use t prop from withTranslation

src/components/Header/Header.js

@@ -3,7 +3,7 @@ import PropTypes from 'prop-types';
 import { Link, withRouter } from 'react-router-dom';
 import { Dropdown } from 'react-viewerbase';
 import { withTranslation } from 'react-i18next';
-import i18n, { t } from 'ohif-i18n';
+import i18n from 'ohif-i18n';
 import './Header.css';
 import OHIFLogo from '../OHIFLogo/OHIFLogo.js';
 import ConnectedUserPreferencesModal from '../../connectedComponents/ConnectedUserPreferencesModal.js';
@@ -13,7 +13,8 @@ class Header extends Component {
     home: PropTypes.bool.isRequired,
     location: PropTypes.object.isRequired,
     openUserPreferencesModal: PropTypes.func,
-    children: PropTypes.node
+    children: PropTypes.node,
+    t: PropTypes.func.isRequired,
   };
 
   static defaultProps = {
@@ -32,6 +33,7 @@ class Header extends Component {
   }
 
   loadOptions() {
+    const { t } = this.props;
     this.options = [
       {
         title: t('preferences'),
@@ -49,12 +51,13 @@ class Header extends Component {
   changeLanguage(language) {
     i18n.init({
       fallbackLng: language.substring(0, 2),
-      lng: language
+      lng: language,
     });
     this.loadOptions();
   }
 
   render() {
+    const { t } = this.props;
     return (
       <div className={`entry-header ${this.props.home ? 'header-big' : ''}`}>
         <div className="header-left-box">
@@ -108,11 +111,7 @@ class Header extends Component {
           >
             ES-MX
           </button>
-          <Dropdown
-            title={t('options')}
-            list={this.options}
-            align="right"
-          />
+          <Dropdown title={t('options')} list={this.options} align="right" />
           <ConnectedUserPreferencesModal />
         </div>
       </div>