Added value of subtraction imaging in detecting arterial enhancement in small (<3 cm) hepatic nodules on dynamic contrast-enhanced MRI in patients at high risk of hepatocellular carcinoma.

OBJECTIVES: To determine the importance of arterial enhancement in diagnosing small (<3 cm) hepatocellular carcinomas (HCCs) and to evaluate the added value of dynamic subtraction magnetic resonance imaging (MRI) in detecting arterial enhancement in small (<3 cm) hepatic nodules in high-risk patients. METHODS: Eighty-six patients with 135 pathologically confirmed small (<3 cm) hepatic nodules (104 HCCs, 31 benign nodules) underwent MRI before curative surgery. Arterial enhancement was determined by three methods: (1) visual assessment of the arterial phase alone, (2) visual comparison of the arterial phase with the unenhanced phase and (3) additional review of subtraction images. The diagnostic performance of each method was calculated and compared using generalised estimating equations analysis. RESULTS: Arterial enhancement demonstrated high positive predictive value (PPV) (96.5-98.9 %) and specificity (90.3-96.8 %), but low negative predictive value (NPV) (54.6-62.5 %) and intermediate sensitivity (76-79.8 %) for diagnosing small HCCs. Diagnostic performance was highest for subtraction imaging. There were significant differences among the three methods in sensitivity (P = 0.04), accuracy (P = 0.044), PPV (P < 0.001) and NPV (P = 0.024), but not in specificity (P = 0.167). CONCLUSION: The accurate detection of arterial enhancement in small hepatic nodules is important for diagnosing HCC and may be enhanced by subtraction imaging.

MRI features of hepatocellular carcinoma expressing progenitor cell markers.

BACKGROUND & AIMS: To determine whether magnetic resonance (MR) imaging features differ between hepatocellular carcinomas (HCCs) with and without expression of progenitor cell markers, such as cytokeratin (CK) 19 and epithelial cell adhesion molecule (EpCAM). METHODS: Sixty-three patients with 71 HCCs who underwent surgery after preoperative gadoxetic acid-enhanced MR imaging were evaluated. HCCs expressing progenitor cell markers were defined as showing CK19 or EpCAM expression. MR imaging features, including the fat component, arterial enhancement (global vs. peripheral), dynamic enhancement (washout vs. progressive or persistent), nodule-in-nodule appearance and MR gross morphology (expanding vs. non-expanding), were compared between HCCs with and without progenitor cell markers expression. Lesion-to-liver signal intensity ratio (SIR) and apparent diffusion coefficient values were compared using an independent samples t-test. Early recurrence rates were also compared. RESULTS: HCCs expressing progenitor cell markers were more commonly of the non-expanding type (P = 0.016), more frequently had a progressive or persistent dynamic enhancement pattern (P = 0.008) and less frequently demonstrated a nodule-in-nodule appearance (P = 0.009). HCCs expressing progenitor cell markers had significantly higher SIRs on diffusion-weighted images (DWIs) (b = 50 and 800, P < 0.001; b = 400, P = 0.001) and a significantly lower SIR on hepatobiliary phase images (P = 0.024). The early recurrence rate was significantly higher in patients with prior HCCs that expressed progenitor cell markers (P = 0.045). CONCLUSIONS: HCCs expressing progenitor cell markers can be characterized according to their non-expanding MR gross morphology, persistent or progressive dynamic enhancement patterns, higher SIRs on DWIs, lower SIRs on hepatobiliary phase images and less frequent nodule-in-nodule appearance.

Prediction of the histopathological grade of hepatocellular carcinoma using qualitative diffusion-weighted, dynamic, and hepatobiliary phase MRI.

