DOI:10.2214/AJR.07.2305
AJR 2007; 189:283-289
© American Roentgen Ray Society
CT Colonography for Follow-Up After Surgery for Colorectal Cancer
Young Jun Choi1,
Seong Ho Park1,
Seung Soo Lee1,
Eugene K. Choi2,
Chang Sik Yu3,
Hee Cheol Kim3 and
Jin Cheon Kim3
1 Department of Radiology and Research Institute of Radiology, University of
Ulsan College of Medicine, Asan Medical Center, 388-1 Poongnap-Dong,
Songpa-Gu, Seoul 138-736, Korea.
2 Weill Medical College of Cornell University, New York, NY.
3 Department of Surgery, University of Ulsan College of Medicine, Asan Medical
Center, Seoul, Korea.
Received January 28, 2007;
accepted after revision April 18, 2007.
Address correspondence to S. H. Park
(seongho{at}amc.seoul.kr).
Abstract
OBJECTIVE. The purpose of this article is to discuss the CT
colonography (CTC) findings and the role of CTC for follow-up after curative
surgery for colorectal cancer.
CONCLUSION. Contrast-enhanced CTC can be effective for surveillance
for colorectal cancer recurrence after curative surgery because it enables
simultaneous evaluation of distant abdominal metastasis, pericolic recurrence,
intraluminal recurrence, and metachronous lesions. The appearances of
anastomotic recurrences at CTC overlap with those of more common inflammatory
polyps and rare benign ulcers.
Keywords: colorectal cancer • CT colonography • postsurgical surveillance • surgery
Introduction
Postsurgical surveillance in patients who underwent curative surgery
for colorectal cancer is important because early detection and treatment of
tumor relapse seem to be critical for patient prognosis. No consensus yet
exists regarding the use of CT colonography (CTC) for postsurgical
surveillance of colorectal cancer patients. Although recent guidelines
[1,
2] do not consider CTC to be a
surveillance option, a few recent studies
[3-6]
have suggested its usefulness in postsurgical colorectal cancer surveillance.
Because more than half of the recurrences of colorectal cancer occur as
distant metastases [7,
8] and most local recurrences
lack an intraluminal component
[8], CTC performed with IV
contrast enhancement may offer a unique advantage: It allows simultaneous
evaluation of distant abdominal organs, the pericolic area, and the colonic
lumen. CTC could also have a role in postsurgical patients in whom optical
colonoscopy failed.
CTC techniques relevant to postsurgical status have not been much discussed
in the literature; however, a few points may be worth consideration. It may be
wise to have a period of respite after surgery. Postoperative optical
colonoscopic examination and clearing of synchronous lesions in patients with
incomplete preoperative optical colonoscopy is recommended at 3-6 months after
surgery [2]. Likewise, CTC may
probably be safely performed several months after surgery. The rectal balloon
should be used carefully in patients with a low rectal anastomosis to avoid
anastomotic breakdown or obscuring of anastomotic lesions.
To our knowledge, the various CTC findings after curative surgery for
colorectal cancer have not been adequately described in the literature.
Therefore, the purpose of this article is to present a spectrum of CTC
findings and to discuss the role of CTC for follow-up after curative surgery
for colorectal cancer.
Normal Anastomosis
Colonic or ileocolic anastomoses can be made in an end-to-end or
end-to-side fashion by manually suturing or by using a surgical stapler. A
normal anastomosis typically presents as a smooth, circumferential ridge
(Figs. 1A,
1B and
2A,
2B) or a weblike appearance
(Fig. 3) on CTC. The
anastomotic edge may appear sharp (Figs.
1A,
1B and
3) or blunted (Fig.
2A,
2B).
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Fig. 1A —66-year-old man with normal ileocolic anastomosis (end-to-side type)
after right hemicolectomy. Three-dimensional endoluminal CT colonography image
shows normal anastomosis, which appears as smooth, sharp, and circumferential
ridge (arrowheads).
