MR imaging of prostate cancer

PURPOSE: Accurate diagnosis and staging of prostate cancer (PC) is developing into an important health care issue in light of the high incidence of PC and the improvements in stage-adapted therapy. The purpose of this paper is to provide an overview on the current role of MR imaging and MR spectroscopy in the diagnosis and staging of PC. MATERIAL AND METHODS: Pertinent literature was searched and evaluated to collect information on current clinical indications, study techniques, diagnostic value, and limitations of magnetic resonance imaging and spectroscopy. RESULTS: Major indications for MR imaging of patients with suspected PC are to define tumor location before biopsy when clinical or TRUS findings are inconclusive, and to provide accurate staging of histologically proven PC to ascertain effective therapy. Current MR imaging techniques for the evaluation of PC include multiplanar high-resolution T2-weighted FSE and T1-weighted SE sequences using combined endorectal and phased-array coils. Using these techniques, the reported accuracy of MR imaging for the diagnosis of extracapsular tumor extension ranges between 82 and 88% with sensitivities between 80 and 95%, and specificities between 82 and 93%. Typical MR findings of PC in different stages of disease, as well as diagnostic problems, such as chronic prostatitis, biopsy-related hemorrhage and therapy-related changes of prostatic tissue are discussed. In addition, the current perspectives and limitations of MR spectroscopy in PC are summarized. CONCLUSIONS: Current MR imaging techniques provide important diagnostic information in the pretherapeutic workup of PC including a high staging accuracy, and is superior to TRUS.     

MR imaging of treated prostate cancer

Many management options are available to patients with newly diagnosed prostate cancer. Magnetic resonance (MR) imaging plays an important role in initial staging of prostate cancer, but it also aids in tumor detection when there is clinical or biochemical suspicion of residual or recurrent disease after treatment. The purpose of this review is to describe the normal appearances of the prostatic region after different kinds of treatment for prostate cancer and to discuss how these appearances differ from those of recurrent and residual disease. Several MR imaging techniques used in evaluating patients with prostate cancer are described, including conventional MR imaging sequences (mainly T1- and T2-weighted sequences), MR spectroscopic imaging, diffusion-weighted imaging, and dynamic contrast agent-enhanced MR imaging. Clinical considerations, together with the different approaches for interpreting serum prostate-specific antigen values in the posttreatment setting, are also presented. All forms of treatment alter the MR imaging features of the prostatic region to a greater or lesser extent, and it is important to be able to recognize expected posttreatment appearances and distinguish them from the features of recurrent or residual cancer to aid subsequent clinical management.     

前列腺癌功能磁共振成像诊断研究

近年来,随着MR技术的发展,一些功能成像技术,如扩散加权成像、动态增强MRI和MR波谱技术也越来越多地应用于前列腺研究。通过其对组织生理、病理和血供改变的观察,获悉活体器官功能状态,为前列腺癌早期发现,正确的诊断、分期和鉴别诊断提供了依据。     

前列腺癌的功能MRI

前列腺癌是老年男性最常见的恶性肿瘤之一。在2005年232090个美国人被诊断为前列腺癌，30350例患者因此死亡。在美国6个人中有1人患前列腺癌。大部分前列腺癌生长缓慢，早期诊断可以根治。但是，超过85％的前列腺癌患者发现多个癌灶。前列腺癌的诊断依靠超声引导下经直肠穿刺活检。由于超声对前列腺癌检测及定位准确性低，所以往往进行随机穿刺。     

The prostate: MR imaging and spectroscopy. Present and future

The applications of combined MR imaging and MR spectroscopic imaging of prostate cancer have expanded significantly over the past 10 years and have reached the point of clinical trial results to test robustness and clinical significance. MR spectroscopic imaging extends the diagnostic evaluation of prostate cancer beyond the morphologic information provided by MR imaging throughout the detection of cellular metabolites. The combined metabolic and anatomic information provided by MR imaging and MR spectroscopic imaging has allowed a more accurate assessment of the presence, location, extent, and aggressiveness of prostate cancer both before and after treatment. This information has already demonstrated the ability to improve therapeutic planning for individual prostate cancer patients and shows great promise in the assessment of therapeutic response and the evaluation of new treatment regimes.     

