Unit 6
Radiography of the Excretory System
RDSC 233
Bontrager pp. 539-574 & Patient Care in Radiography chap. 10.
Anatomy of the urinary system
Positioning of:
Radiographic anatomy
Iodinated Contrast Media
Tomography Review
The Intravenous urogram
(IVU) procedure
KUB scout
LPO & RPO Obliques
Cone down of kidneys
Post void upright
Film Critique
Exposure Factors
Atlas of Human Anatomy
Second edition (313)
Need to know
Fibrous capsule
Upper & lower pole
Medial & lateral borders
Renal artery and vein
Renal pelvis
Ureter
Ureteropelvic junction
(UPJ)
(infundibulum)
Atlas of Human Anatomy
Second edition (313)
& Bontrager (543)
Cortex *
Need to know
Renal pyramids (medulla) **
Renal papilla
Minor & major calyces (calices) s. calyx
* Glomerular and Bowman’s capsule, Glomerulus
** Loop of Henle, renal a & v, collecting tubule
Atlas of Human Anatomy
Second edition (343)
F
e
m
a
l
e
Need to know
Body, fundus, & neck of bladder.
Mucosal lining, submucosa, muscular
& serous layers
Ureteral orifice at uereterovesicle junction
Internal urethral orifice
Trigone of bladder
M
a
l
e
Urethra (female 4 cm)
Prostrate, prostatic urethra & urethra
(male 20 cm)
Bladder capacity: 250 cc urge to void
700 cc capacity
Atlas of Human Anatomy
Second edition (248)
Need to know
Relative position of
Kidneys to spine
Lt. Upper pole, T11-12 interspace
Rt. Lower pole, L3
Ureters (12”) & psoas muscles
Iliac crest and inferior poles
Lateral border is
posterior to medial border
Superior pole is posterior
to inferior pole
Superior pole is medial to
inferior pole
Radiographic Anatomy
Right Renal Arteriogram
Radiographic Anatomy
of the urinary system
Circulation of iodine contrast
before the nephron phase
(first appearance) of kidney in
an IVU
nephron
“blush”
renal a.
IVU Tomogram
minor calyces
catheter
cortex
Ureter
major calyx
renal pelvis
Ureteropelvic junction
(infundibulum)
15 minute KUB with full bladder
IVU Tomogram, late nephron
phase, collecting system
beginning to visualize
Upper pole
rt. kidney
medulla
Hilum *
Lateral
border
Lower pole
rt. kidney
Rt iliac
crest
cortex
* In middle of medial border,
superimposed on psoas m.
Anatomy
Review
Contrast Agents
January 1896 – First contrast injected into the vascular system of an
amputated hand.
1904 – First cystogram. Air (negative contrast) injected retrograde into
bladder.
1906 – First retrograde uretrogram using opaque contrast.
1923 – First excretory urography, called a “special procedure” due to the
risk associated with the toxic substances used.
1950s – Less toxic, Iodine preperations were introduced under the brand
names of Hypaque, Conray, and Renografin.
1986 – Nonionic iodine contrast agents were introduced.
127
Iodine 53
Iodine: atomic number 53.
Essential for nutrition, abundant in thyroid.
Principle ingredient in the surgical scrub, betadine
Non-metallic, commonly found in salt water swamps or brackish waters,
in grayish-black, lustrous plates or granules.
A halogen (group VII elements including fluorine, bromine, and chlorine),
iodine readily binds to salt.
Original “ionic” iodine contrasts were bound to sodium or meglumine
salt. When injected, the molecule begins to disassociate, releasing ionic
particles (+ cation and - anion) at a concentration 4 to 8 times higher
than the particle content of blood (Osmolality).
Characteristics of Ionic Contrast
Iodine concentration determines the radiopacity of the agent.
Measured in %weight/volume. Ranges from 10 to 82, dependent on its
use. Many products include the concentration of iodine salts in the
brand name: Renografin-60, Hexabrix 76, Isovue-200 (20%). See
appendix L in Patient Care in Radiography.
