Differentiation of malignant tumours from granulomas by using dynamic [ 18 F]-fluoro-L-αmethyltyrosine

Transcription

1 Ymguchi et l. EJNMMI eserch (205) 5:29 DOI 0.86/s z OIGINA ESEACH Open Access Differentition of mlignnt tumours from grnuloms y using dynmic [ 8 F]-fluoro--αmethyltyrosine positron emission tomogrphy Aiko Ymguchi, Hirofumi Hnok, Yutk Fujisw 2, Songji Zho 3,4, Kzutomo Suzue 5, Akihiro Morit 2, Hideyuki Toming 6, Tetsuy Higuchi 7, Hjime Hised 5, Yoshito Tsushim 7, Yuji Kuge 8,9 nd Ysuhiko Iid,2* Astrct Bckground: Previous clinicl studies hve reveled the potentil of [ 8 F]-fluoro--α-methyltyrosine ( 8 F-FAMT) for the differentil dignosis of mlignnt tumours from srcoidosis. However, one concern regrding the differentil dignosis with 8 F-FAMT is the possiility of flse negtives given the smll solute uptke of 8 F-FAMT tht hs een oserved in some mlignnt tumours. The im of this study ws to evlute usefulness of dynmic 8 F-FAMT positron emission tomogrphy (PET) for differentiting mlignnt tumours from grnuloms. Methods: ts ering oth grnuloms (Mycocterium ovis cillus Clmette-Guérin (BCG)-induced) nd tumours (C6 gliom cell-induced) underwent dynmic 2-deoxy-2-[ 8 F]-fluoro-D-glucose ( 8 F-FDG) PET nd 8 F-FAMT PET for 20 min on consecutive dys. Time-ctivity curves, sttic imges, men stndrdized uptke vlues (SUVs) nd the SUV rtios (SUVs; clculted y dividing SUV t ech time point y tht of 2 min fter injection) were ssessed. esults: In tumours, 8 F-FAMT showed shoulder pek immeditely fter the initil distriution followed y grdul clernce compred with grnuloms. Although the men SUV in the tumours (.00 ± 0.0) ws significntly higher thn tht in the grnuloms (0.88 ± 0.2), lrge overlp ws oserved. In contrst, the SUV ws mrkedly higher in tumours thn in grnuloms (50 min/2 min, 0.72 ± 0.06 nd 0.56 ± 0.05, respectively) with no overlp. The dynmic ptterns, SUV, nd men SUV of 8 F-FDG in the grnuloms were comprle to those in the tumours. Conclusions: Dynmic 8 F-FAMT nd SUV nlysis might compenste for the current limittions nd help in improving the dignostic ccurcy of 8 F-FAMT. Keywords: 3-[ 8 F]-Fluoro-α-methyl--tyrosine; ; Inflmmtion; ; Dynmic positron emission tomogrphy Bckground The differentil dignosis of enign from mlignnt lesions y using positron emission tomogrphy (PET) is prolem tht remins unsolved ecuse 2-deoxy-2- [ 8 F]-fluoro-D-glucose ( 8 F-FDG) - the most frequently pplied PET proe for tumour imging - shows incresed uptke in severl enign pthologies such s inflmmtory foci, srcoidosis, nd ctive tuerculosis [,2]. To overcome this limittion, one promising * Correspondence: iid@suzuk-u.c.jp Deprtment of Bioimging Informtion Anlysis, Gunm University Grdute School of Medicine, Show-mchi, Meshi, Jpn 2 Fculty of Phrmceuticl Sciences, Suzuk University of Medicl Science, Minmitmgki-Cho, Suzuk, Mie , Jpn Full list of uthor informtion is ville t the end of the rticle pproch is the use of C/ 8 F-lelled mino cid PET trcers. In contrst to 8 F-FDG, mino cid trcers show lower uptke in mcrophges nd other inflmmtory cells [3] nd thus hve een evluted for their potentil to differentite etween enign nd mlignnt lesions, oth in niml models nd in ptients [4-6]. However, severl studies hve reported incresed uptke of mino cid trcers in inflmmtory lesions including rditioninduced necrosis [7] nd lymphdenopthy in srcoidosis [8]. Therefore, the use of mino cid trcers for the differentil dignosis hs yet to rech consensus. In contrst to other mino cid PET trcers, [ 8 F]- fluoro--α-methyltyrosine ( 8 F-FAMT) is selective for - type mino cid trnsporter (AT-) nd intercts less 205 Ymguchi et l.; licensee Springer. This is n Open Access rticle distriuted under the terms of the Cretive Commons Attriution icense ( which permits unrestricted use, distriution, nd reproduction in ny medium, provided the originl work is properly credited.

