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Imaging Findings in Eating Disorders
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OBJECTIVE. Eating disorders, such as anorexia nervosa and bulimia nervosa, are often undiagnosed but potentially treatable illnesses that, if not identified, can lead to morbidity and death. Often, because of embarrassment or social stigma, patients do not readily admit to these disorders when interviewed by caregivers. Imaging findings can suggest the presence of an eating disorder; understanding these findings allows the radiologist to contribute to the diagnosis of these insidious conditions and alert the referring caregiver. Current concepts in eating disorders and their multimodality imaging findings in several organ systems will be reviewed.
CONCLUSION. After reviewing this article, the radiologist will understand the imaging findings in eating disorders. This knowledge will empower the radiologist to raise the question of a patient's eating disorder, a condition that may be unsuspected by the referring caregiver and could otherwise remain undiagnosed.
Keywords: anorexia, bulimia, eating disorders, radiology
The term “eating disorder” primarily describes two diagnoses—anorexia nervosa and bulimia nervosa. Anorexia is characterized by intense fear of gaining weight and a refusal to maintain a normal body weight and includes both restrictive and binge eating–and-purging types. Bulimia is characterized by repeated episodes of binge eating followed by inappropriate compensatory behaviors, with purging or nonpurging types. These behaviors include vomiting or misuse of laxatives, diuretics, or enemas, in the purging type of bulimia, and fasting or excessive exercise, in the nonpurging type of bulimia [1].
Eating disorders affect approximately 5 million Americans annually. Although most cases of eating disorders involve young women beginning in adolescence, 5–15% of cases occur in male patients [2]. The prevalence of bulimia is often thought to be underestimated because many patients will not come to clinical attention (i.e., patients will not admit to self-induced vomiting, or bulimia is not suspected because of their normal body weight) [3].
Eating disorders are difficult to diagnose and are considered the group of psychiatric illnesses with the highest morbidity and mortality. For example, the mortality rate for young women with anorexia nervosa is 12 times greater than that for other young women in the general population [2, 4]. Patients are often hesitant to disclose a history of an eating disorder or may conceal the history because of social stigma, a lack of awareness of the adverse effects on health, ignorance about available treatments, or an unwillingness to undergo treatment [2]. These factors can prevent patients from obtaining effective treatment, which increases the risk of patients developing the multiple medical complications associated with these disorders. In light of these diagnostic difficulties, radiologists who are aware of the imaging findings in these illnesses may be uniquely positioned to identify the presence of an eating disorder or its complications.
| Current Concepts in Eating Disorders |   |
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Numerous functional neuroimaging modalities are available for evaluation of eating disorders. These modalities include functional MRI used to assess brain activity and PET and SPECT used to study neurotransmitter receptor function and regional cerebral glucose metabolism. Although study results utilizing these techniques have been somewhat inconsistent secondary to varied subject groups, differing states of illness, and other factors, future studies may help elucidate potential pathways of pharmacologic intervention or provide tools to monitor treatment efficacy [5–7]. For example, ongoing PET studies with radioligands targeted to the neuroreceptors and transporters of the serotonin and dopa-mine systems show dysfunction that persists after recovery from illness and are associated with regions of functional abnormality on functional MRI. Future studies utilizing these neurotransmitter systems may help in identifying more effective treatments; alternatively, new drug targets could be identified using PET to elucidate other abnormal neurotransmitter systems [5].
Another area of active investigation related to eating disorders involves the “female athlete triad,” which consists of low energy availability (with or without eating disorders), menstrual dysfunction, and altered bone mineral density (BMD). In female athletes, the components of this triad are present to varying degrees simultaneously and can have significant short- and long-term health effects. Low energy availability may simply be a function of a low calorie diet and vigorous training schedule; however, up to 62% of athletes have symptoms of an eating disorder, and up to 50% of athletes can be osteopenic. Therefore, it is important that female athletes be adequately screened for the components of this triad during sports physicals [8].
| Imaging Findings | |
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Patients with eating disorders often undergo neurologic imaging to evaluate hormonal abnormalities [4] or are imaged in the setting of trauma. In rare cases, brain imaging may be performed to evaluate for cerebral ischemia after cardiopulmonary resuscitation for a fatal cardiac arrhythmia (Fig. 1), the most common cause of death in patients with anorexia [2].
