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Katsuto Shinohara

Publications and source records attributed to Katsuto Shinohara.

16 recordsLinked to original sources
PubMed2004

Use of MRI and spectroscopy in evaluation of external beam radiotherapy for prostate cancer.

PURPOSE: To characterize the metabolic response in the prostate, the time to resolution of disease, and the correlation between magnetic resonance imaging (MRI) with spectroscopy (MRSI) results, biopsy findings, and serum prostate-specific antigen (PSA) level after external beam radiotherapy. METHODS AND MATERIALS: A total of 55 patients underwent MRSI before and/or at varying times after external beam radiotherapy. The percentage of the cancerous, healthy, and atrophic voxels was calculated, and the time to resolution of disease was determined and compared with the PSA nadir. RESULTS: Of the 55 patients, 70% had negative MRSI and 30% had positive MRSI findings. A strong correlation was found between negative MRSI and negative biopsy findings (n = 11) and between positive MRSI and positive biopsy findings (n = 7). A weak correlation was observed between the PSA level and the MRSI and biopsy findings. The mean time to disease resolution was 40.3 months and the mean time to PSA nadir was 50 months. With time, an increase in atrophy and a decline in cancerous metabolism was found. CONCLUSION: When used in conjunction with PSA measurement and biopsy, the results of this study suggest that MRSI contributes to a greater level of confidence in determining the outcome and may be a useful adjunct for assessing local control before PSA failure when striving to distinguish the benign "blip" from local recurrence.

Androgen Antagonists↗
PubMed2004

Prostate movement during simulation resulting from retrograde urethrogram compared with "natural" prostate movement.

PURPOSE: Retrograde urethrography (UG) is commonly used at the time of simulation to assist in defining the prostate apex. Some investigators have reported that performing the UG introduces error by causing prostate displacement. We investigate the movement of the prostate caused by the retrograde UG. METHODS AND MATERIALS: Twenty-four patients treated with three-dimensional conformal radiotherapy for prostate cancer who had gold marker seeds placed into their prostates were studied. Marker seed locations at the time of simulation and on the portal images acquired just before the treatment were compared with the locations on digitally reconstructed radiographs (DRR). Movement in the superior-inferior and anteroposterior directions as seen on lateral images was measured from 402 portal images by offline customized imaging software and evaluated using analysis of variance methods for continuous variables and chi-square statistics for categoric variables. RESULTS: "Natural" nonrandom movement of the prostate around an "origin" as defined by markers on DRR was observed. This movement tends to be in a superior and anterior direction, with the average shift being 1 mm and 0.82 mm, respectively. The magnitude of movement in the superior direction averaged 2.88 mm compared with 1.64 mm in the inferior direction (p = 0.04). There was slightly greater movement after the UG compared with mean "natural" movement but the difference was less than 3 mm in either direction on average (difference: superior-inferior = 2.64 mm, p = 0.004; anteroposterior = 2.24, p = 0.035). CONCLUSIONS: Use of the UG induces a small but clinically insignificant displacement of the prostate when "natural" movement is taken into account.

Humans↗
PubMed2004

Endorectal MR imaging and MR spectroscopic imaging for locally recurrent prostate cancer after external beam radiation therapy: preliminary experience.

PURPOSE: To evaluate endorectal magnetic resonance (MR) imaging and MR spectroscopic imaging for the depiction of locally recurrent prostate cancer after external beam radiation therapy. MATERIALS AND METHODS: Endorectal MR imaging and MR spectroscopic imaging were performed in 21 patients with biochemical failure after external beam radiation therapy for prostate cancer. Two readers independently and retrospectively reviewed MR images and rated the likelihood of recurrent tumor on a five-point scale. Spectroscopic voxels were considered suspicious for malignancy if the choline level was elevated and citrate was absent. Receiver operating characteristic curve analysis was used to assess cancer detection in each side of the prostate with endorectal MR imaging and spectroscopic imaging at different thresholds based on the scores assigned by the two readers and on the number of suspicious voxels in each hemiprostate, respectively. The presence or absence of cancer at subsequent transrectal biopsy was used as the standard of reference. RESULTS: Biopsy demonstrated locally recurrent prostate cancer in nine hemiprostates in six patients. The area under the receiver operating characteristic curve for the detection of locally recurrent cancer with MR imaging was 0.49 and 0.51 for readers 1 and 2, respectively. By using the number of suspicious voxels to define different diagnostic thresholds, the area under the receiver operating characteristic curve for MR spectroscopic imaging was significantly (P < .005) higher, at 0.81. In particular, the presence of three or more suspicious voxels in a hemiprostate showed a sensitivity and specificity of 89% and 82%, respectively, for the diagnosis of local recurrence. Seven hemiprostates demonstrated complete metabolic atrophy at spectroscopic imaging and only postirradiation atrophy at biopsy. CONCLUSION: Preliminary data suggest that MR spectroscopic imaging, but not endorectal MR imaging, may be of value for the depiction of locally recurrent prostate cancer after radiation therapy.