OBJECTIVES: To investigate the effectiveness of qualitative diffusion-weighted imaging (DWI), subtraction of unenhanced from arterial phase images, and hepatobiliary phase (HBP) images in estimating the histopathological grade of hepatocellular carcinoma (HCC). METHODS: We retrospectively reviewed gadoxetic acid-enhanced magnetic resonance images of 175 patients with 201 surgically resected HCCs. The signal intensity and its relationship with histopathological grade were assessed for each sequence and a combination of sequences. RESULTS: There was a tendency towards higher grades in tumours showing restricted diffusion on DWI (P < 0.001) or arterial enhancement on subtraction imaging (P < 0.001), but not hepatocyte-defect on HBP images (P = 0.33). When lesions were divided into three groups based on combined findings on DWI and subtraction imaging, a linear trend was observed between group and grade (P < 0.001). The positive predictive value (PPV) of the combination of no restricted diffusion and no arterial enhancement in predicting well-differentiated HCC was 100%, higher than the PPV of individual findings on DWI (74%) or subtraction imaging (81%). CONCLUSIONS: DWI and subtraction imaging are helpful for predicting the histopathological grade of HCC, especially when the two sequences are considered together. KEY POINTS: • Predicting the histopathological grade of hepatocellular carcinoma (HCC) preoperatively is important. • Diffusion-weighted imaging (DWI) and subtraction imaging are recently developed MR techniques. • Retrospective study showed DWI and subtraction imaging helps predict HCC grades. • Management of patients with HCC becomes more appropriate.

Response evaluation in patients with colorectal liver metastases: RECIST version 1.1 versus modified CT criteria.

OBJECTIVE: Our retrospective study compared Response Evaluation Criteria in Solid Tumors (RECIST) version 1.1 with modified CT criteria to determine their respective utilities as a prognostic indicator. Using both sets of criteria, we compared treatment responses of patients with colorectal liver metastases treated with bevacizumab-containing chemotherapy with those of patients treated with chemotherapy alone. MATERIALS AND METHODS: Fifty-nine patients who received bevacizumab-containing chemotherapy (n=30, group 1) or chemotherapy alone (n=29, group 2) for the treatment of colorectal carcinoma underwent contrast-enhanced CT before treatment and 2 months after treatment. Two radiologists determined changes in tumor size and density between the pretreatment and 2-month follow-up CT images. RECIST 1.1 assesses responses on the basis of changes in tumor size, and the modified CT criteria assesses responses on the basis of changes in tumor density and size. Responses were correlated with time to tumor progression by log rank test. RESULTS: According to RECIST 1.1, nine of 30 patients (30%) in group 1 and 12 of 29 patients (41%) in group 2 were good responders. According to the modified CT criteria, 23 of 30 patients in group 1 (77%) and 23 of 29 patients in group 2 (79%) were good responders. As assessed by the modified CT criteria, good responders in both groups had significantly longer time to tumor progression than poor responders (p<0.05). As assessed by RECIST 1.1, good responders in group 1 had significantly longer time to tumor progression than poor responders (p=0.0154), but there was no difference in group 2. CONCLUSION: Evaluating treatment response with tumor size and density changes on CT was a better predictor of time to tumor progression than changes in tumor size alone in both groups.

Image Quality and Lesion Detectability of Lower-Dose Abdominopelvic CT Obtained Using Deep Learning Image Reconstruction.

