Optimum imaging of chronic pancreatitis

Chronic pancreatitis is an inflammatory process of the pancreas characterized by progressive parenchyma destruction, resulting in pain and exocrine and endocrine insufficiency. In the advanced stages the diagnosis by imaging is usually straightforward, while in the early phases of the disease there can be a paucity of findings at imaging, thus making an early diagnosis challenging. Different imaging modalities can have a role in the initial diagnosis and in the longitudinal follow-up of patients affected by chronic pancreatitis, also enabling to assess the complications of the disease. Radiography, Ultrasonography, CT and MRI can all provide morphological information, and MRI with the administration of secretin can also provide functional information. The use of an appropriate technique is fundamental for optimizing the examination to the clinical question.

Impact of visceral obesity and sarcobesity on surgical outcomes and recovery after laparoscopic resection for colorectal cancer

BACKGROUND & AIMS

Studies analyzing the impact of visceral fat excess on surgical outcomes after resection for colorectal cancer (CRC) have yielded conflicting results. Visceral obesity (VO) and sarcobesity (SO) have been recently addressed as risk factors for poor short-term results while no data are available for recovery goals after surgery. No data are available on the protective effect of ERAS in VO and SO patients. The aim of this study was to assess clinical implications of computed tomography (CT) assessed VO and SO on surgical and recovery outcomes after minimally invasive resection for CRC before and after ERAS protocol implementation.

METHODS

Visceral adipose tissue (VAT) and skeletal muscle area (SMA) were retrospectively assessed using pre-operative CT studies of 261 patients who underwent laparoscopic resection for CRC between January 2012 and April 2019; ERAS protocol was adopted in 160 patients operated on after March 2014. Patients' surgical and recovery outcomes were compared according to BMI categories, VO and SO which was defined using the VAT/SMA ratio (Sarcobesity Index). Predictive factors for poor surgical and recovery outcomes were evaluated by univariate and multivariate analyses.

RESULTS

Of the 261 patients, 12.6% were BMI obese while 68.6% presented visceral obesity. BMI was not associated to any of the outcomes considered. No differences in intra-operative results were found except for a lower number of retrieved lymph nodes both in VO and SO patients. While VO showed no impact on post-operative course, SO resulted an independent risk factor for cardiac complications and prolonged post-operative ileus (PPOI) at logistic regression analysis. Furthermore, sarcobese patients showed delayed recovery after surgery. Patients enrolled in the ERAS protocol showed improved recovery outcomes for both VO and SO groups, although ERAS did not result to be a protective factor for cardiac complications and PPOI.

CONCLUSIONS

A high Sarcobesity Index is a risk factor for developing cardiac complications and PPOI after laparoscopic resection for CRC. A reduced number of lymph nodes retrieved is associated to VO and SO. These conditions should then be considered in clinical practice for the risk of down staging the N stage. Effect of VO and SO on recovery items after surgery should be further investigated. ERAS protocol application should be implemented to improve recovery outcomes in VO and SO patients undergoing laparoscopic colorectal resection.

Correlation between appearance of the retroportal fat plane at preoperative CT and pathology findings in resected adenocarcinoma of the pancreatic head

AIM

To correlate the appearance of the retroportal fat plane at preoperative computed tomography (CT) and the pathology findings in resected adenocarcinoma of the pancreatic head (PDAC).

MATERIAL AND METHODS

Forty-eight patients with resected PDAC of the pancreatic head were included (24 men, 24 women, mean age 63 years, median BMI 24.1). All patients underwent CT <30 days before surgery. The state of the retroperitoneal resection margin and the presence of lymphatic or perineural invasion were obtained from pathology reports. CT images were reviewed independently by two radiologists for assessment of the retroportal fat plane and graded in two categories (clear/effaced). Inter-reader discrepancies were solved in consensus. Interobserver agreement was calculated and Fisher's test was used to assess the correlation between CT and pathology findings. Visceral fat areas were measured and correlated with CT findings.

RESULTS

A clear retroportal fat plane was significantly associated with a negative retroperitoneal margin at pathology with 100% specificity and PPV (p=0.0001). No association was observed between the appearance of the fat plane at CT and the presence of lymphatic or perineural invasion (p=ns). Interobserver agreement for retroportal fat plane evaluation was good (0.741). False-positive cases had a significantly lower visceral fat area than the correctly classified patients (p=0.0480).

CONCLUSIONS

A clear retroportal fat plane is significantly associated with negative retroperitoneal resection margins at pathology. The lack of visceral adipose tissue can lead to overestimation of retroportal fat plane involvement at preoperative CT.

Iodine Extravasation Quantification on Dual-Energy CT of the Brain Performed after Mechanical Thrombectomy for Acute Ischemic Stroke Can Predict Hemorrhagic Complications

BACKGROUND AND PURPOSE

Intracerebral hemorrhage represents a potentially severe complication of revascularization of acute ischemic stroke. The aim of our study was to assess the capability of iodine extravasation quantification on dual-energy CT performed immediately after mechanical thrombectomy to predict hemorrhagic complications.

