T1 hyperintensity of bladder urine at prostate MRI: frequency and comparison with urinalysis findings

Objective

The purpose of this study was to assess the possible clinical significance of bladder urine T1 hyperintensity based upon comparison with urinalysis findings, using a cohort of patients who underwent prostate MRI and urinalysis at a similar point in time during preoperative work-up.

Methods

We identified 56 patients who underwent prostatectomy at our institution who obtained prostate MRI and urinalysis within 1 day of each other preoperatively. A control group of 160 consecutive adult men who underwent pelvic MRI during the same time period for other indications was also identified. Two radiologists independently and in consensus reviewed the T1-weighted images to assess the frequency of bladder urine T1 hyperintensity in both groups. The urinalyses in the 56 men undergoing prostatectomy were reviewed, with the results compared between patients with and without bladder urine T1 hyperintensity.

Results

Four (7.1%) of 56 men with prostate cancer exhibited T1 hyperintense bladder urine, compared with six (3.8%) of 160 patients exhibiting this finding in the control group (P=.288). Of the four prostate cancer patients with this finding, all exhibited a normal urinalysis. An abnormal urinalysis was identified for four of the prostate cancer patients, all of whom exhibited normal urine T1 signal intensity.

Conclusion

Bladder urine T1 hyperintensity may be seen occasionally in patients with prostate cancer but is not associated with abnormal urinalysis and therefore should not be regarded as a sign of acute urinary pathology.     

The value and limitations of contrast-enhanced transrectal ultrasonography for the detection of prostate cancer

Objectives

To evaluate the role of contrast-enhanced transrectal ultrasonography (CE-TRUS) for detecting prostate carcinoma.

Methods

Sixty-five patients with elevated serum prostate-specific antigen (PSA) and/or abnormal digital rectal examination (DRE) were assessed using transrectal ultrasound (TRUS) and CE-TRUS. In all the patients, CE-TRUS was performed with intravenous injection of contrast agent (SonoVue, 2.4 ml) before biopsy. The cancer detection rates of the two techniques were compared. False-positive and false-negative findings related to CE-TRUS were analyzed in comparison to the pathological results of biopsy or radical prostatectomy. The targeted biopsy to abnormal CE-TRUS areas was also compared to systematic biopsy.

Results

Prostate cancer was detected in 29 of the 65 patients. CE-TRUS showed rapid focal enhancement or asymmetric vessels of peripheral zones in 28 patients; 23 of them had prostate cancer. CE-TRUS had 79.3% sensitivity, compared to 65.5% of TRUS (P < 0.05). There were five false-positive and six false-negative findings from CE-TRUS. Benign prostate hyperplasia, and acute and chronic prostatitis were important causes related to the false-positive results of CE-TRUS. Prostate cancer originating from the transition zone or peripheral zone with lower PSA levels, small-size foci, and moderately or well-differentiated tumor was missed by CE-TRUS. The cancer detection rate of targeted biopsy (75%, 33/44 cores) was significantly higher than one of systematic biopsy (48.2%, 162/336) in those 28 cases (P < 0.05). In addition, no significant correlation was found between the cancer detection rate with CE-TRUS and serum PSA levels.

Conclusion

CE-TRUS may improve the detection rate of prostate cancer through targeted biopsy of contrast-enhanced abnormalities. Our findings indicate that systematic biopsies should not be eliminated on the basis of false-positive and false-negative findings related to CE-TRUS.     

Prostate Volume Measurement by TRUS Using Heights Obtained by Transaxial and Midsagittal Scanning: Comparison with Specimen Volume Following Radical Prostatectomy

Objective

The purpose of this study was to determine, when measuring prostate volume by TRUS, whether height is more accurately determined by transaxial or midsagittal scanning.

Materials and Methods

Sixteen patients who between March 1995 and March 1998 underwent both preoperative TRUS and radical prostatectomy for prostate cancer were included in this study. Using prolate ellipse volume calculation (height × length × width × π/6), TRUS prostate volume was determined, and was compared with the measured volume of the specimen .

Results

Prostate volume measured by TRUS, regardless of whether height was determined transaxially or midsagittally, correlated closely with real specimen volume. When height was measured in one of these planes, a paired t test revealed no significant difference between TRUS prostate volume and real specimen volume (p = .411 and p = .740, respectively), nor were there significant differences between the findings of transaxial and midsagittal scanning (p = .570). A paired sample test, however, indicated that TRUS prostate volumes determined transaxially showed a higher correlation coefficient (0.833) and a lower standard deviation (9.04) than those determined midsagittally (0.714 and 11.48, respectively).

