Combination of a Large Loop Flex Coil with the Breast Coil Improves Evaluation of the Lymph Nodes
1 Clinique St Pierre, Ottignies, Belgium, 2 Siemens Medical Solutions, Belgium | 2007-05-30
At present, we do not have efficient methods to detect the infiltration of axillary lymph nodes in pre-surgery planning of breast cancer. Consequently, even in the case of very small breast tumors, it is necessary to explore the axilla during surgery and to remove at least the sentinel lymph node i.e. the first draining lymph node next to the tumor. Pre-operative MR scans can give us interesting information on the status of the lymph nodes. During MR exams we study the dimension of the nodes, their morphology (looking for asymmetric cortical thickening), we study the intensity of the Gadolinium uptake or calculate the ADC (Apparent Diffusion Coefficient) in diffusion imaging. There is a lot to gain from the use of more specific contrast agents too. Nevertheless, a prerequisite for evaluation is good image quality and sufficient signal- to-noise ratio (S/N) in the axillary region.
In order to improve S/N in the axilla, we use 2 Large Loop Flex coils (LLF) in combination with the Breast coil (Fig. 1A). These exams were done on our MAGNETOM Harmony 1.0T – Maestro Class platform. Putting the loop coils centric around the 2 openings of the breast coil extends the useful RF-coverage far beyond the axilla and improves the signal at the border of the breast coil with at least 200% at 1.0T (Fig. 1B). Although low field systems might benefit more from this S/N gain, high field exams also produce better image quality as shown in Fig. 2 on MAGNETOM Avanto (left axilla with, right axilla without LL Flex Coil).