Evaluation of posterior tibial pathology: comparison of sonography and MR imaging

Objective To compare the results of sonographic (US) and magnetic resonance (MR) imaging in detecting pathology of the posterior tibial tendon (PTT) in patients with PTT dysfunction.Design Twenty-two ankles that were clinically suspected by the orthopedic surgeon to have PTT dysfunction were evaluated with US (10 MHz linear-array transducer) and 1.5 T MR examinations within the same day. The US and MR studies were conducted and interpreted by two sonologists and two musculoskeletal radiologists who were masked to the results of the other study. Four patients had bilateral studies. Classic clinical findings were utilized as a standard reference in staging PTT dysfunction.Patients Eighteen women (mean age 61 years, age range 3986 years).Results Based on a commonly accepted staging system for PTT dysfunction, 6 ankles were classified as stage I, 11 ankles as stage II, and 5 ankles as stage III. All stage I ankles were interpreted as having an intact PTT by both MR imaging and US. In the stage II and III tendons, MR imaging demonstrated PTT tears in 12 of 22 examinations, including 11 partial tears and 1 complete tear. US demonstrated PTT tears in 8 of 22 examinations, including 8 partial tears and no complete tears. The findings of US and MR imaging were consistent in 17 of 22 cases (77%). The five inconsistencies were as follows: in 4 cases, US reported tendinosis when MR imaging interpreted partial tears (no change in management); in one case, US diagnosed a partial tear when MR reported a complete tear of the PTT (no change in management because the clinical findings were more consistent with a partial tear).Conclusions In this study, US and MR imaging of the PTT were concordant in the majority of cases. US was slightly less sensitive than MR imaging for PTT pathology, but these discrepancies did not affect clinical management.     

Sonography of occult dysraphism in neonates and infants with MR imaging correlation.

High-resolution spinal sonography has become an accepted study to screen for occult dysraphic lesions (ODLs) in neonates and infants. These defects are thought to be caused by abnormal fusion or closure of embryonic dorsal midline structures. Sonographic findings suggestive of an ODL include low position of the conus, nontapered bulbous appearance of the conus, dorsal location of the cord within the bony canal, solid or cystic masses in the distal canal or soft tissue of the back extending toward the canal, patulous distal thecal sac, and thick filum. Physical findings suggestive of ODLs include lumbosacral skin dimples, lumbosacral masses, lower extremity weakness, and an extra appendage arising from the back. The appearances of a normal infant spine, dorsal dermal sinus, lipoma, lipomyelomeningocele, lipomyelocele, myelocystocele, and diastematomyelia are depicted sonographically and correlate with those on magnetic resonance (MR) images. MR imaging is most useful when sonographic findings are abnormal or equivocal or when normal skeletal maturation limits sonographic visualization of the intracanalicular contents.     

MR imaging of posterior mediastinal thymus

The diagnosis of posterior mediastinal extension of thymus was made by magnetic resonance imaging, which showed (a) continuity of the normally placed thymus with a posterior mediastinal mass, (b) identical signal characteristics between the anterior and posterior components, (c) homogeneous signal intensity greater than muscle and less than fat on T1- and moderately T2-weighted images which is characteristic of thymic tissue, and (d) characteristic posterior extension of the thymus between the superior vena cava and trachea.     

MR imaging findings of medial tibial crest friction

Objective

Medial tibial condyle bone marrow edema (BME), associated with soft tissue edema (STe) surrounding the medial collateral ligament, was incidentally observed in MRI examinations of young and athletic individuals. The aim of the present study was to 1. Prospectively investigate the association between these findings and coexistence of localized pain, and 2. Explore the possible contribution of the tibial morphology to its pathogenesis.

Methods

The medial tibial condyle crest was evaluated in 632 knee MRI examinations. The angle and depth were measured by two separate evaluators. The presence of STe and BME was recorded. A third evaluator blindly assessed the presence of pain at this site.

Results

BME associated with STe was found in 24 patients (with no history of previous trauma, osteoarthritis, tumor or pes anserine bursitis). The mean crest angle was 151.3° (95%CI 147.4–155.3°) compared to 159.4° (95%CI 158.8–160°) in controls (Mann–Whitney test, P < 0.0001). MRI findings were highly predictive of localized pain (sensitivity 92% specificity 99%, Fisher's exact test, P < 0.0001).

Conclusion

Friction at the medial tibial condyle crest is a painful syndrome. MRI is a highly specific and sensitive imaging modality for its diagnosis.     

