Radiological Anatomy of the Abdomen and Pelvis.

Dr/ ABD ALLAH NAZEER. MD.

Imaging Modalities for the Abdomen and Pelvis.

• Commonly utilized:• Ultrasound• CT (computed tomography)• Radiography• Abdominal plain film• Fluoroscopy– Hysterosalpingography• Other modalities: • MRI– Magnetic resonance imaging• Nuclear medicine– Gallium scan• Positron Emission Tomography (PET).

X - RAY --- FOUR BASIC DENSITIES

Air.

Soft tissue.

Fat.

Bone.

Ultrasonography (ultrasound)• Uses sound waves of frequencies 2 to 17 MHz. (Audible sound is in the range of 20 Hz to 20 kHz.).• Like SONAR, images result from the propagation of sound waves through the body and their reflection frominterfaces within the body.• The time it takes for the sound waves to return to the transducer provides information on the position of the tissue in the body. No ionizing radiation– Uses sound waves to visualize structures• Very operator dependent.• Can not penetrate bone.

Gray scale = anatomy Gallstones

Fetus in uteroColour Doppler = velocity and direction

CT – computed tomography.• Cross-sectional modality with capabilities for multiplanar reconstruction and dynamic imaging to assess vascularity•Tube rotates around the body and a circle of stationary detectors detects the penetrating x-rays forming an image.

MRI -Magnetic Resonance Imaging.• Uses a high-field magnet to image the body.• Rapidly switching magnetic field gradients align the precession of the H protons (water and fat).• When the gradients are turned off, a faint radiofrequency signal is produced.• Image is reconstructed using Fourier transforms.• Multiplanar and vascular assessment possible.

Fluoroscopy• Dynamic radiography– Permits real-time evaluation of the gastrointestinal tract– Barium Swallow (esophagus)– Upper GI Series (stomach)– Small Bowel Follow-through– Barium Enema (colon)• Barium (& air) is introduced by enema or swallowing• Barium appears white on the images (high density attenuates the x-ray beam)• Can assess both intrinsic(mucosal) and some extrinsic(mass-effect) abnormalities.

Nuclear Medicine - GI Bleeding Scan• Evaluates bleeding, particularly from the lower GI tract.• Radiopharmaceutical = Tc99m in vitro labelled RBCs.• Sequential 5 minute images acquired over an hour.• Looking for progressive accumulation of tracer.

Bleeding on the cecum.

Introduction.• The primary imaging modalities for the abdomen and pelvis are plain film, ultrasound, and CT. • Most common indications for imaging include pain, trauma, distention, nausea, vomiting, and/or change in bowel habits.• Choice of modality depends upon clinical symptoms, patient age & gender, and findings on physical exam.• Mastery of the anatomy within each quadrant can help explain particular symptoms, clinical presentations, and/or imaging findings.

Reading the Abdominal Plain Film.• Also known as the“KUB” (kidney, ureter, &bladder).• Use a systematic approach toInterpretation.– Lung bases & diaphragms.– Bones.– Soft tissues.• Abnormal calcifications.• Organs.

Stomach

AP SUPINE ABDOMEN X-RAY GAS PATTERN.

• Colon has sacculations called haustra as teniae coli are shorter than the colonic wall• Colon is relatively peripheral but can be very mobile

Plain Film Soft tissues : Liver, Spleen, & Kidney.

Soft Tissue Structures: Subtle on KUB.

What’s Up on an Abdominal Film?

• Always check the lung bases for an infiltrate.• Look for free air on the upright film: commonly beneath the right hemidiaphragm.

Free air under right hemidiaphragm due to perforated duodenal ulcer

Diaphragm

Liver edge

STOMACH

WITHOUT CONTRAST

COLON

UPPER GI ORAL BARIUM CONTRAST. BARIUM ENEMA.

UPPER GASTRIC STUDY

BARIUM FILLED STOMACH.

SMALL BOWEL

Calcifications, Metallic Surgical and Foreign Bodies

AP ABDOMEN(MALE).

AP ABDOMENFEMALE.

Gallbladder

Common bile duct

Gallbladder stones.

Right common iliac vein.

MR Angiography.Right pelvic renal transplantas seen on MRA.

CT cross sectional anatomy.

MRI anatomy images of the abdomen.

BILIARY TRACT SCANHIDA SCAN.

Hepato-biliary scan.

MRA.

AORTOGRAM

INFERIORVENA CAVAGRAM

Conclusions• The primary imaging modalities for the abdomen and pelvis are plain film, ultrasound, and CT.• Basic anatomic knowledge can improve the diagnostic value of the radiological imaging.• Correct use of anatomic terms facilitates communication with referring clinicians.• Choice of modality depends upon clinical symptoms, patient age & gender, and findings on physical exam.• Mastery of the anatomy within each quadrant can help explain particular symptoms, clinical presentations, and/or imaging findings.

Thank You.