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Meet the Expert: Paul Sidhu

8 July, 2021  

Paul Sidhu is Professor of Imaging Sciences at King’s College London and consultant radiologist in the Department of Radiology at King’s College Hospital. His research interests have focused on ultrasound and interventional radiology. Here he shares his thoughts with Hospital Healthcare Europe on ultrasound and how this technique has evolved and will continue to develop in the future.

On how radiology services are organised at King’s

Professor Sidhu described how King’s is a large tertiary, general hospital in southeast London serving a population of over 2.2 million people in a largely deprived area. King’s has several different sites that cover various services, including paediatric, neonatal, cardiothoracic, neurosurgery, breast cancer screening, and liver transplantation. There is one centralised, very large, radiology department employing around 80 consultant radiologists and up to 700 staff. The department is also involved in the provision of training for radiologists and radiographer staff. Although radiologists are qualified doctors, their path towards becoming a radiologist is a long one that can take up to 12 years. In contrast, radiographers, who are the individuals responsible for taking images, still need to undergo degree level training although their role has greatly expanded in recent years. At King’s for example, radiographers manage all aspects of imaging for CT and MRI scans imaging in interventional radiology and some radiographers have become sonographers involved in the scanning and issuing of medical reports. All aspects require several years of training to become established within these roles. 

Ultrasound is available and employed in many different specialities by experienced and competent individuals. Professor Sidhu explained how there remains strict controls on who can perform scans that involve exposure to radiation and particularly in nuclear medicine, with the administration of radioactive isotopes. Administrators are required to have a specific ARSAC licence. All hospitals that undertake examinations with radiation exposure will have a radiation protection officer. In contrast, while there are no specific controls on who can perform either an MRI and ultrasound scan, he highlighted how MRI equipment is prohibitively expensive and ultimately is best reserved for the radiology department. Nevertheless, according to Professor Sidhu, the position is rather different with respect to ultrasound. While in the past, ultrasound has been the responsibility of the radiology department, as Professor Sidhu explained, things are rapidly changing with much ultrasound, particularly point-of-care, becoming performed outside of radiology. For instance, chest physicians will use ultrasound to identify pleural effusions that need to be drained, and rheumatologists will make use of ultrasound to examine the small joints of the hands. The evolution of ultrasound in other specialties has been considerable and radiologists no longer have either the time or perhaps inclination to perform such scans. Despite these developments, as Professor Sidhu described, it is safety regulations, focused on the patient, that keep radiology departments together. However, while the use of ultrasound has now extended beyond the realms of the radiology department, he felt that the radiology community was not overly concerned about this direction of travel, especially given that in the UK, there is a shortage of radiologists, and this delegation has to some extent been welcomed. In fact, he now believes that no single speciality effectively “owns” ultrasound and in many radiology departments, the ultrasound scanning is performed by sonographers and the radiologists themselves have moved on to becoming more focused on the interpretation of specialised scans. As a passing thought, he felt that while radiologists were likely to be the most competent individuals to perform and interpret scans, if an ultrasound was being used as a point-of-care service for a specific indication, provided that an individual healthcare professional appropriately interpret a scan, he had no objection to these developments. 

On the ESR subcommittee on ultrasound, his work as Chair, and future plans

Professor Sidhu mentioned how he had been a member of the European Society of Radiologists (ESR) ultrasound subcommittee for several years during which time, it had produced a number of different position papers. He cited what has become a very successful position paper on infection control and prevention from 2017,1 highlighting the importance of good hygiene measures, especially with transducers and how these should be cleaned after each use. More recently in 2020, the group have published best practice recommendations and imaging use.2 

This latest paper was an update of an earlier 2009 position paper on ultrasound.3 As Professor Sidhu clarified, the newer version provides a series of recommendations on appropriate standards for the use of ultrasound in radiology from the perspective of the ESR.  For instance, the position paper, defines the essential requirements for equipment, practice aspects of use, infection control, requirements for training, certification and competence. He noted that while not all ultrasound operators would necessarily conform to the standards delineated in the position paper, it did define the professional standards which would be expected if the service were delivered by a radiologist. Professor Sidhu explained that an important aim of the position paper was to hopefully clarify for any non-radiologists, the anticipated standards which should be followed, in a sense, a standard operating procedure for undertaking ultrasound, which had the support of the ESR and therefore credibility. Professor Sidhu described how it was important that the position paper provided the necessary guidance because when using ultrasound, it is not the machine which does the job but the operator. If the operator is not competent, neither is the output from the machine! In short, it is vital that operators will need to practice, learn and develop all the time to perfect the technique to ensure that they get the best use from the device. 