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Fig. 1B —66-year-old man with normal ileocolic anastomosis (end-to-side type)
after right hemicolectomy. Optical colonoscopy shows corresponding smooth,
sharp anastomotic edge of even thickness (arrowheads).
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Fig. 2A —68-year-old man with normal colocolic anastomosis (end-to-end type)
after low anterior resection. Three-dimensional endoluminal CT colonography
image shows normal anastomosis, which presents as smooth, blunted, and
circumferential ridge (arrowheads).
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Fig. 2B —68-year-old man with normal colocolic anastomosis (end-to-end type)
after low anterior resection. Optical colonoscopy shows corresponding
appearance of normal anastomosis (arrowheads).
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Fig. 3 —73-year-old man with normal colocolic anastomosis (end-to-end type)
after low anterior resection. Three-dimensional endoluminal CT colonography
image shows normal anastomosis that presents weblike appearance.
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Abnormal Anastomosis
Extruded Surgical Staples
Exposition and extrusion of surgical staples used to create anastomosis to
the lumen is common. In one series, exposed staples were seen at optical
colonoscopy in 24% (6/25) of stapled colonic anastomoses
[9]. Although an extruded
surgical staple generally has no clinical significance, it can mimic colonic
polyps on a 3D endoluminal CTC view (Fig.
4A). Extruded staples can be clearly distinguished from true
polyps on 2D images by their high attenuation
(Fig. 4B).
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Fig. 4A —35-year-old man with 5-mm extruded surgical staple in colocolic
anastomosis after low anterior resection. Three-dimensional endoluminal CT
colonography (CTC) image shows small polypoid lesion (arrowhead)
adjacent to anastomotic edge.
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Fig. 4B —35-year-old man with 5-mm extruded surgical staple in colocolic
anastomosis after low anterior resection. Transverse 2D image at soft-tissue
window setting (window width, 400 H; window level, 20 H) from CTC clearly
shows high attenuation of corresponding polypoid structure
(arrowhead) and intact staple line (arrows).
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Inflammatory Polyps
Most polyps that occur at the anastomotic site are nonneoplastic
inflammatory polyps [10] (Fig.
5A,
5B,
5C). In one series,
inflammatory polyps were the most commonly observed anastomotic abnormality,
having an incidence of 14.5% (27/186) among those who underwent resection for
a colonic neoplasm, in contrast to the incidence of 1.1% (2/186) for
adenomatous polyps [10].
Inflammatory polyps may present 6 months to 7 years after surgery and have
been reported to appear endoscopically as discrete, erythematous, 5- to 15-mm
polypoid lesions [10]. They
are histologically characterized by acute and chronic inflammation,
occasionally with granulation tissue
[10]. At CTC, inflammatory
polyps present as polypoid luminal protrusions that are indistinguishable from
adenomatous polyps (Fig. 5A,
5B,
5C); they may mimic recurrent
carcinomas. Optical colonoscopy findings are also generally indistinguishable
from those of adenomas or recurrent carcinomas and thus biopsy is required for
confirmation [10,
11].
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Fig. 5A —79-year-old man with 9-mm inflammatory polyp at ileocolic
anastomosis. Three-dimensional endoluminal CT colonography (CTC) image
obtained 3 years after surgery shows well-defined sessile polypoid lesion
(arrowheads) in anastomosis.
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Fig. 5B —79-year-old man with 9-mm inflammatory polyp at ileocolic
anastomosis. Two-dimensional transverse image at wide window setting (window
width, 1,500 H; window level, -400 H) from CTC shows polypoid lesion
(arrowhead) of soft-tissue attenuation on anastomotic edge. C =
colon, I = ileum.
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Fig. 5C —79-year-old man with 9-mm inflammatory polyp at ileocolic
anastomosis. Follow-up optical colonoscopy shows corresponding polypoid lesion
(arrowheads) with overlying erythematous mucosa at site of
anastomosis. Colonoscopic biopsy revealed nonspecific inflammatory change with
no evidence of neoplasm.
