The calvarium encasing the brain parenchyma is formed by the

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1 Dign Interv Rdiol 2007; 13:68-74 Turkish Soiety of Rdiology 2007 HEAD AND NECK IMAGING PICTORIAL ESSAY CT nd MRI findings in lvril non-infetious lesions Özlem Ylçın, Tülin Yıldırım, Osmn Kızılkılıç, Cem Erim Hürn, Zfer Koç, Volkn Aydın, Orhn Şen, Fzilet Kyselçuk ABSTRACT Differentil dignosis of the lvril lesions is importnt in order to deide whether iopsy, surgil intervention, or follow-up is required for further mngement. In this pitoril essy on lvril lesions, lyti or sleroti ptterns, ontours of the lesions, lifitions, soft tissue omponents, inner nd outer tle loliztions were evluted with omputed tomogrphy (CT). On mgneti resonne imging (MRI) signl hrteristis nd ontrst enhnement of the lesion, reltion to rin prenhym nd soft tissue were evluted. CT sn is onsidered to e the est exmintion to hrterize one ltertions wheres MRI depits one mrrow normlities nd invsion of djent tissues. Key words: lvrium omputed tomogrphy mgneti resonne imging From the Deprtments of Rdiology (Ö.Y. ylinozlem@ hotmil.om, T.Y., O.K., C.E.H., Z.K.), Neurosurgery (V.A., O.Ş.), nd Pthology (F.K.), Bşkent University Shool of Mediine, Adn, Turkey. Reeived 20 My 2005; revision requested 21 Mrh 2006; revision reeived 29 Mrh 2006; epted 10 April The lvrium ensing the rin prenhym is formed y the frontl, prietl, nd oipitl ones, s well s smll portion formed y the temporl ones. It onsists of 2 ortil lyers, the inner tle nd the outer tle, nd in etween those 2 lyers is the diploe, whih ontins one mrrow. Fol lesions of the lvrium my originte primrily from ony strutures, or they my e seondry to invsion of the skin- or rin-sed lesions into ony strutures. Welldefined orders nd sleroti mrgins re hrteristi of enign lesions. Slow-growing tumors led to thinning in the neighoring lvrium, wheres ggressive tumors led to drmti destrution. The first step in rdiologil evlution of the lvrium is plin rdiogrphy, where lesions might e evluted s lyti or sleroti. With omputed tomogrphy (CT), the nture of the lesion (i.e., lyti or sleroti), the presene of destrution in the inner or outer tle, lifition within the lesion, sleroti mrgins, nd the density of the lesion n e evluted (1 3). Mgneti resonne imging (MRI) is superior to CT in demonstrting erly lesions without one destrution, or those tht hve n ssoited soft tissue omponent nd prenhyml involvement. With MRI, the inner nd outer tles re seen s signl void. Intensity of the diploe vries with regrd to the ge of the ptient. During the first 2 dedes, the diploe is seen diffusely hypointense due to tive one mrrow in T1-weighted sequenes. After the seond dede, it is uniformly hyperintense due to ftty infiltrtion of the one mrrow. Within the hyperintense diploe, there my e pthy symmetri hypointensities. In MR sequenes tken fter ontrst mteril hs een dministered, dur surrounding Phionin grnultions nd diploi hnnels re enhned, nd in the remining res there is no enhnement. Most lvril fol lesions re hypointense on T1-weighted imges nd hyperintense on T2-weighted imges, nd they enhne with ontrst. During evlution of the diploe, T1- nd T2-weighted, nd ontrst-enhned T1-weighted imges should e ssessed together (4). Clvril lesions my e lssified s mlignnt nd enign, sed on their iologil tivity, or they my e lssified s ongenitl, tumorl, inflmmtory, or trumti, ording to their histopthologil fetures. In this pitoril essy, lvril lesions were lssified nd disussed s lyti, sleroti, or using one defets, ording to their CT fetures (Tle). Lyti lesions In hildren nd young dults, the differentil dignosis of solitry lyti lesions inludes eosinophili grnulom, epidermoid-dermoid, osteolstom, hemngiom, nd neurysml one yst. In older ptients with multiple lyti lesions, metstses nd multiple myelom should e onsidered. Vritions, suh s prietl formen, prietl thinning, nd Phionin grnultion, my mimi lyti lesions (3, 5). 68

