Biomedical subjects

Denis Lyonnet

Publications and source records attributed to Denis Lyonnet.

10 recordsLinked to original sources

PubMed2006

Prostate dynamic contrast-enhanced MRI with simple visual diagnostic criteria: is it reasonable?

UNLABELLED: The purpose of this study was to evaluate the accuracy of prostate cancer localization with simple visual diagnostic criteria using dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI). A total of 46 consecutive patients with biopsy-proven prostate cancer underwent prostate 1.5 T MRI with pelvic phased-array coils before prostatectomy. Besides the usual T2-weighted sequences, a 30-s DCE sequence was acquired three times after gadoterate injection. On DCE images, all early enhancing lesions of the peripheral zone were considered malignant. In the central gland, only early enhancing lesions appearing homogeneous or invading the peripheral zone were considered malignant. Three readers specified the presence of cancer in 20 prostate sectors and the location of distinct tumors. Results were compared with histology; p < 0.05 was considered significant. For localization of cancer in the sectors, DCE imaging had a significantly higher sensitivity [logistic regression, odds ratio (OR): 3.9, p < 0.0001] and a slightly but significantly lower specificity (OR: 0.57, p < 0.0001). Of the tumors >0.3 cc, 50-60% and 78-81% were correctly depicted with T2-weighted and DCE imaging, respectively. For both techniques, the depiction rate of tumors >0.3 cc was significantly influenced by the Gleason score (most Gleason </=6 tumors were overlooked), but not by the tumor volume. CONCLUSION: DCE-MRI using pelvic phased-array coils and simple visual diagnostic criteria is more sensitive for tumor localization than T2-weighted imaging.

Aged↗

PubMed2006

Evaluation of color Doppler in guiding prostate biopsy after HIFU ablation.

OBJECTIVE: Transrectal ultrasound cannot accurately depict early cancer recurrences after prostate high-intensity focused ultrasound (HIFU) ablation. We evaluated transrectal color Doppler (CD) in guiding post-HIFU prostate biopsy. METHODS: Prostate CD-guided sextant biopsies were obtained in 82 patients who had undergone prostate HIFU ablation for cancer, 24 of whom had hormone therapy before the treatment. At the time of biopsy, a subjective CD score was given to all biopsy sites (0=no flow; 1=minimal flow; 2=suspicious flow pattern). CD findings were compared with biopsy results. RESULTS: CD was a significant predictor of biopsy findings, according to univariate and multivariate site-by-site analysis. However, only 36 of 94 sites with residual cancer had positive CD findings, and thus, negative CD findings should not preclude random biopsy. There was a significant interaction between CD diagnostic capability and a history of hormone therapy before HIFU treatment. CD was a significant and independent predictor of biopsy findings in patients who had not received hormone therapy (odds ratio: 4.4; 95%CI: 2.5-7.9; p<0.0001), but not in those who had (odds ratio: 1.3; 95%CI: 0.5-3.4; p>0.5). CONCLUSION: Biopsy taken in CD-positive sites were 4.4 times more likely to contain cancer in patients who did not receive hormone therapy. CD could not reliably depict cancer recurrence in patients with history of hormone therapy.

Aged↗

PubMed2006

Nonmetastatic renal-cell carcinoma: is it really possible to define rational guidelines for post-treatment follow-up?

Defining rational follow-up guidelines in patients treated for cancer is important, from both a medical and an economical perspective. Renal-cell carcinoma is reputed to be unpredictable in its course and only a few, and often contradictory, follow-up guidelines exist for patients treated for nonmetastatic renal-cell carcinoma. Recent advances in tumor biology have contributed to a better understanding of this cancer and have indicated that personalized follow-up regimens, based on tumor and host molecular characteristics, might be possible in the near future.

Biomarkers, Tumor↗

PubMed2005

Prostate MR imaging at high-field strength: evolution or revolution?

As 3 T MR scanners become more available, body imaging at high field strength is becoming the subject of intensive research. However, little has been published on prostate imaging at 3 T. Will high-field imaging dramatically increase our ability to depict and stage prostate cancer? This paper will address this question by reviewing the advantages and drawbacks of body imaging at 3 T and the current limitations of prostate imaging at 1.5 T, and by detailing the preliminary results of prostate 3 T MRI. Even if slight adjustments of imaging protocols are necessary for taking into account the changes in T1 and T2 relaxation times at 3 T, tissue contrast in T2-weighted (T2w) imaging seems similar at 1.5 T and 3 T. Therefore, significant improvement in cancer depiction in T2w imaging is not expected. However, increased spatial resolution due to increased signal-to-noise ratio (SNR) may improve the detection of minimal capsular invasion. Higher field strength should provide increased spectral and spatial resolution for spectroscopic imaging, but new pulse sequences will have to be designed for overcoming field inhomogeneities and citrate J-modulation issues. Finally, dynamic contrast-enhanced MRI is the method of imaging that is the most likely to benefit from the increased SNR, with a significantly better trade-off between temporal and spatial resolution.

Artifacts↗

PubMed2004

Can color doppler predict the uniformity of HIFU-induced prostate tissue destruction?

