MR cytometry: More effective than conventional diffusion MRI in differentiating benign and malignant musculoskeletal...

To investigate the clinical significance of microstructure imaging based on MR cytometry in the qualitative diagnosis of musculoskeletal tumors (MSTs).

Participants with clinically suspected MSTs between March 2024 and March 2025 were prospectively enrolled. Conventional apparent diffusion coefficient (ADC) value and four microstructural parameters, including cell diameter (d), intracellular volume fraction (v_in), Cellularity index, and extracellular diffusivity (D_ex), were estimated using the IMPULSED method (a form of MR cytometry). The ADC_PGSE, ADC_{25 Hz} and ADC_{40 Hz} were measured at three different effective diffusion times, and the change ADC (cADC) and relative change ADC (rcADC) were measured. The performance was evaluated using the area under the receiver operating characteristic curve (AUC) and compared using the DeLong test.

A total of 62 participants with benign and malignant MSTs (mean age, 47.7 ± 20.9 [SD] years; 21 women, 41men) were enrolled. Among these ADC parameters, rcADC had the highest AUC (AUC = 0.737; 95 %Cl: 0.600, 0.874; p = 0.002). Among the four microstructure parameters derived from MR cytometry, Cellularity index had the highest AUC (AUC = 0.735; 95 %Cl: 0.601, 0.868; p = 0.002). Among all parameters, the AUC of rcADC and Cellularity index is higher than that of conventional ADC (AUC = 0.728; 95 %Cl: 0.594, 0.863; p = 0.003). The combination of the four microstructure parameters of MR cytometry further improved the diagnostic performance (AUC = 0.758; 95 %Cl: 0.626, 0.890; p = 0.001).

MR cytometry was an effective method for helping to predict the benign and malignant MSTs and is superior to conventional ADC values.