磁共振扩散加权成像在肺癌中的临床应用

影像学检查在肺癌的诊断和分期中起到了至关重要的作用,目前电子计算机体层成像(CT)和正电子发射断层成像技术以及磁共振成像(MRI)已经被广泛的应用于肺癌的分期和疗效评估。其中MRI不仅能提供形态学信息,近年来发展起来的磁共振功能成像能提供更多的功能信息。磁共振扩散加权成像(Diffusion-weighted imaging,DWI)是最常应用于临床的磁共振功能成像序列。最初主要应用在神经系统,随着磁共振成像序列的不断发展以及软硬件的开发应用,其在腹部和盆腔的应用也日趋广泛,然而胸部DWI成像仍待普及和更多认识。本文就肺部DWI成像在良恶性病变鉴别、恶性肿瘤的筛查、分期、以及治疗疗效评估方面进行综述。     

磁共振波谱成像结合扩散加权成像在脑胶质瘤及脑转移瘤鉴别诊断中的意义

目的:评估磁共振波谱成像(Proton Magnetic Resonance Spectroscopy,1H-MRS)联合磁共振扩散加权成像(Diffusion Weighted Imaging,DWI)在鉴别脑胶质瘤及孤立的脑转移瘤中的作用。方法:应用3.0T磁共振扫描仪,对临床手术确诊及组织病理学诊断证实的49例脑肿瘤患者(35例多形性胶质母细胞瘤,14例脑转移瘤)进行常规磁共振成像、磁共振波谱成像及磁共振扩散加权成像,并并对获得的数据进一步测量瘤内及瘤周区的代谢比、N-乙酰天门冬氨酸(NAA)、胆碱(Cho)、肌酸(Cr)值以及表观弥散系数(ADC值),分析两肿瘤组之间不同参数的统计学差异。此外,我们研究了感兴趣区域(ROI)的大小对肿瘤区域的病变扩散性能潜在影响。结果:胶质母细胞瘤瘤周N-乙酰天门冬氨酸(NAA)、肌酸(Cr),胆碱(Cho)/Cr,Cho/NAA和r CBV显著高于颅内转移瘤(P0.05);ADC值在两肿瘤组之间无显著差异(P0.05)。结论:在瘤周区1H-MRS有助于鉴别胶质母细胞瘤与单发的脑转移瘤。在瘤内扩散性的定量特性依赖ROI大小的设置。     

Whole body diffusion for metastatic disease assessment in neuroendocrine carcinomas: comparison with OctreoScan(R) in two cases

ABSTRACT: Neuroendocrine tumor (NET) patients must be adequately staged in order to improve a multidisciplinary approach and optimal management for metastatic disease. Currently available imaging studies include somatostatin receptor scintigraphy, like OctreoScan(R), computed tomography (CT), scans and magnetic resonance imaging (MRI), which analyze vascular concentration and intravenous contrast enhancement for anatomic tumor localization. However, these techniques require high degree of expertise for interpretation and are limited by their availability, cost, reproducibility, and follow-up imaging comparisons. NETs significantly reduce water diffusion as compared to normal tissue. Diffusion-weighted imaging (DWI) in MRI has an advantageous contrast difference: the tumor is represented with high signal over a black normal surrounding background. The whole-body diffusion (WBD) technique has been suggested to be a useful test for detecting metastasis from various anatomic sites. In this article we report the use of DWI in MRI and WBD in two cases of metastatic pulmonary NET staging in comparison with OctreoScan(R) in order to illustrate the potential advantage of DWI and WBD in staging NETs.     

