Anatomy - American College of...

AbdomenImaging Overview

Anatomy

Before You Begin

This module, intended for pre-clinical medical students, is part of the core anatomy teaching series. There should be no prerequisite knowledge necessary for medical students to successfully review and understand this module.

Many of the additional module series in our website build off a strong understanding of human anatomy as it presents in imaging. Please refer back to these anatomy modules if you ever need to review.

If material is repeated from another module, it will be outlined as this text is so that you are aware

Introduction

• The abdomen consists of:• Abdominal Wall

• Upper GI Tract

• Lower GI Tract

• Kidneys and Retroperitoneum

• Inguinal Region

• In this module, we will explore basic abdominal anatomy identifiable with common imaging modalities

Basic Anatomy Overview

Plain Film Radiographs

Abdominal Radiographs• Utilize ionizing radiation to

capture images

• Material density determines the degree of X-ray attenuation, and thus, appearance:

Gas (Air)

Soft Tissue (Water)

Metal

Fat

Bone

Consider Positioning• Remember that gas rises; bowel gas pattern can thereby

indicate patient positioning:

Supine Upright

• Identify density variations to determine tissue interfaces and distinguish organs

Approach to Interpretation

Approach to Interpretation• Trace out the bowel in a segmental fashion (note that not all

segments will be visible, depending on gas distribution)

Stomach

Cecum

Descending Colon

10

Liver lobe edge

11

R. kidney L. psoas

12

Medulla

Minor calyx

Renal pelvis

Papilla

Renal pyramid

Ureter

Cortex

Computed Tomography (CT)

CT Abdomen

• Utilizes ionizing radiation to produce cross-sectional images

• Digital “windowing” can highlight specific tissues

• Note the patient orientation shown to the left

Anterior

Posterior

RightLeft

Lesser Sac

Falciform Ligament

LiverGastrosplenicLigament

Left Subphrenic space

Right Subphrenicspace

Lesser Sac

Gastrohepatic Ligament

Pancreas

Lesser Sac

Peritoneum and Retroperitoneum

Spine

LKAIVC

RK

Spatial Relationships Overview

Lesser Sac

Falciform Ligament

LiverGastrosplenicLigament

Left Subphrenic space

Right Subphrenicspace

Lesser Sac

Gastrohepatic Ligament

Pancreas

Lesser Sac

Peritoneum and Retroperitoneum

Spine

LKAIVC

RK

Spatial Relationships Overview

A. Near midline

Stomach

Colon

Lesser Sac

Pancr

3rd

Duod

Coronary Ligaments

Greater peritonealCavity

Greater Omentum

Liver

“Bare Area”

Diaphram

Triangular Ligament

Left SubphrenicSpace

Gastrophrenic ligament

Lesser SacStomach

Liver

Left Kidney

Pancr.

Greater Omentum

Colon

Greater peritonealCavity

Transverse Mesocolon

Gastrocolic Ligament

B. Lateral Aspect

CT Axial Series

Liver

Gallbladder Stomach

Esophagus

Diaphragm

Hep. flexure

Portal v.

IVC

D. aorta

GB

duodenum

Spleen

jejunum

2nd pt of Duodenum

Stomach

GB

Spleen

L. Gastric A.

Pancreas

Splenic flexure

Liver

Descending duodenum

R. Suprarenal gland

IVC

Portal v.

Splenic v.

jejunum

Splenic V

Splenic A

T. colon Stomach

Common Hepatic A.

Splenic A.

L. Gastric APortal v.

Celiac Trunk

L. Suprarenal gland

2nd part of duodenum

Pancreas

Superior mesenteric a.

IVC

L. Renal v.

Inf. Mes. V.

2nd part of duodenum

Pancreas

Right renal v.

Ureteropelvic Junction

Right Renal A.

L. Renal v.

L. Renal a.

Asc. colonDesc. colon

SMV SMA

Inferior mesenteric a.

Inferior mesenteric v.

Superior mesenteric a. + .v

Terminal ileum

Cecum

L. External oblique

L. Internal oblique

L. Transversus abdominusL. Rectus abdominus

L. Psoas m.

R. ureter

L. Quadratus lumborum m.

CT Coronal Series

Jejunal aa.

R. Colic a

jejunum

Splenic v.

SMA

Pancreas

R. Colic a.

Pancreas

Duodenal sweep

StomachLiver

Gallbladder

Asc. colon

D. colon

Splenic a.

L. hep. A.

R. hep. a.

Cystic a.

CT

SMA

IMA

Prop. Hepatic a.

Sup. Rectal a.

Sigmoidal aa.

ileocolic a.

Colic branch

Ileal branch

L. Gastric a.

Portal v.

Appendix

haustra

Tail of pancreas

Ileocolic v.

L. Renal a.

Splenic a.

Barium Studies

Barium Studies

• Utilize ionizing radiation to image the GI tract after the patient has swallowed contrast (often barium sulfate)

• Approach to interpretation largely utilizes the same principles as abdominal radiographs

97

Fundus

Body

Antrum

Pyloric sphincter

Pyloric canal

esophagusRugae

99

Pyloric canal

Pyloric sphincter

Superior part duodenum

Descending part duodenum

Inferior part duodenum

Ascending part duodenum

Jejeunum

Jejeunum

Ileum

Ascending colon

Hepatic flexure

Splenic flexureTransverse colon

Descending colon

Sigmoid colon

Cecum

Ileocecal junction

Haustra

ERCPEndoscopic Retrograde Cholangiopancreatography

ERCP• Technique involves concomitant endoscopy and fluoroscopy

• As such, it can be both diagnostic and therapeutic

• Allows physicians to inject contrast into the biliary tree and pancreas, identifying pathologies that may be present

Biliary Tree Anatomy Overview

Body of Gallbladder

Cystic duct

R. Hepatic duct L. Hepatic duct

Common Hepatic duct

Common Bile duct

Hepatopancreatic ampulla

Angiograms

Celiac Trunk Overview

Splenic a.Hepatic artery proper

Gastroduodenal a.

L. Gastric a.

Splenic a.

L. Gastric a.

Common hepatic a.

Gastroduodenal a.

R. Colic a.

Ileocolic a.

Colic br.

Cecal br.

SMA

112

Asc. br.

of L. colic a.

desc. br.

of L. colic a.

Sigmoid aa.

Superior rectal a.

L. Colic a.

IMA

113

L. Colic a.

IMA

Asc. br.

of L. colic a.

desc. br.

of L. colic a.

Sigmoid aa.

Superior rectal a.

END