fix(viewer): View two or more specified studies (#2815)

extensions/default/src/DicomWebDataSource/index.js

@@ -89,10 +89,11 @@ function createDicomWebApi(dicomWebConfig, UserAuthenticationService) {
   const implementation = {
     initialize: ({ params, query }) => {
       const { StudyInstanceUIDs: paramsStudyInstanceUIDs } = params;
-      const queryStudyInstanceUIDs = query.get('StudyInstanceUIDs');
+      const queryStudyInstanceUIDs = query.getAll('StudyInstanceUIDs');
 
       const StudyInstanceUIDs =
-        queryStudyInstanceUIDs || paramsStudyInstanceUIDs;
+        queryStudyInstanceUIDs.length && queryStudyInstanceUIDs ||
+        paramsStudyInstanceUIDs;
       const StudyInstanceUIDsAsArray =
         StudyInstanceUIDs && Array.isArray(StudyInstanceUIDs)
           ? StudyInstanceUIDs