Nalvera.AI is the easier of the two for AI medical image segmentation: it runs in your browser, with nothing to install.
Interactive AI segmentation with mouse clicks works on Nalvera.AI in the cloud, with no GPU or plugin of your own. In 3D Slicer, it needs an AI extension (plugin) and, for practical speed, a GPU.
Create your accountHow Do Nalvera.AI and 3D Slicer Compare?
Nalvera.AI is a cloud platform for medical imaging research. Beyond segmentation and visualization, it supports clinical research studies, PET and SPECT quantification, synthetic image generation, and research reports from CT. 3D Slicer is a free, open-source desktop application for medical image visualization, segmentation, and analysis.
| Feature | Nalvera.AI | 3D Slicer |
|---|---|---|
| Runs on | Your browser, with EU-hosted GPUs | Your computer, after installation |
| AI segmentation | Built in | Through extensions (plugins) |
| Mouse-click AI | Built in, with Nalvera iSeg and NV-Segment-CT | Through extensions such as nnInteractive |
| GPU for mouse-click AI | None of your own | Yours, or a server you connect to |
| AI models | Ready to run | Downloaded on first use |
| Main speed limit | Internet bandwidth | Local hardware: GPU, processor, and memory |
| Command line | Not used | To install a GPU server |
| Correcting outlines | Adaptive 2D and 3D brushes, interpolation | Segment Editor: paint, draw, threshold, and more |
| Measurements | Across a whole study, over time and between groups | Per segment, with Segment Statistics |
| PET and SPECT quantification | Built in, for each structure | Through separate extensions |
| Cost | Free to start, then pay per use | Free, open source |
Can You Do Interactive AI Segmentation With Mouse Clicks in the Cloud?
Yes, on Nalvera.AI. Upload a CT or MRI scan, and open it in the Interactive Studio in a desktop browser. Click inside a structure to include it and outside to exclude it. GPUs in the cloud compute the 3D outline from your clicks, and each further click updates it.
Nalvera iSeg segments CT and MRI, and NV-Segment-CT offers a second model on CT. You fine-tune the outlines with advanced multi-dimensional adaptive brush tools, interpolation tools, and more.
Does 3D Slicer Need a GPU for Interactive AI Segmentation?
For practical speed, yes, and it also needs an AI extension (plugin). The built-in Segment Editor offers manual and semi-automatic tools. Interactive AI comes from extensions such as nnInteractive and MONAI Label.
The documentation of the nnInteractive extension states: "10 GB of VRAM is recommended" and "CPU is supported but slow." With no suitable GPU on your computer, you install a server on a GPU machine, from the command line or with Docker, and connect 3D Slicer to it.
How Does TotalSegmentator Run in Each?
On Nalvera.AI, you select TotalSegmentator, submit your scan, and hosted GPUs segment it at full resolution. MOOSE CT, MuscleMap MRI, MRSegmentator, and NV-Segment-CT work the same way.
In 3D Slicer, you install the TotalSegmentator extension and restart the application. The first run downloads PyTorch and the AI models, which its documentation puts at "5-10 minutes and several GB disk space." Full-resolution segmentation then takes under a minute on a GPU and about 45 minutes on a CPU. On macOS, "you need to use the CPU."
What Happens After Segmentation?
On Nalvera.AI, you continue in Study Design: create all your own variables, organize patients and scans, measure what matters to you, follow it over time, and compare groups. You can also register and overlay PET, SPECT, MRI, and CT, and extract functional imaging parameters for each structure, such as SUV. Nalvera.AI is an all-in-one research platform, from scan to study results.
3D Slicer reports measurements per segment with its Segment Statistics module. Segmentations from Nalvera.AI download as .nii.gz files, which also open in 3D Slicer.
Can 3D Slicer Run in the Cloud?
On the free Binder service, 3D Slicer runs through a Jupyter notebook. Its documentation, checked on 4 November 2026, warns that "server resources are quite limited" and that "there is no interactive access to the graphical user interface." The full application in the cloud takes a container or virtual machine that you set up yourself. Nalvera.AI runs in the cloud from your first sign-in.
How Much Do They Cost?
3D Slicer is free and open source, and you supply the hardware. Nalvera.AI is free to start: each new account gets 10 AI tasks and 5 credits a month, and one free AI task covers a whole session of clicks in the Interactive Studio. After that you pay per use, and you see the cost of each AI task before you submit it.
Try Interactive AI Segmentation in the Cloud
Create your free account, then upload your own scan or start with a sample scan.
Create your accountResearch use only. Nalvera.AI is not a medical device, and AI-generated outputs are not intended for clinical diagnosis or treatment.