(18)F-fluorodeoxyglucose positron emission tomography/computed tomography and magnetic resonance imaging in patients with liver metastases from uveal melanoma: results from a pilot study.
OBJECTIVE
(18)F-fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) and MRI are used for detecting liver metastases from uveal melanoma. The introduction of new treatment options in clinical trials might benefit from early response assessment. Here, we determine the value of FDG-PET/CT with respect to MRI at diagnosis and its potential for monitoring therapy.


METHODS
Ten patients with biopsy-proven liver metastases of uveal melanoma enrolled in a randomized phase III trial (NCT00110123) underwent both FDG-PET coupled with unenhanced CT and gadolinium-diethylene triamine pentaacetic acid-enhanced liver MRI within 4 weeks. FDG-PET and MRI were evaluated blindly and then compared using the ratio of lesion to normal liver parenchyma PET-derived standardized uptake value (SUV). The influence of lesion size and response to chemotherapy were studied.


RESULTS
Overall, 108 liver lesions were seen: 34 (31%) on both modalities (1-18 lesions/patient), four (4%) by PET/CT only, and 70 (65%) by MRI only. SUV correlated with MRI lesion size (r=0.81, P<0.0001). PET/CT detected 26 of 33 (79%) MRI lesions of more than or equal to 1.2 cm, whereas it detected only eight of 71 (11%) lesions of less than 1.2 cm (P<0.0001). MRI lesions without PET correspondence were small (0.6±0.2 vs. 2.1±1.1 cm, P<0.0001). During follow-up (six patients, 30 lesions), the ratio lesion-to-normal-liver SUV diminished in size-stable lesions (1.90±0.64-1.46±0.50, P<0.0001), whereas it increased in enlarging lesions (1.56±0.40-1.99±0.56, P=0.032).


CONCLUSIONS
MRI outweighs PET/CT for detecting small liver metastases. However, PET/CT detected at least one liver metastasis per patient and changes in FDG uptake not related to size change, suggesting a role in assessing early therapy response.
Department of Nuclear Medicine, Centre Hospitalier Universitaire Vaudois and University of Lausanne, CH-1011 Lausanne, Switzerland.
Victoria
V
Orcurto
Alban
A
Denys
Verena
V
Voelter
Ann
A
Schalenbourg
Pierre
P
Schnyder
Leonidas
L
Zografos
Serge
S
Leyvraz
Angelika Bischof
AB
Delaloye
John O
JO
Prior
D000328:Adult; D000368:Aged; D005260:Female; D019788:Fluorodeoxyglucose F18; D006801:Humans; D008113:Liver Neoplasms / Q000000981:diagnostic imaging* / Q000556:secondary*; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008297:Male; D008545:Melanoma / Q000000981:diagnostic imaging* / Q000473:pathology*; D008875:Middle Aged; D064847:Multimodal Imaging / Q000379:methods; D010865:Pilot Projects; D049268:Positron-Emission Tomography; D019275:Radiopharmaceuticals; D014057:Tomography, X-Ray Computed; D014604:Uveal Neoplasms / Q000000981:diagnostic imaging* / Q000473:pathology*; D055815:Young Adult; D000098943:Uveal Melanoma
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18