Conclusion

Prostate volume measured by TRUS closely correlates with real prostate volume. Furthermore, we suggest that when measuring prostate volume in this way, height is more accurately determined by transaxial than by midsagittal scanning.     

Negative predictive value of multiparametric MRI for prostate cancer detection: Outcome of 5-year follow-up in men with negative findings on initial MRI studies

Objective

To assess the clinical negative predictive value (NPV) of multiparametric MRI (mp-MRI) for prostate cancer in a 5-year follow-up.

Materials and methods

One hundred ninety-three men suspected of harboring prostate cancer with negative MRI findings were included. Patients with positive transrectal ultrasound (TRUS)-guided biopsy findings were defined as false-negative. Patients with negative initial TRUS-guided biopsy findings were followed up and only patients with negative findings by digital rectal examination, MRI, and repeat biopsy and no increase in PSA at 5-year follow-up were defined as “clinically negative”. The clinical NPV of mp-MRI was calculated. For quantitative analysis, mean signal intensity on T2-weighted images and the mean apparent diffusion coefficient value on ADC maps of the initial MRI studies were compared between peripheral-zone (PZ) cancer and the normal PZ based on pathologic maps of patients who had undergone radical prostatectomy.

Results

The clinical NPV of mp-MRI was 89.6% for significant prostate cancer. Small cancers, prostatitis, and benign prostatic hypertrophy masking prostate cancer returned false-negative results. Quantitative analysis showed that there was no significant difference between PZ cancer and the normal PZ.

Conclusion

The mp-MRI revealed a high clinical NPV and is a useful tool to rule out clinically significant prostate cancer before biopsy.     

Rectal villous tumours: MR features and correlation with TRUS in the preoperative evaluation

Aim

The aim of this study was to assess the clinical relevance of MR and transrectal ultrasonography (TRUS) imaging of rectal villous tumours to elucidate the correlation between imaging results and specific histopathological tumour features, such as tumour size (T) and lymph node involvement (N), in order to establish the better technique for the pre-surgical patient evaluation.

Patients and methods

23 cases of villous tumours of the rectum were studied with phased-array MR and TRUS. All patients underwent either surgical or endoscopic treatment. Final diagnosis was based on histopathological results. In particular, the following features were characterized by the imaging techniques mentioned above: lesion site, distance between lesion and ano-rectal junction, size, morphology and contrast enhancement of lesions, fluid layer around the lesion, alterations of the deep layers of the rectal wall, sphincter infiltration, presence or absence of mesorectal, iliac and obturatory lymphnode involvement.

Results

Histology established muscular involvement in 7 cases (T2), perirectal fat infiltration in 1 case (T3); in the remaining 15 cases, staging was Tis-T1. In 17/23 cases (73.9%) the lesions were correctly staged with both imaging techniques, whereas in 5/23 cases (21.7%) the lesions were overstaged. No cases were understaged. TRUS concorded with histological exams in 17/23 cases (73.9%). 5/23 cases (21.7%) were overstaged and 1/23 (4%) was understaged. MR and TRUS were in accordance in 20/23 cases (86.9%).

Discussion

Considering the frequent degeneration of villous tumours, correct preoperative identification and precise evaluation of these lesions, such as the detection of rectal wall invasion, is essential in deciding optimal treatment strategy. MRI and TRUS allow the identification of specific features of villous tumours and of malignant degeneration, allowing for a correct local disease staging.     

Multiparametric MRI of the prostate with three functional techniques in patients with PSA elevation before initial TRUS-guided biopsy

Objective:

Multiparametric MRI (mp-MRI) of the prostate is increasingly being used for local staging and detection of recurrence of prostate cancer (PCA). In patients with elevated prostate-specific antigen (PSA), mp-MRI could provide information on the position of the cancer, allowing adjustments to be made to the needle depth and direction before repeat transrectal ultrasound (TRUS)-guided biopsy to ensure accurate sampling of lesions. The purpose of the prospective study was to evaluate mp-MRI of the prostate in patients with PSA elevation before initial TRUS-guided biopsy.

Methods:

mp-MRI was performed in 94 patients using a 1.5-T scanner (MAGNETOM Aera^®; Siemens Healthcare, Erlangen, Germany) and 16-channel phased-array body coil (Siemens Healthcare). T₂ weighted images (T2WI), diffusion-weighted imaging (DWI), dynamic contrast-enhanced (DCE) MRI and MR spectroscopy were obtained. TRUS-guided random biopsies and additional targeted biopsies of suspicious MRI areas were performed.

