261 F.3d 1329 (Fed. Cir. 2001)
ADVANCED CARDIOVASCULAR SYSTEMS, INC. and GUIDANT SALES CORPORATION, Plaintiffs-Appellants,v.SCIMED LIFE SYSTEMS, INC. and BOSTON SCIENTIFIC CORPORATION, Defendants-Appellees.
00-1454
United States Court of Appeals for the Federal Circuit
DECIDED: August 6, 2001

Appealed from: U.S. District Court for the Southern District of Indiana Judge David F. Hamilton Richard A. Bardin, Fulwider Patton Lee & Utecht, LLP, of Los Angeles, California, argued for plaintiffs-appellants. With him on the brief were Craig B. Bailey and James Juo. Of counsel on the brief were Harvey Kurzweil, Clark E. Walter, Aldo A. Badini, and Bradford J. Badke, Dewey Ballantine LLP, of New York, New York.
Walter E. Hanely, Jr., Kenyon & Kenyon, of New York, New York, argued for defendants-appellees. With him on the brief were Charles R. Brainard, Douglas E. Ringel, and Reem F. Jishi. Of counsel were Paul H. Heller, of New York, New York; and Mark Michael Supko, of Washington, DC.
Before MICHEL, Circuit Judge, ARCHER, Senior Circuit Judge, and SCHALL, Circuit Judge.
SCHALL, Circuit Judge.


1
Advanced Cardiovascular Systems, Inc. and Guidant Sales Corp.  (collectively, "ACS") appeal the decision of the United States District  Court for the Southern District of Indiana granting summary judgment in  favor of Scimed Life Systems, Inc. and Boston Scientific Corporation  (collectively, "Scimed") in ACS's suit against Scimed for patent  infringement. Adv. Cardiovascular Sys., Inc. v. Scimed Life Sys., Inc., No.  98-1108 (S.D. Ind. June 28, 2000) ("Adv. Cardiovascular IV"). The district  court ruled that Scimed was entitled to summary judgment that it did not  infringe the asserted claims of United States Patent Nos. 5,421,955 (the "  '955 patent"), 5,514,154 (the " '154 patent"), 5,603,721 (the " '721  patent"), 5,728,158 (the " '158 patent"), and 5,735,893 (the " '893  patent"). Id. The patents at issue relate to a flexible coronary stent that  is adapted to be placed in a patient's blood vessel, expand, and then stay  expanded, thereby keeping the involved segment of the vessel open. The  asserted claims are directed to the stent, methods for using the stent, and  a process for making the stent.


2
We vacate the district court's grant of summary judgment of non-  infringement with respect to claims 11 and 12 of the '955 patent, claims 1-  4, 9, and 23 of the '154 patent, claims 1-4 of the '721 patent, and claims  1, 2, 5, 6, 9, and 11-13 of the '158 patent, because the grant of summary  judgment was based on an erroneous construction of the term "connecting  elements," and the similar terms "interconnected," "connecting members,"  and "struts for connecting." The court erred in construing these terms as  requiring that the stent's connecting elements be parallel both to each  other and to the longitudinal axis of the stent. We also vacate the  district court's grant of summary judgment of non-infringement with respect  to claims 12-15, 17, 18, and 20 of the '154 patent. We do so because the  court erred in construing the phrase "generally parallel connecting  elements" to require the connecting elements to be generally parallel to  the stent's longitudinal axis, and because it is unclear, from the  intrinsic evidence, under what frame of reference the claims require the  connecting elements to be generally parallel to each other. We affirm,  however, the district court's grant of summary judgment of non-infringement  with respect to claims 10 and 21 of the '154 patent, claims 14-16, 19, and  20 of the '158 patent, and claims 1, 2, and 4-13 of the '893 patent. The  case is remanded to the district court for further proceedings.

BACKGROUND
I.

3
The '955, '154, '721, '158, and '893 patents all are assigned to ACS. Each  patent relates back to two original abandoned applications, Application No.  07/783,558 (the " '558 application"), filed on October 28, 1991, and  Application No. 08/164,986 (the " '986 application"), filed on December 9,  1993. Since they all are related to the '558 and '986 applications, the  patents have similar specifications and drawings.


4
The '154 patent's specification and drawings are representative of the  specifications and drawings of all of the patents in suit. The '154 patent  is directed to "an expandable stent which is relatively flexible along its  longitudinal axis to facilitate delivery through [a blood vessel], but  which is stiff and stable enough radially in an expanded condition to  maintain" free passage through a vessel in which the invention is  implanted. '154 patent, col. 1, ll. 53-58. The stent 10 is depicted below  in Figures 3 and 4 of the '154 patent.


5
[Tabular or Graphical Material Omitted]


6
Figure 3 shows the stent 10 inside an artery 15. Id. at col. 5, ll. 11-28.  The specification describes stent 10 as having a "plurality of radially  expandable cylindrical elements," identified as 12 in Figures 3 and 4, that  can each "expand and . . . flex relative to one another." Id. at col. 1,  ll. 59-62. "Interconnecting elements or struts," also called "connecting  elements" and identified as 13 in Figures 3 and 4, "extend . . . between  adjacent cylindrical elements" and "provide increased stability and a  preferable position to prevent warping of the stent upon the expansion  thereof." Id. at col. 1, l. 65 - col. 2, l. 1. The stent is placed on a  balloon or other expandable member. Thereafter, once the stent is placed at  the desired location in a blood vessel, the balloon is inflated, the stent  expands, and the balloon is removed, leaving the stent in its expanded  state, against the blood vessel's walls 15, as shown in Figure 3. Id. at  col. 4, l. 57 - col. 5, l. 10.