 View larger version (101K) | Fig. 1 —22-year-old woman with bulimia and metabolic disarray who suffered cardiac arrest due to arrhythmia and was successfully resuscitated. She remained obtunded; therefore, brain MRI was performed. Diffusion-weighted image shows subtle diffuse cortical restricted diffusion, most prominent in occipital lobes (arrows), as well as restricted diffusion in basal ganglia and thalami. These findings were considered consistent with hypoxic ischemic injury from patient's prolonged cardiac arrest. |
Neuroimaging findings in patients with anorexia include ventriculomegaly and CSF space enlargement on MRI and CT, with pronounced enlargement of the cortical sulci and interhemispheric fissure (Figs. 2A and 2B). Cerebellar atrophy can also be seen in anorexic patients. These findings have been found to be partially reversible with weight gain and are often therefore termed “pseudo-atrophy” [6, 7, 9].
 View larger version (127K) | Fig. 2A —19-year-old man with anorexia and pituitary hormone abnormalities who presented with constipation and abdominal pain. A, T2-weighted MRI reveals ventriculomegaly (asterisks, A) and enlargement of cortical sulci (arrow, B). |
 View larger version (117K) | Fig. 2B —19-year-old man with anorexia and pituitary hormone abnormalities who presented with constipation and abdominal pain. B, T2-weighted MRI reveals ventriculomegaly (asterisks, A) and enlargement of cortical sulci (arrow, B). |
 View larger version (158K) | Fig. 2C —19-year-old man with anorexia and pituitary hormone abnormalities who presented with constipation and abdominal pain. C, Anteroposterior view of abdomen shows large amount of stool in colon (white arrow), as well as several dilated loops of small bowel in right upper abdomen (black arrow) due to bowel obstruction. |
 View larger version (121K) | Fig. 2D —19-year-old man with anorexia and pituitary hormone abnormalities who presented with constipation and abdominal pain. D, Two years after patient's initial presentation with bowel obstruction, he was still calorie restricting and had short stature at age 21. Left hand radiograph was performed to ascertain patient's bone age. According to bone age standards, his bone age is 16 years. Note presence of open radial and ulnar (black arrow) and phalangeal (white arrow) physes, which close in most healthy patients by age 18 years. |
The neuroimaging findings in bulimia are similar to those in patients with anorexia, but less severe. These findings are more often seen in bulimic patients with chronic dietary restriction [9].
In patients with the purging subtypes of anorexia and bulimia who induce vomiting, aspiration of regurgitated material is a possibility. The diagnosis of aspiration pneumonitis in a patient with dependent pulmonary opacities and a known purging type of eating disorder is relatively straightforward; the diagnosis may be more difficult if the history is withheld [10]. However, in an otherwise healthy young patient with sudden-onset respiratory distress and lower lobe opacities, self-induced vomiting with aspiration is an important consideration.
Aspiration of partially digested food usually appears as opacities in the dependent portions of the lung and may be identified on radiographs (Fig. 3A). Opacities normally clear in 24–48 hours via mucociliary action and coughing. Persistent or progressive worsening of opacities beyond 3 days suggests superimposed infection or deterioration due to acute respiratory distress syndrome [10, 11] (Fig. 3B).
 View larger version (168K) | Fig. 3A —38-year-old woman with previously unknown history of bulimia admitted for hypokalemia and hyponatremia who developed sudden-onset dyspnea. A, Chest radiograph shows acutely developed extensive parenchymal opacities (arrows) in both lower lobes due to aspiration. Causes of patient's symptoms and metabolic abnormalities were unknown until it was revealed that she was inducing vomiting and abusing laxatives in hospital. |
 View larger version (182K) | Fig. 3B —38-year-old woman with previously unknown history of bulimia admitted for hypokalemia and hyponatremia who developed sudden-onset dyspnea. B, Patient continued to deteriorate, and her aspiration event was complicated by acute respiratory distress syndrome. On chest CT, there are small bilateral pleural effusions (asterisks) and diffuse parenchymal opacities. Patient also had anterior bulla on right (arrow), which became infected. |
Studies are currently being pursued linking anorexia and emphysematous changes of the lung. This association was initially observed on postmortem examinations of Warsaw ghetto residents who had died of starvation in World War II. The concept of “nutritional emphysema” has been confirmed in animal studies, in which rats with restricted caloric intake had changes consistent with emphysema during pathologic examination. The results of one of these studies found emphysema-like changes in the lungs of patients who are chronically malnourished when compared with control subjects. The pathophysiology of these emphysema-like changes is thought to be related to a survival mechanism, rather than lung destruction, as in true emphysema. Lung tissue is metabolized to provide substrate for other vital organs, such as the brain and muscle, as body mass and total oxygen consumption decrease [12, 13].
