Endorectal surface coil MR imaging of prostatic carcinoma with the inversion-recovery sequence

The value of inversion-recovery (IR) sequences in the diagnosis and staging of prostatic carcinoma with magnetic resonance (MR) imaging was studied. Twenty-six patients with carcinoma of the prostate were imaged at 1.5 T with an endorectal surface coil and with a variety of IR sequences and a set of spin-echo (SE) sequences for comparison. Ex vivo prostate specimens were imaged again at the same field strength. The two images were correlated with histologic sections. Cancer was identified with MR imaging in 96% of patients. Of the tumors more than 4 mm in diameter, 87% were identified on T2-weighted SE images, whereas only 26% were identified on IR images. However, IR images may be more useful in local staging of carcinoma. Gross capsular infiltration was present in only two patients; however, it was detectable (and excluded in five other patients) by means of IR images. It was not detectable on SE images. The high quality of images obtained with the endorectal coil was confirmed. The authors conclude that addition of the IR sequence to MR imaging with the endorectal coil may improve the usefulness of this examination.     

MR imaging characteristics of noncancerous lesions of the prostate.

Radical prostatectomy specimens from 53 men with clinical stage A or B prostate cancer were retrospectively reviewed and compared with correlative axial T2-weighted magnetic resonance (MR) images obtained just before surgery. Non-cancerous lesions were evaluated for signal intensity and location. Focal high-signal-intensity areas (n = 72) were present in 81% of patients. The 26% of lesions seen in the central gland all correlated with cystic atrophy. Of the 53 lesions seen in the peripheral prostate, 47 (89%) were cystic atrophy without associated cancer, four (7.5%) cystic atrophy with cancer, and two (3.8%) focal inflammation. Focal low-signal-intensity areas (n = 42) were present in 60% of patients. Of the 31% of lesions in the central prostate, one-fifth correlated with benign prostatic hyperplasia (BPH) and four-fifths with fibrous tissue. Of the 69% of peripheral lesions, 83% corresponded to fibrous tissue, 10% to BPH, and 7% to normal tissue. Mixed lesions (n = 42) were present in 64% of patients; 86% of these were located centrally and 14% peripherally. All mixed central lesions were BPH; the peripheral lesions were areas of combined cystic atrophy and fibrosis. BPH of low or mixed signal intensity can extend into the peripheral prostate and mimic cancer. High-intensity cystic atrophy associated with cancer can mimic normal tissue.     

MR imaging of the pelvis with an endorectal-external multicoil array.

Magnetic resonance (MR) images of the pelvis obtained with an endorectal coil have improved resolution relative to that of body coil images; however, they have limited spatial coverage. The sensitivity profile can be improved by using the endorectal coil combined with an external anterior coil as part of a multicoil array. If each coil is connected to a separate receiver, the individual images can be combined to provide an optimal signal-to-noise ratio (S/N). The authors have investigated a 5-inch (12.7-cm) surface coil or a two-coil array as the anterior coil. In both of these configurations, the S/N is improved relative to that of the endorectal coil alone at distances greater than 3 cm from the endorectal coil. The anterior two-coil array provides more lateral coverage. The improved spatial coverage available with this technique expands potential clinical applications of endorectal MR imaging.     

The value of endorectal MR imaging to predict positive biopsies in clinically intermediate-risk prostate cancer patients

The aim of this study was to assess the effectiveness of endorectal MR imaging in predicting the positive biopsy results in patients with clinically intermediate risk for prostate cancer. We performed a prospective endorectal MR imaging study with 81 patients at intermediate risk to detect prostate cancer between January 1997 and December 1998. Intermediate risk was defined as: prostatic specific antigen (PSA) levels between 4 and 10 ng/ml or PSA levels in the range of 10–20 ng/ml but negative digital rectal examination (DRE) or PSA levels progressively higher (0.75 ng/ml year^–1). A transrectal sextant biopsy was performed after the endorectal MR exam, and also of the area of suspicion detected by MR imaging. The accuracies were measured, both singly for MR imaging and combined for PSA level and DRE, by calculating the area index of the receiver operating characteristics (ROC) curve. Cancer was detected in 23 patients (28 %). Overall sensitivity and specificity of endorectal MRI was 70 and 76 %, respectively. Accuracy was 71 % estimated from the area under the ROC curve for the total patient group and 84 % for the group of patients with PSA level between 10–20 ng/ml. Positive biopsy rate (PBR) was 63 % for the group with PSA 10–20 ng/ml and a positive MR imaging, and 15 % with a negative MR exam. The PBR was 43 % for the group with PSA 4–10 ng/ml and a positive MR study, and 13 % with a negative MR imaging examination. We would have avoided 63 % of negative biopsies, while missing 30 % of cancers for the total group of patients. Endorectal MR imaging was not a sufficient predictor of positive biopsies for patients clinically at intermediate risk for prostate cancer. Although we should not avoid performing systematic biopsies in patients with endorectal MR imaging negative results, as it will miss a significant number of cancers, selected patients with a PSA levels between 10–20 ng/ml or clinical-biopsy disagreement might benefit from endorectal MR imaging. Received: 8 February 2000/Revised: 7 July 2000/Accepted: 10 July 2000     