7
The '154 patent notes that "[p]referably, all of the interconnecting  elements of the stent are joined at either the peaks or the valleys of the  undulating structure of the cylindrical elements . . . . In this manner  there is no shortening of the stent upon expansion." Id. at col. 2, l. 67 -  col. 3, l. 4; see also id. at col. 5, ll. 42-51. This configuration is  demonstrated in Figures 3 and 4 of the '154 patent, shown above.


8
Claim 1 of the '154 patent is directed to the stent itself, and is  representative of the apparatus claims asserted by ACS. Claim 1 reads:


9
1. A longitudinally flexible stent for implanting in a body lumen, comprising:


10
a plurality of cylindrical elements which are independently expandable in the radial direction and which are interconnected so as to be generally aligned on a common longitudinal axis;


11
a plurality of connecting elements for interconnecting said cylindrical elements, said connecting elements configured to interconnect only said cylindrical elements that are adjacent to each other; and


12
an outer wall surface on said cylindrical elements, said outer wall surface being smooth prior to expansion of said stent and forming a plurality of outwardly projecting edges which form as said stent is expanded radially outwardly from a first diameter to a second, enlarged diameter.


13
Id. at col. 8, ll. 36-52. Independent claim 12 differs from claim 1,  describing "a plurality of generally parallel connecting elements . . . ."  Id. at col. 9, l. 28 (emphasis added).


14
The '154 patent is a descendant of the '558 application. The '558  application included claims directed to an expandable, flexible stent, a  method of using the stent, a process for making the stent, and a kit that  included the stent. Some of the '558 application's claims were rejected as  being anticipated by United States Patent No. 5,102,417, which was issued  to Julio C. Palmaz (the "Palmaz '417 patent"). The '558 application's  claims were amended in response to the rejection, but the examiner  maintained his rejection based on the Palmaz '417 patent.


15
The '986 application was filed as a continuation of the '558 application.  Eventually, a preliminary amendment to the '986 application was filed,  amending certain claims of the application to recite "a plurality of  generally parallel connecting elements for interconnecting said cylindrical  elements . . . ." (emphasis added). The inventors argued that the amended  claims were patentable over the Palmaz '417 patent. The examiner maintained  his rejection, however. The '154 patent then was filed as a continuation-  in-part of the '986 application, and the '986 application was abandoned.  The '154 patent's claims, directed to an expandable, flexible stent, were  allowed. Most of the asserted claims of the '154 patent, such as  independent claim 1, simply recite "connecting elements," see '154 patent,  col. 8, ll. 36, 52, while other asserted claims, independent claim 12 for  example, recite "generally parallel connecting elements," see id. at col.  9, ll. 23-33.


16
The '955 patent was filed as a continuation of the '558 application, and  the '558 application then was abandoned. The '955 patent's claims are  directed to a process for making the expandable, flexible  stent.1 Claims 11 and 12 of the '955 patent, the asserted  claims, describe the claimed cylindrical elements as being  "interconnected," but do not expressly describe the interconnections as  being "parallel." '955 patent, col. 8, l. 57 - col. 9, l. 10.


17
The '721 patent was filed as a divisional of the '154 patent; it claims a  method for using the expandable, flexible stent. The asserted claims of the  '721 patent describe the stent as having cylindrical elements that are  "interconnected." However, like the asserted claims of the '955 patent,  they do not state that the interconnections are "parallel." '721 patent,  col. 8, l. 33 - col. 10, l. 6.


18
The '158 patent was filed as a divisional of the '721 patent; its claims  are directed to an expandable, flexible stent. Most of the '158 patent  claims that ACS asserts against Scimed recite a "longitudinally flexible  stent" that has a "plurality of connecting elements." '158 patent, col. 8,  l. 47 - col. 10, l. 52. Asserted dependent claim 2, however, recites a  stent in claim 1 "wherein said connecting elements are generally parallel  to each other," id. at col. 8, ll. 64-65. At the same time, claim 4, which  also depends from claim 1 but is not asserted, describes a stent "wherein  said connecting elements are generally parallel to the common longitudinal  axis of said cylindrical elements," id. at col. 9, ll. 1-3.


19
The '893 patent was filed as a divisional of the '721 patent; its claims  are directed to an expandable, flexible stent. The '893 patent's claims  recite "connecting members" or "struts for connecting" that join the  stent's cylindrical elements. '893 patent, col. 8, l. 32 - col. 10, l. 19.  None of the asserted claims of the '893 patent modify these terms with the  phrase "generally parallel." Id.


20
The accused device that is made by Scimed, the NIR stent, is an expandable,  flexible coronary stent. The NIR stent is shown below.


21
[Tabular or Graphical Material Omitted]


22
Relevant to the district court's grant of summary judgment of non-  infringement, the NIR stent's connecting elements are not straight, such as  those seen in Figures 3 and 4 of the '154 patent, but curved vertical loops  or U's. These curved connecting elements attach to the peaks or valleys of  the horizontal loops that comprise the body of the NIR stent.

II.

