Evaluation of proton density fat fraction (PDFF) obtained from a vendor-neutral MRI sequence and MRQuantif software

OBJECTIVE

To validate the proton density fat fraction (PDFF) obtained by the MRQuantif software from 2D chemical shift encoded MR (CSE-MR) data in comparison with the histological steatosis data.

METHODS

This study, pooling data from 3 prospective studies spread over time between January 2007 and July 2020, analyzed 445 patients who underwent 2D CSE-MR and liver biopsy. MR derived liver iron concentration (MR-LIC) and PDFF was calculated using the MRQuantif software. The histological standard steatosis score (SS) served as reference. In order to get a value more comparable to PDFF, histomorphometry fat fraction (HFF) were centrally determined for 281 patients. Spearman correlation and the Bland and Altman method were used for comparison.

RESULTS

Strong correlations were found between PDFF and SS (rs = 0.84, p < 0.001) or HFF (rs = 0.87, p < 0.001). Spearman's coefficients increased to 0.88 (n = 324) and 0.94 (n = 202) when selecting only the patients without liver iron overload. The Bland and Altman analysis between PDFF and HFF found a mean bias of 5.4% ± 5.7 [95% CI 4.7, 6.1]. The mean bias was 4.7% ± 3.7 [95% CI 4.2, 5.3] and 7.1% ± 8.8 [95% CI 5.2, 9.0] for the patients without and with liver iron overload, respectively.

CONCLUSION

The PDFF obtained by MRQuantif from a 2D CSE-MR sequence is highly correlated with the steatosis score and very close to the fat fraction estimated by histomorphometry. Liver iron overload reduced the performance of steatosis quantification and joint quantification is recommended. This device-independent method can be particularly useful for multicenter studies.

CLINICAL RELEVANCE STATEMENT

The quantification of liver steatosis using a vendor-neutral 2D chemical-shift MR sequence, processed by MRQuantif, is well correlated to steatosis score and histomorphometric fat fraction obtained from biopsy, whatever the magnetic field and the MR device used.

KEY POINTS

• The PDFF measured by MRQuantif from 2D CSE-MR sequence data is highly correlated to hepatic steatosis. • Steatosis quantification performance is reduced in case of significant hepatic iron overload. • This vendor-neutral method may allow consistent estimation of PDFF in multicenter studies.

Surgical management of adhesive small bowel obstruction: Is it still mandatory to wait? - An update

Small bowel obstruction syndromes (SBO) represent one of the main causes of emergency admission for surgical abdominal pain. The 2018 Bologna Guidelines (Ten Broek et al. 2018) recommend non-operative management at the outset if there are no signs of severity; surgery is proposed after 72h for the 20-30% of patients who fail medical management. However, these recommendations were based on old studies published at a time when laparoscopic surgery was not commonplace and when diagnostic capabilities (particularly for establishing etiology) were less developed than they are today. Additionally, the advent and development of laparoscopy and enhanced rehabilitation after surgery have led to a decrease in surgical morbidity. These guidelines are therefore now debated and several recent publications have encouraged urgent or semi-urgent surgical management for patients presenting for SBO in order to reduce morbidity, mortality, duration of hospitalization and costs, and to improve the feasibility of therapeutic laparoscopy. Prompt surgical management could also reduce the risk of recurrent small bowel obstructions. This model for early surgical management probably cannot be applied to all patients. It therefore seems important to select those patients at risk for failure of medical treatment and to identify those in whom the probability of successful laparoscopy is high. New radiological tools should allow better selection in the future. At the present time, the indications for early surgery "within 24h" should be emphasized.

[Impact of partial nephrectomy in a hybrid operating room on the activity of kidney cancer surgery]

INTRODUCTION

Partial nephrectomy (NP) after embolization of tumor vessels (NPESH) in a hybrid room combines embolization of tumor vessels and enucleation of the tumor under laparoscopy in the same operative time. The purpose of this study was to assess the impact of the use of NPESH in the management of patients treated with surgery for a localized kidney tumor.

