The Sectional and Isotopic Imaging Modalities

The sectional imaging modalities have not only confirmed the pathways of extension but have provided a striking advance in the diagnosis and localization of in-

27 40 74 70 70

traperitoneal abscesses.

Ultrasonography has a sensitivity of almost 95% and a specificity approaching 100% if the study is not limited by bowel gas, obesity, and surgical wounds and band-ages.80-82 The absence of ionizing radiation makes it particularly safe in evaluating children and young women.

Abscesses present generally as irregular fluid collections with indistinct margins. Ultrasonography is too time consuming, however, to serve as a survey evaluation of the entire abdomen in suspected abscesses; it is best used when localizing features have been indicated.

Computed tomography may reveal an abscess as a mass with low attenuation value displacing surrounding structures, occasionally with a peripheral rim of higher density that may show contrast enhancement; there may be thickening or obliteration of neighboring fascial planes, and the frequent presence of gas bubbles or air-fluid levels usually allows definitive diagnosis. Computed tomography may diagnose and accurately define the extent of involvement in up to 96-100% of cases,

depending on the size of the abscess. ' ' It provides precise differentiation with excellent anatomic detail. Radiation dosage is comparable to that from an average barium study. The characteristic signs on ultrasonography and CT usually permit clear distinction from other postoperative fluid collections such as seroma and lymphocysts.

Increasing clinical experience has shown that MR imaging has high diagnostic accuracy in the evaluation text continues on page 124

Phrenicocolic Ligament

Fig. 3—114. Abscess localization in postoperative neocompartment.

Excision of gastrocolic ligament (GCL), transverse mesocolon (TM), and phrenicocolic ligament (PCL), associated with colectomy. Lateral and frontal diagrams (a and b) and CT (c and d) after left colectomy illustrate abscess in a newly established lesser sac plus an infra/paracolic compartment (1). An intact gastrosplenic ligament (arrows) demarcates this from an abscess in the left subphrenic space (2). Sp = spleen; St = stomach; L = liver; C = colon; LS = lesser sac; asterisk = duodenojejunal flexure. (Reproduced from Kumpan.27)

Fig. 3—114. Abscess localization in postoperative neocompartment.

Excision of gastrocolic ligament (GCL), transverse mesocolon (TM), and phrenicocolic ligament (PCL), associated with colectomy. Lateral and frontal diagrams (a and b) and CT (c and d) after left colectomy illustrate abscess in a newly established lesser sac plus an infra/paracolic compartment (1). An intact gastrosplenic ligament (arrows) demarcates this from an abscess in the left subphrenic space (2). Sp = spleen; St = stomach; L = liver; C = colon; LS = lesser sac; asterisk = duodenojejunal flexure. (Reproduced from Kumpan.27)

Colon Abscess Pictures

Fig. 3-115. Abscess secondary to retained laparotomy pad.

The abscess is shown by swirled pattern of gas loculations, and the pad demonstrates localized opacities. The abscess distorts and compresses the ascending colon.

Fig. 3-115. Abscess secondary to retained laparotomy pad.

The abscess is shown by swirled pattern of gas loculations, and the pad demonstrates localized opacities. The abscess distorts and compresses the ascending colon.

Fig. 3-116. Three different examples of retained surgical sponges and towels shown by CT.

(a) Contrast-enhanced CT shows a spherical, sharply defined mass with a thin dense wall and containing multiple gas bubbles in the supramesocolic space beneath the tail of the pancreas. A retained sponge was confirmed at surgery. An aorticoiliac bypass is present.

(b) Contrast-enhanced CT shows a low-density mass containing multiple linear infolded densities. Calcifications in the wall of the mass are present. A retained surgical towel was found at surgery within a subdiaphragmatic abscess penetrating the right lobe of the liver and the right hemidiaphragm.

(c) Contrast-enhanced CT demonstrates a cystic spherical mass with well-defined borders containing dense, linear contiguous shadows having a folded appearance. At surgery, a retained towel in a right subphrenic sterile abscess was discovered. (Reproduced from Buy et al.63)

Retained Lap SpongeHepatoduodenal Ligament

Fig. 3-117. Abscess (infected biloma) of the hepatoduodenal ligament.

(a) Ultrasonography, transverse view, shows echogenic fluid collection (black arrows) encasing the main portal vein (open arrow). The common bile duct (B) is dilated, and cholecysto-choledocholithiasis was noted (not shown). G = gallbladder; Ao = abdominal aorta.

(b) At autopsy, greenish biliary abscess (arrows) extends along the portal vein (PV) within the hepatoduodenal ligament from the site of a minute disruption of the right hepatic duct. B = common bile duct.

(Reproduced from Mori et al. )

Fig. 3-117. Abscess (infected biloma) of the hepatoduodenal ligament.

(a) Ultrasonography, transverse view, shows echogenic fluid collection (black arrows) encasing the main portal vein (open arrow). The common bile duct (B) is dilated, and cholecysto-choledocholithiasis was noted (not shown). G = gallbladder; Ao = abdominal aorta.

(b) At autopsy, greenish biliary abscess (arrows) extends along the portal vein (PV) within the hepatoduodenal ligament from the site of a minute disruption of the right hepatic duct. B = common bile duct.

(Reproduced from Mori et al. )

Duodenocolic Ligament

Fig. 3—118. Extension via the hepatoduodenal ligament to the duodenocolic ligament from an infected biloma secondary to acute cholecystitis.

