Note: Descriptions are shown in the official language in which they were submitted.
~j WO 95/20405 2 ~ 8 2 2 ~ 3 . -,~ I /a
O~AL ~AGNE~IC PARTIC~E FORMUI.ATION
~ he present invention relates to magnetic resonance
imaging ~MRI) in general and in particular to compositions useful
as or in the preparation ~f MRI contrast media for imaging the
gastrointestinal system or other body cavities from which
contrast media may be discharged without passing through body
tissue .
The use of contrast agents for effective MRI of the
gastrointestinal tract is well ~st~hl; Ch~d. Both positive and
negative contrast agents ha~e been ~crrihed~ the latter agents
gener~lly containing ferromagnetic, ferrimagnetlc or
superparamagnetic particles. The~e particles are usually
po~rced in a liquid carrier to form a s~-zp~ncinn which is
ntct~red to the site of interest for imasing.
Among negative c~ agents, r-gnet;r~lly 5-1ccPrt;hl~
iron oxide ~NSIO) partic Les are attractive because they are
miscible with intestinal contents and are ef~ective at small
doses. NSIO agents are Superr'~ _ ~ ic and fe--l ~ ?ti c
agents which produce signal bl~r~n~n~ ~negative cnntr~st) by
creati~g a local distortion of the _ ti c field, resulting in
T2 r ~ Y lt; nn time shorten~ng.
Moderate magnetiic field distortion causes signal
h,l~rlr~-n;7l~ but excessive ~ n~t;c distortion can result in poor
imaging by causing magnetic susceptibi}ity artifacts (pixel
mismapping and image distortion). Excessive magnetic distortion
is usually caused by high particle conr~n~ration, but even at a
suitable cnnr~ntr~tiont excessive magnetic distortion can also be
caused by particle aggregation and f70rc~ tion, frequently seen
with s~cr~ncions ~such as MSIO suspensions) that are susceptible
to gravitational settling Since magnetic suiceptibility
artifacts cause distracting bright signals, interfere with
visualization of normal adjacent structures and induce
significant image ~lurring, they have limited the widespread
W095/20405 21~ 2 2 ~ 3 ~ c ~ lla
--2--
acceptance o~ MSIO contrast agents AccDrdingly, although
several ~SI0 contrast ag,~ts~ have recently been developed, they
have not been widely used:
In general, satisfactory distribution of the contrast
medium in the bowel loops is difficult to achieve due to both the
meandering configuration and tremendous surface area of the
region. Additionally, peristaltic ~ v~ -nt s can further affect
distribution. To overcome this problem, practitioners can use
high concentrations of magnetically responsive particles
su~ficient to produce the necessAry contrast effect throughout
the imaged zone, but this can cause the local concentration of
particles in the region to become so high that image distortions
akin to "metal artifacts" are produced. This is highly
undesirable as such artifacts might be mistaken for pathological
st U~LUL~:S and since the most important function of the contrast
medium in such imaging is to allow reliable differentiation
between the body cavity cr~ntA1n~ng the contrast medium and
pA~hr7o~;CAl structures in the body, particularly in the abdomen,
any such uncertainty seriously reduces the diagnostic value of
the t~rhn ~ que .
In short, while r-gneticAl ly responsive particles are
extremely effective in ~nhAnr; ng image contrast, several workers
have r~nrl ~ d that negative contrast media are of little value
or of less value than positive contrast media in abdominal
imaging .
Attempts have been made to formulate a product with
sufficient viscosity to ~-~ntA~n particle dispersion and still
avoid particle aggregation and flocc~lA~on. The problem is that
in order to achieve good images, the gastrointestinal tract must
be rn~ y filled which means that the patient must consume
large volumes of the bulky formulation. While dispersion of the
particles in the formulation is improved if its viscosity is
high, ingestion or infusion of large volumes of highly viscous
contrast media is difficult or impossible for the patient.
To overcome this problem, Nycomed (PCT/EP90/01196)
discloses a negative contrast medium which contains viscosity
"nhAnci n~ agents that reach full viscos~ty enhancing effect only
wo s~/2~40s ~ 1 8 2 .~ 1 ~ I ~ 11 . "
-3-
after administration In ~he Nycomed formulation the viscosity
enhancing agent is ' incompletely hydrated", meaning that it
reaches ~ull viscosity onl~ after exposure to aqueous media, such
as water or body fluids like gastric juices.
The problem with that approach is that if the product is
incomplètely hydrated, the active ingredient is not properly
distributed to yield s~perior MR-images upon ingestion.
Purthermore there is no proof that post-ingestion
distri~oution/hydration is complete or optimal, again jeopardizing
MR-image efficacy. In addition, preparation (reconstitution) of
granular product ~ust prior to dosing is subject to human error
which may result in improper concentration and thus may adversely
affect image quality.
What is needed, then, is the dev~l r - t of a ready-to-
use formulation which ensures complete hydration and consistent
dispersion of the active particles prior to dosing offers
superior MR-image efficacy and overcomes potential errors in
prer~ri?t ~ on .