MATERIAL AND METHODS

Using the uroCCR database, we included all consecutive patients operated in a university hospital for localized kidney tumor. From 2011 to May 2015, patients were treated by Standard Partial Nephrectomy (NPS) Laparoscopic or Open and from May 2015 to May 2019 by NPESH. We evaluated characteristics of patients, tumors, perioperative data and complications. These data were compared by Student and Khi2 tests.

RESULTS

87 NPS were performed during Period 1 and 137 NPS were performed during period 2. The ASA score of patients undergoing NPESH was higher than NPS (P<0.0001). The tumor complexity and median tumor size were similar in the two groups (P=0.852 and P=0.48). The complication rate for NPS and NPESH was 55.2% and 33.6% (P=0.002). There were less severe complications in the NEPSH group (P=0.012). The median length of stay was 8 and 4 days for the NPS and NPESH groups (P<0.0001). Positive surgical margins were 2 (2.3%) and 6 (4.6%) for the NPS and NPESH group (P=0.713).

DISCUSSION

NPESH is an efficient technique compared to NPS. It seems to be an interesting alternative to limit renal ischemia, complication rate and length of stay for the management of localized kidney tumors.

Burned bodies: post-mortem computed tomography, an essential tool for modern forensic medicine

Abstract

Currently, post-mortem computed tomography (PMCT) has become an accessible and contemporary tool for forensic investigations. In the case of burn victims, it provides specific semiologies requiring a prudent understanding to differentiate between the normal post-mortem changes from heat-related changes. The aim of this pictorial essay is to provide to the radiologist the keys to establish complete and focused reports in cases of PMCT of burn victims. Thus, the radiologist must discern all the contextual divergences with the forensic history, and must be able to report all the relevant elements to answer to the forensic pathologist the following questions: Are there tomographic features that could help to identify the victim? Is there evidence of remains of biological fluids in liquid form available for toxicological analysis and DNA sampling? Is there another obvious cause of death than heat-related lesions, especially metallic foreign bodies of ballistic origin? Finally, what are the characteristic burn-related injuries seen on the corpse that should be sought during the autopsy?

Teaching points

• CT is highly useful to find features permitting the identification of a severely burned body.

• PMCT is a major asset in gunshot injuries to depict ballistic foreign bodies in the burned cadavers.

• CT is able to recognise accessible blood for tests versus heat clot (air-crescent sign).

• Heat-related fractures are easily differentiated from traumatic fractures.

• Epidural collections with a subdural appearance are typical heat-related head lesions.

Diagnosis of hepatocellular carcinoma: An update on international guidelines

Imaging is essential for the successful management of patients with or at risk of developing hepatocellular carcinoma (HCC). If ultrasound remains the key screening modality, computed tomography and magnetic resonance imaging (MRI) can play a major role in the characterization and noninvasive diagnosis of nodules in patients at risk of developing HCC. Each technique has succeeded in adapting to the wide histological spectrum of focal liver lesions. In this review, we discuss recent advancements in imaging techniques and evaluation - notably diffusion-weighted imaging, contrast-enhanced ultrasound, and liver-specific MRI contrast agents - as well as their addition to international guidelines and reporting systems such as the Liver imaging reporting and data system (LI-RADS).

Liver fibrosis diagnosis by blood test and elastography in chronic hepatitis C: agreement or combination?

BACKGROUND

In chronic hepatitis C, the European Association for the Study of the Liver and the Asociacion Latinoamericana para el Estudio del Higado recommend performing transient elastography plus a blood test to diagnose significant fibrosis; test concordance confirms the diagnosis.

AIM

To validate this rule and improve it by combining a blood test, FibroMeter (virus second generation, Echosens, Paris, France) and transient elastography (constitutive tests) into a single combined test, as suggested by the American Association for the Study of Liver Diseases and the Infectious Diseases Society of America.

