Exhibit 4.2
                             SUPPLEMENTAL INDENTURE

            Supplemental Indenture (this "Supplemental Indenture"), dated as of
February 25, 2002, among Wilkes-Barre Imaging, L.L.C. (the "Guaranteeing
Subsidiary"), a subsidiary of InSight Health Services Corp. (or its permitted
successor), a Delaware corporation (the "Company"), InSight Health Services
Holdings Corp., the Subsidiary Guarantors (as defined in the Indenture referred
to herein) and State Street Bank and Trust Company, N.A., as trustee under the
Indenture referred to below (the "Trustee").

                               W I T N E S S E T H

            WHEREAS, the Company has heretofore executed and delivered to the
Trustee an indenture (the "Indenture"), dated as of October 30, 2001 providing
for the issuance of an aggregate principal amount of $225 million of 9 7/8%
Senior Subordinated Notes due 2011 (the "Notes");

            WHEREAS, the Indenture provides that under certain circumstances the
Guaranteeing Subsidiary shall execute and deliver to the Trustee a supplemental
indenture pursuant to which the Guaranteeing Subsidiary shall unconditionally
guarantee all of the Company's obligations under the Notes and the Indenture on
the terms and conditions set forth herein (the "Guarantee"); and

            WHEREAS, pursuant to Section 9.01 of the Indenture, the Trustee is
authorized to execute and deliver this Supplemental Indenture.

            NOW THEREFORE, in consideration of the foregoing and for other good
and valuable consideration, the receipt of which is hereby acknowledged, the
Guaranteeing Subsidiary and the Trustee mutually covenant and agree for the
equal and ratable benefit of the Holders of the Notes as follows:

            1. Capitalized Terms. Capitalized terms used herein without
definition shall have the meanings assigned to them in the Indenture.

            2. Agreement to Guarantee. The Guaranteeing Subsidiary hereby agrees
as follows:

            (a) Along with all other Guarantors, to jointly and severally
Guarantee to each Holder of a Note authenticated and delivered by the Trustee
and to the Trustee and its successors and assigns, irrespective of the validity
and enforceability of the Indenture, the Notes or the obligations of the Company
hereunder or thereunder, that:

                  (i) the principal of and interest on the Notes will be
      promptly paid in full when due, whether at maturity, by acceleration,
      redemption or otherwise, and interest on the overdue principal of and
      interest on the Notes, if any, if lawful, and all other obligations of the
      Company to the Holders or the Trustee hereunder or thereunder will be
      promptly paid in full or performed, all in accordance with the terms
      hereof and thereof; and





                  (ii) in case of any extension of time of payment or renewal of
      any Notes or any of such other obligations, the same will be promptly paid
      in full when due or performed in accordance with the terms of the
      extension or renewal, whether at stated maturity, by acceleration or
      otherwise. Failing payment when due of any amount so guaranteed or any
      performance so guaranteed for whatever reason, the Guarantors shall be
      jointly and severally obligated to pay the same immediately.

            (b) The obligations hereunder shall be unconditional, irrespective
of the validity, regularity or enforceability of the Notes or the Indenture, the
absence of any action to enforce the same, any waiver or consent by any Holder
of the Notes with respect to any provisions hereof or thereof, the recovery of
any judgment against the Company, any action to enforce the same or any other
circumstance that might otherwise constitute a legal or equitable discharge or
defense of a guarantor.

            (c) The following are hereby waived: diligence, presentment, demand
of payment, filing of claims with a court in the event of insolvency or
bankruptcy of the Company, any right to require a proceeding first against the
Company, protest, notice and all demands whatsoever.

            (d) This Guarantee shall not be discharged except by complete
performance of the obligations contained in the Notes and the Indenture.

            (e) If any Holder or the Trustee is required by any court or
otherwise to return to the Company, the Guarantors, or any Custodian, Trustee,
liquidator or other similar official acting in relation to either the Company or
the Guarantors, any amount paid by either to the Trustee or such Holder, this
Guarantee, to the extent theretofore discharged, shall be reinstated in full
force and effect.

            (f) The Guaranteeing Subsidiary shall not be entitled to any right
of subrogation in relation to the Holders in respect of any obligations
guaranteed hereby until payment in full of all obligations guaranteed hereby.

            (g) As between the Guarantors, on the one hand, and the Holders and
the Trustee, on the other hand, (x) the maturity of the obligations guaranteed
hereby may be accelerated as provided in Article Six of the Indenture for the
purposes of this Guarantee, notwithstanding any stay, injunction or other
prohibition preventing such acceleration in respect of the obligations
guaranteed hereby, and (y) in the event of any declaration of acceleration of
such obligations as provided in Article Six of the Indenture, such obligations
(whether or not due and payable) shall forthwith become due and payable by the
Guarantors for the purpose of this Guarantee.

            (h) Pursuant to Section 10.02 of the Indenture, after giving effect
to any maximum amount and any other contingent and fixed liabilities that are
relevant under any applicable Bankruptcy or fraudulent conveyance laws, and
after giving effect to any collections from, rights to receive contribution from
or payments made by or on behalf of any other Guarantor in respect of the
obligations of such other Guarantor under Article Ten of the


                                       2


Indenture shall result in the obligations of such Guarantor under its Guarantee
not constituting a fraudulent transfer or conveyance.