In terms of ensuring continued best practice, Professor Sidhu outlined documents produced by the ESR were designed to support non-radiologist operators. This advice encouraged participation in audits of their service but additionally and equally important, was that non-specialists needed to maintain their skills and competence through an examination of the practice all the time, together will ensuring equipment maintenance, the environment used to perform imaging and how best to manage patient throughput, all of which were essential for adherence to professional standards. Professor Sidhu hinted that with a rapid pace of development in ultrasound technology, it is highly likely that the professional standards of today would require updating in the near future. He pointed to the fact that equipment was becoming smaller, so that handheld devices are able to do a reasonable job and ultrasound technology is also available for use on smartphones and an iPad for scanning.

Future plans

Professor Sidhu indicated that one of his aims for the ESR over the next few years was to define the place of ultrasound within radiology more clearly. He remarked on how the position of ultrasound within radiology is far less clear cut than say 20 years ago and that is often seen as the ‘Cinderella’ modality in radiology. He noted for instance how today, a lot of younger radiologists were more interested in CT and MRI scanning because this was perceived as being more cutting edge and that ultrasound is often seen as harder work than the other modalities. After all, clinicians must operate the device, sit with the patient, and scan them, whereas there is no direct patient contact with MRI and CT, with the hard work coming from the ability to form a diagnostic image, readily interpretable. He revealed how for the next ESR meeting in 2022,4 the committee is preparing a session dealing with where they believe ultrasound will sit in 20 years’ time. He stated that there are plans for three speakers at the meeting and who will discuss different models of ultrasound practice. Firstly, there is the German model, in which many GPs perform ultrasound as well as having a centralised hospital department run by radiologists, but with other medical specialists effectively dipping into the service. Second is the Russian model, whereby both radiologists and other physicians only do ultrasound and no other imaging modality. The third, and often perceived as a controversial model, is the one deployed in the UK, where it is the radiologists who performs less scanning, taking on more specialised examinations (e.g. MSK) and delegating the sonographers to effectively undertake most of the scanning, and providing diagnostic reports. He felt that a discussion of the different models would undoubtedly provoke a lively debate. Professor Sidhu mentioned that tied in with this debate will be a position paper on where the ESR believes ultrasound should sit within radiology and how the speciality should evolve over the coming years. Professor Sidhu, though not the final arbiter on any decisions, felt that in the future, perhaps radiologists should not see themselves as guardians of the ultrasound world. He added that anyone from whatever subspecialty and who has an interest and can demonstrate competency and safety in their practice should be encouraged to use ultrasound. Professor Sidhu believed that there was nothing inherently wrong with, for example, a rheumatologist upskilled in the use of ultrasound, if they saw the benefit of the imaging modality in their assessment of a patient. He also thought it possible that radiologists could retain ultrasound within their departments but allowing access to physicians from different specialities with an overarching goal of improvements in patient care. 

A further advantage of ultrasound highlighted by Professor Sidhu was the flexibility of the modality. In contrast to the static imagery of an MRI or CT scan, ultrasound was performed in real-time. Consequently, it was possible during the scan to enquire as to whether the patient experienced any pain or discomfort, particularly if the imaging indicated a potential cause for the pain. Alternatively, the patient may offer a snippet of history during the scanning, and which helps to confirm the diagnosis, neither of which are available to radiologists when interpreting other imaging modalities.

On the impact of the pandemic on imaging 

Professor Sidhu described how King’s was very busy during the first and second waves of the COVID-19 pandemic.5 With the global cancellation of routine imaging during the first wave, the radiology department was quiet with ultrasound becoming extremely useful within the intensive care unit as a point-of-care for imaging of patients’ lungs; this was done predominately by the pulmonary physicians although radiologists did perform some abdominal scans. He added that during the second wave, the department was a lot more prepared and continued with as much routine scanning, if patients could safely attend the hospital, but suspects that this has resulted in a huge backlog of imaging awaiting to be undertaken. While the magnitude of this backlog remains uncertain, Professor Sidhu remarked that there are still a lot of patients waiting to be scanned. 