Water soluable. Unlike barium in suspension, iodine preparations must mix
with blood.
Stable in solution. The iodine molecule must remain in solution. Products
that do not meet this requirement are packages as a solute, and solvent.
Low viscosity. The thickness of an agent significantly affects the ease in
which a bolus is injected, and the rate of drip infusion.
Low toxicity. Any preparation not natural to the body is toxic to some degree,
as are natural substances given in excess. The goal of contrast media is to
keep adverse reactions to a minimum.
Low osmolality. The number of particles in solution is the chief factor of
toxicity.
The Osmotic Effect
1. As contrast
is injected
osmolality
increases
2. Blood entering the
capillary bed is
hypertonic to the
fluid in the surrounding
tissues.
6. Flexibility of vessels walls
allow vasodilation
to accomodate hypervolemia.
3. Extravascular fluid
crosses the semipermeable membrane of
the capillary to achieve
isotonicity, causing
hypervolemia
4. Fluid
drawn
from
RBCs,
causes
sickling.
5. Epithelial cells lining the intimal
wall are similarly effected, and can
lead to inflammation and
thrombophlebitis
Nonionic, low-osmolality contrast agents (LOACs)
Quickly became popular in the late 1980s
Nonionics do not disassociate into as many particles, and therefore
create fewer ions, and less osmolality. The cost is much greater, but
comes with the promise of fewer contrast reactions.
From Patient Care in Radiography,
5th edition. pg.269.
Precautions for the administration of all contrast agents
* Check the date on the bottle, ensure correct contrast is chosen
* Do not throw bottles away until after exam
Contraindications:
Glucophage – med for diabetes mellitus. When combined with
contrast increases the risk of renal failure. Recommended to
be withheld 48 hrs prior to and following contrast administration
Multiple myeloma - Malignancy of bone that leads to renal failure, and
increases the risk of contrast reactions.
Azotemia (uremia)- High levels of nitrogen waste in blood. Laboratory
tests BUN (blood urea nitrogen) should be 8 – 25 mg/100 ml. Another
test for nitrogen waste, Creatinine levels, should be .6 to 1.5 mg/dl.
Contraindications continued:
Hypersensitivity to iodine
Anuria – no excretion of urine
Severe renal disease or failure
Congestive heart disease (CHF)
Sickle cell anemia
Pheochromocytoma – tumor of the kidney
In certain cases, an IVU may be performed despite contraindications.
Patients should be well hydrated to lessen the risks.
Informed Consent
What to
watch for
Reactions can
develop quickly,
and patients
should not be
left alone.
From Patient Care in Radiography,
5th edition. pg.271.
Potential Contrast Reactions (and treatments for)
Though the incidence is lessened, reactions to nonionic contrast injections are
the same as for ionic agents. Most reactions occur within 5 minutes of injection.
Staying calm and reassuring is imperative to the patient’s well being.
Mild:
metallic taste
flushing (slow, deep breathing)
nausea
vomiting (emesis basin)
Moderate: urticaria (benadryl)
facial edema
transient hypotension
headache
dizziness
diaphoresis
chills (blanket warmer)
vasovagal (fear of needles)
swelling of parotids
transient bronchospasm
delayed skin reaction (keep patients 20 min)
tachycardia
Severe: prolonged hypotension/circulatory collapse (Adrenaline [epinephrine]
improves cardiac output and relaxes bronchial smooth muscles).
pulmonary edema
angina (nitroglycerine)
severe bronchospasm (adrenaline)
cardiac arrest (sodium bicarbonate)
arrhythmias (Inderal)
convulsions
coma
paralysis
death
Radiographic Positioning of the IVU
The IVU Procedure
Materials
Venipuncture
contrast (amount dependent on body weight, typically around 100cc)
syringes
butterfly needles (19 or 21 gauge)
venipuncture arm board
alcohol wipes
tourniquet
Reaction
supplies
emesis basin
towels
emergency drugs/crash cart
Filming
lead marker set
compression device
10” x 12” & 14” x 17” cassettes
gonadal shields
positioning sponges
The IVU Procedure
Because the time it takes for the kidney to excrete
the contrast is integral to the diagnosis of function,
the IVU exam is timed, and marked on every film.
