Hiroyuki Morisaka

Detection of Pancreatic Carcinoma and Liver Metastases with Gadoxetic Acid–enhanced MR Imaging: Comparison with Contrast-enhanced Multi–Detector Row CT

PURPOSE To intraindividually compare gadoxetic acid-enhanced magnetic resonance (MR) imaging with contrast material-enhanced multi-detector row computed tomography (CT) in detection of pancreatic carcinoma and liver metastases. MATERIALS AND METHODS The ethics committee approved this retrospective study with waiver of informed consent. This study included 100 patients (53 men, 47 women; mean age, 67.8 years) consisting of 54 patients with pathologically confirmed pancreatic carcinoma (mean size, 33 mm) and 46 without a pancreatic lesion. Sixty-two liver metastases (mean size, 10 mm) in 15 patients with pancreatic carcinoma were diagnosed at pathologic examination or multimodality assessment. Three readers blinded to the final diagnosis interpreted all MR (precontrast T1- and T2-weighted and gadoxetic acid-enhanced dynamic and hepatocyte phase MR images) and tetraphasic dynamic contrast-enhanced CT images and graded the presence (or absence) of pancreatic carcinoma and liver metastasis on patient-by-patient and lesion-by-lesion bases. Receiver operating characteristic analysis, McNemar test, and Fisher test were performed to compare the diagnostic performance of CT and MR imaging. RESULTS No significant differences were observed between CT and MR images in depiction of pancreatic carcinoma. However, MR imaging had greater sensitivity in depicting liver metastasis than did CT for two of the three readers in the MR imaging-versus-CT analysis (85% vs 69%, P = .046) and for all three readers in the lesion-by-lesion analysis (92%-94% vs 74%-76%, P = .030-.044). CONCLUSION Gadoxetic acid-enhanced MR imaging was equivalent to dynamic contrast-enhanced CT in depicting pancreatic carcinoma and had better sensitivity for depicting liver metastases, suggesting the usefulness of gadoxetic acid-enhanced MR imaging for evaluation of patients with pancreatic carcinoma.

Diagnosis of Pathologically Early HCC with EOB-MRI: Experiences and Current Consensus.

Objective: After much debate, the International Consensus Group for Hepatocellular Neoplasia (ICGHN) has recently arrived at a conclusion regarding the pathological criteria for early hepatocellular carcinoma (HCC). They have stated that stromal invasion should be recognized as the most important pathological finding for precisely diagnosing and differentiating early HCC from dysplastic nodules (DN). Methods: We conducted a review of the imaging findings from multi-imaging modalities of early HCC cases diagnosed according to the pathological criteria of the ICGHN. The multi-imaging modalities included gadoxetic acid (Gd-EOB-DTPA) enhanced magnetic resonance imaging (MRI), abbreviated as EOB-MRI, contrast-enhanced CT (CE-CT), CT during arterioportography (CTAP), and CT during hepatic arteriography (CTHA). It has been shown that EOB-MRI is the only imaging modality that has sufficient resolution for the detection and classification of early HCC. Results: The most significant imaging feature for diagnosing early HCC was hypointensity on hepatobiliary-phase (HP) images of EOB-MRI; all of the cases of early HCC that were detected on HP images of EOB-MRI showed hypointensity, while all of the images of DN showed isointensity or hyperintensity compared with the liver parenchyma. The results of the diagnostic performance analysis showed that EOB-MRI had excellent sensitivity (97%) for detecting early HCC and outstanding specificity (100%) for distinguishing early HCC from DN. Conclusions: Considering the results from imaging-pathologic correlations and follow-up studies indicating that many early-stage hepatocellular nodules showing hypointensity on HP images of EOB-MRI tend to develop hypervascularization during a relatively short follow-up period, it is beginning to be accepted that such nodules may be treated as early HCC. However, hepatologists and radiologists should also recognize that some cases of early HCC may show isointensity or hyperintensity on HP images of EOB-MRI, making it impossible to differentiate early HCC from DN, although the low prevalence of such nodules may be unlikely to affect the generally accepted follow-up protocols for cirrhotic patients. Our results and other recent reports have indicated that signal-intensity patterns on HP images of EOB-MRI for DN and early HCC directly correlate with the degree of expression of the organic anion transporting polypeptide (OATP) 1B3 in the nodules. Thus, the diagnostic performance of pathological analyses for early HCC cases may be dramatically improved, nearly up to that of EOB-MRI, by incorporating an OATP1B3 staining method.

