CT of the abdomen: degree and quality of enhancement obtained with two concentrations of the same iodinated contrast medium with fixed iodine delivery rate and total iodine load.

OBJECTIVES: to compare vascular and parenchymal enhancement in abdominal computed tomography (CT) using two iodine concentrations (370 vs 300mgI/mL) of the same contrast medium (CM) molecule (iopromide), using fixed iodine delivery rate (IDR, 1.2gI/s) and total iodine load (630mgI/kg). METHODS: 144 patients were randomized into two groups: group A receiving iopromide 370 and group B receiving iopromide 300. Attenuation values (AV) were measured in correspondence to key anatomical structures on different phases and compared between groups with parametrical tests. Qualitative analysis was also performed. Peak injection pressure and local discomfort at the site of injection (pain and warmth) were registered. RESULTS: mean AV of abdominal aorta in late arterial phase were 300.32±59.76 for group A and 298.2±59.14 for group B (p=0.8); mean AV of portal vein in portal phase were 190.5±29.92 for group A and 192.91±24.12 for group B (p=0.6). Mean AV of liver parenchyma in portal phase were 124.73±18.22 for group A and 125.11±15.7 for group B (p=0.9); mean AV of liver at equilibrium were 85.11±7.75 for group A and 85.41±8.09 for group B (p=0.8). Qualitative analysis did not show significant differences between groups (p>0.05). Median peak injection pressure was lower in group B (93psi, 76-172) than in group A (115psi, 88-288, p<0.0001), while discomfort at injection site was not significantly different (p>0.05). CONCLUSIONS: with fixed IDR and total iodine load, comparable quantitative and qualitative enhancement can be achieved with different concentrations of the same CM. Peak injection pressure increases using CM with higher iodine concentration.

Real-time elastography in the assessment of liver fibrosis: a review of qualitative and semi-quantitative methods for elastogram analysis.

Despite its invasiveness, liver biopsy is still considered the gold standard for the assessment of hepatic fibrosis. Non-invasive ultrasound-based techniques are increasingly employed to assess parenchymal stiffness and the progression of chronic diffuse liver diseases. Real-time elastography is a rapidly evolving technique that can reveal the elastic properties of tissues. This review examines qualitative and semi-quantitative methods developed for analysis of real-time liver elastograms, to estimate parenchymal stiffness and, indirectly, the stage of fibrosis. Qualitative analysis is the most immediate approach for elastogram analysis, but this method increases intra- and inter-observer variability, which is seen as a major limitation of real-time elastography. Semi-quantitative methods include analysis of the histogram derived from color-coded maps, as well as calculation of the elastic ratio and fibrosis index.

Value of fused 18F-Choline-PET/MRI to evaluate prostate cancer relapse in patients showing biochemical recurrence after EBRT: preliminary results.

PURPOSE: We compared the accuracy of (18)F-Choline-PET/MRI with that of multiparametric MRI (mMRI), (18)F-Choline-PET/CT, (18)F-Fluoride-PET/CT, and contrast-enhanced CT (CeCT) in detecting relapse in patients with suspected relapse of prostate cancer (PC) after external beam radiotherapy (EBRT). We assessed the association between standard uptake value (SUV) and apparent diffusion coefficient (ADC). METHODS: We evaluated 21 patients with biochemical relapse after EBRT. Patients underwent (18)F-Choline-PET/contrast-enhanced (Ce)CT, (18)F-Fluoride-PET/CT, and mMRI. Imaging coregistration of PET and mMRI was performed. RESULTS: (18)F-Choline-PET/MRI was positive in 18/21 patients, with a detection rate (DR) of 86%. DRs of (18)F-Choline-PET/CT, CeCT, and mMRI were 76%, 43%, and 81%, respectively. In terms of DR the only significant difference was between (18)F-Choline-PET/MRI and CeCT. On lesion-based analysis, the accuracy of (18)F-Choline-PET/MRI, (18)F-Choline-PET/CT, CeCT, and mMRI was 99%, 95%, 70%, and 85%, respectively. Accuracy, sensitivity, and NPV of (18)F-Choline-PET/MRI were significantly higher than those of both mMRI and CeCT. On whole-body assessment of bone metastases, the sensitivity of (18)F-Choline-PET/CT and (18)F-Fluoride-PET/CT was significantly higher than that of CeCT. Regarding local and lymph node relapse, we found a significant inverse correlation between ADC and SUV-max. CONCLUSION: (18)F-Choline-PET/MRI is a promising technique in detecting PC relapse.