Introduction to Abdominal Imaging Lecture "Dr. Dykstra" (TEST 2) Flashcards
Abdominal Radiographs
- Often used in the Initial workup in patients complaining of Abdominal Pain
Radiographic Densities (Air & Fat/ Water)
Air:
- Air in normal or Abnormal Location?
- Air with the Small Bowel?
- Obstructed Bowel Gas?
- Extraluminal
Fat/ Water:
- Both densities outline the Margins of the Organs
- Blood, Pus, and Water appear as Water density on Radiographs
- Evaluate for additional densities present that are not Organs (Ex: Masses, Hematomas, Abscesses)
Radiographic Densities (Bones & Metal)
Bones:
- Evaluate bones on every Radiograph, CT, MRI
- Look for other Calcific or Ossific densities including stones
Metal:
- Foreign Bodies, Surgical Clips
Air/ Pneumoperitoneum
- Rule of thumb is that FREE AIR RISES to the most SUPERIOR Portion of the Abdominal Cavity
- Typically best seen on an upright Radiograph
- Left side down Decubitus with a cross table LATERAL FILM is an Alternative Radiograph
a) Detects air between the Liver and Right Lower Ribs
b) May need to be used in patients who are too sick to be placed in an Upright position!!!!!!
Air under the Diaphragm
- Most easily seen and most definitive in Diagnosis
- Best seen on the RIGHT SIDE because the Liver offers a DISTINCT OUTLINE between the Free Air and the Soft Tissue
- On the LEFT SIDE, t can be DIFFICULT to distinguish from air in the Stomach or Splenic Flexure
Rigler’s Sign
- Produced when BOTH SIDES of the Bowel Wall become OUTLINED by AIR
- Normally, only the INNER ASPECT of the Bowel may be defined by AIR
- When free air exists, both sides of the Bowel Wall CAN BE SEEN (Also called the Double-Wall Sign)
- Typically seen on Supine Radiographs
- Requires a significant amount of FREE AIR WITHIN the Abdomen
Free Air
- Free air can collect over the Liver on SUPINE RADIOGRAPHS and OUTLINE the edges of the FALCIFORM LIGAMENT
- Air can also Collect in MORRIS’S POUCH (Inferior to the Liver and above the Right Kidney)
Causes of Free Air
1) Perforated Viscus:
- Peptic Ulcer Disease
- Penetrating Trauma
- Diverticulitis
- Bowel Obstruction
2) Inflammatory Conditions:
- Toxic Megacolon
- TB
- Peritoneal Inflammation
3) Iatrogenic:
- Postsurgical/ post Laparoscopy/ Endoscopy
- Peritoneal Dialysis
4) Intrathoracic Causes
5) Pneumatosis Intestinalis
Soft Tissue Masses
- Evaluate for Bowel Displacement (Lact of Gas in an area that normally contains air)
- Extrinsic impression of a Mass on a Bowel Loop
- Edge of a Soft Tissue Mass
Calcifications/ Ossifications
- Renal Stones
- Appendicolith
- Gallstones
- Renal Cyst Wall
- Gallbladder Wall
- Atherosclerotic Calcification of the Aorta
- Urinary Bladder Stones
- Fibroids
Bowel Gas Patterns
- Air in the Stomach is ALWAYS NORMAL
- Normal to see Air scattered in 1 to 2 loops of Small Bowel which is of Normal Caliber
- ABNORMAL is GREATER THAN 3 LOOPS of Small Bowel with Scattered Air
- Almost always see air in the Rectum and Sigmoid
Normal Air-Fluid Levels
1) Stomach (Unless on a SUPINE FILM)
2) Small Bowel (Two or Three LEVELS Allowed)
3) Large Bowel (NOT Typically Seen)
Small Bowel vs Large Bowel
SMALL BOWEL:
- Tends to be more CENTRALLY LCOATED
- VALVULAE Extend across the ENTIRE LUMEN
- Less than 3 cm in Diameter
LARGE BOWEL:
- Tends to be PERIPHERALLY Located
- HAUSTRA DO NOT Extend from Wall to Wall
Abnormal Gas Patterns
1) ILEUS:
- bowel Dilation WITHOUT Mechanical Obstruction
Causes of Ileus:
- Metabolic Disorders
- Medications
- Ischemia
- Recent Surgery
- Localized abdominal pain caused by Appendicitis, Pancreatitis, etc, may cause Focal Small Bowel Dilation with Air- Fluid Levels (SENTINEL LOOPS)
- Neuromuscular and Motility abnormalities
- Sprue
2) MECHANICAL OBSTRUCTION:
- Small Bowel Obstruction
- large Bowel Obstruction
Ileus
- 1 to 2 persistently Dilated Loops of Small or Large Bowel
- Air IN RECTUM or SIGMOID
- May see air Fluid Levels, but are NONDIFFERENTIAL (Are Equal Heights within the same Bowel Loop)
- May resemble early or partial SBO