Intravoxel incoherent motion imaging of the kidney: alterations in diffusion and perfusion in patients with renal dysfunction

PURPOSE To investigate the relationship between estimated glomerular filtration rate (eGFR) and parameters calculated using intravoxel incoherent motion (IVIM) imaging of the kidneys. MATERIALS AND METHODS We studied 365 patients, divided into 4 groups based on eGFR levels (mL/min/1.73m(2)): group 1, eGFR≥80(n=80); group 2, eGFR 60-80 (n=156); group 3, eGFR 30-60 (n=114); and group 4 ,eGFR<30 (n=15). IVIM imaging was used to acquire diffusion-weighted images at 12 b values. The diffusion coefficient of pure molecular diffusion (D), the diffusion coefficient of microcirculation or perfusion (D*), and perfusion fraction (f) were compared among the groups using group 1 as control. RESULTS In the renal cortex, D* values were significantly lower in groups 2, 3, and 4 than in group 1. The D value of renal cortex was significantly low in only group 3. In the renal medulla, the D* and D values were significantly lower only in groups 2 and 3, respectively. CONCLUSION As renal dysfunction progresses, renal perfusion might be reduced earlier and affected more than molecular diffusion in the renal cortex. These changes are effectively detected by IVIM MR imaging.

Comparison of the diagnostic accuracies of magnetic resonance elastography and transient elastography for hepatic fibrosis

OBJECTIVES To compare the diagnostic accuracies of magnetic resonance elastography (MRE) and transient elastography (TE) for hepatic fibrosis. MATERIALS AND METHODS This retrospective study was approved by the institutional review board and included 113 patients (mean age, 63.1±12.2years; 84 men and 29 women) with chronic liver disease who underwent liver biopsy or resection, histopathologic assessment (METAVIR scoring system), and TE within 6months of MRE. Diagnostic accuracies of MRE and TE were compared using receiver operating characteristic curve analysis. Appropriate cutoff values of the two methods determined by maximum positive and minimum negative likelihood ratios were used to calculate the positive and negative predictive values for discriminating significant fibrosis (≥F2) from F0-F1 or cirrhosis (F4) from F0-F3. RESULTS Mean (95% confidence interval) area under the receiver operating characteristic curve values of MRE for cirrhosis (F4) (0.97 [0.93-0.99] vs. 0.93 [0.87-0.96]; P=0.0308), clinically significant fibrosis (≥F2) (0.98 [0.94-0.99] vs. 0.87 [0.79-0.92]; P=0.0003), and any fibrosis (≥F1) (0.97 [0.92-0.99] vs. 0.87 [0.76-0.93]; P=0.0126) were significantly higher than those of TE. By using the cutoff values derived from the maximum positive likelihood ratio, the positive and negative predictive values for≥F2 were 98.8% and 83.9%, respectively, by MRE and 98.2% and 44.8%, respectively, by TE; and for F4, 97.0% and 86.3%, respectively, by MRE and 95.8% and 77.5%, respectively, by TE. CONCLUSION MRE has better diagnostic accuracy than TE for staging hepatic fibrosis.

Multi-organ perfusion CT in the abdomen using a 320-detector row CT scanner: Preliminary results of perfusion changes in the liver, spleen, and pancreas of cirrhotic patients

