A magnetic resonance imaging uses a fast SE-related mul tiple slice technique which permits a decreased SAR, a reduced MTC effect, and still offers excellent image con trast. The imaging includes a process of applying to an object placed in a static magnetic field a one excitation RF pulse in synchronization with a pulse of slice-selective magnetic field gradient applied to the object; a process of consecutively applying to the object a plurality of refocusing RF pulses each of which being applied in synchronization with another pulse of slice-selective magnetic field gradient applied to the object; and a process of consecutively acquir ing a plurality of spin echoes emanated from the object each with a pulse of phase-encoding magnetic field gradient applied to the object, each of said plurality of spin echoes being emanated responsively to each of said plurality of refocusing RF pulses. A flip angle of one of the refocusing RF pulses is set to a first value which is either equal to or less than 180°, said one of the refocusing RF pulses being assigned for phase-encoding at each location in a phase encoding direction of a central block containing a non encoding location of a k-space into which the spin echoes are mapped every block. Flip angles of the remaining refocusing RF pulses are set to a second value smaller than the first value.

Noninvasive diagnosis of peripheral vascular disease started with the introduction of Doppler technology. The development of high frequency ultrasound and color Doppler imaging allows continuous assessment of vascular disorders along the arterial tree. However, the technique remains operator dependent. It also suffers from anatomic limitations, such as bowel gas and ultrasound attenuation due to depth or wall calcification. Ultrasound contrast agents increase the Doppler signal intensity and should therefore reduce the rate of technical failures. They are useful for detecting the flux in cases of attenuated ultrasound beam and reduced blood flow. Their administration using continuous infusion protocols increases the duration of the effect. New imaging modalities such as harmonic imaging and pulse inversion imaging reduce Doppler artifacts and allow real time detection of the microbubbles flowing in the blood stream. Future directions include ultrasound-guided therapy of occlusion using encapsulated drugs targeted to the thrombus.

Power Doppler ultrasound (US) is a new technology that is superior to conventional color Doppler imaging in the detection of blood flow. Because of its greater sensitivity to flow and reduced angle dependence, power Doppler US demonstrates optimal color filling of renal pedicular vessels and allows improved evaluation of the renal parenchymal microvasculature. Power Doppler US was used as an adjunct to conventional color Doppler imaging in technically challenging cases and to improve evaluation of renal vascular disorders in a series of 916 patients. The primary clinical advantages of using power Doppler US compared with conventional color Doppler imaging include better morphologic appreciation of atherosclerotic changes in the renal artery wall, allowing improved diagnostic performance especially in hemodynamically nonsignificant plaques; ability to differentiate between subocclusive renal artery stenosis and occlusion; increased confidence in the diagnosis of renal vein thrombosis and in the assessment of caval tumor thrombus; and better appreciation of renal cortical perfusion defects. In addition, because of its greater sensitivity to perivascular artifact, power Doppler US has the potential to increase the detection rate for intrarenal arteriovenous fistulas.

Color Doppler sonography (CDS) of the male genital tract includes imaging of the prostate gland, of the cavernosal arteries and of the scrotum. It represents a unique means of significantly increasing the predictive positive value of hypoechoic nodules originating in the peripheral zone. In patients with a normal DRE and a PSA level between 4 and 10 ng/ml, it permits selection of patients with significant hypervascular cancers from those with hypovascular nodules or without TRUS/CDS abnormalities harbouring cancers of significantly lower Gleason score. CDS of the cavernosal arteries is the most accurate means of detecting impotence of vascular origin. Intermediate values of peak systolic velocities (25–35 cm/s) are not conclusive for arterial insufficiency and measurement of other Doppler parameters (systolic rise time and acceleration) are required to confirm arterial insufficiency. End diastolic velocity of below 5 cm/s is a reliable means of guaranteeing a normally functioning veno-occlusive system avoiding the need for cavernometry. Scrotal CDS is useful in evaluating acute scrotal disorders and permits the differentiation of acute torsions from epididymitis when the clinical examination is equivocal. Partial torsions are difficult to identify as they do not impair testicular arterial blood flow. Using spectral analysis may improve the sensitivity of color imaging in these cases. CDS of the spermatic veins is useful for quantifying the importance of non-palpable varicoceles by measuring the length and the pattern of the Doppler curve.

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.

Unusual fat-containing renal tumors in a series of 27 cases comprised five categories: atypical and complicated angiomyolipomas (AMLs) (n = 15), including AMLs with extrarenal growth (n = 5), AMLs with undetectable fat (n = 4), and hemorrhagic AMLs (n = 6); fat-containing renal cell carcinomas (RCCs) (n = 9); lipoma (n = 1); liposarcoma (n = 1); and fat-containing renal oncocytoma (n = 1). Fat was present within RCCs by the following mechanisms; lipid-producing necrosis within a large RCC (n = 2), intratumoral bone metaplasia with fatty marrow elements and calcification within a small RCC (n = 2), and entrapment of perirenal (n = 4) or sinus (n = 1) fat by large irregular RCCs. Fat-containing RCC must be considered in cases of fat-containing renal tumors, even though the presence of intratumoral fat is characteristic of AML. A dedicated computed tomography scanning protocol and strict diagnostic criteria are mandatory for accurate diagnosis. Malignancy should be suspected on the basis of the following criteria: presence of intratumoral calcifications; large, irregular tumor invading the perirenal or sinus fat; large necrotic tumor with small foci of fat; and association with nonfatty lymph nodes or venous invasion.

