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Biomedical subjects

H Trillaud

Publications and source records attributed to H Trillaud.

At least 19 recordsLinked to original sources
PubMed2000

Dilatation of the collecting system during pregnancy: physiologic vs obstructive dilatation.

Dilatation of the collecting system is a classical phenomenon during pregnancy, due to hormonal and extrinsic compressive factors. Imaging has to differentiate a physiological dilatation and a pathological obstruction due to urolithiasis. Presently, sonography, using both, B-mode and color Doppler, has the potential to demonstrate the physiological compression of ureters at the level of the pelvic brim. A pathological obstruction is considered either when a stone is detected above the usual site of compression or when the ureter appears dilated beyond. Color Doppler helps in localizing the site of ureteral compression against the vessels and in differentiating ureters from veins. Magnetic resonance urography, with strongly T2-weighted sequences, also may show the site and type of obstruction without contrast agent administration. These two non-radiating techniques make it possible to avoid the use of X-rays in most cases for management of these patients. The type of treatment is based mostly on the level of pain and the presence or absence of stone.

Female↗
PubMed2000

Nephrotoxic nephritis and obstructive nephropathy: evaluation with MR imaging enhanced with ultrasmall superparamagnetic iron oxide-preliminary findings in a rat model.

PURPOSE: To evaluate the role of magnetic resonance (MR) imaging enhanced with ultrasmall superparamagnetic iron oxide (USPIO) in the evaluation and differentiation of different types of nephropathies. MATERIALS AND METHODS: Two experimental rat models of nephropathies were studied: a model of nephrotoxic nephritis induced by means of intravenous injection of sheep anti-rat glomerular basement membrane serum (n = 43) and a model of obstructive nephropathy (n = 6). Imaging sessions were performed with a spectrometer operating at 4.7 T with fast low-angle shot, or FLASH, sequences. Signal intensity was measured in each kidney compartment before and 24 hours after intravenous injection of USPIO (90 micromol of iron per kilogram of body weight). MR findings were compared with histologic data and urine protein levels. RESULTS: In the nephrotoxic nephritis model 24 hours after injection of USPIO, a significant signal intensity decrease (P: <.05) was present only in the cortex where the glomerular lesions were located. In the obstructive nephropathy model, the signal intensity decrease (P: <.05) was located in all kidney compartments in response to diffuse interstitial lesions. The decrease in signal intensity was due to iron uptake by either macrophages or mesangial cells gaining endocytic activity and was correlated, in the nephrotoxic nephritis model, to the degree of proteinuria. CONCLUSION: Twenty-four-hour delayed USPIO-enhanced MR imaging may help identify and differentiate various types of nephropathies.

Animals↗
PubMed2000

Rapid ELISA D-dimer testing in the exclusion of venous thromboembolism in hospitalized patients.

The clinical diagnosis of deep-vein thrombosis (DVT) and pulmonary embolism (PE) is known to be unreliable. Until now, no biological marker has been found to confirm thrombosis, but help can be gained from a biological marker ruling out the diagnosis of DVT or PE, i.e., the sensitive measurement of D-dimer (DD) species. This article summarizes our experience in introducing a rapid D-dimer test (ELISA VIDAS D-dimères test, bioMérieux) in a collaborative strategy for thrombosis diagnosis during 9 consecutive months involving 1,131 measurements. The efficacy of the DD test was very different according the type of patient, and departments where the DD test provides a real diagnostic benefit were identified. High clinical probability for thrombosis was encountered in 32 patients and radiology was carried out, although D-dimer was negative: none of these patients was found to have a thrombosis after radiologic examination. However, extensive progress must be made in test prescription to reduce the excessive rate of positive D-dimer tests (78%) and positive measurements that are not followed up by radiology (42%).

Biomarkers↗
PubMed2000

Doppler frequency shift and time-domain velocity enhancement induced by an ultrasonographic contrast agent.

The aim of this study was to evaluate in rabbit aorta the effect of three bolus doses of Levovist on velocity values measured with spectral Doppler sonography and with time-domain correlation method (color velocity imaging). At each step, a mean peak systolic velocity was calculated from five measurements. These measurements were taken before injection, at 20 s after, at every 30 s till the third minute, and at every minute until return to peak systolic velocity at baseline value. Total duration of enhancement was noted after each injection. After each injection, once the systolic velocity values return to baseline values, a 3 min delay was observed before the following intravenous contrast agent injection was done. With Doppler spectral analysis, after the first injection, peak systolic velocity enhancement was 15 +/- 8.4% (5 to 28%), with a 6.4 +/- 4.3 min duration. After the second injection, peak systolic velocity enhancement was 15.8 +/- 8.4% (5 to 28%) with an 8.8 +/- 4 min duration. After the third injection, it was 14 +/- 9.8% (5 to 34%) with a 13.6 +/- 7.6 min duration (P = 0.04). Peak systolic velocity measured with color velocity imaging remained unchanged after every injection. Doppler velocities were increased by a bolus injection of a contrast agent. Amplitude was not cumulative with the number of injections but was cumulative on its duration. Velocity measurement with time-domain correlation was not influenced by repeated injections.

