MRCP imaging at 3.0 T vs. 1.5 T: preliminary experience in healthy volunteers

Verification of image quality improvement by deep learning reconstruction to 1.5 T MRI in T2-weighted images of the prostate gland

This study aimed to evaluate whether the image quality of 1.5 T magnetic resonance imaging (MRI) of the prostate is equal to or higher than that of 3 T MRI by applying deep learning reconstruction (DLR). To objectively analyze the images from the 13 healthy volunteers, we measured the signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the images obtained by the 1.5 T scanner with and without DLR, as well as for images obtained by the 3 T scanner. In the subjective, T2W images of the prostate were visually evaluated by two board-certified radiologists. The SNRs and CNRs in 1.5 T images with DLR were higher than that in 3 T images. Subjective image scores were better for 1.5 T images with DLR than 3 T images. The use of the DLR technique in 1.5 T MRI substantially improved the SNR and image quality of T2W images of the prostate gland, as compared to 3 T MRI.

Magnetic resonance cholangiopancreatography versus endoscopic ultrasound for diagnosis of choledocholithiasis: an updated systematic review and meta-analysis

INTRODUCTION

Both endoscopic ultrasound (EUS) and magnetic resonance cholangiopancreatography (MRCP) are used for the diagnosis of choledocholithiasis (CDL). Previous studies have shown conflicting results regarding the optimal diagnostic strategy for suspected CDL; hence, this meta-analysis was conducted.

METHODS

A comprehensive search of literature from 1990 till April 2022 was done of three databases for studies comparing EUS and MRCP to diagnose CDL.

RESULTS

A total of 12 studies were identified. The pooled sensitivity and specificity for EUS were 0.96 [95% confidence interval (CI) 0.92-0.98], and 0.92 (95% CI 0.85-0.96), respectively. The pooled sensitivity and specificity for MRCP were 0.85 (95% CI 0.78-0.90) and 0.90 (95% CI 0.79-0.96), respectively. EUS had a higher relative sensitivity [Relative risk (RR) 1.12, 95% CI 1.05-1.19], a higher diagnostic accuracy (Odds ratio 1.98, 95% CI 1.35-2.90) but comparable specificity (RR 1.02, 95% CI 0.96-1.08) with MRCP.

CONCLUSION

There is little difference concerning specificity, although EUS likely provides a higher sensitivity and accuracy for diagnosing CDL, compared to MRCP.

Imaging of the biliary tract

PURPOSE OF REVIEW

Magnetic resonance cholangiopancreatography (MRCP) has become the reference examination for the exploration of the biliary tract and has replaced endoscopic cholangiography for the analysis of the biliary tract because of its equivalent performance and its noninvasive character.

RECENT FINDINGS

Based on the International Primary Sclerosing Cholangitis (PSC) Study Group recommendations for MR imaging in PSC, two protocols can be distinguished for the imaging of biliary tract: a basic protocol and a more complete protocol. It is essential to know the main pitfalls in order not to wrongly describe biliary anomalies. In addition to the excellent performance of MR imaging with MRCP in analyzing the anatomy and the anomalies of the biliary tree, complementary techniques have recently been developed. Several MR prognostic factors have been described. New hepato-specific contrast agents are now available for assessment of the general and segmental liver function. MR Elastography and Diffusion-weighted MR sequences are accurate to evaluate the degree of hepatic fibrosis. Finally, images obtained in MRCP can be postprocessed by a software that will analyze and model the biliary tree in order to quantitatively evaluate the biliary system.

SUMMARY

Magnetic resonance imaging with its recent developments becomes by now an essential tool for the evaluation of biliary diseases.

Patient- and Examination-Related Predictors of 3D MRCP Image Quality in Children

BACKGROUND. MRCP provides noninvasive imaging of the biliary tree and pancreatic duct. In our experience, MRCP image quality is commonly suboptimal in children. OBJECTIVE. The purpose of this study was to characterize the frequency of nondi-agnostic 3D fast spin-echo (FSE) MRCP acquisitions and determine predictors of nondi-agnostic MRCP image quality in children. METHODS. This retrospective study included 200 randomly selected pediatric patients (101 female and 99 male patients; mean age, 11.7 years) who underwent MRCP between January 1, 2019, and December 31, 2020. Patient- and examination-related variables were recorded. Three fellowship-trained pediatric radiologists independently reviewed 3D FSE MRCP acquisitions for diagnostic quality (diagnostic vs nondiagnostic) and overall image quality score on a scale from 1 to 5 (1 = worst image quality imaginable, 5 = best image quality imaginable). After computing interreader agreement, analyses used readers' most common diagnostic quality assessment and mean image quality score. Multivariable logistic regression and linear regression analyses were used to identify predictor variables of a diagnostic examination and higher image quality score. RESULTS. Interreader agreement for an MRCP acquisition being diagnostic quality, expressed as a kappa coefficient, was 0.53-0.71; interreader agreement for image quality score, expressed as an intraclass correlation coefficient, was 0.68-0.74. A total of 36 of 200 (18%) MRCP acquisitions were nondiagnostic; the mean image quality score was 3.5 ± 1.1 (SD). Multivariable predictors of a diagnostic MRCP acquisition included greater body mass index (OR = 1.11 [95% CI, 1.02-1.21]; p = .02), scanner field strength of 1.5 T (odds ratio [OR] = 2.87 [95% CI, 1.23-6.68]; p = .01), and presence of acute pancreatitis (OR = 4.91 [95% CI, 1.53-15.77]; p = .008). Multivariable predictors of a higher image quality score (β = 0.05-0.94) included older age (p = .01), imaging performed with patient under sedation or general anesthesia (p < .001), presence of biliary dilatation (p = .004), and inpatient status (p = .02). A lower image quality score was predicted by a scanner field strength of 3 T (β = -0.61; p < .001). A greater amount of time between the start of the MRI examination and the MRCP acquisition exhibited a nonsignificant association with a decrease in the image quality score (p = .06). CONCLUSION. Pediatric MRCP acquisitions are commonly nondiagnostic. Patient-specific and technical factors systematically impact MRCP image quality in children. CLINICAL IMPACT. Recognition of image quality predictors that are potentially modifiable and amendable to proactive intervention can guide efforts to optimize MRCP image quality in children.

