Image fusion of SPECT and PET data has been shown to improve diagnostic accuracy in a variety of clinical circumstances. While the use of SPECT/CT and PET/CT image fusion has been well documented in the literature, the potential role of planar image fusion is not well documented. This brief report presents several circumstances in which planar image fusion might be useful in clinical practice. Introduction Physiological imaging using single photon emission computed tomography (SPECT) is a valuable tool in the diagnosis of many diseases but may be limited, on occasion, by poor anatomic localization (1). This limitation might be overcome using image fusion, a process of data superimposition using multiple image types; typically computed tomography (CT) or magnetic resonance imaging (MRI) for anatomic data superimposed with SPECT or positron emission tomography (PET) for functional data (1). It is not uncommon for the combined image fusion data to provide additional clinical information that was not evident from either anatomic or functional datasets; interpreted in isolation or in tandem without fusion. Image fusion of SPECT and PET data has been shown to improve diagnostic accuracy in many clinical circumstances (2). There are two main methods of performing SPECT/CT image fusion. The first employs hybrid scanner technology where a CT scanner is integrated in the gamma camera gantry to allow sequential imaging of anatomy and physiology. An alternative approach would be to perform image fusion on data acquired on individual dedicated SPECT and CT systems. While the use of SPECT/CT and PET/CT image fusion has been well documented in the literature, the potential role of planar image fusion (e.g. planar scintigraphy and radiograph) is not well documented. Merge version 2.0 is a fully functional freeware program readily downloadable over the internet. Merge 2.0 is a simple graphic utility designed to merge graphic images, including batch merging to a reference image. While these features were initially conceived for manipulation of graphics and watermarking images more easily, they readily lend themselves to merging planar scintigraphy with radiographs and applying an anatomic reference image to a dynamic scintigraphic data set. This brief report presents several circumstances in which planar image fusion might be useful. Discussion Scintigraphy to XrayPerhaps the most useful application of planar image fusion is the merging of bone scans with xrays. Combining the high spatial resolution of xrays with the physiologically sensitive bone scan assist on overcoming the limitations of each. Figure 1 presents a 14 year old male with a history of persistent tenderness of the left wrist following a fall (three weeks). The xray was reported as normal. The bone scan demonstrated increased tracer accumulation extending across the distal growth-plate of the left radius as well as the area surrounding the distal portion of the left scaphoid.
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