Ferumoxytol-enhanced MR lymphography for detection of metastatic lymph nodes in genitourinary malignancies: A prospective study
American Journal of Roentgenology
Bladder cancer; Ferumoxytol; Kidney cancer; Lymph node; Prostate cancer
© American Roentgen Ray Society OBJECTIVE. The objective of our study was to evaluate the utility of ferumoxytol-enhanced MR lymphography (MRL) in detection of metastatic lymph nodes (LNs) in patients with prostate, bladder, and kidney cancer. SUBJECTS AND METHODS. This phase 2 single-institution study enrolled patients with confirmed prostate (arm 1), bladder (arm 2), and kidney (arm 3) cancer and evidence of suspected LN involvement. Participants underwent ferumoxytol-enhanced MRL 24 and 48 hours after IV injection of 7.5 mg Fe/kg of ferumoxytol. A retrospective quantitative analysis was performed to determine the optimal timing for ferumoxytol-enhanced MRL using percentage change in normalized signal intensity (SI) from baseline to 24 and 48 hours after injection, which were estimated using the linear mixed-effects model in which time (24 vs 48 hours), diseases status, and time and disease status interaction were the fixed-effects independent variables. Differences in normalized SI values between subgroups of lesions were estimated by forming fixed-effects contrasts and tested by the Wald test. RESULTS. Thirty-nine patients (n = 30, arm 1; n = 6, arm 2; n = 3, arm 3) (median age, 65 years) with 145 LNs (metastatic, n = 100; benign, n = 45) were included. LN-based sensitivity, specificity, positive predictive value, and negative predictive value of ferumoxytol-enhanced MRL was 98.0%, 64.4%, 86.0%, and 93.5%, respectively. Sensitivity and specificity of ferumoxytol-enhanced MRL did not vary by LN size. Metastatic LNs showed a significantly higher percentage decrease of normalized SI on MRL at 24 hours after ferumoxytol injection than at 48 hours after ferumoxytol injection (p = 0.023), whereas the normalized SI values for nonmetastatic LNs were similar at both imaging time points (p = 0.260). CONCLUSION. Ferumoxytol-enhanced MRL shows high sensitivity in the detection of metastatic LNs in genitourinary cancers independent of LN size. The SI difference between benign and malignant LNs on ferumoxytol-enhanced MRL appears similar 24 and 48 hours after ferumoxytol injection, suggesting that imaging can be performed safely within 1 or 2 days of injection. Although ferumoxytol-enhanced MRL can be useful in settings without an available targeted PET agent, issues of iron overload and repeatability of ferumoxytol-enhanced MRL remain concerns for this method.
Turkbey, B., Czarniecki, M., Shih, J., Harmon, S., Agarwal, P., Apolo, A., Citrin, D., Gulley, J., Harisinghani, M., Madan, R., Metwalli, A., Paquette, E., Pinto, P., Rais-Bahrami, S., Rowe, L., Wood, B., Jacobs, P., Lindenberg, L., Dahut, W., & Choyke, P. (2020). Ferumoxytol-enhanced MR lymphography for detection of metastatic lymph nodes in genitourinary malignancies: A prospective study. American Journal of Roentgenology, 214 (1). http://dx.doi.org/10.2214/AJR.19.21264