Utility of chemical shift - MRI for anterior mediastinal mature teratoma

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1 R. MASUNO, t al : Chmial shift - MR imaging for miastinal matur tratoma 137 J. Tokyo M. Univ., 73 2 : , 2015 Utility of hmial shift - MRI for antrior miastinal matur tratoma Ryuhi MASUNO 1), Soihi AKATA 1), Jinho PARK 1), Jun MATUBAYASHI 2), Norihiko IKEDA 3), Kazuhiro SAITO 1) an Koihi TOKUUYE 1) 1) Dpartmnt of Raiology, Tokyo Mial Univrsity (R.M., S.A., J.P., K.T. an K.S), 2) Dpartmnt Pathology, Tokyo Mial Univrsity (J.M.) 3) Dpartmnt of Surgry, Tokyo Mial Univrsity (N.I.). Astrat Chmial shift - magnti rsonan imaging (CS - MRI) an tt mirosopi fat that annot tt y omput tomography (CT) or onvntional MRI. Th purpos of this stuy was to invstigat whthr antrior - MRI. Finings otain y CT, onvntional MRI, an CS - MRI on a total of 29 antrior miastinal ysti masss rst from 28 patints (9 matur tratomas, 20 othr ysts) twn Novmr 2005 an August 2012 at th Tokyo Mial Univrsity hospital wr analyz rtrosptivly. All MRI was prform using a T systm. All patints unrwnt axial rath - hol ual - ho squn. Th rptition tim was ms, whil ho tim was 2.38 (oppos - phas) an 4.76 (in - phas) ms. Th signal - intnsity inx of CS - - frns trmin twn two groups (matur tratomas an othr ysts). Tratoma was onfirm y a hang in signal on CS - MRI in two ass. On th othr han, no hang in signal was osrv in othr typs of lsion or th rmaining tratomas. Th Mann - Whitny U - tst rval a statistially signifiant iffrn twn th two groups (matur tratomas an othr ysts, P= 0.039<0.05). If th antrior miastinal ysti mass has a signal - intnsity inx of gratr than 20% on CS - MRI, a matur tratoma shoul iagnos, vn Introution Although most tratomas ar nign, malignant transformation os somtims our. Both nign an malignant tratomas may grow an ruptur or fistuliz with ajant struturs in th miastinum, or with th lung, plura or priarium 1). Most matur ysti tratomas show signifiantly low nsity in omput tomography (CT) as thy usually ontain fat. On magnti rsonan imaging (MRI), matur ysti tratomas ar sn with high signal intnsitis in oth T1 - wigh an T2 - wight imags 2)3) - ult to tt th fat omponnt in som tratomas y CT or onvntional MRI. Furthrmor, Mollr t al. 4) rport that almost 30% of tratomas o not xhiit fat on CT or MRI. Chmial shift - MRI (CS - MRI) an us to tt mirosopi fat that annot tt y CT or onvntional MRI. Thrfor, w valuat whthr antrior MRI. Matrials an Mthos Finings otain y CT, onvntional MRI, an CS - MRI on a total of 29 antrior miastinal ysti masss rst from 28 patints (9 matur tratomas, 20 othr ysts) twn Novmr 2005 an August 2012 at th Tokyo Mial Univrsity hospital wr analyz rtro- - Riv Novmr, 18, 2014, Apt January 14, 2015 Ky wors : hmial shift imaging, MRI, matur tratoma, miastinal tumor Corrsponing author : Ryuhi Masuno, Dpartmnt of Pathology, Tokyo Mial Univrsity, Nishi - shinjuku, Shinjuku - ku, Tokyo Japan TEL : Ext FAX : E - mail : wisruits@yahoo.o.jp 1

