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.

Quantification of Liver Iron Overload with MRI: Review and Guidelines from the ESGAR and SAR

Accumulation of excess iron in the body, or systemic iron overload, results from a variety of causes. The concentration of iron in the liver is linearly related to the total body iron stores and, for this reason, quantification of liver iron concentration (LIC) is widely regarded as the best surrogate to assess total body iron. Historically assessed using biopsy, there is a clear need for noninvasive quantitative imaging biomarkers of LIC. MRI is highly sensitive to the presence of tissue iron and has been increasingly adopted as a noninvasive alternative to biopsy for detection, severity grading, and treatment monitoring in patients with known or suspected iron overload. Multiple MRI strategies have been developed in the past 2 decades, based on both gradient-echo and spin-echo imaging, including signal intensity ratio and relaxometry strategies. However, there is a general lack of consensus regarding the appropriate use of these methods. The overall goal of this article is to summarize the current state of the art in the clinical use of MRI to quantify liver iron content and to assess the overall level of evidence of these various methods. Based on this summary, expert consensus panel recommendations on best practices for MRI-based quantification of liver iron are provided.

Proton pump inhibition for secondary hemochromatosis in hereditary anemia: a phase III placebo-controlled randomized cross-over clinical trial

Iron overload is a severe general complication of hereditary anemias. Treatment with iron chelators is hampered by important side‐effects, high costs, and the lack of availability in many countries with a high prevalence of hereditary anemias. In this phase III randomized placebo‐controlled trial, we assigned adults with non‐transfusion‐dependent hereditary anemias with mild‐to‐moderate iron overload to receive esomeprazole (at a dose of 40 mg twice daily) or placebo for 12 months in a cross‐over design. The primary end point was change of liver iron content measured by MRI. A total of 30 participants were enrolled in the trial. Treatment with esomeprazole resulted in a statistically significant reduction in liver iron content that was 0.55 mg Fe/g dw larger than after treatment with placebo (95%CI [0.05 to 1.06]; p = 0.03). Median baseline liver iron content at the start of esomeprazole was 4.99 versus 4.49 mg Fe/g dw at start of placebo. Mean delta liver iron content after esomeprazole treatment was −0.57 (SD 1.20) versus −0.11 mg Fe/g dw (SD 0.75) after placebo treatment. Esomeprazole was well tolerated, reported adverse events were mild and none of the patients withdrew from the study due to side effects. In summary, esomeprazole resulted in a significant reduction in liver iron content when compared to placebo in a heterogeneous group of patients with non‐transfusion‐dependent hereditary anemias. From an international perspective this result can have major implications given the fact that proton pump inhibitors may frequently be the only realistic therapy for many patients without access to or not tolerating iron chelators.

Indexing Imaging Reports for Data Sharing: A Study of Mapping Using RadLex Playbook and LOINC

New use cases and the need for quality control and imaging data sharing in health studies require the capacity to align them to reference terminologies. We are interested in mapping the local terminology used at our center to describe imaging procedures to reference terminologies for imaging procedures (RadLex Playbook and LOINC/RSNA Radiology Playbook). We performed a manual mapping of the 200 most frequent imaging report titles at our center (i.e. 73.2% of all imaging exams). The mapping method was based only on information explicitly stated in the titles. The results showed 57.5% and 68.8% of exact mapping to the RadLex and LOINC/RSNA Radiology Playbooks, respectively. We identified the reasons for the mapping failure and analyzed the issues encountered.

Practical guide to quantification of hepatic iron with MRI

Abstract

Our intention is to demystify the MR quantification of hepatic iron (i.e., the liver iron concentration) and give you a step-by-step approach by answering the most pertinent questions. The following article should be more of a manual or guide for every radiologist than a classic review article, which just summarizes the literature. Furthermore, we provide important background information for professional communication with clinicians. The information regarding the physical background is reduced to a minimum. After reading this article, you should be able to perform adequate MR measurements of the LIC with 1.5-T or 3.0-T scanners.

Key Points

• MRI is widely accepted as the primary approach to non-invasively determine liver iron concentration (LIC).

• This article is a guide for every radiologist to perform adequate MR measurements of the LIC.

• When using R2* relaxometry, some points have to be considered to obtain correct measurements—all explained in this article.

Whole-Body CT after Motor Vehicle Crash: No Benefit after High-Energy Impact and with Normal Physical Examination

Background Debate continues about the risks and benefits of systematic whole-body CT when no injury is clinically suspected. Risks of whole-body CT include high radiation exposure and iodine contrast agent, but its effectiveness in reducing mortality in low-risk motor vehicle crashes is unclear. Purpose To assess unsuspected injuries revealed at whole-body CT in patients following motor vehicle crash (MVC) meeting only kinetic elements of the Vittel criteria for the severity of trauma, with no evidence of trunk injury and a Glasgow Coma Scale score of 15. Materials and Methods This retrospective study included all consecutive adult patients who consulted an emergency department of a level 1 trauma center between August 2016 and July 2017 if they underwent whole-body CT for one or more kinetic elements of the Vittel criteria, had a normal examination of the trunk, and had a Glasgow Coma Scale score of 15. Data of the MVC mechanism and physical and biologic examinations were collected, as well as patient treatment data after whole-body CT. Whole-body CT examinations were read by two double-blinded readers to help detect unsuspected injuries. Results Ninety-three patients were included; 72 were men with a mean age of 30.8 years ± 12.0 (standard deviation). Sixty-nine patients were occupants of a car. Seventeen patients were hit by a car while on motorbikes, three while on bicycles, and four as pedestrians. Unsuspected injuries were depicted at 11 whole-body CT examinations: eight lung contusions, one acetabular fracture, one sternal fracture, and one adrenal hematoma. None of these injuries required a specific treatment. One patient with lung contusion of more than 30% of lung volume was followed without requiring further treatment. Conclusion In this population, whole-body CT did not lead to any change in patient treatment. These results suggest whole-body CT should not be systematically performed when no evidence of trunk injury is observed in patients following motor vehicle crash meeting only kinetic elements of Vittel criteria. © RSNA, 2019 See also the editorial by Munera and Durso in this issue.

