Combined Use of MR Fat Quantification and MR Elastography in Living Liver Donors: Can It Reduce the Need for Preoperative Liver Biopsy?

PURPOSE

To evaluate the diagnostic performance of magnetic resonance (MR) fat quantification and MR elastography for the assessment of hepatic steatosis and fibrosis in living liver donor candidates.

MATERIALS AND METHODS

This retrospective study was approved by the institutional review board, and the requirement of informed consent was waived. Donors who underwent MR fat quantification and MR elastography at 1.5 T, followed by liver biopsy, were chronologically grouped into test and validation groups. In the test group (n = 362), MR fat fraction and liver stiffness were compared among donors with normal parenchyma (n = 244), simple steatosis (n = 71), steatosis with inflammatory activity (n = 21), nonalcoholic steatohepatitis (n = 17), and fibrosis (n = 9). Diagnostic performance of the two techniques was assessed by using receiver operating characteristic curve analysis for the detection of substantial steatosis (macrovesicular fat ≥ 10%) or fibrosis (≥F1) and was tested in a validation group (n = 34).

RESULTS

In the test group, donors with steatosis showed significantly higher fat fraction than donors without steatosis (P < .0001), and donors with fibrosis and nonalcoholic steatohepatitis showed significantly higher liver stiffness values than donors without fibrosis (P < .0001). Areas under the curve were 0.93 (cutoff value > 5.8%) for MR fat quantification and 0.85 (cutoff value > 1.94 kPa) for MR elastography. By using those values, the combination of the two techniques could be used to detect substantial steatosis or fibrosis with 100% sensitivity (12 of 12 patients, 95% confidence interval: 73.4%, 100%) and 100% negative predictive value (15 of 15 patients, 95% confidence interval: 78.0%, 100%) in the validation group.

CONCLUSION

A combination of MR fat quantification and MR elastography can provide sufficient sensitivity to detect substantial steatosis or fibrosis (≥F1) in liver donor candidates.

CT findings suggesting anastomotic leak and predicting the recovery period following gastric surgery

OBJECTIVE

To assess diagnostic performance of routine CT for detecting anastomotic leak after gastric surgery, and analyse the relationship between recovery period and CT findings.

METHODS

We included 179 patients who underwent immediate CT and fluoroscopy after gastric surgery. Two reviewers retrospectively rated the possibility of leak on CT using a five-point scale focused on predefined CT findings. They also evaluated CT findings. Patients were categorised as: Group I, leak on fluoroscopy; Group II, possible leak on CT but negative on fluoroscopy; Group III, no leak. We analysed the relationship between recovery period and group.

RESULTS

Area under the curve for detecting leak on CT was 0.886 in R1 and 0.668 in R2 with moderate agreement (к = 0.482). Statistically common CT findings for leak included discontinuity, large amount of air-fluid and wall thickening at anastomosis site (p < 0.05). Discontinuity at anastomosis site and a large air-fluid collection were independently associated with leak (p < 0.05). The recovery period including hospitalisation and postoperative fasting period was longer in Group I than Group II or III (p < 0.05). Group II showed a longer recovery period than Group III (p < 0.05).

CONCLUSIONS

Postoperative routine CT was useful for predicting anastomotic leak using specific findings, and for predicting length of recovery period.

KEY POINTS

• Anastomotic leakage remains a significant clinical problem following gastric surgery. • Routine CT without oral contrast is useful for predicting anastomotic leaking. • Wall discontinuity at anastomosis sites was an independent predictor for leaking. • CT is also useful for predicting recovery period following gastric surgery.

Hepatocellular carcinoma: diagnostic performance of multidetector CT and MR imaging-a systematic review and meta-analysis

PURPOSE

To perform a systematic review and meta-analysis of the diagnostic performance of computed tomography (CT) and magnetic resonance (MR) imaging as noninvasive modalities for evaluating hepatocellular carcinoma (HCC) in patients with chronic liver disease.

MATERIALS AND METHODS

A search of the MEDLINE, EMBASE, and Cochrane Library databases was performed to identify studies providing per-patient or per-lesion diagnostic accuracies of multidetector CT and MR imaging for HCCs in patients with chronic liver disease. Studies published from January 2000 to December 2012 that used a reference standard based on histopathologic findings and/or findings at follow-up were included. Summary estimates of diagnostic accuracy were obtained by using a random-effects model with further exploration with meta-regression and subgroup analyses.