23
In the district court, ACS alleged that Scimed infringed claims 11 and 12  of the '955 patent, claims 1-4, 9, 10, 12-15, 17, 18, 20, 21, and 23 of the  '154 patent, claims 1-4 of the '721 patent, claims 1, 2, 5, 6, 9, 11-16,  19, and 20 of the '158 patent, and claims 1, 2, and 4-13 of the '893 patent  by manufacturing and selling its NIR stent. The parties first asked the  court to construe certain terms in the asserted claims. In response, the  court construed the asserted claims, adopting ACS's proposed construction  of "connecting element," construing the term to mean "an element of the  stent that connects adjacent cylindrical elements." Adv. Cardiovascular  Sys., Inc. v. Scimed Life Sys., Inc., No. 98-1108, slip op. at 16-17 (S.D.  Ind. Oct. 15, 1999) ("Adv. Cardiovascular I"). The court construed the  phrase "generally parallel connecting elements" in independent claim 12 of  the '154 patent to mean that the connecting elements must be parallel both  to each other and to the stent's longitudinal axis. Id. at 25-27. In  addition, the court determined that dependent claim 2 of the '158 patent  explicitly required the connecting elements to be generally parallel to  each other. Id. at 26-27. Finally, the court construed the phrase "[a]  plurality of outwardly projecting edges" in claims 1 and 23 of the '154  patent, and similar phrases in claim 1 of the '721 patent and claims 1 and  14 of the '158 patent, to mean "a number of U-, W-, and Y-shaped members of  the cylindrical elements."2 Id. at 23-24.


24
Scimed then moved for a supplemental claim construction, asking, in part,  that the district court limit the term "connecting element" in the asserted  claims to a "connector that is generally parallel to the longitudinal axis  of the stent." Adv. Cardiovascular Sys., Inc. v. Scimed Life Sys., Inc.,  No. 98-1108, slip op. at 1-2 (S.D. Ind. Feb. 9, 2000) ("Adv. Cardiovascular  II"). The district court granted the request and adopted Scimed's proposed  construction, focusing on statements by the inventors during prosecution  relating to the Palmaz '417 patent. Id. at 4-5. The court also noted that  "if the connecting elements claimed in the [asserted patents] must all be  generally parallel to the longitudinal axis, they should all be generally  parallel to each other." Id. at 5 n.2. We interpret this footnote to mean  that the district court construed the term "connecting element" to require  the connecting elements to be generally parallel both to each other and to  the longitudinal axis of the stent.


25
Scimed then moved for summary judgment of non-infringement with respect to  the asserted claims. In due course, the district court granted summary  judgment of non-infringement, either literal or by equivalents, of claims  12-15, 17, 18, and 20 of the '154 patent on the ground that the NIR stent  did not have connecting elements that were "generally parallel," as  required by the claims. Adv. Cardiovascular Sys., Inc. v. Scimed Life Sys.,  Inc., No. 98-1108, slip op. at 7-12 (S.D. Ind. Feb. 9, 2000) ("Adv.  Cardiovascular III"). The court noted that the connecting elements of the  NIR stent were not generally parallel to each other, because, when the  curved or U shaped connecting elements on opposite sides of the NIR stent  were compared, they were "not aligned in the same manner." Id. at 8.  Rather, they were seen to "run in opposite directions, like, as defendants  put it, a smile and a frown." Id. The court also noted that the NIR stent's  connecting elements were not generally parallel to the stent's longitudinal  axis because they were curved and therefore could not be parallel to that  axis. Id. at 9-10. The court stated that ACS had failed to present any  evidence explaining how the NIR stent's connecting elements, which were  non-parallel, were equivalent to the claimed "generally parallel connecting  elements." Id. at 10-12. Concluding, based on the NIR stent's lack of  substantially U-shaped members, that the NIR stent also did not fall within  the scope of the '893 patent's claims, the court granted summary judgment  of no literal infringement, or infringement under the doctrine of  equivalents, of claims 1, 2, and 4-13 of the '893 patent in favor of  Scimed.3 Id. at 16-17. The court also granted summary judgment  of non-infringement of claims 10 and 21 of the '154 patent, which require  the stent to be formed of a single piece of tubing, and claims 14-16, 19,  and 20 of the '158 patent, which require the stent's cylindrical elements  to have "a width," id. at 17, because, as the district court noted, ACS  represented to the court that it would not assert infringement of those  claim limitations, id. at 3.4


26
ACS then asked the district court to reconsider its construction of  "connecting elements," while Scimed requested that the court, based upon  its construction of "connecting elements," grant summary judgment of non-  infringement of all of the claims asserted by ACS. The district court  denied ACS's motion for reconsideration, reaffirming its construction of  "connecting elements." Adv. Cardiovascular IV, slip op. at 7-8. In so  doing, the court pointed to the fact that the only embodiment in the  asserted patents depicts the connecting elements as generally parallel to  the stent's longitudinal axis. Id. The district court also based its  construction on statements made by the inventors regarding the Palmaz '417  patent during the prosecution of the '986 application, concluding that the  inventors described their invention, not just the claims of the '986  application, as superior to the Palmaz '417 patent because it had  connecting elements that were generally parallel to the stent's  longitudinal axis. Id. at 8-10. The court applied its construction of  connecting elements to the term "interconnected" in the '955 and '721  patents, and to the terms "connecting members" and "struts for connecting"  in the '893 patent because all of those terms refer to the means for  connecting the described stent's cylindrical elements. Id. at 10-11.


27
Based on its construction of the term "connecting elements," the district  court granted Scimed's motion for summary judgment, finding that the NIR  stent did not infringe, either literally or under the doctrine of  equivalents, any of the asserted claims because the stent's connecting  elements are not generally parallel both to each other and the stent's  longitudinal axis. Id. at 11-12. The court therefore entered judgment in  favor of Scimed. ACS now appeals. We have jurisdiction pursuant to 28  U.S.C. § 1295(a)(1) (1994).

DISCUSSION
I.

