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.

[Diagnostic imaging of peripheral renal vascular disorders]. / 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.

[Characterization of renal masses]. / Caractérisation des masses rénales.

The characterization of renal masses relies mainly on CT which remains the gold standard in the diagnosis of renal tumors and cysts. Ultrasound enables to diagnose benign cysts which account for the majority of incidentally detected renal masses. MR imaging is useful in the diagnosis of renal masses that remain indeterminate at CT. Moreover, it is efficient as a substitute when CT is contraindicated. Renal masses include three categories with respect to the size and the gross architecture of the lesion: indeterminate very small masses (less than 10mm in diameter); cystic renal masses and solid renal masses that exhibit postcontrast tumor tissue enhancement. Characterization of cystic renal masses relies mainly on the Bosniak classification which consists of four categories: benign simple cysts (cat I); minimally complicated cysts (cat II); indeterminate cystic renal masses that include cystic renal tumors (multiloculated or not) and complex cysts; cystic renal cell carcinomas (cat IV). Solid renal masses include pseudotumors (normal variants, renal dysmorphisms and inflammatory renal masses) and renal neoplasms among which CT enable to distinct: typical large renal cell carcinomas, typical fat-containing angiomyolipomas and indeterminate renal tumors.

[Renal sinus disorders: imaging findings and pitfalls]. / Le sinus du rein: imagerie pathologique et pièges.

Renal sinus pathology can be classified into 3 groups: intrinsic lesions that arise from the anatomical components of the sinus (fatty tissue, collecting system, arteries and veins, lymphatic vessels, and nerves); extrinsic lesions that develop within the renal sinus from the renal parenchyma; secondary lesions including metastases and retroperitoneal tumors with renal sinus involvement. The diagnosis of renal sinus disorders often relies on a multimodality approach including IVU, doppler-ultrasonography, and CT. The wide variety of renal sinus diseases that may origin either from the renal parenchyma or the retroperitoneum, and the numerous pitfalls mostly due to anatomic variations, may prevent from making a right etiological diagnosis in numerous cases.

Laser guidance system for CT-guided procedures.

In a phantom and in 37 patients, a simple laser guidance system for computed tomography (CT)-guided procedures used the software program of the CT scanner and a laser beam mounted on the CT gantry without need for additional software or components. The skin entry point and angulation of the target path were determined. Then the system projected the desired needle path (including compound angulation), allowing accurate needle placement in all cases, even in small lesions.