<PAGE>

                                                                 EXHIBIT 10.13

                             EMPLOYMENT AGREEMENT
                             --------------------

     This  Employment Agreement (the "Agreement") is made and entered into as of
the 31st day of March, 1999 between ACCESS Radiology Corporation (the
"Employer"), a Delaware corporation, and Scott S. Sheldon (the "Executive"),
residing at 10 Emerson Place, Charles River Park, Boston, Massachusetts 02114.
Where not otherwise defined herein, capitalized terms used herein have the
meanings set forth in Section 7.1 of this Agreement.

     WHEREAS, the Employer wishes to employ the Executive in an executive
capacity, as its President and Chief Executive Officer, and Executive wishes to
accept such employment, on the terms and conditions set forth herein;

     NOW, THEREFORE, in consideration of the mutual promises, benefits and
covenants herein contained, the Employer and the Executive hereby agree as
follows:

     1.   Term.
          ----

     1.1  The Employer employs the Executive and the Executive accepts such
employment, for a  period ending on December 31, 2000 (the "Initial Term").

     1.2  This Agreement shall be automatically renewed for additional one-year
terms (a "Renewal Term") upon the expiration of the Initial Term or any Renewal
Term unless either party delivers to the other written notice of expiration
within 60 days prior to the end of the then current term.

     1.3  This Agreement may be terminated prior to the expiration of the
Initial Term or any Renewal Term as provided in Section 4 of this Agreement.

     2.   Positions and Duties.
          --------------------

     2.1  During the term of this Agreement, the Employer shall employ the
Executive to serve as President and Chief Executive Officer of the Employer
subject to the terms of this Agreement and except as Executive and Employer
otherwise agree in writing.  The Executive shall perform such executive,
administrative, and operational duties customary for executives in such capacity
or as may be assigned to the Executive from time to time by the Board of
Directors of the Employer.

     2.2  Executive agrees to serve the Employer faithfully and to the best of
the Executive's ability and to devote substantially all of the Executive's
business time, attention and efforts to the interests and business of the
Employer and its Subsidiaries.  Nothing contained herein shall preclude
Executive from serving on the board of one business corporation (other than
Employer and its subsidiaries) and on boards of not-for-profit organizations and
trade groups, nor from participating in community affairs, provided that such
activities do not materially interfere with the Executive's performance of  his
duties and responsibilities to the Employer.  The Executive warrants to the
Employer that the Executive is not under any contractual commitment prohibiting
or limiting Executive's employment by the Employer.

     2.3  The Executive agrees at all times to perform his duties in accordance
with applicable laws, rules, and regulations and the policies and procedures of
the Employer applicable to senior executives from time to time.


                                       1
<PAGE>

     3.     Compensation, Benefits, and Expenses.
            ------------------------------------

     3.1    Salary. During the period from the Effective Date through the
            ------
Initial Term and any Renewal Term of the Agreement, and except as otherwise
provided in Initial the Agreement, the Employer shall pay to Executive an annual
base salary of $175,000, or such greater amount as may be determined from time
to time by the Board of Directors (the "Base Salary Amount"), in installments
pursuant to the Employer's standard payroll policies and subject to such
withholding or deductions as may be mutually agreed between Employer and the
Executive or required by law. The Board of Directors shall review Executive's
salary not less frequently than annually, prior to February 1 of each year.

     3.2    Incentive Compensation.  In addition to the salary set forth in
            ----------------------
Section 3.1, Executive shall be entitled to earn incentive compensation in an
amount and on terms agreed to by the Employer and the Executive (the "Incentive
Compensation").

     3.3    Benefits.  During the period of his employment, Executive shall be
            --------
entitled to participate in Employer's plans for the welfare and benefit of its
employees available to senior executive officers (including health, disability,
and life insurance programs, and vacation periods) as shall be established and
modified from time to time.

     3.4    Expenses. During the term of this Agreement, the Employer authorizes
            --------
Executive to incur reasonable and necessary out-of-pocket expenses in the course
of performing his duties and rendering services hereunder in accordance with
Employer's policies with respect thereto, and the Employer shall reimburse
Executive for all such expenses, provided (i) such expenses and the purpose for
which they were incurred are in accordance with Employer's policies, and (ii)
the Executive timely submits to the Employer expense reports and substantiation
of the expenses in accordance with Employer's policies.

     3.5    Relocation. It is contemplated by the parties that Executive's
            ----------
permanent residence will remain in the greater Boston metropolitan area.
Executive will not be required to relocate his residence as a condition or term
of employment.

