Roberto Kalil Filho, Cicero Piva de Albuquerque
M agnetic resonance im aging in Chagas' heart disease
Heart Institute, Hospital das Clinicas, Faculdade
de Medicina da
Universidade de Sao Paulo - Sao Paulo, Brazil
M a n y im p o rta n t a s p e c ts o f C h a g a s ' h e a rt d is e a s e c a n b e s u c c e s s fu lly a s s e s s e d u s in g m a g n e tic re s o n a n c e im a g in g o f th e h e a rt. It is p o s s ib le to o b ta in w ith g re a t d e ta il th e a n a to m ic c h a ra c te riz a tio n o f th e c a rd ia c c h a m b e rs a s w e ll a s im p o rta n t in fo rm a tio n o f th e
fu n c tio n a l o r m e ta b o lic s ta tu s o f th e h e a rt. M a g n e tic re s o n a n c e im a g in g a fte r g a d o lin iu m in fu s io n s e e m s a ls o a p ro m is in g te c h n iq u e to o b ta in a b e tte r re g io n a l c h a ra c te riz a tio n o f m y o c a rd ia l tis s u e , a n d m a y b e im p o rta n t in th e n o n -in v a s iv e d ia g n o s is o f
a c tiv e m y o c a rd itis in p a tie n ts w ith C h a g a s ' h e a rt d is e a s e .
U N IT E R M S : C h a g a s ' d is e a s e . M y o c a rd itis . M a g n e tic re s o n a n c e im a g in g .
M
pow erfulagnetic resonancetool to increaseim agingthehasabilitybecom eof theaphysician to achieve a precise diagnosis in a
long series of different m edical specialties. Its non-invasive
nature as w ell as the lack of use of ionizing radiation are
now recognized advantages over other previously available
im aging techniques, m aking m agnetic resonance studies
an integral part of the m odern diagnostic arm am entarium .
C ardiology is no exception to this rule. T oday, through
the use of nuclear m agnetic im aging, it is possible to obtain
pictures w ith great anatom ical detail of the heart, aorta
Address for correspondence: Roberto Kalil Filho
Instituto do Cora9ao, Hospital das Clfnicas da Faculdade
de Medicina da Universidade de Sao Paulo
A v. Dr. Eneas de C~rvalho Aguiar, 44
Sao Paulo -S P -Brasil - CEP 05403-000
and other surrounding structures heretofore unavailable
to conventional radiology and echocardiography. M agnetic
resonance has also m ade possible to develop very
sophisticated analyses of m yocardial global and regional
function such as m yocardial tagging as w ell as the m ost
precise so far determ ination of m yocardial cham ber
volum es. U sing sim ilar technology and com m ercially
available N M R scanners it is also possible to gain insight
of m etabolic processes and pathw ays w ith the application
of nuclear m agnetic resonance spectroscopy. A ll these
techniques can be used to patients w ith heart failure of
any cause and in particular to patients w ith C hagas' heart
disease.
C hagas' heart disease is frequently associated w ith
chronic m yocarditis leading to heart failure, arrhythm ias
and sudden death (1,11). In experim ental studies, cardiac
m agnetic resonance im aging (M R I) proved to be a sensitive
m odality to detect interstitial edem a and'm yocardial
infiltration w i th lym phocytes, i ncl udi ng the
c h a ra c te riz a tio n o f c a rd ia c tra n sp la n t re je c tio n (4 ). A lso ,
in p re v io u s c lin ic a l stu d ie s w ith o u t th e u se o f
e n d o m y o c a rd ia l b io p sy , m a g n e tic re so n a n c e im a g in g h a s
b e e n u se d fo r th e d e te c tio n o f a c u te m y o c a rd itis. O n e
p re lim in a ry re p o rt su g g e ste d th a t m a g n e tic re so n a n c e
im a g in g c o u ld b e u se fu l fo r th e d ia g n o sis o f m y o c a rd itis
in in fa n ts a n d c h ild re n a n d c o u ld b e u se d a s a n a ttra c tiv e
a lte rn a tiv e m e th o d to e n d o m y o c a rd ia l b io p sy fo r th e n o n
-in v a siv e d ia g n o sis o f m y o c a rd itis in th is a g e g ro u p (5 ).
H o w e v e r, th e se p re v io u s stu d ie s d id n o t u se
g a d o lin iu m . In o u r o p in io n , th e u se o f g a d o lin iu m is
a sso c ia te d w ith a p o w e rfu l e n h a n c e m e n t fo r o f th e a b ility
o f m a g n e tic re so n a n c e im a g in g to d iffe re n tia te n o rm a l
fro m in fla m e d tissu e . G a d o lin iu m is a p a ra m a g n e tic
c o n tra st a g e n t th a t ~ a rk s a re a s w ith in c re a se d in te rstitia l
e d e m a th u s im p ro v in g th e a b ility o f m a g n e tic re so n a n c e
im a g in g te c h n iq u e s to d e te c t th e p re se n c e o f m y o c a rd ia l
in fla m m a to ry p ro c e sse s. T h e u se o f th is a g e n t m a y e x p la in
in p a rt th e h ig h se n sitiv ity o f M R I to d e te c t in fla m m a tio n
in C h a g a s d ise a se p a tie n ts. In a d d itio n , p re lim in a ry d a ta
su g g e st th a t m y o c a rd ia l re la x a tio n tim e s a n d th u s sig n a l
in te n sity a re n o t c h a n g e d in re g io n s o f m y o c a rd iu m in
p a tie n ts w ith c a rd ia c d ila ta tio n p e r se (6 ), w h ic h w o u ld
e x p la in th e u n c h a n g e d sig n a l in te n sity in o u r id io p a th ic
d ila te d c a rd io m y o p a th y p a tie n ts. M o re o v e r, m a g n e tic
re so n a n c e im a g in g w o u ld a p p e a r to h a v e c e rta in
a d v a n ta g e s in th e d ia g n o sis o f m y o c a rd itis in C h a g a s'
d ise a se , a s it is n o t o n ly n o n in v a siv e b u t m a y a lso b e
m o re re p re se n ta tiv e o f th e e n tire h e a rt th a n a b io p sy
sp e c im e n .
T h e d ia g n o sis o f m y o c a rd itis in C h a g a s' h e a rt d ise a se
h a s tra d itio n a lly b e e n b a se d o n th e re su lts o f in v a siv e
e n d o m y o c a rd ia l b io p sy o r n e c ro p sy (2 ,9 ). G e n e ra lly , th e
d ia g n o sis o f m y o c a rd itis is b a se d o n a n a to m o p a th o lo g ic a l
fin d in g s o r e n d o m y o c a rd ia l b io p sy re su lts. In v a siv e rig h t
e n d o m y o c a rd ia l b io p sy is th e g o ld sta n d a rd te c h n iq u e fo r
th e "in v iv o " d ia g n o sis o f th e m y o c a rd ia l in fla m m a to ry
p ro c e ss in h e a rt d ise a se s in g e n e ra l, a n d o f C h a g a s' h e a rt
d ise a se in p a rtic u la r (7 ). H o w e v e r, th e in v a siv e n a tu re o f
e n d o m y o c a rd ia l b io p sy m a y b rin g re c o g n iz e d lim ita tio n s
su c h a s m o rb id ity , c o st, p o ssib le c o m p lic a tio n s, d istre ss
fo r se q u e n tia l b io p sie s, a n d th e p o te n tia l fo r sa m p lin g e rro r,
w h ic h m a y c a u se lo w se n sitiv ity w h e n th e in fla m m a to ry
in filtra te is p a tc h y o r fo c a l (l D ).T h u s, th e re is a n e e d fo r
th e d e v e lo p m e n t o f n o n in v a siv e te c h n iq u e s fo r th e
d ia g n o sis o f m y o c a rd itis. M a g n e tic re so n a n c e im a g in g
h a s re c e n tly p ro v e d to b e a n e m e rg in g n o n in v a siv e
te c h n iq u e p ro v id in g c a rd ia c im a g e s w ith a h ig h sp a tia l
re so lu tio n to d e p ic t c a rd ia c a n a to m y a n d m o rp h o lo g y (3 ).