OBJECTIVE: To evaluate the image quality and lesion detectability of lower-dose CT (LDCT) of the abdomen and pelvis obtained using a deep learning image reconstruction (DLIR) algorithm compared with those of standard-dose CT (SDCT) images. MATERIALS AND METHODS: This retrospective study included 123 patients (mean age ± standard deviation, 63 ± 11 years; male:female, 70:53) who underwent contrast-enhanced abdominopelvic LDCT between May and August 2020 and had prior SDCT obtained using the same CT scanner within a year. LDCT images were reconstructed with hybrid iterative reconstruction (h-IR) and DLIR at medium and high strengths (DLIR-M and DLIR-H), while SDCT images were reconstructed with h-IR. For quantitative image quality analysis, image noise, signal-to-noise ratio, and contrast-to-noise ratio were measured in the liver, muscle, and aorta. Among the three different LDCT reconstruction algorithms, the one showing the smallest difference in quantitative parameters from those of SDCT images was selected for qualitative image quality analysis and lesion detectability evaluation. For qualitative analysis, overall image quality, image noise, image sharpness, image texture, and lesion conspicuity were graded using a 5-point scale by two radiologists. Observer performance in focal liver lesion detection was evaluated by comparing the jackknife free-response receiver operating characteristic figures-of-merit (FOM). RESULTS: LDCT (35.1% dose reduction compared with SDCT) images obtained using DLIR-M showed similar quantitative measures to those of SDCT with h-IR images. All qualitative parameters of LDCT with DLIR-M images but image texture were similar to or significantly better than those of SDCT with h-IR images. The lesion detectability on LDCT with DLIR-M images was not significantly different from that of SDCT with h-IR images (reader-averaged FOM, 0.887 vs. 0.874, respectively; p = 0.581). CONCLUSION: Overall image quality and detectability of focal liver lesions is preserved in contrast-enhanced abdominopelvic LDCT obtained with DLIR-M relative to those in SDCT with h-IR.

Comparison of gadoxetic acid-enhanced dynamic imaging and diffusion-weighted imaging for the preoperative evaluation of colorectal liver metastases.

PURPOSE: To retrospectively compare the diagnostic accuracy for the detection of colorectal liver metastases between gadoxetic acid-enhanced MRI (EOB-MRI) and diffusion-weighted imaging (DWI) on 3.0 Tesla (T) system, and then to determine whether a combination of the two techniques may improve the diagnostic performance. MATERIALS AND METHODS: Forty-seven patients underwent MR imaging at 3.0T, including DWI (DWI set) and dynamic and hepatobiliary phase EOB-MRI (EOB set) for the preoperative evaluation of colorectal liver metastases. All suspicious metastases were confirmed by hepatic surgery. Two blinded readers independently reviewed three different image sets, which consisted of DWI set, EOB set, and combined set. The accuracy was assessed by the area (Az) under the alternative-free response receiver operating characteristic curve, and the sensitivity and positive predictive value (PPV) were calculated. RESULTS: We found a total of 78 confirmed colorectal liver metastases in 42 of 47 patients. Each reader noted higher diagnostic accuracy of combined set of EOB-MRI and DWI than DWI set and EOB set, without statistical significance. Regardless of the size of colorectal liver metastasis, each reader detected significantly more metastases on combined set than on DWI set, and PPV was significantly higher with DWI set than with EOB set or with combined set for one reader. CONCLUSION: EOB-MRI was more useful for the detection of colorectal liver metastases, while DWI was more useful for their characterization. The combination of EOB-MRI and DWI showed significantly higher accuracy and sensitivity for the preoperative detection of small colorectal liver metastases than DWI.

A Case Report of Cholangiocarcinoma Arising from a Biliary Adenofibroma: Radiologic Findings and Review of Literature.

Biliary adenofibromas are rare biliary epithelial tumors that are classified as benign. Nevertheless, some cases have been reported to show malignant transformations. The radiologic findings of biliary adenofibromas and their malignant transformation are not well-established because of their rarity. We present a case of a cholangiocarcinoma arising from a biliary adenofibroma assessed using ultrasonography, CT, and MRI. The differential diagnoses include other hepatic tumors.

Clinical implication of positive oral contrast computed tomography for the evaluation of postoperative leakage after gastrectomy for gastric cancer.

