Baseline and ongoing PET-derived factors predict detrimental effect or potential utility of 18F-FDG PET/CT (FDG-PET/CT) performed for surveillance in asymptomatic lymphoma patients in first remission.
OBJECTIVE
To identify both clinical and FDG PET/CT-derived factors predicting the occurrence of relapse, or conversely, the likelihood of false positive findings in surveillance FDG-PET/CT studies (PETsv).


METHODS
The study included 149 asymptomatic patients with Hodgkin's lymphoma (HL) (n = 55) or diffuse large B cell lymphoma (DLBCL) (n = 94) in first remission. PETSv studies were performed 12, 18, 24 and 36 months thereafter. Logistic regression analysis was performed to identify clinical and imaging-derived predictors of either PET-detected relapse or false-positive (FP) results. Tested clinical variables were: 1) age, 2) HL vs. DLBCL, 3) stage of disease, 4) bulky disease, 5) previous radiotherapy. PET/CT-derived variables were: 1) maximum standardized uptake value at baseline, 2) size-incorporated maximum standardized uptake value (SIMaxSUV) at baseline, 3) positive interim PET(PET-2), 4) presence of hot spots likely to be unrelated to the disease in final PET, 5) residual non-FDG avid mass.


RESULTS
Accuracy was 88 % for PETsv1, 95 % for PETsv2, 95 % for PETsv3 and 91 % for PETsv4. However, PPV was relatively low in all PETsv. Best predictors of relapse were result of interim PET, HL versus NHL type, SIMaxSUV, age ≥ 60. Best predictors of FP were previous radiotherapy and hot spots unrelated to the disease in final PET.


CONCLUSIONS
The present study confirms the need of restricting the use of surveillance PET/CT to patients at high risk of relapse. Information derived from PET/CT performed at baseline (metabolic disease burden), in the course (PET2) and at the end of therapy (unrelated hot spots) can help to select high-risk patients and also to identify patients more likely to present equivocal findings at PETsv.
Nuclear Medicine Unit, IRCCS AOU San Martino - IST, Largo R. Benzi 10, 16132, Genoa, Italy. silviadaniela.morbelli@hsanmartino.it.
Silvia
S
Morbelli
Nuclear Medicine Unit, IRCCS AOU San Martino - IST, Largo R. Benzi 10, 16132, Genoa, Italy.
Selene
S
Capitanio
Institute of Molecular Bioimaging and Physiology, CNR, Genoa-Milan, Italy.
Fabrizio
F
De Carli
Nuclear Medicine Unit, IRCCS AOU San Martino - IST, Largo R. Benzi 10, 16132, Genoa, Italy.
Francesca
F
Bongioanni
Department of Hematology and Oncology, IRCCS AOU San Martino-IST, Genoa, Italy.
Enrico
E
De Astis
Department of Hematology and Oncology, IRCCS AOU San Martino-IST, Genoa, Italy.
Maurizio
M
Miglino
Nuclear Medicine Unit, IRCCS AOU San Martino - IST, Largo R. Benzi 10, 16132, Genoa, Italy.
Maria Teresa
MT
Verardi
Nuclear Medicine Unit, IRCCS AOU San Martino - IST, Largo R. Benzi 10, 16132, Genoa, Italy.
Ambra
A
Buschiazzo
Nuclear Medicine Unit, IRCCS AOU San Martino - IST, Largo R. Benzi 10, 16132, Genoa, Italy.
Francesco
F
Fiz
Institute of Molecular Bioimaging and Physiology, CNR, Genoa-Milan, Italy.
Cecilia
C
Marini
Nuclear Medicine Unit, IRCCS AOU San Martino - IST, Largo R. Benzi 10, 16132, Genoa, Italy.
Elena
E
Pomposelli
Nuclear Medicine Unit, IRCCS AOU San Martino - IST, Largo R. Benzi 10, 16132, Genoa, Italy.
Gianmario
G
Sambuceti
D000293:Adolescent; D000328:Adult; D000368:Aged; D058070:Asymptomatic Diseases; D005189:False Positive Reactions; D005260:Female; D019788:Fluorodeoxyglucose F18; D006689:Hodgkin Disease / Q000000981:diagnostic imaging* / Q000628:therapy; D006801:Humans; D008228:Lymphoma, Non-Hodgkin / Q000000981:diagnostic imaging* / Q000628:therapy; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D012074:Remission Induction; D014057:Tomography, X-Ray Computed
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
Hodgkin lymphoma; Interim PET; Non-Hodgkin lymphoma; Positron emission tomography; Surveillance