Document:

<PAGE>   1
                                                                   Exhibit 10.63

                        AMENDMENT TO SECURITY AGREEMENTS
                               (LOAN A GUARANTORS)

         THIS AMENDMENT TO SECURITY AGREEMENTS (the "AMENDMENT") is made and
entered into as of November 8, 1999, by and between the entities listed on
EXHIBIT "A" attached hereto (each a "GUARANTOR" and collectively, the
"GUARANTORS") and DVI BUSINESS CREDIT CORPORATION ("LENDER").

                                   BACKGROUND

         A. Pursuant to various Security Agreements dated February 25, 1997 June
29, 1999, or November 8, 1999, as the case may be, by and between Guarantors and
Lender (collectively, the "SECURITY AGREEMENTS"), each Guarantor has granted to
Lender a continuing first priority pledge and security interest in all existing
and after-acquired Collateral (as to each Guarantor, the "SECURITY INTEREST" and
collectively, the "SECURITY INTERESTS").

         B. Each Security Interest secures the prompt payment and performance of
all obligations of the applicable Guarantor under its respective Unconditional
Continuing Guaranty dated February 25, 1997, June 29, 1999, or November 8, 1999,
as the case may be, pursuant to which that Guarantor agreed to guaranty and
become surety for all present and future obligations of US Diagnostic, Inc.
("BORROWER") to Lender, including, without limitation, all obligations arising
under that certain Loan and Security Agreement dated February 25, 1997, by and
between Borrower and Lender, as amended, and all documents, instruments and
agreements related thereto (collectively, the "LOAN DOCUMENTS").

         C. Pursuant to the terms and conditions of Amendment No. 4 to Loan and
Security Agreement of even date herewith by and between Borrower and Lender (the
"AMENDMENT NO. 4"), Borrower has agreed to divide its obligations under the Loan
and Note into two (2) separate and distinct obligations, each secured by a
separate pool of collateral.

         D. At Lender's request, Guarantors have agreed that the Security
Interests granted under the Security Agreements shall hereafter secure only the
obligations of Borrower under that certain Secured Promissory Note A of even
date herewith given by Borrower to Lender in the original principal amount of
Twenty-Four Million Dollars ($24,000,000.00) ("NOTE A"), and NOT the obligations
of Borrower under that certain Secured Promissory Note B of even date herewith
given by Borrower to Lender in the original principal amount of Eleven Million
Dollars ($11,000,000.00) ("NOTE B"), except upon the merger of the obligations
of Borrower under Note A and Note B in accordance with their terms.

         E. All capitalized terms not otherwise defined herein shall have the
meanings set forth in the Amendment No. 4.

                                       1
<PAGE>   2

         NOW, THEREFORE, the parties hereto, intending to be legally bound and
for good and valuable consideration, agree as follows:

         1. OBLIGATIONS. SECTION 1.1 of the Security Agreement shall be and is
hereby amended by deleting in its entirety the definition of "OBLIGATIONS"
contained therein and inserting in its place the following:

         ""OBLIGATIONS" mean the due and punctual payment of all amounts due
under Note A and the performance of all obligations of Guarantor under the
Guaranty, solely to the extent such obligations directly relate to Note A;
provided, however, that if the obligations of Borrower under Note A and Note B
are ever merged in accordance with their terms, the term "OBLIGATIONS" as used
herein shall thereafter be automatically deemed to include the payment of all
amounts due under Note A and under Note B."

         2. COUNTERPARTS. This Amendment may be executed in counterparts, all of
which when taken together constitute one and the same instrument.

         3. GOVERNING LAW. This Amendment is governed by and must be interpreted
and construed in accordance with the laws of the State of California (without
giving effect to any principles of conflicts of law).

         4. NO WAIVER. Lender is entering into this Amendment without any
forbearance, and without waiver or prejudice of, any Unmatured Default, any
Event of Default or any rights or remedies Lender has or may have under the Loan
Documents and applicable law, all of which rights and remedies Lender hereby
expressly reserves.

         5. INTERPRETATION. Any provision in this Amendment that may be contrary
to any provision of any of the Security Agreements shall prevail and override
that provision of that Security Agreement. Except as expressly set forth herein,
all other provisions of the Security Agreements shall remain unmodified and in
full force and effect.

         IN WITNESS WHEREOF, the undersigned have executed this Amendment as of
the date first above written.