            3. Subordination. The Obligations of the Guaranteeing Subsidiary
under its Guarantee pursuant to this Supplemental Indenture shall be junior and
subordinated to the Senior Indebtedness of the Guaranteeing Subsidiary on the
same basis as the Notes are junior and subordinated to the Senior Indebtedness
of the Company. For the purposes of the foregoing sentence, the Trustee and the
Holders shall have the right to receive and/or retain payments by the
Guaranteeing Subsidiary only at such time as they may receive and/or retain
payments in respect of the Notes pursuant to the Indenture, including Article
Ten hereof.

            4. Execution and Delivery. Each Guaranteeing Subsidiary agrees that
the Guarantees shall remain in full force and effect notwithstanding any failure
to endorse on each Note a notation of such Guarantee.

            5. Guaranteeing Subsidiary May Consolidate, Etc., on Certain Terms.

            Except as otherwise provided in Section 11.05 of the Indenture, a
Subsidiary Guarantor may not consolidate with or merge with or into any other
Person or convey, sell, assign, transfer, lease or otherwise dispose of its
properties and assets substantially as an entirety to any other Person (other
than the Company or another Subsidiary Guarantor) unless:

                  (i) subject to the provisions of the following paragraph, the
      Person formed by or surviving such consolidation or merger (if other than
      such Subsidiary Guarantor) or to which such properties and assets are
      transferred assumes all of the obligations of such Subsidiary Guarantor
      under the Indenture and its Guarantee, pursuant to a supplemental
      indenture in form and substance satisfactory to the Trustee;

                  (ii) immediately after giving effect to such transaction, no
      Default or Event of Default has occurred and is continuing; and

                  (iii) the Subsidiary Guarantor delivers, or causes to be
      delivered, to the Trustee, in form and substance reasonably satisfactory
      to the Trustee, an Officers' Certificate and an Opinion of Counsel, each
      stating that such transaction complies with the requirements of the
      Indenture.

            For purposes of the foregoing, the transfer (by lease, assignment,
sale or otherwise, in a single transaction or series of transactions) of all or
substantially all of the properties or assets of one or more Restricted
Subsidiaries, the Capital Stock of which constitutes all or substantially all of
the properties and assets of the Company, shall be deemed to be the transfer of
all or substantially all of the properties and assets of the Company.

            In case of any such consolidation, merger, sale or conveyance and
upon the assumption by the successor Person, by supplemental indenture, executed
and delivered to the Trustee and reasonably satisfactory in form to the Trustee,
of the Guarantee endorsed upon the Notes and the due and punctual performance of
all of the covenants and conditions of the Indenture to be performed by a
Guarantor, such successor Person shall succeed to and be substituted for a
Guarantor with the same effect as if it had been named herein as a Guarantor.



                                       3

Such successor Person thereupon may cause to be signed any or all of the
Guarantees to be endorsed upon all of the Notes issuable hereunder which
theretofore shall not have been signed by the Company and delivered to the
Trustee. All the Guarantees so issued shall in all respects have the same legal
rank and benefit under the Indenture as the Guarantees theretofore and
thereafter issued in accordance with the terms of the Indenture as though all of
such Guarantees had been issued at the date of execution hereof.

            6.    Releases.

            (a) A Subsidiary Guarantor will be deemed automatically and
unconditionally released and discharged from all of its obligations under its
Guarantee without any further action on the part of the Trustee or any Holder of
the Notes upon a sale or other disposition to a Person not an Affiliate of the
Company of all of the Capital Stock of, or all or substantially all of the
assets of, such Subsidiary Guarantor, by way of merger, consolidation or
otherwise, which transaction is carried out in accordance with Section 4.10 of
the Indenture; provided that any such termination shall occur (x) only to the
extent that all obligations of such Subsidiary Guarantor under all of its
guarantees of, and under all of its pledges of assets or other security
interests which secure any Indebtedness of the Company shall also terminate upon
such sale, disposition or release and (y) only if the Trustee is furnished with
written notice of such release together with an Officers' Certificate from such
Subsidiary Guarantor to the effect that all of the conditions to release in this
Section 6 have been satisfied.

            (b) Any Guarantor not released from its obligations under its
Guarantee shall remain liable for the full amount of principal of and interest
on the Notes and for the other obligations of any Guarantor under the Indenture
as provided in Article Eleven of the Indenture.

            7. No Recourse Against Others. No director, officer, employee,
incorporator or stockholder of the Parent, the Company or any Subsidiary
Guarantor, as such shall have any liability for any obligations of the Parent,
the Company or the Subsidiary Guarantors under the Notes, the Indenture, the
Guarantees or for any claim based on, in respect of, or by reason of, such
obligations or their creation. Each Holder of Notes, by accepting a Note, waives
and releases all such liability. The waiver and release are part of the
consideration for issuance of the notes. The waiver may not be effective to
waive liabilities under the federal securities laws.

