Radiology

2. USE OF PET SCAN IN NSCLC:
OUR INITIAL EXPERIENCE

3. WHAT IS PET IMAGING
POSITRON EMISSION TOMOGRAPHY IS AN EXCITING NEW
MODALITY WHERE SHORT LIVED POSITRON EMITTING
ISOTOPES
ARE USED TO IMAGE FUNCTION AND METABOLIC
ACTIVITY OF
DIFFERENT ORGANS AND DISEASE PROCESSES.

4. EDWARD J HOFFMAN &MICHAEL PHLEPS DEVELOPED THE
FIRST HUMAN PET SCANNER IN 1973 AT WASHINGTON
UNIVERSITY.
PET CENTER AT UNIVERSITY OF PENNYSYLVANIA WAS THE
FIRST CENTER ESTABLISHED IN 1975 AS A RESEARCH FACILITY
FOR STUDY OF HUMAN BRAIN FUNCTION.
SINCE 1991 PET APPLICATION INCREASED &INCLUDED IN
CLINICAL STUDIES

5. APPLICATION OF PET
ONCOLOGY
 EARLY DETECTION OF
CANCER
 MAPPING EXTENT OF
DISEASE/STAGING.
AS A TOOL IN RT PLANNING.
MONITORING RESPONSE OF
THERAPY
DETECTING RECURRENCES
DIFFERENTIATING
RECURRENCES FROM EDEMA/
NECROSIS.
NON ONCOLOGY
CARDIOLOGY
 NEUROLOGY
INFECTION IMAGING

6. PET IS MOSTLY USED IN:
LUNG CANCER
 BREAST CANCER
 LYMPHOMA
 MELANOMA
 COLON CANCER
 HEAD AND NECK CANCERS

7. TREATMENT OF NSCLC DEPENDS ON :
LOCATION OF PRIMARY TUMOR
• EXTENTION OF DISEASE
• PRESENCE OR ABSENCE OF MEDICAL COMORBIDITIES
• ASSESSMENT OF .
- EXTAPULMONARY INTRATHORACIC
METASTASIS.
- EXTRATHORACIC METASTASIS

8. PET SCAN :INNOVATION IN LUNG
CANCER IMAGING
WHOLE BODY FDG PET SCAN HAS SHOWN
99% SENSITIVITY IN DETECTING PRIMARY TUMOR AT
INITIAL WORK UP FOR NSCLC.
91% SENSITIVITY IS SEEN AT DETECTING MEDIASTINAL
LYMPH NODE PREOPERATIVELY.

9. OVERVIEW FROM VARIOUS PROSPECTIVE
PERFORMANCE STUDIES
IN ASSESSMENT OF LOCOREGIONAL LYMPH
NODE SPREAD
PET HAS :
NEGATIVE PREDICTIVE VALUE IN EXCLUSION OF
N2 OR N3 DISEASE.
FALSE NEGATIVE RESULTS IN MEDIASTINAL PET
WITH MINIMAL N2 DISEASE.
- FALSE POSITIVE FINDINGS SEEN IN PATIENTS
WITH
INFLAMMATORY NODES.
GRANULOMATOUS DISORDERS.
ISOLATED POSITIVE FINDING NEEDS PATHOLOGIC
VERIFICATON: POSSIBILITY OF FALSE POSITIVE RESULTS.

10. IN EXTRA THORACIC STAGING PET IS USEFUL ADJUNCT
TO CONVENTIONAL IMAGING
DUE TO ABILITY TO DETECT UNEXPECTED
METASTASIS
CURRENTLY INSUFFICIENT DATAAVAILABLE TO STATE
THAT PET COULD REPLACE STANDARD IMAGING.
IT NOW UNDERGOES VALIDATION IN LARGE SCALE
RANDOMISED PATIENT OUTCOME STUDIES.
MEANWHILE CURRENT RECOMMENDATION FOR USE OF
PET SCAN IN CONTEMPORARY LUNG CANCER IS
PROVIDED.

