Diffusion-weighted imaging of pancreatic cancer

Magnetic resonance imaging (MRI) is a reliable and accurate imaging method for the evaluation of patients with pancreatic ductal adenocarcinoma (PDAC). Diffusion-weighted imaging (DWI) is a relatively recent technological improvement that expanded MRI capabilities, having brought functional aspects into conventional morphologic MRI evaluation. DWI can depict the random diffusion of water molecules within tissues (the so-called Brownian motions). Modifications of water diffusion induced by different factors acting on the extracellular and intracellular spaces, as increased cell density, edema, fibrosis, or altered functionality of cell membranes, can be detected using this MR sequence. The intravoxel incoherent motion (IVIM) model is an advanced DWI technique that consent a separate quantitative evaluation of all the microscopic random motions that contribute to DWI, which are essentially represented by molecular diffusion and blood microcirculation (perfusion). Technological improvements have made possible the routine use of DWI during abdominal MRI study. Several authors have reported that the addition of DWI sequence can be of value for the evaluation of patients with PDAC, especially improving the staging; nevertheless, it is still unclear whether and how DWI could be helpful for identification, characterization, prognostic stratification and follow-up during treatment. The aim of this paper is to review up-to-date literature data regarding the applications of DWI and IVIM to PDACs.     

MR扩散加权成像在胰腺癌中的应用

胰腺癌是腹部最常见的恶性肿瘤,5年生存率不超过5%[1]或只有0.4%~2%.据报道,胰腺癌患者在过去30年几乎没有提高生存率[2].早期胰腺癌一般局限于实质内,直径<2 cm,无胰腺外浸润及淋巴结转移,其临床表现隐匿不易发现,有80%~90%的患者因为发现太迟以至于失去手术机会[3].所以对提高胰腺癌患者的生存率来说,快速准确的诊断显得尤为重要.     

Diffusion-weighted MR imaging of uterine endometrial cancer

PURPOSE: To determine the feasibility of diffusion-weighted (DW) MRI of uterine endometrial cancer and to investigate whether the apparent diffusion coefficient (ADC) values of endometrial cancer differ from those of normal endometrium and whether they differ according to the histologic grade of the tumor. MATERIALS AND METHODS: Study population included 18 consecutive females with surgically proven endometrial cancer and 12 females with pathologically confirmed normal endometrium in cervical cancer patients. Visual evaluation and ADC measurement were performed in endometrial cancer and normal endometrium. RESULTS: All endometrial cancer and the normal endometrium appeared hyperintense on DW images. The mean ADC value (10(-3) mm(2)/second) of endometrial cancer was 0.88 +/- 0.16, which was significantly lower (P < 0.01) than that of normal endometrium (1.53 +/- 0.10). The mean ADC value for each histologic grade was 0.93 +/- 0.16 (G1), 0.92 +/- 0.13 (G2), and 0.73 +/- 0.09 (G3). CONCLUSION: The present study showed that DW imaging is feasible in demonstrating uterine endometrial cancer and ADC measurement has a potential ability to differentiate between normal and cancerous tissue of the endometrium. The ADC values of endometrial cancers of higher grade show tendency to decrease compared to those of lower grade, although estimation of histologic grade based on ADC values seems difficult because of considerable overlap.     

前列腺癌的MR扩散成像初步研究

目的初步评价MR扩散成像(DWI)对前列腺癌的诊断可行性。方法28例前列腺癌患者及20例前列腺正常的对照组受试者行MR DWI检查,使用回波平面扩散张量成像序列,b值为1000s/mm2。测量正常前列腺外周带及前列腺癌区域的表观扩散系数(ADC)值。同时测量每位受检者膀胱区域的ADC值。结果48例中44例(91.7%)获得前列腺外周带和膀胱的ADC值。24例前列腺癌灶的ADC值为(0.35±0.06)×10-3mm2/s,20例正常前列腺外周带的ADC值为(1·35±0.30)×10-3mm2/s,前列腺癌灶较正常前列腺外周带ADC值低(t=11.99,P=0.00)。前列腺癌患者膀胱的ADC值为(1.27±0.21)×10-3mm2/s,对照组膀胱ADC值为(1.29±0.30)×10-3mm2/s,2组之间差异无统计学意义(t=1.15,P=0.48)。结论MR DWI可用于前列腺的检查。前列腺癌灶与正常前列腺外周带ADC值的差别有可能用于前列腺癌的鉴别诊断。     

Diffusion-weighted magnetic resonance imaging: a potential non-invasive marker of tumour aggressiveness in localized prostate cancer