HE IMAGING PARTNERS, LTD.                   PINNACLE IMAGING ASSOCIATES

By: /s/ Joseph A. Paul                      By: /s/ Joseph A. Paul
   -------------------------------              -------------------------------
Name: Joseph A. Paul                        Name: Joseph A. Paul
     -----------------------------               ------------------------------
Title: President                            Title: President
      ----------------------------                -----------------------------

VALLEY PRESBYTERIAN MAGNETIC                COLUMBUS DIAGNOSTIC CENTER,
RESONANCE CENTER, LP                        INC.

By: /s/ Joseph A. Paul                      By: /s/ Joseph A. Paul
   -------------------------------              -------------------------------
Name: Joseph A. Paul                        Name: Joseph A. Paul
     -----------------------------               ------------------------------
Title: President                            Title: President
      ----------------------------                -----------------------------

                                       2
<PAGE>   3

MEDITEK - BROWARD, INC.                     MEDITEK - PALM BEACH
                                            GARDENS, INC.

By: /s/ Joseph A. Paul                      By: /s/ Joseph A. Paul
   -------------------------------              -------------------------------
Name: Joseph A. Paul                        Name: Joseph A. Paul
     -----------------------------               ------------------------------
Title: President                            Title: President
      ----------------------------                -----------------------------

ADVANCED MEDICAL IMAGING                    MEDITEK - GREYSTONE, INC.
CENTER, INC.

By: /s/ Joseph A. Paul                      By: /s/ Joseph A. Paul
   -------------------------------              -------------------------------
Name: Joseph A. Paul                        Name: Joseph A. Paul
     -----------------------------               ------------------------------
Title: President                            Title: President
      ----------------------------                -----------------------------

MEDITEK - ICOT, INC.                        KALEY IMAGING, INC.

By: /s/ Joseph A. Paul                      By: /s/ Joseph A. Paul
   -------------------------------              -------------------------------
Name: Joseph A. Paul                        Name: Joseph A. Paul
     -----------------------------               ------------------------------
Title: President                            Title: President
      ----------------------------                -----------------------------

MEDITEK - PALMS, INC.                       MEDITEK - PREMIER NORTH, INC.

By: /s/ Joseph A. Paul                      By: /s/ Joseph A. Paul
   -------------------------------              -------------------------------
Name: Joseph A. Paul                        Name: Joseph A. Paul
     -----------------------------               ------------------------------
Title: President                            Title: President
      ----------------------------                -----------------------------

MEDITEK - SUN COAST, INC.                   COMPUTERIZED MEDICAL
                                            IMAGING CENTER, INC.

By: /s/ Joseph A. Paul                      By: /s/ Joseph A. Paul
   -------------------------------              -------------------------------
Name: Joseph A. Paul                        Name: Joseph A. Paul
     -----------------------------               ------------------------------
Title: President                            Title: President
      ----------------------------                -----------------------------

SAN FRANCISCO MAGNETIC                      MODESTO IMAGING CENTER, INC.
RESONANCE CENTER, INC.

By: /s/ Joseph A. Paul                      By: /s/ Joseph A. Paul
   -------------------------------              -------------------------------
Name: Joseph A. Paul                        Name: Joseph A. Paul
     -----------------------------               ------------------------------
Title: President                            Title: President
      ----------------------------                -----------------------------

SOUTH COAST RADIOLOGISTS,                   MEDITEK PREMIER, INC.
A CORPORATION

By: /s/ Joseph A. Paul                      By: /s/ Joseph A. Paul
   -------------------------------              -------------------------------
Name: Joseph A. Paul                        Name: Joseph A. Paul
     -----------------------------               ------------------------------
Title: President                            Title: President
      ----------------------------                -----------------------------

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<PAGE>   4

ORANGE PARK DIAGNOSTIC                      SALISBURY IMAGING, INC.
CENTER, INC.

By: /s/ Joseph A. Paul                      By: /s/ Joseph A. Paul
   -------------------------------              -------------------------------
Name: Joseph A. Paul                        Name: Joseph A. Paul
     -----------------------------               ------------------------------
Title: President                            Title: President
      ----------------------------                -----------------------------

JEFFERSON MAGNETIC
RESONANCE IMAGING, LLC

By: /s/ Joseph A. Paul
   -------------------------------
Name: Joseph A. Paul
     -----------------------------
Title: President
      ----------------------------

                                       4
<PAGE>   5

                                   GUARANTORS

HE Imaging Partners, Ltd.
Pinnacle Imaging Associates
Valley Presbyterian Magnetic Resonance Center, LP
Columbus Diagnostic Center, Inc.
MediTek - Broward, Inc.
MediTek - Palm Beach Gardens, Inc.
Advanced Medical Imaging Center, Inc.
MediTek - Greystone, Inc.
MediTek - ICOT, Inc.
Kaley Imaging, Inc.
MediTek - Palms, Inc.
MediTek - Premier North, Inc.
MediTek - Sun Coast, Inc.
Computerized Medical Imaging Center, Inc.
San Francisco Magnetic Resonance Center, Inc.
Modesto Imaging Center, Inc.
South Coast Radiologists, a Corporation
MediTek Premier, Inc.
Orange Park Diagnostic Center, Inc.
Salisbury Imaging, Inc.
Jefferson Magnetic Resonance Imaging, LLC