Amendment of the Japanese consensus guidelines for autoimmune pancreatitis, 2020

In response to the latest knowledge and the amendment of the Japanese diagnostic criteria for autoimmune pancreatitis (AIP) in 2018, the Japanese consensus guidelines for managing AIP in 2013 were required to be revised. Three committees [the professional committee for developing clinical questions (CQs) and statements by Japanese specialists; the expert panelist committee for rating statements by the modified Delphi method; and the evaluating committee of moderators] were organized. Twenty specialists in AIP extracted the specific clinical statements from a total of 5218 articles (1963-2019) from a search in PubMed and the Cochrane Library. The professional committee made 14, 9, 5, and 11 CQs and statements for the current concept and diagnosis, extra-pancreatic lesions, differential diagnosis, and treatment, respectively. The expert panelists regarded the statements as valid after a two-round modified Delphi approach with individually rating these clinical statements, in which a clinical statement receiving a median score greater than 7 on a 9-point scale from the panel was regarded as valid. After evaluation by the moderators, the amendment of the Japanese consensus guidelines for AIP has been proposed in 2020.

Breath-hold 3D magnetic resonance cholangiopancreatography at 1.5 T using a deep learning-based noise-reduction approach: Comparison with the conventional respiratory-triggered technique

OBJECTIVES

To assess the image quality of conventional respiratory-triggered 3-dimentional (3D) magnetic resonance cholangiopancreatography (Resp-MRCP) and breath-hold 3D MRCP (BH-MRCP) with and without denoising procedure using deep learning-based reconstruction (dDLR) at 1.5 T.

METHODS

Forty-two patients underwent MRCP at 1.5 T MRI. The following imaging sequences were performed: Resp-MRCP and BH-MRCP. We applied the dDLR method to the BH-MRCP data (BH-dDLR-MRCP). As a qualitative analysis, two radiologists rated the visibility of the proximal common bile duct (CBD), pancreaticobiliary junction, distal main pancreatic duct, cystic duct, and right and left hepatic ducts. Artifacts and overall image quality were also rated. The signal-to-noise ratios (SNRs), contrast ratios, and contrast-to-noise ratios (CNRs) of the CBD images were calculated for quantitative analysis.

RESULTS

BH-MRCP was successfully performed in a single BH. The qualitative and quantitative measurements for BH-dDLR-MRCP were significantly higher than for BH-MRCP (P < 0.02 and P < 0.001, respectively), and the qualitative measurements for BH-dDLR-MRCP were equivalent to or higher than for Resp-MRCP (P = 0.048-1.000). The SNRs and CNRs for BH-dDLR-MRCP were significantly higher than for Resp-MRCP (P < 0.001 and P = 0.001, respectively).

CONCLUSION

dDLR is useful and clinically feasible for BH-MRCP at 1.5 T MRI, and enables rapid imaging without loss of image quality compared to conventional Resp-MRCP.

The Sclerosing Cholangitis Outcomes in Pediatrics (SCOPE) Index: A Prognostic Tool for Children

BACKGROUND AND AIMS

Disease progression in children with primary sclerosing cholangitis (PSC) is variable. Prognostic and risk-stratification tools exist for adult-onset PSC, but not for children. We aimed to create a tool that accounts for the biochemical and phenotypic features and early disease stage of pediatric PSC.

APPROACH AND RESULTS

We used retrospective data from the Pediatric PSC Consortium. The training cohort contained 1,012 patients from 40 centers. We generated a multivariate risk index (Sclerosing Cholangitis Outcomes in Pediatrics [SCOPE] index) that contained total bilirubin, albumin, platelet count, gamma glutamyltransferase, and cholangiography to predict a primary outcome of liver transplantation or death (TD) and a broader secondary outcome that included portal hypertensive, biliary, and cancer complications termed hepatobiliary complications (HBCs). The model stratified patients as low, medium, or high risk based on progression to TD at rates of <1%, 3%, and 9% annually and to HBCs at rates of 2%, 6%, and 13% annually, respectively (P < 0.001). C-statistics to discriminate outcomes at 1 and 5 years were 0.95 and 0.82 for TD and 0.80 and 0.76 for HBCs, respectively. Baseline hepatic fibrosis stage was worse with increasing risk score, with extensive fibrosis in 8% of the lowest versus 100% with the highest risk index (P < 0.001). The model was validated in 240 children from 11 additional centers and performed well.

CONCLUSIONS

The SCOPE index is a pediatric-specific prognostic tool for PSC. It uses routinely obtained, objective data to predict a complicated clinical course. It correlates strongly with biopsy-proven liver fibrosis. SCOPE can be used with families for shared decision making on clinical care based on a patient's individual risk, and to account for variable disease progression when designing future clinical trials.