RESULTS

Forty studies (six on multidetector CT, 22 on MR imaging, and 12 on both CT and MR imaging) were included. The studies evaluated a total of 1135 patients with multidetector CT and 2489 patients with MR imaging. The overall per-patient sensitivity of MR imaging was 88% (95% confidence interval [CI]: 83%, 92%), with a specificity of 94% (95% CI: 85%, 98%). The overall per-lesion sensitivity of MR imaging was higher than that of multidetector CT when the paired data of the 11 available studies were pooled (80% vs 68%, P = .0023). Gadoxetic acid-enhanced MR imaging showed significantly higher per-lesion sensitivity than MR imaging performed with other contrast agents (87% vs 74%, P = .03). Per-lesion sensitivity was significantly lower for HCCs smaller than 1 cm than that for HCCs 1 cm or larger (P < .001 for CT, P = .02 for MR imaging) and for those in explanted livers (P = .04 for CT, P < .001 for MR imaging).

CONCLUSION

MR imaging showed higher per-lesion sensitivity than multidetector CT and should be the preferred imaging modality for the diagnosis of HCCs in patients with chronic liver disease.

Image-guided tumor ablation: standardization of terminology and reporting criteria--a 10-year update

Image-guided tumor ablation has become a well-established hallmark of local cancer therapy. The breadth of options available in this growing field increases the need for standardization of terminology and reporting criteria to facilitate effective communication of ideas and appropriate comparison among treatments that use different technologies, such as chemical (eg, ethanol or acetic acid) ablation, thermal therapies (eg, radiofrequency, laser, microwave, focused ultrasound, and cryoablation) and newer ablative modalities such as irreversible electroporation. This updated consensus document provides a framework that will facilitate the clearest communication among investigators regarding ablative technologies. An appropriate vehicle is proposed for reporting the various aspects of image-guided ablation therapy including classification of therapies, procedure terms, descriptors of imaging guidance, and terminology for imaging and pathologic findings. Methods are addressed for standardizing reporting of technique, follow-up, complications, and clinical results. As noted in the original document from 2003, adherence to the recommendations will improve the precision of communications in this field, leading to more accurate comparison of technologies and results, and ultimately to improved patient outcomes.

2014 KLCSG-NCC Korea Practice Guidelines for the management of hepatocellular carcinoma: HCC diagnostic algorithm

Hepatocellular carcinoma (HCC) is the fifth most commonly occurring cancer in Korea and typically has a poor prognosis with a 5-year survival rate of only 28.6%. Therefore, it is of paramount importance to achieve the earliest possible diagnosis of HCC and to recommend the most up-to-date optimal treatment strategy in order to increase the survival rate of patients who develop this disease. After the establishment of the Korean Liver Cancer Study Group (KLCSG) and the National Cancer Center (NCC), Korea jointly produced for the first time the Clinical Practice Guidelines for HCC in 2003, revised them in 2009, and published the newest revision of the guidelines in 2014, including changes in the diagnostic criteria of HCC and incorporating the most recent medical advances over the past 5 years. In this review, we will address the noninvasive diagnostic criteria and diagnostic algorithm of HCC included in the newly established KLCSG-NCC guidelines in 2014, and review the differences in the criteria for a diagnosis of HCC between the KLCSG-NCC guidelines and the most recent imaging guidelines endorsed by the European Organisation for Research and Treatment of Cancer (EORTC), the Liver Imaging Reporting and Data System (LI-RADS), the Organ Procurement and Transplantation Network (OPTN) system, the Asian Pacific Association for the Study of the Liver (APASL) and the Japan Society of Hepatology (JSH).

Non-hypervascular hypointense nodules ≥1 cm on the hepatobiliary phase of gadoxetic acid-enhanced magnetic resonance imaging in cirrhotic livers

OBJECTIVE

To determine the pathologic nature of non-hypervascular hypointense nodules (≥1 cm) on the hepatobiliary phase (HBP) of gadoxetic acid-enhanced magnetic resonance (MR) imaging and to describe the chronological changes of their imaging features on follow-up MR imaging.

PATIENTS AND METHODS

This retrospective study was approved by our Institutional Review Board and the requirement for informed consent was waived. 69 patients with 115 non-hypervascular HBP hypointense nodules (≥1 cm in diameter) in cirrhotic livers were enrolled. 67 nodules were histologically diagnosed (group 1) and 52 nodules were followed up with MR for at least 12 months (group 2); 4 nodules belonged to both groups. Two radiologists reviewed the initial and follow-up MR images to determine the size and signal intensities on unenhanced T1- and T2-weighted images, dynamic phases and HBP images in consensus. In addition, two pathologists reviewed the histologic findings including H&E staining and four kinds of immunohistochemical staining in group 1.