2 Ymguchi et l. EJNMMI eserch (205) 5:29 Pge 2 of 8 with other trnsporters [9]. In previous study tht evluted srcoidosis ptients with suspected mlignncy, 8 F-FAMT showed significntly lower uptke in srcoidosis lesions compred to tumour lesions, supporting the clinicl utility of 8 F-FAMT for the differentil dignosis [0]. However, one concern regrding the differentil dignosis with 8 F-FAMT is the possiility of flse negtive results, ecuse 8 F-FAMT shows reltively smll solute uptke, even in mlignnt tumours, which is occsionlly lower thn tht in srcoidosis. Therefore, n lterntive prmeter tht cn estimte differences in 8 F-FAMT uptke etween inflmmtion nd tumours is needed. ecently, Zho et l. [] reported the usefulness of dynmic PET imging of - C-methionine ( C-MET; the most frequently used mino cid trcer) for the differentil dignosis of grnuloms from mlignnt tumours, in rt models. This trcer exhiited significntly different dynmic profile in grnuloms compred to tumours. The success of dynmic PET using C- MET for the differentil dignosis rised the intriguing possiility tht 8 F-FAMT could e used s n lterntive mino cid PET trcer. However, the dynmic profile of 8 F-FAMT ws unknown, nd severl chrcteristics of 8 F-FAMT, such s the mechnism of trnsport nd metolism, could led to dynmic profile distinct from tht of C-MET. Therefore, in this study, we evluted the usefulness of dynmic 8 F-FAMT PET for the differentition of mlignnt tumours from grnuloms in comprison with 8 F-FDG in n experimentl rt model. Methods diophrmceuticls The synthesis of 8 F-FAMT ws performed t the Gunm University Hospitl (Cyclotron Fcility) s previously descried [2]. The rdiochemicl yield nd purity of 8 F-FAMT were pproximtely 20% nd 99%, respectively. The 8 F-FDG ws lso produced in the Cyclotron Fcility s previously descried [3]. Animl model All experimentl protocols were pproved y the ortory Animl Cre nd Use Committee of Gunm University. Seven-week-old mle Wistr King Aptekmn/hok rts (weight, 240 to 290 g; Jpn SC, Inc., Shizuok, Jpn) were used in ll experiments. We dopted the Mycocterium ovis cillus Clmette-Guérin (BCG)- induced intrmusculr grnulom model tht hs similr histologicl feture s srcoidosis [4]. The BCG strin of Jpn ( 0 7 colony-forming unit (CFU); Jpn BCG ortory, Tokyo, Jpn) ws suspended in 0.2 ml of phosphte-uffered sline [5], or llogenic rt gliom cells (C6, cells/0.2 ml) were inoculted into the left nd right clf muscles of the nimls to generte rt model ering oth grnuloms nd tumours. The C6 gliom cell line (CB2854) ws provided y the IKEN BC through the Ntionl Bioesource Project of the MEXT, Jpn. Dynmic PET study At 20 dys fter the inocultion of BCG nd 0 dys fter the inocultion of the gliom cells, rts (n = 6) were kept fsting overnight, nesthetized with isoflurne, nd injected intrvenously with 8 F-FDG (.7 ± 2.57 MBq). Dynmic PET (list mode cquisition) ws performed for 20 min with the hind leg region in the field of view y using n Inveon PET scnner dedicted to smll niml imging (Siemens Medicl Solutions USA Inc., Knoxville, TN, USA). The next dy, 8 F-FAMT (9.4 ±.9 MBq) ws injected intrvenously, nd dynmic PET ws performed ccording to similr protocol. The injection doses of 8 F-FDG nd 8 F-FAMT were determined sed on the hlf-life of 8 F (0 min) [] nd the tumour ccumultion levels of 8 F-FDG nd 8 F-FAMT. The dt were reconstructed nd corrected for ttenution nd sctter y using two-dimensionl filtered ckprojection. The imge mtrix ws , which resulted in voxel size of mm. The individul time sequence ws the following: 4 scns min, 3 scns 