Results:

Additional targeted biopsies were obtained in 17 of 43 (40%) patients with PCA. 11 of 17 targeted biopsies contained PCA. 5 of 11 PCAs were diagnosed only by additional targeted biopsies. Sensitivity of mp-MRI in patients was 97.7% and specificity was 11.8%. mp-MRI was false negative in one patient. Sensitivity of mp-MRI in 207 lesions was 80.9% and specificity was 44.7%. In a logistic regression model, the apparent diffusion coefficient value was the only significant parameter to differentiate malignant and benign lesions.

Conclusion:

mp-MRI should be performed in patients with PSA elevation before initial TRUS-guided biopsy to allow additional targeted biopsies from suspicious areas of MRI. We recommend mp-MRI with T2WI, DWI, DCE MRI and MR spectroscopy. DWI as the most reliable technique should be used in every mp-MRI.

Advances in knowledge:

DWI is the most reliable technique in mp-MRI of the prostate.     

Solid non-invasive ovarian masses on MR: Histopathology and a diagnostic approach

Purpose

The purpose is to clarify the histopathology of the solid, non-invasive ovarian masses and to investigate the MR characteristics that distinguish benign from malignant.

Materials and methods

From 1996 to 2008, we identified 38 cases with predominantly solid non-invasive ovarian masses examined by contrast MR. We evaluated the signal intensity on T2WI and degree of contrast enhancement. In 31 of these cases with dynamic contrast study, we classified the enhancing patterns of the masses into gradually increasing and plateau after rapid increase patterns.

Result

Sixteen cases were benign sex-cord stromal tumors, three were other types of benign tumors, nine cases were diagnosed with primary malignant ovarian tumors, and 10 showed metastatic tumors. Low intensity on T2WI was observed in 15 benign and 2 malignant tumors. The gradually increasing pattern was observed in all 17 benignancies and 5 of the 14 malignancies. In the equilibrium phase, the masses were weakly enhanced in all 19 benignancies and only 4 of 19 malignancies. The diagnostic criteria, that low signal intensity masses with gradual weak enhancement are benign showed 93.3% accuracy and 100% positive predictive value.

Conclusion

Benign solid ovarian masses tended to show low signal intensity on T2WI and gradual weak enhancement.     

Osteoid osteoma in atypical locations: the added value of dynamic gadolinium-enhanced MR imaging

Purpose

To compare the results of dynamic gadolinium-enhanced magnetic resonance imaging (MRI), unenhanced MRI and computed tomography (CT), in terms of nidus conspicuity and diagnostic confidence of osteoid osteoma in atypical sites.

Materials and methods

CT and MR (nonenhanced T1- and T2-weighted and dynamic MRI) images of 19 patients with histologically proven osteoid osteoma located in atypical sites were retrospectively reviewed. Time-enhancement curves of the nidus and the adjacent bone marrow were generated. Images from each technique were scored for nidus conspicuity by two independent radiologists. Another blinded radiologist was asked to assess final diagnosis of the bone lesion on MR and CT images, independently.

Results

In all cases, nidus contrast uptake started in the arterial phase and was higher compared to the surrounding bone marrow. Dynamic MRI significantly increased nidus conspicuity compared to nonenhanced MRI (P < .0001) and CT (P = .04). In 6/19 (31.6%) cases nidus conspicuity was higher at dynamic MRI compared to CT. Confident diagnosis of osteoid osteoma was achieved in all patients with MRI and in 10/19 (52.6%) patients with CT.

Conclusion

In patients with osteoid osteoma located in atypical sites, dynamic MRI increases nidus conspicuity, allowing confident diagnosis.     

A qualitative approach to combined magnetic resonance imaging and spectroscopy in the diagnosis of prostate cancer

Purpose

To investigate the feasibility and diagnostic value of a whole prostate qualitative approach to combined magnetic resonance imaging and spectroscopy (MRI + MRS) in the detection of prostate cancer in patients with elevated PSA.

Materials and methods

Three hundred and fifty six subjects (mean serum PSA 11.47 ng/ml, range 0.40-133 ng/ml) were examined with fast-T2-weighted images (MRI) and 3D-magnetic resonance spectroscopy (MRS). Both modalities were qualitatively analyzed on a whole prostate basis by a single radiologist using a 4-point diagnostic scale. Prostate cancer was histopathologically proven in 220 patients and non-evidence of cancer was determined after at least 12 months clinical follow-up in 136 subjects.

