ORIGINAL ARTICLES   

The Quarterly Journal of Nuclear Medicine and Molecular Imaging 2004 September;48(3):188-97

Copyright © 2009 EDIZIONI MINERVA MEDICA

language: English

Imaging characterization of non-hypersecreting adrenal masses. Comparison between MR and radionuclide techniques

Maurea S. ¹, Caracò C. ², Klain M. ¹, Mainolfi C. ¹, Salvatore M. ¹

¹ Division of Radiology and Nuclear Medicine Department of Biomorphological and Functional Sciences “Federico II” University of Naples, Naples, Italy 2 Institute of Biostructures and Bioimages National Council for Researches (CNR), Naples, Italy

Aim. In ­patients ­with non-hyper­se­cret­ing adren­al mass­es, ­tumor char­ac­ter­iza­tion is clin­i­cal­ly rel­e­vant to estab­lish the appro­pri­ate treat­ment plan­ning. The aim of ­this ­study was to com­par­a­tive­ly char­ac­ter­ize ­such adren­al ­lesions ­using MR and radio­nu­clide tech­niques.
Methods. Thirty ­patients ­with non-hyper­se­cret­ing uni­lat­er­al adren­al ­tumors under­went ­both MR and adren­al scin­tig­ra­phy. MR was per­formed ­using SE T1- (pre- and ­post-gad­o­lin­ium ­DTPA) and T2-weight­ed imag­es as ­well as in- and out-­phase chem­i­cal-­shift imag­ing (CSI). MR qual­ita­tive and quan­ti­ta­tive (sig­nal inten­sity ­ratios) eval­u­a­tion was per­formed. Radionuclide stud­ies con­sist­ed of ­iodine-131 nor-cho­les­te­rol (n=20), ­iodine-131 ­MIBG (n=15) and flu­o­rine-18 FDG PET (n=11) ­scans. Histology (n=16), biop­sy (n=3) or clin­i­cal-imag­ing fol­low-up (n=11) dem­om­strat­ed 13 aden­o­mas, 3 ­cysts, 2 mye­lo­lip­o­mas, 4 phe­och­rom­o­cy­to­mas (phe­os), 4 car­ci­no­mas, 1 sar­co­ma and 3 metas­ta­ses. Comparative imag­ing anal­y­sis was ­focused on aden­o­mas, phe­os and malig­nant ­tumors. Results. Qualitative MR eval­u­a­tion ­showed: sig­nal T2-hyper­in­ten­sity in 46% of aden­o­mas and in 100% of phe­os and malig­nant ­tumors, no gad­o­lin­ium enhance­ment in 92% of aden­o­mas and def­i­nite sig­nal inten­sity ­loss on CSI in 100% of ­such ­tumor ­lesions, gad­o­lin­ium enhance­ment in 100% of phe­os and in 63% of malig­nan­cies and no abso­lute ­change of sig­nal inten­sity on CSI in 100% of ­both phe­os and malig­nan­cies. Quantitative MR anal­y­sis dem­on­strat­ed: sig­nif­i­cant­ly high­er sig­nal T2-hyper­in­ten­sity of phe­os com­pared to aden­o­mas and malig­nan­cies as ­well as sig­nif­i­cant­ly high­er enhance­ment ­after gad­o­lin­ium in phe­os com­pared to aden­o­mas and malig­nan­cies (p<0.03). Radionuclide stud­ies ­showed sig­nif­i­cant­ly ­increased nor-cho­les­te­rol ­uptake ­only in aden­o­mas (n=13), sig­nif­i­cant ­MIBG accu­mu­la­tion ­only in phe­os (n=4) and FDG activ­ity ­only in malig­nant adren­al ­lesions (n=8).
Conclusion. MR tech­niques may pro­vide ­some pre­sump­tive cri­te­ria to char­ac­ter­ize non-hyper­se­cret­ing adren­al mass­es, ­such as no gad­o­lin­ium enhance­ment and def­i­nite sig­nal inten­sity ­loss on CSI in aden­o­mas or quan­ti­ta­tive­ly meas­ured T2-hyper­in­ten­sity and gad­o­lin­ium enhance­ment in phe­os. On the oth­er ­hand, radio­nu­clide modal­ities ­offer ­more spe­cif­ic find­ings in ­this set­ting ­since nor-cho­les­te­rol and ­MIBG ­scans are respec­tive­ly ­able to ­reveal ­benign ­tumors ­such as aden­o­ma and phe­och­rom­o­cy­to­ma, ­while FDG imag­ing ­allows iden­tifi­ca­tion of malig­nant adren­al ­lesions. Adrenal scin­tig­ra­phy is rec­om­mend­ed in ­those ­patients, ­when MR imag­es are uncer­tain or incon­clu­sive.