MATERIALS AND METHODS

Because this was a retrospective study, the need for informed consent was waived. Eighty-five consecutive patients who underwent brain dual-energy CT immediately after mechanical thrombectomy for acute ischemic stroke between August 2013 and January 2017 were included. Two radiologists independently evaluated dual-energy CT images for the presence of parenchymal hyperdensity, iodine extravasation, and hemorrhage. Maximum iodine concentration was measured. Follow-up CT examinations performed until patient discharge were reviewed for intracerebral hemorrhage development. The correlation between dual-energy CT parameters and intracerebral hemorrhage development was analyzed by the Mann-Whitney U test and Fisher exact test. Receiver operating characteristic curves were generated for continuous variables.

RESULTS

Thirteen of 85 patients (15.3%) developed hemorrhage. On postoperative dual-energy CT, parenchymal hyperdensities and iodine extravasation were present in 100% of the patients who developed intracerebral hemorrhage and in 56.3% of the patients who did not (P = .002 for both). Signs of bleeding were present in 35.7% of the patients who developed intracerebral hemorrhage and in none of the patients who did not (P < .001). Median maximum iodine concentration was 2.63 mg/mL in the patients who developed intracerebral hemorrhage and 1.4 mg/mL in the patients who did not (P < .001). Maximum iodine concentration showed an area under the curve of 0.89 for identifying patients developing intracerebral hemorrhage.

CONCLUSIONS

The presence of parenchymal hyperdensity with a maximum iodine concentration of >1.35 mg/mL may identify patients developing intracerebral hemorrhage with 100% sensitivity and 67.6% specificity.

Perfusion CT can predict tumoral grading of pancreatic adenocarcinoma

OBJECTIVES

To describe perfusion CT features of locally advanced pancreatic ductal adenocarcinoma and to evaluate correlation with tumor grading.

METHODS

Thirty-two patients with locally advanced pancreatic adenocarcinoma were included in this study. Lesions were evaluated by P-CT and biopsy after patient's informed consent. P-CT parameters have been assessed on a large single and on 6 small intratumoral ROIs. Values obtained have been compared and related to the tumor grading using Mann-Whitney U test. Sensibility, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy in predicting tumor grading have been calculated for cut-off values chosen by using ROC curves.

RESULTS

Out of 32 lesions, 12 were classified as low grade and 20 as high grade. A statistically significant difference between high and low grade neoplasms were demonstrated for PEI and BV parameters. PEI and BV cut-off values were respectively 17.8 HU and 14.8 ml/100g. PEI identified high grade neoplasms with a 65% sensitivity, 92% specificity, 93% PPV, 61% NPV and 75% accuracy. BV identified high grade neoplasms with a 80% sensitivity, 75% specificity, 84% PPV, 69% NPV, 78% accuracy. Considering both PEI and BV, P-CT identified high grade lesions with a 60% sensitivity, 100% specificity, 100% PPV, 60% NPV and 75% accuracy.

CONCLUSIONS

PEI and BV perfusion CT parameters proved their efficiency in identifying high grade pancreatic adenocarcinoma.

Pancreatic fat accumulation and its relationship with liver fat content and other fat depots in obese individuals

BACKGROUNDS AND AIMS

We assessed the associations between pancreatic fat accumulation and other fat compartments, including liver fat and visceral adipose tissue as well as insulin resistance and other metabolic abnormalities in obese individuals.

SUBJECTS AND METHODS

We studied 42 Caucasian adults with obesity [20 men and 22 women; mean body mass index (BMI) 35.2±4 kg/m(2)], who had no history of liver diseases or excessive alcohol consumption, in which subcutaneous, visceral, liver, and pancreatic fat contents were quantified by an in-opposed-phase magnetic resonance imaging (MRI) technique.

RESULTS

Compared with patients in the lower tertile (<5.6%, no.=15), those in the upper tertile of liver fat content had more visceral adipose tissue, greater insulin resistance and had higher values of BMI, blood pressure, triglycerides and lower HDL-cholesterol and adiponectin. Notably, pancreatic fat accumulation also significantly increased across tertiles of liver fat content. In univariate analysis, the strongest correlates of pancreatic fat were visceral and liver fat contents (r=0.80 and r=0.54, p<0.001- 0.0001, respectively). Pancreatic fat accumulation was also moderately associated with insulin resistance and other metabolic syndrome features. However, when adjusted for age, gender and visceral adipose tissue, the associations of pancreatic fat accumulation with liver fat and other metabolic abnormalities were no longer significant.

CONCLUSIONS

There are significant associations between pancreatic fat accumulation and liver fat content as well as insulin resistance and other metabolic abnormalities in obese, but otherwise healthy, individuals. However, these associations are largely mediated by the amount of visceral adipose tissue.

Effect of moderate weight loss on hepatic, pancreatic and visceral lipids in obese subjects

OBJECTIVE

To compare the effects of weight loss on visceral and subcutaneous abdominal fat, liver and pancreas lipid content and to test the effects of these changes on metabolic improvement observed after weight loss.

DESIGN

Weight-loss program designed to achieve a loss of 7-10% of the initial weight.

