Radiology smartphone applications; current provision and cautions

Smartphones and their applications are increasingly used by medical practitioners and have potentially significant roles in the healthcare and clinical setting [15]. Health-related applications in various medical fields have been studied; however this is one of the first papers to review smartphone applications relevant to radiology.

Szekely et al. [16] recently published a similar study assessing the range and benefits of radiology-related smartphone and tablet applications. However their search only revealed 81 applications compared with the 321 identified in this study. Whilst the dates of the search and the exclusion criteria used differed between the studies, the search performed by Szekely et al. may have been incomplete.

Compared with the previous reports in other specialties, a relatively large number of radiology-related applications were identified. This probably reflects the general relevance of radiology compared with the previously studied medical fields, as well the rapid growth in medical applications [2].

The advent of smartphones and applications has made it easier for programmers, medically trained or not, to develop and publish medical-related literature. This increased accessibility has obvious benefits; however there are concerns regarding the accuracy of medical application content [5, 7‐10]. In keeping with this, only 44 % of applications in the study acknowledged medical professional/society involvement or the use of guidelines or papers in application development. A further 12 % were developed by imaging companies. This low level of medical professional involvement is concerning.

It is currently difficult for a potential user to determine the accuracy of application content prior to purchase. The application stores provide a short description written by the application developer, customer ratings and comments, and a selection of screen shots. Whilst the customer ratings provide a source of feedback, 61 % of applications in this study had no rating. Furthermore 69 % of those rated were based on less than ten ratings, reducing the reliability of the customer feedback.

Expert medial input in the development of medical applications may improve reliability. This input should be clearly stated in the application advertising material to allow potential users to make an informed assessment of an application’s reliability prior to purchase. Regulations may also be required for some medical applications. The FDA plans to regulate a subset of smartphone medical applications that might present a potential risk to patients, such as those allowing display of medical images directly from a picture archiving and communication system (PACS) server [17]; however most of the applications identified in this study are not part of this subset.

Another way of helping users gauge an application’s reliability would be to develop a quality ‘kite mark’ for the field. This might be a role for the RCR or other radiology societies who could give their stamp of approval for products judged fit for the purpose.

With an appropriate application it is possible to access DICOM format images stored in PACS systems via a smartphone connected to the Internet. Fifteen out of the 29 viewing software applications have the facility to allow images from any PACS to be viewed remotely, and the remaining 14 permit access to a named PACS server. The viewing features available on these applications are becoming increasingly sophisticated, with many permitting multiplanar reformatting, two- or three-dimensional reconstructions, measuring as well as scrolling, panning, zooming and windowing.

The regulation of medical smartphone applications is a new and evolving field. The FDA has released guidance on its intention to regulate a subset of medical applications, including those allowing access to DICOM format images, however this guidance is currently only a recommendation as full regulatory oversight has not commenced [17]. Three of the viewing software applications in the study had FDA approval for primary diagnostic use (Table 3). The remaining 26 viewing software applications without FDA approval should not be used for primary diagnosis; however this was only stated in the publicity information of 62 % of these.

To gain FDA approval the application must be shown to have substantial equivalence to another legally marketed device (i.e. any new technological changes are at least as safe and effective as the predicate). Whilst the software of the mobile PACS applications is very similar or identical to existing PACS systems, the relevant hardware is clearly different (smartphones versus reporting workstation), and this potentially affects the safety of the smartphone application. With these hardware limitations in mind both the Mobile MIM and ResolutionMD applications have clear disclaimers stating they should only be used when there is no access to a workstation, as they are not intended to replace full workstations.

The Medical Devices Directive (MDD) [18] ensures safety and performance of medical devices throughout the EU, with each member state having its own regulatory framework. However there is currently no consensus between member states over the definition of a medical device and which medical applications should be considered medical devices, leading to uncertainty among application developers and healthcare providers. In the UK, DICOM viewing applications would be considered a medical device by the Medicines and Healthcare Products Regulatory Agency (MHRA). Every registered medical device in the EU must carry the CE (Conformité Européene) mark, signalling that the manufacturer is satisfied the product conforms to the relevant requirements in the relevant legislation. The necessary requirements vary according to the MDD’s classification of the medical device. Most applications, including DICOM viewing applications, are within the lowest risk category (class I), which means the developers can self-declare conformity to the essential requirements without the need for independent review. Unfortunately there is currently very limited use of the CE mark in the application stores [10].