2 min, 4 scns 5 min nd 9 scns 0 min. For quntittive nlysis, imges were nlysed y mnully drwing volumes of interest (VOIs) in order to trce the contours of the grnuloms nd tumours without correction for prtil volume effects. The timectivity curves, sttic imges (50 to 60 min for 8 F-FAMT nd 8 F-FDG) nd the men SUVs in the lesions were clculted. The SUV ws determined y using the following eqution: SUV = ctivity in VOI (MBq/cc)/[injected dose (MBq)/ody weight (g)]. To further evlute the dynmic pttern of 8 F-FAMT uptke, the SUV rtio (SUV) ws determined. The rtio of SUVs of 8 F-FAMT t ech time point to tht t 2 min post injection (p.i.) ws clculted. The SUVs of 8 F-FDG were lso clculted from the SUVs t 20 min p.i. reltive to tht of 2 min p.i. Immunofluorescent histochemistry Prformldehyde-fixed (4%), prffin-emedded, 3-μmthick tumour nd grnulom tissue sections were stined with hemtoxylin nd eosin (H&E). Immunofluorescent stining of the djcent tissue sections ws lso performed ccording to stndrd protocol. Glucose trnsporter (GUT-) ws detected y using n nti- GUT- polyclonl ntiody (rit IgG, synthetic peptide, Acm, Cmridge, UK). AT- ws stined y using n nti-at- ma (rit IgG, synthetic peptide, Acm). The primry ntiodies were detected with the corresponding isotype-specific got nti-rit IgG H&

3 Ymguchi et l. EJNMMI eserch (205) 5:29 Pge 3 of 8 (Dyight 488, Acm). Adjcent tissue sections incuted with rit IgG insted of the primry ntiodies were used s negtive controls. Sttisticl nlyses epeted mesures nlysis of vrince ws used to ssess the significnce of differences in the dynmic ptterns of 8 F-FAMT nd 8 F-FDG uptke etween grnuloms nd tumours. A pired t-test ws performed to evlute the significnce of differences in SUVs nd SUVs. A two-tiled vlue of p < 0.05 ws considered significnt. esults Dynmic PET study epresenttive trnsversl dynmic imges of 8 F-FAMT nd 8 F-FDG re shown in Figure. The uptke of 8 F-FAMT grdully decresed in oth grnuloms nd tumours (Figure ). In contrst, the uptke of 8 F-FDG grdully incresed in oth lesions (Figure ). The time-ctivity curves of the men SUVs of 8 F-FAMT nd 8 F-FDG in ech VOI re shown Figure 2. In the tumours, 8 F-FAMT showed shoulder pek immeditely fter the initil distriution (6 to 5 min nd 2 min p.i., respectively), followed y grdul clernce, wheres in the grnuloms, 8 F-FAMT showed slow, exponentil clernce fter the initil distriution (2 min; SUV:.69 ± 0.25). The dynmic pttern of 8 F-FAMT uptke in the tumours ws significntly different from tht in the grnuloms or muscles (Figure 2, p < 0.00). The dynmic pttern of 8 F-FAMT uptke etween grnuloms nd muscles showed no significnt differences. The time-ctivity curves of 8 F-FDG in the grnuloms nd tumours exhiited similr ptterns nd showed no significnt differences (Figure 2). Sttic imges of 8 F-FAMT-PET nd 8 F-FDG-PET t 60 min fter dministrtion re shown in Figure 3,. Visul nd SUV ssessments of the sttic imges were unle to differentite tumours from grnuloms in ll cses, owing to overlps in 8 F-FAMT uptke, lthough the men SUV in the grnuloms (0.88 ± 0.2) ws significntly lower thn tht in the tumours (.00 ± 0.0, p < 0.00, Figure 3c). The sttic imges nd the men SUVs of 8 F-FDG in the grnuloms were similr to those in the tumours (tumour vs. grnulom: 4.25 ± 0.93 vs ± 0.59, p = 0.37, respectively, Figure 3d). epresenttive SUVs re shown in Figure 4. The SUVs of 8 F-FAMT in tumours were significntly min 3 min 6 min 5 min 25 min 30 min 50 min 70 min min 3 min 6 min 5 min min 30 min 50 min 70 min Figure Dynmic 8 F-FAMT () nd 8 F-FDG () imges in rts ering oth grnulom nd tumour. White rrow: loctions of C6 tumour (right) nd grnulom (left). 0.0

