Application of 64-Detector Computed Tomography Myelography in the Diagnostics of the Spinal Canal

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1 originl ppers Adv Clin Exp Med 2011, 20, 3, ISSN X Copyright y Wroclw Medicl University Brr Hendrich 1, Krzysztof Zimmer 2, Mciej Guziński 1, Mrek J. Sąsidek 1 Appliction of 64-Detector Computed Tomogrphy Myelogrphy in the Dignostics of the Spinl Cnl Zstosownie 64-rzędowej mielogrfii tomogrfii komputerowej w dignostyce knłu kręgowego 1 Deprtment of Generl nd Interventionl Rdiology nd Neurordiology, Chir of Rdiology, Wroclw Medicl University, Polnd 2 Deprtment of Trumtic nd Hnd Surgery, Wroclw Medicl University, Polnd Astrct Bckground. The most importnt imging modlity of the spine nd spinl cnl is mgnetic resonnce (MRI). In reltively lrge group of ptients with contrindictions to MR, the lterntive method is computed tomogrphy myelogrphy (myelo-ct). The development of multi-detector spirl CT, especilly 64-detector scnners, could potentilly increse the dignostic possiilities of myelo-ct. Ojectives. Evlution of usefulness of 64-detector myelo-ct in dignostics of the spinl cnl. Mteril nd Methods. Myelo-CT studies were performed with 64-detector CT scnner in 31 ptients (29 mles, 2 femles, ge 17 71, men ge 31.9). The ptients were referred with dignoses of rchil plexus injury (27 cses), spinl cnl stenosis (2 cses), suspected communiction with fluid spce in scrl region (1 cse), nd suspected intrspinl lesions fter verterl stiliztion (1 cse). A contrst medium (300 mg iodine/ml) ws injected into the durl sc vi sucoccipitl (14 ptients) or lumr (17 ptients) puncture. After tht, spirl cquisition (slice thickness mm, pitch 0.9) ws performed with 64-detector CT scnner, followed y multiplnr MIP (Mximum Intensity Projection) reconstruction. In 26 ptients, comprison with opertive results ws performed. Results. Among the 27 ptients with trumtic injury of the rchil plexus, nerve root lesions were reveled (pregnglionic rchil plexus injury) in 14 ptients, nd in 13 cses myelo-ct ws norml (postgnglionic injury). In the 4 ptients referred with dignoses other thn rchil plexus injury, myelo-ct contriuted to therpeutic decisions, e.g. of reopertion in the ptient with intrspinl hemtom, dignosed on the sis of the myelo-ct scn. In the 14 ptients with the fetures of pregnglionic rchil plexus injury in myelo-ct, we nlyzed C5-T1 nerve roots in detil on the side of the injury (overll 140 roots). We found lck of the outlines or continuity of 57 roots in 13 ptients. Intropertively, 53 roots were verified, confirming their injury in 49 cses (92.5%). Conclusions. 64-detector CT myelogrphy enles n efficient ssessment of the spinl cnl spce in ptients with contrindictions to MR, especilly visuliztion of nerve root injury (Adv Clin Exp Med 2011, 20, 3, ). Key words: myelogrphy, spirl computed tomogrphy, rchil plexus, spinl injuries. Streszczenie Wprowdzenie. Njwżniejszą metodą orzową kręgosłup i knłu kręgowego jest rezonns mgnetyczny (MR). U dość licznej grupy pcjentów z przeciwwskznimi do MR lterntywnym dniem jest mielogrfi tomogrfii komputerowej (mielo-tk). Rozwój spirlnej tomogrfii komputerowej wielorzędowej, w szczególności 64-rzędowej, udzi ndzieje n zwiększenie możliwości dignostycznych mielo-tk. Cel prcy. Ocen przydtności 64-rzędowej mielo-tk w dignostyce knłu kręgowego. Mterił i metody. Bdni mielo-tk wykonno z pomocą prtu 64-rzędowego, u 31 pcjentów (29 mężczyzn, 2 koiety, wiek 17 71, średnio 31,9 roku). Pcjenci yli kierowni z rozpoznniem uszkodzeni splotu rmiennego (27 chorych), stenozy knłu kręgowego (2 pcjentów), podejrzeni komunikcji z przestrzenią płynową w okolicy krzyżowej (1 pcjent), podejrzeni zmin wewnątrzknłowych po stilizcji kręgosłup (1 pcjent). Środek kontrstowy (300 mg jodu/ml) podwno do przestrzeni podpjęczynówkowej drogą nkłuci podpotylicznego (14 pcjentów) lu lędźwiowego (17 pcjentów). Z pomocą 64-rzędowego skner wykonywno kwizycję spirlną (gruość wrstwy 0,625 mm, skok spirli 0,9). Podczs postprocessingu uzyskiwno rekonstrukcje wielopłszczyznowe MIP (Mximum Intensity Projection). Przeprowdzono nlizę porównwczą z wynikmi śródopercyjnymi u 26 pcjentów.