In c re a se d sig n a l in te n sity a sso c ia te d w ith in te rstitia l e d e m a
a n d in filtra tio n o f th e m y o c a rd iu m b y ly m p h o c y te s h a v e
b e e n d e m o n stra te d in a n im a l e x p e rim e n ts. T h e tissu e
a lte ra tio n s c a u se d b y m y o c a rd ia l in fla m m a tio n m a y in d u c e
a b n o rm a l sig n a l in te n sity o f th e m y o c a rd ia l w a lls, w h ic h
c a n b e d e te c ta b le in th e c lin ic a l se ttin g .
In a re c e n t stu d y , B o c c h i e t a I. d e sc ri b e d th e
c o rre la tio n b e tw e e n c a rd ia c m a g n e tic re so n a n c e ,
e n d o m y o c a rd ia l b io p sy re su lts, a n d G a lliu m -6 7 m y o c a rd ia l
u p ta k e fo r th e n o n in v a siv e d ia g n o sis o f m y o c a rd itis in
C h a g a s' d ise a se (3 ). T e n m a le p a tie n ts w ith
c a rd io m y o p a th y se c o n d a ry to C h a g a s' d ise a se , in
c o n g e stiv e h e a rt fa ilu re w e re stu d ie d . T h e p a tie n ts w e re
su b m itte d to rig h t v e n tric u la r e n d o m y o c a rd ia l b io p sie s,
c a rd ia c m a g n e tic re so n a n c e im a g in g , a n d G a lliu m -6 7
m y o c a rd ia l u p ta k e . T h e re su lts o f th is g ro u p w e re
c o m p a re d w ith a c o n tro l g ro u p o f p a tie n ts w ith id io p a th ic
d ila te d c a rd io m y o p a th y . A ll p a tie n ts w ith C h a g a s' h e a rt
d ise a se sh o w e d h ig h e r sig n a l in te n sity d u rin g m a g n e tic
re so n a n c e im a g in g a fte r a d m in istra tio n o f g a d o lin iu m .
A c c o rd in g to th e b io p sy stu d ie s, e ig h t C h a g a s' d ise a se
p a tie n ts h a d e v id e n t sig n s o f m y o c a rd itis a n d tw o o th e r
p a tie n ts h a d b o rd e rlin e e v id e n c e m y o c a rd itis. In
c o m p a riso n , o n ly o n e p a tie n t in th e c o n tro l g ro u p h a d a
h isto lo g ic d ia g n o sis o f b o rd e rlin e m y o c a rd itis, a n d n o
p a tie n t h a d e v id e n t m y o c a rd itis. G a lliu m -6 7 c a rd ia c u p ta k e
w a s p o sitiv e fo r m y o c a rd ia l in fla m m a to ry p ro c e ss in 7
C h a g a sic p a tie n ts a n d b o rd e rlin e in o n e . O n th e o th e r
h a n d , o n ly o n e p a tie n t in th e c o n tro l g ro u p h a d a n u p ta k e
th a t w a s p o sitiv e fo r in fla m m a tio n a n d o n e h a d a b o rd e rlin e
re su lt. In c o n c lu sio n , th e d a ta fro m th is stu d y stro n g ly
su g g e st th a t m y o c a rd itis is fre q u e n tly fo u n d in C h a g a s'
h e a rt d ise a se . C a rd ia c m a g n e tic re so n a n c e im a g in g a p p e a rs
to b e a n a c c u ra te a n d a lte rn a tiv e m e th o d fo r th e d ia g n o sis
o f in fla m m a to ry p ro c e ss a sso c ia te d w ith C h a g a s' h e a rt
d ise a se .