Results

Receiver operating curve analysis revealed a significantly better diagnostic performance of MRI + MRS (A_z = 0.857) than MRI alone (A_z = 0.801) and MRS alone (A_z = 0.810). The sensitivity, specificity and accuracy of MRI + MRS for detection of prostate cancer were 72.3%, 92.6%, and 80.1%, respectively.

Conclusions

Spectral evaluation with a whole prostate qualitative approach is feasible in routine clinical practice. The combination of MRI and MRS yields superior diagnostic results than either modality alone.     

Detection of prostate cancer with three-dimensional transrectal ultrasound: correlation with biopsy results

Objectives

The aim of this study was to evaluate the role of three-dimensional transrectal ultrasound in the diagnosis of prostate cancer.

Methods

A total of 112 patients with elevated serum prostate-specific antigen (PSA) or a positive digital rectal examination were evaluated using three-dimensional greyscale transrectal ultrasound (3D-GS TRUS) and three-dimensional power Doppler sonography (3D-PDS). Target biopsies were obtained together with 12 core systematic biopsies. Pathological results were correlated with the imaging data.

Results

Cancers were detected in 269 biopsy sites from 41 patients. 229 sites of cancer were depicted by 3D-GS TRUS and 213 sites were depicted by 3D-PDS. 30 sites were missed by both 3D-GS TRUS and 3D-PDS. Abnormal prostate images depicted by 3D-GS TRUS and 3D-PDS were associated with lesions with a Gleason score of 6.9 or higher.

Conclusion

The detection rates of prostate cancer were significantly improved with 3D-GS TRUS and 3D-PDS on serum PSA levels >10 ng ml^–1 or 20 ng ml^–1. 3D-GS TRUS and 3D-PDS may improve the biopsy yield by determining appropriate sites for target and systematic biopsies. The abnormalities detected by 3D ultrasound were associated with moderate- and high-grade prostate cancers. However, based on the number of false-negative TRUS results, the use of systematic prostate biopsies should not be eliminated.Prostate cancer is a common malignancy in older males. Previous autopsy studies have shown that one-third of males over 50 years old have latent cancer, yet only 10% develop clinically significant carcinomas during their lifetime [1]. The exact mechanism mediating the progression of microfocal cancers into symptomatic forms of the disease has not been elucidated. Since prostate cancers demonstrate remarkably heterogeneous behaviours ranging from slow-growing lesions to aggressive tumours that metastasise rapidly [2], the diagnosis and treatment of prostate cancers is very challenging. The current methods of screening for prostate cancer include measuring serum prostate-specific antigen (PSA) levels, digital rectal examination and transrectal ultrasound (TRUS) scanning and biopsy. However, controversy surrounds which screening method is the most clinically significant for detecting lesions.Since approximately 20–50% of prostate cancers are invisible by greyscale (GS) TRUS [3], GS TRUS has limited value for detection of prostate cancer [4,5]. In addition, 35% of lesions missed by GS TRUS are moderate- or high-grade tumours [6]. Colour Doppler ultrasound, as an important adjunct to GS TRUS, could improve detection of prostate cancer, although in one study 16% of cases with clinically significant cancer were still missed by this method [7].Three-dimensional (3D) TRUS is a relatively new imaging modality. Preliminary studies have shown improved cancer detection with 3D TRUS when compared with two-dimensional TRUS [8,9]. However, it is still unknown which malignant lesions may be detected by 3D TRUS. Furthermore, 3D TRUS has not been analysed in correlation with the site-specific biopsy pathological results.The purpose of this study was to assess the role of 3D-GS TRUS and 3D power Doppler sonography (3D-PDS) in the diagnosis of prostate carcinoma. This study correlated 3D-GS TRUS and 3D-PDS data with biopsy pathological results using a site-by-site analysis that included target and systematic biopsies.     

Evaluation of magnetic resonance imaging criteria for Meckel's cave lesion: logistic regression analysis and correlation with surgical findings

Objective

Our aim was to investigate the statistical preoperative diagnostic criteria of lesions of Meckel's cave (MC) on MRI.

Materials and methods

We retrospectively reviewed the MR images with MC lesions in 34 patients. The MR signs were compared with histopathologic and surgical findings in all lesions. Odds ratio values and the confidence intervals of the MRI diagnostic criteria were evaluated by univariate logistic regression.