RESULTS

In group 1, 73.1% (49/67) of nodules were hepatocellular carcinomas. In group 2, 32.7% (17/52) of nodules developed arterial hypervascularity on follow-up, and 78.8% (41/52) showed at least one of the three imaging features considered to indicate malignant changes during follow-up (mean 19 ± 10 months): increase in diameter by ≥5 mm (23/52, 44.2%), arterialization (17/52, 32.7%) and hyperintensity on T2-weighted images (18/52, 34.6%).

CONCLUSION

Our study results demonstrate that a significant proportion of non-hypervascular HBP hypointense nodules (≥1 cm in diameter) in patients with cirrhosis showed either malignant features on pathology (73.1%) or developed hypervascularity (32.7%) during follow-up.

Intraductal papillary mucinous neoplasms of the pancreas: evaluation of malignant potential and surgical resectability by using MR imaging with MR cholangiography

PURPOSE

To evaluate the diagnostic performance of magnetic resonance (MR) imaging with MR cholangiopancreatography (MRCP) in determining the malignant potential and surgical resectability of pancreas intraductal papillary mucinous neoplasms (IPMNs).

MATERIALS AND METHODS

Institutional review board approval was obtained, and the requirement for informed consent was waived. Ninety-eight patients with pathologically proved pancreas IPMNs who underwent MR imaging with MRCP comprised the study population. MR images were analyzed for findings suggestive of high-risk stigmata or worrisome features, as proposed by the international consensus guidelines 2012. Interobserver agreement between two experienced observers (observers 1 and 2) and one inexperienced observer (observer 3) was assessed. Diagnostic performance of MR imaging in the evaluation of the malignant potential and surgical resectability of IPMNs was analyzed in these three observers by using receiver operating curve analysis.

RESULTS

MR imaging with MRCP showed sensitivity of 83% (35/42), 79% (33/42), and 90% (38/42); specificity of 80% (41/51), 51% (26/51), and 24% (12/51); and accuracy of 82% (76/93), 63% (59/93), and 54% (50/93) for observers 1, 2, and 3, respectively, in the evaluation of the malignant potential of pancreas IPMNs when at least one worrisome feature was present. Interobserver agreement in the detection of intramural nodules (κ = 0.349-0.574), enhanced solid components (κ = 0.318-0.574), and measurement of main pancreatic duct diameter (intraclass correlation coefficient = 0.9477) was fair to high. The respective sensitivity, specificity, and accuracy in determination of surgical resectability were 95% (81/85), 99% (84/85), and 88% (75/85); 69% (9/13), 69% (9/13), and 54% (7/13); and 92% (90/98), 95% (93/98), and 84% (82/98) for observers 1, 2, and 3.

CONCLUSION

MR imaging with MRCP is a useful modality in the evaluation of the malignant potential and resectability of IPMNs, with high sensitivity and moderate specificity in the experienced radiologists but relatively low specificity in the inexperienced radiology trainee.

UltraFast Doppler ultrasonography for hepatic vessels of liver recipients: preliminary experiences

Purpose:

The purpose of this study was to investigate the value of UltraFast Doppler ultrasonography (US) for evaluating hepatic vessels in liver recipients.

Methods:

Thirty-nine liver Doppler US sessions were conducted in 20 liver recipients. Each session consisted of UltraFast and conventional liver Doppler US in a random order. We compared the velocities and phasicities of the hepatic vessels, duration of each Doppler study, occurrence of technical failures, and differences in clinical decisions.

Results:

The velocities and resistive index values of hepatic vessels showed a strong positive correlation between the two Doppler studies (mean R=0.806; range, 0.710 to 0.924). The phasicities of the hepatic vessels were the same in both Doppler US exams. With respect to the duration of the Doppler US exam, there was no significant difference between the UltraFast (251±99 seconds) and conventional (231±117 seconds) Doppler studies (P=0.306). In five poor breath-holders, in whom the duration of conventional Doppler US was longer, UltraFast Doppler US (272±157 seconds) required a shorter time than conventional Doppler US (381±133 seconds; P=0.005). There was no difference between the two techniques with respect to technical failures and clinical decisions.

