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15.03.2012 УЗИ правой подвздошной области и КТ Брюшной полости.

Женщина 32 года, поступила с жалобами на сильные боли в тазу справа. Болеет 4 дня, ранее не обращалась т.к. боится операции (со слов). На данный момент выраженные боли справа в подвздошной области, из за боли невозможно адекватно смотреть датчиком с применением компрессии. Получил всего пару сонограмм. Ваше мнение и какова тактика?

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 Здесь наверно большим

 Здесь наверно большим критерием будет яркое усиление слизистой оболочки с утолщенным подслизистым слоем

Я за терминальный илеит.

 
 #

Как указали выше коллеги,

Как указали выше коллеги, имеется патология терминального отдела подвздошной кишки и илеа-цекального клапана, представленной в виде утолщения стенок и отека Баугиньевой заслонки. Как видите, коллеги УЗИсты высказывавшиеся за острый аппендицит с рекомендацией оперировать немного погорячились. Выводы я думаю понятны. Пациентке выполнили колоноскопию и взяли биопсию, завтра будет результат.

 

 

Очень рекомендую ознакомится с ниже приведенной по КТ диагностике патологии илеа-цекальной области:

 

Multi–Detector Row CT: Spectrum of Diseases Involving the Ileocecal Area

  1. Jean-Michel Tubiana, MD

+ Author Affiliations


  1. 1From the Department of Radiology, Hôpital Saint-Antoine, 184 rue du Faubourg Saint-Antoine, 75571 Paris Cedex 12, France (C.H., M.D.C., A.B., L. Azizi, M.L., L. Arrivé, J.M.T.); and the Department of Medicine, Université Paris-Descartes, Paris, France (C.H.). Presented as an education exhibit at the 2003 RSNA Annual Meeting. Received October 26, 2004; revision requested January 5, 2005; final revision received July 1; accepted July 26. All authors have no financial relationships to disclose.
  1. Address correspondence to
    C.H. (e-mail: christine.hoeffel@sat.ap-hop-paris.fr).

Abstract

The ileocecal area is a relatively short segment of the gastrointestinal tract but may be affected by pathologic conditions that are either common throughout the gastrointestinal system or exclusive to this area. These conditions include benign and malignant tumors, inflammatory processes (appendicitis, diverticulitis, epiploic appendagitis, Crohn disease), infectious diseases, and miscellaneous conditions (cecal ischemia, typhlitis, cecal volvulus, duplication cyst). The various components of the ileocecal area (cecum, appendix, ileocecal valve, terminal ileum) are close to one another, so that these conditions may involve more than one anatomic structure, thereby creating a diagnostic dilemma. The evaluation of various parameters (eg, stratified enhancement pattern of the thickened bowel wall, degree of thickening, extent and location of bowel wall involvement, degree of fat stranding relative to the degree of wall thickening) and associated findings (lymph nodes, mesenteric stranding, abscess and sinus tracts, fatty proliferation, solid organ abnormalities) will help narrow the differential diagnosis. Multi–detector row computed tomography (CT) is considered the best imaging examination for the evaluation of the ileocecal area. Consequently, the radiologist should be familiar with the multi–detector row CT features of the spectrum of diseases affecting this area to help ensure correct diagnosis and appropriate treatment.

© RSNA, 2006

LEARNING OBJECTIVES FOR TEST 4

After reading this article and taking the test, the reader will be able to:

  • List the main tumoral and nontumoral conditions affecting the ileocecal area.

  • Describe the clinical and radiologic features of inflammatory conditions of the ileocecal area.

  • Identify the main radiologic features that help differentiate between inflammatory and malignant processes of the ileocecal area.

 

Introduction

A great variety of diseases may involve the ileocecal area. This area includes the cecum, terminal ileum, ileocecal valve, and appendix. Conditions involving this region have a propensity to affect all or part of the aforementioned segments; thus, making the diagnosis may be difficult. These conditions are responsible for a significant percentage of surgical admissions of patients with acute abdomen, mainly those patients who present with acute right lower quadrant pain. At present, computed tomography (CT) is considered a first-line modality for the evaluation of the ileocecal area. In this article, we discuss and illustrate the multi–detector row CT features of a wide spectrum of conditions affecting the ileocecal area, focusing on diseases that are confined to this area. In addition, we discuss the role that multi–detector row CT may play in narrowing the differential diagnosis, with emphasis on cases in which disease involves two or more segments and on findings that may allow differentiation.

CT Technique

CT was performed using a four–detector row CT scanner (Somatom Volume Zoom; Siemens Medical Solutions, Erlangen, Germany) with a 0.5-second tube rotation, and interactive reformation was performed on a CT-dedicated Siemens 3D Virtuoso workstation. We normally used a detector collimation of 2.5 mm, a section thickness of 3 mm, and a section reconstruction interval of 2 mm. We injected 120 mL of non-ionic contrast material intravenously at a rate of 3 mL/sec, and images were acquired in the portal phase in most cases. Because the majority of lesions were discovered in an emergency context, scanning protocol with respect to oral or rectal administration of water or contrast material varied depending on the clinically suspected abnormality.