4 Ymguchi et l. EJNMMI eserch (205) 5:29 Pge 4 of Muscle SUV men Time (min) 6 5 SUV men Time (min) Figure 2 Time-ctivity curves of 8 F-FAMT () nd 8 F-FDG () in rts ering tumour nd grnulom. higher thn those in grnuloms (50 min p.i./2 min p.i., tumour: 0.72 ± 0.06, grnulom: 0.56 ± 0.05, p < 0.00, Figure 4), with no overlp etween 20 nd 00 min p.i.. The SUVs in the grnuloms nd muscles showed no significnt differences nd hd considerle overlp owing to similrities in the dynmic profile. However, the SUVs of 8 F-FDG in tumours were reltively higher thn those in grnuloms (20 min p.i./2 min p.i., tumour: 3.57 ±.23, grnulom: 2.7 ± 0.60, p = 0.022, Figure 4), lthough there ws sustntil overlp. Immunofluorescent histochemistry High expression levels of AT- were oserved in the tumours (Figure 5). In contrst, only fint expressions of AT- were oserved in the BCG-induced grnuloms (Figure 5d). High expression levels of GUT- were oserved on cell memrnes in oth tumours nd grnuloms (Figure 5,e). epresenttive imges of H&E stining for the tumours nd BCG-induced grnuloms re shown in Figure 5c,f, respectively. Discussion We found tht dynmic 8 F-FAMT PET is useful for differentiting grnuloms from mlignnt tumours in rt model. The moderte shoulder pek (6 to 5 min p.i.) nd prolonged clernce in the time-ctivity curves of 8 F-FAMT in tumours my reflect the high expression levels of AT- in mlignnt lesions s compred to grnulomtous lesions. The high expression levels of AT- were confirmed y immunohistochemicl stining. These results re consistent with previous clinicl studies tht showed correltion etween 8 F-FAMT uptke nd the expression levels of AT- [6-8]. Although SUV ssessment of 8 F-FAMT showed significnt differences etween grnuloms nd tumours, the SUV vlue lone could not relily provide the differentil dignosis in ll cses, ecuse the individul

5 Ymguchi et l. EJNMMI eserch (205) 5:29 Pge 5 of c SUV men Muscle d SUV men N.S. Figure 3 Sttic 8 F-FAMT () nd 8 F-FDG () imges in rts ering grnulom nd tumour. Trnsverse, coronl nd sgittl imges of 8 F-FAMT nd 8 F-FDG (50 to 60 min). White rrow: loctions of C6 tumour (right) nd grnulom (left). Individul vlues of SUV for 8 F-FAMT (c) nd 8 F-FDG (d) in grnulom nd tumour lesion (50 to 60 min p.i.). Significnt differences were determined (p < 0.005; N.S., not sttisticlly significnt). SUV vlues of tumours nd grnuloms overlpped sustntilly. It should e noted tht unlike clinicl study of srcoidosis ptients [0], in our grnulom model, 8 F-FAMT ccumulted in the grnuloms t 60 min p.i. Becuse the kinetics of 8 F-FAMT depends on oth incresed locl lood flow nd AT-, one possile explntion for this difference is the effect of the concentrtion of rdioctivity in the lood. However, even in the clinicl study, the SUVs of 8 F-FAMT in lung cncer lesions showed sustntil overlp with srcoidosis N.S. 7 * SUV (50 min/ 2 min) SUV (20 min/2 min) Tumor Muscle Figure 4 Individul vlues of SUV for 8 F-FAMT (50 min/2 min) () nd 8 F-FDG (20 min/2 min) (). Significnt differences were determined (*p <0.05;p < 0.005; N.S., not sttisticlly significnt). Tumor