AIM: To evaluate diffusion-weighted magnetic resonance imaging (DW-MRI) as a marker for disease aggressiveness by comparing tumour apparent diffusion coefficients (ADCs) between patients with low- versus higher-risk localized prostate cancer. METHOD: Forty-four consecutive patients classified as low- [n = 26, stageT1/T2a, Gleason score < or = 6, prostate-specific antigen (PSA)< 10 (group 1)] or intermediate/high- [n = 18, stage > or = T2b and/or Gleason score > or = 7, and/or PSA > 10 (group 2)] risk, who subsequently were monitored with active surveillance or started neoadjuvant hormone and radiotherapy, respectively, underwent endorectal MRI. T2-weighted (T2W) and DW images (5 b values, 0-800 s/mm(2)) were acquired and isotropic ADC maps generated. Regions of interest (ROIs) on T2W axial images [around whole prostate, central gland (CG), and tumour] were transferred to ADC maps. Tumour, CG, and peripheral zone (PZ = whole prostate minus CG and tumour) ADCs (fast component from b = 0-100 s/mm(2), slow component from b = 100-800 s/mm(2)) were compared. RESULTS: T2W-defined tumour volume medians, and quartiles were 1.2 cm(3), 0.7 and 3.3 cm(3) (group 1); and 6 cm(3), 1.3 and 16.5 cm(3) (group 2). There were significant differences in both ADC(fast) (1778 +/- 264 x 10(-6) versus 1583 +/- 283 x 10(-6) mm(2)/s, p = 0.03) and ADC(slow) (1379 +/- 321 x 10(-6) versus 1196 +/- 158 x 10(-6) mm(2)/s, p = 0.001) between groups. Tumour volume (p = 0.002) and ADC(slow) (p = 0.005) were significant differentiators of risk group. CONCLUSION: Significant differences in tumour ADCs exist between patients with low-risk, and those with higher-risk localized prostate cancer. DW-MRI merits further study with respect to clinical outcomes.     

Diffusion-weighted magnetic resonance imaging for monitoring prostate cancer progression in patients managed by active surveillance

Objectives

We studied patients managed by active surveillance to determine whether there was a difference over time in apparent diffusion coefficients (ADCs) derived from diffusion-weighted MRI in those who progressed to radical treatment (progressors, n = 17) compared with those who did not (non-progressors, n = 33).

Methods

50 consecutive patients (Stage T1/2a, Gleason grade ≤ 3+4, prostate-specific antigen (PSA) <15 ng ml^–1, <50% cores positive) were imaged endorectally (baseline and 1–3 years follow-up) with T₂ weighted (T₂W) and echo-planar diffusion-weighted MRI sequences. Regions of interest drawn on ADC maps with reference to the T₂W images yielded ADC_all (b = 0–800), ADC_fast (b = 0–300) and ADC_slow (b = 300–800) for whole prostate (minus tumour) and tumour (low signal-intensity peripheral zone lesion in biopsy-positive octant).

Results

Tumour and whole prostate ADC_all and ADC_fast were significantly reduced over time in progressors (p = 0.03 and 0.03 for tumours, respectively; p = 0.02 and 0.007 for the whole prostate, respectively). There were no significant changes in ADC over time in non-progressors. A 10% reduction in tumour ADC_all indicated progression with a 93% sensitivity and 40% specificity (A_z of receiver operating characteristic (ROC) curve = 0.68). Percentage reductions in whole prostate ADC_all, ADC_fast and ADC_slow were also significantly greater in progressors than in non-progressors (p = 0.01, 0.03 and 0.008, respectively).

Conclusion

This pilot study shows that DW-MRI has potential for monitoring patients with early prostate cancer who opt for active surveillance.Patients with early-stage prostate cancer may be offered active surveillance because of the indolent nature of the disease in many cases. This involves regular monitoring with prostate-specific antigen (PSA) levels and repeat biopsy. Repeat biopsy is invasive, sometimes poorly tolerated and carries a risk of morbidity. Non-invasive imaging methods are therefore being explored increasingly to provide biomarkers of prostate cancer behaviour.Although T₂ weighted (T₂W) MRI is the best way of visualising anatomical detail within the prostate, it has a sensitivity of just 60–76% for disease detection within the gland, with a specificity of around 55% [1, 2]. An increasingly useful addition to conventional T₂W MRI is the use of “apparent diffusivity” (tissue water incoherent displacement over distances of 1–20 μm) to develop image contrast. Diffusion-weighted (DW) MRI has been used in both clinical and research settings to detect and evaluate a variety of tumour types [3–7]. In prostate cancer, DW-MRI is proving useful in tumour detection [8]. The apparent diffusion coefficients (ADCs) that are derived by this technique provide quantitative information on the degree to which water diffusion, including the contributions made by microcapillary perfusion and true diffusion within the extracellular space, is restricted within tissues. ADCs are therefore directly associated with coherent microvessel density and cellularity [9] and with microcapillary perfusion (which contribute to a “fast” diffusion component), and with water movement within the extracellular or intracellular space over a shorter diffusion path (which contributes to a “slow” diffusion component). We have shown previously that significant differences in tumour ADCs exist between patients with low-risk and higher-risk localised prostate cancer, and that this is the case for both the fast and the slow components [10]. Changes in ADC components in the tumour and in the surrounding normal prostate tissue have not, however, been studied previously in relation to disease progression in low-risk patients managed by active surveillance. The aim of this pilot study of patients managed by active surveillance was therefore to use DW-MRI to establish whether the changes in tumour and whole prostate ADCs in patients who progressed to radical treatment differed over time from those in patients whose disease did not progress.     

