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ESOPHAGUS

Congenital Abnormalities

Duplication

An esophageal duplication, which is a foregut cyst, is the least common of all esophageal congenital abnormalities. Complete duplication is rare; some of these abnormalities are also associated with gastric duplication. Some duplications communicate with the esophageal lumen, although most do not. With a high superior communication they mimic a branchial pouch fistula. Some lie between the esophagus and trachea or extend into the mediastinum anteriorly. A rare one is intraabdominal in location.

Duplications are often incidental findings, although being lined by alimentary tract mucosa, they can ulcerate. Hemorrhage or secretions increase their size, with the larger ones then obstructing pulmonary vessels or a bronchus. In the very young they are prone to obstruct the esophageal lumen. Similar to other gut duplications, a rare adenocarcinoma and a leiomyosarcoma have developed in these duplications involved all layers and pleural surface.

Conventional radiography or a contrast study reveals an extrinsic or intramural mass adjacent to the esophageal lumen, most often in the lower third of the esophagus. Computed tomography and MRI confirm their cystic nature. They appear as sharply marginated, fluid-filled oval or spherical tumors (Fig. 1.1). Endoscopic US of one cyst showed contiguity of the esophageal muscularis propria with cyst wall muscle layers

(6).

A typical duplication is hypointense on T1and hyperintense on T2-weighted images, although the T2 signal varies depending on cyst protein content. Postcontrast the cyst wall enhances to varying degree; marked enhancement should suggest either inflammation or presence of gastric mucosa.

A rare cancer develops in a foregut cyst. 2-[18F]-fluoro-deoxy-D-glucose (FDG) positron emission tomography (PET) of a foregut cyst adenocarcinoma revealed numerous hypermetabolic regions consistent with metastases (7).

Figure 1.1. Esophageal duplication. Computed tomography (CT) reveals a cyst (arrow) adjacent to the distal esophagus. It did not communicate with the esophageal lumen. (Courtesy of Temil Tirkes, M.D., University of Pennsylvania.)

either in the lung or in the mediastinum. When located adjacent to the esophagus they appear to arise from the wall of the esophagus, result in dysphagia, and mimic an esophageal duplication (8). Histologically, both have ciliated epithelium; however, esophageal duplications have two smooth-muscle layers and lack cartilage. Some authors classify both simply as foregut cysts.

Short Esophagus/Congenital

Esophageal Stenosis

Most congenital strictures in infants are smooth, elongated, and associated with esophageal foreshortening. In an infant the congenital nature of such a stricture is generally suspected; in older individuals differentiation from complications of reflux esophagitis is problematic.

Multiple ringlike constrictions in the upper or mid-esophagus are occasionally found in young adults with long-standing dysphagia (9); such an appearance is believed to represent residual congenital esophageal stenosis, although a Barrett’s esophagus is in the differential.

Bronchogenic cysts are congenital malformations having an epithelial lining. They occur

Failure of foregut differentiation results in specific tracheoesophageal anomalies. Most

investigators classify these foregut malformations into five types. The nomenclature used varies and it is thus best to describe the actual defect present (Fig. 1.2). Gas in the stomach implies a communication with the tracheobronchial tree. Some H-type fistulas are rela-

ADVANCED IMAGING OF THE ABDOMEN

tively asymptomatic during infancy and manifest only later in life.

Almost two thirds of neonates with these anomalies also have other defects, with the most common being a cardiac defect, followed by skeletal, neurologic, and renal disorders.

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Some have a complex bronchopulmonary foregut malformation, including sequestration and duplication. At times the esophageal pouch contains heterotopic pancreatic tissue. One newborn with an esophageal lung (a rare type of communicating bronchopulmonary foregut malformation) also had esophageal atresia, a tracheoesophageal fistula, duodenal stenosis, an annular pancreas, imperforate anus, vertebral anomalies, and ambiguous genitalia (10). In one infant an upper pouch reached 1.5cm below the tracheal carina while the distal esophagus connected to the trachea 2cm above the carina, thus also forming a partial esophageal duplication (11); the upper pouch contained heterotopic pancreatic tissue. Rarely, the distal esophagus connects with a lower lobe bronchus, with the involved lung having a systemic arterial blood supply (12).