MRI for the measurement of liver iron content, and for the diagnosis and follow-up of iron overload disorders

MRI is now the reference method for detecting and quantifying hepatic and extrahepatic iron overload, regardless of its cause. The decrease of the hepatic signal is proportional to the amount of iron in the tissues. It is more pronounced with T2*-weighted gradient echo sequences. It increases proportionally with the strength of the magnetic field. Thus a 3-T MRI is be more sensitive and probably more accurate to detect a slight iron overload, as seen in dysmetabolic hepatosiderosis. Conversely, a 1.5-T MRI better estimates a high overload. Quantification can be done with the calculation of T2* (or R2*) or by using the liver to muscle signal intensity ratio (SIR). Today with a single multi-echo gradient-echo sequence, obtained in a unique apnea, the two methods can be used simultaneously. An associated quantification of steatosis is also obtained. This same type of sequence is proposed for quantification of iron in other tissues and in particular for the myocardium.

Assessment of liver iron overload by 3 T MRI

PURPOSE

To evaluate the performance and limitations of the signal intensity ratio method for quantifying liver iron overload at 3 T.

METHODS

Institutional review board approval and written informed consent from all participants were obtained. One hundred and five patients were included prospectively. All patients underwent a liver biopsy with biochemical assessment of hepatic iron concentration and a 3 T MRI scan with 5 breath-hold single-echo gradient-echo sequences. Linear correlation between liver-to-muscle signal intensity ratio and liver iron concentration was calculated. The algorithm for calculating magnetic resonance hepatic iron concentration was adapted from the method described by Gandon et al. with echo times divided by 2. Sensitivity and specificity were calculated.

RESULTS

Five patients were excluded (coil selection failure or missing sequence) and 100 patients were analyzed, 64 men and 36 women, 52 ± 13.3 years old, with a biochemical hepatic iron concentration range of 0-630 µmol/g. Linear correlation between biochemical hepatic iron concentration and MR-hepatic iron concentration was excellent with a correlation coefficient = 0.96, p < 0.0001. Sensitivity and specificity were, respectively, 83% (0.70-0.92) and 96% (0.85-0.99), with a pathological threshold of 36 µmol/g.

CONCLUSION

Signal intensity ratio method for quantifying liver iron overload can be used at 3 T with echo times divided by 2.

Acoustic radiation force impulse imaging for assessing liver fibrosis in alcoholic liver disease

AIM: To evaluate the performance of elastography by ultrasound with acoustic radiation force impulse (ARFI) in determining fibrosis stage in patients with alcoholic liver disease (ALD) undergoing alcoholic detoxification in relation to biopsy.

METHODS: Eighty-three patients with ALD undergoing detoxification were prospectively enrolled. Each patient underwent ARFI imaging and a liver biopsy on the same day. Fibrosis was staged according to the METAVIR scoring system. The median of 10 valid ARFI measurements was calculated for each patient.

RESULTS: Sixty-nine males and thirteen females (one patient excluded due to insufficient biopsy size) were assessed with a mean alcohol consumption of 132.4 ± 128.8 standard drinks per week and mean cumulative year duration of 17.6 ± 9.5 years. Sensitivity and specificity were respectively 82.4% (0.70-0.95) and 83.3% (0.73-0.94) (AUROC = 0.87) for F ≥ 2 with a cut-off value of 1.63m/s; 82.4% (0.64-1.00) and 78.5% (0.69-0.89) (AUROC = 0.86) for F ≥ 3 with a cut-off value of 1.84m/s; and 92.3% (0.78-1.00] and 81.6% (0.72-0.90) (AUROC = 0.89) for F = 4 with a cut-off value of 1.94 m/s.

CONCLUSION: ARFI is an accurate, non-invasive and easy method for assessing liver fibrosis in patients with ALD undergoing alcoholic detoxification.

Dynamic contrast-enhanced MRI: Study of inter-software accuracy and reproducibility using simulated and clinical data

PURPOSE

To test the reproducibility and accuracy of pharmacokinetic parameter measurements on five analysis software packages (SPs) for dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), using simulated and clinical data.

MATERIALS AND METHODS

This retrospective study was Institutional Review Board-approved. Simulated tissues consisted of pixel clusters of calculated dynamic signal changes for combinations of Tofts model pharmacokinetic parameters (volume transfer constant [K(trans) ], extravascular extracellular volume fraction [ve ]), longitudinal relaxation time (T1 ). The clinical group comprised 27 patients treated for rectal cancer, with 36 3T DCE-MR scans performed between November 2012 and February 2014, including dual-flip-angle T1 mapping and a dynamic postcontrast T1 -weighted, 3D spoiled gradient-echo sequence. The clinical and simulated images were postprocessed with five SPs to measure K(trans) , ve , and the initial area under the gadolinium curve (iAUGC). Modified Bland-Altman analysis was conducted, intraclass correlation coefficients (ICCs) and within-subject coefficients of variation were calculated.

