Multimodal imaging evaluation in staging of rectal cancer

Table 2 Advantages and disadvantages of imaging modalities in preoperative staging

Imaging modalities	Advantages	Disadvantages
Preoperative staging
EUS	Depth of tumor invasion in early rectal cancer	Limited field of view Perirectal invasion and LN metastasis
CT	Wide availability Fast scanning time	Local staging and CRM involvement in lower rectal cancer
MRI	High soft tissue resolution Local staging and CRM involvement	Distant metastasis
PET/CT	Distant metastasis	Poor spatial resolution Perirectal invasion and CRM involvement
Post-therapeutic restaging
EUS	None	Low accuracy of T staging and LN staging
CT	Relatively high accuracy of CRM status	Relatively low accuracy of T staging and LN staging
MRI	High specificity of therapeutic response assessment High accuracy of CRM involvement	Relatively poor sensitivity
PET/CT	Distant metastasis	No standard parameter and follow-up protocol

MRI: Magnetic resonance image; EUS: Endorectal ultrasonography; CT: Computed tomography; PET: Positron emission tomography; CRM: Circumferential resection margin; LN: Lymph node.