BACKGROUND: Tissue blood perfusion influences the results of some hyperthermia and thermotherapy procedures, but its role in the outcome of prostate cancer treatment by high-intensity focused ultrasound (HIFU) has not been evaluated yet. We evaluated preoperative prostate color Doppler as a predictor of the efficacy of HIFU treatment. METHODS: Thirty-five patients underwent pre- and post-contrast color Doppler examination of the prostate before HIFU treatment. Specific software was used to calculate, on color Doppler images, the color pixel density (CPD), and the specific flow (SF, i.e., mean velocity x CPD) in different regions of interest. Post-treatment sextant biopsies were obtained in 31 patients, 5.8 +/- 2.8 months after HIFU treatment. RESULTS: No significant correlation was found between the uniformity of HIFU-induced tissue destruction observed on control biopsies and the pre-treatment CPD/SF values in any region of interest, either before or after contrast injection. On the other hand, history of radiation therapy was significantly associated with homogeneous tissue destruction and history of hormone therapy was significantly associated with incomplete tissue destruction. CONCLUSIONS: Color Doppler cannot predict the uniformity of HIFU-induced tissue destruction. History of radiation therapy was found to be a factor of favorable prognosis and history of hormone therapy was found to be a factor of poor prognosis in our population.

Aged↗

PubMed2004

Recurrent prostate cancer after external beam radiotherapy: value of contrast-enhanced dynamic MRI in localizing intraprostatic tumor--correlation with biopsy findings.

OBJECTIVES: To assess the accuracy and interobserver variability of T2-weighted (T2W) and contrast-enhanced dynamic (CE-Dyn) magnetic resonance imaging (MRI) in predicting the results of transrectal biopsy in patients with suspected recurrent prostate cancer after external beam radiotherapy. METHODS: A total of 22 patients with increasing prostate-specific antigen levels after external beam radiotherapy for prostate cancer underwent T2W and CE-Dyn MRI of the prostate. The CE-Dyn sequence (acquisition time 30 seconds) was repeated three times after the injection of gadolinium. All patients underwent subsequent transrectal biopsy. Three independent readers interpreted the MRI scans. The MRI and biopsy results were correlated in 10 prostate sectors (the sextants of the peripheral zone, the two transitional zones, and the two seminal vesicles). RESULTS: Biopsy cores were obtained in 147 prostate sectors. Of these, 63 were positive for cancer in 19 patients. On the T2W images, the three readers interpreted as positive for cancer 15, 15, and 13 of the 19 patients showing cancer at biopsy. They interpreted as negative 3, 0, and 1 of the 3 patients showing no cancer at biopsy. On CE-Dyn images, the three readers correctly classified all the patients as positive or negative for cancer. The T2W and CE-Dyn MRI findings were concordant with biopsy results in, respectively, 81 to 95 and 107 to 117 prostate sectors (P <0.001 and P <0.01 for readers 1 and 2 and was nonsignificant for reader 3). The interobserver agreement was better for CE-Dyn images (kappa = 0.63 to 0.70) than for the T2W images (kappa = 0.18 to 0.39). The MRI-calculated tumor volumes and the mean biopsy core invasion rates were significantly correlated on the CE-Dyn images for all readers. They correlated significantly on T2W images only for one reader. CONCLUSIONS: CE-Dyn MRI depicts the intraprostatic distribution of recurrent cancer after external beam radiotherapy more accurately and with less interobserver variability than T2W MRI.

Aged↗

PubMed2003

[Results of transrectal focused ultrasound for the treatment of localized prostate cancer (120 patients with PSA < or + 10ng/ml].

OBJECTIVES: To evaluate the efficacy of high intensity focused ultrasound (HIFU) for the treatment of localized prostate cancer in a population of potentially curable patients. MATERIALS AND METHODS: 120 patients with clinical stage T1-T2 prostate cancer with an initial PSA < or = 10 ng/ml and not candidates for radical prostatectomy were treated by HIFU (ABLATHERM, EDAP S.A.). Clinical failure was defined by the need for adjuvant therapy (endocrine or external beam radiotherapy). Progressive disease (laboratory failure) was strictly defined by identification of residual cancer on follow-up biopsies (regardless of the PSA) or by 3 successive elevations of PSA (when follow-up biopsies were negative) with a velocity greater than 0.75 ng/ml/year. Progression-free survival rates were calculated according to the Kaplan-Meier method. Success rates stratified according to risk factors were compared by Log-rank tests. RESULTS: The patients presented the following characteristics on inclusion: mean age: 71.2 +/- 5.34 years, PSA: 5.67 +/- 2.47 ng/ml, prostatic volume: 33.6 +/- 16.5 cc, stage: T1:61, T2:59, Gleason score 2-6: 77, 7-10: 43. The mean number of HIFU session per patient was 1.5 +/- 0.7. The mean duration of catheterization was 9 days and the mean follow-up was 27 months (range: 3-96 months). Follow-up biopsies did not reveal any residual cancer in 103 patients (86%). A residual cancer was identified in 17 patients, but only 6 patients required adjuvant therapy (endocrine: n = 2, radiotherapy: n = 4), corresponding to a clinical success rate of 95%. Progression-free survival for the whole patient population was 76.9%. A significant difference (p < 0.05) was observed between patients with a Gleason score between 2 and 6 (85.4%) and patients with a Gleason score between 7 and 10 (61.3%). CONCLUSION: These results show that high intensity focused ultrasound is a treatment option achieving similar results to those of other non-surgical treatments for prostate cancer.

