E. de Kerviler

CT-guided biopsies in lung infections in patients with haematological malignancies

CT-guided transparietal lung biopsy in imaging makes it possible to find the pathogenic agent in half of all fungal infections and most bacterial infections (sensitivity=55%, specificity=100%). Performance is decreased in consolidations (50% of infections) compared to masses. Complications, pneumothorax, alveolar bleeding and hemoptysis are generally benign and rarely (<5%) require specific treatment. On the other hand, the diagnostic performance increases significantly with the calibre of 18G co-axial systems compared to 20G. The risk is not related to the number of samples or platelet levels.

Le diagnostic d'un ganglion tumoral

Resume Les techniques d’imagerie sont actuellement multiples et ont toutes des avantages et des limites. La radiologie standard (numerique) reste toujours d’actualite. Le diagnostic tomodensitometrique d’une adenopathie est facile mais la determination de sa nature maligne ou benigne est beaucoup plus difficile. Quelques petits signes permettent de s’en sortir. L’imagerie par resonance magnetique souffre des memes limites mais permet de diagnostiquer un ganglion cicatriciel fibreux pour ne pas le confondre avec un ganglion tumoral. L’echographie doppler puissance donne une analyse de l’angio-architecture d’un ganglion en revelant sa modification lorsqu’il est tumoral. La lympho-scintigraphie isotopique identifie facilement le ganglion sentinelle. Le PET-SCAN associe l’imagerie morphologique a l’imagerie fonctionnelle et ameliore la precision diagnostique des adenopathies tumorales. Quelques exemples de strategies diagnostiques de certains cancers sont exposes.

Biopsies percutanées sous scanner

The number of biopsy requests continuously increases over the years. Similarly, lesions that are not amenable to CT-guided biopsy are exceptional due to improved imaging guidance and technical advances. The needle tract should preferably go through fat, which is less painful and safer. The biopsy should be painless with the use of local anesthetics complemented by intravenous sedation. Blunt introducers and hydrodissection techniques create access to lesions without injury to vessels, bowel loops and fascias. The biopsy samples should be processed in accordance with the suspected diagnosis.

Risque IRM : règles de sécurité, incidents et accidents

It is now accepted that MR imaging does not present any biological risk for humans, even in cases of repeated exposure. However, several of the MR components (magnetic field, gradients, RF pulses, electrodes...) may cause some inconveniences to patients, most of them being reversible. However, severe accidents have been reported. Even though screening of patients for MR imaging eligibility is performed to identify patients with contra-indications to MRI, the lack of vigilance or the ignorance of certain basic safety requirements could lead to serious adverse effects, including death. The goal of this article is to review the various accidents reported with MRI, to explain their mechanism, and to describe means of prevention.

Iron overload of hematological origin: Validation of a screening procedure for cardiac overload by MRI in routine clinical practice

PURPOSE Screening for cardiac iron overload is generally done by magnetic resonance imaging (MRI) and demonstrated by a shortening of the myocardial T2* below 20 ms at 1.5 Tesla. This measurement was validated with a specific sequence and the CMRTools(®) calculation software (reference technique). The objective of this study was to validate the use of sequences and software programs that are available in routine clinical practice to screen for iron overload. MATERIAL AND METHODS First, a phantom of 11 tubes with a T2* between 4 and 33 ms was tested at three sites that had MRI machines of different brands. Second, the myocardial T2* values of 75 patients were measured in routine clinical practice using two methods. The first method used the reference sequence specially installed in the machines associated with the CMRTool software. The second method used the standard acquisition sequences available in the machines followed by calculation on a computer spreadsheet. RESULTS In the phantom, the mean of the differences in T2* between each machine was 0.6 ms. Thirteen patients had a lowered T2* value with the reference technique. Three cases were poorly classified using the routine technique and corresponded with false positives of low overload (T2* between 18 and 20 ms). CONCLUSION Screening for myocardial iron overload can be done by MRI by using sequences and calculation software available in routine clinical practice during the same examination as the one for the evaluation of hepatic iron overload.

Imagerie radiologique et TEP scanner des lymphomes de l’adulte et de l’enfant

Imaging and PET-CT of adultand childhood lymphoma Malignantlymphomas are lymphoproliferative disorders arising in both lymphoidtissue and non-lymphoid organ systems. Treatment rarely is surgical,and currently relies on a combination of chemotherapy and radiationtherapy. The role of imaging is to determine the spread of the disease,to identify targets and to assess therapeutic response. Imaging techniquesmainly use morphological criteria, and may underestimate infiltrativedisease, as observed in bones. The frequent presence of residualmasses after treatment usually prevents classification of patientsas complete response. Over time, positron emission tomography (PET) withF18-fluorodeoxyglucose (FDG) has become a prominent part of theworkup at diagnosis and during follow-up. Recently, PET has been integratedin the revised response criteria for malignant lymphoma.

Diagnostic strategy for the assessment of axillary lymph node status in breast cancer

The nodal status in breast cancer is a major prognostic factor in terms of survival. It also plays a role in the therapeutic decision-making process. Therefore, the evaluation of lymph node involvement in breast cancer is imperative in establishing a personalized treatment scheme. The sentinel lymph node procedure has proved successful for small breast tumors (T1-T2), limiting axillary lymphadenectomy and its side effects without changing overall survival. Even so, a substantial number of women must undergo axillary lymphadenectomy during a second surgery when the analysis of the sentinel node discloses major nodal involvement. Imaging can improve patient selection, especially those who appear eligible for immediate axillary lymphadenectomy. Ultrasound is able to depict morphological abnormalities in the lymph nodes such as cortical thickening, peripheral vascularization, hilar infiltration and loss of the kidney-shaped appearance of a normal node. When ultrasound is negative, the risk of massive nodal involvement is limited, thus allowing the oncologist to take an approach with the sentinel lymph node procedure. Magnetic resonance imaging (MRI) can also be useful in detecting pathological lymph nodes, particularly with diffusion-weighted MRI sequence.