RESULTS

Thirty-one examinations from 23 patients were of sufficient technical quality and postprocessed. Measurement errors were observed on the simulated data for all the pharmacokinetic parameters and SPs, with a bias ranging from -0.19 min(-1) to 0.09 min(-1) for K(trans) , -0.15 to 0.01 for ve , and -0.65 to 1.66 mmol.L(-1) .min for iAUGC. The ICC between SPs revealed moderate agreement for the simulated data (K(trans) : 0.50; ve : 0.67; iAUGC: 0.77) and very poor agreement for the clinical data (K(trans) : 0.10; ve : 0.16; iAUGC: 0.21).

CONCLUSION

Significant errors were found in the calculated DCE-MRI pharmacokinetic parameters for the perfusion analysis SPs, resulting in poor inter-software reproducibility. J. Magn. Reson. Imaging 2016;43:1288-1300.

The effect of water suppression on the hepatic lipid quantification, as assessed by the LCModel, in a preclinical and clinical scenario

OBJECTIVE

To investigate the effect of water suppression on the hepatic lipid quantification, using the LCModel.

MATERIALS AND METHODS

MR spectra with and without water suppression were acquired in the liver of mice at 4.7 T and patients at 3 T, and processed with the LCModel. The Cramér-Rao Lower Bound (CRLB) values of the seven lipid resonances were determined to assess the impact of water suppression on hepatic lipid quantification. A paired t test was used for comparison between the CRLBs obtained with and without water suppression.

RESULTS

For the preclinical data, in the high (low) fat fraction subset an overall impairment in hepatic lipid quantification, i.e. an increase of CRLBs (no significant change of CRLBs) was observed in spectra acquired with water suppression. For the clinical data, there were no substantial changes in the CRLB with water suppression. Because (1) the water suppression does not overall improve the quantification of the lipid resonances and (2) the MR spectrum without water suppression is always acquired for fat fraction calculation, the optimal data-acquisition strategy for liver MRS is to acquire only the MR spectrum without water suppression.

CONCLUSION

For quantification of hepatic lipid resonances, it is advantageous to perform MR spectroscopy without water suppression in a clinical and preclinical scenario (at moderate fields).

Screening for colorectal cancer: the role of CT colonography

Colorectal cancer, which is the third most frequent cancer and the cancer with the second highest mortality rate, frequently develops on a pre-existing adenomatous polyps whose slow growth and malignant degeneration can be identified and controlled by effective screening. Although most lesions can be detected and resected during optical colonoscopy (OC), the cost, risk and poor acceptance of this technique by the general population means that it is reserved for high-risk or very high-risk individuals. The fecal occult blood test (FOBT) (such as the Hemoccult(®)) is proposed for intermediate-risk individuals between 50 and 75 years old. However, despite the improvements that have been made in this method, sensitivity is low, and although it is simple, it is too rarely used. CT colonography (virtual colonoscopy) is proposed in case of failure, additional risk factors or refusal of optical colonoscopy in high-risk patients or in the presence of a positive FOBT. It should also be proposed as an alternative to the FOBT test to patients who accept the constraints of this technique.

A simple system to predict perihilar cholangiocarcinoma resectability

BACKGROUND

The aim of this study was to retrospectively validate a new system to predict perihilar cholangiocarcinoma (PHC) resectability. We hypothesized that when the left lateral section (segments II-III) duct confluence (LLC) is free, the left lateral section might be preserved for curative resection. When the LLC is invaded, vascular invasion is frequent and radical resection might often be impossible without complex vascular reconstruction.

METHOD

Radiological files of patients operated for PHC at our institution were reviewed and PHC was classified depending on whether LLC was invaded (type X) or free (type Y). Peroperative findings and follow-up were then matched with our XY classification.

RESULTS

Thirty-seven patients were included, 28 (78 %) type Y and nine (22 %) type X PHCs. Hepatic artery (HA) invasion was present in 14 % of type Y and 100 % of type X PHCs (P < 0.001). Left HA was never involved in type Y and always involved in type X. Portal vein invasion was present in 25 and 78 % of type Y and type X PHC, respectively (P = 0.014). Complete resection rates without HA in type Y and X patients were 89 % (84 % R0 and 16 % R1) and 33 % (37.5 % R0 and 12.5 % R1), respectively (P = 0.01). Sensitivity, specificity, and precision of the XY classification to predict resectability were 84, 67, and 84 %, respectively.

CONCLUSION

XY classification for PHCs suggests that in type Y (free LLC), the tumor is most often resectable, while in type X (LLC involved), the tumor is only resectable using complex vascular reconstructions.

Pubo-femoral distance: an easy sonographic screening test to avoid late diagnosis of developmental dysplasia of the hip

OBJECTIVES

To propose an easy and reproducible sonographic screening test able to avoid late presentation of developmental dysplasia of the hip (DDH).

METHODS

The pubo-femoral distance (PFD) cut-off point was determined on 980 infants who underwent ultrasonography of the hips in comparison with the final diagnosis, based on clinical, ultrasound data and follow-up. PFD reproducibility was tested on 52 hips by both an experienced and an inexperienced radiologist. After teaching this screening method to general radiologists, its impact was evaluated by analysing the rate of late diagnosis in an entire administrative area.

RESULTS

An abnormal PFD threshold above 6 mm gave a sensitivity of 97.4 % for the diagnosis of DDH (271 hips) and a specificity of 84 %. Sensitivity increased to 100 % when taking into consideration children of 1 month or older. The PFD measurement stayed reproducible even in inexperienced hands (k = 0.795). For 3 years, following the extension of screening to all female infants, there was no late diagnosis of DDH in girls in amongst a catchment area of 1 million inhabitants.