Results

The following three signs of MC on post-contrast T1WI of MRI have been found to represent the most valuable criterion for determination of MC lesion: (1) contrast enhancement, (2) bulging of lateral wall, and (3) the absence of normal MC, with odds ratios of 362.67 (P<.001), 40.38 (P=.001), and 40.38 (P=.001) individually.

Conclusion

Contrast enhancement on post-contrast T1WI is the most sensitive MR sign for demonstrating the presence of MC lesion.     

The role of diffusion – Weighted MRI in evaluation of prostate cancer

The aim of work

To illustrate the role of T2WI combined with diffusion WI (DWI) in the evaluation of patients with prostate cancer.

Patients and methods

This prospective study included 36 patients (mean age 61) with clinical suspicion of prostate cancer using surface coil at 1.5 T MR Unit. Axial, coronal, and sagittal high resolution (HR) T2WI were performed, DWI was applied using a single-shot echo-planar imaging sequence in axial orientation. Regions of interest were drawn on ADC maps on the site of visible restricted diffusion as well as the normal tissue, then the ADC value was calculated. Considering histopathological diagnosis the standard of reference, the results of T2WI alone were compared with those of combined T2WI and DWI.

Results

In this prospective study, 36 men were examined and T2WI, DWI, ADC map and ADC values were measured. T2 low SI was detected in the peripheral zone of the prostate of 36 patients, and restricted diffusion in 31 patients.

Conclusion

Our study indicates that the addition of the ADC map and DWI to T2WI provide significantly more accurate results for prostate cancer detection and staging.     

Diagnostic utility of DTI in prostate cancer

Purpose

The aim of this study was to compare the diffusion tensor parameters of prostate cancer, prostatitis and normal prostate tissue.

Materials and Methods

A total of 25 patients with the suspicion of prostate cancer were included in the study. MRI was performed with 3 T system (Intera Achieva, Philips Medical Systems, The Netherlands). T2 TSE and DTI with ss-EPI were obtained in each subject. TRUS-guided prostate biopsy was performed after the MRI examination. Images were analyzed by two radiologists using a special software system. ROI's were drawn according to biopsy zones which are apex, midgland, base and central zone on each sides of the gland. FA and ADC values in areas of cancer, chronic prostatitis and normal prostate tissue were compared using Student's t-test.

Results

Histopathological analysis revealed carcinoma in 68, chronic prostatitis in 67 and was reported as normal in 65 zones. The mean FA of cancerous tissue was significantly higher (p < 0.01) than the FA of chronic prostatitis and normal gland. The mean ADC of cancerous tissue was found to be significantly lower (p < 0.01), compared with non-cancerous tissue.

Conclusion

Decreased ADC and increased FA are compatible with the hypercellular nature of prostate tumors. These differences may increase the accuracy of MRI in the detection of carcinoma and to differentiate between cancer and prostatitis.     

Retroperitoneal ganglioneuroma in children: CT and MRI features with histologic correlation

Objective

To demonstrate the CT and MRI features with histologic correlation of retroperitoneal ganglioneuromas in children.

Methods

The diagnostic images (seventeen CT scans and five MR scans) in 17 children with retroperitoneal ganglioneuroma confirmed by operation and histopathology were retrospectively reviewed, and correlated to the histologic findings.

Results

All tumors presented as an oval-shaped, well-defined mass on both CT and MR images. On unenhanced CT images, calcification was detected in six masses (35.3%), and predominantly low attenuation with the CT value ranged from 22 to 38 HU (mean 29.5 HU) in all the tumors. The tumors with CT value less than 30 HU had a relatively larger amount of myxoid stroma on histopathologic sections than those with CT value more than 30 HU. Tumors showed homogeneous low signal intensity on T1-weighted images and inhomogeneous high signal intensity with interlaced or nodular low signal intensity on T2-weighted images. The post-contrast enhancement on both CT and MR images was lacking or slight in early phase, but moderate or marked in late phase. The inhomogeneous high signal intensity on T2WI, as well as the delayed enhancement corresponded to a large amount of myxoid stroma and a relatively small number of cellular components in tumors.

Conclusion

An oval shape, well-defined margin, low attenuation on CT, inhomogeneous hyperintensity on T2WI, and delayed moderate or marked enhancement are typical features of retroperitoneal ganglioneuroma in children. The imaging features correlated well to the histologic findings.     

