12. Imaging of the pelvis - angiogram, ultrasound, MRI

Question 1

Which imaging modalities are used in imaging the pelvis?

Answer 1

MRI
U/S

CT of limited use:
Poor soft tissue contrast
Artefact from pelvic girdle

Question 2

Advantages of MRI

Answer 2

Advantages of MRI:
No ionising radiation
Better soft tissue contrast
BUT
Longer examination times
More expensive

Question 3

The male pelvis

Answer 3

Below bladder:
Prostate
Rectum
Ischio-rectal fossae
Obturator internus – lateral rotation and abduction of hip

Further up, at level of hip joints:
Bladder
Seminal vesicles

Question 4

Female pelvis

Answer 4

Uterus
- Endometrium
- Myometrium
- Junctional zone
Ovary –fluid bright (on T2 image)
Bladder
cervix

Question 5

Sagittal MRI

Answer 5

Bladder
Uterus
Cervix
rectum

Question 6

What is a hysterosalpingogram

Answer 6

HSG - hysterosalpingogram. Like smear test, get scapula into vagina then stick a cannula in with contrast into cervix

Question 7

The perineum (sagittal MRI)

Answer 7

Bladder / Urethra
Vagina
Rectum

NB: peritoneal reflections in the pelvis.
Female 
 vesico-uterine pouch
Recto-uterine pouch (pouch of Douglas)
Male
Vesico-rectal pouch

Question 8

Pelvic ultrasound

Answer 8

Advantages of U/S:
Fast & cheap
No ionising radiation
Non –invasive (?but transvaginal (TV))
BUT
Operator dependant
Bone / bowel gas may obscure image

Question 9

Transabdominal vs transvaginal ultrasounds bladder state

Answer 9

Transabdominal scan always done with a full bladder because urine is good for transmitting US

With transvaginal ultrasound, need to empty the bladder first so that bladder doesn’t press on the uterus etc

Question 10

Ante-natal ultrasound

Answer 10

Congenital anomalies
Growth rate
Calculating EDD

Question 11

Foetal measurements

Answer 11

They can include the crown rump length (CRL), biparietal diameter (BPD), femur length (FL)

head circumference (HC), occipitofrontal diameter (OFD), abdominal circumference (AC), and humerus length (HL), as well as calculation of the estimated fetal weight (EFW).

Question 12

How do we image the vascular anatomy of the pelvis

Answer 12

How do we image vascular system:
MRI / MRA
Duplex U/S
CT angio
Angiography (direct cather angio)

Question 13

Duplex U/S

Answer 13

Measure highest velocity in artery
Can assess flow, stenosis, aneurysm, plaque
Look for turbulent flow (bruits) and post-stenotic dilatation

Question 14

Catheter angiogram

Answer 14

Invasive femoral artery access, catheter into aorta or steered into selective artery.
Seldinger technique: needle puncture, insert guidewire, remove needle, advance catheter or sheath over wire.

Question 15

Arteries seen in pelvic angiogram

Answer 15

Aorta
Common iliac artery
Internal iliac artery
External iliac artery

Question 16

At what level does the aorta bifurcate?

Answer 16

L4

Question 17

Where does the vena cava divide?

Answer 17

L5

Question 18

The aorta and vena cava

Answer 18

Aorta divides at L4
The vena cava divides at L5
The RIGHT CIA crosses the origin of LEFT CIV

Question 19

May-Thurner syndrome

Answer 19

Form of left iliac vein DVT

Right CIA crossing origin of left CIV squashes the CIV causing DVT

Question 20

Internal and external iliac arteries

Answer 20

The external iliac artery passes anterior to the internal iliac artery and they both pass laterally

Question 21

Divisions of internal iliac artery anatomy

Answer 21

Anterior and posterior divisions:

Posterior division is Iliolumbar, lumbosacral and superior gluteal, everything else is anterior