Differentiating Laryngeal Carcinomas from Precursor Lesions by Diffusion-Weighted Magnetic Resonance Imaging at 3.0 T: A Preliminary Study

Background

Diffusion-weighted magnetic resonance imaging (DWI) has been introduced in head and neck cancers. Due to limitations in the performance of laryngeal DWI, including the complex anatomical structure of the larynx leading to susceptibility effects, the value of DWI in differentiating benign from malignant laryngeal lesions has largely been ignored. We assessed whether a threshold for the apparent diffusion coefficient (ADC) was useful in differentiating preoperative laryngeal carcinomas from precursor lesions by turbo spin-echo (TSE) DWI and 3.0-T magnetic resonance.

Methods

We evaluated DWI and the ADC value in 33 pathologically proven laryngeal carcinomas and 17 precancerous lesions.

Results

The sensitivity, specificity, and accuracy were 81.8%, 64.7%, 76.0% by laryngostroboscopy, respectively. The sensitivity, specificity, and accuracy of conventional magnetic resonance imaging were 90.9%, 76.5%, 86.0%, respectively. Qualitative DWI analysis produced sensitivity, specificity, and accuracy values of 100.0, 88.2, and 96.0%, respectively. The ADC values were lower for patients with laryngeal carcinoma (mean 1.195±0.32×10⁻³ mm²/s) versus those with laryngeal precancerous lesions (mean 1.780±0.32×10⁻³ mm²/s; P<0.001). ROC analysis showed that the area under the curve was 0.956 and the optimum threshold for the ADC was 1.455×10⁻³ mm²/s, resulting in a sensitivity of 94.1%, a specificity of 90.9%, and an accuracy of 92.9%.

Conclusions

Despite some limitations, including the small number of laryngeal carcinomas included, DWI may detect changes in tumor size and shape before they are visible by laryngostroboscopy. The ADC values were lower for patients with laryngeal carcinoma than for those with laryngeal precancerous lesions. The proposed cutoff for the ADC may help distinguish laryngeal carcinomas from laryngeal precancerous lesions.     

乳腺癌功能磁共振成像与生物学预后因子的研究进展

乳腺癌已成为女性最为常见的恶性肿瘤,如何对乳腺癌进行早期诊断、合理化治疗及判断预后意义重大。雌激素受体(ER)、孕激素受体(PR)、Ki-67、人表皮生长因子受体2(HER-2)等免疫组化指标在判断乳腺癌临床类型、转移情况及预后等方面具有重要作用。随着功能磁共振的发展,氢质子磁共振波谱(1H-MRS)、动态增强磁共振成像(DCE-MRI)、扩散加权成像(DWI)等被越来越广泛的用于乳腺组织的检查。研究功能磁共振与乳腺癌预后因子的相关性,对乳腺癌的临床分型、治疗及预后等方面有一定的指导作用。本文就相关进展进行综述。     

Magnetic resonance imaging and spectroscopy of prostate cancer

Magnetic resonance imaging may improve the staging of prostate cancer compared with clinical evaluation alone, computerized tomography, or transrectal ultrasound, and it allows simultaneous and detailed evaluation of prostatic, periprostatic, and pelvic anatomy. Endorectal magnetic resonance imaging and magnetic resonance spectroscopic imaging (endoMRI/MRSI) allow better visualization of the zonal anatomy of the prostate and better delineation of tumor location, volume, and extent (stage). Metabolic criteria used to identify and localize prostate cancer with endoMRI/MRSI have been standardized, thus improving the accuracy of the examination and limiting interobserver variations in interpretation. Evidence is now emerging that endoMRI/MRSI may also be helpful in assessing response to prostate cancer treatment, most commonly with radiation and/or androgen-deprivation therapy.     

