Biomedical subjects

Maurice Stephan Michel

Publications and source records attributed to Maurice Stephan Michel.

At least 19 recordsLinked to original sources

PubMed2006

Complications in percutaneous nephrolithotomy.

OBJECTIVE: This review focuses on a step-by-step approach to percutaneous nephrolithotomy (PNL) and its complications and management. METHODS: Based on institutional and personal experience with >1000 patients treated by PNL, we reviewed the literature (Pubmed search) focusing on technique, type, and incidence of complications of the procedure. RESULTS: Complications during or after PNL may be present with an overall complication rate of up to 83%, including extravasation (7.2%), transfusion (11.2-17.5%), and fever (21.0-32.1%), whereas major complications, such as septicaemia (0.3-4.7%) and colonic (0.2-0.8%) or pleural injury (0.0-3.1%) are rare. Comorbidity (i.e., renal insufficiency, diabetes, gross obesity, pulmonary disease) increases the risk of complications. Most complications (i.e., bleeding, extravasation, fever) can be managed conservatively or minimally invasively (i.e., pleural drain, superselective renal embolisation) if recognised early. CONCLUSIONS: The most important consideration for achieving consistently successful outcomes in PNL with minimal major complications is the correct selection of patients. A well-standardised technique and postoperative follow-up are mandatory for early detection of complications.

Adolescent↗

PubMed2006

Bipolar and multipolar radio frequency ablation with resistance controlled power output: standardized ex vivo kidney tissue evaluation.

PURPOSE: We investigated a newly developed bipolar and multipolar RF ablation system with an internally cooled electrode and resistance controlled power output in a standardized model of perfused ex vivo kidney tissue. MATERIALS AND METHODS: RF energy was applied at different power levels (20, 30 and 60 W) for 1, 3, 5 and 9 minutes. Each treatment parameter was repeated 5 times. For the 20/30 W levels a bipolar electrode with an active conducting part of 20/30 mm was selected. At 60 W 2 bipolar electrodes with an active conducting part (30 mm each) were connected. Lesion volumes and shapes were calculated by measuring the maximum vertical, long axis and short axis diameters of the macroscopic lesion. RESULTS: Lesion volume increased significantly with the treatment time and generator power applied (p < 0.0001). Lesion size in multipolar ablated zones was larger than that in bipolar ablated zones. A reliable dose-effect relationship existed between the generator power/applied treatment time and ablated tissue lesion size. All lesions were elliptical. CONCLUSIONS: Bipolar and multipolar RF ablation with an internally cooled electrode and tissue resistance control represent an interesting advance in RF technology. The development of lesion size and volume is predictable, while a uniform lesion shape can be achieved in perfused ex vivo kidney tissue. Further in vivo trials are required to test whether complete and reliable tumor tissue ablation is possible with this system.

Animals↗

PubMed2006

Magnetic resonance imaging for assessment of radiofrequency lesions in kidney tissue immediately after ablation: an experimental study.

BACKGROUND AND PURPOSE: Radiofrequency ablation (RFA) is an attractive minimally invasive treatment option for small renal masses. The purpose of this study was to investigate the morphologic imaging appearance of RF lesions immediately after the ablation of kidney tissue using standard clinical MR sequences, as well as to investigate the correlation between MR and gross lesion size. MATERIALS AND METHODS: Ablations were performed 17 times in a standardized model of ex-vivo perfused porcine kidneys using a resistance-controlled RF device (250 W, 470 kHz) and a nonexpandable bipolar applicator inserted into the center of healthy renal parenchyma. The RF current was applied for 9 minutes at 20 W. Imaging was performed after ablation using standard clinical MR sequences: morphologic T(1)/T(2)- weighted images and an isotropic post-contrast T(1) high-resolution measurement (VIBE). Maximum lesion diameters were measured in three directions and were compared with the measurements of the gross lesions. Histologic (hematoxylin + eosin and nicotinamide adenine dinucleotide staining) and statistical analyses were performed. RESULTS: The gross pathologic examination showed a firm, white-yellow ablation zone sharply demarcated from the untreated tissue. The histologic examination confirmed cellular viability outside but not in the treatment zone. The RF lesions were hyperintense on T(1)-weighted images and hypointense on T(2)-weighted images. The lesion size measured in the VIBE images correlated best with the macroscopic lesion size (N = 16). CONCLUSIONS: Morphologic MR T(1) and T(2) sequences of RF lesions immediately after ablation produce reliable and consistent imaging characteristics. The post-contrast, high-resolution sequence (VIBE) enables the extent of the lesion to be determined accurately. The potential uses of this imaging strategy in clinical practise warrant further investigation on human renal-cell carcinoma.

