Radiography and CT of Adult Large-Bowel Obstruction

A review of the imaging findings in multiple causes of large bowel obstruction and a comparison with acute colonic pseudo-obstruction.

Course ID: Q00469 Category:
Modalities: ,


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Targeted CE per ARRT’s Discipline, Category, and Subcategory classification:
[Note: Discipline-specific Targeted CE credits may be less than the total Category A credits approved for this course.]

Computed Tomography: 1.50
Procedures: 1.50
Abdomen and Pelvis: 1.50

Radiography: 0.50
Procedures: 0.50
Head, Spine and Pelvis Procedures: 0.50

Registered Radiologist Assistant: 2.00
Procedures: 2.00
Abdominal Section: 2.00


  1. Introduction
  2. Clinical Findings and Pathophysology
  3. Abdominal Radiography Technique
    1. Merits of Abdominal Radiography
    2. Challenges of Abdominal Radiography in Patients with LBO
  4. Multidetector CT
    1. CT Technique
    2. Pitfalls of CT Imaging of LBO
  5. The Contrast Enema
  6. LBO: Major Causes
    1. Colon Carcinoma
    2. Volvulus
    3. Sigmoid Volvulus
    4. Cecal Volvulus
    5. Transverse Colon Volvulus
    6. Diverticulitis
    7. Adult Intussusception
    8. Intraluminal Contents Causing LBO
    9. Hernias
    10. Inflammatory Bowel Disease
    11. Adhesions
    12. External Compression
  7. ACPO or Ogilvie Syndrome: An Important Mimic of LBO


Upon completion of this course, students will:

  1. identify the cancer type that represents the vast majority of malignant head and neck tumors in adults
  2. list the particles used in external beam radiation therapy for head and neck tumors
  3. describe the currently preferred radiation therapy option for the head and neck
  4. identify the IMRT dose range delivered to high-risk areas
  5. list the imaging techniques that are routinely used in clinical practice to evaluate head and neck cancers
  6. describe pathologies that exhibit increased water diffusion on DW imaging
  7. explain the units of measurement of the apparent diffusion coefficient (ADC)
  8. understand the diagnostic capabilities of FDG PET/CT for detection of head and neck SCC
  9. recognize the value of FDG PET/CT in the evaluation of head and neck SCC
  10. list the pathologies that may demonstrate increased FDG uptake and lead to false-positive PET/CT image findings
  11. describe the mean SUV range of head and neck SCCs at FDG PET/CT imaging
  12. list the hybrid imaging system design that uses MR imaging-based attenuation correction maps to calculate SUVs
  13. compare the SUVs of focal lesions calculated at PET/MR with those calculated at PET/CT
  14. describe the timing of early effects of high-dose radiation therapy
  15. list the tissue types that typically demonstrate late effects of irradiation
  16. list the late effects of radiation therapy
  17. list the areas affected by radiation therapy-induced superficial lymphedema
  18. describe the tissue features present in a mature scar
  19. identify the imaging features that occur in the presence of scar tissue
  20. define the imaging feature known as “evil gray”
  21. list the body areas that may demonstrate high physiologic nonspecific FDG uptake
  22. describe atypical locations of brown fat
  23. recognize the diagnostic technique used to detect local mucosal destruction
  24. describe the imaging characteristics of soft-tissue necrosis following administration of gadolinium contrast agents
  25. identify the diagnostic techniques recommended for correlation with morphologic imaging when differentiating recurrent disease from benign soft-tissue necrosis
  26. understand the time frame for the occurrence of osteoradionecrosis after radiation therapy
  27. recognize the increased risk for osteoradionecrosis associated with radiation therapy doses of 62-70 Gy
  28. list the most reliable imaging signs of osteoradionecrosis
  29. describe the percentage of patients who may demonstrate chondroradionecrosis with recurrent tumor
  30. recognize the most common manifestation of radiation therapy-induced arteriopathy in the head and neck
  31. understand the effect of radiation therapy in the risk for development of thyroid disorders
  32. identify the brain region typically involved with radiation therapy-induced brain necrosis
  33. list the predisposing factors for radiation therapy-induced optic neuropathy
  34. list the pathologies that may lead to radiation therapy-induced tumors in the head and neck
  35. describe the imaging techniques that have limited value for precise assessment of deep tumor spread in the irradiated neck
  36. identify the diagnostic technique that may be superior to PET/CT, CECT, and MR imaging for detection of small metastatic nodes
  37. describe the diagnostic capabilities of FDG PET when investigating recurrent tumors and nodes after radiation therapy
  38. understand the impact of the positive predictive value of PET/CT in the evaluation of recurrent tumors
  39. list the areas where second primary tumors in patients with head and neck SCC recurrence are most often detected
  40. define miscoregistration due to geometric distortion
  41. describe the parameters of PET reconstructions in the head and neck
  42. list the imaging findings of peritumoral inflammation
  43. describe the percentage of thyroid incidentalomas that can be malignant
  44. identify the pathologic condition that exhibits very low signal intensity on both T1- and T2-weighted MR images
  45. identify the pathologic condition that demonstrates low ADCs