[Phaeochromocytoma and paraganglioma]. / Phéochromocytome et paragangliome.

Phaeochromocytomas and paragangliomas (PPGL) are rare neuroendocrine tumors that arise from the adrenal medulla or sympathetic and parasympathetic ganglia. These tumors produce most often catecholamines in excess, causing hypertension and sometimes severe acute cardiovascular complications. The diagnosis is based on plasma or urines metanephrines measurements and on conventional and nuclear medicine imaging. Catecholamines-producing PPGL is very unlikely if levels are normal. The diagnosis of PPGL cannot be made without visualization of a tumor. Therapeutic management consists mostly of surgical excision, after drug preparation, and should be done in referral centers. About 40% of pheochromocytomas and paragangliomas occur in the context of an autosomal inherited syndrome, making genetic testing essential. The follow-up must be prolonged because a metastatic evolution or a recurrence can be observed in about 15% of the cases.

Radiological evaluation of response to treatment: application to metastatic renal cancers receiving anti-angiogenic treatment.

Targeted therapies have considerably improved the prognosis of patients with metastatic renal cancer (mRCC) but there are no reliable response assessment criteria reflecting the clinical benefits, because there is no regression in size, or it is delayed. Such criteria would help early identification of non-responders, who would then benefit from a change of treatment, and would avoid their being subjected to unnecessary side effects related to the treatment. We will review the imaging techniques currently available for evaluating tumour response in mRCC patients, including the response evaluation criteria in solid tumours (RECIST), the Choi criteria, the modified Choi criteria, and the CT size and attenuation criteria (SACT). We will also discuss functional imaging techniques, which are based on the physiological characteristics of the tumours, such as perfusion CT, magnetic resonance imaging or ultrasound (DCE-CT, DCE-MRI, DCE-US), diffusion MRI, BOLD MRI and new positron emission tomography (PET) tracers. It is not possible at present to propose a unanimously acknowledged criterion for evaluating tumour response to targeted therapy. However, there is a real need for this according to oncologists and the pharmaceutical industry, and radiologists need to be involved in reflecting on the subject.

Evaluation of a new disinfection procedure for ultrasound probes using ultraviolet light.

Following 183 ultrasound examinations, a randomized trial was conducted to compare three procedures for disinfection of probes under routine conditions: dry wiping with a soft, dry, non-sterile paper towel, antiseptic wiping with a towel impregnated with disinfectant spray and dry wiping followed by a 10 min ultraviolet C (UVC) cycle in a disinfection chamber. After ultrasonography, swabs were taken from transducer heads before and after cleaning and streaked onto plates that were then cultured. The number of colonies per plate was counted and organisms identified. The median microbial reduction was 100% for UVC, 98.4% for antiseptic wiping and 87.5% for dry wiping (P<0.001). The percentage of negative specimens was 88% for UVC, 16% for antiseptic wiping and 4% for dry wiping (P<0.0001). Microbial flora was isolated from 12 probes (6.6%) before cleaning, whereas specimens obtained after cleaning contained no pathogens except in one case after antiseptic wiping. UVC disinfection of ultrasound probe may provide a useful method for reducing the bacterial load under routine conditions.

[MR imaging of ano-perineal suppurations]. / IRM des suppurations ano-périnéales.

A good digital examination is usually sufficient for the diagnosis and the treatment planning of anal fistulae. Cross-sectional imaging techniques, however, can accurately identify deep abscesses and characterize complex fistulae. MRI is well suited for this examination, with almost no motion artifact, excellent contrast between muscles and fatty spaces, and multiplanar acquisition. A fistula starts from an internal opening in the digestive tube and can end in an abscess cavity or open at the skin at an external opening. The cryptoglandular anal fistulae (fistula-in-ano) are non-specific in origin and are usually simple, whereas specific fistulae are due to many diseases such as Crohn's disease, tuberculosis, trauma, radiation, colloid carcinoma, hidradenitis suppurative, actinomycosis or lymphoma and are often complex. MRI appears useful in the cases with recurrent fistulae, Crohn's disease, when the secondary orifice is atypically placed, during a multistep treatment for complex fistulae, or when an anal stenosis forbids a clinical or ultrasound examination. A good knowledge of the perineum anatomy is required for analysing the fistula tracts. The muscle planes separate fatty spaces which have an important role in the spread of the disease: sub-mucosal space, marginal space, intersphincteric space, postanal space of Courtney, supralevator space, and the two ischioanal spaces on both sides of the anal canal. The anal canal is surrounded by the ring-like internal sphincter, which continues the internal muscularis propria of the rectum, and the external sphincter, which is intermingled with the puborectalis muscle. We perform our MRI examination with an external phased array coil, and we place a cannula to identify the anal canal. The T2W sequences give the more interesting information, but the sequences with fat-suppression and gadolinium chelate injection are also very useful. The MRI examination allows the analysis of: 1) the location of the fistula tracts according to Park's classification, 2) the location of the internal opening, 3) the locations of the external opening(s), 4) the location of deep abscesses, 5) the long distance extensions, 6) the state of the ano-rectal wall and the perirectal spaces, 6) the damages of the anal sphincter.

[Diagnostic approach of pulmonary embolism by spiral angioscanner]. / Approche diagnostique de l'embolie pulmonaire par l'angioscanner spiralé.