Another problem es~countered with oral r ~~net 1 c particle
tO~5P) plepaLc-tlons is that on storage or ~.-~o:,ure to heat they
rapidly lose viscosity and develop calcing, thereby losing imaging
efficacy.
The paradigm for an efficient OMP is a good-imaging,
low-viscosity, fully hydrated, ready-to-use f. lAtiol~ that is
capable of uniformly dispersing the magnetic particles without
being so viscous that it is unpalatable. This formulation would
contain an appropriate dispersing agent in a sufficient amount.
If it is to be stored for long periods prlor to administration, a
useful feature, it must be preserved against microbial activity
and must resist caking that often occurs when active ingredients
and excipients settle and adhere to the walls of contni n-~rS. For
better patient compliance, it should preferably be as palatable
as possible which means, at the least, that the formulation
should mask the taste and color of the active metallic
ingredient. This would involve selecting appropriate sweeteners
and coloring agents which do not react with the metal particles
WO 95/20405 2 1 ~ ~ 2 1 3 11~- s `. ,~ ~
--4--
~ . ,
It would be hignly desirable to obtain such a
~ormulat ion .
Prior to this invention, attempts were made to overcome
the problem of imaglng artifacts and poor images obtained with
simple ~i.e. without thickeners) aqueous suspensions of
magnetically responsive particles. These efforts focused on
increasing the viscosity of the suspension.
We have found that to obtain high ~uality images, the
important feature of the suspension is not increased viscosity,
but rather, the ability of the carrier to r~-~ntA~n dispersion of
r~netirAl ly responsive particles to form a stable homogenous
suspension. Viscosity is important only to the extent that it
prevents ?~ . r~t~r)n or gravit~Ar1~nal settling of particles and
affords the fnrr-t~n and stability of a h~ cllc Sllcpencinn,
Accordingly, the present invention provides ~o 1 at 1 ons
for contrast media with viscosities as low as 25 to 465 cP which
produce high quality images . These rc 1 At ~ nnC suspend magnetic
particles very well for extensive periods of time without caking,
lumping or separation. Further, the product is substantially
hydrated at the time of -- Lion.
Thus, in one aspect of the invention there is provided
an aqueous carrier for dispersing magnetically responsive
particles, the carrier comprising one or more substantially
hydrated dispersion-~nhan~ ~ n~ agent .
The invention also provides a contrast medium comprislng
a suspension of magnetically responsive particles dispersed in a
subst Ant 1 A 1 1 y hydrated carrier .
Yet another aspect of the invention provides a ready-to-
use contrast medium which remains-unchanged after storage.
A method of generating a magnetic resonance image of a
human or ~nnl n body is also provided.
~1~2~1~
-- 5
Figure l represent~ four plots showing the relationship
between viscosity and signal intensity ratios.
Figure lA represents the T1-weighted Pulse sequence.
Figure lB represents the T2-weighted pulse sequence.
Figure lC represellts the proton density-weighted
pulse 6equence.
Figure lD represents all three pulse sequences
combined .
Figure 2 is a plot showing the viscosity values for
various formulations of the invention measured during
the course of study.
As uæed herein, the following terms shall have the
following meanings.
"Substantiall~ hydrated" means that one or more
dispersion Pn~ncPm~nt agents in the formulation are in
contact with water, such that a desirable viscosity is
achieved prior to patient dosing. A desirable viscosity
is one that is palatable, yet is capable of uniformly
dispersing the magnetic particles. While it is possible
that viscosity might increase during passage to the site
of interest, such increase is not critical for high
perf ormance .
"Magnetically responsive particles" relates to
particles having ferromagnetic, ferrimagnetic or
superparamagnetic properties. Such particles produce
blackening by creating local distortion of the magnetic
f ield, resulting in T2 relaxation time shortening .
3~ Magnetically susceptible iron oxide (MSIO) is exemplary.
"Ready-to-use" means that the product is capable of
being administered to the patient directly from the
package with no preparation other than mild shaking. No
diluting or reconstitution is required.
4r iL!~
~182213 ,,,J,~ ,[ /j
WO 95/20405 - 6 -
-OMP-' means ~ral magnetic Particles. indicating that
magnetically responsive particles have been added to a liquid
carrier to provide a suspension for oral consumption.
Carrier" means a chemical vehicle used to assist or
transport the active component to the desired anatomical site.
'Phantom" refers ~o a twin coaxial tube spparatus of
which the outer tube corJt~ns water and the inner tube contains
tr~ct medium. It is used for in-vitro ~ evaluation.
"Negative contrast agent" describes an agent which
contains materials whose effect of reducing the spin-spin
relaxation time tT2) of the imaging nuclei outweighs any T1
reducing effect and results in a re~ ct~n~ in MR signal intensity
from the body regions into which they distribute. Negative
contrast media g~ner~lly co~ltain f~:L.~ ~~net1c, f~rr;r-~n~tic or
Sllr~rp~, ~ 1C particleS-
Positive contrast agent" describes a paramagnetic
compound which shorten the spin-lattice relaxation time ~Tl) of
the imaging nuclel and s ~ result in an increase in image
~nt~nC;ty ln the body regions into which they distribute. One
such positive cu..L ~L agent is Gd DTPA.