Diagnostic Considerations

In diseases involving the ileocecal area, the evaluation of various CT features will lead to a more accurate differential diagnosis (Table 1) (1).

Table 1. Diagnostic Multi–Detector Row CT Features of Ileocecal Diseases

A stratified enhancement pattern in a thickened segment of bowel wall is used to exclude malignant conditions and is, therefore, a very important criterion for establishing the diagnosis. Such a pattern may have a “double halo” or “target” configuration.

Another variable that aids in establishing the diagnosis is the degree of thickening. In general, benign conditions result in bowel wall thickening of less than 2 cm, whereas wall thickening greater than 3 cm usually indicates a neoplastic condition. However, entities that cause mild bowel wall thickening often overlap, and wall thickening may be marked in infectious or ischemic processes (2).

The extent and location of bowel wall involvement should also be evaluated. Although inflammatory or neoplastic conditions may overlap in terms of the length of bowel involved, the analysis helps in narrowing the differential diagnosis: With few exceptions (mainly lymphoma), long segments of involvement indicate a benign condition.

When perienteric fat stranding is seen adjacent to a thickened bowel segment, an inflammatory process should be suspected. When the perienteric fat adjacent to a thickened bowel segment is normal, an acute inflammatory condition is less likely. Fat stranding that is disproportionately more severe than the degree of wall thickening is one of the findings that allow differentiation between inflammatory diseases and suggests diverticulitis, appendicitis, or epiploic appendagitis (3).

Associated findings include lymph nodes; mesenteric stranding and calcification; abscess, sinus tracts, and fistulas; proliferation of fat; vascular occlusion; and solid organ abnormalities.

Tumors of the Ileocecal Area

CT features that may aid in differentiating between tumors of the ileocecal area are listed in Table 2.

Table 2. Diagnostic Multi–Detector Row CT Features of Ileocecal Tumors

Primary Malignant Tumors

Adenocarcinomas.—Adenocarcinomas of the cecum account for one-fourth of all colic adenocarcinomas (4). They have the same general and multi–detector row CT features as all other colic adenocarcinomas, including marked asymmetric colic wall thickening, short segment involvement, and abrupt change from normal to abnormal segments of colon. However, cecal adenocarcinomas have a tendency to be large, polypoid, and bulky and may act as the lead point for an intussusception. Although they may occupy a large proportion of the colic lumen, they rarely cause obstruction and often grow without clinical manifestations for long periods of time. Cecal adenocarcinomas may demonstrate mild local infiltration, even without perforation (Fig 1) (5). However, wall thickening is more severe relative to pericolic infiltration than in most acute inflammatory diseases, particularly diverticulitis. The distal ileum may be affected and abnormally thickened in up to 10% of patients with right colic cancer as a result of tumor extension or, less commonly, a nontumoral process (congestion and edema) (6).

Figure 1.  Mucinous colic adenocarcinoma in a 49-year-old man. Coronal oblique reformatted multi–detector row CT image shows a bulky, irregular heterogeneous mass (arrows) involving both the cecum and the terminal ileum with abrupt transition on the right colon, mild fat stranding (arrowheads), and small mesenteric lymph nodes.

Adenocarcinomas of the terminal ileum are primarily annular and constricting (Fig 2). The annular lesion manifests as eccentric or circumferential wall thickening involving a short segment of the ileum and enhances after the intravenous administration of contrast material. Differentiation of the infiltrative form of terminal ileal adenocarcinoma from stenosing Crohn disease can be difficult; however, certain features of Crohn disease as well as the length of bowel involved may be helpful in this context. Adenocarcinomas of the terminal ileum may rarely manifest as a pedunculated polypoid mass that can lead to intussusception. Unlike small bowel lymphoma, however, they do not tend to cavitate.

Figure 2.  Adenocarcinoma of the terminal ileum in a 56-year-old woman with Crohn disease who presented with a sudden occlusive syndrome. Intestinoscopy revealed a stenosis that could not be bypassed with an endoscope. Oblique sagittal reformatted multi–detector row CT image obtained through the ileocecal junction shows obstructive stenosis of the terminal ileum (arrow). Resection of the terminal ileum revealed a small bowel adenocarcinoma 2 cm from the ileocecal valve.

Adenocarcinomas of the appendix are less common than appendiceal carcinoid tumors but are more likely to be detected at multi–detector row CT due to their larger size and higher rate of complications (7). The majority of these tumors are mucin rich; thus, their diagnosis at CT hinges primarily on detection of the resulting mucocele. Soft-tissue thickening and irregularity of the mucocele wall and surrounding fat are nonspecific findings that suggest malignancy, secondary inflammation, or both. Nonmucinous neoplasms of the appendix are usually detected in the setting of appendicitis in an older patient as a focal soft-tissue mass involving the appendix without mucocele formation. A subtle infiltrative appendiceal mass with surrounding periappendiceal inflammation may be mistaken for nontumoral appendicitis.