2 352 B. Hendrich et l. Wyniki. Wśród 27 pcjentów z urzowym uszkodzeniem splotu rmiennego u 14 stwierdzono cechy uszkodzeni korzeni nerwowych (uszkodzenie przedzwojowe splotu), w 13 przypdkch z tej grupy orz mielo-tk ył prwidłowy (uszkodzenie pozzwojowe). U 4 chorych, u których mielo-tk zostł wykonn ze wskzń innych niż uszkodzenie splotu rmiennego, dnie to pomogło podjąć decyzje terpeutyczne, np. o reopercji u pcjent z rozpoznnym n podstwie mielo-tk krwikiem w knle kręgowym. U 14 chorych z cechmi uszkodzeni przedzwojowego splotu rmiennego w mielo-tk szczegółowej ocenie poddno korzenie nerwowe C5-Th1 po stronie uszkodzonej (łącznie 140 korzeni). Wykzno rk zrysu lu ciągłości 57 korzeni u 13 pcjentów. Śródopercynie zweryfikowno 53 korzenie, potwierdzjąc ich uszkodzenie w 49 przypdkch (92,5%). Wnioski. 64-rzędow mielogrfi TK pozwl n skuteczną ocenę przestrzeni wewnątrzknłowej u pcjentów z przeciwwskznimi do MR, zwłszcz uwidocznienie uszkodzeni korzeni nerwowych (Adv Clin Exp Med 2011, 20, 3, ). Słow kluczowe: mielogrfi, spirln tomogrfi komputerow, splot rmienny, uszkodzenie kręgosłup. The most importnt role in dignostic imging of the spine nd spinl cnl is currently plyed y mgnetic resonnce (MRI) [1 5]. This technique llows for comprehensive ssessment of the spinl cnl, vertere, interverterl discs, fluid spces within the cnl nd periverterl structures. However, there is still quite lrge numer of ptients in whom mgnetic resonnce cnnot e pplied due to contrindictions relted to ferromgnetic implnts nd stilizers, pcemkers etc. With this group of ptients other techniques my e pplied, especilly computed tomogrphy nd, in the cse of ssessment of fluid spces of the spine, CT myelogrphy [6]. With the development of multi-detector spirl computed tomogrphy nd especilly the introduction of 16-, or even 64-detector devices, which provide imging with sumillimeter resolution in ll plnes, the qulity of CT scns of different regions of the ody hs improved significntly [7 12]. This rises hopes for the incresed dignostic potentil of CT myelogrphy studies s well. In the Deprtment of Generl nd Interventionl Rdiology nd Neurordiology, School of Rdiology, Wroclw Medicl University, myelogrphic studies (MR myelogrphy nd CT myelogrphy) re performed routinely on ptients who require ssessment of posttrumtic injury of the rchil plexus. The modlity of choice is MR myelogrphy, n entirely non-invsive technique sed on strong T2-weighing which provides so-clled MR hydrogrphy, similr s in the cse of mgnetic resonnce cholngiopncretogrphy (MRCP) or MR urogrphy [13, 14]. In ptients with contrindictions to MR, CT myelogrphy is performed. Despite the development of digitl rdiogrphy, the previously pplied conventionl X-ry myelogrphy hs een lmost entirely ndoned [6, 15]. The im of the pper is to ssess the usefulness of 64-detector CT myelogrphy in dignostics of the spinl cnl nd especilly the verifiction of indictions to high resolution CT myelogrphy nd the definition of new stndrds of performnce nd ssessment of scns y 64-detector device. Mteril nd Methods Between Decemer 2007 nd Jnury 2010, CT myelogrphy ws performed with 64-detector scnner in 31 ptients (29 men nd 2 women), ged from 17 to 71 (men ge: 31.9). All the ptients hd contrindictions to mgnetic resonnce in most cses ferromgnetic components of frctured one unions. Injury to the rchil plexus with suspected tering of nerve roots from the spinl cord ws y fr the most frequent indiction to CT myelogrphy (27 out of 31 ptients). In two ptients