直肠癌MRI研究进展

MRI是目前直肠癌诊断、分期的首选影像学方法。在判断肿瘤对邻近器官、结构的浸润程度上具有明显优势,尤其是对有较高复发风险的低位肿瘤。常规MRI尤其是高分辨MRI能够清晰显示直肠相关解剖,结合扩散加权成像(Diffusion weighted imaging,DWI)通过确定肿瘤边界,直肠系膜有无受侵,淋巴结及远处转移情况,可以准确有效的进行术前诊断、分期;DWI有助于鉴别辅助治疗后失活与存活组织、筛选出辅助治疗有效的患者,在评估治疗后疗效、提示患者预后方面发挥重要作用,也为临床制定治疗方案提供依据。同时也发现准确进行淋巴结分期、鉴别复发仍然存在困难,需要在以后进一步探讨,提高评估的准确性。本文就近年来MRI在直肠癌术前评价、术后疗效评估、复发监测及表观弥散系数(Apparent diffusion coefficient,ADC)的应用做一综述。     

直肠癌MRI研究进展

MRI是目前直肠癌诊断、分期的首选影像学方法。在判断肿瘤对邻近器官、结构的浸润程度上具有明显优势,尤其是对有较高复发风险的低位肿瘤。常规MRI尤其是高分辨MRI能够清晰显示直肠相关解剖,结合扩散加权成像（Diffusion weighted imaging,DWI）通过确定肿瘤边界,直肠系膜有无受侵,淋巴结及远处转移情况,可以准确有效的进行术前诊断、分期;DWI有助于鉴别辅助治疗后失活与存活组织、筛选出辅助治疗有效的患者,在评估治疗后疗效、提示患者预后方面发挥重要作用,也为临床制定治疗方案提供依据。同时也发现准确进行淋巴结分期、鉴别复发仍然存在困难,需要在以后进一步探讨,提高评估的准确性。本文就近年来MRI在直肠癌术前评价、术后疗效评估、复发监测及表观弥散系数（Apparent diffusion coefficient,ADC）的应用做一综述。     

磁共振弥散加权成像及ADC值对鼻咽癌颅底放疗疗效的评价价值

目的:探讨磁共振弥散加权成像(DWI)及表观扩散系数(ADC)值在鼻咽癌颅底放疗中的临床价值。方法:收集我院于2013年6月~2014年6月复查的40例鼻咽癌患者,分别于放疗前及放疗结束12个月以后对所有患者行常规核磁共振成像(MRI)及DWI检查,测量放疗前、后ADC值,根据影像学检查以及临床诊断结果分为复发组(n=5)及未复发组(n=35)。结果:复发组放疗前ADC值为(0.797±0.031)×10~(-3)mm~2/s,与未复发组放疗前ADC值(0.805±0.028)×10~(-3)mm~2/s比较,差异无统计学意义(P0.05)。复发组放疗结束12个月以后ADC值为(1.097±0.091)×10~(-3)mm~2/s,与未复发组放疗结束12个月以后ADC值(1.705±0.128)×10~(-3)mm~2/s比较,差异有统计学意义(P0.05)。结论:DWI作为一种新兴的磁共振成像技术,对于鼻咽癌颅底放疗疗效的评价具有重要价值,通过DWI对ADC值的测量,可有效的预测患者预后是否良好。     

Preoperative Axillary Staging with 3.0-T Breast MRI: Clinical Value of Diffusion Imaging and Apparent Diffusion Coefficient

The axillary staging in newly diagnosed breast cancer is under major evolution. The aims of this study were to define the diagnostic performance of 3.0-T diffusion-weighted imaging (DWI) in the detection of axillary metastases in newly diagnosed breast cancer, to assess apparent diffusion coefficients (ADCs) for histopathologically confirmed metastatic lymph nodes in a clinical setting. Altogether 52 consecutive breast cancer patients underwent magnetic resonance imaging and DWI in addition to axillary ultrasound. ADCs of axillary lymph nodes were analysed by two breast radiologists and ultrasound-guided core biopsies were taken. In a separate reading by one radiologist two types of region of interests were used for a smaller group of patients. Altogether 56 axillae (121 lymph nodes) were included in the statistical analysis. Metastatic axillae (51.8%) had significantly lower ADCs (p<0.001). Mean ADCs were 0.663–0.676 x 10^-3 mm²/s for the histologically confirmed metastatic LNs and 1.100–1.225 x 10^-3 mm²/s for the benign. The sensitivity, specificity, and accuracy of DWI were 72.4%, 79.6%, and 75.9%, respectively with threshold ADC 0.812 x 10^-3 mm²/s. Region of interest with information on the minimum value increased the diagnostic performance (area under the curve 0.794 vs. 0.619). Even though ADCs are significantly associated with histopathologically confirmed axillary metastases the diagnostic performance of axillary DWI remains moderate and ultrasound-guided core biopsies or sentinel lymph node biopsies cannot be omitted.     