Mucinous carcinomas involving the prostate: atypical findings at MR imaging.

The magnetic resonance (MR) imaging findings in four patients with mucinous tumors involving the prostate are presented. The MR appearance of these tumors differed from that of typical prostatic adenocarcinomas in that the signal intensity on T2-weighted images approximated or exceeded that of the uninvolved peripheral zone. The unusual appearance of mucinous prostate tumors may present problems in diagnosis and staging with MR imaging.     

Magnetic resonance imaging of prostate carcinoma using phased-array coils: therapeutic effect and recurrence

Magnetic resonance imaging with phased-array coils was performed in patients with prostate carcinoma before and after hormonal therapy, radiation therapy or radical prostatectomy to evaluate therapeutic effect and recurrence. After hormonal therapy, the prostate gland, seminal vesicle and primary site of tumor usually decrease in size with variable T2 hypointensity. Recurrent or residual tumors after hormonal therapy usually represent T2 hyperintense lesions compared to the hypointensity of the surrounding tissues. Changes of metastatic sites after therapy were also demonstrated.     

Proton two-dimensional chemical shift imaging for evaluation of prostate cancer: external surface coil vs. endorectal surface coil

PURPOSE: To compare the diagnostic ability of proton magnetic resonance spectroscopy (MRS) using an external surface coil with that using an endorectal surface coil in patients with prostate cancer. MATERIALS AND METHODS: MR imaging (MRI) and two-dimensional chemical shift imaging (2D CSI) were performed in 5 healthy volunteers and in 35 patients with prostate cancer. The receiver coil was the anterior lower part of a phased-array coil or an endorectal surface coil. RESULTS: Receiver-operating characteristic analysis for diagnosing prostate cancer showed no significant difference (P = 0.784) between the area under the curve of phased-array coil CSI and that of endorectal surface coil CSI. CONCLUSION: The phased-array coil CSI could provide comparable detection accuracy to endorectal surface coil CSI. In patients with rectal diseases or patients who could not tolerate the discomfort with insertion of an endorectal surface coil, we recommend the phased-array coil CSI.     

Local staging of prostate carcinoma with endorectal coil MRI: correlation with whole-mount radical prostatectomy specimens

The purpose of this study was to investigate the accuracy of endorectal coil MRI in the local staging of prostate carcinoma. A total of 73 patients with biopsy-proven prostate carcinoma were examined at 0.5 T prior being submitted to radical prostatectomy. The gold standard was provided in all patients by findings at whole-mount sectioning of the surgical specimens. At pathology 28 patients had stage T2, 30 had stage T3a/b, and 15 had stage T3c lesions. Overall accuracy of endorectal coil MRI in defining local tumor stage was 82% (60 of 73 patients). Of 73 patients, 5 (7%) were underestimated and 8 (11%) overestimated. The sensitivity and the specificity of endorectal coil MRI in diagnosing capsular penetration were 95% and 82%, respectively. Seminal vesicle invasion was detected with 80% sensitivity and 93% specificity. Our data indicate that endorectal coil MRI is an accurate method for local staging of prostate cancer.Correspondence to: C. Bartolozzi     

MR-compatible assistance system for punction in a high-field system: device and feasibility of transgluteal biopsies of the prostate gland