2 Figure 1.. Eosinophili grnulom. Lterl skull rdiogrph () of 19-yer-old femle shows lyti lesion in the frontl one with nrrow trnsition zone. Axil CT imge () demonstrtes thinning in the inner nd outer tles. On oronl SE T1-weighted MR imge with ontrst (TR/TE, 500/12) (), the homogenously enhning lesion is shown to e rising from the diploe with durl invsion. Eosinophili grnulom Eosinophili grnuloms re most frequently loted in the prietl re nd re seen in ptients 5 15 yers old. They re hrterized y lyti lesion invding the inner nd outer tles Clssifition of lvril lesions ording to their CT fetures MULTIPLE LYTIC LESIONS SOLITARY Geogrphi pttern Histioytosis-X Sleroti rim (+) Epidermoid/dermoid Hemngiom Punh hole Multiple myelom Sleroti rim (-) Well defined Osteoporosis Eosinophili grnulom irumsript Pget`s disese Ill defined Osteohondrosrom Metstses Centrl lifition Lipom Button sequestrum Eosinophili grnulom Brest ner Osteomyelitis Epidermoid Defet in one Congenitl Trumti Itrogeni Ground-glss FOCAL Nodulr slerosis Cotton-wool SCLEROTIC LESIONS DIFFUSE Regulr inner tle: firous dysplsi Irregulr inner tle: introsseous meningiom Inner tle: eosinophili grnulom Durl meningiom Outer tle: osteom Pget s disese with well-defined orders. Peripherl slerosis is not seen unless the lesion is in the heling period. Residul one tissue, known s utton sequestrum, my e deteted in the lesion. This my e seen in rest ner metstses, epidermoid ysts, nd osteomyelitis s well. On MRI, they pper s soft tissue mss loted in the diploe, ppering hypointense in T1-weighted series, hyperintense in T2-weighted series, nd enhning homogenously. Durl invsion ours in ses of one invsion. Durl enhnement fter ontrst dministrtion my e seen. Epidermoid-dermoid yst, hemngiom, meningiom, nd osteolstom should e onsidered in the differentil dignosis. (3, 5) (Fig. 1). Clvril hemngiom A lvril hemngiom is solitry lesion seen mostly in middle-ged women. The most frequent type is vernous. This lyti lesion, whih ffets the outer tle, ut not the inner tle, might hve sleroti orders. The ony stritions rditing entrlly to the periphery of the lesion form sunurst or honeyom pttern, hrteristi feture of the lesion. On the other hnd, the sme pttern my e seen in meningioms, osteogeni sroms, nd osteolsti metstses. Intensity of the hemngiom on MRI vries; however, hyperintensity on T1-weighted imges is differentiting feture of the lesion (1, 6). Aneurysml one yst An neurysml one yst is rpidly-growing lesion seen exlusively in hildhood nd young dulthood. It is lyti lesion with well-defined orders nd is expnsile. It my hve multiloultions. Low nd high signl res demonstrted in MRI re due to lood Volume 13 Issue 2 CT nd MRI of lvril non-infetious lesions 69

