MRI Abdomen

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Upper Abdominal Organs

The liver is normally positioned and has normal size and smooth borders. Its internal structure is normal, with no focal abnormalities of signal intensity. The intrahepatic and extrahepatic bile ducts are not distended. The porta hepatis appears normal.

The gallbladder displays a normal size, smooth borders, and homogeneous contents.

The spleen is orthotopic and of normal size. It has smooth outer contours and a homogeneous internal structure.

The pancreas is normal in size and position. The head, body, and tail of the organ have smooth, lobulated outer contours and normal internal structure. The pancreatic duct is unobstructed.

Both kidneys are normal in size and position. The renal parenchyma shows normal width and structure.

The renal pelvis and calices are normal. The urinary drainage tract is unobstructed.

Both adrenal glands are normal in position and size, and the adrenal crura are normally developed. The adrenal compartment is unremarkable.

Major vessels and the para-aortic region appear normal, with no evidence of lymphadenopathy.

Imaged portions of the lung and soft tissues show no abnormalities. Interpretation

The upper abdominal organs appear normal.

Checklist

Position

— Directly below the right hemidiaphragm Size (see below)

Borders:

No focal abnormalities Intrahepatic bile ducts:

— Course (toward porta hepatis)

Extrahepatic bile ducts:

— Course (from porta hepatis to head of pancreas)

— Homogeneous contents of fluid-equivalent signal intensity

— Wall thickness (see below)

— No pericholecystic fluid Gallbladder contents:

— Homogeneous

— Fluid-equivalent signal intensity

— No calculi (hypointense or hyperintense)

Porta hepatis occupied by the hepatic artery, common bile duct, and portal vein No masses

No lymphadenopathy Size (see below) Smooth outer contours Homogeneous internal structure Size normal for age (see below) Normal lobulation Smooth outer contours

• Pancreatic duct unobstructed (see below)

• No peripancreatic fluid

Kidneys

• Paired

• Position (see below)

• Size (see below)

• Smooth contours

• Width of cortex and medulla

• Renal pelvis (presence, symmetry, size, no

widening, homogeneous fluid contents)

• Calices (shape, width, homogeneous contents)

• Enhancement characteristics (see below)

Ureters

• Not duplicated

• Course

• No obstruction of urinary drainage

Adrenal glands

• Shape

• Size (see below)

• Slender crura (no asymmetric widening)

• No circumscribed hypointense (T1: cyst, ade-

noma), isointense, or hyperintense expansion

Intestinal

• Colon haustrations

structures

• Small bowel

• Wall thickness

• Homogeneous opacification with oral contrast

medium (if administered)

• No free extraintestinal or intra-abdominal air or

fluid

• Para-aortic region:

— Major vessels (position, size, fluid signal)

— Soft tissues (no masses)

— No lymphadenopathy

Lungs

• Clear and expanded

Costophrenic

• Clear and aerated on both sides

sinus

Soft tissues

Important Data

Dimensions

1

Liver:

a Left lobe (anteroposterior diameter on the left paravertebral

line): up to 5 cm

b Caudate lobe/right lobe (CL/RL) = 0.37 ± 0.16 (e.g., 0.88 ± 0.2

in cirrhosis). Reference lines [from medial side]: line I is tan

gent to the medial border of the caudate lobe; line II is paral

lel to I and tangent to the lateral aspect of the portal vein;

line III is tangent to the lateral hepatic border and perpen-

dicular to a line midway between the portal vein and infe

rior vena cava and perpendicular to I and II.

c Angle of hepatic border: ca. 45° on the left side (formed by

left lateral and inferior hepatic borders)

2

Gallbladder:

a Horizontal diameter up to 5 cm (> 5 cm is suspicious for hy-

drops)

b Width of gallbladder wall: 1-3 mm

3

Width of common bile duct:

• < 8 mm (< 10 mm after cholecystectomy)

4

Spleen:

a Depth: 4-6 cm

b Width: 7-10 cm

c Length: 11-15 cm

Splenic index: D x Wx L = 160-440

III II I

III II I

Axial image

5

Pancreas:

a Head: up to 3.5 cm

b Body: up to 2.5 cm

c Tail: up to 2.5 cm

Pancreatic duct: width 1-3 mm

s

Adrenal glands (variable):