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Benign Ulceration
Benign ulcers rarely occur at the anastomotic site and can mimic recurrent
carcinoma. In contrast to gastric anastomotic ulcers that are well known,
colonic anastomotic ulcers have been described in only a few reports
[10,
12,
13]. A widely variable amount
of time (1-48 years) may elapse between surgery and the occurrence of
anastomotic ulcers [13]. In
some cases, underlying inflammatory bowel disease or nonsteroidal
antiinflammatory drug use are known etiologic factors, although the
pathogenesis of many reported cases is unclear. Those cases without apparent
etiologic factors are thought to originate from various causes, including
ischemia secondary to postoperative vascular change, local mechanical trauma
secondary to abnormal motility, reaction to surgical material, bacterial
overgrowth, and bile acid malabsorption
[13].
Anastomotic Tumor Recurrence
Anastomotic or local tumor recurrences present more frequently as
extraluminal lesions than as intraluminal lesions
[8]. According to one
meta-analysis, the rate of intraluminal anastomotic recurrence was only 3.2%
(33/1,028) of patients who underwent curative surgery for colorectal cancer in
contrast to 14.4% (193/1,342) for all local recurrences
[8]. Intraluminal recurrent
carcinomas appear as ulcerated lesions (Fig.
6A,
6B,
6C), strictures with friable
mucosa, bulky luminal masses, or polypoid lesions on CTC and on optical
colonoscopy [3,
6,
11]. Extraluminal recurrences
present on CT as an enhancing extra-colonic mass adjacent to the anastomosis
(Fig. 7A,
7B,
7C) or colonic wall thickening
at the anastomotic site that may be accompanied by pericolic infiltration. In
previous studies, contrast-enhanced CTC showed 100% sensitivity (2/2 patients)
with 94% specificity (45/48 patients)
[3] and 100% sensitivity (51/51
patients) with 83% specificity (24/29 patients)
[6] in the diagnosis of local
recurrence.
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Fig. 6A —66-year-old man with cancer recurrence at site of anastomosis after
low anterior resection. Three-dimensional endoluminal CT colonography (CTC)
image obtained 10 months after surgery shows ill-defined ulcerating,
infiltrative (black arrowheads) lesion at site of anastomosis. Rectal
tube (white arrowhead) is seen adjacent to lesion. U = ulcer.
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Fig. 6B —66-year-old man with cancer recurrence at site of anastomosis after
low anterior resection. Two-dimensional transverse image at wide window
setting (width, 1,500 H; level, -400 H) from CTC shows undulating colonic
contour at anastomosis. Undulation is caused by ulcer and mounds
(arrowheads).
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Fig. 6C —66-year-old man with cancer recurrence at site of anastomosis after
low anterior resection. Subsequent optical colonoscopy shows corresponding
ulcerating, infiltrative lesion (arrowheads) at anastomotic site.
Surgical resection was performed, and pathology confirmed recurrence of
adenocarcinoma. U = ulcer.
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Fig. 7A —50-year-old woman with extraluminal anastomotic recurrence in
pericolic area after low anterior resection. Two-dimensional transverse image
at soft-tissue window setting (width, 400 H; level, 20 H) obtained 25 months
after surgery shows moderately enhancing infiltrative soft-tissue mass
(arrowheads) located right lateral and posterior to anastomosis.
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Fig. 7B —50-year-old woman with extraluminal anastomotic recurrence in
pericolic area after low anterior resection. Subsequent PET/CT image at
corresponding level shows hypermetabolism (arrowheads) of lesion,
confirming tumor recurrence.
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Fig. 7C —50-year-old woman with extraluminal anastomotic recurrence in
pericolic area after low anterior resection. Optical colonoscopy performed
same day as CT colonography shows no definitive evidence of mucosal recurrence
at anastomotic site and adjacent areas.
