Dr/ ABD ALLAH NAZEER. MD.

Radiological imaging of diverticulardisease and diverticulitis.

Definitions:Diverticulum–sac-like protrusion of the colonic wall that consists of mucosa, submucosa, serosaDiverticulosis–the presence of diverticula, often an incidental findingDiverticulitis–inflammation resulting from a perforation of a diverticulumDiverticular Hemorrhage–Diverticular bleeding usually not associated with diverticulitis

EpidemiologyAge: Affects <5% before 40yo-30% at 60yo-65% at 80yo.20% of those present with sxs.

Risk factors:“disease of Western Civilization”low fiber constipation. obesity, lack of physical activity.NSAIDs.Smoking.

Pathophysiology95% of diverticuli occur in the sigmoid In Asians, 70% present as R-sided pain

Laplace’s law: (P=T/r), sigmoid has the smallest diameter and largest pressures. Segmentation exaggerated-increase in intraluminal P

Colonic diverticular disease most commonly affects the

rectosigmoid colon. The pathophysiology of diverticular disease is likely to be related to a complex relationship between age, dietary factors, colon structure and motility. Diverticular disease is traditionally accepted as a condition of Western civilization. The condition is rarely encountered in populations inhabiting rural regions with Asia and Africa. Raised intra-colonic pressure occurs as an adaptative mechanism to a low-fibre diet, which is associated with an increased transit time. This is associated with increased desiccation and viscosity of the fecal content, promoting the development of diverticula. Diverticulitis is the most common clinical complication of colonic diverticular disease. Diverticulitis results from obstruction at the neck of a diverticulum leading to localized inflammation. Smoking is associated with an increased risk of complications in diverticular disease. Opioid analgesics, non-steroidal anti-inflammatory drugs and corticosteroids are all positively associated with an increased risk of perforated colonic diverticular disease. Calcium channel blockers, which reduce colonic contractility and tone, protect against perforation in colonic diverticular disease.

Radiological imaging:Plain abdominal X-rayOnly to exclude significant abnormalities in intestinal passage and free intra-abdominal gas.Not suitable for detecting diverticulitis.SonographyGenerally available and cheap method of investigationHighly dependent on the ease of imaging and the experience of the Practitioner Complicated disease is difficult to recognize (pelvic abscesses, fistulas, etc.)Mono-contrast barium enema, Inadequately sensitive for detecting peri diverticular inflammation, abscesses, and fistulas.Only recommended when CT not available for organizational reasons.Computed tomographyMethod of choice, also for recognition of the complicated disease CT guided drainage is possible.Magnetic resonance imagingUsed in trials, routine use still prematureColonoscopyMainly indicated for the reliable exclusion of tumors – during periods free of inflammation.Angiography.

X-ray investigation /colonographyEither double-contrast or mono-contrast techniques may be used for conventional X-ray investigations of the colon. The reliability of both procedures depends directly on how well the patient is prepared. The double-contrast technique with aqueous barium sulphate solution is principally restricted to the post acute phase (after at least 7 days). This technique is contraindicated for acute diagnosis, as there is a risk of perforation –indeed a covered perforation may already have developed – and this can lead to loss of barium, with the risk of barium peritonitis. In addition, contrast medium containing barium may remain in the intestine for long periods and may complicate an operation should this become necessary. The imaging of the diverticulum is also adequate, although the inflamed diverticulum is only observed as "spicule-like" mucous membrane avulsions, due to the obstruction in the diverticulum neck. The segmental extension of the inflammation can be well documented. Free perforations can be easily recognized by the detection of extra-intestinal contrast medium. On the other hand, it is difficult to detect a covered perforation. This can often only be indirectly inferred from the extra-mural indentations of the intestinal wall from small pericolic micro-abscesses. A colon contrast enema often gives inadequate images of peridiverticular inflammatory reactions and of changes in complicated diverticulitis. The colon contrast medium investigation only detected a peridiverticular abscess in 29% of cases demonstrated by computed tomography. Moreover, the overall extent of the inflammatory reaction is markedly underestimated by both procedures. According to the literature, the sensitivity of the two procedures lies between 71% and 94% (13), with specificities between 61% (13) and 72%

SonographySonography – including duplex sonography and harmonic imaging – is a widely available imaging procedure. In principle, the patient should fast before the investigation, but no other preparation is necessary. After a preliminary investigation of the whole abdomen, a specific image is taken of the intestinal structures with a high resolving linear transducer (7.5 to 10 MHz). Sonographic studies have shown that localized thickening of the intestinal wall can be imaged with high sensitivity. In particular, the so-called dome sign is thought to be highly specific for diverticulitis. This is a hypoechogenic hemispherical lesion, eccentrically positioned near the intestinal wall. The center of this lesion is hyperechogenic, corresponding to the inflamed diverticulum. According to the literature, the sensitivity of sonography for diverticulitis lies between 79% and 98% and its specificity, between 80% and 98%. Direct imaging of the inflamed diverticulum is moderately sensitive (77%), but highly specific (99%) for diverticulitis. Sonography's sensitivity for the uncomplicated form is as high as 96%. However, imaging the inflamed diverticulum is often not possible, particularly in complicated diverticulitis. In addition, there is often an increase in the echogenicity of the pericolic fat tissue, corresponding to inflammatory edematous changes (sensitivity: 15% to 50%). Additional sonographic signs of complicated colonic diverticulitis include pathological cockades with a very narrow lumen (inflammatory stenosis) and the direct detection of peridiverticular abscesses. These may be hypoechogenic and also exhibit an intermediate reflection pattern, with or without gas (sensitivity about 40%).