SUBJECTS

24 obese subjects (13 males and 11 females) with age ranging from 26 to 69 years and body mass index (BMI) 30.2-50.5 kg m(-2).

MEASUREMENTS

weight, BMI, waist circumference, body composition as assessed by dual-energy X-ray absorptiometry, metabolic variables, leptin, adiponectin, visceral and subcutaneous abdominal fat, liver and pancreas lipid content as assessed by magnetic resonance were evaluated before and after weight loss achieved by hypocaloric diet.

RESULTS

After a mean body weight decrease of 8.9%, BMI, waist circumference, fat mass, all metabolic variables, homeostasis model assessment of insulin resistance (HOMA), alanine amino transferase, gamma glutamyl transpeptidase, high-sensitivity C-reactive protein (hs-CRP) and leptin, but not adiponectin and high-density lipoprotein-cholesterol, significantly decreased (all P<0.01). Visceral and subcutaneos abdominal fat, liver and pancreas lipid content significantly decreased (all P<0.01). Percent changes in liver lipid content were greater (84.1±3%) than those in lipid pancreas content (42.3±29%) and visceral abdominal fat (31.9±15.6%). After weight loss, percentage of subjects with liver steatosis decreased from 75 to 12.5%. Insulin resistance improvement was predicted by changes in liver lipid content independently of changes in visceral fat, pancreas lipid content, systemic inflammation, leptin and gender.

CONCLUSION

Moderate weight loss determines significant decline in visceral abdominal fat, lipid content in liver and pancreas. Reduction of liver lipid content was greater than that of pancreas lipid content and visceral fat loss. Liver lipid content is the strongest predictor of insulin resistance improvement after weight loss.

Standardisation of liver MDCT by tracking liver parenchyma enhancement to trigger imaging

OBJECTIVE

To assess parenchymal bolus-triggering in terms of liver enhancement, lesion-to-liver conspicuity and inter-image variability across serial follow-up MDCTs.

METHODS

We reviewed MDCTs of 50 patients with hepatic metastases who had a baseline CT and two follow-up examinations. In 25 consecutive patients CT data acquisition was initiated by liver parenchyma triggering at a 50-HU enhancement threshold. In a matched control group, imaging was performed with an empirical delay of 65 s. CT attenuation values were assessed in vessels, liver parenchyma and metastasis. Target lesions were classified according to five enhancement patterns.

RESULTS

Compared with the control group, liver enhancement was significantly higher with parenchyma triggering (59.8 ± 7.6 HU vs. 48.8 ± 11.2 HU, P = 0.0002). The same was true for conspicuity (liver parenchyma - lesion attenuation) of hypo-enhancing lesions (72.2 ± 15.9 HU vs. 52.7 ± 19.4 HU, P = 0.0006). Liver triggering was associated with reduced variability for liver enhancement among different patients (P = 0.035) and across serial follow-up examinations in individual patients (P < 0.0001). The number of patients presenting with uniform lesion enhancement pattern across serial examinations was significantly higher in the triggered group (20 vs. 11; P = 0.018).

CONCLUSION

Liver parenchyma triggering provides superior lesion conspicuity and improves standardisation of image quality across follow-up examinations with greater uniformity of enhancement patterns.

KEY POINTS

Liver parenchyma tracking improves liver enhancement and lesion-to-liver conspicuity in abdominal CT. In serial CT studies this technique reduces variability of conspicuity and enhancement patterns. Higher liver-to-lesion conspicuity is a prerequisite for reliable detection of liver lesions. Stabilisation of enhancement permits more accurate follow-up of oncology patients.

Resectable pancreatic adenocarcinoma: is the enhancement pattern at contrast-enhanced ultrasonography a pre-operative prognostic factor?

The aim of our study was to determine whether the enhancement pattern of pancreatic adenocarcinoma at contrast-enhanced ultrasonography (CEUS) is related to patient prognosis after resection. CEUS of 42 resected adenocarcinomas were retrospectively reviewed. Tumors were divided into two groups: group A=poorly vascularized (presence of avascular areas) or group B=well vascularized (absence of avascular areas). All lesions were resected and underwent pathological examination assessing tumor differentiation as: undifferentiated (poorly differentiated) or differentiated (moderately and well differentiated). Mean vascular density (MVD) was also evaluated. CEUS enhancement and pathology were correlated (Spearman's test). Survival was analyzed with the Kaplan-Meier method. Multivariate analysis was performed with the Cox regression model. There were 30 differentiated and 12 undifferentiated adenocarcinomas at pathology. At CEUS, 10 lesions were poorly vascularized, whereas 32 lesions were well vascularized. Positive correlation was observed between CEUS groups and tumoral differentiation (rs=0.51; p=0.001) and between CEUS and MVD (rs=0.74; p<0.0001). Median survival in patients with group A vascularization at CEUS was significantly lower than in group B (p=0.015). Cox proportional hazard model revealed the presence of poorly vascularized tumor at CEUS (p=0.0001) as a predictor of higher mortality. In conclusion, CEUS enables accurate depiction of the vascularization of adenocarcinoma, with positive correlation to histology grade and MVD.