Aged↗

PubMed2002

Characterization of time-enhancement curves of benign and malignant prostate tissue at dynamic MR imaging.

Our objectives were to determine time-enhancement curves of prostate cancer, peripheral zone, and adenoma at gadolinium-enhanced MR imaging, and to determine if a high-spatial/low-temporal dynamic imaging could be accurate in depicting prostate cancer, or if a higher temporal resolution (and a lower spatial resolution) should be favored. Thirty-nine patients with prostate cancer underwent MR imaging before radical prostatectomy by using T1- and T2-weighted axial images and a single-slice dynamic gadolinium-enhanced sequence (40 images; one image per 6 s; injection of 20 ml at 2 ml/s). After analysis of the pathologic specimens, four region-of-interest (ROI) cursors (cancer, peripheral zone, adenoma, and muscle) were retrospectively placed on dynamic images. Time-enhancement curves of the ROIs were obtained. The theoretical accuracy of a 30-s dynamic multislice MR sequence in depicting cancer within peripheral zone and adenoma (ROC curves) was calculated from these curves. On average, prostate cancer enhanced more and earlier than peripheral zone and adenoma, but there were great interindividual variations. For start delays ranging from 12 to 84 s, the areas under the ROC curves ranged from 0.602 to 0.698 for the depiction of cancer within adenoma and from 0.614 to 0.827 for the depiction of cancer within peripheral zone. The best results were obtained with a 36-s start delay. In conclusion, we found a 30-s scanning window which seems to allow a good depiction of cancer within peripheral zone. Because of largely overlapping enhancement patterns, cancer will probably not be depicted within adenoma by dynamic imaging, at least by using low temporal resolution.

Adenocarcinoma↗

PubMed2002

Acute thrombosis of renal transplant artery: graft salvage by means of intra-arterial fibrinolysis.

BACKGROUND: Arterial thrombosis in a transplanted kidney is a serious complication that usually leads to graft loss. The purpose of our study was to evaluate intra-arterial fibrinolysis as a treatment of acute renal transplant artery thrombosis and to determine the maximum period of occlusion allowing a reasonable chance of graft salvage. METHODS AND RESULTS: Four patients underwent intra-arterial fibrinolysis for acute transplant artery thrombosis. Transplantations had been performed 29 days to 10 years before the fibrinolysis. Fibrinolysis was carried out by using recombitant tissue plasminogen activator (n=1) or urokinase (n=3). In one patient, anuric for 13 hr at admittance, fibrinolysis could not revascularize the graft artery. In a second patient, anuric for 48 hr at admittance, fibrinolysis did revascularize the graft artery, but dialysis could not be discontinued. In the two remaining patients, anuric for 19 and 20 hr at admittance, the graft artery was successfully revascularized and dialysis could be discontinued 1 week later. One of these two patients returned to dialysis 71 months later because of chronic rejection. Thirty-four months after the acute episode, the remaining patient had a patent artery and did not require dialysis. CONCLUSIONS: Fibrinolysis seems an efficient treatment that may save transplants after up to 24 hr of the arterial occlusion.

Acute Disease↗

PubMed2002

[Treatment of renal tumors with radiofrequency: preliminary results].

OBJECTIVE: To study the feasibility and the innocuity of the treatment by radiofrequency of small renal tumours. MATERIAL AND METHODS: From June 2000 to September 2001, 10 renal tumours in 6 patients were treated by radiofrequency. The mean age of the patients was 57 years. The mean tumour diameter was 20 mm. Indications for partial surgery were 3 solitary kidneys, one patient with chronic renal failure, one patient with Von Hippel Lindau disease and one patient in whom several angiomyolipomas were discovered in the right kidney. 4 patients were treated via a lumbar incision and 2 were treated percutaneously (one with ultrasound guidance and the other with computed tomography guidance). Patients were reviewed by imaging (CT and/or MRI) with injection of contrast agent to demonstrate complete devascularization of the tumour. RESULTS: Treatment lasted an average of 180 minutes. The intraoperative complication rate was 16%. The mean hospital stay was 9 days (4 days for the percutaneous route). Nine tumours (5 patients) were devascularized after a single session. One patient (treated via the percutaneous route under ultrasound guidance) showed persistence of tumour tissue (identified by CT). A second session, performed 4 months later, allowed complete devascularization of the tumour. The mean follow-up is 13 months. CONCLUSION: This study demonstrates the feasibility and safety in terms of renal function of radiofrequency treatment of small renal tumours. However further studies are necessary to precisely define the radiological criteria of tumour necrosis and to evaluate the long-term results of this method (outcome of necrotic tumour tissue, metastatic risk, cancer recurrence along the needle track in the case of a percutaneous approach). This treatment must be reserved for selected patients.

Adult↗