Oncological imaging of the abdomen and pelvis: Spectrum of trends and advances

Advancements in medical imaging have brought about unprecedented changes in the assessment, management and post-treatment follow-up of cancer. Sonography, positron emission tomography, computed tomography and magnetic resonance imaging are the primary tools being developed for oncological imaging. Advancements in these modalities, the introduction of new imaging and treatment techniques, as well as recent management of tumors, have led to continuous changes in diagnosis and treatment. Herein, we discuss the wide spectrum of imaging trends and advances.     

Local staging of prostate cancer with MRI

Accurate local staging of prostate cancer is essential for patient management decisions. Conventional and evolving magnetic resonance imaging (MRI) techniques, such as diffusion- weighted imaging, dynamic contrast-enhanced MRI, and MR spectroscopy, are promising techniques in prostate cancer imaging. In this article, we will review the current applications of conventional and advanced MRI techniques in the local staging of prostate cancer.     

Simple baseline correction for 1H MRSI data of the prostate

Proton magnetic resonance spectroscopic imaging of the prostate can detect and localise tumour tissue in patients with prostate cancer. Pattern recognition methods have the potential to discriminate tumour from normal tissue using the spectral patterns of magnetic resonance spectroscopic imaging data thus providing a powerful tool for diagnosis and monitoring treatment of prostate cancer. Prostate magnetic resonance spectroscopic imaging data acquisition has been optimized for a flat baseline, including a long echo time and the use of water and fat suppression pulses. Despite this acquisition method, lipid resonances may still occur particularly at the margins of the prostate. Correcting the baseline by removing lipid artifacts is, therefore, a necessary processing step. We propose a simple baseline correction method for prostate magnetic resonance spectroscopic imaging through subtraction of a single simulated‐Lorentzian resonance. This method is shown to restore flat baselines to a test set of spectra and compares favorably with a state‐space modeling approach. Magn Reson Med, 2012. © 2012 Wiley Periodicals, Inc.     

In vivo prostate magnetic resonance spectroscopic imaging using two-dimensional J-resolved PRESS at 3 T.

In vivo magnetic resonance spectroscopic imaging of the prostate using single-voxel and multivoxel two-dimensional (2D) J-resolved sequences is investigated at a main magnetic field strength of 3 T. Citrate, an important metabolite often used to aid the detection of prostate cancer in magnetic resonance spectroscopic exams, can be reliably detected along with the other metabolites using this method. We show simulations and measurements of the citrate metabolite using 2D J-resolved spectroscopy to characterize the spectral pattern. Furthermore, using spiral readout gradients, the single-voxel 2D J-resolved method is extended to provide the spatial distribution information as well all within a reasonable scan time (17 min). Phantom and in vivo data are presented to illustrate the multivoxel 2D J-resolved spiral chemical shift imaging sequence.     

扩散峰度成像在直肠癌中的研究进展

扩散峰度成像（DKI）是一种以生物组织内水分子扩散运动呈非高斯分布为理论基础的功能MRI技术,能够描述组织内水分子扩散运动受限的真实情况,准确反映组织微观结构的复杂程度,目前已用于直肠癌的诊疗及疗效评估。介绍DKI的原理及其定量参数,概述DKI在直肠癌诊断、临床病理特征评价、分子生物学特征表征及新辅助疗效评估方面的研究进展,分析DKI在直肠癌应用中的局限性。     

A review of the efficacy of bone scanning in prostate and breast cancer.

Bone scintigraphy has provided valuable data in the assessment and management of neoplastic disease since being first described in the early 1960s. There have been many developments in imaging techniques and radiopharmaceuticals over the years allowing more reliable detection of metastatic spread to bone. Other imaging modalities are also evolving roles in the detection of metastatic spread including computed tomography (CT), magnetic resonance imaging (MRI), and positron emission tomography (PET). Despite this, isotope bone scans continue to have a central role in detection and surveillance of bone metastases in breast and prostate cancer. Paralleling developments in imaging there have been enormous changes in the treatment options available for cancers of the breast and prostate that have metastasised to bone. Bone specific treatments including radionuclides and bisphosphonates as well as high dose chemotherapy provide potential improvement in disease control. There is also evidence that earlier treatment of bone metastases may prolong survival. This increases the need for efficient methods of detection and monitoring of disease. In this article we discuss the efficacy of bone scintigraphy in breast and prostate cancer from the point of view of staging, systematic follow-up of asymptomatic patients, evaluation of symptomatic patients and the assessment of response to therapy.     