Spiral volumetric computerized tomography (CT) allows the exploration of the whole chest during a single contrast injection and breath-hold. For the diagnosis of central pulmonary embolisms, the sensibility is between 78 and 98% and the specificity between 86 and 94% depending on the direct visualization of the endoluminal defect. Detection of intercurrent parenchymal pathologies or of non-obstructive arterial thrombi explain some false positive or inconclusive results of the ventilation-perfusion scintigraphy. Sub-segmental thrombi are less easily detected and sensibility for both central and sub-segmental embolisms is only 63%, explaining some rare false negatives of the CT on isolated sub-segmental embolisms. Chronic thrombi are outlying and contiguous with the arterial wall. They are associated with arterial stenosis, cut-off and loops and an oligemic mosaic pattern of the parenchyma. CT allows pre-operative staging before surgical recanalization and the intra-venous injection does not interfere with the arterial pressure. CT is a non-invasive, reliable and easily available technique which clearly plays an important role in the diagnosis of pulmonary embolism.

Reproducibility of coronary calcification detection with electron-beam computed tomography.

If coronary calcification scores obtained with electron-beam computed tomography (EBT) were proved to be correlated to coronary atherosclerosis, the reproducibility of the technique had to be assessed before being used for patient follow-up. A total of 150 patients, selected as a result of a cholesterol screening programme, were studied by EBT. Twelve contiguous 3-mm-thick transverse slices beginning on the proximal coronary arteries were obtained through the base of the heart. The amount of calcium was evaluated as the calcified area weighted by a coefficient depending on the density peak level. The value was expressed as a logarithmic scale. Intra-observer, inter-observer and inter-examination reproducibilities were calculated. They were 1.9, 1.3 and 7.2%, respectively. These results were good enough to allow the use of EBT for longitudinal studies. The influence of acquisition and calculation conditions on score computation were also analysed.

[Electron canon computed tomography. Technique and clinical applications in cardiac imaging]. / TDM à canon à électrons. Technique et applications cliniques en imagerie cardiaque.

Electron Beam CT (EBCT) was initially devoted to both dynamic and morphological cardiac studies. ECG gated slices acquired in 100 milliseconds produce cardiac images without motion artefacts. Intracavitary tumors and thrombus are clearly detected and EBCT contributes to the stagging and follow-up of masses. Exploration of congenital abnormalities such as pulmonary atresia can be performed even in newborns. EBCT allows the diagnosis of tiny modifications of coronary arteries, endocardium or pericardium. EBCT offers a new modality of cardiac imaging which gives complementary informations to other modalities.

[Angioscanner analysis using Imatron C100 in 44 cases of hepatic tumors]. / Analyse angioscanner par Imatron C100 de 44 cas de tumeurs hépatiques.

We studied 44 patients with focal benign (n = 13) or malignant (n = 31) liver tumors prouved by histology or follow-up. The flow mode was acquired by electron beam CT (EBCT) after injection (35 cc at 6 ml/sec): 20 slices with a 400 ms exposure time. We looked for abnormal vessels and density curves inside the tumor, liver and aorta. We describe arterial vascularization in most cases (type 1) and particularly in all the hepatocarcinomas (n = 15) associated with abnormal vessels, and also in rare tumors (n = 4). For benign lesions like angiomas (n = 9) we showed surrounding the mass arterial vascularization in add to the typical aspect (type 3); for nodular hyperplasia (n = 3) arterial blush was associated with the last part of the tumoral curve at the same level as liver. Most often metastasis (n = 13) had no central vascularization and a slight peripheral density increased (type 2). Flow mode by EBCT allows a good density curves analysis particularly at arterial time.

[The transplanted kidney. Role of imaging in early non-functioning grafts]. / Rein transplanté. Place de l'imagerie dans les non-fonctions précoces.

Renal failure following transplantation can be classified in two groups: initial non function characterized by the absence of renal function after transplantation and delayed secondary non function after an initial improvement. In the first group, the most frequent etiology is an acute tubular necrosis (30 to 50% of the cases) which usually heals within three weeks. Arterial thrombosis are rare but of very bad prognosis. In the second group, the most frequent cases are acute rejection, urological complications, renal artery stenosis, urinary infections and cyclosporine, intoxication. Diagnostic imaging, and especially the color Doppler flow, is very effective in obtaining diagnosis. Vascular or urological complications are to be confirmed by contrasted opacifications. In the absence of vascular or urological obstruction renal failure must be related to a renal parenchymal disease. This may be acute tubular necrosis, a rejection, a pyelonephritis or a medicinal intoxication depending on clinical symptoms, the time of their apparition and the results of biological examinations.

[Biliary cystadenocarcinoma. Apropos of a case]. / Cystadénocarcinome biliaire. A propos d'un cas.

Biliary cystadenocarcinoma is rare biliary ductal neoplasm, usually occurring in middle-aged women, which arises in a healthy liver, with a better prognostic than other malignant tumors of the liver. We report a new case documented by echography, CT scan and MR. Echography showed multiple heterogeneous and septate masses with fluid-fluid level and dilatation of the intra-hepatic biliary ducts. CT showed multilocular cystic masses with internal septa and papillary excrescences showing contrast enhancement and no calcification. MR displayed a rather intense and variable signal in some parts of the masses on T1 weighted images, flasching on T2 weighted images, corresponding to a hemorrhagic fluid, confirmed by surgery. On T1 weighted images after gadolinium administration, the masses were less well visualized.