Animals↗

PubMed2006

Ablation of clinically relevant kidney tissue volumes by high-intensity focused ultrasound: Preliminary results of standardized ex-vivo investigations.

PURPOSE: To investigate strategies to achieve confluent kidney-tissue ablation by high-intensity focused ultrasound (HIFU). MATERIALS AND METHODS: Our model of the perfused ex-vivo porcine kidney was used. Tissue ablation was performed with an experimental HIFU device (Storz Medical, Kreuzlingen, Switzerland). Lesion-to-lesion interaction was investigated by varying the lesion distance (5 to 2.5 mm), generator power (300, 280, and 260 W), cooling time (10, 20, and 30 seconds), and exposure time (4, 3, and 2 seconds). The lesion rows were analyzed grossly and by histologic examination (hematoxylin-eosin and nicotinamide adenine dinucleotide staining). RESULTS: It was possible to achieve complete homogeneous ablation of a clinically relevant tissue volume but only by meticulous adjustment of the exposure parameters. Minimal changes in these parameters caused changes in lesion formation with holes within the lesions and lesion-to-lesion interaction. CONCLUSIONS: Our preliminary results show that when using this new device, HIFU can ablate a large tissue volume homogeneously in perfused ex-vivo porcine tissue under standardized conditions with meticulous adjustment of exposure parameters. Further investigations in vivo are necessary to test whether large tissue volumes can be ablated completely and reliably despite the influence of physiologic tissue and organ movement.

Animals↗

PubMed2006

Technical characterization of a new bipolar and multipolar radiofrequency device for minimally invasive treatment of renal tumours.

OBJECTIVE: To investigate the technical characteristics of a newly developed device for bipolar and multipolar radiofrequency ablation (RFA) of kidney tissue with a resistance-controlled power output. MATERIALS AND METHODS: The standardized model of the isolated perfused ex vivo porcine kidney was used. Two different applicators (20 and 30 mm active length) were selected for bipolar RFA, and one pair of applicators (2 x 30 mm active length) for multipolar RFA. RF energy was applied at different power levels (20, 30, 60 W) depending on the total active length of the electrodes. Treatment times were 1, 3, 5 and 9 min. The ablation cycles were recorded in continuous digital real-time and displayed on a monitor showing pre-set power, actual applied power, applied energy, tissue resistance, and impedance. Lesion sizes were measured macroscopically. A coagulation coefficient (coagulated tissue volume per applied energy unit) was calculated. RESULTS: There was a dosage-effect relationship between the generator power/treatment time and the sizes of the lesions. With increasing treatment time, less tissue volume was coagulated per unit of applied energy. The actual applied energy was lower than that calculated theoretically. The resistance and impedance values for the 30-W applicator were lower than those of the 20-W applicator. CONCLUSIONS: The technical features of this RFA device, with internally cooled bipolar and multipolar applicators and a resistance-controlled power output, represents an innovative improvement in RF technology. In vivo studies are needed to confirm the expected advantages and the suitability of this device for complete and reliable ablation of renal tumours.

Animals↗

PubMed2006

Intravenous contrast media in uroradiology: evaluation of safety and tolerability in almost 50,000 patients.

OBJECTIVE: To evaluate the frequency of adverse events and possible risk factors after the administration of an intravenous contrast medium (CM), iobitridol, in a large multicentre postmarketing surveillance study. SUBJECTS AND METHODS: A total of 49,975 patients undergoing intravenous urography were included in this study. A water-soluble, non-ionic CM (iobitridol, 1 ml/kg body weight) was administered. Age, sex, indication for the actual examination and adverse events were documented. Also, high-risk patients were identified. RESULTS: Of the 49,975 patients, 28,336 (56.7%) were males and 21,639 (43.3%) females. Indications for urography were mainly urolithiasis (39.1%), inflammatory diseases (25.6%) and tumours (13.9%). Additionally, 7.4% were risk patients: 1.9% with creatinine >1.5 mg/dl (0.1% were on haemodialysis); 0.8% had a history of previous allergic reactions to CM, 3.7% pre-existing asthma or allergies and 2% other risk factors against CM examination. Only 0.9% of the patients experienced acute adverse events that were non-serious and transient. Less than 0.1% of the patients experienced vomiting, dizziness or cardiovascular problems. Only 1 patient developed an anaphylactic shock but recovered fully under treatment. A chi(2) analysis revealed that adverse reactions occurred in patients with pre-existing renal insufficiency or allergies. Significantly more females had contrast-agent-related symptoms compared to men. Patients undergoing urography for urolithiasis had significantly fewer symptoms compared to patients with other indications. CONCLUSION: Iobitridol is clinically safe and well tolerated in urography as demonstrated in this study of a large patient population, producing mainly minor symptoms as adverse events. However, caution is advised when administering iobitridol to high-risk patients.