the im of the exmintion ws to ssess the degree of spinl stenosis nd durl sc compression efore n opertion. In nother ptient the exmintion ws performed to ssess possile communiction etween pthologicl fluid spce in the scrl region nd the durl sc. In one cse the exmintion ssessed chnges in the spinl cnl erly fter surgicl stiliztion of the spine. Ptients were dministered ml of contrst medium of 300 mg of iodine/ml y suoccipitl (in 14 cses) or lumr (in 17 ptients) injection. The puncture site ws selected y neurordiologist fter ssessment of ntomicl conditions. The puncture ws done with 19G puncture needle guided y rdiogrphy in the Intervention Rdiology Section nd then the ptient ws tken to the CT Section. The ptients with lumr puncture were lid on one side with hips elevted for couple of minutes ( wedge-shped hip support ws used). Ptients who received contrst medium vi suoccipitl puncture were put on the computed tomogrphy tle immeditely. For scnning, they ly supine, rms long the trunk. A pilot scn of the section of the spine with the suspected lesion ws performed to define the re of interest. In the cse of ssessment of surchnoid spce in ptients with suspected ter of nerve roots from the spinl cord, the re of interest included the re etween mid C2 verter to interverterl spce T2/ T3. In the remining cses the scope of scnning depended on the clinicl prolem. Then, 64-de-

3 Appliction of 64-Detector CT Myelogrphy 353 tector scnner ws pplied to perform spirl cquisition (slice thickness mm, pitch 0.9, lmp rottion 0.5 s verge). Ech time, n utomted selection of lmp current ws pplied (intensity modultion). Rdition doses depended minly on the scope of the exmintion, rnging from 700 to 1500 DLP (Dose Length Product) (1000 DLP verge). Post-processing included multi-plne MIP reconstructions (Mximum Intensity Projection). The imges were ssessed in soft-tissue nd one windows. After the exmintion, the ptients were tken to clinicl wrd in supine position. In the cse of ptients fter lumer puncture, typicl indictions fter lumr puncture were pplied. Ptients fter suoccipitl puncture were dvised to remin in hlf-sitting position for 6 hours. In one ptient, wek post-puncture syndrome ws oserved nd ws treted in routine wy (supine position nd fluid therpy for 24 hours). In the remining cses no side effects were noted. The results were ssessed t AW4.4 working sttions. MIP reconstructions of trnsverse scns were nlyzed in t lest two windows: the soft tissue window nd close to the one window. In our opinion this is the est wy to visulize nerve roots ginst the contrsting cererospinl fluid. Coronl, sgittl nd olique MIP reconstructions were used for the est comprison of the helthy side nd the ffected one. Levels on which nerve root injuries were reveled were nlyzed in detil in trnsverse sections. Roots tht re comprised in the rchil plexus were ssessed, i.e ventrl nd dorsl C5, C6, C7, C8 nd T1 roots on the ffected side, dividing the rchil plexus into the upper prt (C5 nd C6 roots), medil prt (C7 root) nd lower prt (C8 nd T1 roots). Norml ppernce ws defined s n intct outline of roots, symmetric course of roots s compred to the contrlterl plexus, symmetric contours of the durl sc nd medil loction of the spinl cord within the durl sc. If lesions were detected in the CT myelogrphy, the direct fetures of the injury were ssessed, including lck of outline or continuity of the root nd displcement of the cord within the durl sc towrd the ffected side due to the drwing force ffecting the upper lim (vulsion injury) (Fig. 1, ). The imge of nerve roots on the ffected side ws ssessed y comprison to nerve roots on the sme level on the uninvolved side (Fig. 2, ). The ssessment concerned the presence of outlines of oth dorsl nd ventrl roots. If n outline of none of the two roots ws found on given level, the result ws clssified s ter of 2 roots. The ssessment lso concerned the loction of pseudocysts in reltion to the durl sc, interverte- Fig. 1. Ptient with symptoms of injury of the left rchil plexus. CT myelogrphy ( coronl plne, trnsverse plne) shows no outline of C7 nd C8 roots on the left nd smll pseudocyst on the C6/C7 level (), while on the opposite side ll roots re visile. Spinl cord is displced to the left nd slightly posteriorly () Ryc. 1. Pcjent z ojwmi uszkodzeni lewego splotu rmiennego. W mielo-tk ( płszczyzn czołow, płszczyzn poprzeczn) stwierdz się rk zrysu korzeni C7 i C8 po stronie lewej orz niewielką toriel rzekomą n wysokości C6/C7 (). Rdzeń kręgowy jest przemieszczony w lewo i nieco ku tyłowi ()

4 354 B. Hendrich et l. Fig. 2. CT myelogrphy, coronl plne: lck of outline of C6, C7, C8 nd T1 nerve roots on the left, smll pseudocyst of the T1 root. Trnsverse scn: lck of root contours on the left, durl sc compressed y pseudocyst Ryc. 2. Mielo-TK w płszczyźnie czołowej (): rk zrysu korzeni nerwowych C6, C7, C8, Th1 po stronie lewej, mł toriel rzekom korzeni Th1. Orz w płszczyźnie poprzecznej (): rk rysunku korzeni po stronie lewej, toriel rzekom ucisk worek oponowy Fig. 3. CT myelogrphy (two different ptients): two lrge pseudocysts on the C6/C7 nd C7/T1 levels in the spinl cnl nd interverterl formin, irregulr contours of the durl sc on the left Ryc. 3. Mielo-TK (dwóch różnych pcjentów): dwie duże toriele rzekome n poziomch C6/C7 i C7/Th1 w knle kręgowym i otworch międzykręgowych, nierówne orysy work oponowego po stronie lewej

5 Appliction of 64-Detector CT Myelogrphy 355 Tle 1. Results of CT myelogrphy nd correltion with intropertive findings Tel 1. Wyniki dni mielo-tk i zgodność z oceną śródopercyjną No. Initils (Inicjły) Age (Wiek) Lck of root outline (Brk zrysów korzeni) C5 C6 C7 C8 Th1 upper prt górn) Plexus injury (Uszkodzenie splotu) middle prt środkow) lower prt doln) Other disorder (Inn ptologi) stenosis (stenoz) numer of pseudocysts (licz pseudotorieli) spondylosis (spondylioz) trction nd spinl cord displcement (trkcj i przemieszczenie rdzeni) Conformity with intrprocedurl ssessment (Zgodność z oceną śródopercyjną) 1 ŁP 20 no ter Conformity 2 ŁJ 71 cervicl stenosis yes yes no dt 3 JA prtil conformity 4 CS yes no surgery 5 OP conformity 6 PK prtil conformity 7 KD conformity 8 CM yes conformity 9 DD 26 spinl stilistion conformity 10 GłM 60 ssessment of the spinl cnl yes no surgery 11 GrM 22 no ter conformity 12 WR yes prtil conformity 13 JR 36 no ter conformity 14 RP yes conformity 15 SK yes conformity 16 TM 47 no ter yes yes conformity 17 PZ 37 cyst in l-s section conformity

6 356 B. Hendrich et l. Tle 1. Results of CT myelogrphy nd correltion with intropertive findings (cd.) Tel 1. Wyniki dni mielo-tk i zgodność z oceną śródopercyjną (cd.) No. Initils (Inicjły) Age (Wiek) Lck of root outline (Brk zrysów korzeni) C5 C6 C7 C8 Th1 upper prt górn) Plexus injury (Uszkodzenie splotu) middle prt środkow) lower prt doln) Other disorder (Inn ptologi) stenosis (stenoz) numer of pseudocysts (licz pseudotorieli) spondylosis (spondylioz) trction nd spinl cord displcement (trkcj i przemieszczenie rdzeni) Conformity with intrprocedurl ssessment (Zgodność z oceną śródopercyjną) 19 J-ZA 19 no ter conformity 20 TD 28 no ter no surgery 21 LK prtil conformity 22 SS 59 no ter yes conformity 23 KJ prtil conformity 24 FM 45 no ter yes conformity 25 MR 32 no ter conformity 26 GruM yes conformity 27 BT 26 no ter conformity 28 ŻA 22 no ter conformity 29 FS yes no verifiction of the level of lesions 30 WR 50 no ter yes yes conformity 31 PJ 54 no ter conformity TOTAL