A hypertensive IVU includes films (often tomograms) done at 1, 2, & 3
minutes, or even 30 second intervals. This study is done to determine
if hypertension is caused by the kidneys secreting excess renin.
Prior to injection a KUB (scout film) is taken to check for technique, the
position of the kidneys for the cone down views, the success of the bowel prep,
(which is similar to that of a barium enema), and to identify calcifications
that might otherwise be obscured by the contrast.
Routines are determined by department protocol, but a typical sequence is:
1 min. nephrogram, or nephrotomograms (cone down 10” x 12”)
5 min. supine KUB (or 10” x 12” cone down of kidneys)
10 and/or 15 min. supine KUB
20 min. LPO & RPO obliques
Upright postvoid
The IVU Procedure
The good news is...
The scout film is exactly the same as a plain film KUB:
The obliques are like colon obliques, except 300, and
they include the pubic symphysis (bladder) like a KUB.
The upright postvoid is like the upright abdomen, except
it is centered like a KUB to also include the bladder.
The only unique film is the 10” x 12” cone down of the
kidneys for the nephrogram, or more commonly, the
tomograms.
Routine IVU Positioning
Preparation
1. Evaluate the order
2. Greet the patient
3. Take History
4. Have patient void
What is pertinent Hx?
urinary tract infection, mass, oliguria,
renovascular hypertension, renal
calculi, elevated creatinine or BUN,
hematuria, bladder CA, prostate
enlargement, trauma to kidneys,
polycystic kidney, malrotation,
ectopic kidney
5. Remove jewelry, check attire, snaps, pins, NG tubes, etc.
6. Explain the exam in layman’s terms
7. Questions?
8. Set technique before positioning
Centering the Kidneys on a 10” x 12”
Sponge, big
help for IVUs
CR midway between xiphoid tip
and iliac crest.
Note proximity of the lower pole of
the rt. kidney to the iliac crest.
Sometimes it is a couple of inches
above it, and sometimes it is even
lower
Lt. Upper pole, T11-12 interspace
Lt. Lower pole, L3
(crest is L4-L5 interspace)
Note pyloric bulb
fulcrum – Physical pivot point
objective (focal) plane – plane in space
that corresponds to the fulcrum, where
the x-ray pivots
Linear tomography is routinely
used in IVUs. Cut thickness is
typically 1 cm. Three levels are
required to demonstrate the
entire kidney in focus.
cut level – distance from the image receptor
to the objective plane
exposure angle (arc) – The distance the tube
travels, measured in degrees.
section (cut) thickness – the thickness of the
anatomy being imaged that is in the focal
plane, and thus in focus.
amplitude – the distance the tube travels during
its excursion through the exposure angle.
Does not effect the cut thickness, only the
exposure time.
Linear
Tomography
Finish
Vertical
Start
Start
Vertical
Finish
Localizing the Kidneys (level) for Tomography
Divide the measurement
of abdomen at the level of
the kidneys by three. Start
at that cut level and work up.
For example, a 27 cm patient
would have “tomos” at 9, 10,
and 11 cm.
11 cm
10 cm
9 cm
Critique criteria for tomographic series
1. The upper and lower poles of both kidneys must be included.
2. Between the three tomographic levels, each kidney should
be in focus, in its entirety
11 cm
10 cm
9 cm
11 cm
10 cm
9 cm
11 cm
10 cm
9 cm
Perfect
Lower pole not in focal plane
(started to low)
Upper pole not in focal plane
(started too high)
Focus is
approximately
here
Various focal planes in different patients: Even more evident than the focus of
the kidney, is the appearance of the vertebra. These are arranged posterior (1)
to anterior (4).