Acute Disease↗

PubMed2006

Intravesical mitomycin C for superficial transitional cell carcinoma.

Intravesical instillation of mitomycin C after a transurethral resection of a bladder tumor constitutes a standard treatment modality in the management of superficial transitional cell carcinoma in the urinary bladder. An immediate instillation of mitomycin C after transurethral resection has been shown to reduce the recurrence rate of superficial transitional cell carcinoma. Intravesical mitomycin C is generally considered to be a safe treatment option, but the past few years have seen the publication of a number of case reports on severe complications following mitomycin C instillation. This article reports on the mode of action, as well as the intravesical effects and current indications for mitomycin C instillation. This review will summarize the oncological benefits of mitomycin C in comparison with other intravesical treatments, such as bacillus Calmette-Guérin, and elucidate the incidence and types of possible complications associated with intravesical mitomycin C chemotherapy.

Administration, Intravesical↗

PubMed2006

[The isolated perfused porcine kidney model for investigations concerning surgical therapy procedures].

Experiments to develop innovative surgical therapy procedures are conventionally conducted on animals, as crucial aspects like tissue removal and bleeding disposition cannot be investigated in vitro. Extracorporeal organ models however reflect these aspects and could thus reduce the use of animals for this purpose fundamentally in the future. The aim of this work was to validate the isolated perfused porcine kidney model with regard to its use for surgical purposes on the basis of histological and radiological procedures. The results show that neither storage nor artificial perfusion led to any structural or functional damage which would affect the quality of the organ. The kidney model is highly suitable for simulating the main aspects of renal physiology and allows a constant calibration of perfusion pressure and tissue temperature. Thus, with only a moderate amount of work involved, the kidney model provides a cheap and readily available alternative to conventional animal experiments; it allows standardised experimental settings and provides valid results.

Animals↗

PubMed2005

IGF-II serum levels increase discrimination between benign prostatic hyperplasia and prostate cancer and improve the predictive value of PSA in clinical staging.

PURPOSE: IGF-I serum levels have been demonstrated as being associated with prostate cancer (PCa) and can serve as a predictive factor for the risk of PCa development. However, the role of IGF-II in PCa and its importance as a predictive marker is still unclear. Our aim was to determine PSA and IGF-II serum levels in patients with PCa and benign prostatic hyperplasia (BPH) and to analyse the value of IGF-II as an additional predictive factor in the diagnostics of PCa. METHODS: 112 patients who underwent surgery for BPH or PCa (no hormonal treatment, no further malignancies) were included in this study ((I) 38 PCa, PSA < or = 15 ng/ml; (II) 34 PCa, PSA > 15 ng/ml; (III) 40 BPH). Preoperative serum levels of total PSA and total IGF-II were determined by ELFA and ELISA, respectively. RESULTS: PSA levels were (I) 5.7+/-1.9 ng/ml; (II) 25.0+/-11.5 ng/ml and (III) 4.0+/-2.8 ng/ml. (II) was statistically associated with a high grading (2b/3; p = 0.0182), a high Gleason sum score (7-10; p = 0.0049) and a non-organ confined tumor (T3/4; p = 0.0009) compared to (I), all Chi2 test. IGF-II levels were significantly higher in PCa (I+II) compared to BPH (833.8+/-238.9 ng/ml vs. 633.3+/-141.4 ng/ml, p < 0.0001, t-test). Both PSA and IGF-II were associated with tumor staging (p = 0.0097, p = 0.0308; t-test). No significant correlation was observed between PSA and IGF-II levels. Logistic regression analysis revealed that the combination of PSA and IGF-II improves the prediction of tumor staging in PCa (p = 0.0175 and p = 0.0459, Wald test). Additionally, the combination of PSA and IGF-II can significantly increase discrimination between BPH and PCa; each p < 0.0001, Wald test. CONCLUSIONS: This study provides evidence that IGF-II serum levels may serve as an additional parameter for (a) improved determination of tumor staging and (b) better discrimination between BPH and PCa.