Conclusion:

UltraFast Doppler US is clinically equivalent to conventional Doppler US with advantages for poor breath-holders during the post-liver transplantation work-up.

Diagnostic performance of gadoxetic acid-enhanced liver MR imaging in the detection of HCCs and allocation of transplant recipients on the basis of the Milan criteria and UNOS guidelines: correlation with histopathologic findings

PURPOSE

To determine whether hepatobiliary phase ( HBP hepatobiliary phase ) imaging can improve the diagnostic performance of gadoxetic acid-enhanced liver magnetic resonance (MR) imaging in the detection of hepatocellular carcinomas ( HCC hepatocellular carcinoma s) and to investigate the accuracy of gadoxetic acid-enhanced MR imaging in the allocation of transplant recipients on the basis of the Milan criteria and United Network for Organ Sharing ( UNOS United Network for Organ Sharing ) guidelines.

MATERIALS AND METHODS

This retrospective study had institutional review board approval; the requirement for informed consent was waived. Between June 2008 and June 2011, 63 patients who underwent liver transplantation (LT) were included. All patients underwent a gadoxetic acid-enhanced 3.0-T MR imaging examination of the liver that included HBP hepatobiliary phase images obtained 20 minutes after contrast material administration. Two abdominal radiologists independently assessed two MR imaging data sets to detect HCC hepatocellular carcinoma s: Set 1 included unenhanced and gadoxetic acid-enhanced dynamic images, and set 2 also included HBP hepatobiliary phase images. Patients were allocated into three groups: Those who did not meet the Milan criteria, those who did meet the Milan criteria with additional priority according to UNOS United Network for Organ Sharing guidelines, and those who did meet the Milan criteria without additional priority. Diagnostic performance of each data set in depicting HCC hepatocellular carcinoma s was compared by using jackknife alternative free-response receiver operating characteristics ( JAFROC jackknife alternative free-response receiver operating characteristic s). Sensitivity and accuracy of patient allocation were compared by using generalized estimating equations.

RESULTS

Sixty-three HCC hepatocellular carcinoma s were found in 36 of 63 patients. Eight patients were classified as not meeting Milan criteria, 12 as meeting Milan criteria with additional priority, and 43 as meeting Milan criteria without additional priority. For the detection of HCC hepatocellular carcinoma s, reader-averaged figures of merit estimated with JAFROC jackknife alternative free-response receiver operating characteristic s were 0.761 for set 1 and 0.791 for set 2 (P < .001). Addition of HBP hepatobiliary phase images significantly improved sensitivity for the detection of HCC hepatocellular carcinoma s, particularly 1-2-cm HCC hepatocellular carcinoma s (six [20.7%] vs 13 [44.8%] of 29 [P = .008] for reader 1 and eight [27.6%] vs 12 [41.4%] of 29 [P = .041] for reader 2). Accuracy of patient allocation was 88.9% for set 1 and 92.1% for set 2 (P = .151).

CONCLUSION

Addition of HBP hepatobiliary phase images can significantly improve the diagnostic performance of gadoxetic acid-enhanced liver MR imaging in the detection of 1-2-cm HCC hepatocellular carcinoma s in liver transplantation candidates. In addition, gadoxetic acid-enhanced MR imaging showed 92.1% accuracy in patient allocation on the basis of the Milan criteria and UNOS United Network for Organ Sharing guidelines.

Dynamic contrast-enhanced MRI of gastric cancer: Correlation of the perfusion parameters with pathological prognostic factors

PURPOSE

To investigate the feasibility of dynamic, contrast-enhanced, magnetic resonance imaging (DCE-MRI) for perfusion quantification of gastric cancers, and to correlate the DCE-MRI parameters with the pathological prognostic factors.

MATERIALS AND METHODS

This prospective study was approved by our Institutional Review Board. Twenty-seven patients with gastric cancers underwent DCE-MRI using a free-breathing, radial, gradient-echo (GRE) sequence with k-space weighted image contrast (KWIC) reconstruction on a 3T scanner. The DCE-MRI parameters (volume transfer coefficient [K(trans) ], reverse reflux rate constant [Kep ], extracellular extravascular volume fraction [Ve ], and initial area under the gadolinium concentration curve during the first 60 seconds [iAUC]) of gastric cancer and normal wall were measured and compared with each other using the Wilcoxon signed rank test. The relationship between the DCE-MRI parameters of gastric cancer and the pathological prognostic factors were evaluated using the Mann-Whitney test or the Spearman rank correlation test.