7 Appliction of 64-Detector CT Myelogrphy 357 rl formin, spinl cnl nd spinl cord s well s irregulr contours of the durl sc (Fig. 3,, c). Indirect evidence of ter of nerve roots from the spinl cord were considered, too, e.g. presence of pseudocysts nd irregulr contour of the cord [3, 4]. Other lesions within the cervicl spine were ssessed too, e.g. frctures, degenertive lesions, spinl cnl stenosis nd congenitl disorders. Out of the 31 ptients, 26 were operted on nd in these cses the results were compred to intropertive dt. Results Fig. 4. CT myelogrphy, olique () nd trnsverse () plnes, shows pseudocyst t the T1/T2 level on the left, ove, trction of the spinl cord towrd the interverterl formen is visile Ryc. 4. W dniu mielo-tk w płszczyźnie skośnej () i poprzecznej () n poziomie Th1/Th2 po stronie lewej jest widoczn toriel rzekom, powyżej stwierdz się przeciągnięcie rdzeni kręgowego w stronę otworu międzykręgowego The CT myelogrphy results for 31 ptients nd intropertive verifiction for 26 of them re presented in Tle 1. Among the 27 ptients referred to CT myelogrphy ecuse of unilterl injury to the rchil plexus, evidence of dmge to nerve roots ws found (pregnglionic dmge to the rchil plexus) in 14. In the remining 13 cses CT myelogrphy ws norml; in these cses, considering clinicl findings, the dmge ws ssessed s postgnglionic (peripherl). Twenty five ptients with trumtic injury of the rchil plexus were operted on in the Deprtment of Trumtic nd Hnd Surgery, Wroclw Medicl University. The opertions confirmed entirely the pregnglionic or peripherl dmge in 19 cses. In 5 ptients, prtil correltion ws reveled, i.e. ter of nerve roots ws confirmed ut the numer of ffected roots found during the surgery ws different thn dignosed y CT myelogrphy (more in 4 ptients nd less in 1 ptient). In 1 ptient (FS) the ter of T1 roots dignosed y CT myelogrphy (Fig. 4) ws not verified during the opertion ecuse there ws no surgicl revision of the T1/T2 interverterl formen due to difficult ccess. Complete conformtion of lesions reveled during the surgery nd dignosed y CT myelogrphy ws found in 2 ptients operted on for other resons: the surgeries confirmed respectively compression of the durl sc y hemtom fter stiliztion nd the presence of cyst in the scro-lumr spine. Fourteen ptients with symptoms of n injury to the rchil plexus nd lesions visile in CT myelogrphy underwent detiled evlution of the imge of dorsl nd ventrl nerve roots of the section from the C4/C5 to the T1/T2 interverterl formen on the ffected side (140 roots overll). Lck of the outline of nerve roots ginst the contrst medium nd lck of continuity or deformtion were found in 57 roots (13 in the upper plexus, 17 in the medium plexus nd 27 in the lower plexus). In 3 ptients (PK, JA nd SD) ter of single (dorsl) root ws dignosed with ventrl roots intct. The dt regrding intropertive ppernce ws otined for 53 roots. Injury to 49 roots ws found during the surgeries (92.5%). Thirty four pseudocysts were reveled with the most frequent loction within the spinl cnl, followed y interverterl formin (Figs 4 6).

