Value of FDG PET/Contrast-Enhanced CT in Initial Staging of Colorectal Cancer - Comparison with Contrast-Enhanced CT.

Abstract

BACKGROUND:

FDG PET/CT is at an equivocal stage to recommend for staging of colorectal cancer as compared to contrast-enhanced CT (ceCT). This study was intended to evaluate the value of FDG PET/ceCT in colorectal cancer staging as compared to ceCT alone.

MATERIALS AND METHODS:

PET/ceCT was performed for 61 colorectal cancer patients who were prospectively enrolled in the study. Three patients were excluded due to loss to follow-up. PET/ceCT findings and ceCT results alone were read separately. The treatment planning was then determined by tumor board consensus. The criteria for T staging were determined by the findings of ceCT. Nodal positive by PET/ceCT imaging was determined by visual analysis of FDG uptake greater than regional background blood pool activity. The diagnostic accuracy of T and N staging was determined only in patients who received surgery without any neoadjuvant treatment.

RESULTS:

Of 58 patients, there were 40 with colon cancers including sigmoid cancers and 18 with rectal cancers. PET/ceCT in pre-operative staging detected bone metastasis and metastatic inguinal lymph nodes (M1a) that were undepicted on CT in 2 patients (3%), clearly de ned 19 equivocal lesions on ceCT in 18 patients (31%) and excluded 6 metastatic lesions diagnosed by ceCT in 6 patients (10%). These resulted in alteration of management plan in 15 out of the 58 cases (26%) i.e. changing from chemotherapy to surgery (4), changing extent of surgery (9) and avoidance of futile surgery (2). Forty four patients underwent surgery within 45 days after PET/CT. The diagnostic accuracy for N staging with PET/ceCT and ceCT alone was 66% and 48% with false positive rates of 24% (6/25) and 76% (19/25) and false negative rates of 47% (9/19) and 21% (4/19), respectively. All of the false negative lymph nodes from PET/ceCT were less than a centimeter in size and located in peri-lesional regions. The diagnostic accuracy for T staging was 82%. The sensitivity of the peri-lesional fat stranding sign in determining T3 stage was 94% and the specificity was 54%.

CONCLUSIONS:

Our study suggested promising roles of PET/ceCT in initial staging of colorectal cancer with better diagnostic accuracy facilitating management planning.

• Authors: Anchisa Kunawudhi, Karun Sereeborwornthanasak, Chetsadaporn Promteangtrong, Bunchorn Siripongpreeda, Saiphet Vanprom, Chanisa Chotipanich
• Journal: Asian Pacific journal of cancer prevention : APJCP (Asian Pac J Cancer Prev) Vol. 17 Issue 8 Pg. 4071-5 ( 2016) ISSN: 2476-762X [Electronic] Thailand
• PMID: 27644663 (Publication Type: Comparative Study, Journal Article)

Chemical References

• Contrast Media

Topics

• Adult
• Aged
• Colorectal Neoplasms (pathology)
• Contrast Media (administration & dosage)
• Female
• Humans
• Lymph Nodes (pathology)
• Male
• Middle Aged
• Multimodal Imaging (methods)
• Neoplasm Staging (methods)
• Positron Emission Tomography Computed Tomography (methods)
• Positron-Emission Tomography (methods)
• Sensitivity and Specificity
• Tomography, X-Ray Computed (methods)