DWI及ADC值在脊柱转移瘤诊断中的应用

目的 :探讨DWI及ADC值在脊柱转移瘤诊断中价值。方法 :收集我院临床确诊的脊柱转移瘤30例脊柱转移组,脊柱良性病变25例(良性病变组)。55例均行常规矢状位、横轴位及DWI扫描,b值取0、800 s/mm2,分别测量得2组病变ADC值。主观评价并比较2组的DWI病灶信号强度。采用ROC曲线,获得最佳DWI及ADC值界值,以及诊断敏感度、特异度,两者联合指标的敏感度、特异度。结果:椎体病变T1WI呈低信号或以低信号为主的混杂信号,T2WI脂肪抑制后为高信号、混杂高信号。良性病变组DWI以稍高信号为主(17/25),脊柱转移瘤组DWI以高信号为主(24/30),2组差异有统计学意义(Z=4.477,P0.001)。测得平均ADC值:脊柱转移瘤组为(0.843±0.189)×10-3mm2/s;良性病变组为(1.204±0.184)×10-3mm2/s,2组差异有统计学意义(t=7.131,P0.001)。当病变DWI为稍高信号,鉴别脊柱良恶性病变ROC曲线下面积为0.812,敏感度80%,特异度80%;2组ADC值鉴别脊柱良恶性病变ROC曲线下面积为0.920,最佳临界值为0.947×10-3mm2/s,敏感度76.67%,特异度96%。DWI病变信号为稍高及高信号,ADC值≤0.947 4×10-3mm2/s,满足其中之一诊断为恶性病变的诊断敏感度90%,特异度80%。结论:常规MRI结合DWI及ADC值对诊断脊柱转移瘤具有重要价值。     

Quantitation of T2 lesion load in patients with multiple sclerosis: a novel semiautomated segmentation technique

RATIONALE AND OBJECTIVES: The authors designed a segmentation technique that requires only minimal operator input at the initial and final supervision stages of segmentation and has computer-driven segmentation as the primary determinant of lesion boundaries. The technique was applied to compute total T2-hyperintense lesion volumes in patients with multiple sclerosis (MS). A semi-automated segmentation technique is presented and shown to have a test-retest reliability of <5%. MATERIALS AND METHODS: The method used a single segmented section with MS lesions. A probabilistic neural net performed segmentation into four tissue classes after supervised training. This reference section was deconstructed into the entire set of possible 4 x 4-pixel subregions, which was used to segment all-brain sections in steps of 4 x 4-pixel, adjacent image blocks. Intra- and interimage variabilities were tested by using 3-mm-thick, T2-weighted, dual-echo, spin-echo MR images from five patients, each of whom was imaged twice on the same day. Five different reference sections and three temporally separated. training sessions involving the same reference section were used to test the segmentation technique. RESULTS: The coefficient of variation ranged from 0.013 to 0.068 (mean +/- standard deviation, 0.037 +/- 0.039) for results from five different reference sections for each brain and from 0.007 to 0.037 (mean, 0.027 +/- 0.021) for brains segmented with the same reference section on three temporally separated occasions. Test-retest (intra-imaging) reliability did not exceed 5% (except for a small lesion load of 1 cm3 in one patient). Interimaging differences were approximately 10%. CONCLUSION: The segmentation technique yielded intra-imaging variabilities (2%-3%, except for very small MS lesion loads) that compare favorably with previously published results. New repositioning techniques that minimize imaging-repeat imaging variability could make this approach attractive for resolving MS lesion detection problems.     

Magnetic resonance (MR) differential diagnosis of breast tumors using apparent diffusion coefficient (ADC) on 1.5‐T

To review the published reports concerning the apparent diffusion coefficient (ADC) value evaluation for the differentiation between malignant and benign breast tumors, articles were searched with the inclusion criteria: (a) a 1.5‐T unit was used; (b) the diagnostic criteria were clearly stated; (c) diffusion‐weighted images (DWIs) were obtained, and ADC value was calculated; (d) ADC values of breast tumors were reported with mean ± standard deviation (SD). Meta‐analysis from 12 articles revealed that the pooled sensitivity and specificity were 0.89 (95% confidence interval [CI], 0.85–0.91) and 0.77 (95% CI, 0.69–0.84), respectively, and that only the maximum b factor correlated with the mean ADC values of malignant and benign tumors, and the noncancerous breast tissue (P< 0.05,P < 0.01,P< 0.05, respectively). In conclusion, ADC evaluation is useful for the differentiation between malignant and benign breast tumors. J. Magn. Reson. Imaging 2009;30:249–255. © 2009 Wiley‐Liss, Inc.     

Diagnostic value of apparent diffusion coefficient (ADC) in assessment of pituitary macroadenoma consistency

Background

Pre-operative assessment of macroadenoma consistency is helpful for proper surgical planning. DWI correlated with ADC value adding information about the tumor consistency that cannot be obtained with cMRI.