Animals↗
PubMed1999

MR imaging of intrarenal macrophage infiltration in an experimental model of nephrotic syndrome.

The objective of this study was to use MR imaging to detect macrophage infiltration of the kidney after injection of ultrasmall superparamagnetic iron oxide (USPIO) particles in a rat model of experimental nephropathy. Ninety micromol of USPIO were injected intravenously in 10 rats with nephropathy secondary to intravenous injection of 5 mg of puromycin aminonucleoside (PAN), and in 10 control rats. The signal intensity was measured in each kidney compartment before and 24 h after injection of the contrast agent. FLASH sequences were performed on a spectrometer operating at 4.7 T. MR findings were compared with histological data. Twenty-four hours after injection of USPIO, a significant decrease (P < 0.0001) was observed in signal intensity in each kidney compartment in the PAN group. There was no variation in the control group. In the diseased kidneys, histological data revealed the presence of macrophages with iron oxide particles within their cytoplasm and lysosomes. Using USPIO, MR imaging can evidence infiltration of the rat kidney by macrophages.

Animals↗
PubMed1999

An echo-shifted gradient-echo MRI method for efficient diffusion weighting.

A segmented magnetic resonance imaging (MRI) method is introduced with time-efficient diffusion weighting resulting in total imaging times similar to those of single-shot methods. The approach is based on the principles of echo shifting with a train of observations (PRESTO) MRI sequence. The time efficiency of the sequence is based on the use of diffusion gradient pulses that also serve to shift the echo train to the next TR period, resulting in TE > TR. Each diffusion gradient is therefore used twice, for dephasing one set of spins as well as rephasing a second set of spins. Diffusion weighting and acquisition are thus achieved simultaneously. The sequence is validated in vitro and in vivo on rat kidney.

Animals↗
PubMed1999

Volume flow measurement in hemodialysis shunts using time-domain correlation.

Volume flow was measured in 58 hemodialysis shunts (32 grafts and 26 radial fistulas) using the color velocity imaging-quantification method. This method is based on time-domain correlation for velocity calculation and integration of time-varying velocity profiles generated by M-mode sampling. Measurements were made in the brachial artery to estimate radial fistula flow or directly in the grafts. Intraoperator reproducibility was 14.9% for fistulas and 11.6% for grafts. Flow rate was significantly lower in abnormal shunts associated with a functional disorder or a morphologic complication (808 ml/min +/- 484) than in shunts associated with no abnormalities (1401 ml/min +/- 562). Receiver operating characteristic curves showed that a flow rate of 900 ml/min for fistulas and 1300 ml/min for grafts provided 81% and 79% sensitivity and 79% and 67% specificity, respectively. A functional disorder or a morphologic complication was associated with all fistulas and grafts in which flow rates were lower than 500 ml/min and 800 ml/min, respectively.

Adolescent↗
PubMed1998

Case report: secondary biliary cirrhosis possibly related to congenital hepatic fibrosis. Evidence for decreased number of portal branch veins and hypertrophic peribiliary vascular plexus.

A 30-year-old man with presinusoidal portal hypertension was transplanted for cryptogenic cirrhosis. On the explanted liver, few intrahepatic stones, biliary cirrhosis, chronic cholangitis of the large bile ducts and a peculiar proliferation of small dilated bile ducts at the periphery of the portal tracts led to the diagnosis of secondary biliary cirrhosis and cholangitis, possibly linked to ductal plate malformation, including congenital hepatic fibrosis associated with a minor form of Caroli's disease. Ex vivo portogram and histology showed the paucity of portal vein branches and the hypertrophy of the peribiliary vascular plexus. This hypertrophy, which has been reported in livers with presinusoidal hypertension, is another indirect argument to suggest the diagnosis of congenital hepatic fibrosis.

Adult↗
PubMed1998

Characterization of urinary calculi: in vitro study of "twinkling artifact" revealed by color-flow sonography.

