So Jung Lee

A Prospective Comparison of Standard-Dose CT Enterography and 50% Reduced-Dose CT Enterography With and Without Noise Reduction for Evaluating Crohn Disease

OBJECTIVE The purpose of this study was to prospectively compare standard-dose CT enterography (CTE) and 50% reduced-dose CTE, obtained with and without an image noise reduction method, in the evaluation of Crohn disease. SUBJECTS AND METHODS Ninety-two patients (69 men and 23 women; mean age [± SD], 31.2 ± 9.5 years) with Crohn disease underwent CTE. Using a dual-source scanner equipped with a proprietary noise reduction method (iterative reconstruction in image space [IRIS]), three sets of CTE images were obtained: standard-dose filtered back projection (FBP) (i.e., weighted FBP), low-dose (i.e., 50% reduction) FBP, and low-dose IRIS CTE. Image noise was measured. Two independent radiologists evaluated subjective image quality (1 [worst] to 4 [best]) and findings of active Crohn disease in the terminal small-bowel segment, including mural hyperenhancement, thickening and stratification, comb sign, and increased perienteric fat attenuation (1 [definitely absent] to 5 [definitely present]). RESULTS The mean (± SD) volume CT dose index (CTDI(vol)) was 7.0 ± 0.9 mGy and 3.5 ± 0.5 mGy for standard-dose and low-dose CTE examinations, respectively. The mean (± SD) image noise for standard-dose FBP, low-dose FBP, and low-dose IRIS CTE was 10.6 ± 1.7 HU, 13.9 ± 2.1 HU, and 9.7 ± 1.7 HU, respectively (p < 0.001 for all comparisons). Both assessors found that image quality was poorer with low-dose (mean grade (± SD), 2.3 ± 0.4-2.7 ± 0.5) than in standard-dose (3 ± 0) CTE (p < 0.01), and one found that image quality was poorer with low-dose IRIS (2.3 ± 0.4) than with low-dose FBP (2.7 ± 0.5) CTE (p < 0.01). Low-dose (with or without IRIS) and standard-dose CTE showed ≥ 85% agreement (one-sided 95% CI ≥ 77%) in interpretation of bowel findings. CONCLUSION Low-dose CTE using 50% reduced-dose performed similarly to standard-dose CTE in identifying findings of enteric inflammation of Crohn disease. Although a noise reduction method markedly reduced image noise in half-dose examinations, its effect on image quality was not as great and was reader dependent.

Hepatic Arterial Stenosis Assessed with Doppler US after Liver Transplantation: Frequent False-Positive Diagnoses with Tardus Parvus Waveform and Value of Adding Optimal Peak Systolic Velocity Cutoff

PURPOSE To evaluate the utility of the tardus parvus waveform of the hepatic artery at Doppler ultrasonography (US) in the diagnosis of hepatic arterial stenosis in liver transplant (LT) recipients and determine whether the accuracy of such a diagnosis is enhanced by including an optimal peak systolic velocity (PSV) cutoff. MATERIALS AND METHODS This retrospective study was institutional review board approved; the requirement for informed consent was waived. The authors identified 361 LT recipients (267 male, 94 female) who underwent Doppler US and either computed tomography (CT) or angiography, with an interval between these examinations of less than 1 week. At Doppler US, tardus parvus pattern was defined as a waveform with a resistive index (RI) of less than 0.5 and a systolic acceleration time longer than 0.08 second. At CT or angiography, patients were assigned to the hepatic arterial stenosis (≥50% vessel narrowing) or nonstenosis group. The capability of the tardus parvus pattern to facilitate the diagnosis of hepatic arterial stenosis was calculated. The difference in PSV between the true- and false-positive tardus parvus patterns was evaluated. Receiver operating characteristic (ROC) analysis was performed to determine the optimal cutoff PSV for diagnosing hepatic arterial stenosis. The capability of the tardus parvus pattern and an optimal PSV cutoff in the diagnosis of hepatic arterial stenosis was determined. RESULTS Sixty transplant recipients had the tardus parvus pattern at Doppler US. The sensitivity, specificity, and positive predictive value (PPV) of the tardus parvus pattern were 72% (23 of 32 LT recipients), 88.8% (292 of 329 LT recipients), and 38% (23 of 60 LT recipients), respectively. The false-positive rate was 11.2% (37 of 329 LT recipients). ROC analysis revealed an optimal PSV cutoff of less than or equal to 48 cm/sec for diagnosing hepatic arterial stenosis. The combination of the tardus parvus pattern and a PSV cutoff of less than or equal to 48 cm/sec improved specificity to 99.1% (326 of 329 LT recipients) and the PPV to 88% (22 of 25 LT recipients), thereby reducing the false-positive rate to 1% (three of 329 LT recipients) while slightly decreasing the sensitivity to 69% (22 of 32 LT recipients). CONCLUSION Use of the tardus parvus waveform of the hepatic artery resulted in a low PPV and a high false-positive rate. However, the combination of the tardus parvus pattern and an optimal PSV cutoff greatly improved the PPV and reduced the false-positive rate in the diagnosis of hepatic arterial stenosis.

