Imaging the operated colon using water-enema multidetector CT, with emphasis on surgical anastomoses
Imaging the operated colon using water-enema multidetector CT, with emphasis on surgical anastomoses
Massimo Tonolini 0 1
Sonia Ippolito 0 1
0 Department of Radiology, BLuigi Sacco
1 Massimo Tonolini
2 University Hospital , Via G.B. Grassi 74, 20157 Milan , Italy
Water-enema multidetector CT (WE-MDCT) provides a detailed multiplanar visualisation of mural, intra- and extraluminal abnormalities of the large bowel, relying on preliminary bowel cleansing, retrograde luminal distension, pharmacological hypotonisation and intravenous contrast enhancement. In patients with a history of colorectal surgery for either carcinoma or Crohn's disease (CD), WE-MDCT may also be performed via a colostomy, which allows depicting the anatomy and position of the residual large bowel and evaluates the calibre, length, mural and extraluminal features of luminal strictures. Therefore, WEMDCT may prove useful as a complementary technique after incomplete or inconclusive colonoscopy to assess features and suspected abnormalities of the surgical anastomosis, particularly when endoscopic or surgical interventions are being planned. This pictorial essay presents the WE-MDCT technique and pitfalls, the expected appearances after different colic surgeries and the imaging features of benign anastomotic disorders (fibrotic stricture, kinking, inflammatory ulcer) and of locally recurrent tumours and CD. Teaching points Water-enema multidetector CT (WE-MDCT) effectively visualises the operated colon Complementary to endoscopy, WE-MDCT may helpfully depict abnormalities of surgical anastomoses WE-MDCT allows assessment of strictures' features and abnormalities of the upstream bowel Technical pitfalls, normal postsurgical findings and benign anastomotic disorders are presented WE-MDCT allows detecting relapsing Crohn's disease, recurrent and metachronous tumours
Computed tomography (CT); Colonoscopy; Colorectal surgery; Anastomosis; Stricture; Colorectal carcinoma; Crohn's disease
Introduction
Since the first description by Gossios et al. [
1
], water-enema
multidetector CT (WE-MDCT) has developed into a
technique dedicated to visualising the large bowel, which relies
on a combination of preliminary bowel cleansing, retrograde
fluid-attenuation luminal distension, pharmacological
hypotonisation and intravenous contrast enhancement.
Although relatively simple to perform and interpret,
WEMDCT is increasingly considered the most accurate imaging
technique to comprehensively stage colorectal carcinoma
*
(CRC) and has very high sensitivity (98.6–99%) for lesions
measuring at least 1 cm and good agreement between CT
features and histopathology [
2–5
]. Moreover, WE-MDCT
has been effectively adopted to diagnose bowel endometriosis
[
6–8
], colonic diverticular disease [9] and chronic
inflammatory bowel diseases (IBD) [
9–13
].
Following colorectal surgery for either benign or
malignant processes, optical colonoscopy remains the gold
standard technique to assess the anastomotic site and residual
large bowel and to identify recurrence of resected disease.
However, in operated patients endoscopy is often
hampered by postsurgical adhesions, sharp bowel angulations,
bowel kinking, poor bowel preparation and anastomotic
strictures (AS). WE-MDCT allows reliable measurement
of the colonic wall thickness in normal and pathological
conditions, and provides a detailed multiplanar assessment
of mural, intra- and extraluminal abnormalities of the large
bowel. Therefore, its use is appealing to investigate the
operated colon, particularly after unsuccessful, incomplete
or inconclusive endoscopy.
Based upon personal experience at a tertiary hospital that
performs IBD and oncologic surgery, this pictorial essay presents the
WE-MDCT technique and pitfalls, the expected appearances after
various colon surgeries and the imaging features of benign
anastomotic disorders, recurrent tumours and Crohn’s disease (CD).
Water enema multidetector CT technique and interpretation
Acquisition technique
Retrograde colonic distension is contraindicated in the
presence of high-grade bowel obstruction, when a standard
contrast-enhanced CT acquisition reliably investigates the site
and cause of obstruction, thanks to the pre-existent bowel
dilatation with intraluminal fluid. Before WE-MDCT, bowel
cleansing is obtained using an iso-osmolar non-absorbable
laxative solution (typically 4–6 doses of polyethylene glycol
dissolved in 500 ml water per dose) the day before the
examination, in association with a low-fibre diet for 3 days. Patients
fast for 12 h after a liquid dinner the evening before the
scheduled examination [
9
].
The patient is positioned on the CT scanner table and is
instructed to turn to the left lateral decubitus. A lubricated
enema tube is gently inserted into the rectum and connected
to a bag that contains 1.5–2 l of warm tap water. Retrograde
colonic distension through gravity is obtained within a few
minutes and is stopped when the patient com (...truncated)