Aged↗

PubMed2005

5-year-follow-up of patients with clinically insignificant residual fragments after extracorporeal shockwave lithotripsy.

OBJECTIVES: After SWL treatment, many patients have residual fragments in the kidney or ureter. Fragments </=4mm have high probability to pass spontaneously and are normally not further treated. The term clinically insignificant residual fragment (CIRF) has been established for these stones. However, this term is still controversial, as persisting fragments might be important risk factors for stone growth and recurrence. Aim of this study was to evaluate the impact of CIRF on stone recurrence. METHODS: We evaluated 173 patients (age 3-89 years) who have been treated by SWL and released with CIRF. Mean follow up was 4.9 years (4.5-5.3). 78% of the patients were recurrent stone formers with >2 stones episodes. These patients and their referring urologist received follow-up questionnaires which contained questions about stone clearance, late complications, auxillary measures and dietary or drug metaphylaxis. RESULTS: Most residual stone fragments were located within the lower calyx (17%) and the renal pyelon (14%). Stone analysis was available in 142 patients with CIRF and revealed calciumoxalate calculi in 93.6% of the cases. In 78.6%, CIRF cleared spontaneously within few weeks and did not recur within 5 years. However, residual stones led to stone recurrence and need of re-treatment in 21.4%. Renal pyelon (23%) and calices showed comparable growth of former CIRF (lower calices 26.5%, middle calices 27%, upper calices 26%). Only 48% of the patients with recurrent stone formation followed dietary metaphylaxis. However, a significant correlation between a general or specific metaphylaxis and stone growth of CIRF could not be demonstrated. CONCLUSIONS: Most of the CIRF after SWL pass spontaneously without any complications. But considering that one fifth of the patients developed new stones at the side of residual fragments, it is obvious that close follow-up is required. Although we could not demonstrate a relation between metaphylaxis and stone re-growth, it is conceivable that adequate metaphylaxis can reduce stone recurrences.

Adolescent↗

PubMed2005

Minimally invasive treatment of renal cell carcinoma: comparison of 4 different monopolar radiofrequency devices.

OBJECTIVES: Radiofrequency Ablation is an investigational treatment option for RCC. The aim of our study was to test the ablation algorithms of four different RF systems in a standardized ex vivo perfused porcine kidney model. MATERIALS AND METHODS: A multiline monopolar dry electrode (impedance-based system), a multiline monopolar dry electrode (temperature-based system), a single monopolar wet electrode (impedance-based system) and a single monopolar dry, internally-cooled electrode (impedance-based system) were selected. RF energy was applied at different treatment parameters (power with and without control, tissue temperature, saline enhancement) for 1, 3, 5 and 9 minutes in healthy perfused ex vivo porcine tissue. Each treatment parameter was repeated 5 times. Maximum vertical, long-axis and short-axis diameters of the macroscopic lesion were measured and lesion volumes/ shapes were calculated. RESULTS: Lesion volumes increased significantly with the pre-selected tissue temperature and saline enhancement. Saline enhancement created larger, but irregular shaped lesions. The impedance-based system created lesion volumes that were predictable by treatment time and generator power. Lesions were unpredictable when uncontrolled generator power was applied. The created lesion shape was dependent on the selected electrode configuration. CONCLUSIONS: The currently available monopolar RFA systems offer different specific technical features to control tissue ablation. Detailed knowledge of the specific characteristics of each RF system is necessary to provide a higher chance of successful clinical outcome by complete and reliable ablation.

Animals↗

PubMed2005

Multiple high-intensity focused ultrasound probes for kidney-tissue ablation.

BACKGROUND AND PURPOSE: To investigate kidney-tissue ablation by high-intensity focused ultrasound (HIFU) using multiple and single probes. MATERIALS AND METHODS: Ultrasound beams (1.75 MHz) produced by a piezoceramic element (focal distance 80 mm) were focused at the center of renal parenchyma. One of the three probes (mounted on a jig) could also be used for comparison with a single probe at comparable power ratings. Lesion dimensions were examined in perfused and unperfused ex vivo porcine kidneys at different power levels (40, 60, and 80 W) and treatment times (4, 6, and 8 seconds). RESULTS: At identical power levels, the lesions induced by multiple probes were larger than those induced by a single probe. Lesion size increased with increasing pulse duration and generator power. The sizes and shapes of the lesions were predictably repeatable in all samples. Lesions in perfused kidneys were smaller than those in unperfused kidneys. CONCLUSIONS: Ex vivo, kidney-tissue ablation by means of multiple HIFU probes offers significant advantages over single HIFU probes in respect of lesion size and formation. These advantages need to be confirmed by tests in vivo at higher energy levels.