High-resolution diffusion tensor imaging of prostate cancer using a reduced FOV technique

Objective

Diffusion tensor imaging (DTI) offers the promise of improved tumor localization in prostate cancer but the technique suffers from susceptibility-induced artifacts that limit the achievable resolution. The present work employs a reduced field-of-view technique that enables high-resolution DTI of the prostate at 3 T. Feasibility of the approach is demonstrated in a clinical study including 26 patients and 14 controls.

Materials and methods

Reduced field-of-view acquisition was established by non-coplanar application of the excitation and the refocusing pulse in conjunction with outer volume suppression. Accuracy for cancer detection of apparent diffusion coefficient (ADC) mapping and T₂-weighted imaging was calculated and compared with reference to the findings of trans-rectal ultrasound-guided octant biopsy. Mean ADCs and fractional anisotropy (FA) values in the patients with positive and negative biopsies were compared to each other and to the controls.

Results

Fine anatomical details were successfully depicted on the ADC maps with sub-millimeter resolution. Accuracy for prostate cancer detection was 73.5% for ADC maps and 71% for T₂-weighted images, respectively. Cohen's kappa (κ = 0.48) indicated moderate agreement of the two methods. The mean ADCs were significantly lower, the FA values higher, in the patients with positive biopsy than in the patients with negative biopsy and the controls. Monte Carlo simulations showed that the FA values, but not the ADCs, were slightly overestimated. Bootstrap analysis revealed that the ADC, but not the FA value, is a highly repeatable marker.

Conclusion

In conclusion, the present work introduces a new approach for high-resolution DTI of the prostate enabling a more accurate detection of focal tumors especially useful in screening populations or as a potential navigator for image-guided biopsy.     

Diffusion-weighted MRI, 11C-choline PET and 18F-fluorodeoxyglucose PET for predicting the Gleason score in prostate carcinoma

Objectives

To evaluate the accuracy of transrectal ultrasound-guided (TRUS) biopsy, diffusion-weighted (DW) magnetic resonance imaging (MRI), ¹¹C-choline (CHOL) positron emission tomography (PET), and ¹⁸F-fluorodeoxyglucose (FDG) PET in predicting the prostatectomy Gleason risk (GR).

Methods

The study included 21 patients who underwent TRUS biopsy and multi-technique imaging before radical prostatectomy. Values from five different tests (TRUS biopsy, DW MRI, CHOL PET, FDG PET, and combined DW MRI/CHOL PET) were correlated with the prostatectomy GR using Spearman’s ρ. Tests that were found to have significant correlations were used to classify patients into GR groups.

Results

The following tests had significant correlations with prostatectomy GR: TRUS biopsy (ρ?=?0.617, P?=?0.003), DW MRI (ρ?=?–0.601, P?=?0.004), and combined DW MRI/CHOL PET (ρ?=?–0.623, P?=?0.003). CHOL PET alone and FDG PET only had weak correlations. The correct GR classification rates were 67 % with TRUS biopsy, 67 % with DW MRI, and 76 % with combined DW MRI/CHOL PET.

Conclusions

DW MRI and combined DW MRI/CHOL PET have significant correlations and high rates of correct classification of the prostatectomy GR, the strength and accuracy of which are comparable with TRUS biopsy.

Key Points

? Accurate determination of the Gleason score is essential for prostate cancer management. ? DW MRI ± CHOL PET correlated significantly with prostatectomy Gleason score. ? These correlations are similar to that between TRUS biopsy and prostatectomy.     

Evaluation of the ESUR PI-RADS scoring system for multiparametric MRI of the prostate with targeted MR/TRUS fusion-guided biopsy at 3.0 Tesla

Objectives

To evaluate the Prostate Imaging Reporting and Data System (PI-RADS) proposed by the European Society of Urogenital Radiology (ESUR) for detection of prostate cancer (PCa) by multiparametric magnetic resonance imaging (mpMRI) in a consecutive cohort of patients with magnetic resonance/transrectal ultrasound (MR/TRUS) fusion-guided biopsy.

Methods

Suspicious lesions on mpMRI at 3.0 T were scored according to the PI-RADS system before MR/TRUS fusion-guided biopsy and correlated to histopathology results. Statistical correlation was obtained by a Mann–Whitney U test. Receiver operating characteristics (ROC) and optimal thresholds were calculated.