Comparison of Two Mathematical Models of Cellularity Calculation

OBJECT: Nowadays, there is increasing evidence that functional magnetic resonance imaging (MRI) modalities, namely, diffusion-weighted imaging (DWI) and dynamic-contrast enhanced MRI (DCE MRI), can characterize tumor architecture like cellularity and vascularity. Previously, two formulas based on a logistic tumor growth model were proposed to predict tumor cellularity with DWI and DCE. The purpose of this study was to proof these formulas. METHODS: 16 patients with head and neck squamous cell carcinomas were included into the study. There were 2 women and 14 men with a mean age of 57.0 ± 7.5 years. In every case, tumor cellularity was calculated using the proposed formulas by Atuegwu et al. In every case, also tumor cell count was estimated on histopathological specimens as an average cell count per 2 to 5 high-power fields. RESULTS: There was no significant correlation between the calculated cellularity and histopathologically estimated cell count by using the formula based on apparent diffusion coefficient (ADC) values. A moderate positive correlation (r=0.515, P=.041) could be identified by using the formula including ADC and V_e values. CONCLUSIONS: The formula including ADC and V_e values is more sensitive to predict tumor cellularity than the formula including ADC values only.     

Promising techniques for breast cancer detection,diagnosis, and staging using non-ionizing radiation imaging techniques

Traditional imaging for the diagnosis and staging of breast cancer has relied on the tissue morphology of cancers in the background of normal patterns of fibroglandular breast tissue. X-ray mammography and ultrasound have been the primary modalities for the diagnosis and the work-up of breast cancer. New modalities have been validated including magnetic resonance imaging (MRI) and positron emission tomography (PET). New pulse sequences in MRI combined with contrast enhancement kinetic perfusion curves have greatly enhanced detection of mammographically occult cancers. New modalities on the horizon include optical imaging, exploiting again the differential perfusion properties of cancers in a background of normal glandular tissue. Even more specificity can be ach eved with the addition of ductal or intravenous introduction of optical probes specific to tumor associated antigens such as the HER-2/neu receptor in aggressive breast cancers. Quantum dots and other fluorescent dyes coupled to peptides or other probes will greatly enhance our ability to detect cancers earlier and without ionizing radiation.     

Clinical aspects for the use of DNA image cytometry in detection of bladder cancer: a valuable tool?

The employment of DNA flow or image cytometry for oncological diagnostic procedures is favored because of its high correlation to tumor biological behavior. Prognostic statements and therapeutic strategies therefore are based on the high validity of DNA cytometric measurements. Using 151 bladder washings from patients suspected of bladder cancer for this study, we examined the clinical value of various common methods of DNA single cell (SCI) and stemline interpretations (SLI). Comparing the specificity and sensitivity of DNA image cytometry in detection of bladder tumors, we found 81 and 52%, respectively, for SCI of Boecking, 84 and 45% for SLI of Boecking, 61 and 58% for SLI of Fu, and 82 and 40% for conventional stemline interpretation. To improve diagnostic and prognostic validity of DNA image cytometry, we designed our own method of interpretation. In consequence, we identified six single DNA parameters out of all recorded measurements that correlated most to histopathological grading (G1-G3). Creating reference values at random and rating by points, we used a cytometric grading system for ranking. In detection of bladder cancer specificity and sensitivity ultimately arrived at almost 70% in application of our method. Thus, by this study, we were able to show that sensitivity of DNA examination can be increased by combining various DNA parameters. Apart from our own scheme, the discrepancy in interpretation of DNA image cytometry does not allow us to recommend this procedure as the only diagnostic in detection of bladder cancer. However, in regard to prognostic statements, particularly tumor biological behavior, DNA image cytometry appears to be useful.     

