Pictorial review of bowel ultrasound: Common and unsuspected pathologies

Pictorial review of bowel ultrasound: Common and unsuspected pathologies Poster No.: C-1668 Congress: ECR 2013 Type: Educational Exhibit Authors: A. Law, A. Ali, G. Hutchison; Bolton/UK Keywords: Ultrasound-Colour Doppler, Ultrasound, Abdomen, Small bowel, Gastrointestinal tract, Diagnostic procedure, Inflammation DOI: 10.1594/ecr2013/C-1668 Any information contained in this pdf file is automatically generated from digital material submitted to EPOS by third parties in the form of scientific presentations. References to any names, marks, products, or services of third parties or hypertext links to thirdparty sites or information are provided solely as a convenience to you and do not in any way constitute or imply ECR's endorsement, sponsorship or recommendation of the third party, information, product or service. ECR is not responsible for the content of these pages and does not make any representations regarding the content or accuracy of material in this file. As per copyright regulations, any unauthorised use of the material or parts thereof as well as commercial reproduction or multiple distribution by any traditional or electronically based reproduction/publication method ist strictly prohibited. You agree to defend, indemnify, and hold ECR harmless from and against any and all claims, damages, costs, and expenses, including attorneys' fees, arising from or related to your use of these pages. Please note: Links to movies, ppt slideshows and any other multimedia files are not available in the pdf version of presentations. www.myesr.org Page 1 of 58

Learning objectives 1. 2. To understand the common indications for bowel ultrasound. To illustrate the range of bowel pathologies detected on ultrasound. Background Ultrasound (US) has many advantages, including safety, availability, low cost, real-time dynamic imaging and lack of ionising radiation. However, bowel US can be technically challenging and therefore under-utilised. In our hospital, bowel US is performed regularly. The main indications are small bowel Crohn's disease and appendicitis. Crohn's disease is a chronic inflammatory condition of the gastro-intestinal tract with high incidence in United Kingdom. The small bowel is involved in 80% of cases, most commonly the terminal ileum (1). Patients often need repeated imaging to assess disease status. Imaging modality such as US, which is non-invasive and well tolerated is advantageous. US is useful for primary diagnosis, monitoring treatment response and detecting recurrence and complications. Appendicitis can occur at any age but more frequently in children and young adults. Presentation of acute appendicitis can be atypical and it needs to be differentiated from other clinical conditions with similar symptoms. Diagnosis of appendicitis is not always straight-forward and delayed diagnosis can result in serious complications (7). The main goal of imaging in suspected appendicitis is to reach the diagnosis quickly, using noninvasive and preferably radiation free means. If appendicitis is excluded, unnecessary surgery can be avoided. Even on routine general abdominal US, the bowel should not be neglected, as significant unsuspected pathologies can be diagnosed. Imaging findings OR Procedure details Bowel Ultrasound: Page 2 of 58

Following general abdominal survey with curvilinear 4MHz transducer, a 9MHz linear transducer is used to image the bowel wall in more detail. It is important to recognise the appearance of normal bowel wall (Fig. 1), colour Doppler signal (Fig. 2), mesenteric fat (Fig. 3) and peristalsis (Fig.4). 5 layered structure of normal bowel wall: 1. 2. 3. 4. 5. Echogenic - superficial mucosal interface Hypoechoic - deep mucosa Echogenic - submucosa Hypoechoic - muscularis propria Echogenic - serosa and subserosal fat Page 3 of 58

Fig. 1: Normal 'gut signature' seen in the terminal ileum. Page 4 of 58

Fig. 2: There is little colour Doppler signal in the normal small bowel wall. Flow in normal mesenteric (short arrow) and pelvic vessels (long arrow). Page 5 of 58

Fig. 3: Transverse image of normal terminal ileum (long arrow)and caecum (thick arrow). Normal mesenteric fat has a slightly striated appearance (short thin arrow). Page 6 of 58

Fig. 4: Normal terminal ileum and normal small bowel peristalsis Crohn's disease: US can accurately demonstrate features of Crohn's disease, with reported sensitivity and specificity of 89.7% and 95.6% (5). In our hospital, US is often the primary imaging investigation in suspected small bowel Crohn's disease. Small bowel US is performed with a 4 hour fast, but no laxatives, luminal contrast or intravenous contrast is used. Indications for small bowel US in Crohn's disease: 1. 2. 3. 4. Initial diagnosis Assessing treatment response in symptomatic and asymptomatic patients Assessing known patients presenting with new acute symptoms Detecting post-operative recurrence Limitations: 1. Accuracy highly dependent on operator experience Page 7 of 58

