MR Imaging of Chondrogenic Tumors: Update on Select Imaging Challenges

Assessment of central cartilaginous tumor of the appendicular bone: inter-observer and intermodality agreement and comparison of diagnostic performance of CT and MRI

BACKGROUND

Diagnostic performance, inter-observer agreement, and intermodality agreement between computed tomography (CT) and magnetic resonance imaging (MRI) in the depiction of the major distinguishing imaging features of central cartilaginous tumors have not been investigated.

PURPOSE

To determine the inter-observer and intermodality agreement of CT and MRI in the evaluation of central cartilaginous tumors of the appendicular bones, and to compare their diagnostic performance.

MATERIAL AND METHODS

Two independent radiologists retrospectively reviewed preoperative CT and MRI. Inter-observer and intermodality agreement between CT and MRI in the assessment of distinguishing imaging features, including lesion size, deep endosteal scalloping, cortical expansion, cortical disruption, pathologic fracture, soft tissue extension, and peritumoral edema, were evaluated. The agreement with histopathology and the accuracy of the radiologic diagnoses made with CT and MRI were also analyzed.

RESULTS

A total of 72 patients were included. CT and MRI showed high inter-observer and intermodality agreements with regard to size, deep endosteal scalloping, cortical expansion, cortical disruption, and soft tissue extension (ICC = 0.96-0.99, k = 0.60-0.90). However, for the evaluation of pathologic fracture, MRI showed only moderate inter-observer agreement (k = 0.47). Peritumoral edema showed only fair intermodality agreement (k = 0.28-0.33) and moderate inter-observer agreement (k = 0.46) on CT. Both CT and MRI showed excellent diagnostic performance, with high agreement with the histopathology (k = 0.89 and 0.87, respectively) and high accuracy (91.7% for both CT and MRI).

CONCLUSION

CT and MRI showed high inter-observer and intermodality agreement in the assessment of several distinguishing imaging features of central cartilaginous tumors of the appendicular bones and demonstrated comparable diagnostic performance.

Correlation of quantitative diffusion weighted MR imaging between benign, malignant chondrogenic and malignant non-chondrogenic bone tumors with histopathologic type

Objectives

This study aims to determine the diffusion on weighted imaging which may help in providing characterization of Apparent Diffusion Coefficient (ADC) values in benign, malignant chondrogenic and malignant non-chondrogenic bone tumors.

Material and methods

A retrospective study with 84 samples was conducted from October 2017 to December 2019. The samples consisted of 44 males and 40 females; the age range of 10–73 years (mean age of 32.7 years old). A Diffusion-weighted Magnetic Resonance (MR) utilizes a single-shot echo-planar imaging sequence technique with the 3T MR Scanner. We classified the types of tumors into benign, malignant chondrogenic and malignant non-chondrogenic bone tumors. The mean of ADC values from the area with lowest ADC values was selected for statistical analysis. ADC values were compared between benign, malignant chondrogenic and malignant non-chondrogenic bone tumors. Therefore, Receiver Operating Curve (ROC) analysis was done to determine optimal cut-off values. The correlation of ADC values between benign, malignant chondrogenic and malignant non-chondrogenic bone tumor with histopathologic type was also evaluated.

Results

The mean of ADC values from the area of benign, malignant chondrogenic and malignant non-chondrogenic bone tumor were 1.55 × 10⁻³ mm²/s, 1.84 × 10⁻³ mm²/s and 1.12 × 10⁻³ mm²/s respectively. As a matter of fact, there was a significant difference between benign and malignant bone tumor with cut-off value of 1.15 × 10⁻³ mm²/s and had a sensitivity of 82%, and a specificity of 92.3%. Moreover, a significant correlation was also found between ADC values with the histopathology type of bone tumors.

Conclusion

The ADC values of benign and malignant (chondrogenic and non-chondrogenic groups) bone tumors are different. Thus, the measurement of ADC values improves the accuracy of the diagnosis of bone tumors.