MR cholangiopancreatography at 3.0 T: intraindividual comparative study with MR cholangiopancreatography at 1.5 T for clinical patients

Screening for pancreatic cancer in high-risk individuals using MRI: optimization of scan techniques to detect small lesions

Pancreatic cancer has a dismal prognosis in the general population. However, early detection and treatment of disease in high-risk individuals can improve survival, as patients with localized disease and especially patients with lesions smaller than 10 mm show greatly improved 5-year survival rates. To achieve early detection through MRI surveillance programs, optimization of imaging is required. Advances in MRI technologies in both hardware and software over the years have enabled reliable detection of pancreatic cancer at a small size and early stage. Standardization of dedicated imaging protocols for the pancreas are still lacking. In this review we discuss state of the art scan techniques, sequences, reduction of artifacts and imaging strategies that enable early detection of lesions. Furthermore, we present the imaging features of small pancreatic cancers from a large cohort of high-risk individuals. Refinement of MRI techniques, increased scan quality and the use of artificial intelligence may further improve early detection and the prognosis of pancreatic cancer in a screening setting.

Pancreatic Duct in Autoimmune Pancreatitis: Intraindividual Comparison of Magnetic Resonance Pancreatography at 1.5 T and 3.0 T

OBJECTIVE

The aim of this study was to intraindividually compare magnetic resonance pancreatography (MRP) image quality at 1.5 T and 3.0 T when demonstrating main pancreatic duct (MPD) abnormalities in patients with autoimmune pancreatitis (AIP).

METHODS

Thirty prospectively enrolled patients with AIP underwent MRP at both 1.5 T and 3.0 T followed by endoscopic retrograde pancreatography before treatment. Two readers independently analyzed the MRP images and graded the visualization of MPD strictures and full-length MPD, using endoscopic retrograde pancreatography as the reference standard, as well as overall image artifacts on a 4-point scale. The contrast between the MPD and periductal area was calculated using a region-of-interest measurement.

RESULTS

Visualization scores of MPD strictures and full-length MPD, and summed scores of each qualitative analysis, were significantly greater at 3.0-T MRP than at 1.5-T MRP for both readers (P ≤ 0.02). There were less image artifacts at 3.0 T compared with 1.5 T (P ≤ 0.052). The contrast between the MPD and periductal area was significantly greater at 3.0-T MRP than at 1.5-T MRP (P < 0.001).

CONCLUSIONS

The MRP at 3.0 T was superior to 1.5-T MRP for demonstrating MPD abnormalities in AIP, with better image contrast and fewer image artifacts. Consequently, 3.0-T MRP may be useful for the diagnosis and management of patients with AIP.

Comparison of respiratory-triggered 3-D fast spin-echo and single-shot fast spin-echo radial slab MR cholangiopancreatography images in children

BACKGROUND

The two most commonly performed magnetic resonance cholangiopancreatography (MRCP) sequences, 3-D fast spin-echo (3-D FSE) and single-shot fast spin-echo radial slabs (radial slabs), have not been compared in children.

OBJECTIVE

The purpose of this study was to compare 3-D FSE and radial slabs MRCP sequences on a 3-T scanner to determine their ability to show various segments of pancreaticobiliary tree and presence of artifacts in children.

MATERIALS AND METHODS

We reviewed 79 consecutive MRCPs performed in 74 children on a 3-T scanner. We noted visibility of major ducts on 3-D FSE and radial slabs. We noted the order of branching of ducts in the right and left hepatic ducts and the degree of visibility of the pancreatic duct. Statistical analysis was performed using McNemar and signed rank tests.

RESULTS

There was no significant difference in the visibility of major bile ducts and the order of branching in the right hepatic lobe between sequences. A higher order of branching in the left lobe was seen on radial slabs than 3-D FSE (mean order of branching 2.82 versus 2.27; P-value = 0.0002). The visibility of pancreatic duct was better on radial slabs as compared to 3-D FSE (mean value of 1.53 vs. 0.90; P-value < 0.0001). 3-D FSE sequence was artifact-free in 25/79 (31.6%) MRCP exams as compared to radial slabs, which were artifact-free in 18/79 (22.8%) MRCP exams (P-value = 0.0001).

CONCLUSION

There is no significant difference in the visibility of major bile ducts between 3-D FSE and radial slab MRCP sequences at 3-T in children. However, radial slab MRCP shows a higher order of branching in the left hepatic lobe and superior visibility of the pancreatic duct than 3-D FSE.

How reliable is MRCP with an SS-FSE sequence at 3.0 T: comparison between SS-FSE BH and 3D-FSE BH ASSET sequences

PURPOSE

The purpose of the present study was to evaluate the visibility and the image quality of the biliary and pancreatic duct system on magnetic resonance cholangiopancreatography (MRCP) images based on two breath-hold (BH) methods using array spatial sensitivity technique: a single-shot fast spin-echo (SS-FSE) sequence and a three-dimensional single slab fast spin-echo (3D-FSE) sequence.

MATERIALS AND METHODS

In the present prospective comparative study, 47 patients (22 male and 25 female, mean age=50 years, age range=22-82 years) that were referred for MRCP during a 12-month period are included. All of them were referred with suspected pancreaticobiliary disease. All patients underwent MRCP with both a SS-FSE BH sequence and a 3D-FSE BH sequence. Qualitative evaluation regarding the depiction of three segments of the pancreaticobiliary tree and the frequency of artifacts was performed. Two radiologists graded each sequence of the obtained studies in a blinded fashion. Quantitative evaluation including calculation of relative signal intensity (rSI) and relative contrast (RC) ratios at seven segments of the pancreaticobiliary tree between fluid-filled ductal structures and organ parenchyma at the same ductal segments was performed. In order to evaluate the parameters' differences of the two sequences, either in qualitative or in quantitative analysis, the Wilcoxon paired signed-rank test was performed.