"LVL~ denotes lowest viscoslty limit . Fo- 1 ~t 1 ons with
viscosities lower than the LVL are prone to gravitational
settling .
The present invention provides a fully hydrated, low
viscosity carrier which cont ~ ~ n.C one or more dispersing agents in
sufficient amounts to uniformly disperse magnetically responsive
particles. When suitable magnetically responsive particles are
s~sr~ncied in the carrier, the composition is a contrast medium
which affords high quality magnetic rf~snn~nr~ images.
Suitable dispersing agents are capable of dispersing
magnetically responsive particles under the physiological
conditions of the body cavity to be imaged and thus are
preferably of a non-biodegradable material, especially where the
composition is intended for oral ingestion. Dispersing agents
may conveniently be soluble in aqueous media to produce a viscous
solution. Examples of such materials include natural,
semisynthetic and synthetic high molecular weight substances such
2 ~ 8 2 ~ 1 3
~ WO 95120405 , . t
_ 7 _
as natural or semi synthetic gums and polysacchar~des, e g guar
gum, tragacanth, methylcellulose, hydroxypropylcellulose,
car~oxymethylcellulose, ~anthan gum, alginates and, where
applicable, their physiologically acceptable salts. Many
examples of such materials are known as thickening agents in the
food industry .
Alternative dispersion enhancing agents include
insoluble materials which swell in aqueous media to produce
viscous dispersions. Typical examples of such swellable
rllqr~r5i-~n ~nh~nring agents include clays, eg kaolin, and related
minerals such as, for example, magnesium aluminum silicate,
bentonite, etc. Mixtures of soluble and insoluble dispersion
-1 n~ agents can also be used
For administration into the GI tract, bulking agents
such as those used in the t 1 ~ of const~ r~t; cn such as bran,
psyllium and methylcellulc~se may also be used as dispersion
~nhs-nc~ n~ agents alone or in combination with other dispersion
~nh:~nc~ n~ agents .
Preferred ,i~ c~rs~ns agents include ca,L~ hylcellu-
lose sodium, hydroxypropylmethylcellulose, methylcellulose,
hyd o~yethylcellulose, I.ydLO-.y~L~ ~lcellulose, microcrystalline
l ose, carbomers, gum tr~7~ nth~ sodium alginate, gelatin,
pectin, polyvinylpyrrol$clone, guar gum, xanthan gum,
pregelatinized starch, locust bean gum, montmorillonite,
bentonite, hectorite, carr~geenan, starch, xylitol, sorbitol,
r~-nn~tol ~ and lactose.
The complete contrast agent of the invention comprises
magnetically responsive particles, the components actually
responsible for the negative MRI contrast, dispersed in the
carrier composition of the i~vention.
As mentioned above, many forms of magnetically
responsive particles have been proposed for use as M~I contrast
agents and generally speakin,g, all such particles may be used in
the carrier composition of t]~e invention. Thus the particles may
be free or may be coated by or ~ ~er~ in or on particles of a
non-magnetic carrier material, e.g. a natural or synthetic
polymer, for example cellulose or a sulphonated styrene-divinyl
~ ~D 21~2213
-- 8
benzene copolymer (see for example W0~3/03920 o~
Ugelstad). The magnetically responsive particles may be
Eerromagnetic or ferrimagnetic or may be sufficiently
small as to be superparamagnetic and indeed
superparamagnetic particles are generally pref erred.
Thus, the magnetically responsive particles used
according to the present invention may be of any material
which (although preferably non-radioactive unleæs the
particles are also; ntpnflpd to be detected by their
radioactive decay emissions) exhibits ferromagnetism,
ferrimagnetism or superparamagnetism. The particles may
conveniently be particles of a magnetic metal or alloy, eg
of pure iron, but particularly preferably will be of a
magnetic compound such as a ferrite, for example
magnetite, gamma ferric oxide and cobalt, nickel or
~ns~n~ce ferrites.
To avoid image distortion, it is pref erred that the
mean particle size of the magnetically responsive
particles be less than about 5 micrometers, preferably
less than 1 micrometer and that the overall size of the
non-magnetic carrier particles be 0.1 to 5 micrometers.
The magnetically responsive particles will generally have
mean particle sizes in the range 0 002 to 1 micrometers,
preferably O.OOS to 0.2 micrometers.
~ Where the magnetically responsive particles are
carried by carrier particles, these are preferably of a
material which is physiologically tolerable and which is
not biodegradable, at least in the environments it will
experience on the way to and at the body cavity being
3 0 imaged .
The compositions of the invention may, include
components other than the dispersion enhancing agent and
the magnetic particles. For example, conventional
pharmaceutical formulation aids such as wetting agents,
disintegrants, binders, fillers, dyes, osmoactive agents,
f lavoring agents and liquid carrier media . To improve
contact between the magnetically responsive particles and
the walls of the body cavity, e.g. the gut wall, the
composition3 may also contain mucoa&esives, such
h~ )r[) s~t~
2182213
01 wo 951~040!i ' I ~, I I ~.. ~ 5 . . I /:~
_9~
as for example a polyacrylic acid or a derivati~e thereof,
xanthan gum, etc.