     4.     Termination.
            -----------

     4.1    Termination.  The Executive's employment by Employer shall terminate
            -----------
on the earliest Date of Termination upon the occurrence of any of the following
events:

     4.1.1  the Executive's death;

     4.1.2  the Executive is determined to be "permanently disabled" as defined
under the disability insurance policy covering the Executive;

     4.1.3  termination of Executive by Employer for Cause, provided, however,
that the Board of Directors has given Executive written notice of its intention
to terminate Executive for Cause, specifying with particularity the grounds on
which the proposed termination for Cause is contemplated, which shall be acts or
failures to act on the part of Executive of which the Board first had knowledge
no more than six months prior to the giving of such notice;

     4.1.4  termination of employment by Executive upon written notice to
Employer because of Constructive Termination Without Cause;

     4.1.5  Resignation by Executive, which shall be upon 30 days' written
notice to Employer; or

     4.1.6  termination of Executive by Employer without Cause.

                                       2
<PAGE>

     4.2  Time of Termination.  Executive's employment with Employer (including
          -------------------
all positions held with Employer or its Subsidiaries or affiliates) shall
terminate immediately upon the Date of Termination without further action by
Employer.

     4.3  Effect of Termination of Employment.
          -----------------------------------

     (a)  Termination Due to Death.  In the event the Executive's employment is
          ------------------------
terminated due to his death, his estate or designated beneficiaries shall be
entitled to the following:

          (i)    continuation of installments of the Base Salary Amount in
effect as of the date of death for a period of six months following the date of
death, payable on Employer's standard payroll cycle;

          (ii)   on account of any incentive compensation program for which
awards are computed on a formula basis, an amount equal to the amount earned by
the Executive as of the Date of Termination, pro rated for the portion of the
calendar year elapsed prior to the Date of Termination, and payable on the date
it would otherwise have been payable;

          (iii)  the balance on any other incentive awards previously earned but
not yet paid, payable on their standard payment date;

          (iv)   the right to exercise any stock option held by Executive which
is then exercisable (other than any option qualified as an incentive stock
option under the Internal Revenue Code (an "ISO")) on the date of death for the
remainder of its term;

          (v)    any other amounts payable on death pursuant to any written
plans or policies of Employer; and

          (vi)   any other amounts that accrued and became due and payable prior
to termination but have not yet been paid from Employer to Executive.

     (b)  Termination Due to Disability. In the event the Executive's employment
          -----------------------------
is terminated due to his permanent or total disability, Executive or his legal
representative shall be entitled to the following:

          (i)    on account of any incentive compensation program for which
awards are computed on a formula basis, an amount equal to the amount earned by
the Executive as of the Date of Termination, pro rated for the portion of the
calendar year elapsed prior to the Date of Termination, and payable on the date
it would otherwise have been payable;

          (ii)   the balance on any other incentive awards previously earned but
not yet paid, payable on their standard payment date;

          (iii)  the right to exercise any stock option held by Executive which
is then exercisable (other than any ISO) on the Date of Termination for the
remainder of its term;

          (iv)   continuation of medical benefits and life insurance as provided
in Section 3.3 of this Agreement for so long as such continuation may be
provided at reasonable cost to the Employer under its insurance arrangements in
effect from time to time (provided that if the Executive accepts employment with
another employer that offers medical and/or life insurance benefits, then the
Employer's obligation to provide such benefits under this clause shall
terminate);

                                       3
<PAGE>

            (v)   any other amounts payable according to the Employer's
disability policies; provided that disability payments that would be funded by
insurance on the date hereof shall be made to the extent that funds are
available under insurance policies maintained by the Employer which are then in
effect;

            (vi)  any other amounts that accrued and became due and payable
prior to termination but have not yet been paid from Employer to Executive

     (c)  Termination without Cause or Constructive Termination Without Cause.
          -------------------------------------------------------------------
In the event of the Executive's employment is terminated by Employer without
Cause (other than by death or disability) or there is a Constructive Termination
Without Cause, Executive shall be entitled to the following:

            (i)   a lump sum payment of $95,000, except that if such a
termination occurs within twelve months after a Change in Control , then the
Executive shall instead be entitled to continuation of installments of the Base
Salary Amount in effect as of the Date of Termination for a period of twelve
months following the Date of Termination, payable on Employer's standard payroll
cycle;

            (ii)  on account of any incentive compensation program for which
awards are computed on a formula basis, an amount equal to the amount earned by
the Executive as of the Date of Termination, pro rated for the portion of the
calendar year elapsed prior to the Date of Termination, and payable on the date
it would otherwise have been payable;

