Exhibit 3.81

Delaware	PAGE 1
The First State

     I, JEFFREY W. BULLOCK, SECRETARY OF STATE OF THE STATE OF DELAWARE, DO HEREBY CERTIFY THE ATTACHED ARE TRUE AND CORRECT COPIES OF ALL DOCUMENTS ON FILE OF “DANVILLE DIAGNOSTIC IMAGING CENTER, LLC” AS RECEIVED AND FILED IN THIS OFFICE.

     THE FOLLOWING DOCUMENTS HAVE BEEN CERTIFIED:

     CERTIFICATE OF FORMATION, FILED THE FIFTEENTH DAY OF JUNE, A.D. 2005, AT 12:54 O’CLOCK P.M.

     AND I DO HEREBY FURTHER CERTIFY THAT THE AFORESAID CERTIFICATES ARE THE ONLY CERTIFICATES ON RECORD OF THE AFORESAID LIMITED LIABILITY COMPANY, “DANVILLE DIAGNOSTIC IMAGING CENTER, LLC”.

3985585     8100H		/s/ Jeffrey W. Bullock
110292378 You may verify this certificate online at corp. delaware.gov/authver.shtml		Jeffrey W. Bullock, Secretary of State AUTHENTICATION: 8619907 DATE: 03-14-11

Sate of Delaware
Secretary of State
Division of Corporations
Delivered 01:30 PM 06/15/2005
FILED 12:54 PM 06/15/2005
SRV 050499375 — 3985585 FILE

Certificate of Formation
of
Danville Diagnostic Imaging Center, LLC

     The undersigned, an authorized natural person, for the purpose of forming a limited liability company, under the provisions and subject to the requirements of the State of Delaware, particularly Chapter 18, Title 6 of the Delaware Code and the acts amendatory thereof and supplemental thereto, and known, identified, and referred to as the Delaware Limited Liability Company Act (the “Act”), hereby certifies that:

     FIRST: The name of the limited liability company is Danville Diagnostic Imaging Center, LLC (the “Company”).

     SECOND: The address of the registered office and the name and address of the registered agent of the Company required to be maintained by Section 18-104 of the Act is The Corporation Trust Company, Corporation Trust Center, 1209 Orange Street, Wilmington, Delaware 19801.

     IN WITNESS WHEREOF, the undersigned has executed this Certificate of Formation as of June 14, 2005.

By:	/s/ Mary Kim E. Shipp
	Mary Kim E. Shipp
	Authorized Person