The compositions of the invention are particularly
suited for use as MRI ~-ontrast media for imaging of the
gastroint~ct;n~1 tract and in particular for imaging the ~ o~
and the intestines. For such purposes the contrast medium may be
a~` ~n~ctered orally or rectally or by orally or rectally inserted
tubes. ~owever, as indicated above the contrast media are also
suitable for use in imaging other ~ t~rn~1 1y voided body cavities
such as the bladder, uterus and vagina.
When the composition is to be stored, as in the case of
ready-to-use preparations, package - ihility studies ~n~l~rate
that product containers composed of glass or polyethylene
terepthalate (PET) afford the greatest product Ch~l f l; ~e with
regards to preservation efficacy.
Thus, viewed from another aspect the present invention
provides the use of a physiologically tolerable dispersion
; ng carrier for dispersing magnetic particles in a
composition. The ~ t~6~tlr~n is suitable for use in magnetic
rPson~nre imaging.
Viewed from a further aspect, the present invention
provides a method of generating a magnetic resonance image of a
human or non , e.g, r~ 1~ An, sub ject in which method a
contrast medium comprising ~-7n~t~r~1 1y responsive particles in a
~isr~rsion ~nh:nrtn~ carrier is administered into an externally
voided body cavity of the subject (e.g. the gastrointestinal
tract), wherein said dispersion ~nh~nr; ng carrier acts to
increase the ~1 cr~rsion of the magnetically responsive particles
following ~ :n~ctration of said medium into the subject.
Viewed from a yet further aspect, the present invention
provides a packaged, substantially hydrated, ready-to-use
diagnostic contrast agent comprising a plurality of magnetically
responsive particles dispersed in a physiologically tolerable
dispersion ~nh~nri n7 agent.
In the method of tl1e invention the dose of the contrast
medium will generally be at least 500 mL for an adult human
subject and more usually 600 to llO0 mL, especially 750 to lO00
wo ssno40s 2 ~ ~ 2 2 ~ 3 ~1.. OC ~ /a
-~o-
ml. The content of the ma~netically responsive particles will
depend on the particular particles used. However, the particles
will generally be contained at a concentration of 0 . 01 to 10
g/litre, preferably 0.1 to 3 g/litre The dose may be taken in
portlons, e.g. for oral administration, about 2/3 being ingested
20 minutes before imaging and the ;'rèmainder being ingested
immediately before the subject is placed within the magnet (or
scanner) . ~ ~
The formulations for the dispersion ~nh;ln; ng carrier
and the contrast medium are shown ln Table I,
~WO 951~0405 2 1~ 2 2 ~ ~, P.~ a
l'able I
Carrie} for Dispersing Magnetic Particles
- Most Preferred
In~zredient General Preferred
*~Avicel CL-611 0.100-10.0 0.200-1.00 0.250-0.5Qo
Xantharl Gum 0.010-1.00 0.030-.300 0.050-0.250
Potassium Sorbate Q010- 1.00 0.050-.500 0.100-Q200
Sodium Benzoate 0.010 -1.00 Q050 - .500 Q100 - Q200
Saccharin Sodium 0.010-1.00 0.010-Q500 0.010-0.030
FD5cCYellowNo.6 0.001-.100 0.005-0.0500 0.009-Q020
FD8~C Red No. 40 0.001 - .100 Q005 - 0.0500 Q008 - Q015
FD8~C Blue No. 1 0.0001 - Q010 0.0005 - 0.005 0.001 - 0.00
pH lN HCl/
lN NaOH qs t*2.0 7.0 3.0 - 6.0 4.0 - 4.5
Contrast Medium (~ oF the Invention
(M ~netic Particles in the Cr,lrrierl
Most Preferred
InS~redient General Preferred
Q300 - Q550 0382 - 0.490 .400 - 0.485
Ma~netic Particles *100- 175 125-170 135-165
All units listed are to be taken as w/v, except * and * * .
* ~Lg Fe/mL
* * pH units
*** Avicel CL-611 c~nt~;nC microcrystalline cellulose and
carboxymethylcellulose sodium.
Wo 95/2040s ~!1 8 ~ 213 1 z ~ ~ /a
., ~,. ~....
The inventiOn is further illustrated by the following
non-limiting examples.
E xample 1
Preparation of 1 T;ter of OMP ~Arrier
Pre~ara~ ion of Disl~r.sion No . 1:
To 750 g of purified water heated to 70C - 80C in a
jacketed stainless steel or glass-lined manufacturing vessel, the
microcrystalline cellulose and ca I,o~S r hylcellulose sodium were
added and dispersed with vigorpus mixing and side scraper
agitation. With contin~lol~s mixing xanthan gum was slowly added
until it was wetted and completely dispersed. Temperature was
malntained at not less than 70C. The dispersion was then
cooled to 25C - 35C with c~ntin~l~rl side scraper ag~t~ti~n.
Pr~r~lrat~on of Slurry No.l:
To appro-r;r-t~ly 25 g of purified water in a stainless
steel or glass-lined r-nnfActllring vessel, the FD&C Red No. 40,
FD&C Yellow No. 6, and FD~C 81ue No. 1 were added and rli srersed.
