Positron emission tomography and optical tissue imaging

1

POSITRON EMISSION TOMOGRAPHY AND OPTICAL TISSUE IMAGING

The United States of America may have certain rights to this invention under Management and Operating Contract DE-AC05-060R23177 from the United States Department of Energy.

FIELD OF THE INVENTION

The present invention relates to positron emission tomography (PET) imaging and more particularly to a combined PET and optical imaging system for the rapid determination of adequate cancerous tissue resection and surgical margins during surgical procedures for the removal of cancerous tissue.

BACKGROUND OF THE INVENTION

During cancer surgeries, one of the important concerns is to determine if there are satisfactory surgical margins around the cancerous tissue. Ideally, the surgeon Would like to remove all of the tumor, With adequate margins around the cancerous tissue, but Without taking out too much of the healthy surrounding tissue. Typically, after the lesion is surgically removed, the tissue is sent to a pathology lab to determine if the margins around the cancer are suflicient. This process can take 20-30 minutes or more to get a confirmation that the tumor has been excised and that there are adequate surgical margins. During that time, the surgeon(s) must Wait for confirmation. If the margins are not adequate, this process may be repeated several times before the surgery is concluded, adding substantial idle time to the surgery. For the patient, the time lost during this process results in increased time in surgery and extended exposure to anesthesia, Which can result in increased morbidity. Increased surgical time can also lead to overall increased costs for the procedure.

It Would therefore be highly desirable to have a method and apparatus for rapidly determining if adequate cancerous tissue resection has been made and adequate surgical margins alloWed during surgical procedures for the removal of cancerous tissue.

OBJECT OF THE INVENTION

It is therefore an object of the present invention to provide a method and apparatus for the rapid determination of the boundaries of cancerous tissue and the determination of the presence of adequate margins thereabout after resection dur

ing surgery. SUMMARY OF THE INVENTION

According to the present invention there is provided a mobile compact imaging system that combines both PET and optical imaging into a single system Which can be located in the operating room (OR) and provides faster feedback to determine if a tumor has been fully resected and if there are adequate surgical margins. While the final confirmation is obtained from the pathology lab, such a device can reduce the total time necessary for the procedure and the number of iterations required to achieve satisfactory resection of a tumor With good margins.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially phantom perspective vieW of the imaging system of the present invention.

2

FIG. 2 is a partially phantom perspective vieW of the module mounting and co-registration fixture With sample-tray guides of the imaging system of the present invention.

DETAILED DESCRIPTION

Positron Emission Tomography With F-18 fluoro-deoxyglucose (FDG) has been shoWn to be a valuable tool for imaging various cancers. Many cancers demonstrate increased glucose metabolism compared to normal tissues. When FDG is injected intravenously, it concentrates in tumors alloWing them to be imaged. In the protocol used in connection With the imaging system of the present invention, one hour before surgery, the patient is injected With a small amount of a positron emitting radiopharmaceutical such as FDG. When the surgeon has removed the cancerous lesion, he or she Will mark the resected tissue and the surgical bed With dyes to map orientation for analysis of margins.

The Positron Emission Tomography (PET) Tissue Sample Imager of the present invention uses a pair of small PET cameras to image radiotracer uptake in the resected tissue sample. The cancerous tissue Will typically be identified as a focal area or areas of increased radiotracer accumulation Within the sample. The PET Tissue Sample Imager of the present invention also alloWs for obtaining a co-registered optical image of the tissue sample. The metabolic PET image demonstrating radiotracer accumulation is fused onto the optical image for display. Evaluating the fused images in tWo different 90° orientations alloWs the surgeon to determine if there are adequate margins of normal tissue around the tumor or if further intervention is required. This approach also alloWs the surgeon to observe the physical location of tissue Within the patient by observation of the optical image. This process can be completed in just a feW minutes in the operating room thus eliminating the need for iterative pathological examinations.

Referring noW to the accompanying draWings, the dualmodality, mobile imager of the present invention 10 comprises:

1) a planar PET imager 12 that typically, but not necessarily, exhibits a 10 cm><20 cm field of vieW and ~1.5-3.0 mm planar reconstruction resolution;

2) a PET module mounting and co-registration fixture With sample-tray guides 14;

3) an optical camera 16;

4) a tissue sample tray 18;

5) a mobile gantry compatible With an operating room environment 20;

6) an optional arm With PET imager mount 22;

7) a computer 34 With monitor 24, keyboard 26 and mouse 28;

8) imager electronics With loW voltage and high voltage poWer supplies 30;

9) a PET module data acquisition system 32;

10) data acquisition and processing softWare loaded on computer 34;

11) image fusion softWare loaded on computer 34; and

12) a UPS/ isolation transformer 36.

Several PET imaging technologies can be implemented in planar PET imager 12 of the present invention. The preferred general type of apparatus Will have a scintillator as a sensor/ energy converter of the 511 keV annihilation gamma rays, While different photodetectors Will serve as detectors of the scintillation light produced by the absorbed 511 keV gamma rays in the scintillator gamma sensor. The scintillator sensor can be made of pixellated or plate crystal scintillator materials such as LSO, LYSO, GSO, BGO, LaBr3, NaI(Tl), CsI(Tl),