RESULTS

DCE-MRIs were of diagnostic quality in 22 patients (81.5%). Ve and iAUC were significantly higher in gastric cancer than in normal gastric wall (P < 0.05). Ve showed significant positive correlation with T-staging of gastric cancers (P < 0.05). K(trans) was significantly correlated with the grades of epidermal growth-factor receptor expression (P < 0.05).

CONCLUSION

DCE-MRI using a radial GRE with KWIC reconstruction is feasible for quantification of the perfusion dynamics of gastric cancers, and the DCE-MRI parameters of gastric cancers may provide prognostic information.

Ultra-low peak voltage CT colonography: effect of iterative reconstruction algorithms on performance of radiologists who use anthropomorphic colonic phantoms

PURPOSE

To analyze the effect of a decrease in computed tomographic (CT) colonographic voltage, from 100 and 120 kVp to 80 kVp and reconstructed with filtered back projection ( FBP filtered back projection ), on radiation dose, image noise, and diagnostic performance in anthropomorphic phantoms and to assess the effect of iterative reconstruction ( IR iterative reconstruction ) algorithms on radiologists' performance for 80-kVp CT colonography.

MATERIALS AND METHODS

Seven colon phantoms with 68 simulated polyps (≥6 mm) were scanned at three peak voltage settings (80, 100, 120 kVp) and 10 mAs. Images were reconstructed by using FBP filtered back projection , hybrid statistic-based IR iterative reconstruction , and knowledge-based IR iterative reconstruction algorithms. Effective radiation dose, image noise, and per-polyp sensitivity were recorded and compared by two reviewers with Friedman test, repeated measures analysis of variance, and McNemar test.

RESULTS

Median size-specific dose estimate and effective radiation dose of 80-kVp CT colonography was 0.231 mGy and 0.167 mSv, respectively, which was lower than with 100- and 120-kVp CT colonography, with significant difference between 80 and 120 kVp (P = .0005). Image noise (202.0 HU) at 80-kVp FBP filtered back projection CT colonography was significantly higher than at 100-kVp FBP filtered back projection (139.1 HU) and 120-kVp FBP filtered back projection (120.4 HU) (P < .0001). Per-polyp sensitivity (reviewer 1, 14.7% [10 of 68]; reviewer 2, 7.4% [five of 68]) at 80-kVp FBP filtered back projection was significantly lower than at 100-kVp FBP filtered back projection (reviewer 1, 57.4% [39 of 68]; reviewer 2, 39.7% [27 of 68]) and 120-kVp FBP filtered back projection (reviewer 1, 85.3% [58 of 68]; reviewer 2, 83.8% [57 of 68]) (P < .0001). With statistic-based IR iterative reconstruction , image noise at 80 kVp decreased significantly (52.8% [106.7 HU of 202.0 HU]) compared with that at 80-kVp FBP filtered back projection (P < .0001), but per-polyp sensitivity (reviewer 1, 79.4% [54 of 68]; reviewer 2, 66.2% [45 of 68]) at 80-kVp statistic-based IR iterative reconstruction remained significantly lower than at 100-kVp statistic-based IR iterative reconstruction (reviewer 1, 95.6% [65 of 68]; reviewer 2, 86.8% [59 of 68]) (P = .001) and 120-kVp statistic-based IR iterative reconstruction (reviewer 1, 98.5% [67 of 68]; reviewer 2, 89.7% [61 of 68]) (P < .001). For knowledge-based IR iterative reconstruction , per-polyp sensitivity at 80 kVp was improved to 98.5% (67 of 68) and 94.1% (64 of 68), not significantly different from that at 100 kVp (reviewer 1, 100% [68 of 68]; reviewer 2, 95.6% [65 of 68]) and 120 kVp (reviewer 1, 100% [68 of 68]; reviewer 2, 95.6% [65 of 68]) (P > .999).

CONCLUSION

A decrease in tube voltage to 80 kVp caused reduction in radiation dose (0.166 mSv) with deterioration in image noise and per-polyp sensitivity. By using a knowledge-based IR iterative reconstruction algorithm, radiologists' performance of 80-kVp CT colonography was acceptable and on par with that at 100- or 120-kVp CT colonography.

