Reorganizing an array: odd entries as KEY, even entries as VALUE

I'm trying to finish up a URL router that I created for my custom MVC framework. I have a list of parameters that I dissected from the URL, but the problem is that they only have numerical keys. What I want to do is set it up so the first value in the $params array will be the KEY and then the second value in the array is the VALUE of the first KEY. But I need to take it beyond that even further. Essentially, I need all odd number key's value in the array to be the new KEY and the even number key's value to be the value.

Example:

This is how it's CURRENTLY set up:

Array
(
  [0] => greeting
  [1] => hello
  [2] => question
  [3] => how-are-you
  [4] => response
  [5] => im-fine
)

This is how it NEEDS to be (after conversion):

Array
(
  [greeting] => hello
  [question] => how-are-you
  [response] => im-fine
)

Would it be easier to create this type of array when I explode the string by the '/' delimiter when I'm taking it out of the URL string? If so, what would be the best function for that?

It's probably a simple solution, because I'm sure this is a common issue, but any enlightenment?