Aged↗
PubMed2004

Time to metabolic atrophy after permanent prostate seed implantation based on magnetic resonance spectroscopic imaging.

PURPOSE: To characterize the time to metabolic atrophy (TMA) after permanent prostate implantation (PPI) using combined MRI and magnetic resonance spectroscopic imaging (MRSI) compared with the time to prostate-specific antigen (PSA) nadir. METHODS AND MATERIALS: This study was based on a posttreatment analysis comparing the MRI/MRSI findings with the PSA levels of 65 patients treated with PPI alone or combined with external beam radiotherapy and/or HT. The fraction of interpretable voxels demonstrating metabolic atrophy was used to compare the TMA with the time to PSA nadir. RESULTS: The fraction of patients with metabolic atrophy in >95% of usable voxels after PPI increased from approximately 46% to 100% at 6 and 48 months, respectively. The mean time for PSA nadir vs. TMA was 42.5 vs. 28.9 months (PPI), 32.8 vs. 25.6 months (external beam radiotherapy + PPI), and 25.3 vs. 28.0 months (external beam radiotherapy + hormonal therapy + PPI). CONCLUSION: Magnetic resonance spectroscopic imaging may provide an early tool for evaluating the treatment response for patients treated with PPI. If supported by longer follow-up, TMA may be a useful adjunct to PSA measurement for assessing local control after PPI and could be useful in evaluating the complex relationships between the quality of the implant and the time to indication of successful therapy.

Brachytherapy↗
PubMed2004

Daily electronic portal imaging for morbidly obese men undergoing radiotherapy for localized prostate cancer.

PURPOSE: We summarize our experience with a series of morbidly obese men treated using daily online portal imaging and implanted gold markers to guide external beam radiation therapy (EBRT). METHODS AND MATERIALS: Three consecutive morbidly obese men were treated with EBRT for localized prostate cancer. Daily electronic portal imaging was used to verify patient position. The magnitude and direction of patient positioning error were documented for each fraction. RESULTS: The absolute magnitude of positioning error was greatest in the left-right direction with a mean of 11.4 mm/fraction (median, 8 mm; range, 0-42 mm). Mean error in the superior-inferior direction was also substantial at 7.2 mm/fraction (median, 5 mm; range, 0-47 mm). Anteroposterior error was the least problematic with a mean value of 2.6 mm/fraction (median, 2.5 mm; range, 0-8 mm). CONCLUSIONS: Daily electronic portal imaging combined with gold fiducial markers dramatically improves the precision of EBRT in the treatment of morbidly obese men with prostate cancer. Setup error rather than organ motion appears to be the dominant force in positioning error in obese men.

Gold↗
PubMed2004

A prospective comparison of 3 diagnostic methods to evaluate ejaculatory duct obstruction.

PURPOSE: Various diagnostic tests are available to evaluate patients with ejaculatory duct obstruction (EDO). However, the most accurate diagnostic technique, defined as the one that best predicts a successful outcome after ejaculatory duct resection, is unclear. We prospectively performed transrectal ultrasound (TRUS) and 3 other tests in men with EDO and determined their relative value in this diagnosis. MATERIALS AND METHODS: Patients with suspected EDO on clinical evaluation that included TRUS proceeded to further intraoperative evaluation with duct chromotubation, seminal vesicle aspiration and seminal vesiculography. A comparative analysis of findings from each technique was performed and the success of subsequent transurethral resection procedures was assessed. RESULTS: All 25 patients had evidence of EDO on diagnostic TRUS, a finding that merited further evaluation with other modalities. However, TRUS findings correlated poorly with those of the other diagnostic tests. Obstruction on TRUS was confirmed in only 52%, 48% and 36% of vesiculography, seminal vesicle aspiration and duct chromotubation studies, respectively. A better correlation was observed between the dynamic tests of duct chromotubation and seminal vesiculography. Based on all diagnostic tests only 12 patients (48%) proceeded to duct resection, of whom 10 (83%) showed significant improvement in semen analysis parameters or clinical symptoms after the procedure. CONCLUSIONS: A comparative analysis of 4 diagnostic techniques suggests that TRUS alone has poor specificity for EDO evaluation. Incorporating dynamic tests into the algorithm of EDO diagnosis may decrease unnecessary duct resection procedures and improve the success of the resection procedures that are indicated.