Results

In 64 patients, 128/445 positive biopsy cores were obtained out of 95 suspicious regions of interest (ROIs). PCa was present in 27/64 (42 %) of the patients. ROC results for the aggregated PI-RADS scores exhibited higher areas under the curve compared to those of the Likert score. Sensitivity/specificity for the following thresholds were calculated: 73 %/92 % and 85 %/67 % for PI-RADS scores of 9 and 10, respectively; 85 %/56 % and 60 %/97 % for Likert scores of 3 and 4, respectively.

Conclusions

The standardised ESUR PI-RADS system is beneficial to indicate the likelihood of PCa of suspicious lesions on mpMRI. It is also valuable to identify locations to be targeted with biopsy. The aggregated PI-RADS score achieved better results compared to the single five-point Likert score.

Key points

? The ESUR PI-RADS scoring system was evaluated using multiparametric 3.0-T MRI. ? To investigate suspicious findings, transperineal MR/TRUS fusion-guided biopsy was used. ? PI-RADS can guide biopsy locations and improve detection of clinically significant cancer. ? Biopsy procedures can be optimised, reducing unnecessary negative biopsies for patients. ? The PI-RADS scoring system may contribute to more effective prostate MRI.     

MRI-guided breast biopsy at 3T using a dedicated large core biopsy set: Feasibility and initial results

Objective

The increasing importance of breast MRI in the diagnostic processes concerning breast cancer yield often lesions that are visible on MRI only. To assess the nature of these lesions, pathologic analysis is necessary. Therefore, MR-guided biopsy should be available. Breast MRI at 3T has shown advantage over 1.5T. Unfortunately, current equipment for MR-guided biopsy is better suited for intervention at 1.5T due to the danger of heating titanium co-axial sleeves and large susceptibility artifacts. We evaluated a dedicated 3T breast biopsy set that uses plastic coaxial needles to overcome these problems.

Materials and methods

We performed MRI-guided breast biopsy in 23 women with 24 MRI-only visible breast lesions at 3T. Biopsy procedures were performed with plastic coaxial needles in a closed bore 3T clinical MR system on a dedicated phased array breast coil with a commercially available add-on stereotactic biopsy device.

Results

Width of the needle artifact was 2 mm in all 24 cases. Biopsy procedure was completed between 35 and 67 min. The procedure was judged moderately easy in 12 and normal in 10 cases. One procedure was judged difficult and there was one technical failure.

Conclusion

MRI-guided breast biopsy at 3T is a fast and accurate procedure. The plastic coaxial needles reduce the susceptibility artifact largely and do not increase the difficulty of the procedure. The diagnostic yield is at least equal to the diagnostic yield of the same procedure at 1.5T. Therefore, this technique can be safely used for lesions only visible at 3T MRI.     

Imaging and pathology findings after an initial negative MRI-US fusion-guided and 12-core extended sextant prostate biopsy session

PURPOSE

A magnetic resonance imaging-ultrasonography (MRI-US) fusion-guided prostate biopsy increases detection rates compared to an extended sextant biopsy. The imaging characteristics and pathology outcomes of subsequent biopsies in patients with initially negative MRI-US fusion biopsies are described in this study.

MATERIALS AND METHODS

We reviewed 855 biopsy sessions of 751 patients (June 2007 to March 2013). The fusion biopsy consisted of two cores per lesion identified on multiparametric MRI (mpMRI) and a 12-core extended sextant transrectal US (TRUS) biopsy. Inclusion criteria were at least two fusion biopsy sessions, with a negative first biopsy and mpMRI before each.

RESULTS

The detection rate on the initial fusion biopsy was 55.3%; 336 patients had negative findings. Forty-one patients had follow-up fusion biopsies, but only 34 of these were preceded by a repeat mpMRI. The median interval between biopsies was 15 months. Fourteen patients (41%) were positive for cancer on the repeat MRI-US fusion biopsy. Age, prostate-specific antigen (PSA), prostate volume, PSA density, digital rectal exam findings, lesion diameter, and changes on imaging were comparable between patients with negative and positive rebiopsies. Of the patients with positive rebiopsies, 79% had a positive TRUS biopsy before referral (P = 0.004). Ten patients had Gleason 3+3 disease, three had 3+4 disease, and one had 4+4 disease.

