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Abstract：
To determine the diagnostic yield of cone beam computed tomography (CBCT) compared with 3 T magnetic resonance imaging (MRI) for the evaluation of subchondral insufficiency fractures of the knee. Consecutive patients with subchondral insufficiency fractures of the knee examined by 3 T MRI and CBCT of the femoral condyles were reviewed. Two experienced raters graded the lesion severity on 3 T MRI and CBCT images: grade 1: no signs of a subchondral bone lesion; grade 2: subchondral trabecular fracture or cystic changes, but without infraction of the subchondral bone plate; grade 3: collapse of the subchondral bone plate. Ratings were repeated after six weeks to determine reliability. In addition, the bone lesion size was measured as elliptical area (mm2) and compared between CBCT and T1-weighted MRI sequences. Among 30 patients included (43.3% women; mean age: 60.9 ± 12.8 years; body mass index (BMI) 29.0 ± 12.8 kg/m2), the medial femoral condyle was affected in 21/30 patients (70%). The grading of subchondral lesions between MRI and CBCT did not match in 12 cases (40%). Based on MRI images, an underestimation (i.e., undergrading) compared with CBCT was observed in nine cases (30%), whereas overgrading occurred in three cases (10%). Compared to CBCT, routine T1-weighted 3 T sequences significantly overestimated osseus defect zones in sagittal (84.7 ± 68.9 mm2 vs. 35.9 ± 38.2 mm2, p < 0.01, Cohen\'s d = 1.14) and coronal orientation (53.1 ± 24.0 mm2 vs. 22.0 ± 15.2 mm2, p < 0.01, Cohen\'s d = 1.23). The reproducibility of the grading determined by intra- and inter-rater agreement was very high in MRI (intra-class correlation coefficient (ICC) 0.78 and 0.90, respectively) and CBCT (ICC 0.96 and 0.96, respectively). In patients with subchondral insufficiency fractures of the knee, the use of CBCT revealed discrepancies in lesion grading compared with MRI. These findings are clinically relevant, as precise determination of subchondral bone plate integrity may influence the decision about conservative or surgical treatment. CBCT represents our imaging modality of choice for grading the lesion and assessing subchondral bone plate integrity. MRI remains the gold standard modality to detect especially early stages.
摘要：
为了确定锥形束计算机断层扫描（CBCT）与3T磁共振成像（MRI）相比的诊断率，以评估膝关节软骨下功能不全骨折。连续对膝关节软骨下功能不全的患者进行了3TMRI和股骨髁CBCT检查。两名经验丰富的评估者在3TMRI和CBCT图像上对病变的严重程度进行了分级：1级：没有软骨下骨病变的迹象；2级：软骨下小梁骨折或囊性改变，但没有软骨下骨板的缺损；3级：软骨下骨板塌陷。六周后重复评级以确定可靠性。此外,骨病变大小以椭圆面积(mm2)测量,并在CBCT和T1加权MRI序列之间进行比较.在包括的30例患者中（43.3％的女性；平均年龄：60.9±12.8岁；体重指数（BMI）29.0±12.8kg/m2），21/30例患者（70％）股骨内侧髁受累。12例(40%)软骨下病变MRI与CBCT分级不相符。根据MRI图像,低估(即，降级)与CBCT相比，观察到9例(30%)，而在3例（10％）中发生了过度分级。与CBCT相比,常规T1加权3T序列显著高估矢状骨缺损区(84.7±68.9mm2vs.35.9±38.2mm2，p<0.01，科恩sd=1.14）和日冕方向（53.1±24.0mm2vs.22.0±15.2mm2，p<0.01，科恩d=1.23)。在MRI（类内相关系数（ICC）分别为0.78和0.90）和CBCT（ICC分别为0.96和0.96）中，通过评估者之间的一致性确定的分级的可重复性非常高。膝关节软骨下功能不全骨折的患者，与MRI相比,使用CBCT显示病变分级存在差异.这些发现与临床相关，因为软骨下骨板完整性的精确确定可能会影响保守或手术治疗的决定。CBCT代表了我们对病变进行分级和评估软骨下骨板完整性的首选成像方式。MRI仍然是检测特别是早期阶段的金标准模式。