Pneumomediastinum rarely occurs in patients with anorexia and bulimia. Nearly 20 cases of pneumomediastinum associated with eating disorders have been reported in the literature. Most of these cases have been spontaneous pneumomediastinum, thought to result from dissection of air through thinner alveolar walls and pulmonary interstitium secondary to nutritional emphysema. A minority of the cases occurred in conjunction with self-induced vomiting. Pneumomediastinum in patients with eating disorders must be distinguished from secondary pneumomediastinum due to esophageal perforation, because the latter requires surgical intervention. Spontaneous pneumothorax also rarely occurs in this population via the similar proposed mechanisms of dissection of air through thin alveolar walls and pulmonary interstitium [14–17].
Finally, in many patients with eating disorders who are chronically malnourished, the left ventricular mass and cavity size can be decreased [2], leading to a small cardiac silhouette on chest radiographs (Fig. 4A) and a small heart on MRI or CT.
 View larger version (203K) | Fig. 4A —28-year-old woman with anorexia. A, Posteroanterior chest radiograph shows small cardiac silhouette and cachexia. |
 View larger version (159K) | Fig. 4B —28-year-old woman with anorexia. B, Lateral chest radiograph again shows marked loss of subcutaneous fat and musculature that can be seen in anorexia. |
There are several dental and oropharyngeal findings related to eating disorders that the radiologist could encounter. Some studies have found that, in general, patients with eating disorders have poor dentition compared with control subjects, with increased dental caries, peri-apical abnormalities, and missing teeth. This suggestion is controversial because many authors think that these findings are multifactorial and cannot be directly correlated with eating disorders (Fig. 5). The dental abnormalities can be seen in dedicated dental radiographs or incidentally on radiographs and CT scans of the facial bones. Dental abnormalities, although nonspecific, may be the only visible sign of an eating disorder in young patients with bulimia who are normal in weight [18–20].
 View larger version (101K) | Fig. 5 —27-year-old woman with bulimia. Panoramic radiograph of jaw reveals several missing teeth, caries in right and left mandibular first molars (black arrows), and caries of right maxillary molar with fracture (white arrow). There are also small caries involving several other teeth. |
Ten percent to 60% of patients with eating disorders develop sialadenosis, usually enlargement of the parotid or submandibular glands, and in some cases it can be their presenting sign. Glandular enlargement is associated with recurrent vomiting and can be seen on imaging studies, or radiologists may notice the enlarged glands on inspection when encountering a patient directly, such as in the setting of fluoroscopy [18, 21].
Patients with eating disorders often present with nonspecific complaints of abdominal bloating, nausea, epigastric discomfort, and fullness. These symptoms can be secondary to the common underlying gastrointestinal disturbances associated with the pathophysiology of eating disorders, including delayed gastric emptying and constipation, or could be secondary to relatively rare gastrointestinal complications, such as acute gastric dilatation, gastric rupture, superior mesenteric artery (SMA) syndrome, small-bowel obstruction, or rectal prolapse [22–31].
Disturbances in gastrointestinal function in eating disorders can cause patients to present with abdominal pain and are thought to play a role in perpetuating the behavioral characteristics of these syndromes. Delayed gastric emptying and constipation can cause symptoms such as bloating, abdominal distention, and fullness, contributing to early satiety or “feeling fat” in anorexic patients. Delayed gastric emptying can also interfere with treatment of the disease when attempting refeeding. The exact mechanism of delayed gastric emptying in patients with eating disorders is not certain; however, several hypotheses have been proposed, including gastric smooth muscle atrophy secondary to protein malnutrition, gastric autonomic dysrhythmias, or starvation and paucity of food in the stomach [22, 23]. Gastric emptying can be evaluated via scintigraphy in these patients.