OBJECTIVE: The "twinkling artifact" is a color-flow sonographic artifact described behind calcifications and presenting as a random color encoding in the region where shadowing would be expected on gray-scale images. Our purpose was to study the relationship between this twinkling artifact seen behind urinary stones on color-flow sonography and the morphology or biochemical composition of these urinary stones. MATERIALS AND METHODS: Forty-seven urinary stones were studied in vitro with color-flow sonography. Transmit frequency, color gain, velocity range, color filters, focal depth, and depth of field were changed during scanning. The twinkling artifact was graded 0 when absent, 1 when present but occupying a portion of acoustic shadowing, and 2 when occupying the entire acoustic shadowing. Stones were studied under a binocular magnifying glass to characterize the surface, and infrared spectrophotometry was used to determine the chemical composition. RESULTS: Calculi of calcium oxalate dihydrate and calcium phosphate always produced a grade 1 or grade 2 twinkling artifact. Absence of artifact was noted only for calcium oxalate monohydrate and urate stones. In 100% of grade 0 calcium oxalate stones, the monohydrate compound was predominant (>93%). In 100% of grade 2 calcium oxalate stones, the dihydrate compound was predominant (>75%). For calcium oxalate stones, the surface pattern was correlated with their composition. Sensitivity and specificity for absence of artifact, as indicative of calcium oxalate monohydrate, were 60% and 83%, respectively, for all stones and 56% and 100%, respectively, only for radiopaque stones. CONCLUSION: An in vitro relationship exists between the twinkling artifact and the morphology of urinary stones. Color-flow sonography could play a role in detecting dense calcium oxalate monohydrate calculi, which in turn may help predict fragmentability.

Artifacts↗
PubMed1998

Color Doppler sonography in early renal transplantation follow-up: resistive index measurements versus power Doppler sonography.

OBJECTIVE: This study was designed to compare power Doppler images of perfusion with interlobar resistive index measurements obtained during the early monitoring of renal graft transplant to diagnose cortical perfusion abnormalities and assess prognosis. SUBJECTS AND METHODS: Thirty-one patients underwent color Doppler sonography (4-7 MHz and 7-10 MHz) on day 6+/-2 after renal transplantation. Cortical vessel density was assessed visually and classified as either normal or decreased. Twelve months after transplantation, the results of power Doppler imaging and the levels of resistive index were reviewed in light of clinical and laboratory findings, graft biopsy results, and functional outcome. RESULTS: No significant relationship was observed among power Doppler grades, levels of resistive index, and renal function. Power Doppler grades and resistive index levels failed to allow us to distinguish between tubulopathy and rejection. However, we found a statistically significant relationship between renal function at 12 months after transplantation and power Doppler grade (p = .04). CONCLUSION: This study suggests that color Doppler sonography is insensitive in revealing and in allowing radiologists to differentiate the causes of graft dysfunction. However, power Doppler sonography allows a prediction of the functional recovery of the graft at 12 months after transplantation not provided by resistive index levels.

Adult↗
PubMed1998

D-dimer strategy in thrombosis exclusion--a gold standard study in 100 patients suspected of deep venous thrombosis or pulmonary embolism: 8 DD methods compared.

DD are now recognized as a valuable tool to screen patients suspected of deep venous thrombosis or pulmonary embolism before carrying out a gold standard radiologic examination. The newest methods available claim to be able to ascertain the absence of thrombosis, but they have yet to prove their efficiency. We compared the performances of 3 reference ELISA methods (D-DI Asserachrom Stago, D-dimer Enzygnost Behring and Dimertest GOLD EIA Agen), 5 recent rapid methods (VIDAS D-Dimer bioMérieux, Instant IA Stago, Simplired Agen, Nycocard D-dimer Nycomed and Accuclot D-Dimer Sigma Diagnostics) and two routine latex methods (Dimertest American Diagnostica and FDP-Slidex bioMérieux) in 100 patients. One of the rapid quantitative methods was demonstrated to have a level of efficiency comparable to that of ELISA methods. Finally, the cost and efficiency of different strategies were evaluated, the association of a routine latex method with the VIDAS D-Dimer bioMérieux being proven to be the most efficient.

Adult↗
PubMed1997

[The value of transrectal MRI in the staging of localized prostate cancer].

OBJECTIVE: To determine the diagnostic value of transrectal magnetic resonance imaging (MRI) in the local staging of prostatic cancer. METHOD: 75 patients suffering from clinically localized prostatic cancer were included consecutively from December 1992 to September 1996. An MRI examination (1.5 Tesla, Siemens) with a transrectal coil was performed before radical prostatectomy. The results of this examination in terms of capsular invasion, seminal vesicle lesion and apical invasion were correlated with the results of histological examination of the operative specimen and the findings of digital rectal examination, transrectal ultrasonography, serum PSA level and biopsy mapping. RESULTS: The best performance of transrectal MRI concerned elimination of seminal vesicle lesion with a specificity of 92%. The positive predictive value of transrectal MRI was 90% for the capsular invasion. The positive predictive value of transrectal MRI was 56% for the apex, the sensitivity was 40% and the specificity was 82%. When transrectal MRI did not reveal any extraprostatic involvement the risk of positive margins on radical prostatectomy was less than 6%. CONCLUSION: In this study, transrectal MRI appeared to be satisfactory to improve the staging of localized prostate cancer, especially in terms of seminal vesicle lesion and apical invasion, but, most importantly, appeared to be very useful to predict negative resection margins.