RESULTS

On quantitative evaluation, both rSI and RC ratios of all segments of the pancreaticobiliary tree at SS-FSE BH sequence were higher than those at 3D-FSE BH sequences. This finding was statistically significant (P<.01). On qualitative evaluation, the two radiologists found intrahepatic ducts and pancreatic ducts to be better visualized with SS-FSE BH than with 3D-FSE BH sequence. This finding was statistically significant (P<.02). One of them found extrahepatic ducts to be significantly better visualized with SS-FSE BH sequence. Moreover, the frequency of artifacts was lower in the SS-FSE sequence, a finding that was of statistical significance. Interobserver agreement analysis found at least substantial agreement (κ>0.60) between the two radiologists.

CONCLUSION

The SS-FSE sequence is performed faster and significantly improves image quality; thus, it should be included into the routine MRCP sequence protocol at 3.0 T. Furthermore, we recommended SS-FSE BH MRCP examination to be applied to uncooperative patients or patients in emergency because of its short acquisition time (1 s).

MR cholangiopancreatography at 3.0 T in children: diagnostic quality and ability in assessment of common paediatric pancreatobiliary pathology

OBJECTIVE

To assess the diagnostic quality of MR cholangiopancreatography (MRCP) at 3.0 T in children and to assess its diagnostic ability in answering the clinical query. Also, to determine the frequency of artefacts and anatomic variations in ductal anatomy.

METHODS

Consecutive MRCPs performed in children using a 3-T scanner were retrospectively reviewed to note indications, findings, imaging diagnosis, normal variants, quality and artefacts. Analysis was performed based on the final diagnosis assigned by pathology or the combination of clinical, laboratory, imaging features and follow-up to determine whether it was possible to answer the clinical query by MRCP findings.

RESULTS

There were 82 MRCPs performed at 3.0 T on 77 children. 42/82 (51%) MRCPs were of good quality, 35/82 (43%) MRCPs were suboptimal but diagnostic and the remaining 5/82 (6%) MRCPs were non-diagnostic. MRCP answered the clinical query in 61/82 (74%) cases; however, it did not answer the clinical query in 11/82 (14%) cases and was equivocal in 10/82 (12%) cases. There was significant association between the quality of MRCP and the ability of MRCP to answer the clinical query (p<0.0001). 64/82 (78%) MRCP examinations had at least 1 artefact. Variation in the bile duct anatomy was seen in 27/77 (35%) children.

CONCLUSION

MRCP performed at 3.0 T is of diagnostic quality in most cases and is able to provide an answer to the clinical query in the majority of cases.

ADVANCES IN KNOWLEDGE

3-T MRCP is feasible and useful in the assessment of pancreatobiliary abnormalities in children.

MR imaging techniques for pancreas

Pancreatic magnetic resonance (MR) imaging has become a useful tool in evaluating pancreatic disorders. Technical innovations in MR imaging have evolved over the last decade, with most sequences being performed in one or a few breath-holds. Three-dimensional sequences with thin, contiguous slices allow for improved spatial resolution on the postgadolinium images and MR cholangiopancreatography (MRCP). The diagnostic potential of MRCP is equivalent to endoscopic retrograde pancreatography, particularly when intravenous secretin is used to enhance the pancreatic duct assessment. This article highlights the advantages and disadvantages of state-of-the-art and emerging pulse sequences and their application to imaging pancreatic diseases.

CT and MR cholangiography: advantages and pitfalls in perioperative evaluation of biliary tree

Recent developments in imaging technology have enabled CT and MR cholangiopancreatography (MRCP) to provide minimally invasive alternatives to endoscopic retrograde cholangiopancreatography for the pre- and post-operative assessment of biliary disease. This article describes anatomical variants of the biliary tree with surgical significance, followed by comparison of CT and MR cholangiographies. Drip infusion cholangiography with CT (DIC-CT) enables high-resolution three-dimensional anatomical representation of very small bile ducts (e.g. aberrant branches, the caudate branch and the cystic duct), which are potential causes of surgical complications. The disadvantages of DIC-CT include the possibility of adverse reactions to biliary contrast media and insufficient depiction of bile ducts caused by liver dysfunction or obstructive jaundice. Conventional MRCP is a standard, non-invasive method for evaluating the biliary tree. MRCP provides useful information, especially regarding the extrahepatic bile ducts and dilated intrahepatic bile ducts. Gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid-enhanced MRCP may facilitate the evaluation of biliary structure and excretory function. Understanding the characteristics of each type of cholangiography is important to ensure sufficient perioperative evaluation of the biliary system.

State-of-the-art pancreatic MRI

OBJECTIVE

The purpose of this article is to discuss the most current techniques used for pancreatic imaging, highlighting the advantages and disadvantages of state-of-the-art and emerging pulse sequences and their application to pancreatic disease.

CONCLUSION

Given the technologic advances of the past decade, pancreatic MRI protocols have evolved. Most sequences can now be performed in one or a few breath-holds; 3D sequences with thin, contiguous slices offer improved spatial resolution; and better fat and motion suppression allow improved contrast resolution and image quality. The diagnostic potential of MRCP is now almost as good as ERCP, with pancreatic MRI as the main imaging technique to investigate biliopancreatic pain, chronic pancreatitis, and cystic pancreatic tumors at many institutions. In addition, functional information is provided with secretin-enhanced MRCP.