Coloretcal carcinoma

Dr. Naveed AshrafRadiologic Pictorial Review
Colorectal Carcinoma
1

TEACHING POINTS
CT : is generally used for assessing the presence of any metastatic disease
and not for determining the local T staging.
MRI: is used for the local staging of rectal cancer (considered a separate
entity to colon cancer as its pelvic location reduces the ability to obtain
wide resection margins with a consequent increased risk of local
recurrence)
Mesorectal fascia: encloses the mesorectum (which contains the draining
lymphatic nodes and vessels) . Nodal spread usually occurs cranially within
this compartment
Positive circumferential resection margin (CRM): if there is tumour within
1 mm of the mesorectal fascia this requires preoperative chemotherapy
Local nodal involvement: It is important to record whether a suspicious
node lies within 1 mm of the CRM
FDG PET-CT: This is useful for detecting extracolonic disease (lesions >1
cm) . It is the most accurate modality for detecting recurrent pelvic cancer
(scar tissue does not demonstrate increased FDG PET uptake)
Endorectal US : This allows for better differentiation of the rectal wall
layers than MRI . It is used to assess early tumour involvement and select
T1N0 cases for local excision
2

Adenoma Carcinoma sequence. . A 1-cm polyp (arrow) is demonstrated in
the proximal transverse colon. B. Seventeen years later, the small polyp
has grown into a full-blown polypoid carcinoma (arrow).
3

In another patient, there are adenomas in the distal sigmoid (arrowhead ),
a polypoid carcinoma near the apex of the sigmoid, and an annular
carcinoma more proximally in the sigmoid colon.
4

Lesions missed at endoscopy identified on barium enema. A. There is a
small sessile polyp (arrow) behind a fold at the rectosigmoid junction. This
lesion was missed twice on sigmoidoscopy and was finally detected at the
third sigmoidoscopic examination. B. A small polyp (arrow) is situated
behind a fold at an area of angulation at the junction of the sigmoid and
the descending colon. This polyp was missed on two colonoscopic
examinations and was found on the third.
5

Lesions missed at endoscopy identified on barium enema.
Polypoid carcinoma is just proximal to the rectosigmoid junction.
This lesion was missed on several sigmoidoscopic and colonoscopic
examinations and was confirmed only at surgery.
Polypoid carcinoma at the hepatic flexure was missed on initial
colonoscopy.
6

Distribution of colorectal polyps (based on 108 consecutive polyps).
Approximately 60% of the polyps are in the rectum and sigmoid colon.
7

Villous adenomas. A. A flat tumor in the descending colon with an irregular
surface suggestive of a villous adenoma. This was a villoglandular polyp. B.
Typical villous tumor in the sigmoid colon. This tumor exhibits the typical,
irregular, frondlike surface of a villous tumor. It was a malignant villous
adenoma.
8

Double-contrast barium enema and colonoscopy features of polyps. A. The
bowler hat sign representing a sessile polyp. B. Mexican hat sign. This is
the typical appearance of a pedunculated polyp seen end-on. The outer
ring represents the head of the polyp, and the inner ring represents the
stalk.
9

Carpet lesions. A. Typical carpet lesion (arrow) in the cecum. B. Malignant
transformation in a carpet lesion. An obvious polypoid carcinoma is seen in
the ascending colon. Surrounding the polypoid lesion is the mucosal
change representing the underlying adenoma.
10

CT of benign polyps. A. Axial thin-section MDCT scan identifies a sessile
polyp (arrow) on the left wall of the proximal sigmoid colon, which was
confirmed by colonoscopy in a patient with carcinoma of the cecum and
familial polyposis syndrome. B. Axial thin-section MDCT below level shown
in A demonstrates a second polyp (arrow) in the small bowel.
11

Early colon cancers: polypoid carcinoma with a pedicle in 29-year-old man
with rectal bleeding. A pedunculated polyp in the descending colon (large
arrow) has a typically benign appearance. This was removed at
colonoscopy and was found to be a carcinoma with invasion of the stalk.
The smaller lesions (small arrows) were hyperplastic polyps.
12

Pedunculated early cancer. Early carcinoma (arrow) with a short, thick
stalk.
13

Lateral view shows an ulcerated plaquelike carcinoma etched in white
(arrows) at the rectosigmoid junction.
14