K a lil e t a I. (8 ) u se d re g io n a l c a rd ia c m a g n e tic
re so n a n c e im a g in g fo r th e a sse ssm e n t o f th e in fla m m a to ry
p ro c e ss in c h ro n ic C h a g a s h e a rt d ise a se . C a rd ia c sig n a l
in te n sity fro m th e se p ta l a n d fre e w a ll m y o c a rd ia l re g io n s
w a s c o m p a re d w ith th a t fro m sk e le ta l m u sc le b e fo re a n d
a fte r a b o lu s in je c tio n o f g a d o lin iu m . In c re a se d re la tiv e
sig n a l in te n sity w a s o b se rv e d in th e le ft v e n tric u la r fre e
w a ll a n d in th e se p tu m (F ig u re 1 ). T h e se fin d in g s sh o w e d
th a t m a g n e tic re so n a n c e im a g in g c a n n o n -in v a siv e ly d e te c t
th e p re se n c e a n d lo c a liz a tio n , a s w e ll a s a sse ss th e
h e te ro g e n e o u s n a tu re o f th e d istrib u tio n o f th e
in fla m m a to ry p ro c e ss in C h a g a s's h e a rt d ise a se .
T h e d e v e lo p m e n t o f im a g in g m e th o d s fo r th e
a c c u .ra te a sse ssm e n t o f a b n o rm a litie s in th e m y o c a rd iu m
o f p a tie n ts w ith k n o w n o r su sp e c te d C h a g a s' h e a rt d ise a se
m a y h a v e im p o rta n t th e ra p e u tic a n d p ro g n o stic
c o n se q u e n c e s. N u c le a r m a g n e tic re so n a n c e c a n
Figure 1 . A t y p ic a l e x a m p le o f a s h o r t a x is n u c le a r m a g n e t ic im a g in g v ie w o f t h e h e a r t a t t h e le v e l o f t h e p a p illa r y m u s c le s
a f t e r t h e in f u s io n o f G a d o lin iu m o f a p a t ie n t w it h C h a g a s ' h e a r t
d is e a s e a n d b io p s y p r o v e n s ig n if ic a n t m y o c a r d it is . N o t e t h e
g r e a t e r s ig n a l in t e n s it y o f t h e la t e r a l a n d p o s t e r io r w a lls o f t h e le f t
v e n t r ic le .
d e m o n s tr a te C h a g a s ' h e a r t d is e a s e m y o c a r d itis n o n
-in v a s iv e ly . A ls o , th e r e s u lts o f B o c c h i's s tu d y s h o w th a t
m a g n e tic r e s o n a n c e im a g in g m a y b e a n a ttr a c tiv e m e th o d
f o r d ia g n o s is o f m y o c a r d ia l in f la m m a to r y p r o c e s s in
c h r o n ic C h a g a s ' h e a r t d is e a s e w ith a f a v o r a b le
p e r f o r m a n c e w h e n c o m p a r e d w ith e n d o m y o c a r d ia l b io p s y
r e s u lts a n d G a lliu m - 6 7 c a r d ia c u p ta k e .
T h e h ig h in c id e n c e o f m y o c a r d itis in C h a g a s ' d is e a s e
p a tie n ts is in a c c o r d a n c e w ith o th e r p u b lic a tio n s w h ic h
s h o w e d th a t th e p r e s e n c e a n d p e r s is te n c e o f m y o c a r d ia l
d a m a g e b y in f la m m a to r y p r o c e s s a r e c o m m o n
m o r p h o lo g ic a l f in d in g s in c h r o n ic c h a g a s ic
c a r d io m y o p a th y ( 7 ,1 0 ) . I t h a s b e e n s h o w n th a t th e r e is a
h ig h p r e v a le n c e o f d if f u s e o r f o c a l c h r o n ic in f la m m a to r y
p r o c e s s , d if f u s e in te r s titia l f ib r o s is , d e g e n e r a tio n a n d
h y p e r tr o p h y o f c a r d ia c f ib e r in c h r o n ic C h a g a s ' h e a r t
d is e a s e ( 9 ) .
