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Scientific Session On-demand channel 6 Abdominal vascular imaging Bile Ducts and Gallbladder Computer Tomography GI Tract - Oesophagus Image Guided Therapy Liver - Diffuse Liver Disease Magnetic Resonance Oncology Quantitative Imaging

SS 14 - Technical advances in gastro-intestinal and abdominal imaging (ID 83)

Moderators
Date
Fri, 22.05.2020
Time
11:00 - 12:30
Topic
Abdominal vascular imaging, Bile Ducts and Gallbladder, Computer Tomography, GI Tract - Oesophagus, Image Guided Therapy, Liver - Diffuse Liver Disease, Magnetic Resonance, Oncology, Quantitative Imaging

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On-demand

SS 14.1 - Opportunistic screening for osteoporosis by abdominal CT in a British population

Presentation Number
SS 14.1
Speakers:
Session Name
SS 14 - Technical advances in gastro-intestinal and abdominal imaging
Channel
On-demand channel 6

Abstract

Purpose

It has previously been shown that CT scans performed for other indications can be used to identify patients with osteoporosis. This has not yet been tested in a British population. We sought to evaluate the use of vertebral CT attenuation measures for predicting osteoporosis in a British cohort, using dual-energy X-ray absorptiometry (DEXA) as a reference standard.

Material and methods

Patients who underwent abdominal CT in 2018, and concomitantly underwent DEXA within a six-month interval, were retrospectively included. CT attenuation values in Hounsfield units (HU) were measured on the sagittal reconstruction by the placement of a region-of-interest at the central portion of the L1 vertebral body, and then compared to their corresponding DEXA score. Receiver operating characteristic (ROC) curves were generated to evaluate the performance of a logistic regression model, and to determine sensitivity and specificity thresholds.

Results

536 patients (394 females, mean age 65.8) were included, of which 174 had DEXA-defined osteoporosis. L1 attenuation measures were significantly different (p<0.01) between the three DEXA-defined groups of osteoporosis (118HU), osteopenia (143HU) and normal bone density (178HU). The area under the ROC curve was 0.74 (95% CI 0.69 – 0.78). A threshold of 169HU was 90% sensitive and a threshold of 104HU was 90% specific for diagnosing osteoporosis.

Conclusion

Routine abdominal CT can be used to opportunistically screen for osteoporosis without additional cost or radiation exposure. The thresholds identified in this study are comparable with previous studies in other populations. We recommend radiologists engage with primary care and rheumatology providers to determine appropriate cut-off values for further investigation.

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On-demand Top 20 Presentation

SS 14.3 - Image quality analysis of two different techniques for multi-arterial phase dynamic study in liver MRI with gadoxetic acid: results of a monocentric prospective randomised observational study

Presentation Number
SS 14.3
Speakers:
Session Name
SS 14 - Technical advances in gastro-intestinal and abdominal imaging
Channel
On-demand channel 6

Abstract

Purpose

To evaluate the technical performance of two different multi-arterial phase techniques in liver MRI.

Material and methods

From February 2017 to December 2018, we enrolled 273 randomized patients who underwent liver MRI using CAIPIRINHA (Controlled Aliasing in Parallel Imaging Results in Higher Acceleration) or TWIST-VIBE (Siemens, Erlangen, Germany) before and after the administration of gadoxetic acid (Gd-EOB-DTPA) (dose: 0.025ml/kg; injection rate: 1ml/s). The acquisition time of both sequences is superimposable (<20s). The protocol includes 3 arterial phases (6.5s each for CAIPIRINHA; 9s, 4s, 4s for TWIST-VIBE) with the possibility of reducing them depending on the patient's fitness level. The images were evaluated by two dedicated radiologists, who quantify Gibbs artifacts and noise (present/absent), breath artifacts and general quality of images using a score from 1 to 5 (1 “non-diagnostic” and 5 “absence of artifacts”/“optimal exam quality”).

Results

There is no statistically significant difference between the demographic data of CAIPIRINHA and TWIST-VIBE cohort. CAIPIRINHA has always a better quality score (p>0.02) but we could not obtain a three-arterial-phase study in all patients (3%). TWIST-VIBE has worse Gibbs and breath score artifact but better noise score.

