Les lésions hépatiques contenant de la graisse comprennent une large gamme de diagnostics différentiels, et l’imagerie permet le plus souvent de les distinguer. L’analyse de la graisse intralésionnelle s’appuie sur la TDM, l’échographie ou l’IRM, mais cette dernière est la technique la plus sensible en permettant de différencier la graisse macroscopique et microscopique. Les lésions hépatiques pouvant contenir de la graisse présentent une sémiologie caractéristique en contraste spontané, notamment en IRM. La présence de graisse peut être un attribut principal de la lésion, un critère auxiliaire ou une particularité plus inhabituelle. Cependant, la présence d’un contingent graisseux peut être piégeuse en modifiant l’aspect caractéristique de certaines lésions sur les séquences habituelles à l’IRM. Une lésion graisseuse intra-hépatique peut correspondre à des pseudo-lésions stéatosiques, mais peut également être le signe d’une lésion hépatocytaire primitive bénigne ou maligne. La détection d’un contingent graisseux intralésionnel s’intègre désormais dans les algorithmes diagnostiques des cancers primitifs du foie, mais également comme un outil utile pour le sous-typage des lésions hépatocytaires. Confronté à la présence de lésions graisseuses en imagerie, le raisonnement radiologique doit permettre d’établir un diagnostic formel de pseudo-lésions stéatosiques ou de certaines lésions hépatocytaires, mais également d’évoquer les principaux diagnostics différentiels et de proposer la réalisation d’une biopsie, dans certains cas, afin de ne pas méconnaître les diagnostics plus difficiles des lésions primitives atypiques ou mésenchymateuses. Fat-containing liver lesions include many diagnoses, and they are most often distinguished by imaging. The analysis of intralesional fat is based on CT, ultrasound or MRI, but the latter is the most sensitive technique in allowing macroscopic and microscopic fat to be differentiated. Hepatic lesions that may contain fat present a characteristic semiology, especially on MRI. The presence of fat may be a primary attribute of the lesion, an ancillary feature, or a more unusual feature. However, the presence of a fatty contingent can be tricky, impacting the characteristic appearance of certain lesions. Intrahepatic fatty lesions may correspond to pseudo-steatosic lesions, but may also be the sign of a benign or malignant primary hepatocellular lesion. The detection of an intralesional fatty contingent is now integrated into the diagnostic algorithms of primary liver cancers, but also as a useful tool for the subtyping of hepatocyte lesions. Confronted with the presence of fatty lesions in imaging, radiological reasoning should make it possible to establish a formal diagnosis of steatotic pseudo-lesions or of certain primary liver lesions, but also to raise the possibility of differential diagnoses, so as not to miss the more difficult diagnoses, such as atypical primary liver tumors or mesenchymal lesions.

L’exploration hépatique par tomodensitométrie (TDM) est un des actes les plus fréquents dans la pratique clinique d’un radiologue. Cependant, les protocoles d’imagerie TDM hépatique sont encore insuffisamment standardisés, avec une variabilité intercentres concernant à la fois le nombre de phases d’acquisition et le protocole d’injection de produit de contraste iodé incluant tout autant le délai d’acquisition de chaque phase que la quantité d’iode utilisée. L’harmonisation des protocoles d’injection, qui doivent s’adapter à la fois au patient et au contexte clinique spécifique, fait l’objet d’intenses débats actuellement. Dans cet article, nous exposons une revue de la littérature autour des techniques d’exploration hépatique par TDM pouvant permettre de proposer un protocole d’imagerie TDM hépatique standardisé mais également d’apporter un éclairage sur les questions encore incomplètement tranchées par les données de la recherche. Cette évaluation scientifique a été réalisée sous l’égide de la SIAD, en lien avec le CIRTACI et la SFR.

Le coloscanner, également appelé coloscopie virtuelle, est une technique d’imagerie radiologique simple qui permet d’identifier les polypes adénomateux du côlon de plus de 6mm. Sa sensibilité et sa spécificité dépendent avant tout de la qualité de la préparation colique et de la technique d’examen. Il est absolument nécessaire de réaliser l’examen après une préparation colique rigoureuse, spécifiquement dédiée au coloscanner et il faut compléter cette préparation par des techniques de marquage des selles et des liquides. Il est ensuite nécessaire de réaliser l’examen selon une méthodologie qui est désormais bien rodée. Il est ainsi possible d’obtenir une sensibilité du coloscanner de l’ordre de 90 % pour les polypes adénomateux de plus de 10mm avec une spécificité estimée de 96 %. L’objet de cet article est de détailler les étapes de réalisation d’un coloscanner qui ont été mises au point depuis une quinzaine d’années.