6 Ymguchi et l. EJNMMI eserch (205) 5:29 Pge 6 of 8 GUT- AT- H&E c d e f Figure 5 Microscopy imges ( 40) of immunofluorescent stining of AT- (tumour (), grnulom (d)), GUT- (tumour (), grnulom (e)) nd H&E stining (tumour (c), grnulom (f)). White rrowhed: cncer cell; lck rrow: lymphocyte infiltrtion; white rrow: epithelioid cell grnulom. Brs indicte 50 μm. lesions nd ckground [0]. Becuse of the lower mximl SUVs, even in mlignnt lesions, the sensitivity of 8 F-FAMT is lower thn tht of 8F-FDG [8,9]. Thus, more definitive indictor tht cn improve the ccurcy of the differentil dignosis is needed. To ddress this issue, we evluted the SUV of 8 F-FAMT reltive to the SUV of 2 min p.i. nd found tht the overlp in SUVs diminished nd showed significnt difference in most of cquisition times (3 min p.i. to 20 min p.i.) ecuse of prolonged retention of 8F-FAMT in the tumours. The SUV ppered to depend on the existence of specific uptke, ecuse there were no significnt differences in the SUVs etween grnuloms nd muscle tissue where specific uptke ws sent. These dt suggested tht the dynmic profile of 8F-FAMT in mlignnt lesions could reflect AT--dependent specific uptke, regrdless of the mximl SUV. Therefore, we elieve tht SUV will e useful for differentil dignosis even if the mximl SUV is low. However, the clcultion points should e optimized for ech lesion, ecuse differences etween species or types of cncer might ffect the solute uptke or clernce rte of 8FFAMT. Therefore, it is worth performing clinicl study to investigte whether SUV mesurement cn improve the sensitivity of 8F-FAMT. As predicted, 8F-FDG showed comprle timectivity curve ptterns, SUVs nd expression levels of GUT- in tumours nd grnuloms. Although the SUVs of 8F-FDG in the tumours were slightly higher thn those in the grnuloms, there ws considerle overlp. Therefore, 8F-FDG my provide less relile informtion for the differentil dignosis, even if dynmic imging is performed. These dt support tht BCGinduced grnuloms could serve s proper model for the differentil dignosis of tumours from inflmmtion, s ws used in study of C-MET [2]. However, unlike C-MET, which tended to e retined in oth lesions fter the initil distriution, 8 F-FAMT showed slow, exponentil clernce from oth lesions. This difference might e ttriuted to the trnsport mechnism nd metolic pthwy of the trcers. Indeed, C-MET cn e sustrte for vrious trnsporters such s system, A, ASC nd y + [20,2]. Additionlly, following incorportion, C-MET is rpidly metolized nd trpped inside the cells [22]. These properties of C-MET my result in the retention of the trcer, oth in tumours nd in norml tissues. In contrst, 8F-FAMT is incorported into cncer cells solely vi AT-, which functions s idirectionl trnsporter with n oligtory exchnge mechnism [5,23]. The trnsport ctivity depends on the vilility of intrcellulr exchnge sustrtes with similr influx nd efflux selectivity. Once incorported, 8 F-FAMT remined intct in cells for up to 60 min, nd it ws metolized to protein to only smll extent [24]. These chrcteristics might cuse gentle decrese in 8F-FAMT in tumour cells long with decrese in the concentrtion of 8F-FAMT in plsm. However, regrdless of these properties, 8F-FAMT lso showed distinct dynmic profiles in tumours nd grnuloms s C-MET did. Thus our results implicte potentil wide pplicility of dynmic PET for the differentil dignosis, even for the other mino cid trcers tht show slow exponentil clernce from the tumours.

