Advanced Cardiovascular Systems, Inc. (ACS) appeals the decision of the United States District Court for the District of *1071Minnesota, Advanced Cardiovascular Sys., Inc. v. Scimed Life Sys., Inc., 697 F.Supp. 354, 8 USPQ2d 2002 (D.Minn.1988), granting the summary judgment motion of Scimed Life Systems, Inc. (Scimed) and dismissing ACS’s complaint. We vacate and remand.
BACKGROUND
ACS and Scimed are manufacturers of dilation catheters employed to enlarge arteries narrowed by cholesterol or other deposits. In using these catheters, the distal end is inserted through an artery and is maneuvered into the narrowed cavity after a separate guiding catheter has been run along a previously inserted guidewire. Once in place, the balloon at the distal end is inflated by injecting a fluid through the opposite proximal end. The inflated balloon expands to a predetermined size and shape to press against the arterial wall and enlarge the passageway. When the dilation procedure is complete, the balloon is deflated and the devices removed.
ACS, as assignee, obtained United States Patent No. 4,323,071 (’071) for a guiding and dilating catheter assembly and filed suit against Scimed, alleging that Scimed’s catheter infringed claims 1, 5, and 10-16 of the ’071 patent. Figure 1 illustrates ACS’s assembly.
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Scimed responded by denying infringement, counterclaiming for antitrust violations, tortious interference with prospective contractual relations and unfair competition, and moving, in separate motions, for summary judgment on the issues of infringement and inequitable conduct. The district court granted summary judgment of noninfringement, but denied the motion on inequitable conduct.
ISSUE
Whether the district court erred in granting summary judgment that the accused catheters do not infringe the ’071 patent.
OPINION
The dispute underlying the district court’s grant of summary judgment of non-infringement is over the meaning of the words “formed integral” and “formed therein” in the following limitations of the asserted claims:
said tubular member of said dilating catheter assembly having proximal and distal ends and an inflatable annular portion formed integral with the tubular member of said dilating catheter assembly near the distal end thereof; an inflatable annular portion formed integral with the tubular member near the distal end thereof;
said tubular member having an inflatable annular portion formed integral therewith adjacent the distal end; and said second tubular member having a balloon-shaped portion formed therein adjacent the distal end.
’071 patent, claims 1, 5, 10, 11 (emphasis added). In contending that the accused devices infringe the ’071 patent — either literally or by equivalency — ACS maintains that the terms refer to a catheter construction in which the balloon portion continues and completes the structure of the outer catheter tube and has material properties comparable to those of the tube. To support this interpretation, ACS submitted three declarations — one from each of the *1072inventors and one from an ACS expert who was allegedly one with ordinary skill in the art of catheter design — and a dictionary definition of the term “integral.” Relying solely on the specification and only part * of the patent’s prosecution history, Scimed contends that the terms mean “of one piece.” If Scimed is correct, infringement is avoided because Scimed’s catheter is constructed from separate balloon and outer tube segments. Figure 2 illustrates Scimed’s catheter.
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FIGURE 2
If ACS is correct, Scimed’s catheter might infringe, either literally or equivalently, because the balloon segment has a long tube-like skirt that is affixed by glue to the outer tube at a necked-down region. This connecting structure between the balloon and outer tube might be covered by the claims if the disputed terms require only that the balloon segment “continue and complete” the outer tube.
Although recognizing that defining “integral as meaning ‘completing and continuing the structure’ ... is logically possible” and that ACS might be able to present expert testimony in support thereof, the district court refused to consider ACS’s extrinsic evidence supporting that interpretation. Advanced, 697 F.Supp. at 360, 8 USPQ2d at 2006. The court accepted Scimed’s asserted definition, relied solely on the specification and the incomplete prosecution history, and, for infringement (both literal and under the doctrine of equivalency), limited the terms to describe a catheter of unitary and adhesive-free construction. Id. at 359, 8 USPQ2d at 2005.
In a different case, the Court of Customs and Patent Appeals (CCPA) refused to confine the term “integral” to mean “one-piece.” In re Hotte, 475 F.2d 644, 647, 177 USPQ 326, 329 (CCPA 1973). In Hotte, the CCPA expressly rejected the appellant’s argument “that the requirement that the [claimed electrical] leads be ‘integral’ with the plate elements distinguishes from any structure requiring the attachment of leads” and held that “ ‘integral’ is sufficiently broad to embrace constructions united by such means as fastening and welding.” Id. We, of course, do not hold that “integral” can never mean “one-piece,” but only conclude that the disputed terms are not so common and so ordinary that their meaning could never be seriously disputed.
