Lowe,VJ

PET/CT in Cancer: A General

Overview & State of the Art

Val J. Lowe, MD Val J. Lowe, MD

PET Facility

Mayo Clinic

Lowe,VJ

Unstable parentnucleus

Proton decays toneutron in nucleus Positron and

neutrino emitted

Positron combineswith electron andannihilates

Two 511 keVphotons produced~180 apart

Positron Emission

and Annihilation

Radioisotopes

Lowe,VJ

Increased glucose metabolism in cancer

(Warburg 1930)

[18]F-2-deoxy-2-flouro-D-glucose (FDG)

trapping in tumor cells has been described

and is the result of the increased glucose

metabolism in tumors (Gallagher, 1978)

[18]F-2-deoxy-2-flouro-D-glucose (FDG)

Lowe,VJ

OH

OH

OH

OH

HO

O

OH

OH

OH

HO

O

OH

OH

OH

HO

O

F

D-Glucose 2-Deoxy-D-Glucose

2-Deoxy-2-Fluoro-D-Glucose

FDG Physiology

Lowe,VJ

Vascular Capillary Extra- Intracellular metabolism

compartment membrane cellular space

HexokinaseGlucose

Glucose

G - 6 - P

Hexokinase18

FDG18FDG

G - 6 - P

Glycogen

Phosphorylase 'a'

G - 1 - PO4

G - 6 - PO4

F - 6 - PO4

CO2 + H2O

18FDG - 6 - PO4

Cell membrane

FDG Physiology

Lowe,VJ

15 years ago:

PET Lung Scan

20 minute emission for 20 cm

axial field of view

+ 20 minutes for attenuation

correction = 40 minutes for 20

cm

PET/CT Development

Lowe,VJ

7 years ago:

CT unit fusion to PET:

Responded to the need for

anatomic information coupled

to PET

Provided a faster way to get

attenuation correction leading

to 40 minute body scans

PET/CT Development

Lowe,VJ

Summary Today:

Imaging Speed:

Different machines can give 15-40

minute whole-body images

Anatomic CT fusion:

A selection of CT resolutions

PET/CT Development

Lowe,VJ

In the works for tomorrow’s “State

of the Art”:

Imaging Speed:

?? 5 minute whole body scans

Improved Accuracy:

New tracers

Time of flight reconstruction

PET/CT Development

A B C D

Coronal images of an average patient with a BMI of 27

kg/cm2.

A) 2D acquisition, 5 min per bed;

B) 3D acquisition, 5 min per bed;

C) 3D acquisition, 3 min per bed;

D) 3D acquisition, 2 min per bed.

Lowe,VJ

PET/CT Equipment

PET component

Respiratory gate triggering

Allows respiratory gating and positioning of a lung nodule more accurately

The data is sparse but this could improve the characterization of some lung nodules

Lowe,VJ

PET New Developments

Respiratory gating: After WB scan, acquire

respiratory gated study centered on lesion

3D, list mode, 8 bin, 10 min, one bed

Summed

Gated, bin 3

Lowe,VJ

PET/CT can perform the most accurate N and M staging in almost all aggressive cancers compared to CT, MRI or US.

PET has great potential to evaluate cancer therapy; results better than CT

PET may provide more specific molecular targeting capability in the future

PET/CT in Cancer: A General Summary of Performance

Lowe,VJ

Medicare and Insurance Coverage

Steady indication by indication approval by CMS of PET/CT in oncology in the last 2 decades

Still, FDA approvals lagging for its use but not hampering clinical use and reimbursement

Specific language needs to be used in ordering

Final F ram ework

Solid Tumo r Ty pe Ini t ial Tre atm ent

Strat egy*

Subs eq ue nt

Tre atment

Strat egy **

Colorectal Co ver Co ver

Es op hagus Co ver Co ver

Head & Neck (not thyroid or CNS) Co ver Co ver

Lymphoma Co ver Co ver

Non - s mall ce ll lung Co ver Co ver

Ovary Co ver Co ver

Bra in Co ver CED

Cervix 1 or CED Co ver

Small ce ll lung Co ver CED

Soft Tis sue Sarcoma Co ver CED

Panc re as Co ver CED

Test e s Co ver CED

Bre ast (fe m al e and m al e) 2 Co ver

Mel anoma 3 Co ver

Prostate N/ C CED

Thyroid Co ver 4 or CED

All o the r sol id tu mors Co ver CED

Myeloma Co ver Co ver

All o the r cance rs no t l is ted her e in CED CED

1) Cervix: Covered for the detection of pre-

treatment metastases (i.e., staging) in newly

diagnosed cervical cancer subsequent to

conventional imaging that is negative for

extra-pelvic metastasis. All other uses are

CED.(2) Breast: Noncovered for diagnosis

and/or initial staging of axillary lymph nodes.

Covered for initial staging of metastatic

disease.(3) Melanoma: Noncovered for

initial staging of regional lymph nodes. All

other uses for initial staging are

covered.(4) Thyroid: Covered for

subsequent treatment strategy of recurrent

or residual thyroid cancer of follicular cell

origin previously treated by thyroidectomy

and radioiodine ablation and have a serum

thyroglobulin >10ng/ml and have a negative

I-131 whole body scan. All other uses for

subsequent treatment strategy are CED.

CMS Coverage List