Animals↗

PubMed2005

New bipolar resection device for transurethral resection of the prostate: first ex-vivo and in-vivo evaluation.

BACKGROUND AND PURPOSE: Bipolar resection systems for transurethral resection of the prostate (TURP) offer some advantages over conventional monopolar devices. As both the active and the return electrode are placed on the tip of the resectoscope, current flow is locally limited, and negative effects caused by the current flow through the patient's body in the monopolar array can theoretically be reduced. Furthermore, bipolar resectoscopes use 0.9% sodium chloride solution as irrigation fluid, and therefore, the risk of TUR syndrome is theoretically eliminated. In this trial, we evaluated a new bipolar resectoscope in an ex-vivo model and in vivo and compared it with a standard monopolar resection device. MATERIALS AND METHODS: The modified model of the isolated blood perfused porcine kidney was used to determine cutting qualities, ablation rate, blood loss, and coagulation depth of the bipolar resection device compared with a monopolar resectoscope. A measurement system placed in the line between the generator and the patient was used to determine electric parameters when both resectoscopes were used in vivo. RESULTS: The ex-vivo evaluation showed worse cutting ability of the bipolar resection device compared with the monopolar resectoscope, with essential difficulties in starting a cut. The ablation rate was equal, as both resectoscopes had the same loop diameter. The bleeding rate was lower in bipolar (15.16+/-3.31 g/min) than monopolar (20.78+/-1.52 g/min) resection, whereas bipolar cutting resulted in marginally deeper coagulation zones (236.25+/-36.69 microm 216.0+/-42.25 microm). The in-vivo measurements made it clear that more power and more current is delivered to the patient during bipolar resection. The reason lies in a period at the beginning of each cut, when the patient's impedance is low and current flow high. CONCLUSION: Our results suggest that bipolar resection offers an alternative to conventional monopolar TURP. The advantage of a more localized energy field is at least in part compensated for by the higher generator output power during the procedure. Our ex-vivo results indicate a reduced bleeding rate compared with monopolar resection. Clinical studies have to be performed to prove the significance of our findings for patient treatment.

Animals↗

PubMed2005

Validation of computer-based training in ureterorenoscopy.

OBJECTIVES: To evaluate the outcome of training both urological novices and experts, using the recently developed UroMentor (Simbionix Ltd, Israel) trainer, that provides a realistic simulation of rigid and flexible ureterorenoscopy (URS). SUBJECTS AND METHODS: Twenty experienced urologists (total number of previous flexible URSs 21-153) were monitored during simulated flexible URS for treating a lower calyceal stone, and the outcome was correlated with individual experience. A score was compiled based on the variables recorded, including total operation time, stone contact time, complications such as bleeding or perforation, and treatment success. A further five urological residents with no endourological experience were trained on the UroMentor in rigid URS for ureteric stone treatment. Their acquired clinical skills were subsequently compared to those of five urological residents who received no simulator training. RESULTS: All 20 experienced urologists disintegrated the stone on the simulator, and the score achieved was related to their personal experience; there was a significant difference in performance in those with < 40 and > 80 previous flexible URSs. For the five urological residents with no endourological experience, simulator training improved their skills, and comparison with urological residents who had received no simulator training showed advantages for the trained residents. After being trained on the simulator, the group performed better in the first four URSs on patients. CONCLUSIONS: Individual experience correlates with individual performance on the simulator. Simulator training was helpful in improving clinical skills. Although the distribution of computer-based simulators is limited by high prices, virtual reality-based training has the potential to become an important tool for clinical education.

Clinical Competence↗

PubMed2005

Extracorporeal application of high-intensity focused ultrasound for prostatic tissue ablation.

OBJECTIVE: To investigate the efficacy and safety of extracorporeal prostatic tissue ablation using high-intensity focused ultrasound (HIFU) in vivo in animals, and in a clinical feasibility study in men, as this is an investigational minimally invasive treatment alternative for locally confined prostatic carcinoma, but may have significant side-effects. PATIENTS, MATERIALS AND METHODS: Ultrasound (1.04 MHz excitation frequency) was generated by an extracorporeal cylindrical piezo-ceramic element and focused by a paraboloidal reflector to a focal size of 32 x 4 mm. The focal distance and aperture diameter were both 100 mm. HIFU was applied extracorporeally at different intensities and pulse duration (up to 6 s) to 11 dog prostates in vivo (median intensity 1192 W/cm2) and eight patients (median intensity 3278 W/cm2, range 2384-3576) under general anaesthesia. The lesions were assessed macroscopically and histologically after HIFU and any side-effects evaluated. RESULTS: Thermoablation was feasible in vivo and in all patients. Macroscopic analysis and histology showed sharply demarcated coagulative necrosis. Side-effects, including skin and rectal burns, occurred only after transvesical application in the in vivo study. There were no side-effects in patients after perineal application. CONCLUSION: Extracorporeal HIFU is technically feasible and induces sharply demarcated tissue damage in the prostate. From the early results of this phase 1 study, the perineal approach seems to be safe.