28
Summary judgment "shall be rendered forthwith if the pleadings,  depositions, answers to interrogatories, and admissions on file, together  with the affidavits, if any, show that there is no genuine issue as to any  material fact and that the moving party is entitled to judgment as a matter  of law." Fed. R. Civ. P. 56(c); see also Vivid Techs., Inc. v. Am. Sci. &  Eng'g, Inc., 200 F.3d 795, 806-07, 53 USPQ2d 1289, 1297 (Fed. Cir. 1999);  Wolf v. Northwest Ind. Symphony Soc'y, 250 F.3d 1136, 1141 (7th Cir. 2001).  We review a grant of summary judgment without deference. Conroy v. Reebok,  Int'l, Ltd., 14 F.3d 1570, 1575, 29 USPQ2d 1373, 1377 (Fed. Cir. 1994). In  addition, we must, as the district court was required to do, draw all  reasonable factual inferences in favor of the nonmovant. Anderson v.  Liberty Lobby, Inc., 477 U.S. 242, 255 (1986); Semiconductor Energy Lab.  Co. v. Samsung Elecs. Co., 204 F.3d 1368, 1378, 54 USPQ2d 1001, 1008 (Fed.  Cir. 2000).


29
Determination of a claim of infringement involves a two step inquiry.  First, the claims are construed, a question of law in which the scope of  the asserted claims is defined. Cybor Corp. v. FAS Techs., Inc., 138 F.3d  1448, 1454-56, 46 USPQ2d 1169, 1172-74 (Fed. Cir. 1998) (en banc). Second,  the claims, as construed, are compared to the accused device. Id. This is a  question of fact. WMS Gaming, Inc. v. Int'l Game Tech., 184 F.3d 1339,  1346, 51 USPQ2d 1385, 1389 (Fed. Cir. 1999). To prevail, the plaintiff must  establish by a preponderance of the evidence that the accused device  infringes one or more claims of the patent either literally or under the  doctrine of equivalents. Id.

II.

30
We address first the parties' contentions with respect to the remaining  asserted claims that do not have any reference to a parallel relationship  as far as the "connecting elements" are concerned. Those claims are claims  11 and 12 of the '955 patent, claims 1-4, 9, and 23 of the '154 patent,  claims 1-4 of the '721 patent, and claims 1, 2, 5, 6, 9, and 11-13 of the  '158 patent.5 As seen above, the district court construed the  term "connecting elements" in the '154 and '158 patents to require the  connecting elements to be generally parallel both to each other and to the  longitudinal axis of the stent. Adv. Cardiovascular III, slip op. at 5-6.  The court applied this construction to the term "interconnected" in the  asserted claims of the '955 and '721 patents and to the terms "connecting  members" and


31
"struts for connecting" in the '893 patent.6 Adv.  Cardiovascular IV, slip op. at 8-9. Based on this construction, the  district court concluded that the NIR stent did not infringe any of the  asserted claims because the NIR stent's connecting elements were not  parallel both to each other and to the stent's longitudinal axis. Id. at  11-12.


32
ACS argues that the district court erred in its claim construction. It  asserts that none of the asserted patents ascribe any significance to the  orientation of the claimed connecting elements in relation to each other or  to the stent's longitudinal axis. ACS notes that the phrase "generally  parallel" appears nowhere in the specification, and only appears in some of  the asserted claims, specifically independent claim 12, and dependent  claims 13-15, 17, 18, and 20 of the '154 patent and dependent claim 2 of  the '158 patent. ACS points out that only the drawings of the asserted  patents show the connecting elements generally parallel both to each other  and the stent's longitudinal axis, and it contends that such a limitation,  that only appears in the drawings, should not be read into the claims. ACS  also contends that the district court gave too much weight to statements  made during the prosecution of the '986 application because the '986  application specifically claimed "generally parallel connecting elements."


33
Scimed responds that the district court's claim construction was proper.  Scimed argues that the only embodiments disclosed in the asserted patents  depict the connecting elements in parallel alignment both with each other  and with the stent's longitudinal axis. Scimed also argues that the  asserted patents emphasize the longitudinal orientation of the connecting  elements and the fact that this orientation prevents shortening and  deformation of the stent upon expansion. In light of these teachings in the  specification, Scimed asserts, the district court properly limited the  described connecting elements to connecting elements that are generally  parallel both to each other and to the stent's longitudinal axis. Scimed  also argues that the inventors expressly disclaimed non-parallel connecting  elements during prosecution by indicating that the "invention," not just  the claims in the '986 application, was distinguishable from the Palmaz  '417 patent because the Palmaz '417 patent disclosed connectors that were  not parallel to the stent's longitudinal axis and therefore deformed upon  expansion.


34
We agree with ACS that the district court erred in construing "connecting  elements" and the similar terms "interconnected," "connecting members," and "struts for connecting" by requiring the stent's connecting elements to be  generally parallel both to each other and to the stent's longitudinal axis.  We reach this conclusion based on the intrinsic evidence of record-the  claims, the specification, and the prosecution history, Vitronics Corp. v.  Conceptronic, Inc., 90 F.3d 1576, 1582, 39 USPQ2d 1573, 1576 (Fed. Cir.  1996).