2 138 THE JOURNAL OF TOKYO MEDICAL UNIVERSITY Vol. 73 No. 2 sptivly. All lsions wr onfirm pathologially. Four tumors larly ontaining fat as on CT an onvntional MRI wr xlu. Thrfor, a total of 25 ass (5 matur tratomas an 20 othr ysts) wr inlu in th analysis. All MRI was prform using a T systm. All patints unrwnt axial rath - hol ual - ho squn. Th rptition tim rang was ms, whil ho tim was 2.38 (oppos - phas) an 4.76 (in - phas) ms. Th signal - intnsity inx (SII) on CS - MRI was otain for ah mass. Th SII was alulat as follows : [(SI in - SIopp ) / (SI in )] 100, whr SI in is th tumor signal intnsity on in - phas imags an SI opp is th tumor signal intnsity on oppos - phas imags. Matur tratomas wr iagnos whn th mass ha an SII of gratr than 20%. Th Mann - Whitny U - tst was us to trmin th statistial signifian of iffrns in SII valus twn th two groups (matur tratomas an othr ysts). A P - valu of lss than 0.05 was onsir to Rsults Two of th 5 tratomas show high SII valus, iniating tru positiv. Th 20 othr ysts wr all tru for iagnosing a matur tratoma using SII wr 100%. Furthrmor, th ngativ pritiv valu was Th Mann - Whitny U - tst rval a signifiant iffrn twn th two groups (matur tratomas an othr ysts, P=0.039<0.05). Figurs 1 an 2 show that a hang in signal y a hmial shift was onfirm in two of th tratomas. A slight rution in signal was osrv in on as, an a lar rution in anothr. On th othr han, no hang in signal was osrv in th othr typs of tumor (Figur 3) or in th rmaining tratomas (Figur 4). Disussion Primary grm ll tumors (GCT) of th miastinum ar rlativly rar an rprsnt approximatly 10% - 15% of miastinal tumors 1). Miastinal GCTs ar gnrally foun in aolsnts an young aults. Approximatly 80% of suh lsions ar nign, an most of ths nign lsions rprsnt tratomas 5) is haratristi of tratoma, ut iffrntiation oms Chmial shift - MRI is muh mor snsitiv than othr fat - supprss MR squns in tting mirosopi fat within tissu aus it rlis on uniqu iffrns in rsonan frquny twn protons in watr an thos in triglyri moluls 6). Chmial shift - MRI has alray n avoat as a mtho to stalish th iagnosis of arnal anoma, whih ontains various amounts of fat tissu, an to intify thymi tissu an hyprplasti thymus in arly aulthoo 7). Howvr, th usfulnss of CS - MRI for iagnosis of tratomas has not yt n rport. Thrfor, w invstigat whthr CS - MRI was usful in th iagnosis of tratomas. Sin w monstrat a statistially signifiant iffrn twn two groups of matur tratomas an othr ysts, w onlu that CS - MRI was usful in iagnosing tratomas. In this sris of ass, two of th tratomas prou a hang in signal in hmial shift imags. Howvr, no fat omponnt was larly onfirm in ithr as. Ration may our to forign mattr suh as hair or horn - lik matrial, or vn fat lak from nutrophils. Although thymoma an tratoma, whih o not xhiit any hang in signal in hmial shift imaging, also xhiit forign mattr ration, this os not nssarily iniat lakag of fat from nutrophils. Suh a forign mattr ration is mor likly to our in tratomas than in othr typs of tumor. Furthrmor, if th tumor also ontains hair or irt, suh a ration may strongr. Thus, iffrns Som tratomas may also xhiit malignant transformation, an oth nign an malignant tratomas may th miastinum, or with th lung, plura, or priarium. Thrfor, w liv that CS - MRI may linially usful in iagnosing ysti matur tratomas. Conlusion If th antrior miastinal ysti mass has a SII of gratr than 20% on CS - MRI, a matur tratoma shoul - ings ar intrminat. Tal 1. Rsults of analysis of signal - intnsity inx Snsitivity 40% (2/5) 100% (20/20) Positiv Pritiv Valu 100% (2/2) Ngativ Pritiv Valu 87% (20/23) 2

3 R. MASUNO, t al : Chmial shift - MR imaging for miastinal matur tratoma 139 Figur 1. Matur tratoma in 29 yar - ol woman. a : CT rval ysti tumor with apsul an sptum in antrior miastinum. : MRI in phas : oppos phas Signal intnsity (arrow) show a rution uring oppos phas. (SI in =227, SI opp =97, Signal intnsity inx=57.3). Tru Positiv. : Low - - osin [H - E] stain) rval yst wall, skin omponnt, saous glans, an srtion. : High - - osin [H - E] stain) rval foam lls an polykaryoa 3