• Crural thickness <10 mm

7

Kidneys:

a Craniocaudal diameter: 8-13 cm

b Anteroposterior diameter: ca. 4 cm

c Transverse diameter 5-6 cm

Position of superior poles of kidneys:

d Right: superior border of L1

d Left: inferior border of T12

f Transverse renal axis: posteriorly divergent angle of 120°

g Width of renal cortex: 4-5 mm

Time to corticomedullary equilibrium: 1 minute

Contrast excretion into the pyelocaliceal system: 3 minutes

Gerota fascia (thickness): 1 -2 mm

Width of ureter: 4-7 mm

S

Diameter of abdominal aorta:

• Approximately 18-30 mm

9

Inferior vena cava:

• Transverse diameter up to 2.5 cm

Lymph nodes larger than 1 cm are suspicious for pathology.

Axial image
Coronal image

Liver

The liver is orthotopic and presents normal size and smooth borders. It has a normal internal structure with no focal abnormalities. The intra-hepatic and extrahepatic bile ducts are not dilated. The gallbladder appears normal, displaying smooth borders and homogeneous contents.

The porta hepatis shows no abnormalities.

Other visualized upper abdominal organs are unremarkable.

Interpretation

The liver appears normal.

Checklist

Liver • Position

— Directly below the right hemidiaphragm

• No focal abnormalities

• Intrahepatic bile ducts:

— Course (toward porta hepatis)

• Extrahepatic bile ducts:

— Course (from porta hepatis to head of pancreas)

— Homogeneous contents of fluid-equivalent signal intensity

Intestinal •

structures •

Gallbladder:

— Contours (smooth and sharp)

— Wall thickness (see below, no general or circumscribed thickening)

— No pericholecystic fluid Gallbladder contents:

— Homogeneous

— Fluid-equivalent signal intensity

— No filling defects (calculi, polyps)

— Occupied by the hepatic artery, common bile duct, and portal vein

— No lymphadenopathy

Costophrenic sinus is clear and aerated on each side

Normal size (see below)

Homogeneous internal structure

Normal size (see below)

Pancreatic duct unobstructed (see below)

Unremarkable

Position

Size

Internal structure Normal

No free extraintestinal or intra-abdominal air or fluid

Important Data

Dimensions:

1 Liver:

a Left lobe (anteroposterior diameter on the left paravertebral line): up to 5 cm b Right lobe (craniocaudal diameter measured on the midclavicular line): up to ca. 15 cm Angle of hepatic border:

c Right side: ca. 75° (inferior border, sagittal plane) d Left side: ca. 45° (left lateral and inferior borders) e Caudate lobe/right lobe (CL/RL) = 0.37 ± 0.16 (e.g., 0.88 ± 0.2 in cirrhosis). Reference lines [from medial side]: line I is tangent to the medial border of the caudate lobe; line II is parallel to I and tangent to the lateral aspect of the portal vein; line III is tangent to the lateral hepatic border and perpendicular to a line midway between the portal vein and inferior vena cava and perpendicular to I and II.

2 Gallbladder:

a Horizontal diameter up to 5 cm (> 5 cm is suspicious for hy-drops)

b Width of gallbladder wall: 1-3 mm

3 Width of common bile duct:

T1-weighted noncontrast axial image

III II I

III II I

T2-weighted noncontrast axial image

T1-weighted axial image after the i. v. administration of a superparamagnetic contrast agent

T2-weighted axial image after the i. v. administration of a superparamagnetic contrast agent

4 Portal vein:

5 Hepatic veins:

• Splenic index: DxWxL = between 160 and 440 Adrenal glands (variable):

• Crural thickness <10 mm Kidneys:

• Craniocaudal diameter: 8-13 cm

• Anteroposterior diameter: ca. 4 cm

• Transverse diameter: 5-6 cm Position of superior poles of kidneys:

• Right: superior border of L1; left: inferior border ofT12 Transverse renal axis:

• Posteriorly divergent angle of 120°

Sagittal image at the level of the mid- Sagittal image through the left lobe of clavicular line the liver

Sagittal image at the level of the mid- Sagittal image through the left lobe of clavicular line the liver

Width of renal cortex:

Diameter of abdominal aorta:

• Approximately 18-30 mm Inferior vena cava:

• Transverse diameter: up to 2.5 cm

Lymph nodes larger than 1 cm are suspicious for pathology.

