I agree that this seems at most to be a borderline case on its face, and 10% is not an unusual percentage similarity for non-plagiarized work.
However, there are some things counting against you:
First, I suspect that your work here may not be meeting the learning goals of the course. Typically, you should be able to synthesize multiple sources for a college-level presentation. Relying so much on one source suggests that you haven't made a unique presentation, rather, you've found someone else's presentation and summarized it. Possibly the topic you've chosen is too generic.
Second, it does seem that you've directly copied from the source rather than internalizing the concepts and generating text in your own words. For example, the source states "MRI is relatively expensive, requires longer imaging times than CT and may not be immediately available in all areas"; you transformed this into two bullet points "MRI is relatively expensive/requires longer imaging times than CT". It seems likely to me that you did in fact copy these phrases directly, or perhaps wrote them down verbatim in your notes as bullet points and then copied those into your writing. If, instead, you read this article, internalized it, and then reproduced it, your bullet points might have been "Cost" and "Long imaging times". These are not concepts that can only be expressed one way. The more times you choose exactly the same wording, the more it appears that you've taken the source verbatim and then tried to adjust the language to evade plagiarism detection. I still think you're in a sufficiently grey area where I'd have trouble arguing you should see a substantial penalty for this, but it might be worth a warning to be more careful in the future.
Finally, and this is I think the most damning, your words come in exactly the same order as the source. All of them. You have taken the exact order and structure of the original source. This is not merely a reproduction of selected phrases from another article, all of the words bolded in red occur in exactly the same order in the source as in your work. There is no reasonable way this would occur in exactly the same sequence if you did not copy from the article. Further, even more of the content is substantially identical than was directly flagged. You write "MRI machines have enclosed, tight spaces that can trigger claustrophobia in people without anxiety or phobias". The original source sentence is "...MRI machine is a tight, enclosed space that can trigger claustrophobia even in patients without preexisting phobias or anxiety". All you have done is changed verbs (machine is -> machines have), rotated some words (tight, enclosed -> enclosed, tight; phobias or anxiety -> anxiety or phobias), and used synonyms in context (patients -> people). This is not acceptable, it looks like you're just trying to beat a plagiarism checker.
I think what you did is to copy the article you are citing and then go through, line by line, remove some of the words and insert your own. Some may argue it does not represent plagiarism in the worst form, but to me it is a dishonest representation of original work. This is not an acceptable way to write an academic paper. You can avoid this in the future by first reading from multiple sources and learning about your topic, then writing from your own memory about the subject, supporting your work with citations and quotes from what you've read. One way I was taught to do this in grade school was to use note cards where you express a concept and a source on each card, and then use those cards independently of your references to compose an essay.
I don't know whether you intentionally plagiarized to make your assignment easier, or if you've learned incorrectly what the academic standards for plagiarism are. It is important that you recognize that you are not being accused because there is some 10% overlap detected by an automatic plagiarism detector, which may be perfectly defensible, but because you've lifted an entire article on the subject and merely modified it to appear like it's different. I'm also wary to advise what you should do about this accusation, because it depends a lot on how your instructor and institution will behave. I think in the best case, you will admit how you have crafted this work, recognize that what you thought was acceptable behavior is not, and re-do the assignment or an equivalent the correct way and be assessed on that assignment. If this is the first time you've been sanctioned for plagiarism, I think it would be fair to let this additional work be your primary punishment, and not have your final grade be affected. I don't know how consistent this outcome will be with the policies at your institution.
I've thought about this some more, and I really think the evidence is strong enough that you've plagiarized that I think your best option is to admit you've closely paraphrased your work from one source, to make a case that you did not previously understand this action was plagiarism, and that you now understand this is not acceptable and that you will correct this in the future. The best way to demonstrate this would be to redo the assignment appropriately, clearly explain what it is that you did wrong (without excuses or "to be honest I didn't plagiarize"), and ask offer additional work to demonstrate meeting the learning objectives of the course. I think the hardest part will be re-learning your understanding of plagiarism. Here are some references that may help you:
https://www.bristol.ac.uk/arts/exercises/referencing/page_05.htm
https://integrity.mit.edu/handbook/academic-writing/avoiding-plagiarism-paraphrasing (see "unacceptable paraphrase" example #5)
https://writing.wisc.edu/handbook/assignments/quotingsources/ (see the "Word-for-Word Plagiarism" and "A Patchwork Paraphrase" sections)
If I were involved in this hearing, I would be least likely to advise strong penalties against you if you:
Completely re-did the assignment correctly before the hearing, and submitted this version to your instructor
Explain coherently the issue of close paraphrasing and how you have learned that it is plagiarism to reuse the sentences and structure of someone else's work even if you substitute words. Your best option may be to write an additional essay on what close paraphrasing is, in your own words, citing sources appropriately.
Promise that you've learned from this and won't do it again
Frankly, if you use the excuses you've tried to use here in the comments and chat, I would have very little sympathy, especially as you have had previous accusations of plagiarism and seem to have made little effort since then to learn what you've done wrong.