Multivariate statistical mapping of spectroscopic imaging data

For magnetic resonance spectroscopic imaging studies of the brain, it is important to measure the distribution of metabolites in a regionally unbiased way; that is, without restrictions to a priori defined regions of interest. Since magnetic resonance spectroscopic imaging provides measures of multiple metabolites simultaneously at each voxel, there is furthermore great interest in utilizing the multidimensional nature of magnetic resonance spectroscopic imaging for gains in statistical power. Voxelwise multivariate statistical mapping is expected to address both of these issues, but it has not been previously employed for spectroscopic imaging (SI) studies of brain. The aims of this study were to ( 1 ) develop and validate multivariate voxel‐based statistical mapping for magnetic resonance spectroscopic imaging and ( 2 ) demonstrate that multivariate tests can be more powerful than univariate tests in identifying patterns of altered brain metabolism. Specifically, we compared multivariate to univariate tests in identifying known regional patterns in simulated data and regional patterns of metabolite alterations due to amyotrophic lateral sclerosis, a devastating brain disease of the motor neurons. Magn Reson Med, 2010. © 2009 Wiley‐Liss, Inc.     

The role of dynamic contrast-enhanced and diffusion weighted magnetic resonance imaging in the female pelvis

Functional imaging by means of dynamic multiphase contrast-enhanced magnetic resonance imaging (DCE-MRI) and diffusion weighted magnetic resonance imaging (DW-MRI) is now part of the standard imaging protocols for evaluation of the female pelvis. DCE-MRI and DW-MRI are important MR imaging techniques which enable the radiologist to move from morphological to functional assessment of diseases of the female pelvis. This is mainly due to the limitations of morphologic imaging, particularly in lesion characterization, accurate lymph node staging, assessment of tumour response and inability to differentiate post-treatment changes from tumour recurrence.DCE-MRI improves the accuracy of T2WI in staging of endometrial cancer. It also helps differentiate tumour recurrence from radiation fibrosis in patients with cervical cancer. DCE-MRI improves characterization of cystic adnexal lesions and detection of small peritoneal implants in patients with ovarian cancer.DW-MRI is valuable in preoperative staging of patients with endometrial and cervical cancer, especially in detection of extra-uterine disease. It does increase reader's confidence for detection of recurrent disease in gynaecological malignancies and improves detection of small peritoneal implants in patients with ovarian cancer.In this review article we give an overview of both DCE-MRI and DW-MRI techniques, concentrating on their main clinical application in the female pelvis, and present a practical approach of the added value of these techniques according to the main pathological conditions, highlighting the pearls and pitfalls of each technique.     

Proton MR spectroscopy in the breast: Technical innovations and clinical applications

Proton magnetic resonance spectroscopy (MRS) is a promising noninvasive diagnostic technique for investigation of breast cancer metabolism. Spectroscopic imaging data may be obtained following contrast‐enhanced MRI by applying the point‐resolved spectroscopy sequence (PRESS) or the stimulated echo acquisition mode (STEAM) sequence from the MR voxel encompassing the breast lesion. Total choline signal (tCho) measured in vivo using either a qualitative or quantitative approach has been used as a diagnostic test in the workup of malignant breast lesions. In addition to tCho metabolites, other relevant metabolites, including multiple lipids, can be detected and monitored. MRS has been heavily investigated as an adjunct to morphologic and dynamic MRI to improve diagnostic accuracy in breast cancer, obviating unnecessary benign biopsies. Besides its use in the staging of breast cancer, other promising applications have been recently investigated, including the assessment of treatment response and therapy monitoring. This review provides guidance on spectroscopic acquisition and quantification methods and highlights current and evolving clinical applications of proton MRS. Level of Evidence 5 Technical Efficacy: Stage 5 J. Magn. Reson. Imaging 2019.     

