MRI - Lung Cancer
Assessment of the structure and function of lymph nodes within the chest using MRI in patients with known lung cancer.
OVERVIEW: Lung cancer is the biggest cancer killer in the UK, accounting for more than one in five cancer deaths.
Accurate staging of non-small cell lung cancer is the critical step which determines both the treatment modality and the prognosis. This is currently best accomplished via a multidisciplinary approach involving surgical, respiratory, oncology and radiology input in order to establish whether or not curative surgical resection is possible. Preoperative mediastinal lymph node staging separates initial operative versus non-operative status. Patients without mediastinal nodal metastases (or occasionally with ipsilateral nodes) are considered operative candidates, while patients with central or contralateral mediastinal nodal metastases are treated primarily with chemotherapy and external beam radiotherapy.
Several invasive and non-invasive methods exist to diagnose and stage lung cancer, and most patients require more than one. Inadequate staging or indeed incorrect staging of the mediastinal nodes can have the catastrophic consequences of a missed opportunity to operate or more commonly an inappropriate operation leading to high morbidity and worse outcome.
The limitations of CT in assessing nodal disease are highlighted by a false positive rate of 40% in mediastinum and the fact that 5 to 15% of patients with clinical T1N0 (stage I) tumours are found to have positive lymph node involvement at surgery. Therefore CT can overstage and understage and cannot solely determine mediastinal lymph node status in patients with NSCLC.
Sensitivity and specificity of PET for identifying mediastinal metastasis have been reported to be 74% (95% CI, 69 to 79%) and 85% (95% CI, 82 to 88%) respectively.
Recent advances in Magnetic Resonance Imaging provide the opportunity to accurately image the mediastinum with little if any respiratory or cardiac motion artefact. At UCLH we already have experience in this area with our work on the staging of paediatric lymphoma. In addition to hi-resolution anatomical imaging MRI can give a functional assessment of small nodes that are deemed not to be diseased by CT size criteria, and is therefore could prove more sensitive and specific than CT.
Patients with known lung cancer and mediastinal nodes on CT undergo endoscopic ultrasound (EBUS) guided biopsies of mediastinal nodes as small as 0.5 cm in diameter. This pilot study will determine if it is possible to accurately detect nodal involvement using MRI by comparing multi-parametric MR characteristics of lymph nodes with EBUS nodal biopsies.
Primary Study Aims:
- Evaluate the anatomical and functional MRI characteristics of mediastinal nodes by correlation to a histological gold standard obtained from EBUS guided biopsies for patients with lung cancer.
- Compare MR imaging and contrast enhanced chest CT data in assessing mediastinal nodal disease.
Secondary Study Aims:
- Investigate whether respiratory and cardiac gated hi-resolution MRI is able to detect lung disease in patients with CT diagnosed lung cancer.