3 Figure 2.. Metstsis. Axil CT imge () of 60-yer-old ptient with history of rest ner shows prietl lyti lesion. Sgittl SE T1-weighted () nd oronl TSE T2-weighted (TR/TE, 3500/100) () MR imges demonstrte fol lesion in the diploe nd ssoited prenhyml metstsis. Figure 3.. Metstsis. A ptient, who hd undergone surgery for thyroid ner 20 yers erlier, presented with the omplint of slowgrowing, pinless swelling in the rnium. Axil CT (), nd TSE T2-weighted (), nd SE post-ontrst T1-weighted MR imges () depit solitry metstti mss lesion in the right prietl one. The lesion destroys the inner nd outer tles. It is expnsile nd hs soft tissue omponent. It extends through the dur mter nd suutneous tissue, nd shows dense homogenous enhnement pttern. elements in different stges. Fluid-fluid levels in the yst nd smll ysts projeted in the lrger yst demonstrte sop-ule pperne (7). Dermoid/Epidermoid Epidermoid ysts re mostly loted in the prietl nd temporl ones of ptients ged yers. Lyti lesions with sleroti orders, they expnd to the inner nd outer tles. On MRI, they re hypointense on T1- weighted imges nd hyperintense on T2-weighted imges. They osionlly do not enhne fter ontrst dministrtion. Dermoid ysts re most ommonly seen in neworns nd infnts up to 3 yers old. They re mostly loted in the nterior fontnel. CT shows ft density nd lifition in the lesions, nd MRI demonstrtes signl heterogeneity (1 3). Lipom Lipoms re expnsile lyti lesions with well-defined mrgins. They my hve sleroti orders nd, due to ftty nerosis in the lesions, they my show entrl lifition. They pper s ft density on CT nd show typil ft signl on MRI (2, 3). Metstsis Metstses re mostly seondry to lung, rest, nd prostte ners in dults, nd re seondry to neurolstoms nd sroms in hildren. Clvril metstses re usully multiple nd osteolyti. Prostte ner metstses re usully sleroti or mixed type. Thyroid nd renl ell ner metstses re generlly sleroti nd solitry. On MRI T1-weighted imges efore nd fter ontrst dministrtion should e evluted together. Ares tht re seen s hypointense in ftty one mrrow on T1-weighted imges show enhnement following ontrst medium dministrtion. In the presene of known primry tumor, ssoited prenhyml metstses, nd multiple lyti lesions, lvrium metstses should e onsidered (1, 3) (Figs. 2 nd 3). Multiple myelom Multiple myeloms re the most frequently seen primry one lesions in dvned ges. The solitry form is plsmytom. It is lyti lesion loted oth in the inner nd outer tles with well-defined mrgins nd resemling punh holes. They re hypointense on T1-weighted imges, hyperintense on T2-weighted imges, nd they enhne fter ontrst dministrtion (1) (Fig. 4). 70 June 2007 Dignosti nd Interventionl Rdiology Ylçın et l.

4 Figure 4.. Multiple myelom. Lterl CT snogrm () of 64-yer-old femle demonstrtes lesion ner the vertex resemling punh hole ssoited with soft tissue omponent s well s mny other lyti rnil lesions. Prenhyml () nd one () window xil CT imges show punh hole lesions involving the inner nd outer tles throughout the rnium with n ssoited soft tissue omponent. Pseudomeningoele Pseudomeningoeles re the hernition of CSF or rin prenhym into the suutneous tissue due to postopertive one defet. Figure 5.,. Cephloele. Axil CT imges of mle neworn in the prenhyml () nd one () windows show defet in the oipitl region nd s extending through the suutneous tissue. Defets in one Lesions using one defets my e ongenitl (ephloele, sinus perirnii), trumti (leptomeningel yst), or itrogeni (pseudomeningoele). Cephloele Cephloeles re hernitions of rin prenhym due to ongenitl fusion defets. They re most usully seen in the oipitl region in neworns. They re lssified s meningoenephloele, meningoele, treti ephloele, nd glioele, sed on the neurl elements they onsist of. CT is essentil in demonstrting the one defet nd MRI is essentil in showing the s ontents nd ssoited ererl nomlies, if there re ny (1) (Fig. 5). Leptomeningel yst Leptomeningel ysts re lte omplition of