An increased prevalence of foregut malformations is found in Down syndrome. An association exists between esophageal atresia/ tracheoesophageal fistula and congenital distal esophageal stenosis. Complicating the issue are the more common acquired postoperative esophageal strictures. Congenital esophageal stenoses tend to be relatively long, smooth, and circumferential and located at the mid-to-distal esophagus, with a normal caliber superiorly and inferiorly; postoperative strictures, on the other hand, tend to be more focal (Fig. 1.3).

The procedure of choice to evaluate neonates with congenital tracheoesophageal atresia and fistulas is contrast radiography. The role of 3D CT and virtual bronchoscopy is not established, although they appear accurate in defining esophageal atresia and fistulas (13). Small tracheoesophageal fistulas are difficult to detect. Most involve the proximal one third of the esophagus and extend superiorly before communicating with the trachea. A double balloon catheter has been proposed as an aid to evaluate subtle H-type fistulas (14).

Postoperative anastomotic complications include symptomatic stricture, leakage, and recurrent fistula; gastroesophageal reflux is found in over half of these infants, and postoperative esophageal dysmotility is common. Postoperative extrapleural fluid collections in neonates after esophageal atresia repair using an extrapleural surgical approach suggest an anastomotic leak (15); chest radiographs reveal these

Figure 1.3. Residual deformity in mid-esophagus from a tracheoesophageal fistula repair as a child.

effusions to be similar in appearance to pleural effusions.

Vascular Anomalies

Embryologically, the great vessels develop from six fetal vascular arches. A normal aorta develops from the fourth arch and pulmonary artery and ductus arteriosus from the sixth. The specific vascular anomaly present depends on the vascular arch remnant; radiologists usually subdivide them based on their radiologic appearance.

Imaging should suggest the type of anomaly present, although at times angiography is necessary to outline the full extent of an anomaly.

Posterior Esophageal Impressions

This is the most common vascular anomaly in this region and is caused by an aberrant right subclavian artery posterior to the esophagus, with an occasional one being between the trachea and esophagus. Similar but reversed finding is found with a right aortic arch and an aberrant left subclavian artery.

Most patients are asymptomatic and it is not uncommon to first detect this anomaly in an adult as an incidental finding. A minority develop dysphagia due to secondary esophageal compression, a condition known as dysphagia lusoria. Occasionally dysphagia lusoria first develops in adulthood and is severe enough to result in poor oral intake and weight loss.

An esophagram is diagnostic; in a frontal position the aberrant artery indents the esophagus from the level of the aortic arch superiorly and to the right, while in a lateral position this indentation is typically posterior to the esophagus.Aortography and CT are superfluous for diagnosis, although useful to define the underlying anatomy if surgical correction is contemplated.

A rare aberrant right subclavian artery aneurysm has eroded into the esophagus.

Posterior Esophageal and Anterior

Tracheal Impressions

A vascular ring consists either of a double aortic arch or a right arch together with an aberrant left subclavian artery. A high prevalence of an aberrant left subclavian artery is found in patients with a right aortic arch. The proximal end of the aberrant left subclavian artery, located in the posterior tracheoesophageal space, appears as a diverticular-like aortic outpouching. Magnetic resonance imaging best defines the relationship between involved structures. Esophageal compression and tracheal displacement account for some of the wheezing and dysphagia in these patients.

A barium esophagogram should identify a right aortic arch deformity and suggest an aberrant left subclavian artery but will not detect a vascular outpouching. In symptomatic individuals, the ready availability and low cost of a barium esophagogram make it an ideal screening study.

ADVANCED IMAGING OF THE ABDOMEN

Trauma

Blunt trauma is an uncommon cause of esophageal injury. Cardiovascular and lung trauma tend to predominate with a severe injury. Rarely, iatrogenic esophageal injury results from resuscitative measures, at times unsuspected because of minor initial trauma.

An esophageal injury classification scale, devised by the American Association for the Surgery of Trauma, is outlined in Table 1.1.

