Patient selection determines the prostate cancer yield of dynamic contrast-enhanced magnetic resonance imaging-guided transrectal biopsies in a closed 3-Tesla scanner
ABSTRACT To evaluate the cancer yield of transrectal prostate biopsies in a 3-T magnetic resonance imaging (MRI) scanner in patients with elevated prostate specific antigen (PSA) levels and recent negative transrectal ultrasonography (TRUS)-guided prostate biopsies.
Between July 2004 and November 2005, patients with at least one previous negative prostate biopsy within the previous 12 months had MRI-guided biopsy of the prostate in a 3-T MRI scanner. Patients with previous positive biopsies for cancer were excluded. Target selection was based on T2-weighted imaging and dynamic contrast-enhanced (DCE) imaging studies.
Thirteen patients were eligible; their median (range) age was 61 (47-74) years and PSA value 4.90 (1.3-12.3) ng/mL. Most patients had one previous negative biopsy (range 1-4). Four patients had a family history of prostate cancer. There were 37 distinct targets based on T2-weighted imaging. Fifteen of 16 distinct DCE abnormalities were co-localized with a target based on T2-weighted imaging. Despite this correlation, only one of 13 patients had a directed biopsy positive for cancer. Including systematic biopsies, two of 13 patients had a biopsy positive for prostate cancer. One patient had prostate intraepithelial neoplasia and one had atypical glands in the specimen.
The prostate-cancer yield of transrectal biopsies in a 3-T MRI scanner, among patients with recent negative TRUS-guided prostate biopsies, is similar to repeat systematic TRUS-guided biopsy. DCE correlates with T2-imaging but does not appear to improve prostate cancer yield in this population.
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ABSTRACT: Systematic transrectal ultrasound-guided biopsy (TRUSBx) is the gold standard for detecting prostate cancer. This systematic approach is characterized by low sensitivity (39-52%) and high specificity (81-82%). Magnetic resonance (MR)-guided biopsy techniques are becoming more and more available, but there is no current consensus on the optimal technique. This review presents an overview of MR-guided biopsy techniques for prostate cancer detection. Current literature was reviewed regarding MR-guided biopsy for prostate cancer detection. A literature search was performed using the commercially available MedLine online search engine. Combinations of the following search and Medical Subject Headings terms were applied to retrieve relevant articles: "magnetic resonance," "prostatic neoplasms," and "biopsy." Review articles and studies describing techniques other than MR-guided biopsy were excluded. Biopsy of the prostate is an essential procedure for determining optimal treatment. Systematic TRUSBx is the gold standard, but it fails to detect numerous tumors. Diagnostic MR imaging provides more accurate selection of regions in which tumors are suspected. Using these diagnostic images during an MR-directed biopsy procedure improves quality of the biopsy. In open MR scanners, the prebiopsy images often must be registered to the real-time biopsy images because open MR scanners do not provide optimal tissue contrast; thus, the patient must first be examined in a closed MR scanner and then biopsied in an open scanner. The advantage of open MR over closed MR is that the physician has easy patient access. With special equipment, prostate MR-guided biopsy is also possible in a closed system. Closed MR scanners can be used for the prebiopsy scan as well as for the biopsy procedure. The combination of a diagnostic MR examination and MR-guided biopsy is a promising tool and may be used in patients with previous negative TRUSBx.European Urology 07/2008; 54(3):517-27. DOI:10.1016/j.eururo.2008.06.001 · 12.48 Impact Factor
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ABSTRACT: Cyclodextrin glucanotransferase (CGTase) was produced when the Bacillus sp. TS1-1 was grown in a medium containing sago starch, yeast extract, phosphorus and mineral salt sources, using shake flask mode at 37 °C for 24 h. Response surface methodology (RSM) was applied to optimize the medium constituents with respect to CGTase production and activity. A 24 full factorial design (first order model) was carried out to identify the significant effect of medium components towards CGTase production. The variables involved in this initial screening study were sago starch, yeast extract, K2HPO4 and MgSO4·7H2O. Statistical analysis of results have shown that only sago starch and yeast extract have a significant effect on CGTase production. A second-order model was proposed by using 22 central composite design to represent the production CGTase activity as a function of sago starch and yeast extract. The optimized values of 1.48% and 1.89% of sago starch and yeast extract was obtained, respectively. Under these proposed optimized conditions, the model predicted a CGTase activity of 79.66 U/ml and via experimental rechecking the model, an activity of 84 U/ml was attained.Enzyme and Microbial Technology 10/2004; DOI:10.1016/j.enzmictec.2004.07.008 · 2.97 Impact Factor
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ABSTRACT: To assess the feasibility and early toxicity of selective, IMRT-based dose escalation (simultaneous integrated boost) to biopsy proven dominant intra-prostatic lesions visible on MRI. Patients with localized prostate cancer and an abnormality within the prostate on endorectal coil MRI were eligible. All patients underwent a MRI-guided transrectal biopsy at the location of the MRI abnormality. Gold fiducial markers were also placed. Several days later patients underwent another MRI scan for fusion with the treatment planning CT scan. This fused MRI scan was used to delineate the region of the biopsy proven intra-prostatic lesion. A 3 mm expansion was performed on the intra-prostatic lesions, defined as a separate volume within the prostate. The lesion + 3 mm and the remainder of the prostate + 7 mm received 94.5/75.6 Gray (Gy) respectively in 42 fractions. Daily seed position was verified to be within 3 mm. Three patients were treated. Follow-up was 18, 6, and 3 months respectively. Two patients had a single intra-prostatic lesion. One patient had 2 intra-prostatic lesions. All four intra-prostatic lesions, with margin, were successfully targeted and treated to 94.5 Gy. Two patients experienced acute RTOG grade 2 genitourinary (GU) toxicity. One had grade 1 gastrointestinal (GI) toxicity. All symptoms completely resolved by 3 months. One patient had no acute toxicity. These early results demonstrate the feasibility of using IMRT for simultaneous integrated boost to biopsy proven dominant intra-prostatic lesions visible on MRI. The treatment was well tolerated.Radiation Oncology 02/2007; 2:36. DOI:10.1186/1748-717X-2-36 · 2.36 Impact Factor