|Year : 2013 | Volume
| Issue : 2 | Page : 132-136
Role of 2-D reformatted images of MDCT in evaluation of small bowel obstruction: A case series
Kamini Gupta, Jaswinder Singh, Kavita Saggar, Amandeep Jassi
Department of Radiodiagnosis, Dayanand Medical College and Hospital, Ludhiana, Punjab, India
|Date of Web Publication||6-Sep-2013|
Department of Radiodiagnosis, Dayanand Medical College and Hospital, Tagore Nagar, Ludhiana - 141 001, Punjab
Source of Support: None, Conflict of Interest: None
The availability of multidetector computed tomography (MDCT) scanners, coupled with imaging workstations that allow multiplanar and three-dimensional (3D) evaluation of isotropic data sets, have allowed improved depiction and characterization of small bowel obstruction (SBO). In this article, we present a series of five cases and emphasize that addition of coronal images to axial images enhance the identification of site and etiology of SBO especially in unusual cases of SBO.
Keywords: Bowel, multidetector computed tomography, obstruction
|How to cite this article:|
Gupta K, Singh J, Saggar K, Jassi A. Role of 2-D reformatted images of MDCT in evaluation of small bowel obstruction: A case series. J Mahatma Gandhi Inst Med Sci 2013;18:132-6
|How to cite this URL:|
Gupta K, Singh J, Saggar K, Jassi A. Role of 2-D reformatted images of MDCT in evaluation of small bowel obstruction: A case series. J Mahatma Gandhi Inst Med Sci [serial online] 2013 [cited 2020 Sep 22];18:132-6. Available from: http://www.jmgims.co.in/text.asp?2013/18/2/132/117793
| Introduction|| |
The utilization of cross-sectional imaging in the evaluation of small bowel has been growing in recent years. This change is attributed to several technological advances in CT imaging, including introduction of multidetector technology; which allows for acquisition of multiple image slices with every gantry rotation, improving temporal and spatial resolution, increasing the area of coverage during a short interval permitting high quality reformatted images to be obtained in multiple planes, and facilitating identification of transition point and other findings of SBO. 
The significantly shorter scanning time improves visualization and assessment of small bowel by decreasing motion artifacts and allows rapid scan acquisition at multiple phases of enhancement. Decreasing slice thickness, on the other hand, improves spatial resolution, leading to acquisition of nearly isotropic voxels and allows for optimal multiplanar reconstruction (MPR) of small bowel and mesentery. 
We present a series of five cases, wherein we describe the importance of MDCT and its two-dimensional (2D) applications in reaching to the correct diagnosis of SBO and providing clues to its etiopathogenesis.
Inclusion Criteria: All the patients, who were clinically suspected of having small gut obstruction.
Exclusion Criteria: Patients with alternative diagnosis on MDCT.
| Case Report|| |
MDCT in all the patients was carried out on Somatom definition AS, 128 slice CT Machine by Siemens Germany Ltd.
| Preparation of patient|| |
Limited section plain CT of upper abdomen without oral and intravenous contrast was done at 100 kV (low dose) in all the patients. If the proximal small gut loops were distended more than 2.5 cm and were fluid filled, then oral contrast was not given. If the small gut loops were collapsed or less distended, then oral contrast for bowel distension either positive or neutral was used, based on patient's clinical diagnosis or as requested by the referring clinician. A 20 mL
of gastrograffin (water soluble ionic contrast) diluted in 1 L of water was used as positive oral contrast and 1 L of polyethylene glycol solution was used as neutral oral contrast; 100 mL of nonionic contrast medium with an iodine content of 300 mg/mL was injected intravenously through a 20-gauge cannula at rate of 3 mL/s using an automated power injector. Intravenous contrast was given to all the patients to diagnose gut ischemia as it is a common complication of small gut obstruction. Scanning was done in portal venous phase in all the cases. Arterial phase was done only if there was clinical suspicion of mesenteric ischemia. Scan area covered from the dome of diaphragm till pubic symphysis in portal venous phase.
Patient was positioned supine on the table. Scanning was done in a single breath hold (less than 10 s) with a 128 slice MDCT scanner at 120 kV, 190-250 mA using Care Dose software. Real-time interactive 2D images were created by using MPR techniques at the available workstation.
| Case 1|| |
A 57-year-old male patient presented with pain in the abdomen and vomiting for 1 day. On examination, his abdomen was distended and tense. On MDCT, proximal and mid small gut loops were filled with air and fluid and were dilated, measuring up to 3 cm. A group of encapsulated normal caliber small gut loops along with mesentery were seen in the right lumbar and iliac region lateral to caecum and ascending colon [Figure 1]. Gut loops within the sac showed poor wall enhancement due to ischemia. Fluid was also seen in the hernial sac. Based on these findings, the diagnosis of strangulated paracecal hernia was given, which was proved on subsequent surgery.