Image-guided tumor ablation: standardization of terminology and reporting criteria--a 10-year update

Image-guided tumor ablation has become a well-established hallmark of local cancer therapy. The breadth of options available in this growing field increases the need for standardization of terminology and reporting criteria to facilitate effective communication of ideas and appropriate comparison among treatments that use different technologies, such as chemical (eg, ethanol or acetic acid) ablation, thermal therapies (eg, radiofrequency, laser, microwave, focused ultrasound, and cryoablation) and newer ablative modalities such as irreversible electroporation. This updated consensus document provides a framework that will facilitate the clearest communication among investigators regarding ablative technologies. An appropriate vehicle is proposed for reporting the various aspects of image-guided ablation therapy including classification of therapies, procedure terms, descriptors of imaging guidance, and terminology for imaging and pathologic findings. Methods are addressed for standardizing reporting of technique, follow-up, complications, and clinical results. As noted in the original document from 2003, adherence to the recommendations will improve the precision of communications in this field, leading to more accurate comparison of technologies and results, and ultimately to improved patient outcomes. Online supplemental material is available for this article .

MRI of breast tumor initiating cells using the extra domain-B of fibronectin targeting nanoparticles

The identification of breast tumor initiating cells (BTICs) is important for the diagnosis and therapy of breast cancers. This study was undertaken to evaluate whether the extra domain-B of fibronectin (EDB-FN) could be used as a new biomarker for BTICs and whether EDB-FN targeting superparamagnetic iron oxide nanoparticles (SPIONs) could be used as a magnetic resonance imaging (MRI) contrast agent for BTIC imaging in vitro and in vivo. BTICs (NDY-1) exhibited high EDB-FN expression, whereas non-BTICs (MCF-7, BT-474, SUM-225, MDA-MB-231) did not exhibit EDB-FN expression. Furthermore, Cy3.3-labeled EDB-FN specific peptides (APTEDB) showed preferential binding to the targeted NDY-1 cells. To construct an EDB-FN targeted imaging probe, APTEDB was covalently attached to a thermally cross-linked SPION (TCL-SPION) to yield APTEDB-TCL-SPION. In the in vitro MRI of cell phantoms, selective binding of APTEDB-TCL-SPION to NDY-1 cells was evident, but little binding was observed in MCF-7 cells. After the intravenous injection of APTEDB-TCL-SPION into the NDY-1 mouse tumor xenograft model, a significant decrease in the signal within the tumor was observed in the T2*-weighted images; however, there was only a marginal change in the signal of non-targeting SPIONs such as APTscramble-TCL-SPION or TCL-SPION. Taken together, we report for the first time that EDB-FN was abundantly expressed in BTICs and may therefore be useful as a new biomarker for identifying BTICs. Our study also suggests that APTEDB-TCL-SPION could be used as an MRI contrast agent for BTIC imaging.

Staging accuracy of MR for pancreatic neuroendocrine tumor and imaging findings according to the tumor grade

PURPOSE

To investigate staging accuracy of MR for pancreatic neuroendocrine neoplasms (PNETs) and imaging findings according to the tumor grade.

MATERIALS AND METHODS

Our study consisted of 39 patients with PNET G1 (n = 24), PNET G2 (n = 12), and pancreatic neuroendocrine carcinoma (PNEC) (n = 3). All underwent preoperative MRI. Two radiologists retrospectively reviewed MR findings including tumor margin, SI on T2WI, enhancement patterns, degenerative change, duct dilation, and ADC value. They also assessed T-stage, N-stage, and tumor size. Statistical analyses were performed using Chi square tests, ROC analysis, and Fisher's exact test.

RESULTS

Specific findings for PNEC or PNET G2 were ill-defined borders (P = 0.001) and hypo-SI on venous- and delayed-phase (P = 0.016). ADC value showed significant difference between PNET G1 and G2 (P = 0.007). The Az of ADC value for differentiating PNET G1 from G2 was 0.743. Sensitivity and specificity were 70% and 86%. Accuracy for T-staging was 77% (n = 30) and 85% (n = 33), and for N-staging was 92% (n = 36) and 87% (n = 34) with moderate agreement. T-stage showed significant difference according to tumor grade (P < 0.001), although there was no significant difference in tumor size or N-stage.

CONCLUSION

Ill-defined borders and hypo-SI on venous- and delayed-phase imaging are common findings of higher grade PNET, and ADC value is helpful for differentiating PNET G1 from G2. MR is useful for preoperative evaluation of T-, N-stage. Tumor size of PNET and T-stage showed significant difference according to tumor grade.