Large polypoid carcinoma (arrows) at the splenic flexure
15

Annular “apple core” lesion.
16

Synchronous tumors. A. A nearly obstructing polypoid carcinoid is seen in
the transverse colon, and a second adenoma is seen in the sigmoid colon.
B. Multiple polypoid carcinomas (arrows) in the ascending colon.
17

Carcinoma in a patient with diverticulosis. The polypoid carcinoma (arrow)
is more difficult to recognize in the presence of extensive diverticulosis.
18

Dr. Naveed AshrafRadiologic Pictorial Review19

TNM-stage
The treatment of a patient with
rectal cancer depends on the TNM-
stage and whether the MRF is
involved.
T-staging
T1 and T2 tumors are limited to the
bowel wall.
T3 tumors grow through the bowel
wall and infiltrate the mesorectal
fat.
They are further differentiated in:
T3a: < 1mm extension
beyond muscularis propria
T3b: 1-5 mm extension
T3c: 5 - 15 mm extension
T3d: > 15 mm
T3 MRF+ (MRF positive)
tumor within 1mm of MRF
MRF- (MRF Negative) no
tumor within 1 mm of MRF
The N-stage is based on the number
of suspicious lymph nodes:
N0 no suspicious nodes
N1 1-3 suspicious nodes
N2 ⩾ 4 suspicious nodes
20

Large intraluminal mass in a distended rectum without extension beyond
bowel wall (T2N0M0).
A. A thin-section MDCT scan in the arterial phase demonstrates a very
large intraluminal mass (large arrows) that appears to arise from the
anterior wall of the rectum. Bladder wall (thin arrows) is clearly
separated from the rectal wall by a thin layer of fat.
B. Several centimeters below the level of A, the fat plane between
bladder wall (thin arrows) and the mass (large arrow) in the anterior
rectal wall remains intact.
21

A. Coronal MPR demonstrates the large intraluminal component of the
mass (large arrows) and the wall thickening (small arrows), with a
smooth outer border.
B. The sagittal multiplanar reformatted image demonstrates a clear fat
plane between the bladder wall (small arrow) and thickened rectal wall
(thin arrow). Both MPRs confirm absence of perirectal infiltration. The
large intraluminal mass (large arrows) is also appreciated.
22

Axial thin-section (2.5 mm) MDCT scan of the rectum in the arterial phase
and with rectal administration of water demonstrates focal thickening of
the anterior and right lateral rectal wall (long arrows). The outer margin of
the rectum is smooth and well preserved. The rectal tube also is seen
(arrowhead ). No abnormal lymph nodes are identified (CT stage II).
23

Axial MDCT scan obtained with a slice thickness of 5 mm and in the portal
venous phase also shows the lesion (arrows) but the outer tumor margins
are ill defined and less well assessed.
24

Rectal carcinoma with microextension into perirectal fat, T3N0M0. The
wall of the distal sigmoid colon is circumferentially thickened as a result of
a concentric adenocarcinoma, and its outer margins are smooth. No
adenopathy or invasion of fat is demonstrated
25

Adenocarcinoma of the rectum confined to the rectal wall with perirectal
lymph nodes (T2N1M0; Dukes’ stage C1). A. MDCT scan demonstrates
minimal but diffuse wall thickening (red arrows). Mesorectal fascia is well
shown (arrowheads). Perirectal lymph nodes (white arrows) are seen in
the perirectal fat adjacent to left lateral wall of rectum. MDCT was
performed after one course of radiation, which probably caused the
diffuse wall thickening. B. MDCT scan slightly below the level in A reveals
asymmetric nodular thickening of left lateral wall of the rectum (arrows)
without extension of tumor into perirectal fat.
26

Adenocarcinoma of the sigmoid colon, A, B. T3N0 M0 (Dukes’ stage B2). A.
The axial MDCT scan demonstrates a nodular mass along the left lateral
wall of the sigmoid colon (arrows) without definite extension beyond the
bowl wall. B. In the coronal reconstruction a broad based extension of
tumor (arrow) into the pericolonic fat is seen.
27