Uninterpretable Dynamic Susceptibility Contrast-Enhanced Perfusion MR Images in Patients with Post-Treatment Glioblastomas: Cross-Validation of Alternative Imaging Options

Purpose

The purpose of this study was to evaluate the accuracy of diffusion-weighted imaging (DWI) and dynamic contrast-enhanced (DCE) perfusion MR imaging for distinguishing tumor recurrence from post-treatment effect as alternatives to dynamic-susceptibility contrast-enhanced (DSC) perfusion MR imaging when the DSC image is uninterpretable.

Materials and Methods

This retrospective study was approved by our institutional review board. Seventy one post-treatment glioblastoma patients who showed enlarged contrast-enhancing lesions on follow-up MR images after concurrent chemoradiotherapy and uninterpretable DSC images for corresponding enhancing lesions, underwent additional DWI and DCE MR imaging. The primary outcome was the frequency of interpretable DWI and DCE MR cases in these 71 patients. The secondary outcome was the area under the receiver operating characteristic curve (AUC) of DWI and DCE imaging parameters for distinguishing tumor recurrence from post-treatment effect in selected patients with interpretable DWI and DCE images. The imaging parameters were quantified as 10% cumulative histogram cutoff of apparent diffusion coefficient (ADC10) and 90% cumulative histogram cutoff of initial area under the time signal intensity curve (IAUC90). The AUCs were cross-validated by using leave-one-out method.

Results

Of the 71 patients, the uninterpretable DSC images were associated with treatment-related hemorrhage within the corresponding enhancing lesions (n = 54, 76.1%) and a near skull base location (n = 17, 23.9%). The frequencies of interpretable DWI and DCE image were 51 (71.8%) and 59 (83.1%) of the 71 cases with uninterpretable DSC images, respectively. Of the 45 selected patients with interpretable DWI and DCE images, the combination of DWI with DCE imaging showed a superior diagnostic performance than DWI or DCE imaging alone for differentiating tumor recurrence from post-treatment effect (cross-validated AUC: 0.78 versus 0.55 and 0.73 for reader 1; cross-validated AUC: 0.78 versus 0.53 and 0.75 for reader 2, respectively). Cross-validated accuracy of the single and combined imaging parameters also showed the highest for the combination of DWI with DCE MR imaging (72.9% for reader 1; 72.5% for reader 2) and the lowest for DWI alone (54.0% for reader 1; 56.4% for reader 2). Inter-reader agreement for DCE imaging was higher than that for DWI (intraclass correlation coefficient: 0.95 versus 0.87).

Conclusion

DCE MR imaging could be a superior and more reproducible imaging biomarker than DWI for differentiating tumor recurrence from post-treatment effect in patients with post-treatment glioblastoma when DSC MR images are not interpretable.     

磁共振成像对非小细胞肺癌的诊断价值分析

目的:探讨磁共振成像(Magnetic resonance imaging,MRI)对非小细胞肺癌的诊断价值。方法:选择2016年9月-2019年4月南京医科大学附属脑科医院(胸科院区)放射科收治的肺部结节患者74例,包括病理证实为肺部良性病变54例(良性组)和非小细胞肺癌20例(肺癌组)。所有患者都给予常规MRI、增强MRI与磁共振扩散加权成像(Diffusion weighted imaging,DWI),记录影像学特征并评估其诊断价值。结果:肺癌组的病灶形态、边缘等MRI特征与良性组对比差异无统计学意义(P0.05)。在b值=0、600、800、1000 s/mm~2条件下,肺癌组的病灶表观扩散系数(Apparent diffusion coefficient,ADC)值都显著低于良性组(P0.05)。肺癌组的病灶MRI增强Ⅰ型+Ⅱ型比例显著高于良性组(P0.05)。MRI鉴别诊断非小细胞肺癌的敏感性与特异性为98.1%和94.4%。结论:MRI用于非小细胞肺癌的诊断能反映病灶组织的血流动力学与水分子活动状况,具有较高的诊断敏感性与特异性。     

