[Multiparametric MRI and MRI-TRUS fusion biopsy in patients with prior negative prostate biopsy]

BACKGROUND

Multiparametric MRI (mpMRI) plays an increasingly important role in prostate cancer (PCa) diagnostics and is recommended in men with previously negative TRUS biopsy. The optimal biopsy method after mpMRI is under discussion.

OBJECTIVE

Prospective, PIRADS- and START-conform analysis of the relevance of mpMRI and MRI-TRUS fusion biopsy in patients with prior negative TRUS biopsy and comparison of the detection rates of fusion-targeted biopsies (tB) and systematic transperineal saturation biopsies (sB).

MATERIALS AND METHODS

Between 10/2012 and 09/2015, 287 patients with prior negative TRUS biopsy underwent mpMRI and software-assisted, rigid MRI-TRUS fusion biopsy. In addition to and strictly separated from sB (median cores n = 24), tB (median cores per patient n = 4, per lesion n = 3) were performed in case of suspicious MRI lesions (PIRADS ≥ 2). Both biopsy methods were compared by using McNemar's test.

RESULTS

Of the 287 patients, 148 (52 %) had positive biopsies. Of these, 108/287 (38 %) had significant PCa (Gleason Score [GS] = 3 + 3 and PSA ≥ 10 ng/ml or GS ≥ 3 + 4) and again 43/287 (15 %) had a GS ≥ 4 + 3 PCa. sB failed to diagnose 8/148 PCa (5.4 %) and 6/108 significant PCa (5.5 %), whereas tB failed to diagnose 48 (32.4 %) PCa (p < 0.0001) and 22 (20.4 %) significant PCa (p = 0.0046). Of the PCa missed by tB, 11  had a GS ≥ 3 + 4 and 5 of these a GS = 4 + 3. On a per patient basis, MRI failed to detect 5 significant PCa, whereby 17 of the significant PCa were missed by fusion-targeted cores alone.

CONCLUSIONS

In men with unsuspicious MRI (PIRADS < 3), there is a 11 % risk of significant PCa. In case of suspicious MRI lesions, the combination of both biopsy approaches offers maximum tumor detection.

Evaluation of microvascular permeability with dynamic contrast-enhanced MRI for the differentiation of primary CNS lymphoma and glioblastoma: radiologic-pathologic correlation

BACKGROUND AND PURPOSE

Dynamic contrast-enhanced MR imaging can provide in vivo assessment of the microvasculature in intracranial tumors. The aim of the present study was to evaluate the diagnostic performance of dynamic contrast-enhanced MR imaging derived vascular permeability parameters, including the volume transfer constant, the volume of extravascular extracellular space, and the flux rate constant between the extravascular extracellular space and plasma, for the differentiation of primary CNS lymphoma and glioblastoma.

MATERIALS AND METHODS

Sixty glioblastomas and 11 primary central nervous system lymphomas were included. Pretreatment T1-weighted dynamic contrast-enhanced MR imaging with a 3D T1-weighted spoiled gradient-echo sequence was performed on a 3T MR imaging scanner. Perfusion parameters (volume transfer constant, the volume of extravascular extracellular space, and the flux rate constant) were measured on the basis of the Tofts-Kernmode model. The Mann-Whitney U test and receiver operating characteristic analysis were used to compare those parameters between primary central nervous system lymphoma and glioblastoma. Histopathologic correlation of dynamic contrast-enhanced MR imaging findings was performed by using reticulin staining and CD31 immunohistochemistry.

RESULTS

Median volume transfer constant and flux rate constant values were significantly higher in primary central nervous system lymphoma (0.145 ± 0.057 and 0.396 ± 0.088) than in glioblastoma (0.064 ± 0.021 and 0.230 ± 0.058) (P < .001, respectively). Median volume of extravascular extracellular space values did not differ significantly between primary central nervous system lymphoma (0.434 ± 0.165) and glioblastoma (0.319 ± 0.107). On receiver operating characteristic analysis, volume transfer constant had the best discriminative value for differentiating primary central nervous system lymphoma and glioblastoma (threshold, 0.093; sensitivity, 90.9%; specificity, 95.0%). Histopathologic evaluation revealed intact vascular integrity in glioblastoma despite endothelial proliferation, whereas primary central nervous system lymphoma demonstrated destroyed vessel architecture, thereby promoting vascular disintegrity.

CONCLUSIONS

Primary central nervous system lymphoma demonstrated significantly higher volume transfer constant and flux rate constant values compared with glioblastoma, implying a higher vascular permeability in primary central nervous system lymphoma. These findings confirm initial observations from perfusion CT and dynamic contrast-enhanced MR imaging studies, correlating with underlying histopathologic features, and may be useful in distinguishing primary central nervous system lymphoma from glioblastoma.

MRI-guided prostate biopsy detects clinically significant cancer: analysis of a cohort of 100 patients after previous negative TRUS biopsy

PURPOSE

To investigate the positive biopsy rate of MRI-guided biopsy (MR-GB) in a routine clinical setting, identify factors predictive for positive biopsy findings and to report about the clinical significance of the diagnosed tumors.

METHODS

Patients with at least one negative trans-rectal-ultrasound-guided biopsy (TRUS-GB), persistently elevated or rising serum prostate specific antigen (PSA) and at least one lesion suspicious for PCa on diagnostic 1.5 Tesla endorectal coil MRI (eMR) were included. Biopsies were carried out using a 1.5 Tesla MRI and an 18 G biopsy gun. Clinical information and biopsy results were collected; logistic regression analysis was carried out. Definite pathology reports of patients with diagnosis of PCa and subsequent radical prostatectomy (RP) were analyzed for criteria of clinical significance.

RESULTS

One hundred patients were included, mean number of previous biopsies was 2 (range 1-9), mean PSA at time of biopsy was 11.7 ng/ml (1.0-65.0), and mean prostate volume was 46.7 ccm (range 13-183). In 52/100 (52.0%) patients, PCa was detected. Out of 52 patients, 27 patients with a positive biopsy underwent RP, 20 patients radiation therapy, and 5 patients active surveillance. In total, 80.8% of the patients revealed a clinically significant PCa. In univariate regression analysis, only serum PSA levels were predictive for a positive biopsy result. Number of preceding negative biopsies was not associated with the likelihood of a positive biopsy result.

CONCLUSIONS

MR-GB shows a high detection rate of clinically significant PCa in patients with previous negative TRUS-GB and persisting suspicion for PCa.