8 358 B. Hendrich et l. Fig. 6. CT myelogrphy (coronl plne) shows pseudocysts locted inside the spinl cnl on C7/T1 nd T1/T2 levels nd very smll pseudocyst on the C6/C7 level; t the ltter level the outline of the root is visile Ryc. 6. W dniu mielo-tk (płszczyzn czołow) są widoczne toriele rzekome położone wewnątrzknłowo n poziomch C7/Th1 i Th1/Th2 orz rdzo dron toriel rzekom n poziomie C6/C7; n tym osttnim poziomie jest widoczny zrys korzeni Fig. 5. CT myelogrphy, sgittl () nd trnsverse () plnes, inside the spinl cnl, on the left, multiple pseudocysts re visile with tortuous outlines of nerve roots Ryc. 5. Mielo-TK w płszczyźnie strzłkowej () i poprzecznej (), wewnątrzknłowo po stronie lewej są widoczne liczne toriele rzekome z kręto przeiegjącymi zrysmi korzeni nerwowych Only one pseudocyst involved periverterl soft tissues. Usully the presence of cyst ws relted to lck of the outline of nerve roots in the spinl cnl (Fig. 7). In one ptient (JA), continuity of the nerve roots ws visulized in the lumen of pseudocyst (Fig. 8), ut during the opertion the roots were found to e torn. In the cse of ptient OP, lthough there ws no direct evidence of ter of nerve roots from the spinl cnl, multiple pseudocysts contining roots were found within the cnl. In 3 cses, further evidence of root injury ws visile without their ter, i.e. symmetricl course of roots within the durl sc s compred to the unffected side (in two cses the dignosis ws confirmed during the surgery, in one cse there ws no intropertive verifiction). CT myelogrphy lso llowed for the dignosis of other lesions in the cervicl spine. Evidence of degenertive process in the cervicl spine nd compression of the durl sc y spinl structures were found in 6 ptients (Fig. 9), spinl cnl stenosis in 3 ptients, Schmorl s nodes in 2 ptients, vcuum signs in the interverterl discs of 2 ptients nd verterl fusion (Klippel-Feil syndrome) in one ptient. Furthermore, 3 ptients were dignosed with other posttrumtic injuries thn root ter: frctures of ris, spinous processes, clvicle nd C6 verterl ody. In ptient DD, fter spine stiliztion surgery due to frcture, CT myelogrphy enled the discovery of hemtom tht ws compressing

9 Appliction of 64-Detector CT Myelogrphy 359 Fig. 7. CT myelogrphy (trnsverse plne) pseudocyst visile in the interverterl formen on the right, no outline of roots ipsilterlly Ryc. 7. Mielo-TK (płszczyzn poprzeczn) toriel rzekom jest widoczn w otworze międzykręgowym po stronie prwej, rk zrysu korzeni nerwowych po tej stronie Fig. 8. CT myelogrphy (coronl plne) shows nerve root in the lumen of n inferior pseudocyst. The root is ngulted in the distl section, during the surgery, root ter ws reveled Ryc. 8. Bdnie mielo-tk w płszczyźnie czołowej wykzuje w świetle niżej leżącej torieli rzekomej oecność korzeni nerwowego zgiętego kątowo w dystlnym odcinku, śródopercyjnie wykzno przerwnie korzeni Fig. 9. CT myelogrphy, sgittl () nd trnsverse () plnes, severe cervicl spondylosis, there is compression of the durl sc y osteophytes nd interverterl discs, with nrrowed lumen of the spinl cnl, there is gs in C4/C5 nd C5/C6 interverterl discs s evidence of degenertion of the discs Ryc. 9. Mielo-TK w płszczyźnie strzłkowej () i poprzecznej (), zwnsown spondyloz szyjn, widoczny ucisk n worek oponowy wywierny przez osteofity i krążki międzykręgowe orz zwężenie świtł knłu kręgowego, gz w krążkch międzykręgowych C4/C5, C5/C6 wyrz zwyrodnieni tych krążków

10 360 B. Hendrich et l. the durl sc: this ws the sis for the decision to operte second time. In 2 ptients (LJ nd GM) with dignosed spinl cnl stenosis, CT myelogrphy provided more ccurte ssessment of the lesions inside the cnl nd helped in decisions regrding therpy. In ptient PZ, CT myelogrphy excluded the suspected communiction etween the pthologic fluid spce in the scrl region nd the durl sc. Discussion The methodology of performing nd ssessment of CT myelogrphy pplied in our center is very similr to tht presented y Ymzki et l. [16], who used cervicl spine puncture from C1/C2 ccess in ll their ptients. In our institution, we pplied lumr puncture s frequently s suoccipitl