AMIDE is a free, open-source software tool for multimodality medical image analysis. Developed by Andreas Markus Loening and Sanjiv Sam Gambhir, it allows researchers to display, analyze, and manipulate volumetric medical images from various modalities such as PET, CT, and MRI. The software uses on-demand data reslicing to enable simultaneous display and analysis of multiple data sets and regions of interest (ROI). AMIDE is available under the GNU General Public License (GPL), allowing free modification and redistribution. It supports UNIX, Mac OS X, and Windows platforms. AMIDE's design avoids the limitations of previous software by organizing data sets and ROIs in a tree structure, enabling unlimited simultaneous display, modification, and analysis. Data sets can be processed in non-orthogonal directions, with continuous interpolation from the original data to allow non-destructive reslicing. This feature facilitates manual alignment and fused viewing of multiple images. The software also provides a user-friendly interface, abstracting away the underlying digital representation of medical data, allowing users to view data at any angle and thickness. AMIDE includes various features useful for molecular imaging researchers, such as three-dimensional ROI drawing and analysis, two- and three-way linked viewing, rigid body registration using fiducial markers, filtering and cropping of data sets, movie generation, series viewing, and volume rendering. It supports a wide range of medical image formats and provides tools for data import, processing, and export. Validation of AMIDE was performed using a dataset consisting of PET and CT scans of a nude mouse. The software was compared with other image analysis packages, and results showed that AMIDE's ROI statistics were not significantly different from those of other packages. AMIDE's ability to handle non-orthogonal data sets and its open-source nature make it a valuable tool for the molecular imaging research community. The software is freely available, with source code and installation instructions accessible via its website. It is designed to be accessible to novice users, with a simplified interface and unit handling that allows data and statistics to be presented in real-world terms. The continuous reslicing approach, while computationally expensive, enables flexible and arbitrary image fusion capabilities. AMIDE is expected to become increasingly important as multimodality image analysis becomes more common in research. Future developments aim to extend its core features, particularly in providing interactive interfaces for advanced medical imaging algorithms.AMIDE is a free, open-source software tool for multimodality medical image analysis. Developed by Andreas Markus Loening and Sanjiv Sam Gambhir, it allows researchers to display, analyze, and manipulate volumetric medical images from various modalities such as PET, CT, and MRI. The software uses on-demand data reslicing to enable simultaneous display and analysis of multiple data sets and regions of interest (ROI). AMIDE is available under the GNU General Public License (GPL), allowing free modification and redistribution. It supports UNIX, Mac OS X, and Windows platforms. AMIDE's design avoids the limitations of previous software by organizing data sets and ROIs in a tree structure, enabling unlimited simultaneous display, modification, and analysis. Data sets can be processed in non-orthogonal directions, with continuous interpolation from the original data to allow non-destructive reslicing. This feature facilitates manual alignment and fused viewing of multiple images. The software also provides a user-friendly interface, abstracting away the underlying digital representation of medical data, allowing users to view data at any angle and thickness. AMIDE includes various features useful for molecular imaging researchers, such as three-dimensional ROI drawing and analysis, two- and three-way linked viewing, rigid body registration using fiducial markers, filtering and cropping of data sets, movie generation, series viewing, and volume rendering. It supports a wide range of medical image formats and provides tools for data import, processing, and export. Validation of AMIDE was performed using a dataset consisting of PET and CT scans of a nude mouse. The software was compared with other image analysis packages, and results showed that AMIDE's ROI statistics were not significantly different from those of other packages. AMIDE's ability to handle non-orthogonal data sets and its open-source nature make it a valuable tool for the molecular imaging research community. The software is freely available, with source code and installation instructions accessible via its website. It is designed to be accessible to novice users, with a simplified interface and unit handling that allows data and statistics to be presented in real-world terms. The continuous reslicing approach, while computationally expensive, enables flexible and arbitrary image fusion capabilities. AMIDE is expected to become increasingly important as multimodality image analysis becomes more common in research. Future developments aim to extend its core features, particularly in providing interactive interfaces for advanced medical imaging algorithms.