Fast T2-weighted liver MRI: Image quality and solid focal lesions conspicuity using a deep learning accelerated single breath-hold HASTE fat-suppressed sequence.

PURPOSE: Acceleration of MRI acquisitions and especially of T2-weighted sequences is essential to reduce the duration of MRI examinations but also kinetic artifacts in liver imaging. The purpose of this study was to compare the acquisition time and the image quality of a single-shot fat-suppressed turbo spin-echo (TSE) T2-weighted sequence with deep learning reconstruction (HASTEDL) with that of a fat-suppressed T2-weighted BLADE TSE sequence in patients with focal liver lesions. MATERIALS AND METHODS: Ninety-five patients (52 men, 43 women; mean age: 61 ± 14 [SD]; age range: 28-87 years) with 42 focal liver lesions (17 hepatocellular carcinomas, 10 sarcoidosis lesions, 9 myeloma lesions, 3 liver metastases and 3 focal nodular hyperplasias) who underwent liver MRI at 1.5 T including HASTEDL and BLADE sequences were retrospectively included. Overall image quality, noise level in the liver, lesion conspicuity and sharpness of liver lesion contours were assessed by two independent readers. Liver signal-to-noise ratio (SNR) and lesion contrast-to-noise ratio (CNR) were measured and compared between the two sequences, as well as the mean duration of the sequences (Student t-test or Wilcoxon test for paired data). RESULTS: Median overall quality on HASTEDL images (3; IQR: 3, 3) was significantly greater than that on BLADE images (2; IQR: 1, 3) (P < 0.001). Median noise level in the liver on HASTEDL images (0; IQR: 0, 0.5) was significantly lower than that on BLADE images (1; IQR: 1, 2) (P < 0.001). On HASTEDL images, mean liver SNR (107.3 ± 39.7 [SD]) and mean focal liver lesion CNR (87.0 ± 76.6 [SD]) were significantly greater than those on BLADE images (67.1 ± 23.8 [SD], P < 0.001 and 48.6 ± 43.9 [SD], P = 0.027, respectively). Acquisition time was significantly shorter with the HASTEDL sequence (18 ± [0] s; range: 18-18 s) compared to BLADE sequence (152 ± 47 [SD] s; range: 87-263 s) (P < 0.001). CONCLUSION: By comparison with the BLADE sequence, HASTEDL sequence significantly reduces acquisition time while improving image quality, liver SNR and focal liver lesions CNR.

Chest PET/MRI in Solid Cancers: Comparing the Diagnostic Performance of a Free-Breathing 3D-T1-GRE Stack-of-Stars Volume Interpolated Breath-Hold Examination (StarVIBE) Acquisition With That of a 3D-T1-GRE Volume Interpolated Breath-Hold Examination (VIBE) for Chest Staging During Whole-Body PET/MRI.

BACKGROUND: Whole-body positron emission tomography/magnetic resonance imaging (WB-PET/MRI) is increasingly used in oncology. However, chest staging remains challenging. PURPOSE: To compare the diagnostic performance of a free-breathing 3D-T1-GRE stack-of-stars volume interpolated breath-hold examination (StarVIBE) with that of a 3D-T1-GRE volume interpolated breath-hold examination (VIBE) during WB-PET/MRI for chest staging. STUDY TYPE: Retrospective, cohort study. POPULATION: One hundred and twenty-three patients were referred for initial staging of solid cancer, 46 of whom had pulmonary nodules and 14 had pulmonary metastasis. FIELD STRENGTH/SEQUENCE: Free-breathing 3D-T1-GRE stack-of-stars (StarVIBE) and Cartesian 3D-T1-GRE VIBE at 3.0 T. ASSESSMENT: Image quality was assessed using a 4-point scale and using the signal-to-noise ratio (SNR) of lung parenchyma and contrast-to-noise ratio (CNR) of pulmonary nodules. Diagnostic performances of both sequences were determined by three independent radiologists for detection of pulmonary nodules, lymph node involvement, and bone metastases using chest CT, pathology, and follow-up as reference standards. STATISTICAL TESTS: Paired Student's t-test; chi-squared; Fisher's exact test. A P value <0.05 was considered statistically significant. RESULTS: StarVIBE quality was judged as better in 34% of cases and at least equivalent to VIBE in 89% of cases, with significantly higher quality scores (4 [4-4] vs. 3 [3-4], respectively). SNR and CNR values were significantly higher with StarVIBE (8 ± 1.3 and 9.7 ± 4.6, respectively) than with VIBE (1.8 ± 0.2 and 5.5 ± 3.3, respectively). Compared to VIBE, StarVIBE showed significantly higher sensitivity (73% [95% CI 62-82] vs. 44% [95% CI 33-55], respectively) and specificity (95% [95% CI 88-99] vs. 67% [95% CI 56-77]) for pulmonary nodules detection and significantly higher sensitivity (100% [95% CI 89-100] vs. 67% [95% CI 48-82], respectively) for detection of lymph node involvement. Sensitivities for bone metastases detection were not significantly different (100% [95% CI 88-100] vs. 82% [95% CI 63-94], P = 0.054). DATA CONCLUSION: Owing to improved SNR and CNR and spatial resolution, a free-breathing 3D stack-of-stars T1-GRE sequence improves chest staging in comparison with standard 3D-T1-GRE VIBE and may be integrated in WB-PET/MRI acquisitions for initial staging of solid cancer. LEVEL OF EVIDENCE: 3 TECHNICAL EFFICACY: Stage 2.

