Feature: Accounting for hypoxiaA PET-based possibility

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Fused image of paired perfusion-hypoxia imaging. Matched image sets of the perfusion marker Hoechst 33342 (blue; A) and the hypoxia marker EF5 (red; B).
Image source: Mol Cancer Ther 2007;6(11):2900-2908.

One of the variables with the effects of cancer is hypoxia, and a PET-based imaging technique may be capable of measuring and mapping it. Researchers at Washington University in St. Louis are focusing on two aspects of the investigational PET probe Cu-62 ATSM for hypoxia imaging.

One is to address the logistical and technical complexities associated with performing the scans. The other is to measure the effects of hypoxia on the prediction of patient outcomes. Hypoxia, or hypoxiation, occurs when the body as a whole (generalized hypoxia) or a region of the body (tissue hypoxia) is deprived of adequate oxygen supply.

Similar questions are being posed at Cedars-Sinai in Los Angeles in early human studies of HX-4 (F18 FMISO), a promising PET-based hypoxia probe in development by Siemens Molecular Imaging. The agent is helping researchers determine if higher radiation doses will overcome hypoxia.

Improved instrumentation and better imaging reconstruction software also could improve the accuracy and reproducibility of radiation therapy response measurement, Habib Zaidi, PhD, head of the PET instrumentation and neuroimaging laboratory at Geneva University Hospital in Switzerland, said in an interview. He stressed the need for treatment planning software that would allow for the importation and realignment of functional PET images and display of standard uptake value (SUV) units for user-defined automatic thresholding.

Zaidi noted some investigators believe PET/MRI could replace PET/CT as a platform of choice for measuring therapeutic response. The new hybrid whole-body systems promise to improve the presentation of soft tissue and provide blood flow measures and spectroscopic measures of tissue metabolism to combine with PET’s molecular imaging capabilities.

In an interview, Roland Hustinx, MD, PhD, nuclear medicine chair at the University Hospital of Liege in Belgium, agreed that much more work still needs to be done. “It is complicated. It is difficult. It will take more time, but I think we are getting there,” he said.