Role of imaging and synoptic MRI reporting in determining optimal management paradigm for rectal cancer: a narrative review

Abstract

: Magnetic resonance imaging plays a key role in the primary staging and post-treatment assessment of rectal cancer. MRI with high resolution T2-weighted sequences accurately assesses tumour morphology, location, depth of spread and the relationship of the tumour to surrounding structures such as the circumferential resection margin. The extent of disease beyond the mesorectal plane is well defined by MRI. In addition, MRI identifies poor prognostic indicators such as tumour deposits and extramural venous invasion. The information gleaned from the MRI assists the multidisciplinary team to determine the most appropriate treatment including surgical planning, mapping for radiotherapy treatment and the decision to administer neoadjuvant chemotherapy. Systematic proforma reporting of rectal MRI by radiologists is based on a template containing a comprehensive list of diagnostic and prognostic information. This form of reporting is encouraged as it provides consistency in radiology reporting and enables clinicians to communicate effectively with patients about the treatment pathways they will undertake. Clarity at diagnosis is critical for developing treatment plans that will produce optimal patient outcomes. MRI is also useful in restaging of rectal tumours post neoadjuvant chemotherapy and may assist in the detection of local recurrence. In this review, the role and accuracy of MRI in the local staging of rectal cancer both at baseline and after neoadjuvant treatment, the ideal MR imaging protocol and the benefits of proforma reporting will be discussed.