Preoperative differentiation between T1a and ≥T1b gallbladder cancer: combined interpretation of high-resolution ultrasound and multidetector-row computed tomography

OBJECTIVES

To determine the diagnostic value of combined interpretation of high-resolution ultrasound (HRUS) and multidetector-row computed tomography (MDCT) for preoperative differentiation between T1a and ≥T1b gallbladder (GB) cancer.

METHODS

Eighty-seven patients with pathologically confirmed GB cancers (T1a, n = 15; ≥T1b, n = 72), who preoperatively underwent both HRUS and MDCT, were included in this retrospective study. Two reviewers independently determined the T-stages of the GB cancers on HRUS and MDCT using a five-point confidence scale (5, definitely T1a; 1, definitely ≥T1b). For individual modality interpretation, the lesions with scores ≥4 were classified as T1a, and, for combined modality interpretation, the lesions with all scores ≥4 in both modalities were classified as T1a. The McNemar test was used to compare diagnostic performance.

RESULTS

The diagnostic accuracy of differentiation between T1a and ≥T1b GB cancer was higher using combined interpretation (90.8% and 88.5% for reviewers 1 and 2, respectively) than individual interpretation of HRUS (82.8% and 83.9%) or MDCT (74.7% and 82.8%) (P < 0.05, reviewer 1). Combined interpretations demonstrated 100% specificity for both reviewers, which was significantly higher than individual interpretations (P < 0.05, both reviewers).

CONCLUSIONS

Combined HRUS and MDCT interpretation may improve the diagnostic accuracy and specificity for differentiating between T1a and ≥T1b GB cancers.

KEY POINTS

• Differentiating between T1a and ≥T1b gallbladder cancer can help surgical planning. • HRUS and MDCT are useful for local staging of gallbladder cancer. • HRUS and MDCT may be synergistic for T-staging of gallbladder cancer.

Intravoxel incoherent motion diffusion-weighted MR imaging for monitoring the therapeutic efficacy of the vascular disrupting agent CKD-516 in rabbit VX2 liver tumors

PURPOSE

To evaluate the diagnostic value of intravoxel incoherent motion (IVIM) diffusion-weighted (DW) magnetic resonance (MR) imaging in the quantitative assessment of the therapeutic efficacy of a vascular disrupting agent (VDA) (CKD-516) in rabbit VX2 liver tumors.

MATERIALS AND METHODS

The institutional animal care and use committee approved this study. In 21 VX2 liver tumor-bearing rabbits, IVIM DW imaging examinations were serially performed with a 3.0-T imaging unit by using 12 b values from 0 to 800 sec/mm(2). The apparent diffusion coefficient (ADC), true diffusion coefficient (D), pseudodiffusion coefficient (D*), perfusion fraction (f), and blood flow-related parameter (fD*) of tumors at different time points (baseline, 4 hours, 24 hours, 3 days, and 7 days after CKD-516 administration) were compared within the treated group (n = 15) by using the Friedman test as well as between the control (n = 6) and treated groups by using the Mann-Whitney test. Correlation between the change in tumor size and IVIM DW imaging parameters was analyzed by using the Spearman rank test.

RESULTS

In the treated group, D* and f significantly decreased at 4 hours and then recovered to baseline at 24 hours, while D significantly increased at 24 hours (P < .005). All IVIM-derived parameters showed no significant differences between the control and treated groups at 3- and at 7-day follow-up. The greater decrease observed in f and fD* at 4 hours correlated with the smaller increase in tumor size during the 7 days of follow-up (ρ = 0.53 and 0.65, respectively; P < .05 for both).

CONCLUSION

The therapeutic effect induced by a VDA could be effectively evaluated by using IVIM DW imaging, and f and fD* may be early predictive indicators of tumor response.

Portable high-intensity focused ultrasound system with 3D electronic steering, real-time cavitation monitoring, and 3D image reconstruction algorithms: a preclinical study in pigs

PURPOSE

The aim of this study was to evaluate the safety and accuracy of a new portable ultrasonography-guided high-intensity focused ultrasound (USg-HIFU) system with a 3-dimensional (3D) electronic steering transducer, a simultaneous ablation and imaging module, real-time cavitation monitoring, and 3D image reconstruction algorithms.

