[18F-FDG PET/CT in response evaluation of gastrointestinal stromal tumours treated with imatinib].
OBJECTIVE
Several studies have demonstrated the effective use of adjuvant treatment with Imatinib mesylate for unresectable, metastatic or recurrent gastrointestinal stromal tumours (GIST). We retrospectively evaluated the role of 18F-FDG PET/CT scanning in assessing the response of GIST patients to imatinib mesylate therapy.


METHODS
Eight consecutive patients with GIST confirmed by surgery (4 stomach, 2 small bowel, 1 small bowel and peritoneum, and 1 rectum) underwent eighteen 18F-FDG PET/CT imaging after beginning imatinib mesylate therapy (400 mg/day or greater if disease progression). PET/CT scan was acquired 60-90 minutes after the intravenous injection of 333-707 MBq of 18F-FDG. Visual and semiquantitative (standardized uptake value [SUV]) analysis of images was performed. Response to therapy was assessed according to EORTC recommendations for PET. Results were confirmed by clinical follow-up, radiographic findings or histological analysis.


RESULTS
Complete response to imatinib mesylate was observed in 5 patients. Four had abdominal lymph nodes, associated with liver metastases in 2, and the other had a residual tumour mass. Partial response (reduction in SUV and in the extent of FDG uptake) was demonstrated in a patient with lung nodules. Disease progression was observed in one patient who had developed new liver metastases on the PET/CT scan. One patient with multiple peritoneal implants and abdominal mass was a non-responder and died 2 months after the 18F-FDG PET/CT.


CONCLUSIONS
18F-FDG PET/CT scan identified the degree of GIST response to imatinib therapy. Patients who responded to therapy showed normalisation of FDG uptake or a decrease in the SUV of lesions.
Servicio de Medicina Nuclear, Hospital Universitario Marqués de Valdecilla, Universidad de Cantabria, Santander, España. mnubmj@humv.es
I
I
Banzo
R
R
Quirce
I
I
Martínez-Rodríguez
J F
JF
Jiménez-Bonilla
A
A
Sainz-Esteban
J
J
Barragán
H
H
Portilla-Quattrociocchi
J M
JM
Carril
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000627:therapeutic use; D001549:Benzamides; D016903:Drug Monitoring / Q000379:methods; D005260:Female; D019788:Fluorodeoxyglucose F18; D005770:Gastrointestinal Neoplasms / Q000000981:diagnostic imaging* / Q000188:drug therapy; D046152:Gastrointestinal Stromal Tumors / Q000000981:diagnostic imaging* / Q000188:drug therapy; D006801:Humans; D000068877:Imatinib Mesylate; D008113:Liver Neoplasms / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000556:secondary; D008175:Lung Neoplasms / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000556:secondary; D008297:Male; D008875:Middle Aged; D010879:Piperazines / Q000627:therapeutic use; D049268:Positron-Emission Tomography; D011743:Pyrimidines / Q000627:therapeutic use; D019275:Radiopharmaceuticals; D012074:Remission Induction; D014057:Tomography, X-Ray Computed
D000970:Antineoplastic Agents; D001549:Benzamides; D010879:Piperazines; D011743:Pyrimidines; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D000068877:Imatinib Mesylate