title: Paradoxically decreased signal intensity on postcontrast short-TR MR images.
abstract: Seven lesions are presented in which short TR/short TE images obtained immediately after IV administration of gadopentetate dimeglumine demonstrated an apparent decrease in signal intensity compared with precontrast short TR/short TE images. All seven lesions were hyperintense on precontrast short TR/short TE images. In four cases in which long TR/long TE scans were also obtained, the lesions were hypointense. This phenomenon may be due to a dominant T2 shortening effect by the contrast material that "overwhelms" T1 shortening even on short TR/short TE scans. Other compounding factors may include variations in scanning variables, receive and transmit attenuations, or a photographic phenomenon due to window widths and center levels.
authors.affiliation: Department of Radiology, Neuroradiology Section, Hospital of the University of Pennsylvania, Philadelphia 19104.
authors.forename: D M
authors.initials: DM
authors.lastname: Yousem
authors.forename: I
authors.initials: I
authors.lastname: Ihmeidan
authors.forename: R
authors.initials: R
authors.lastname: Quencer
authors.forename: S W
authors.initials: SW
authors.lastname: Atlas
mesh_terms: D003287:Contrast Media; D004338:Drug Combinations; D005069:Evaluation Studies as Topic; D019786:Gadolinium DTPA; D006258:Head and Neck Neoplasms / Q000175:diagnosis; D006801:Humans; D007089:Image Enhancement / Q000592:standards*; D008279:Magnetic Resonance Imaging / Q000379:methods; D008536:Meglumine; D009942:Organometallic Compounds; D009994:Osmolar Concentration; D004369:Pentetic Acid
chemical_list: D003287:Contrast Media; D004338:Drug Combinations; D009942:Organometallic Compounds; D008536:Meglumine; D004369:Pentetic Acid; D019786:Gadolinium DTPA