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Query: UMLS:C0376358 (prostate cancer)
 59,338 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cryosurgery has been shown to be an effective therapy for prostate cancer. Temperature monitoring throughout the cryosurgical iceball could dramatically improve efficacy, since end temperatures of at least -40 degrees C are required. The results of this study indicate that MR thermometry based on tissue R(*)(2) has the potential to provide this information. Frozen tissue appears as a complete signal void on conventional MRI. Ultrashort echo times (TEs), achievable with half pulse excitation and a short spiral readout, allow frozen tissue to be imaged and MR characteristics to be measured. However, half pulse excitation is highly sensitive to eddy current distortions of the slice-select gradient. In this work, the effects of eddy currents on the half pulse technique are characterized and methods to overcome these effects are developed. The methods include: 1) eddy current compensated slice-select gradients, and 2) a correction for the phase shift between the first and second half excitations at the center of the slice. The effectiveness of these methods is demonstrated in R(*)(2) maps calculated within the frozen region during cryoablation.
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PMID:Temperature mapping of frozen tissue using eddy current compensated half excitation RF pulses. 1167 51

We retrospectively studied the staging accuracy of magnetic resonance (MR) imaging after neoadjuvant hormonal therapy (NAH) for 21 localized prostate cancers. MR imaging was performed using a 1.5-Tesla magnetic resonance system with a pelvic phased array coil. T2-weighted MR images were obtained on axial and coronal planes, and T1-weighted MR images using the dynamic technique with Gd-DTPA bolus enhancement were obtained in axial planes for each patient. On T2-weighted imaging, the signal intensity of the normal tissue in the peripheral zone became lower after NAH. Therefore, it was more difficult to detect residual malignant lesions in many cases than before NAH. The accuracy of T staging for prostate cancer after NAH in MRI was 71%. The accuracy, sensitivity, and specificity of the extracapsular invasion was 76%, 0% and 94%, respectively, and those of the seminal vesicular invasion 85%, 0% and 100%, respectively. While 2 of the 4 patients judged as downstaged cases in MRI showed corresponding pathological findings, 5 of the 21 cases (23.8%) were underdiagnosed. Local staging with only MRI for prostate cancer after NAH seems to have limits in applicability.
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PMID:[Local staging with magnetic resonance imaging after neoadjuvant hormonal therapy for prostate cancer]. 1169 96

One of the most lethal aspects of cancer arises from its ability to invade and metastasize. Determining the factors that promote cancer cell invasion and metastasis is therefore critically important in treating this disease. The tumour physiological environment is uniquely different from normal tissue, and exhibits hypoxia, acidic extracellular pH and high levels of lactate. This environment, dictated largely by abnormal tumour vasculature and metabolism, in turn also promotes angiogenesis. The physiological environment, tumour metabolism, angiogenesis and vascularization are therefore inextricably linked. We have developed and applied non-invasive magnetic resonance (MR) imaging (I) and spectroscopy (S) techniques to understand the role of vascular, physiological and metabolic properties in cancer invasion and metastasis. These MR studies are performed with human breast and prostate cancer cells maintained in culture or grown as solid tumours in immune-suppressed mice. We have detected significant differences in vascular, physiological and metabolic characteristics of metastatic and non-metastatic human breast and prostate cancer models with MRI and MRS. Using a combined MRI/MRS approach we are currently acquiring metabolic, extracellular pH and vascular images from the same localized regions within a solid tumour to further understand the dynamics between these parameters and their role in cancer invasion and metastasis.
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PMID:The physiological environment in cancer vascularization, invasion and metastasis. 1172 32

The aim of the study was to establish the normal range and to evaluate the reproducibility of dynamic contrast enhanced MRI (DCE-MRI) parameter estimates in normal human pelvic tissues. Nineteen patients with prostate cancer, undergoing androgen deprivation treatment, had paired DCE-MRI examinations of the pelvis using spoiled gradient-echo sequences. Quantitative enhancement parameters were calculated for each examination: transfer constant (K(trans)), leakage space (v(e)) and maximum contrast medium accumulation (MCMA) of pelvic muscles, bone marrow and fat. Descriptive and reproducibility statistics were calculated: within-patient standard deviation (wSD), repeatability and within-patient coefficient of variation (wCV). The femoral head and ischiorectal fat showed large numbers of non-enhancing pixels (81 and 88%, respectively). The ischial bone marrow had the highest values of kinetic parameter estimates (K(trans) 0.554 min(-1), v(e) 18.5% and MCMA 0.164 mmol/kg). Muscle parameters values were lower (K(trans) 0.126-0.137 min(-1), v(e) 10.6-11.5% and MCMA 0.077-0.086 mmol/kg). The mean difference between paired examinations was not significantly different from zero for any parameter. v(e) and MCMA had the lowest wCV (between 19 and 29%). For individuals, a log(10) K(trans) change of approximately 0.90 in muscles and 0.52 in the ischium would be statistically significant. The corresponding absolute changes for v(e) are 6.7% in muscle and 13.6% in the ischium. For a group of 19 patients, small changes are statistically significant (muscle log(10) K(trans) 0.208 and v(e) 1.5% and ischium log(10) K(trans) 0.123 and v(e) 3.1%). Fat and the femoral head are unreliable tissues from which to obtain kinetic parameter estimates due to poor enhancement. v(e) and MCMA have smaller coefficient of variation than K(trans) in muscles and ischium. Reproducibility studies of normal and pathological tissues should be incorporated into clinical research protocols that measure treatment effects by DCE-MRI techniques.
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PMID:Reproducibility of quantitative dynamic MRI of normal human tissues. 1187 Sep 10

A three-dimensional (3D) mutual information registration method was created and used to register MRI volumes of the pelvis and prostate. It had special features to improve robustness. First, it used a multi-resolution approach and performed registration from low to high resolution. Second, it used two similarity measures, correlation coefficient at lower resolutions and mutual information at full resolution, because of their particular advantages. Third, we created a method to avoid local minima by restarting the registration with randomly perturbed parameters. The criterion for restarting was a correlation coefficient below an empirically determined threshold. Experiments determined the accuracy of registration under conditions found in potential applications in prostate cancer diagnosis, staging, treatment and interventional MRI (iMRI) guided therapies. Images were acquired in the diagnostic (supine) and treatment position (supine with legs raised). Images were also acquired as a function of bladder filling and the time interval between imaging sessions. Overall studies on three patients and three healthy volunteers, when both volumes in a pair were obtained in the diagnostic position under comparable conditions, bony landmarks and prostate 3D centroids were aligned within 1.6 +/- 0.2 mm and 1.4 +/- 0.2 mm, respectively, values only slightly larger than a voxel. Analysis suggests that actual errors are smaller because of the uncertainty in landmark localization and prostate segmentation. Between the diagnostic and treatment positions, bony landmarks continued to register well, but prostate centroids moved towards the posterior 2.8-3.4 mm. Manual cropping to remove voxels in the legs was necessary to register these images. In conclusion, automatic, rigid body registration is probably sufficiently accurate for many applications in prostate cancer. For potential iMRI-guided treatments, the small prostate displacement between the diagnostic and treatment positions can probably be avoided by acquiring volumes in similar positions and by reducing bladder and rectal volumes.
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PMID:Automatic MR volume registration and its evaluation for the pelvis and prostate. 1193 73

The literature on spinal cord involvement in prostate cancer is reviewed by searching the Medline from 1965 to 1997 and references in publications on the subject. The objective was to identify the clinical characteristics and treatment modalities of the disease. Prostate cancer is the leading cause of metastatic spinal cord disease in men. The tumour reaches the spinal column mainly by the venous route. The frequency of involvement in decreasing order is thoracic spine, lumbar spine and cervical spine. The tumour usually exerts compression of the cord from the extradural space. However, intradural and intramedullary metastases have devastating effects. The patients have other neurological and urological symptoms prior to the onset of paraplegia. But in some, spinal cord compression may be the first symptom of prostate cancer. Plain X-rays may suffice in diagnosis but MRI is the single most valuable investigation for anatomic definition or localization of spinal cord secondaries. All forms of treatment are palliative. Treatment options, singly or in combination, include hormonal manipulation, radiotherapy and laminectomy each often with high dose corticosteroids. Recurrence of symptoms after an initial relief with hormonal manipulation signifies escape of the tumour from endocrine control and portends a poor prognosis.
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PMID:Symptomatic spinal cord involvement in prostate cancer. 1195 73