35
We begin our analysis with the claim language. Pitney Bowes, Inc. v.  Hewlett-Packard Co., 182 F.3d 1298, 1305, 51 USPQ2d 1161, 1165 (Fed. Cir.  1999) ("The starting point for any claim construction must be the claims  themselves."). In that regard, none of the claims presently under  discussion require the recited "connecting elements," "interconnected"  members, "connecting members," or "struts for connecting," to be "generally  parallel" both to each other and to the stent's longitudinal axis. For  example, independent claim 1 of the '154 patent simply recites "a plurality  of connecting elements." '154 patent, col. 8, l. 43. The claim continues,  indicating that the connecting elements are "configured to interconnect  only said cylindrical elements that are adjacent to each other . . . ."  Id., col. 8, ll. 44-46. The claim has no other express structural  limitations on the claimed connecting elements. In contrast, independent  claim 12 of the '154 patent, which is discussed in Part III below, recites  "a plurality of generally parallel connecting elements . . . ." Id., col.  9, l. 28 (emphasis added). Claim 12's language includes an express  limitation on the described connecting elements, that they be generally  parallel. Based on the claim language alone, the term "connecting  elements," and the terms "interconnected," "connecting members," and  "struts for connecting," are not limited to those connectors that parallel  each other and the stent's longitudinal axis.


36
The specification further supports not requiring the connecting elements  described in the asserted claims to be generally parallel both to each  other and to the stent's longitudinal axis. "Claims must be read in view of  the specification, of which they are a part." Markman v. Westview  Instruments, Inc., 52 F.3d 967, 979, 34 USPQ2d 1321, 1329 (Fed. Cir. 1995),  aff'd, 517 U.S. 370, 38 USPQ2d 1461 (1996). However, "[w]hile it is true  that claims are to be interpreted in light of the specification and with a  view to ascertaining the invention, it does not follow that limitations  from the specification may be read into the claims . . . ." Sjolund v.  Musland, 847 F.2d 1573, 1581, 6 USPQ2d 2020, 2027 (Fed. Cir. 1988). Here,  the specification does not require the connecting elements be parallel to  each other and to the stent's longitudinal axis. Scimed admits that the  phrase "generally parallel" only appears in the patents in suit when it is  used in a particular claim. At the same time, the specifications of the  asserted patents do not discuss the orientation of the connecting elements  in relation to each other or to the longitudinal axis of the described  stent. Looking at the '154 patent for example, the specification's only  discussion of the connecting elements' orientation states that the  connecting elements are "disposed between adjacent cylindrical elements,"  '154 patent, col. 4, ll. 25-26, and that this adjacent placement "prevents  shortening of the stent during the expansion thereof," id. at col. 5, ll.  50-51. See also id. at col. 3, ll. 1-4 (noting that the connecting elements  should be joined at "either the peaks or the valleys of the undulating  structure of the cylindrical elements . . . . In this manner there is no  shortening of the stent upon expansion."). The specification's only other  discussion of the connecting elements' orientation indicates that it is  preferred to place them "on one side of the cylindrical element 12 . . . to  achieve maximum flexibility for a stent." Id. at col. 5, ll. 34-37.  Contrary to Scimed's assertions, none of the specifications of the asserted  patents teach that the connecting elements must be parallel both to each  other and to the stent's longitudinal axis in order to prevent the  shortening of the stent when the stent is expanded. As noted above, the  specifications teach that it is the attachment of the connecting elements  to either the peaks or the valleys of the cylindrical elements, as  demonstrated in Figures 3 and 4 of the '154 patent, not the parallel  placement of the connecting elements, that prevents shortening upon the  stent's expansion.


37
Scimed correctly notes that all of the drawings in the asserted patents  depict the connecting elements in parallel alignment both with each other  and the stent's longitudinal axis. However, this fact, by itself, does not  support adding such a limitation to the claims. See Johnson Worldwide  Assoc., Inc. v. Zebco Corp., 175 F.3d 985, 992, 50 USPQ2d 1607, 1612 (Fed.  Cir. 1999) (noting that "mere inferences drawn from the description of an  embodiment of the invention cannot limit claim terms"). Without a  "generally parallel" limitation in the claim or a discussion in the  specification about the claimed connecting elements being generally  parallel both to each other and to the stent's longitudinal axis, the  drawings' depiction of the connecting elements in parallel relationship  both with each other and the stent's longitudinal axis can not support the  conclusion that such a limitation exists. Since nothing in the  specification assigns significance to the fact that the drawings align the  connecting elements parallel both to each other and to the stent's  longitudinal axis, we will not allow this aspect of the drawings to be  imported into the claims as a limitation. See, e.g., Kraft Foods, Inc. v.  Int'l Trading Co., 203 F.3d 1362, 1367-69, 53 USPQ2d 1814, 1818-19 (Fed.  Cir. 2000) (indicating that the claim term "protecting back panel" was  limited to a "relatively stiff" panel because, in addition to other  intrinsic evidence, the specification's text described the back panel in  the patent's drawings as being "constructed of a relatively stiff  material"); Toro Co. v. White Consol. Indus, Inc., 199 F.3d 1295, 1300-02,  53 USPQ2d 1065, 1069-70 (Fed. Cir. 1999) (construing the claim term  "including" to mean "part of" and "permanently attached" because, in  addition to the patent's drawings, the specification's text stressed that  the claimed vacuum/blower's flow restriction ring was part of and attached  to the invention's air inlet cover); Wang Labs., Inc. v. Am. Online, Inc.,  197 F.3d 1377, 1382-83, 53 USPQ2d 1161, 1164-65 (Fed. Cir. 1999) (noting  that the claims were limited to a character-based protocol because of the  express teachings of such a protocol in both the patent's specification and  the drawings). In this case, the specifications only discuss the  orientation of the connecting elements in relation to the cylindrical  elements, not to other connecting elements or the stent's longitudinal  axis. Therefore, although the drawings show the connecting elements  parallel both to each other and to the stent's longitudinal axis, the  drawings do not require limiting the claimed connecting elements to a  configuration in which they are in parallel alignment both with each other  and with the stent's longitudinal axis.


