Relative apparent diffusion coefficient: a promising tool to differentiate metastatic from benign lymph nodes in...

Area of Science:

• Radiology
• Oncology
• Medical Imaging

Background:

• Diffusion-weighted imaging (DWI) is utilized for lymphadenopathy characterization.
• Prior studies show variability in DWI for lymph node differentiation.
• The study aimed to compare apparent diffusion coefficient (ADC) and relative ADC (rADC) for differentiating metastatic and benign lymph nodes.

Purpose of the Study:

• To evaluate the diagnostic performance of ADC and rADC in distinguishing metastatic from benign lymph nodes.
• To determine the optimal region of interest (ROI) for reliable rADC measurements.
• To assess the utility of muscle tissue as a reference site for rADC calculation.

Main Methods:

• Apparent diffusion coefficients (ADCs) were measured in rabbit lymph nodes and quadriceps muscles.
• Relative ADC (rADC) was calculated as the ratio of lesion ADC to reference site ADC.
• Receiver operating characteristic (ROC) analysis compared the diagnostic accuracy of ADC and rADC.

Main Results:

• Good interobserver agreement (ICC=0.816) was achieved with a five-pixel ROI.
• Statistically significant differences in ADC and rADC values were observed between metastatic and benign lymph nodes.
• rADC demonstrated a greater area under the ROC curve than ADC, with 93% sensitivity and 90% specificity at an rADC cutoff of 0.640.

Conclusions:

• Muscle tissue provides a repeatable reference site for rADC measurements.
• rADC enhances diagnostic accuracy for detecting metastatic lymph nodes in animal models.
• rADC shows potential as a valuable tool in preclinical cancer imaging.