Magnetic resonance imaging characteristic of lymph nodes: Comparison of T1 and T2 weighted image in normal rabbits

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(1)³¤¥Èó. * F* a. (2004) 44 2 Korea J Vet Res(2004) 44(2) : 311~315. â*.~¶V«'ç~ßû&ÆöB5"5;'ç~jv. VcÁ"Æ*Á^;ÁJ;Áßs Á^Öã Á;ê× . . . BÞ&v >~"&, BÞ&v ~"& (²Òß: 2004j 4ú 25¢) 1. Magnetic resonance imaging characteristic of lymph nodes: Comparison of T1 and T2 weighted image in normal rabbits Ki-chang Lee, Min-cheol Choi*, Ho-jung Choi, Jung-hee Yoon, Seong-hong Choi1, Woo-kyung Moon1, and Jin-wook Chung1 College of Veterinary Medicine, Seoul National University, Seoul 151-742, Korea 1 College of Medicine, Seoul National University, Seoul 110-744, Korea (Accepteda April 25, 2004) Abstract : The detection of lymph node metastasis is an important step in tumor staging and is significant for therapy planning. It has been challenged to yield an appropriate image with diagnostic methods such as Magnetic Resonance (MR) and Computed Tomography (CT). Though CT has been used widely and accessed easily to show internal organs, it can hardly provide difference between lymph node and adjacent vessel or fat tissue. It has been well established that MR can reveal the subtle discrepancy within soft tissue. This study investigated the suitability of MR lymph node imaging without contrast enhancement by comparison of T1-weighted image (T1WI) and T2- weighted image (T2WI) in ten normal rabbits. According to the pulse sequence optimized from preliminary study, T1-weighted spin-echo (repetition time/echo time = 400/12 ms) and T-2 weighted fast spin-echo (repetition time/echo time = 3500/84 ms) images covering the hind limbs and pelvic region were acquired at 1.5 T. Two radiologists scrupulously evaluated the MR images in consensus. And signal intensity of lymph nodes was compared with that of adjacent fat. Statistical analysis showed that T1-weighted coronal image visualized the lymph nodes (iliac, superficial inguinal and popliteal lymph nodes) quickly and consistently rather than T2-weighted one. Conclusively, T1WI for evaluation of lymph nodes is moderately better than T2WI and appears to have potential for quick and sufficient mapping of the lymph nodes. In addition, this normal MR image of lymph nodes could be applied to further study for the evaluation of lymphatic system in abscess and tumor bearing animal model. Key words : T1-weighted image, T2-weighted image, lymph node, rabbit. B . .~ ¶V«'çzº " Ò²öB î BB>º 'B~ ï&ö ÒÏ>¾ [10, 11] ³· _f V æ 6"ö ~ B ·W â*. «&f «·ö ~ *W kW â*.Ã~ FZ¢ ê~V * [6, 13]ö ÷7>Ú ® . f &NB þf & ÆöB ô Úæ ®b "öº MRI 'B ¢ Ï *W â*.Ãj C&ÚV * &Æ~ â. MRI. ¶V«'ç(MRI)f jÛ' Ö> ¦ ç* &ê¢ ¾æÚ · .j 2b *Öz[R'F(CT)¾ .r2R'Fj &Ú~¾, CT¾ .r2R'FöB BÒB ®{ ÷æj . ;{~² ê "º º& ¦Ò ÏB [7]. â*. *Corresponding author: Min-cheol Choi College of Veterinary Medicine, Seoul National University, Seoul 151-742, Korea [Tel: +82-2-880-1278, Fax: +82-2-880-8662, E-mail: [email protected]]. 311.