T3N1M0 (Dukes’ stage C1). C. The full extent of the circumferential tumor
in the sigmoid colon (arrows) is best demonstrated in the coronal
reconstruction. Subtle broad-based stranding (short arrow) suggests
extension beyond the bowel wall. D. The sagittal reconstruction
demonstrates a small lymph node (short arrow) next to the sigmoid
neoplasm (long arrows).
28

Rectal carcinoma in posterior and lateral walls (arrows) of rectum
(T3N1M0; Dukes’ stage C1). A. Outer borders (arrows) are slightly irregular,
but no definite nodularity can be seen. This makes it difficult to distinguish
a desmoplastic reaction from actual tumor extension in this case. The
patient was diagnosed by MDCT as probably a T3. B. At a level higher than
in A, tumor is present only in posterior wall (thick arrow). Water facilitates
visualization of intraluminal component of tumor in spite of the presence
of feces. Also note hypogastric lymph nodes (thin arrow) that are lateral to
mesorectal fascia.
29

CT scan of primary invasive rectal adenocarcinoma (T4bN2M1; Dukes’
stage D). A. Large enhancing rectal mass (white arrow) with extension to
pelvic sidewalls. Enhanced mass is inseparable from the sacrum (black
arrows) and piriformis muscle (arrowhead ) on left. B. Rectal mass (red
arrow) directly extends into mesorectal fascia (long arrow). Abnormal
internal iliac lymph node (small arrow) also is identified. C. At a level just
below the midpole of kidneys, extensive retroperitoneal adenopathy
(arrows) is demonstrated. D. Several hepatic metastases (arrows) are seen.
30

Sigmoid carcinoma with invasion of uterus (T4bN1M0; Dukes’ stage C2). A.
Long segmental thickening (small arrows) of sigmoid wall. Note the
absence of wall stratification, which can be seen in diverticulitis. The
sigmoid tumor is inseparable from the low-density mass in the uterus
(large arrows). B. At a level 5 mm below A, gas (long arrow) is seen,
indicating direct invasion of the tumor into uterus with perforation and
necrosis. Note ascites (short arrows) along the pelvic sidewall.
31

Rectal tumor with direct extension to the mesorectal fascia and
locoregional lymphadenopathy (T3N1M0 or Dukes’ stage C2). A. Large
rectal mass with broad-based extension of soft tissue (arrows) into
perirectal fat and direct invasion of mesorectal fascia (arrowheads). B.
Several centimeters above the level of A, rectal wall is markedly thickened
but tumor does not extend into piriform muscle (thick arrow) or bladder.
Note enlarged perirectal lymph node (thin arrow).
32

Dr. Naveed Ashraf
40-year-old woman with upper rectal cancer. This case shows impact of
high-resolution oblique T2-weighted imaging on T staging. A, Routine axial
plane (dotted lines) planned on sagittal T2-weighted image. Arrow shows
tumor axis. B, On axial T2-weighted image, rectal tumor seems to invade
posterior surface of uterus (arrowheads).
33

Dr. Naveed Ashraf
(continued)— This case shows impact of highresolution oblique T2-
weighted imaging on T staging. C, Thinner slices with plane (dotted lines)
perpendicular to axis of rectum and tumor (arrow) for high-resolution
oblique imaging. D, On high-resolution oblique T2-weighted image, there
is no invasion of uterus with visible fat plane (arrows) between rectal
cancer and uterus.
34

Dr. Naveed Ashraf
T3 rectal tumors on T2-weighted MR images. A, Low rectal tumor in 58-
year-old man with tumoral spiculations (intermediate signal intensity) of
mesorectal fat (arrowheads). B, Low rectal tumor in 63-year-old man with
nodular extension to mesorectal fat. Double-headed arrow shows shortest
distance from most penetrating part of tumor and mesorectal fascia.
35

Dr. Naveed Ashraf
(continued)—T3 rectal tumors on T2-weighted MR images. C, Midrectal
tumor in 80-year-old man with massive extension to mesorectal fat and
mesorectal fascia infiltration (arrowheads). Double-headed arrow shows
extramural depth of invasion. D, Nontumoral spiculation (low signal
intensity) of mesorectal fat without nodular extension to tumor
(arrowheads) beyond muscularis propria in 67-year-old woman;
pathology revealed T2 tumor.
36

Anterior and lateral aspects of upper rectum and anterior aspect of middle
rectum are covered with peritoneum (red line). Shortest distance between
tumor and circumferential resection margin (blue arrows) is measured as
that between most penetrating part of tumor and mesorectal fascia not
covered by peritoneum (black line).
37