4 140 THE JOURNAL OF TOKYO MEDICAL UNIVERSITY Vol. 73 No. 2 a Figur 2. Matur tratoma in 37 yar - ol woman. : MR imaging in phas : oppos phas Signal intnsity (arrow) show a rution uring oppos phas. (SI in =179, SI opp =35, Signal intnsity inx =80.4). Tru Positiv. : Low - - osin [H - E] stain) rval that wall of tumor mainly ompris matur skin an that ysts wr lin with iliat olumnar pithlium, suggsting prsn of ronhi. In this as, : High - - osin [H - E] stain) of part of tumor rval pling of 4

5 R. MASUNO, t al : Chmial shift - MR imaging for miastinal matur tratoma 141 a Figur 3. Thymoma (arrow) in 58 yar - ol woman. a : CT rval ysti tumor with apsul. : MR imaging in phas : oppos phas In this as, lin in signal intnsity of tumor uring oppos phas was wak. (SI in =129, SI opp =133, Signal intnsity inx = - 3.1). Tru Ngativ. : Low - - osin [H - E] stain) rval nrosis of tumor ntr, aroun whih was an aumulation of foam lls. : High - - osin [H - E] stain) of part of tumor. Componnt of vial thymoma an osrv on xtrior of tumor. Again, foam lls wr osrv aroun ara of nrosis. (sal : 200 5

6 142 THE JOURNAL OF TOKYO MEDICAL UNIVERSITY Vol. 73 No. 2 a Figur 4. Matur tratoma in 26 yar - ol man. No fat was shown. : MR imaging in phas : oppos phas Also in this as, lin in signal intnsity of tumor uring oppos phas was wak. (SI in =110, SI opp =105, Signal intnsity inx =4.5). Fals Ngativ. : Low - - osin [H - E] stain) rval that yst was fill with kratin. : High - - osin [H - E] stain) of part of tumor. Cholstrol lft, 6

7 R. MASUNO, t al : Chmial shift - MR imaging for miastinal matur tratoma 143 Rfrns 1) Taka S, Miyoshi S, Ohta M, Minami M, Masaoka A, Matsua H : Primary Grm Cll Tumors in th Miastinum. CANCER 97 : , ) E. Quint L : Imaging of antrior miastinal masss. Canr Imaging 7 : S56 - S62, ) Takagi H, Ihigo S, Muras T, Ika T, Imai A : Early iagnosis of malignant - transform ovarian matur ysti tratoma : fat - supprss MRI finings. Journal of Gynologi Onology 23 : , ) Uno T, Tanaka Y, Nagata M, Tsunoa H, Anno I, Ishikawa S, Kawai K, Itai Y : Sptrum of Grm Cll Tumors : From Ha to To. RaioGraphis 24 : , ) Mollr KH, Rosao - - Christnson ML, Tmplton PA : Miastinal matur tratoma : imaging faturs. AJR 169 : , ) Inaoka T, Takahashi K, Minta M, Yamaa T, Shuk N, Okizaki A, Nagasawa K, Sugimori H, Aurano T : Thymi Hyprplasia an Thymus Glan Tumors : Diffrntiation with Chmial Shift MR Imaging. Raiology 243 : , ) Takahashi K, Inaoka T, Murakami N, Hirota H, Iwata K, Nagasawa K, Yamaa T, ki Minta M, Aurano T : Charatrization of th Normal an Hyprplasti Thymus on Chmial - Shift MR Imaging. AJR 180 : , CT MRI hmial shift - MRI CS - MRI CT MRI CS - MRI MRI T systm ual - ho squn TR ms TE 2.38 oppos - phas 4.76 in - phas CS - MRI 2 CS - MRI Mann - Whitny U - tst P= 0.039<0.05 CT MRI CS - MRI hmial shift imaging MRI 7