Positron Emission Tomography

Positron Emission Tomography: Experience with PET and Synthesis of the Evidence

Executive Summary
INAHTA conducted this joint collaboration in response to an increasing global interest in the clinical potential of positron emission tomography (PET). The project documents PET use and related public health coverage in countries represented by INAHTA members and synthesizes technology assessments of PET conducted by INAHTA members and three private US organizations. It considers all PET systems, that is, conventional full ring models, newer partial ring models and SPECT cameras modified for imaging positron emitters.

PET is a functional imaging technology that uses a radioactive tracer to assess perfusion and metabolic activity in the human body. Introduced first as a research tool, PET has undergone technological advances that make it feasible for clinical use.

PET's availability is still quite limited, as evidenced by the low numbers and relative under use of scanners in each country or region. Most health systems used their PET scanners for both research and diagnostic purposes, but there were wide variations in use across systems. Local regulatory policies and the availability of private funding sources likely contributed to these differences.

The vast majority of reimbursed clinical PET activity is concentrated in relatively few health systems and is confined to comparatively few indications.

Public health systems in Australia, Switzerland, Denmark and the US (VHA) conducted 85% of the activity.

The most frequently covered PET indications, presented in descending order, were for diagnosing head and neck cancer, lung cancer and lymphoma followed closely by differentiating brain tumor from radiation necrosis and diagnosing colorectal cancer, breastcancer and melanoma.

70% of the oncology activity comprised melanoma, lung cancer staging, and an undefined category of \"other\". The vast majority of neurology activity was for distinguishing brain tumor from radiation necrosis and for localizing epileptic foci in potential surgical candidates with intractable epilepsy.

Many health systems refer to US experiences, particularly Medicare policy, to establish local reimbursement policy. In the US in 1997, supporters of clinical PET were instrumental in changing FDA regulation of PET drugs. As a result, Medicare has expanded coverage of PET scans beyond cardiac perfusion imaging to include diagnosing indeterminate solitary pulmonary nodules, recurrent metastatic melanoma and recurrent colorectal cancer and staging non-small cell lung cancer, Hodgkin's and non-Hodgkin's lymphoma.

Regarding PET's utility, evidence of diagnostic accuracy is largely based on traditional full ring PET, is limited by bias and often relates only to small patient numbers. In all of the advocated clinical indications there was uniform agreement that critical research is needed to define the clinical and economic consequences of using PET on treatment decisions and health outcome relative to other methods now in clinical use.

Many INAHTA agencies identified clinical PET as a major research priority and are initiating rigorous evaluation efforts. Most recommended that, if used at all, PET should be used under research protocols designed to evaluate PET's relative cost-effectiveness.