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Metachronous Colonic Lesions
Although a history of previous colon cancer is an overt risk factor for the
development of metachronous colorectal cancer and advanced adenomas, the
actual rate of metachronous cancer in cancer patients who have had curative
resection is not very high, with a reported rate of 1.3% (18/1,342 patients)
according to one meta-analysis
[8]. The diagnostic performance
of CTC in the detection of metachronous cancers (Fig.
8A,
8B,
8C) and adenomas (Fig.
9A,
9B,
9C) in postsurgical patients
has yet to be further investigated but should be similar to that of CTC in
screening patients.
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Fig. 8A —73-year-old woman with 9-mm metachronous cancer in distal ascending
colon after low anterior resection. Three-dimensional endoluminal CT
colonography (CTC) image obtained 30 months after surgery shows sessile
polypoid lesion (arrowheads) in distal ascending colon.
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Fig. 8B —73-year-old woman with 9-mm metachronous cancer in distal ascending
colon after low anterior resection. Two-dimensional multiplanar reformatted
image at wide window setting (width, 1,500 H; level, -400 H) from CTC shows
polypoid lesion (arrowheads) in distal ascending colon.
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Fig. 8C —73-year-old woman with 9-mm metachronous cancer in distal ascending
colon after low anterior resection. Subsequent optical colonoscopy shows
corresponding sessile polyp (arrowheads). Colonoscopic polypectomy
was performed, and pathology revealed metachronous adenocarcinoma.
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Fig. 9A —67-year-old man with 8-mm metachronous adenomatous polyp in rectum
after right hemicolectomy. Three-dimensional endoluminal CT colonography (CTC)
image obtained 15 months after surgery shows sessile polypoid lesion
(arrowhead) attached to Houston's valve in distal rectum.
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Fig. 9B —67-year-old man with 8-mm metachronous adenomatous polyp in rectum
after right hemicolectomy. Two-dimensional transverse image of CTC using wide
window setting (width, 1,500 H; level, -400 H) shows corresponding polypoid
lesion (arrowhead) in distal rectum.
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Fig. 9C —67-year-old man with 8-mm metachronous adenomatous polyp in rectum
after right hemicolectomy. Subsequent optical colonoscopy shows corresponding
polypoid lesion (arrowheads) with lobulated surface in distal rectum.
Polypectomy was performed, and pathology revealed villotubular adenoma.
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Distant Metastases
More than half of the recurrences after curative resection of colorectal
cancer are distant metastases to the liver and lungs
[7,
8]. Abdominal CT plays an
important role in the detection of abdominal metastasis, including hepatic
(Fig. 10A) or lymph node
(Fig. 10B) metastases. The
importance of abdominal CT is reflected in the recently revised surveillance
guideline for postsurgical colorectal cancer patients proposed by American
Society of Clinical Oncology
[1]. The guideline recommends
annual CT of the abdomen for 3 years after primary therapy for patients who
are at a high risk of recurrence
[1]. CTC performed with IV
contrast enhancement accomplishes the dual functions of abdominal CT and
colonic evaluation. Therefore, contrast-enhanced CTC may potentially be a more
efficient single technique for colorectal cancer surveillance after surgery.
Because inflammatory polyps and benign ulcers are generally not
distinguishable from adenomatous polyps or recurrences on CTC and the presence
of dysplasia in an adenomatous polyp cannot be distinguished on CTC, followup
optical colonoscopy and biopsy will be mandatory in patients with such
suspected abnormalities at CTC.
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Fig. 10A —77-year-old woman with recurrence in form of metastases in liver and
intraabdominal lymph nodes after low anterior resection. Two-dimensional
transverse CT colonography images using soft-tissue window setting (width, 400
H; level, 20 H) obtained at 26 months after surgery show metastatic mass in
liver (arrowheads, A) and metastatic lymphadenopathy in
paraaortic and retrocaval areas (arrowheads, B). Subsequent
optical colonoscopy (not shown) showed no evidence of intraluminal anastomotic
recurrence.
