ª Springer Science+Business Media New York 2014
Abdominal Imaging
Abdom Imaging (2014) DOI: 10.1007/s00261-014-0261-3
The bowel wall target sign Jonathan Walter,1 Andres Ayoob,2 David DiSantis2 1 2
College of Medicine, University of Kentucky, Lexington, KY, USA Department of Radiology, University of Kentucky, Lexington, KY, USA
Traditionally, a target configuration describes concentric circles [1]. So when CT depicts abnormally thickened bowel wall as concentric rings of varying attenuation, the imaging appearance has been dubbed the target sign (Fig. 1) [2]. On intravenous contrast enhanced CT without positive enteric contrast material (Fig. 2 a, b), the target sign comprises three rings of alternating attenuation. Two high attenuation value rings—mucosa (inner ring) and muscularis propria (outer ring)—are separated by low attenuation value submucosa (middle ring), presumably reflecting edema or fat [3, 4]. As a differential diagnostic consideration, while the sign is associated with bowel wall thickening of varied etiology (infection, inflammation, ischemia, shock bowel, and radiation), it generally does not occur in neoplasia [5]. Fig. 1. Schematic image of the target sign. High attenuation value inner (mucosa) and outer (muscularis propria) rings, with a middle low attenuation layer (submucosa) interposed. (asterisk marks the bowel lumen)
Correspondence to: Andres Ayoob; email: [email protected]
J. Walter et al.: The bowel wall target sign
References 1. http://dictionary.reference.com/browse/target. Accessed July 24, 2014 2. Balthazar EJ (1991) CT of the gastrointestinal tract: principles and interpretation. AJR Am J Roentgenol 156(1):23–32 3. Gore RM, Balthazar EJ, Ghahremani GG, Miller FH (1996) CT features of ulcerative colitis and Crohn’s disease. AJR Am J Roentgenol 167(1):3–15 4. Jones B, Fishman EK, Hamilton SR, et al. (1986) Submucosal accumulation of fat in inflammatory bowel disease: CT/pathologic correlation. J Comput Assist Tomogr 10(5):759–763 5. Wittenberg J, Harisinghani MG, Jhaveri K, Varghese J, Mueller PR (2002) Algorithmic approach to CT diagnosis of the abnormal bowel wall. Radiographics 22(5):1093–1107
Fig. 2. Target sign in Crohn Disease. CT enterography. (A) Coronal and (B) axial images show the classic three concentric rings of alternating attenuation in a thickened segment of distal ileum. The high attenuation value mucosa (yellow arrows) and muscularis propria (red arrows) are separated by the lower attenuation value submucosa. Note also the mesenteric hyperemia (blue arrow in B) typical of active inflammation
Abdominal Imaging
Abdom Imaging (2014) DOI: 10.1007/s00261-014-0261-3
The bowel wall target sign Jonathan Walter,1 Andres Ayoob,2 David DiSantis2 1 2
College of Medicine, University of Kentucky, Lexington, KY, USA Department of Radiology, University of Kentucky, Lexington, KY, USA
Traditionally, a target configuration describes concentric circles [1]. So when CT depicts abnormally thickened bowel wall as concentric rings of varying attenuation, the imaging appearance has been dubbed the target sign (Fig. 1) [2]. On intravenous contrast enhanced CT without positive enteric contrast material (Fig. 2 a, b), the target sign comprises three rings of alternating attenuation. Two high attenuation value rings—mucosa (inner ring) and muscularis propria (outer ring)—are separated by low attenuation value submucosa (middle ring), presumably reflecting edema or fat [3, 4]. As a differential diagnostic consideration, while the sign is associated with bowel wall thickening of varied etiology (infection, inflammation, ischemia, shock bowel, and radiation), it generally does not occur in neoplasia [5]. Fig. 1. Schematic image of the target sign. High attenuation value inner (mucosa) and outer (muscularis propria) rings, with a middle low attenuation layer (submucosa) interposed. (asterisk marks the bowel lumen)
Correspondence to: Andres Ayoob; email: [email protected]
J. Walter et al.: The bowel wall target sign
References 1. http://dictionary.reference.com/browse/target. Accessed July 24, 2014 2. Balthazar EJ (1991) CT of the gastrointestinal tract: principles and interpretation. AJR Am J Roentgenol 156(1):23–32 3. Gore RM, Balthazar EJ, Ghahremani GG, Miller FH (1996) CT features of ulcerative colitis and Crohn’s disease. AJR Am J Roentgenol 167(1):3–15 4. Jones B, Fishman EK, Hamilton SR, et al. (1986) Submucosal accumulation of fat in inflammatory bowel disease: CT/pathologic correlation. J Comput Assist Tomogr 10(5):759–763 5. Wittenberg J, Harisinghani MG, Jhaveri K, Varghese J, Mueller PR (2002) Algorithmic approach to CT diagnosis of the abnormal bowel wall. Radiographics 22(5):1093–1107
Fig. 2. Target sign in Crohn Disease. CT enterography. (A) Coronal and (B) axial images show the classic three concentric rings of alternating attenuation in a thickened segment of distal ileum. The high attenuation value mucosa (yellow arrows) and muscularis propria (red arrows) are separated by the lower attenuation value submucosa. Note also the mesenteric hyperemia (blue arrow in B) typical of active inflammation