Molecular imaging of cancer: MR spectroscopy and beyond

Proton magnetic resonance spectroscopic imaging is a non-invasive diagnostic tool for the investigation of cancer metabolism. As an adjunct to morphologic and dynamic magnetic resonance imaging, it is routinely used for the staging, assessment of treatment response, and therapy monitoring in brain, breast, and prostate cancer. Recently, its application was extended to other cancerous diseases, such as malignant soft-tissue tumours, gastrointestinal and gynecological cancers, as well as nodal metastasis. In this review, we discuss the current and evolving clinical applications of proton magnetic resonance spectroscopic imaging. In addition, we will briefly discuss other evolving techniques, such as phosphorus magnetic resonance spectroscopic imaging, sodium imaging and diffusion-weighted imaging in cancer assessment.     

Nonpalpable prostate cancer: detection with MR imaging

The pathologic specimens and magnetic resonance (MR) images of 53 patients with clinically palpable prostate cancer confined to one lobe were studied to evaluate the ability of MR imaging to depict clinically nonpalpable prostate cancer. All patients had undergone imaging with a 1.5-T imager with T1- and T2-weighted sequences in both axial and sagittal planes before undergoing radical retropubic prostatectomy. At pathologic examination, only the palpable tumor was present in 30 of the 53 patients (57%), and 33 unsuspected tumors were present in an area distinct from the palpable tumor in 23 of the patients (43%). MR imaging successfully depicted 51 palpable tumors for a sensitivity of 96% and 19 of the 33 unsuspected tumors for a sensitivity of 58%. The sensitivity of MR imaging in the detection of nonpalpable, posteriorly located tumors was greater than for those located anteriorly (85% vs 15%). MR imaging was false-positive for nonpalpable tumor in 17 of 30 patients for a specificity of 43%. On the basis of these data, MR imaging has greater sensitivity in the depiction of posteriorly located cancer and is limited by a high false-positive rate in the depiction of nonpalpable tumors.     

MR spectroscopic imaging and diffusion-weighted imaging of prostate cancer with Gleason scores

Purpose:

To investigate functional changes in prostate cancer patients with three pathologically proven different Gleason scores (GS) (3+3, 3+4, and 4+3) using magnetic resonance spectroscopic imaging (MRSI) and diffusion‐weighted imaging (DWI).

Materials and Methods:

In this study MRSI and DWI data were acquired in 41 prostate cancer patients using a 1.5T MRI scanner with a body matrix combined with an endorectal coil. The metabolite ratios of (Cho+Cr)/Cit were calculated from the peak integrals of total choline (Cho), creatine (Cr), and citrate (Cit) in MRSI. Apparent diffusion coefficient (ADC) values were derived from DWI for three groups of Gleason scores. The sensitivity and specificity of MRSI and DWI in patients were calculated using receiver operating characteristic curve (ROC) analysis.

Results:

The mean and standard deviation of (Cho+Cr)/Cit ratios of GS 3+3, GS 3+4, and GS 4+3 were: 0.44 ± 0.02, 0.56 ± 0.06, and 0.88 ± 0.11, respectively. For the DWI, the mean and standard deviation of ADC values in GS 3+3, GS 3+4, and GS 4+3 were: 1.13 ± 0.11, 0.97 ± 0.10, and 0.83 ± 0.08 mm²/sec, respectively. Statistical significances were observed between the GS and metabolite ratio as well as ADC values and GS.

Conclusion:

Combined MRSI and DWI helps identify the presence and the proportion of aggressive cancer (ie, Gleason grade 4) that might not be apparent on biopsy sampling. This information can guide subsequent rebiopsy management, especially for active surveillance programs. J. Magn. Reson. Imaging 2012;36:697–703. © 2012 Wiley Periodicals, Inc.     

