Computer-aided diagnostics for clinicians
Professor Sanjay Gandhi is a senior consultant radiologist at North Bristol NHS Trust and NBT Lead Clinician for Radiation Protection and Lead Radiologist for Haematology Cancer MDT. He joins MediSens as a guest speaker in 2018. We caught up with Sanjay to ask about the use of CT in colonography in the last few weeks before his conference session on computer-aided diagnostics.
Talk us through the CT virtual colonography…
CT colonography (CTC), known also as CT colonoscopy, is a safe, more sensitive and better tolerated radiological test for evaluation of the whole colon compared to barium enema examination. Several clinical trials over the last decade have shown a similar accuracy to conventional colonoscopy in detecting polyps and colorectal cancers.
At our institute (North Bristol NHS Trust), we developed a CT colonography service with an emphasis on patient comfort and safety. A CT procedure takes only 15 minutes and is therefore quicker than colonoscopy. An antispasmodic is administered by an intravenous injection to diminish bowel peristalsis. This also reduces bowel spasms and colic in the patient. A soft fine-bore rectal tube is inserted and connected to an automated carbon dioxide insufflator to ensure adequate distension of rectum and colon. The patient is scanned in the supine position (lying on their back) using a moderate to low CT radiation dose protocol, followed by the prone scan with an even lower dose. Scanning in two positions ensures that a polyp or cancer is not obscured by the presence of fluid or faecal material, which is normally present in the lumen of the colon.
A typical CTC examination generates approximately 2000 images, which include multiplanar reconstructions of supine and prone series in the axial, coronal and sagittal planes. Images are interpreted by trained radiologists on CT workstations and reviewed on soft tissue, colonic and bone widows. This allows for assessment of solid abdominal viscera, spine and other bones in addition to any colonic pathology. Visualised parts of lungs are also assessed.
In addition to 2D scans, the majority of radiologist also review 3D rendered virtual colonoscopy images, which allow an endoluminal view of colon and ﬂy through. Increasingly, Computer Aided Detection (CAD) software is employed in a second read paradigm.
Ionising radiation has a negative impact versus the current all-in-one approach to optical detection and surgery in one go – What’s the advantage?
Like all CT exams, CTC uses ionising radiation and therefore should be used judiciously, particularly in younger patients. The dose should be kept as low as is reasonably practicable (the ALARP principle). Fortunately, modern CT scanners offer comparatively low dose scan protocols and dose modulation algorithms. Most patients undergoing CTC are over the age of 60 and have comorbidities. Therefore, in this population group, an actual lifetime risk of harm from a diagnostic CT scan is very low and unlikely to influence their life expectancy. Benefits of an accurate diagnosis far outweigh any risk from CT.
Advantages: Unlike colonoscopy, CTC does not require the insertion and manipulation of a colonoscope. Using a small soft fine-bore catheter in the rectum, the patient undergoes gas insufflation of the colon. CTC is safer in elderly and frail patients as it can use milder laxative regimens. The patient remains awake during CT scanning, whereas sedation is often necessary for colonoscopy.
CTC has a very low perforation rate (0.005 to 0.05%), compared to 0.08% with optical colonoscopy. In an unlikely event of perforation, bowel defect is often very small and usually evident during the CT scanning. In the vast majority of cases, such perforation is self-limiting.
CTC not only enables the assessment of tumours, it has the advantage of providing additional information such as any local invasion, lymph node enlargement and metastases. Another benefit of CTC over colonoscopy is that it allows for the evaluation of colon proximal to obstructing tumours to exclude synchronous lesions.
Another significant advantage of CT is its ability to review of extra-colonic organs. Approximately 10% of CTC examinations reveal potentially significant extra-colonic abnormalities such lymphoma, pancreatic, renal or ovarian malignancy and abdominal aortic aneurysms.
Imaging techniques from medicine routinely enter other industries, are there any use-cases from elsewhere you think can be useful in medical diagnostics?
Historically, medical diagnostics and several branches of engineering such as aviation and petrochemical industries have mutually benefited from new discoveries. For example, X-ray, Ultrasound and MRI are used both in medicine as engineering and allied industries. Similarly, technical advancement in computer hardware and software has helped healthcare diagnostics via digital imaging, machine learning and CAD. Over the next decade, the use of robots and microrobots is also expected to increase significantly in the healthcare sector.
To what extent should clinicians take responsibility for innovating new approaches?
Clinicians are patients’ advocates and know their healthcare needs very well, therefore, it is vital for clinicians to provide leadership in developing new technology and innovative solutions.
From my experience in developing teaching Apps and diagnostic AI projects, I am convinced that the end products are superior when clinicians are actively involved in innovations.
Who are you expecting to see in your session at the conference?
I am expecting to see Radiologists, Oncologists and other cancer specialists. I also hope to share our research work with AI and machine learning experts and software developers.
Away from work, what do you enjoy doing with your spare time?
Traveling and learning about different cultures has been a lifelong hobby. In addition to writing textbooks in my spare time, I have been writing a crime thriller. I also enjoy reading as well as networking.
What’s your favourite word, and what does it mean?
My favourite word is ‘Gyan’, which in Sanskrit and Hindi means ‘knowledge’.
Gyan is a treasure that increases in value when we share it with others. According to many Asian religions such as Hinduism, Jainism and Buddhism, the best donation of all is ‘gyan-daan’, the donation of knowledge. We can create a better world through sharing knowledge and expertise.
It’s your first visit to MediSens, what are you looking forward to?
MediSens has created an excellent programme and there are a number of eminent speakers at this conference. I am looking forward to sharing their experience to improve patient care. As Research and Innovation Lead for Core Clinical Services at my NHS Trust, I would utilise networking sessions as a platform to foster research collaborations.
Professor Sanjay Gandhi is a senior consultant radiologist at North Bristol NHS Trust and NBT Lead Clinician for Radiation Protection and Lead Radiologist for Haematology Cancer MDT.
His MediSens conference session “Advances in computer-aided diagnosis; how should radiologists and oncologists embrace this technology?” will be delivered on February 26th.