Navigator-triggered and breath-hold 3D MRCP using compressed sensing: image quality and method selection factor assessment

PURPOSE

To examine whether MRCP using a combination of compressed sensing and sensitivity encoding with navigator-triggered and breath-hold techniques (NT C-SENSE and BH C-SENSE, respectively) have comparable image quality to that of navigator-triggered MRCP using only sensitivity encoding (NT SENSE) at 1.5-T.

METHODS

Fifty-one participants were enrolled in this prospective study between July and October 2018 and underwent the three 3D MRCP sequences each. The acquisition time and relative duct-to-periductal contrast ratios (RC values) of each bile duct segment were obtained. Visualization of the bile and main pancreatic ducts, background suppression, artifacts, and overall image quality were scored on 5-point scales. Mean and median differences in RC values and qualitative scores of NT C-SENSE and BH C-SENSE relative to NT SENSE were calculated with 95% confidence intervals (CIs).

RESULTS

Acquisition time of NT SENSE, NT C-SENSE, and BH C-SENSE were 348, 143 (mean for both), and 18 s (for all participants), respectively. The RC value of each bile duct segment was inferior, but the lower limits of the 95% CIs of the mean differences were ≥ - 0.10, for both NT C-SENSE and BH C-SENSE. The visualization score of the intrahepatic duct in BH C-SENSE was inferior to that in NT SENSE (lower 95% CI limit, - 1.5). In both NT C-SENSE and BH C-SENSE, the 95% CIs of the median differences in the other qualitative scores were from - 1.0 to 0.0.

CONCLUSION

NT C-SENSE and BH C-SENSE have comparable image quality to NT SENSE at 1.5-T.

Advances in MR Imaging of the Biliary Tract

Imaging of the biliary system has improved and has allowed MR to become a key noninvasive tool for evaluation of the biliary system. A variety of magnetic resonance cholangiopancreatography techniques have been developed, with improved visualization of the biliary system and biliary pathology. Key avenues of advancement include increasing the speed of acquisition, improving spatial resolution, and reducing artifacts. T1-weighted imaging using gadolinium-based hepatobiliary contrast agents allows for evaluation in additional indications, such as liver donor evaluation, biliary leak identification, and choledochal cyst confirmation. There is potential for further increased utility of MR in the evaluation of the biliary system.

Comparison Between Pre-operative Radiologic Findings and the Actual Operative Findings of the Graft in Adult Living Donor Liver Transplantation

BACKGROUND

Computed tomography (CT) volumetry and magnetic resonance cholangiopancreatography (MRCP) are mandatory steps for the evaluation of potential donors in living donor liver transplantation. The aim of this study is to compare the preoperative CT volumetry and biliary orifices of the donor graft to the actual operative findings.

METHODS

Between December 2013 and December 2017, 45 donors (27 men and 18 women) with a mean age of 27.3 years (range, 19-41 years) were evaluated preoperatively by CT volumetry and MRCP at the National Hepatology and Tropical Medicine Research Institute in Cairo, Egypt. Of the donors, 43 out of 45 underwent intraoperative cholangiography before and after bile duct division. The right hepatectomies for all donors, as well as the actual weight and apparent biliary orifices in the graft, were documented.

RESULTS

The mean estimated graft volume (EGV) preoperatively by CT volumetry was 894.9 ± 184.2 mL (range, 480-1687 mL), whereas the actual graft weight (AGW) intraoperatively after washout was 862.6 ± 124.4 g (range, 676-1110 g). The correlation coefficient between the EGV and AGW was significantly linear (Y = 0.96X, r² = 0.72, slope: 0.96, P < .001). The accuracy of the MRCP in preoperative biliary mapping was 76.7% whereas the accuracy of the MRCP in predicting the number of graft biliary orifices was 74.4% compared with the intraoperative cholangiography (IOC), which was 95.3% (P < .001).

CONCLUSION

The weight of the right lobe of the liver graft in living donor liver transplants (LDLTs) can be accurately predicted preoperatively by multiplying the EGV by 0.96. Also, the IOC is an essential technique for LDLT.

Recommendations on the use of magnetic resonance imaging in PSC-A position statement from the International PSC Study Group

Primary sclerosing cholangitis (PSC) is a chronic cholestatic liver disorder characterized by inflammation and fibrosis of the intra- and/or extrahepatic bile ducts. Magnetic resonance imaging (MRI) is a noninvasive imaging modality that can be used to diagnose PSC and detect disease related complications. Quantitative MRI technologies also have the potential to provide valuable prognostic information. Despite the potential of this imaging technology, the clinical application of MRI in the care of PSC patients and imaging standards vary across institutions. Moreover, a unified position statement about the role of MRI in the care of PSC patients, quality imaging standards, and its potential as a research tool is lacking.

CONCLUSION

Members of the International PSC Study Group and radiologists from North America and Europe have compiled the following position statement to provide guidance regarding the application of MRI in the care of PSC patients, minimum imaging standards, and future areas of research. (Hepatology 2017;66:1675-1688).

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.

Usefulness of three-dimensional magnetic resonance cholangiopancreatography with partial maximum intensity projection for diagnosing autoimmune pancreatitis

PURPOSE

To compare three-dimensional magnetic resonance cholangiopancreatography (MRCP) with/without partial maximum intensity projection (MIP) and endoscopic retrograde cholangiopancreatography (ERCP) in patients with autoimmune pancreatitis (AIP).

MATERIALS AND METHODS

Three-dimensional MRCP and ERCP images were retrospectively analyzed in 24 patients with AIP. We evaluated the narrowing length of the main pancreatic duct (NR-MPD), multiple skipped MPD narrowing (SK-MPD), and side branches arising from the narrowed portion of the MPD (SB-MPD) using four MRCP datasets: 5 original images (MIP₅), 10 original images (MIP₁₀), all original images (full-MIP), and a combination of these three datasets (a-MIP). The images were scored using a 3- or 5-point scale. The scores of the four MRCP datasets were statistically analyzed, and the positive rate of each finding was compared between MRCP and ERCP.

