Sequential whole-body PET/MR scanner: concept, clinical use, and optimisation after two years in the clinic. The manufacturer's perspective.

PET and MRI are established clinical tools which provide complementary information, but clinical workflow limits widespread clinical application of both modalities in combination. The two modalities are usually situated in different hospital departments and operated and reported independently, and patients are referred for both scans, often consecutively. With the advent of PET/MR as a new hybrid imaging modality there is now a possibility of addressing these concerns.

Time-of-flight PET/CT using low-activity protocols: potential implications for cancer therapy monitoring.

Introduction: Accurate quantification of tumour tracer uptake is essential for therapy monitoring by sequential PET imaging. In this study we investigated to what extent a reduction in administered activity, synonymous with an overall reduction in repeated patient exposure, compromised the accuracy of quantitative measures using time-of-flight PET/CT.

Methods: We evaluated the effect of reducing the emission count statistics, using a 64-channel GEMINI TF PET/CT system.

Image intensity normalisation by maximising the Siddon line integral in the joint intensity distribution space.

This paper presents a novel data-driven method for image intensity normalisation, which is a prerequisite step for any kind of image comparison. The method involves a novel application of the Siddon algorithm that was developed initially for fast reconstruction of tomographic images and is based on a linear normalisation model with either one or two parameters. The latter are estimated by maximising the line integral, computed using the Siddon algorithm, in the 2D joint intensity distribution space of image pairs.

Externally triggered gating of nuclear medicine acquisitions: a useful method for partitioning data.

Physiological gating in nuclear medicine image acquisition was introduced over 30 years ago to subdivide data from the beating heart into short time frames to minimize motion blurring and permit evaluation of contractile parameters. It has since been widely applied in planar gamma camera imaging, SPECT, positron tomography (PET) and anatomical modalities such as x-ray CT and MRI, mostly for cardiac or respiratory investigations. However, the gating capability of gamma cameras and PET scanners can be employed to produce multiply partitioned, statistically independent projection data that can be used in various ways such as to study the effect of varying total acquired counts or time, or administered radioactivity, on image quality and multiple observations for statistical image analyses.

Statistical pixelwise inference models for planar data analysis: an application to gamma-camera uniformity monitoring.

In this paper two tests based on statistical models are presented and used to assess, quantify and provide positional information of the existence of bias and/or variations between planar images acquired at different times but under similar conditions. In the first test a linear regression model is fitted to the data in a pixelwise fashion, using three mathematical operators. In the second test a comparison using z-scoring is used based on the assumption that Poisson statistics are valid.