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Fig. 10B —77-year-old woman with recurrence in form of metastases in liver and
intraabdominal lymph nodes after low anterior resection. Two-dimensional
transverse CT colonography images using soft-tissue window setting (width, 400
H; level, 20 H) obtained at 26 months after surgery show metastatic mass in
liver (arrowheads, A) and metastatic lymphadenopathy in
paraaortic and retrocaval areas (arrowheads, B). Subsequent
optical colonoscopy (not shown) showed no evidence of intraluminal anastomotic
recurrence.
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Nevertheless, because of the low diagnostic yield of optical colonoscopy
after curative surgery for colorectal cancer (i.e., 3.2% and 1.3% rates of the
detection of anastomotic recurrence and metachronous cancer, respectively
[8], and a combined 7.6%
incidence of recurrence at the anastomosis and metachronous cancer
[11]), it would be efficient
if CTC could eliminate through screening those patients whose colon is normal.
Further large-scale studies may be needed to define the role of CTC in the
postsurgical surveillance of colorectal cancer patients.
CTC Examination of a Patient with Colostomy
CTC may be successfully performed in patients with a colostomy by using a
small catheter with a retention balloon, which is required to prevent air
leaks and to hold the catheter in place (Fig.
11A,
11B,
11C). Because of the lack of
firm supporting structures surrounding the colon in the abdominal wall and its
narrower luminal diameter compared with the rectum, wedging of the catheter
tip against the colonic wall (Fig.
12), causing colonic injury and occlusion of the tip against the
wall, often occurs during catheter advancement. Careful catheter insertion is
required to avoid this. The retention balloon should not be inflated
excessively and should be inflated only after the balloon portion of the
catheter has completely passed the colostomy stoma because of the potential of
mucosal injury and perforation when ballooning in the colostomy stoma. Digital
examination of the colostomy to assess the direction and luminal dimension of
the colon underneath the stoma should help facilitate safe catheter
placement.
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Fig. 11A —69-year-old woman with sigmoid colostomy after abdominoperineal
resection (Mile's operation) for rectal cancer. Three-dimensional
reconstruction of ray-sum view shows colon that is optimally dilated with
carbon dioxide insufflation using small-caliber catheter with retention
balloon placed through colostomy. Balloon was inflated with approximately 30
mL of air.
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Fig. 11B —69-year-old woman with sigmoid colostomy after abdominoperineal
resection (Mile's operation) for rectal cancer. Two-dimensional multiplanar
reformatted image at wide window setting (width, 1,500 H; level, -400 H)
(B) and 3D endoluminal view (C) of CT colonography show
appropriate catheter positioning and ballooning. Rectal catheter
(arrowhead) is placed in center of colon without occlusion of tip
against colonic wall. B = balloon.
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Fig. 11C —69-year-old woman with sigmoid colostomy after abdominoperineal
resection (Mile's operation) for rectal cancer. Two-dimensional multiplanar
reformatted image at wide window setting (width, 1,500 H; level, -400 H)
(B) and 3D endoluminal view (C) of CT colonography show
appropriate catheter positioning and ballooning. Rectal catheter
(arrowhead) is placed in center of colon without occlusion of tip
against colonic wall. B = balloon.
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Fig. 12 —60-year-old woman with sigmoid colostomy after abdominoperineal
resection (Mile's operation) for rectal cancer. Two-dimensional multiplanar
reformatted image at wide window setting (width, 1,500 H; level, -400 H) shows
inappropriate placement of catheter. Catheter tip (arrowhead) is
pushing against colonic wall. Retention balloon (B) is also overdistended and
superficially located.
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Fig. 4C —35-year-old man with 5-mm extruded surgical staple in colocolic
anastomosis after low anterior resection. Optical colonoscopy clearly shows
pseudolesion—that is, polyp-mimicking appearance of extruded surgical
staple (arrowhead) on 3D CTC.
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Abstract
Introduction