OBJECTIVE: To evaluate the clinical usefulness of positive oral contrast computed tomography (CT) for the detection of leakage and its relationship with the immediate postoperative outcome after gastrectomy for gastric cancer. METHODS: A total of 210 patients with a clinical suspicion of leakage after gastrectomy for gastric cancer underwent a positive oral contrast CT. Two radiologists retrospectively reviewed the CT images, recorded the presence of extraluminal contrast leakage, and graded the amount of leaked contrast. The rate of postoperative intervention treatment, the length of postoperative hospital stay, and mortality rates were correlated with the presence and grades of leakage. Matching accuracy between CT and other diagnostic studies in detection of leakage was also evaluated. RESULTS: There were 162 patients without extraluminal contrast leakage (77.1%), 13 with grade 1 leakage (6.2%), 19 with grade 2 (9.0%), and 16 with grade 3 (7.6%). Postoperative intervention rate, hospital stay, and mortality were significantly higher in patients with extraluminal contrast than those in patients without extraluminal contrast (P < 0.05). Postoperative hospital stays increased as the leakage grades increased (P = 0.0008). The matching accuracy between CT and other studies was 82.1% (n = 32/39). CONCLUSIONS: Positive oral contrast CT can be a reliable tool for diagnosing postoperative leakage that requires further intervention after gastrectomy in gastric cancer patients, and the immediate postoperative outcome may be related with the grade of leaked contrast on CT.

Diffuse Large B-Cell Lymphoma in the Portal Vein.

Tumor thrombus in the portal vein without any liver parenchymal abnormality is extremely rare. In the liver, the primary tumor most frequently presenting with intravascular tumor thrombi is hepatocellular carcinoma and lymphoma is rarely considered. Even though thrombosis occurs quite often in lymphoma, cases of tumor thrombus are rare and cases of tumor thrombus in the portal vein are even rarer. Only four cases of lymphoma with portal vein tumor thrombosis have been reported to date and all cases were the result of direct extensions of a dominant nodal or extra-nodal mass. To our knowledge, there has been no report on diffuse large B-cell lymphoma (DLBCL) presenting only within the lumen of the portal vein and not intravascular B-cell lymphoma. We present the first case of DLBCL presenting only within the lumen of the portal vein in an immunocompetent patient.

Effects of neoadjuvant combined chemotherapy and radiation therapy on the CT evaluation of resectability and staging in patients with pancreatic head cancer.

PURPOSE: To evaluate the effect of neoadjuvant combined chemotherapy and radiation therapy (CCRT) on preoperative accuracy of multidetector computed tomography (CT) for resectability and tumor staging in patients with pancreatic head cancer. MATERIALS AND METHODS: This retrospective study received institutional review board approval and was exempted from informed consent requirements. From May 2002 to March 2007, 38 patients with pancreatic head adenocarcinoma underwent multidetector CT before surgery. Of these, 12 patients received neoadjuvant CCRT. Imaging findings were evaluated for tumor resectability and tumor staging. Surgical and pathologic results were used as the reference standard. The accuracy of resectability and individual components of each T category were compared between the patients with neoadjuvant CCRT and without it by using the chi(2) test or Fisher exact test. A P of less than .05 was considered as significant. RESULTS: The accuracy in determining resectability was 83% (10 of 12) in patients who had received neoadjuvant CCRT and 81% (21 of 26) in patients who had not, without significant difference (P > .05). Of 32 patients who underwent pancreaticoduodenectomy, histopathologic tumor staging was reported for T1 (n = 2), T2 (n = 1), and T3 (n = 9) lesions in patents with neoadjuvant CCRT (n = 12), and for T3 in all patients without neoadjuvant CCRT (n = 20). T-staging accuracy was 67% (eight of 12) with neoadjuvant CCRT and 95% (19 of 20) without it, with a significant difference (P = .0185). CONCLUSION: Neoadjuvant CCRT reduces the accuracy of tumor restaging after treatment of pancreatic head cancer, but this effect is not so great as to affect the determination of resectability.

On the Design of a Novel Underactuated Robotic Finger Prosthesis for Partial Hand Amputation.