There have been several case reports of acute gastric dilatation in anorexic patients after a binge episode or during refeeding, which is thought to occur secondary to the delayed gastric emptying. Patients are unable to vomit the ingested material because of compression of the gastroesophageal junction, and radio-graphs or CT scans reveal a grossly distended stomach. Many patients are treated with nasogastric tube drainage, but some require laparotomy and gastrectomy to prevent or treat complications, including gastric necrosis or perforation [24–27].
A differential diagnostic consideration of acute gastric dilatation in anorexic patients is SMA syndrome. SMA syndrome is caused by compression of the duodenum between the aorta and spine posteriorly and the SMA anteriorly as a result of loss of the adipose tissue that normally surrounds the SMA. Other patients pre-disposed to this condition are those with acute weight loss from burns or surgery. Patients with anorexia may present with chronic abdominal pain, postprandial fullness, and vomiting. On radiographs, the stomach can appear markedly distended (Fig. 6A); however, an abrupt transition point at the dilated third portion of the duodenum as it courses between the SMA and aorta on CT (Fig. 6B) easily differentiates this entity from nonobstructive acute gastric dilatation, in which only the stomach is dilated. Analogous obstructive findings will be found on a barium examination of the upper gastrointestinal tract, which is considered the reference standard for the diagnosis of SMA syndrome. Weight gain is important in the treatment of SMA syndrome; patients may require the insertion of feeding tubes (Fig. 6C) to prevent complications and to safely promote caloric intake [28, 29].
 View larger version (202K) | Fig. 6A —19-year-old man with anorexia who presented with abdominal pain, nausea, and vomiting. (Courtesy of Shortsleeve M, Mount Auburn Hospital, Boston, MA) A, On anteroposterior abdominal radiograph, stomach is distended (black arrows), and there are air-fluid levels in proximal duodenum (white arrow). |
 View larger version (196K) | Fig. 6B —19-year-old man with anorexia who presented with abdominal pain, nausea, and vomiting. (Courtesy of Shortsleeve M, Mount Auburn Hospital, Boston, MA) B, On axial CT, there is abrupt cutoff of third portion of duodenum as it passes between superior mesenteric artery (SMA) and aorta (black arrow), consistent with SMA syndrome. |
 View larger version (56K) | Fig. 6C —19-year-old man with anorexia who presented with abdominal pain, nausea, and vomiting. (Courtesy of Shortsleeve M, Mount Auburn Hospital, Boston, MA) C, Jejunal feeding tube was inserted into this patient with SMA syndrome for safe refeeding. Note persistent gastric dilatation and compression of third portion of duodenum (arrow). |
Gastrointestinal disturbances in bulimic patients include increased gastric capacity, diminished gastric relaxation, diminished postpran-dial release of cholecystokinin, and impaired autonomic activity, all of which contribute to the perpetuation of the disease. Increased gastric capacity allows patients to consume large meals during their binges, and gastric dilatation can be seen on imaging studies [22, 23] (Fig. 7A). Anecdotal evidence from case reports indicates a possible association between bulimia and gastroesophageal reflux and its complications, including esophagitis (Fig. 7B), strictures, ulcers, and adenocarcinoma. A controlled study with longitudinal data has not yet been performed to confirm the association, although it seems probable considering the high frequency of self-induced vomiting in many bulimic patients [3].
