Bildgebende Verfahren bei der Diagnose des Prostatakarzinoms

Identifying and analyzing different cancer subtypes using RNA-seq data of blood platelets

Detection and diagnosis of cancer are especially important for early prevention and effective treatments. Traditional methods of cancer detection are usually time-consuming and expensive. Liquid biopsy, a newly proposed noninvasive detection approach, can promote the accuracy and decrease the cost of detection according to a personalized expression profile. However, few studies have been performed to analyze this type of data, which can promote more effective methods for detection of different cancer subtypes. In this study, we applied some reliable machine learning algorithms to analyze data retrieved from patients who had one of six cancer subtypes (breast cancer, colorectal cancer, glioblastoma, hepatobiliary cancer, lung cancer and pancreatic cancer) as well as healthy persons. Quantitative gene expression profiles were used to encode each sample. Then, they were analyzed by the maximum relevance minimum redundancy method. Two feature lists were obtained in which genes were ranked rigorously. The incremental feature selection method was applied to the mRMR feature list to extract the optimal feature subset, which can be used in the support vector machine algorithm to determine the best performance for the detection of cancer subtypes and healthy controls. The ten-fold cross-validation for the constructed optimal classification model yielded an overall accuracy of 0.751. On the other hand, we extracted the top eighteen features (genes), including TTN, RHOH, RPS20, TRBC2, in another feature list, the MaxRel feature list, and performed a detailed analysis of them. The results indicated that these genes could be important biomarkers for discriminating different cancer subtypes and healthy controls.

Accuracy of shear wave elastography for the diagnosis of prostate cancer: A meta-analysis

Many studies have established the high diagnostic accuracy of shear wave elastography (SWE) for the detection of prostate cancer (PCa); however, its utility remains a subject of debate. This meta-analysis sought to appraise the overall accuracy of SWE for the detection of PCa. A literature search of the PubMed, Embase, Cochrane Library, Web of Science and CNKI (China National Knowledge Infrastructure) databases was conducted. In all of the included studies, the diagnostic accuracy of SWE was compared with that of histopathology, which was used as a standard. Data were pooled, and the sensitivity, specificity, area under the curve (AUC), positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR) were calculated to estimate the accuracy of SWE. The pooled sensitivity and specificity for the diagnosis of PCa by SWE were 0.844 (95% confidence interval: 0.696–0.927) and 0.860 (0.792–0.908), respectively. The AUC was 0.91 (0.89–0.94), the PLR was 6.017 (3.674–9.853), and the NLR was 0.182 (0.085–0.389). The DOR was 33.069 (10.222–106.982). Thus, SWE exhibited high accuracy for the detection of PCa using histopathology as a diagnostic standard. Moreover, SWE may reduce the number of core biopsies needed.

Comparison of meta-analyses among elastosonography (ES) and positron emission tomography/computed tomography (PET/CT) imaging techniques in the application of prostate cancer diagnosis

The early diagnosis of prostate cancer (PCa) appears to be of vital significance for the provision of appropriate treatment programs. Even though several sophisticated imaging techniques such as positron emission tomography/computed tomography (PET/CT) and elastosonography (ES) have already been developed for PCa diagnosis, the diagnostic accuracy of these imaging techniques is still controversial to some extent. Therefore, a comprehensive meta-analysis in this study was performed to compare the accuracy of various diagnostic imaging methods for PCa, including 11C-choline PET/CT, 11C-acetate PET/CT, 18F-fluorocholine PET/CT, 18F-fluoroglucose PET/CT, transrectal real-time elastosonography (TRTE), and shear-wave elastosonography (SWE). The eligible studies were identified through systematical searching for the literature in electronic databases including PubMed, Cochrane, and Web of Science. On the basis of the fixed-effects model, the pooled sensitivity (SEN), specificity (SPE), and area under the receiver operating characteristics curve (AUC) were calculated to estimate the diagnostic accuracy of 11C-choline PET/CT, 11C-acetate PET/CT, 18F-fluorocholine (FCH) PET/CT, 18F-fluoroglucose (FDG) PET/CT, TRTE, and SWE. All the statistical analyses were conducted with R language Software. The present meta-analysis incorporating a total of 82 studies demonstrated that the pooled sensitivity of the six imaging techniques were sorted as follows: SWE > 18F-FCH PET/CT > 11C-choline PET/CT > TRTE > 11C-acetate PET/CT > 18F-FDG PET/CT; the pooled specificity were also compared: SWE > 18F-FCH PET/CT > 11C-choline PET/CT > TRTE > 18F-FDG PET/CT > 11C-acetate PET/CT; finally, the pooled diagnostic accuracy of the six imaging techniques based on AUC were ranked as below: SWE > 18F-FCH PET/CT > 11C-choline PET/CT > TRTE > 11C-acetate PET/CT > 18F-FDG PET/CT. SWE and 18F-FCH PET/CT imaging could offer more assistance in the early diagnosis of PCa than any other studied imaging techniques. However, the diagnostic ranking of the six imaging techniques might not be applicable to the clinical phase due to the shortage of stratified analysis.

