Tina Islam, Presenter: Nothing to Disclose

Peter F. Hahn MD, PhD, Abstract Co-Author: Nothing to Disclose

Mukesh Gobind Harisinghani MD, Abstract Co-Author: Nothing to Disclose

Lymphotropic nanoparticle-enhanced MRI (LNMRI) has been shown to cause a homogeneous drop in signal intensity of benign lymph nodes. In patients with primary prostate cancer we evaluated morphological characteristics of inguinal lymph nodes and their signal intensity behavior on LNMRI. This patient population was selected because their inguinal lymph nodes are likely to be benign.

29 patients with prostate cancer (mean age 63 years) underwent T2-weighted fast spin echo and T2*-weighted gradient echo MR imaging before and 24-36 hours following the intravenous administration of ferumoxtran-10 (Combidex®; AMAG Pharmaceuticals Inc, Cambridge, MA). On the precontrast images shape (oval or round), border contour (well- or ill-defined), hilum status (presence or absence of fatty hilum), signal homogeneity (homogeneous or heterogeneous) were described and nodal short axis diameters were measured for inguinal nodes. On the postcontrast T2*-weighted images the percentage (<30%, 30%-50%, or >50%) of high signal intensity within the benign inguinal nodes were estimated.

233 inguinal lymph nodes were examined in 29 patients. 93.6% were oval, 57.9% showed a fatty hilum, 90.6% showed a well-defined border, and 92.3% a homogeneous signal. Mean short axis nodal diameter was 0.42 cm (+/- 0.17). Estimated high signal intensity of <30% was found in 31.3% of all groin nodes, indicative of benign differentiation. Estimated high signal intensity region between 30%-50% and >50% was found in 23.2% and 45.5% respectively, mimicking malignant features.

In a patient population with unlikely tumor involvement of inguinal lymph nodes, 68.7% of the presumed benign nodes show a high signal intensity region larger than 30% on LNMRI, similar to that observed in malignant lymph nodes. Benign inguinal lymph nodes take up nanoparticles less avidly than benign deep nodes do.

Consequently, different standards must be used in interpreting the appearance of inguinal nodes on LNMRI performed for tumors that typically spread to the groin.

Islam, T, Hahn, P, Harisinghani, M, Decreased Uptake of Ferumoxtran-10 in Inguinal Lymph Nodes in Lymphotropic Nanoparticle-enhanced MRI.  Radiological Society of North America 2008 Scientific Assembly and Annual Meeting, February 18 - February 20, 2008 ,Chicago IL. http://archive.rsna.org/2008/6012723.html