2. 3. 4. 5. Assessment suboptimal in obese patients and with excessive bowel gas Difficult to assess whole of small bowel (e.g. proximal jejunum and deep pelvic loops) Assessment more difficult if multiple skip lesions and long segments of disease Less sensitive than CT and MR for detection of complications such as perforation Sonographic features of Crohn's disease (2): 1. 2. 3. 4. 5. 6. 7. 8. 9. Symmetric or asymmetric wall thickening (>4mm) - Fig. 5 Hyperaemia of bowel wall and mesentery- Fig. 6 'Fat wrapping' or 'creeping fat sign' seen with long-standing transmural inflammation, specific sign for Crohn's disease - Fig. 7 Mesenteric inflammatory mass - Fig.8 and 9 Reduced or absent peristalsis - Fig.10 Loss of mural stratification or normal 'gut signature' - Fig. 11 Presence of complications e.g stricture, fistula, abscess - Fig. 12 Pseudosacculations and skip lesions Reactive mesenteric lymphadenopathy - Fig. 13 Page 8 of 58

Fig. 5: Thickened terminal ileum (8mm) in active Crohn's disease Page 9 of 58

Fig. 6: Hyperaemic inflamed terminal ileum with increased signal on colour Doppler of bowel wall. Page 10 of 58

Fig. 7: 'Fat wrapping'. Bulky echogenic fibrofatty proliferation encircling the inflamed bowel (arrow). Page 11 of 58

Fig. 8: Hypoechoic mesenteric inflammatory mass, with ill-defined border, no identifiable wall or liquefaction, features which help differentiate it from an abscess. Page 12 of 58

Fig. 9: CT shows corresponding right iliac fossa ill-defined soft tissue density mesenteric inflammatory mass (short arrow) adjacent to inflamed terminal ileum (long arrow). Page 13 of 58

Fig. 10: Reduced peristalsis and a 'stiff' wall, secondary to chronic Crohn's disease Page 14 of 58

Fig. 11: Thickened hypoechoic inflamed terminal ileum with loss of layered structure Page 15 of 58

Fig. 12: Crohn's disease patient with thick-walled pelvic abscess containing fluid, gas and echogenic debris Page 16 of 58

Fig. 13: Enlarged oval hypoechoic ileo-colic node in patient with active terminal ileal Crohn's disease This cineloop (Fig.14) of a patient with active terminal ileal Crohn's demonstrates several of the sonographic features described above. Page 17 of 58

Fig. 14: Active terminal ileal Crohn's disease with wall thickening, loss of layered structure due to transmural inflammation and 'fat wrapping' US is useful for assessment of treatment response, signs of which include reduction in wall thickness and colour Doppler signal. In a patient with thickened distal ileum and marked 'fat wrapping' on initial scan (Fig. 7), after 1 year of biologic therapy, distal ileum is less thickened, not hyperaemic and there is resolution of 'fat wrapping' (Fig. 15). Page 18 of 58

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Fig. 15: Distal ileum less thickened, not hyperaemic (not shown) and 'fat wrapping' no longer seen Complications of Crohn's disease can be seen on US. Patient developed a discharging cutaneous opening 7 months after right hemi-colectomy for Crohn's disease. US demonstrates an enterocutaneous fistula communicating with an inflamed neo-terminal ileum (Fig. 16). Fig. 16: Inflamed neo-terminal ileum (long arrow) fistulating to skin surface (short arrow) Strictures can cause abdominal pain and obstructive symptoms. US can help differentiate between stenosis due to potentially reversible inflammation and oedema and fibrotic strictures. Patient with terminal ileal stenosis shows features of active inflammation on US (Fig.17), therefore medical therapy escalated rather than proceeding to surgery. Page 20 of 58

Fig. 17: Thickened terminal ileal wall(double arrow) with narrowed lumen (+) and marked increase in colour Doppler signal in keeping with active inflammation. Upstream small bowel dilated(long arrow) US can detect post-operative recurrence of Crohn's disease, often seen in neoterminal ileum or at the ileocolic anastomosis. In a patient who could not tolerate colonoscopy, US shows normal anastomosis but disease recurrence in the neoterminal ileum (Fig 18 to 19). Page 21 of 58

