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Numerous Irregularities Doom Interference Holding

00-1159
July 24, 2001

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Last Month at the Federal Circuit - August 2001

Judges: Rader (author), Michel, and Lourie

In In re Roemer, No. 00-1159 (Fed. Cir. July 24, 2001), the Federal Circuit reversed-in-part, vacatedin- part, and remanded a decision of the Board that found the claims of a reissue patent application related to magnetic resonance imaging (“MRI”) unpatentable over a previously issued U.S. patent.

An MRI apparatus typically includes a main magnet, an internal imaging volume, a radiofrequency- producing (“RF”) coil, and gradient coils. The main magnet produces a background magnetic field in the imaging volume. When the RF coil is turned on, protons in a patient positioned in the imaging volume absorb energy from RF coil electromagnetic pulses. When the RF coil is turned off, these protons release this absorbed energy. The gradient coils produce a second magnetic field to provide a substantially linear magnetic field gradient acting as a reference coordinate system for the imaging volume. This reference coordinate system allows the MRI apparatus to detect the exact locations and measure the precise amounts of these energy releases, converting the results into an image. Typically, an MRI apparatus manufacturer locates the gradient coils between the imaging volume and the surrounding main magnet.

In 1988, U.S. Patent No. 4,737,716 (“the Roemer patent”) issued to Dr. Peter Roemer et al. The Roemer patent discloses a solution to a problem where the gradient coil magnetic fields adversely affect the main magnet. The solution includes second coils located between the corresponding gradient coils and the main magnet. The magnetic fields of these second coils essentially cancel that of the gradient coils outside of the second coils, thus eliminating these adverse effects.

In 1989, Dr. Roemer filed a reissue application, copying claims to intentionally provoke an interference with U.S. Patent No. 4,733,189 (“the Punchard patent”). Later, the Administrative Patent Judge (“APJ”) added U.S. Patent No. 4,978,920 (“the Mansfield patent”) to the interference.

Although a count in an interference should only read on patentable subject matter, the APJ found the single count of the interference unpatentable over U.S. Patent No. 4,595,899 (“the Smith patent”). The Smith patent discloses an MRI apparatus that includes second coils to essentially cancel the main magnet’s magnetic field outside of the main magnet, a different purpose than the Roemer reissue application and the Punchard and Mansfield patents.

In a departure from normal interference procedure, the parties conceded that any claims corresponding to the count were unpatentable over the Smith patent. Armed with this concession, the APJ had concluded that all claims of the Roemer reissue application, including all claims copied from the Punchard and Mansfield patents, corresponded to the count and were unpatentable over the Smith patent.

Only Dr. Roemer appealed this determination. Despite the fact that interference rules limit determinations of patentability to claims, not counts, Dr. Roemer’s appeal accepted the APJ’s determination that the single count of the interference was unpatentable over the Smith patent. Instead, his appeal focused on whether sixteen specific claims of the Roemer reissue application corresponded to the count.

The Federal Circuit read a portion of the preamble of an independent claim to require a substantially linear magnetic field gradient. The Court also contrasted the Roemer reissue application’s complex canceling of the gradient coils’ magnetic field outside of the second coils with the Smith patent’s simpler canceling of the main magnet’s magnetic field outside of the main magnet. The Federal Circuit found that the Board had erred in its conclusion that six of the claims of the Roemer reissue application corresponded to the count and, thus, were unpatentable over the Smith patent and reversed that portion of the Board’s holding. Additionally, because the Board had failed to make any findings of fact regarding the remaining ten appealed claims of the Roemer reissue application,
the Federal Circuit vacated and remanded the related portion of the Board’s holding.