            (iii) the balance on any other incentive awards previously earned
but not yet paid, payable on their standard payment date;

            (iv)  the right to exercise any stock option held by Executive which
is then exercisable (other than any ISO) on the Date of Termination for the
remainder of its term;

            (v)   continuation, for (x) twelve months if termination occurs
within twelve months of a Change in Control or (y) six months, if termination
occurs more than twelve months after a Change in Control, of medical benefits
and life insurance as provided in Section 3.3 of this Agreement and
participation in other welfare benefit plans (provided that if within such
period the Executive accepts employment with another employer that offers
medical and/or life insurance benefits, then the Employer's obligation to
provide such benefits under this clause shall terminate); and

            (vi)  any other amounts that accrued and became due and payable
prior to termination but have not yet been paid from Employer to Executive

     (d)  Termination for Cause or Resignation.  In the event Executive's
          ------------------------------------
employment is terminated by Employer for Cause or by Executive by Resignation,
Executive shall receive:

            (i)   Base Salary Amount in effect on, and payable through, the Date
of Termination in accordance with Employer's standard payroll policies; and

            (ii)  any other amounts that accrued and became due and payable
prior to termination but have not yet been paid from Employer to Executive.

     (e)  Termination due to Expiration of Term.  In the event Employer elects
          -------------------------------------
to not renew Executive's employment at the expiration of the Initial Term or any
Renewal Term, Executive shall receive:

                                       4
<PAGE>

           (i)   a lump sum payment of $95,000, except that if such a
termination occurs within twelve months after a Change in Control , then the
Executive shall instead be entitled to continuation of installments of the Base
Salary Amount in effect as of the Date of Termination for a period of twelve
months following the Date of Termination, payable on Employer's standard payroll
cycle;

           (ii)  the balance of any incentive awards earned but not yet paid,
payable on their standard payment date;

           (iii) the right to exercise any stock option held by Executive which
is then exercisable (other than any ISO) on the Date of Termination for the
remainder of its term;

           (iv)  continuation, for (x) twelve months if termination occurs
within twelve months of a Change in Control or (y) six months, if termination
occurs more than twelve months after a Change in Control, of medical benefits
and life insurance as provided in Section 3.3 of this Agreement and
participation in other welfare benefit plans (provided that if within such
period the Executive accepts employment with another employer that offers
medical and/or life insurance benefits, then the Employer's obligation to
provide such benefits under this clause shall terminate); and

           (v)   any other amounts that accrued and became due and payable prior
to termination but have not yet been paid from Employer to Executive.

     5.  Return of Employer's Property.
         -----------------------------

     Immediately upon termination of the Executive's employment with the
Employer, the Executive shall deliver to the Employer all confidential
information of the Employer, including, but not limited to, documents,
correspondence, notebooks, reports, computer programs, names of full-time and
part-time employees and consultants, and all other materials and copies thereof
(including computer discs and other electronic media) relating in any way to the
business of the employer in any way obtained by the Executive during the period
of his employment with Employer.  Immediately upon termination of the
Executive's employment with the Employer, the Executive shall deliver to the
Employer all tangible property of Employer in the possession of Executive.  The
obligations of Executive under this Section 5 shall survive the termination of
Executive's employment and the expiration or termination of this Agreement.

     6.  Remedies.
         --------

     In the event of any breach or threatened breach, the parties to this
Agreement may pursue any and all remedies available at law or in equity for any
such breach or threatened breach, including the recovery of damages.  The
Executive shall be under no obligation to mitigate any damages suffered by
Executive and arising in connection with this Agreement, nor (except as provided
in Sections 4.3 (c)(v) and 4.3 (e)(iv)) shall any income or amounts payable to
Executive other than pursuant to this Agreement offset damages hereunder.  No
payment due Executive under this Agreement shall be subject to any discount
based on accelerated payment or otherwise.  Costs of litigation, including,
without limitation, costs of investigations, fees and expenses of attorneys,
shall be borne by the Executive (i) if the Executive or his estate or
beneficiaries shall actually receive  lump sum payments or payments of Base
Salary (as the case may be) and medical, life insurance and welfare benefits
pursuant to Section 4.3 in the amounts and on the dates set forth therein (ii)
if the Executive shall have resigned or (iii) if the Executive shall have been
terminated for Cause (provided that if a court of competent jurisdiction shall
determine that Cause did not exist, then such costs of litigation shall be
repaid to the Executive).  In other cases such costs of litigation shall be
borne by the Employer.  Each party to this Agreement acknowledges that the
Employer would be irreparably harmed by any breach of

                                       5
<PAGE>

Section 5 and that damages alone would be an inadequate remedy for any breach of
such Section. Accordingly, the Employer shall be entitled to equitable relief,
including without limitation a preliminary and/or permanent injunction for
specific performance, with respect to any such breach, without requirement of
the posting of a bond or other surety.

