3: Clinical Nuclear Medicine – Whole-Body Scans

and Bruce J. Barron2



(1)
Loyola University Medical Center, Maywood, Illinois, USA

(2)
School of Medicine, Emory University, Atlanta, USA

 





1 Infections and Inflammations



1.1 Gallium-67 Citrate Scan



Indications




  1. 1.


    Lymphoma (HD > NHL).

     

  2. 2.


    Solid tumors (lung, melanoma, HCC (hepatoma), sarcoma, testicular tumor, head and neck cancers, neuroblastoma.

     

  3. 3.


    Infections and inflammations (vertebral osteomyelitis – better than In-111 WBC), fever of unknown origin (FUO), fungal infections, granulomatous diseases, and sarcoidosis.

     


Ga-67 Citrate

t phys 78 h. Cyclotron produced, decays by electron capture (EC). Emits gamma radiation 93 (37 %), 185 (20 %), 300 (17 %), and 395 (5 %). Known as “90, 190, 290, and 390.”


Mechanisms of Action

Iron analog. Will not cross the BBB (blood brain barrier).

Infections: Ga-67 binding affinity – lactoferrin > > siderophores > transferrin. Leukocytes will secrete lactoferrin (lactoferrin mechanism), and bacteria will secrete siderophores. Ga-67 – bound to transferrin → transported via blood stream to infection site → attached to lactoferrin >> > and siderophores.

Solid tumors: Transmembrane transferrin receptor (CD71) on tumor cells via endocytosis (transferrin mechanism), then attached to lysosomal proteins.

Lymphomas: Transferrin and lactoferrin mechanism.


Protocol

Bowel prep. optional → IV injection → 48–72 h, whole body scan + SPECT/CT of the chest/abdomen at 48 or 72 h. Can wait up to 7–10 days to image (e.g., differentiate intra-abdominal infection from normal bowel clearance).


Dose

Infection (5 mCi), tumor imaging (10 mCi).


Imaging

Collimator – medium energy parallel, 20 % windows at 93, 185, and 300 KeV or 20 % windows at 93 and 185 KeV. Whole-body planar anterior posterior images followed by SPECT/CT of region of interest (chest/abdomen and pelvis).


Critical Organ

Colon.


Distribution

Blood pool (plasma protein bound %) – 24 h, 20 %; 48 h, 10 %; and 72 h, 5 %.

Infection site/tumor uptake at 12–24 h.

Liver > bone marrow >> > colon (variable uptake), lacrimal gland, nasopharyngeal, breasts (cycle variant), testes, lung, thymus (peds), spleen, kidneys.


Clearance

First 24 h – 25 % clearance by kidneys. > 24 h – bowel> > kidneys (kidney uptake is abnormal at 48 h).


Variations




  1. A.


    Chemotherapy decreases liver activity significantly.

     

  2. B.


    Scrotal uptake may be normal.

     

  3. C.


    Imaging quality: Poor due to “downscatter” from high-energy photons not being imaged.

     

  4. D.


    Weak bone agent. Discordance with bone scan – infection is less likely.

     

  5. E.


    Sarcoidosis involving the salivary glands will demonstrate intense Ga67 uptake also known as the “panda sign”.

     


Distribution and Clearance



A327756_1_En_3_Figa_HTML.gif

Distribution

Blood pool (plasma protein bound %) – 24 h, 20 %; 48 h, 10 %; and 72 h, 5 %. Infection site/tumor uptake at 12–24 h.

Liver > bone marrow >> > colon (variable uptake), lacrimal gland, nasopharyngeal, breasts (cycle variant), testes, lung, thymus (peds), spleen, kidneys.

Clearance (1) First 24 h – 25 % clearance by kidneys. (2) ≥ 24 h – bowel> > kidneys. (3) 48 h – 75 % tracer in body.


Normal Distribution



A327756_1_En_3_Figb_HTML.gif

Distribution

Blood pool (plasma protein bound %) – 24 h, 20 %; 48 h, 10 %; and 72 h, 5 %. Infection site/tumor uptake at 12–24 h.

Liver > bone marrow >> > colon (variable uptake), lacrimal gland, nasopharyngeal, breasts (cycle variant), testes, lung, thymus (peds), spleen, kidneys.

Clearance (1) First 24 h – 25 % clearance by kidneys. (2) ≥ 24 h – bowel> > kidneys. (3) 48 h – 75 % tracer in body.

May 26, 2018 | Posted by in NUCLEAR MEDICINE | Comments Off on 3: Clinical Nuclear Medicine – Whole-Body Scans
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