Retrospective validation of a new diagnostic criterion for hepatocellular carcinoma on gadoxetic acid-enhanced MRI: can hypointensity on the hepatobiliary phase be used as an alternative to washout with the aid of ancillary features?

OBJECTIVES: To validate new diagnostic criteria for hepatocellular carcinoma (HCC) on gadoxetic acid-enhanced MR imaging (Gd-EOB-MRI) using hypointensity on the hepatobiliary phase (HBP) as an alternative to washout in combination with ancillary features. METHODS: This retrospective study included 288 patients at high risk for HCC with 387 nodules (HCCs, n=292; non-HCCs, n=95) showing arterial phase hyper-enhancement (APHE) ≥1 cm on Gd-EOB-MRI. Imaging diagnoses of HCCs were made using different criteria: APHE plus hypointensity on the portal venous phase (PVP) (criterion 1), APHE plus hypointensity on the PVP and/or transitional phase (TP) (criterion 2), APHE plus hypointensity on the PVP and/or TP and/or HBP (criterion 3), and criterion 3 plus non-LR-1/2/M according to the Liver Imaging Reporting and Data System (LI-RADS) v2017 considering ancillary features (criterion 4). Sensitivities and specificities of those criteria were compared using McNemar's test. RESULTS: Among diagnostic criteria for HCCs, criteria 3 and 4 showed significantly higher sensitivities (93.8% and 92.5%, respectively) than criteria 1 and 2 (70.9% and 86.6%, respectively) (p values <0.001). The specificity of criterion 4 (87.4%) was shown to be significantly higher than that of criterion 3 (48.4%, p<0.001), albeit comparable to criterion 2 (86.3%, p>0.999) and significantly lower than criterion 1 (97.9%, p=0.002). CONCLUSIONS: In the non-invasive diagnosis of HCCs on Gd-EOB-MRI, HBP hypointensity may be used as an alternative to washout enabling a highly sensitive diagnosis with little loss in specificity if it is used after excluding nodules considered to be benignities or non-HCC malignancies based on characteristic imaging features. KEY POINTS: • Gd-EOB-MRI enhancement and ancillary features can be used to diagnose HCC. • Exclusion of LR-1/2/M improves specificity when HBP hypointensity is used.

Contrast-Enhanced Ultrasound Using Perfluorobutane-Containing Microbubbles in the Assessment of Liver Allograft Damage: An Exploratory Prospective Study.

This prospective study investigated the usefulness of contrast (perfluorobutane-containing microbubbles)-enhanced ultrasound in the non-invasive assessment of liver allograft damage. Forty-one liver recipients underwent contrast-enhanced ultrasound followed by a liver biopsy. The hepatic filling rate (time between the arrival of contrast agent in the right hepatic artery and the maximum intensity of hepatic parenchyma) and parenchymal intensity difference before and after instantaneous high-power emission in the Kupffer phase were measured. Patients with allograft damage had higher hepatic filling rates and lower parenchymal intensity differences than those without damage (42.0 ± 16.9 vs. 30.5 ± 7.7 s, p = 0.005; 6.1 ± 7.4 vs. 16.6 ± 16.1 dB, p = 0.047, respectively). In the diagnosis of liver allograft damage, hepatic filling rate and parenchymal intensity difference had sensitivities of 61.5% and 90.9% and specificities of 92.6% and 63.6% using cutoffs of >38.5 s and ≤10.3 dB, respectively. In conclusion, contrast-enhanced ultrasound may be a promising tool in the detection of liver allograft damage.

Assessment of Malignant Potential in Intraductal Papillary Mucinous Neoplasms of the Pancreas: Comparison between Multidetector CT and MR Imaging with MR Cholangiopancreatography.

PURPOSE: To compare the diagnostic performance of multidetector computed tomography (CT) and magnetic resonance (MR) imaging with MR cholangiopancreatography (MRCP) in identifying the malignant potential of pancreatic intraductal papillary neoplasms (IPMNs) and evaluate their intermodality agreement. MATERIALS AND METHODS: Institutional review board approval was obtained, and the requirement for informed consent was waived for this retrospective study. In 129 patients with pathologically proved pancreatic IPMNs, three reviewers independently evaluated their preoperative CT and MR imaging with MRCP findings. Intermodality agreement between multidetector CT and MR imaging with MRCP, as well as interobserver agreement of each imaging modality, for depicting high-risk stigmata and worrisome features were assessed. Diagnostic values of other signs of overt malignancy, including the presence of a parenchymal mass and local-regional extension, were analyzed. Diagnostic performance and intermodality agreement were assessed by using receiver operating characteristics (ROC) curve analysis and weighted κ statistics. RESULTS: Overall, multidetector CT and MR imaging with MRCP were similar in their ability to depict signs suspicious or indicative of malignancy in patients with IPMN (area under the ROC curve [AUC] = 0.82 for both), with good intermodality agreement (κ = 0.75) and moderate interobserver agreement (κ = 0.47-0.59) when high-grade dysplasia was used as the cutoff for malignancy. When parenchymal masses and local-regional extensions were also considered as overt signs of malignancy, the ability to identify invasive IPMNs significantly increased (AUC = 0.87 for CT and AUC = 0.88 for MR imaging), with high sensitivity (94.3%), while maintaining specificity (69.1%). CONCLUSION: The diagnostic performance of multidetector CT and MR imaging with MRCP for identifying the malignant potential of pancreatic IPMNs was similar and showed good intermodality agreement, suggesting that follow-up with either modality may be used.