This paper presents a novel robotic finger prosthesis for partially amputated patients who have lost a thumb and index finger. The challenging issues were to design i) a three-degree-of-freedom (DOF) underactuated mechanism that mimics intact finger movements including motion profiles and self-adaptation for unknown constraints, ii) an attachment socket for everyday life that allows ease of donning and doffing, and comfortable wearability, and iii) a shape to pack the selected components including an actuator, linkages, and sensors into a limited space avoiding motion interference with other intact fingers and wrist. This paper reports our effort to solve the challenging issues. The proposed three-DOF prosthetic finger can generate 4.6N pinch force and 99.4°/s angular velocity at the MCP joints. For command signals, surface-electromyogram (sEMG) sensors were used. This enables users to operate the fingers with certain configuration and grasping force. The performance of the proposed design was verified through the box-and-block test and bottle opening test with a patient who has a partially amputated hand.

Dynamic Contrast-Enhanced Magnetic Resonance Imaging as a Surrogate Biomarker for Bevacizumab in Colorectal Cancer Liver Metastasis: A Single-Arm, Exploratory Trial.

PURPOSE: The purpose of this study is to investigate dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and plasma cytokines and angiogenic factors (CAFs) as pharmacodynamic and prognostic biomarkers of bevacizumab monotherapy in colorectal cancer with liver metastasis (CRCLM). MATERIALS AND METHODS: From July 2011 to March 2012, 28 patients with histologically confirmed CRCLM received bevacizumab monotherapy followed by combined FOLFOX therapy. The mean age of the patients was 57 years (range, 30 to 77 years). DCE-MRI (Ktransand IAUC60) was performed at baseline, first follow-up (3 days after bevacizumab monotherapy), and second follow-up (3 days after combined therapy). CAF levels (vascular endothelial growth factor [VEGF], placental growth factor [PlGF], and interleukin-8) were assessed on the same days. Progression-free survival (PFS) time distributions were summarized using the Kaplan-Meier method and compared using log-rank tests. RESULTS: The median PFS period was 11.2 months. Ktrans, IAUC60, VEGF, and PlGF values on the first follow-up day were significantly different compared with baseline values. No differences were observed on the second follow-up day. A > 40% decrease in Ktrans from baseline to first follow-up was associated with a longer PFS (hazard ratio, 0.349; 95% confidence interval, 0.133 to 0.912; p=0.032). Changes in CAFs did not show correlation with PFS time. CONCLUSION: DCE-MRI parameters and CAFs are pharmacodynamic biomarkers of bevacizumab for CRCLM. In our study, change in Ktrans at 3 days after bevacizumab monotherapy was a favorable prognostic factor; however, the value of CAFs as a prognostic biomarker was not found.

Characterization of incidental liver lesions: comparison of multidetector CT versus Gd-EOB-DTPA-enhanced MR imaging.

As a result of recent developments in imaging modalities and wide spread routine medical checkups and screening, more incidental liver lesions are found frequently on US these days. When incidental liver lesions are found on US, physicians have to make a decision whether to just follow up or to undergo additional imaging studies for lesion characterization. In order to choose the next appropriate imaging modality, the diagnostic accuracy of each imaging study needs to be considered. Therefore, we tried to compare the accuracy of contrast-enhanced multidetector CT (MDCT) and Gd-EOB-DTPA-enhanced MRI for characterization of incidental liver masses. We included 127 incidentally found focal liver lesions (94 benign and 33 malignant) from 80 patients (M∶F = 45∶35) without primary extrahepatic malignancy or chronic liver disease. Two radiologists independently reviewed Gd-EOB-DTPA-enhanced MRI and MDCT. The proportion of confident interpretations for differentiation of benign and malignant lesions and for the specific diagnosis of diseases were compared. The proportion of confident interpretations for the differentiation of benign and malignant lesions was significantly higher with EOB-MRI(94.5%-97.6%) than with MDCT (74.0%-92.9%). In terms of specific diagnosis, sensitivity and accuracy were significantly higher with EOB-MRI than with MDCT for the diagnosis of focal nodular hyperplasia (FNH) and focal eosinophilic infiltration. The diagnoses of the remaining diseases were comparable between EOB-MRI and MDCT. Hence, our results suggested that Gd-EOB-MRI may provide a higher proportion of confident interpretations than MDCT, especially for the diagnosis of incidentally found FNH and focal eosinophilic infiltration.