Association of posterior tibial tendon abnormalities with abnormal signal intensity in the sinus tarsi on MR imaging

Objective. To evaluate the association of abnormal signal intensity within the sinus tarsi with abnormalities of the posterior tibial tendon (PTT) on MR imaging. Design and patients. Sinus tarsi abnormalities were identified on 30 ankle MR examinations in 29 patients. The PTT and anterior talofibular ligament were retrospectively analyzed for abnormalities in these same patients. Results and conclusions. Tears of the anterior talofibular ligament were found in 13 of 30 (43%) ankles. PTT abnormalities (complete tear, partial tear or dislocation) were seen in 14 of 30 (47%) studies, and were distributed relatively equally between those patients with and without lateral ligament tears. Our results provide evidence of an association between abnormalities of the PTT and the sinus tarsi. The finding of abnormal signal intensity within the sinus tarsi on MR imaging should alert the radiologist to potential abnormalities of the PTT. Received: 17 March 2000 Accepted: 17 May 2000     

MR imaging of posterior cruciate ligament injuries

Posterior cruciate ligament(PCL) injuries are less frequent than anterior cruciate ligament(ACL) injuries, but are presumably more common than once thought. Thirty-nine patients with PCL injuries identified on MR images were studied. The criteria for PCL injury were complete tear, partial tear, and avulsion fracture. The approximate site of a partial tear was categorized as proximal, midsubstance, distal, or combination. Fourteen patients(35.9%) had complete tears of the PCL, 21 patients(53.8%) had partial tears, and four patients(10.3%) had avulsion fractures. A total of 12 patients (30.7%) had isolated PCL injuries, while the remaining 27 patients demonstrated evidence of other coexistent knee injuries, such as meniscal tears and ligamentous injuries. Of coexistent knee injuries, meniscal tears(18 patients, 46.2%) were most often seen.     

7.0T钠元素MR成像在阿基里斯跟腱炎临床诊断的初步应用

目的为了研究钠元素MR成像诊断阿基里斯跟腱炎的可行性。材料与方法该研究获得医学伦理委员会批准,研究对象为签署知情同意书的20名健康志愿者和8例阿基里斯跟腱炎病人。使用7.0T全身MR扫描设备,15通道钠元素膝部线圈。不仅获得MR影像中跟腱的信噪比(SNR),而     

Anterior tibial tendon abnormalities: MR imaging findings

PURPOSE: To retrospectively evaluate the magnetic resonance (MR) imaging findings of anterior tibial tendon (ATT) abnormalities. MATERIALS AND METHODS: Institutional review board approval was not necessary for review of patient images and was granted for examination of the volunteers; informed consent was obtained. MR imaging findings in 28 consecutive patients (20 women, eight men; mean age, 63.2 years) clinically suspected of having an ATT abnormality were compared with those in an age- and sex-matched control group of 28 asymptomatic volunteers (20 women, eight men; mean age, 62.9 years). Surgical correlation was available for 11 patients. The short-axis diameter of the ATT and the longitudinal extent of signal intensity abnormalities were measured (Mann-Whitney U test). Signal intensity abnormalities of the ATT and irregularities of the underlying tarsal bones were analyzed in consensus by two blinded radiologists (chi2 test). RESULTS: In the symptomatic group, three cases of tendinosis and 13 partial and 12 complete ATT tears were diagnosed. In 11 cases (one case of tendinosis and two cases of partial and eight cases of complete ATT tear), surgical correlation was available and the MR imaging diagnosis was confirmed. In the asymptomatic group, four cases of tendinosis of the ATT were seen. The ATT diameter was significantly thicker in symptomatic patients at 1 cm (5.1 vs 3.1 mm in control group, P < .001), 3 cm (5.8 vs 3.4 mm, P < .001), and 6 cm (5.4 vs 4.3 mm, P = .006) proximal to the distal point of insertion. Most ATT abnormalities (in 23 [82%] of 28 patients) were located within the first 3 cm proximal to the insertion. Signal intensity abnormalities were seen in the anterior portion of the ATT in two (7%) of the 28 symptomatic patients and in the posterior portion in 11 (39%); diffuse involvement was seen in 15 (54%). Bone spurs on the navicular surface (nine [32%] patients vs no [0%] control subjects, P = .001), a ridged shape of the medial surface of the medial cuneiform bone (13 [46%] vs one [4%], P < .001), and osteophyte formation at the first tarsometasarsal joint (eight [29%] vs two [7%], P = .036) were significantly more common in the symptomatic patient group. CONCLUSION: Characteristic findings of ATT abnormalities include tendon thickening (> or =5 mm) and diffuse or posterior signal intensity abnormalities of the tendon within 3 cm from the distal point of insertion.     

Sonography and MR imaging of bifid median nerve with anatomic and histologic correlation

OBJECTIVE: Imaging of a bifid median nerve has not been previously described in the radiology literature. We present three cases of bifid median nerve. The first is a patient with carpal tunnel syndrome seen on sonography and confirmed at surgery. The other two were found among 10 cadaveric specimens and were imaged with sonography and MR imaging. Confirmation of bifid median nerve in these two specimens was obtained using anatomic and histologic correlation. CONCLUSION: Sonography and MR imaging can allow effective diagnosis and delineation of a bifid median nerve in the wrist. This diagnosis is important to make before carpal tunnel release or other wrist surgeries are performed to avoid nerve injury. Furthermore, the sonographic size criteria for diagnosing carpal tunnel syndrome in nonbifid median nerves may not be accurate in evaluating bifid median nerves.     