The meaning of the disputed terms here is not clear from the specification, the incomplete prosecution history, and the other claims. Cf. General Elec. Co. v. United States, 572 F.2d 745, 751, 198 USPQ 65, 70 (Ct.Cl.1978) (recognizing that summary judgment is appropriate if the meaning of a claimed term is made incontrovertibly clear in the patent or in the file wrapper). The claims and the specification do not define the terms, and the phrase “one-piece construction” was never used during prosecution.
Although the district court and the dissent in construing the terms use certain *1073prosecution statements to distinguish the Nozick and Taricco patents, according to ACS (and left undisputed by Scimed) neither of those patents were part of the summary judgment record. Without having the references before it, the district court could not have properly interpreted the implications of any arguments made to overcome them. See Water Technologies Corp. v. Calco, Ltd., 850 F.2d 660, 667, 7 USPQ2d 1097, 1102 (Fed.Cir.1988) (explaining that a court “must construe claims ‘in the light of the claim language, the other claims, the prior art, the prosecution history, and the specification’ ” (quoting SRI Int’l v. Matsushita Elec. Corp. of Am., 775 F.2d 1107, 1118, 227 USPQ 577, 583 (Fed.Cir.1985)) (in banc) (emphasis omitted)).
The Gruntzig patent was part of the record. It is unclear, however, whether the district court construed the Gruntzig device as having an inner tube, a concentric outer tube, and a balloon glued onto the outer concentric tube. As can be seen below from the labeled version of Gruntzig’s figure 2, that interpretation would be incorrect.
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Moreover, the district court and the dissent also construe the terms as requiring a single-piece construction by relying on certain statements made to allegedly distinguish the Gruntzig patent. None of the statements, however, aids in interpreting the terms because the statements themselves use the disputed terms “formed integral” and “formed therein” without any illuminating definition, and nothing in the Grunt-zig patent sheds light on their meaning.
This is a case where expert testimony is “particularly helpful” because the meaning of the disputed terms is not readily apparent from the patent and its incomplete prosecution history. See Moeller v. Ionetics, Inc., 794 F.2d 653, 657, 229 USPQ 992, 995 (Fed.Cir.1986); see also Snellman v. Ricoh Co., 862 F.2d 283, 287, 8 USPQ2d 1996, 2000 (Fed.Cir.1988) (using expert testimony to explain the meaning of technical terms), cert. denied, — U.S. -, 109 S.Ct. 3199, 105 L.Ed.2d 707 (1989); Tandon Corp. v. United States Int’l Trade Comm’n, 831 F.2d 1017, 1021, 4 USPQ2d 1283, 1286 (Fed.Cir.1987) (directing that “[w]hen the meaning of key terms of claims is disputed, as in this case, extrinsic evidence may be adduced including testimony of witnesses”). The district court erred here in its refusal to consider ACS’s extrinsic evidence. The declarations submitted by ACS contradict Scimed’s definition of the terms. After studying the ’071 patent, the Gruntzig patent and ACS catheters of the type described in the ’071 patent, the expert witness declared that the term “ ‘integral’, as used by [the '071 patent claims] refers to [a] continuous balloon tube construction” in which “[a] balloon with comparable material properties completes and continues the structure of the outer tube at the distal end of the catheter.” One inventor declared that the disputed terms, “as used in the patent claims in the [’071] patent, do not exclude a construction in which a balloon is made as a separate part and then attached to the outer tube to continue and complete the construction of the outer tube”. The other inventor declared that “[i]t was by no means crucial to our work to have a one-piece balloon tube construction....”
The dictionary definition submitted by ACS also supports its contention. According to Webster’s, “integral” means:
1 a: essential to completeness: CONSTITUENT ... c: formed as a unit with *1074another part 2: composed of integral parts: INTEGRATED 3: lacking nothing essential: ENTIRE
Webster’s New Collegiate Dictionary 595 (8th ed. 1981). This definition does not conclusively limit “integral” to “of one piece.”
Because nothing yet made of record restricts the terms to mean “of one piece,” Scimed has failed to establish that it was entitled to summary judgment as a matter of law. See Hi-Life Prods., Inc. v. American Nat’l Water-Mattress Corp., 842 F.2d 323, 325, 6 USPQ2d 1132, 1133 (Fed.Cir.1988) (requiring both an absence of a genuine issue of material fact and entitlement to judgment as a matter of law before granting summary judgment). Accordingly, the summary judgment of noninfringement is vacated and the case remanded with instructions to reinstate ACS’s complaint. See Howes v. Medical Components, Inc., 814 F.2d 638, 647, 2 USPQ2d 1271, 1276 (Fed.Cir.1987).
COSTS
Each party is to bear its own costs.
VACATED and REMANDED.
As explained hereinafter, not all of the relevant prior art references had been made of record prior to the summary judgment grant.