Fig. 18: Normal appearances at ileo-colic anastomosis Page 22 of 58

Fig. 19: Thickened hyperaemic inflamed neo-terminal ileum proximal to the normal anastomosis Symptoms of appendiceal involvement in ileocaecal Crohn's disease and acute appendicitis can overlap, but the former does not require appendicectomy. On US, appendix can be thickened, with increased colour Doppler signal in both conditions (3). Mildly thickened appendix associated with thickened hyperaemic terminal ileum (#5mm) and caecum, are suggestive of Crohn's disease (3). In a patient presenting with right iliac fossa pain, appendix is mildly thickened (6mm) and hyperaemic but terminal ileum is more thickened with features of active Crohn's disease, not acute appendicitis (Fig. 20 and 21). Page 23 of 58

Fig. 20: Mildly thickened appendix measuring 6mm (short arrow). More thickened terminal ileum showing focal hypoechoic transmural inflammation in keeping with active Crohn's disease Page 24 of 58

Fig. 21: Both terminal ileum and appendix are hyperaemic, with increased signal on colour Doppler In a different patient with a mildly thickened appendix (Fig 22), but moderately thickened terminal ileum (Fig. 11) and caecum (Fig. 23). Appendicectomy showed no histological evidence of acute appendicitis. Page 25 of 58

Fig. 22: Mildly thickened appendix (7mm diameter), not inflamed on histology Page 26 of 58

Fig. 23: Caecal wall thickening (5mm) with prominent echogenic submucosal layer (arrow), secondary to active Crohn's disease Appendicitis: The main use of US is to help in diagnosis of clinically equivocal cases. Page 27 of 58

Reported accuracy of diagnosing appendicitis with US is greatly varied with a sensitivity of 44%-94% and specificity of 47%-95 % (8). Similar to the small bowel, we assess the appendix with a 9MHz linear transducer using a graded compression technique, in longitudinal and transverse planes. Normal sonographic appearance of the appendix (Fig. 24) 1. 2. 3. 4. Blind-ending tubular structure Compressible with an ovoid configuration in the transverse plane < 6mm diameter No peristalsis (c.f. peristalsis seen in normal terminal ileum) Fig. 24: Normal appendix measuring 3mm diameter retaining the layered structure Sonographic features of acute appendicitis: 1. Non-compressible blind-ending tubular structure Page 28 of 58

2. 3. 4. 5. 6. Diameter #6mm Hyperaemia with increased signal on colour Doppler (Fig.25) Echogenic peri-appendiceal fat (Fig.26) Pericaecal or periappendiceal free fluid, extraluminal gas or abscess Appendicolith with obstruction (Fig.32) Fig. 25: Thickened hyperaemic appendix (10mm diameter) with increased signal on colour Doppler. Confirmed appendicitis at surgery Page 29 of 58

Fig. 26: Same patient as Fig.25. Thickened appendix (short arrow) and echogenic periappendiceal fat (long arrow) Pitfalls in diagnosis of appendicitis on US: Normal appendix can also appear mildly dilated on US (6-9mm), which is a potential imaging pitfall (Fig. 27). Appendicitis therefore should not be diagnosed on size alone without other sonographic features listed above. Page 30 of 58

Fig. 27: Fluid-filled mildly dilated appendix (8mm diameter) incidentally noted in an asymptomatic patient Page 31 of 58

Prominent hypoechoic mucosal layer due to lymphoid hyperplasia can cause mild thickening of the appendix (Fig. 28 and 29). Although this finding can be seen in a normal appendix, it is more prominent in viral gastroenteritis and mesenteric lymphadenitis. Fig. 28: Mildly thickened appendix (6mm diameter) incorrectly diagnosed as appendicitis. Appendix not inflamed at surgery. Prominent hypoechoic mucosal layer (arrow) Page 32 of 58

Fig. 29: Transverse image of appendix in same patient. Note periappendiceal fat is normal in echotexture (arrow) Sometimes appendicitis is confined to the distal tip. Therefore appendicitis cannot be excluded unless entire length of appendix is visualised (Fig.30) Page 33 of 58

