O. Hélénon

Ultrasound elastography of the prostate: State of the art

Prostate cancer is the cancer exhibiting the highest incidence rate and it appears as the second cause of cancer death in men, after lung cancer. Prostate cancer is difficult to detect, and the treatment efficacy remains limited despite the increase use of biological tests (prostate-specific antigen [PSA] dosage), the development of new imaging modalities, and the use of invasive procedures such as biopsy. Ultrasound elastography is a novel imaging technique capable of mapping tissue stiffness of the prostate. It is known that prostatic cancer tissue is often harder than healthy tissue (information used by digital rectal examination [DRE]). Two elastography techniques have been developed based on different principles: first, quasi-static (or strain) technique, and second, shear wave technique. The tissue stiffness information provided by US elastography should improve the detection of prostate cancer and provide guidance for biopsy. Prostate elastography provides high sensitivity for detecting prostate cancer and shows high negative predictive values, ensuring that few cancers will be missed. US elastography should become an additional method of imaging the prostate, complementing the conventional transrectal ultrasound and MRI. This technique requires significant training (especially for quasi-static elastography) to become familiar with acquisition process, acquisition technique, characteristics and limitations, and to achieve correct diagnoses.

Ureteral Endometriosis: The Role of Magnetic Resonance Imaging

In six women out of 792 who underwent magnetic resonance imaging (MRI) for management of deep infiltrating endometriosis (DIE), ureteral involvement was suspected. Ureteral endometriosis was identified as a hypointense nodule on T2- weighted images and hyperintense foci on T1-weighted images. Magnetic resonance urography detected obstruction and hydronephrosis in half the women. Detection with MRI of periureteral involvement (extrinsic endometriosis) in four women rather than ureteral wall lesions (intrinsic endometriosis) in two women is an original finding from this series. Magnetic resonance imaging features were correlated and matched with intraoperative and pathologic findings. Magnetic resonance imaging is a useful preoperative tool for the diagnosis and assessment of ureteral endometriosis in rare cases when such lesions have been suspected.

Elastography of the thyroid

Thyroid nodules are very common, while thyroid cancer is rare and has a very good prognosis. Thyroid nodule ultrasound characterization performed by experienced clinicians allows the selection of the tumours to be punctured and guiding fine needle aspiration (FNA). FNA provide cytology information able to differentiate benign tumours from cancer in approximately 80% of cases. However, it remains difficult to identify thyroid cancers with ultrasound imaging, as demonstrated by the very low rate of cancers detected in all of the carried out FNA (approximately 5%). As a majority of thyroid cancers are hard, the stiffness evaluation has become part of nodular characterization. Since 2005, elastography has been used for the evaluation of thyroid nodules; quasi-static elastography was the first technique available and used, at first, an external pressure induced by the probe, which was then replaced by carotid internal excitation allowing improvement in sensitivity. Semi-quantitative analysis allows comparison of tissue elasticities between tissue with elasticity anomalies and normal tissue and provides therefore useful analytic information. Shear wave elastography (SWE) provides a map of the elasticity in a region and allows stiffness quantification of lesions in kilopascals in order to reinforce the predictive value of malignancy. A tumour whose stiffness is greater than 65kPa or for which the stiffness ratio is greater than 3.7 compared to surrounding healthy tissue is highly suspicious. SWE may enable the detection of malignant follicular tumours that currently escape detection by the ultrasound-guided ultrasound/aspiration cytology couple. Lymph node metastasis of papillary thyroid cancer can also be detected by elastography due to its increased stiffness.

Prophylactic Embolization of Renal Angiomyolipomas: Evaluation of Therapeutic Response Using CT 3D Volume Calculation and Density Histograms