38
Finally, we note that the prosecution history supports a claim construction  that does not require that the recited "connecting elements" be generally  parallel both to each other and to the stent's longitudinal axis. The  prosecution history "is often of critical significance in determining the  meaning of the claims," Vitronics, 90 F.3d at 1582-83, 39 USPQ2d at 1577,  since it may be used to determine the scope and meaning of the claims,  Alpex Computer Corp. v. Nintendo Co., 102 F.3d 1214, 1220, 40 USPQ2d 1667,  1671 (Fed. Cir. 1996).


39
The prosecution history does not support the district court's claim  construction. In prosecuting the '986 application, the inventors argued  that, in contrast to the Palmaz '417 patent's non-parallel connecting  members, "the independent claims of the present invention recite a  plurality of generally parallel connecting elements." However, when making  this argument, the inventors were referring to the specific language in the  '986 application's claims, language that recited "a plurality of generally  parallel connecting elements," to distinguish the '986 application from the  Palmaz '417 patent. As discussed below in Part III, this language appears  in other asserted claims of the '154 patent, specifically claims 12-15, 17,  18, and 20. The inventors explicitly limited their arguments to the '986  application's claims that recite "generally parallel connecting elements,"  not to claims that only recite "connecting elements." Therefore, the  arguments do not apply to the invention's connecting elements in general,  but only to connecting elements that are described, in the claims, as  "generally parallel."


40
Scimed, however, points to statements that the inventors made that  allegedly applied to their invention in general and that, therefore, were  not exclusive to the '986 application's claim language. In distinguishing  the Palmaz '417 patent, the inventors stated:


41
Moreover, Applicants' invention is superior to the stent disclosed in the Palmaz patent from a functional standpoint. As is clearly shown in Figs. 7 and 10 of the '417 Palmaz patent, due to its construction, upon expansion, the stent will substantially shorten as the slotted members of the stent body expand. Further, connecting members 100 and 102 deform upon expansion, as depicted in Figure 10, which adds to the shortening of the stent. . . .


42
The problem of stent shortening as taught by Palmaz has been solved by Applicants' invention due to its novel structure. The connecting elements of Applicants' invention are configured to "interconnect only said cylindrical elements that are adjacent to each other." Accordingly, as Applicants' stent is expanded from its first configuration to a larger configuration, the stent will not appreciably shorten . . . .


43
We reject Scimed's argument. Even if these statements could apply to the  claims that are now at issue, the inventors argued that their invention's  structure was superior to the Palmaz '417 patent because the Palmaz '417  patent allowed substantial shortening upon expansion while "[t]he  connecting elements of [the inventors'] invention are configured to  'interconnect only said cylindrical elements that are adjacent to each  other.' Accordingly, as [the inventors'] stent is expanded from its first  configuration to a larger configuration, the stent will not appreciably  shorten." The inventors thus argued that their invention was superior to  the Palmaz '417 patent because it configured the connecting elements to  join adjacent cylindrical elements. The inventors did not argue that their  invention was superior because its connecting elements were parallel to the  stent's longitudinal axis. Finally, even if parts of the '986 application's  prosecution history could be viewed as applying to asserted claims that do  not explicitly describe "generally parallel connecting elements," the  prosecution history does not support the district court's claim  construction. As discussed below in Part III, nowhere in the prosecution  history did the inventors indicate that their invention, in general,  required that the connecting elements be parallel to each other and to the  stent's longitudinal axis.


44
The district court erred in construing the claim terms "connecting  elements," "interconnected," "connecting members," and "struts for  connecting" as requiring connecting members to run parallel both to each  other and to the longitudinal axis of the stent. The court's grant of  summary judgment of no literal infringement or infringement under the  doctrine of equivalents with respect to claims 11 and 12 of the '955  patent, claims 1-4, 9, and 23 of the '154 patent, claims 1-4 of the '721  patent, and claims 1, 2, 5, 6, 9, and 11-13 of the '158 patent was based on  this incorrect construction, Adv. Cardiovascular IV, slip op. at 11-12. We  therefore vacate the district court's grant of summary judgment with regard  to those claims, and remand for further proceedings.

III.

45
In contrast to the asserted claims just discussed that only recite  "connecting elements," independent claim 12 and dependent claims 13-15, 17,  18, and 20 of the '154 patent specifically claim "a plurality of generally  parallel connecting elements." '154 patent, col. 9, l. 25 - col. 10, l. 17.  The court construed the phrase "generally parallel connecting elements" to  require the described connecting elements to run generally parallel both to  each other and to the stent's longitudinal axis. Adv. Cardiovascular I,  slip op. at 25-27. Based on this construction, the court granted summary  judgment of no literal infringement of claims 12-15, 17, 18, and 20 of the  '154 patent because it found that the connecting elements on the opposite  sides of the NIR stent are not generally parallel to each other because  they curve in opposite directions. Adv. Cardiovascular III, slip op. at 8.  The court also noted that the connecting elements of the NIR stent are not  parallel to the stent's longitudinal axis because, while the longitudinal  axis is straight, the connecting elements are curved. Id. at 9. The court  also granted summary judgment of no infringement under the doctrine of  equivalents, finding that ACS had failed to present any evidence to support  its contention that non-parallel connecting elements are insubstantially  different from the claimed generally parallel connecting elements. Id. 10-  12.


