Diagnostic Radiology PET Scan by zerosoul

VIEWS: 192 PAGES: 12

									PET-CT & MOLECULAR IMAGING

DR YAU YAT YIN

ELECTRON ABSORPTION

WHAT IS CT?

GREY SCALE MAP IN OLD DAYS
010203000000000000 000002222220033333 010101010101010101 010100101010100100 050505050202030503 030003300000000000 808089282888888888 888804567899000000 111111111111111111

WHAT IS CT?

WHAT IS CT?

WHAT IS CT?

WHAT IS CT?

1

CT - EXCELLENT SPATIAL RESOLUTION

INFLAMMATION OR TUMOR

SMALL TUMOR

WHAT IS CT?

SM NODES - MET OR REACTIVE

LIMITATION OF ANATOMICAL IMAGING
•Can characterize mass but not its contents •Difficult to differentiate small tumor foci from surrounding normal tissue •Lymph Node: detect presence but not its significance

DIFFERENCE - AVAILABLE TYPE OF IMAGING NM Tracer Pathology

MRI & CT
•Post-op or RT tissue distortion necrosis Vs tumor recurrence
CT, MRI & US

FUNCTIONAL IMAGING -NM

PET BASIC PRINCIPLE

PET BASIC PRINCIPLE
Glucose is a cell’s energy source. Cancer cells metabolize more glucose than normal cell
南方 PET中心

18 F-FDG的 像原理 ?

Vascular

Tumor Cell
Glycogen
18 FDG-1-P

INSIDE HUMAN BODY
18 FDG

K1

Hexokinase
K3
18 FDG 18 FDG-6P

18 FDG-6-

K2

K4

Glucose-6phosphatase

phosphogluconolactone

HMP shunt

18 F-fru-6-P

POSITRON EMITTERS: Fluorine 18, NH3, C 11 & O18

Glucose transporter protein

Glycolysis

NM - PHOTONS

GLUCOSE ANALOG

2

Shielding and Septa

WHAT IS PET?
• Scintillators

Photomultipliers Scintillator

B A D C

γ (511 keV)

Radioactivity metabolic map

WHAT IS PET??

WHAT METABOLISM?

POSITRON EMISSION TOMOGRAPHY
• • • • • •

PROBLEM WITH PET
Lesion <6-10mm Small tumor burden Low grade tumor Non-FDG avid High background uptake e.g brain, urine Takes 45-60 min WB

METABOLIC IMAGING
Where are these hot Spots? NAD

Correlation with other imaging

POOR SPATIAL RESOLUTION

LONG EXAM TIME

TRUE FUSION

METABOLIC IMAGING

WHAT IS PET-CT

Difficulty in little tissue contrast area with eyeballing Exact fusion not possible in big body parts where motion can occur : breathing/ peristalsis Different scanning technique/time Difficulty with small lesions

LIMITATION OF PSUEDO FUSION

3

PET/CT ACQUISITION
Crystal detector speed & resolution
110 cm
60 cm
CT PET

168 cm

1. Patient preparation/positioning 2. Topogram (Scout scan) 3. Spiral CT scan (CT contrast?) implants patient motion

CT

PET
100 cm

CT-based corrections 4. Multi-bed PET emission scan AC-PET reconstruction

truncation noise

PET-CT SCANNER

PET-CT CORRECTED PET LIMITATION
• Site precision XX • False +ve: *

WHAT IS ADVANTAGE OF PET-CT

*=胃,腸,頭頸部,心 臟,腎,子宮,腦,膀 胱,甲狀線,聲帶.

56F treated Ca Breast 10 years ago. Presented with chest discomfort
PET-CT 4/7/02 : Metastases to bones, neck, Mediastinal & internal mammary nodes causing SVC obstruction.

PET-CT Vs PET, BONE &/OR CT
Bx: Adenocarcinoma of breast origin

NAC

Bone scan & PET scan 12/7/02 showed sternal lesion. Repeat CT in the same department also failed to demonstrate suspicious neck nodes.

PET-CT MORE ACCRUATE

4

PET-CT VALIDATION
PET in oncology overall fig : Sensitivity: 84-87% Specificity: 88-93% Accuracy: 87-90% JNM 2001; 42:1S-93S PET-CT

WHY DO YOU USE PET-CT?
Provides additional info than PET or CT alone in 49% Improves lesion characterization in 15% Retrospective Dx in 8% (CT or PET) Impact on management in 14%

Bar-Shalom et al. JNM 2003;44:1200-1209 204 patients over 9 month with follow up

PET-CT IN OTHER SPECIALTY
• Is there a lesion ? e.g post op scarring or recurrence, equivocal imaging or biopsy result, raised tumor marker • Is a lesion benign or malignant – post op? • Is lesion operable? • Search for a primary • Define site of Bx •

SPN & VALUE OF SUV -Dx

Oncology- Staging, Monitor Rx, Follow up & Recurrence

SUV 2.9

SUV 4

Sensitivity 94%, Specificity 86%

40F, Right Breast Ca, US- 1.8cm, STAGING

48F, PH of colon Ca, C/O abdo pain

Bx Guidance

5

38M, Ca COLON 2001. CT 2002 LIVER MET. POST Rx 2003

37M, WT LOSS, CT- LIVER MASSES, AFP NORMAL

COLONOSCOPY NEGATIVE

Post L hepatectomy Recurrence

FOLLOW UP/MONITOR Rx

BX GUIDANCE - GIST

49F, PRESENTED WITH LT SCF LN ? PRIMARY

PET-CT: UNKNOWN PRIMARY
50F,Left hip pain. MRI – metastatic disease. Primary not found.

