PET/CT in Lymphoma Dr. Felix Sundram Nuclear Medicine Physician - - PowerPoint PPT Presentation

PET/CT in Lymphoma

• Dr. Felix Sundram

Nuclear Medicine Physician Wijaya International Medical Centre Sime Darby Medical Centre Honorary Lecturer, University Sains Malaysia

Staging of Lymphoma

 Ann-Arbor Classification  WHO Classification  Clinical staging

 Decides treatment plan  Factors taken into account include

 Ann-Arbor Staging  B-symptoms  Age  Extranodal disease  Bulky disease

 Categorized as limited, intermediate & advanced

Gallium-67 citrate

 CT/MRI unable to differentiate residual

disease from fibrosis

 Gallium -67 has low specificity, and low

sensitivity for infradiaphragmatic disease

 Limitations in low-grade NHL  ? Does patient have a gallium - avid

lymphoma

 Logistics of supply from overseas

Non- Hodgkin’s lymphoma of thyroid in a patient with Chronic Thyroiditis and with a solitary nodule in the left lobe.

Uptake only in the nodule

67Ga Scan

Normal uptake in the nodule

201Tl Scan

Role of PET/CT in Lymphoma

 Anatomic imaging such as CT assesses

size of tumor mass

 PET/CT uses metabolic imaging to give a

more reliable indication of tumour burden

 Considerable evidence to support the use

• f FDG PET/CT in Lymphomas (PFS, OS)

Therapy Response Assessment

 Biochemical response  Histopathological response  Morphological response

(CT,MRI,US) RECIST: Response Evaluation Criteria in Solid Tumours PERCIST: PET Response Criteria in Solid Tumours

PET Response Assessment in Lymphomas

 Residual masses at end of therapy are

frequent (70% HD; 50% NHL) but only a minority of patients relapse (<20% HD; 25% NHL )

 Patients in apparent complete remission

also relapse

 Early treatment of residual disease may

improve survival.

Revised Response Criteria for Malignant Lymphoma

 J Clin Oncol 2007; 25: 579-586

 Cheson et al. JCO 2007  CR

Any IWC but PET –ve and BMB –ve except IWC p.d. lesion <1.5cm

 PR

IWC PR/CR, PET +ve in >1 previously involved sites

 SD

IWC SD but PET +ve in previously involved sites

 PD

IWC PD but PET +ve in previously involved sites IWC PD for new lesion <1.5cm

RECIST 1.1 (January 2009 Update)

 Measurable lesion

 > 15mm short axis diameter on CT for lymph-

nodes.

 Target lesion

 Overall 5 target lesions (not > 2 organs) are to

be considered.

 Additional PET (FDG) scan interpretation

PERCIST

 PET assessment of response to therapy

using FDG has a substantial biological relevance and biological predictive value

• f PET seems higher than anatomic

modalities.

PET/CT in Lymphoma

 Staging PET (prognosis/decide treatment)  Interim PET (prognosis/change treatment)  End of treatment PET (prognosis/further

more aggressive treatment)

 Recurrence PET (distinguish the changes

from new disease)

Staging

 FDG( F-18 Fluorodeoxyglucose) PET is

accurate in HL and high-grade/aggressive NHL

 Frequently identifies sites/nodes missed

by CT

 Upstaging and downstaging  Advanced indolent Lymphoma: rarely

positive uptake

NHL Bone Marrow Involvement

 FDG PET does not reliably demonstrate

bone-marrow involvement – especially in low grade lymphoma such as MCL

 False positive uptake in HL  Bone-marrow trephine If clinically

indicated

NHL – Cutaneous T-cell Lymphoma

 Not all lymphoma types are PET positive

 Use to assess response but pre-treatment

PET required

Prognosis at Diagnosis

 Stage  Prognostic scores ( Int’l prognostic index ,

WHO etc.in HL/NHL)

 Tumour response to treatment (PET/CT)

Response Assessment in Interim PET

 In aggressive NHL post 2-3 cycles

 PET +ve :10-50% PFS at 1 year  PET –ve : 75-100% PFS at 1 year

 In HL post 2-3 cycles

 PET +ve : 39% PFS at 5 years  PET –ve :: 92% PFS at 5 years

Hutchings Ann Oncol 2005

 Early PET response – adapted therapy

 Can therapy be changed based on the interim

PET/CT scan

 Trials currently in progress  PET positive disease – increase therapy?  PET negative disease – decrease therapy?

End of Treatment Response

 Tumour size reduction – main criterion

previously

 End of treatment PET highly predictive of

PFS & OS in aggressive NHL

 Less clear for indolent NHL

Activity in Residual Mass

 HL:

high NPV, Less high PPV as false positives may occur due to inflammation.

 NHL:

high PPV, less high NPV as negative result post-treatment cannot exclude minimal residual disease and late relapses with a negative PET are possible.

End of Treatment Response and Follow-up

 Negative PET post treatment cannot

exclude microscopic disease

 Studies show that routine follow-up of

patients with PET/CT offers no advantage

• ver CT

Recurrence

 Main advantage of PET/CT over CT is the

ability to distinguish residual fibrosis or inactive tumour mass from active disease

 Guide excision biopsy if multiple residual

lymph-nodes

Antologous Stem Cell Transplantation (ASCT)

 FDG PET/CT can predict outcome

following ASCT

 PET performed after salvage chemotherapy

and before high-dose chemotherapy and SCT in 60 patients

 25/30 patients with a negative PET study prior

to SCT remained in remission post SCT (median follow-up – 1510 days)

 26/30 patients with abnormal PET study

developed disease progression

Spaepen K et. al. Blood 2003; 102: 53-59

Other PET Tracers



18F-FLT (Fluorothymidine) – high sensitivity

in NHL and potential role in response assessment?



11C-thymidine – staging and response

assessment? Most work and staging research is still with FDG

Conclusion

 PET/CT has a proven role in staging, and

assessment of response of most lymphoma types

 PET/CT has prognostic significance

(staging, interim and end of treatment)