RESULTS

The median scores for SB-MPD on MIP₅ and a-MIP were significantly higher than those on MIP₁₀ and full-MIP. In other words, partial MIP is superior to full-MIP for visualization of detailed structures. The positive rate for SB-MPD on full-MIP was significantly lower than that on ERCP, whereas the positive rate on MIP₅, MIP₁₀, and a-MIP was not significantly different from that on ERCP. Moreover, the positive rate for NR-MPD and SK-MPD on the MRCP images was significantly higher than that on the ERCP images.

CONCLUSION

Partial MIP is useful for evaluating the MPD and is comparable with ERCP for diagnosing AIP.

Clinical application of navigator-gated three-dimensional balanced turbo-field-echo magnetic resonance cholangiopancreatography at 3 T: prospective intraindividual comparison with 1.5 T

OBJECTIVE

To evaluate and compare the clinical utility of balanced turbo-field-echo (BTFE) magnetic resonance cholangiopancreatography (MRCP) sequences obtained at 3 and 1.5 T.

METHODS

We acquired three-dimensional (3D) BTFE MRCP scans with a navigator-gated technique at 3 T on a different day after 1.5 T in 39 consecutive patients. Two radiologists independently rated the image quality and visibility of anatomical structures (right and left hepatic duct, cystic duct, gallbladder, common bile duct, and main pancreatic duct) using a four-point scale. For quantitative analysis, the signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), and acquisition time were evaluated.

RESULTS

All visual scores tended to be higher for 1.5 T than 3 T images. There was a significant difference in the image quality and the depiction of the main pancreatic duct (p < 0.01). The image acquisition time was significantly shorter for 3 T than 1.5 T (199.3 ± 40.1 vs. 264.0 ± 86.5 s, p < 0.01). There was no significant difference in SNR and CNR.

CONCLUSIONS

3D-BTFE MRCP scans acquired at 3 T were of sufficient image quality with respect to the biliary tree. SNR and CNR were comparable on 3 and 1.5 T scans, although the acquisition time was significantly shorter with the 3 T scanner.

Usefulness of breath-hold inversion recovery-prepared T1-weighted two-dimensional gradient echo sequence for detection of hepatocellular carcinoma in Gd-EOB-DTPA-enhanced MR imaging

The aim is to evaluate the diagnostic performance and the added value of breath-hold inversion recovery-prepared T1-weighted two-dimensional gradient echo (IR-2D-GRE) sequence for detection of hepatocellular carcinoma (HCC) in patients with insufficient liver parenchymal enhancement during the hepatobiliary phase (HBP) of Gd-EOB-DTPA-enhanced magnetic resonance imaging (MRI). Seventeen patients with a quantitative liver-to-spleen contrast ratio of ≤1.5 on HBP images and 36 HCCs were included. Liver-to-lesion contrast ratios on HBP images obtained with IR-2D-GRE sequence were significantly higher than those with three-dimensional gradient echo sequence. The addition of IR-2D-GRE sequence during HBP of Gd-EOB-DTPA-enhanced MRI yielded higher diagnostic accuracy and improved sensitivity.

Pancreatic tumors imaging: An update

Currently, ultrasound (US), computed tomography (CT) and Magnetic Resonance imaging (MRI) represent the mainstay in the evaluation of pancreatic solid and cystic tumors affecting pancreas in 80-85% and 10-15% of the cases respectively. Integration of US, CT or MR imaging is essential for an accurate assessment of pancreatic parenchyma, ducts and adjacent soft tissues in order to detect and to stage the tumor, to differentiate solid from cystic lesions and to establish an appropriate treatment. The purpose of this review is to provide an overview of pancreatic tumors and the role of imaging in their diagnosis and management. In order to a prompt and accurate diagnosis and appropriate management of pancreatic lesions, it is crucial for radiologists to know the key findings of the most frequent tumors of the pancreas and the current role of imaging modalities. A multimodality approach is often helpful. If multidetector-row CT (MDCT) is the preferred initial imaging modality in patients with clinical suspicion for pancreatic cancer, multiparametric MRI provides essential information for the detection and characterization of a wide variety of pancreatic lesions and can be used as a problem-solving tool at diagnosis and during follow-up.

Non-contrast-enhanced MR portography and hepatic venography with time-spatial labeling inversion pulses: comparison at 1.5 Tesla and 3 Tesla

Background

A 3 Tesla (3 T) magnetic resonance (MR) scanner is a promising tool for upper abdominal MR angiography. However, there is no report focused on the image quality of non-contrast-enhanced MR portography and hepatic venography at 3 T.

Purpose

To compare and evaluate images of non-contrast-enhanced MR portography and hepatic venography with time-spatial labeling inversion pulses (Time-SLIP) at 1.5 Tesla (1.5 T) and 3 T.

Material and Methods

Twenty-five healthy volunteers were examined using respiratory-triggered three-dimensional balanced steady-state free-precession (bSSFP) with Time-SLIP. For portography, we used one tagging pulse (selective inversion recovery) and one non-selective inversion recovery pulse; for venography, two tagging pulses were used. The relative signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were quantified, and the quality of visualization was evaluated.