PURPOSE To utilize 320-detector row CT in perfusion CT of multiple abdominal organs and to compare the tissue perfusion between patients with and without liver cirrhosis. MATERIALS AND METHODS This study included 21 patients with cirrhosis and 20 without cirrhosis. The 320-detector row CT scanner enabled multi-organ perfusion CT without requiring the scanner table to be moved. Perfusion was calculated using the maximum slope model for the aorta, the portal vein, the right and left lobes of the liver, the head and body of the pancreas, the spleen, and the corpus and antrum of the stomach. Perfusion in each organ of patients with and without cirrhosis was compared. RESULTS Portal venous perfusion of the right and left lobes of the liver in patients with cirrhosis (117 and 100 mL min(-1)100mL(-1), respectively) was significantly less than that in patients without cirrhosis (213 and 174 mL min(-1)100mL(-1), respectively; p=0.0081 and 0.0294, respectively). Arterial perfusion of the spleen (111 mL min(-1)100mL(-1)) and the body of the pancreas (112 mL min(-1)100mL(-1)) in patients with cirrhosis was also significantly decreased compared with that in patients without cirrhosis (spleen, 162 mL min(-1)100mL(-1), p=0.0020; body of pancreas, 133 mL min(-1)100mL(-1), p=0.0405). CONCLUSION The results of the perfusion CT suggest that arterial perfusion of the spleen and the body of the pancreas, as well as portal perfusion of the liver, in cirrhotic patients was decreased compared with that in non-cirrhotic patients.

Intravoxel incoherent motion imaging of focal hepatic lesions

To compare diffusivity values between malignant and benign focal hepatic lesions using the intravoxel incoherent motion model.

MRI-based staging of hepatic fibrosis: Comparison of intravoxel incoherent motion diffusion-weighted imaging with magnetic resonance elastography.

To evaluate the use of intravoxel incoherent motion (IVIM) imaging for staging hepatic fibrosis, and compare its staging ability with that of magnetic resonance elastography (MRE).

Added Value of a Gadoxetic Acid-enhanced Hepatocyte-phase Image to the LI-RADS System for Diagnosing Hepatocellular Carcinoma

PURPOSE We investigated the added value of the hypointensity on hepatocyte-phase (HP) imaging of gadoxetic acid-enhanced MRI (EOB-MRI) in the 2014 version of the Liver Imaging Reporting and Data System (LI-RADS) for distinguishing hepatocellular carcinoma (HCC) from benign hepatic lesions in patients with chronic liver disease. METHODS We retrospectively evaluated targeted lesions (111 HCCs, 28 benign hepatic lesions) of 139 patients (101 men, 38 women; aged 18 to 89 years, mean age, 68 ± 11 years) with chronic liver disease. EOB-MRI and dynamic contrast-enhanced computed tomography (CECT) were performed within 3 months. Two abdominal radiologists independently reviewed 3 imaging datasets: (1) EOB-MRI without an HP image using the LI-RADS system (MR imaging without HP); (2) EOB-MRI with an HP image using a modified version of the LI-RADS system in which hypointensity on the HP image was used as an additional major criterion of malignancy (MR imaging with HP); and (3) dynamic contrast-enhanced computed tomography (CECT) images using the LI-RADS system. We evaluated intra- and inter-reader agreement with kappa statistics along with 95% confidence intervals and compared diagnostic sensitivity and specificity of the 3 imaging datasets with McNemars test. RESULTS The sensitivities of MR imaging were statistically higher with HP (Reader 1, 95% [107/111]; Reader 2, 95% [106/111]) than without HP (Reader 1, 84% [93/111], P = 0.002; Reader 2, 86% [96/111], P = 0.002). Specificity was comparably high between MR imaging with HP (Reader 1, 96% [27/28]; Reader 2, 96% [27/28]) and dynamic CECT (Reader 1, 100% [28/28], P = 0.317; Reader 2, 100% [28/28], P = 0.317) and MR imaging without HP (Reader 1, 96% [27/28], P = 1.00; Reader 2, 100% [28/28], P = 0.317). CONCLUSION The use of an HP image from EOB-MRI as an additional major criterion improved the sensitivity of LI-RADS to distinguish HCCs from benign hepatic lesions while retaining high specificity.

Hepatitis activity should be considered a confounder of liver stiffness measured with MR elastography

To evaluate the effect of hepatitis activity on liver stiffness measurements and the role of serum alanine aminotransferase (ALT) in liver fibrosis staging by MR elastography (MRE).

Presence of a hypovascular hepatic nodule showing hypointensity on hepatocyte-phase image is a risk factor for hypervascular hepatocellular carcinoma

To determine whether the presence of a hypovascular nodule in the liver showing hypointensity on hepatocyte‐phase of gadoxetic acid‐enhanced magnetic resonance imaging (EOB‐MRI) is a risk factor for hypervascular hepatocellular carcinoma (HCC) in patients with chronic liver disease.