Optimization of whole-body 2-[18F]FDG-PET/MRI imaging protocol for the initial staging of patients with myeloma.

OBJECTIVE: To determine the optimal 2-[18F]FDG-PET/MRI imaging protocol for the initial staging of patients with suspected or confirmed multiple myeloma. METHODS: Radiologists and nuclear medicine specialists reviewed all PET/MRI exams of 104 patients with a monoclonal gammopathy (MG). The presence of focal and diffuse bone marrow involvement (BMI) was assessed using 4 different image datasets: WB-MRI, PET, WB-PET/MRI, and WB-DCE-PET/MRI. A reference standard was established by a panel review of all baseline and follow-up imaging, and biological and pathological information. The diagnostic performance for each image dataset to detect BMI was evaluated and compared (Fisher's exact test). RESULTS: Sensitivity, specificity, and accuracy for focal BMI of WB-MRI was 87%, 97%, and 92%; of PET was 78%, 97%, and 95%; of WB-PET/MRI was 93%, 97%, and 95%; and of WB-DCE-PET/MRI was 93%, 97%, and 95%, respectively. WB-PET/MRI and WB-DCE-PET/MRI were statistically superior to PET (p = 0.036) without decreasing specificity. The sensitivity, specificity, and accuracy of WB-MRI for diffuse BMI detection was 91%, 80%, and 85%; of 3DT1-PET was 53%, 89%, and 74%; of WB-PET/MRI was 98%, 66%, and 79%; and of WB-DCE-PET/MRI was 98%, 59%, and 75%, respectively. PET lacked sensitivity compared to all other dataset studies (p < 0.0001). WB-MRI had the best accuracy without reaching statistical significance when compared to the other datasets. CONCLUSION: The WB-PET/MRI dataset including T1 and T2 Dixon, WB-DWI, and PET images provides optimal diagnostic performance to detect both focal lesions and diffuse BMI, with limited added value of WB-DCE for baseline staging of patients with MG. Key Points • The combination of morphological and functional MRI sequences and metabolic (2-[18F]FDG-PET) images increases the diagnostic performance of PET/MRI to detect focal bone lesions. • The adjunction of dynamic contrast-enhanced sequences did not improve diagnostic performance.

Impact of the 18F-FDG-PET/MRI on Metastatic Staging in Patients with Hepatocellular Carcinoma: Initial Results from 104 Patients.

Optimal HCC therapeutic management relies on accurate tumor staging. Our aim was to assess the impact of 18F-FDG-WB-PET/MRI on HCC metastatic staging, compared with the standard of care CT-CAP/liver MRI combination, in patients with HCC referred on a curative intent or before transarterial radioembolization. One hundred and four consecutive patients followed for HCC were retrospectively included. The WB-PET/MRI was compared with the standard of care CT-CAP/liver MRI combination for HCC metastatic staging, with pathology, followup, and multidisciplinary board assessment as a reference standard. Thirty metastases were identified within 14 metastatic sites in 11 patients. The sensitivity of WB-PET/MRI for metastatic sites and metastatic patients was significantly higher than that of the CT-CAP/liver MRI combination (respectively 100% vs. 43%, p = 0.002; and 100% vs. 45%, p = 0.01). Metastatic sites missed by CT-CAP were bone (n = 5) and distant lymph node (n = 3) in BCLC C patients. For the remaining 93 nonmetastatic patients, three BCLC A patients identified as potentially metastatic on the CT-CAP/liver MRI combination were correctly ruled out with the WB-PET/MRI without significant increase in specificity (100% vs. 97%; p = 0.25). The WB-PET/MRI may improve HCC metastatic staging and could be performed as a "one-stop-shop" examination for HCC staging with a significant impact on therapeutic management in about 10% of patients especially in locally advanced HCC.

