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.

Transhepatic endovascular repair for portal vein haemorrhage.

BACKGROUND: Post-surgical bleeding of the main portal vein (PV) is a rare event but difficult to manage surgically. Among the different options of treatment, endovascular stenting of the PV can be considered. We reported two cases of stent-graft placement in PV with subsequent closure of the portal vein access with two percutaneous closure devices deployed simultaneously. CASES PRESENTATION: The first patient was a 43 years-old woman affected with a pseudoaneurysm of the extrahepatic PV, occurred after a duodenocephalopancreasectomy performed for a neuroendocrine tumour of the pancreatic isthmus. The second patient was a 54 years-old man suffering from multiple episodes of bleeding after liver transplantation, due to a PV fissure. In both cases, a stent graft was placed into the portal system, between the PV and the superior mesenteric vein through a right trans-hepatic access to the portal system. In both cases, a final control showed patency of the mesenteric vein and PV and no endoleak detection. At the end of the procedure, two percutaneous closure devices were loaded, to close the transhepatic portal access. In one case, one of the devices did not work and the entry point was managed with a single device, without further complications. No bleeding was seen though the entry point nor at the US examination performed right after the procedure. After procedure, patients were prescribed with low-molecular weight heparin (LMWH) and kept under surveillance. For both patients, CT scan performed within 24h after the procedure, showed a patent stent-graft and no evidence of any venous portal ischemia. The first patient was then transferred to another hospital, to continue observation and medical management. The second one underwent 2 months of hospitalization, during which he developed a pancreatic fistula and mild renal insufficiency. Then, he left the hospital to its native Country to continue his medical. CONCLUSION: PV stent-graft placement seems a feasible option to manage portal bleeding. Trans-hepatic access is an easy and fast approach. The trans-hepatic portal accesses may be successfully managed with the deployment of percutaneous closure devices.

Recurrent acute pancreatitis caused by combined gastric and pancreatic duplications: value of preoperative CT and MRCP and conservative surgery.

We present a series of patients with recurrent acute pancreatitis caused by a duplicated pancreatic head connected to a gastric duplication and successfully treated by conservative surgery. This retrospective study included consecutive adult patients referred to our institution for recurrent acute pancreatitis. All patients underwent a preoperative non-invasive imaging examination including contrast-enhanced computed tomography and magnetic resonance cholangiopancreatography (MRCP). The final diagnosis of this developmental anomaly was based on surgical and pathological examinations. The four patients in this study had the same typical imaging pattern including a duplicated duct. There was no recurrent acute pancreatitis after surgical treatment, which involved atypical resection of the duplicated pancreatic head and segmental gastric resection, without a Whipple procedure. The discovery of an accessory pancreatic head with a duct terminating in a cyst identified on MRCP in a patient with recurrent acute pancreatitis could suggest this rare and surgically treatable cause of acute pancreatitis.

CBCT-Based Image Guidance for Percutaneous Access: Electromagnetic Navigation Versus 3D Image Fusion with Fluoroscopy Versus Combination of Both Technologies-A Phantom Study.

PURPOSE: We set out to compare three types of three-dimensional CBCT-based imaging guidance modalities in a phantom study: image fusion with fluoroscopy (IF), electromagnetic navigation (EMN) and the association of both technologies (CEMNIF). MATERIALS AND METHODS: Four targets with a median diameter of 11 mm [first quartile (Q1): 10; third quartile (Q3): 12] with acute angle access (z-axis < 45°) and four targets of 10 mm [8-15] with large angle access (z-axis > 45°) were defined on an abdominal phantom (CIRS, Meditest, Tabuteau, France). Acute angle access targets were punctured using IF, EMN or CEMNIF and large angle access targets with EMN by four operators with various experiences. Efficacy (target reached), accuracy (distance between needle tip and target center), procedure time, radiation exposure and reproducibility were explored and compared. RESULTS: All targets were reached (100% efficacy) by all operators. For targets with acute angle access, procedure times (EMN: 265 s [236-360], IF: 292 s [260-345], CEMNIF: 320 s [240-333]) and accuracy (EMN: 3 mm [2-5], IF: 2 mm [1-3], CEMNIF: 3 mm [2-4]) were similar. Radiation exposure (EMN: 0; IF: 708 mGy.cm2 [599-1128]; CEMNIF: 51 mGy.cm2 [15-150]; p < 0.001) was significantly higher with IF than with CEMNIF and EMN. For targets with large angle access, procedure times (EMN: 345 s [259-457], CEMNIF: 425 s [340-473]; p = 0.01) and radiation exposure (EMN: 0, CEMIF: 159 mGy.cm2 [39-316]; p < 0.001) were significantly lower with EMN but with lower accuracy (EMN: 4 mm [4-6] and CEMNIF: 4 mm [3, 4]; p = 0.01). The operator's experience did not impact the tested parameters regardless of the technique. CONCLUSION: In this phantom study, EMN was not limited to acute angle targets. Efficacy and accuracy of puncture for acute angle access targets with EMN, IF or CEMNIF were similar. CEMNIF is more accurate for large angle access targets at the cost of a slightly higher procedure time and radiation exposure.

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.

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.

Use of Model-Based Iterative Reconstruction (MBIR) in reduced-dose CT for routine follow-up of patients with malignant lymphoma: dose savings, image quality and phantom study.

OBJECTIVES: To evaluate both in vivo and in phantom studies, dose reduction, and image quality of body CT reconstructed with model-based iterative reconstruction (MBIR), performed during patient follow-ups for lymphoma. METHODS: This study included 40 patients (mean age 49 years) with lymphoma. All underwent reduced-dose CT during follow-up, reconstructed using MBIR or 50 % advanced statistical iterative reconstruction (ASIR). All had previously undergone a standard dose CT with filtered back projection (FBP) reconstruction. The volume CT dose index (CTDIvol), the density measures in liver, spleen, fat, air, and muscle, and the image quality (noise and signal to noise ratio, SNR) (ANOVA) observed using standard or reduced-dose CT were compared both in patients and a phantom study (Catphan 600) (Kruskal Wallis). RESULTS: The CTDIvol was decreased on reduced-dose body CT (4.06 mGy vs. 15.64 mGy p < 0.0001). SNR was higher in reduced-dose CT reconstructed with MBIR than in 50 % ASIR or than standard dose CT with FBP (patients, p ≤ 0.01; phantoms, p = 0.003). Low contrast detectability and spatial resolution in phantoms were not altered on MBIR-reconstructed CT (p ≥ 0.11). CONCLUSION: Reduced-dose CT with MBIR reconstruction can decrease radiation dose delivered to patients with lymphoma, while keeping an image quality similar to that obtained on standard-dose CT. KEY POINTS: • In lymphoma patients, CT dose reduction is a major concern. • Reduced-dose body CT provides a fourfold radiation dose reduction. • Optimized CT reconstruction techniques (MBIR) can maintain image quality.