Hematoma

Although a hematoma is included here under the heading of trauma, it should be kept in mind that some hematomas are spontaneous in origin, especially in patients on anticoagulation therapy. The patient presents with acute chest pain, dysphagia if the hematoma compresses the esophageal lumen, or hematemesis. Pain in some patients is severe enough to suggest spontaneous esophageal rupture (Boerhaave syndrome), an aortic dissection, or acute myocardial infarction.

Some hematomas are huge. A contrast esophagram identifies a smooth or serpiginous intramural tumor (Fig. 1.4). In a still bleeding patient, postcontrast CT reveals extravasation into the hematoma; otherwise, CT simply detects a well-marginated, elongated intramural tumor, initially having an attenuation higher than that of blood.

A contrast study of a hematoma communicating with the esophageal lumen has an appearance similar to an intramural diverticulum; with healing, the hematoma pocket should gradually disappear. A similar imaging appearance is seen with an intramural abscess that drains spontaneously into the lumen.

Table 1.1. Surgical Esophageal Injury Scale

Anterior Esophageal and Posterior

Tracheal Impressions

Abnormal sixth arch development leads to left pulmonary artery originating from the right. Respiratory difficulties predominate in these infants. Either CT or MRI should identify the vascular nature of this anomaly.

* Advanced one grade for multiple injuries, up to grade III. Modified from Moore et al. (16).

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Figure 1.4. Esophageal intramural hematoma. The distal esophagus contains serpiginous folds (arrows) mimicking varices. These findings cleared on a follow-up study.

Most esophageal hematomas resolve with conservative therapy.

Perforation

Clinical

Table 1.2 lists underlying conditions associated with esophageal perforation or fistula. Sudden compression or stretching against an adjacent bony segment account for some perforations during blunt trauma. An occasional cervical spine bony fragment perforates the esophagus.

Table 1.2. Conditions associated with esophageal perforation/fistula

Neoplasm

Primary esophageal

Extrinsic neoplasms

Postsurgical/instrumentation

Erosion by tube or stent

After corrosive ingestion

Penetrating or blunt trauma

Chronic infection

Ingested foreign body

Mallory-Weiss tear

Boerhaave syndrome

Ehlers-Danlos syndrome

The most distal esophageal segment is normally intraabdominal in location, and a perforation here results in a pneumoperitoneum or peritonitis rather than mediastinitis.

Blind attempts to pass a nasogastric tube have led to pharyngeal perforation or a perforation through a Zenker’s diverticulum. In newborns, a contrast study through a perforating tube superficially mimics esophageal atresia.

Pain and fever after esophageal instrumentation suggest a perforation, and such a scenario is not an uncommon indication for a prompt esophagram request. The choice of contrast agent to be used is controversial, with junior radiologists leaning toward water-soluble contrast agents while more senior, experienced radiologists tend to prefer barium sulfate. This topic is addressed in more detail below (see Imaging).

Although most localized perforations are managed successfully medically, a more extensive injury requires surgical correction. The success rate of primary repair is highest if performed within 24 hours of injury, thus the reason for performing an esophagram promptly.

Spontaneous esophageal perforation without an underlying abnormality is rare. Patients with Ehlers-Danlos syndrome are somewhat prone to spontaneous esophageal rupture.

Mallory-Weiss Tear

Many Mallory-Weiss tears are not in the esophagus but occur in a sliding hiatal hernia. Prior retching or vomiting is common, although some patients have no antecedent symptomatology. The laceration extends through the mucosa and typically manifests with bleeding, often massive, but most bleeding stops spontaneously. Occasionally, however, even therapeutic endoscopy cannot control bleeding and surgery is necessary.

A Mallory-Weiss tear or even perforation has occurred after ingestion of a colonic lavage solution. Partial obstruction of the esophagogastric junction appears to predispose to these tears.

Boerhaave’s Syndrome

Boerhaave’s syndrome, or spontaneous transmural esophageal perforation, generally occurs

in the lower third of the esophagus and extends into the left pleural space. Right-sided pleural involvement is less common. This condition has been described in the cervical esophagus (17), but whether such perforation is indeed Boerhaave’s syndrome depends on how the syndrome is defined.