MR多参数联合成像在前列腺癌诊断中的研究进展

前列腺癌近年来在我国男性中的发病率逐步上升,已成为威胁中老年男性健康的重要疾病.MR有着良好的软组织分辨力和多方位成像优势,其多参数联合成像无创性诊断前列腺癌具有较大价值.随着MR技术的进展,扩散加权成像(diffusion weighted imaging,DWI)、扩散张量成像(diffusion tensor imaging,DTI)、扩散峰度成像(diffusion kurtosis imaging,DKI)、基于体素内不相干运动(intravoxel incoherent motion imaging,IVIM)的多b值DWI联合动态增强磁共振成像(dynamic contrast enhanced MRI,DCE-MRI)已经逐步应用于前列腺癌的研究及诊断.     

Detection of prostate cancer: Utility of diffusion-weighted MR imaging and 3D MR spectroscopic imaging

Purpose

To prospectively compare the mean ADC generated from DWI, the mean choline + creatine/citrate ratio generated from 3D MRS and the combined mean ADC and mean choline + creatine/citrate ratio in the detection of prostate cancer, and to correlate between the choline + creatine/citrate ratio and the aggressiveness of malignancy determined by Gleason score, with histopathological examination of the excised gland as the reference standard.

Patients and methods

Forty-six patients with biopsy-proved cancer underwent pre-operative MRI at 1.5 T. Axial T1, axial, coronal and sagittal T2-weighted, diffusion-weighted and 3D MRS using a point-resolved spectroscopic sequence (PRESS) were acquired. The mean ADC, mean choline + creatine/citrate ratio and combined parameters for malignant lesions are correlated with the pathological results. For each malignant lesion choline + creatine/citrate ratio was correlated with the aggressiveness of malignancy determined by Gleason score. Receiver operating characteristic (ROC) curves were used to determine sensitivity, and specificity of the studied parameters, and Kappa measures of agreement were calculated for prostate cancer detection.

Results

The mean ADC for tumor tissue was 1.0 ± 0.22 × 10⁻³ mm²/s (mean ± SD), and was significantly lower than that for non-tumor tissue 1.44 ± 0.28 × 10⁻³ mm²/s (p < 0.001). For MRS study the mean (choline + creatine)/citrate ratio in tumor tissue was 1.98 ± 1.0, and was significantly higher than that for non-tumor tissue, 0.72 ± 0.39 (p < 0.001). By combining both ADC values and (choline + creatine)/citrate ratio for differentiating malignant from non-malignant tissues a receiver operating characteristic analysis (ROC) curve showed Area under curve (AUC = 0.93) and was significantly higher than either (choline + creatine)/citrate ratio alone (AUC = 0.86) (p < 0.001) or ADC value alone (AUC = 0.89) (p < 0.001). There is an increasing (choline + creatine)/citrate ratio with increasing Gleason score, however, there is overlap between groups. A greater sensitivity of MRS for tumor detection 85% and 92% was present for tumors with Gleason score 4 + 3 and ?4 + 4, respectively, while for tumors with Gleason score 3 + 3 the sensitivity was 63%.

Conclusion

The combination of ADC and (choline + creatine)/citrate ratio is better than each parameter alone in differentiating between tumor and non-tumor prostatic tissue, also MR spectroscopic imaging findings of prostate tumor (Cho + Cr)/Cit ratio correlate with pathologic Gleason score. The combined parameters offer a promising non-invasive method for the diagnostic workup of prostate cancer.     

MR扩散加权成像在前列腺癌中的临床应用进展

超高b值扩散加权成像已成为近年来前列腺癌功能成像研究的热点,它不仅可以更加真实地反映前列腺癌组织的扩散特性,而且能对前列腺癌组织结构及细胞特性提供定性及定量分析.就MR扩散加权成像在前列腺癌的临床应用、超高b值的使用现状及其未来发展方向予以综述.     