Coronal image

Kidneys

Both kidneys appear normal in size and position, and the renal parenchyma displays normal width. There is no evidence of a mass. The calices are of normal shape, and the renal pelvis appears normal. The urinary drainage tract is unobstructed.

Postcontrast images show a normal time to corticomedullary equilibrium and undelayed, symmetrical contrast excretion into the renal pelves.

Other visualized upper abdominal organs, especially the adrenal glands, show no abnormalities.

Interpretation

Both kidneys appear normal.

Checklist

Kidneys • Paired

Size (see below) Contours:

Parenchymal width and signal (see below) Normal relation of cortex to medulla Renal pelves:

— Bilateral symmetry

— Shape of calices Ureters:

— No obstruction of urinary drainage Perirenal and pararenal spaces:

Perirenal and pararenal fasciae:

— Width (no circumscribed thickening)

Kidneys 141

Adrenal glands

Shape

Size (see below)

Slender crura

No circumscribed expansion

Retroperitoneal

No abnormalities (mass, fluid)

space

Intestinal struc-

Normal

tures (colon

Wall thickness

haustrations,

No free extraintestinal or intra-abdominal air or

small bowel)

fluid

Major vessels

Course

Caliber (see below)

No lymphadenopathy (see below)

Soft tissues

Fat signal

Bilateral symmetry

T1-weighted coronal image using breath-hold technique, early bolus phase

Important Data

1

Position of superior poles of kidneys:

a Right: superior border of L1

b Left: inferior border of T12 (variable; right kidney is lower

than left kidney by up to one vertebral body height)

2

Distance between superior renal poles:

• Approximately 10 cm (4-16 cm)

3

Distance between inferior renal poles:

• Approx. 13 cm (9-18.5 cm)

4

Transverse renal axis:

• Posteriorly divergent angle of 120°

5

Renal dimensions:

• Craniocaudal 8-13 cm (<1.5 cm craniocaudal difference in

renal sizes)

Transverse renal diameter at level of hilum: 5-6 cm (b =

transverse) x 3-4 cm (c = anteroposterior)

6

Renal cortical thickness:

• 4-5 mm

7

Time to corticomedullary equilibrium:

• 1 minute

8

Contrast excretion into the pyelocaliceal system:

• 3 minutes

9

Width of ureter:

• 4-7 mm

10

Gerota fascia (thickness):

• 1-2 mm

11

Abdominal aorta:

• Transverse diameter ca. 18-30 mm

12

Inferior vena cava:

• Transverse diameter up to 2.5 cm

Lymph nodes larger than 1 cm are suspicious for pathology.

T1-weighted axial image without contrast medium
T1-weighted axial image after contrast administration
T1-weighted axial image after contrast administration
T1-weighted noncontrast axial image at the level of the ureters

Adrenal Glands

Both adrenal glands present normal size and position with normally developed crura. There is no evidence of a mass or circumscribed expansion.

The adrenal compartment appears normal.

Postcontrast images show normal adrenal enhancement characteristics and dynamics.

No abnormalities are found in other visualized upper abdominal organs, especially the kidneys.

Interpretation

Both adrenal glands appear normal.

Checklist

Adrenal glands • Paired

• Position (superior and anterior to kidneys)

• Signal characteristics of normal adrenals (T1: slightly hypointense to liver; T1 fat-saturated: isointense; T2: hypointense; T2 fat-saturated: hyperintense)

• No circumscribed hypointense, isointense or hy-perintense expansion of adrenal crura (e.g., T2-weighted signal is increased in many pheochro-mocytomas) or circumscribed hypointense or hyperintense lesions (e.g., calcifications, fat deposits)

• Enhancement characteristics:

— Adenomas show moderate signal increase that usually returns to initial level by 10 minutes postinjection

— Most malignant tumors still show intense enhancement after 15 minuntes

• Chemical shift imaging:

— In-phase and out-of-phase T1-weighted images show fat intensity (decreased signal) in benign disease

• Adrenal compartment:

— Fat intensity

• Homogeneous internal parenchymal structure

• Intrahepatic and extrahepatic bile ducts

• Costophrenic sinus is clear and aerated on each side

• Smooth outer contours

• Homogeneous internal structure

• Pancreatic duct

• Smooth contours Stomach and • Position bowel • Size

• No infiltration

Major blood • Transverse diameter (see below)