Diffusion-weighted MR imaging for the evaluation of seminal vesicle invasion in prostate cancer: initial results

PURPOSE: To evaluate the accuracy of T2-weighted (T2WI) with diffusion-weighted imaging (DWI) as compared with T2WI alone for predicting seminal vesicle invasion (SVI) of prostate cancer. MATERIALS AND METHODS: A total of 30 patients with SVI and 136 patients without SVI who underwent prostate MR imaging were included in the study. MR images were analyzed retrospectively and independently by two readers for SVI on T2WI and T2WI with DWI using a 5-point scale. RESULTS: For predicting SVI, the specificity for T2WI with DWI and for T2WI was 97% and 87%, respectively, and accuracy was 96% and 87%, respectively, as determined by the experienced reader (P < 0.01). For the less experienced reader, the specificity for T2WI with DWI and for T2WI was 96% and 81%, respectively, and accuracy was 90% and 77%, respectively (P < 0.01). The diagnostic performance of the less experienced reader with T2WI with DWI led to significant improvement of the area under the receiver operating characteristic curve (Az) as compared with T2WI alone (Az = 0.815 versus 0.696; P < 0.01). Interreader agreement showed a substantial agreement (kappa = 0.613) for T2WI, and a substantial agreement (kappa = 0.737) for T2WI with DWI. CONCLUSION: For predicting SVI, T2WI with DWI showed a better diagnostic performance than T2WI alone. Additionally, the accuracy of the less experienced reader using T2WI with DWI showed a significant improvement as compared with T2WI alone.     

Diffusion-weighted imaging of normal and malignant prostate tissue at 3.0T

PURPOSE: To measure the apparent diffusion coefficient (ADC) of normal and malignant prostate tissue at 3.0T using a phased-array coil and parallel imaging, and determine the utility of ADC values in differentiating tumor from normal peripheral zone (PZ). MATERIALS AND METHODS: ADC values were calculated for 49 patients (tumor and PZ) with evidence of prostate cancer. Additionally, for nine asymptomatic volunteers, ADC values were determined for apparently normal central gland and PZ. A single-shot EPI diffusion-weighted imaging (DWI) technique with b = 0 and 500 seconds/mm2 was employed. RESULTS: ADC values were significantly lower for tumor (1.38 +/- 0.32 x 10(-3) mm2/second) than for patient PZ (1.95 +/- 0.50 x 10(-3) mm2/second, P < 0.001) and volunteer PZ (1.60 +/- 0.25 x 10(-3) mm2/second, P = 0.031). A considerable overlap of ADC values was noted between patient tissue types. CONCLUSION: DWI of the prostate at 3.0T in conjunction with a phased-array coil and parallel imaging allows ADC calculation of the prostate. ADC values were lower for tumors compared to normal-appearing PZ; however, there was considerable intersubject variability.     

Diffusion-weighted MRI after cryosurgery of the canine prostate. Magnetic resonance imaging

PURPOSE: To evaluate the acute lesion created by cryosurgery with diffusion-weighted magnetic resonance imaging (DWI). MATERIALS AND METHODS: The appearance of the acute cryolesion was evaluated in four canine prostates DWI after they were warmed to original body temperature. The prostates were excised, stained with triphenyl tetrazolium chloride (TTC), photographed, prepared for hematoxylin and eosin (H&E) staining, and examined under a light microscope. RESULTS: A marked decrease in apparent diffusion coefficient of 38% was evident in the center of the previously frozen tissue, but not in all of the previously frozen tissue. Histologic results confirm differences between the iceball core and the periphery of the iceball, which have markedly different imaging characteristics on DWI. CONCLUSION: The core of the previously frozen tissue has a reduced apparent diffusion coefficient (ADC) compared to the periphery of the previously frozen tissue and previously unfrozen tissue.     

