When evaluating the abdomen for abnormalities, there are a number of imaging tests that may be performed. One such technique, magnetic resonance cholangiopancreatography (MRCP), can provide information about the patient's hepatobiliary and pancreatic systems. New technology may affect the techniques used, as well as patient comfort to improve the imaging process for the hospital.1
Magnetic resonance cholangiopancreatography
MRCP utilizes magnetic resonance techniques to evaluate the liver, gallbladder, bile ducts, pancreas and pancreatic duct for disease through the use of detailed images.2 This method is particularly useful, because it is non-invasive and does not expose the patient to ionizing radiation. MRCP is an alternative to endoscopic retrograde cholangiopancreatography (ERCP).
Unfortunately, one of the challenges to completing an MRCP scan comes from the need for a patient to alter their breathing.1 This is a common challenge when imaging the abdomen, since that region of the body is affected by respiratory motion and sometimes cardiac motion. In order to minimize the affect of respiratory motion on the scan, the patient often has to hold their breath, which can be difficult in patients with emergent or chronic conditions. In these cases, the goal is to obtain images of a diagnostic quality with reduced breath-holding.
New techniques may impact 3D MRCP protocols
At Saint-Joseph Hospital in Paris, France, the radiology department believes that a new MRI technique involving compressed sensing acceleration may have a long-term impact on how they conduct MRCPs. Compressed sensing is a method that can reduce the necessary scan time for a MRCP exam. This is done by sparse data sampling and iterative reconstruction to decrease scan times and increase resolution.1
Because the team at Saint-Joseph Hospital, led by Dr. Marc Zins as the Head of the Radiology Department, believes that 3D MRCP is highly accurate, they decided to investigate the use of compressed sensing to accelerate their scans.1 As they did so, they compared four different techniques for their acquisition: their existing protocol, a conventional respiratory-triggered Coronal 3D MRCP, a Coronal MRCP respiratory-triggered exam with compressed sensing and a Coronal 3D MRCP breath-hold exam using compressed sensing.
All of the patients fasted for at least four hours in order to reduce the amount of fluid in stomach and digestive tract, as well as distend the gallbladder and limit duodenal peristalsis.1 The patients also had no prior administration of anti-peristalsis. Pineapple juice was used to help act as a negative contrast agent, which may limit signal interference related to digestive tract fluid in the resultant images.
When the methods were compared, the team found that, between the respiratory-triggered conventional 3D MRCP and the respiratory-triggered 3D MRCP with compressed sensing, there was similar image quality, even with the use of compressed sensing to reduce scan time by at least 34%.1 Additionally, respiratory-triggered and breath-holding 3D MRCP with compressed sensing had different spatial resolutions.1 However, the breath-hold scans often provided information needed for the doctor to make a confident diagnosis.1
Saint-Joseph Hospital and its radiology team saw so much of an impact that their protocol replaced respiratory-triggered Coronal 3D MRCP with Coronal 3D MRCP with respiratory-triggering and compressed sensing at a factor of 1.6. In the future, additional facilities may see the same impact on their practices as the techniques become more common. Magnetic resonance imaging of the abdomen may have just become faster and more comfortable with the introduction of compressed sensing.
- 3D MRCP with HyperSense: an evaluation of respiratory-triggered and breath-hold sequences. SIGNA Pulse of MR. http://www.gesignapulse.com/signapulse/spring_2019/MobilePagedArticle.action?articleId=1488825&app=false#articleId1488825. Last accessed October 15, 2019.
- Magnetic Resonance Cholangiopancreatography (MRCP). RadiologyInfo.org. https://www.radiologyinfo.org/en/info.cfm?pg=mrcp. Last accessed October 15, 2019.