puncture, thus ensuring dignostic contrst of the exmined section of the spinl cnl in ll cses. However, we chose higher concentrtion of the contrst medium (300 mg J/ml, compred to 240 mg J/ml used y the Jpnese uthors). Moreover, we performed the study with 64-detector device (compred to 16-detector device used y Ymzki et l), which llowed us to exmine similr section of the spine in much shorter time, thus reducing the rte of scns with rtifcts (especilly motion rtifcts). We used olique reconstructions to compenste for cervicl lordosis nd to otin symmetric imges of the cord nd roots on oth sides t the sme level. However, n ccurte ssessment required severl reconstructions. Ymzki et l. compensted for cervicl lordosis y positioning the ptients heds on pillow during the scnning nd they ssessed ventrl roots in the coronl plne nd dorsl roots in olique scns 20 30º from the coronl plne so s to otin n imge of dorsl roots on ll levels t one time. Similr to the Jpnese uthors, we oserved levels with one root usully the dorsl injured, while the ventrl root remined intct. We hve oserved more injuries in the lower plexus, which is consistent with the literture nd our previous reserch [3, 6]. In the cses of roots which hd een visile within pseudocysts in ptients JA nd WR, who were proven during their surgeries to hve injured roots or spinl nerves, it ws ssumed tht the ter hd to e locted right outside the pseudocyst where continuity of the nerve root could not e trced. We hve noted the presence of lesions within the contours of the spinl cord (ptients WR, RP): deformtion of the cord nd displcement towrd the injury, rising suspicion of such dmge s scrs nd firosis, mking it impossile for the spinl cord to return to the centrl position in the durl sc. These displcements were differentited from compression of the spinl cord y lrge pseudocysts locted within the cnl nd displcing the spinl cord contrlterlly. Avulsion of the cord towrd the ffecting force my led in rre cses to ulging of the spinl cord into the pseudocyst, cusing severe neurologicl chnges s in the cse descried y Tnk et l. [17], where cord hernition into pseudocyst cused Brown- Sequrd syndrome. A similr cse ws lso reported y Yokot et l. [18]. Penkert et l. [19] compred the results of MRI nd CT myelogrphy with surgicl dt fter lminectomy nd intrspinl lesion revision. In the rticle y Crvlho [1], ssessment of posttrumtic injury of the plexus ws lso performed fter lminectomy nd intrdurl revision of nerve structures. In our mteril, no revision of the spinl cnl ws performed, nd therefore some roots could e mistken for norml roots during the surgery, mening their continuity ws ctully interrupted within the cnl while the spinl nerve in the interverterl formen ws intct. Chow et l. [20] reported tht the presence of pseudocyst itself is not unequivocl evidence of n vulsion of nerve roots from the spinl cord. More relile evidence involves the lck of the outline of the nerve root in the pseudocyst. We hve confirmed this oservtion in our previous pper [6] nd in the current mteril, too. In some cses roots visile ginst pseudocysts were not interrupted (OP, CM), while in other cses the ter ws proly locted right outside the pseudocyst (JA). Menwhile, even recently, pseudocyst ws considered virtully the only symptom of root ter in CT myelogrphy. The present pper shows tht 64-detector CT myelogrphy with its potentil of producing very thin slices nd highqulity reconstructions enles direct visuliztion of nerve roots nd significnt improvement of dignostic effectiveness in injuries of the rchil plexus. The uthors concluded tht 1) 64-detector CT myelogrphy llows for the efficient ssessment of spinl cnl spce in ptients with contrindictions to MRI, 2) ppliction of 64-detector computed tomogrphy llows not only detection of pseudocysts ut lso direct ssessment of the continuity of prticulr dorsl nd ventrl roots, 3) in the evlution of CT myelogrphy results, one hs necessrily to consider compression nd displcement of the durl sc nd spinl cord, which my led to significnt neurologic sequele.

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