Carcinoid Tumors.—Distal ileal carcinoid tumors are likely to be small, but the thinner collimation that is possible with multi–detector row CT allows their diagnosis (8). They usually manifest as hypervascular nodular wall thickening or a smooth submucosal mass (Fig 3). As they enlarge, they rarely cause annular narrowing, but there may be kinking of the bowel wall with narrowing of the lumen. Manifestations of mesenteric desmoplastic reaction, sometimes without an evident mass component, are the most common and striking CT findings. This reaction manifests as an ill-defined, soft-tissue-attenuation mass with mesenteric stranding in a stellate pattern extending toward the surrounding bowel loops. The mass contains calcification in up to 70% of cases.

Figure 3a.  Carcinoid tumor of the terminal ileum in a 47-year-old man. Coronal oblique reformatted multi–detector row CT images show an ill-defined, spiculated mesenteric mass (arrows in a) and a small enhancing nodule of the terminal ileal wall (arrows in b). Note also the hepatic metastases.

Figure 3b.  Carcinoid tumor of the terminal ileum in a 47-year-old man. Coronal oblique reformatted multi–detector row CT images show an ill-defined, spiculated mesenteric mass (arrows in a) and a small enhancing nodule of the terminal ileal wall (arrows in b). Note also the hepatic metastases.

Carcinoid tumors of the appendix are usually less than 1 cm in size and found in the distal third of the appendix. They are most often discovered at surgery or pathologic examination. Symptomatic obstructing carcinoid tumors near the base of the appendix will usually manifest at CT as appendicitis (Fig 4); they sometimes manifest as diffuse mural thickening at multi–detector row CT (7). Metastatic disease is rare but has CT features similar to those of small bowel carcinoid tumors.

Figure 4a.  Appendiceal carcinoid tumor in a 60-year-old woman who presented with right lower quadrant pain. (a) Multi–detector row CT scan shows a mildly enlarged (8-mm) appendix (arrow) with surrounding fat stranding (arrowhead). (b) Coronal oblique reformatted multi–detector row CT image shows associated thickening of the cecum (arrow) and terminal ileum (arrowhead). Surgery and pathologic examination revealed a carcinoid tumor of the appendix.

Figure 4b.  Appendiceal carcinoid tumor in a 60-year-old woman who presented with right lower quadrant pain. (a) Multi–detector row CT scan shows a mildly enlarged (8-mm) appendix (arrow) with surrounding fat stranding (arrowhead). (b) Coronal oblique reformatted multi–detector row CT image shows associated thickening of the cecum (arrow) and terminal ileum (arrowhead). Surgery and pathologic examination revealed a carcinoid tumor of the appendix.

Lymphoma.—The ileum and the cecum are the most common sites of involvement by primary lymphoma in the small and large bowel, respectively. The lymphoma may also extend to the appendix.

Lymphoma of the ileocecal region most commonly manifests as single or multiple segmental areas of circumferential thickening with homogeneous attenuation and poor enhancement. The bowel wall may display symmetric thickening and is usually markedly thickened (1.5–7 cm) (9,10).

Lymphoma of the ileocecal area may also be seen as a polypoid lesion of variable size that may act as the lead point of an intussusception. Lymphoma may mimic adenocarcinoma, but in the former, the segment of bowel involved is usually longer; the transition from tumor to normal bowel is much more gradual; and associated, possibly bulky mesenteric and retroperitoneal lymph nodes are usually seen encroaching on the vessels from both sides (Fig 5).

Figure 5.  Non-Hodgkin ileocecal lymphoma in a 55-year-old man. Multi–detector row CT scan shows marked homogeneous symmetric thickening of the cecal wall. There is no stenosis of the lumen (arrowhead). Large regional and mesenteric lymphadenopathies (arrows) are also seen. Note the presence of fat stranding, which is, however, less severe than the wall thickening.

A classic complication is ulceration with formation of a fistulous tract to adjacent bowel loops. An excavating mass is one that involves the entire bowel wall, with bowel entering and exiting the mass. The lumen or cavity of the mass fills with contrast material and is usually larger than the bowel entering it; this condition is referred to as aneurysmal dilatation of the bowel.

GISTs of the ileocecal area may rarely occur in the distal ileum and, even more rarely, in the cecum. Many pathologists believe that all GISTs will eventually become malignant, but that smaller tumors should be classified as posing less risk for malignancy (11). The diagnosis of GIST can be suggested by the presence at multi–detector row CT of a large, well-circumscribed tumor arising from the ileum that is usually predominantly extraluminal with a heterogeneously enhancing soft-tissue rim surrounding a necrotic center (12). GIST of the ileum has many features similar to those of lymphoma. It can manifest as a large mass within the ileum that may ulcerate, cavitate, and extend into the adjacent mesentery. The presence of associated lymphadenopathy favors the diagnosis of lymphoma, since the lymphatic route is not a common mode of tumor spread in GIST.

Secondary Malignant Involvement

Neoplastic lesions may spread to the small bowel hematogenously, by means of direct invasion, or by means of intraperitoneal seeding (the right lower quadrant at the termination of the small bowel mesentery being one of the predominant sites of implantation). Metastases to the distal ileum are typically not confined to this segment of bowel and often occur in patients with a history of primary malignancy that is compatible with such metastases. Direct invasion from the right ovary usually involves the cecum and distal ileum by means of extension through the small bowel mesentery of the ileum (13).

