Back to the original question, I'd start by trying to get copies of the docket entries in the case in which you "appeared." For starters, I doubt that the official disposition was "thrown out the window," which seldom appears in the docket entries.
The term "appear" is a bit misleading, since technically those who "appear" in any litigation in Massachusetts are (a) those attorneys who file an appearance on behalf of a party client and (b) those parties who appear on their own behalf ("pro se").
If a proceeding for a criminal motor vehicle offense was commenced, it would be technically entitled Commonwealth v. X, where X is the defendant (the person charged; you). That is most likely an "appearance," and so the answer to the question should be "Yes."
If a criminal proceeding was commenced, there are only three possible dispositions: GG (found guilty, either upon a plea, an admission of facts sufficient, or a trial); NG (found not guilty after a trial); and DIS (dismissed). The best result is NG. DIS covers a multiple of possible scenarios, ranging from dismissal for want of jurisdiction (which implies nothing either way about underlying guilt) to CWOF ("continued without a finding"), which can only enter after an admission of facts sufficient, and is taken by most folks to be the practical (if not legal) equivalent of GG.
However, there may never have been a criminal case commenced; you may have appeared before a Clerk or a Judge on an application for a criminal complaint (G.L. ch. 218, sec. 35A). After listening to the application and sworn statement in support of it, the officer may have decided not to issue a criminal complaint, which is the functional equivalent of a Grand Jury issuing a report of No True Bill, and is even better than an NG. Subject to more research and thinking about it, a person who shows up in court in response to a 218/35A probably hasn't "appeared," since the legal meaning of "appear" presupposes that there is a "proceeding" in which to "appear," and by definition until a complaint issues in response to an application for one, there is no "proceeding."
The foregoing is a longwinded response to the following effects: (A) you haven't given us enough information to answer the question, and you probably don't have the necessary information yourself; and (B) it is as likely as not that, once you get the necessary information, only a lawyer is going to be able to figure out the answer. Sorry about that.