Virtual unenhanced imaging of the liver derived from 160-mm rapid-switching dual-energy CT (rsDECT): Comparison of the accuracy of attenuation values and solid liver lesion conspicuity with native unenhanced images.

OBJECTIVES: To evaluate the reliability of attenuation values of the liver parenchyma and focal liver lesions on virtual unenhanced images from arterial (VUEart) and portal venous phases (VUEport) compared to native unenhanced (NU) attenuation values in patients referred for assessment of malignant liver lesions. METHODS: Seventy-three patients with confirmed primary or metastatic liver tumors who underwent a multiphase contrast-enhanced rapid-switching kVp dual-energy CT (rsDECT) were included in this IRB-approved retrospective study. Both qualitative and quantitative analyses - including the lesion-to-liver contrast-to-noise ratio (LL-CNR) - were performed and compared between NU and both VUEart and VUEport images. RESULTS: The mean liver attenuation values were significantly lower in VUEart images (56.7 ±â€¯6.7 HU) than in NU images (59.6 ±â€¯7.5 HU, p = 0.008), and were comparable between VUEart and VUEport images (57.9 ±â€¯6 UH, p = 0.38) and between VUEport and NU images (p = 0.051). The mean liver lesions attenuation values were comparable between NU, VUEart and VUEport images (p = 0.60). Strong and significant correlations values were found both in liver lesions and tumor-free parenchyma (r = 0.82-0.91, p < 0.01). The mean LL-CNR was significantly higher in VUEart and VUEport images than in NU images (1.7 ±â€¯1 and 1.6 ±â€¯1.1 vs 0.9 ±â€¯0.6; p < 0.001), but was comparable between VUEart and VUEport images (p > 0.9). Lesion conspicuity was significantly higher in VUEport images than in NU images (p < 0.001). CONCLUSION: VUEport images derived from 3rd generation rsDECT could confidently replace NU images in patients undergoing assessment for malignant liver lesions. These images provide comparable attenuation values in both liver lesions and liver parenchyma while reducing the radiation dose and scanning time.

Whole-Body Functional MRI and PET/MRI in Multiple Myeloma.

Bone disease is one of the major features of multiple myeloma (MM), and imaging has a pivotal role in both diagnosis and follow-up. Whole-body magnetic resonance imaging (MRI) is recognized as the gold standard for the detection of bone marrow involvement, owing to its high sensitivity. The use of functional MRI sequences further improved the performances of whole-body MRI in the setting of MM. Whole-body diffusion-weighted (DW) MRI is the most attractive functional technique and its systematic implementation in general clinical practice is now recommended by the International Myeloma Working Group. Whole-body dynamic contrast-enhanced (DCE) MRI might provide further information on lesions vascularity and help evaluate response to treatment. Whole Body PET/MRI is an emerging hybrid imaging technique that offers the opportunity to combine information on morphology, fat content of bone marrow, bone marrow cellularity and vascularization, and metabolic activity. Whole-body PET/MRI allows a one-stop-shop examination, including the most sensitive technique for detecting bone marrow involvement, and the most recognized technique for treatment response evaluation. This review aims at providing an overview on the value of whole-body MRI, including DW and DCE MRI, and combined whole-body 18F-FDG PET/MRI in diagnosis, staging, and response evaluation in patients with MM.

Multiphase Liver MRI for Identifying the Macrotrabecular-Massive Subtype of Hepatocellular Carcinoma.