Fig. 30: Normal non-thickened proximal appendix. Distal portion thickened, with surrounding echogenic periappendiceal fat. Confirmed distal appendicitis at surgery. Atypical presentation of appendicitis: Appendicitis can present with atypical symptoms, mimicking other diagnoses. A child presenting with right loin pain is treated for suspected pyelonephritis. US shows perforated appendicitis in a high subhepatic location with appendicolith and an abscess anterior to the right kidney (Fig. 31). Page 34 of 58

Fig. 31: Perforated appendicitis with appendicolith (calipers) and abscess (long arrow) anterior to right kidney (short arrow) Similarly a child presenting with fever and suprapubic pain is suspected to have a urinary tract infection. US shows an inflamed appendix in the right pelvis with an appendicolith (Fig.32) and an abscess adjacent to the bladder (Fig.33), causing right sided hydronephrosis (not shown). Page 35 of 58

Fig. 32: Dilated appendix (arrow) containing appendicolith (calipers). Page 36 of 58

Fig. 33: Pelvic abscess (calipers) adjacent to bladder giving rise to cystitis symptoms Unusual appendix pathologies: Appendiceal diverticulitis is a rare entity and is found in 0.13 % of appendicectomies (9). It can mimic appendicitis and pre-operative diagnosis on US is usually difficult. Page 37 of 58

An elderly patient presents with suspected appendicitis. US shows a dilated appendix with two inflamed diverticula (Fig.34) Fig. 34: Dilated appendix with 2 inflamed diverticula (arrows). Page 38 of 58

De Garengeot's hernia is when the appendix is incarcerated in a femoral hernia (10). Fig.35 shows a dilated inflamed appendix which is trapped in a femoral hernia. The appendix could be traced into the right iliac fossa. Fig. 35: Dilated appendix (calipers), echogenic inflamed periappendiceal fat (arrow) and fluid in femoral hernia Page 39 of 58

Unsuspected pathologies: Ultrasound can detect a range of unsuspected bowel pathologies, including intussusception, colonic diverticulitis, gastric and colonic carcinoma. Colonic diverticulitis: Colonic diverticulitis is uncommon before the age of 40 years and increases in frequency with age (6) Sonographic features of diverticulitis (4): 1. 2. 3. 4. Colonic thickening >4mm Echogenic inflammatory change in pericolic fat Visualisation of the diverticula - saccular out-pouchings Complications e.g. perforation and intramural or pericolic abscess 37 year-old female patient presenting with left pelvic pain and was suspected to have a gynaecological pathology. However, US shows sigmoid diverticulitis (Fig.36). Page 40 of 58

Fig. 36: Thickened sigmoid colon (short arrow). Inflamed diverticulum (long arrow) has echogenic centre, hypoechoic rim and surrounding inflamed echogenic fat Another patient presenting with right iliac fossa pain and suspected appendicitis had an US which shows perforated diverticulitis in a low lying loop of proximal transverse colon (Fig.37 and 38) confirmed on CT (Fig.39). Page 41 of 58

Fig. 37: Thickened colonic wall (short arrow) and inflamed diverticulum (long arrow) Page 42 of 58

Fig. 38: Same patient. Thickened colonic wall (short arrow) and echogenic pericolic free gas (long arrow) Page 43 of 58

Fig. 39: CT abdomen shows inflamed diverticulum (short arrow) and free gas (long arrow) corresponding to US findings. Gastrointestinal malignancy: Due to low sensitivity, abdominal US is not an effective screening technique for diagnosis of gastric or colonic tumours (4). However, these can be incidentally found on routine scans for non-specific gastrointestinal symtpoms. During abdominal US for weight loss and abdominal pain, a large gastric tumour is detected (Fig. 40 and 41). Page 44 of 58

Fig. 40: Circumferential, hypoechoic, irregular gastric wall thickening with loss of stratified layers. Page 45 of 58

Fig. 41: Gastric tumour is seen in transverse section with an echogenic central region (short arrow) surrounded by a hypoechoic rim (long arrow), so called "pseudo-kidney" sign. The corresponding CT scan shows diffuse gastric malignancy with linitus plastica infiltrative pattern, proven histologically to be a signet ring cell tumour (Fig.42). Page 46 of 58

