Differential diagnosis of metastasis from non-metastatic lymph nodes in cervical cancers: pilot study of diffusion weighted imaging with background suppression at 3T magnetic resonance.

ABSTRACT

BACKGROUND: Diffusion weighted imaging with background suppression (DWIBS) is potentially useful in detecting metastatic lymph nodes. This study aimed to evaluate the efficacy of DWIBS at 3T magnetic resonance (MR) for diagnosing metastatic lymph nodes in cervical cancer. METHODS: This retrospective study included 25 patients with cervical cancer who underwent MR examination and were treated by hysterectomy and lymphadenectomy. The metastatic and non-metastatic lymph nodes were histologically proven by operation. Apparent diffusion coefficient (ADC) values, long-axis diameters, short-axis diameters, ratio of short- to long-axis diameters of all the identifiable lymph nodes were measured and compared. RESULTS: Twenty-five primary tumor lesions, 17 metastatic lymph nodes and 140 non-metastatic lymph nodes were pathologically confirmed in 25 cases with cervical cancer. The difference of ADC values between primary tumor lesions, metastatic and non-metastatic lymph nodes were statistically significant (F = 7.93, P = 0.001). There was no statistically significant difference between primary tumor lesions of cervical cancer and metastatic lymph nodes (t = -0.75, P = 0.456), and the difference between primary tumor lesions and non-metastatic lymph nodes was statistically significant (t = 4.68, P < 0.001). The ADC values, long-axis diameters, short-axis diameters, ratio of short- to long-axis diameters of metastatic and non-metastatic lymph nodes were (0.86 ± 0.36) × 10(-3) mm(2)/s vs. (1.12 ± 0.34) × 10(-3) mm(2)/s, (1.51 ± 0.41) cm vs. (1.19 ± 0.36) cm, (1.16 ± 0.35) cm vs. (0.77 ± 0.22) cm, 0.78 ± 0.17 vs. 0.68 ± 0.19 respectively, and statistically significant difference existed between two groups. CONCLUSIONS: DWIBS at 3T MR has the distinct advantages in detecting pelvic lymph nodes of cervical cancer. Quantitative measurement of ADC values could reflect the degree of restriction of diffusion of metastatic and non-metastatic lymph nodes. The combination of size and ADC value would be useful in the accurate diagnosis of metastatic lymph nodes.