CONCLUSIONS

PFD measurement with a threshold for abnormality of 6 mm at the age of 1 month, without asymmetry above 1.5 mm, could eradicate DDH late diagnosis.

Localized hypertrophic neuropathy of the sciatic nerve in children: MRI findings

BACKGROUND

Localized hypertrophic neuropathy (LHN) of the sciatic nerve in children is a rare condition characterized by a painless neurological deficit in the sciatic nerve territory.

OBJECTIVE

To demonstrate the role of MRI using a specific protocol and describe the primary findings in LHN.

MATERIALS AND METHODS

Imaging in four children (age 2 years to 12 years) is presented. All children presented with lower limb asymmetry. Three had a steppage gait. LHN was confirmed by electrophysiological studies and by MRI of the whole sciatic nerve with a dedicated protocol covering the lumbar spine and the lower limb.

RESULTS

There were four direct MRI findings: (1) linear and focal hypertrophy with progressive enlargement of a peripheral nerve or plexus diameter, (2) abnormal hyperintensity of the nerve on T2-weighted images, (3) preserved fascicular configuration, and (4) variable enhancement after intravenous gadolinium administration. In addition there were atrophy and fatty infiltration of innervated muscles. MRI was helpful for determining the extent of lesions and in excluding peripheral nerve compression or tumour.

CONCLUSION

MRI of the whole sciatic nerve is the method of choice for diagnosing LHN of the sciatic nerve.

[Developmental dysplasia of the hip]

At one month, the acetabular depth from a standard lateral coronal section is 4.6 ± 1.0mm. The correlation between experienced and junior radiologists is high (kappa 0.795). A treshhold of 6mm with a Δ (difference between right and left) less than 1.5mm provides a sensitivity of 100% for the detection of DDH at one month. Universal US screening at one month of all high-risk infants in 2009 resulted in a reduction of delayed diagnosis of DDH (zero girls, two boys) in Ille-et-Vilaine due to continuous medical education of general radiologists.

Accuracy of computed tomographic colonography in a nationwide multicentre trial, and its relation to radiologist expertise

OBJECTIVE

Reports on the accuracy of computed tomographic colonography (CTC) mainly involve series from expert institutions. The aims of this study were to assess CTC accuracy in a nationwide population and to relate it to radiologist performance in their initial training.

DESIGN

Nationwide multicentre trial.

SETTING

Twenty-eight radiologists, working in 26 mostly academic clinical units, were involved in the study after having attended a formal specialised 2-day training session on CTC. They worked through a training set of 52 cases with automatic feedback after an attempt at each case.

PATIENTS

The study enrolled 845 patients with average and high risk of colorectal cancer, 737 of whom had both complete CTC and videocolonoscopy data, which constituted the dataset.

INTERVENTIONS

Patients underwent same-day CTC followed by videocolonoscopy with segmental unblinding of CTC results.

MAIN OUTCOME MEASURES

Sensitivity, specificity and positive and negative predictive values for detection of polyps ≥ 6 mm in per-patient and per-lesion analyses of CTC without computer-aided detection.

RESULTS

Sensitivity, specificity and positive and negative predictive values for patients with polyps ≥ 6 mm were 69% (95% CI 61% to 77%), 91% (95% CI 89% to 94%), 67% (95% CI 59% to 74%) and 92% (95% CI 90% to 94%), respectively. Univariate analysis showed that the detection rate for polyps ≥ 6 mm was linked to neither radiologist case volume nor number of polyps, but was related to sensitivity achieved in the training set. Pooled sensitivity was 72% (95% CI 63% to 80%) versus 51% (95% CI 40% to 60%) for radiologists achieving above and below median sensitivity in the training set (61%), respectively. Multivariate analysis showed that sensitivity for polyps ≥ 6 mm in the training set was the only remaining significant predictive factor for subsequent performance.

CONCLUSIONS

Radiologist sensitivity CTC for detection of polyps ≥ 6 mm in training was the sole independent predictor for subsequent sensitivity in detection of such polyps.

MRI quantification of splenic iron concentration in mouse

PURPOSE

To quantify hepatic and splenic iron load, which is a critical issue for iron overload disease diagnosis. MRI is useful to noninvasively determine liver iron concentration, but not proven to be adequate for robust evaluation of splenic iron load. We evaluated the usefulness of MRI-derived parameters to determine splenic iron concentration in mice.

MATERIALS AND METHODS

A mouse model of experimental iron load was used. Multi-echo spin-echo images of liver and spleen were acquired at 4.7 Tesla. The parameters were tested at all echoes with and without an external reference. Splenic and hepatic iron concentrations were determined using biochemical assay as the gold standard.

RESULTS

Our results show that (i) use of an internal or external reference is essential; (ii) optimal echo times were TE = 19.5 ms and TE = 32.5 ms for the liver and spleen, respectively; (iii) in the liver, the relationship between biochemical and MRI iron concentration determinations is logarithmic; (iv) in the spleen, the best relationship is an inverse function.

CONCLUSION

A single spin-echo sequence allows robust estimation of hepatic and splenic iron content. Parameters classically used for hepatic iron concentration cannot be applied to splenic iron determination, which requires both the specific sequence and the adapted fitting function.

[Imaging of cystic liver diseases]

The high frequency of benign and asymptomatic liver cysts must not underevaluate the potential diagnostic difficulties of liver cystic diseases. Complicated liver cyst or cystic mass of various origin, such as developmental, neoplastic or inflammatory, are important to be recognized by the radiologist. The diagnostic approach is depending on the number of lesions and their dissemination. The presence of a wall, the internal structure of the lesion, particularly the MR signal and the proximity of the biliary tree are the main diagnostic criteria. Some less frequent but characteristic unusual features need to be memorized.