Multi–detector row CT features include increased bowel wall thickness, annular stenosis with marked luminal narrowing and angulation, and a polypoid mass that may occasionally cavitate (Fig 6) (9).

Figure 6.  Cecal metastasis from hepatocellular carcinoma in a 60-year-old man. Multi–detector row CT scan shows a large, hyperattenuating subserosal cecal mass (arrows).

Benign Tumors

Lipoma.—The cecum is the most common location of lipomas. True lipomas of the ileocecal valve (Fig 7) should not be confused with lipomatosis of the valve (Fig 8), which is much more common. A true lipoma will manifest as an asymmetric mass, whereas lipomatosis manifests as symmetric enlargement of the valve. The ileum is the most common location of small bowel lipomas, which are usually asymptomatic but can occasionally cause bleeding or lead to intussusception (14). They usually appear as a well-defined, round or oval, homogeneous intramural mass with an attenuation between −80 and −120 HU.

Figure 7.  Lipoma of the ileocecal valve in a 70-year-old man. Sagittal oblique reformatted multi–detector row CT image shows a lipoma located at the level of the ileocecal junction, appearing as a well-defined small fatty mass (arrow).

Figure 8.  Lipomatosis of the ileocecal valve in a 40-year-old man. Sagittal oblique reformatted multi–detector row CT image of the ileocecal junction shows symmetric fatty enlargement of the ileocecal valve (arrows).

Benign Appendiceal Tumors.—Adenomas of the appendix may be either mucinous or nonmucinous. Mucinous adenomas are far more common and manifest as a mucocele—that is, a round, sharply defined paracecal mass with homogeneous contents of near water or soft-tissue attenuation depending on the amount of mucin (Fig 9) (7).

Figure 9.  Incidentally discovered mucocele (mucinous appendiceal adenoma) in a 71-year-old man. Coronal oblique reformatted multi–detector row CT image tilted laterally shows the full extent of an elongated cystic mass (arrowheads) and its proximity to the base of the cecum (arrow).

Other Benign Tumors.—Adenomas most commonly occur in the ileocecal region and may manifest as pedunculated or broad-based intraluminal masses with soft-tissue attenuation. Hemangiomas rarely occur in the ileocecal area, where they are hypervascular and may be pedunculated.

Tumor-related Complications

Multi–detector row CT may offer distinct advantages over traditional single–detector row CT in the evaluation of complications of tumors of the ileocecal area, mainly, obstruction and intussusception (15,16). Thinner collimation and faster scanning increase resolution and decrease respiratory and motion artifact, especially in patients with severe bowel obstruction, who are often in severe pain (8). The availability of additional planes is appreciated by surgeons and often increases the confidence of radiologists in dealing with difficult cases of obstruction (Figs 2, 10) and intussusception (16). Ileocolic intussusception is the prolapse of a portion of the ileum into the lumen of the cecum or colon. Benign masses including lipoma (Fig 11), ileal polyps, appendiceal mucocele, and enteric cystic duplication (Fig 12); polypoid malignant tumors such as lymphoma and carcinomas (Fig 13); and Meckel diverticulum (Fig 14) may all act as lead points for ileocolic intussusception. The most common symptoms are abdominal pain, nausea, and vomiting, usually of long duration, although patients may occasionally present with acute abdomen (17). Multi–detector row CT features include a pathognomonic bowel-within-bowel configuration with or without contained fat and mesenteric vessels; proximal bowel obstruction; and, sometimes, a mass corresponding to the pathologic lead point.

Figure 10.  Adenocarcinoma of the ileocecal valve in a 92-year-old patient. CT scan through the ileocecal junction shows an enhancing mass (arrow) causing small bowel obstruction. Note the presence of the “small bowel feces sign” in the small bowel loops. Surgery helped confirm adenocarcinoma of the ileocecal valve.

Figure 11.  Terminal ileal lipoma. CT scan shows a rounded, well-limited mass with fat attenuation (arrow) at the leading end of an ileocolic intussusception. Surgery helped confirm terminal ileal lipoma as the cause of the intussusception.

Figure 12.  Enteric duplication cyst in a 35-year-old patient who presented with acute abdominal pain. The patient had recently undergone colonoscopy, which had revealed a submucosal mass resembling a terminal ileal lipoma protruding into the ileocecal valve. Coronal oblique reformatted multi–detector row CT image through the leading end of an ileocecal intussusception shows a nonenhancing, homogeneous soft-tissue mass (arrow). Laparoscopic ileocecal resection revealed a large (3.5-cm) duplication cyst at the ileocecal junction.

Figure 13a.  Cecal adenocarcinoma. (a) Multi–detector row CT scan shows a cecocolic intussusception. Mesenteric fat and contrast material–enhanced mesenteric vessels are seen within the lumen of the intussusception (arrow). (b) Coronal oblique reformatted multi–detector row CT image through the leading end of the intussuscipiens shows an enhancing mass (arrow), which proved to be cecal adenocarcinoma.