Conclusion

CAIPIRINHA always allows to obtain a diagnostic image, rarely at the expense of the three arterial phases (0% with one phase, 3% with two phases, 97% with three phases). TWIST-VIBE always allows to obtain three arterial phases. CAIPIRINHA better tolerates artifacts at the detriment of image resolution; TWIST-VIBE has a better signal-to-noise ratio but greater susceptibility to artifacts. The choice of one or the other must take into account patient's compliance and physical characteristics.

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On-demand

SS 14.4 - Mapping of the liver function: impact of MR field strength on T1 reduction rate

Presentation Number
SS 14.4
Speakers:
Session Name
SS 14 - Technical advances in gastro-intestinal and abdominal imaging
Channel
On-demand channel 6

Abstract

Purpose

To determine whether T1 reduction rate is dependent on field strength in patients with and without liver cirrhosis.

Material and methods

85 consecutive gadoxetic acid (Gd-EOB-DTPA) liver MRI scans with available T1 mapping pre- and post-contrast administration in the equilibrium phase were analyzed between September 2018 and January 2019. 44 exams were performed on a 1.5T system and 41 exams on a 3T system. Each of these two groups was then divided into patients with and without liver cirrhosis. T1 reduction rates were calculated as (native T1 – post-contrast T1)/native T1. Groups were compared using a Mann-Whitney U test.

Results

At 1.5T 23 patients had cirrhosis, while 21 patients had no cirrhosis. At 3T 17 patients had cirrhosis, while 24 patients had no cirrhosis. At both 3T and 1.5T T1 reduction rate discriminated between patients with and without cirrhosis (p=0.001 and p>0.001). T1 reduction rates did not differ significantly between 3T and 1.5T in patients with cirrhosis (median 60% vs. 59%; p=0.991) and without cirrhosis (median 75% vs. 75%; p=0.787).

Conclusion

This study shows that T1 reduction rate is comparable between 3T and 1.5T and may discriminate patients with and without liver cirrhosis as an imaging surrogate to map liver function.

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SS 14.5 - Effect of scanner selection and tube parameters on CT texture analysis: evaluation on ex vivo pig liver

Presentation Number
SS 14.5
Speakers:
Session Name
SS 14 - Technical advances in gastro-intestinal and abdominal imaging
Channel
On-demand channel 6

Abstract

Purpose

To assess if tube parameters and scanner type affect the results of CT texture analysis parameters performed on pig liver parenchyma.

Material and methods

We performed 15 consecutive CT scans of a pig liver, using two different scanners (Brilliance64 and Brilliance6, Philips). Ten scans were performed on Brilliance64 using every possible combination of tube current (25, 50, 100, 150 or 200mAs) and voltage (80 or 120kVp), whereas five scans were performed on Brilliance6 at 120kVp varying only the tube current. CT texture analysis was performed on each scan with LifeX software (http://www.lifexsoft.org) by drawing 4 volumetric ROIs. Texture features of each scan were compared using Welch’s ANOVA test and Brown-Forsythe ANOVA test.

Results

Several texture parameters were significantly different between the various scans performed on the two scanners. Regarding first-order texture parameters, skewness, energy and entropy were significantly different on scans acquired with the same voltage and current settings on different scanners, whereas entropy and energy were significantly different on scans acquired with different voltage or tube current settings on the same scanner. The large majority of second and higher order texture parameters appeared to be significantly affected by voltage, current and scanner selection.

Conclusion

CT textural parameters showed significant variability, depending on both CT scanner and scanning parameters. Our results need to be confirmed on a larger series, but they instill many doubts about the reproducibility and the reliability of texture analysis parameters.

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SS 14.6 - Correlation between medical outcome and US, shear-wave elastography and MRI findings in native liver survivor patients with biliary atresia after Kasai portoenterostomy

Presentation Number
SS 14.6
Speakers:
Session Name
SS 14 - Technical advances in gastro-intestinal and abdominal imaging
Channel
On-demand channel 6

Abstract

Purpose

Biliary atresia (BA) is an obliterative cholangiopathy and Kasai portoenterostomy (KP) represents its first-line treatment. Clinical and laboratory parameters together with abdominal US are usually performed during the follow-up. Shear-wave elastography (SWE) is able to evaluate liver parenchyma stiffness and MRI has also been proposed to study these patients. The aim of our study is to correlate US, SWE and MRI findings with medical outcomes in native liver survivor patients with BA after KP.