Adolescent↗
PubMed2004

Ferromagnetic thermal ablation of locally recurrent prostate cancer: prostate specific antigen results and immediate/intermediate morbidities.

PURPOSE: Curative options for locally recurrent prostate cancer following external beam radiotherapy are limited due to the significant morbidity associated with surgical therapy. ThermoRods (Ablation Technologies, San Diego, California) are permanently implantable, 14 mm cobalt-palladium alloy rods that produce heat through oscillation of a magnetic field. The rod is designed to self-regulate the temperature to 70C by a temperature dependent magnetic transition (Curie effect). We determined whether patients with prostate cancer and local failure could be treated with thermal ablation of the prostate using this novel technology. MATERIALS AND METHODS: A total of 14 men with an average age of 72 years (range 62 to 81) were enrolled in the study. All had biopsy proven prostate cancer with increasing prostate specific antigen (PSA) (1.0 to 10.3 ng/ml). The seminal vesicles were not routinely biopsied. Metastatic disease was assayed in all men with bone scan and in later patients with abdominopelvic computerized tomography. Patients had ThermoRods placed under transrectal ultrasound guidance, similar to brachytherapy. The pre-plan was rigorously followed to produce a 3-dimensional array with rods separated by 1 cm across the short axis. Patients were treated in a magnetic field for 1 hour. Urethral and rectal temperatures were also monitored and cooled appropriately. Serial PSA measurements and 6 month posttreatment biopsies were obtained after the procedure. RESULTS: Average time since radiation was 4.5 years. PSA nadir values after radiation were between 0.3 and 2.2 ng/ml. Prostatic temperatures were homogeneously increased greater than 50C, while rectal and urethral temperatures did not exceed 44C at any point. The urethral catheter was removed 2 weeks postoperatively in all cases. Six months after the procedure 8 of the 14 men (57%) had a PSA decrease to less than 0.1 ng/ml. Complications included urinary retention as well as incontinence. Incontinence was generally temporary and only 1 patient (7%) had long-term incontinence. Most patients were impotent after treatment. Of the patients 21% experienced urinary retention. Five patients (36%) needed to undergo secondary procedures after therapy, including transurethral prostate resection in 2, balloon dilation in 1, cystoscopic removal of necrotic tissue in 1 and bladder irrigation in 1. CONCLUSIONS: This novel means of thermal ablation produces significant PSA decreases in patients. Morbidity is predominantly in the form of incontinence and impotence. Incontinence is generally temporary. The use of ferromagnetic rods enables the precise control of tissue destruction with the sparing of immediately adjacent structures. The technology uses skills familiar to the urologist and avoids radiation. The durability of the PSA response and incidence of late morbidity remain to be defined.

Aged↗
PubMed2003

(Non)-migration of radiopaque markers used for on-line localization of the prostate with an electronic portal imaging device.

PURPOSE: Radiopaque gold markers can be implanted in the prostate to visualize its position on portal images during radiation therapy. This procedure assumes that the markers do not move within the prostate. In this work we test this assumptiom. METHODS AND MATERIALS: Three markers were implanted transrectally in the prostate of patients undergoing external radiation therapy. An orthogonal pair of portal images was acquired periodically throughout the course of radiation therapy with an a-Si electronic portal imaging device (EPID). The marker coordinates were determined, and the distances between the implanted markers were recorded. The distance time trend is used to evaluate the magnitude of marker migration. RESULTS: The average standard deviation (SD) of the distances between markers was 1.3 mm (range 0.44 to 3.04 mm). Three of the 11 patients show a SD larger than 2 mm. For these patients, all three distances show a simultaneous reduction with time, compatible with a shrinking of the prostate. All had been treated with neoadjuvant hormone therapy. For 1 of the 3 patients, this reduction in volume was confirmed with a repeat computed tomographic scan. CONCLUSION: None of the 33 markers studied migrated significantly. The implantation of three radiopaque gold markers enables accurate and precise on-line verification of the prostate position during external beam radiation therapy. The use of three markers provides a tool to monitor prostate position and volume changes that can occur over time due to hormone or radiation therapy.