Determination of Normal Hepatic Elasticity by Using Real-time Shear-wave Elastography

PURPOSE To determine normal reference values of liver elasticity and measurement reliability by using real-time shear-wave elastography (SWE) in patients with a range of ages and body mass index (BMI) measurements, with presence or absence of hepatic steatosis. MATERIALS AND METHODS The institutional review board approved this study, and informed consent was waived because of the retrospective nature of the study. Two hundred thirty-eight patients who underwent SWE and ultrasonography-guided liver biopsies on the same day were identified retrospectively. The median kilopascal value of three consecutive measurements was used as a representative value for each subject. One hundred ninety-six patients who were potential donors for living-donor liver transplantation and had biopsy-proven normal (123 nonsteatotic and 73 steatotic) livers as the only histologic abnormality were included in the study. Reference ranges of normal hepatic elasticity were calculated by using lower and upper limits at the 2.5 and 97.5 percentiles. With the upper value of the reference range as a cutoff value, the sensitivity and specificity for the diagnosis of hepatic fibrosis were calculated. Measurement reliability was evaluated by using the intraclass correlation coefficient (ICC). To investigate the effects of potential confounding factors (age, hepatic steatosis, and BMI) on liver elasticity, the Pearson correlation test and the Student t test were performed. RESULTS The reference range of normal hepatic elasticity was 2.6-6.2 kPa. With 6.2 kPa as a cutoff value, the sensitivity and specificity for the diagnosis of hepatic fibrosis were 91% (20 of 22 subjects) and 95.9% (188 of 196 subjects), respectively. The overall ICC for the elasticity measurements was 0.924. The potential confounding factors that we considered had negligible effects on the elasticity values. CONCLUSION Hepatic elasticity values measured with SWE in histologically proven normal livers ranged from 2.6 to 6.2 kPa, with high measurement reliability. The effect of the potential confounding factors on liver elasticity was negligible.

Evaluation of Early-Stage Hepatocellular Carcinoma by Magnetic Resonance Imaging With Gadoxetic Acid Detects Additional Lesions and Increases Overall Survival

BACKGROUND & AIMS Hepatocellular carcinoma (HCC) has a high rate of intrahepatic recurrence after curative treatment, possibly because metastases are not always identified before treatment. Magnetic resonance (MR) imaging with a liver-specific contrast agent, gadoxetic acid, can detect small HCCs with high levels of sensitivity. We investigated whether MR imaging with gadoxetic acid increases overall and recurrence-free survival of patients initially assessed by computed tomography (CT). METHODS We performed a retrospective study of data from 700 patients diagnosed with a single-nodular HCC by dynamic 4-phase CT in Seoul, Korea, from January 2009 through December 2010. Of these patients, 323 underwent additional evaluation with gadoxetic acid-enhanced MR imaging (CT+MR group). The 377 patients who did not undergo MR imaging analysis are referred to as the CT group. RESULTS The CT and CT+MR groups were comparable in most baseline characteristics (Child-Pugh class A, 93.1% vs 94.7%; and median size of the primary HCCs, 2.8 vs 2.6 cm, respectively). Seventy-four additional HCC nodules were detected in 53 (16.4%) of the patients who underwent MR evaluation after CT (CT+MR group). These detections increased the Barcelona Clinic Liver Cancer stages for 43 patients (13.3%) and modified their treatment plans. On multivariable analyses, the CT+MR group had a significantly lower rate of HCC recurrence (hazard ratio [HR], 0.72; 95% confidence interval [CI], 0.54-0.96) and lower overall mortality (HR, 0.65; 95% CI, 0.44-0.96) than the CT group. In an analysis of 285 pairs of patients matched on the basis of the propensity score, the CT+MR group had significantly lower overall mortality (HR, 0.66; 95% CI, 0.44-0.99). CONCLUSIONS Among patients who underwent dynamic CT analysis of a single-nodular HCC, additional evaluation by MR imaging with gadoxetic acid led to the detection of additional HCC nodules in 16% of patients, reduced the risk of disease recurrence, and decreased overall mortality.