For many anticancer therapies, it would be desirable to accurately monitor and quantify tumor response early in the treatment regimen. This would allow oncologists to continue effective therapies or discontinue ineffective therapies early in the course of treatment, and hence, reduce morbidity. This is especially true for second-line therapies, which have reduced response rates and increased toxicities. Previous works by others and ourselves have shown that water mobility, measured by diffusion-weighted magnetic resonance imaging (DW-MRI), increases early in tumors destined to respond to therapies. In the current communication, we further characterize the utility of DW-MRI to predict response of prostate cancer xenografts to docetaxel in SCID mice in a preclinical setting. The current data illustrate that tumor volumes and secreted prostate-specific antigen both respond strongly to docetaxel in a dose-responsive manner, and the apparent diffusion coefficient of water (ADC(w)) increases significantly by 2 days even at the lowest doses (10 mg/kg). The ADCw data were parsed by histogram analyses. Our results indicate that DW-MRI can be used for early detection of prostate carcinoma xenograft response to docetaxel chemotherapy.
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PMID:Early response of prostate carcinoma xenografts to docetaxel chemotherapy monitored with diffusion MRI. 1198 45

In the last decade, brachytherapy emerged as a particularly appealing new way ot treating localized prostate cancer. Recently published 10-12 years biochemical control results appear to be superimposable to the best percentages achieved by surgery or conformal radiotherapy, with a small percentage of complications. This applied to severely patients. Only patients with T1/T2, PSA < 10 ng/mL, and Gleason score < 7 should be proposed such a treatment. The potential benefit of exploring patients with a endorectal coil MRI is being evaluated. The number of positive biopsies is also a parameter which should probably be considered in the therapeutic choice. Moreover, a prostate volume > 60 g, hip mobility limitations, a urinary obstructive syndrome and previous transurethral resection lead to difficulties in technical implantation and therefore must be taken into account when discussing brachytherapy. In conclusion, for adequately selected patients, brachytherapy offers a particularly applied alternative to surgery and external radiotherapy, with satisfactory long term biochemical control rates and limited complications.
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PMID:[Indications for curietherapy of the prostate using permanent implants]. 1211 40

To report a technique for target directed transperineal ultrasound guided biopsy using high resolution endorectal MRI images Ultrasound fusion. Two patients presented after external beam irradiation for prostate cancer with a rising PSA. An Endorectal MRI using a 1.5 Tesla scanner was obtained. Subsequently a Transrectal Ultrasound guided biopsy was performed. The Ultrasound probe was fixed to a stepper-stabilizer to provide a reference coordinate system for stereotaxic needle biopsy needle placement. The MRI image set was fused to the Ultrasound images in real time. Abnormal areas determined in the MR images were targeted for biopsy. Recurrent prostate carcinoma was detected pathologically in 3 of 4 stereotactic biopsies. Abnormal areas suspicious for cancer detected on T1 weighted images obtained in a strong field Endorectal MRI scan can be targeted for stereotactic biopsy using Transrectal Ultrasound. This image guide technique may be very useful in directing biopsies.
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PMID:Real time MRI-ultrasound image guided stereotactic prostate biopsy. 1211 12

The objective of this study was to assess the utility of CT-MRI image fusion software and compare both prostate volume and localization with CT and MRI studies. We evaluated the differences in clinical volumes in patients undergoing three-dimensional conformal radiation therapy for localized prostate cancer. After several tests performed to ensure the quality of image fusion software, eight patients suffering from prostate adenocarcinoma were submitted to CT and MRI studies in the treatment position within an immobilization device before the start of radiotherapy. The clinical target volume (CTV) (prostate plus seminal vesicles) was delineated on CT and MRI studies and image fusion was obtained from the superimposition of anatomical fiducial markers. A comparison of dose-volume histograms relative to CTV, rectum, bladder and femoral heads was performed for both studies. Image fusion showed a mean overestimation of CTV of 34% with CT compared with MRI. Along the anterior-posterior and superior-inferior direction, CTV was a mean 5 mm larger with CT study compared with MRI. The dose-volume histograms resulting from CT and MRI comparison showed that it is possible to spare a mean 10% of rectal volume and approximately 5% of bladder and femoral heads, respectively. This study confirmed an overestimation of CTV with CT images compared with MRI. Because this finding only allows a minimal sparing of organs at risk, considering the organ motion during each radiotherapy session and the excellent outcomes of prostate cancer treatment with CT based target identification, we are still reluctant to reduce the CTV to that identified by MRI.
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PMID:CT-MRI image fusion for delineation of volumes in three-dimensional conformal radiation therapy in the treatment of localized prostate cancer. 1214 34


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