     7.   Miscellaneous.
          -------------

     7.1  Certain Definitions.
          -------------------

     (a)  "Cause"  shall mean (i) breach of this Agreement or any other
agreement between the Executive and the Employer, (ii) willful refusal to
perform assigned duties, (iii) dishonesty, (iv) willful injury or attempt to do
injury to the Employer, its assets or its business, (v) substance abuse or (vi)
any act that is a felony or any violation of laws or policies relating to
harassment or discrimination.

     (b)  "Constructive Termination Without Cause" shall mean:

             (i)   the Executive shall have ceased to be the President of the
Employer, the Executive shall have been assigned to duties which are
inconsistent with his position as President or limitations shall have been
imposed on the Executive's authority that are inconsistent with his position as
President, in each case without the Executive's prior written consent, whether
as a result of a transaction after the date hereof (including without limitation
a merger, reorganization, consolidation or similar transaction) or otherwise;

             (ii)  a change in management structure (including the Executive
having ceased to be the Chief Executive Officer of the Employer) shall have
occurred without the prior written consent of the Executive, with the result
that the Executive does not report directly to the Board of Directors of the
Employer and, not less than three months nor more than six months after the
effectiveness of such change, the Executive shall have delivered to all members
of the Board of Directors a written statement setting forth in detail the
reasons why the Executive is not willing to work with the individual to whom he
then reports;

             (iii) without the Executive's prior written consent, there shall
have been a reduction in the Executive's then current Base Salary Amount or a
reduction in the Executive's target award opportunity (if any) or other long-
term performance incentive which is proportionately greater than corresponding
reductions in base salary, target award opportunities or long term performance
incentives (as the case may be) for senior management generally, or the Employer
shall have terminated or failed to continue to provide to the Executive any
employee benefit then otherwise provided to the Employer's senior management
generally, or the Employer shall have failed to include the Executive in any
incentive compensation plan of the Employer unless a plan providing
substantially the same opportunity is substituted;

             (iv)  the Employer shall engage in fraudulent conduct in which
Executive is not a participant;

             (v)   the Employer shall materially breach this Agreement and shall
not cure such breach within thirty days after written notice of such breach is
given by Executive to the Board of Directors of Employer, including, without
limitation, by failing to obtain the confirmation or assumption of the
Employer's obligations under this Agreement as required by Section 7.5 with
respect to any transaction referred to in that Section; or

             (vi)  the Employer shall require that Executive relocate to a
principal place of business outside of the Boston, Massachusetts metropolitan
area.

                                       6
<PAGE>

     (c)  "Date of Termination" shall mean:

             (i)   if employment terminates because of Executive's death, the
date of death;

             (ii)  if employment terminates for "Cause", the date of notice
under Section 4.1.3;

             (iii) if employment terminates due to "Resignation", then the
earlier of the Executive's last day of employment or 30 days from the receipt by
the Employer of notice of such Resignation;

             (iv)  if employment terminates because of permanent or total
disability, the date of determination that Executive is disabled as described in
Section 4.1.2 of this Agreement;

             (v)   if employment terminates for Constructive Termination Without
Cause, on the date set forth in Executive's notice as described in Section 4.1.4
of this Agreement; or

             (vi)  if employment terminates due to expiration of term, the date
of expiration.

     d)   "Change in Control" shall mean any transaction or series of related
transactions (including a merger, consolidation or sale of all or substantially
all assets) that results in the acquisition by any person or group of beneficial
ownership of securities of the Employer (or the entity resulting from a merger,
consolidation or sale of all or substantially all assets) representing a
majority of the aggregate voting power of the capital stock of the Employer (or
a resulting entity, calculated in all cases on a fully diluted basis); provided
that the acquisition of additional securities by any person or group that had
beneficial ownership, on January 21, 1999, of securities representing 10% or
more of the aggregate voting power of the capital stock of the Employer, shall
not be a Change in Control. The terms "group" and "beneficial ownership" shall
have the same meanings as under the Rules and Regulations of the United States
Securities and Exchange Commission promulgated under the Securities Exchange Act
of 1934.