PURPOSE To evaluate the efficacy and tolerance of prophylactic embolization of angiomyolipomas (AMLs) and to analyze the therapeutic response by using three-dimensional 3D volume calculation and 3D quantification of fatty and angiomyogenic components during computed tomography (CT) follow-up. MATERIALS AND METHODS Over a 51-month period, 30 patients with 34 AMLs (mean diameter, 82 mm ± 37; range, 30-173 mm) underwent 37 prophylactic embolization procedures. The protocol included supraselective arterial embolization with a combination of absolute alcohol, microparticles, and coils. Mean clinical and imaging follow-up were 20.5 and 14.5 months, respectively. The 3D volume calculation and density histograms were retrospectively analyzed for treatment evaluation. RESULTS Four technical failures were observed (11%), with one successful secondary reattempt, resulting in 31 AMLs (91.2%) being embolized. Thirty (88.2%) had CT follow-up and were included in the analysis. Embolization was complete after a single procedure for 25 AMLs (83%) and required two procedures in two cases. Three AMLs had incomplete embolization and were scheduled for a second procedure. Mean volume reductions were 43% ± 32 for AMLs followed for 1-6 months after embolization and 81% ± 19 for the 12 AMLs followed for more than 1 year. The volume reduction after embolization was significantly correlated with the AML initial composition, with fat-rich AMLs showing a much smaller reduction of size than predominantly angiomyomatous AMLs (P < .05). CONCLUSIONS Prophylactic embolization allows significant reduction of AML volume with a high success rate. Three-dimensional CT volume and density histogram calculations suggest that it is especially effective on angiomyogenic components and fat-poor AMLs.

Adénome oncocytaire du rein : redéfinition des critères diagnostiques en tomodensitométrie

Resume Objectif Redefinir et evaluer les criteres diagnostiques tomodensitometriques (TDM) de l’oncocytome renal (OR) dans le but d’elargir les indications de traitement chirurgical conservateur pour une tumeur benigne. Materiel et methode Etude retrospective sur 57 patients porteurs de 69 OR avec correlation anatomo-pathologique. Un test en double aveugle sur 60 tumeurs renales de diametre > 3 cm, comprenant des oncocytomes renaux et des cancers est realise afin d’evaluer l’efficacite de criteres tomodensitometriques redefinis. Resultats Parmi les gros OR (diametre > 3 cm), 55 % ont presente une cicatrice, hypodense a un temps nephrographique tubulaire, centrale ou excentree, associee a un parenchyme peripherique homogene, hypervascularise, et dont la forme a conduit a definir 3 categories distinctes. L’utilisation de nos criteres diagnostiques a donne une concordance inter-observateur satisfaisante (p Conclusion Les criteres tomodensitometriques que nous avons redefinis, eventuellement associes a la biopsie renale, devraient permettre d’augmenter les indications de nephrectomie partielle pour les oncocytomes de grande taille.

Renovascular disease: Doppler ultrasound

Color Doppler ultrasound (CDUS) seems to be an effective imaging technique for the diagnosis of renal vascular diseases. It is already the modality of choice for the detection of acute renal vein thrombosis and nonocclusive intrarenal vascular disorders including iatrogenic arteriovenous fistula and false aneurysm, particularly in patients with impaired renal function that precludes the use of iodinated contrast agents. Although proximal Doppler interrogation remains an important step in diagnosing renal artery (RA) stenosis, useful hemodynamic information can be obtained from the distal arterial bed. When CDUS fails in identifying proximal RAs, normal waveform velocity and morphology obtained from intrarenal arteries enable one to rule out RA occlusion and most of the severe stenoses (> or = 80%). Such information, which is not subject to a significant risk of technical failure, seems to be particularly useful in studying patients with acute renal failure of suspected vascular origin. Despite the extreme variability in reported performance between studies, CDUS has seemed to be a valuable tool compared with other noninvasive modalities in the diagnosis of RA stenosis. Whereas a CDUS-based strategy is already accepted in numerous specialized centers, a thorough evaluation of diagnostic criteria and extensive training of operators will allow CDUS to be widely accepted for the screening of patients at high risk for renovascular hypertension.

Double-echo gradient chemical shift MR imaging fails to differentiate minimal fat renal angiomyolipomas from other homogeneous solid renal tumors.