 View larger version (154K) | Fig. 7A —61-year-old man with long history of bulimia. A, Axial CT through upper abdomen shows gastric dilatation (arrow). |
 View larger version (120K) | Fig. 7B —61-year-old man with long history of bulimia. B, Axial CT reveals nodular thickening in distal esophagus (black arrows), which was confirmed to be esophagitis on endoscopy. Presence of oral contrast agent in esophagus is abnormal and suggests gastroesophageal reflux. Consolidation in left lower lobe (white arrow) is likely secondary to aspiration. |
Patients with anorexia and bulimia often present with constipation as a result of poor nutrition, dehydration, and impaired intestinal motility. Constipation most commonly results in abdominal bloating and distention but can present with serious medical complications, such as necrotizing colitis or bowel obstruction (Fig. 2C). Some patients with eating disorders may take large amounts of laxatives in response to constipation; however, most use them as a purging mechanism. This leads to electrolyte derangements and further slowing of intestinal motility secondary to hypokalemia [22, 23]. Laxative abuse can lead to cathartic colon, characterized by loss of colonic myenteric neurons. Cathartic colon can be suggested on imaging studies when an ahaustral colon is present with increased submucosal fat [32]. In addition, prolonged use of laxatives, in combination with numerous purging activities causing increased intraabdominal pressure, can lead to rectal prolapse in patients with eating disorders. Because rectal prolapse is usually seen in older women, its presence in a young woman should raise suspicion for an eating disorder. These patients could come to the attention of the radiologist on dynamic pelvic floor MRI or defecography. Patients may also be imaged after surgical correction to assess for complications such as small-bowel obstruction (Fig. 8), abscess, or recurrence (patients often continue purging activities after correction of prolapse) [30, 31, 33].
 View larger version (158K) | Fig. 8A —47-year-old woman with history of bulimia and laxative abuse complicated by rectal prolapse, repaired with rectosigmoid resection and rectopexy, who presented with abdominal pain, nausea, and vomiting due to bowel obstruction. A, On coronal (A) and axial (B) CT of abdomen, there are multiple abnormally dilated loops of small bowel (arrows, A), with decompressed small bowel adjacent to surgical clip (arrow, B). |
 View larger version (112K) | Fig. 8B —47-year-old woman with history of bulimia and laxative abuse complicated by rectal prolapse, repaired with rectosigmoid resection and rectopexy, who presented with abdominal pain, nausea, and vomiting due to bowel obstruction. B, On coronal (A) and axial (B) CT of abdomen, there are multiple abnormally dilated loops of small bowel (arrows, A), with decompressed small bowel adjacent to surgical clip (arrow, B). |
Finally, the presence of an unusual foreign body in the esophagus or stomach on radio-graphs should raise suspicion for an eating disorder. Patients with eating disorders may use objects to induce vomiting and then accidentally ingest them. Although any object may be used, the toothbrush seems to be used frequently, likely because of its presence in the bathroom, where self-induced vomiting most often occurs. The ingested toothbrush has a characteristic appearance on radiographs with parallel rows of short metallic radiodensities when viewed en face, representing the metallic plates that hold the bristles in place (Fig. 9A). A lateral view of a toothbrush projects as a single metallic density strip, because the plates holding the bristles become superimposed (Fig. 9B). Although this behavior can be seen in other mental illnesses, it may be the first clue to the diagnosis of an eating disorder and is one of the easiest for the radiologist to recognize. Recognition of this finding and its immediate communication to the referring physician is important, because the management of ingested foreign bodies includes removal via endoscopy or laparotomy to avoid pressure necrosis or bowel perforation [34, 35].
 View larger version (168K) | Fig. 9A —19-year-old woman with bulimia and foreign body ingestion. A, Anteroposterior view of abdomen shows characteristic en face appearance of ingested toothbrush (arrow) with several parallel rows of short metallic plates that anchor bristles. |
 View larger version (171K) | Fig. 9B —19-year-old woman with bulimia and foreign body ingestion. B, Anteroposterior view of abdomen shows lateral view of ingested toothbrush, which can be identified as single radiopaque strip (arrow) caused by superimposition of metallic plates. |
In many female patients with anorexia, weight loss causes disturbances in the hypothalamic-gonadal axis manifesting as amenorrhea. Menses return in up to 40–50% of adult patients after reaching a target body mass index; the remainder of patients with persistent amenorrhea are at increased risk for impaired fertility and osteoporosis secondary to low estrogen levels. Several studies have therefore supported the use of directly assessing pelvic organ morphologic features and maturity via pelvic sonography to determine a healthy weight target in individual anorexic patients. On pelvic ultrasound in adult anorexic patients with secondary amenorrhea, the uterus regresses to its prepubertal length of 2–3 cm, the endometrium becomes very thin or undetectable, and the ovaries decrease in size to a volume less than 2 cm3. Pelvic ultrasound in the pediatric population with anorexia and primary amenorrhea reveals that the uterus and ovaries are smaller than would be expected for the age of the patient. During treatment, the uterus and ovaries increase in size with sustained weight gain; the appropriate target weight for an individual patient is then determined for a patient when the uterus and ovaries have reached maturity and menstruation occurs [36–38].