Figure 13b.  Cecal adenocarcinoma. (a) Multi–detector row CT scan shows a cecocolic intussusception. Mesenteric fat and contrast material–enhanced mesenteric vessels are seen within the lumen of the intussusception (arrow). (b) Coronal oblique reformatted multi–detector row CT image through the leading end of the intussuscipiens shows an enhancing mass (arrow), which proved to be cecal adenocarcinoma.

Figure 14.  Inverted Meckel diverticulum with an ileoileal intussusception. Contrast-enhanced CT scan demonstrates an ileoileal intussusception, which appears as a central focus of fat attenuation with concentric rings of alternating fat and soft-tissue attenuation (arrow). These findings represent a core of mesenteric fat surrounded by the wall of the diverticulum and the intestinal wall.

Inflammatory Conditions

Noninfectious Inflammatory Conditions

Appendicitis.—Acute appendicitis manifests as enlargement of the appendix to a diameter greater than 6 mm; thickened wall with enhancement; periappendiceal fat stranding; and, sometimes, focal thickening of the terminal ileum or cecum (Fig 15). Conversely, patients with mild isolated appendiceal dilatation (<9 mm) are unlikely to have appendicitis. In addition, fewer than one-third of patients with an identifiable normal appendix surrounded by inflammatory stranding or fluid will have appendicitis (18). A focal defect in the wall of the inflamed appendix, an appendicolith outside the appendix, a periappendiceal fluid collection, or extraluminal air near the appendix indicates perforation of the appendix. In such cases, the appendix may be difficult to see (Fig 16).

Figure 15a.  Appendicitis in a 30-year-old patient. (a) Sagittal oblique reformatted multi–detector row CT image shows the full length of an inflamed appendix (arrowhead) and mild thickening of the cecal base (arrow). (b) Coronal oblique reformatted multi–detector row CT image shows thickening of both the terminal ileum (arrowhead) and the cecal base (arrow).

Figure 15b.  Appendicitis in a 30-year-old patient. (a) Sagittal oblique reformatted multi–detector row CT image shows the full length of an inflamed appendix (arrowhead) and mild thickening of the cecal base (arrow). (b) Coronal oblique reformatted multi–detector row CT image shows thickening of both the terminal ileum (arrowhead) and the cecal base (arrow).

Figure 16.  Perforated appendicitis in a 40-year-old man. Coronal oblique reformatted multi–detector row CT image shows severe fat stranding of the ileocecal area, along with thickening of the cecal base and terminal ileum. The appendix is not identified. Note the presence of secondary epiploic appendagitis of the cecum, which appears as an oval, paracecal fatty mass with a well-circumscribed, hyperattenuating rim (arrows).

Diverticulitis.—Cecal diverticulitis may be mistaken clinically for acute appendicitis. Early, accurate diagnosis is important for avoiding unnecessary laparotomy and preventing potential complications such as abscesses. Multi–detector row CT findings usually consist of asymmetric or circumferential thickening of the cecal wall, focal pericolic inflammation, and demonstration of diverticula. Inflamed diverticula are usually located at the level of maximum pericolic inflammation and maximum wall thickening. Visualization of a normal appendix or of inflammatory changes involving the ascending colon at a level distal to the ileocecal valve favors the diagnosis of diverticulitis over appendicitis (19). Pericecal lymph nodes adjacent to the focal area of cecal thickening are more commonly seen in patients with cancer than in those with diverticulitis. In differentiating between diverticulitis and right colic carcinoma, an inflamed diverticulum (ie, a diverticulum associated with a thickened, enhancing diverticular wall and peridiverticular inflammatory changes) and a preserved wall enhancement pattern are the most discriminative findings (Figs 17, 18) (5). Multi–detector row CT allows more frequent visualization of the diverticula because of the thinner collimation that is used.

Figure 17a.  Right colic diverticulitis in a 36-year-old man with hyperleukocytosis who presented with acute right lower quadrant pain. The patient had undergone appendectomy 8 years earlier. Coronal oblique reformatted multi–detector row CT images show mild thickening of the cecal wall; an inflamed enhancing diverticulum with a thickened wall (arrow in a); stranding of peridiverticular and pericecal fat; and a thickened terminal ileum (arrow in b). These findings led to a diagnosis of right colic diverticulitis.

Figure 17b.  Right colic diverticulitis in a 36-year-old man with hyperleukocytosis who presented with acute right lower quadrant pain. The patient had undergone appendectomy 8 years earlier. Coronal oblique reformatted multi–detector row CT images show mild thickening of the cecal wall; an inflamed enhancing diverticulum with a thickened wall (arrow in a); stranding of peridiverticular and pericecal fat; and a thickened terminal ileum (arrow in b). These findings led to a diagnosis of right colic diverticulitis.

Figure 18a.  Cecal diverticulitis in a 23-year-old woman who presented with left upper quadrant pain and an elevated C-reactive protein level. The patient had undergone appendectomy in 1980. (a) Oblique reformatted multi–detector row CT image shows a thickened, hypoattenuating diverticular wall with preservation of a layered enhancement pattern (arrow), as well as diverticular inflammation (arrowhead). (b) Coronal oblique reformatted multi–detector row CT image helps confirm marked symmetric thickening of the cecal wall (arrowhead) and terminal ileum (arrows). Laparoscopic surgery was performed for persistent abdominal pain and helped confirm cecal diverticulitis.

