Giacomo Belli

Liver stiffness measurement predicts severe portal hypertension in patients with HCV‐related cirrhosis

Measurement of hepatic venous pressure gradient (HVPG) is a standard method for the assessment of portal pressure and correlates with the occurrence of its complications. Liver stiffness measurement (LSM) has been proposed as a noninvasive technique for the prediction of the complications of cirrhosis. In this study, we evaluated the ability of LSM to predict severe portal hypertension compared with that of HVPG in 61 consecutive patients with HCV‐related chronic liver disease. A strong relationship between LSM and HVPG measurements was found in the overall population (r = 0.81, P < 0.0001). However, although the correlation was excellent for HVPG values less than 10 or 12 mm Hg (r = 0.81, P = 0.0003 and r = 0.91, P < 0.0001, respectively), linear regression analysis was not optimal for HVPG values ≥10 mm Hg (r2 = 0.35, P < 0.0001) or ≥12 mm Hg (r2 = 0.17, P = 0.02). The AUROC for the prediction of HVPG ≥10 and ≥12 mm Hg were 0.99 and 0.92, respectively and at LSM cutoff values of 13.6 kPa and 17.6 kPa, sensitivity was 97% and 94%, respectively. In patients with cirrhosis, LSM positively correlated with the presence of esophageal varices (P = 0.002), although no correlation between LSM and esophageal varices size was detected. The area under the ROC for the prediction of EV was 0.76 and at a LSM cutoff value of 17.6 kPa sensitivity was 90%. Conclusion: LSM represents a non‐invasive tool for the identification of chronic liver disease patients with clinically significant or severe portal hypertension and could be employed for screening patients to be subjected to standard investigations including upper GI endoscopy and hemodynamic studies. (HEPATOLOGY 2007;45:1290–1297.)

MR-diffusion weighted imaging of healthy liver parenchyma: repeatability and reproducibility of apparent diffusion coefficient measurement.

To compare repeatability and reproducibility of four different methods of apparent diffusion coefficient (ADC) evaluation of liver parenchyma. In fact, repeatability and reproducibility assessment is mandatory in quantitative evaluations, however, these have not been accurately investigated in liver MR‐diffusion‐weighted studies.

Single-voxel long TE 1H-MR spectroscopy of the normal brainstem and cerebellum

To evaluate the feasibility of single voxel 1H‐MRS of the CNS structures contained in the posterior cranial fossa and to determine the distribution of the normal metabolite ratios, concentrations, and T2 relaxation times in the midbrain, pons, medulla, dentate nucleus and cerebellar vermis.

Risk-benefit analysis of X-ray exposure associated with lung cancer screening in the Italung-CT trial.

OBJECTIVE Prior analyses of X-ray exposures in lung cancer screening with CT considered the basic acquisition technique in single-detector scanners and the effects of a lifetime screening regimen, whereas the potential benefit in terms of lives saved was not addressed. MATERIALS AND METHODS We determined the total-body effective dose of different acquisition techniques for one single-detector and one MDCT scanner and made projections about the cumulative radiation exposure to smokers undergoing four annual CT examinations on the same scanners in the Italung-CT Trial. Combining these data with estimates of radiation-induced fatal cancer and of the benefit of screening, we calculated the risk-benefit ratio for participants in the trial, ex-smokers, and never-smokers. RESULTS The cumulative effective doses per 1,000 subjects were 3.3 Sv using an MDCT scanner and 5.8 or 7.1 Sv using a single-detector scanner. Potential fatal cancers associated with radiation exposure were 0.11 per 1,000 subjects for MDCT scanners and 0.20 or 0.24 for single-detector scanners, which is about 10-100 times lower than the number of expected lives saved by screening assuming a 20-30% lung cancer-specific mortality reduction in current smokers. They were, however, of similar magnitude to the lives saved by screening in never-smokers and former smokers assuming a 10% efficacy of screening. CONCLUSION MDCT is associated with lower radiation doses than single-detector CT technology. The risk of radiation dose in the Italung-CT Trial is compensated for by the expected benefit. CT screening for lung cancer should not be offered to never-smokers, whereas its recommendation in former smokers is debatable.

The Influence of Diffusion-and Relaxation-Related Factors on Signal Intensity : An Introductive Guide to Magnetic Resonance Diffusion-Weighted Imaging Studies

In magnetic resonance diffusion-weighted imaging, signal intensity is influenced simultaneously by temperature, diffusivity, b value, pseudodiffusion, macroscopic motion, and T2-weighted intensity value. The purpose of this pictorial essay is to discuss and exemplify the influence that such factors and the related modifications have on signal intensity. Apparent diffusion coefficient, shine-through and pseudodiffusion will also be examined to show how T2-weighted signal intensity value and nondiffusional intravoxel incoherent motion can affect the diffusion-weighted imaging.