(2) 312. VcÁ"ÆÁ^;ÁJ;ÁßsÁ^ÖãÁ;ê×. *. 'çzö & & ¢¦ > ® [6, 10]. ~æò *Òræ ;ç &Æ â*.~ MRI 'çö & ªÊ&(pulse sequence) . 5 ·f V~ â*. 'çzö & ¶ò& ~ öBº ÖF ;ç &Æ~ â*. 7 Ë(iliac), »fë(superficial inguinal) Ò J.(popliteal) â*.~ T1 ;'ç" T2 ;'ç~ ßû" jÞ '. ¶V«'çj áV * ªÊ&j &V~& .. 6¦V 56ræ U ê ¾*Ú 6>z~ jÎ>¦;öB sign test~&b 6 PACS(picture archiving and communication system) 'çöB ' â*. 1. Òò 5 O». ªç'b ; Ú~ v¢ z> ê ì þ ÿb ÒÏ~&. ÿb~ îº " j ÷Ï~ "G "Ò~ î~& ¶V «'çf öB Ò² j ÒÏ~& î B ÿbj f* *~B 5 ;'çj á î ¶V«'çf ¢ Ûb ~ ; 'çf Êföz V»j Ï~ > * öz* ¢ ; 'çf ³Êföz V»j Ï~ >* öz* ¢ ÒÏ~ áî áÚê 'çf v «~ O ÒF *^~& þ 6ë~ â*.~ &ê¢ &. 3 kg New Zealand White Rabbit 10 . Ketamine hydrochloride (Ketalar, Yuhan Yanghang, Seoul, Korea) 50 mg/kg Xylazine hydrochloride (Rompun, Bayer Korea, Seoul, Korea) 5 mg/kg . 1.5T system (Horizon; General Electric company, USA) head coil T1 T2 . FOV(Field of View): 16 cm, scan thickness: 2 mm, interscan space: 0 mm, matrix: 256x160, NEX(number of excitation): 2 T1 (spin echo, SE) / (repetition time, TR / echo time, TE) 400/ 12 msec , T2 (fast spin echo, FSE) / (TR/TE) 3500/ 84 msec .. Fig. 1. Axial images of iliac region. (A) T1-weighted (TR/ TE, 400/12 msec) and (B) T2-weighted (TR/TE:3500/84 msec) in a normal rabbit. Lymph nodes are not apparent on both images.. Fig. 2. Pelvic region of a normal rabbit. (A) T1-weighted (TR/TE, 400/12 msec) magnetic resonance image and (B) T2weighted (TR/TE, 3500/84 msec) image in the frontal section orientation. Relatively well-demarcated iliac medial lymph node is identified (arrow of A) compared to T2-weighted one (arrow of B). (C) Iliac medial lymph nodes along with vessel(open arrow) from a same rabbit, histologic specimen. Low activity of the lymph node without secondary follicles, cell-lined paracortex and medullary cords (hematoxylin and eosin stain, bar indicates 1 mm)..

(3) â*.~ ¶V«'ç~ ßû: &ÆöB T1" T2 ;'ç~ jv. .öB 7 æO" &j>º ^;ê(signal intensity) ¢ ®ÊÆÎb >~z~ paired student t-test ª C~& .. þÿbf ¶V«'çj áf êö B MR 'çöB &V â*.j Gn 5 ç ÷Ò'b jv &V~& . ÿböB 'ÂB â*.j 10% öÖ Ïö 48* ÿn ;Î Ê 2¢f : j ò Ú 1 mm *Ïb ÷Ò Ò¢¢ ò Ê H & E staining ~ *ã ¦Ò¢ ~& .. Ö ". &Æ â*. 'çz¢ * '~ ªÊ&f NEX ¢ Û b ~ T1 ;'çf Êföz»b. 2. 313. öB ;'çf ³Êföz »b öB '' '~ 'çj á j > ®î. ''~ 5 ;'çöB »(axial)" &ç j jv Ö" »öBº Ë â*.. ~ ;{ ¦' *~ 5 'çz& B& Úæ æ p~ (Fig. 1). ¾ &çöB ^ ¦*~ â*. Îv T1, T2öB &V &Ë~&b(Figs. 2,3,4) ' â *." 7 æO"~ &ê¢ ®ÊÆÎöB êG Ö" T1öB F~' &ê¢ ¾æî (p<0.001) (Table 1). ß® ª &Ë ÚJÚ Ë â*.fT1 ; 'çöB .&^f ª«~² ª>º â*. ^ *>º "* æOç" Â] &¢ Ú .&^ ¸² &V>º > T2 ;'çöB. TR/TE, 400/12 msec , T2 TR/TE:3500/84 msec . T1 T2 (coronal). Fig. 3. Popliteal lymph node (arrow) of a normal rabbit. (A) T1-weighted (TR/TE, 400/12 msec) magnetic resonance images and (B) T2-weighted (TR/TE, 3500/84 msec) image. Well-demarcated lymph node surround by fat is identified (arrow) on both T1 and T2-weighted images. (C) Popliteal lymph node from a same rabbit, histologic specimen. Low activity of the lymph node without secondary follicles, cell-lined paracortex and cell-poor medullary cords (hematoxylin and eosin stain, bar indicates 1 mm).. Fig. 4. Superficial inguinal lymph nodes (arrows) of a normal rabbit. (A) T1-weighted (TR/TE, 400/12 msec) magnetic resonance images and (B) T2-weighted (TR/TE, 3500/84 msec) image. Well-demarcated lymph node surround by fat is identified (arrow) on both T1 and T2-weighted images. (C) Superficial inguinal lymph nodes (arrow) from a same rabbit, histologic specimen (hematoxylin and eosin stain, bar indicates 1 mm)..

