White Blood Cell Scan

Question 1

RP

Dose

Answer 1

In111 oxide: 500 μCi

Tc99m HMPAO: 10-24 mCi

Question 2

Indications

Answer 2

Detect and localize acute or chronic osteomyelitis
Detect and localize acute abscesses
Detect and localize infection/ inflammation - FUO
Rule out loosening vs infection of prosthesis
Localize source of sepsis

Question 3

Contraindications

Answer 3

Antibiotics – decrease leukocyte chemotaxis

Leukopenic patient

Question 4

Patient Prep

Answer 4

Document name, date and time for procedure to begin
Void
Remove attenuating objects from pockets

Question 5

Positioning

Answer 5

Supine with arms at their side

Question 6

Target Organ
Critical Organ
Method of Localization
Route or Excretion

Answer 6

Target Organ – Infection
Critical Organ – Liver/ Spleen
Method of Localization – Chemotaxis
Route of Excretion – Bowel

Question 7

Procedure

Answer 7

In111 – Oxine 
Image at 24 hrs post re-injection
Whole Body/ Spots at areas of interest 
Tc99m – HMPAO 
Image at 1-4 hours post
Whole body/ Spots at areas of interest (10 min/image)
18-24 hour delayed images possible for chronic infection
Gut activity at 4 hrs
SPECT possible

Question 8

Computer Set Up

Answer 8

MEGP collimator for In111
LEAP or LEHR for Tc99m
Tumor/Infection - WBC
Whole body
512x1024
10cm/min
Spots
In111 – 500k counts or 10-20 min
Tc99m – 800k – 2M counts or 5-10 min
512x512 for CAP
256x256 for extremities
SPECT
360° elliptical, 64 stops 45-60 sec/ stop

Question 9

Normal

Answer 9

In111
20-50% of dose in kidneys, bone marrow, liver, spleen
up to 4 hrs: pulmonary uptake
18-24 hrs: liver, spleen and bone marrow
NO: renal, bladder or GI activity
Tc99m
Initial uptake in lungs, liver, spleen and major vessels
1-2 hrs: liver, spleen, GB and bladder
4 hrs: bowel – reduced lung activity
24 hrs: colon

Question 10

Abnormal

Answer 10

Focal hot spots
Cold spots – osteomyelitis, compression fracture, neoplasm
Lung activity after 4 hours indicates: Pulmonary edema, Diffuse inflammatory lung disease, Atelectasis, Renal failure, Sepsis

Question 11

Notes

Answer 11

In111 - lipophilic and easily gets into cell membrane- stable and better tagging, longer half life (SPECT not as good) No bowel for delayed images. better for injection/inflammation imaging. Good for shunts and graft infections
Tc99m - Imaging at 24 hours is not as clear as In111 (SPECT better with Tc99m). Better for osteomyelitis and exterminates. Less liver spleen. Larger dose, better for Peds