Response to chemotherapy in gastric adenocarcinoma with diffusion-weighted MRI and (18) F-FDG-PET/CT: correlation of apparent diffusion coefficient and partial volume corrected standardized uptake value with histological tumor regression grade.
OBJECTIVE
To assess whether changes in diffusion-weighted MRI (DW-MRI) and (18) F-fluoro-2-deoxyglucose positron emission tomography/computed tomography ((18) F-FDG PET/CT), correlate with treatment response to neoadjuvant therapy (NT), as expressed by tumor regression grade (TRG), from locally advanced gastric adenocarcinoma (GA).


METHODS
Seventeen patients underwent both DW-MRI and (18) F-FDG-PET/CT scans before and after the end of NT. Apparent diffusion coefficient (ADC) and mean standardized uptake value (SUV) corrected for partial volume effect (PVC-SUVBW-mean ) were evaluated and compared with histopathological TRG.


RESULTS
Pre- and post-NT and percentage changes for ADC and PVC-SUVBW-mean were assessed. Post-NT ADC and ΔADC showed a significant inverse correlation with TRG (r = -0.71; P = 0.0011 and r = -0.78; P = 0.00020, respectively) and significant differences in their mean values were found between responders (TRG 1-2-3) and nonresponders (TRG 4-5) (P = 0.0009; P = 0.000082, respectively). No correlations with TRG were found for pre-NT ADC and for all PVC-SUVBW-mean values as well as between ΔADC and Δ PVC-SUVBW-mean .


CONCLUSIONS
DW-MRI seems more accurate than (18) F-FDG-PET/CT and ADC modifications may represent a reproducible tool to assess tumor response for GA.
Department of Radiology and Center for Experimental Imaging, San Raffaele Scientific Institute, Vita-Salute University, Milan, Italy.
Francesco
F
Giganti
Francesco
F
De Cobelli
Carla
C
Canevari
Elena
E
Orsenigo
Francesca
F
Gallivanone
Antonio
A
Esposito
Isabella
I
Castiglioni
Alessandro
A
Ambrosi
Luca
L
Albarello
Elena
E
Mazza
Luigi
L
Gianolli
Carlo
C
Staudacher
Alessandro
A
Del Maschio
D000230:Adenocarcinoma / Q000473:pathology* / Q000628:therapy*; D000368:Aged; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000627:therapeutic use*; D003131:Combined Modality Therapy; D038524:Diffusion Magnetic Resonance Imaging / Q000379:methods*; D005260:Female; D019788:Fluorodeoxyglucose F18; D005743:Gastrectomy; D006801:Humans; D007089:Image Enhancement / Q000379:methods*; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D008297:Male; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods*; D020360:Neoadjuvant Therapy; D009367:Neoplasm Staging; D049268:Positron-Emission Tomography / Q000379:methods*; D011446:Prospective Studies; D013223:Statistics as Topic; D013270:Stomach / Q000187:drug effects / Q000473:pathology; D013274:Stomach Neoplasms / Q000473:pathology* / Q000628:therapy*; D014057:Tomography, X-Ray Computed / Q000379:methods*; D016896:Treatment Outcome
D019788:Fluorodeoxyglucose F18
ADC; DW-MRI; PET/MRI; PVC-SUVBW-mean; TRG; gastric cancer