Pr~p~ration of Solut~on No. 1:
To approximately 125 g of purified water in a stainless
steel or glass-lined r~nllfActl~rins vessel, the potassium sorbate,
sodium benzoate; and saccharin sodium were added and dissolved.
Slurry No. 1 above was then added and mixed until completely
di spersed .
Pre~Aration of FinAl Produ~t:
Solution No. 1 immediately abPve, was then added to
Dispersion No. 1 above, and mixed for 15 minutes, and then
brought to 95% of 1 liter (the desi red final weight (volume) )
with purified water and again mixed ~or not less than 10 minutes.
0 W0 9512040S - 1 3 - ~ 1 8 ~ 2 ~ a
The pH o~ the dispersion thl~ls obtained was ad j-~sted within the p~
range of 4.2 - 4.3, using lN Hydrochloric Acid and/or lN Sodium
Hydroxide and again mixed for not less than 10 minutes to ensure
uniformity. The dispersion viscosity was measured to ensure a
viscosity of 395 cP or higher. When necessary to increase the
viscosity, an additional 10% of the formula amount of Xanthan Gum
was slowly added with continuous mixing for not less than 15
minutes. The dispersion W.lS then screelled throught a 100 mesh
st~1nl~s~ steel sieve, into a tared stalnless steel or glass-
lined mixing vessel.
Example 2
Prei?~ration of Contract Agent
A homogenous suspension of magnetically responsive
particles was prepared by inversion mixing of the active
ingredient tMSIO from Nycomed) for not less than 1 hour until it
waS cnnf ' ~ that all so:Lids were ~-lcp~ncl~r, A calculated
amount of MSIO to achieve a total iron concentration of 150
mcgFe/mL was slowly added with stirring to the OMP carrier
described in Example 1 hereinabove. Stirring continued for not
less than 15 minutes. ~he weight (volume) of the final
SllcrenC~nn was ~ t~-rm~ne~l ar,d if nec~s~ry adjusted to the final
weight (volume~ (1 liter) with purifled water. Slow mixing
c~-nt~nl-~cl for not less than 10 minutes to ensure uniformity. The
final product was adjusted with lN Hydrochloric Acid and~or lN
Sodium Hydroxide to a pH range of 4.2 - 4.3.
Evalll~tion Qf Prerl~red r~lntr~t Aa~nts
In vitro and In Viwo evaluations of the contrast agent
of the invention were carried out as follows.
Contr~ct Aqents
The active ingredient in the contrast media used in the
examples is MSIO (supplied by Nycomed AS, Oslo, Norway)
consisting of monodisperse 3-4 ~lm polymer part:icles coated with
Wo 95/20405 2 ~ ~ 2 2 1 3 ! ~ 1 4 r~1/. l7~ ~
approximately 50 nm particles o~ iron ~errite (Described i~.
Norwegian Patents 142022; 143403; and 155316).
Three formulations shown in Table 2 and two formulations
in Table 3 were prepared with an lron concentration of Nycomed's
MSIO at 125-150 ,Ug/mL, and a viscosity of 156 cP to 430 cP.
Xanthum gum was used to control- product viscosities.
The L-type formulations (Ll, L2, L3) shown in Table 2
are the ready-to-use preparations of the invention described
hereinabove . The G-type formulations (G1 and G2 ) shown in Table
3 differ from the L-type in composition and, further, are
prepared from a granular c~lncr~ntrate reconstituted with water
just prior to administration. The G-type preparation represents
the prior art.
,l~n~l Prf~ration
The animals for in vivo studies were mongrel dogs
anaesthetized with 2% Surital~{ I.V. (Thiamylal Sodium by Parke
Davis) titrated to ~ntAin light AnAPs~h~siA~ To deliver O~P, a
nasogastric tube was inserted into the stomach of the animals and
they were positioned in the MR scanner in the supine position.
~R T~in~
In Vitro Evaluation: In vitro MR imaging, which was
obtained using a Signa (GE Medical Systems, Milwaukee)
~u~e~ n~ magnet system oper~A~t~n~ at 1.5T, was performed on
r~nt~ - contA~n1n~ 20 mL of WIN 39996 samples ~ Ately after
manual shaking. A head coil and conventional 2DFT spin-warp
technique were used. Multi-section axial acquisitions were
tAinf~ with a 24 cm field of view, 256x256 imaging matrix, 7 mm
section thickness, and 3 mm intersecton gap. Pulse sequences
used were T1-weighted (TR/TE; 300/15 msec, 1 excitation), T2-
weighted (2000/70, 1), and proton density-weighted (2000/20, 1).
In Vivo Evaluation: In vivo MR imaging, which was
obtained using the same MR unit described above, was performe~
using the head coil and conventional two dimensional Fourie-
WO 9~;12040S ~ 1 8 2 ~ f ~ I ~ I I VD9_ r ~ 1 /a
0~ _15_
Transform (2DFI`) spin-warp technique. Multi-section axial
acquisitions on the abdome~n were obtained with a 25-30 cm field
of view, 128x256 imaging matrix, 7 mm section thickness, and 3 mm
intersection gap. Pulse sequences used were Tl-weighted (TR/TE
300Jl5 msec, 4 excitations), T2-weighted ~2000/70, l), and proton
density-weighted (2000/20, 1).