MR波谱分析对前列腺癌诊断效能的研究

目的 以前列腺六分区法为基础,评价MRS对前列腺痛的诊断效能.方法 110例行MR前列腺检查的患者中前列腺癌54例,非前列腺癌56例,以经直肠穿刺活检病理结果作为金标准,计算前列腺MRS各体素内的(且H碱+肌酸)/枸橼酸盐(CC/C)的比值并采用秩和检验进行比较,计算六分区内阳性体素所占的比例(阳性体素比,PVR),采用ROC分析判断单个体素代谢物比值及分区内阳性体素比的诊断效能.结果 来源于癌区的体素1673个,非癌区体素2426个.癌区和非癌区体素的CC/C中位数分别为2.137和0.600,差异有统计学意义(Z-41.7,P<0.01).以单个体素CC/C比值0.911为临界点,诊断前列腺癌的敏感度为81.4%(1362/1673),特异度为83.1%(2018/2426),准确度为82.4%[(1362+2018)/4099].癌区和非癌区的PVR中位数分别为1和0,差异有统计学意义(Z=-11.7,P<0.01).以分区内PVR值0.519为临界点时,诊断前列腺癌的敏感度77.5%(148/191),特异度76.9%(247/321),准确度为77.1%[(148+247)/512].结论 通过确定单个体素CC/C比值及六分区内PVR的临界值,MRS有助于前列腺癌的量化诊断.     

MR imaging and MR spectroscopy in rhizomelic chondrodysplasia punctata

A case of rhizomelic chondrodysplasia punctata was investigated with MR imaging of the brain and hydrogen-1 MR spectroscopy of the brain and blood. Areas with abnormal signal hyperintensity on T2-weighted images or hypointensity on T1-weighted images were detected in the subcortical white matter. MR spectroscopy of the brain showed that normal-appearing white matter was characterized by increased levels of mobile lipids and myo-inositol, reduced levels of choline, and the presence of acetate. The importance of these metabolic anomalies is correlated to the deficiency in plasmalogen biosynthesis.     

联合应用MR波谱分析与扩散加权成像定量指标行前列腺癌定量诊断

目的 以前列腺六分区为基础,量化分析并验证MRS与DWI两种功能成像的定量指标在联合诊断前列腺癌时的权重大小.方法 搜集2006年2月至2007年7月间前列腺MR检查数据库中患者资料,并以接受前列腺MR检查的不同时间段,将入选前列腺检查患者分为2组,分别用于定量分析和验证结果,第1组为从2006年2月至12月期间、第2组为从2007年1月至7月期间的患者.每例患者在行常规MRI后,均进行MRS和DWI检查,测量MRS可用体素的(胆碱+肌酸)/枸橼酸盐(CC/C)值和分区内最小ADC值(ADC_(mini)).以CC/C≥0.911作为阳性体素标准,计算前列腺MRS六分区内阳性体素比(PVR).采用聚类分析中的线性判别,计算第1组分区内PVR和ADC_(mini)合用时各自所占的权重.将第2组分区内PVR和ADC_(mini)代入公式,采用ROC分析比较单独及联合诊断的诊断效能.结果 第1组和第2组均有40例患者,非前列腺癌加例,前列腺癌20例.由第1组病例得出的联合诊断线性判别公式为DWI和MRS联合诊断的非标准化线性判别值(D)=3.264×ADC_(mini)-0.205×PVR-4.407,分区内PVR和ADC_(mini)的曲线下面积(Az)分别为0.769和0.910,联合诊断的Az为0.909.第2组病例分区内PVR和ADC_(mini)的Az分别为0.838和0.912,联合诊断的Az为0.915.2组的联合诊断效能与单独使用DWI的诊断效能差异均无统计学意义(X~2值分别为0.32和1.50,P值均＞0.05).结论 DWI对前列腺癌的诊断效能高于MRS,联用2种功能参数不能明显提高总体的诊断效能.     

3D MR spectroscopic imaging in the evaluation of prostate cancer

The management of prostate cancer is a complex issue with a varying range of treatment options available. Magnetic resonance (MR) imaging of the prostate has been available for sometime but has the limitation of only anatomical evaluation. Three-dimensional MR spectroscopy is emerging as a new and sensitive tool in the metabolic evaluation of prostate cancer. This article reviews the principle, techniques, and methods of evaluation of spectroscopy and also discusses the applications of spectroscopy in the current management of prostate cancer.     