Gold↗
PubMed2003

Transperineal prostate biopsy after abdominoperineal resection.

PURPOSE: Prostate cancer evaluation in men who have undergone abdominoperineal resection poses a challenge for urologists. Diagnosis and staging methods are limited because as access to the prostate via digital rectal examination is not possible. Prostate specific antigen (PSA) has been used to screen for malignancy in this population. However, the conventional diagnostic technique with transrectal ultrasound guided biopsies cannot be used. Transperineal ultrasound and biopsy have been described to evaluate the prostate in this setting. We report our experience with transperineal ultrasound biopsy for evaluating the prostate in patients with elevated PSA who have previously undergone abdominoperineal resection. MATERIALS AND METHODS: We reviewed the records of 28 patients treated at 2 institutions. All patients had a history of abdominoperineal resection and subsequent transperineal ultrasound guided prostate biopsy for evaluating elevated PSA. Mean serum PSA in this population was 22 ng./ml. (median 9.5, range 4.1 to 237). Abdominoperineal resection was done in 16 patients (57%) for colorectal cancer, in 11 (39%) for ulcerative colitis and in 1 (4%) for familial polyposis coli. Average time since resection was 14 years (range 1 to 33). Five patients had previously undergone radiation therapy as part of treatment for colorectal cancer before transperineal ultrasound biopsy. RESULTS: Of the 28 biopsies performed 23 revealed prostate cancer, 2 revealed prostatitis and 3 were benign. Average Gleason grade was 6.6 (range 3 to 9). Of the 23 patients with prostate cancer 22 were treated with androgen deprivation therapy (7), prostatectomy (8), external beam (6) and high dose (1) radiation therapy. Of the 8 patients who underwent prostatectomy pathological stage was T2 in 3 and T3 in 4, while pathological findings were not determined in 1 patient in whom the prostate was removed in pieces. CONCLUSIONS: In patients with a history of abdominoperineal resection and elevated PSA transperineal ultrasound guided biopsy of the prostate can provide an accurate tissue diagnosis.

Abdominal Wall↗
PubMed2003

Imaging clinically localized prostate cancer.

At this time there is no highly sensitive and specific widespread radiographic test for local staging of prostate cancer. Future developments will likely require a combination of imaging modalities with utilization guided by risk-stratification models (Table 4). Staging data for all imaging tests discussed in this article are summarized in Tables 5 and 6. Clinically, conventional gray-scale TRUS remains the most frequently used tool because of its utility in guiding prostatic biopsies. Modifications of TRUS--including power and color Doppler, 3D imaging, and new ultrasound contrast agents and elastography--show promise in increasing the accuracy of ultrasound. Endorectal MRI may have some value for staging selected patients. The addition of prostatic MRS, which images the differential activity of metabolites, may increase the specificity of MRI. Newer techniques with finer voxel resolution may prove to be clinically useful. A large well-designed study evaluating the utility of MRI/MRS is currently being planned. Cross-sectional imaging of the pelvis with either MRI or CT should be used selectively as should radionuclide bone scans. Similarly, ProstaScint scans should be ordered selectively, either before or after primary therapy, rather than routinely in all patients.

Antibodies, Monoclonal↗
PubMed2003

Prostate cancer: cryotherapy.

The incidence of prostate cancer has more than doubled in the last 10 years, and 220,900 new cases will be detected in 2003. This increase is due in large part to increased use of prostate-specific antigen (PSA)-based screening, transrectal ultrasonography, and random biopsy of the prostate. The treatment of prostate cancer, however, remains controversial, and no consensus has been established as to what constitutes appropriate treatment for any stage of disease, especially for localized cancers. Radical prostatectomy, radiation therapy, or watchful waiting all have their advocates, and the risks and benefits of these approaches are discussed frequently. Skepticism about conventional treatments has stimulated patients and physicians to search for alternatives that are effective and associated with limited morbidity. Technologic developments have rekindled interest in cryotherapy as a viable alternative to other, more conventional localized therapies. Given the relative paucity of alternatives for patients who experience biochemical progression after radiotherapy, cryosurgery also may prove to be a good alternative for those patients whose tumors appear to remain localized despite progression. In addition, it appears that cryosurgery will play an increased role in the future management of prostate cancer.