Real-time elastography in the diagnosis of patients suspected of having prostate cancer: a meta-analysis

The goal of the study described here was to assess the performance of real-time elastography (RTE) in the detection of prostate cancers using a meta-analysis. A literature search of PubMed, Medline, Embase and the Cochrane Library was conducted. Published studies that evaluated the diagnostic performance of RTE in the diagnosis of prostate cancer and using the histopathology of the radical prostatectomy specimen as a reference standard were included. Sensitivity, specificity, positive likelihood ratio, negative likelihood ratio and area under the curve were calculated to examine the accuracy of RTE. A total of seven studies that included 508 patients were analyzed. The pooled sensitivity and specificity for the diagnosis of prostate cancer by RTE were 0.72 (95% confidence interval: 0.70-0.74) and 0.76 (0.74-0.78), respectively. The summary diagnostic odds ratio was 12.59 (7.26-21.84), and the area under the curve was 0.841 (Q* = 0.773). In conclusion, RTE imaging has high accuracy in the detection of prostate cancers using the histopathology of the radical prostatectomy specimen as the reference standard and may reduce the number of core biopsies in the future.

Multiparametric ultrasound of the prostate: adding contrast enhanced ultrasound to real-time elastography to detect histopathologically confirmed cancer

PURPOSE

We prospectively assessed whether a combined approach of real-time elastography and contrast enhanced ultrasound would improve prostate cancer visualization.

MATERIAL AND METHODS

Between June 2011 and January 2012, 100 patients with biopsy proven prostate cancer underwent preoperative transrectal multiparametric ultrasound combining real-time elastography and contrast enhanced ultrasound. After initial elastographic screening for suspicious lesions, defined as blue areas with decreased tissue strain, each lesion was allocated to the corresponding prostate sector. The target lesion was defined as the largest cancer suspicious area. Perfusion was monitored after intravenous injection of contrast agent. Target lesions were examined for hypoperfusion, normoperfusion or hyperperfusion. Imaging results were correlated with final pathological evaluation on whole mount slides after radical prostatectomy.

RESULTS

Of 100 patients 86 were eligible for final analysis. Real-time elastography detected prostate cancer with 49% sensitivity and 73.6% specificity. Histopathology confirmed malignancy in 56 of the 86 target lesions (65.1%). Of these 56 lesions 52 (92.9%) showed suspicious perfusion, including hypoperfusion in 48.2% and hyperperfusion in 48.2%, while only 4 (7.1%) showed normal perfusion patterns (p = 0.001). The multiparametric approach decreased the false-positive value of real-time elastography alone from 34.9% to 10.3% and improved the positive predictive value of cancer detection from 65.1% to 89.7%.

CONCLUSIONS

Perfusion patterns of prostate cancer suspicious elastographic lesions are heterogeneous. However, the combined approach of real-time elastography and contrast enhanced ultrasound in this pilot study significantly decreased false-positive results and improved the positive predictive value of correctly identifying histopathological cancer.

Transrectal sonoelastography in the detection of prostate cancers: a meta-analysis

What's known on the subject? and What does the study add? The accuracy of transrectal sonoelastography (TRSE) in the detection of prostate cancer is variable, with a sensitivity ranging from 51.1 to 91.7% and specificity ranging from 62.2 to 86.8%. This is the first meta-analysis to assess the overall accuracy of TRSE in the detection of prostate cancer.

OBJECTIVE

• To assess the overall accuracy of transrectal sonoelastography (TRSE) targeted biopsy in the diagnosis of patients suspected of having prostate cancer (PCa).

METHODS

• A systematic search of electronic databases, including PubMed, Embase and The Cochrane Library, and manual bibliography searches were performed. • All relevant studies assessing the diagnostic accuracy of TRSE in PCa detection were included in our meta-analysis. • The data were pooled and sensitivity, specificity, area under the curve (AUC), positive likelihood ratio (LR) and negative LR were calculated.