Dr. Naveed Ashraf
High-resolution oblique T2-weighted images of two patients with T4 rectal
tumors. A, 40-year-old man with rectal tumor invading right seminal
vesicle (arrow) and levator ani (arrowheads). B, 53-year-old woman with
rectal tumor (asterisk) invading left posterior vaginal wall (arrow).
38

Coronal schematic diagram of lower rectum (left) and MR image of lower
rectum (right) in 58-year-old woman depict anal sphincter complex and
surgical dissection planes.
Standard low anterior resection (LAR) is reserved for mid- and high-rectal
tumors without invasion to pelvic floor muscles.
Intersphincteric resection (ISR) dissects internal anal sphincter at about
level of dentate line.
Abdominoperineal resection (APR) involves removal of rectum along with
sphincter complex.
AV = anal verge, EAS = external sphincter complex, IAS = internal anal
sphincter, ISP = intersphincteric plane, PR = puborectalis, LA = levator ani.
39

Dr. Naveed Ashraf
Low rectal cancer in 63-year-old woman. A and B, Axial T2-weighted (A)
and contrast-enhanced T1-weighted (B) images depict large locally
advanced low rectal cancer invading sphincter complex, extending laterally
to right ischiorectal fossa and right obturator externus muscle, and
invading anterior vagina. In this patient, conventional abdominoperineal
resection (dotted line) would result in positive margin. Wide
abdominoperineal excision and pelvic exenteration (solid line) were
performed on basis of MRI findings.
40

Dr. Naveed Ashraf
Malignant pelvic lymphadenopathy with rectal cancer in 71-year-old man.
A, Axial T2-weighted image shows three heterogeneous enlarged lymph
nodes in upper mesorectum and right obturator region (arrowheads). B,
Involved nodes shows heterogeneous enhancement (arrows) on contrast-
enhanced T1- weighted image.
41

On axial T2-weighted image, two oval nodules suggestive of mesorectal
nodes are evident on right (arrowhead) at 9-o’clock position and left
(arrow) at 3-o’clock position of rectum.
42

Continued- Coronal T2-weighted image of right-side lesion shows
irregularly expanded vessel with heterogeneous tumor signal intensity
(arrowheads) in vicinity of rectal tumor (asterisk) indicative of Extramural
vascular invasion EMVI.
43

Continued- Coronal T2-weighted image of left-side lesion (arrow) shows
that lesion remains oval in shape, which suggests that lesion is metastatic
mesorectal lymph node.
44

Dr. Naveed Ashraf
Significant pathologic response to chemoradiation therapy (CRT).
A, shows large circumferential rectal tumor with intermediate signal
intensity
B, shows marked fibrosis.
45

Dr. Naveed Ashraf
A, Diffusionweighted image shows restricted diffusion
B, shows diffusion is not restricted
46

Dr. Naveed Ashraf
A, shows that tumor enhances.
B, shows marked interval decrease in tumor size and enhancement.
47

Dr. Naveed Ashraf
A, PET shows tumor (arrow,) is metabolically active.
B, shows marked interval improvement, but there is residual focal uptake
of FDG (arrow) along left wall of lower rectum.
48

Dr. Naveed Ashraf
T2 volumetry for the evaluation of tumor response in a 72-year-old man.
(a) Before radiation therapy and chemotherapy, volumetry based on
sagittal T2-weighted MR image (red) shows a large mass in the upper
rectum with a volume of 95 mL. (b) After radiation therapy and
chemotherapy, MR image shows a dramatic reduction in tumor volume (7
mL).
49

Dr. Naveed Ashraf
DWI for tumor detection in a 56-year-old man with a relapsing rectal
tumor. (a) Sagittal T2-weighted MR image does not adequately show the
tumor extension. (b) Sagittal diffusion-weighted image at a high b value (b
= 1000 sec/mm2) clearly shows the tumor (arrows). DWI has the
advantage of higher contrast resolution but is still hampered by lower
spatial resolution compared with T2-weighted imaging. Thus,
simultaneous use of both data sets provides better results for tumor
delineation. DWI is an accurate technique for detecting CRC.
50

Coloretcal carcinoma

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