     7.2  Notices.  Any notices under this Agreement shall be in writing and
          -------
shall be given by personal delivery, by local courier service, by certified or
registered letter, return receipt requested, or by a nationally recognized
overnight delivery service; and shall be deemed given when delivered in person
or by local courier or upon actual receipt of the facsimile or certified or
registered letter, or on the business day next following delivery to a
nationally recognized overnight delivery service at the addresses set forth
below or to such other address or addresses as either party shall have specified
in writing to the other party hereto.

             If to the Employer:

             ACCESS Radiology Corporation
             25 Hartwell Avenue
             Lexington, MA 02421
             Attn.:  Secretary

             If to the Executive:

             Scott S. Sheldon
             10 Emerson Place
             Charles River Park
             Boston, MA 02114

                                       7
<PAGE>

     7.3  Governing Law.  All questions pertaining to the validity,
          -------------
construction, execution and performance of this Agreement shall be construed in
accordance with, and be governed by, the laws of the state of Massachusetts
without reference to its principles of conflicts of law.

     7.4  Entire Agreement; Amendment or Modification.  This Agreement, the
          -------------------------------------------
Restricted Stock Purchase Agreement between Employer and Executive, the
Shareholders Agreement between Employer, Executive and certain other
shareholders of Employer, the Confidentiality and Work Product Agreement between
Employer and Executive, the Non-Competition Agreement between Employer and
Executive and the Employer's written employment manuals and policies are all of
the agreements of the parties hereto relevant to the matters contained herein.
This Agreement supersedes the Employment agreement dated as of August 28, 1997
between the Executive and the Employer.   No modification or amendment of any of
the provisions of this Agreement shall be effective unless in writing and signed
by the Executive and Employer.  No failure to exercise any right or remedy
hereunder shall operate as a waiver thereof.  No term or condition of this
Agreement shall be deemed to have been waived, nor shall a party be estopped
from enforcing any provision of this Agreement, except by a statement in writing
signed by the Executive or Employer, whichever party against whom such waiver or
estoppel is sought.  If any provision of this Agreement is determined by a court
of competent jurisdiction to be invalid or unenforceable, such provision shall
be reformed to the extent necessary to make it valid or enforceable and to carry
out the intent of the parties, or if such reformation is not possible, the
remaining provisions of this Agreement shall continue in full force and effect.

     7.5  Assignability; Binding Nature.  This Agreement has been duly
          -----------------------------
authorized by the Board of Directors of Employer and shall be binding upon and
inure to the benefit of the parties and their respective successors, heirs (in
the case of the Executive) and permitted assigns.  No rights or obligations of
the Employer under this Agreement may be assigned or transferred by the
Employer, except that such rights or obligations may be assigned or transferred
pursuant to a merger or consolidation in which the Employer is not the
continuing entity, or the sale of all or substantially all of the assets of the
Employer, provided that the assignee or transferee shall expressly assume the
liabilities, obligations and duties of the Employer, as contained in this
Agreement.  If requested by Executive, Employer will, prior to the effectiveness
of any merger or consolidation of Employer with or into any other entity or any
sale of all or substantially all of the assets of Employer, provide to Executive
the express written assumption of all of Employer's obligations hereunder by the
surviving or successor entity (or express written confirmation of such
obligations if Employer is the surviving entity).  Executive may not assign any
of his rights hereunder without the prior written consent of Employer.

     7.6  Survival. The Executive's obligations under Sections 5 and 6 will
          --------
survive the termination of Executive's employment and the termination of
expiration of this Agreement.  The Employer's obligations under this Agreement
will survive the termination of Executive's employment and the termination or
expiration of this Agreement until paid in full.

     7.7  Headings.  The paragraph and subparagraph headings contained in this
          --------
Agreement are for reference purposes only and shall not affect the construction
or interpretation of this Agreement.

                                       8
<PAGE>

     7.8  Counterparts; Effectiveness.  This Agreement may be executed in
          ---------------------------
several counterparts, and all counterparts so executed shall constitute one
agreement, binding on the parties hereto, notwithstanding that both parties are
not signatory to the original or the same counterpart. This Agreement shall
become effective as of the date first set forth above when executed by the
Executive and the Employer.

          IN WITNESS WHEREOF, the parties hereto have executed this Agreement
on the date first above written, and will be effective for all purposes as of
the Effective Date.


                                   ACCESS Radiology Corporation



                                   By: ______________________



                                   EXECUTIVE


                                   __________________________
                                   Scott S. Sheldon

                                       9