title: Early response assessment in gastrointestinal stromal tumors with FDG PET scan 24 hours after a single dose of imatinib.
abstract: Gastrointestinal stromal tumors (GIST), rare mesenchymal tumors of the gastrointestinal tract, are gaining the interest of researchers because of the impressive metabolic response to the targeted molecular therapeutic drug imatinib mesylate. FDG PET is now routinely used to assess treatment response in cases of GIST because this has proven to give metabolic information, which demonstrates response earlier than anatomic imaging modalities. A 50-year-old man presented with abdominal pain and the CT scan showed a large lobulated heterogeneously enhancing mass in the abdomen. Fine needle aspiration cytology (FNAC) confirmed GIST with strong immunoreactivity to C-Kit protein. A baseline FDG PET done before initiation of therapy showed intense nonhomogenous FDG uptake in the mass (standard uptake value maximum, SUVmax of 13.45). A whole body FDG PET, repeated 24 hours after a single dose of imatinib mesylate 400 mg, showed a significant reduction in FDG uptake with a SUVmax of 4.26.
authors.affiliation: Radiation Medicine Centre, BARC, TMC Annexe, Jerbai Wadia Road, Parel, Mumbai, India. ajitshinto@gmail.com
authors.forename: Ajit
authors.initials: A
authors.lastname: Shinto
authors.forename: Narendra
authors.initials: N
authors.lastname: Nair
authors.forename: Anil
authors.initials: A
authors.lastname: Dutt
authors.forename: Nawab S
authors.initials: NS
authors.lastname: Baghel
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D001549:Benzamides; D044963:Biopsy, Fine-Needle; D003952:Diagnostic Imaging / Q000379:methods; D019788:Fluorodeoxyglucose F18 / Q000494:pharmacology*; D046152:Gastrointestinal Stromal Tumors / Q000175:diagnosis* / Q000000981:diagnostic imaging* / Q000188:drug therapy; D006801:Humans; D000068877:Imatinib Mesylate; D008297:Male; D008875:Middle Aged; D010879:Piperazines / Q000494:pharmacology*; D049268:Positron-Emission Tomography / Q000379:methods*; D019009:Proto-Oncogene Proteins c-kit / Q000378:metabolism; D011743:Pyrimidines / Q000494:pharmacology*; D019275:Radiopharmaceuticals / Q000494:pharmacology*; D013997:Time Factors; D014057:Tomography, X-Ray Computed / Q000379:methods
chemical_list: D000970:Antineoplastic Agents; D001549:Benzamides; D010879:Piperazines; D011743:Pyrimidines; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D000068877:Imatinib Mesylate; D019009:Proto-Oncogene Proteins c-kit