Case report – rectal cancer
T.Rohan
Department of Radiology and Nuclear Medicine University Hospital Brno and Faculty of Medicine
Masaryk University
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Male, 72 years
•Admitted to surgery department for staging and treatment of recenttly  diagnosed rectal cancer.
•
•Positive fecal occult blood test. On following colonoscopy rectal cancer in the distance 8 cm from
anus, histologically confirmed adenocarcinoma.
•
•No subjective complaints.
•Objectively palpable resistance during digital rectal examination.
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Rectal cancer staging
•Locoregional staging (extent of the tumor, regional lymph nodes):
•MRI of the rectum, rectoscopy with endoluminal ultrasound
•
•Staging of distant metastases:
•CT of abdomen and thorax, alternative is PET/CT or PET/MRI of the trunk
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PET/MRI of the trunk and rectum allows to perform locoregional staging and detection of distant
metastases during one procedure.
During staging of rectal cancer on PET/MRI, in adition to standard sequences, dedicated sequences
focused on rectum are performed.

MRI of the rectum - summary
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In the distance of 5 cm from anus is a rectal cancer causing circular thickening of rectal wall in
the length of 8 cm. Tumor grows into surrounding fat, but it is not infiltrating mesorectal fascia
or prostate. On diffuse weighted images is visible restricted diffusion corresponding to increased
accumulation of fluordeoxyglucose.
Conclusion: Rectal cancer T3b N0 M0.
T2 axial plane – distance from anus, extent of the tumor
T2 coronal plane – circular thickening of the wall with spiculations iradiating into surounding
fat, small lymph nodes in perirectal fat (circles).
PET/MRI fusion – radiopharmaceutical (18-FDG) is accumulated in rectal cancer and urinary bladder
(excreted via urine).

Follow-up
•Presentation on tumor board.
•
•Tumor board recommends neoadjuvant chemoradiotherapy (in total aplicated 45Gy focused on the
pelvis and 5.4Gy on the rectum, concomitantly capecitabine, no complicationss)
-
•Initial plan was to perform restaging on PET/MRI, but the patient missed the appointment and
PET/MRI was not ordered  in time.
•PET (PET/MR) should be performed at least 8 weaks since the last radiotherapy because of possible
false positive findings in irradiated area.
•
•Because of mentioned consequences restaging was performed via MRI of the rectum (locoregional
staging) and abdominal CT (distant metastases).
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MRI of the rectum - restaging
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7 cm from the anus is rectal tumor causing semicircular thickening of the wall in the length of 5
cm, wall thickening is in partial regression (today up to 10 mm, on the previous examination up to
17 mm). Tumor grows 1-2 mm into surrounding fat on the ventral part of the rectum, it is not in
contact with mesorectal fascia or prostate.
Conclusion: Rectal cancer ycT3a N0 M0 – partial regression of the tumor.
T2 axial plane – distance from anus, extent of the tumor
T2 coronal plane – less conspicuous circular thickening of the wall with  small spiculation into
surrounding fat, no lymph nodes in perirectal fat.
PET/MRI fusion – radiopharmaceutical (18-FDG) is accumulated in rectal cancer and urinary bladder
(excreted via urine).

•No distant metastases on abdominal CT.
•
•Surgical resection – transanal total mesorectal excision with coloanal anastomosis.
•(Histologically moderately differentiated (G2) intestinal typee adenocarcinoma infiltrating
muscular layer (ypT2). No signs of angioinvasion no metastasis in lymph nodes - LN 0/11 (ypN0).
Proximal, distal and circular resection line without signs of the tumor. ypT2ypN0M0)
•Resection was followed with adjuvant chemotherapy.
•
•Further follow-up on PET/MRI.
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Summary
•Locoregional staging of rectal cancer rekta is performed on MRI.
•
•PET/MRI allows to perform locoregional staging and detection of distant metastases of rectal
cancer during one procedure.
•
•MRI of the rectum is suitable method for restaging after neoadjuvant therapy.
•
•PET (PET/MR) should be performed at least 8 weaks since the last radiotherapy because of possible
false positive findings in irradiated area.
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