We present the first cadavic study results concerning the feasibility of the use of an MR-guided assistance system, Innomotion (Innomedic, Herxheim, Germany), for accurate and consistent placement of percutaneous needles in the prostate gland. The MR-compatible assistance system consists of a C-arch, guiding arm and application module (AMO). T1-weighted fast low angle shot (FLASH) 2-D-GRE sequence (TR/TE=110/4 ms) and T2-weighted turbo spin-echo (TSE)-sequences (TR/TE=3200/97 ms) in transversal orientation were used for the monitoring of the punction of the prostate gland. Planning and control of the intervention is to be made outside the scanner room on a desktop computer that receives DICOM images from the scanner. Servopneumatic drives move the AMO to the insertion point. The physician has to introduce the punction needle manually. The mean deviation of the needle tip to the target in a gel phantom was 0.35 mm. An accurate punction of the prostate gland can easily be performed using this system with a transgluteal access. The T2-weighted images are superior for the evaluation of the prostate anatomy and the needle position during the interventions. In conclusion, our preliminary results indicate that this MR-guided assistance system is suitable for an accurate transgluteal needle placement in the prostate.     

Contrast-enhanced versus systematic transrectal ultrasound-guided prostate cancer detection: an overview of techniques and a systematic review

An overview is given of the current conventional and contrast-specific transrectal ultrasound (TRUS) techniques for prostate imaging that may be used for guiding biopsy. Subsequently, a systematic literature search resulted in inclusion of four studies that directly compared systematic and contrast-enhanced-targeted TRUS-guided biopsy of the prostate. All four studies revealed that contrast-enhanced-targeted TRUS-guided biopsy significantly improved the positive biopsy core rate. In the largest study, the mean Gleason score of the contrast-enhanced-targeted TRUS-guided biopsies was significantly higher than that of the systematic biopsies. Future randomized clinical trials, preferably in a non-academic multi-institutional set-up, will have to be performed to confirm the value of contrast-enhanced-targeted TRUS-guided biopsy in regular clinical practice.     

Granulomatous prostatitis: a pitfall in MR imaging of prostatic carcinoma

Granulomatous prostatitis is an uncommon disease that can prostatic carcinoma on both digital rectal examination and transrectal ultrasound. Four patients who underwent magnetic resonance imaging of the prostate had a histological diagnosis of graanulomatous prostatitis; three of them had recent urinary tract infections. The other patient had an associated midline prostatic cyst and a focus of malignancy. T1-and T2-weighted spin-echo images were obtained in all cases. Peripheral zone lesions of decreased signal intensity, suggestive of carcinoma,were found in all four patients on T2-weighted images. Granulomatous prostatitis should be considered in the differential diagnosis of low signal intensity areas with prostatic magnetic resonance imaging. Correspondence to; P.A. Gevenois     

MR imaging of the prostate at 3 Tesla: comparison of an external phased-array coil to imaging with an endorectal coil at 1.5 Tesla

RATIONALE AND OBJECTIVES: To qualitatively compare the image quality of torso phased-array 3-Tesla (3T) imaging of the prostate with that of endorectal 1.5-Tesla imaging. MATERIALS AND METHODS: Twenty cases of torso phased-array prostate imaging performed at 3-Tesla with FSE T2 weighted images were evaluated by two readers independently for visualization of the posterior border (PB), seminal vesicles (SV), neurovascular bundles (NVB), and image quality rating (IQR). Studies were performed at large fields of view(FOV) (25 cm) (14 cases) (3TL) and smaller FOV (14 cm) (19 cases) (3TS). A comparison was made to 20 consecutive cases of 1.5-T endorectal evaluation performed during the same time period.Results. 3TL produced a significantly better image quality compared with the small FOV for PB (P = .0001), SV (P =.0001), and IQR (P = .0001). There was a marginally significant difference within the NVB category (P = .0535). 3TL produced an image of similar quality to image quality at 1.5 T for PB (P = .3893), SV (P = .8680), NB (P = .2684), and IQR (P = .8599). CONCLUSION: Prostate image quality at 3T with a torso phased-array coil can be comparable with that of endorectal 1.5-T imaging. These findings suggest that additional options are now available for magnetic resonance imaging of the prostate gland.     