Figure 18b.  Cecal diverticulitis in a 23-year-old woman who presented with left upper quadrant pain and an elevated C-reactive protein level. The patient had undergone appendectomy in 1980. (a) Oblique reformatted multi–detector row CT image shows a thickened, hypoattenuating diverticular wall with preservation of a layered enhancement pattern (arrow), as well as diverticular inflammation (arrowhead). (b) Coronal oblique reformatted multi–detector row CT image helps confirm marked symmetric thickening of the cecal wall (arrowhead) and terminal ileum (arrows). Laparoscopic surgery was performed for persistent abdominal pain and helped confirm cecal diverticulitis.

Ileal diverticulitis is rare and has the same characteristics as cecal diverticulitis (Fig 19).

Figure 19.  Terminal ileal diverticulitis in a 55-year-old man. Multi–detector row CT scan shows inflamed diverticula on the terminal ileum with surrounding fat stranding (arrows).

Although Meckel diverticulum occurs at some distance (60–100 cm) from the ileocecal valve, it may cause complications such as inflammation, whose differential diagnosis includes appendicitis and inflammatory bowel disease (20). The CT diagnosis of inflammation of Meckel diverticulum relies on the identification of a blind-ending, tubular, round or oval structure in the right lower quadrant with surrounding inflammation. Occasionally, enteroliths will be present within the inflamed diverticulum. The presence of a pouchlike structure attached to the adjacent small intestine is a helpful clue to the diagnosis. Other helpful features include the presence of a secondary small intestinal obstruction and visualization of a normal appendix (20,21).

Epiploic appendagitis is thought to occur as a result of spontaneous torsion, ischemia, or inflammation of an epiploic appendage of the colon (22). Patients present with acute abdominal pain that can mimic appendicitis. Characteristic findings include an oval, paracecal fatty mass representing the infarcted or inflamed appendix epiploica; a well-circumscribed, hyperattenuating rim surrounding the mass; and, sometimes, a high-attenuation central dot (Figs 16, 20). The cecal wall may show mild local reactive thickening that is disproportionately less severe than the paracecal inflammatory changes. Epiploic appendagitis can be managed conservatively (23).

Figure 20.  Epiploic appendagitis in a young male patient with acute right iliac fossa pain. Multi–detector row CT scan demonstrates an oval, paracecal fatty mass (arrows) with surrounding fat stranding.

Idiopathic Inflammatory Disease

Crohn disease has a propensity to involve the terminal ileum and the cecum. It also affects the appendix, especially in cases of colic disease, but Crohn disease limited to the appendix is uncommon. CT findings include mild segmental bowel wall thickening, narrowing of the lumen, mesenteric fat stranding, creeping fat, mesenteric lymph node enlargement, and skip lesions. Edema within the wall may result in layered enhancement during the acute phase of inflammation, and bowel wall thickening may be marked (>2 cm) at this stage (Fig 21) (24). Long segmental wall thickening of the terminal ileum, circumferential thickening of the cecum, and inflammation that is centered away from the appendix are the major features that help differentiate Crohn disease from the reactive changes seen in appendicitis. Secondary findings that also help establish the diagnosis of Crohn disease include fistulas, sinus tracts, abscesses, and fibrofatty proliferation (Fig 22). One of the complications of small bowel Crohn disease is adenocarcinoma.

Figure 21a.  Crohn disease in a 41-year-old man. (a) Multi–detector row CT scan shows an enlarged appendix (black arrow), stratified symmetric thickening of the terminal ileum (arrowheads), and adjacent creeping fat (white arrow). (b) Sagittal reformatted multi–detector row CT image demonstrates hypoattenuating symmetric thickening of the cecal wall (arrowheads) and stratified thickening of the terminal ileum (arrows).

Figure 21b.  Crohn disease in a 41-year-old man. (a) Multi–detector row CT scan shows an enlarged appendix (black arrow), stratified symmetric thickening of the terminal ileum (arrowheads), and adjacent creeping fat (white arrow). (b) Sagittal reformatted multi–detector row CT image demonstrates hypoattenuating symmetric thickening of the cecal wall (arrowheads) and stratified thickening of the terminal ileum (arrows).

Figure 22.  Crohn disease in a 33-year-old man. Sagittal oblique reformatted multi–detector row CT image shows a thickened, inflammatory terminal ileum (arrowheads) with a fistula and retroperitoneal abscess posteriorly (arrows).

Ulcerative colitis may involve the ileocecal area; to our knowledge, however, exclusive involvement of either the right colon or the distal ileum by this disease has not been demonstrated.