动态对比增强磁共振成像在鼻咽癌分期中的应用价值

目的:分析动态对比增强磁共振成像(DCE-MRI)在鼻咽癌分期中的应用价值。方法:选取2016年6月至2018年4月我院经病理证实的初诊鼻咽癌患者104例为研究对象,均行DCE及扩散加权成像(DWI)检查,比较不同鼻咽癌分期患者的DCE-MRI定量参数[转运常数(Ktrans)、血管外细胞外间隙体积百分数(Ve)、速率常数(Kep)、容积分数(f PV)]及表观扩散系数(ADC)值,分析各DCE-MRI参数与临床分期的相关性,并评估DCE-MRI对鼻咽癌分期的诊断价值。结果:随总分期增加,鼻咽癌患者Ktrans、Ve增加,且Ve随T分期增加而增加,M1分期者Ktrans、Ve大于M0分期者(P0.05),不同N分期患者各DCE-MRI参数比较差异无统计学意义(P0.05),Kep、f PV在各分期中比较差异也无统计学意义(P0.05);随总分期增加,鼻咽癌患者ADC值减少(P0.05);Spearman相关分析发现,鼻咽癌患者Ktrans与总分期、M分期呈正相关,Ve与总分期、T分期呈正相关,ADC值与总分期呈负相关(P0.05);各参数中,Ktrans诊断鼻咽癌总分期的曲线下面积(AUC)最大,为0.925,Ktrans诊断鼻咽癌早期(Ⅱ期)、晚期(Ⅲ期与Ⅳ期)的AUC分别为0.909、0.921,均较ADC(AUC=0.864、0.815)高。结论:DCE-MRI在鼻咽癌临床分期中有较高应用价值,其中Ktrans的诊断效能最好且高于DWI诊断,肿瘤分期越高,Ktrans越大,可作为肿瘤分期的一个指标。     

1.5T磁共振不同序列用于检出妇科肿瘤盆腔淋巴结转移的比较

目的:比较1.5T磁共振(MRI)不同序列条件下对妇科肿瘤盆腔淋巴结转移的检出情况,探讨最佳检出序列条件。方法:选取2015年5月-2017年5月初诊为卵巢癌、宫颈癌、子宫内膜癌的患者78例作为研究对象,均行盆腔淋巴结清扫术。所有患者术前均行T1加权序列(T1WI)、T2加权序列(T2WI)、增强扫描(T1WI+C)、弥散加权成像(DWI)检查,记录每个序列检查条件下检出的盆腔转移淋巴结个数及分布。以病理结果作为判断的"金标准"进行对比。结果:对比病理检查结果,应用DWI序列对妇科肿瘤盆腔淋巴结转移的检出率(95.8%)显著高于T2WI-MRI序列(85.8%)和T1WI-MRI序列(75.0%)(P0.05);DWI序列与T1WI+C序列(90.8%)相比差异无统计学意义(P0.05);DWI阈值法与DWI短径法相比,淋巴结的检出率差异无统计学意义(P0.05)。结论:应用1.5T磁共振检查妇科肿瘤盆腔淋巴节转移时,采用DWI序列扫描对于转移淋巴结的具有较高的检出率,显著优于其他序列扫描;在进行阳性淋巴结判断中,ADC阈值法和短径法均可选用。     

An unusual case of retrovesical ectopic prostate tissue accompanied by primary prostate cancer