11. HIGH RATE OF DETECTION OF UNSUSPECTED DISTANT
METASTASIS BY PET SCAN IN APPARENT STAGE III
NSCLC:IMPLICATIONS FOR RADICAL RADIATION
THERAPY.
PET STAGING IS RECOMMENDED FOR RADICAL RT,
AS HIGHEST YEILD OF UNSUSPECTED DISTANT
METS IS OBSERVED IN STAGE III DISEASE &
ULTIMATELY PATIENT DIE OF DISTANT METASTASIS.
COMPARISON OF PET-STAGED AND
CONVENTIONALLY STAGED COHORTS TREATED .
TWO PROSPECTIVE COHORTS : PET SCAN 80 PTS.
: NON PET SCAN
77 PTS.
30% OF RADICAL RT CANDIDATES BECAME INELIGIBLE
FOR RADICAL RT AS COMPARED WITH THOSE STAGED
CONVENTIONALY.

12. 23% CASES MANAGEMENT STRATEGY CHANGED FROM
RADICAL TO PALLIATIVE INTENT
22% CASES NEW FDG AVID NODES FOUND IN 5 CM OF
PRIMARY TUMOR WERE INCLUDED IN PTV
17-29% CASES POORLY COVERED WITH CT BASED
GEOGRAPHICAL MISS WELL INCLUDED IN PET PLANNING
30-76% CASES INCREASE IN PTV
24-70% CASES REDUCTION IN PTV
( HIGH IMPACT IN PATIENT WITH ATELECTASIS)
THUS RELATIVE CHANGE IN PTV RANGED FROM 0.4 -
1.86

13. REVIEW LITERATURE :FDG PET IMPACT ON STAGE
& CONTOURED GTV
TNM STAGING CHANGED 8/26 (31%)
METS DISEASE FOUND 2/26 (8%)
GTV CONTOUR CHANGED 14/24 (58%)
GTV VOLUME DECREASE 3/24 (12%)
GTV VOLUME INCREASED 11/24 (46%)
(ADDITIONAL TUMOR DETECTED)
MINIMAL GTV CHANGE 10/24 (42%)

14. MEAN LUNG DOSE, V20,MEAN ESOPHAGIAL DOSE HAS BEEN
IDENTIFIED
AS PREDICTORS OF NORMAL TISSUE COMPLICATIONS
WHEN GTV DECREASED IN PATIENTS WITH ATELECTASIS
,DOSES OF
NORMAL TISSUES SUCH AS LUNG AND ESOPHAGUS ARE
DECREASED
- THEREBY PROBABILITY OF PNEUMONITIS AND
ESOPHAGITIS IS DECREASED
 WHEN GTV ENLARGED TO INCORPORATE ADDITIONAL PET
DETECTED
TUMOR , THE VALUES OF MEAN LUNG DOSE, V20 & MED
ARE INCREASED
LEADING TO HIGHER COMPLICATIONS PROBABILITIES

15. MONITORING TREATMENT RESPONSE IN
NSCLC
PET CAN DIFFERENTIATE BETWEEN RECURRENT OR RESIDUAL
TUMOR
AND POST TREATMENT CHANGES
(ALTHOUGH CONVENTIONAL NON INVASIVE MODALITIES SUCH AS
CT OR MRI PROVIDES EXCELLENT MORPHOLOGIC INFORMATION)
USING SUV OF EARLY AND DELAYED IMAGES, RETENTION
INDEX IS
CALCULATED ( RI < 0.1; > 0.1) {SUV=STANDARDISED
UPTAKE VALUE}
 FINAL WEEK OF RT PET IS DONE WITH INTENTION OF
INCREASING
FINAL DOSE (IN PATIENS WHOSE RI REMAINS ELEVATED)
SERIAL IMAGING AT SAME SITES OVER A PERIOD OF MORE
THAN 3 MONTHS
CLARIFY THE EFFICACY OF THIS MODALITY IN THE PROVISION
OF
PROGNOSTIC INFORMATION

16. DECIDING TREATMENT STRATEGY :
CURATIVE / PALLIATIVE.
IMPROVES VOLUME DELINEATION :
TARGET
NORMAL/CRITICAL ORGAN.
REDUCES RISK OF GEOGRAPHICAL MISS.
DISTINGUISHES TUMOR FROM ATELECTASIS.
 PROGNOSIS / MONITORING TREATMENT
RESPONSE.