MR imaging of the posterior hypophysis in children

The posterior lobe of the pituitary gland was studied by MR imaging in 30 children without pituitary gland disease and compared with studies from a group of 13 children with central diabetes insipidus, including eight cases of primary diabetes insipidus and five cases of diabetes insipidus secondary to suprasellar tumors (four proved germinomas, one still unknown tumor). Two components in the sella turcica were identified in all 30 children without pituitary gland disease, and the posterior lobe was identified as a high-intensity structure on T1-weighted images. In all 13 patients with diabetes insipidus, the normal hyperintense signal of the posterior hypophysis was absent on T1-weighted images. Three patients with suprasellar tumors presented with a progressively enlarging pituitary stalk on follow-up. Our findings show that absence of the normal hyperintense signal of the posterior lobe is closely related to a loss of function of the neurohypophysis. Size or signal modification of the pituitary stalk should suggest the development of a suprasellar tumor.     

MR imaging of the posterior fossa structures of human embryos and fetuses.

There have been few reports on MR imaging of the developing human fetal brain. The aim of this article is to establish a standard atlas of developing fetal brain, focusing in particular on posterior fossa structures. Eighty-eight formalin-fixed embryos and fetuses were examined using 1.5 Tesla MR units. Specimens ranged from Carnegie stage 17 to 28 gestational weeks. The morphologic changes in developing cerebellum, cerebellar fissures, pontine flexure, fourth ventricle, and cerebral aqueduct were observed in each developmental period. The height of the fourth ventricle and cerebral aqueduct and the thickness of the tectum and the tegmentum of the midbrain were measured. We obtained detailed MR images of the developmental changes in posterior fossa structures and produced an atlas of these images. Our study showed that the period of visualization of cerebellar structures and fissures was later on MR imaging than described in past anatomical and embryological studies. In addition, the sudden decrease in height of the fourth ventricle and the cerebral aqueduct found in our study might reflect the presence of communication between the fourth ventricle and subarachnoid space.     

MMP‐8 polymorphism is genetic marker to tendinopathy primary posterior tibial tendon

Posterior tibial tendon is particularly vulnerable and is responsible for much morbidity in sportspersons. Some patients have a predisposition without a clinically recognized cause, suggesting that individual characteristics, inclusive genetic inheritance, play an important role in tendinopathy. Matrix metalloproteinase (MMP)‐8 is a proteinase capable of degrading a large amount of extracellular proteins, and influence degradation and remodeling of collagen. To determine whether the ?799 polymorphism in the promoter of MMP‐8 gene is associated with tendinopathy in posterior tibial tendon, 50 patients undergoing surgical procedures and anatomopathological diagnosis of degenerative lesions of the posterior tibial tendon and 100 control patients with posterior tibial tendon integrity and without signs of degeneration in magnetic resonance imaging were evaluated for the ?799 MMP‐8 polymorphism. There was a significant difference in the presence of the different alleles (P = 0.001) and genotype (P = 0.003) between the control group and the test group for the MMP‐8 gene. The polymorphism at position ?799 of the gene for MMP‐8 is associated with tendinopathy primary posterior tibial tendon in the population studied. The results suggest that individuals with the T allele are at greater risk of developing tendinopathy.     

MR imaging of posterior fossa infarctions: vascular territories and clinical correlates.

Ischemic infarctions in certain vascular territories of the cerebellum and brain stem can produce some characteristic radiologic and clinical patterns. The cerebellum serves as a coordination center for the maintenance of equilibrium and muscle tone and refines the movements of the somatic muscles. The anatomy of the brain stem is extremely complex, and small infarcts can potentially be disastrous. MR imaging depicts the anatomy of the posterior fossa and infarcts in this region with greater accuracy than was previously possible. Familiarity with the vascular territories and patterns of infarction of the posterior fossa depicted with MR imaging and familiarity with the associated clinical symptoms of stroke in this region can help the radiologist recognize these infarcts and correlate clinical and radiologic findings. When patients are referred for MR imaging of the brain because of clinical findings suggestive of infarction, it may be useful to obtain coronal or sagittal views in addition to axial images to better depict the vascular distribution of a suspected ischemic lesion.     

Normal and degenerative posterior spinal structures: MR imaging

A retrospective study of the magnetic resonance (MR) images of the lumbar spines of 13 healthy subjects and 30 patients with degenerative changes was done. In the healthy subjects, the vertebral facets, thickness of the cartilage and ligamentum flavum, signal characteristics of the bone marrow, and size of the spinal canal were studied. In the patients with degenerative changes in one of these structures, MR images in the sagittal plane were useful in demonstrating hypertrophy of the ligamentum flavum or the vertebral facets, in grading the degree of foraminal stenosis, and in measuring the sagittal diameter of the spinal cord. MR images in the axial plane facilitated detailed analysis of the facet joint and more accurate measurements of the thickness of the ligamentum flavum and spinal canal diameter. MR images were compared with computed tomography scans in 12 patients.