Introduction: The prognosis of HCC depends amongst others factors upon tumor differentiation. So far, the latter can be assessed by histology only. In practice this is not always available and may impair management. To assess the added value of Gd-BOPTA-enhanced hepatobiliary phase imaging to distinguish hepatocellular carcinomas according to their pathological differentiation. Methods: This prospective study was IRB approved and the requirement for informed consent was waived. Twenty five patients with 26 resectable HCC BCLC A (8 well differentiated, 13 moderately differentiated and 5 poorly differentiated) naïve of any treatment, and who underwent orthotopic liver transplantation or hepatectomy were included. All patients underwent a preoperative liver MRI after Gd-BOPTA injection included delayed hepatobiliary phase acquisitions. Two readers reviewed all images in terms of signal intensity (SI) features on unenhanced, and hepatobiliary phase images to establish the Lesion-to-Liver contrast Enhancement Ratio (LLCER). The LLCER was correlated to pathological differentiation (Mann Whitney, ROC). Results: The LLCER of well differentiated HCC (mean 14.2% ± 14.2) was significantly higher than that of moderately to poorly differentiated HCC (mean -6.26% ± 7.1) (p < 0.0002). Using a cut-off value of +4.6% yielded a 94% specificity and 100% sensitivity for discriminating well differentiated from moderate to poorly differentiated HCC. Conclusion: LLCER at the hepatobiliary phase after Gd-BOPTA injection allows the differentiation of well-differentiated from moderately to poorly differentiated HCC.

Diagnosis: Intramuscular hydatid cyst. Magnetic resonance imaging (MRI) showed a multivesicular cyst located in the latissimus dorsi muscle (Figure 1); a hydatid cyst was suspected. The diagnosis was rapidly confirmed by a serologic test for Echinococcus granulosus (via enzyme-linked immunosorbent assay [ELISA], 71 kUA/L, and Western blot method, showing 1 specific band [7 KDa]). The patient was started on albendazole 1000 mg per day and referred to surgery. The mass was excised by muscle sparing and without any spillage of intracystic material. Perioperative macroscopical inspection showed multiple daughter vesicles of varying sizes (Figure 2), and parasitological examination confirmed the diagnosis of E. granulosus, with the presence of multiple scolices. During the postoperative course, the patient received 2 other courses of 1 month of albendazole, and serologic control showed a decrease in the ELISA titers, which became negative after 1 year. Hydatid disease is a zoonosis caused by the larval stages of E. granulosus, which is endemic in certain parts of the world [1]. Clinicians may be faced with imported cases in nonendemic regions. It is often underdiagnosed because of its asymptomatic development over the years. Parasitic etiology should be considered as a differential diagnosis of soft tissue tumor. Intramuscular hydatid cysts represent a rare presentation of this infection, which may be confused with other lesions such as tumors or may mimic other pathological processes. Clinicians must bear in mind the possibility of primary parasitic involvement at unusual sites [2–9]. Ultrasonography and MRI are useful in the diagnosis, showing the size, localization, and type of cyst with a sensitivity of 95%, and if vesicular fibrils are present, the sensitivity increases to 100% [10]. Serological tests can also be useful in the diagnosis but can sometimes give false-negative results [10]. To avoid dissemination of the cysts that can cause an anaphylactic shock, diagnosis puncture should not be performed. Surgery must be cautious; hypertonic saline solution must be spread on the cysts in case of rupture during surgery and adrenaline made available in case of anaphylactic shock.

Following interventional radiology procedures, bleeding can occur in 0.5 to 4% of the cases. Risk factors are related to the patient, to the procedure, and to the end organ. Bleeding is treated usually by interventional radiologists and consists mainly of embolization. Bleeding complications are preventable: before the procedure by checking hemostasis, during the procedure by ensuring the accurate puncture site (with ultrasound or fluoroscopy guidance) or by treating the puncture path using gelatin sponge, curaspon(®), biological glue or thermocoagulation, and after the procedure by carefully monitoring the patients.

Les anévrismes des artères viscérales sont des pathologies rares dont la mortalité en cas de rupture est estimée entre 25 et 70 % dans la littérature. Leur traitement est principalement du ressort de la radiologie interventionnelle. Les techniques d’embolisation dépendent de la localisation, de l’organe atteint, de l’anatomie artérielle locorégionale et de l’expérience de l’opérateur. Le succès après traitement par radiologie interventionnelle est supérieur à 90 %. La principale complication est la reperméabilisation de l’anévrisme, d’où l’importance de la surveillance post-thérapeutique qui est réalisée au mieux par l’IRM.

Les saignements post-radiologie interventionnelle s’observent dans 0,5 à 4 % des cas. Les facteurs de risque sont liés au patient, au geste et à l’organe traité. Leur traitement peut souvent être réalisé par les équipes de radiologie interventionnelle, principalement par embolisation. Ces complications hémorragiques peuvent être prévenues : avant le geste, par vérification de l’hémostase, pendant le geste, en s’assurant d’une ponction au bon site (repérage échographique ou scopique) et/ou en traitant le trajet de ponction (curaspon, colle biologique, thermo-coagulation). Après le geste, il faut s’assurer d’une bonne surveillance du patient.