Diagnostic criteria for hepatocellular carcinoma ⩽3 cm with hepatocyte-specific contrast-enhanced magnetic resonance imaging

BACKGROUND & AIMS Current diagnostic imaging criteria for hepatocellular carcinoma (HCC) are dedicated to imaging with nonspecific extracellular contrast agents. This study aimed to evaluate diagnostic criteria for HCC ⩽3 cm on magnetic resonance imaging (MRI) with a hepatocyte-specific contrast agent through an inception cohort study. METHODS Of 291 patients with chronic liver disease and new nodules of 1-3 cm in diameter at surveillance ultrasonography, 295 solid nodules (194 HCCs, 98 benign nodules, and three other malignancies) in 198 patients with a confirmed final diagnosis or ⩾24 months follow-up were evaluated on gadoxetic acid-enhanced MRI. Through univariate and multivariate logistic regression analyses, various diagnostic criteria were developed by combining significant MRI findings for diagnosing HCC. The diagnostic performance of each criterion was compared with that of the European Association for the Study of the Liver (EASL) criteria. RESULTS Four MRI findings (arterial-phase hyperintensity, transitional-phase hypointensity, hepatobiliary-phase hypointensity, and rim enhancement) were independently significant for diagnosis of HCC ⩽3 cm. For whole nodules, EASL criteria showed the best performance for diagnosing HCC (sensitivity, 83.5%; specificity, 81.2%). For nodules ⩽2 cm in diameter, a new criterion (arterial-phase hyperintensity and hepatobiliary-phase hypointensity) showed a significantly higher sensitivity than that of the EASL criteria (83.0% vs. 74.5%, p=0.008), without a significantly different specificity (76.7% vs. 81.1%, p=0.125). CONCLUSIONS EASL criteria exhibit the best diagnostic performance for HCC ⩽3 cm on hepatocyte-specific contrast-enhanced MRI. A newly identified criterion (arterial-phase hyperintensity and hepatobiliary-phase hypointensity) may increase the diagnostic sensitivity of small (⩽2 cm) HCC.

Diagnostic Strategy for Differentiating Autoimmune Pancreatitis From Pancreatic Cancer: Is an Endoscopic Retrograde Pancreatography Essential?

Objectives The purpose of this study was to determine whether the choice for performance of endoscopic retrograde pancreatography (ERP) could be tailored to findings on computed tomography (CT) in patients with suspected autoimmune pancreatitis (AIP). Methods Eighty-four AIP patients and 73 pathology-proven pancreatic cancer patients from a prospectively maintained database were retrospectively included. Computed tomography and ERP images were reviewed in consensus by 2 blinded radiologists. The diagnostic performance of CT alone and combined use of CT and ERP (CT-ERP) were compared. Results The area under the receiver operating characteristic curve of CT-ERP was significantly greater than that of CT alone (0.97 vs 0.87, P < 0.001). When patients with AIP were divided into 2 subgroups according to CT features (typical vs atypical), 24 (69%) of 35 AIP patients with atypical CT findings were correctly diagnosed with AIP at CT-ERP and received benefits from additional ERP. Endoscopic retrograde pancreatography had little added benefit in patients with typical CT findings for AIP (n = 49), because no alternative diagnoses were established after ERP. Conclusions In patients with suspected AIP, the decision to perform ERP could be tailored to findings on CT.