Background The recently described "macrotrabecular-massive" (MTM) histologic subtype of hepatocellular carcinoma (HCC) (MTM-HCC) represents an aggressive form of HCC and is associated with poor survival. Purpose To investigate whether preoperative MRI can help identify MTM-HCCs in patients with HCC. Materials and Methods This retrospective study included patients with HCC treated with surgical resection between January 2008 and February 2018 and who underwent preoperative multiphase contrast material-enhanced MRI. Least absolute shrinkage and selection operator (LASSO)-penalized and multivariable logistic regression analyses were performed to identify clinical, biologic, and imaging features associated with the MTM-HCC subtype. Early recurrence (within 2 years) and overall recurrence were evaluated by using Kaplan-Meier analysis. Multivariable Cox regression analysis was performed to determine predictors of early and overall recurrence. Results One hundred fifty-two patients (median age, 64 years; interquartile range, 56-72 years; 126 men) with 152 HCCs were evaluated. Twenty-six of the 152 HCCs (17%) were MTM-HCCs. LASSO-penalized logistic regression analysis identified substantial necrosis, high serum α-fetoprotein (AFP) level (>100 ng/mL), and Barcelona Clinic Liver Cancer (BCLC) stage B or C as independent features associated with MTM-HCCs. At multivariable analysis, substantial necrosis (odds ratio = 32; 95% confidence interval [CI] = 8.9, 114; P < .001), high serum AFP level (odds ratio = 4.4; 95% CI = 1.3, 16; P = .02), and BCLC stage B or C (odds ratio = 4.2; 95% CI = 1.2, 15; P = .03) were independent predictors of MTM-HCC subtype. Substantial necrosis helped identify 65% (17 of 26; 95% CI: 44%, 83%) of MTM-HCCs (sensitivity) with a specificity of 93% (117 of 126; 95% CI: 87%, 97%). In adjusted models, only the presence of satellite nodules was independently associated with both early (hazard ratio = 3.7; 95% CI: 1.5, 9.4; P = .006) and overall (hazard ratio = 3.0; 95% CI: 1.3, 7.2; P = .01) tumor recurrence. Conclusion At multiphase contrast-enhanced MRI, substantial necrosis helped identify macrotrabecular-massive hepatocellular carcinoma subtype with high specificity. © RSNA, 2020.

Primary leiomyosarcoma of the liver: Two new cases and a systematic review.

Primary hepatic leiomyosarcoma (PHL) is a rare malignant tumor, which originates from smooth muscles. Clinical presentation and imaging features are non-specific and can mimick the most frequent primary liver tumors namely hepatocellular carcinoma and intrahepatic cholangiocarcinoma. We report here two cases of PHL including one from the portal vein. The literature was searched for studies reporting cases of PHL reported from 2011 and 2019. The two patients were operated with R0 resection. Diagnosis of PHL was confirmed by histopathological and immunohistochemical examinations. Surgery remains the mainstay of the management of PHL. R0 resection is the main prognostic factor. Our literature search identified 16 additional cases from 12 reports. Preoperative diagnosis of PHL needs a high degree of suspicion due to atypical clinical presentation and non-specific imaging features. Surgery is the mainstay of the management of PHL. R0 resection is the main prognostic factor.

Severe, non specific symptoms in non-typhoidal Salmonella infections in adult patients with sickle cell disease: a retrospective multicentre study.

BACKGROUND: Non-typhoidal salmonellosis (NTS) often occurs in children with sickle-cell disease (SCD) and remains a significant cause of mortality in developing countries. However, there is lack of reports on the clinical presentation, outcome and complications of NTS in adults with SCD. METHODS: We performed a chart review between 2006 and 2016 of adults SCD diagnosed with NTS in 3 referral centers monitoring approximately 3500 SCD adults. RESULTS: Twenty-three episodes of NTS were diagnosed among 22 SCD adults. Diagnosis was challenging: 65% (n = 15/23) of patients presented with vaso-occlusive crisis (VOC) and 30% had no fever. Isolated serotypes were: ser. Enteritidis (n = 8), ser. Typhimurium (n = 6), others (n = 3). We identified two patterns of infections: (1) bacteremic NTS (n = 15) with (n = 9) or without secondary foci of infections (n = 6); (2) non-bacteremic NTS with extra-intestinal foci of infection (n = 8), including primary bones/joints infections (n = 5). Half of patients with osteo-articular localization (n = 6/13) had a previous history of osteonecrosis (n = 2) or osteomyelitis (n = 4) at the same site. Morbidity was high, 6 patients (26%) were admitted to the intensive care unit, 14 patients (61%) required RBC transfusion for VOC. Half of the episodes (n = 12) required surgery (n = 10) or interventional radiology (n = 2) to control the infection. One patient presented a relapse of NTS bacteraemia one year after the first episode. CONCLUSIONS: Besides bloodstream infections, clinical presentation of NTS in adults with SCD is non-specific at admission. A triad including bacteraemia, secondary focis of infection and bone localizations was observed in 30% of cases.

Quantitative correlation between uptake of Gd-BOPTA on hepatobiliary phase and tumor molecular features in patients with benign hepatocellular lesions.

PURPOSE: The purpose of our study was to correlate the quantitative analysis of benign hepatocellular tumor uptake on delayed hepatobiliary phase (HBP) imaging with the quantitative level of OATP expression. METHODS: This single-center retrospective study, which took place between September 2009 and March 2015, included 20 consecutive patients with a proven pathologic and immunohistochemical (IHC) diagnosis of FNH or HCA, including quantification of the OATP expression. The patients underwent Gd-BOPTA-enhancement MRI, including an HBP. The analysis of HBP uptake was performed using the liver-to-lesion contrast enhancement ratio (LLCER). Mean LLCER and OATP expressions were compared between FNH and HCA, and the expression of OATP was correlated with the LLCER value. RESULTS: Of the 23 benign hepatocellular tumors, 9 (39%) were FNH and 14 (61%) were HCA, including 6 inflammatory, 2 HNF1a inactivated, 3 ß-catenin-mutated and 3 unclassified HCAs. On HBP, 100% of the FNH appeared hyper- or isointense, and 79% of the adenomas appeared hypointense. The mean OATP expression of FNH (46.67 ± 26.58%) was significantly higher than that of HCA (22.14 ± 30.74%) (p = 0.0273), and the mean LLCER of FNH (10.66 ± 7.403%) was significantly higher than that of HCA (-13.5 ± 12.25%) (p < 0.0001). The mean LLCER of ß-catenin-mutated HCA was significantly higher than that of other HCAs (p = 0.011). Significant correlation was found between the OATP expression and LLCER values (r = 0.661; p = 0.001). CONCLUSION: In benign hepatocellular tumors, the quantitative analysis of hepatobiliary contrast agent uptake on HBP is correlated with the level of OATP expression and could be used as an imaging biomarker of the molecular background of HCA and FNH. KEY POINTS: • Gd-BOPTA uptake on HBP correlates with the OATP level in benign hepatocellular tumors • FNH and ß-catenin-mutated HCA showed an increased lesion-to-liver contrast enhancement ratio (LLCER) • Increased LLCER may be explained by activation of the Wnt ß-catenin pathway.

Positron emission tomography/computed tomography with 18F-fluorocholine improve tumor staging and treatment allocation in patients with hepatocellular carcinoma.

BACKGROUND & AIMS: Hepatocellular carcinoma (HCC) staging according to the Barcelona Clinical Liver Cancer (BCLC) classification is based on conventional imaging. The aim of our study was to assess the impact of dual-tracer 18F-fluorocholine and 18F-fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) on tumor staging and treatment allocation. METHODS: A total of 192 dual-tracer PET/CT scans (18F-fluorocholine and 18F-fluorodeoxyglucose PET/CT) were performed in 177 patients with HCC. BCLC staging and treatment proposal were retrospectively collected based on conventional imaging, along with any new lesions detected, and changes in BCLC classification or treatment allocation based on dual-tracer PET/CT. RESULTS: Patients were primarily men (87.5%) with cirrhosis (71%) due to alcohol ±â€¯non-alcoholic steatohepatitis (26%), viral infection (62%) or unknown causes (12%). Among 122 patients with PET/CT performed for staging, BCLC stage based on conventional imaging was 0/A in 61 patients (50%), B in 32 patients (26%) and C in 29 patients (24%). Dual-tracer PET/CT detected new lesions in 26 patients (21%), upgraded BCLC staging in 14 (11%) and modified treatment strategy in 17 (14%). In addition, dual-tracer PET/CT modified the final treatment in 4/9 (44%) patients with unexplained elevation of alpha-fetoprotein (AFP), 10/25 patients (40%) with doubtful lesions on conventional imaging and 3/36 patients (8%) waiting for liver transplantation without active HCC after tumor response following bridging therapy. CONCLUSION: When used for HCC staging, dual-tracer PET/CT enabled BCLC upgrading and treatment modification in 11% and 14% of patients, respectively. Dual-tracer PET/CT might also be useful in specific situations (an unexplained rise in AFP, doubtful lesions or pre-transplant evaluation of patients without active HCC). LAY SUMMARY: Using a combination of tracers 18F-fluorocholine and 18F-fluorodeoxyglucose when performing positron emission tomography/computed tomography (PET/CT), often called a PET scan, helps to identify new tumor lesions in patients with hepatocellular carcinoma. This technique enabled staging modification of patients' tumors and led to changes in treatment allocation in certain patients.

Differentiating focal nodular hyperplasia from hepatocellular adenoma: Is hepatobiliary phase MRI (HBP-MRI) using linear gadolinium chelates always useful?

PURPOSE: To assess the value of Hepatobiliary phase MRI (HPB-MRI) to differentiate FNH and HCA, and evaluate its impact on diagnostic accuracy, diagnostic confidence, inter-observer variability, and patient clinical management. METHODS: Forty-nine patients referred for Gd-BOPTA-enhanced MRI were retrospectively included in this IRB-approved study, with a total of 119 lesions-90 FNH and 29 HCA. Two observers separately assessed in 2 distinct randomized reading sessions the performance of MRI with (HBP-MRI) or without (conventional MRI) the use of HBP images. Each lesion was ranked with a 5-point scale (from 1 Typical FNH to 5 Certainly not a FNH). Sensitivity, specificity, overall accuracy, and inter-observer agreement for the differentiation of FNH from HCA were calculated and compared between conventional and HBP-MRI. RESULTS: Both sensitivity (respective values of 38.9% and 97.8%), overall accuracy (respective values of 53.8% and 98.3%), and inter-observer agreement (respective values of Kappa 0.56 and 0.88) were significantly higher using HBP-MRI than with conventional MRI, with unchanged specificity (100%). The sensitivity of conventional MRI for the diagnosis of FNH was significantly lower in lesions ≤ 3 cm (20% vs. 88%). Overall, HBP could have changed lesion management in 59/119 cases (49.5%), including 53 FNH and 6 HCA with no impact in 60/119 lesions (50.5%) including all 35 lesions classified as scores 1 and 2 for the diagnosis of FNH. CONCLUSIONS: The clinical impact of HBP-MRI is mostly important for smaller than 3-cm FNH, and more limited in larger FNH lesions as well as for HCA diagnosis for which conventional MRI is already accurate. The use of extracellular contrast agents upfront could limit the required use of linear HBP contrast agents for benign hepatocellular lesion characterization. On HBP, all FNH appeared hypointense compared to adjacent liver while close to 97% of HCA appeared hypointense.

Can dual-energy CT replace perfusion CT for the functional evaluation of advanced hepatocellular carcinoma?

OBJECTIVES: To determine the degree of relationship between iodine concentrations derived from dual-energy CT (DECT) and perfusion CT parameters in patients with advanced HCC under treatment. METHODS: In this single-centre IRB approved study, 16 patients with advanced HCC treated with sorafenib or radioembolization who underwent concurrent dynamic perfusion CT and multiphase DECT using a single source, fast kV switching DECT scanner were included. Written informed consent was obtained for all patients. HCC late-arterial and portal iodine concentrations, blood flow (BF)-related and blood volume (BV)-related perfusion parameters maps were calculated. Mixed-effects models of the relationship between iodine concentrations and perfusion parameters were computed. An adjusted p value (Bonferroni method) < 0.05 was considered significant. RESULTS: Mean HCC late-arterial and portal iodine concentrations were 22.7±12.7 mg/mL and 18.7±8.3 mg/mL, respectively. Late-arterial iodine concentration was significantly related to BV (mixed-effects model F statistic (F)=28.52, p<0.0001), arterial BF (aBF, F=17.62, p<0.0001), hepatic perfusion index (F=28.24, p<0.0001), positive enhancement integral (PEI, F=66.75, p<0.0001) and mean slope of increase (F=32.96, p<0.0001), while portal-venous iodine concentration was mainly related to BV (F=29.68, p<0.0001) and PEI (F=66.75, p<0.0001). CONCLUSIONS: In advanced HCC lesions, DECT-derived late-arterial iodine concentration is strongly related to both aBF and BV, while portal iodine concentration mainly reflects BV, offering DECT the ability to evaluate both morphological and perfusion changes. KEY POINTS: • Late-arterial iodine concentration is highly related to arterial BF and BV. • Portal iodine concentration mainly reflects tumour blood volume. • Dual-energy CT offers significantly decreased radiation dose compared with perfusion CT.