                                   EXHIBIT "A"
                                       to
                        AMENDMENT TO SECURITY AGREEMENTS
                               (LOAN A GUARANTORS)

                                       5<PAGE>   1
                                                                   Exhibit 10.64

                        AMENDMENT TO SECURITY AGREEMENTS
                               (LOAN B GUARANTORS)

         THIS AMENDMENT TO SECURITY AGREEMENT (the "AMENDMENT") is made and
entered into as of November 8, 1999, by and between the entities listed on
EXHIBIT "A" attached hereto (each a "GUARANTOR" and collectively, the
"GUARANTORS") and DVI BUSINESS CREDIT CORPORATION ("LENDER").

                                   BACKGROUND

         A. Pursuant to various Security Agreements dated February 25, 1997, or
June 29, 1999, as the case may be, by and between Guarantors and Lender
(collectively, the "SECURITY AGREEMENTS"), each Guarantor has granted to Lender
a continuing first priority pledge and security interest in all existing and
after-acquired Collateral (as to each Guarantor, the "SECURITY INTEREST" and
collectively, the "SECURITY INTERESTS").

         B. Each Security Interest secures the prompt payment and performance of
all obligations of the applicable Guarantor under its respective Unconditional
Continuing Guaranty dated February 25, 1997 or June 29, 1999, as the case may
be, pursuant to which that Guarantor agreed to guaranty and become surety for
all present and future obligations of US Diagnostic, Inc. ("BORROWER") to
Lender, including, without limitation, all obligations arising under that
certain Loan and Security Agreement dated February 25, 1997, by and between
Borrower and Lender, as amended, and all documents, instruments and agreements
related thereto (collectively, the "LOAN DOCUMENTS").

         C. Pursuant to the terms and conditions of Amendment No. 4 to Loan and
Security Agreement of even date herewith by and between Borrower and Lender (the
"AMENDMENT NO. 4"), Borrower has agreed to divide its obligations under the Loan
and Note into two (2) separate and distinct obligations, each secured by a
separate pool of collateral.

         D. At Lender's request, Guarantors have agreed that the Security
Interests granted under the Security Agreements shall hereafter secure only the
obligations of Borrower under that certain Secured Promissory Note B of even
date herewith given by Borrower to Lender in the original principal amount of
Eleven Million Dollars ($11,000,000.00) ("NOTE B"), and NOT the obligations of
Borrower under that certain Secured Promissory Note A of even date herewith
given by Borrower to Lender in the original principal amount of Twenty-Four
Million Dollars ($24,000,000.00) ("NOTE A"), except upon the merger of the
obligations of Borrower under Note A and Note B in accordance with their terms.

         E. All capitalized terms not otherwise defined herein shall have the
meanings set forth in the Amendment No. 4.

                                       1
<PAGE>   2

         NOW, THEREFORE, the parties hereto, intending to be legally bound and
for good and valuable consideration, agree as follows:

         1. OBLIGATIONS. SECTION 1.1 of the Security Agreement shall be and is
hereby amended by deleting in its entirety the definition of "OBLIGATIONS"
contained therein and inserting in its place the following:

         ""OBLIGATIONS" mean the due and punctual payment of all amounts due
under Note B and the performance of all obligations of Guarantor under the
Guaranty, solely to the extent such obligations directly relate to Note B;
provided, however, that if the obligations of Borrower under Note A and Note B
are ever merged in accordance with their terms, the term "OBLIGATIONS" as used
herein shall thereafter be automatically deemed to include the payment of all
amounts due under Note A and under Note B."

         2. COUNTERPARTS. This Amendment may be executed in counterparts, all of
which when taken together constitute one and the same instrument.

         3. GOVERNING LAW. This Amendment is governed by and must be interpreted
and construed in accordance with the laws of the State of California (without
giving effect to any principles of conflicts of law).

         4. NO WAIVER. Lender is entering into this Amendment without any
forbearance, and without waiver or prejudice of, any Unmatured Default, any
Event of Default or any rights or remedies Lender has or may have under the Loan
Documents and applicable law, all of which rights and remedies Lender hereby
expressly reserves.

