Accuracy of MR imaging for staging prostate cancer: a meta-analysis to examine the effect of technologic change

RATIONALE AND OBJECTIVES: The purpose of this study was to summarize the accuracy of magnetic resonance (MR) imaging for staging prostate cancer and to determine the effect of high magnetic field strength, use of the endorectal coil, use of fast spin-echo (SE) imaging, and study size on staging accuracy. MATERIALS AND METHODS: A literature search and review yielded 27 studies comparing MR imaging to a pathologic standard in patients with clinically limited prostate cancer. Subgroup analyses examined magnetic field strength, use of an endorectal coil, use of fast SE imaging, publication date, and study size. RESULTS: A summary receiver operating characteristic curve for all studies had a maximum joint sensitivity and specificity of 74%. At a specificity of 80% on this curve, sensitivity was 69%. Subgroup analyses showed that fast SE imaging was statistically significantly more accurate than conventional SE techniques (P < .001). Unexpectedly, studies employing higher magnetic field strength and those employing an endorectal coil were less accurate. CONCLUSION: Seemingly small technologic advances may influence test accuracy. Early and small studies, however, may overstate accuracy because of publication bias, bias in small samples, or earlier studies being performed by the experts who developed the technology itself.     

Preoperative staging of rectal cancer: accuracy of 3-Tesla magnetic resonance imaging

The purpose of this study was to evaluate the accuracy of 3-Tesla magnetic resonance imaging (MRI) for the preoperative staging of rectal cancer. Thirty-five patients with a primary rectal cancer who underwent preoperative 3-T MRI using a phased-array coil and had a surgical resection were enrolled in the study group. Preoperatively, three experienced radiologists independently assessed the T and N staging. A confidence level scoring system was used to determine if there was any perirectal invasion, and receiver operating characteristic (ROC) curves were generated. The interobserver agreement was estimated using κ statistics. The overall accuracy rate of T staging for rectal cancer was 92%. The diagnostic accuracy was 97% for T1, 89% for T2 and 91% for T3, respectively. The predictive accuracy for perirectal invasion by the three observers was high (Az>0.92). The interobserver agreement for T staging was moderate to substantial. The overall sensitivity, specificity, and accuracy for the detection of mesorectal nodal metastases were 80%, 98%, and 95%, respectively. In conclusion, preoperative 3-T MRI using a phase-array coil accurately indicates the depth of tumor invasion for rectal cancer with a low variability.     

Primary staging of prostate cancer

Staging prostate cancer is a systematic classification of the extent of disease based on clinical and pathological criteria. Despite general acceptance of the TNM staging system, a lot of controversy and uncertainty with respect to staging still exists. This paper gives an overview of different staging modalities and emphasizes the need for incorporation of prognostic factors, such as tumour grade and volume, in the staging system. Correspondence to: G. J. Jager     

Local staging of rectal cancer: a review of imaging

During the past decades the management of patients with rectal cancer has substantially changed, with a significant reduction in local recurrence rates following the introduction of better imaging, better surgery, and more efficient neoadjuvant therapy. This review discusses the clinically relevant information radiologists should know on staging of rectal cancer patients. The crucial role of the radiologist in patient management is explained. Furthermore, the evidence for the use of magnetic resonance imaging (MRI) in staging and restaging of rectal cancer patients as well as the main features that need to be evaluated when interpreting rectal cancer MRI are given. New diagnostic challenges as a result of new treatment options are also discussed.     

宫颈癌MRI分期与妇科检查分期对比分析

目的 对照妇科检查分期,探讨MRI在宫颈癌尤其是中、晚期宫颈癌分期中的价值。方法 32例具有完整临床及手术病理资料的宫颈癌患者,术前均行MRI检查,将MRI影像分期结果,临床妇科检查分期结果与宫颈癌术后病理分期结果相比较。结果 32例宫颈癌中,MRI分期判断为Iib期以前11例,Iib期（含Iib期）以后21例。与病理结果比较,MRI对二者区分的准确性为93%,对有无宫旁侵犯判断的准确性为94%,敏感性为91%,特异性为94%。妇科检查分期判断为Iib期以前14例,Iib期（含Iib期）以后18例。妇科检查对二者区分的准确性为87%,对有无宫旁侵犯判断的准确性为81%,敏感性为75%,特异性为87%。结论 MRI对早期宫颈癌的诊断及分期尚待改进,但对中晚期宫颈癌及宫颈癌宫旁侵犯,MRI具有重要临床应用价值。     