Renal involvement in von Hippel-Lindau (VHL) disease has emerged as the most prevalent cause of death in this hereditary disorder. In a group of 43 VHL patients (23 unrelated families) with renal lesions we examined whether severity of renal disease is affected by parental inheritance and VHL subtype (1, without pheochromocytoma; 2, with pheochromocytoma). We also tested whether and how nephron-sparing surgery could be applied. Renal involvement comprised multiple cysts and bilateral and multifocal carcinomas (RCC) which were detected by screening in 38 patients, at 30.5 (14 to 62) years of age. The severity of the renal disease was similar in VHL type 1 (79% of the pedigrees) and 2 (21%). It was not influenced by the sex of the carrier. Twenty-nine patients were operated on at a mean age of 33.6 years: 21 patients (28 kidneys or 61% of all operated kidneys) underwent nephron-sparing surgery, 4 had complete ablation of involved kidneys and thus required dialysis, 3 had uninephrectomy and 1 had cyst fenestration. Vascular thrombosis was the most severe early complication. It occurred in 4 of 9 kidneys treated by ex vivo surgery. During a median follow-up of 29 months, local recurrence occurred in 5 of 21 (24%) patients treated by nephron-sparing surgery, whereas 2 developed metastasis. Chronic renal failure (creatinine > 120 mumol/liter) affected 11 patients; in 9 of them, it was due to sequelae of surgery. In conclusion, screening of RCC and nephron-sparing surgery are of value in VHL patients. However, indications of ex vivo surgery should be drastically restricted and renal sequelae are not uncommon. Renal followup is required because of the risk of recurrence.

Two cases of focal acute pyelonephritis presenting with an unusual pseudo-tumoral appearance on CT are reported. The lesions exhibited a focal intra-parenchymal homogeneous round-shape mass without any other parenchymal or perirenal fat CT abnormalities. The final diagnosis of focal acute pyelonephritis was confirmed on following CT scans which demonstrated the total disappearance of the lesions in both cases. This particular appearance of acute focal pyelonephritis which mimicked a renal tumor should be clearly individualized in the terminology based on CT findings.

L’echo-doppler est une technique non vulnerante permettant une evaluation a la fois morphologique et fonctionnelle des abords vasculaires pour hemodialyse periodique. Au cours des stenoses interessant le montage vasculaire, cette technique possede une excellente valeur diagnostique et permet de quantifier le retentissement de la lesion sur le debit de fistule. Si le depistage de ces lesions doit toujours reposer sur l’examen clinique et la surveillance minutieuse des parametres de dialyse, l’echo-doppler est indique en cas d’hypodebit, de doute diagnostique, pour la surveillance des lesions traitees et pour le depistage des stenoses chez les patients a haut risque de thrombose d’abord vasculaire. En effet, par rapport a la fistulographie, cette methode possede une valeur diagnostique comparable pour un cout inferieur. Sur le plan therapeutique, la confrontation des donnees cliniques et ultrasonographiques suffit souvent a poser l’indication a la correction de ces lesions et permet d’obtenir dans les cas difficiles un consensus nephro-radio-chirurgical pour une prise en charge harmonieuse de ces patients fragiles.

The developpment of an endorectal surface coil now permitts a partial study of the anatomical model developped by McNeal. Axial and coronal views, which were used to establish the model can be obtained in a short period of time with fast spin echo sequences. Axial views are performed along the proximal uretra and coronal views are performed along the axis of the distal uretra and the ejaculatory duts. Anatomical boundaris of the transitionnal zone are well delineated on axial views, illustrating the concept of "inner gland". The prostatic capsule and the neuro-vascular bundles, pathways of extension of the cancer out of the prostate are also well delineated. Coronal sections allow a very good anatomical study of the caudal jonction of the vas deferens and the seminal vesicles (the so called weak space), pathway of tumor extension to the seminal vesicles. Differences in signal of the prostatic zones make the outter gland cancers very conspicuous as well as some transitionnal cancers which can show, in some cases, an homogeneous hyposignal.