Added Value of Integrated Whole-Body PET/MRI for Evaluation of Colorectal Cancer: Comparison With Contrast-Enhanced MDCT.

OBJECTIVE: The purpose of this study was to evaluate the added clinical value of PET/MRI compared with conventional contrast-enhanced MDCT (CECT) alone in the evaluation of patients with colorectal cancer. MATERIALS AND METHODS: The study population comprised 51 patients with colorectal cancer who underwent (18)F-FDG PET/MRI and CECT within a 90-day interval between October 2012 and August 2013. Two reviewers in consensus evaluated whether PET/MRI added value to CECT for lesion detection and characterization and assessed whether changes in treatment strategies were made. The malignancy probability of each lesion was assessed on a 5-point scale. ROC analyses were performed with histopathologic findings, imaging, and clinical follow-up as the reference standards. Two reviewers evaluated the presence or absence of pulmonary metastatic nodules on PET/MR images that had been detected on chest CT scans. RESULTS: PET/MRI added value to CECT for 14 of 51 patients (27.5%) in terms of better characterization (12/51 [23.5%]) and additional detection (2/51 [3.9%]) of extracolonic lesions. The additional information from PET/MRI led to a change in treatment strategy for 11 of 51 (21.6%) patients. ROC analyses showed that PET/MRI was significantly superior to CT in depicting colorectal cancer (p < 0.05). The rate of detection of pulmonary metastatic nodules with PET/MRI was 52.9% (9/17). CONCLUSION: Integrated whole-body PET/MRI added value to CECT in the detection of metastatic lesions and characterization of indeterminate lesions, albeit with limited performance for small pulmonary metastatic nodules. The results suggest that PET/MRI may aid in the selection of more appropriate treatment strategies for patients with colorectal cancer.

Noninvasive diagnosis of hepatocellular carcinoma on gadoxetic acid-enhanced MRI: can hypointensity on the hepatobiliary phase be used as an alternative to washout?

OBJECTIVES: To determine which dynamic phase(s) of gadoxetic acid-enhanced MRI is most appropriate to assess "washout" in the noninvasive diagnosis of hepatocellular carcinoma (HCC) based on hemodynamic pattern. METHODS: In this retrospective cohort study, 288 consecutive patients with chronic liver disease presented with 387 arterially enhancing nodules (292 HCCs, 95 non-HCCs) (≥1 cm) on gadoxetic acid-enhanced MRI. All HCCs were confirmed by histopathology or by their typical enhancement pattern on dynamic liver CT. MR imaging diagnosis of HCC was made using criteria of arterial enhancement and hypointensity relative to the surrounding parenchyma (1) on the portal-venous phase (PVP), (2) on the PVP and/or transitional phase (TP), or (3) on the PVP and/or TP, and/or hepatobiliary phase (HBP). RESULTS: For the noninvasive diagnosis of HCC, criterion 1 provided significantly higher specificity (97.9%; 95% confidence interval, 92.6 - 99.7%) than criteria 2 (86.3%; 77.7 - 92.5%), or 3 (48.4%; 38.0 - 58.9%). Conversely, higher sensitivity was obtained with criterion 3 (93.8%; 90.4 - 96.3%) than with criterion 2 (86.6%; 82.2 - 90.3%) or 1 (70.9%; 65.3 - 76.0%). CONCLUSIONS: To make a sufficiently specific diagnosis of HCC using gadoxetic acid-enhanced MRI based on typical enhancement features, washout should be determined on the PVP alone rather than combined with hypointensity on the TP or HBP. KEY POINTS: • Gadoxetic acid-enhanced MRI enhancement features can be used to diagnose HCC. • Washout should be determined on the PVP alone for high specificity. • Hypointensity on the TP or HBP increases sensitivity but lowers specificity.