Perfusion parameters of dynamic contrast-enhanced magnetic resonance imaging in patients with rectal cancer: correlation with microvascular density and vascular endothelial growth factor expression.

OBJECTIVE: To determine whether quantitative perfusion parameters of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) correlate with immunohistochemical markers of angiogenesis in rectal cancer. MATERIALS AND METHODS: Preoperative DCE-MRI was performed in 63 patients with rectal adenocarcinoma. Transendothelial volume transfer (K(trans) ) and fractional volume of the extravascular-extracellular space (Ve) were measured by Interactive Data Language software in rectal cancer. After surgery, microvessel density (MVD) and vascular endothelial growth factor (VEGF) expression scores were determined using immunohistochemical staining of rectal cancer specimens. Perfusion parameters (K(trans) , Ve) of DCE-MRI in rectal cancer were found to be correlated with MVD and VEGF expression scores by Spearman's rank coefficient analysis. T stage and N stage (negative or positive) were correlated with perfusion parameters and MVD. RESULTS: Significant correlation was not found between any DCE-MRI perfusion parameters and MVD (rs = -0.056 and p = 0.662 for K(trans) ; rs = -0.103 and p = 0.416 for Ve), or between any DCE-MRI perfusion parameters and the VEGF expression score (rs = -0.042, p = 0.741 for K(trans) ; r = 0.086, p = 0.497 for Ve) in rectal cancer. TN stage showed no significant correlation with perfusion parameters or MVD (p > 0.05 for all). CONCLUSION: DCE-MRI perfusion parameters, K(trans) and Ve, correlated poorly with MVD and VEGF expression scores in rectal cancer, suggesting that these parameters do not simply denote static histological vascular properties.

Gadoxetate disodium-enhanced magnetic resonance imaging versus contrast-enhanced 18F-fluorodeoxyglucose positron emission tomography/computed tomography for the detection of colorectal liver metastases.

PURPOSE: : To compare the diagnostic accuracy of gadoxetate disodium-enhanced magnetic resonance imaging (EOB-MRI) on a 3-T system and integrated contrast-enhanced F-fluorodeoxyglucose positron emission tomography/computed tomography (CE-PET/CT) for the detection of hepatic metastases from colorectal cancers. MATERIALS AND METHODS: : The approval from the institutional review board was obtained, and the requirement for informed consent was waived. We retrospectively evaluated 135 metastases in 68 patients (37 men, 31 women; mean age: 68 years; age range: 37-82 years) who underwent both EOB-MRI and CE-PET/CT. A total of 103 metastases were confirmed during surgery and 32 were confirmed by imaging findings during follow-up. The images were independently reviewed by 2 observers. The diagnostic accuracies of EOB-MRI and CE-PET/CT were determined by calculating the areas under each reader-specific receiver operating characteristic curve (Az). Patient-based lesion sensitivity and specificity were compared using the McNemar test. RESULTS: : The mean area under the Az on EOB-MRI versus CE-PET/CT was 0.94 versus 0.81 for all lesions (P < 0.001), 0.92 versus 0.60 for lesions ≤1 cm in size (P < 0.001), and 0.88 versus 0.96 for lesions >1 cm (P = 0.098), respectively. The sensitivity, specificity, positive predictive values, and negative predictive value on a patient basis were 100%, 71%, 97%, and 100% for EOB-MRI and 93%, 71%, 97%, and 57% for CE-PET/CT, respectively. CONCLUSIONS: : EOB-MRI using a 3-T system is more accurate than CE-PET/CT, especially for the detection of small (≤1.0 cm) lesions. Patient-based analysis revealed that EOB-MRI has a higher sensitivity and negative predictive value than CE-PET/CT.