SIGNIFICANCE OF ADC MEASUREMENTS AS RADIOLOGICAL MRI MARKER IN DETECTION OF METASTATIC LYMPH NODE INVOLVEMENT IN PATIENTS WITH PROSTATE CANCER.

Abstract

Background: In spite of significant advances in diagnosis of prostate cancer (PCa), the detection and differential diagnosis of metastatic lymph node involvement remains an important clinical dilemma in a large number of cases. Contrast-enhanced abdominal computed tomography and magnetic resonance imaging (MRI), in part when using T1-weighed images (T1-WI and T2-WI), allow evaluating indirectly the presence of invasion in regional lymph nodes by assessing their diameter and morphology. Nonetheless, these techniques do not appear to be sufficiently sensitive for direct identification of lymph nodes with metastatic lesions.

Aim: To study the significance of the apparent diffusion coefficient (ADC) of diffusion-weighted MRI in detection of metastatic lymph node involvement in PCa patients.

Materials and methods: The study involved 35 patients with histologically verified PCa. Based on multiparametric prostatic MRI findings and pathomorphological reports, we have performed ADC measurements for pelvic lymph nodes either with (n = 15, mean size 1.78 ± 0.59 cm) or without metastases (n = 20, mean size: 0.94 ± 0.06 cm) in PCa patients who underwent radical prostatectomy with lymph node dissection.

Results: No significant diffe-rences were observed when comparing mean sizes of N+ and N- pelvic lymph nodes. At the same time, when comparing mean ADC values for N+ and N- pelvic lymph nodes, we observed a statistically significant difference: 0.74 ± 0.09 · 10-3 mm2/s in metastatic lymph node vs 1.05 ± 0.23 · 10-3 mm2/s in lymph nodes without metastatic involvement (p < 0.001).

Conclusion: The use of ADC for diffusion-weighted MRI may provide valuable information for detection of metastatic lymph node involvement in patients with PCa.