METHODS

A total of 1199 patients were included in an exploratory set (HCV, n = 679) or in two validation sets (HCV ± HIV, HBV, n = 520). Accuracy was mainly evaluated by correct diagnosis rate for severe fibrosis (pathological Metavir F ≥ 3, primary outcome) by classical test scores or a fibrosis classification, reflecting Metavir staging, as a function of test concordance.

RESULTS

Score accuracy: there were no significant differences between the blood test (75.7%), elastography (79.1%) and the combined test (79.4%) (P = 0.066); the score accuracy of each test was significantly (P < 0.001) decreased in discordant vs. concordant tests. Classification accuracy: combined test accuracy (91.7%) was significantly (P < 0.001) increased vs. the blood test (84.1%) and elastography (88.2%); accuracy of each constitutive test was significantly (P < 0.001) decreased in discordant vs. concordant tests but not with combined test: 89.0 vs. 92.7% (P = 0.118). Multivariate analysis for accuracy showed an interaction between concordance and fibrosis level: in the 1% of patients with full classification discordance and severe fibrosis, non-invasive tests were unreliable. The advantage of combined test classification was confirmed in the validation sets.

CONCLUSIONS

The concordance recommendation is validated. A combined test, expressed in classification instead of score, improves this rule and validates the recommendation of a combined test, avoiding 99% of biopsies, and offering precise staging.

Simultaneous CT angiography and whole-body CT is an effective imaging approach before multiorgan retrieval

PURPOSE

To assess the role of whole-body computed tomography (CT) for determining morphological suitability before multiorgan retrieval (MOR) in brain dead patients.

MATERIALS AND METHODS

Fifty-one clinically brain dead patients (21 women, 30 men; mean age 61 year±15) were included in this prospective, single center study. All patients had CT angiography of the brain and whole-body CT examination. CT images were evaluated for the presence of morphological abnormalities of lungs, liver and other abdominal organs and presence of vascular anatomical variants. The results of CT examinations were compared to intraoperative findings observed during organ harvesting and/or the results of histopathological analysis of biopsy specimens. The impact of whole-body CT examination on the harvesting process was evaluated.

RESULTS

Ninety-five percent of vascular anatomical variants that were found intraoperatively were depicted on CT. CT density measurements predicted surgical finding of steatosis in 80% of patients. Whole-body CT changed the MOR strategy in 21/51 patients (41%) including 3 MOR cancellations and 8 grafts refusals, whereas organ harvesting was continued in 10 patients after histopathological analysis was performed.

CONCLUSION

Selection of potential graft donors using whole-body CT is reliable and improves graft selection during MOR.

Osteoprotegerin levels are associated with liver fat and liver markers in dysmetabolic adults

AIM

This study aimed to determine the association between visceral adipose tissue (VAT), liver fat (LF) content, and other markers of the metabolic syndrome (MetS) and osteoprotegerin (OPG) in dysmetabolic adults.

METHODS

Subjects from the NUMEVOX cohort were included if they fulfilled at least one MetS criterion. They then underwent a thorough metabolic and cardiovascular evaluation, including arterial stiffness, atherosclerotic plaques, homoeostasis model assessment for insulin resistance (HOMA-IR) indices and OPG. VAT and LF content were measured by magnetic resonance imaging (MRI). Ultrasound examination of arteries and arterial stiffness were recorded, and age- and gender-adjusted paired correlations calculated.

RESULTS

Body mass index, waist circumference and MRI-derived VAT correlated with OPG, whereas abdominal subcutaneous fat did not. OPG levels were strongly correlated with LF content (r=0.25, P=0.003), liver markers such as alanine aminotransferase (r=0.39, P<0.001) and HOMA-IR index (r=0.39, P<0.0001). Plasma OPG also correlated with arterial stiffness and the number of atherosclerotic sites.

CONCLUSION

Plasma OPG levels are positively associated with both liver markers and increased LF content, but not with subcutaneous fat in dysmetabolic men. These findings suggest that elevated OPG levels may play a role in the link between fatty liver disease and enhanced cardiovascular risk.