OBJECTIVES The purpose of this retrospective study was to evaluate the diagnostic performance of double-echo gradient chemical shift (GRE) magnetic resonance (MR) imaging for the differentiation of angiomyolipomas with minimal fat (mfAML) from other homogeneous solid renal tumors. METHODS Between 2005 and 2010 in two institutions, all histologically proven homogenous solid renal tumors imaged with computed tomography and MR imaging, including GRE sequences, have been retrospectively selected. A total of 118 patients (mean age: 61 years; range: 20-87) with 119 tumors were included. Two readers measured independently the signal intensity (SI) on GRE images and calculated SI index (SII) and tumor-to-spleen ratio (TSR) on in-phase and opposed-phase images. Intra- and interreader agreement was obtained. Cut-off values were derived from the receiver operating characteristic (ROC) curve analysis. RESULTS Twelve mfAMLs in 11 patients were identified (mean size: 2.8cm; range: 1.2-3.5), and 107 non-AML tumors (3.2cm; 1-7.8) in 107 patients. The intraobserver reproducibility of SII and TSR was excellent with an intraclass correlation coefficient equal to 0.99 [0.98-0.99]. The coefficient of correlation between the readers was 0.99. The mean values of TSR for mfAMLs and non-mfAMLs were -7.0±22.8 versus -8.2±21.2 for reader 1 and -6.7±22.8 versus -8.4±20.9 for reader 2 respectively. No significant difference was noticed between the two groups for SII (p=0.98) and TSR (p=0.86). Only 1 out of 12 mfAMLs and 11 of 107 non-AML tumors presented with a TSR inferior to -30% (p=0.83). CONCLUSION In a routine practice, GRE sequences cannot be a confident tool to differentiate renal mfAMLs from other homogeneous solid renal tumors.

Conduite à tenir devant un nodule thyroïdien : échographie, cytoponction

All ultrasound examinations for thyroid nodule should include a malignancy risk assessment based on the markedly hypoechoic nature of the nodule, presence of microcalcifications, ill-defined margins, nodule with shape taller than wide and intra-nodular hypervascularity at color Doppler. In patients with multinodular thyroid gland, precise nodule mapping is necessary to allow accurate follow-up of each nodule, correctly identify which nodule(s) is hyper functioning on iodine scan (if done) and guide fine needle aspiration (FNA) of suspicious nodules. As such, all reports of US examinations for thyroid nodule(s) should include a diagram or map of the nodule(s). An evaluation of cervical lymph nodes also helps to determine the malignancy risk. The main US features for malignant adenopathy include: rounded lymph node, loss of normal echogenic fatty hilum, and loss of normal hilar vascularization. Several patterns are highly suggestive of thyroid cancer metastasis: microcalcifications, cystic components, hyperechoic nodes, mimicking thyroid tissue. FNA is a routine procedure in experienced hands. It is the best test to determine which nodule(s) needs to be surgically removed. Thyroglobulin assay on needle-washing fluids after FNA is mandatory when lymph node metastasis is suspected. Preoperative lymph nodes mapping with neck ultrasound is commonly repeated prior to surgery to assess the need for node dissection in patients with proven thyroid malignancy.

Imagerie diagnostique de la pathologie vasculaire rénale périphérique

Peripheral vascular disorders of the kidney involve the intrarenal branches of the renal vascular tree. It include occlusive (infarction and cortical necrosis) and non-occlusive vascular lesions (acquired arteriovenous fistulas, arteriovenous malformation, false aneurysms and microaneurysms). Initial diagnosis relies on color Doppler US and CT angiography. Angiography plays a therapeutic role. MR imaging provides useful diagnostic information on perfusion disorders especially in patients with renal insufficiency.

Diagnostic d'adénome métanéphrique rénal : Intérêt de l'immunohistochimie et apport de la biopsie

Resume La majorite des tumeurs renales de l’adulte sont des carcinomes. Ils sont traites de facon chirurgicale par une excision limitee ou par une nephrectomie. En cas de tumeur renale decouverte fortuitement et de petite taille, une biopsie est proposee afin d’adapter le traitement. Nous rapportons le cas d’une femme de 45 ans presentant une masse renale. Une biopsie de cette masse mettait en evidence un adenome metanephrique. Cette tumeur etant benigne, aucune exerese chirurgicale n’a ete realisee. Nous abordons d’une part l’interet de l’immunohistochimie dans le diagnostic differentiel des tumeurs « a petites cellules basophiles » du rein. D’autre part, cette observation souligne la place croissante de la biopsie dans la prise en charge optimale des tumeurs renales.