Infectious Conditions

Tuberculosis and Other Enteritides

The ileocecal area is the portion of the gastrointestinal tract that is most commonly involved by tuberculosis. Characteristic CT features include asymmetric thickening of the ileocecal valve and medial wall of the cecum, exophytic extension engulfing the terminal ileum, and massive lymph nodes with central low-attenuation areas (25). Associated findings such as peritoneal involvement, a history of tuberculosis, a positive tuberculin skin test, and characteristic chest radiographic findings provide additional clues if present.

Infectious Terminal Ileitis

Infectious terminal ileitis is usually caused by Yersinia, Campylobacter, or Salmonella organisms (2). The clinical diagnosis is straightforward when patients present with acute diarrhea symptoms and the results of stool cultures are confirmatory. Symptoms may be indistinguishable from those of appendicitis when right lower quadrant pain is the major complaint. The characteristic CT features include circumferential wall thickening of the terminal ileum and cecum and moderate or marked enlargement of the mesenteric lymph nodes in the right lower quadrant. Concentric thickening of the bowel wall may be limited to the ileum and may be marked, but usually with preservation of a layered enhancement pattern (Figs 23, 24). Perforation and fistulization may occasionally occur (26).

Figure 23.  Terminal ileitis due to Campylobacter infection in a 28-year-old patient. Multi–detector row CT scan shows marked thickening of the cecum (arrowheads) and terminal ileum (arrows) with preservation of a layered enhancement pattern. Note the small regional lymph nodes and the absence of fat stranding.

Figure 24a.  Terminal ileitis in a 51-year-old woman who presented with acute abdominal pain and fever. A mass was palpated in the right iliac fossa. (a) Multi–detector row CT scan shows marked right colic wall thickening with preservation of a layered enhancement pattern (arrowhead), a finding that helped rule out lym-phoma. A cluster of lymphadenopathies (arrows) is also seen. (b) Multi–detector row CT scan shows thickening of the terminal ileum (arrowhead). Arrows indicate the cluster of lymphadenopathies. Laparoscopy was performed owing to these CT findings and helped confirm infectious disease due to Y enterocolitica.

Figure 24b.  Terminal ileitis in a 51-year-old woman who presented with acute abdominal pain and fever. A mass was palpated in the right iliac fossa. (a) Multi–detector row CT scan shows marked right colic wall thickening with preservation of a layered enhancement pattern (arrowhead), a finding that helped rule out lymphoma. A cluster of lymphadenopathies (arrows) is also seen. (b) Multi–detector row CT scan shows thickening of the terminal ileum (arrowhead). Arrows indicate the cluster of lymphadenopathies. Laparoscopy was performed owing to these CT findings and helped confirm infectious disease due to Y enterocolitica.

Inflammatory Reaction to an Extrinsic Infectious Process

The extrinsic inflammation from a tubo-ovarian abscess may cause serosal edema and mural thickening of the appendix and even of the cecal wall, which creates a diagnostic challenge (Fig 25) (27,28). Recognizing that the inflammation is centered in the adnexa rather than in the appendix assists in making the correct diagnosis.

Figure 25a.  Tubo-ovarian abscess with mild inflammatory reactive changes of the cecal base and appendix in a 36-year-old woman. (a) Coronal oblique reformatted multi–detector row CT image shows mild thickening of the cecal base (arrows) and enlargement of the appendix to 8 mm (arrowhead). (b) Multi–detector row CT scan shows features suggestive of a left tubo-ovarian abscess (arrows), a finding that was confirmed surgically.

Figure 25b.  Tubo-ovarian abscess with mild inflammatory reactive changes of the cecal base and appendix in a 36-year-old woman. (a) Coronal oblique reformatted multi–detector row CT image shows mild thickening of the cecal base (arrows) and enlargement of the appendix to 8 mm (arrowhead). (b) Multi–detector row CT scan shows features suggestive of a left tubo-ovarian abscess (arrows), a finding that was confirmed surgically.

Miscellaneous Conditions

Typhlitis (Neutropenic Colitis)

Typhlitis is an inflammatory condition seen in immunocompromised patients. It characteristically affects the cecum and ascending colon but may also involve the terminal ileum and the appendix. Typhlitis frequently manifests as right lower quadrant pain, fever, and evidence of peritoneal inflammation. Multi–detector row CT features include segmental bowel wall thickening, pericolic fluid collection or fat stranding, pneumatosis coli, and intramural low-attenuation regions indicative of edema or necrosis, which may be confused with the reactive changes of appendicitis (Figs 26, 27) (29,30). However, the length of the cecum and right colon involved by typhlitis is generally much greater than that associated with appendicitis, and the presence of known risk factors favors the diagnosis of typhlitis (neutropenic colitis) (31). Moreover, bowel thickening is more asymmetric in appendicitis than in typhlitis, which usually manifests with circumferential symmetric thickening. Early diagnosis and aggressive medical treatment are essential for avoiding transmural necrosis and perforation.

Figure 26.  Typhlitis in a 35-year-old man who presented with right lower quadrant pain, fever, and diarrhea. The patient was undergoing chemotherapy. Sagittal oblique reformatted multi–detector row CT image tilted to display the ileocecal junction shows marked thickening of the cecal wall with pronounced submucosal edema (arrow). The appendix is normal, and the terminal ileum is moderately thickened.