            8. NEW YORK LAW TO GOVERN. THE INTERNAL LAW OF THE STATE OF NEW YORK
SHALL GOVERN AND BE USED TO CONSTRUE THIS SUPPLEMENTAL INDENTURE BUT WITHOUT
GIVING EFFECT TO APPLICABLE PRINCIPLES OF CONFLICTS OF LAW TO THE EXTENT THAT
THE APPLICATION OF THE LAWS OF ANOTHER JURISDICTION WOULD BE REQUIRED THEREBY.

            9. Counterparts. The parties may sign any number of copies of this
Supplemental Indenture. Each signed copy shall be an original, but all of them
together represent the same agreement.

            10. Effect of Headings. The Section headings herein are for
convenience only and shall not affect the construction hereof.

                                       4


            11. Trustee. The Trustee shall not be responsible in any manner
whatsoever for or in respect of the validity or sufficiency of this Supplemental
Indenture or for or in respect of the recitals contained herein, all of which
recitals are made solely by the Guaranteeing Subsidiary and the Company.



                  [Remainder of Page Left Intentionally Blank]


                                       5


            IN WITNESS WHEREOF, the parties hereto have caused this Supplemental
Indenture to be duly executed and attested, all as of the date first above
written.

Dated:  February 25, 2002

                                        WILKES-BARRE IMAGING, L.L.C.


                                        By: InSight Health Corp., as the
                                            sole member and sole manager
                                            of Wilkes-Barre Imaging, L.L.C.


                                        By: /s/ Steven T. Plochocki
                                            ------------------------------------
                                            Name:  Steven T. Plochocki
                                            Title: President and Chief Executive
                                                   Officer


                                        INSIGHT HEALTH SERVICES CORP.


                                        By: /s/ Steven T. Plochocki
                                            ------------------------------------
                                            Name: Steven T. Plochocki
                                            Title: President and Chief Executive
                                                   Officer


                                        INSIGHT HEALTH SERVICES HOLDINGS CORP.


                                        By:  /s/ Steven T. Plochocki
                                            ------------------------------------
                                            Name: Steven T. Plochocki
                                            Title: President and Chief Executive
                                                   Officer


                                        INSIGHT HEALTH CORP.


                                        By:  /s/ Steven T. Plochocki
                                            ------------------------------------
                                            Name: Steven T. Plochocki
                                            Title: President and Chief Executive
                                                   Officer


                                       6


                                        SIGNAL MEDICAL SERVICES, INC.


                                        By: /s/ Steven T. Plochocki
                                            ------------------------------------
                                            Name: Steven T. Plochocki
                                            Title: President and Chief Executive
                                                   Officer


                                        OPEN MRI, INC.


                                        By: /s/ Steven T. Plochocki
                                            ------------------------------------
                                            Name: Steven T. Plochocki
                                            Title: President and Chief Executive
                                                    Officer


                                        MAXUM HEALTH CORP.


                                        By: /s/ Steven T. Plochocki
                                            ------------------------------------
                                            Name:  Steven T. Plochocki
                                            Title: President and Chief Executive
                                                   Officer


                                        RADIOSURGERY CENTERS, INC.


                                        By:  /s/ Steven T. Plochocki
                                            ------------------------------------
                                            Name: Steven T. Plochocki
                                            Title: President and Chief Executive
                                                   Officer


                                        MAXUM HEALTH SERVICES CORP.


                                        By:  /s/ Steven T. Plochocki
                                            ------------------------------------
                                            Name: Steven T. Plochocki
                                            Title: President and Chief Executive
                                                   Officer

                                       7



                                  MRI ASSOCIATES, L.P.


                                  By:  InSight Health Corp., its General
                                       Partner


                                  By:  /s/ Steven T. Plochocki
                                      ----------------------------------------
                                      Name: Steven T. Plochocki
                                      Title: President and Chief Executive
                                             Officer


                                  MAXUM HEALTH SERVICES OF NORTH TEXAS, INC.

                                  By:  /s/ Steven T. Plochocki
                                      ----------------------------------------
                                      Name: Steven T. Plochocki
                                      Title: President and Chief Executive
                                             Officer


                                  MAXUM HEALTH SERVICES OF DALLAS, INC.


                                  By:  /s/ Steven T. Plochocki
                                      ----------------------------------------
                                      Name: Steven T. Plochocki
                                      Title: President and Chief Executive
                                             Officer


                                  NDDC, INC.


                                  By: /s/ Steven T. Plochocki
                                      ----------------------------------------
                                      Name: Steven T. Plochocki
                                      Title: President and Chief Executive
                                             Officer


                                  DIAGNOSTIC SOLUTIONS CORP.


                                  By: /s/ Steven T. Plochocki
                                      ----------------------------------------
                                      Name: Steven T. Plochocki
                                      Title: President and Chief Executive
                                             Officer


                                       8


                                  STATE STREET BANK AND TRUST COMPANY,
                                  N.A., AS TRUSTEE


                                  By: /s/ Cheryl L. Clarke
                                      ----------------------------------------
                                      Name: Cheryl L. Clarke
                                      Title: Assistant Secretary




                                       9