(4) 314. VcÁ"ÆÁ^;ÁJ;ÁßsÁ^ÖãÁ;ê×. Table 1. Signal Intensity ratio of lymph nodes over the adjacent fat intensity on T1-weighted and T2weighted T1-weighted image Iliac lymph node Inguinal lymph node Popliteal lymph node. 0.24* a 0.32 a 0.39 a. T2-weighted image 0.47 0.50 0.71. Signal intensity ratio; node signal / fat signal a ; p<0.001. º "* .& 5 "G^f FÒ 'çb ¾æ¾ ª «{~æ p~ (Fig. 1)(p<0.05).. V. ¶V«'çöB â*.f 'b æOö ~ ®b ¾ &V> .&" £² êB [3, 4, 8, 9, 12, 14]. â*.~ ¶V«'çöB~ ^ º ÒÏ~º ªÊ&ö V¢ ·~² ¾æ¾º & Ë V' 7º v >*" öz* j '.~² .~, ¶ ~º ¦*¢ ;B 6 ë~º TR/TE 500-600/20-30 msecj ÒÏ T1; 'ç(T1-weighted image, T1WI)öB â*.~ ^º " G º ;~ æO º £* Ô rJ^ ®. [7]. > TR/TE 2000/60-100 msec¢ ÒÏ T2;' ç(T2-weighted image, T2WI)öB â*.~ ^º " G º ;~, æO" FÒ T2;& â*.~ ^Ã&f jf~ ö V¢ æOö j z× z ; ^ ¾æÂ rJ^ ® [7]. *W â*. «&~ ãÖº T2WIöB «{ ^¢ ¾æÚV r ^ö â*. *~ ¦Âö MRI& Ö FÏ~ ß® Ò²öB *æË& ¦"öB CTº «&B â *." *ç#j ê~V ¦ ãÖ& ôV r^ ö MRI~ T2WI FÎ~ [2]. ~æò ¢>'b T1WI 'B¢ ÒÏ~æ pê â*." æO 5 . &ÒöB ¶Ê#² &Ë ±f &ê¢ ¾æÚ " º ªÊ& z× ^" .&ö ~ îçj ²z~ ß® Ô¾ 7ê~ ¶Ëj &ê MRVVö B Î"'¢ rJ^ ®b [7] «Ïÿ Ú~ â*.. f "* æOç~ T1 ^V r^ö T1WIöB £ ² ªB [5]. ;ç &Æ â*.~ T1WI 5 T2WIj jv þöBê ¢>'b rJê Ò " îR &æ T1WIöB &Ë ±f &ê¢ &V~ ·f â*.~ {öê 'Ã;Î" ì T1WI FÏ~ ² ÏF > ®rj ÝA ~& . ¯ T1WIöB Ë. â*." ? .& 5 æOçö ~ ·f â* .~ &ê& Ö> ©f æOç~ ^ö ~ ç&' &ê Ã&ö V Îæ T2 ; 'çöB iliac â*.~ &ê& T1 ;'ç ç &'b Ôf ©f "* æOç~ &^ö V ©b 6B . öB ÒÏB ªÊ & 7 T1WIöBº Êf öz(spin echo, SE)¢ ÒÏ~&º ¶V«'çöB V >º R'O»bB >* TR 5 echo * TE~ j '® æzÊº ©ö ~ 'ç~ z²³ê¢ ê Ï~² >ê æzÒ > ®. [2, 13]. T2WIöB ÒÏB ³Êföz(fast spin echo; FSE)º /³³jÃ;»(rapid acquisition with relaxation enhancement; RARE)~ ¢>' «bB ' öz *ö Ò÷7ªÊ& F¯B (Û 180ê). V¢ B, ' ¶ªÊö & >~ Êföz ªÊ¢ ³~ ''~ özº ¶Ë 5 z** ®¢ ' Ë 'b, çêf ^ & Çrj(signal-to-ratio)& ¸f 'çj áj > ® [1]. 'ç~ îöB z® Þ />º ^ & Çrj¢ ¸ îj BFÊº * O»bº 'ç ³* v V 6º ç ² º>æò, G;ö & Z·* J~, ¯ ^ö & Ç r~ 'Ëj *V * G;j ® ~º f ? *ç¦^ãÒ ~¾ö & B~ öz¢ áº æ¢ ¾æÚº >¢ ^ï²>(number of signal averages; NSA) 6º ¶>(number of excitation, NEX) ¢ [1, 2]. þöBº ^ & Çrj¢ ¸ 'ç~ îj ËçÊ¶ NEX 2¢ ÒÏ~& . Ö'b öBº ê'b &~ ®º & Æ â*.~ 'çz¢ * > Nf~ ªÊ & . j Û '~ ¯ NEX 2¢ Ûb ~ T1WI j * Êföz V»j Ï~ TR/TE: 400/12 msec ¢, T2WI¢ * ³ÊfözV»j Ï~ TR/TE: 3500/84 msec¢ áîb, ªÊ &j ÒÏ~ T1WI 5 T2WI ''öB &Ë &ê& Ö> â*. ~ ¶V«'çj áj > ®î . ß® ªç'b MR 'ç êöB " ÒÏ>º v , ¯ » ¾ çöB º &ç~ 'çz& FÒ F º â*. &N MR 5 B ªçöB Vº · æò 7º ~~¢ &æº Ë â*. *~ 2 k~ æ& >º .&ö é ~ *~~ ®º, &çöBº .& 5 â*. 6ëö FÒ~ê ¢ö ¾ >'>V r^î . Ëê *Ò Ú öB & ê¯> ®º &¦ ³· 5 «· F B &ÆöB ·W 5 kW~ â*. ÷æj ¶V«' çb ê~ ¾j& 'B¢ ÒÏ~ *W F.

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