Axillary lymph node metastases: a statistical analysis of various parameters in MRI with USPIO.
OBJECTIVE
To assess the value of plain vs. iron oxide-enhanced MRI vs. the combined study (plain + postcontrast) based on qualitative and quantitative parameters of three pulse sequences.


METHODS
Data from two sites were acquired using the same technique; therefore, this data could be pooled. T1W-SE, T2W-FSE, and 3D-PSIF were used before and 24-36 hours after MRI with ultra small particles of iron oxide (USPIO) was performed. A total of 52 lymph nodes (LNs) in nine patients (25 benign, 27 malignant) were evaluated by two readers who were visually and quantitatively blinded to the histology. Combinations of the following diagnostic parameters were compared using logistic regression analysis: the short-axis diameter of the LN, the signal distribution of the LN on postcontrast agent MRI (homogeneous or heterogeneous), and qualitatively and quantitatively determined signal changes of the LN following administration of contrast agent in the three evaluated sequences.


RESULTS
Using pre- and postcontrast data, the optimized accuracy based on the statistically most significant parameters (LN diameter > 6 mm, visual assessment of signal change on T2W-SE) was 87% (81% sensitivity, 92% specificity). Precontrast data alone yielded 75% accuracy (63% sensitivity, 86% specificity). Postcontrast data alone yielded 75% accuracy (56% sensitivity, 96% specificity).


CONCLUSIONS
Based on our results, USPIO-MRI improved the diagnosis of metastatic axillary LNs compared with precontrast MRI alone. Both pre- and postcontrast studies are needed. T1W-SE and T2W-PSIF did not yield significant additional information. This study may help to further improve the technique of USPIO imaging.
Department of Diagnostic Radiology, University of Halle, Germany.
Constanze
C
Stets
Silvio
S
Brandt
Fintan
F
Wallis
Jörg
J
Buchmann
F J
FJ
Gilbert
Sylvia H
SH
Heywang-Köbrunner
D001365:Axilla; D001943:Breast Neoplasms / Q000473:pathology*; D003287:Contrast Media; D003911:Dextrans; D005260:Female; D052203:Ferrosoferric Oxide; D006801:Humans; D007501:Iron; D008198:Lymph Nodes / Q000473:pathology*; D008207:Lymphatic Metastasis / Q000175:diagnosis*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D058185:Magnetite Nanoparticles; D010087:Oxides; D012044:Regression Analysis; D012680:Sensitivity and Specificity
D003287:Contrast Media; D003911:Dextrans; D058185:Magnetite Nanoparticles; D010087:Oxides; C097921:ferumoxtran-10; D007501:Iron; D052203:Ferrosoferric Oxide