Multivariate random-effects approach: for meta-analysis of cancer staging studies

RATIONALE AND OBJECTIVES: Meta-analyses of diagnostic accuracy studies produce summary estimates of sensitivity and specificity. Cancer staging relies on staging systems and meta-analysis is often performed after dichotomization of the staging results. For each dichotomization, summary estimates of sensitivity and specificity can be calculated by repeated bivariate random-effects analyses. In this process, staging information is lost and under- and overstaging can not be adequately expressed. MATERIALS AND METHODS: We propose a new multivariate random-effects approach, which is an extension of the bivariate random-effects approach. To illustrate the principles and outcomes of both approaches, we used data from a meta-analysisevaluating endoluminal ultrasonography in staging of rectal cancer. In the multivariate approach, results on correct staging and under- and overstaging were calculated. In addition, the results from this analysis were used to calculate sensitivity and specificity estimates for each dichotomization and these estimates were compared with the results of the repeated bivariate analyses. RESULTS: By the multivariate analysis, results on correct staging and under- and overstaging were obtained. The sensitivity and specificity estimates for the dichotomizations, calculated from the results of this multivariate approach, were also comparable with the sensitivity and specificity estimates obtained by the repeated bivariate analyses. CONCLUSIONS: The multivariate random-effects approach can be a useful meta-analytic method for summarizing cancer staging data presented in diagnostic accuracy studies.     

Preoperative staging of renal cell carcinoma using magnetic resonance imaging: comparison with pathological staging

We have retrospectively assessed the accuracy of our MRI protocol on 1.0-T MRI system for preoperative staging of renal cell carcinoma using the 2002 TNM staging system and pathological staging as the gold standard.Medical records of 48 patients (mean age, 56.28 years) with 57 renal tumors were reviewed: 52 malignant renal tumors were found; most of the patients were staged T1N0M0. In our study, κ test revealed excellent agreement between all three classes of the TNM staging system.     

Dynamic breast magnetic resonance imaging without complications in a patient with dual-chamber demand pacemaker

Mammography and ultrasound indicated a cancer of the right breast in a 77-year-old woman with a dual-chamber demand pacemaker. The patient was not pacemaker-dependent. She underwent breast 1.5T magnetic resonance imaging (MRI) (dynamic gradient echo sequence with Gd-DOTA 0.1 mmol/kg). Before the patient entered the MR room, the configuration of the device was changed (the response to magnet was switched from asynchronous to off and the rate-responsive algorithm was disabled). No relevant modifications of heart rhythm or rate were observed during the MR examination. No symptom was reported. Immediately after the examination, the pacemaker interrogation showed neither program changes nor alert warnings. MRI detected a bifocal cancer in the right breast which allowed tailored breast-conserving treatment to be initiated. Histopathology confirmed a bifocal invasive ductal carcinoma.     

Transurethral prostate magnetic resonance elastography: Prospective imaging requirements

Tissue stiffness is known to undergo alterations when affected by prostate cancer and may serve as an indicator of the disease. Stiffness measurements can be made with magnetic resonance elastography performed using a transurethral actuator to generate shear waves in the prostate gland. The goal of this study was to help determine the imaging requirements of transurethral magnetic resonance elastography and to evaluate whether the spatial and stiffness resolution of this technique overlapped with the requirements for prostate cancer detection. Through the use of prostate‐mimicking gelatin phantoms, frequencies of at least 400 Hz were necessary to obtain accurate stiffness measurements of 10 mm diameter inclusions, but the detection of inclusions with diameters as small as 4.75 mm was possible at 200 Hz. The shear wave attenuation coefficient was measured in vivo in the canine prostate gland, and was used to predict the detectable penetration depth of shear waves in prostate tissue. These results suggested that frequencies below 200 Hz could propagate to the prostate boundary with a signal to noise ratio (SNR) of 60 and an actuator capable of producing 60 μm displacements. These requirements are achievable with current imaging and actuator technologies, and motivate further investigation of magnetic resonance elastography for the targeting of prostate cancer. Magn Reson Med, 2011. © 2010 Wiley‐Liss, Inc.     