Dose exposure in the ITALUNG trial of lung cancer screening with low-dose CT

Few data are available on the effective dose received by participants in lung cancer screening programmes with low-dose CT (LDCT). We report the collective effective dose delivered to 1406 current or former smokers enrolled in the ITALUNG trial who completed 4 annual LDCT examinations and related further investigations including follow-up LDCT, 2-[(18)F]flu-2-deoxy-d-glucose positron emission tomography (FDG-PET) or CT-guided fine needle aspiration biopsy (FNAB). Using the air CT dose index and Monte Carlo simulations on an anthropomorphic phantom, the whole-body effective dose associated with LDCT was determined for the eight CT scanners used in the trial. A value of 7 mSv was assigned to FDG-PET while the measured mean effective dose of CT-guided FNAB was 1.5 mSv. The mean collective effective dose in the 1406 subjects ranged between 8.75 and 9.36 Sv and the mean effective dose to the single subject over 4 years was between 6.2 and 6.8 mSv (range 1.7-21.5 mSv) according to the cranial-caudal length of the LDCT volume. 77.4% of the dose was owing to annual LDCT and 22.6% to further investigations. Considering the nominal risk coefficients for stochastic effects after exposure to low-dose radiation according to the National Radiological Protection Board, International Commission on Radiological Protection (ICRP) 60, ICRP103 and Biological Effects of Ionizing Radiation VII, the mean number of radiation-induced cancers ranged between 0.12 and 0.33 per 1000 subjects. The individual effective dose to participants in a 4-year lung cancer screening programme with annual LDCT is very low and about one-third of the effective dose that is associated with natural background radiation and diagnostic radiology in the same time period.

Impact of cerebrospinal fluid contamination on brain metabolites evaluation with 1H-MR spectroscopy: A single voxel study of the cerebellar vermis in patients with degenerative ataxias

To investigate the impact of cerebrospinal fluid (CSF) contamination on metabolite evaluation in the superior cerebellar vermis with single‐voxel 1H‐MRS in normal subjects and patients with degenerative ataxias.

Quality assurance multicenter comparison of different MR scanners for quantitative diffusion-weighted imaging

To propose a magnetic resonance imaging (MRI) quality assurance procedure that can be used for multicenter comparison of different MR scanners for quantitative diffusion‐weighted imaging (DWI).

Spirometric-gated computed tomography quantitative evaluation of lung emphysema in chronic obstructive pulmonary disease: A comparison of 3 techniques

Objective: To compare the quantitative assessment of pulmonary emphysema with spirometric-gated computed tomography (gated CT) using 3 different acquisition techniques and to determine if low-current spiral CT could be used effectively to quantitate emphysema. Methods: Eleven patients with chronic obstructive pulmonary disease (COPD) underwent gated CT and pulmonary function tests (PFTs). Spiral whole-lung 10-mm collimation acquisitions at standard (146 mAs) and low (43 mAs) current and sequential 3-slice 1-mm collimation high-resolution computed tomography (HRCT) acquisitions at standard current were obtained at 90% of the patient’s vital capacity. The mean lung density (MLD) and the pixel index (PI) derived from the 3 data sets were compared using one-way analysis of variance and correlated with PFTs using linear regression. Moreover, the radiation dose associated with each technique was measured. Results: The MLDs were not significantly different. The PIs calculated from the standard- and low-current spiral acquisitions were similar, and both were significantly different from that of HRCT. The MLDs correlated with the PFTs in standard-current spiral and HRCT but not in low-current spiral acquisitions, whereas the PIs correlated with the PFTs in all 3 techniques. High-resolution computed tomography implied the lowest dose (0.08 mSv) compared with low-current (1.2 mSv) and standard-current (4 mSv) spiral techniques. Conclusions: Low- and standard-dose spiral CT provides similar lung density data in COPD. The combination of low-dose whole-lung spiral CT and 3-slice HRCT represents the best compromise between the amount of information provided and radiation exposure to the patient and could be substituted for standard-dose spiral CT for quantitative evaluation of COPD.

Performance of Doppler ultrasound in the prediction of severe portal hypertension in hepatitis C virus‐related chronic liver disease

Purpose: To evaluate the correlation between hepatic vein pressure gradient measurement and Doppler ultrasonography (DUS) in patients with chronic liver disease (CLD).