Collapse-related bone changes at multidetector CT in ARCO 1-2 osteonecrotic femoral heads: correlation with clinical and MRI data

Comparison of CT and MRI in diagnosing occult hip fracture: a systematic review and meta-analysis

OBJECTIVE

To compare the diagnostic accuracy of computed tomography (CT) scans and magnetic resonance imaging (MRI) in detecting occult hip fractures.

METHODS

We conducted a systematic literature review and identified 12 articles involving 1,819 participants for inclusion. Data extraction and quality assessment were performed using the Quality Assessment of Diagnostic Accuracy Studies-2 tool. Publication bias was assessed with the Deek funnel plot asymmetry test. We conducted a meta-analysis using a random-effects model to derive pooled estimates of sensitivity, specificity, positive and negative likelihood ratios, and the diagnostic odds ratio, along with their 95% confidence intervals. A summary receiver operating characteristic curve was generated to illustrate the overall diagnostic accuracy.

RESULTS

The methodological quality of the included studies was high, with minimal concerns about the applicability of the tests in clinical settings. Both CT and MRI showed good diagnostic efficacy for occult hip fractures. However, MRI consistently outperformed CT, exhibiting significantly higher sensitivity, specificity, and likelihood ratios, thereby providing superior accuracy in confirming or excluding occult fractures. Meta-regression analysis revealed that sequence parameters and sample size significantly influenced the differences in sensitivity and specificity between CT and MRI.

CONCLUSION

Both CT and MRI are effective modalities for detecting occult hip fractures, with MRI demonstrating greater diagnostic accuracy. This meta-analysis supports the use of MRI when higher sensitivity and specificity are required in clinical practice.

The Many Faces of Marrow Necrosis

Depending on the age and location within the skeleton, bone marrow can be mostly fatty or hematopoietic, and both types can be affected by marrow necrosis. This review article highlights the magnetic resonance imaging findings of disorders in which marrow necrosis is the dominant feature.Fatty marrow necrosis is detected on T1-weighted images that show an early and specific finding: the reactive interface. Collapse is a frequent complication of epiphyseal necrosis and detected on fat-suppressed fluid-sensitive sequences or using conventional radiographs. Nonfatty marrow necrosis is less frequently diagnosed. It is poorly visible on T1-weighted images, and it is detected on fat-suppressed fluid-sensitive images or by the lack of enhancement after contrast injection.Pathologies historically "misnamed" as osteonecrosis but do not share the same histologic or imaging features of marrow necrosis are also highlighted.

CT and MRI findings beyond the subchondral bone in osteonecrosis of the femoral head to distinguish between ARCO stages 2 and 3A

OBJECTIVES

To determine the diagnostic values of deep changes beyond the subchondral bone in osteonecrosis of the femoral head (ONFH) to distinguish between Association Research Circulation Osseous (ARCO) stages 2 and 3A.

METHODS

This retrospective study included 124 hips with ONFH of stages 2 (n = 49; 23 females; mean age, 50.7 years) and 3A (n = 75; 20 females; mean age, 53.2 years) from May 2017 to August 2022, who underwent CT (n = 124) and MRI (n = 85). Deep changes beyond subchondral bone were analyzed on CT (bone resorption area and cystic change) and on MRI (bone marrow edema [BME] and joint effusion). Diagnostic performance and multivariate analysis were evaluated for detecting stage 3A.

RESULTS

Stage 3A showed more frequent bone resorption area (72.0% vs. 4.1%), cystic change (52.0% vs. 0.0%), BME (93.5% vs. 43.6%), and joint effusion (76.0% vs. 24.5%) than stage 2 (p < 0.001, all). Bone resorption area and cystic change showed low sensitivities (52.0~72.0%) but high specificities (96.0~100.0%), while BME and joint effusion showed high sensitivities (76.0~93.0%) but low specificities (56.0~76.0%) for stage 3A. Predictors were in the order of bone resorption area, cystic change, and joint effusion (odds ratio: 32.952, 26.281, 9.603, respectively), and combined bone resorption area and cystic change had the best predictive value (AUC, 0.900) for stage 3A.

CONCLUSIONS

Among deep changes, bone resorption area and cystic changes were highly specific and BME and joint effusion were highly sensitive for stage 3A. Combined bone resorption area and cystic change had the best predictive value for predicting ARCO stage 3A.

KEY POINTS

• The exact classification between ARCO stage 2 and 3A is essential but it is sometimes difficult to distinguish between ARCO stage 2 and 3A only by subchondral fracture, especially early post-collapse stage with preservation of femoral head contour. • The predictors of stage 3A were in the order of bone resorption area, cystic change, and joint effusion and combined bone resorption area and cystic change had the best predictive value for predicting stage 3A. • Analysis of deep changes beyond the subchondral bone may make it easier to distinguish between ARCO stage 2 and 3A.