Post-treatment MRI aspects of photodynamic therapy for prostate cancer

OBJECTIVES

Photodynamic therapy is a new focal therapy for prostate cancer.

METHODS

In this technique, a photosensitising agent is introduced intravenously, then activated by local laser illumination to induce tumour necrosis. Treatment efficacy is assessed by magnetic resonance imaging (MRI).

RESULTS AND CONCLUSIONS

We illustrate specific post-treatment MRI aspects at early and late follow-up with pathological correlations.

TEACHING POINTS

• Dynamic phototherapy is a new and promising focal therapy for prostate cancer. • One-week MRI shows increased volume of the treated lobe and large, homogeneous necrosis area. • Six-month MRI shows significant changes of the prostate shape and signal. • Six-month MRI becomes "base line" appearance for further follow-up or monitoring.

MRI and venographic aspects of pelvic venous insufficiency

Pelvic venous insufficiency is a frequent pathology in multiparous women. Diagnosis can be made by chance or suspected in the case of symptoms suggesting pelvic congestion syndrome or atypical lower limb varicosity fed by pelvic leaks. After ultrasound confirmation, dynamic venography is the reference pretherapeutic imaging technique, searching for pelvic varicosity and possible leaks to the lower limbs. MRI is less invasive and allows a three-dimensional study of the varicosity and, with dynamic angiography, it can assess ovarian reflux. It also helps to plan or even sometimes avoid diagnostic venography.

Gastrointestinal imaging: tips and traps in the diagnosis of small HCC

Improvement in survival of patients with HCC depends on detecting small lesions. This is possible by screening all patients with cirrhosis for HCC. However, these small lesions are difficult to characterise as only 50 to 80% of lesions less than 3cm have a typical HCC appearance, depending on the imaging technique used. MRI, with its various possibilities (dynamic sequences, diffusion-weighting, liver-specific contrast agents), is currently the most effective imaging technique for characterising these small HCCs, but at present we do not know the best combination of imaging examinations for diagnosing the condition.

Planned caesarean in the interventional radiology cath lab to enable immediate uterine artery embolization for the conservative treatment of placenta accreta

AIM

To evaluate the feasibility and efficacy of routine uterine artery embolization (UAE) immediately after planned caesareans performed in the cath lab for conservative treatment of placenta accreta.

MATERIALS AND METHODS

A retrospective study included all patients who had a planned caesarean in the cath lab for conservative treatment of placenta accreta at Angers University Hospital, which is a tertiary care centre, from April 2001 to September 2010. Twelve patients underwent UAE immediately after caesarean with the placenta left partially or totally in situ. The success rate of embolization, blood loss, and complications were reported.

RESULTS

Diagnosis of abnormal placentation was confirmed by caesarean findings in 14 cases. Four patients had a percreta form with bladder invasion. In seven cases blood loss was insignificant and UAE was prophylactic; no secondary haemorrhage was observed in this group. Postpartum haemorrhage occurred in five cases: control of immediate postpartum bleeding by embolization was successful in three and failed in two leading to hysterectomy. In one case uterine necrosis occurred 6 weeks after embolization, requiring a hysterectomy. Delayed complications resulted in hysterectomy and partial bladder resection 3 months after delivery for one of the patients with placenta percreta.

CONCLUSION

UAE immediately after a caesarean performed in the cath lab is a feasible therapeutic option for conservative treatment of placenta accreta. Advantages include reducing stress and risks associated with transferring women with potentially unstable haemodynamics.

Benefit of the Vittel criteria to determine the need for whole body scanning in a severe trauma patient

OBJECTIVE

To evaluate the use of the Vittel criteria in addition to a clinical examination to determine the need for a whole body scan (WBS) in a severe trauma patient.

