112,056 research outputs found
Dose-saving in hepatic CT perfusion by shortening the unenhanced stage of the examinations
No full textAbstract:
Purpose: The high radiation dose delivered to patients in CT perfusion (CTp) examinations often prevents the use of CTp. This study investigates the unenhanced phase of hepatic CTp to find the minimum baseline needed to compute reliable perfusion values, thus minimizing the radiation dose delivered.
Methods and Materials: 64 patients with colorectal cancer, with liver free of known diseases, underwent hepatic axial CTp examination, with acquisition (every 1s during the first 30s, every 3s after, 66s scan duration, 42 samples) starting with contrast agent injection. Considering the single compartment dual-input model, regions of interest (ROIs) were drawn for each patient on aorta, portal vein, and liver. Voxel-based blood flow (BF) values computed during first-pass phase using the entire sequence were compared (repeated ANOVA, p-value≤0.05) with those attained progressively disregarding the first unenhanced samples. Mean BF and percentage variations, dose length product (DLP) and effective dose (ED) were computed for each dataset.
Results: Mean BF variations of maximum 1, 2, and 5mL/min/100g were observed in at least one examination by excluding 1, 7 (p=0.96), and 9 (p=0.1) data points, respectively. BF variations became statistically significant after that 10, or more, unenhanced samples were excluded, although perfusion maps remained highly correlated. For each sampling saved, the overall DLP and ED decreased by 2.38%.
Conclusion: Starting the acquisition after 7 or 9 seconds from contrast medium injection yields a dose reduction of about 17% and 21%, respectively. This achievement would reduce the dose, without losing information, and thus could contribute to develop CTp indications
CT perfusion maps of liver computed with different methods match
No full textPurpose: To achieve accurate information regarding the reproducibility of Computed Tomography perfusion (CTp), by comparing perfusion parameters computed using different independent CTp algorithms.
Methods and Materials: 49 patients with colorectal cancer and normal liver underwent axial CTp examinations at diagnosis. Blood flow (BF) values were computed on selected Regions of Interest (ROI) assuming a dual-input one-compartment model, using three different methods: maximum slope, deconvolution and the Materne model. After removing unreliable BF values, the perfusion maps were compared visually and correlation analyses between maps were performed (high correlations only are considered, when R2≥0.95).
Results: In all the examinations, most of CT perfusion maps show a perfect match, for both high- and low-perfused regions, preserving the details. For some examinations, the Materne model tends to make the transitions between differently perfused regions sharper. All correlations had R2≥0.90, four of them with R2<0.95, and 45 examinations were finally considered. 23 of them showed R2=0.99 and five only had R2<0.97. It is worth remarking that a marked visual correspondence also exists for maps with R2<0.95.
Conclusion: The excellent match between the perfusion maps achieved proves that the different algorithms can yield comparable results, useful for visual evaluations of local perfusion. Moreover, the very good correlations between BF values obtained with computational methods that are independent from each other improve the reliability of voxel-based perfusion values, this taking a step forward to the reproducibility of the CTp technique
Is right hepatectomy for liver living donation really comparable to right hepatectomy for benign liver lesions?
No full textIntroduction: Right hepatectomy (RH) for adult to adult living liver donation
(LD) remains risky despite major progress in the last 10 years. In order to
elucidate factors explaining this lower tolerance of a standardized procedure
we prospectively studied the outcome of patients (pts) who underwent a RH
for benign lesions (BL) in comparison with RH for LD.
Materials and methods: From 2001 we studied prospectively the pre- and
post-operative data, including volumetric variations of 26 RH for BL. This
group was matched with 26 LD which underwent a RH in the same period.
The two groups (BL vs LD) were similar for age (43±11 vs 46±11 years),
sex and BMI (25±4 vs 23±3). All pts have the same pre- and post-operative
assessment (preoperative CT scan with volumetric measurements and study
of coagulation profi le, biological tests every day until POD 7, including an
abdominal CT scan on POD 7).