[Clinical and angiographic parameters affecting the quality of 16 slice spiral CT in the diagnosis of restenosis after stenting the left main coronary artery]

The metallic component of coronary stents makes it difficult to study their lumen by angio scanner. The object of this preliminary study was to appreciate the factors influencing the diagnosis of restenosis after stenting the left main coronary artery by 16-slice spiral angio CT. This Monocentric study included 27 patients who underwent 16-slice spiral angio CT six months after stenting of the left main coronary artery. It was possible to assess the stent lumen in 21 patients (78%) and no cases of > 50% restenosis were observed. In 4 patients, hypodense zones adjacent to the stent links were observed suggesting moderate intimal hyperplasia. The tests for ischaemia were normal in 3 of these patients. Coronary angiography and endocoronary ultrasound excluded significant restenosis in the fourth patient. In univariable analysis, the facors associated with good or excellent angioscanner quality (45% of patients) were Ostial stenosis (p = 0.03), no or minimal calcification on initial coronary angiography (p = 0.0S), stent diameters > 3.5mm (p = 0.03), heart rates < 60/min (p = 0.04), absence of extrasystoles (p = 0.05) during acquisition. In multivariable analysis, the only significant factors were absent or minimal calcification and stent diameters > 3.5mm (p = 0.02). The multidetector scanner seems a very promising method of investigating patients who have undergone stenting of the left main coronary artery but this study shows that certain clinical and angiographic parameters are limiting factors of surveillance with a 16-slice angioscanner.

[Diagnosis of iron overload]

Hepatic iron overload conditions can be classified as genetic, mainly related to HFE haemochromatosis, and secondary, mainly associated with haematological and hepatic disorders and with metabolic syndrome. The strict affirmation of iron excess relies upon liver biopsy, MRI or calculation of the amount of iron removed through phlebotomies. Determination of its cause relies upon the assessment of transferrin saturation which, when increased, suggests the diagnosis of either haemochromatosis--implying HFE testing--or overload secondary to dysmyelopoiesis or to end-stage cirrhosis, and, when normal, suggests the diagnosis of dysmetabolic iron overload syndrome.

Fistule pancréatique post-traumatique : succès du traitement endoscopique par endoprothèse

INTRODUCTION

The risk of complications and the severity of pancreatic trauma depend on the status of the main pancreatic duct. Endoscopic retrograde pancreatography (ERCP) has emerged as the technique of reference for assessing pancreatic ductal anatomy, and it also permits therapeutic intervention by the endoscopic placement of an endoprosthesis.

CASE

We report a pancreatic fistula attributable to posttraumatic rupture of the main duct, undiagnosed before ERCP and successfully treated by endoscopic stent placement.

DISCUSSION

ERCP has emerged as a tool for both diagnosis and treatment. Major traumatic pancreatic duct disruptions can be diagnosed more easily and managed successfully by endoscopic stent placement, thereby avoiding surgical morbidity. ERCP is impractical in emergency settings for many reasons. Magnetic resonance pancreatography may be useful for establishing the type and extent of pancreatic lesions and for selecting patients for endoscopic treatment.

[Spontaneous peri-pancreatic hematoma associated with celiac trunk stenosis: diagnostic difficulties and therapeutic management]

We report a case of spontaneous peri-pancreatic hematoma which was associated with a celiac trunk stenosis. Hematoma was probably due to the rupture of a pancreaticoduodenal artery aneurysm. This diagnosis of pancreatic carcinoma, initially retained, illustrates the difficult diagnostic process. Therapeutic modalities for preventing recurrence are discussed.

Non-invasive assessment of hepatic iron stores by MRI

BACKGROUND

MRI has been proposed for non-invasive detection and quantification of liver iron content, but has not been validated as a reproducible and sensitive method, especially in patients with mild iron overload. We aimed to assess the accuracy of a simple, rapid, and easy to implement MRI procedure to detect and quantify hepatic iron stores.

METHODS

Of 191 patients recruited, 17 were excluded and 174 studied, 139 in a study group and 35 in a validation group. All patients underwent both percutaneous liver biopsy with biochemical assessment of hepatic iron concentration (B-HIC) and MRI of the liver with various gradient-recalled-echo (GRE) sequences obtained with a 1.5 T magnet. Correlation between liver to muscle (L/M) signal intensity ratio and liver iron concentration was calculated. An algorithm to calculate magnetic resonance hepatic iron concentration (MR-HIC) was developed with data from the study group and then applied to the validation group.

FINDINGS

A highly T2-weighted GRE sequence was most sensitive, with 89% sensitivity and 80% specificity in the validation group, with an L/M ratio below 0.88. This threshold allowed us to detect all clinically relevant liver iron overload greater than 60 micromol/g (normal value <36 micromol/g). With other sequences, an L/M ratio less than 1 was highly specific (>87%) for raised hepatic iron concentration. With respect to B-HIC range analysed (3-375 micromol/g), mean difference and 95% CI between B-HIC and MR-HIC were quite similar for study and validation groups (0.8 micromol/g [-6.3 to 7.9] and -2.1 micromol/g [-12.9 to 8.9], respectively).

INTERPRETATION

MRI is a rapid, non-invasive, and cost effective technique that could limit use of liver biopsy to assess liver iron content. Our MR-HIC algorithm is designed to be used on various magnetic resonance machines.