Animals↗

PubMed2005

High-intensity focused ultrasound as a treatment option in renal cell carcinoma.

Due to the widespread use of modern imaging modalities, small renal masses are discovered incidentally at increasing rates. Advances in minimally invasive technologies have changed the treatment options for renal cell carcinoma. High-intensity focused ultrasound aims to completely ablate renal tumors in a noninvasive manner. Experimental studies have demonstrated principle feasibility and safety of the technology. However, clinical studies on renal cell carcinoma are very limited and no substantial oncologic results are available to date. Major technical improvements are mandatory to enable high-intensity focused ultrasound as an effective treatment option for patients with small renal masses.

Animals↗

PubMed2004

Cystinuria in childhood and adolescence: recommendations for diagnosis, treatment, and follow-up.

Cystinuria, an autosomal-recessive disorder of a renal tubular amino acid transporter, is the cause of about 10% of all kidney stones observed in children. Different genetic characteristics are not represented by different phenotypes. The stones are formed of cystine, which is relatively insoluble at the physiological pH of urine. Without any preventive measures, the patients will suffer from recurrent stone formation throughout their life. Even with medical management, long-term outcome is poor due to insufficient efficacy and low patient compliance. Many patients suffer from renal insufficiency as a result of recurrent stone formation and repeated interventions. However, regular follow-up and optimal pharmacotherapy significantly increase stone-free intervals. Medical management is mainly based on hyperhydration and urine alkalinization. Sulfhydryl agents such as tiopronin can be added. Recurrent stone formation necessitates repeated urological interventions. These mostly minimally invasive procedures carry the risk of impairment of renal function. In adults, extracorporeal shockwave lithotripsy (SWL) as well as intracorporeal lithotripsy is often unsuccessful. However, in children SWL shows excellent results for cystine stones. In cases with large stone burden, percutaneous nephrolithotripsy (PNL) or even open surgical nephrolithotomy are preferred. This review discusses the underlying pathogenetic mechanisms and provides guidance for the diagnosis, therapy, and management of cystinuria following the recommendations of the International Cystinuria Consortium and the European Association of Urology.

Adolescent↗

PubMed2004

Simple models improve the discrimination of prostate cancers from the peripheral gland by T1-weighted dynamic MRI.

Evaluation of the accuracy of descriptive and physiological parameters calculated from signal intensity-time curves using T1-weighted dynamic contrast enhanced MRI (DCE MRI) to differentiate prostate cancers from the peripheral gland. Twenty-seven patients with prostate cancers were examined with DCE MRI prior radical prostatectomy. Regions of interest were defined in tumors and non-affected areas in the peripheral zone. Dynamic data were parameterized in amplitude and exchange rate constant (kep) using a two-compartment model. Additionally, relative slope during 26, 39, 52 and 65 s, areas under the curve (AUC) and time to start of signal intensity increase (tlag) were determined. Vessel density (VD) of excised prostates was quantified in tumor areas using a CD34 stain. The parameter slope52 showed 20% higher values (P<0.001) in tumors than in the peripheral gland and compared with the other parameters the largest area under the ROC curve (0.81). The minimum total error rate was attained at a cut-point of 0.021, yielding a sample value of sensitivity and specificity of 70% and 88%, respectively, and a bias-corrected sum of sensitivity and specificity of 1.54. In addition, amplitude (P<0.001), kep (P=0.03) and AUC (P<0.001) were significantly higher in tumors. tlag did not discriminate carcinomas from glandular tissue. VD was higher in tumors than in the non-affected peripheral prostate (P=0.05). However, none of the dynamic parameters in carcinomas showed a significant correlation with VD or Gleason score. Although pharmacokinetic modeling in DCE MRI showed potential to discriminate prostate cancers from peripheral prostate tissue, descriptive parameters of the early signal enhancement after contrast media injection reached higher sensitivity and specificity.

Aged↗