A meta-analysis of the accuracy of prostate cancer studies which use magnetic resonance spectroscopy as a diagnostic tool

OBJECTIVE: We aimed to do a meta-analysis of the existing literature to assess the accuracy of prostate cancer studies which use magnetic resonance spectroscopy (MRS) as a diagnostic tool. MATERIALS AND METHODS: Prospectively, independent, blind studies were selected from the Cochrane library, Pubmed, and other network databases. The criteria for inclusion and exclusion in this study referenced the criteria of diagnostic research published by the Cochrane center. The statistical analysis was adopted by using Meta-Test version 6.0. Using the homogeneity test, a statistical effect model was chosen to calculate different pooled weighted values of sensitivity, specificity, and the corresponding 95% confidence intervals (95% CI). The summary receiver operating characteristic (SROC) curves method was used to assess the results. RESULTS: We chose two cut-off values (0.75 and 0.86) as the diagnostic criteria for discriminating between benign and malignant. In the first diagnostic criterion, the pooled weighted sensitivity, specificity, and corresponding 95% CI (expressed as area under curve [AUC]) were 0.82 (0.73, 0.89), 0.68 (0.58, 0.76), and 83.4% (74.97, 91.83). In the second criterion, the pooled weighted sensitivity, specificity, and corresponding 95% CI were 0.64 (0.55, 0.72), 0.86 (0.79, 0.91) and 82.7% (68.73, 96.68). CONCLUSION: As a new method in the diagnostic of prostate cancer, MRS has a better applied value compared to other common modalities. Ultimately, large scale RCT (randomized controlled trial) randomized controlled trial studies are necessary to assess its clinical value.     

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.     

Updates in advanced diffusion-weighted magnetic resonance imaging techniques in the evaluation of prostate cancer

Diffusion-weighted magnetic resonance imaging (DW-MRI) is considered part of the standard imaging protocol for the evaluation of patients with prostate cancer. It has been proven valuable as a functional tool for qualitative and quantitative analysis of prostate cancer beyond anatomical MRI sequences such as T2-weighted imaging. This review discusses ongoing controversies in DW-MRI acquisition, including the optimal number of b-values to be used for prostate DWI, and summarizes the current literature on the use of advanced DW-MRI techniques. These include intravoxel incoherent motion imaging, which better accounts for the non-mono-exponential behavior of the apparent diffusion coefficient as a function of b-value and the influence of perfusion at low b-values. Another technique is diffusion kurtosis imaging (DKI). Metrics from DKI reflect excess kurtosis of tissues, representing its deviation from Gaussian diffusion behavior. Preliminary results suggest that DKI findings may have more value than findings from conventional DW-MRI for the assessment of prostate cancer.     

Future of prostate imaging: Artificial intelligence in assessing prostatic magnetic resonance imaging

Prostate cancer (Pca; adenocarcinoma) is one of the most common cancers in adult males and one of the leading causes of death in both men and women. The diagnosis of Pca requires substantial experience, and even then the lesions can be difficult to detect. Moreover, although the diagnostic approach for this disease has improved significantly with the advent of multiparametric magnetic resonance, that technology has certain unresolved limitations. In recent years artificial intelligence (AI) has been introduced to the field of radiology, providing new software solutions for prostate diagnostics. Precise mapping of the prostate has become possible through AI and this has greatly improved the accuracy of biopsy. AI has also allowed for certain suspicious lesions to be attributed to a given group according to the Prostate Imaging-Reporting & Data System classification. Finally, AI has facilitated the combination of data obtained from clinical, laboratory (prostate-specific antigen), imaging (magnetic resonance), and biopsy examinations, and in this way new regularities can be found which at the moment remain hidden. Further evolution of AI in this field is inevitable and it is almost certain to significantly expand the efficacy, accuracy and efficiency of diagnosis and treatment of Pca.     

Multi-parametric MR imaging of transition zone prostate cancer: Imaging features, detection and staging

Magnetic resonance (MR) imaging has been increasingly used in the evaluation of prostate cancer. As studies have suggested that the majority of cancers arise from the peripheral zone (PZ), MR imaging has focused on the PZ of the prostate gland thus far. However, a considerable number of cancers (up to 30%) originate in the transition zone (TZ), substantially contributing to morbidity and mortality. Therefore, research is needed on the TZ of the prostate gland. Recently, MR imaging and advanced MR techniques have been gaining acceptance in evaluation of the TZ. In this article, the MR imaging features of TZ prostate cancers, the role of MR imaging in TZ cancer detection and staging, and recent advanced MR techniques will be discussed in light of the literature.     

磁共振成像检查在宫颈癌的诊断及分期中的应用价值分析

目的探讨磁共振成像检查对宫颈癌患者的诊断及分期价值。方法回顾性分析2016年10月至2018年11月在我院接受治疗的73例疑似宫颈癌患者的临床资料,所有入选者均需接受磁共振成像检查,分析诊断效能以及分期结果。结果以病理组织活检结果作为金标准,磁共振成像对宫颈癌的诊断敏感度为96.6%,特异度为78.6%,准确度为93.2%,阳性预测值为95.0%,阴性预测值为84.6%;磁共振成像对宫颈癌Ⅰa期的诊断符合率为80.0%,Ⅰb期为75.0%,Ⅱa期为75.0%,Ⅱb期为72.7%,Ⅲa期为44.4%,Ⅲb期为50.0%,Ⅳ期为50.0%。结论磁共振成像为临床诊断宫颈癌患者的有效手段,具有良好的诊断效能,且可为临床分期提供有效依据。     

多参数磁共振成像在前列腺癌中的应用进展

前列腺癌（PCa）的发病率位居全球男性恶性肿瘤的第二位,随着人口老龄化进程的加快,其发病率和病死率也在逐年上升。若PCa不被及早发现、检测、诊断,将严重危害老年男性的健康。自前列腺影像报告与数据系统V2.1版指南更新了多参数磁共振成像（mpMRI）序列及评分新规范以后,mpMRI在PCa中的应用前景更为广泛。多项研究报道了mpMRI在PCa活检前及指导靶向活检、主动监测、根治性前列腺切除术后局部复发及转移中的应用价值,但mpMRI评估PCa仍然存在局限性。笔者主要就mpMRI关键序列及评分的新规范、mpMRI评估PCa的应用进展、当前的局限性及潜在的解决方案展开综述。     

T2-weighted MR imaging of prostate cancer: multishot echo-planar imaging vs fast spin-echo imaging

The aim of the present study was to assess the performance of pre-biopsy T2-weighted MR imaging using multishot echo-planar imaging (EPI) sequence for visualization of prostate cancer and to compare image quality with that of fast spin-echo (FSE) sequence. Thirty-nine patients with suspected prostate cancer and one healthy male volunteer were examined on a 1.5-T MR scanner equipped with a pelvic phased-array coil. Axial MR images were obtained using multishot EPI sequence with a multishot number of 16 and FSE sequence without fat suppression. Paired EPI and FSE images were independently evaluated by three radiologists. Furthermore, signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were compared between EPI and FSE images of 12 pathologically proven lesions of prostate cancer. Delineation of the periprostatic venous plexus, prostate zonal anatomy, and seminal vesicle on EPI was graded to be superior/inferior to FSE in 15.8/0, 14.6/0, and 21.5/4.3% of cases, respectively. On the other hand, delineation of the neurovascular bundle was superior/inferior to FSE in 2.6/13.2% of cases. The SNR and CNR of prostate cancer on EPI were significantly higher than those on FSE (7.99±2.51 vs 3.36±0.58, p<0.0001, and 5.51±2.02 vs 2.21±0.79, p<0.0001, respectively). In conclusion, multishot EPI has higher quality of contrast resolution for imaging of prostate cancer compared with FSE and would have the potential usefulness in the detection of prostate cancer, although these results obtained with a phased-array coil cannot be extrapolated to examinations performed with an endorectal coil.     

Clinical significance of magnetic resonance imaging findings in rectal cancer

Staging of rectal cancer is essential to help guide clini-cians to decide upon the correct type of surgery and determine whether or not neoadjuvant therapy is indicated. Magnetic resonance imaging (MRI) is currently one of the most accurate modalities on which to base treatment decisions for patients with rectal cancer. MRI can accurately detect the mesorectal fascia, assess the invasion of the mesorectum or surrounding organs and predict the circumferential resection margin. Although nodal disease remains a difficult radiological diagnosis, new lymphographic agents and diffusion weighted imaging may allow identification of metastatic nodes by criteria other then size. In light of this, we have reviewed the literature on the accuracy of specific MRI findings for staging the local extent of primary rectal cancer. The aim of this review is to establish a correlation between MRI findings, prognosis, and available treatment options.