MATERIALS AND METHODS

Between December 2008 and November 2009, 339 severe trauma patients with at least one Vittel criterion were prospectively evaluated with a WBS. The following data were collected: the Vittel criteria present, circumstances of the accident, traumatic injury on the WBS, and irradiation. The original intent to prescribe a computed tomography (CT) scan (whole body or a targeted region), based solely on clinical signs, was specified.

RESULTS

Injuries were diagnosed in 55.75% of the WBS (n=189). The most common Vittel criteria were "global assessment" (n=266), "thrown, run over" (n=116), and "ejected from vehicle" (n=94). The multivariate analysis used the following as independent criteria for predicting severe traumatic injury on the WBS: Glasgow score less than 13, penetrating trauma, and colloid resuscitation greater than 11. Based solely on clinical factors, 164 patients would not have had any scan or (only) a targeted scan. In that case, 15% of the severe injuries would have been missed.

CONCLUSION

Using the Vittel criteria to determine the need for a WBS in a severe trauma patient makes it possible to find serious injuries not suspected on the clinical examination, but at the cost of an increased number of normal scans.

[Imaging features of osseous and extra-osseous involvement in Erdheim-Chester disease]

Erdheim-Chester disease is a rare form of systemic non-Langerhans cell histiocytosis characterized by infiltration by lipid-laden or foamy histiocytes. Osseous involvement, major diagnostic criteria, is constant and characteristic. It presents as metaphyseal and diaphyseal osteosclerosis, mainly affecting the long bones of the lower limbs. A few cases with axial skeleton involvement have been reported. Extra-osseous lesions may affect the retroperitoneum, lungs, skin, heart, brain and orbits. Prognosis depends mainly on the extra-osseous disease, mainly heart and lung involvement. Diagnosis is based on the combination of radiographic features, nuclear medicine features and nearly pathognomonic immunohistochemical profile.

A not so solitary fibrous tumor of the liver

Solitary fibrous tumor (SFT) is a rare neoplasm. Liver parenchyma is a rare location of SFT and, in this case, it usually follows a benign course. We report here the case of a 54-year-old man who presented a large SFT tumor of the right hepatic lobe. The tumor was surgically resected. Local recurrence occurred 6 years later as a 15 cm diameter liver tumor. Histological examination of the resected lesion showed features of an aggressive form of SFT. Two years later, the patient presented with complaints of neck pain and ensuing examinations revealed a tumor of the cranial base. A new surgical resection was performed and histological examination confirmed a metastasis of the SFT. Few weeks later, the patient presented an irreducible psoitis due to an iliac bone metastasis. He died within 1 month.

Distribution of abdominal adipose tissue as a predictor of hepatic steatosis assessed by MRI

AIM

To evaluate the relationship between the distribution of visceral and subcutaneous adipose tissue and hepatic steatosis assessed using magnetic resonance imaging (MRI).

MATERIALS AND METHODS

One T1-weighted, in-/out-of-phase, single-section sequence at the L3/L4 level and one multi-echo gradient MRI (MGRE) sequence were performed on 65 patients [19 females and 46 males; age 57+/-9.5 years; body mass index (BMI) 31+/-5.1kg/m(2)]. Visceral adipose tissue (VAT), subcutaneous adipose tissue (SAT) surfaces, and hepatic steatosis were automatically calculated using in-house software. Weight, height, BMI, waist circumference, hip circumference, and waist:hip ratio were recorded. The probability of having a steatosis greater than 10% on MRI was evaluated by receiver operating characteristic (ROC) curves.

RESULTS

The anthropometric parameter best correlated to hepatic steatosis was the waist-to-hip ratio (r=0.301). VAT and proportion of VAT were correlated to liver fat content (r=0.307 and r=0.249, respectively). No significant correlations were found for BMI, hip circumference, and SAT. The area under the receiver operating characteristics (AUROCs) for the relationship between liver steatosis and BMI, waist circumference, waist:hip ratio, VAT surface, and proportion of VAT, were respectively 0.52, 0.63, 0.71, 0.73 and 0.75.