One hundred eighty-seven native kidneys in 96 patients were examined with color Doppler ultrasound (US) to (a) determine the color Doppler US characteristics of renovascular disorders and (b) assess the value of color Doppler US in detection of such disorders. Correlative angiography or computed tomography was performed in 94 patients. The following renovascular disorders were found: renal artery (RA) stenosis (40 cases), RA thrombosis (13 cases), RA aneurysm (four cases), renal vein thrombosis (three cases), arteriovenous fistula (three cases), peripheral infarction (one case of bilateral infarcts), and distal occlusive disease (three cases). One case of aortal coarctation was also found. Color Doppler US failed to demonstrate the proximal main RA in 25% of cases (among 193 RAs total including supernumerary RAs). The sensitivity and specificity of color Doppler US for the detection of RA stenosis or thrombosis were 89% and 99%, respectively. Color Doppler US thus appears to be effective in the diagnosis of renovascular disease in native kidneys.

The development of an endorectal surface coil now permits a partial study of the anatomical model developed by McNeal. Axial and coronal views, which were used to establish the model can be obtained in a short period of time with fast spin echo sequences. Axial views are performed along the proximal urethra and coronal views are performed along the axis of the distal urethra and the ejaculatory ducts. Anatomical boundaries of the transitional zone are well delineated on axial views, illustrating the concept of "inner gland". The prostatic capsule and the neuro-vascular bundles, pathways of extension of the cancer out of the prostate are also well delineated. Coronal sections allow a very good anatomical study of the caudal junction of the vas deferens and the seminal vesicles (the so called weak space), pathway of tumor extension to the seminal vesicles. Differences in signal of the prostatic zones make the outer gland cancers very conspicuous as well as some transitional cancers which can show, in some cases, an homogeneous hyposignal.

Teleteaching aims to help universities and nonacademic institutions improve, update and upgrade their educational programs for a better control of health care cost-effectiveness in developed or developing countries. A multicontinental multilingual service therefore could be offered through multimedia information superhighways and telebroadcasting networks. Attractive programs can be made combining conventional lectures, workshops, talk-shows, reality-shows, teleconferencing and teleproctoring formulae similar to techniques used in ordinary show-business. When the problems of moral and financial sponsoring are solved, teleteaching will create a new job mixing medical and nonmedical specialists of telecommunications aiming to offer highly professional medical educational shows

Corréas J-M, Chabriais J, Melki P, Helcnon O, Di Paola M, Di Paola R, Moreau J-F. Gd-DOTA renal pharmacokinetic study by factor analysis in transplanted human kidney and in phantom. Invest Radiol 1994;29:S174–S176.

The accuracy of color Doppler US (CDUS) for the detection of main renal transplant artery stenoses is excellent (Se 92%; Sp 99%). Whereas the sensitivity of CDUS is still unsatisfactory for the detection of arterial branch stenosis (Se 70%), it has become higher than previously reported because of the ability of color flow images to identify hemodynamic changes at the site of stenosis and focal downstream repercussions in the case of tight stenosis. Color Doppler US is a valuable method in the detection of segmental infarction or large areas of cortical necrosis. However, small superficial cortical perfusion defects are usually undetectable by color Doppler. Contrast-enhanced MRI appears to be more accurate than color Doppler US; it is useful in confirming the diagnosis of infarction and detecting small infarcts missed by color Doppler US, and provides an accurate evaluation of the extent of the infarct; Spectral features (reflux during the whole diastole) obtained from renal arteries in case of acute renal vein thrombosis are suggestive but not specific since they can be observed in the case of severe acute rejection with cortical necrosis. Such findings associated with a lack of venous Doppler signals in the whole kidney are highly suggestive of renal transplant vein thrombosis. Postbiopsy arteriovenous fistulas and false arterial aneurysms are accurately detected by color Doppler Imaging, Color Doppler appears to be the primary Imaging modality for early detection of renal allograft vascular complications. Angiography should be performed after CDUS in order to confirm the diagnosis in doubtful cases, to evaluate preoperatively proximal vascular lesions and sometimes to perform a percutaneous transluminal curative procedure; Contrast-enhanced MRI provides an accurate and non invasive evaluation of peripheral necroses.

Due to the development of the duplex mode, combining ultrasound images with Doppler recording, and especially the development of flow colour coding. Doppler is now increasingly used to investigate the kidney and male genital tract. It is now the technique of choice in the initial diagnosis of certain renal diseases: primary renal vein thrombosis, iatrogenic and malformative arteriovenous anomalies, vascular complications of renal transplantation, and for examination of the scrotal contents in a context of acute scrotum or investigation of the cavernosal arteries in the case of erection disorders. It allows a rapid diagnosis and guides the subsequent radiological assessment. Doppler can also provide useful or even essential additional information in the case of a known abnormality such as renal cancer, in which it defines the venous extension when CT scan is technically insufficient. In certain fields, such as diagnosis of renovascular hypertension or exploration of the prostate, the place of Doppler is still poorly defined and remains controversial, except in a few specialised centres equipped with sophisticated apparatuses used by experienced operators. After briefly reviewing Doppler techniques and the basic steps in interpretation, the authors define the contribution and limitations of colour Doppler in the investigation of the urinary tract and male genital tract. Normal appearances and the results of Doppler-ultrasound in nephrourological disease are illustrated.