乳腺癌分子成像的应用价值

乳腺癌是女性最常见的恶性肿瘤之一,早期诊断及正确评估其侵袭性是影响乳腺癌病人预后的重要因素。多种分子成像技术(包括超声、磁共振成像、放射性核素显像及光学分子成像)对乳腺癌的诊断、临床亚型判断、治疗方式选择及预后评估均有重要价值。其中,超声靶向微泡治疗和光学分子成像指导乳腺癌手术治疗等技术的发展有望成为乳腺癌治疗的新方式。就多种分子成像技术在乳腺癌中的应用价值予以综述。     

Progress in atherosclerotic plaque imaging

Cardiovascular diseases are the primary cause of mortality in the industrialized world,and arterial obstruction, triggered by rupture-prone atherosclerotic plaques,lead to myocardial infarction and cerebral stroke.Vulnerable plaques do not necessarily occur with flow-limiting stenosis,thus conventional luminographic assessment of the pathology fails to identify unstable lesions.In this review we discuss the currently available imaging modalities used to investigate morphological features and biological characteristics of the atherosclerotic plaque. The different imaging modalities such as ultrasound, magnetic resonance imaging,computed tomography, nuclear imaging and their intravascular applications are illustrated,highlighting their specific diagnostic potential.Clinically available and upcoming methodologies are also reviewed along with the related challenges in their clinical translation,concerning the specific invasiveness, accuracy and cost-effectiveness of these methods.     

静、动态MRI用于盆底功能障碍肛提肌评价的研究进展

盆底功能障碍是由于盆底支持结构薄弱所引起的包括盆腔器官脱垂、排尿及排便功能障碍等一系列症状的疾病。肛提肌是支持盆底的主要结构,静态MRI具有较高的软组织分辨力,能客观地评价肛提肌的形态及结构,动态MRI能实时反映肛提肌的运动及功能,为其全面评估提供客观依据。就静、动态MRI在盆底功能障碍中对肛提肌评价的应用及研究进展予以综述。     

Tumor imaging using hyperpolarized 13C magnetic resonance spectroscopy

Dynamic nuclear polarization is an emerging technique for increasing the sensitivity of magnetic resonance imaging and spectroscopy, particularly for low‐γ nuclei. The technique has been applied recently to a number of ¹³C‐labeled cell metabolites in biological systems: the increase in signal‐to‐noise allows the spatial distribution of an injected molecule to be imaged as well as its metabolic product or products. This review highlights the most significant molecules investigated to date in preclinical cancer models, either in terms of their demonstrated metabolism in vivo or the biological processes that they can probe. In particular, label exchange between hyperpolarized ¹³C‐labeled pyruvate and lactate, catalyzed by lactate dehydrogenase, has been shown to have a number of potential applications. Finally, techniques to image these molecules are also discussed as well as methods that may extend the lifetime of the hyperpolarized signal. Hyperpolarized magnetic resonance imaging and magnetic resonance spectroscopic imaging have shown great promise for the imaging of cancer in preclinical work, both for diagnosis and for monitoring therapy response. If the challenges in translating this technique to human imaging can be overcome, then it has the potential to significantly alter the management of cancer patients. Magn Reson Med, 2011. © 2011 Wiley‐Liss, Inc.     

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.     

非小细胞肺癌影像学分期研究进展

非小细胞肺癌是一种极为常见的癌症,早期非小细胞肺癌的影像学诊断尤为重要,对于该病诊断方法很多:普通CT、低剂量CT(LDCT)、核磁共振(MRI)、正电子发射计算机体层显像/x线计算机体层成像(PET/CT)、磁共振弥散加权成像(DWI),现就影像学技术在非小细胞肺癌分期中的应用现状及发展方向进行综述。     

Volumetric multishot echo-planar spectroscopic imaging.