ABSTRACT: We report an unusual case of retrovesical ectopic prostate tissue in a 73-year-old man with primary prostate cancer. The man's prostate-specific antigen was 24.66 ng/ml. Transabdominal ultrasonography, pelvic computed tomography and pelvic magnetic resonance imaging demonstrated a heterogeneous 8.5 x 8.0 x 7.0 cm mass in contact with the posterior wall of the urinary bladder. The patient underwent a retropubic radical prostatectomy and resection of the tumor. Pathological examination of the prostate revealed a prostatic adenocarcinoma, Gleason score of 4 + 5 = 9, and the retrovesical tumor was confirmed to be a benign prostate tissue.     

Magnetic Resonance Imaging Assessment of Effective Ablated Volume following High Intensity Focused Ultrasound

Under magnetic resonance (MR) guidance, high intensity focused ultrasound (HIFU) is capable of precise and accurate delivery of thermal dose to tissues. Given the excellent soft tissue imaging capabilities of MRI, but the lack of data on the correlation of MRI findings to histology following HIFU, we sought to examine tumor response to HIFU ablation to determine whether there was a correlation between histological findings and common MR imaging protocols in the assessment of the extent of thermal damage. Female FVB mice (n = 34), bearing bilateral neu deletion tumors, were unilaterally insonated under MR guidance, with the contralateral tumor as a control. Between one and five spots (focal size 0.5 × 0.5 × 2.5 mm³) were insonated per tumor with each spot receiving approximately 74.2 J of acoustic energy over a period of 7 seconds. Animals were then imaged on a 7T MR scanner with several protocols. T1 weighted images (with and without gadolinium contrast) were collected in addition to a series of T2 weighted and diffusion weighted images (for later reconstruction into T2 and apparent diffusion coefficient maps), immediately following ablation and at 6, 24, and 48 hours post treatment. Animals were sacrificed at each time point and both insonated/treated and contralateral tumors removed and stained for NADH-diaphorase, caspase 3, or with hematoxylin and eosin (H&E). We found the area of non-enhancement on contrast enhanced T1 weighted imaging immediately post ablation correlated with the region of tissue receiving a thermal dose CEM43 ≥ 240 min. Moreover, while both tumor T2 and apparent diffusion coefficient values changed from pre-ablation values, contrast enhanced T1 weighted images appeared to be more senstive to changes in tissue viability following HIFU ablation.     

Non-Gaussian Analysis of Diffusion Weighted Imaging in Head and Neck at 3T: A Pilot Study in Patients with Nasopharyngeal Carcinoma

Purpose

To technically investigate the non-Gaussian diffusion of head and neck diffusion weighted imaging (DWI) at 3 Tesla and compare advanced non-Gaussian diffusion models, including diffusion kurtosis imaging (DKI), stretched-exponential model (SEM), intravoxel incoherent motion (IVIM) and statistical model in the patients with nasopharyngeal carcinoma (NPC).

Materials and Methods

After ethics approval was granted, 16 patients with NPC were examined using DWI performed at 3T employing an extended b-value range from 0 to 1500 s/mm². DWI signals were fitted to the mono-exponential and non-Gaussian diffusion models on primary tumor, metastatic node, spinal cord and muscle. Non-Gaussian parameter maps were generated and compared to apparent diffusion coefficient (ADC) maps in NPC.

Results

Diffusion in NPC exhibited non-Gaussian behavior at the extended b-value range. Non-Gaussian models achieved significantly better fitting of DWI signal than the mono-exponential model. Non-Gaussian diffusion coefficients were substantially different from mono-exponential ADC both in magnitude and histogram distribution.

Conclusion

Non-Gaussian diffusivity in head and neck tissues and NPC lesions could be assessed by using non-Gaussian diffusion models. Non-Gaussian DWI analysis may reveal additional tissue properties beyond ADC and holds potentials to be used as a complementary tool for NPC characterization.