Nephrolithiasis and nephrocalcinosis are also imaging findings in patients with eating disorders that are associated with volume depletion and electrolyte and acid-base disturbances, particularly in patients who abuse laxatives [32, 39–41].
Osteoporosis occurs in up to 50% of patients with anorexia, complicated by fractures in nearly 45% of those affected. The risk of fracture is seven times higher in patients who have had anorexia for longer than 5 years than in healthy women of the same age [42]. Relevant is the fact that anorexia often occurs during adolescence, when patients should reach their peak bone mass. Instead, bone loss occurs because of a multitude of causes, including estrogen deficiency in female patients and nutrient deficiencies. Several studies have shown that BMD does not increase into the normal range even years after weight gain and resumption of a normal menstrual cycle, which places these patients at high risk for osteoporosis and fractures (common sites include the vertebrae, radius, and hip) (Fig. 10). Therefore, some suggest that patients with anorexia and recovered anorexic patients should undergo screening for osteoporosis with dual-energy x-ray absorptiometry [2, 42–45].
 View larger version (114K) | Fig. 10 —55-year-old woman with 40-year history of anorexia and osteopenia who presented after fall. Frontal radiograph of right hip shows subcapital femoral fracture (arrows). |
Bone strength, however, is determined not only by BMD but also by bone microarchitecture (i.e., the spatial arrangement of the trabeculae and the mechanical properties of bone), and some studies using flat-panel volume CT have shown deleterious effects on bone microarchitectural parameters in patients with anorexia, even before changes in BMD are evident [46, 47]. There are greater deficits in bone mass in patients whose onset was in adolescence as compared with those with adult-onset disease, highlighting the importance of bone development in adolescence and suggesting that adolescent onset of anorexia impairs bone health later in life [46]. Compared with healthy age-matched control subjects, adolescent girls with anorexia have reductions in apparent trabecular bone volume fraction and apparent trabecular thickness and an increase in apparent trabecular separation, despite similar BMD measurements; this discrepancy suggests that BMD adequately measures bone health in the healthy population, but this may not be true in patients with anorexia [46].
When evaluating anorexic patients for stress or insufficiency fractures, it is important to be aware of features of this disease that can make diagnosis difficult on MRI. Patients with advanced anorexia can exhibit loss of fat signal in the subcutaneous tissues and bone marrow, which can mask the bone marrow edema from an acute fracture. Therefore, bone scintigraphy may be more helpful in identifying otherwise occult fractures in the population with eating disorders [48].
In addition to decreased BMD in adolescents, anorexia can lead to linear growth retardation and short stature, because adequate caloric intake and fat are necessary during puberty for appropriate growth. Imaging findings include delayed bone age on hand radiographs [4, 49, 50] (Fig. 2D).
The clinical findings most classically associated with eating disorders—namely, the extremely low body mass index and lack of subcutaneous fat [1, 2]—can also be seen radiographically (Figs. 4A and 4B). Such findings in an otherwise young healthy patient are suggestive of an eating disorder.
| Conclusion | |
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Eating disorders can affect multiple organ systems with a spectrum of morbidity. Manifestations of these disorders can be identified on multiple imaging modalities and are presented here to increase awareness among radiologists. Because many of the findings are nonspecific and can be seen in other disease processes, interpretation may be best performed in consultation with the referring physician. This knowledge empowers the radiologist to suggest the presence of an occult underlying eating disorder, or, in patients known to be eating disordered, to recognize their complications. In addition, early recognition may prevent future morbidity and mortality in these patients.
| Acknowledgments | |
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We thank Michael Shortsleeve, for his guidance and for providing illustrative cases, and Rebecca Weinstock, whose astute diagnosis was the genesis of this project.
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