Visco~tv M~
All viscosity measurements were made at 25C using a
Brookf~e1d RVTDV-II Viscometer operatlng at lO rpm with a No. 2
spindle. All viscosity val~les are reported in centipoise (cP).
Statict1~ n~lvsis
The ;nfll~pncc~ of viscosity on imaging qualitles were
studied by F.7r~min~n~ the "Signal Intensity ratios vs. viscosity"
plot (Figure l) . Data wère obtained from fc 1 ~t~ ons Ll and L3,
respectively, regardless of their storage times and t~ ~ LuLes.
The relatl-~nch1p was bipllasic on each of the three pulse
S~lUf~nc~-c and on all three pulse sequences combined. Both
se, - -c of each curve are linearly related. Since this plot
indicated a biphasic relationship, the data were analyzed by
se_ ed linear regression analysis. The critical point (the
interception between the t~o regressions) was derived based on
the slope and Y-intercept of each regression.
~1R T~l;rln~ ~nd Ir~ge Ar)~lysic
The in vitro and ~n vivo MR imaging procedures using
Tl-, T2- and proton density-weighted pulse sequences, have been
described above. MR images from this study were evaluated both
qualitatively and quantitatively. Qualitative assessments
involved evaluation of image quality along with image artifacts
in terms of their presence or absence, as well as the severity
and quantity of bright magnetic susceptibili~y image distortion,
as compared to unenhanced images. Quantitative assessments
WO 95120405 21 8 2 2 ~ 3 - 6~ L5~ a
involved meas~rements of signal intensity (SI) values from the
phantoms for in vitro studies, and from two regions of interest
~ROI) in the stomach and four,l~OI's in the small bowel for in
vivo studies. The SI values~were normalized by means of the SI
ratio: the SI of the contrast agent of the invention over that of
air. Ratios less than 2.0 were considered to be "sufficiently
black", greater than 2.0 "insuff~c~Pntly black", and close to 2
"marginal . This criterion was chosen based on preliminary
results indicating that ratios above 2 tended to produce
insufficient blackening along with image distortions. This
criterion was supported by the results of the present studies
Table 4.
n Vivo Determ;n~t~on of Low~ct Viccosity Lim;t for EYcellent
e O11A1 ity
This PYrPr; L ctrAtes the lowest viscosity that
the cnntrAct agent of the invention must r-~ntA~n to ensure
F-ff~r~Pnt MR imaging.
About 500 - 600 mL of six liquid f~ lAt;nnC of varying
viscosities targeted to be (1, 25, 50, 75, 100 and 150 cPs
designated formulations A,B,C,D,E and F respectively) were
prepared and A- ' ' n~ ctered within 5 minutes via a nasogastric tube
into the stomach of two dogs.
Images of the sites of interest were obtained and
evaluated as described hereinabove.
The viscosities of all fo 1 at i ons were very stable as
is refll~ctPd by the small fl~lctuAt jons in the Yiscosity values
(Standard Deviation or SD < 3.5 cP) measured during the course of
the study. (Figure 2 and Table 4).
In the in vivo imaging evaluation, excellent signal
blackening without image artifacts was produced at viscosities
>-25 cP, with the exception of imaging the small bowel using the
proton-density pulse sequence with the 100 cP formulation ~Table
4). The unexpectedly poor quality produced by the 100 cP
formulation in imaging the small bowel was caused by a "ghost
artifact", which was caused by motion, especially respiratory
~ Wo gsl2040s - 1 7_ 2 1 8 2 ~ 1 3 P~ .,,~C ~
motion. The ~'ghost artifact" was confirmed by an extra signal
overlapping onto the real signal across the entire image On all
three pulse sequences, the 25 cP formulation produced excellent
signal blackening with mild image blurring. This mild image
artifact was not considered to be significant. This demonstrates
that in anaesthetized dogs, contrast media of the invention
having a viscosity of at least of -25 cP produces excellent
signal bl ;~rkPn; n~ without significant image artifacts .
WO 95120405 2 1 8 2 2 ~ 3 , ~ C 175
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~ WO 9S/20405 . ~ .l I /a
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In vitro ~eterrnination of Lowest Vis~osLtv Limit for Fucell~nt
e OU~litv
~ hereas in vivo LVL was found to be -25 cP, the in vitro
LVL was found to be between ~25 and -50 cP (Table ~). The exact
reasons for the discrepancy between the in vivo and in vitro LVL
values are unknown. It may be the result of in vivo peristaltic
activity continuously mixing intraluminal contrast agent and
preventing gravitational settling. It may also be the result of
~nhAn, L of signal b~ Ark~ni ng by intraluminal contrast/medium
that was above and below the plane of image. It appears that the
imaging quality of the contrast agent is r~ on the degree
of dispersion of the r~-~netirAlly susceptible iron ferrite in the
formulation, and that a minimum viscosity is needed to insure
such dispersion. Fo~ f; r-nc with viscosity lower than the LVL
value are prone to gravitational settling, resulting in particle
aggregation which in turn, leads to uneven distribution of
particle cnnr~ntrAt~rnc. Tn~ , ^lty in part~cle c~nr~nt~2tions
in turn causes insufficient signal blackening and magnetic
susceptibility artifacts.