正常子宫内膜和子宫内膜癌的扩散加权成像特点

目的探讨子宫内膜癌、子宫内膜不同周期及病理状态下的扩散加权成像的特点,研究表观扩散系数(ADC)及相对表观扩散系数(rADC)在子宫内膜癌的鉴别诊断应用价值。方法对29例子宫内膜癌,9例子宫内膜良性病变者和26例正常对照者行1.5T MRI检查并进行ADC值的测定(b值为800s/mm2)。闭孔内肌作参比部位,测量正常子宫内膜及内膜癌的rADC值,将不同组别ADC、rADC值相比较,进行统计学分析。结果子宫内膜癌ADC、rADC值分别为〔(0.96±0.22)×10-3 mm2/s、0.72±0.22〕,显著低于正常子宫内膜的ADC、rADC值〔(1.39±0.27)×10-3 mm2/s、1.02±0.22〕和子宫内膜良性病变ADC、rADC值〔(1.33±0.18)×10-3 mm2/s、1.02±0.28〕。萎缩期子宫内膜ADC、rADC值〔(1.62±0.37)×10-3 mm2/s、1.16±0.27〕显著高于增生期〔(1.29±0.14)×10-3 mm2/s、0.98±0.19〕和分泌期内膜〔(1.27±0.12)×10-3 mm2/s、0.94±0.12〕。结论 ADC有潜力鉴别子宫良性病变与子宫内膜癌,以闭孔内肌作为参比部位,所获得的rADC值可以很好的反映子宫内膜癌及正常子宫的扩散特征。     

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.     

前列腺扩散加权成像技术和诊断应用的研究进展

磁共振扩散加权成像（DWI）是目前唯一能够无创地检测活体组织的水扩散特性的改变,反映分子水平的病理生理过程的检查方法。就前列腺DWI技术及其在前列腺疾病诊断应用中的优势与限度,以及前列腺DWI技术的最新研究进展予以综述。     

前列腺扩散加权成像技术和诊断应用的研究进展

磁共振扩散加权成像(DWI)是目前唯一能够无创地检测活体组织的水扩散特性的改变,反映分子水平的病理生理过程的检查方法。就前列腺DWI技术及其在前列腺疾病诊断应用中的优势与限度,以及前列腺DWI技术的最新研究进展予以综述。     

Diffusion-weighted imaging of cerebritis

Restricted water diffusion has been used to distinguish pyogenic abscess from other rim-enhancing brain masses; however diffusion-weighted imaging of cerebral infection before capsule formation has rarely been described. We report a case of fungal cerebritis in which water diffusion was more restricted than that of normal contralateral brain and the measured diffusion coefficient was in the range of that reported for pyogenic brain abscess. In the proper clinical setting, cerebritis should be considered in the differential diagnosis of an ill-defined focal brain mass associated with markedly restricted water diffusion.     

Diffusion-weighted MR imaging and ADC measurement in normal prostate,benign prostatic hyperplasia and prostate carcinoma

Purpose

Our aim was to investigate the diffusion-weighted Imaging (DWI) appearance and apparent diffusion coefficient (ADC) values of normal prostatic gland, prostate carcinoma (PCa) and benign prostate hyperplasia (BPH) and to determine the utility of DWI in their characterization.

Materials and methods

During a period of 16 months, 40 consecutive patients, with elevated PSA level and 12 healthy volunteers with no clinical symptoms or history of prostate disease were prospectively evaluated with DWI of the prostate. MRI was performed using a 1.5T MR scanner equipped with a pelvic phased array coil. For anatomical imaging, T2W FSE in the three orthogonal planes, and T1WI in axial plane were obtained. DWI with b values of 0, 300, 500 and 800 s/mm² were performed in axial plane. The results were confirmed by TRUS-guided biopsy or prostatectomy.

Results

Patients ranged in age from 45 to 85 years (mean 66.6 ± 7.9 year). Twenty patients were confirmed to have BPH, whereas 20 patients had PCa. The mean and SD of ADC values for the peripheral zone (PZ), central gland (CG), BPH nodules and PCa were 1.839 ± 0.233, 1.469 ± 0.239, 1.359 ± 0.201 and 0.87 ± 0.13 respectively. The mean ADC value of PCa was significantly lower than that of CG, PZ, and BPH nodule, with p value <0.05.

Conclusion

DW MR imaging characteristics and ADC values can differentiate PCa and BPH. DWI with ADC may be used as a complementary method to conventional MRI in diagnosis of PCa and BPH.     

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.     

前列腺癌的多模态成像

前列腺癌是一种高度异质性疾病,目前治疗重点是识别与治疗预后不良的高危肿瘤,减少对惰性、低风险肿瘤的过度治疗。近年来,影像学在前列腺癌的探查、分期、治疗后评估和复发检测中的重要性逐渐增加。在不同的临床场景中,包括传统与功能检测在内的多种成像方式各有其优势与限制。该文概述目前应用于前列腺癌的影像学检测方法,从初期诊断到晚期...