7 Ymguchi et l. EJNMMI eserch (205) 5:29 Pge 7 of 8 Tken together, dynmic 8 F-FAMT could e more relile imging method for distinguishing tumours from grnuloms, compred to conventionl sttic imges. Thus, dynmic 8 F-FAMT PET in ddition to stndrd 8 F-FDG-PET would increse the ccurcy of the differentil dignosis of mlignnt tumours from srcoidosis, rdition-induced necrosis nd tuerculosis. As dynmic 8 F-FAMT showed comprle results to C-MET, clinicl studies evluting the pplicility of dynmic mino cid PET for the differentil dignosis will e the ojective of future reserch. Conclusions The dynmic profile of 8 F-FAMT showed significnt differences etween tumours nd grnuloms. Additionlly, SUV of 8 F-FAMT diminished the overlp etween tumours nd grnuloms, which hs een oserved in SUV nlysis. These results indicte tht dynmic 8 F-FAMT nd SUV nlysis might compenste for current imging limittions nd help with improving the dignostic ccurcy of 8 F-FAMT. Competing interests The uthors declre tht they hve no competing interests. Authors contriutions YA, HT, SZ, KY nd IY prticipted in the design of the study. Dt cquisition ws done y YA, FY, MA, SK nd IY. Dt nlysis ws done y YA, IY, nd HnH. YA drfted the mnuscript. HnH nd IY revised the mnuscript criticlly. TH, HisH, nd TY contriuted regents/mterils/nlysis tools. All uthors red nd pproved the finl mnuscript. Acknowledgements We re grteful to Dr. Koji Kishimoto (Deprtment of Biochemistry, Gunm University Grdute School of Medicine) for kindly providing BCG nd to Mr. Shuji Senokuchi, Ms. Ski Inmoto (Fculty of Phrmceuticl Sciences, Suzuk University of Medicl Science) for excellent technicl ssistnce. Author detils Deprtment of Bioimging Informtion Anlysis, Gunm University Grdute School of Medicine, Show-mchi, Meshi, Jpn. 2 Fculty of Phrmceuticl Sciences, Suzuk University of Medicl Science, Minmitmgki-Cho, Suzuk, Mie , Jpn. 3 Deprtment of Trcer Kinetics & Bionlysis, Grdute School of Medicine, Hokkido University, 5 Chome Kit 8 Jōnishi, Spporo, Jpn. 4 Deprtment of Moleculr Imging, Grdute School of Medicine, Hokkido University, 5 Chome Kit 8 Jōnishi, Spporo, Jpn. 5 Deprtment of Prsitology, Gunm University Grdute School of Medicine, Show-mchi, Meshi, Jpn. 6 Advnced Clinicl eserch Center, Fukushim Medicl University, Hikrig-ok, Fukushim, Jpn. 7 Deprtment of Dignostic diology nd Nucler Medicine, Gunm University Grdute School of Medicine, Show-mchi, Meshi, Jpn. 8 Deprtment of Integrted Moleculr Imging, Grdute School of Medicine, Hokkido University, 5 Chome Kit 8 Jōnishi, Spporo, Jpn. 9 Centrl Institute of Isotope Science, Hokkido University, 5 Chome Kit 8 Jōnishi, Spporo, Jpn. eceived: 24 Ferury 205 Accepted: 8 April 205 eferences. rson SM. Cncer or inflmmtion? A holy gril for nucler medicine. J Nucl Med. 994;35: Endo K, Oriuchi N, Higuchi T, Iid Y, Hnok H, Miykuo M, et l. PET nd PET/CT using 8 F-FDG in the dignosis nd mngement of cncer ptients. Int J Clin Oncol. 2006;: Jger P, Vlurg W, Pruim J, de Vries EG, ngen KJ, Piers DA. dioleled mino cids: sic spects nd clinicl pplictions in oncology. J Nucl Med. 200;42: ee TS, Ahn SH, Moon BS, Chun KS, Kng JH, Cheon GJ, et l. Comprison of 8 F-FDG, 8 F-FET nd 8 F-FT for differentition etween tumor nd inflmmtion in rts. Nucl Med Biol. 2009;36: Stoer B, Tnse U, Herz M, Seidl C, Schwiger M, Senekowitsch-Schmidtke. Differentition of tumour nd inflmmtion: chrcteristion of [methyl- 3 H]methionine (MET) nd O-(2-[ 8 F]-fluoroethyl)--tyrosine (FET) uptke in humn tumour nd inflmmtory cells. Eur J Nucl Med Mol Imging. 2006;33: u FC, Weer WA, Wester HJ, Herz M, Becker I, Kruger A, et l. O-(2-[(8)F]fluoroethyl)--tyrosine (FET): trcer for differentition of tumour from inflmmtion in murine lymph nodes. Eur J Nucl Med Mol Imging. 2002;29: Tsuyuguchi N, Sund I, Iwi Y, Ymnk K, Tnk K, Tkmi T, et l. Methionine positron emission tomogrphy of recurrent metsttic rin tumor nd rdition necrosis fter stereotctic rdiosurgery: is differentil dignosis possile? J Neurosurg. 