SCARY - A Malware can actually alter your CT/MRI Scan to show fake Tumor - A team from Israel developed the malicious software to show how easy it is to do that.

The program was able to convincingly add fake malignant growths to images of lungs taken by MRI and CT scanning machines.
How? -  Because the files were generally not digitally signed or encrypted. This means any changes would be hard to spot.

The images targeted were scans of lungs but the malware could be tuned to produce other fake conditions such as brain tumors, blood clots, fractures or spinal problems

While hospitals were careful about sharing sensitive data beyond their boundaries, they took much less care when handling data internally, said one of the researchers.

https://www.bbc.com/news/technology-47812475