(a) CT through the inferior insertion of the hepatoduodenal ligament shows a collection (arrow) around the duodenum (d).

A calcified stone (arrowhead) is seen in the common bile duct. The fat plane around the pancreas (p) is preserved.

(b) In a more caudal section, the collection (arrow) lies anterolateral to the descending duodenum, in the duodenocolic ligament.

(Reproduced from Arenas et al.75)

Fig. 3—118. Extension via the hepatoduodenal ligament to the duodenocolic ligament from an infected biloma secondary to acute cholecystitis.

(a) CT through the inferior insertion of the hepatoduodenal ligament shows a collection (arrow) around the duodenum (d).

A calcified stone (arrowhead) is seen in the common bile duct. The fat plane around the pancreas (p) is preserved.

(b) In a more caudal section, the collection (arrow) lies anterolateral to the descending duodenum, in the duodenocolic ligament.

(Reproduced from Arenas et al.75)

Liver Abscess Mri

Fig. 3-119. Abscess of the gastrohepatic ligament, extending from a hepatic abscess.

The liver abscess is secondary to transcatheter embolotherapy for a hepatocellular carcinoma located in the posteroinferior portion of the lateral segment of the liver.

Contrast-enhanced CT shows a fluid collection (arrows) between the posteroinferior aspect of the left lobe of the liver (L) and the lesser curvature of the stomach (St) that is contiguous with the necrotic tumor (T) of the liver. (Reproduced from Mori, et al.74)

Fig. 3-120. Abscess of the gastrohepatic ligament, hepatoduodenal ligament, and ligamentum teres extending from an abscess in the posteromedial portion of the lateral segment of the liver. (a) Ultrasonography shows abscess in the posterior portion of the lateral segment (Abs) of the left lobe of the liver. Contiguous hypoechoic zones (arrows) are present between the left lobe of the liver (L) and the stomach (St) and between the stomach and the pancreas (P). These zones reflect abscesses (fluid collections) of the gastrohepatic ligament and in the lesser sac, respectively. Ao = abdominal aorta.

(b and c) CT scans after the administration of contrast medium demonstrate fluid collections in the gastrohepatic ligament (curved closed arrows), the hepatoduodenal ligament (curved open arrow), and the ligamentum teres (black arrow). Collections may lie partially within the fissure for ligamen-tum teres and the superior recess of the lesser sac. St = stomach. (Reproduced from Mori, et al.74)

Collection Purulente AnalCollection Purulente Anal

Fig. 3-121. Abscess of the falciform ligament extending from a hepatic abscess.

(a and b) CT in a patient with fever and leukocytosis following anal surgery shows a subcapsular hepatic collection (A) extending into the falciform ligament. Fine-needle aspiration yielded purulent material. (Reproduced from Arenas et al.75)

Fig. 3-121. Abscess of the falciform ligament extending from a hepatic abscess.

(a and b) CT in a patient with fever and leukocytosis following anal surgery shows a subcapsular hepatic collection (A) extending into the falciform ligament. Fine-needle aspiration yielded purulent material. (Reproduced from Arenas et al.75)

of acute intraperitoneal abscesses. They are best demonstrated on gadolinium-enhanced T1-weighted fat-suppressed images as well-defined fluid collections with

peripheral rim enhancement.

The overall accuracy for gallium-67 examination is highly dependent on the type of patient studied.82,86-88 The presence of a surgical incision as well as nonspecific uptake in inflammatory but nonsuppurative lesions, bowel, and tumors may be mistaken for an abscess. Despite the use of cleansing enemas for repeated gallium scans, differentiation of an abscess from normal bowel may still occasionally be difficult. The technique provides relatively poor resolution and has a higher false-positive and false-negative rate than either ultrasonog-raphy or CT. Although 6-hour delay scans have been advocated,86 they are difficult to interpret because of high background radioactivity. A reliable diagnosis may be made from the 24-hour study, but 48- and sometimes 72-hour scans are necessary. This contrasts with the immediate results obtainable from ultrasonography and CT.

In111-labeled leukocyte scanning, in contrast, results in superior image quality; moreover, no indium-111 normally appears in the gastrointestinal tract or its contents or in the urinary collection system. However, intense uptake may occur in recent hematomas and less intense accumulations in any acute inflammatory lesion and in some noninflammatory states as well.89

Isotopic scans are particularly useful as an initial survey in suspected abscesses when there are no localizing clinical signs and plain film findings are negative or equivocal. Newer agents include technetium-99m (99mTc)-HMPAO-labeled leukocytes, 99mTc-labeled chemotactic peptides, 111In-labeled polyclonal immunoglobulin G, and 99mTc-labeled monoclonal antibody.

Currently, patients who are not critically ill and have no focal signs of an abscess may be initially imaged by an indium-labeled leukocyte scan. In critically ill patients, however, CT and ultrasound provide a more rapid and specific diagnosis. Computed tomography obviates many of the practical disadvantages of ultrasound in such patients, displays the relationship of an abscess to surrounding structures, and permits planning of the most appropriate route for percutaneous or surgical drainage.

Natural Weight Loss

Natural Weight Loss

I already know two things about you. You are an intelligent person who has a weighty problem. I know that you are intelligent because you are seeking help to solve your problem and that is always the second step to solving a problem. The first one is acknowledging that there is, in fact, a problem that needs to be solved.

Get My Free Ebook


Post a comment