Figure 27a.  Typhlitis in a 22-year-old man with myeloblastic acute leukemia with aplasia who presented with sudden, violent right lower quadrant pain with fever. (a) Multi–detector row CT scan through the base of the cecum shows a thickened cecum (black arrow), appendix (arrowhead), and terminal ileum (white arrow). Marked submucosal edema is also seen. A diagnosis of appendicitis was made, and the patient underwent corrective surgery. (b) Oblique reformatted multi–detector row CT image obtained a few days later shows increased edema of the cecum and terminal ileum. The patient responded favorably to several weeks of aggressive treatment. Histologic examination of the appendix revealed inflammatory lesions suggestive of typhlitis.

Figure 27b.  Typhlitis in a 22-year-old man with myeloblastic acute leukemia with aplasia who presented with sudden, violent right lower quadrant pain with fever. (a) Multi–detector row CT scan through the base of the cecum shows a thickened cecum (black arrow), appendix (arrowhead), and terminal ileum (white arrow). Marked submucosal edema is also seen. A diagnosis of appendicitis was made, and the patient underwent corrective surgery. (b) Oblique reformatted multi–detector row CT image obtained a few days later shows increased edema of the cecum and terminal ileum. The patient responded favorably to several weeks of aggressive treatment. Histologic examination of the appendix revealed inflammatory lesions suggestive of typhlitis.

Ischemic Conditions

Ischemic small bowel processes are usually diffuse. The ischemic condition that can be confined to the ileocecal area is ischemic necrosis of the cecum, a rare, potentially life-threatening entity that has been reported to occur spontaneously and in association with chronic heart disease, cardiopulmonary bypass surgery, systemic chemotherapy, cholesterol embolization, and aortitis syndrome. Ischemic necrosis of the cecum should be included in the differential diagnosis when a patient presents with acute right lower quadrant pain, particularly if the patient is elderly or has predisposing risk factors (32,33). CT findings include circumferential cecal wall thickening, a mural stratification pattern due to submucosal edema, and mild pericolic stranding, with a normal appendix and absence of diverticula. More specific signs include isolated pneumatosis coli, mesenteric or portal venous gas, and pneumoperitoneum (Fig 28).

Figure 28a.  Ischemic necrosis of the cecum in a 66-year-old patient who presented with sudden right lower quadrant pain. The patient had a history of cardiac failure with arrhythmia. (a) Coronal oblique reformatted multi–detector row CT image shows cecal wall thickening (arrow). (b) Multi–detector row CT scan demonstrates the presence of air (arrows) in the veins that drain the cecum. Surgery (ileocecal resection) and pathologic findings helped confirm acute ischemic colitis with necrotic colic mucosa but without perforation.

Figure 28b.  Ischemic necrosis of the cecum in a 66-year-old patient who presented with sudden right lower quadrant pain. The patient had a history of cardiac failure with arrhythmia. (a) Coronal oblique reformatted multi–detector row CT image shows cecal wall thickening (arrow). (b) Multi–detector row CT scan demonstrates the presence of air (arrows) in the veins that drain the cecum. Surgery (ileocecal resection) and pathologic findings helped confirm acute ischemic colitis with necrotic colic mucosa but without perforation.

Volvulus of the Cecum

Volvulus may affect the cecum. CT demonstrates a whorled pattern caused by torsion of the bowel segments (afferent and efferent loops) around the fixed and twisted mesentery. The distended cecum is usually located in the left upper quadrant (Fig 29).

Figure 29.  Volvulus of the cecum. Sagittal reformatted multi–detector row CT image tilted laterally shows the transition zone (arrow) between the opacified colon and the cecum (arrowheads). The cecum is distended, rotated, and located in the left quadrant.

Ileocecal Enteric Duplication Cyst

Enteric duplication cyst is an uncommon congenital abnormality that most commonly involves the small intestine, particularly the ileum. The cecum is also often involved. These cysts most frequently occur in children. At CT, enteric duplication cyst will appear as a smoothly rounded, fluid-filled cyst or as a tubular structure with thin enhancing walls, located in or adjacent to the bowel wall (Fig 12) (34). Occasionally, a cyst located in the ileum at or near the ileocecal junction can manifest as an intussusception.

Endometriosis

Endometriosis of the ileocecal area is very rare. In most cases, small bowel endometriosis implants involve the terminal ileum within 10 cm of the ileocecal valve, usually manifesting as eccentric areas of narrowing. Clinical history and presentation may suggest the correct diagnosis (35).

Conclusions

Because it allows imaging of larger areas with thinner sections than has previously been possible and yields multiplanar reformatted images, multi–detector row CT plays an important role in the evaluation of patients with a variety of diseases involving the ileocecal area. Some variables such as mural stratification pattern and degree of fat stranding help narrow the differential diagnosis in conditions involving the cecum, terminal ileum, or appendix. Other characteristic CT findings in disease entities of the ileocecal area often lead to a final diagnosis. Correct noninvasive diagnosis is important because treatment approaches for these conditions range from patient monitoring to surgery.

Abbreviation: GIST = gastrointestinal stromal tumor

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