Role of fluorine-18 fluoro-deoxyglucose positron emission tomography scan in the evaluation and follow-up of patients with low-grade lymphomas.
BACKGROUND
Fluorine-18 fluoro-deoxyglucose positron emission tomography (FDG-PET) scanning has excellent sensitivity and specificity for staging non-Hodgkin lymphomas, but to the authors' knowledge few studies to date have evaluated FDG-PET in low-grade lymphomas only.


METHODS
A retrospective study was performed on patients with biopsy-proven nontransformed and transformed follicular lymphoma (FL), B-cell small-cell lymphocytic lymphoma (SLL/CLL), or marginal zone lymphoma (MZL) who underwent PET and computed tomography (CT) scans within 3 weeks. Standard uptake values (SUV) of all abnormal foci were measured.


RESULTS
In FL, PET demonstrated 94% sensitivity and 100% specificity for staging. PET was more specific than CT for detecting recurrence or assessing therapeutic responses (91% vs. 50%). FDG avidity among patients with WHO Grades 1, 2, and 3 disease was not significantly different (analysis of variance [ANOVA]). For MZL staging, PET had moderate sensitivity (71%) and outperformed CT alone in the depiction of extranodal sites (85% vs. 57% sensitivity). In SLL/CLL, PET sensitivity was 53% and underestimated disease extent in 5 of 19 patients (26%) compared with CT. PET did not affect initial management but confirmed suspected recurrences in 75% of patients. Nontransformed FL had a higher SUV (ANOVA, P < .05) compared with MZL and SLL/CLL. SUV was higher in transformed than in nontransformed tumors (P < .001, Student t test).


CONCLUSIONS
PET usefulness in staging low-grade lymphomas varies depending on histology. PET sensitivity is excellent in FL and moderate in MZL. PET is more specific than CT for follow-up in all types. PET has limited usefulness for SLL/CLL staging. However, a suggestive pattern of hazy and mild uptake was often noted in positive scans. In all low-grade lymphomas, the emergence of foci of intense uptake should raise suspicion of conversion to high-grade disease.
Karam
Maroun
M
Nuclear Medicine Section, Albany Medical College, Albany, New York 12208, USA. karamm@mail.amc.edu
Novak
Leon
L
Cyriac
Jomol
J
Ali
Ameera
A
Nazeer
Tipu
T
Nugent
Francis
F
D019788:Fluorodeoxyglucose F18; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000000981:diagnostic imaging*; D016393:Lymphoma, B-Cell / Q000000981:diagnostic imaging*; D008224:Lymphoma, Follicular / Q000000981:diagnostic imaging*; D008228:Lymphoma, Non-Hodgkin / Q000000981:diagnostic imaging*; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography; D012189:Retrospective Studies; D012680:Sensitivity and Specificity
D019788:Fluorodeoxyglucose F18