Visceral artery aneurysms are rare but their estimated mortality due to rupture ranges between 25 and 70%. Treatment of visceral artery aneurysm rupture is usually managed by interventional radiology. Specific embolization techniques depend on the location, affected organ, locoregional arterial anatomy, and interventional radiologist skill. The success rate following treatment by interventional radiology is greater than 90%. The main complication is recanalization of the aneurysm, showing the importance of post-therapeutic monitoring, which should preferably be performed using MR imaging.

Introduction: Our objective was to report the impact of the implementation within an imaging department of a team dedicated to dose and image quality in computed tomography (CT).

The management of colorectal intrahepatic metastases before resection is multidisciplinary and radiologists and nuclear medicine specialists play a major role. In accordance with the French National Guide for appropriate use of diagnostic imaging, the approach should be multimodal: a chest-abdomen and pelvic (CAP) CT scan and hepatic MRI are mandatory while PET-CT provides important additional information, in particular on intra-abdominal extrahepatic metastases. This multimodal approach emphasizes the importance of early and appropriate use of imaging in these patients, as well as the central role of multidisciplinary meetings in oncology.

La prise en charge avant résection des lésions secondaires intra-hépatiques est multidisciplinaire, le rôle des radiologues et des médecins nucléaires y est majeur. Conformément au guide du bon usage des examens d’imagerie, l’approche doit être multimodale : la tomodensitométrie thoraco-abdomino-pelvienne et l’IRM hépatique sont incontournables ; la TEP-TDM apporte des éléments importants, notamment pour les métastases intra-abdominales extra-hépatiques. Cette approche multimodale souligne l’importance d’une prise en charge adaptée et précoce de ces patients en imagerie, ainsi que le rôle central des réunions de concertation pluridisciplinaire en oncologie.

La prise en charge de patients présentant une tumeur hépatocytaire bénigne repose, pour une large part, sur les données d’imagerie ; le diagnostic d’hyperplasie nodulaire focale (HNF) doit être posé en IRM de manière certaine, car aucun autre élément clinique ou biologique ne peut aider au diagnostic. L’identification de lésions de type adénome est tout aussi essentielle pour adapter la prise en charge. C’est dire si l’impact du compte rendu radiologique est majeur dans ces situations. Pour autant, les pièges diagnostiques existent. L’objectif de cet article est de présenter les clés du diagnostic des lésions hépatocytaires bénignes, mais également d’alerter sur les principaux pièges diagnostiques.

Management of patients with a benign hepatocellular tumor relies largely on imaging data; the diagnosis of focal nodular hyperplasia (FNH) must be made with certainty using MRI, because no other clinical or laboratory data can help diagnosis. It is also essential to identify adenomas to manage them appropriately. The radiological report in these situations is therefore of major importance. However, there are diagnostic traps. The aim of this paper is to present the keys to the diagnosis of benign lesions and to warn of the main diagnostic pitfalls.

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.

Purpose. - To validate the 2010 diagnostic criteria from the American Association for the Study of Liver Diseases (AASLD) for hepatocellular carcinoma (HCC) on MRI using the surgical liver specimen as a gold standard.Patients and methods. - A total of 21 liver transplant recipients were retrospectively included. Each underwent surgery because of HCC between January 2007 and January 2008. Pre-transplant MRI was performed on a 1.5 Testa MR unit. The T1W and T2W signal and kinetic contrast enhancement were correlated for each lesion with the surgical specimen. Lesion diameters between MRI and specimen were compared (Spearman). A multivariate model was created (R statistics software package) to predict the presence and grade of tumor differentiation (WHO, Edmonson Steiner).Results. - A total of 71 nodules were detected at histology, including 54 HCC (mean size: 25.3 mm) compared to 68 on MRI. There was moderate agreement (r = 0.58, P < 0.001) between the maximum lesion diameters measured on MRI and at histology. Wash-out on MRI provided an accuracy of 75% for the detection of HCC (sensitivity = 75 %, specificity = 76 %). Adding T2W hyperintensity to the AASLD criteria increased the sensitivity of MRI from 70.3% to 77.7% for the diagnosis of HCC and from 67.6% to 79% for nodules less than 20 mm in diameter, without affecting specificity. On multivariate analysis, wash out as a single variable was significantly associated with a diagnosis of HCC (P < 0.01, odds ratio 12.0, CI 95% [2.6-55.5]). T1W hyperintensity (P=0.04, odds ratio 5.4) and loss of signal on opposed-phase images (P=0.02, odds ratio 9.2) were predictive of good differentiation.Conclusion. - On MRI, the AASLD criteria or presence of wash out within a liver nodule in patients with underlying chronic hepatocellular disease are suggestive of tumoral transformation. The addition of T2W hyperintensity to the AASLD criteria increases the detection of HCC, especially nodules smaller than 20 mm. (C) 2011 Elsevier Masson SAS and Editions francaises de radiologie. All rights reserved.