Lymph nodes • No lymphadenopathy

Soft tissues

Important Data Dimensions:

1 Adrenal glands (variable):

• Crural thickness <10 mm Kidneys:

Position of superior poles of kidneys:

• Right: superior border of L1

• Left: inferior border of T12 Transverse renal axis:

• Posteriorly divergent angle of 120°

Liver

Spleen

Pancreas Kidneys

Thickness of renal cortex:

• Craniocaudal diameter: 8-13 cm

• Anteroposterior diameter: ca. 4 cm

• Transverse diameter: 5-6 cm Gerota fascia (thickness):

• Length: 11-15 cm Diameter of abdominal aorta:

• Approximately 18-30 mm

T2-weighted axial image through the adrenal glands
T1-weighted axial image, noncontrast and in-phase
T1-weighted axial image, noncontrast and out-of-phase
T1-weighted axial image, postcontrast and out-of-phase

Female Pelvis

The pelvic inlet appears normal, with normal configuration of the iliac wings and iliopsoas muscles.

No abnormalities are found in imaged bowel structures, and there are no signs of wall thickening or mass lesions.

The uterus is anteverted and has normal internal structure. The adnexa appear normal on both sides.

The adequately distended urinary bladder appears normal and has a normal wall thickness.

The vessels of the lesser pelvis are normal in course and caliber. There is no apparent lymphadenopathy.

The femoral heads are normally shaped and articulate normally with the acetabula. They have normal bone-marrow signal characteristics. The soft tissues show no abnormalities.

Interpretation

The lesser pelvis appears normal.

Checklist Pelvic inlet

Iliopsoas muscles

Intestinal structures (especially the cecum and rectum)

Perirectal fat

Ischiorectal fossa

Uterus

Configuration

Width

Symmetry

Iliac wings (shape)

Size

Signal characteristics

Symmetry

Position

Wall thickness (if with normal distension, see below)

No circumscribed wall thickening

Well-opacified lumen with no soft-tissue mass

Signal characteristics (fat intensity)

No infiltration

No masses

Bilateral symmetry

No masses

No lymphadenopathy Position

Size (see below)

Borders (smooth outer contours)

Cervix, vagina

Ovaries

Urinary bladder

Vessels

Lymph node stations Pelvic skeleton

Subcutaneous tissue and muscles

Signal characteristics Uterine cavity:

— Configuration

— Signal characteristics Position

Size

Borders

Position

Size (see below) Signal characteristics Symmetry

No masses of soft-tissue or fluid signal intensity Adequate distention Outer contours:

— Wall thickness (see below) Caliber (see below)

Course

No significant intimal calcifications No lymphadenopathy

Configuration

Margins (cortex smooth and sharp, no discontinuities)

Fat-equivalent signal intensity of bone marrow No circumscribed areas of marrow replacement Femoral heads rounded and centered in acetabula Sacroiliac joints:

— Smooth contours

— Normal width (see below) Symphysis pubis (see below) Signal characteristics Extent

Borders Symmetry

Important Data

Pelvic dimensions:

1 True conjugate:

• Approximately 11 cm

2 Pelvic cavity:

3 Pelvic outlet:

• Approximately 9 cm

4 Transverse diameter (transverse interspinous distance):

• Approximately 13 cm

5 Uterus (variable):

• Prepubescent: a, length up to 3 cm; b, transverse diameter ca. 1 cm

• Nullipara: a, length up to 8 cm; b, transverse diameter ca. 4 cm

• Multipara: a, length up to 9.5 cm; b, transverse diameter ca. 5.5 cm

Postmenopausal: a, length up to 6 cm; b, transverse diameter ca. 2 cm

(Transverse diameter of upright uterus = well distended bladder < 5 cm)

6 Uterine cervix:

a Craniocaudal < 2 cm b Transverse diameter < 3 cm

Paracoronal image along the true conjugate (line 1 in Fig. on left [= midsagittal section through the lower abdomen]).

Coronal image

7

Ovaries:

• Prepubescent: a, length up to 2.5 cm; b, transverse diame-

ter ca. 2.5 cm

• Sexual maturity: a, length up to 4 cm; b, transverse diame-

ter ca. 2.5 cm

• Postmenopausal: a, length up to 3 cm; b, transverse

diameter ca. 1.5 cm

8

Urinary bladder (well distended):

• Wall thickness ca. 3 cm

9

Rectum:

• Wall thickness < 5 mm

10

Symphysis pubis:

• Width < 6 mm

11

Cartilage thickness of sacroiliac joint spaces:

• 2-5 mm (anterior and inferior: 2-3 mm)

Male Pelvis

The pelvic inlet appears normal, with normal configuration of the iliac wings and iliopsoas muscles.

