MR Imaging of Tibial Stress Fractures

脛骨應力性骨折的磁振造影影像表徵

陳欣琪(Hsin-Chi Chen) ； 施庭芳(Tiffany Ting-Fang Shih) ； 黃國茂(Kou-Mou Huang) ； 李瑤華(Yiu-Wah Li)

《中華放射線醫學雜誌》 24卷2期 (1999/04) Pp. 51-56

摘要

脛骨是年輕人最容易發生應力性骨折的所在，我們以高磁場磁振造影檢查7個脛骨的應力性骨折（病人於感到疼痛後3周到12個月內來作檢查）。我們將這7個病灶依其發生部位分為二群，第一群包括4個發生在幹髓端髓質骨的應力骨折，第二群包括3個發生在骨幹處皮質骨的應力骨折。第一群中所有4個髓質骨的應力骨折，其磁振造影影像均可見髓腔內有一條極低訊號的不規則線，其走向與骨小樑垂直，而與骨皮質相連接。包圍在此線周圍的骨髓腔區域，也有不正常的T1影像低訊號，T2影像高訊號表現。這4個骨折病灶中，有一例有接受靜脈顯影劑注射，發現圍繞在這極低訊號線條旁的骨髓腔，有顯影加強現象。這4個骨折病灶中，也只有這個病灶，可觀察到骨折線旁有不正常的骨膜下新月形區域，此區域呈現T1影像低訊號，T2影像高訊號，且有顯影加強現象。而第二群的所有3個皮質骨的應力骨折，其磁振造影影像均可見梭狀或橢圓形狀的皮質增厚，但不併有骨髓腔內不正常訊號。此外，所有這3病灶也均可見骨折線旁有T2影像高訊號的骨膜下新月形區域。此3例中有2例，並可見到增厚的骨皮質內有水平裂縫，此2例於接受靜脈顯影劑注射後，可見到圍繞在裂縫周圍的骨皮質及裂縫本身內均有顯影加強現象。藉由這7個病灶的影像分析，我們可以瞭解到，應力性骨折發生在髓質骨和皮質骨時，各有其不同的影像表徵。

關鍵字

骨折，應力性 ； 骨折，磁振造影 ； 脛骨，骨折

並列摘要

The tibia is a relatively common site for stress fractures and these can easily be missed on initial radiographs. Computed tomography can yield non-specific findings in cases of transverse tibial stress fractures. The purpose of this study is to analyze the characteristic high-field-strength MR imaging features of tibial stress fractures. Six patients with seven tibial stress fractures were included. We divided the lesions into two groups according to Savoca's classification: group I included four stress fractures (3 patients) involving the cancellous bone of the tibial metaphysis, while, group Ⅱ included three stress fractures (3 patients) involving the cortical bone of the tibial diaphysis. In group Ⅰ, MR images showed an intramedullary low-signal band surrounded by amorphous areas of decreased signal intensity on T1-weighted images, and high signal intensity on T2-weighted images in all four lesions. The low-signal band was continuous with the cortex and perpendicular to the trabeculae. A subperiosteal crescent area of high signal intensity on T2-weighted images with enhancement on post- contrast images was also demonstrated in one of the four lesions. In group Ⅱ, the MR images of all three cases revealed fusiform or elliptical cortical thickening, but no definite intramedullary abnormalities. An intracortical transverse cleft was demonstrated in two of the three lesions. Cortical enhancement surrounding and in the center of the intracorticnl cleft was also noted in these two lesions. Subperiosteal crescent areas of high signal intensity on T2-weighted images were also detected in all cortical lesions. Characteristic MR imaging findings may distinguish stress fracture from other similar lesions.

並列關鍵字

Fracture, stress ； Fracture, MR ； Tibia, fractures