Results

The CNRs of the main portal vein, right portal vein, and left portal vein at 3 T were better than at 1.5 T. The image quality scores for the portal branches of segment 4, 5, and 8 were significantly higher at 3 T than at 1.5 T. The CNR of the right hepatic vein (RHV) at 3 T was significantly lower than at 1.5 T. The image quality scores of RHV and the middle hepatic vein were higher at 1.5 T than at 3 T. For RHV visualization, the difference was statistically significant.

Conclusion

Non-contrast-enhanced MR portography with Time-SLIP at 3 T significantly improved visualization of the peripheral branch in healthy volunteers compared with1.5 T. Non-contrast-enhanced MR hepatic venography at 1.5 T was better than at 3 T.

Non-contrast-enhanced MR portography and hepatic venography with time-spatial labeling inversion pulses: comparison of imaging with the short tau inversion recovery method and the chemical shift selective method

PURPOSE

To compare and evaluate images of non-contrast enhanced magnetic resonance (MR) portography and hepatic venography acquired with two different fat suppression methods, the chemical shift selective (CHESS) method and short tau inversion recovery (STIR) method.

MATERIALS AND METHODS

Twenty-two healthy volunteers were examined using respiratory-triggered three-dimensional true steady-state free-precession with two time-spatial labeling inversion pulses. The CHESS or STIR methods were used for fat suppression. The relative signal-to-noise ratio and contrast-to-noise ratio (CNR) were quantified, and the quality of visualization was scored.

RESULTS

Image acquisition was successfully conducted in all volunteers. The STIR method significantly improved the CNRs of MR portography and hepatic venography. The image quality scores of main portal vein and right portal vein were higher with the STIR method, but there were no significant differences. The image quality scores of right hepatic vein, middle hepatic vein, and left hepatic vein (LHV) were all higher, and the visualization of LHV was significantly better (p<0.05).

CONCLUSION

The STIR method contributes to further suppression of the background signal and improves visualization of the portal and hepatic veins. The results support using non-contrast-enhanced MR portography and hepatic venography in clinical practice.

Magnetic resonance evaluations of biliary malignancy and condition at high-risk for biliary malignancy: Current status

Tumors of the biliary tree are relatively rare; but their incidence is rising worldwide. There are several known risk factors for bile duct cancers, and these are seem to be associated with chronic inflammation of the biliary epithelium. Herein, 2 risk factors have been discussed, primary sclerosing cholangitis and reflux of pancreatic juice into the bile duct, as seen in such as an abnormal union of the pancreatic-biliary junction because magnetic resonance imaging (MRI) is used widely and effectively in the diagnosis of these diseases. When biliary disease is suspected, MRI can often help differentiate between benignity and malignancy, stage tumors, select surgical candidates and guide surgical planning. MRI has many advantages over other modalities. Therefore, MRI is a reliable noninvasive imaging tool for diagnosis and pre-surgical evaluation of bile duct tumors. Nowadays remarkable technical advances in magnetic resonance technology have expanded the clinical applications of MRI in case of biliary diseases. In this article, it is also discussed how recent developments in MRI contributes to the diagnosis of the bile duct cancer and the evaluation of patients with risk factors affecting bile duct cancer.

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.

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.

MRCP and 3D LAVA imaging of extrahepatic cholangiocarcinoma at 3 T MRI

Extrahepatic cholangiocarcinoma (CCA) is a primary bile duct malignant tumour with poor prognosis. Familiarity with their varied imaging characteristics can be helpful in developing a correct diagnosis and in optimal treatment planning, and thus contribute to a better prognosis. The purpose of this article is to illustrate the typical appearances of extrahepatic CCA on magnetic resonance cholangiopancreatography (MRCP) and three-dimensional (3D) LAVA (liver acquisition with volume acceleration) sequences at 3 T magnetic resonance imaging (MRI), and to discuss the superiority of the two techniques in the diagnosis of CCA.

3D flow-independent peripheral vessel wall imaging using T(2)-prepared phase-sensitive inversion-recovery steady-state free precession

PURPOSE

To develop a 3D flow-independent peripheral vessel wall imaging method using T(2)-prepared phase-sensitive inversion-recovery (T(2)PSIR) steady-state free precession (SSFP).

MATERIALS AND METHODS

A 3D T(2)-prepared and nonselective inversion-recovery SSFP sequence was designed to achieve flow-independent blood suppression for vessel wall imaging based on T(1) and T(2) properties of the vessel wall and blood. To maximize image contrast and reduce its dependence on the inversion time (TI), phase-sensitive reconstruction was used to restore the true signal difference between vessel wall and blood. The feasibility of this technique for peripheral artery wall imaging was tested in 13 healthy subjects. Image signal-to-noise ratio (SNR), wall/lumen contrast-to-noise ratio (CNR), and scan efficiency were compared between this technique and conventional 2D double inversion recovery - turbo spin echo (DIR-TSE) in eight subjects.

RESULTS

3D T(2)PSIR SSFP provided more efficient data acquisition (32 slices and 64 mm in 4 minutes, 7.5 seconds per slice) than 2D DIR-TSE (2-3 minutes per slice). SNR of the vessel wall and CNR between vessel wall and lumen were significantly increased as compared to those of DIR-TSE (P < 0.001). Vessel wall and lumen areas of the two techniques are strongly correlated (intraclass correlation coefficients: 0.975 and 0.937, respectively; P < 0.001 for both). The lumen area of T(2)PSIR SSFP is slightly larger than that of DIR-TSE (P = 0.008). The difference in vessel wall area between the two techniques is not statistically significant.

CONCLUSION

T(2)PSIR SSFP is a promising technique for peripheral vessel wall imaging. It provides excellent blood signal suppression and vessel wall/lumen contrast. It can cover a 3D volume efficiently and is flow- and TI-independent.

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.