Liver Imaging Reporting and Data System v2014 With Gadoxetate Disodium–enhanced Magnetic Resonance Imaging: Validation of Li-rads Category 4 and 5 Criteria

ObjectivesThe aim of this study was to validate the Liver Imaging Reporting and Data System (LI-RADS) v2014 category 4 (LR-4) and 5 (LR-5) criteria on gadoxetate disodium–enhanced magnetic resonance imaging (MRI) in patients with chronic liver disease. Materials and MethodsBetween January and December 2012, 300 patients with chronic liver disease who had hepatic nodules 3.0 cm or smaller at surveillance ultrasonography and gadoxetate disodium–enhanced MRI were included. LI-RADS category was retrospectively assigned to each nodule on MRI. Final diagnosis was assessed using pathologic diagnosis only (operation or core-needle biopsy) or pathologic and clinical diagnosis (marginal recurrence after treatment or a change in lesion size on follow-up imaging). To validate the LR-4 and LR-5 criteria, the sensitivity, positive predictive value (PPV), and false referral rate for diagnosing hepatocellular carcinoma were examined. ResultsBased on major imaging features only, 137 nodules were initially assigned as LR-3, but 133 (97.1%) were upgraded into LR-4 by the presence of ancillary features. Excluding the remaining 4 LR-3 and 3 LR-M nodules, we analyzed 379 nodules in 294 patients, consisting of 211 LR-4 and 168 LR-5 nodules. Using pathologic diagnosis only, the sensitivity and PPV with 95% confidence intervals (CIs) for LR-5 were higher than those for LR-4 (57.3% [50.6–63.7] vs 42.7% [36.3–49.4]; 94.6% [89.0–97.5] vs 82.0% [73.7–88.1]), with a lower false referral rate (5.4% [2.5–11.0] vs 18.0% [11.9–26.3]). Using pathologic and clinical diagnosis, PPV and 95% CI for LR-5 were higher than that for LR-4 (95.2% [90.7–97.7] vs 79.1% [73.1–84.1]), whereas sensitivity and 95% CI for LR-5 was similar to that for LR-4 (48.9% [43.6–54.3] vs 51.1% [45.7–56.4]). ConclusionsIn patients with chronic liver disease, LR-5 criteria on gadoxetate disodium–enhanced MRI had excellent PPV for diagnosing hepatocellular carcinoma, whereas LR-4 criteria showed good PPV, but are only of limited use.

Differential diagnosis of sclerosing cholangitis with autoimmune pancreatitis and periductal infiltrating cancer in the common bile duct at dynamic CT, endoscopic retrograde cholangiography and MR cholangiography

AbstractObjectivesTo compare findings at dynamic computed tomography (CT), endoscopic retrograde cholangiography (ERC) and magnetic resonance cholangiography (MRC) in patients with sclerosing cholangitis with autoimmune pancreatitis (SC-AIP) and periductal infiltrating cancer in the common bile duct (CBD), and to evaluate the diagnostic performance of ERC and MRC in differentiating between the two diseases.MethodsBile duct changes at dynamic CT, ERC and MRC were compared in 58 patients with SC-AIP and CBD involvement and 93 patients with periductal infiltrating CBD cancer. Two radiologists rated their confidence in differentiating between the two diseases and the diagnostic performances of ERC and MRC were compared.ResultsAt CT, SC-AIP was more frequently associated with intrapancreatic CBD involvement, thinner CBD walls, concentric wall thickening, smooth outer margins, and lower degrees of upstream ductal dilatation and contrast enhancement (P ≤ 0.05) than CBD cancer. At ERC and MRC, SC-AIP was more frequently associated with smooth margins, gradual and symmetric narrowing, multifocal involvement and hourglass appearance (P ≤ 0.027) than CBD cancer. MRC showed good diagnostic performance comparable to ERC.ConclusionsDynamic CT, ERC and MRC can be helpful in distinguishing SC-AIP from periductal infiltrating CBD cancer. MRC may be a useful diagnostic alternative to ERC in differentiating between the two diseases.Key Points• SC-AIP often mimics periductal infiltrating ductal cancer. • Imaging findings of SC-AIP and periductal infiltrating CBD cancer can be similar. • Dynamic CT, ERC and MRC help differentiate between these two diseases. • MRC may be a useful diagnostic alternative to ERC.