Computed tomographyComputed tomography has become the diagnostic gold standard. It is performed as spiral-CT on single or multi detector row CT (MDCT) scanners. The patient is then given both an oral and a rectal dose of contrast medium (CM). The investigation is performed afterintravenous administration of contrast medium in a portal vein CM phase. Intravenouslyadministered spasmolytics can also greatly facilitate intestinal imaging. In modern MDCT,primary layer collimations of 0.6 to 1.5 mm are primarily selected. In addition, multiplanar reformatting can be used to improve the presentation and documentation of the findings.Data acquisition is performed from the level of the sub-phrenic space to the symphysispubis, with the aim of directly detecting any alternative diagnosis which mightimitate the symptoms of diverticulitis. Typical changes found in diverticulitis are symmetrical thickening of the inflamed intestinal wall (normal thickness about 3 to 5 mm), with segment size of > 10 cm (sensitivity 95%, specificity 31%), and diffuse edematous infiltration of the pericolic fat tissue (sensitivity 95%, specificity 35%). found fluid accumulation around the root of the mesentery and increased vascular injection in the mesosigmoid, with the high predictive values of 89% and 100% for diverticulitis. Free perforations can be imaged from the intraluminal gas or with contrast medium. Abscesses are diagnosed by computed tomography in 100% of cases. Even with computed tomography, detection of fistulae is difficult. Colovesicular fistulae or fistulae between the colon and uterus can be indirectly inferred from the gas in the area of the urinary bladder and/or the uterus, if there has been no prior use of the instruments which might have interfered (e.g. a urinary bladder catheter). Computed tomography can also detect rare complications, such as septic thrombosis of the mesenteric vein

Magnetic resonance imagingBecause of the lack of radiation exposure and the high soft tissue contrast, MRI has become established as an alternative to computed tomography for intestinal imaging, particularly in younger patients and for some specific indications. 1.5 Tesla MR tomographs are usually used. Imaging mostly employs either body coils or highly resolving surface coils.There is not yet any reliably established and standardized procedure for the diagnosis of diverticulitis. There has been wider experience with imaging processes linked to chronic inflammatory bowel disease, particularly Crohn's disease. For these measurements, intestinal contrast is achieved using 2.5% mannitol solution administered orally. The detection of diverticulitis was based not only on intestinal wall thickening, but also locally increased uptake of contrast medium and pericolic inflammatory reactions. Magnetic resonance imaging gives good images of the pericolic inflammatory reactions.

ColonoscopyEndoscopy is of most use in diverticulitis in the intervals free of inflammation. This method can reliably exclude colonic cancer and other inflammatory diseases of the colon.

AngiographyDiverticular bleeding in the colon is the most frequent cause of lower gastrointestinal bleeding. About 3% to 15% of patients with diverticulosis suffer bleeding in the course of their lives this is caused by rupture of the vasa recta. This event occurs independently of acute or chronic inflammatory reactions and tends to cease spontaneously. For reasons which remain unclear, this is much more frequent in diverticulae of the ascending colon than in sigmoid diverticulae. The primary procedure for diagnosis and treatment is currently endoscopy. If bleeding cannot be controlled, primary surgical treatment is indicated. There are also rare cases in which the bleeding point can be localized with digital subtraction angiography, possibly combined with CT-angiography using an angiographic catheter in the mesenteric artery. In some cases superselective catheterization and embolization of the bleeding vessel is possible. The success rates for primary hemostasis vary between 83% and 94%. 27% to 34% of patients suffer renewed bleeding, despite successful primary embolization. It should always be born in mind that intestinal wall ischemia is a possible complication.

Meckel's diverticulitis. Supine abdominal radiograph shows cholelithiasis (arrow) and dilated loops of small bowel (arrowhead)

Upright abdominal radiograph shows dilated loops of small bowel, with multiple air fluid levels (arrows

Barium enemas of manifestations of diverticulitis, (A) Acute diverticulitis with edema (arrow) of the bowel wall. (B) Intramural sinus tract (arrow) in acute diverticulitis. (C) Confined perforation or abscess (arrow) in acute diverticulitis.

Radiograph showing extensive diverticulosis.

Radiological evidence of acute diverticulitis (arrows) using water-soluble contrast medium.

Sigmoid diverticulitis at sonography. A hypoechoic thickened diverticulum is surrounded by hyperechoic inflamed fat (arrows).