|Figure 1: Paracecal hernia coronal multiplanar reconstruction (MPR) section shows gut loops herniated in the right paracecal location lateral to the cecum (white arrow) and showing minimal mural enhancement. Rest of the small gut loops are dilated and air filled|
Click here to view
| Case 2|| |
A 62-year-old male patient presented with pain in the abdomen, vomiting, and distension for 3 days. He was a known hypertensive with atrial fibrillation and coronary artery disease. On MDCT, small gut loops were dilated till ileocecal junction, measured up to 3.8 cm in caliber. A hypodense thrombus was seen in the superior mesenteric vein (SMV) and its tributaries [Figure 2], white arrows]. Based on these findings a diagnosis of SMV thrombosis with small gut ischemia and functional obstruction was made and the patient was managed conservatively and followed-up.
|Figure 2: Mesenteric ischemia due to superior mesenteric vein (SMV) thrombosis: Coronal MPR section shows hypodense filling defect in the entire SMV and its tributaries (white arrows). Note congestion in the mesentery, free interloop fluid and dilatation of small gut which shows absent mural enhancement|
Click here to view
| Case 3|| |
A 40-year-old male patient presented with sudden pain in right lumbar region with vomiting for 8 h. On examination there was mild distension with tenderness in right lumbar region. MDCT findings revealed dilated fluid filled, mid and distal small gut loops, and zone of transition in right lumbar region with positive small bowel feces sign. A blind, fluid filled, dilated (8 mm) tubular structure measuring 5 cm in length was seen in relation to one of distal small gut loop. Streakiness was seen in the adjacent mesentery. Distal to it, rest of small intestine was normal [Figure 3]. Based on these findings, a diagnosis of Meckel's diverticulitis causing ileus was given and was confirmed on surgery.
|Figure 3: Meckel's diverticulitis: Oblique coronal section shows a dilated blind diverticulum in relation to one of small gut loop showing "positive small bowel feces sign" (white arrow) and normal caliber ileum distally|
Click here to view
| Case 4|| |
A 35-year-old male patient presented with pain in the abdomen with constipation and vomiting. His MDCT revealed fluid filled, dilated (up to 3.8 cm) small gut loops. Caecum was anteriorly and medially rotated and was markedly distended with air [Figure 4], white arrow]. There was stranding in the mesentery with whirling of vessels. These findings were clearly evident in coronal reformatted images than in axial sections. A diagnosis of cecal volvulus causing intestinal obstruction was given and subsequently confirmed on surgery.
|Figure 4: Cecal volvulus: Coronal section anteriorly shows air-filled, distended cecum displaced superomedially (white arrow). Small gut loops are also dilated|
Click here to view
| Case 5|| |
A 45-year-old female patient presented with off and on pain for last 2 months in right hypochondrium. She gave history of its sudden worsening in last 9-10 hours with abdominal distension and constipation. Her MDCT revealed dilatation of small gut loops and presence of hyperdense contents in one of the ileal loop in pelvis just proximal to the zone of transition. Also her gallbladder was collapsed and air filled [Figure 5], black arrow]. A diagnosis of gallstone ileus due to cholecystoduodenal fistula was given and confirmed on surgery.
|Figure 5: Gall stone ileus: Coronal MPR section shows dilatation of small gut loops and presence of hyperdense contents in one of the pelvic ileal loop just proximal to the zone of transition (white arrow). Also her gallbladder was collapsed and air-filled (black arrow)|
Click here to view
| Discussion|| |
With MDCT, the MPR of CT image data facilitates evaluation of small gut and its mesentery.  Reconstructions in any arbitrary plane with a spatial resolution similar to that of the axial plane are possible. 
Diagnosis of bowel obstruction depends on the identification of a transition zone. However, depiction of a definite transition zone is sometimes difficult because of overlapping dilated bowel loops when viewing only axial images. Similarly, it is often difficult to differentiate obstruction from adynamic ileus. In these situations, the easily accessible 2D reconstructed images may help to verify the site, level, and cause of obstruction.  MDCT with coronal reformats generated at the scanner console has a high accuracy for detection of the key features of SBO and results in improved reader confidence. The addition of coronal images is complementary to axial images and does not serve as a replacement for these.  In particular, 2D and three-dimensional (3D) imaging can be helpful in evaluating indeterminate cases on the axial plane, such as volvulus or internal hernia. Multidetector row CT with reformatting at a workstation provides important advantages over conventional imaging methods in evaluation of the small intestine and surrounding structures (mesentery, mesenteric vasculature, and peritoneal cavity).  The additional use of coronal reformations improves diagnostic accuracy and interobserver agreement in the evaluation of patients with abdominal pain, particularly those with less experience. For this reason, radiology departments with residents or other trainees should be encouraged to routinely generate coronal reformations in patients with acute abdominal pain evaluated with MDCT. 
In this series, the diagnosis of paracecal hernia was made with confidence in coronal images as the beaking appearance indicative of tethering at the aperture of peritoneal recess and dilatation of small bowel loops with a transition zone were revealed. Though axial plane plays a central role in the diagnosis of SBO, the adjunct of coronal plane improves reader confidence level. Filippone et al., in their study concluded that in large bowel obstruction, although no differences were found between axial and coronal views in terms of diagnostic accuracy, the best values were observed with combined axial and coronal planes. 