Endorectal magnetic resonance imaging of prostatic cancer: comparison between fat-suppressed T2-weighted fast spin echo and three-dimensional dual-echo, steady-state sequences

The aim of this study was to develop an endorectal MRI strategy for prostatic cancer. We evaluated the MR images from 44 consecutive prostatic cancer patients treated by radical prostatectomy. Each sequence from every examination was assessed separately with a specific tumor map drawn. Tumor localization, capsular penetration, and seminal vesicle invasion were marked on maps on the basis of T2 and DESS (dual-echo steady-state) sequences. Thirty patients also had T1-weighted images, and these were assessed with regard to possible tumor outgrowth. The maps were compared with histopathological findings from radical prostatectomy specimens. According to our study, DESS equaled T2 in every respect. No statistically significant differences between the sequences were found with respect to detecting either tumor localization, outgrowth, or seminal vesicle invasion. DESS is a potential new sequence in prostatic MRI as it has been proven to parallel the routinely used T2-weighted imaging. Received: 2 December 1999/Revised: 3 July 2000/Accepted: 4 July 2000     

Correlation between Doppler vascular density and PSA response to radiation therapy in patients with localized prostate carcinoma

RATIONALE AND OBJECTIVES: The authors performed this study to ascertain whether there is a correlation between pretreatment Doppler vascular density (DVD) of the prostate and prostate-specific antigen (PSA) response following radiation therapy in prostate cancer patients. MATERIALS AND METHODS: Prior to radiation therapy, 14 patients with biopsy-proven carcinoma (of Gleason grades 2-7) were imaged with transrectal ultrasound in gray-scale, color Doppler, and power Doppler modes. The Doppler images were analyzed for mean DVD with the aid of a computer program. PSA levels were measured before therapy and every 3 months after therapy. The PSA measurements were fitted to an exponential to determine PSA halving time (T1/2). Correlations were made between T1/2 and the following pretherapy measurements: mean DVD, PSA level, prostate volume, and Gleason grade. RESULTS: Median follow-up time was 392 days. A linear correlation with regression coefficient (R) of 0.75-0.80 was observed between mean DVD and T1/2 for color Doppler and power Doppler imaging. In both imaging modes, each percentage increase in mean DVD led to an increase in T1/2 by 25 days. Pretherapy prostate volume, PSA level, and Gleason score did not correlate with T1/2. CONCLUSION: The pretreatment mean DVD correlates inversely with the rate of posttherapy decline in PSA in patients with prostate cancer. That is, pretreatment vascularity prognosticates postirradiation PSA response. The mechanism underlying this correlative relationship is not known.     

A numerical approach to non-circular birdcage RF coil optimization: verification with a fourth-order coil.

It is demonstrated that birdcage resonators, satisfying conditions of quadrature operation and radiofrequency field homogeneity, can be realized in practice on formers of non-circular cross section described by an equation of the form (x/a)n + (y/b)n = 1 where a and b are constants and n > or = 2 is an integer. Using a ladder network analogous to that of a conventional circular birdcage, optimization algorithms were employed to determine the elemental current distribution on the non-circular cylindrical surfaces. A comparison of circular, elliptical, symmetric and asymmetric fourth-order (n = 4) section birdcage current distributions is presented. A short, asymmetric fourth-order cage was constructed and tested experimentally at 3 T and compared with a conventional circular-section head coil.     

MR anatomy and small lesions of the eye: improved delineation with a special surface coil

To develop an improved investigation protocol for MRI studies of intraocular lesions, imaging with a small surface coil (diameter 6 cm) was compared with a standard surface coil (diameter 11 cm). Both coils were assessed initially on an eye phantom and then by studying 22 patients with uveal melanoma and similar lesions of the eye. The influence of bandwidth and field or view (FOV) were systematically studied and evaluated quantitatively. A smaller bandwidth improved image quality independent of surface coil size. The subsequent secondary increase in chemical shift artefact was acceptable. Smaller FOVs (60–80 mm) necessitated the use of a smaller surface coil. A smaller bandwidth also proved to be advantageous with the use of the smaller surface coil. In conclusion, a smaller-diameter surface coil improves MR imaging of ocular lesions. Pulse sequences with a small bandwidth maintain an acceptable signal-to-noise ratio when the FOV is reduced. Received 27 December 1995; Revision received 29 July 1996; Accepted 3 September 1996     

Granulomatous prostatitis: A hypoechoic lesion of the prostate

Numerous benign and malignant entities can disrupt the normal prostatic parenchymal architecture producing hypoechoic lesions in the peripheral zone. We report two cases of granulomatous prostatitis mimicking carcinoma. The differential diagnosis of hypoechoic lesions and the etiologies of granulomatous prostatitis are discussed. All hypoechoic lesions in the peripheral zones of the prostate require biopsy for histologic diagnosis.     