MR imaging and spectroscopy in Lhermitte-Duclos disease

Lhermitte-Duclos disease is a rare abnormality occurring in the cerebellum with only 130 cases reported in the literature. There is debate as to whether this abnormality is a hamartoma, a malformation or a tumour. In this case report we discuss the spectroscopy findings from two patients presenting with this disease. The patients, one 40-year-old Caucasian woman with a 6-year history of headaches, unsteady gait and falls, deterioration in vision and another 28-year-old Caucasian man with a 1-year history of headaches and a previous history of a transient stroke, were found to have this lesion in the cerebellum. Proton spectroscopic data were obtained using a single-voxel PRESS technique (TE=135 ms, TR=1600 ms), from the region of the abnormality. The results were expressed as ratios under the three prominent resonances representing choline (Cho), creatine (Cr), and N-acetyl (NA) moieties. The metabolite ratios were compared to normative data. The two cases demonstrated reduced ratios in NA/Cho and NA/Cr in relation to the controls. The ratios of Cho/Cr appeared closer to the normal mean ratio. There were peaks attributable to lactate in both cases. The low NA/Cr and NA/Cho ratios could be due to the apparent lack of neuronal architecture and the presence of embryonic neural tissue, which does not express NA, indicating more favourably towards a benign hamartoma rather than a tumour.     

三维氢质子MR波谱成像对前列腺移行带癌的诊断价值

目的 探讨三维氢质子MR波谱成像(3D 1HMRSI)对前列腺移行带癌的检出价值,并评估3D 1HMRSI判断移行带癌侵袭性的可行性.方法 回顾性分析60例常规MR成像疑诊为移行带癌患者的3D' HMRSI资料.参照穿刺活检病理结果,记录移行带癌和前列腺增生体素的(胆碱+肌酸)/枸橼酸盐[( Cho+ Cre)/Cit]比值.采用独立大样本t(’)检验比较移行带癌组和增生组(Cho+Cre)/Cit比值,应用ROC分析评估(Cho+ Cre)/Cit比值对移行带癌的诊断效能.根据Gleason评分将移行带癌分为低危(Gleason评分＜7分)、中危(Gleason评分=7分)和高危(Gleason评分＞7分)3个组,将3个组移行带癌的( Cho+ Cre)/Cit比值进行秩和检验.采用秩相关分析(Cho+ Cre)/Cit比值与Gleason评分的相关性.结果 25例为移行带癌,35例为良性前列腺增生.获取移行带癌体素177个,160个体素3D1HMRSI表现为Cho峰与Cit峰倒置,(Cho+ Cre)/Cit比值增高.前列腺增生体素517个,大多数谱线形态类似正常外周带.移行带癌组与增生组( Cho+ Cre)/Cit比值分别为2.17±1.29和0.77±0.20,差异有统计学意义(t’=14.38,P＜0.01).(Cho+ Cre)/Cit比值用于诊断移行带癌,ROC曲线下面积为0.985(P＜0.01),当(Cho+ Cre)/Cit比值取1.08为诊断临界值时,灵敏度为92.7％,特异度为94.2％,准确度为93.8％.低、中、高危组移行带癌的体素数分别为57、64和56个,( Cho+ Cre)/Cit比值分别为1.43(1.16 ～1.87)、1.66(1.43～2.36)和2.32(1.86 ～3.30),差异有统计学意义(x2=36.282,P＜0.01).(Cho+ Cre)/Cit比值随着Gleason评分的升高而增大,二者呈正相关(r =0.555,P＜0.01).结论 3D 1HMRSI有助于移行带癌的早期检出,(Cho+ Cre)/Cit比值能鉴别移行带癌和增生组织,是有价值的评估移行带癌侵袭性的影像指标.     

MR imaging and proton MR spectroscopy in adult Krabbe disease

We present the MR imaging findings in four patients (two pairs of siblings from two unrelated families) with adult Krabbe disease. In the first family, clinical presentation mimicked familial spastic paraplegia. Their MR images showed selective, increased signal intensity on T2-weighted sequences along the corticospinal tracts, most prominently in the proband and barely detectable in her brother. Proton MR spectroscopy showed increased choline and myo-inositol in the affected white matter. In the second family, the clinical presentation differed in that the signs of pyramidal tract involvement were asymmetrical, with concomitant asymmetry on MR images in one. In adults, Krabbe disease may present on MR imaging with selective pyramidal fiber involvement.