1
2
3
4
LPO and RPO obliques
300 obliques are done
to lay the kidney of interest
out in profile.
In an AP projection the hilum is
angled anteriorly.
An LPO position best demonstrates
the internal collecting system of the
rt kidney
LPO position
Note that the spine is further from
the left ureter than the right ureter
Right
Right
Left
Left
LPO and RPO obliques
An RPO is seen here.
Note the appearance of the ala of the ilium,
and the lt. SI joint.
The left kidney is seen in a PA view, but
its ureter may be obscured by the spine.
The right kidney is obliqued 600 to the film,
but its ureter will be free of the spine, and
if filled with contrast, well demonstrated.
The compression technique (not routine)
If the internal collecting system
empties too rapidly to be well
visualized, the radiologist may
request ureteral compression
to obstruct the flow of
contrast to the bladder.
Compression is applied by
wrapping a band around the
abdomen, securing a set of
inflatable balloons over the
ureters, and applying enough
pressure to create an artificial
hydronephrosis.
Ureter
Balloons
The compression technique:
Equipment
Retention band: wrapped around
abdomen, secures the plate and sponge
over the balloons.
Rigid plate (plexiglass)
to apply equalized
pressure on sponge
Sponge, placed over
the balloons
Inflation ballons, placed
on the abdomen, centered
on the ureters.
Y
Inflation
bulb
The compression technique
There are usually two balloons, though
some models have one that is the size
of two. With either model the top of
the balloons are placed at the level of
the iliac crest, and close to touching at
the midline.
Bontrager
p. 371.
Contraindications to compression
include recent surgery, known
abdominal mass, renal calculi, and
aortic aneurysm. A 15% trendelenburg
is used instead.
The compression technique
The top of the balloons are placed at the iliac crest, close to touching
at midline. The sponge is positioned over the balloons and the
plexiglass plate is centered over the sponge. The compression
band secures all the parts and is fastened with velcro. The balloons
are blown up to compress the ureters.
Post void or upright post void
The postvoid is typically done as the
last film of a routine. It is a standard
KUB. It is most often done supine,
but may be prone.
In addition to the residual contrast
that the recumbant film demonstrates,
the upright position shows the change
in position of the bladder and kidneys,
organs that are most susceptable to
ptosis
In addition to these routine views
cone down views of the bladder
and obliques may be requested.
They will be covered in the unit
on cystography.
Exposure Factors
Techniques for an IVU are the same as for plain films of the
abdomen except it is especially important to keep the kVp
low to enhance the k-shell characteristic of iodine as much
as possible. 70-75 kVp is recommended.
Probability of Absorbtion
K Shell Binding Energy of 33 keV
Iodine
34 keV
32 keV
33 keV
Bone
Muscle
keV
The End
30.
31.
32.
33.
34.
35.
36. Name one consequence of the osmotic effect (1 EC)
37. Name a second consequence of the osmotic effect (1EC)
30. Cortex
31. Renal pyramids (medulla)
32. Minor calyces (calices)
33. Upper pole
rt. kidney
34. Hilum
35. Lateral
border
36. Name one consequence of the osmotic effect (1 EC)
37. Name a second consequence of the osmotic effect (1EC)
The Osmotic Effect
1. As contrast
is injected
osmolality
increases
2. Blood entering the
capillary bed is
hypertonic to the
fluid in the surrounding
tissues.
6. Flexibility of vessels walls
allow vasodilation
to accomodate hypervolemia.
3. Extravascular fluid
crosses the semipermeable membrane of
the capillary to achieve
isotonicity, causing
hypervolemia
4. Fluid
drawn
from
RBCs,
causes
sickling.
5. Epithelial cells lining the intimal
wall are similarly effected, and can
lead to inflammation and
thrombophlebitis