Rapid volumetric magnetic resonance spectroscopic imaging (MRSI) is potentially of great relevance to the diagnosis and treatment of focal cerebral diseases such as cancer and epilepsy. A strategy for volumetric multishot echo-planar spectroscopic imaging (MEPSI) is described which allows whole-brain metabolite mapping in approximately 20 min. A multishot trajectory is used in both the spatial and temporal domains which reduces the accumulated phase during each echo train and tolerates conventional Fourier reconstruction without regridding. Also described is a generalized correction for phase discontinuities arising from the multishot acquisition of the time domain, which is independent of the spatial k-space trajectory and is therefore also applicable to multishot spiral MRSI. Whole-brain, lipid-suppressed MEPSI data were acquired from five normal subjects. The mean signal-to-noise ratios (SNRs) (+/-SE) for the n-acetylaspartate (NAA), choline (Cho), and creatine (Cr) maps across all subjects were 21.3 +/- 1.8, 11.7 +/- 0.6, and 9.2 +/- 0.6, respectively, with a computed voxel size of 2.33 ml.     

高血压脑病发病机制及相关MRI表现

高血压脑病（hypertensive encephalopathy ,HE）是内科较为常见的急症,常发生在重症高血压患者,其发病机制目前较为公认的主要有血管痉挛学说和脑血管自动调节功能崩溃学说。M RI在高血压脑病诊断、鉴别诊断、疗效观察及预后评定中有重要帮助,以下主要通过 M RI不同成像技术方法,包括常规平扫、弥散加权成像、磁共振血管成像（MRA）、磁共振波谱成像（MRS）、磁共振增强扫描、磁共振灌注成像（PWI）及磁敏感成像（SWI）,综合起来阐述该病各有何种表现,就其相关临床发病机制予以综述。     

Utility of positron emission tomography-magnetic resonance imaging in musculoskeletal imaging

Differentiation between neoplastic and nonneoplastic conditions magnetic resonance imaging (MRI) has established itself as one of the key clinical tools in evaluation of musculoskeletal pathology. However, MRI still has several key limitations which require supplemental information from additional modalities to complete evaluation of various disorders. This has led to the development hybrid positron emission tomography (PET)-MRI which is rapidly evolving to address key clinical questions by using the morphological strengths of MRI and functional information of PET imaging. In this article, we aim to review physical principles and techniques of PET-MRI and discuss clinical utility of functional information obtained from PET imaging and structural information obtained from MRI imaging for the evaluation of musculoskeletal pathology. More specifically, this review highlights the role of PET-MRI in musculoskeletal oncology including initial diagnosis and staging, treatment planning and post-treatment follow-up. Also we will review utility of PET-MRI in evaluating musculoskeletal infections (especially in the immunocompromised and diabetics) and inflammatory condition. Additionally, common pitfalls of PET-MRI will be addressed.     

MR脂肪定量技术在腰椎椎体骨髓脂肪含量评估中的研究进展

骨髓是人体内重要的造血和免疫器官,其内脂肪含量的变化对于疾病的精准诊断和疾病严重程度的分级至关重要。由于MRI对软组织和脂肪组织等具有较好的分辨力,因而对骨髓脂肪含量的定量评估起着不可替代的作用。就扩散加权成像、磁共振波谱成像、化学位移成像以及水脂分离技术等MR脂肪定量技术在腰椎椎体骨髓脂肪含量定量评估方面的应用及研究进展予以综述。     

肿瘤MR分子影像学研究进展

MR分子影像学以分子生物学为基础,借助MRI技术在活体状态下从分子、基因水平对肿瘤进行更早期、更特异性诊断与监测治疗效果。目前关于MR分子影像研究多集中于MR特异性分子探针的制备、肿瘤血管形成显像、报告基因显像、波谱显像等方面,由于MR具有精确的空间定位及功能成像等优势,因此在肿瘤分子影像研究中具有极大的发展潜力,将在21世纪肿瘤的诊断与治疗中发挥重要作用。MR分子影像学以分子生物学为基础,借助MRI技术在活体状态下从分子、基因水平对肿瘤进行更早期、更特异性诊断与监测治疗效果。目前关于MR分子影像研究多集中于MR特异性分子探针的制备、肿瘤血管形成显像、报告基因显像、波谱显像等方面,由于MR具有精确的空间定位及功能成像等优势,因此在肿瘤分子影像研究中具有极大的发展潜力,将在21世纪肿瘤的诊断与治疗中发挥重要作用。