46
ACS argues that claims 12-15, 17, 18, and 20 of the '154 patent only  require the connecting elements to be generally parallel to each other, not  to the stent's longitudinal axis. ACS asserts that, under this  construction, the NIR stent's connecting elements meet the "generally  parallel" limitation because, while curved, they are still parallel to each  other. Scimed responds by arguing that the district court properly  construed "generally parallel connecting elements" to require the  connecting elements be parallel both to each other and to the stent's  longitudinal axis. Relying upon this construction, Scimed asserts that the  NIR stent cannot infringe because its connecting elements are curved,  making them non-parallel to each other and to the stent's longitudinal  axis.


47
We conclude that the district court erred in construing claims 12-15, 17,  18, and 20 of the '154 patent as requiring connecting elements that run  parallel to the longitudinal axis of the stent. These claims simply recite  "generally parallel connecting elements." See, e.g., id. at col. 9, l. 28.  The claims contain no language explicitly requiring the connecting elements  to be parallel to the longitudinal axis of the stent. In addition, as noted  above in Part II, there is no support for such a construction in the '154  patent's specification or drawings.


48
Scimed, however, points to the prosecution history. It argues that the  inventors distinguished their invention over the disclosure of the Palmaz  '417 patent on the ground that the Palmaz '417 patent disclosed connecting  members that were not parallel to the longitudinal axis of the stent. The  prosecution history does not support this argument.


49
It is important to recognize exactly what the inventors stated with respect  to the Palmaz '417 patent and their invention, as disclosed in the '986  application:


50
The '417 Palmaz patent discloses connector members 100 which are preferably disposed in a "non-parallel" relationship with respect to the longitudinal axis of adjacent grafts or prosthesis 70. . . . As seen in Figures 7-10 of Palmaz, each of the connector members 100 and 102 are disposed in a non-parallel relationship with respect to the longitudinal axis of the adjacent prosthesis 70.


51
* * *


52
[T]he independent claims of the present invention recite "a plurality of generally parallel connecting elements" which clearly distinguish over the preferred "non-parallel" connecting members 100 of the '417 Palmaz patent.


53
Figures 7, 9, and 10 from the Palmaz '417 patent are as follows:


54
[Tabular or Graphical Material Omitted]


55
The inventors did not argue that connecting members 100 and 102 are in a  non-parallel relationship with the longitudinal axis of what would be the  "stent" in Palmaz, which is designated by the number 70'. See Palmaz '417  patent col. 12, ll. 15-17 (stating that "graft or prosthesis, 70' is  illustrated as including three grafts, or prostheses, 70, flexibly  connected to one another by connecting members 100"). Rather, they argued  that connecting members 100 and 102 were in a non-parallel relationship  with "graft" or "prosthesis" elements 70. In other words, the inventors  were not saying that their invention was distinguished from the Palmaz '417  patent because Palmaz had connecting members that were not parallel to the  longitudinal axis of the stent, which, by inference, their invention did.  Rather, they were saying that their invention, unlike the Palmaz '417  patent, see connecting members 100 and 102 in Figures 7, 9, and 10 above,  had connecting members that were in parallel alignment with the  longitudinal axis of prosthesis 70. Thus, the inventors neither stated nor  suggested during prosecution that their invention was limited to a stent in  which the connecting members were in parallel alignment with the  longitudinal axis of the stent.7


56
As already seen, the district court based its grant of summary judgment of  non-infringement on two aspects of the NIR stent: that the stent's  connecting elements are not parallel to each other and are not parallel to  the stent's longitudinal axis. While claims 12-15, 17, 18, and 20 of the  '154 patent do not contain the latter limitation, neither party disputes  that the claims require the former limitation-that the connecting elements  be parallel to each other. When determining whether this limitation had  been infringed, the district court noted that, "[w]hen the elements of the  stent have been cut from [a] flat sheet, the 'connecting elements' in any  particular row would be parallel to one another," but "[w]hen the sheet is  rolled to form the finished stent, however, the NIR stent's 'connecting  elements' are not aligned in the same manner [because] '[c]onnecting  elements' on opposite sides of the cylinder run in opposite directions . .  . ." Adv. Cardiovascular III, slip op. at 8. The court thus concluded that,  for purposes of infringement, it was required to look at the finished  stent, and that in the finished NIR stent, the connecting elements are not  generally parallel to each other. Id.


57
ACS does not dispute the district court's description of the NIR stent's  connecting elements. Nor, as just noted, does ACS dispute the district  court's construction that the claims require the connecting elements to


58
be  generally parallel to each other. Instead, ACS argues that the district  court's analysis as to whether the connecting elements are actually  parallel to each other uses the wrong frame of reference. ACS asserts that  the correct frame of reference for comparing the connecting elements is not  a linear plane cutting through opposite sides of the stent, but a  cylindrical plane following the surface of the stent. ACS argues that along  the cylindrical plane of the stent, the connecting elements are parallel to  each other. ACS notes that, during prosecution, the examiner considered the  Palmaz '417 patent's connecting elements, which are slanted, to be  parallel, further supporting its argument that the NIR stent's connecting  elements, which are also not straight, are parallel. Scimed responds that  the connecting elements on the opposite sides of the NIR stent are not  parallel to each other because, when looking through the stent, they curve  in opposite directions. Therefore, Scimed contends, the NIR stent cannot  infringe.