CONCLUSION

Adipose tissue distribution is more relevant than total fat mass when assessing the possibility of liver steatosis in overweight patients.

Radiation-induced cholangitis with hepatocellular carcinoma

There are no reports of hepatocellular carcinoma complicating postradiotherapy cholangitis. We report the case of a 45-year-old patient who had undergone upper abdominal radiotherapy for Hodgkin's disease, 21 years before, which was complicated years later by cholangitis with stricture of the common bile duct. Biliodigestive anastomosic surgery was scheduled due to recurrent angiocholitis, and hepatocellular carcinoma was discovered. The patient died from carcinoma some months later.

Liver fibrosis staging with contrast-enhanced ultrasonography: prospective multicenter study compared with METAVIR scoring

We prospectively assessed contrast-enhanced sonography for evaluating the degree of liver fibrosis as diagnosed via biopsy in 99 patients. The transit time of microbubbles between the portal and hepatic veins was calculated from the difference between the arrival time of the microbubbles in each vein. Liver biopsy was obtained for each patient within 6 months of the contrast-enhanced sonography. Histological fibrosis was categorized into two classes: (1) no or moderate fibrosis (F0, F1, and F2 according to the METAVIR staging) or (2) severe fibrosis (F3 and F4). At a cutoff of 13 s for the transit time, the diagnosis of severe fibrosis was made with a specificity of 78.57%, a sensitivity of 78.95%, a positive predictive value of 78.33%, a negative predictive value of 83.33%, and a performance accuracy of 78.79%. Therefore, contrast-enhanced ultrasound can help with differentiation between moderate and severe fibrosis.

[Recurrent acute pancreatitis revealing a hydatid cyst of the pancreas]

The authors report a case of hydatid cyst of the pancreas in a 29-year-old man. Biology and computed tomography contributed to the preoperative diagnosis. The intervention consisted in a left pancreatectomy with spleen ablation. In the light of this case and the literature review, the authors discuss diagnostic issues raised by hydatid cyst of the pancreas.

[MR-endoscopic US correlation for loco-regional staging of rectal carcinoma]

INTRODUCTION

To correlate findings at high-resolution MR and endoscopic US (EUS) for preoperative loco-regional staging of rectal carcinoma.

PATIENTS AND METHODS

Fifty-two patients with rectal carcinoma underwent high-resolution MR imaging. Only 43 of these patients underwent EUS due to technical limitations and stenosing carcinomas. Morphological imaging features and TNM staging were evaluated for both imaging modalities. The degree of correlation and accuracy were calculated for both.

RESULTS

The correlation between MR and EUS was good for tumor length and thickness (r=0.7 and 0.61) for for nodal (N) staging (k=0.53). Correlation was good for T1 and T2 stages (k=0.51) and T3 stage (k=0.43) and very poor for stage 4 (k= -0.09), because no T4 lesion was detected at EUS. 81.8% of patients where T stage was over-estimated on MRI and 100% of patients where T stage was over-estimated on EUS had received preoperative radiation therapy. Therefore, results should be interpreted with caution. The predictive evaluation of tumor resectability (absence of perirectal fascia invasion) with a circumferential margin on MR> or =5 mm was 93%.

CONCLUSION

Correlation between MR and EUS was moderate for T staging, because of limitations of EUS for large tumors. Results confirm that high-resolution MRI is useful for loco-regional staging of rectal carcinoma, especially for large tumors. EUS should be limited to the valuation of superficial tumors of the rectum.

[Imaging nodules within cirrhotic liver: how do I do it?]

Cirrhosis is a chronic liver disease characterized by the presence of diffuse parenchymal necrosis, reactive fibrosis and nodular regeneration. These regenerative nodules may evolve into dysplastic nodules and finally nodules of hepatocellular carcinoma (HCC). Improved survival of cirrhotic patients with HCC depends on eligibility to liver transplantation. The purpose of this paper is to review the imaging features of liver nodules within cirrhotic liver and to propose the imaging strategies when considering the possibility of liver transplantation.