hed trums tht our efore the ge of 3 yers. There re 2 different forms: growing frtures nd intrdiploi rhnoid ysts. There is durl ter in oth forms nd hernition of ererospinl fluid (CSF) or rin prenhym into the suutneous tissue. A growing frture is widening of the frture line >4 mm nd involves oth the inner nd outer tles. Intrdiploi rhnoid ysts erode the inner tle rther thn the outer tle. Dignosis of leptomeningel yst is mde in ptients with history of trum, one defet, presene of gliosis in neighoring prenhym, nd the presene of ysti lesions hving CSF hrteristi (8, 9) (Fig. 6). Sinus perirnii Sinus perirnii presents in neworns. It typilly expnds with n inrese in intrrnil pressure nd ompresses y diret pressure on the lesion. It is n norml onnetion etween durl venous sinuses nd extrrnil vsulr strutures. It is mostly loted in the frontl region, round the midline. It my e spontneous, trumti, or ongenitl in origin. CT demonstrtes n enhning lesion ner the defet in the inner or outer tle. On MRI, whih demonstrtes signl void res within the lesion, the ssoition of the lesion with intrrnil durl sinuses n e evluted. It enhnes homogenously (10). Sleroti lesions Pthologies leding to fol slerosis in the lvrium inlude firous dysplsi, osteom, meningiom, Pget s disese, sleroti metstsis, nd osteogeni srom (3). Firous dysplsi Firous dysplsi presents in young dults. On CT it most frequently demonstrtes ground-glss pttern. Rrely, there my e dense homogenous or ysti pttern. Signl intensity on MRI vries with regrd to the mount of firous tissue nd osseous mtrix in the lesion. The most frequent type is hypointense on T1- nd T2-weighted Volume 13 Issue 2 CT nd MRI of lvril non-infetious lesions 71

5 Figure 6.. Leptomeningel yst. Axil CT imge () of 63-yer-old mle with history of trum in hildhood demonstrtes erosion of the inner tle of left prietl one. Axil () nd oronl () TSE T2-weighted MR imges show one defet into whih there is hernition of rin prenhym nd ererospinl fluid. Figure 7.. Firous dysplsi. Anteroposterior skull rdiogrph () of 24-yer-old femle demonstrtes sleroti lesion in the right temporl one. Axil CT imge in one window () revels ground-glss pperne in the right temporl one. On xil SE T1-weighted MR imge (), hypointense expnsile lesion originting from the diploe is seen. whih re known s osteoporosis irumsript. In the osteosleroti stge, differentition etween the inner nd outer tles is lost nd the diploe widens. In mixed stge, irregulr res of slerosis demonstrte otton-wool pperne. MRI demonstrtes widening of the diploe nd heterogenous signl intensity (1 3). Figure 8.,. Osteom. Axil CT imge () of 45-yer-old femle demonstrtes welldefined fol slerosis originting from the outer tle of the right frontl one. Axil TSE T2-weighted () MR imge shows signl void lesion. imges, nd it enhnes intensely. Homogenous ground-glss pperne, expnsion onfined to the outer tle, nd no ffet on the inner tle re differentiting fetures (11) (Fig. 7). 72 June 2007 Dignosti nd Interventionl Rdiology Pget s disese Pget s disese presents with different rdiologil fetures in ll 3 of its stges. In the osteolyti stge, there re lyti lesions tht erode the outer tle Osteom Osteoms re solid nodulr sleroti lesions usully rising from the outer tle nd re usully <1 m. If they originte from the inner tle they my e misdignosed s osseous meningioms; however, unlike meningioms, osteoms do not hve soft tissue omponent, do not enhne, nd demonstrte signl void on ll MRI sequenes. Rrely, osteoms in the prnsl sinuses my enhne (2, 12) (Fig. 8). Ylçın et l.