RESULTS

• Pooled patient data analysis: the pooled (95% confidential intervals [95% CI]) sensitivity of TRSE targeted biopsy in patients suspected of having PCa was 62 (55-68) %; specificity was 79% (74-84%); AUC was 0.7696; positive LR was 2.92 (2.28-3.74); and negative LR was 0.49 (0.41-0.59). • Pooled core data analysis: pooled (95% CI) sensitivity, specificity, positive LR and negative LR were 34% (30-38%), 93% (91-95%), 5.07 (3.91-6.57) and 0.71 (0.66-0.75), respectively.

CONCLUSION

• Transrectal sonoelastography is a promising technique in PCa detection and can be considered to be a valuable supplemental method to systemic biopsy.

The contribution of strain patterns in characterization of prostate peripheral zone lesions at transrectal ultrasonography

BACKGROUND

Elasticity is an important characteristic of tissue. During an elastography examination, various strain images of lesions are observed, and a suitable classification of strain patterns (SP) may provide vital diagnostic information about lesions. Numerous studies have shown that ultrasound elastography can improve the detection of prostate cancer, but the diagnostic value of SP classification has not yet been fully evaluated.

PURPOSE

To investigate the contribution of SP on the characterization of prostate peripheral zone lesions by transrectal real-time tissue elastography (TRTE) in combination with conventional transrectal ultrasonography (TRUS).

MATERIAL AND METHODS

One hundred and seventy-one patients with suspected prostate cancer underwent TRUS and TRTE examinations. The SPs of the suspicious lesions were classified into five scores by TRTE according to the degree and distribution of strain. All findings were confirmed by transrectal systematic 12-core biopsies and targeted biopsies for suspicious areas detecting by TRUS and/or TRTE.

RESULTS

One hundred and forty-eight of 171 patients had high-quality TRTE imaging and were included into the study. When a cut-off point of SP score III was used, the area under the receiver-operating characteristic curve (AUC) was, respectively, 0.75 (95% CI: 0.67-0.83), 0.85 (95% CI: 0.78-0.91) and 0.84 (95% CI: 0.77-0.91) for the diagnosis of prostate cancer by TRUS, TRTE and TRTE + TRUS. A linear tendency of SP and Gleason scores was observed in scores III-V. The detection rate of prostate cancer using TRTE-targeted biopsy (75.8%) was significantly higher than that of systematic 12-core biopsy plus TRUS-targeted biopsy (14.5%) (P = 0.00).

CONCLUSION

This study suggests the significant contribution of SP on characterization of prostate peripheral zone lesions and the improvement of TRTE-targeted biopsy on detection of prostate cancer.

[Diffusion-weighted MRI of the prostate]

Diffusion-weighted magnetic resonance imaging (DWI) can complement MRI of the prostate in the detection and localization of prostate cancer, particularly after previous negative biopsy. A total of 13 original reports and 2 reviews published in 2010 demonstrate that prostate cancer can be detected by DWI due to its increased cell density and decreased diffusiveness, either qualitatively in DWI images or quantitatively by means of the apparent diffusion coefficient (ADC). In the prostate, the ADC is influenced by the strength of diffusion weighting, localization (peripheral or transitional zone), presence of prostatitis or hemorrhage and density and differentiation of prostate cancer cells. Mean differences between healthy tissue of the peripheral zone and prostate cancer appear to be smaller for ADC than for the (choline + creatine)/citrate ratio in MR spectroscopy. Test quality parameters vary greatly between different studies but appear to be slightly better for combined MRI and DWI than for MRI of the prostate alone. Clinical validation of DWI of the prostate requires both increased technical conformity and increased numbers of patients in clinical studies.

Comparison of real-time elastography with grey-scale ultrasonography for detection of organ-confined prostate cancer and extra capsular extension: a prospective analysis using whole mount sections after radical prostatectomy

OBJECTIVE

•To evaluate whether transrectal real-time elastography (RTE) improves the detection of intraprostatic prostate cancer (PCa) lesions and extracapsular extension (ECE) compared with conventional grey-scale ultrasonography (GSU).

PATIENTS AND METHODS

•In total, 229 patients with biopsy-proven PCa were prospectively screened for cancer-suspicious areas and ECE using GSU and RTE. •The largest tumour focus detected by RTE was defined as the index lesion. •The prostate gland was stratified into six sectors on GSU and RTE, which were compared with histopathological whole mount sections after radical prostatectomy.

RESULTS

•Histopathologically, PCa was confirmed in 894 out of 1374 (61.8%) evaluated sectors and ECE was identified in 47 (21%) patients. •Of these 894 sectors, RTE correctly detected 594 (66.4%) and GSU 215 (24.0%) cancer suspicious lesions. •Sensitivity was 51% and specificity 72% using RTE compared to 18% and 90% for GSU. •RTE identified the largest side specific tumour focus in 68% of patients. •ECE was identified with a sensitivity of 38% and specificity of 96% using RTE compared to 15% and 97% using GSU.