The ability to view full-resolution images remotely has implications for timely diagnosis and treatment; however the limitations of using smartphones for image interpretation must be considered [19]. First, there are few studies investigating the diagnostic accuracy of image interpretation using smartphones [12, 20‐23]. Second, smartphones cannot meet the minimum standards for primary diagnostic displays required in Europe. For example, the RCR requires a screen resolution of ≥1,280 × 1,024 pixels and screen size of ≥ 42 cm, with the possibility of comparing serial examinations side by side [24]; the iPhone 5’s display for example has 1,136 × 640 pixels and a 10.2-cm screen [25]. The deleterious effects of ambient light on mobile image interpretation also need to be taken into account. Finally, reporting workstation displays undergo rigorous regular calibration and quality assurance procedures to ensure they remain fit for the purpose. Smartphones being used for primary diagnosis would have to be part of similar quality assurance programmes.

Therefore, despite FDA approval, caution must be used when using DICOM viewing applications for primary diagnosis on smartphones and we feel the fundamental limitations of smartphone displays means smartphones are more suited for reviewing images. Whilst radiologists are likely to appreciate such restrictions, other medical practitioners using these applications may be less aware of their limitations.

In contrast to smartphones, tablet devices have larger displays with better resolution. They may therefore be better suited for mobile review of DICOM images. Studies assessing tablet devices in this regard are promising [26‐28]; however further research is required to determine their diagnostic accuracy.

Data confidentiality is a major concern when using smartphones to review patient images, particularly if the phone is lost or stolen. One option used by several of the viewing applications is not storing any protected health information on the mobile device. Instead the user has to log in to a secure server and access the data via a secure, encrypted data transfer link. Further improvements in data security can be gained from applications utilising the HTLM5 markup language. In contrast to previous versions, HTLM5 has many commonly used applications integrated, such as video and audio elements. This makes it easier for users to access graphical and multimedia content directly via the web server without the need for additional plug-ins and subsequent data download onto a user’s device. Whilst these options provide safe methods for managing confidential data, it obviously limits the use of the application to areas that have Internet access. Other applications permit the download of protected health information onto smartphones. Data stored in this way should be encrypted, and there should be the possibility to remotely disable lost or stolen devices.

There are other security concerns that should be mentioned. Employees, including healthcare workers, are increasingly using their own smartphones for work, resulting in a “bring your own device” trend. A recent survey showed that 41 % of US healthcare workers do not have a password on their phone, over 50 % access unsecure Wi-Fi networks and 48 % have not disabled the Bluetooth discoverable mode [29]. Furthermore many healthcare institutions do not have a formal mobile strategy, with most unable to wipe the data from an employee’s personal device should it be lost or stolen. Such practices raise serious security issues, which, in the setting of the healthcare system, could place patients’ protected health information at risk.

The speed of data transfer and download is a further limitation of mobile image review on smartphones. A study evaluating the OsiriX smartphone application showed that the time taken to transfer 85 5-mm axial slices of a CT of the abdomen and pelvis using an iPhone 3S was up to 51 s with a WiFi connection, over 7 min using a 3G connection and over 35 min using an EDGE network connection [20]. The time taken for transferring thin (1-mm) slices to permit multiplanar formatting will be considerably longer. While smartphone and network technology continues to improve, with a corresponding increase in the rate of data transfer, the prolonged transfer times, particularly when no Wi-Fi connection is available, may currently limit the usefulness of smartphone viewing software applications.

Other concerns regarding noise, distraction, infection control, and health and safety cautions have also been reported [30, 31].

The advertised costs of some of the DICOM viewing applications are misleading. Some applications charge a one-off fee, which allows the user to download and use the application. In contrast, several applications are free to download but require access to a named PACS system or specific additional hardware or software to work. These “hidden fees” are often considerable, totalling hundreds or thousands of euros. The use of such applications is restricted to practitioners whose institutions have access to the required PACS system, negating some, if not all, of these “hidden fees”, but restricting their wider usage.

One of the limitations of the study was the use of named medical involvement as a surrogate marker for reliability of application content. As the cost of downloading and reviewing all of the applications identified was prohibitively expensive, the validity and accuracy of the content within applications could not be directly verified. However, this recreates the situation potential application purchasers currently encounter prior to purchase.