Squamous cell carcinoma arising in a hepatic forgut cyst

We report the second case of squamous cell carcinoma arising in a hepatic foregut cyst (CHFC) in a 40-year-old woman. Microscopically, the lining of the cyst was composed of ciliated columnar epithelium, gastric and squamous epithelium. The squamous epithelium showed areas with dysplastic changes and other areas with carcinomatous transformation. In this congenital lesion, it was not surprising to find squamous and gastric mucosa because oesophagus, stomach, and tracheobronchic tree derive from the embryologic foregut. Squamous carcinoma might develop in a context of inflammation as in biliary cyst. In agreement with the first case described in the literature, this report also suggests that a large-sized symptomatic hepatic cyst should be excised.

Aceruloplasminemia: new clinical, pathophysiological and therapeutic insights

Aceruloplasminemia is an autosomal recessive disease of iron overload associated with mutation(s) in the ceruloplasmin gene. We report here a new case of aceruloplasminemia in a woman who is a compound heterozygote for two new mutations. Besides this novel genotypic profile, this observation provides new insights on: (i) iron metabolism with normal erythroid repartition, in the absence of serum non-transferrin-bound iron and with an increase of 59Fe plasma clearance; (ii) hepatic abnormalities associated with the presence of iron-free foci; (iii) the therapeutic management of the disease, chronic subcutaneous infusion of deferrioxamine being remarkably effective at reducing hepatic iron overload.

Increased body iron stores in elite road cyclists

BACKGROUND

One third of French elite road cyclists were found to have hyperferritinemia on antidoping control tests performed during the Tour de France in 1998.

PURPOSE

This study was undertaken to determine whether hyperferritinemia corresponded to elevated body iron stores or not and, affirmatively, what were its mechanism, its clinical consequences, and its spontaneous course.

METHODS

83 elite road male cyclists presenting with hyperferritinemia, defined as serum ferritin level greater than 300 microg.L-1, were studied with respect to consumption of iron and other drugs, serum iron tests, HFE mutations, and hepatic iron concentration (HIC; N < 35 micromol.g-1 dry weight).

RESULTS

All cyclists were asymptomatic and had normal physical and cardiac examination. Their median (range) serum ferritin, serum iron, and transferrin saturation levels were 504 microg.L-1 (306-1671), 20 micromol.L-1 (8.5-36.3), and 39% (20-76), respectively. HIC was increased in 24/27 up to 187 micromol.g-1. Allelic frequency of the H63D mutation was increased in cyclists when compared to controls (P = 0.04). However, iron tests did not differ according to HFE genotypes. Most cyclists (89%) had been supplemented with iron. The median iron supplementation was 25.5 g (range: 1.4-336) and correlated well (P = 0.002) with serum ferritin. Evolution of serum ferritin levels did not differ whether cyclists had been continuing iron supplementation or not.

CONCLUSION

Hyperferritinemia in elite road cyclists accounted for increased body iron stores caused by and persisting after cessation of excessive iron supplementation. Even when mild, iron excess may expose to long-term complications and should be removed, at least at the time when professional cyclists retire. To prevent iatrogenic iron overload, supplementation with iron must be done according to serum ferritin follow-up and not either blindly or on the basis of serum iron determination only.

[Quantification of iron overload]

Iron overload involves primarily hepatocytes in case of digestive hyperabsorption (hemochromatosis and dyserythropoiesis) and macrophages in case of transfusional excess. Serum iron and transferrin saturation are poorly correlated with the degree of iron overload. Serum ferritin is a better reflect of iron stores but numerous clinical conditions, unrelated to variations of iron load, can increase the serum level. Biochemical determination of liver iron overload is the gold standard of iron quantification and well correlated to the level of iron burden appreciated by the amount of iron removed by venesection, but its determination necessitates a liver biopsy and is dependant of sampling error in case of heterogeneous iron deposits (cirrhosis). The sensitivity of computed tomography is insufficient, beeing unable to detect iron overload below 5 times the normal liver iron load, especially in case of associated steatosis. Magnetic resonance imaging is a valuable tool when using T2 weighted gradient echo sequences on 1.5 Tesla magnet and permits non invasive iron overload quantification.

The RETAIN project: DICOM teleradiology over an ATM-based network. Radiological Examinations Transfer on an ATM Integrated Network

The RETAIN project (Radiological Examinations Transfer on an ATM Integrated Network) has aimed at testing videoconferencing and DICOM image transfers to get advice about difficult radiological cases over an asynchronous transfer mode (ATM)-based network, which affords a more comfortable interface than narrow-band networks and allows exchange of complete image series using the DICOM format of studies. For this purpose, an experimental ATM network was applied between six university hospitals in four different countries. An assessment of the functionalities of the system was performed by means of log-file analysis, video recording of the sessions and forms filled out by the participants at the end of each session. Questionnaires were answered by the users at the end of the project to bring out perspectives of utilisation and added value. We discussed 43 cases during 20 sessions. For technical or organisational problems, only 20 of the 36 planned sessions took place. The throughput over ATM (10.5 Mbit/s, 20 times faster than six ISDN B-channels) was adequate. Despite the experimental configuration of the network, the system was considered as satisfactory by all the physicians. In 72 % of the sessions, the expected result (answer to the question) was gained. By common consent, videoconferencing was unanimously regarded as a prominent tool in improving the interaction quality. Asynchronous transfer mode is an efficient method for fast transferring of radiologic examinations in DICOM format and for discussing them through high-quality videoconferencing.