         5. INTERPRETATION. Any provision in this Amendment that may be contrary
to any provision of any of the Security Agreements shall prevail and override
that provision of that Security Agreement. Except as expressly set forth herein,
all other provisions of the Security Agreements shall remain unmodified and in
full force and effect.

         IN WITNESS WHEREOF, the undersigned have executed this Amendment as of
the date first above written.

AH IMAGING, INC.                            KIRKWOOD MRI CENTER, INC.

By: /s/ Joseph A. Paul                      By: /s/ Joseph A. Paul
   -------------------------------              -------------------------------
Name: Joseph A. Paul                        Name: Joseph A. Paul
     -----------------------------               ------------------------------
Title: President                            Title: President
      ----------------------------                -----------------------------

MR OF KANSAS CITY, L.P.                     BRIDGETON MRI CENTER, INC.

By: /s/ Joseph A. Paul                      By: /s/ Joseph A. Paul
   -------------------------------              -------------------------------
Name: Joseph A. Paul                        Name: Joseph A. Paul
     -----------------------------               ------------------------------
Title: President                            Title: President
      ----------------------------                -----------------------------

                                       2
<PAGE>   3

OUTPATIENT RADIOLOGY CENTER                 DI IMAGING CENTER, INC.

By: /s/ Joseph A. Paul                      By: /s/ Joseph A. Paul
   -------------------------------              -------------------------------
Name: Joseph A. Paul                        Name: Joseph A. Paul
     -----------------------------               ------------------------------
Title: President                            Title: President
      ----------------------------                -----------------------------

LB IMAGING, INC.                            COMMUNITY RADIOLOGY OF
                                            VIRGINIA, INC.

By: /s/ Joseph A. Paul                      By: /s/ Joseph A. Paul
   -------------------------------              -------------------------------
Name: Joseph A. Paul                        Name: Joseph A. Paul
     -----------------------------               ------------------------------
Title: President                            Title: President
      ----------------------------                -----------------------------

USDL PITTSBURGH, INC.                       MEDITEK - CHATHAM
                                            INDUSTRIES, INC.

By: /s/ Joseph A. Paul                      By: /s/ Joseph A. Paul
   -------------------------------              -------------------------------
Name: Joseph A. Paul                        Name: Joseph A. Paul
     -----------------------------               ------------------------------
Title: President                            Title: President
      ----------------------------                -----------------------------

HEIGHTS IMAGING CENTER, INC.                MEDICAL MARKETING
                                            DEVELOPMENT, INC.

By: /s/ Joseph A. Paul                      By: /s/ Joseph A. Paul
   -------------------------------              -------------------------------
Name: Joseph A. Paul                        Name: Joseph A. Paul
     -----------------------------               ------------------------------
Title: President                            Title: President
      ----------------------------                -----------------------------

SANTA FE IMAGING CENTER, INC.               AFFILIATED MEDICAL IMAGING
                                            NETWORK, INC.

By: /s/ Joseph A. Paul                      By: /s/ Joseph A. Paul
   -------------------------------              -------------------------------
Name: Joseph A. Paul                        Name: Joseph A. Paul
     -----------------------------               ------------------------------
Title: President                            Title: President
      ----------------------------                -----------------------------

USD DAYTON, INC.                            WESTLAKE DIAGNOSTIC CENTER,
                                            INC.

By: /s/ Joseph A. Paul                      By: /s/ Joseph A. Paul
   -------------------------------              -------------------------------
Name: Joseph A. Paul                        Name: Joseph A. Paul
     -----------------------------               ------------------------------
Title: President                            Title: President
      ----------------------------                -----------------------------

MICA IMAGING, INC.

By: /s/ Joseph A. Paul
   -------------------------------
Name: Joseph A. Paul
     -----------------------------
Title: President
      ----------------------------

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<PAGE>   4

                                   GUARANTORS

MR of Kansas City, L.P.
Outpatient Radiology Center
Community Radiology of Virginia, Inc.
USDL Pittsburgh, Inc.
MediTek - Chatham Industries, Inc.
Heights Imaging Center, Inc.
Medical Marketing Development, Inc.
Santa Fe Imaging Center, Inc.
Affiliated Medical Imaging Network, Inc.
USD Dayton, Inc.
Westlake Diagnostic Center, Inc.
MICA Imaging, Inc.
Bridgeton MRI Center, Inc.
Kirkwood MRI Center, Inc.
AH Imaging, Inc.
DI Imaging Center, Inc.
LB Imaging, Inc.

                                   EXHIBIT "A"
                                       to
                        AMENDMENT TO SECURITY AGREEMENTS
                               (LOAN B GUARANTORS)

                                       4

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