CONCLUSION

In patients with a negative MRI-US fusion prostate biopsy and indications for repeat biopsy, the detection rate of the follow-up sessions was lower than the initial detection rate. Of the prostate cancers subsequently found, 93% were low grade (≤3+4). In this low risk group of patients, increasing the follow-up time interval should be considered in the appropriate clinical setting.Prostate cancer is the most common cancer in males, with an estimated 238 590 new diagnoses annually in the USA, and it is the second leading cause of cancer-related mortality in males (1). One in six males will develop prostate cancer in his lifetime (1). The current standard of care for diagnosing and grading prostate cancer is a 12-core extended sextant biopsy obtained with transrectal ultrasonography (TRUS) guidance (2, 3). As magnetic resonance imaging (MRI) has superior contrast resolution than ultrasonography (US), it is possible for multiparametric MRI (mpMRI) to detect prostate cancer with high reliability (4). Since clinically insignificant cancer is often invisible to magnetic resonance (MR), prostate MRI preferentially detects more aggressive cancers (5–9). MRI can be used to guide the prostate biopsy, either using a direct “in-gantry” approach or by using MRI-US fusion, which was developed as an office-based alternative (10). MRI-US targeted biopsies have about twice the per-core detection rate of sextant biopsies (11), and have been shown to be particularly useful for prostates measuring greater than 40 mL, which typically have lower rates of cancer detection than smaller prostate glands (12).Since TRUS-guided biopsies have a relatively low sensitivity, many patients with a rising prostate-specific antigen (PSA), but an initial negative biopsy, undergo additional biopsies with progressively lower yields. In a study of sequential systematic biopsies in 1051 males, the detection rate of successive biopsies was 22%, 10%, 5%, and 4%, respectively (13). The third and fourth TRUS-guided biopsy sessions detected lower grade cancers and were found to have higher morbidity than the first two biopsies. Recently, MRI-US fusion biopsy has been reported to increase cancer detection rates in the setting of a prior negative TRUS biopsy (14, 15).While MRI-US fusion biopsy is promising in the setting of previous negative random sampling, the response to a negative MRI-US fusion biopsy is less clear. Since a MRI-US fusion biopsy increases prostate cancer detection, this population should have a lower disease burden than patients with an initial negative TRUS-guided biopsy alone. Now that MRI-US fusion biopsies have been available for several years, such data are beginning to accumulate. Here, we investigate the detection rates of subsequent biopsies in patients with an initial negative MRI-US fusion prostate biopsy.     

MR-perfusion (MRP) and diffusion-weighted imaging (DWI) in prostate cancer: Quantitative and model-based gadobenate dimeglumine MRP parameters in detection of prostate cancer

Background

Various MR methods, including MR-spectroscopy (MRS), dynamic, contrast-enhanced MRI (DCE-MRI), and diffusion-weighted imaging (DWI) have been applied to improve test quality of standard MRI of the prostate.

Purpose

To determine if quantitative, model-based MR-perfusion (MRP) with gadobenate dimeglumine (Gd-BOPTA) discriminates between prostate cancer, benign tissue, and transitional zone (TZ) tissue.

Material and methods

27 patients (age, 65 ± 4 years; PSA 11.0 ± 6.1 ng/ml) with clinical suspicion of prostate cancer underwent standard MRI, 3D MR-spectroscopy (MRS), and MRP with Gd-BOPTA. Based on results of combined MRI/MRS and subsequent guided prostate biopsy alone (17/27), biopsy and radical prostatectomy (9/27), or sufficient negative follow-up (7/27), maps of model-free, deconvolution-based mean transit time (dMTT) were generated for 29 benign regions (bROIs), 14 cancer regions (cROIs), and 18 regions of transitional zone (tzROIs). Applying a 2-compartment exchange model, quantitative perfusion analysis was performed including as parameters: plasma flow (PF), plasma volume (PV), plasma mean transit time (PMTT), extraction flow (EFL), extraction fraction (EFR), interstitial volume (IV) and interstitial mean transit time (IMTT). Two-sided T-tests (significance level p < 0.05) discriminated bROIs vs. cROIs and cROIs vs. tzROIs, respectively.

Results

PMTT discriminated best between bROIs (11.8 ± 3.0 s) and cROIs (24.3 ± 9.6 s) (p < 0.0001), while PF, PV, PS, EFR, IV, IMTT also differed significantly (p 0.00002-0.0136). Discrimination between cROIs and tzROIs was insignificant for all parameters except PV (14.3 ± 2.5 ml vs. 17.6 ± 2.6 ml, p < 0.05).

Conclusions

Besides MRI, MRS and DWI quantitative, 2-compartment MRP with Gd-BOPTA discriminates between prostate cancer and benign tissue with several parameters. However, distinction of prostate cancer and TZ does not appear to be reliable.