~ -rAtiVe F~ lAt;~7nc
This example compares the imaging qualities of five
different OMP fc 1 At; nnc (See Tables 2 and 3) after these
f~ lAt~nc had been exposed to various t ~ es for various
periods (Table 5).
Three liquid forrbulations (Ll, L2 and L3), which
differed in hydroxylpropyl-nnethylcellu ose, xanthan gum, sodium
sulfate, microcrystalline cellulose and carboxymethylcellulose
sodium concentrations ~Table 2), were studied in vitro.
Formulation L2 was in~erior to formulations L1 and L3
because after one-week exposure to 70C, poor signal blackening
~reflected by SI ratios greater than 2) on Tl-weighted and proton
density-weighted sequences were produced by formulation L2 (Table
5). Conversely, excellent signal blackening (reflected by SI
wo gsQo405 2 1 8 ~ 2 1 3 P~ . s ~"~ ~
ratios smaller than 2) on all three pul~e sequences were produced
by formulations Ll and L3 after they had been exposed to the
identical conditions. Formulation I,2 was judged to be inferior
also because although excellent signal blackening (reflected by
SI ratios less than 2) were observed on all three pulse sequences
after had been exposed to 30C for one week, poor signal
blArl'~nin~ on the second T1-weighted sequence was observed. This
suqgests that gravitational settling occurred 20 minutes after
manual shaking. Gravitational settling was not apparent 20
minutes after manual shaking with formulations Ll and L3 after
these fo l~t~ons had been exposed to 30C for one month and one
week, respectively tTable 5).
For the two gr;ln~ r fo l~t1Ons (Gl and G21 ~YImined
in this study ~Table 3), neither was found acceptable. Poor
signal bl Ar-k~n; n~ was ~Ic,du~ d by fc - 1 ~t ~ on G1 after exposure
to 50C for six weeks, and by formulation G2 after exposure to 50
and 70C for one week ~Table 5). For formulation Gl, the
efficacy was slightly ~ d by using glass instead of plastic
cont~1n~rs. This was refle~ted by the slightly lower SI ratios
on all three pulse ~eq~ nres lnduced by fo 1 ~qt ~ n Gl from glass
rather than plastic bottles.
The results of this study also showed that for all
unacceptable formulations ~liquid formulation L2 and granular
formulations Gl and G2), the imaging efficacy was improved by
manual shaking. This was reflected by some SI ratios on the
second Tl-weighted se-~uence ~i.e., after they had been subjected
to an additional manual shaking) being lower than those on the
first Tl-weighted sequence ~Table 5). However, imp~ by
the additional manual shaking was not sufficient to allow these
formulations to provide sufficient blackening, since SI ratios
were still close to or greater than 2.
Finally, the viscosity of the liquid formulations
decreased as a function of the temperature to which they were
subjected. This inverse relationship between the viscosity and
temperature exposure for the liquid formulations was evident
during the one-month exposure of formulation L1, and the one-week
exposure of formulations L2 and L3, to various temperatures
-
Wo 95120405 - 2 1 -
(Table 5) . This inverse relationship was not observed witn the
granular formulations. The results show that the granular
formulations did not always provide good imaging qualities even
though their viscosities were greater than 150 cP, confirming
that more than high viscosity is needed to produce high quality
imaging.
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Imaging Performance After Storage
Since formulations L1 and L3 were found to provide
excellent signal blackening (See the comparative experiments
above) they were further evaluàtèd in vitro for performance after
storage. The results (Table 6~ show that after exposure to room
temperature for eight weeks both formulations provided excellent
signal hlAck~n;ng (reflected by SI ratios smaller than 2) on all
three pulse sequences with no image artifacts. After exposure to
70C for one week followed by room temperature for seven weeks,
both formulations also proYided excellent signal blackening (SI
ratios below or close to 2) on all three pulse sequences with no
image artifacts. However, after exaggerated exposure to 70C for
five weeks plus room temperature for three weeks, the imaging
qualities ~Lud~lced by these two formulations were poor (SI ratios
greater than 2 and image artifacts observed on at least two of
the three pulse sequences). These results indicate that both
formulations behaved similarly to stressful environments in
regard to 2~ imaging.
_ _ _
~ 1 8 2 2 1 ~ P~ C ~
Wo 95120405
-Z7-
sirlg t he Formuldtion of the Invention in Humans
Prior to magnetlc resonance imaging, human volunteers
- ingested a contrast agent whose formulation appears in Table 7.