Hematemesis is often the initial presentation, with an occasional patient presenting with vomiting and chest pain. Duodenal obstruction, regardless of cause, is associated with Boerhaave’s syndrome. A possibility of esophageal perforation is often overlooked and thus a delay in diagnosis and therapy for a condition having an inherent high mortality and morbidity. Nevertheless, an occasional patient is treated medically with satisfactory results.

About 90% of patients with Boerhaave’s syndrome have an abnormal chest radiogram (18); hydropneumothorax was found in 50%, pneumomediastinum in 30%, isolated pleural effusion in 25%, and parenchymal infiltrates in 14%. Computed tomography also identifies these findings as well as periesophageal mediastinal fluid.An esophagram using a water-soluble contrast agent should identify the site of perforation and guide surgical therapy (Fig. 1.5). If a diagnosis is delayed, CT is appropriate to detect mediastinitis or a mediastinal abscess.

Figure 1.5. Boerhaave’s syndrome. Contrast extravasation (arrow) is just proximal to a hiatal hernia.

ADVANCED IMAGING OF THE ABDOMEN

Imaging

The most common abnormality after instrumental esophageal perforation is pneumomediastinum, followed by left cardiophrenic angle obliteration. It should be realized that immediately after a perforation a chest radiograph is often normal. In general, a proximal intrathoracic esophageal perforation is more often associated with a right pleural effusion,while a distal perforation leads to a left pleural effusion.

A contrast esophagram is the study of choice to detect an acute perforation. Computed tomography will detect a thickened esophageal wall and adjacent extraluminal fluid, but whether it has a role in early detection of a small leak is questionable.

The choice of contrast agent to be used in a setting of suspected acute esophageal perforation is controversial. A water-soluble agent is used with a suspected acute perforation in the distal esophagus and possible spill into the peritoneal cavity. With a suspected more proximal esophageal perforation a common approach in the United States is to start with a water-soluble agent and switch to barium if a leak is not identified, a practice not without controversy. Some radiologists use barium initially for suspected pharyngeal and proximal esophageal perforations. Granted that barium is retained in soft tissues, but no convincing evidence suggests additional tissue damage by barium beyond what is produced by infected saliva. Similar to the rest of the gastrointestinal tract, damage produced by an esophageal perforation is mostly due to leak of infected esophageal content; additional spill of barium into an already infected cavity adds little, if any, damage. Retained barium in soft tissues is of little consequence aside from possibly hindering future examinations if large amounts are spilled. Thus residual barium was detected in 29% of follow-up radiographic studies performed 4 to 48 days after barium esophagrams identified esophageal leaks in postoperative patients (19); none of the residual barium interfered with new studies. Barium sulfate in soft tissues is not carcinogenic.

Classic teaching held that acute spill of barium sulfate into the peritoneal cavity resulted in acute barium peritonitis having a high morbidity and mortality. While undoubtedly true a generation or more ago, current

ESOPHAGUS

commercial barium sulfate products have evolved into considerably safer products inducing less of an inflammatory reaction.

Perforations have been claimed to have been missed when using a 50% to 100% weight/ volume barium suspension (20,21), which is counter to other published data (22) and to my experience; higher opacity barium has more x-ray stopping power and better opacifies small tracts than iodinated contrast. Subtle perforations are more readily identified with barium.

Many radiologists in Europe routinely use water-soluble contrast agents for suspected esophageal perforation. Among these agents, in Europe low-osmolality contrast media are usually employed; in the United States a commercial high-osmolality mixture of sodium and meglumine diatrizoate (Gastrografin and related products) is preferred, mostly because of its flavoring agents, which make it somewhat palatable to patients. The high-osmolality agents are contraindicated if spill into lungs is suspected, in which setting United States radiologists prefer the relatively innocuous barium sulfate.

My practice is to use water-soluble contrast agents in a setting of acute trauma if a possibility of intraperitoneal spill exists. With trauma (including abdominal surgery) more than several days old, on the other hand, barium sulfate is preferred. Thus a fluoroscopic study requested for suspected perforation several days after an intraabdominal resection is generally performed with barium sulfate.