2003;98: Ymd Y, Uchid Y, Ttsumi K, Ymguchi T, Kimur H, Kithr H, et l. Fluorine-8-fluorodeoxyglucose nd cron--methionine evlution of lymphdenopthy in srcoidosis. J Nucl Med. 998;39: Wiriysermkul P, Ngmori S, Toming H, Oriuchi N, Kir K, Nko H, et l. Trnsport of 3-fluoro--lph-methyl-tyrosine y tumor-upregulted -type mino cid trnsporter : cuse of the tumor uptke in PET. J Nucl Med. 202;53: Kir K, Oriuchi N, Otni Y, Yngitni N, Sung N, Hisd T, et l. Dignostic usefulness of fluorine-8-lph-methyltyrosine positron emission tomogrphy in comintion with 8 F-Fluorodeoxyglucose in srcoidosis ptients. Chest. 2007;3: Zho S, Kuge Y, Yi M, Zho Y, Htno T, Mgot K, et l. Dynmic C-methionine PET nlysis hs n dditionl vlue for differentiting mlignnt tumors from grnuloms: n experimentl study using smll niml PET. Eur J Nucl Med Mol Imging. 20;38: Tomiyoshi K, Amed K, Muhmmd S, Higuchi T, Inoue T, Endo K, et l. Synthesis of isomers of 8 F-lelled mino cid rdiophrmceuticl: position 2- nd F-lph-methyltyrosine using seprtion nd purifiction system. Nucl Med Commun. 997;8: Hmcher KCH, Stöcklin G. Efficient stereospecific synthesis of no-crrierdded 2-[ 8 F]-fluoro-2-deoxy-D-glucose using minopolyether supported nucleophilic sustitution. J Nucl Med. 986;27: Zho S, Kuge Y, Kohnw M, Tkhshi T, Kwshim H, Temm T, et l. Extensive FDG uptke nd its modifiction with corticosteroid in grnulom rt model: n experimentl study for differentiting grnulom from tumors. Eur J Nucl Med Mol Imging. 2007;34: Zho S, Kuge Y, Kohnw M, Tkhshi T, Zho Y, Yi M, et l. Usefulness of C-methionine for differentiting tumors from grnuloms in experimentl rt models: comprison with 8 F-FDG nd 8 F-FT. J Nucl Med. 2008;49: Miyshit G, Higuchi T, Oriuchi N, Arisk Y, Hnok H, Toming H, et l. 8 F-FAMT uptke correltes with tumor prolifertive ctivity in orl squmous cell crcinom: comprtive study with 8 F-FDG PET nd immunohistochemistry. Ann Nucl Med. 200;24: Kir K, Oriuchi N, Shimizu K, Ishikit T, Higuchi T, Imi H, et l. Evlution of thorcic tumors with 8 F-FMT nd 8 F-FDG PET-CT: clinicopthologicl study. Int J Cncer. 2009;24: Kir K, Oriuchi N, Otni Y, Shimizu K, Tnk S, Imi H, et l. Fluorine-8- lph-methyltyrosine positron emission tomogrphy for dignosis nd stging of lung cncer: clinicopthologic study. Clin Cncer es. 2007;3: Inoue T, Koym K, Oriuchi N, Alyfei S, Yun Z, Suzuki H, et l. Detection of mlignnt tumors: whole-ody PET with fluorine 8 lph-methyl tyrosine versus FDG - preliminry study. diology. 200;220: Broer S. Amino cid trnsport cross mmmlin intestinl nd renl epitheli. Physiol ev. 2008;88: ngen KJ, Muhlensiepen H, Holschch M, Hutzel H, Jnsen P, Coenen HH. Trnsport mechnisms of 3-[ 23 I]iodo-lph-methyl--tyrosine in humn gliom cell line: comprison with [ 3 H]methyl]--methionine. J Nucl Med. 2000;4: Kuot, Kuot K, Ymd S, Td M, Tkhshi T, Iwt, et l. Methionine uptke y tumor tissue - microutordiogrphic comprison with FDG. J Nucl Med. 995;36:

8 Ymguchi et l. EJNMMI eserch (205) 5:29 Pge 8 of Ohkme H, Msud H, Ishii Y, Kni Y. Expression of -type mino cid trnsporter (AT) nd 4 F2 hevy chin (4F2hc) in liver tumor lesions of rt models. J Surg Oncol. 200;78: discussion Inoue T, Tomiyoshi K, Higuichi T, Ahmed K, Srwr M, Aoygi K, et l. Biodistriution studies on -3-[fluorine-8]fluoro-lph-methyl tyrosine: potentil tumor-detecting gent. J Nucl Med. 998;39: Sumit your mnuscript to journl nd enefit from: 7 Convenient online sumission 7 igorous peer review 7 Immedite puliction on cceptnce 7 Open ccess: rticles freely ville online 7 High visiility within the field 7 etining the copyright to your rticle Sumit your next mnuscript t 7 springeropen.com