' Table 7
Formulation of Contrast Agent
In~redients (% w/v) Formulation
Ma~netic Particles 0,47%
Mi~Lu~ly~al1ine Cellulose and 0,480>x
Ca-lG~y~ llylcellulose Na
Xanthan Gun~ ca.2 0,180~
Pûtassium Sorbate Q150~oc
Sodium Benzoate QlZO~
Saccharin Sodium OD20Dx
FD8~C Yellûw No. 6 OD100x
~&C Red No. 40 QOO900
FD&C Blue No. 1 QOOlQO
HCl/NaOH q.s. pH=4.25
Purified Water q.s. (mL~ 100.xx~x
1 To provide total iron cr~nrf!n~ration of 150 ~Lg/mL.
2 To adjust viscosity to 310-510 cP.
q.s. = sufficient quantity.
E~ rnle A
A 25 year old male volunteer orally ingested 500 mL o~
the formulation described above over a 30 minute time period.
Multiple axial abdominal and pelvic Magnetic Resonance (MR)
images were obtained prior to ingestLon and at multiple time
points following ingestion.
~ he pre-ingestion gradient echo MR images showed
intermediate signal intensity within the stomach, On the 60
minute post-ingestion gradient echo MR images, the signal
intensity within the stomach had decrezsed due to the presence of
. .
218221~ a
W0 95/2040~
_z,~
the formulation (negative contrast effect) and increased
distension of the stomach was noted
Pre-ingestion gradient echo MR images demonstrated
moderate to high signal intensity in the lumen of the small bowel
which was darkened by the presence of formulation within the
lumen of the small bowel on the 60 minute post-ingestion image
These results show that in this patient 500 mL of
product increased signal blArk~nin~ of both the stomach and small
bowel after 60 minutes using a gradient echo pulse sequence.
Therefore, the product improved negative contrast and increased
visil:~ility of these two organs, when compared to pre-ingestion MR
images .
F xa le B
A 43 year old female volunteer orally ingested 750 mL of
the formulation described above over a 60 minute time period.
Multiple axial MR images were obtained from the mid-stomach to
pelvic region both prior to and following ingestion of the
formulation. Images at multiple time periods were acquired
following ; nrJ~st i ~)n .
The Tl-weighted pre-ingestion MR images demonstrated
int~ te signal within the stomach, small bowel, and regions
of the large bowel. The immediate post-ingestion Tl-weighted
images demonstrated distension and darkening of the stomach due
to the presence of the f~_ 1At~on In addition, the formulation
was seen distributed throughout segments of the small bowel with
resultant darkening of the small bowel lumen. The 60 minute
post-ingestion Tl-weighted M~ images showed continued darkening
of the stomach however, less distension of the stomach was noted.
Further distribution and darkening of small bowel segments were
noted in the 60 minute post-ingestion images.
In addition, the 60 minute post-ingestion images
demonstrated occasional segments of large bowel with intermediate
to dark signal intensity.
These results show that 750 mL of product in this
patient resulted in an inuDediate signal blackening of the stomach
o W0 95120405 j, 9 2 1 ~ ~ 2 ~ ~ r ~ >7~ a
using Tl-weigh~ed sequences Furthermore, 60 minutes a~ter
ingestion, excellent negative contrast was seen in the small
bowel and occasionally in the large bowel using the same pulse
sequence. Therefore, visibility of these areas was greatly
improved when compared to pre-ingestion images.
~x le C
A 45 year old ~emale volunteer orally ingested 1000 mL
of the formulation described above over a 60 minute time period.
~ultiple axial Tl and T2-weighted MR images of the abdomen and
pelvis were obtained prior to and al various time points
following ingestion of the f- lAt~n
The pre-ingestion T}-weighted MR images of the lower
abdomen and pelvis demonstrated i nt~ te signal within the
lumen of the large bowel and sigmoid colon. The three hour post-
ingestion Tl-weighted images demonstrated darkening of the
luminal ~nt~nte of the large bowel, sigmoid colon and rectum.
The T2-weighted pre-ingestion MR images demonstrated
int~ te signal within the stomach, small bowel and large
bowel. This intermediate signal was mixed with areas of dark
signal within the bowel lumen . The i - ~ ~te post-ingestion T2-
weighted ~R images showe~ darkening and distension of the
stomach. In addition, segments of the small bowel demonstrated
areas of darkening compared to the pre-ingestion images
L-C~ nq the yLes~l~ce of the ~ ~nt-~ct agent f~ l ~t ion .
The three hour post ingestion T2-weighted MR images
demonstrated darkening of segments o~ large bowel luminal
cont-~nte compared to the pre-ingestion T2-weighted MR images.
WO95/20405 ~182213 .~ s - 175
-30-
These results show that_overall, 1000 mL ingestion of
product resulted in an increase of signal blackening of luminal
contents of large bowel, sigmoid colon and rectum after three
hours using Tl-weighted pulse sequences. T2-weighted pulse
sequences, three hours after ingestion, display superior contrast
of large bowel luminal contents, as opposed to pre-ingestion
images .
In summary, improved negative contrast (MR-imaging
efficacy) of various ~ nenLs of the gastrointestinal tract was
obtained using three pulse sequences and three doses of the
contrast media fo_ 1 ~t ~ on of the inventions .
The invention has been described in detall with
particular reference to certain preferred embo~ -ntC thereof,
but it will be understood that variations and modifications can
be etrfpcrpd within the spirit and scope of the inventions.