Material and methods

Twenty-four patients were retrospectively enrolled and divided into two groups based on “ideal” (n=15) or “non-ideal” (n=9) medical outcome defined according to clinical and laboratory parameters. US, SWE and MRI exams were analyzed qualitatively and quantitatively for imaging signs suggestive of chronic liver disease (CLD).

Results

Significant differences were found in terms of liver surface (p= 0.007) and morphology (p= 0.013), portal vein diameter (p= 0.012) and spleen size (p= 0.002) by US, liver signal intensity (p= 0.013), portal vein diameter (p= 0.010), presence of portosystemic collaterals (p= 0.042) and spleen size (p= 0.001) by MRI. The evaluation of portal vein diameter (moderate, κ= 0.44), portosystemic collaterals (good, κ= 0.78) and spleen size (very good, κ= 0.92) showed the best agreement between US and MRI. A significant (p= 0.01) difference in liver parenchyma stiffness by SWE was also found between the two groups (cut-off=9.6 kPa, sensitivity=55.6%, specificity=100%, area under the ROC curve=0.82).

Conclusion

US, SWE and MRI findings correlate with the medical outcome in native liver survivor patients with BA after KP.

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SS 14.8 - Cryoablation for abdominal tumoral implants: a case series

Presentation Number
SS 14.8
Speakers:
Session Name
SS 14 - Technical advances in gastro-intestinal and abdominal imaging
Channel
On-demand channel 6

Abstract

Purpose

Percutaneous cryoablation (CA) is widely used for the treatment of primary cancers and metastases with excellent outcomes. Results of CA for abdominal tumoral implants are limited. The purpose of this report is to show our preliminary results of CA of abdominal implants.

Material and methods

A retrospective analysis was performed of metastatic patients treated by means of CA for an abdominal tumoral implant between November 2018 and October 2019. All patients were discussed in a multidisciplinary tumour board. Complete ablation was defined as no local tumour enhancement on the first follow-up imaging. Adverse events (AE) were registered according to the SIR classification.

Results

Eight patients received CA for an abdominal tumoral implant of their renal cancer (n=3), colorectal cancer (n=2), endometrial cancer (n=2), granulosa cell cancer (n=1) and lung cancer (n=1). Abdominal implants were located retroperitoneally (n=4), in the abdominal wall (n=2), pancreas (n=1) and anterior of the stomach (n=1). Median size of the implants was 1.7 cm (R 1.1-3.7cm). Complete ablation was achieved in all lesions. One patient developed an AE grade 2 consisting of psoas muscle pain that was successfully treated with medication.

Conclusion

Cryoablation in the abdomen can be safely and effectively used for tumour control in an oligometastatic setting.

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SS 14.10 - Is there an association between the CT aspect of porto-systemic collaterals in cirrhotic patients and the risk of variceal haemorrhage?

Presentation Number
SS 14.10
Speakers:
Session Name
SS 14 - Technical advances in gastro-intestinal and abdominal imaging
Channel
On-demand channel 6

Abstract

Purpose

To determine if the aspect of the collateral, porto-caval circulation, as detected by CT can be associated with the risk of developing variceal hemorrhage.

Material and methods

CT scans of 105 cirrhotic patients were retrospectively included in the study. Patients with unequivocal diagnosis of liver cirrhosis (established by clinical, biological, imaging or histopathological arguments) were admitted for the follow-up of liver cirrhosis. Images were retrospectively analyzed by two readers with experience in the field of abdominal radiology. Diameter of the left gastric vein, presence or absence and dimensions of oesophageal and gastric varices, paraumbilical veins and splenorenal vein, respectively, were the indicators assessed by CT.

Results

The diameter of the paraoesophageal veins was significantly higher in patients with upper GI bleeding (4 mm vs. 2.5 mm, p=0.02). Moreover, there was a significant association between the diameters of the paragastric veins and the presence of variceal hemorrhage (p=0.04). The logistic regression analysis showed that only the diameter of the left gastric vein can independently be associated with the risk of upper GI bleeding (OR=1.6 [95%CI: 1.17-2.19], p=0.003). We found an optimal cut-off value of 4 mm for the diameter of the left gastric vein, useful to discriminate among patients with variceal hemorrhage from the ones without it, with a good diagnostic performance (AUC=0.78, Se=97%, Sp=45.8%, PPV=55.2%, NPV=95.7%).

Conclusion

There is a strong association between CT parameters and the risk of upper gastrointestinal bleeding. Diameter of the left gastric vein has good sensitivity and negative predictive value for variceal hemorrhage.

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