United States District Court, D. Massachusetts
MEMORANDUM AND ORDER ON CLAIM CONSTRUCTION
RICHARD G. STEARNS UNITED STATES DISTRICT JUDGE
the second wave in a Multidistrict Litigation (MDL) involving
U.S. Patent No. 5, 560, 360 (the ’360 patent), directed
to “[a] neurography system  for generating
diagnostically useful images of neural tissue  employing a
modified magnetic resonance imaging [(MRI)] system.”
’360 patent, Abstract. In 2012, plaintiffs NeuroGrafix,
Neurography Institute Medical Associates, Inc., Image-Based
Surgicenter Corporation, and Dr. Aaron G. Filler, launched an
armada of lawsuits against MRI equipment manufacturers and
university and hospital end-users, accusing them of
infringing the ’360 patent. With one exception, the
nine cases originally consolidated by the MDL Panel in this
district for pretrial proceedings resolved before reaching
claim construction. In 2015, plaintiffs filed six new
lawsuits. These too were consolidated with this MDL
Before the court are the parties’ competing briefs on
claim construction. Pursuant to Markman v. Westview
Instruments, Inc., 517 U.S. 370 (1996), the court
received tutorials in the underlying technology and heard
argument on August 18, 2016.
’360 patent, entitled “Image Neurography and
Diffusion Anisotropy Imaging, ” was issued on October
1, 1996. It lists as its inventors Aaron G. Filler,
 Jay S.
Tsuruda, Todd L. Richards, and Franklyn A. Howe. The
’360 patent sets out 66 claims.
’360 patent discloses methods and apparatus for
generating “diagnostically useful” images of
peripheral nerves (the term includes peripheral, autonomic,
and cranial nerves) using MRI technology. ’360 patent,
Abstract. These nerves
commonly travel through and along bone, muscle, lymphatics,
tendons, ligaments, intermuscular septa, collections of fatty
tissues, air and fluid spaces, veins, arteries, joints, skin,
mucous membranes and other tissues. The relatively small size
of peripheral nerves, as well as their close proximity to
other tissue of comparable size and shape, makes them
difficult to locate and identify.
Id. col. 1, ll. 32-38. The complex structure of
neural plexus (where bundles of nerve fibers “may join
together, separate, rejoin, intermix, and resegregate,
forming intricate three dimensional patterns”) also
complicates the examination of peripheral nerves.
Id. col. 1, ll. 39-51.
to the invention of the ’360 patent, MRI technology had
been used to image peripheral nerves with only limited
success. By way of a brief background,
MRI involves the exposure of tissue to a variety of different
magnetic and radio-frequency ([RF]) electromagnetic fields.
The response of the specimen’s atomic nuclei to the
fields is then processed to produce an image of the specimen.
Id. col. 2, ll. 5-9. The patient is first exposed to
a polarizing magnetic field that causes hydrogen
protons’ axes to align themselves with the field. When
additional energy in the form of an RF electromagnetic wave
pulse is applied, the protons change the alignment of their
axes. When the RF pulse is switched off, the protons reorient
their alignment with the magnetic field, causing them to emit
detectable resonance (also in the form of radio waves).
Receiver coils detect the radio signal, which is converted by
a computer using Fourier analysis into a visual image.
Various RF pulse sequences can be used to emphasize or
suppress different types of tissues within the body.
to the ’360 patent, MRI was used in conjunction with
injectable contrast agents to image peripheral nerves. This
technique requires two-part contrast agents - one part to
promote neural uptake of the dye, and the other to enhance
the imageability of the nerve. The technique has several
limitations. In addition to being invasive, only a single
nerve or nerve group can be imaged at one time, and the
contrast agent typically reduces the intensity of the imaged
also been used to successfully image non-peripheral white
matter nerve tracts in the brain without the use of contrast
agents. White matter nerve tracts, in comparison to the
surrounding gray matter, exhibit a relatively high diffusion
anisotropy, that is, water mobility in the direction along
the white matter tracts is relatively high, while water
mobility perpendicular to the tracts is l0w.
[T]his process involves the use of a pair of field gradient
pulses (hereinafter referred to as diffusion gradients),
oriented perpendicular and parallel to the white matter
tracts to be imaged. . . . [G]iven the anisotropic nature of
the tracts, water will diffuse freely along a tract, but is
restricted in it[s] motion perpendicular to the tract. When
the diffusion gradient is aligned with the tract there is
thus a greater reduction in signal than when the diffusion
gradient is aligned perpendicular to the tract. Because this
phenomenon is not exhibited by the surrounding gray matter
tissue, the white matter tracts can be identified.