Carotid arterial wall MRI at 3T using 3D variable-flip-angle turbo spin-echo (TSE) with flow-sensitive dephasing (FSD)

PURPOSE

To evaluate the effectiveness of flow-sensitive dephasing (FSD) magnetization preparation in improving blood signal suppression of three-dimensional (3D) turbo spin-echo (TSE) sequence (SPACE) for isotropic high-spatial-resolution carotid arterial wall imaging at 3T.

MATERIALS AND METHODS

The FSD-prepared SPACE sequence (FSD-SPACE) was implemented by adding two identical FSD gradient pulses right before and after the first refocusing 180 degrees -pulse of the SPACE sequence in all three orthogonal directions. Nine healthy volunteers were imaged at 3T with SPACE, FSD-SPACE, and multislice T2-weighted 2D TSE coupled with saturation band (SB-TSE). Apparent carotid wall-lumen contrast-to-noise ratio (aCNR(w-l)) and apparent lumen area (aLA) at the locations with residual-blood (rb) signal shown on SPACE images were compared between SPACE and FSD-SPACE. Carotid aCNR(w-l) and lumen (LA) and wall area (WA) measured from FSD-SPACE were compared to those measured from SB-TSE.

RESULTS

Plaque-mimicking flow artifacts identified in seven carotids on SPACE images were eliminated on FSD-SPACE images. The FSD preparation resulted in slightly reduced aCNR(w-l) (P = 0.025), but significantly improved aCNR between the wall and rb regions (P < 0.001) and larger aLA (P < 0.001). Compared to SB-TSE, FSD-SPACE offered comparable aCNR(w-l) with much higher spatial resolution, shorter imaging time, and larger artery coverage. The LA and WA measurements from the two techniques were in good agreement based on intraclasss correlation coefficient (0.988 and 0.949, respectively; P < 0.001) and Bland-Altman analyses.

CONCLUSION

FSD-SPACE is a time-efficient 3D imaging technique for carotid arterial wall with superior spatial resolution and blood signal suppression.

Abdominal magnetic resonance imaging at 3 T: oncological applications

The gain in signal-to-noise ratio at 3 T magnetic resonance (MR) imaging produces many benefits for abdominal imaging applications, including the capability to reduce acquisition times and/or improve spatial resolution for a variety of pulse sequences, the potential for broader application of parallel imaging techniques, and an increased sensitivity to gadolinium-based contrast media. These advances have the potential of improving the accuracy of MR imaging in the detection, staging, treatment planning, and follow-up of patients with abdominal tumors. At the same time, because certain high-field-strength-related drawbacks could not be compensated for, abdominal 3 T MR imaging should be clinically implemented with caution in some patients (eg, patients with massive ascites).

Nonenhanced free-breathing ECG-gated steady-state free precession 3D MR angiography of the renal arteries: comparison between 1.5 T and 3 T

OBJECTIVE

The purpose of our study was to compare the image quality of free-breathing ECG-gated nonenhanced steady-state free precession (SSFP) MR angiography of renal arteries at 1.5 T and 3 T.

SUBJECTS AND METHODS

Twenty volunteers (11 men, nine women; mean age, 23.2 +/- 2.3 years) without a history of renovascular disease participated in the study. Nonenhanced SSFP MR angiography was performed on all subjects at both 1.5 T and 3 T with a maximum interval of 2 weeks between the imaging sessions. The subjective image quality of axial and coronal maximum-intensity-projection reconstructions of four segments (1, abdominal aorta and ostium of renal artery; 2, main renal artery; 3, segmental branches outside renal parenchyma; 4, segmental branches inside renal parenchyma) was evaluated independently by two radiologists using a 4-point scale (4, excellent; 1, nondiagnostic). Relative signal-to-noise ratio, contrast-to-noise ratio, and maximum visible vessel length of the right and left renal arteries also were determined.

RESULTS

No significant difference in image quality at 1.5 T and 3 T was found for segments 1 and 2. The mean image quality for segments 3 and 4 was significantly greater at 3 T (3.88 +/- 0.32, 3.17 +/- 0.70) than at 1.5 T (3.32 +/- 0.73, 2.09 +/- 0.81) (p < 0.001). At 3 T, the maximal vessel length of the right (9.85 +/- 0.82 cm) and left (8.3 +/- 0.79 cm) renal arteries was significantly greater than at 1.5 T (8.94 +/- 1.38 cm and 7.58 +/- 1.18 cm, respectively).

CONCLUSION

Performing nonenhanced SSFP MR angiography at 3 T significantly improves visualization of peripheral renal arterial segments in healthy subjects as compared to 1.5 T.

Biliary tract depiction in living potential liver donors: intraindividual comparison of MR cholangiography at 3.0 and 1.5 T

PURPOSE

To intraindividually compare the accuracy of magnetic resonance (MR) cholangiography at 3.0 and 1.5 T for depicting biliary anatomy with intraoperative cholangiography as the reference standard and to compare the image quality for biliary tract visualization at these two field strengths.

MATERIALS AND METHODS

After obtaining institutional review board approval and informed consent, 52 living potential liver donors underwent MR cholangiography at both 1.5 and 3.0 T. The protocol included projectional single-section rapid acquisition with relaxation enhancement (RARE) and respiratory-triggered three-dimensional (3D) fast spin-echo (SE) T2-weighted sequences. Two readers independently analyzed images, scoring the visualization of all first- and second-order biliary branches on a four-point scale and determining the number of visible third-order branches.

