Quick Access to Top Providers of any "Popular" Part B CPT Code. OpenMedicare.US

 CMS group "Data.CMS.Gov" has an elaborate website for payments to providers by CPT code.  It's a little tricky to use but powerful.  Find it here:

https://data.cms.gov/provider-summary-by-type-of-service/medicare-physician-other-practitioners/medicare-physician-other-practitioners-by-provider-and-service

There's a nonprofit website OpenMedicare.US, that lets you look up the providers of any CPT code in a simple way.

https://www.openmedicare.us/procedures/81479

You can go here:

https://www.openmedicare.us/procedures

and then scroll down to "search by code or description."  Note, however, they only provide "top 500 codes" and that's among all procedures, not just lab procedures.  

For example, 81479 (unlisted code) makes the top 500, as does 88342 (IHC), while 81162 (BRCA) does not.  When you can't get granular listings, it still offers you the national spend.  

Here's top data for 88342 IHC: