title: Prospective study of p-[123I]iodo-L-phenylalanine and SPECT for the evaluation of newly diagnosed cerebral lesions: specific confirmation of glioma.
abstract: OBJECTIVE
  The differentiation between gliomas, metastases and gliotic or inflammatory lesions by imaging techniques remains a challenge. Gliomas frequently exhibit increased uptake of radiolabelled amino acids and are thus amenable to PET or SPECT imaging. Recently, p-[123I]iodo-L-phenylalanine (IPA) was validated for the visualization of glioma by SPECT and received orphan drug status. Here we investigated its diagnostic performance for differentiating indeterminate brain lesions.
  
  
  METHODS
  This prospective open study included 67 patients with newly diagnosed brain lesions suspicious for glioma (34 without and 33 with contrast enhancement in the MRI scan). Patients received 250 MBq IPA intravenously after overnight fasting. SPECT images at 30 min and 3 h post-injection were iteratively reconstructed and visually interpreted after image fusion with an MRI brain scan (fluid-attenuated inversion recovery sequence or T1-weighted contrast-enhanced image). Findings were correlated with results of stereotactic or open biopsies or serial imaging.
  
  
  RESULTS
  Twenty-seven low-grade (2 WHO I, 25 WHO II) and 24 high-grade gliomas (1 WHO III, 23 WHO IV), 3 metastases originating from lung cancer as well as 13 non-neoplastic lesions were proven. All non-neoplastic lesions and all metastases were negative with IPA SPECT. Forty gliomas were true-positive (TP) and 11 false-negative (FN) findings (8 WHO II, 1 WHO III, 2 WHO IV) occurred. There were no false-positive (FP) findings. For the differentiation of primary brain tumours and non-neoplastic lesions, sensitivity and specificity were 78 and 100%. In 34 lesions without contrast enhancement in MRI, IPA SPECT resulted in 17 TP, 8 true-negative, 9 FN and no FP findings (sensitivity 65%, specificity 100%).
  
  
  CONCLUSIONS
  In patients with suspected glioma, IPA SPECT shows a high specificity, but especially in low-grade gliomas FN findings may occur. Due to the high positive predictive value a positive finding allows a suspected glioma to be confirmed.
authors.affiliation: Department of Nuclear Medicine, Saarland University Medical Center, 66421, Homburg/Saar, Germany. Dirk.Hellwig@uks.eu
authors.forename: Dirk
authors.initials: D
authors.lastname: Hellwig
authors.forename: Ralf
authors.initials: R
authors.lastname: Ketter
authors.forename: Bernd F M
authors.initials: BF
authors.lastname: Romeike
authors.forename: Andrea
authors.initials: A
authors.lastname: Schaefer
authors.forename: Georgios
authors.initials: G
authors.lastname: Farmakis
authors.forename: Aleksandar
authors.initials: A
authors.lastname: Grgic
authors.forename: Jean R
authors.initials: JR
authors.lastname: Moringlane
authors.forename: Wolf-Ingo
authors.initials: WI
authors.lastname: Steudel
authors.forename: Carl-Martin
authors.initials: CM
authors.lastname: Kirsch
authors.forename: Samuel
authors.initials: S
authors.lastname: Samnick
mesh_terms: D001932:Brain Neoplasms / Q000000981:diagnostic imaging*; D005260:Female; D005910:Glioma / Q000000981:diagnostic imaging*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010649:Phenylalanine / Q000031:analogs & derivatives*; D011446:Prospective Studies; D019275:Radiopharmaceuticals; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*
chemical_list: C496694:2-iodophenylalanine; D019275:Radiopharmaceuticals; D010649:Phenylalanine