Aged↗
PubMed1996

Cystic smooth-muscle tumor of the liver and spleen associated with Epstein-Barr virus after renal transplantation.

Immunosuppression is known to favor the development of various types of tumors. After organ transplantation, the risk of lymphoproliferative disease, whether clonal or not, is particularly increased and clearly associated with Epstein-Barr virus infection. We report a case of an unusual large cystic tumor of the liver with satellite hepatic and splenic nodules occurring 4 years after renal transplantation. Radiologic examination showed a rich vascularization of the tumor. Light and electron microscopy of a surgical liver biopsy, completed by an immunohistochemical study, demonstrated a well-differentiated tumor of smooth-muscle origin. Using in situ hybridization, we showed large amounts of Epstein-Barr virus messenger RNAs within the tumor cells. In addition, Southern blot analysis revealed that viral DNA was present in the form of a single monoclonal episome within the tumor. The polymerase chain reaction analysis of the genomic DNA of tumoral cells also indicated a monoclonal pattern. At last, the tumor was shown to be of host origin. Six months later, and despite three courses of chemotherapy, the tumoral lesions were unchanged. This case underlines the role of Epstein-Barr virus infection in the development of unusual and clonal smooth-muscle tumors after organ transplantation. The evolution of these rare tumors is uncertain.

Female↗
PubMed1996

Diagnosis of renovascular hypertension: feasibility of captopril-sensitized dynamic MR imaging and comparison with captopril scintigraphy.

OBJECTIVE: Angiotensin-converting enzyme inhibitors may decrease glomerular filtration rate when a significant renal artery stenosis is present. The purpose of this preliminary study is to evaluate the feasibility of captopril-sensitized, dynamic MR imaging of the kidney in a series of patients with a high suspicion of renovascular hypertension and to compare the results with those of captopril scintigraphy. SUBJECTS AND METHODS: Fifteen hypertensive patients with renal artery stenosis shown by angiography were studied with sequential gadolinium-enhanced MR imaging after oral administration of 50 mg of captopril, an inhibitor of angiotensin-converting enzyme. Symmetry of onset and evolution of tubular phases between the two kidneys were analyzed, and medullary signal intensity time curves were drawn for each kidney. When asymmetry between kidneys was noted, the same dynamic study was repeated 24 hr later, without captopril sensitization. All patients also underwent renal scintigraphy after administration of captopril to compare captopril-induced changes in both techniques. Three-dimensional time-of-flight MR angiography was also performed on all patients. RESULTS: MR imaging with normal and symmetric tubular phases showed that 11 patients had no impairment of glomerular filtration after administration of captopril. MR imaging showed that four had impairment of glomerular filtration: studies without captopril were symmetric (n = 2) or slightly asymmetric (n = 2), but administration of captopril induced severe functional impairment on the side of stenosis--that is, a delayed tubular phase with late corticomedullary decrease of signal intensity in the first two patients and absence of tubular phase in the other two. The results of scintigraphy were concordant in all but one case, in which the segmental distribution of filtration impairment, shown by MR imaging, was not shown by scintigraphy. The renal artery stenosis was shown by MR angiography in 10 of 15 patients (67%). CONCLUSION: Captopril-sensitized dynamic MR imaging of the kidney is feasible in patients with renovascular hypertension. However, captopril-induced changes are not present in all patients proven to have the disease. Scintigraphy provides similar results but may ignore segmental functional involvement.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1995

High resolution renal diffusion imaging using a modified steady-state free precession sequence.

A modified steady-state free precession (SSFP) diffusion sequence is proposed for high resolution renal imaging. A pair of bipolar diffusion gradients was used to minimize the errors in measured apparent diffusion coefficient (ADC) caused by variations in T1, T2, and RF flip angle that have been observed with previously employed SSFP diffusion sequences. Motion sensitivity was reduced by the use of compensated gradients, frame-by-frame averaging, and a repetition time of 22 ms, which for a single-acquisition 128 x 128 image requires only 3 s. High resolution was achieved by signal averaging. The modified sequence was applied to in vivo diffusion measurements. In six normal rat kidneys the ADCs (mean +/- SD; x 10(-3) mm2/s) of the cortex, outer medulla, and inner medulla were 2.28 +/- 0.05, 2.38 +/- 0.10, and 2.95 +/- 0.05, respectively. The technique requires relatively large gradients to achieve adequate diffusion weighting.

1-Propanol↗