METHODS

To address the accuracy of the transducer, hydrophones in a water chamber were used to assess the generation of sonic fields. An animal study was also performed in five pigs by ablating in vivo thighs by single-point sonication (n=10) or volume sonication (n=10) and ex vivo kidneys by single-point sonication (n=10). Histological and statistical analyses were performed.

RESULTS

In the hydrophone study, peak voltages were detected within 1.0 mm from the targets on the y- and z-axes and within 2.0-mm intervals along the x-axis (z-axis, direction of ultrasound propagation; y- and x-axes, perpendicular to the direction of ultrasound propagation). Twenty-nine of 30 HIFU sessions successfully created ablations at the target. The in vivo porcine thigh study showed only a small discrepancy (width, 0.5-1.1 mm; length, 3.0 mm) between the planning ultrasonograms and the pathological specimens. Inordinate thermal damage was not observed in the adjacent tissues or sonic pathways in the in vivo thigh and ex vivo kidney studies.

CONCLUSION

Our study suggests that this new USg-HIFU system may be a safe and accurate technique for ablating soft tissues and encapsulated organs.

Noninvasive assessment of hepatic fibrosis in patients with chronic hepatitis B viral infection using magnetic resonance elastography

Objective

To evaluate the diagnostic performance of magnetic resonance elastography (MRE) for staging hepatic fibrosis in patients with chronic hepatitis B virus (HBV) infection.

Materials and Methods

Patients with chronic HBV infection who were suspected of having focal or diffuse liver diseases (n = 195) and living donor candidates (n = 166) underwent MRE as part of the routine liver MRI examination. We measured liver stiffness (LS) values on quantitative shear stiffness maps. The technical success rate of MRE was then determined. Liver cell necroinflammatory activity and fibrosis were assessed using histopathologic examinations as the reference. Areas under the receiver operating characteristic curve (Az) were calculated in order to predict the liver fibrosis stage.

Results

The technical success rate of MRE was 92.5% (334/361). The causes of technical failure were poor wave propagation (n = 12), severe respiratory motion (n = 3), or the presence of iron deposits in the liver (n = 12). The mean LS values, as measured by MRE, increased significantly along with an increase in the fibrosis stage (r = 0.901, p < 0.001); however, the mean LS values did not increase significantly along with the degree of necroinflammatory activity. The cutoff values of LS for ≥ F1, ≥ F2, ≥ F3, and F4 were 2.45 kPa, 2.69 kPa, 3.0 kPa, and 3.94 kPa, respectively, and with Az values of 0.987-0.988.

Conclusion

MRE has a high technical success rate and excellent diagnostic accuracy for staging hepatic fibrosis in patients with chronic HBV infection.

Differentiating between adenomyomatosis and gallbladder cancer: revisiting a comparative study of high-resolution ultrasound, multidetector CT, and MR imaging

Objective

To compare the diagnostic performance of high-resolution ultrasound (HRUS) with contrast-enhanced CT and contrast-enhanced magnetic resonance imaging (MRI) with MR cholangiopancreatography (MRCP) to differentiate between adenomyomatosis (ADM) and gallbladder cancer (GBCA).

Materials and Methods

Forty patients with surgically proven ADM (n = 13) or GBCA at stage T2 or lower (n = 27) who previously underwent preoperative HRUS, contrast-enhanced CT, and contrast-enhanced MRI with MRCP were retrospectively included in this study. According to the well-known diagnostic criteria, two reviewers independently analyzed the images from each modality separately with a five-point confidence scale. The interobserver agreement was calculated using weighted κ statistics. A receiver operating characteristic curve analysis was performed and the sensitivity, specificity, and accuracy were calculated for each modality when scores of 1 or 2 indicated ADM.

Results

The interobserver agreement between the two reviewers was good to excellent. The mean Az values for HRUS, multidetector CT (MDCT), and MRI were 0.959, 0.898, and 0.935, respectively, without any statistically significant differences between any of the modalities (p > 0.05). The mean sensitivity of MRI with MRCP (80.8%) was significantly higher than that of MDCT (50.0%) (p = 0.0215). However, the mean sensitivity of MRI with MRCP (80.8%) was not significantly different from that of HRUS (73.1%) (p > 0.05). The mean specificities and accuracies among the three modalities were not significantly different (p > 0.05).

Conclusion

High-resolution ultrasound and MRI with MRCP have comparable sensitivity and accuracy and MDCT has the lowest sensitivity and accuracy for the differentiation of ADM and GBCA.