Consistency of MR Cytometry Mappings across Different Acquisition Protocols in Prostate Imaging.

RATIONALE AND OBJECTIVES: To evaluate the consistency of MR cytometry mappings across protocols, and quantify the variations in prostate imaging between oscillating gradient spin-echo (OGSE) frequencies of 17/33Hz and 25/50Hz. MATERIALS AND METHODS: This prospective study enrolled 40 patients requiring prostate MRI examinations, who underwent 3T-MRI scans including pulsed gradient spin-echo (PGSE) and OGSE sequences. Two acquisition protocols with different OGSE sequences were employed: 17/33Hz and 25/50Hz. Regions of interest (ROIs) encompassing entire prostates were manually delineated and further subdivided into peripheral (PZ) and transitional zones (TZ) by a radiologist. Microstructural parameters were fitted using the IMPULSED model, and time-dependent apparent diffusion coefficients (ADCs) were calculated. Common first-order and radiomic features were extracted from their mappings. Wilcoxon signed-rank test was performed to evaluate paired differences (17/33Hz vs. 25/50Hz); relative variation coefficients were calculated for each patient; Pearson correlation analysis quantified correlations between two sets of results. All statistical analyses were performed separately for entire prostate, PZ, and TZ. RESULTS: The results for the entire prostate, PZ, and TZ were similar: Although several first-order features (such as mean and median) of imaging parameters showed strong correlations (r>0.7), most features exhibited inconsistencies between the two protocols, including significant paired differences, large relative variations and low correlations, particularly for cell diameter mappings. Over 30% of radiomic features exhibited correlations of r<0.5 across different protocols. CONCLUSION: MR cytometry imaging, including IMPULSED model fitting and time-dependent ADC measurements, depends on the specific acquisition protocol; in particular, cell diameter mapping is highly dependent on OGSE frequencies.