Right-sided colonic diverticulitis. A, Unenhanced CT shows extensive with fat-standing along the cecal wall (arrowheads), and a normal appendix (arrow). B, Sonography reveals the cause of the inflammation by depicting an inflamed cecal diverticulum (arrow) centred in the hyperechoic fat.

Sigmoid diverticulitis: sigmoid colon with multiple diverticula, significant mural thickening (arrow) and pericolic fat stranding (circles).

Mild diverticulitis of the sigmoid colon. CT demonstrates evidence of multiple diverticula in association with mild bowel wall thickening and pericolic fat stranding.

Moderate diverticulitis of the distal descending colon. CT shows moderate bowel wall thickening in association with marked stranding and phlegmon formation.

Transverse CT of the lower abdomen post-oral and intravenous contrast media demonstrates marked stranding (open arrow) surrounding a thickened diverticulum (closed arrow) within the right colon. The features are pathognomonic of acute diverticulitis.

Computed tomographic scan revealing marked eccentric thickening of the wall of the ascending colon and pericolic inflammatory fat and fascia (white arrowheads). Fecal material is seen at the center of the inflammatory complex indicating an inflamed diverticulum (black arrows).

MRI images for sigmoid diverticulitis.

Magnetic resonance image (MRI) of right-sided diverticulitis.

Computed tomographic (CT) findings in acute diverticulitis (arrow) with accumulation of pus (abscess) around the bowel (x).

Sigmoid diverticulitis with abscess formation: sigmoid colon displaying diverticulosis mural thickening, and pericolic fat stranding (arrow). Adjacent low attenuation, septated collection (circle) representing abscess formation.

(a) Transverse CT in a patient with sigmoiddiverticulitis demonstrates a large pelvic abscess with anair fluid level situated in the pouch of Douglas. (b) An 8 Fpigtail drainage catheter has now been successfullyplaced trans-gluteallyinto the collection. The collectionresolved fully on subsequent imaging.

Transverse CT post-intravenous contrast medium in a patient with acute diverticulitis shows a 5 cm abscess cavity in the left iliac fossa (straight arrow). There is a pocket of air within the abscess cavity (curved arrow) indicating communication to bowel. Diverticulitis is present within the sigmoid colon as evidenced by thickening of the bowel wall and stranding.

Severe diverticulitis of the recto-sigmoidcolon with localized perforation and abscess formation.(a) Transverse CT through the lower pelvis demonstratesmarked thickening of the proximal contrast-filled rectum(arrow). There is extensive stranding of the mesocolon.(b) At a higher level, there is a localized perforation withabscess formation (arrow).

Radiological visualization of an incompletefistula (arrow) in a patient with diverticulitis.

Transverse CT through the pelvis in a patient with diverticulitis demonstrates a localized perforation in the left side of the pelvis. A tract of air can be seen connecting the sigmoid colon to the air collection (arrow).

Perforated sigmoid diverticulitis: sigmoid colon displaying diverticulosis, mural thickening and pericolic inflammatory fat stranding (arrow) with adjacent collection of intra-abdominal free air and adjacent inflammatory fat stranding (circle), again representative of active diverticulitis with perforation.

Patient with sigmoid diverticulitis and a colovesical fistula. There is freeair within the anterior aspect of the bladder (arrow). The patient had no

recent bladder instrumentation. There is also associated thickening of the sigmoid colon, which is adherent to the left side of the bladder.

MRI images with Colovesical fistula is a devastating complication, usually secondary to diverticulitis.

CT scans of manifestations of diverticulitis, (A) Contained abscess (arrow) in severe sigmoid diverticulitis. (B) Large air-containing abscess (arrow) in subacute diverticulitis. (C) Large diverticular abscess (arrow) with penetration into retroperitoneal structures and extending through abdominal wall into subcutaneous tissue.

a) Transverse CT through the pelvis demonstratesacute diverticulitis of the proximal sigmoid colonwith bowel wall thickening, diverticula and some localized free air (arrow). (b) Magnified view at a higher level shows air within the branches of the superior mesenteric vein (arrow). (c) There is portal venous air within the liver. Despite these findings, the patient was not acutelyunwell and made a full recovery after surgery.

Transverse CT through the upper abdomen in a patient with perforated diverticulitis viewed on lung windows. There is extensive free intra-peritoneal air with visualization of the falciform ligament (arrow). There is also extensive retroperitoneal air and subcutaneous air on the left side.

Transverse CT in a patient with palpable subcutaneous emphysema and a known past history of diverticulitis. There is extensive air extending from adjacent to the descending colon through the abdominal wall into the subcutaneous tissues.

Selective Angiography Diverticular Bleeding.

Technetium-99m-tagged red blood cell scan showing extravasation of tagged red blood cells into the colon lumen in the sigmoid and descending colon, with radionuclide collection in the descending colon (arrow).

Colonoscopic image of a blood-filled colon with clots and

diverticula (arrows).

ConclusionsCT is a highly specific and sensitive imaging method in the evaluation of acute diverticulitis. It is the most accurate imaging technique available for the assessment of the inflammatory process. CT-guided percutaneous drainage of diverticular abscesses plays a crucial role in improving patient outcome.

Thank You.