RESULTS

MR cholangiography at 3.0 T correctly depicted biliary anatomy in 90.4% of subjects on combined analysis of both sequences by both readers, in 88.5% with projectional RARE images for both readers, and in 84.6% and 88.5% with 3D fast SE images for readers 1 and 2, respectively. MR cholangiography at 1.5 T showed 86.5% and 84.6% accuracy on combined analysis for readers 1 and 2, respectively; 78.8% and 75.0% accuracy on projectional RARE images for readers 1 and 2, respectively; and 84.6% and 86.5% accuracy with 3D fast SE images for readers 1 and 2, respectively. With the projectional RARE sequence, 3.0-T MR cholangiography demonstrated significantly higher mean visualization scores for second-order branches (reader 1: 2.29 vs 1.78, P = .01; reader 2: 2.52 vs 2.10, P < .01) and mean numbers of visible third-order branches (reader 1: 5.53 vs 4.21, P < .01; reader 2: 5.91 vs 3.74, P < .01) than did 1.5-T MR cholangiography.

CONCLUSION

Compared with 1.5-T MR cholangiography, 3.0-T MR cholangiography did not significantly increase accuracy for identification of biliary anatomy. Projectional RARE images at 3.0 T enabled better visualization of second- and third-order branches than did those at 1.5 T.

Three-dimensional T2-weighted MRI of the human femoral arterial vessel wall at 3.0 Tesla

OBJECTIVES

To evaluate the potential use of a novel 3D turbo spin-echo (TSE) T2-weighted (T2w) technique for assessing the vessel wall in the superficial femoral artery at 3.0 T.

BACKGROUND

Magnetic resonance imaging can be used for the noninvasive assessment of atherosclerotic plaque burden in the peripheral circulation. Although black-blood 2D TSE techniques have been used for femoral arterial wall imaging, these techniques require prolonged imaging time to cover a large field of view required to cover the leg. Recently, variable-flip-angle 3D TSE T2w (SPACE) has been introduced as a fast vessel wall imaging technique with submillimeter spatial resolution. A systematic investigation of the application of this technique to femoral arterial wall imaging has yet to be performed.

METHODS

Fifteen healthy volunteers and 3 patients with peripheral arterial disease (PAD) underwent 3D SPACE imaging of the superficial femoral artery at 3.0 T, with the conventional 2D TSE T2w imaging as a reference. Muscle-lumen contrast to noise ratio (CNR) and wall/lumen volumes (WV, LV) were measured at the matched locations on the 3D and 2D image sets. Statistical comparison on a per-subject basis was conducted to determine the difference and agreement between 3D SPACE and the 2D TSE techniques.

RESULTS

The 3D SPACE data sets enabled vessel visualization from arbitrary orientation through multiplanar reformation technique. Muscle-lumen CNR was significantly higher with 3D SPACE than with the 2D TSE (3.12 +/- 0.84 vs. 2.17 +/- 0.34, P < 0.01). This trend was confirmed when CNR efficiency (CNR(eff)) values were further compared. A similar trend was observed in PAD patients (SPACE vs. 2D TSE T2w: CNR 2.35 +/- 0.13 vs. 1.77 +/- 0.25; CNR(eff) 15.35 +/- 0.61 vs. 3.59 +/- 2.62. all P < 0.05). Measurements of WV and LV from the 3D and 2D techniques were highly correlated in volunteers and PAD patients (volunteers, WV: linear regression r2 = 0.98, LV: r2 = 0.98, P < 0.001 for both; patients, WV: linear regression r2 = 0.96, LV: r2 = 0.94, P < 0.001 for both).

CONCLUSION

We established the feasibility of using the 3D SPACE technique for vessel wall imaging in the superficial femoral artery at 3.0T. High, isotropic-resolution SPACE images, with the aid of multiplanar reformation, enable superior vessel wall visualization. Superior blood signal suppression comparable to vessel wall morphologic measurements, and superior time efficiency compared to conventional 2D TSE imaging indicate the great potential of the SPACE method as a noninvasive imaging technique for the assessment of atherosclerotic plaque burden in PAD patients.

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

OBJECTIVES

To prospectively evaluate the image quality and diagnostic accuracy of magnetic resonance cholangiopancreatography (MRCP) at 3.0 T compared with that at 1.5 T used for patients.

MATERIALS AND METHODS

This study was approved by our institutional review board, and informed consent was obtained from all patients. Three-dimensional MRCP with both a 1.5-T system and a 3.0-T system was administered to 33 consecutive patients suspected of having biliary and/or pancreatic diseases. For 3-dimensional MRCP imaging, a respiratory-triggered Fast Recovery Fast Spin Echo sequence with the parallel imaging technique was used for both systems. The spatial resolution at 1.5 T was matched to that at 3.0 T, and matrix size was 512 x 160, field of view (FOV) 36 x 36 cm, slice thickness 2 mm, and the number of slices ranged from 44 to 54. Repetition time varied according to the patients' respiratory cycles, which ranged from 3000 milliseconds to 6000 milliseconds, and effective echo time, ranging from 391 milliseconds to 482 milliseconds, was automatically determined by the systems. Contrast of imaging of the common bile duct versus that of the periductal tissue was quantitatively evaluated. The image quality for homogeneity of signal intensity, image noise, susceptibility artifacts, and overall imaging quality and diagnostic accuracy for stenoses of bile and main pancreatic ducts and for pancreatic cystic lesions were qualitatively evaluated. The results for 1.5- and 3.0-T were then compared statistically, by using the paired t test for quantitative evaluation of contrast between the common bile duct and the periductal tissue, the Wilcoxon signed rank test for visual evaluation of the image quality, and the McNemar chi2 test for evaluation of sensitivity and specificity for diagnostic purposes. A P value of less than 0.05 was considered to indicate a statistically significant difference.