Id. col. 5, ll. 19-39.
technique, however, does not transfer easily to the imaging
of peripheral nerves even though these nerves are also
diffusionally anisotropic. Peripheral nerves are considerably
smaller than white matter tracts and their return signals are
too weak for effective imaging. In addition to fat (which is
isotropic and distinguishable from the nerves when imaged),
peripheral nerves are also surrounded by muscle, which is
also diffusionally anisotropic and not easily distinguished.
solve the problem of effectively imaging peripheral nerves
without the use of contrast agents, the inventors discovered
novel ways of assembling complex pulse sequences, wherein
even though the simple components of the sequence decrease
the signal-to-noise ratio of nerve or decrease the signal
strength of nerve relative to other tissues, the fully
assembled complex sequence actually results in the nerve
signal being more intense than any other tissue.
Id. col. 6, ll. 39-45. More specifically,
“[t]he combined use of fat suppression [pulses] and
diffusional weighting has  been found to be extremely
effective in providing the desired nerve image
enhancement” and has the “synergistic benefit . .
. [of] an actual increase in neural signal anisotropy . . .
with the conspicuity of the neural component of the image
increasing by roughly 250 percent when the fat component is
removed.” Id. col. 22, ll. 32-35; 58-64.
patent describes two nerve imaging approaches depending on
the diffusion-weighted gradients used. Subtraction
neurography is appropriate where the diffusion-weighted
gradients match the nerve axes.
[I]n one currently preferred embodiment, the analysis
involves the application of pulsed magnetic field gradients
to the polarizing field in two or more directions to produce
images in which the peripheral nerve is enhanced or
suppressed, depending upon the “diffusion
weighting” resulting from the particular pulsed
gradient axis chosen. Discrimination of water diffusion
anisotropy is then achieved by subtracting the suppressed
image from the enhanced image, in the manner described in
greater detail below, producing an image depicting only the
Most preferably, the magnetic field gradients are applied in
mutually substantially orthogonal directions. For example,
with gradients approximately perpendicular and parallel to
the axis of the peripheral nerve at the particular point
being imaged, the parallel gradient image can be subtracted
from the perpendicular gradient image to produce the desired
“nerve only” image.
Id. col. 15, ll. 40-57. However, where the gradients
do not align with the nerve(s) to be imaged, vector
processing is used to obtain the image.
[I]f the axis of the peripheral nerve is not known, or if
many nerves having different axes are being imaged, the
neurography system must employ a system of gradient
orientations suitable for imaging nerve having substantially
any axial alignment. For example . . . a full
three-dimensional vector analysis can be used to characterize
the diffusion coefficient and provide a nerve image by
construction based upon a fixed arrangement of diffusion
Id. col. 15, l. 63 - col. 16, l. 4.
36 is a representative method claim.
method of utilizing magnetic resonance to determine the shape
and position of a structure, said method including the steps
(a) exposing a region to a magnetic polarizing field
including a predetermined arrangement of diffusionweighted
gradients, the region including a selected structure that
exhibits diffusion anisotropy and other structures that do
not exhibit diffusion anisotropy;
(b) exposing the region to an electromagnetic excitation
(c) for each of said diffusion-weighted gradients, sensing a
resonant response of the region to the excitation field and
the polarizing field including the diffusionweighted gradient
and producing an output indicative of the resonant response;
(d) vector processing said outputs to generate data
representative of anisotropic diffusion exhibited by said
selected structure in the region, regardless of the alignment
of said diffusion-weighted gradients with respect to the
orientation of said selected structure; and
(e) processing said data representative of anisotropic
diffusion to generate a data set describing the shape and
position of said selected structure in the region, said data
set distinguishing said selected structure from other
structures in the region that do not exhibit diffusion
54 is a representative apparatus claim.
magnetic resonance apparatus for determining data
representative of the diffusion anisotropy exhibited by a
structure, said apparatus including:
(a) excitation and output arrangement means for exposing a
region to a suppression sequence of electromagnetic fields
that suppresses the electromagnetic responsiveness of
structures in the region that do not exhibit diffusion
anisotropy, so as to increase the apparent diffusion
anisotropy of structures in the region that exhibit diffusion
anisotropy, said suppression sequence of electromagnetic
fields not including diffusionweighted magnetic gradients;
(b) polarizing field source means positioned near said
excitation and output arrangement means for exposing the
region to a predetermined arrangement of diffusionweighted
magnetic gradients chosen to:
i) emphasize a selected structure in the region exhibiting
diffusion anisotropy in a particular direction; and
ii) suppress other structures in the region exhibiting
diffusion anisotropy in directions different from said
particular direction, said excitation and output arrangement
means further for sensing a resonant response of the region
to the diffusion-weighted gradient and producing an output
indicative of the resonant response, for each of said
diffusionweighted gradients; and
(c) processor means coupled to said excitation and output
arrangement means for processing said outputs to generate
data representative of the diffusion anisotropy of the
The parties dispute the construction of 9 claims terms.
• “processing said data representative of
anisotropic diffusion to generate a data set describing the
shape and position of said selected structure in the region,
said data set distinguishing said selected structure from
other structures in the region that do not exhibit diffusion
anisotropy” (claim 36)
• “processing said outputs to generate data
representative of the diffusion anisotropy of the selected