Results: The comparison of the two groups (BL vs LD) showed that operation
duration was longer in LD group (320±76 vs 382±65 min) (p=0.004). The
blood loss was similar (623±260 vs 590±350 mL). Postoperative biochemical
data showed that total serum bilirubin was signifi cantly higher in LD group
in POD 2, 3, 5 and 8. Morbidity classifi ed with the Clavien’s system was
similar in both groups 38% vs 42% p=ns. The mortality was nil. After
subtraction of the tumor’s volume (mean 421±530 cc) in the BL group the
total liver volume was similar in both groups (1438±226 vs 1460 ± 318 cc)
but the left remnant liver volume was higher in the BL group (650±216 vs
455±152 cc) (p<0.001) representing 35±7% in BL group vs 31±7% in LD
group (p=0.03). The ratio remnant weight/body weight was higher in BL pts
(1±0.32 vs 0.7±0.23) (p<0.001). At POD 7 the left remnant liver was similar
in the two groups (947 vs 862 cc) demonstrating a regeneration rate of 57%
in BL group as compared to 84% in LD group (p=0.009).
Conclusions: This study demonstrates that RH for LD is not comparable to
the same procedure in pts with BL. The left liver which is smaller in LD group
acquires the same volume at day 7 refl ecting a higher process of regeneration.
These results showing that in LD an important deprivation of liver volume
restored by a signifi cant and sudden regeneration in the fi rst postoperative
week may be the background promoting fatal complications
Imaging diagnosis and staging of hepatocellular carcinoma
No full textDespite the incremental technological advances in cross-sectional imaging techniques [ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI)], there is still some concern that the imaging technology available today is inadequate for appropriate prioritization for liver transplantation (LT) because it cannot provide a sufficiently accurate diagnosis of hepatocellular carcinoma (HCC) on a per-nodule basis or sufficiently accurate disease staging on a per-patient basis. In a recent study, a retrospective analysis of data from the United Network for Organ Sharing (which oversees solid organ transplantation in the United States) compared preoperative findings by cross-sectional imaging with postoperative explant pathology findings; in comparison with the pathological stages of the explanted livers, imaging was found to have underestimated or overestimated the tumor burden in approximately one-fourth of the cases.1 One might speculate that this finding not only is due to the inherent shortcomings of the cross-sectional imaging techniques that are generally available for the liver but also reflects significant differences in the technical specifications of scanner hardware and software, imaging protocols, and interpretive expertise, the lack of standardization of the language used in imaging reports, and the absence of widely accepted diagnostic criteria.
Here we discuss possible pathways to consensus positions on the following issues:
1The minimal technical requirements for US, CT, and MRI.2The minimal requirements for operator expertise.3The standardization of imaging reports.4The classification of nodules on the imaging workup.5The staging of HCC.6The standardization of the evaluation of the results of locoregional therapy (LRT).7The standardization of surveillance for an early HCC diagnosis in patients listed for LT
Is right hepatectomy for liver living donation really comparable to right hepatectomy for benign liver lesions?
No full textUTILITÀ DELLA TC NELLA DIAGNOSI DELLA FISTOLA PANCREATICA DOPO DUODENOCEFALOPANCREASECTOMIA IN PAZIENTI CON SOFT PANCREAS
No full textImaging of Hepatic Focal Nodular Hyperplasia: Pictorial Review and Diagnostic Strategy
No full textFocal nodular hyperplasia (FNH) is the second most common benign solid liver lesion after hemangioma, occurring more frequently in young women. The prime differential diagnoses include hepatocellular adenoma, hepatocellular carcinoma, and hypervascular metastasis. As the management of FNH is typically conservative, imaging plays a key role in diagnostic pathway, and misdiagnosis may have a major clinical effect. In this article, we describe the ultrasound, computed tomography, and magnetic resonance imaging features of FNH, underlining the importance of typical radiological features that allow a specific noninvasive diagnosis. We present a large spectrum of a typical imaging findings that FNH may present and discuss the up-to-date diagnostic strategy
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