Fig. 42: Coronal reformat CT image shows diffuse gastric malignancy Reduced peristalsis can be noted in gastric tumours secondary to poor compliance. Evaluation of vascularity is not usually helpful in distinguishing benign and malignant gastric tumours (11). 48 year-old man presenting with 2 month history of food related epigastric pain had US to exclude gall-bladder stone. However, US scan revealed an unsuspected colonic tumour (Fig.43 and 44) appearance correlates well with subsequent staging CT (Fig.45). Page 47 of 58

Fig. 43: Layered structure seen in the normal transverse colon (short arrow). Irregular hypoechoic mass with loss of bowel wall stratification confirmed on histology to be colonic carcinoma(long arrow) Page 48 of 58

Fig. 44: Transverse image of colonic tumour (thick arrow) with band of tumour (short arrow) extending to stomach (long arrow). Page 49 of 58

Fig. 45: Coronal reformat CT image shows cancer of mid transverse colon (thick arrow) with band of tumour (short arrow) extending to the stomach (long arrow). Intussusception: Only 5-10% of all intussusceptions occur in adults but an organic cause is found in up to 90% (4). 22 year-old man presenting with swelling in right iliac fossa was suspected to have an incisional hernia from previous appendicectomy. However, US demonstrates an ileo-colic intussusception, which was shown to be secondary to active Crohn's disease at surgery (Fig.46). Page 50 of 58

Fig. 46: Hypoechoic ileum is the intussusceptum (long arrow) within the thickened ascending colon, which is the intussuscipiens (thick arrow). Echogenic invaginated mesenteric fat also seen (short arrow) Images for this section: Page 51 of 58

Fig. 6: Hyperaemic inflamed terminal ileum with increased signal on colour Doppler of bowel wall. Page 52 of 58

Fig. 7: 'Fat wrapping'. Bulky echogenic fibrofatty proliferation encircling the inflamed bowel (arrow). Page 53 of 58

Fig. 25: Thickened hyperaemic appendix (10mm diameter) with increased signal on colour Doppler. Confirmed appendicitis at surgery Page 54 of 58

Fig. 36: Thickened sigmoid colon (short arrow). Inflamed diverticulum (long arrow) has echogenic centre, hypoechoic rim and surrounding inflamed echogenic fat Page 55 of 58

Fig. 40: Circumferential, hypoechoic, irregular gastric wall thickening with loss of stratified layers. Page 56 of 58

Fig. 46: Hypoechoic ileum is the intussusceptum (long arrow) within the thickened ascending colon, which is the intussuscipiens (thick arrow). Echogenic invaginated mesenteric fat also seen (short arrow) Page 57 of 58

Conclusion Ultrasound is a safe, well tolerated and sensitive imaging modality for assessment of acute and chronic inflammatory disorders of the gastro-intestinal tract, particularly Crohn's disease and appendicitis. Significant unsuspected bowel pathologies can also be detected and therefore the bowel should not be overlooked on abdominal ultrasound scans. References 1. Furukawa A, Saotome T, Yamasaki M, et al. Cross-sectional imaging in Crohn disease. Radiographics 2004; 24:689-702 2. Sarrazin J, Wilson SR. Manifestations of Crohn disease at US. RadioGraphics 1996;16:499-520 3. Ripollés et al. Appendiceal involvement in Crohn's Disease: Gray-scale sonography and color Doppler flow features. AJR 2006; 186:1071-1078 4. Ledermann H P et al. Bowel wall thickening on transabdominal sonography. AJR 2000; 174:107-115 5. Duigenan S, Gee M. Imaging of pediatric patients with inflammatory bowel disease. AJR 2012; 199:907-915 6. Vijayaraghavan SB. High-resolution sonographic spectrum of diverticulosis, diverticulitis, and their complications. J Ultrasound Med 2006; 25:75-85 7. Sivit CJ et al. When appendicitis is suspected in children. Radiographics 2001; 21: 247-262. 8. Kessler N et al. Appendicitis : Evaluation of sensitivity, specificity and predictive values of US, Doppler US and laboratory findings. Radiology 2004; 230:472-478. 9. Heffernan DS et al. A case of appendiceal diverticulitis and a review of literature. Irish journal of Medicine 2009; 178 : 519-521 10. Chung A, Goel A. De Garengeot's hernia. NEJM 2009. 11. Maconi G, Bianchi Porro G. Ultrasound of the Gastrointestinal Tract. Personal Information Page 58 of 58