Cryotherapy↗
PubMed2002

Sextant prostate biopsies predict side and sextant site of extracapsular extension of prostate cancer.

PURPOSE: We examined the ability of sextant prostate biopsies in combination with other preoperative data to predict side and sextant site of prostate cancer extracapsular extension in a large cohort of patients. MATERIALS AND METHODS: We examined 223 contemporary cases of prostate cancer managed by radical prostatectomy. Using logistic regression analysis, we determined whether patient age, Gleason score, clinical stage, prostate specific antigen, number of positive sextants, biopsy location or percent of biopsy cores positive for cancer in a sextant site, side and overall gland was predictive of location of pathological extracapsular extension into periprostatic tissue. RESULTS: Of 41 of the 223 (18%) patients with nonorgan confined disease extracapsular extension was localized to 45 sextant sites in 36 (apex 8, mid 22, base 15) while only side of extension was known in 5. In a multivariate analysis the best predictors of the risk of extracapsular extension on a side were average percent biopsy cores positive for cancer overall 15 or greater (odds ratio 8.4, p <0.0001) and average from 3 ipsilateral biopsies 15 or greater (odds ratio 7.4, p <0.0001). When used in combination these 2 factors yielded a model with a positive predictive value of 37% and a negative predictive value of 95%. Sextant specific percent biopsy cores positive for cancer was predictive of risk of extracapsular extension in a sextant (odds ratio 2.5, p = 0.020). CONCLUSIONS: Our data demonstrate that average overall and per side percent biopsy cores positive for cancer is a significant predictor of risk of extracapsular extension on a side. Sextant specific percent biopsy cores positive for cancer is predictive of sextant site of extension. The high negative predictive value of the side specific model identifies patients who are good candidates for nerve sparing surgery.

Adult↗
PubMedDate not supplied

Significance of high-grade prostatic intraepithelial neoplasia on prostate biopsy.

The early diagnosis of prostate cancer has been facilitated by the development of serum prostate-specific antigen (PSA) testing and evolution in transrectal ultrasound-guided biopsy of the prostate. Over a decade has passed since the initial recommendations for systematic sextant sampling of the prostate to increase the accuracy of cancer detection. Subsequently, variations in the number and location of biopsies have been proposed to maximize prostate cancer detection and obtain more complete information regarding tumor grade, tumor volume, and local stage. Although current biopsy strategies provide a wide sampling of the prostate gland, biopsy histology may not be conclusive for either the presence or absence of adenocarcinoma. High-grade prostatic intraepithelial neoplasia (HGPIN) is found in a significant fraction of patients undergoing transrectal prostate biopsies. In this article, we discuss the significance of high-grade prostatic intraepithelial neoplasia and other abnormal histology findings and current evidence addressing the presence of cancer and need for additional prostate biopsies.

Adenocarcinoma↗
PubMedDate not supplied

The utility of apical anterior horn biopsies in prostate cancer detection.

We sought to determine the utility of adding apical anterior horn biopsies to systematic prostate sampling regimens in detecting cancer in men with measured prostate volume < or =50 cc. We reviewed the biopsy data of consecutive men referred for an abnormal digital rectal exam or PSA elevation > or =4.0 ng/mL. All of these patients underwent lesion directed biopsy as well as a systematic 12-core biopsy regimen consisting of the standard sextant, bilateral lateral mid- and lateral base-sites, and bilateral apical anterior horn sites. Overall cancer detection and unique cancer detection rates were calculated for each of the 12 sites, stratified by race, age, PSA, and findings on digital rectal exam. In addition, cancer detection rates of various biopsy schemes were calculated and compared. There were 255 men undergoing biopsy who had calculated prostate volume < or =50 cc, and the prostate cancer detection rate was 47%. The overall cancer detection rate of apical anterior horn biopsies ranged between 29% and 56%. The utility of these biopsies was greatest in men with normal rectal exam and PSA <10 ng/mL, with unique cancer detection rates of 6% and 4%, respectively. Including the apical anterior horn biopsies in an 8-biopsy scheme (anterior, apex, lateral mid, lateral base) yielded cancer detection rates greater than 91% in all subgroups that were not statistically different from extended 10- and 12-core biopsy regimens. Apical anterior horn prostate biopsies target cancers that are potentially in the anterior region of the prostate, a region under-sampled using traditional schemes. The use of these biopsies as part of an 8-core biopsy pattern provides high cancer detection in all groups of patients and may represent a new standard.

Aged↗