Liver MRI at 3.0 tesla: comparison of image quality and lesion detectability between single-source conventional and dual-source parallel radiofrequency transmissions. J Comput Assist Tomogr. 2012;36:546-553. [PMID: 22992605 DOI: 10.1097/rct.0b013e318264e4a7]

3.0 Tesla magnetic resonance imaging: A new standard in liver imaging?

An ever-increasing number of 3.0 Tesla (T) magnets are installed worldwide. Moving from the standard of 1.5 T to higher field strength implies a number of potential advantage and drawbacks, requiring careful optimization of imaging protocols or implementation of novel hardware components. Clinical practice and literature review suggest that state-of-the-art 3.0 T is equivalent to 1.5 T in the assessment of focal liver lesions and diffuse liver disease. Therefore, further technical improvements are needed in order to fully exploit the potential of higher field strength.

The status of neuroendocrine tumor imaging: from darkness to light?

Diagnostic imaging plays a pivotal role in the diagnosis, staging, treatment selection and follow-up for neuroendocrine tumors. The available diagnostic strategies are morphologic imaging, including computed tomography, magnetic resonance imaging (MRI) and ultrasound techniques, and molecular imaging, including scintigraphy with (111)In-pentetreotide and positron emission tomography with (68)Ga-DOTA-peptides, (18)F-DOPA and (11)C-5-HTP. A combination of anatomic and functional techniques is routinely performed to optimize sensitivity and specificity. The introduction of diffusion-weighted MRI and dynamic contrast-enhanced techniques represents a promising advance in radiologic imaging, whereas new receptor-binding peptides, including somatostatin agonists and antagonists, represent the recent most favorable innovation in molecular imaging. Future development includes the short-term validation of these techniques, but in extension also a more comprehensive multilevel integration of biologic information pertaining to a specific tumor and patient, possibly encompassing genomic considerations, currently evolving as a new entity denoted 'precision medicine'. The ideal is a diagnostic sequence that captures the global status of an individual's tumor and encompasses a multidimensional characterization of tumor location, metabolic performance and target identification. To date, advances in imagery have focused on increasing resolution, discrimination and functional characterization. In the future, the fusion of imagery with the parallel analysis of biological and genomic information has the potential to considerably amplify diagnosis.

Noncontrast MRI with diffusion-weighted imaging as the sole imaging modality for detecting liver malignancy in patients with high risk for hepatocellular carcinoma

PURPOSE

To compare the diagnostic performance of the noncontrast MRI including DWI to the standard MRI for detecting hepatic malignancies in patients with chronic liver disease.

MATERIALS AND METHODS

We included 135 patients with 136 histologically-confirmed hepatocellular carcinomas (HCCs), 12 cholangiocarcinomas, and 34 benign lesions (≤ 2.0 cm), and 22 patients with cirrhosis but no focal liver lesion who underwent 3.0 T liver MRI. Noncontrast MRI set (T1- and T2-weighted images and DWI) and standard MRI set (gadoxetic acid-enhanced and noncontrast MRI) were analyzed independently by three observers to detect liver malignancies using receiver operating characteristic analysis.

RESULTS

The Az value of the noncontrast MRI (mean, 0.906) was not inferior to that of the combined MRI (mean, 0.924) for detecting malignancies by all observers (P>0.05). For each observer, no significant difference was found in the sensitivity and specificity between the two MRI sets for detecting liver malignancies and distinguishing them from benign lesions (P>0.05), whereas negative predictive value was higher with the combined MRI than with the noncontrast MRI (P=0.0001). When using pooled data, the sensitivity of the combined MRI (mean 94.8%) was higher than that of the noncontrast MRI (mean, 91.7%) (P =0.001), whereas specificity was equivalent (78.6% vs 77.5%).

CONCLUSION

Noncontrast MRI including DWI showed reasonable performance compared to the combined gadoxetic acid-enhanced and noncontrast MRI set for detecting HCC and cholangiocarcinoma and differentiating them from benign lesions in patients with chronic liver disease.

Unenhanced magnetic resonance portography using repetitive arterial or vein labeling method at 3.0-T

OBJECTIVE

The objective of this study was to determine whether unenhanced magnetic resonance (MR) angiography using repetitive arterial or vein labeling (RAVEL) is feasible to visualize effectively the intrahepatic portal vein (PV) at 3.0 T.

METHODS

Forty patients underwent liver MR imaging (MRI) with unenhanced MR portography using RAVEL. Two radiologists performed a consensus review of unenhanced MR portography and portal-phase MRI with regard to anatomic type of PV, vessel conspicuity, and image quality.

RESULTS

For determination of the anatomic type of PV, the 2 techniques were equivalent. There were tendencies toward increased conspicuity for right segmental PV and its branches with unenhanced MR portography and for left PV with conventional MRI, although significant differences were not found between MRIs (P > 0.05). Image quality for unenhanced MR portography was poor in 1, moderate in 8, and good in 31 patients.

CONCLUSIONS

Unenhanced MR portography using RAVEL at 3.0 T is feasible and provides effective visualization of intrahepatic PV.