Although we don't believe in timing the market or panicking over market movements, we do like to keep an eye on big changes -- just in case they're material to our investing thesis.

What: Shares of RadNet (NASDAQ:RDNT) are trading more than 18% higher today thanks to the company's bottom-line beat in earnings released before the opening bell.

So what: RadNet's revenue came in at $168.9 million for the first quarter, which was a weaker result than the $173.5 million Wall Street analysts had projected. However, investors were willing to overlook that miss because RadNet reported a loss of only $0.03 per share, well ahead of the $0.06 loss per share Wall Street had expected. The company pointed out that bad weather on the East Coast affected its business, as 1% fewer MRIs, and 3% fewer PET/CT scans, were performed than were performed a year ago. Same-center procedures also showed a 1% year-over-year decrease in CT scan volume and a 1% decrease in overall procedure volume.

RadNet remains optimistic about its upcoming quarters, as it raised full-year EBITDA guidance by $2 million on both low and high ends to a range of $112 million to $122 million, with its free cash flow generation guidance also boosted by $4 million on low and high ends to a range of $34 million to $44 million. Revenue guidance remains unchanged in a range of $700 million to $730 million for the full year.

Now what: RadNet's shares have been strapped to a rocket all year, and have now nearly quadrupled from their closing price at the start of 2014. The midpoint of Radnet's free cash flow guidance range now gives shares a forward price-to-free-cash-flow ratio of just 6.7, which is quite low, even after so much rapid growth. It's generally smart to be cautious around any stock that's gained so much so quickly, but RadNet gave investors great news today, and there could be much more growth in store if the company can meet its targets, and raise loftier targets next year.

Alex Planes has no position in any stocks mentioned. The Motley Fool has no position in any of the stocks mentioned. Try any of our Foolish newsletter services free for 30 days. We Fools may not all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy.