Joint Deformable Image Registration and ADC Map Regularization: Application to DWI-Based Lymphoma Classification.

The Apparent Diffusion Coefficient (ADC) is considered an importantimaging biomarker contributing to the assessment of tissue microstructure and pathophy- siology. It is calculated from Diffusion-Weighted Magnetic Resonance Imaging (DWI) by means of a diffusion model, usually without considering any motion during image acquisition. We propose a method to improve the computation of the ADC by coping jointly with both motion artifacts in whole-body DWI (through group-wise registration) and possible instrumental noise in the diffusion model. The proposed deformable registration method yielded on average the lowest ADC reconstruction error on data with simulated motion and diffusion. Moreover, our approach was applied on whole-body diffusion weighted images obtained with five different b-values from a cohort of 38 patients with histologically confirmed lymphomas of three different types (Hodgkin, diffuse large B-cell lymphoma and follicular lymphoma). Evaluation on the real data showed that ADC-based features, extracted using our joint optimization approach classified lymphomas with an accuracy of approximately 78.6% (yielding a 11% increase in respect to the standard features extracted from unregistered diffusion-weighted images). Furthermore, the correlation between diffusion characteristics and histopathological findings was higher than any other previous approach of ADC computation.

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.

Quantification of Myocardial Enhancement on Cine-MRI: Diagnostic Value in Cardiac Amyloidosis.

RATIONALE AND OBJECTIVES: Diagnosis of cardiac amyloidosis (CA) on cardiac magnetic resonance (CMR) can be challenging and quantitative indexes are relevant to further characterize the myocardium. We hypothesize that the relative myocardial enhancement measured from pre and post contrast cine imaging provides diagnostic information for CA in the setting of left ventricular hypertrophy (LVH). MATERIALS AND METHODS: Patients with LVH referred to our center and control subjects with normal CMR were retrospectively included. Percentage of myocardial enhancement (percentage ME) was obtained from pre and post contrast (5 minutes) cine sequences. Post contrast myocardial T1 and LGE extent were also recorded. RESULTS: Twenty-one patients with CA, 25 patients with non-amyloid left ventricular myocardial hypertrophy (CH) and 20 controls with normal CMR were analyzed. Percentage ME was significantly higher in CA patients (200% (174-238)) than in CH patients (122% (88-151); p = 0.0001) and control patients (104% (90-149); p = 0.0001). Percentage ME was significantly correlated with the LGE extent (Rho Spearman coefficient = 0.66; p = 0.0001) and with the post contrast myocardial T1 (Rho Spearman coefficient = -0.61; p = 0.0001). With a cutoff value of 152%, the sensitivity and specificity of percentage ME for detection of CA were 90% and 80%, respectively. CONCLUSION: Percentage ME obtained from pre and post contrast cine imaging is correlated to LGE extent and myocardial T1 and may represent an additional diagnostic parameter to consider CA in patients with LVH.

Can power Doppler ultrasound of the entheses help in classifying recent axial spondyloarthritis? Data from the DESIR cohort.

Early diagnosis of axial spondyloarthritis (axSpA) remains a challenge due to the lack of specificity of clinical symptoms and variable prevalence of axial imaging findings permitting a definite diagnosis. Power Doppler ultrasonography (PDUS) of the entheses has demonstrated to be a potential useful tool for the classification and diagnostic management of early SpA independently of the phenotype. OBJECTIVES: To assess the classification value (sensitivity and specificity) of PDUS-defined enthesitis for identifying patients fulfilling Assessment of SpondyloArthritis international Society (ASAS) classification criteria for axSpA (ASAS+) in patients with recent inflammatory back pain (IBP) (the DESIR (DEvenir des Spondylarthropathies Indifférenciées Récentes) cohort). METHODS: Baseline PDUS was performed at eight entheseal sites, and PDUS enthesitis was defined by the presence of vascularisation at entheseal insertion. RESULTS: 402 patients from the DESIR cohort underwent a PDUS evaluation. PDUS enthesitis was detected in 58 (14.4%) patients of whom 40 (14.2%) belonged to the ASAS+ patients and 18 (17%) to the ASAS- patients. The sensitivity of PDUS enthesitis was 13.9% and the specificity was 83.5%, with a positive predictive value of 69% and 26.8% of negative predictive value for meeting ASAS criteria for axSpA. Of the 18 ASAS- patients with positive PDUS, 59% fulfilled Amor's criteria, 88% European Spondyloarthropathy Study Group criteria and 59% both. CONCLUSIONS: In a cohort of patients with recent IBP, the prevalence of PDUS enthesitis was low (14.4%); however, its specificity for classifying patients as axSpA according to ASAS criteria was high (83.5%). PDUS enthesitis might be of additional value for classifying as patients with axSpA IBP who do not fulfil ASAS criteria.

Myocardial native T2 measurement to differentiate light-chain and transthyretin cardiac amyloidosis and assess prognosis.

BACKGROUND: To assess the diagnostic and prognosis value of myocardial native T2 measurement in the distinction between Light-chain (AL) and Transthyretin (ATTR) cardiac amyloidosis (CA). METHODS: Forty-four patients with CA (24 AL; 20 ATTR) and 40 healthy subjects underwent 1.5 T cardiovascular magnetic resonance (CMR). They all underwent T1 and T2 mapping (modified Look-Locker inversion recovery), cine and late gadolinium enhancement (LGE) imaging. The Query Amyloid Late Enhancement (QALE) score, myocardial native T2, T1 and extra cellular volume fraction (ECV) were calculated for all patients. RESULTS: Of the 44 patients, 36 (82%) exhibited enhancement on LGE images. Mean QALE score of AL (7.9 ± 6) and ATTR (10.5 ± 5) patients were similar (p = 0.6). Myocardial native T2 was significantly (p < 0.0001) higher in AL (63.2 ± 4.7 ms) than in ATTR (56.2 ± 3.1 ms) patients, and both higher (p < 0.001) than healthy subjects (51.1 ± 3.1 ms). Myocardial native T2 was highly correlated with myocardial native T1 (Spearman's rho = 0.79; p < 0.001) and exhibited higher diagnostic performance than T1 to separate AL and ATTR patients: the area under curve (AUC) of T2 was 0.94 (95% CI: 0.86-1, p < 0.001) and the AUC of T1 was 0.77 (95% CI: 0.62-0.91, p = 0.03). Myocardial native T2 did not impact overall survival in patients (HR 1.03 (0.94-1.12); p = 0.53) in contrast to ECV that was the best predictor of outcome (HR 1.66 per 0.1 increase in ECV (1.24-2.22); p = 0.0006). CONCLUSIONS: Myocardial native T2 significantly is increased in CA, especially in AL patients in comparison to ATTR patients. Myocardial native T2 does not impact survival in CA patients in contrast to ECV that was the best predictor of outcome. TRIAL REGISTRATION: Trial Registration and unique number: CNIL cardio 1778041. Date of registration: 20 December 2012.

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.

Advanced Hepatocellular Carcinoma: Pretreatment Contrast-enhanced CT Texture Parameters as Predictive Biomarkers of Survival in Patients Treated with Sorafenib.

Purpose To determine whether texture features on pretreatment contrast material-enhanced computed tomographic (CT) images can help predict overall survival (OS) and time to progression (TTP) in patients with advanced hepatocellular carcinoma (HCC) treated with sorafenib. Materials and Methods This retrospective study included 92 patients with advanced HCC treated with sorafenib between January 2009 and April 2015 at two independent university hospitals. Sixty-four of the 92 patients (70%) (six women, 58 men; median age, 66 years) were included from institution 1 and constituted a training cohort; 28 patients (30%) (five women, 23 men; median age, 64 years) were included from institution 2 and constituted a validation cohort. Pretreatment CT texture analysis was performed on late arterial and portal venous phase HCC images. Mean gray-level intensity, entropy, kurtosis, skewness, and standard deviation values were derived from the pixel distribution histogram before and after spatial filtration at different anatomic scales ranging from fine to coarse texture. Lesion heterogeneity was also visually graded on a 4-point scale. Correlations between visual analysis and texture parameters were assessed with the Spearman rank correlation. Univariate Kaplan-Meier and multivariate Cox proportional hazards regression analyses were performed in the training cohort to identify independent predictors of OS and TTP. Their predictive capacity was tested on the validation cohort by using Kaplan-Meier analysis. Results Visual analysis of tumor heterogeneity correlated with entropy at both arterial (P = .012) and portal venous (P = .038) phases. Portal phase-derived entropy at fine (hazard ratio [HR], 5.08; P = .0033), medium (HR, 2.23; P = .019), and coarse (HR, 2.26; P = .0032) texture scales was identified as an independent predictor of OS and confirmed in the validation cohort (P < .05). The difference in median survival between patients in the validation cohort with entropy values below and above the identified threshold was 272 days (with fine texture) and 741 days (with medium and coarse textures). Arterial phase-derived texture parameters (P > .085) and visual analysis (P > .11) were not associated with changes in survival. Conclusion Pretreatment portal venous phase-derived tumor entropy may be a predictor of survival in patients with advanced HCC treated with sorafenib.

Myocardial iodine concentration measurement using dual-energy computed tomography for the diagnosis of cardiac amyloidosis: a pilot study.

OBJECTIVE: To measure myocardium iodine concentration (MIC) in patients with cardiac amyloidosis (CA) using dual-energy computed tomography (DECT). METHODS: Twenty-two patients with CA, 13 with non-amyloid hypertrophic cardiomyopathies (CH) and 10 control patients were explored with pre-contrast, arterial and 5-minute DECT acquisition (Iomeprol; 1.5 mL/kg). Inter-ventricular septum (IVS) thickness, blood pool iodine concentration (BPIC), MIC (mg/mL), iodine ratio and extra-cellular volume (ECV) were calculated. RESULTS: IVS thickness was significantly (p < 0.001) higher in CA (17 ± 4 mm) and CH (15 ± 3 mm) patients than in control patients (10 ± 1 mm). CA patients exhibited significantly (p < 0.001) higher 5-minute MIC [2.6 (2.3-3.1) mg/mL], 5-minute iodine ratio (0.88 ± 0.12) and ECV (0.56 ± 0.07) than CH [1.7 (1.4-2.2) mg/mL, 0.57 ± 0.07 and 0.36 ± 0.05, respectively] and control patients [1.9 (1.7-2.4) mg/mL, 0.58 ± 0.07 and 0.35 ± 0.04, respectively). CH and control patients exhibited similar values (p = 0.9). The area under the curve of 5-minute iodine ratio for the differential diagnosis of CA from CH patients was 0.99 (0.73-1.0; p = 0.001). With a threshold of 0.65, the sensitivity and specificity of 5-minute iodine ratio were 100% and 92%, respectively. CONCLUSION: Five-minute MIC and iodine ratio were increased in CA patients and exhibited best diagnosis performance to diagnose CA in comparison to other parameters. KEY POINT: • Dual-energy computed tomography can be used to detect cardiac amyloidosis • Five-minute myocardial iodine concentration and iodine ratio increase in cardiac amyloidosis • Among iodine parameters, 5-minute iodine ratio has the best diagnosis performance.

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.

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.

Whole-Body Diffusion-weighted MR Imaging of Iron Deposits in Hodgkin, Follicular, and Diffuse Large B-Cell Lymphoma.

Purpose To analyze the frequency and distribution of low-signal-intensity regions (LSIRs) in lymphoma lesions and to compare these to fluorodeoxyglucose (FDG) uptake and biologic markers of inflammation. Materials and Methods The authors analyzed 61 untreated patients with a bulky lymphoma (at least one tumor mass ≥7 cm in diameter). When a LSIR within tumor lesions was detected on diffusion-weighted images obtained with a b value of 50 sec/mm2, a T2-weighted gradient-echo (GRE) sequence was performed and calcifications were searched for with computed tomography (CT). In two patients, Perls staining was performed on tissue samples from the LSIR. LSIRs were compared with biologic inflammatory parameters and baseline FDG positon emission tomography (PET)/CT parameters (maximum standardized uptake value [SUVmax], total metabolic tumor volume [TMTV]). Results LSIRs were detected in 22 patients and corresponded to signal void on GRE images; one LSIR was due to calcifications, and three LSIRS were due to a recent biopsy. In 18 patients, LSIRs appeared to be related to focal iron deposits; this was proven with Perls staining in two patients. The LSIRs presumed to be due to iron deposits were found mostly in patients with aggressive lymphoma (nine of 26 patients with Hodgkin lymphoma and eight of 20 patients with diffuse large B-cell lymphoma vs one of 15 patients with follicular lymphoma; P = .047) and with advanced stage disease (15 of 18 patients). LSIRS were observed in spleen (n = 14), liver (n = 3), and nodal (n = 8) lesions and corresponded to foci FDG uptake, with mean SUVmax of 9.8, 6.7, and 16.2, respectively. These patients had significantly higher serum levels of C-reactive protein, α1-globulin, and α2-globulin and more frequently had microcytic anemia than those without such deposits (P = .0072, P = .003, P = .0068, and P < .0001, respectively). They also had a significantly higher TMTV (P = .0055) and higher levels of spleen involvement (P < .0001). Conclusion LSIRs due to focal iron deposits are detected in lymphoma lesions and are associated with a more pronounced biologic inflammatory syndrome. © RSNA, 2017 Online supplemental material is available for this article.

B1 artifact reduction in abdominal DCE-MRI using kT -points: First clinical assessment of dynamic RF shimming at 3T.

BACKGROUND: The excitation inhomogeneity artifact occurring at 3T in the abdomen can lead to dramatic loss of signal and contrast, thereby hampering diagnosis. PURPOSE: To assess excitation homogeneity and image quality achieved by nonselective prototypical kT -points pulses, compared to tailored static RF shimming, in clinical routine on a commercial dual-transmit scanner. STUDY TYPE: Retrospective study with Institutional Review Board approval; informed consent was waived. POPULATION: Fifty consecutive patients referred for liver MRI at a single hospital. FIELD STRENGTH/SEQUENCE: 3D breath-hold dynamic contrast-enhanced (DCE) MRI at 3T. ASSESSMENT: Flip angle homogeneity was estimated via numerical simulation based on measured static and RF field maps. In all, 20 of the 50 patients underwent DCE-MRI while a pulse designer was present. The effect of RF shimming and kT -point pulses could be compared by repeating the acquisition with each transmit scheme before injection and in the late phase. Signal homogeneity, T1 contrast, enhancement quality, structure details, and global image quality were assessed on a 4-level scale (0 to 3) by two radiologists. STATISTICAL TESTS: Means were compared using Wilcoxon signed-rank tests. RESULTS: Normalized root mean square flip angle error was significantly reduced with kT -points compared to static RF shimming (8.5% ± 1.5% [mean ± standard deviation, SD] vs. 20.4% ± 9.8%; P < 0.0001). The worst case (heavy ascites) led to 13.0% (kT -points) vs. 54.9% (RF shimming). Global image quality was significantly higher for kT -points (2.3 ± 0.5 vs. 1.9 ± 0.6; P = 0.008). One subject's examination was judged unusable with RF shimming by one reader, none with kT -points. 85% of kT -points acquisitions were graded at least 2/3, and only 55% for static RF shimming. DATA CONCLUSION: KT -points reduce excitation inhomogeneity quantitatively and qualitatively, especially in patients with ascites and prone to B1 shading. LEVEL OF EVIDENCE: 1 Technical Efficacy: Stage 1 J. Magn. Reson. Imaging 2018;47:1562-1571.

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".

Three-dimensional Image Fusion Guidance for Transjugular Intrahepatic Portosystemic Shunt Placement.

INTRODUCTION: To assess the safety, feasibility and effectiveness of image fusion guidance with pre-procedural portal phase computed tomography with intraprocedural fluoroscopy for transjugular intrahepatic portosystemic shunt (TIPS) placement. MATERIALS AND METHODS: All consecutive cirrhotic patients presenting at our interventional unit for TIPS creation from January 2015 to January 2016 were prospectively enrolled. Procedures were performed under general anesthesia in an interventional suite equipped with flat panel detector, cone-beam computed tomography (CBCT) and image fusion technique. All TIPSs were placed under image fusion guidance. After hepatic vein catheterization, an unenhanced CBCT acquisition was performed and co-registered with the pre-procedural portal phase CT images. A virtual path between hepatic vein and portal branch was made using the virtual needle path trajectory software. Subsequently, the 3D virtual path was overlaid on 2D fluoroscopy for guidance during portal branch cannulation. Safety, feasibility, effectiveness and per-procedural data were evaluated. RESULTS: Sixteen patients (12 males; median age 56 years) were included. Procedures were technically feasible in 15 of the 16 patients (94%). One procedure was aborted due to hepatic vein catheterization failure related to severe liver distortion. No periprocedural complications occurred within 48 h of the procedure. The median dose-area product was 91 Gy cm2, fluoroscopy time 15 min, procedure time 40 min and contrast media consumption 65 mL. Clinical benefit of the TIPS placement was observed in nine patients (56%). CONCLUSION: This study suggests that 3D image fusion guidance for TIPS is feasible, safe and effective. By identifying virtual needle path, CBCT enables real-time multiplanar guidance and may facilitate TIPS placement.

Report of the 6th International Workshop on PET in lymphoma.

Two hundred and ten nuclear medicine physicians, radiologists, and hematologists from 26 countries attended the 6th International Workshop on Positron Emission Tomography (PET) in Lymphoma and Myeloma held in Menton, France, in September 2016. The meeting was under the auspices of the European Lymphoma Institute (ELI), the European Association of Nuclear Medicine (EANM) the Lymphoma Study Association (LYSA), the Italian Foundation on Lymphoma (FIL) and the Carnot Institute for Lymphoma (CALYM). Forty scientific posters were presented. For the first time, specialists in the field of multiple myeloma (MM) were involved in the expert session. The aim was to establish from the experience of Italian and French studies new guidelines of FDG-PET/CT reporting for myeloma staging and restaging. The meeting dedicated an entire session to MM imaging followed by a session on the role of PET in Peripheral T cell Lymphoma. An entire session addressed the issues of Deauville scale particularly for end treatment assessment and the challenging consequences of immunomodulatory treatments on PET reporting. A specific session presented the potential role of baseline metabolic tumor measurement to predict outcome and identify different risk categories and the main results obtained in different lymphoma entities were described. Whether it could replace clinical staging has been extensively discussed. The more recent results obtained in the H10 trial have been presented and compared to the published data in early stage Hodgkin lymphoma. Finally, the ongoing studies using PET for guiding therapeutic strategies have been reported by the various lymphoma cooperative groups that participated to the meeting.

Magnetic Resonance Imaging Assessment of Kidney Oxygenation and Perfusion During Sickle Cell Vaso-occlusive Crises.

BACKGROUND: Our understanding of the pathophysiologic processes underlying sickle cell nephropathy remains incomplete. We performed a pilot study to investigate the potential value of magnetic resonance imaging (MRI) for the assessment of kidney oxygenation and detection of potential changes to tissue perfusion and cellular integrity during a vaso-occlusive crisis. STUDY DESIGN: A case-control study. SETTING & PARTICIPANTS: 10 homozygous patients with sickle cell disease (SCD), without kidney disease (based on estimated glomerular filtration rate and albuminuria), underwent renal MRI during a vaso-occlusive crisis episode. The imaging data obtained were compared with those for a second MRI performed at steady state (median, 56 [IQR, 37-72] days after the vaso-occlusive crisis MRI). The control group consisted of 10 apparently healthy individuals. MEASUREMENTS: Deoxyhemoglobin level assessed by R2* value was calculated using the blood oxygen level-dependent technique. The intravoxel incoherent motion diffusion-weighted imaging technique was used to calculate D, D*, and F parameters. RESULTS: Median medullary R2* values on steady-state MRI were significantly higher for patients with SCD than for controls (P=0.01) and did not change significantly during the vaso-occlusive crisis. No significant differences in median cortical R2* values were observed. Both cellular integrity (D) and local perfusion (D* and F) were significantly altered in medullary and cortical areas during vaso-occlusive crises in comparison to steady state in patients with SCD. These parameters did not differ significantly between patients with SCD assessed at steady state and the control group. LIMITATIONS: Small sample size, estimation of glomerular filtration rate according to CKD-EPI creatinine equation without adjustment for race. CONCLUSIONS: Deoxyhemoglobin levels in the medullary area are higher in patients with SCD, during vaso-occlusive crises and at steady state, than in controls. Alterations to the tissue perfusion and cellular integrity of renal parenchyma are a common finding during vaso-occlusive crises that provide additional evidence that a vaso-occlusive crisis may be associated with subclinical kidney injury detectable on MRI.

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.

What is the reliability of non-trained investigators in recognising structural MRI lesions of sacroiliac joints in patients with recent inflammatory back pain? Results of the DESIR cohort.

OBJECTIVE: The objective of this study was to evaluate the reliability of recognising structural lesions on MRI (erosions, fatty lesions, ankylosis) of the sacroiliac joints (MRI-SIJ) in clinical practice compared to a central reading in patients with a possible recent axial spondyloarthritis (axSpA). METHODS: Patients aged 18-50 years, with recent (<3 years) and chronic (≥3 months) inflammatory back pain, suggestive of axSpA were included in the DEvenir des Spondyloarthrites Indifférenciées Récentes (DESIR) cohort. MRI-SIJ structural lesions were scored by non-trained local readers, and by two trained central readers. Local readers scored each SIJ as normal, doubtful or definite lesions. Central readers scored separately each type of lesion. The central reading (mean of the two central readers' scores) was the external standard. Agreement (κ) was calculated first between local (3 definitions of a positive MRI-SIJ) and central readings (9 definitions), and then between the two central readers. RESULTS: 664/708 patients with complete available images were included. Agreements between local and central readings were overall 'fair', except when considering at least 2 or 3 fatty lesions and at least 3 erosions and/or fatty lesions where agreement was 'moderate'. Agreement between central readers was similar. MRI-SIJ was positive for 52.6% of patients according to central reading (at least 1 structural lesion) and for 35.4% of patients according to local reading (at least unilateral 'doubtful' or 'definite' structural lesions). CONCLUSIONS: Agreement on a positive structural MRI-SIJ was fair to moderate between local and central readings, as well as between central readers. The reliability improved when fatty lesions were considered. TRIAL REGISTRATION NUMBER: NCTO 164 8907.

Metabolic Tumour Burden Measured by 18F-FDG PET/CT Predicts Malignant Transformation in Patients with Neurofibromatosis Type-1.

BACKGROUND: To investigate the diagnostic and prognostic performances of 18F-FDG PET/CT measures of metabolic tumour burden in patients with neurofibromatosis type-1 (NF1), suspect of malignant transformation. METHODS: This retrospective study included 49 patients (15-60 years old, 30 women) with a diagnosis of NF1, followed in our Reference Centre for Rare Neuromuscular Diseases, who presented clinical signs of tumour progression (pain, neurological deficit, tumour growth). Quantitative metabolic parameters were measured on 149 tumoral targets, using semi-automatic software and the best cut off values to predict transformation was assessed by Receiver Operating Characteristics (ROC) analysis. Prognostic value of PET/CT metabolic parameters was assessed by Kaplan-Meier estimates of overall survival. RESULTS: Lesions were histologically documented in 40 patients: a sarcomatous transformation was found in 16, a dysplastic neurofibroma (NF) in 7, and a benign NF in 17; in the remaining 9 patients, a minimal follow-up of 12 mo (median 59 mo) confirmed the absence of transformation. The optimal cut off values for detection of malignant transformation were, in decreasing order of area under the ROC curves, a tumour-to-liver (T/L) ratio >2.5, SUVmax > 4.5, total lesion glycolysis (TLG) > 377, total metabolic tumour volume (TMTV) > 88 cm3, and heterogeneity index (HIsuv) > 1.69. The best prognostic marker was the TLG: the 4-y estimates of survival were 97% [95% CI, 90% - 100%] in patients with TLG ≤ 377 vs. 27% [95% CI, 5% - 49%] in patients with TLG > 377 (P < 0.0001; χ2 27.85; hazard ratio 13.27 [95% CI, 3.72-47.35]). T/L ratio, SUVmax and TMTV demonstrated slightly lower performance to predict survival, with χ2 ranging 14.41-19.12. The HIsuv index was not predictive of survival. CONCLUSION: Our study demonstrates that TLG and TMTV, as PET/CT measures of metabolic tumour burden, may be used clinically to identify sarcomatous transformation in patients with NF1 and predict overall survival, with a higher specificity for the TLG. Conventional measures such as the SUVmax, and T/L ratio also demonstrate high prognostic value.

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.