18F-FDG PET/CT in gastric MALT lymphoma: a bicentric experience.
OBJECTIVE
The role of 18F-FDG-PET/CT in evaluating gastric MALT lymphoma is still controversial. In the literature the detection rate of 18F-FDG-PET/CT in patients with gastric MALT lymphoma is variable, and the reason for this heterogeneity is not still clear. Our aim was to investigate the particular metabolic behavior of these lymphoma.


METHODS
Sixty-nine patients (26 female, 43 male) with histologically confirmed gastric MALT lymphoma who underwent a 18F-FDG-PET/CT for initial staging from two centers were included. The PET images were analyzed visually and semi-quantitatively by measuring the maximum standardized uptake value (SUVmax), lesion-to-liver SUVmax ratio, and lesion-to-blood pool SUVmax ratio and compared with Ann Arbor stage, epidemiological (age, sex), histological (presence of gastritis, ulcer, H. pylori infection, plasmacytic differentiation, Ki-67 index), and morphological (tumor size, superficial lesions or mass-forming) characteristics.


RESULTS
Thirty-six patients (52 %) had positive PET/CT (average SUVmax was 9±6.7; lesion-to-liver SUVmax ratio 3.7±2.6, lesion-to-blood pool SUVmax ratio 4.8±3.3) at the corresponding gastric lesion; the remaining 33 were not 18F-FDG-avid. In the univariate analysis, 18F-FDG avidity was significantly associated with morphological features (mass forming p<0.001 and high maximum diameter p<0.001), Ann Arbor stage (p=0.010), and Ki67 index (p<0.001) and not correlated with age, sex, presence of gastritis, ulcer, Helicobacter pylori infection, and plasmacytic differentiation. In the multivariate analysis, the correlations with gross morphological appearance, Ann Arbor stage, and Ki-67 score were confirmed. SUVmax, lesion-to-liver SUVmax ratio, and lesion-to-blood pool SUVmax ratio correlated significantly only with Ki67 index (p=0.047; p=0.012; p=0.042).


CONCLUSIONS
18F-FDG avidity was noted in 52 % of gastric MALT lymphoma and this avidity is correlated with gross morphological characteristics, tumor stage, and Ki-67 index. SUVmax, lesion-to-liver SUVmax ratio, and lesion-to-blood pool SUVmax ratio are correlated only with Ki-67 index, and only lesion-to-liver SUVmax ratio was independently associated with Ki-67 score.
Nuclear Medicine, Spedali Civili Brescia, P.le Spedali Civili 1, 25123, Brescia, Italy. doalba87@libero.it.|University Milano-Bicocca, Milan, Italy. doalba87@libero.it.
Domenico
D
Albano
Nuclear Medicine, Spedali Civili Brescia, P.le Spedali Civili 1, 25123, Brescia, Italy.|University Milano-Bicocca, Milan, Italy.
Mattia
M
Bertoli
University Milano-Bicocca, Milan, Italy.
Paola
P
Ferro
Department of Nuclear Medicine, IRCCS San Raffaele Scientific Institute, Milan, Italy.
Federico
F
Fallanca
Department of Nuclear Medicine, IRCCS San Raffaele Scientific Institute, Milan, Italy.
Luigi
L
Gianolli
Department of Nuclear Medicine, IRCCS San Raffaele Scientific Institute, Milan, Italy.
Maria
M
Picchio
Nuclear Medicine, University of Brescia and Spedali Civili Brescia, Brescia, Italy.
Raffaele
R
Giubbini
Nuclear Medicine, University of Brescia and Spedali Civili Brescia, Brescia, Italy.
Francesco
F
Bertagna
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D018442:Lymphoma, B-Cell, Marginal Zone / Q000000981:diagnostic imaging* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D000072078:Positron Emission Tomography Computed Tomography; D019275:Radiopharmaceuticals; D013274:Stomach Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18
18F-FDG PET/CT; FDG avidity; Gastric MALT lymphoma; Gastric lymphoma; MALT lymphoma