RESULTS

Contrast of the common bile duct versus that of the periductal tissue at 3.0 T was superior to that at 1.5 T (P < 0.001). In the visual evaluation, image quality at 3.0 T was superior to that at 1.5 T for evaluation of image noise (P < 0.001), overall image quality (P < 0.001), and delineation of intrahepatic bile ducts (P < 0.01) and the main pancreatic duct (P < 0.05), whereas there were no significant differences in homogeneity of signal intensity and in susceptibility artifacts. The diagnostic accuracy for 3.0 T was approximately equivalent to that for 1.5 T.

CONCLUSION

Our results for patients with biliary and pancreatic diseases demonstrate a marked improvement in contrast of the common bile duct versus that of the periductal tissue and image quality including image noise at 3.0 T compared by 1.5 T when identical spatial resolution configuration were used. The results suggest that 3.0 T may allow higher spatial resolution and offer promise for improved diagnosis in MRCP, although further investigations using optimize scan parameters will be needed before its full potential can be achieved.

Comparison of dynamic MRI at 3.0 T and MDCT of pancreatobiliary disease: evaluation with source, MPR, CPR, and MIP images for image quality and hepatic arterial and portal venous vessel conspicuity

PURPOSE

To compare contrast material-enhanced three-dimensional (3D) magnetic resonance imaging (MRI) at 3.0T and multidetector row computed tomography (MDCT) in the same patient with regard to image quality of pancreatobiliary disease and hepatic vascular conspicuity.

MATERIALS AND METHODS

This study enrolled 32 patients with pancreatobiliary disease who underwent both gadolinium-enhanced 3D dynamic MRI and multiphasic CT using 16-MDCT. Data analysis of image quality was performed by two radiologists based on source images, multiplanar reconstruction (MPR), curved planar reconstruction (CPR), and maximum intensity projection (MIP) reconstruction. Determination of image quality was based on a 4-point image quality rating scale.

RESULTS

The overall image quality of the MRI axial images was superior to that of the axial MDCT images. The MRI protocol yielded an average score of 3.8 points versus 3.5 for the CT imaging. No significant difference was found between 3.0T MRI and MDCT images in MPR or CPR image quality. Image quality for visualization of the distal intrahepatic segmental arteries was significantly improved using MDCT imaging. No significant difference was found between the MDCT and 3.0T MR in portal vein branch image quality.

CONCLUSION

High-resolution dynamic contrast-enhanced MR imaging at 3.0T is a comprehensive technique which provides high image quality in pancreatobiliary disease.

3.0-T MR imaging of the abdomen: comparison with 1.5 T

Three-tesla magnetic resonance (MR) imaging offers substantially higher signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) than 1.5-T MR imaging does, which can be used to improve image resolution and shorten imaging time. Because of these increases in SNR and CNR, as well as changes in T1 and T2 relaxation times, an increase in magnetic susceptibility, and an increase in chemical shift effect, many abdominal applications can benefit from 3.0-T imaging. Increased CNR obtained with a gadolinium-based contrast agent improves lesion conspicuity, requires less intravenous contrast material, and improves MR angiography by increasing spatial and temporal resolution. Increased SNR improves fluid conspicuity and resolution for applications such as MR cholangiopancreatography. Increased chemical shift effect also improves spectral resolution for MR spectroscopy. Several potential problems remain for abdominal imaging at 3.0 T. Limitations on energy deposition may require compromises in pulse sequence timing and flip angles. These compromises result in prolonged imaging time and altered image contrast. Magnetic susceptibility and chemical shift artifacts are worsened, but they may be counteracted by shortening echo time, performing parallel imaging, and increasing bandwidth. Radiofrequency field inhomogeneity is also a major concern in imaging larger fields of view and often leads to standing wave effects and large local variations in signal intensity. Many issues related to MR device compatibility and safety have yet to be addressed at 3.0 T. A 3.0-T MR imaging system has a higher initial cost and a higher cost of upkeep than a 1.5-T system does.

High spatial resolution 3D MR cholangiography with high sampling efficiency technique (SPACE): comparison of 3T vs. 1.5T

PURPOSE

The aim of this study was to evaluate image quality of 3D MR cholangiography (MRC) using high sampling efficiency technique (SPACE) at 3T compared with 1.5T.

METHODS AND MATERIALS

An IRB approved prospective study was performed with 17 healthy volunteers using both 3 and 1.5T MR scanners. MRC images were obtained with free-breathing navigator-triggered 3D T2-weighted turbo spin-echo sequence with SPACE (TR, >2700ms; TE, 780ms at 3T and 801ms at 1.5T; echo-train length, 121; voxel size, 1.1mmx1.0mmx0.84mm). The common bile duct (CBD) to liver contrast-to-noise ratios (CNRs) were compared between 3 and 1.5T. A five-point scale was used to compare overall image quality and visualization of the third branches of bile duct (B2, B6, and B8). The depiction of cystic duct insertion and the highest order of bile duct visible were also compared. The results were compared using the Wilcoxon signed-ranks test.

RESULTS

CNR between the CBD and liver was significantly higher at 3T than 1.5T (p=0.0006). MRC at 3T showed a significantly higher overall image quality (p=0.0215) and clearer visualization of B2 (p=0.0183) and B6 (p=0.0106) than at 1.5T. In all analyses of duct visibility, 3T showed higher scores than 1.5T.

CONCLUSION

3T MRC using SPACE offered better image quality than 1.5T. SPACE technique facilitated high-resolution 3D MRC with excellent image quality at 3T.