Correction to: Differentiating focal nodular hyperplasia from hepatocellular adenoma: Is hepatobiliary phase MRI (HBP-MRI) using linear gadolinium chelates always useful?

The original version of this article unfortunately contained a mistake. There was an error in the last sentence of the summary and the last sentence of the discussion. It should read as "On HBP, all FNH appeared hyper- or iso-intense compared to adjacent liver while close to 97% of HCA appeared hypointense".

Impact of hepatobiliary phase liver MRI versus Contrast-Enhanced Ultrasound after an inconclusive extracellular gadolinium-based contrast-enhanced MRI for the diagnosis of benign hepatocellular tumors.

PURPOSE: To compare the added values of hepatobiliary phase (HBP) MRI and contrast-enhanced ultrasound (CEUS) in addition to inconclusive extracellular gadolinium-based contrast-enhanced MRI (CE-MRI) to characterize benign hepatocellular tumors (BHT). METHODS: Eighty-three BHT-46 focal nodular hyperplasia (FNH) and 37 hepatocellular adenomas (HCA)-with inconclusive CE-MRI in 54 patients (43 women and 11 men, mean age 42 years old ± 14.8) were retrospectively analyzed. All patients underwent both HBP-MRI and CEUS. Two radiologists independently reviewed 2 sets of images, SET-1: CE-MRI and HBP-MRI; SET-2: CE-MRI and CEUS, and classified lesions as "definite FNH," "possible FNH," or "definitely not FNH." Sensitivity (Se) and specificity (Spe) were compared between the two sets; subgroup analyses according to the lesion's size were performed. RESULTS: Regardless of lesion size, the respective Se and Spe of both datasets were not statistically different (95.7 and 100% vs. 76.1 and 94.6% for set-1 and -2 respectively; p = 0.18). For lesions larger than 35 mm, although both sets had similar specificity (100%), sensitivity was higher for SET-1 (100% vs. 40%); p = 0.04. Tumor classifications using SET-1 and SET-2 could have changed patient management in 35/54 (64.8%) and 33/54 (61.1%) of all patients, respectively. CONCLUSIONS: HBP-MRI or CEUS should be performed after an inconclusive CE-MRI. Both can change patient management by avoiding unnecessary biopsy or surveillance. The use of HBP-MRI should be advocated over CEUS in larger (>35 mm) lesions.

Functional imaging of hepatocellular carcinoma using diffusion-weighted MRI and (18)F-FDG PET/CT in patients on waiting-list for liver transplantation.

BACKGROUND: To compare the apparent diffusion coefficient (ADC) on diffusion-weighted imaging (DWI) with the standardized uptake values (SUV) measured by(18)F-FDG-PET/CT in naïve hepatocellular carcinoma (HCC) nodules, and to determine whether these markers are associated with tumours at high-risk of aggressiveness. METHODS: From 2007 to 2010, all patients with HCC on the waiting list for liver transplantation and who underwent both FDG-PET/CT and 1.5-T DWI-MRI (b values: 0, 200, 400, and 800 s/mm(2)) were included in this institutional review board-approved retrospective study. Tumour size, tumour ADC, tumour-to-liver ADC ratio (ADCT/L), maximal tumour SUV and tumour-to-liver SUV ratio (SUVT/L) were measured and compared to serum alpha-fetoprotein (AFP) levels, tumour size and differentiation grade on explanted specimens. RESULTS: A total of 37 HCC nodules in 28 patients were available for correlation between MRI and PET/CT, 7 of which (in 7 patients) showed a SUVT/L > 1.15. We did not find any correlation between tumour ADC or ADCT/L and tumour SUV or SUVT/L. To note, SUVT/L was positively correlated with AFP levels (R = 0.95, P ≤ 0.0001), while ADCT/L was not (P = 0.73). Twenty-four patients (with 32 nodules) underwent liver transplantation. In this subgroup, an increased SUVT/L ratio was associated with larger tumours (average size, 32 ± 14 mm; range, 18-60 mm; P < 0.0001) and with poor differentiation on pathology (grades 3 and 4; P = 0.04), while ADCT/L was neither associated with tumour size or differentiation grade. CONCLUSIONS: ADC and SUV measures in HCC nodules are not correlated. SUVT/L ratio correlates with AFP levels, tumour size and poor differentiation, and should probably be integrated as a co-variable in a predictive outcome model of patients on the waiting-list for liver transplantation.