59
The parties' arguments present a question of claim construction. Neither  partydisputes the shape of the NIR stent's connecting elements or that  claims 12-15, 17, 18, and 20 of the '154 patent require the connecting  elements be generally parallel to each other. What the parties do dispute  is the manner in which the connecting elements are required to be parallel.  ACS argues that the connecting elements only need to be parallel to each  other as they are compared when looking around the cylindrical surface of  the stent, while Scimed and the district court compare connecting elements  by looking through the side of the stent. Nothing in the intrinsic evidence  of record suggests that one method of determining parallelism is correct  over the other. The claims simply recite "a plurality of generally parallel  connecting elements," providing no indication of the frame of reference in  which the connecting elements should be parallel to each other. As noted in  Part II, supra, the specification does not mention the connecting elements  being parallel. The drawings show parallel connecting elements, but the  connecting elements in the drawings are straight lines, which are parallel  to each other in both a cylindrical plane and a linear plane. ACS correctly  notes that the prosecution history contains statements by the examiner that  the Palmaz '417 patent's connecting elements, which would not be parallel  under Scimed's construction, are generally parallel to each other, but  these statements alone do not support ACS's construction. There are no  statements by the inventors, or the examiner, that indicate the specific  manner in which the connecting elements are required to be generally  parallel to each other.


60
When "intrinsic evidence is insufficient to enable the court to determine  the meaning of the asserted claims," resort may be had to extrinsic  evidence. Vitronics, 90 F.3d at 1584, 39 USPQ2d at 1578. Extrinsic evidence  will be particularly helpful in this case when construing the claims and  properly determining what it means to someone skilled in the art to require  the connecting elements to be "generally parallel" to each other. Pitney-  Bowes,182 F.3d at 1308-09, 51 USPQ2d at 1168.


61
For the foregoing reasons, we vacate the district court's grant of summary  judgment of non-infringement of claims 12-15, 17, 18, and 20 of the '154  patent. On remand, the district court may consider extrinsic evidence,  "such as expert testimony, inventor testimony, dictionaries, and technical  treatises and articles," Vitronics, 90 F.3d at 1584, 39 USPQ2d at 1578, in  order to determine in what manner the connecting elements should be  "generally parallel" to each other.

CONCLUSION

62
The district court erred in construing the claim terms "connecting  elements," "interconnected," "connecting members," and "struts for  connecting" by improperly requiring the connecting elements to be both  generally parallel to each other and to the stent's longitudinal axis. We  therefore vacate the court's grant of summary judgment of no literal  infringement or infringement by equivalents of claims 11 and 12 of the '955  patent, claims 1-4, 9, and 23 of the '154 patent, claims 1-4 of the '721  patent, and claims 1, 2, 5, 6, 9, and 11-13 of the '158 patent, which was  based solely on this erroneous construction. We additionally hold that the  district court erred in construing the phrase "generally parallel  connecting elements" in claims 12-15, 17, 18, and 20 of the '154 patent to  require the connecting elements to be generally parallel to the stent's  longitudinal axis. We vacate the court's grant of summary judgment of non-  infringement of these claims because the particular way in which the claims  require the connecting elements to be generally parallel to each other is  unclear, based solely on the intrinsic evidence of record. We affirm the  district court's grant of summary judgment of non-infringement of claims 10  and 21 of the '154 patent, claims 14-16, 19, and 20 of the '158 patent, and  claims 1, 2, and 4-13 of the '893 patent. The case is remanded to the  district court for further proceedings consistent with this opinion.


63
AFFIRMED-IN-PART, VACATED-IN-PART, and REMANDED.

COSTS

64
Each party shall bear its own costs.



Notes:


1
The  '955  patent was subject to a reexamination, but the   two  claims  asserted  by  ACS  in  this case, claims 11 and 12, were allowed  unamended, at the conclusion of the reexamination.


2
 ACS  argues  that  the  district  court's construction of   "projecting  edges"  is erroneous.  However, the construction of this term did  not form the basis for any judgment of non-infringement by the district court.   Since this claim construction is irrelevant to the judgment that is on appeal,   we will not address whether the  construction  was correct.  See Phonometrics,  Inc. v. N. Telecom Inc., 133 F.3d 1459, 1464,  45 USPQ2d 1421, 1425 (Fed. Cir.1998) (noting that any construction, by a district court  or  this court, of a claim term that is not at issue is "merely dictum, and therefore  has no issue preclusive effect").


3
 ACS  does  not  appeal  the  grant  of  summary  judgment   relating  to  the  '893 patent.  Accordingly, the district court's judgment of non-infringement of  claims  1,  2,  and 4-13 of the '893 patent, the asserted claims of that patent, is left undisturbed.


4
 ACS  does  not  appeal  this  finding.   Accordingly, the   district  court's judgment of non-infringement of claims 10 and 21 of the '154 patent and  claims  14-16,  19,  and  20  of  the  '158  patent  also  is left undisturbed.


5
 We  note  that  claim  2  of the '158 patent specifically   requires  the connecting elements be "generally parallel to each other."  '158 patent, col.  8,  ll.  64-65.   However,  the  district  court granted summary judgment of non-infringement of this claim based on its construction  of  the term "connecting elements" alone.  Adv. Cardiovascular IV, slip op.  at 11-12.  Therefore,  we  will handle summary judgment of non-infringement of claim 2 of the '158 patent specifically   the '158 patent in  this part of the opinion, which discusses the construction of "connecting elements"  and  the  grant  of  summary  judgment  based on the construction of that term.


6
 As  noted above, ACS does not appeal the grant of summary   judgment of non-infringement relating to the '893 patent.


7
 After  the statements cited above were made, the examiner   responded  that  "there  is  no  limitation  of  the  claim which requires the connector members to be parallel to the longitudinal axis of  the  stent; only that the connector members are 'generally parallel'."  This response  by  the examiner   examiner  further supports our conclusion that the inventors were not defining   "generally  parallel connecting elements" to mean connecting elements that are  parallel to the stent's longitudinal axis.