6 of the lesion eses with puerty (13) (Fig. 9). Figure 9.,. Sleroti introsseous meningiom. Axil CT imges in the one window () nd ontrst enhned prenhyml window () of 45-yer-old femle show homogenously enhning lesion in the left side of frontl one djent to the oronl suture nd rising from the inner tle. A soft tissue omponent extending through the nterior rnil foss nd suutneous tissue is defined. Osteosrom An osteosrom is mostly primry tumor in hildren, wheres it is seondry to Pget s disese, firous dysplsi, hroni osteomyelitis, nd rdiotherpy in dults. Among ll 3 types, whih re osteolsti, firolsti, nd telngietti, the osteolsti type ours most frequently. CT my revel fol slerosis, ut it is usully destrutive. Minerliztion nd soft tissue mss in the tumor mtrix my e seen. It my demonstrte sunurst pttern. In order to differentite it from hemngiom, whih is enign lesion tht lso shows sunurst pttern, it should e onsidered tht osteosroms re ggressive, destroying the inner nd outer tles, nd hve irregulr ontours. Its MRI signl is heterogenous nd it enhnes heterogeneously (6, 14) (Fig. 10). Figure 10.. Osteosrom. Axil CT imges () in one nd prenhyml () windows nd oronl reformtted CT imge () of 28-yerold femle demonstrte lesion rising from the lterl wll of the orit extending to the temporl one, with destrution nd sunurst pttern. The lesion lso ontins soft tissue omponent. Introsseous meningiom Introsseous meningioms re most often loted ner the oronl suture. Their expnsion in ones nd groundglss pperne my e hrd to differentite from those of firous dysplsi. Nevetheless, meningioms usully present in middle-ged or dvned ged women, grow fter puerty, nd led to irregulrity in the inner tle, wheres in firous dysplsi, the inner tle is not ffeted nd growth Conlusion CT nd MRI re omplementry methods in determining the nture of lvril lesions. In dignosing lesions, ptient ge, history of trum or primry disese, lyti or sleroti nture, inner or outer tle involvement, enhnement pttern, presene of destrution or expnsion, nd the lesion eing solitry or multiple should e tken into onsidertion. A relevnt rdiologil pproh is essentil in the mngement of the lesion, whih inludes iopsy, surgery, nd follow-up. Referenes 1. Amrl L, Chiuriu M, Almedi JR, Ferreir NF, Mendonç R, Lim SS. MR imging for lesions of the rnil vult. Arq Neuropsiquitr 2003; 61: Burgener FA, Meyers SP, Tn RK, Zunuer W. Differentil dignosis in mgneti resonne imging. 1st ed. New York: Georg Thieme Verlg, 2002; Burgener FA, Kormno M. Differentil dignosis in onventionl rdiology. 2nd ed. New York: Georg Thieme Verlg, 1991; West MS, Russel EJ, Breit R, Sze G, Kim KS. Clvril nd skull se metstses: omprison of non-enhned nd Gd-DTPAenhned MR imges. Rdiology 1990; 174: Okmoto K, Ito J, Furusw T, Ski K, Tokiguhi S. Imging of lvril eosinophili grnulom. Neurordiology 1999; 41: Khnm H, Lipper MH, Wolff CL, Lopes MBS. Clvril hemngioms. Surg Neurol 2001; 55: Volume 13 Issue 2 CT nd MRI of lvril non-infetious lesions 73

7 7. Senol U, Krli K, Akyuz M, Tekinlp G, Tuner R, Lulei E. Aneurysml one yst of orit. AJNR Am J Neurordiol 2002; 23: Aıkgoz B, Tekkok IH. Posttrumti intrdiploi leptomeningel fistul nd yst. J Clin Neurosi 2002; 9: Ershin Y, Gulmen V, Plli I, Mutluer S. Growing skull frtures. Neurosurg Rev 2000; 23: Bigot JL, Ion C, Lepreux A, Dhellemmes P, Motte J, Gomes H. Sinus perirnii: dvntges of MR imging. Peditr Rdiol 2000; 30: Chong VFH, Khoo JBK, Fn Y. Firous dysplsi involving the se of the skull. AJR Am J Roentgenol 2002; 178: Arn E, Mrti-Bonmti L. CT nd MR imging of fol lvril lesions. AJR Am J Roentgenol 1999; 172: Dffner RH, Ykulis R, Mroon JC. Introsseous meningiom. Skeletl Rdiol 1998; 27: Bose B. Primry osteogeni srom of the skull. Surg Neurol 2002; 58: June 2007 Dignosti nd Interventionl Rdiology Ylçın et l.