This study evaluates the diagnostic accuracy of an USPIO contrast agent (ferumoxtran-10) in combination with 7 Tesla MRI to detect lymph node metastases in rectal and breast cancer.

The Presence of lymph node metastases in cancer is a key factor for determining prognosis and forming an adequate treatment plan. Determining lymph node status, however, is a challenge. Ferumoxtran-10, an ultrasmall superparamagnetic iron oxide (USPIO) particle has proven to be a valuable contrast agent for detecting lymph node metastases using magnetic resonance imaging (MRI) in various types of cancer (also called nano-MRI). For small lymph node metastases (<5mm) the diagnostic accuracy of this technique does, however, drop substantially. Most of the studies that have been performed with these particles used a 1.5 Tesla or 3 Tesla MRI scanner. The investigators would like to increase the resolution of nano-MRI by using a 7 Tesla scanner, such that the investigators can increase the sensitivity of this technique for small lymph nodes. With this study the investigators would like to validate the results of this technique with pathology in rectal and breast cancer. In these cancer types many patients undergo a surgical lymph node dissection by bulk excision of tissue including the nodes, enabling a node-to-node comparison between MRI and pathology to validate our nano-MRI results . If successful this technique would form a non-invasive alternative to the current lymph node staging techniques such as surgery. Additionally (if metastatic nodes are present), it could complement image guided focal therapies on lymph node metastases such as radiotherapy.

Inclusion Criteria:

General criteria:

• Age > 18 years

Inclusion criteria rectal cancer patients:

• Patients with recently histologically proven rectal cancer, who are planned to undergo a total mesorectal excision without neo-adjuvant radiotherapy.

Inclusion criteria breast cancer patients:

• Patients with recently histologically proven breast cancer (Stage II), who are planned for surgery with sentinel node procedure, but will receive no neo-adjuvant therapy or will undergo an axillary lymph node dissection without prior sentinel node procedure and will receive no neo-adjuvant therapy.

Exclusion Criteria:

General exclusion criteria:

• BMI > 30 kg/m2

• Pregnancy

• Karnofsky score <= 70

• Contraindications for 7T MRI:

  • Epilepsy
  • Inability to provide informed consent
  • Metal implants that are not compatible with 7 Tesla MRI

• Contraindications to USPIO based contrast agents:

  • prior allergic reaction to ferumoxtran-10 or any other iron preparation
  • prior allergic reaction contributed to dextran or other polysaccharide, in any preparation
  • prior allergic reaction to contrast media of any type
  • hereditary hemochromatosis, thalassemia, sickle cell anemia;

Exclusion criteria for rectal cancer:

• Inflammatory diseases of the abdomen (such as Crohn's disease)
• Previous abdominal surgery or radiotherapy

Exclusion criteria for breast cancer:

• Prior radiotherapy or surgery to axillae