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。     

Central pseudodefect of the talus: a potential ankle MR interpretation pitfall.

PURPOSE: The purpose of our study was to outline the MR features of the central pseudodefect of the talus (a normal finding that can simulate an osteochondral lesion on ankle MR studies), assess the prevalence of the central pseudodefect of the talus, and provide insight into the origin of this misleading MR appearance. METHOD: We retrospectively evaluated 31 ankle MR studies in 10 asymptomatic volunteers and 21 consecutive patients for the presence of the central pseudodefect of the talus. None of the patients had a history of trauma to the ankle. The signal, size, and shape of the pseudodefect were documented in each patient. The sagittal images were cross-referenced with the axial and coronal images in all patients in whom the central pseudodefect was identified. RESULTS: Six volunteers (60%) and 13 patients (62%) showed a curvilinear band in the middle third of the talus on far medial sagittal images, consistent with the central pseudodefect of the talus. The band measured 8-15 x 3-8 mm (mean 11 x 4 mm) and was hypointense on T1 and STIR pulse sequences. In two cases, the pseudodefect was subchondral; in the rest, it was found a few millimeters below the articular surface. On cross-referenced axial and coronal images, the band corresponded to the talar insertion site of the deep tibiotalar fibers of the deltoid ligament. CONCLUSION: The central pseudodefect of the talus is a common finding that is produced by the insertion of the tibiotalar fibers of the deltoid ligament into the talus. Familiarity with its appearance is necessary to avoid misinterpreting it as an osteochondral lesion of the talus.     

MR imaging of the normal shoulder: anatomic correlation

The complex anatomy and the requirement to image in the peripheral magnetic field have made the shoulder difficult to examine with MR. However, the use of high-resolution scanning techniques and specialized surface coils has improved the quality of MR images obtained. Seventy-five scans of the shoulders of normal volunteers were correlated with multiplanar cryomicrosections of six cadaver shoulders to study the MR appearance of normal structures. MR was shown to provide excellent depiction of shoulder anatomy.     

Uterine contractions: Possible diagnostic pitfall at MR imaging

A total of 206 nongravid patients with various gynecologic problems underwent pelvic magnetic resonance (MR) examinations that included both sagittal T2-weighted and contrast agent–enhanced T1-weighted images. MR images were retrospectively reviewed to identify changes in endometrial configuration on serial images obtained during the same MR examination. In 20 MR examinations (all in women of reproductive age), endometrial distortion due to myometrial bulging was noted on T2-weighted or contrast-enhanced T1-weighted images. It was absent on other MR images obtained at different times. Myometrial bulging exhibited low signal intensity in 18 examinations. The finding resembled adenomyosis or leiomyoma on T2-weighted or contrast-enhanced T1-weighted images. These results evidence the presence of transient myometrial bulging and transient low-intensity myometrium in the nongravid uterus. This phenomenon is thought to represent uterine contraction. Clinicians should be aware of the potential presence of transient low-signal-intensity myometrial bulging that could present diagnostic problems in the normal uterus.     

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.     

Trigeminal nerve: anatomic correlation with MR imaging

Through correlation with cryomicrotic sections, the appearance of the trigeminal nerve and its branches on magnetic resonance images is described in healthy individuals and in patients with tumors involving this nerve. Coronal images are best for defining the different parts of the nerve and for making a side-to-side comparison. Sagittal images are useful to demonstrate tumors involving the gasserian ganglion.     

Thoracic outlet: anatomic correlation with MR imaging

OBJECTIVE: The purpose of this report is to describe the normal MR anatomy of the thoracic outlet and its modification after postural maneuvers using an anatomic-MR imaging correlation. CONCLUSION: MR imaging appears to be a useful technique to study the thoracic outlet and its contents because of its excellent soft-tissue depiction and its multiplanar capabilities. T1-weighted images obtained in the sagittal plane clearly depicted the different compartments of the cervicothoracic-brachial junction. Hyperabduction maneuvers may have potential applications in the assessment of the thoracic outlet syndrome by showing the location of compression.     

The ankle meter: an instrument for evaluation of anterior talar drawer in ankle sprain

The aim of this study was to work out a clinical test which is possible to measure the anterior talar drawer (ATD) in patients after ankle sprain. The instrument for evaluation was called ankle meter. The instrument consists of two plastic scales (heal scale and tibia scale). The instrument allows quantifying the results of the anterior drawing test. A total of 38 persons (16 men, 22 women) were available as control group. The persons were 28.8±10.1 years old. No proband had any ankle problems in his history. A total of 45 patients (25 males, 20 females) suffering from ankle sprain were included in the study. In these patients stress radiography (147.1 N) was performed to measure the ATD. In control group the clinical measured ATD was 1.7±1.3 mm. Measurement for detect the interobserver validity did not detect significant differences. The ATD of the joint after ankle sprain was significantly higher (8.9±4.3 mm). The difference between healthy and injured ankle in case of an ankle sprain was 7.4±4.2 mm. There was a significant correlation between clinical and radiological measured ATD (R=0.91). The results suggest that it is possible to measure the ATD exactly. The values of the clinical ATD measurement showed a good correlation with the results of stress radiography. Diligent clinical examination in combination with this special test are after this experiences sufficient to classify the severity of injury after ankle sprain.     

