Exhibit 21 EXHIBIT 21. SUBSIDIARIES OF THE REGISTRANT NAME OF SUBSIDIARY STATE OF INCORPORATION - ------------------ ---------------------- InSight Health Corp. Delaware Mississippi Mobile Technology, Inc. Delaware Radiosurgery Centers, Inc. Delaware Maxum Health Corp. Delaware Quest Financial Services, Inc. Delaware Maxum Health Services Corp. Delaware DiagnosTemps, Inc. Delaware Diagnostic Solutions Corp. Delaware Maxum Health Services of North Texas, Inc. Texas Maxum Health Services of Arlington, Inc. Texas Maxum Health Services of Dallas, Inc. Texas MTS Enterprises, Inc. Texas NDDC, Inc. Texas Open MRI, Inc. Delaware Radiology Services Corp. Delaware Signal Medical Services, Inc. Delaware