Mesenteric venous thrombosis is an uncommon (less than 15%), but potentially lethal cause of bowel ischemia.  Because the mesentery fans out from its root to suspend the bowel, it is better depicted in an oblique longitudinal plane. 
Oblique coronal images show entire SMV and its branches in one plane and MIP images are clearly advantageous in knowing the extent of thrombus and secondary changes of ischemia in the small bowel as in our case. These images are of maximum information for surgeon as the extent of thrombosis is evident in a single image.
On axial CT, Meckel's diverticulum is difficult to distinguish from normal small bowel in uncomplicated cases. 2D MPR images result in better visualization and consequent higher sensitivity in the diagnosis of Meckel's diverticulitis.  These images clearly show enteroliths, intussusception, diverticulitis, and SBO.
When demonstrating a large bowel volvulus (LBV), the diagnosis criterion is an abrupt transition between a normal and dilated bowel combined with observation of convergence of both ends of the dilated loop towards the fulcrum point, creating closed-loop obstruction. An important sign to look for is the "whirl sign". This is a whirlpool pattern of concentric structures including twisted intestinal loops, vessels, and mesenteric fat that is highly suggestive of a torsion mechanism. The whirl sign is visible, however, only if the view plane is orthogonal to the axis of rotation. Therefore, we should always review our exams using MPR. 
Gallstone ileus is a complication in 0.3-0.5% of all cases of cholelithiasis. MDCT scanners, using MPRs, allow better evaluation of the intestinal segment in which the stone is impacted and its correct morphology, especially when axial findings are indeterminate or doubtful. Correct evaluation of the size is important because stones smaller than 2 cm may not be innocuous; they may become larger by accretion as they descend the intestinal canal and produce reflex spasm and volvulus. 
| Conclusions|| |
MDCT and 2D imaging processes can offer a full examination of small intestine and powerful information about the bowel and its surrounding structures. In most cases of small bowel disease, various post processing technologies can help radiologists make an easy, rapid, and accurate diagnosis while avoiding unnecessary examinations. In addition these images provide a roadmap to operating surgeon. Therefore, knowledge and awareness of each proper application technique of MDCT is essential to achieve the diagnostic goal of one-step imaging.
| References|| |
|1.||Desser TS, Gross M. Multidetector row computed tomography of small bowel obstruction. Semin Ultrasound CT MR 2008;29:308-21. |
|2.||Mahmoud M, Al-Hawary, Kaza RK, Platt JF. MDCT and 3D imaging of the small bowel and mesentery. Appl Radiol 2011;40:11. |
|3.||Johnson PT, Horton KM, Fishman EK. Nonvascular mesenteric disease: Utility of multidetector CT with 3D volume rendering. Radiographics 2009;29:721-40. |
|4.||Zangos S, Steenburg SD, Phillips KD, Kerl JM, Nguyen SA, Herzog C, et al. Acute abdomen: Added diagnostic value of coronal reformations with 64-slice multidetector row computed tomography. Acad Radiol 2007;14:19-27. |
|5.||Caoili EM, Paulson EK. CT of small-bowel obstruction: Another perspective using multiplanar reformations AJR Am J Roentgenol 2000;174:993-8. |
|6.||Shah ZK, Uppot RN, Wargo JA, Hahn PF, Sahani DV. Small bowel obstruction: The value of coronal reformatted images from 16-multidetector computed tomography--a clinicoradiological perspective. J Comput Assist Tomogr 2008;32:23-31. |
|7.||Takeyama N, Gokan T, Ohgiya Y, Satoh S, Hashizume T, Hataya K, et al. CT of internal hernias. Radiographics 2005;25:997-1015. |
|8.||Filippone A, Cianci R, Storto ML. Bowel obstruction: Comparison between multidetector-row CT axial and coronal planes. Abdom Imaging 2007;32:310-6. |
|9.||Kaleya RN, Sammartano RJ, Boley SJ. Aggressive approach to acute mesenteric ischemia. Surg Clin North Am 1992;72:157-82. |
|10.||Coakley FV, Hricak H. Imaging of peritoneal and mesenteric disease: Key concepts for the clinical radiologist. Clin Radiol 1999;54:563-74. |
|11.||Paulsen SR, Huprich JE, Fletcher JG, Booya F, Young BM, Fidler JL, et al. CT enterography as a diagnostic tool in evaluating small bowel disorders: Review of clinical experience with over 700 cases. Radiographics 2006;26:641-57. |
|12.||Vandendries C, Jullès MC, Boulay-Coletta I, Loriau J, Zins M. Diagnosis of colonic volvulus: Findings on multidetector CT with three-dimensional reconstructions. Br J Radiol 2010;83:983-90. |
|13.||Lassandro F, Romano S, Ragozzino A, Rossi G, Valente T, Ferrara I, et al. Role of helical CT in diagnosis of gallstone ileus and related conditions. AJR Am J Roentgenol 2005;185:1159-65. |
[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]