was the only liver abnormality in 15. Pathologic correlation was available in two patients: In one it revealed marked periportal lymphedema and in the other, PPT of blood. This study indicates that both hemorrhage and lymphatic edema may be represented as PPT in children after blunt abdominal injury.     

Postoperative anatomic and pathologic findings at CT following gastrectomy.

Helical computed tomography (CT) is useful in identifying postoperative anatomic changes, complications, and tumor recurrence in gastric cancer patients who have undergone gastrectomy. Postoperative anatomic changes can usually be identified on consecutive CT scans. Complications include anastomotic leakage, duodenal stump leakage, intraabdominal bleeding, wound complications, and other less common complications (postoperative pancreatitis, retention of surgical foreign bodies, diffuse peritonitis). The degree and extent of bowel wall thickening is important in diagnosing tumor recurrence; however, CT lacks specificity. Large or conglomerated lymph node metastases can be easily diagnosed at CT; however, small solitary or focal metastases may not be detected or differentiated from nonmetastatic nodes. Ascites, a common finding with peritoneal seeding in gastrointestinal tumors, is well depicted at CT. Hematogenous metastases from gastric carcinoma are most frequently seen in the liver and are best demonstrated with helical CT performed during the portal venous phase of enhancement (sensitivity >90% for the detection of lesions >1 cm). The sophisticated surgical procedures used in gastrectomy can alter normal anatomy and make image interpretation difficult; thus, familiarity with the appearance of postoperative anatomic changes, complications, and tumor recurrence is essential for accurate CT evaluation of affected patients.     

Intertarsal ligaments: high resolution MRI and anatomic correlation

High resolution MRI was performed on four cadaveric foot specimens of human feet to demonstrate the ligaments of the tarsal joints. Spin echo T1 images were obtained using a local gradient coil that produces 6 G/cm and 100 A in all three axes. The best views for each of the individual ligaments were determined. High resolution MRI potentially can demonstrate most of the intertarsal ligaments.     

CT evaluation of pterygoid process pneumatization and the anatomic variations of related neural structures

Objective

This topic is concerned with the clarification of the radiological findings that should be reported as regard the anatomic variations of the neural structures related to the pterygoid process in patients listed for endoscopic sinus surgery.

Anterior chest wall: frequency of anatomic variations in children.

PURPOSE: To evaluate the frequency of anterior chest wall variations in children. MATERIALS AND METHODS: The computed tomographic (CT) images of 200 consecutive infants and children (114 boys and 86 girls; mean age, 10.5 years; age range, 3 months to 19 years) who underwent chest CT during a 20-month period were evaluated for chest wall variations. Children who had undergone chest wall surgery or were suspected of having a chest wall abnormality were excluded. The frequency of chest wall anomalies was compared with age and sex (Fisher exact test). RESULTS: The CT scans of 65 children (33%) depicted one or more variations in the anterior chest wall: titled sternum (n = 29), prominent convexity of anterior rib or costal cartilage (n = 19), prominent asymmetric costal cartilage (n = 20), well-defined paracostal subcutaneous nodule (n = 4), mild pectus excavatum (n = 4), or mild pectus carinatum (n = 4). The frequency of these findings did not vary significantly with age (P = .96) or sex (P = .36). CONCLUSION: Variations in the anterior chest wall are common, occurring in one-third of children, and should be considered normal. These asymptomatic variations should not be considered alarming when palpated at physical examination.     

Aging of the diaphragm: a CT study

To determine the normal morphologic evolution of the diaphragm with aging and to correlate age-related changes with other indicators of physical condition--such as skeletal muscle status, obesity, presence of pulmonary emphysema, and presence of esophageal hiatus hernia--a systematic morphometric and morphologic evaluation of computed tomographic studies of 120 patients from the 3d to 8th decades of life was undertaken. Diaphragm muscle thickness did not change significantly with increasing age. Diaphragmatic defects and pseudotumors, nonexistent in the 3d and 4th decades, increased in number and severity to affect 56% of the patients in the 7th and 8th decades. Neither the status of the skeletal muscle nor the presence of obesity correlated with age or with the presence of diaphragmatic defects. Eighty-four percent of the patients with emphysematous changes demonstrated diaphragmatic defects; thus, a strong association with emphysema was observed. If emphysematous patients are excluded, defects were more common in women. The esophageal hiatus width was found to increase with age.     

MRI上不同角度斜断面对踝关节外侧韧带显示效果的研究

目的:寻找踝关节外侧韧带于自然体位下MRI显示最佳的斜断面,为临床更好地评价外侧韧带提供依据。方法:解剖15例自然体位的正常踝关节标本,分离出外侧韧带,测出它们的长轴走行角度,据此制定MRI扫描方案;35例自愿者行踝关节MRI扫描,扫描方位包括常规横断面,冠状面及不同角度斜断面,比较不同扫描方位上各韧带的显示效果。结果:ATFL的显示以20°斜断面效果最佳,其次是横断面和30°斜断面,两者显示效果相当,45°斜断面次之。CFL的显示以-15°斜断面效果最佳,其次是-25°斜断面,横断面和-35°斜断面次之,但两者显示效果相当。CFL的整体显示率较ATFL低。冠状面对ATFL和CFL的显示不满意,但可满意显示PTFL。结论:MRI评价踝关节外侧韧带时,选择适当的扫描方位可以达到最佳的显示效果。     

The diaphragm: anatomic, pathologic, and radiologic considerations

The diaphragm, by virtue of its complex anatomy and multiple ligamentous connections to both thoracic and abdominal structures, is more than a simple partition between the chest and abdomen. Cross sectional images of the diaphragm and peridiaphragmatic processes can be confusing unless the radiologist is aware of the normal structure of the diaphragm, its attachments to the body wall, and the multiple ligaments that attach to the diaphragm.