No abnormalities are found in imaged bowel structures, and there are no signs of wall thickening or mass lesions.

The distended urinary bladder appears normal and has normal wall thickness. The seminal vesicles are of normal size. The angle between the bladder and seminal vesicle is normal on each side. The prostate shows a normal size and configuration.

The vessels of the lesser pelvis are normal in their course and caliber. There is no evidence of lymphadenopathy.

The femoral heads are normally shaped and articulate normally with the acetabula. They have normal bone-marrow signal characteristics. The soft tissues show no abnormalities.

Interpretation

The lesser pelvis appears normal.

Checklist

Pelvic inlet

Intestinal structures (especially the cecum and rectum)

Perirectal fat

Ischiorectal fossa

Seminal vesicles

Configuration Width Symmetry Iliac wings (shape) Iliopsoas muscles:

— Signal characteristics

— Symmetry Borders Position

Wall thickness (if with normal distension, see below)

No circumscribed wall thickening

Well-opacified lumen with no soft-tissue mass

Signal characteristics (fat intensity)

No infiltration

No masses

Bilateral symmetry

No masses

No lymphadenopathy Position (behind the bladder) Size (see below)

Symmetry

Angle between the bladder and seminal vesicle

(see below) is clear on each side

Signal characteristics

Prostate

Position (central at bladder outlet)

Configuration (rounded shape, intact capsule

and lobulation)

Size (see below)

Homogeneous signal intensity

No calcifications

No unilateral nonhomogeneity after contrast ad-

ministration

Urinary bladder

Adequate distension

Smooth outer contours

Wall thickness (see below)

Vessels

Caliber (see below)

Course

Lymph node

No lymphadenopathy

stations

Pelvic skeleton

Configuration

Margins (cortex smooth and sharp, no discon-

tinuities)

Fat-equivalent signal intensity of bone marrow

No circumscribed areas of marrow replacement

Femoral heads rounded and centered in

acetabula

Sacroiliac joints:

— Smooth contours

— Width (see below)

Symphysis pubis

Subcutaneous

Density

tissue and

Extent

muscles

Borders

Symmetry

Important Data

1 Prostate (size varies with age, 20-70 years):

a Anteroposterior diameter ca. 2.5-3 cm b Lateral diameter: 3-5 cm c Craniocaudal diameter: 3-5 cm

Axial image
Axial image
Axial image

3

Rectum:

• Wall thickness < 5 mm

4

Urinary bladder (well distended):

• Wall thickness ca. 3 mm

5

Seminal vesicles (highly variable):

a Length: up to 5 cm

b Width: up to 2 cm

6

Angle between bladder and seminal vesicles:

• Open = normal

7

Width of sacroiliac joint spaces:

• 2-5 mm (anterior and inferior: 2-3 mm)

Testes

The scrotum and its contents display normal configuration. The testes are symmetrical and of normal size with a homogeneous internal structure. Each testis is sharply demarcated by the tunica albuginea, which is of normal thickness.

The epididymis shows a normal size and position on each side and presents a normal internal structure.

The scrotal compartments appear normal on each side, with no sign of increased fluid.

The inguinal canal is normal in its shape, size, and course. The corpora cavernosa and corpus spongiosum are normal.

Interpretation

The testes appear normal.

Checklist Scrotum

Testes

Tunica albuginea

Epididymis (head and tail)

Inguinal canal

Corpora cavernosa

Corpus spongiosum

Size

Configuration Paired

Symmetrical Size (see below)

Homogeneous internal structure (high T2-weighted signal intensity) No circumscribed or diffuse change in signal intensity

Smooth, sharp borders on all sides

Normal thickness

Position

Size (bilateral symmetry) Internal structure

Scrotal compartments have smooth, sharp borders

No increased fluid

Shape

Size

Course

Size

Bilateral symmetry Honeycomb internal structure Size Urethra

Important Data

Testicular dimensions:

1 Length:

2 Transverse diameter:

T2-weighted coronal image
T1-weighted axial image

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