Magnetic resonance iron-free nodules in genetic hemochromatosis

OBJECTIVE

In hemochromatosis, areas of normal hepatic magnetic resonance (MR) signal intensity indicate the presence of iron-free-nodules, which are strongly suspected of being neoplastic. The goal of the study was to define the prevalence and the nature of these iron-free MR nodules at the time of diagnosis in 116 patients included in a prospective study assessing the accuracy of MR imaging (MRI) in the quantification of liver iron overload.

METHODS

Seventy-nine of the 116 patients had homozygous hemochromatosis on a phenotypic basis. Fifteen-millimeter-thick contiguous slices were performed using T1- and T2-weighted gradient echo sequences with a 0.5 Tesla magnet.

RESULTS

Six of 79 homozygous hemochromatotic patients had one or more MR iron-free nodules. Five of the six patients proved to have malignant tumors. Four of six iron-free nodules were hepatocellular carcinoma (5% in the hemochromatosis group and 17.5% in hemochromatotic patients with severe fibrosis).

CONCLUSIONS

The present data confirm the high prevalence of liver cancer at the time of diagnosis, mainly in cirrhotic patients greater than 45 years of age, and indicate that, when performing MRI for liver iron quantification, a complete hepatic MRI examination is preferable to a simple signal measurement in patients at risk for hepatocellular carcinoma.

Influence of the teleradiology technology (N-ISDN and ATM) on the inter-hospital management of neurosurgical patients

We set out to assess the influence of a teleradiology network on the relations between a general hospital and a 100 km distant university hospital in the context of neurosurgical emergencies, and compared a commercially available technology, N-ISDN (Narrowband Integrated Service/Digital Network), to an emerging technology, ATM (Asynchronous Transfer Mode). The evaluation was conducted using records of advice request calls and patient transfers. Three phases were considered: without teleradiology, with transfer of digitized images over N-ISDN at 64 kbps, and with an experimental ATM network at 10.5 Mbps with DICOM image transfers and videoconferencing. Additionally, staff meetings over ATM videoconferencing were set up. To assess the ATM service, we used log files and questionnaires, 108 advice requests were studied over a 18 month period. The average transmission time for one examination was 38 s with full DICOM image resolution over ATM, versus 150 s with 10:1 JPEG (Joint Photographic Expert Group) compression over N-ISDN. Up to 50% unnecessary patient transfers were avoided. Advice requests increased fourfold, and non-urgent advice requests increased from 0 to 21%. Despite the experimental configuration of the ATM network, the service gave satisfaction to all the physicians. Videoconferencing was unanimously regarded as a prominent tool to improve the quality of interaction. It was particularly useful for non-urgent cases and distant staff meetings. Teleradiology can improve the relations between hospitals through an increase of urgent and non-urgent advice requests. Asynchronous transfer mode is an efficient way for fast transfer of radiological examinations in DICOM format and for discussing them through high-quality videoconferencing.

Analysis of cerebrovascular diseases by a new 3-dimensional computerised X-ray angiography system

We set out to validate the concept of three-dimensional (3D) angiography. We evaluated the sensitivity and the quality of morphological analysis mode possible by an experimental system for imaging cerebrovascular disease versus standard digital subtraction angiography (DSA). The system, the 3D Morphometer, is a computerised X-ray angiography unit capable of acquiring a set of two-dimensional (2D) projections during a rotation and then reconstructing a 3D volume from them. We studied 78 patients with suspected cerebrovascular disease. 3D and 2D images (standard 2D DSA performed during the same procedure), were reviewed blindly to assess detection and display of morphological characteristics of cerebrovascular diseases. We found 53 aneurysms, 22 arteriovenous malformations and two venous angiomas. On 3D angiography we detected two aneurysms we missed on 2D angiography. In 47 aneurysms on which further data were obtained during surgery or embolisation, the 3D angiography allowed more accurate analysis of the neck and surrounding vessels in cases in which the 2D angiographic findings were doubtful. Assessment of arteriovenous malformations was equivalent with both techniques. Under the conditions of our study, the technical constraints being the same for both methods, 3D angiography was superior to 2D angiography. Implementation on C-arm vascular systems is being evaluated.

[Test of a teleradiology network based on ATM (asynchronous transfer mode)]

The retain project (Radiological Examination Transfer on ATM Integrated Network) consisted in teleradiology trials focused on pediatric imaging between two university hospitals. Rennes (France) and Barcelona (Spain) using an integrated broadband communication network based on ATM (asynchronous transfer mode), as part of a European research program. The network used was a full 10 Mbits/s ATM network directly connected to local PACSs (medical imaging hospital networks). One important reason to explicitly consider ATM for medical imaging is that multimedia applications on such networks allow integration of digital data and person-to-person communication. The utility of broadband communication for teleradiology has been confirmed. High quality video and sound are important for both human communication and medical video transfer. The project led to guidelines regarding technical options still open to improvement.

Hemochromatosis: diagnosis and quantification of liver iron with gradient-echo MR imaging

PURPOSE

To assess the role of magnetic resonance (MR) imaging in detection and quantification of liver iron overload.

MATERIALS AND METHODS

MR imaging at 0.5 T was prospectively performed on 77 patients (67 with liver iron overload and 10 without) who underwent a liver biopsy with biochemical determination of the liver iron concentration (LIC) (normal, < 36 mumol per gram of liver tissue [dry weight]). Ratios of signal intensities and liver T2 relaxation time were calculated from images obtained with spin-echo and breath-hold gradient-echo (GRE) sequences.