SC DEPOSIT Bx SITE

Bx & TAH

UTERINE SARCOMA

CA OV- TAHBSO 2000 & POST OP CHEMO/ RT. RAISED CA125

Ca Cervix 2002 treated with chemoradiation. Presented with bowel obstruction.

PET-CT FOLLOW UP

PERITONEAL SEEDING 6M

Radiation Changes & nodes

2ND TUMOR- Ca BREAST CONFIRMED

2nd PATHOLOGY - THYROIDITIS

6

ENLARGED LN ON CT.? TUMOR ? RESIDUAL DISEASE

PUO

LIMITATION

CVP LINE INFECTION

PET-CT FOR RT PLANNING

IMRT

CT COLONOSCOPY PART OF PET-CT

SURGICAL ROADMAP

CABG

LIMA RIMA

CARDIOLOGY: Viability Perfusion
RIMA - LCx LMB

7

PET-CT FOR MILD COGNITIVE IMPAIRMENT

TUMORS DIFFICULT WITH PET
• Tumors arising from organ with physiological uptakes of FDG will be obscured e.g. bladder, prostate, bowel, brain, parotid gland. • False negative: tumors not take up FDG or low cellularity or can metabolize FDG e.g BAC, metastatic liposarcoma, HCC, neuroendocrine (carcinoid), MALT, urothelial, mucinous & low grade tumors • Sclerotic bone mets do not take up much FDG e.g prostate • For ovarian Ca, needs to be >1cm. Peritoneal spread cannot be seen if sheet like • Lesions <5-7mm

BRAIN ONCOLOGY
? Normal Testicular uptake

NECROSIS Vs RECUR Brain Met, Sen 68%, Spec 38%

SEMINOMA OF RIGHT TESTIS

TUMOR IN HIGH BACKGOUND ACTIVITY

53M. PH Hepatitis B, Normal AFP, RUQ pain

50% HCC FDG avid

BLADDER CA

FDG –VE, CT +VE

8

PERITONEAL LESIONS = PROBLEMS

PET-CT FAULTS
34y:right cervical node enlargment. FNA = atypical cell. ?malignancy

Bx- TB

LIMITATION OF PET-CT

CA TAIL OF PANCREAS , POST OP 3.5WK. FOR RT PLANNING

SUV max 4.7 55y, Clear cell Ca ovary 3y ago. Rx TAHBSO & chemo. Follow up.

Bx = Hematoma

INFLAMMATION Vs RESIDUAL TUMOR

RADIATION EXPOSURE
• • • • • • • • • CT Head = 2.7mSv CT Th/Abdo/Pelvis = 24.4mSv Low dose CT thorax = 0.4mSv CXR = 0.2mSv, IVP = 4.4mSv Whole body PET = 11.6mSv Brain PET = 5.8mSv Cardiac PET = 7.2mSv Watching 1h TV 10uSi, (=2y ,5h@d) Taipei to NY flight 156uSi
Radiation Exposure in CT by European Coordination Committee of the Radiological & Electromedical Industries 2000

THANK

YOU

9

ROUTINE CHECK – CEA ELEVATED

SUV 2.4

VALUE OF SUV

PET-CT BACKGROUND & DEMAND
2001- only 5 in the world Pittsburgh-1st,3-6/D Zurich- 2nd,6/D Johns Hopkins:8/D MSKCC- 6-10/D,2nd PET-CT= 30/D HK: HKAH ,HKBH> HKSH, QE

2 Centres >2400 patients

MRI EXCELLENT SOFT TISSUE DETAIL

PET DETECTOR COMPONENTS

? LIMITATION

MR SPECTROSCOPY

10

VALUE OF PET-CT
WHICH UPTAKE IS ABNORMAL?

PET-CT IMMEDIATE DIAGNOSIS – NO NEED TO REDO CT

CONFIDENT Dx

NO MISTAKE OF NORMAL STRUCTURES

6Y with painful left knee and limping

PRESENTED WITH BONE PAIN, PSA LEVEL HIGH

34 male,intermittent LtHip pain, MRI- ? AVN. PET-CT to exclude synovial Sacrcoma。

VALUE OF PET-CT
46F, PR Bleed
Bx=Adenocarcinoma

VALUE OF ORAL CONTRAST

11

PET-CT- accurate localization
72F, NON-HODGKIN LYMPHOMA, PET-CT FOR STAGING

ACCURATE STAGING
64 y/o female with past hx of ovarian CA 84 s/p TAH/BSO/chemo Recurrence 1990 Now has raised CA-125。 Recent CT reported NAD

12


								
To top