Differentiation of focal nodular hyperplasia from hepatocellular adenoma: Role of the quantitative analysis of gadobenate dimeglumine-enhanced hepatobiliary phase MRI.

PURPOSE: To determine the value of quantitative analysis of the hepatobiliary phase (HBP) in gadobenate dimeglumine (Gd-BOPTA)-enhanced magnetic resonance imaging (MRI) to differentiate focal nodular hyperplasia (FNH) from hepatocellular adenoma (HCA). MATERIALS AND METHODS: Thirty-eight patients bearing 67 lesions (40 FNH; 27 HCA) were retrospectively included in this Institutional Review Board-approved study. The same volumetric interpolated breath-hold examination (VIBE) T1 -weighted sequences were performed before and after contrast injection on a 1.5T MRI, with HBP images acquired with a mean delay of 80 minutes (range 60-120 min). After a visual assessment of lesions enhancement (qualitative HBP analysis), the HBP signal intensity ratio (SIR) and the lesion-to-liver contrast enhancement ratio (LLCER) were calculated for each lesion by two observers (Mann-Whitney test). The sensitivities, specificities (receiver operating characteristic [ROC] curve analysis) and interobserver correlation (intraclass coefficient, ICC) of quantitative HBP analysis were determined. RESULTS: All FNH and 44.4% of HCA appeared hyper- or isointense relative to the adjacent liver on qualitative HBP analysis. The mean SIR (P < 0.01) and LLCER (P < 0.0001) of FNH were significantly higher than that of HCA. The area under the ROC curve for the differentiation of FNH from HCA with LLCER was 0.98 for both observers. With a cutoff value of -0.3%-observer 1 with highest experience- LLCER assessment provided respective sensitivity and specificity values of 100% and 96.2% for the differentiation of FNH from HCA. The ICC was 0.7 for SIR measurements and 0.8 for LLCER measurements. CONCLUSION: Quantitative LLCER assessment allows an accurate differentiation of FNH from HCA, even in hyper- or isointense HCA on HBP images.

Whole-Body Diffusion-weighted Imaging in Hodgkin Lymphoma and Diffuse Large B-Cell Lymphoma.

Whole-body imaging, in particular molecular imaging with fluorine 18 ((18)F)-fluorodeoxyglucose (FDG) positron emission tomography (PET), is essential to management of lymphoma. The assessment of disease extent provided by use of whole-body imaging is mandatory for planning appropriate treatment and determining patient prognosis. Assessment of treatment response allows clinicians to tailor the treatment strategy during therapy if necessary and to document complete remission at the end of treatment. Because of rapid technical developments, such as echo-planar sequences, parallel imaging, multichannel phased-array surface coils, respiratory gating, and moving examination tables, whole-body diffusion-weighted (DW) magnetic resonance (MR) imaging that reflects cell density is now feasible in routine clinical practice. Whole-body DW MR imaging allows anatomic assessment as well as functional and quantitative evaluation of tumor sites by calculation of the apparent diffusion coefficient (ADC). Because of their high cellularity and high nucleus-to-cytoplasm ratio, lymphomatous lesions have low ADC values and appear hypointense on ADC maps. As a result, whole-body DW MR imaging with ADC mapping has become a promising tool for lymphoma staging and treatment response assessment. The authors review their 4 years of experience with 1.5-T and 3-T whole-body DW MR imaging used with (18)F-FDG PET/computed tomography at baseline, interim, and end of treatment in patients with Hodgkin lymphoma and diffuse large B-cell lymphoma and discuss the spectrum of imaging findings and potential pitfalls, limitations, and challenges associated with whole-body DW MR imaging in these patients.