Arthroscopic treatment of transchondral talar dome fractures

Fifteen cases of transchondral talar dome fractures treated arthroscopically at the Naval Hospital in Oakland, California, were reviewed. Roentgenograms and results from clinical examination were assessed preoperatively and at regular intervals postoperatively. Clinical followup of 18 months was obtained in all cases (range, 18 to 36 months; mean, 26 months). All lesions were treated with arthroscopic excision of fragments with abrasion and/or drilling of the remaining crater. There were nine excellent results, four good, one fair, and one poor. There were no complications. Results of arthroscopic treatment compare favorably to those of open arthrotomy.     

"Pseudocoarctation" of the aorta: pitfall on cine MR imaging

The diagnosis of coarctation of the aorta on cine magnetic resonance imaging is based upon observation of localized narrowing in the region of the aortic isthmus with jet-like signal void areas extending distally. We observed similar findings in 8 of 20 (40%) normal volunteers examined in the sagittal oblique view. These artifactual findings relate primarily to out-of-plane motion of the thoracic aorta during a portion of the cardiac cycle, leading to partial volume averaging with pulmonary air. Awareness of this pitfall will prevent misdiagnosis of aortic coarctation in normal subjects and allow for more accurate assessment of severity of true coarctation.     

Collateral ligaments of the ankle: high-resolution MR imaging with a local gradient coil and anatomic correlation in cadavers.

Findings at high-resolution magnetic resonance (MR) imaging of the lateral and medial collateral ligaments of the ankle were compared with findings in anatomic sections from cadavers. MR imaging of six cadaveric feet was performed with a newly developed local gradient coil and axial and coronal T1-weighted spin-echo sequences. Axial imaging provided optimum views of the anterior and posterior talofibular ligaments, the deep layers of the medial collateral ligament, and the tibionavicular ligament. Coronal imaging allowed complete visualization of the calcaneofibular, posterior talofibular, tibiocalcaneal, and posterior tibiotalar ligaments. In both imaging planes, differentiation of the deep and superficial layers of the medial collateral ligament was possible. Differentiation between the syndesmotic complex and the lateral collateral ligament was accomplished easily; in particular, differentiation of the posterior tibiofibular ligament from the posterior talofibular ligament was not difficult because of the differing insertions of these ligaments. The inhomogeneous appearance of the medial collateral ligament and the posterior talofibular ligament on MR images correlated with areas of fatty tissue on corresponding microscopic sections. High-resolution MR imaging with a newly developed local gradient coil allows excellent visualization of the lateral and medial collateral ligaments of the ankle.     

High-resolution MR imaging of talar osteochondral lesions with new classification

Purpose  

Retrospective review of high-resolution MR imaging features of talar dome osteochondral lesions and development of new classification system based on these features.     

Retrograde drilling for osteochondral lesions of the talar dome

BACKGROUND: For the treatment of osteochondral lesions of the talar dome without detachment of the cartilage, there is little information on whether transmalleolar drilling or retrograde drilling is more effective in terms of clinical and morphologic evaluations. HYPOTHESIS: Retrograde drilling may be more effective than transmalleolar drilling for lesions without cartilage detachment. STUDY DESIGN: Case control study; Level of evidence, 3. METHODS: Subjects were 30 patients with lesions on 1 foot of grade 0 or I, determined according to a modified Pritsch classification system. Nineteen patients underwent transmalleolar drilling (TMD group), and 11 patients underwent retrograde drilling (RD group). Ankle arthroscopy was performed 1 year postoperatively to evaluate cartilage conditions. RESULTS: Arthroscopic findings revealed that in the TMD group, 11 lesions (57.9%) were unchanged (grade I), and 8 lesions (42.1%) had deteriorated from grade 0 to I; in the RD group, 3 lesions (27.2%) had improved from grade I to 0, and 8 (72.8%) were unchanged (2 grade 0 lesions and 6 grade I lesions). There was a significant difference between the 2 groups in the distribution of cases that had improved, were unchanged, or had deteriorated (P < .0001). CONCLUSIONS: This study showed that compared with transmalleolar drilling, retrograde drilling for osteochondral lesions of the talar dome can improve the arthroscopic assessment of the lesions.