RESULTS

Liver-to-tissue signal intensity ratios were better correlated with LIC than T2 relaxation time. Long-echo-time GRE sequences were the most sensitive for detection of slight overload. Thus, high sensitivity (94%) and specificity (90%) were obtained with a liver-to-fat ratio threshold of 1. The quantification of iron with MR imaging was accurate when the LIC was 80-300 mumol/g. For heavy overload, above 300 mumol/g, quantification was impossible owing to complete signal loss. Pancreatic and splenic signal intensity were unchanged in most cases.

CONCLUSION

This method, which can be improved by using more sensitive sequences with a high-field-strength system, should be competitive with biopsy for the diagnosis of substantial liver iron overload.

Magnetic resonance imaging and assessment of liver iron content in genetic hemochromatosis

Computed tomography (CT) scanning is not highly sensitive in the assessment of liver iron content and magnetic resonance imaging (MRI) appears to be more efficient. The aim of this study was to determine the effectiveness of MRI in the evaluation of liver iron content using a standard spin-echo technique. The study included 23 patients with genetic hemochromatosis and 24 non-iron-overloaded patients as controls. A comparison was made of: (a) MRI signal intensity of liver, spleen, paravertebral muscles and subcutaneous adipose tissue using two different spin-echo sequences (SE 500/28; SE 2000/28,56); (b) liver attenuation determined by a single energy CT scan; and (c) a biochemical determination of hepatic iron. There was a significant decrease in liver signal intensity in the genetic hemochromatosis group (256 +/- 201, mean +/- S.D.) compared with the control group (801 +/- 413, p less than 0.001), but there was no correlation with liver iron concentration. However, such a correlation was found and was even more highly significant than in CT when the ratio between the liver and another organ was taken into account. For a lower limit of liver/spleen ratio calculated at 0.46 (mean 2 S.D. in the control group), the specificity (0.96) of MRI was satisfactory, but the sensitivity (0.78) remained insufficient (MRI being unable to detect an iron overload of up to 125 mumol/g). Hopefully, these results might be improved in the near future by using more sensitive sequences such as gradient echo sequences.

Superparamagnetic iron oxide: clinical time-response study

Superparamagnetic iron oxide (AMI 25) is a promising new contrast agent for imaging the reticuloendothelial-system. Iron oxide crystals possess a large magnetic susceptibility and enhance proton relaxation rates, especially transverse relaxation (T2). In order to guide the clinical utilization of this contrast media we analyzed 4 patients with malignant lesions of the liver before and after slow intravenous administration (20 mumol Fe/kg) of AMI 25. We performed two magnetic resonance (MR) sequences at different times using a 0.35 T magnet. MR signal-to-noise ratio (SNR) of the reticuloendothelial system (particularly the liver SNR) decrease promptly. The maximum decrease in SNR (67-72% for the liver, 46-65% for the spleen, 23-41% for the bone marrow) is observed 3 h after injection (P less than 0.01). However, except the peak of contrast enhancement in T1-weighted sequences of splenic tissue, the curve describes a plateau within 30 min and 6 h, allowing a delay between injection and imaging. T2-weighted sequences give a greater contrast-to-noise ratio (CNR) by adding the spontaneous tumor contrast to the effect yielded by AMI 25. These results suggest that images must be acquired between 1 and 6 h after intravenous administration of superparamagnetic iron oxide.

[Radiologic aspects of a case of Waldmann's disease]

The Waldmann's disease or intestinal lymphangiectasia is a rare disease. We observed a case which occurred in a 14 years old boy. The disease was discovered in the screening of an intermittent diarrhea. The diagnosis was suspected on biological signs of protein-losing enteropathy and the presence of lymphangiectasias seen during endoscopy. The lymphography was conclusive showing the abnormal opacification of the mesenteric region. The other examinations were also important to assert the idiopathic origin of the disease.

[Anterior rectal duplication. Value of ultrasonic diagnosis]

A case of neonatal anterior rectal duplication is reported. Abdominal ultrasonography revealed a prerectal cystic mass. The different types of rectal duplications and the main differential diagnosis are described. Mechanical obstruction and neoplastic risk make early surgery necessary.

[The value of computerized tomography in the assessment of hepatic iron overload in genetic hemochromatosis]

The aim of the present study was to evaluate the effectiveness of single-energy computed tomography in determining iron overload in idiopathic hemochromatosis, with special reference to slightly overloaded cases. Liver attenuation was determined in 100 patients (46 cases of idiopathic hemochromatosis, 32 cases of chronic liver disease, and 22 normal controls). The iron load was determined for the first two groups by biochemical determination of liver iron concentration (performed in all but 12 subjects in the chronic liver disease group) and hepatic histologic grading. The main results for liver attenuation (upper normal limit, 72 Hounsfield units) showed that despite a high specificity (0.96), this parameter was of low sensitivity (0.63). Although mean liver attenuation in idiopathic hemochromatosis (77 +/- 14) was significantly higher than in chronic liver diseases (53 +/- 17; p less than 10(-4], and normal controls (66 +/- 3; p less than 10(-3], and despite an overall good correlation between liver attenuation and liver iron concentration (r = 0.72; p less than 10(-3], liver attenuation was unable to detect moderate iron overload. Fourteen of 18 patients with a liver iron concentration of less than 150 mumol/g dry liver wt had liver attenuation values of less than 72. Moreover, 3 of 18 subjects with a liver iron concentration of greater than 150 had a liver attenuation of less than 72. Of these 17 false-negatives, only 7 could be attributed to associated steatosis. On the whole, single-energy computed tomography, when used on a routine basis for diagnosing iron overload, is of limited clinical value in idiopathic hemochromatosis due to its poor sensitivity.(ABSTRACT TRUNCATED AT 250 WORDS)