磁共振成像在细微肋骨骨折中的诊断价值

The diagnostic value of magnetic resonance imaging in rib micro-fractures

目的 通过MRI与CT在诊断细微肋骨骨折上的对比研究,探讨MRI对细微肋骨骨折的诊断价值。材料与方法 招募2019年1月至2020年12月于我院就诊的轻度胸外伤患者25例,于受伤后3周内给予患者首次CT及MRI检查,伤后4~8周行CT复查。以复查CT有骨痂生长为金标准,对细微肋骨骨折进行分型,比较MRI与首次CT检查在细微肋骨骨折上的诊断准确率及敏感度,利用Fisher确切概率法检验MRI与首次CT检查诊断结果的差异性。结果 细微肋骨骨折分为两型,Ⅰ型为骨皮质断裂伴骨痂形成,MRI上表现为骨髓水肿伴骨膜下积液;Ⅱ型为骨皮质显示完整伴有骨内骨痂形成,MRI上仅有骨髓水肿。复查CT共确诊91处细微肋骨骨折,其中Ⅰ型骨折共86处(占94.51%),Ⅱ型骨折共5处(占5.49%)。MRI检查共诊断90处骨折,3处为假阳性,其诊断准确率为92.55%,敏感度为95.60%,其中Ⅰ型骨折共85处(3处假阳性),在压脂序列上表现为“三明治”征,即内层为高信号的骨髓水肿影,中层为低信号的骨皮质,外层为高信号的骨膜下积液;Ⅱ型骨折共5处,在压脂序列上表现为高信号的骨髓水肿影,无骨膜下积液。首次CT检查发现55处骨折,全部为Ⅰ型骨折,诊断准确率及敏感度均为60.44%。MRI与首次CT检查检出的骨折数量差异有统计学意义(P=0.027)。结论 MRI检查对细微肋骨骨折具有高度敏感性及诊断准确率,可作为除CT检查以外的常规补充检查项目应用于轻度胸外伤患者。

Objective: To explore the value of MRI in the diagnosis of rib micro-fractures through a comparative study of MRI and CT.Materials and Methods: Twenty-five patients with mild chest trauma admitted to our hospital from February 2019 to December 2020 were recruited. The patients were subjected to CT and MRI within three weeks after the trauma, CT rescanning was scheduled 4-8 weeks later to classify rib fractures and determine the diagnostic accuracy and sensitivity of MRI and CT for rib micro-fractures. Fisher’s exact probability method was used to test the difference between MRI and first CT. Results: The rib micro-fractures were divided into two types. Type Ⅰ rib fractures showed cortical fracture with callus formation, whereas type Ⅱ had an intact cortical bone with intraosseous callus formation. Type Ⅰ fracture showed bone marrow edema with subperiosteal effusion in MRI, whereas type Ⅱ showed bone marrow edema without subperiosteal effusion. Ninety-one rib micro-fractures were confirmed by CT rescanning, of which 86(94.51%) were typeⅠ fractures and 5(5.49%) were type Ⅱ. MRI identified 90 fractures, of which 3 were false positive, with the diagnostic accuracy rate of92.55% and sensitivity rate of 95.60%. Among them, type Ⅰ fractures(n=85, 3 were false positive) showed "sandwich" sign(heterogeneous high-signal shadow within bone marrow of the inner layer, low-signal bony cortex of the middle layer, and high-signal subperiosteal effusion of the outer layer) in fat pressing sequences;type Ⅱ fractures(n=5) displayed intramedullar high-signal intensities and no subperiosteal effusion. Fifty-five fractures(all type Ⅰ) were discovered in the initial CT examination, and corresponding diagnostic accuracy rate and sensitivity rate were 60.44%. There was significant difference in the number of fractures detected by MRI and initial CT(P=0.027). Conclusions: MRI has high sensitivity and accuracy in the diagnosis of rib micro-fractures, so it can be used as a routine supplementary examination besides CT for patients with mild chest trauma.