Anatomical and metabolic assessment of prostate using a 3-Tesla MR scanner with a custom-made external transceive coil: healthy volunteer study

PURPOSE: To examine the possibility of using a 3 Tesla (T) magnetic resonance (MR) scanner with a custom-made external coil to obtain ductal details of the prostate, high-quality spectra, and metabolite mapping corresponding to prostate zonal anatomy in healthy volunteers. MATERIALS AND METHODS: MRI and two-dimensional (2D) chemical shift imaging (CSI) were performed in 16 healthy volunteers using a 3T scanner with a custom-made external transmit-receive (transceive) coil. Visualization of the prostatic duct-like structure was analyzed on T2-weighted (T2W) images. The resolution of the metabolite peaks and the distribution of metabolites in CSI were also assessed. RESULTS: In the axial plane, 3-mm-thick images were better than 4-mm-thick images with the same voxel volume for assessing duct-like structures and prostatic urethra. Differentiation between inner and outer citrate (Cit) peaks was frequently observed (29 out of 30). The mean peak area ratio of choline (Cho) plus creatine (Cr) over Cit in the peripheral zone (PZ) was significantly lower than in the transition zone (TZ) (P = 0.014). CONCLUSION: 3T MR examinations of the prostate using an external coil allow information to be collected about the details of duct-like structures, the high-quality spectra of Cit, and the zone-specific distribution of metabolites.     

Correlation of microvascular permeability derived from dynamic contrast-enhanced MR imaging with histologic grade and tumor labeling index: a study in human brain tumors

RATIONALE AND OBJECTIVES: Dynamic contrast material-enhanced magnetic resonance (MR) imaging may be used to quantify fractional blood volume (fBV) and microvascular permeability in human brain tumors. Hypothesis is that these measurements correlate with tumor histologic grade and immunohistologically assessed mitotic activity. MATERIALS AND METHODS: Thirty-eight patients with newly diagnosed gliomas underwent MR imaging consisting of dynamic three-dimensional spoiled gradient-recalled acquisition in the steady state image sets following bolus injections of a single dose of gadodiamide. Signal intensity changes in blood and tissue were kinetically analyzed, yielding estimates of fBV and microvascular permeability (k). Tumor specimens were graded with the World Health Organization-II four-point grading score. MIB-1 immunohistochemical labeling (anti-Ki-67 monoclonal antibody) was performed in 22 patients to evaluate mitotic activity. RESULTS: Histologic study revealed nine grade 2, 14 grade 3, and 15 grade 4 tumors. fBV ranged from 0.4% to 24%, k from -0.4 to 31.4 mL/100 cm3 x min, and MIB-1 labeling indexes from 1.7% to 42.8%. Correlation to the tumor grade was highest for permeability (r = 0.73), followed by the MIB-1 index (r = 0.63), and fBV (r = 0.48). Correlation between k and MIB-1 index was strong (r = 0.84). There was no statistically significant difference between the fBV of any of the groups. Despite some overlap between the permeability values of specific tumors from different grades, differences were statistically significant. The MIB-1 index was significantly different between grades 3 and 4 but not between grades 2 and 3. CONCLUSION: Dynamic contrast-enhanced MR imaging allows noninvasive determination of tumor fBV and microvascular permeability k. k is more reliable than the MIB-1 labeling index for differentiating grade 2 from grade 3 tumors.     

MR扩散加权成像在评价前列腺癌内分泌治疗中的应用价值

目的探讨内分泌治疗前后前列腺外周带癌区和非癌区的表观扩散系数（ADC）值的变化情况。方法对经手术病理或穿刺活检证实的14例前列腺癌和18例内分泌治疗6个月以上的前列腺癌患者行MR扩散加权成像（DWI）。依病理结果，将前列腺6分区归类为癌区和非癌区，测量每个分区的ADC值，同时测量每例膀胱、闭孔内肌的ADC值，对2组的结果进行比较。结果未治疗组14例癌区和非癌区的ADC值分别为（1．22±0．25）×10^-3、（1．59±0．19）×10^-3mm^2／s，差异有统计学意义（t=7．03，P〈0．01）。经内分泌治疗后的18例癌区的ADC值升高至（1．46±0．30）×10^-3mm^2／s，非癌区的ADC值为（1．59±0．24）×10^-3mm^2／s，癌区和非癌区之间ADC值差异有统计学意义（t=2．46，P〈0．05）。两组癌区之间ADC值差异有统计学意义（t=4．66，P〈0．01），非癌区、膀胱、闭孔内肌的ADC值差异无统计学意义（t值分别为0．06、0．48、1．64，P值均〉0．05）。结论ADC值用于判断前列腺癌内分泌治疗效果有应用前景。