MRI With Liver-Specific Contrast for Surveillance of Patients With Cirrhosis at High Risk of Hepatocellular Carcinoma

Importance Current recommendations for patients with cirrhosis are to undergo surveillance for hepatocellular carcinoma (HCC) with ultrasonography (US) every 6 months. However, the sensitivity of US screening to detect early-stage HCC is suboptimal. Magnetic resonance imaging (MRI) with liver-specific contrast may detect additional HCCs missed by US in high-risk patients with cirrhosis. Objective To compare the HCC detection rate of US and MRI in patients with cirrhosis who are at high risk for HCC. Design, Setting, and Participants A prospective surveillance study of 407 patients with cirrhosis and an estimated annual risk of HCC greater than 5% who underwent 1 to 3 biannual screening examinations with paired US and liver-specific contrast-enhanced MRI at a tertiary care hospital between November 2011 and August 2014. All patients were followed-up with dynamic computed tomography (CT) at 6 months after the study. The confirmation of HCC was based on the results of histologic examination and/or typical CT images of HCC. Main Outcomes and Measures HCC detection rates and false-positive findings of US vs MRI. Results A total of 407 eligible patients received 1100 screenings with paired US and MRI. Hepatocellular carcinomas were diagnosed in 43 patients: 1 detected by US only, 26 by MRI only, 11 by both, and 5 were missed by both. The HCC detection rate of MRI was 86.0% (37/43), significantly higher than the 27.9% (12/43) of US (P < .001). Magnetic resonance imaging showed a significantly lower rate of false-positive findings than US (3.0% vs 5.6%; P = .004). Of the 43 patients with HCC, 32 (74.4%) had very early-stage HCC (a single nodule <2 cm), and 29 (67.4%) received curative treatments. The 3-year survival rate of the patients with HCC (86.0%) was not inferior to those without HCC (94.2%; hazard ratio, 2.26; 95% CI, 0.92-5.56; P = .08). Conclusions and Relevance In patients with cirrhosis at high-risk of HCC, screening that used MRI with liver-specific contrast resulted in a higher HCC detection rate and lower false-positive findings compared with US. With MRI screening, most of the cancers detected were at very early stage, which was associated with a high chance of curative treatments and favorable survival of patients. Whether surveillance with MRI would reduce mortality from HCC in high-risk patients requires further investigation. Trial Registration clinicaltrials.gov Identifier: NCT01446666

3′-Deoxy-3′-18F-Fluorothymidine PET for the Early Prediction of Response to Leucovorin, 5-Fluorouracil, and Oxaliplatin Therapy in Patients with Metastatic Colorectal Cancer

The aim of this study was to evaluate 3′-deoxy-3′-18F-fluorothymidine (18F-FLT) PET for early prediction of the standard anatomic response and survival outcomes in patients with metastatic colorectal cancer (mCRC) receiving leucovorin, 5-fluorouracil (5-FU), and oxaliplatin (FOLFOX). Methods: The main eligibility criteria included histologically confirmed mCRC, ≥1 extrahepatic measurable lesions, and no prior chemotherapy in a metastatic setting. Chemotherapy consisted of leucovorin on day 1, followed by the continuous infusion of 5-FU on days 1 and 2, and oxaliplatin on day 3. In the second and subsequent cycles of chemotherapy, oxaliplatin was administered simultaneously with leucovorin on day 1. 18F-FLT PET scans were obtained 3 times during the first cycle of chemotherapy: before chemotherapy, 24 h after infusion of 5-FU (day 2), and 48 h after completion of chemotherapy (day 5). The maximum standardized uptake value (SUVMAX) of 18F-FLT was measured. Treatment responses were assessed by CT after 3 cycles of FOLFOX. Results: Eighteen patients were included in the study. The response rate after 3 cycles of FOLFOX was 27.8% (5/18). The SUVMAX was increased in responders (P = 0.043) and nonresponders (P < 0.001) on day 2 and was decreased, compared with baseline values, on day 5 in responders only (P = 0.043). Receiver-operating-characteristic curve analysis indicated that the use of a threshold of an SUVMAX increase on day 2 of ≤45.8% resulted in a sensitivity of 100%, specificity of 69.2%, and relative risk of 2.250 (P = 0.029) for the diagnosis of responders. Use of a threshold of an SUVMAX decrease on day 5 of ≥10.6% resulted in a sensitivity of 100%, specificity of 76.9%, and relative risk of 2.667 (P = 0.007). Patients with low 18F-FLT flare tended to have longer survivals than patients with high flare (2-y overall survival rate, 77.8% vs. 44.4%; P = 0.051). Conclusion: The 18F-FLT flare observed during 5-FU infusion was associated with poor treatment response in patients with mCRC. The degree of 18F-FLT flare might be used to predict the outcome of patients who receive infusional 5-FU–based chemotherapy.