Pediatric radiologists in search of a perforation tend to use nonionic, water-soluble contrast agents.

A postoperative esophagram establishes esophageal integrity prior to start of oral intake. Most postsurgical disruptions heal spontaneously provided the surgical field is adequately drained and esophagus is patent distally.

Foreign Bodies

Esophageal foreign bodies range from bezoars, impacted food, and a penetrating swallowed bony fragment, to swallowed coins, the latter mostly in young children. Nonfood esophageal bezoars are rare. Often these are associated either with a distal stricture or diffuse spasm. A rare sharp foreign body such as a bone splinter perforates sufficiently deep to result in an esophagoaortic fistula and exsanguination. Food impaction in the esophagus is quite common and is often related to a distal stricture or spasm. At times acute impaction is the first presentation of an esophageal carcinoma (Fig. 1.6).

In an otherwise stable patient, barium is the preferred contrast agent of choice to detect food impaction; with the patient upright, the high specific gravity of barium aids disimpaction. A number of physical maneuvers have been employed as an aid to disimpaction, with most being of dubious value. Spasmolytic drugs have

Therapy

Nonoperative therapy in select patients with thoracic esophageal perforations consists of antibiotics, nasoesophageal suction, and total parenteral nutrition. Some of these patients develop esophageal stenoses.

The surgeon usually inquires about a site of perforation; perforations of the lower one third of the intrathoracic esophagus are approached through a left thoracotomy, while more proximal perforations are managed through a right thoracotomy.

Figure 1.6. Squamous cell carcinoma. An esophagram reveals an eccentric infiltrating cancer (arrows).

been tried in some patients if underlying spasm is suspected. In a multicenter double-blind study using glucagon and diazepam, no significant difference in disimpaction was found among patients given spasmolytic agents versus placebo (23). Effervescent agents have been used to treat esophageal food impaction, with varying success.

Computed tomography has evolved into a reliable technique for detecting small, poorly calcified esophageal foreign bodies to the point that the number of endoscopies for this indication has decreased. A prospective CT study of patients with suspected esophageal fish or chicken bones detected an esophageal foreign body in 30, with a foreign body found during subsequent rigid esophagoscopy in 29 (24). Computed tomography also detects associated inflammatory changes in surrounding tissues.

In pediatric patients some radiologists remove an esophageal foreign body with a balloon catheter. This technique is successful and safe in experienced hands. Of 337 coin extractions attempted using a Foley catheter, pediatric radiologists with training in catheter technique were successful in 96% of patients (25); no complications were encountered.

Wall Thickening

Infection/Inflammation

Reflux and Reflux Esophagitis

Clinical

Gastroesophageal reflux consists either of gastric juice or of duodenal content. Reflux tends to be sporadic and difficult to quantify. One definition of massive reflux is reflux to or above the thoracic inlet either spontaneously or with provocation while in a recumbent position. Reflux is not synonymous with esophagitis; some reflux is associated with little inflamation.

Nonimaging tests for gastroesophageal reflux include direct visualization during endoscopy, the Bernstein acid infusion test and 24-hour esophageal pH monitoring. It should be kept in mind that endoscopy evaluates primarily consequences of gastroesophageal reflux rather than reflux per se. The Bernstein test, currently rarely performed, attempts to duplicate a patient’s

ADVANCED IMAGING OF THE ABDOMEN

symptoms during infusion of a weak hydrochloric acid solution into the esophagus. Esophageal pH monitoring is considered the gold standard in detecting reflux. Yet results of 24-hour esophageal pH monitoring show that some patients with endoscopically apparent esophagitis have normal pH monitoring and some without esophagitis have abnormal findings (26).

Gastroesophageal reflux is associated with a hypotensive lower esophageal sphincter that allows reflux. At times, however, reflux occurs even with a hypertensive lower esophageal sphincter. A direct association exists between the presence of a hiatal hernia and gastroesophageal reflux and esophagitis. Patients with a large hiatal hernia are more likely to have abnormal pH monitoring and worse esophagitis than those with a small hiatal hernia.