K a lil e t a I . a n d B o c c h i e t a I . r e p o r te d s till p r e lim in a r y
s tu d ie s w ith s m a ll n u m b e r o f p a tie n ts ( 3 ,8 ) . H o w e v e r , th e ir
r e s u lts a r e n o te w o r th y . T h e g o ld s ta n d a r d f o r v a lid a tio n
o f th e m a g n e tic r e s o n a n c e im a g in g te c h n iq u e o r f o r a n y
o th e r m e th o d u s e d f o r th e d ia g n o s is a n d d is tr ib u tio n o f
m y o c a r d itis s h o u ld b e th e r e a liz a tio n o f m u ltip le b io p s ie s
in m a n y s e g m e n ts o f th e h e a r t o r a p o s t- m o r te m
p a th o lo g ic a l e x a m in a tio n o f th e w h o le h e a r t, w h ic h w a s
c le a r ly n o t p o s s ib le . T h e a s s o c ia tio n o f e n d o m y o c a r d ia l
b io p s y , G a lliu m - 6 7 m y o c a r d ia l u p ta k e a n d m a g n e tic
r e s o n a n c e im a g in g in th is s tu d y is a n a lte r n a tiv e to im p r o v e
th e a n a ly s is o f th e r o le o f e a c h m e th o d .
I n s u m m a r y , m a g n e tic r e s o n a n c e im a g in g s e e m s to
b e a g o o d d ia g n o s tic m e th o d to d e te c t m y o c a r d itis in
c h r o n ic C h a g a s ' h e a r t d is e a s e . I ts u s e in th e d ia g n o s is o f
c h r o n ic C h a g a s ' h e a r t d is e a s e m y o c a r d itis is p r o m is in g
a n d it h a s th e p o te n tia l to b e a u s e f u l a lte r n a tiv e to
e n d o m y o c a r d ia l b io p s y . A n im p o r ta n t a d v a n ta g e o f
m a g n e tic r e s o n a n c e im a g in g is th e e a s e o f p e r f o r m a n c e
o f s e r ia l s tu d ie s a s m a y b e n e c e s s a r y in lo n g - te r m f o llo w
-u p . F -u r th e r o b s e r v a tio n s o n la r g e r n u m b e r o f p a tie n ts w ill
b e o f in te r e s t to c o n f ir m th e s e r e s u lts a n d d e te r m in e th e
s e n s itiv ity a n d s p e c if ic ity o f m a g n e tic r e s o n a n c e in th e
d e te c tio n o f m y o c a r d itis in c h r o n ic C h a g a s ' h e a r t d is e a s e
a n d d e f in e its r e a lis tic c lin ic a l r o le .
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ro le o f a c tiv e m y o c a rd itis in th e d e v e lo p m e n t o f h e a rt fa ilu re
in c h ro n ic C h a g a s ' d is e a s e : a s tu d y b a s e d o n e n d o m y o c a rd ia l
b io p s ie s . C lin C a rd io l 1 0 :6 6 5 -6 7 0 , 1 9 8 7 .
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-R e g io n a l c a rd ia c m a g n e tic re s o n a n c e im a g in g fo r th e
a s s e s s m e n t o f in fla m a to ry p ro g re s s in c h ro n ic h e a rt d is e a s e .
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9 . L A R A N J A , E S .; D IA S , E . & N O B R E G A , G . - C h a g a s ' h e a rt
d is e a s e : a c lin ic a l, e p id e m io lo g ic a n d p a th o lo g ic s tu d y .
C irc u la tio n 1 4 : 1 0 3 5 -6 0 , 1 9 5 6 .
1 0 . M IL E I, J .; S T O R IN O , R .; A L O N S O , G .P .; B E IG E L M A N ,
R .; V A N Z U L L A , S . & F E R R A N S , V . - E n d o m y o c a rd ia l
b io p s ie s in c h ro n ic c h a g a s ic c a rd io m y o p a th y . C a rd io lo g y 8 0 : 4 2 4 -4 3 7 , 1 9 9 2 .
II.R A H IM T O O L A , S .H . &H A G A , J .M . - C h a g a s ' h e a rt d is e a s e in th e U n ite d S ta te s . N E n g l J M e d 3 2 5 :7 6 3 -8 , 1 9 9 1 .