On the key learnings since the pandemic 

Professor Sidhu thinks that an important learning from the pandemic is that services need to become more patient centric and that the provision of imaging services should become easier and more accessible for the patient. With this idea in mind, there is likely to be a wholesale shift of routine outpatient scanning out of the acute hospital and make greater use of community-based imaging, a move he says which has been supported by government. He mentioned that although this change had been under discussion for several years, it was really brought into sharper focus as a consequence of the pandemic. After all, he reflected on how it has been ludicrous to bring large numbers of patients into a busy hospital for routine/GP imaging. Consequently, there is now a move in progress to establish diagnostic hubs, adjacent or close to the hospital and introducing agreed patient pathways to ensure that only those patients who need further management must visit the hospital. Professor Sidhu felt over the next few years, elective imaging could be undertaken within the hub and that this would release capacity with the hospital, allowing time to see acute patients and those who required other forms of interventional or complex imaging, with the important caveat, that the hospital service is accessible for patients when needed.

On the current exciting technological developments 

Professor Sidhu noted how there were enormous developments in ultrasound technology, and which were of huge benefit. He mentioned that a difficulty was that many people still see ultrasound as only black and white, but that this is no longer the case and ultrasound has a far greater capability for imaging that all other modalities. He cited how multiparametric ultrasound imaging can be used to assess patients with steatotic livers6 and that other innovations such as colour Doppler ultrasound, contrast ultrasound and elastography ultrasound,7 which looks at the stiffness of the liver, the amount of fibrosis and scarring have all proved to be of value in patient care. He added that a further advantage of the developments in ultrasound was that the technology was less expensive than other modalities and safe. He sensed that in the next couple of years there would be many further innovations with ultrasound-based technology and that these would continue to be patient-friendly. Using the example of scanning the liver of a two- or three-year-old child, Professor Sidhu described how for an MRI scan, the child needed to be sedated perhaps, given the contrast agent gadolinium, and kept still. However, for an ultrasound scan, the child remains awake, and the parents can also be present to help with any possible anxiety. He thought that as an imaging modality, radiologists would be ultimately unwise to give up on ultrasound, adding that the technology is now at a level where the device does almost everything for the operator, adjusting the parameters automatically to produce the best image. 

Another development that had made a considerable impact on ultrasound mentioned by Professor Sidhu was artificial intelligence. The technology can recognise the organs under investigation, identifies any abnormalities as well as providing a differential diagnosis. He added that it even writes the report for the operator although currently, it still needs a clinician to interpret the results of the scan.

On the skills that radiologists will require in the future

Professor Sidhu thinks that will all the emerging technologies, some radiologists have been left behind simply because the developments in ultrasound are largely driven by physicians in other specialties; in particular, hepatologists. He explained how a key driver is not so much that other specialists embrace the technology but more that unlike radiologists, hepatologists and other specialties do not have routine access to CT and MRI, ensuing the best aspects of ultrasound are utilised constantly, before reverting to another imaging modality. 

Even though in the future ultrasound might well move outside of the sphere of radiology, Professor Sidhu still believes that there will always be a need for radiologists to be skilful in ultrasound. As a profession, they possess the necessary skills to match up the results from all the other scans and images and in doing, so will continue to make an important contribution to patient care.


  1. Nyhsen C et al. Infection prevention and control in ultrasound – best practice recommendations from the European Society of Radiology Ultrasound Working Group. Insights Imaging 2017;8(6):523–35.
  2. European Society of Radiology. Position statement and best practice recommendations on the imaging use of ultrasound from the European Society of Radiology ultrasound subcommittee. Insights Imaging 2020;11:115.
  3. ESR Executive Council 2009; European Society of Radiology. ESR position paper on ultrasound. Insights Imaging 2010;1(1):27–9.
  4. ESR Congress.
  5. Panayiotou A et al. Escalation and De-escalation of the Radiology Response to COVID-19 in a Tertiary Hospital in South London: The King’s College Hospital Experience. Br J Radiol 2020;93:20201034.
  6. Basavarajappa L et al. Multiparametric ultrasound imaging for the assessment of normal versus steatotic livers. Sci Rep 2021;11:2655.
  7. Sigrist R et al. Ultrasound elastography: Review of techniques and clinical applications. Theranostics 2017;7(5):1303–29.