Imagerie TDM et IRM de l’angiogenèse tumorale

Angiogenesis is the process of activating dormant endothelial cells to form new vessels, after stimulation and it is essential in tumor growth. In many types of cancer, angiogenesis results from the activation of oncogenes that stimulate the production of Vascular Endothelial Growth Factor (VEGF). However, these newly formed vessels have a great number of abnormalities: increased density of fragile and hyper-permeable microvessels, arterial-venous shunts, caliber abnormalities and flow instabilities susceptible to flow direction inversion according to interstitial pressure. Anti-angiogenic treatments inhibit VEGF activity, perceived as structural and functional normalization of the microvascular pattern, such as reduced density of microvessels and restored morphology of the remaining ones. Conventional imaging techniques are not sensible to these changes, at best they show tumor size stabilization, hence the need of new techniques. Microvascularization imaging can be achieved by detecting functional disturbances to blood flow and not by showing the microvasculature per se. These techniques are based in quantifying the enhancement in tumor due to the passage of contrast agent after injection or protons labeled by a magnetic field. Through these measurements, one can derive interstitial and blood volumes as well as the tissue perfusion and capillary wall permeability. Microvascular imaging has greatly benefited from the improvements seen in CT and MRI equipment allowing large volume coverage with high spatial and temporal resolutions as from the evolutions in the methods to calculate, present and compare maps of the microcirculation and its heterogeneity. However, software to analyze microvascularization are still rare, limiting the techniques application and validation in large scale. Nevertheless, imaging of the microcirculation is useful throughout the care of the oncological patient: it can reinforce the suspicious nature of a lesion, suggest anti-angiogenic treatment efficacy in hypervascular lesions, and show early treatment response before morphological changes as in RECIST criteria.

Nouveaux développements en IRM en oncologie

The technological improvements in Magnetic Resonance Imaging (MRI), allow the analysis of biomarkers such as cellular density, microcirculation and metabolism, which characterize tumor developments. This functional imaging of biomarkers improves morphological data and diagnostic performances in oncological MRI. Full body MRI takes an increasing place in patients’ management in oncology.RésuméLes avancées technologiques en imagerie par résonance magnétique (IRM) permettent à présent d’analyser certains biomarqueurs (densité cellulaire, microcirculation et métabolisme) caractérisant le développement tumoral. L’imagerie dite ≪ fonctionnelle ≫ de ces différents biomarqueurs tumoraux tend à compléter les données de l’imagerie morphologique classique et à améliorer les performances diagnostiques, prédictives de l’IRM en cancérologie. Enfin, les derniers développements technologiques, permettant l’utilisation conjointe demultiples antennes, permettent d’examiner le corps entier. Ainsi, l’IRM corps entier prend une place croissante dans la prise en charge des patients en oncologie.

Hémorétropéritoine massif après ablation percutanée par radiofréquence d'une tumeur rénale: traitement par embolisation artérielle en urgence

ablation par radiofréquence guidée par l’imagerie est une solution alternative efficace à la chirurgie pour le traitement des cancers du rein (1, 2). Récemment, elle a été utilisée avec succès pour traiter des tumeurs rénales kystiques suspectes de malignité (2). Cette technique, moins invasive que la chirurgie, a un taux de succès compris entre 90 et 100 % (2). Cependant, elle peut être responsable de complications vasculaires, telles qu’un hématome périrénal ou, très rarement, une fistule artérioveineuse, mais qui ne mettent pas en jeu le pronostic vital (2). À notre connaissance, il n’a pas été rapporté de cas de complication vasculaire sévère due à cette technique, ayant eu un retentissement hémodynamique majeur, ayant nécessité un traitement hémostatique d’urgence. Nous rapportons un cas d’une masse rénale kystique de type III selon la classification de Bosniak (3) traitée par radiofréquence et dont l’évolution, marquée par un hémo-rétropéritoine sévère ayant mis en jeu le pronostic vital, a nécessité, en urgence, une embolisation artérielle sélective percutanée.ablation par radiofréquence guidée par l’imagerie est une solution alternative efficace à la chirurgie pour le traitement des cancers du rein (1, 2). Récemment, elle a été utilisée avec succès pour traiter des tumeurs rénales kystiques suspectes de malignité (2). Cette technique, moins invasive que la chirurgie, a un taux de succès compris entre 90 et 100 % (2). Cependant, elle peut être responsable de complications vasculaires, telles qu’un hématome périrénal ou, très rarement, une fistule artérioveineuse, mais qui ne mettent pas en jeu le pronostic vital (2). À notre connaissance, il n’a pas été rapporté de cas de complication vasculaire sévère due à cette technique, ayant eu un retentissement hémodynamique majeur, ayant nécessité un traitement hémostatique d’urgence. Nous rapportons un cas d’une masse rénale kystique de type III selon la classification de Bosniak (3) traitée par radiofréquence et dont l’évolution, marquée par un hémo-rétropéritoine sévère ayant mis en jeu le pronostic vital, a nécessité, en urgence, une embolisation artérielle sélective percutanée.