CONCLUSIONS

•Compared with GSU, RTE provides a statistically significant improvement in detection of PCa lesions and ECE. •RTE enhances GSU, although improvement is still needed to achieve a clinically meaningful sensitivity.

Differentiation of prostate cancer from benign lesions using strain index of transrectal real-time tissue elastography

OBJECTIVE

This study was to assess the diagnostic value of strain index (SI) for transrectal real-time tissue elastography (TRTE) on differentiating malignant from benign lesions in the prostate peripheral zone.

METHODS

83 patients suspected of having prostate cancer (PCa) underwent transrectal ultrasonography (TRUS) and TRTE examinations. The lesions in the prostate peripheral zone detected by TRTE were set as the regions of interest (ROI) for strain ratio (SR) measurement (SRA). The moderate texture tissues without lesion were set as the reference ROI for SR measurement (SRB). Then, SI (SRB/SRA) of total lesions (ASI) and local lesion (PSI) were calculated, and the diagnostic values of ASI and PSI on differentiating benign from malignant lesions were assessed respectively.

RESULTS

The range of PSI was 2.23-67.21 (29.97 ± 15.58) in malignant tumors and 0. 4-43.6 (7.79 ± 8.75) in benign lesions (AUC=0.90), while the range of ASI was 2.84-47.9 (8.38 ± 12.20) in malignant tumors and 0.4 -2.79 (5.85 ± 7.29) in benign lesions (AUC=0.62). There was significant difference of PSI values between the benign and malignant lesions (P<0.01). At the cutoff value of 17.44, PSI yielded the highest sensitivity (74.5%) and specificity (83.3%) for discriminating PCa from benign lesions. The capability of PSI in the diagnosis of PCa improved with the increase of Gleason scores.

CONCLUSION

PSI is one of the elasticity parameters obtained easily by TRTE, it can provide more information in the differentiation of prostate peripheral zone lesions.

Status of transrectal ultrasound imaging of the prostate

PURPOSE

To describe the current and new developments in transrectal ultrasound (US) imaging of the prostate.

PATIENTS AND METHODS

Grayscale imaging of the prostate is the standard method for diagnostic evaluation and biopsy guidance. Color Doppler (CD) imaging, including CD and power Doppler US, allows for detection of macrovascularity and may therefore be helpful for assessment of prostatic blood flow. The use of US microbubbles for CD imaging and new contrast-specific techniques enable assessment of prostate microvascularity associated with prostate cancer (PCa). Recently, real-time elastography has been introduced to improve detection of cancer based upon changes in tissue stiffness.

RESULTS

Contrast-enhanced CD imaging has shown to enable PCa detection by performing targeted biopsies into suspicious areas. Comparisons between systematic and contrast-enhanced targeted biopsies have shown that the targeted approach detects more cancers and cancers with higher Gleason scores with a reduced number of biopsy cores. New microbubble-specific US techniques can improve sensitivity and specificity of US imaging for PCa detection. Real-time elastography has been demonstrated to be useful for the detection of PCa, and may further improve PCa staging.

CONCLUSIONS

The new US techniques seem to have the potential to improve PCa detection, and also PCa grading and staging. As these diagnostic methods improve, the ultimate hope is to eliminate biopsy in patients without cancer.

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.

[Diagnostic radiology of the pelvis. Prostate cancer, bladder cancer, and incontinence]

Prostate cancer, bladder cancer, and pelvic floor weakness are among the most common diseases of the pelvis. Cardinal symptoms include painless macrohematuria in bladder cancer and urinary and fecal incontinence in pelvic floor weakness. Suspicion of prostate cancer currently is most frequently raised when the serum concentration of prostate-specific antigen is pathologically elevated. Besides extensive clinical and invasive diagnosis, clinical imaging is frequently applied for the localization, locoregional staging, and diagnosis of recurrence of prostate cancer and invasive bladder cancer, and in clinically difficult cases of cystocele, enterocele, rectocele, descensus or prolapse of vagina, uterus, and rectum, and rectal intussusception. Magnetic resonance imaging with T2-weighted TSE or FSE images in several planes combined with either axial, T1-weighted images and MR spectroscopy for the prostate, dynamic contrast-enhanced T1-weighted images for the urinary bladder, or dynamic T2-weighted functional images for pelvic floor incontinence are particularly well suited as clinical imaging methods.