Heartburn and acid regurgitation are typical clinical symptoms, but presentations vary, at times mimicking cardiac disease. Considerable evidence suggests an association between gastroesophageal reflux and asthma. Reflux in some patients leads to laryngospasm or bronchospasm and triggers an asthmatic attack. Some patients with reflux-associated asthma do not have symptoms referable to the gastroesophageal reflux.

Children with cystic fibrosis have a higher prevalence of gastroesophageal reflux than normals. Metachromatic leukodystrophy also appears to be associated with gastroesophageal reflux.

Even in children, an esophageal stricture secondary to reflux is more common than a congenital stricture. Why some patients form strictures and others do not is not known; presumably those with prolonged reflux and a decreased lower esophageal sphincter pressure are more prone to strictures, but that is conjecture.

Imaging

Reflux is not synonymous with reflux esophagitis. Several hypermotility abnormalities are found in patients with gastroesophageal reflux: more premature cricopharyngeus muscle contractions and increased amplitude and duration of esophageal contractions compared to controls. Patients with reflux have delayed esophageal emptying; emptying is impaired further once esophagitis develops. In adults,

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an experienced fluoroscopist readily detects most reflux, if present, together with delayed esophageal emptying during a barium study.

Transabdominal US is used in some centers to detect gastroesophageal reflux in children, although the severity of reflux is difficult to assess and the results are controversial. Some investigators have achieved about 90% agreement with esophagography and 24-hour esophageal pH measurement, especially when color Doppler is added to B-mode US,but others have found US to be an unreliable diagnostic test in screening infants (27).

In most symptomatic patients, however, an upper gastrointestinal examination is performed not to detect reflux but rather to identify complications of reflux. Barium esophagram findings of reflux esophagitis consist of ulcers, nodules, fold thickening, and, eventually, strictures. Ulcers tend to be small, focal, and often barely visible. A number of these ulcers are solitary and are more common on the posterior wall close to the gastroesophageal junction (28). Small isolated ulcers are not unique to reflux esophagitis and are also found with herpes infection, drug-induced esophagitis, Behçet’s esophagus, and acute radiationinduced esophagitis.

Small, irregularly shaped nodules, described as granulations, are common in the distal esophagus in reflux esophagitis, often intermixed with small ulcers. The overall appearance often is that of granularity, and a doublecontrast esophagram is generally necessary for adequate visualization. One should keep in mind, however, that nodularity, especially if varying in size and not discrete, also suggests a superficial spreading carcinoma.

Thickened folds due to inflammation are common and often are associated with ulcers. These folds contain both mucosa and submucosa and, being inflamed, are present with the esophageal lumen either distended or collapsed. Folds varying in size with change in intraluminal pressure should suggest varices. Associated findings are common and include hiatal hernias, intramural pseudodiverticula, scarring, and strictures (Fig. 1.7).

In patients with esophagitis (regardless of cause), CT identified a relatively long segment of circumferential esophageal wall thickening (using a 5-mm threshold) in 55% and a target sign in 17% (29); these CT findings are nonspecific, and other diseases, including an occa-

Figure 1.7. Reflux stricture (arrow) in the distal esophagus. A 12-mm barium pill is useful to confirm equivocal strictures.

sional infiltrating cancer, also result in a thickened esophageal wall.

At times transabdominal US detects a hiatal hernia, but esophagitis is not readily detected. Endoscopic US, on the other hand, readily evaluates the esophageal wall and surrounding structures, detecting esophageal wall thickening due to inflammation and other causes.

A radionuclide gastroesophageal reflux study using technetium-99m (Tc-99m) sulfur colloid is physiologic, readily performed, and provides quantitative data. This test has achieved wider acceptance in pediatric patients than in adults.

Whether one imaging or nonimaging modality is superior to others in guiding clinical therapy is debatable.

Therapy

Almost all patients with massive reflux on barium studies have pathologic acid reflux in the recumbent position (30); therapy for reflux disease can be started in these patients without need for 24-hour pH monitoring. Stricture dilation and temporary stent insertion have a limited role in benign esophageal strictures; strictures recur unless the underlying disorder is treated. Long-term stenting with expandable