Patients and methods

Thirty patients with pituitary adenomas were examined by MRI including cMRI (conventional magnetic resonance) and DWI (diffusion weighted imaging) with ADC value measurement. Diagnosis was correlated with intra-operative finding and histopathology.

Results

According to ADC values, we classified our cases into three groups of macroadenoma consistency; Group A (Soft tumors = 22/30) had mean ADC value of 0.482 × 10⁻³ mm²/s, Group B (intermediate consistency = 5/30) had mean ADC value of 0.730 × 10⁻³ mm²/s and Group C (Firm adenomas = 3/30) with mean ADC value of 0.992 × 10⁻³ mm²/s. Diagnostic overlap was detected in one case of group A and 2 cases of group B. The sensitivity, specificity, PPV, NPD and accuracy of ADC values were 80%, 88%, 57.1% and 95.7% at ADC 0.7 × 10⁻³ mm²/s and 100%, 88%, 62.5% and 100% at ADC 0.6 × 10⁻³ mm²/s respectively.

Conclusion

DWI that correlated with ADC value should be included in routine pre-operative assessment of macroadenoma consistency. We recommend a cut off value of 0.6 × 10⁻³ mm²/s, for accurate discrimination of the intermediate/soft macroadenomas from firm adenomas.     

Diffusely elevated cerebral choline and creatine in relapsing-remitting multiple sclerosis.

It is well known that multiple sclerosis (MS) pathogenesis continues even during periods of clinical silence. To quantify the metabolic characteristics of this activity we compared the absolute levels of N-acetylaspartate (NAA), creatine (Cr), and choline (Cho) in the normal-appearing white matter (NAWM) between relapsing-remitting (RR) MS patients and controls. Metabolite concentrations were obtained with 3D proton MR spectroscopy at 1.5 T in a 480 cm(3) volume-of-interest (VOI), centered on the corpus callosum of 11 MS patients and 9 matched controls. Gray/white-matter/cerebral-spinal-fluid (CSF) volumes were obtained from MRI segmentation. Patients' average VOI tissue volume (V(T)), 410.8 +/- 24.0 cm(3), and metabolite levels, NAA = 6.33 +/- 0.70, Cr = 4.67 +/- 0.52, Cho = 1.40 +/- 0.17 mM, were different from the controls by -8%, -9%, +22% and +32%. The Cho level was the only single metric differentiating patients from controls at 100% specificity and >90% sensitivity. Diffusely elevated Cho and Cr probably reflect widespread microscopic inflammation, gliosis, or de- and remyelination in the NAWM. Both metabolites are potential prognostic indicators of current disease activity, preceding NAA decline and atrophy.     

Clinical use of H MR spectroscopy in assessment of relapsing remitting and secondary progressive multiple sclerosis

Background

Conventional MRI has a limited ability to provide specific information about axonal pathology in MS, recently, MRI spectroscopy used for assessment of the axonal loss even in normal appearing white matter.

Objective

To assess the axonal degeneration in plaques and normal appearing white matter in patients with relapsing remitting MS and secondary progressive MS, and correlate their clinical disability using expanded disability status scale (EDSS) score with H¹ MRS abnormalities.

Patients and methods

Thirty-two MS patients (20 RRMS, 12 SPMS) and 20 controls were subjected to thorough history taking, clinical examination with special attention to: age at first symptoms, disease duration and the EDSS score. MRS was performed in order to map N-acetylaspartate (NAA), choline (Cho) and creatine (Cr).

Results

In SPMS, the NAA/Cr ratio and absolute concentrations for NAA in MS plaques and NAWM were significantly reduced compared to RRMS and to controls, also, significant relation with this metabolite values and clinical disability using EDSS score.

Conclusion

In SPMS patients group there were significant reduction in the levels of NAA in both plaques and NAWM compared to RRMS and control groups, moreover significant correlation of NAA reduction in the plaques of both groups related to clinical disability and disease progression.     

Diagnostic utility of diffusion‐weighted MR imaging and apparent diffusion coefficient value for the diagnosis of adrenal tumors

Purpose

To determine the utility of diffusion‐weighted MR imaging (DWI) for the diagnosis of adrenal tumors.

Materials and Methods

Forty‐two patients (24 men and 18 women; age, 61.5 ± 12.7 years old; range, 34–86 years) with 43 adrenal tumors (11 functioning cortical adenomas, 20 nonfunctioning cortical adenomas, 7 metastatic tumors, and 5 pheochromocytomas) were retrospectively investigated. DWIs were obtained by single‐shot spin‐echo type echo‐planar imaging sequence (1.5 Tesla [T]; TR = 8000 ms, TE = 72, b‐factor = 0 and 1000 s/mm²), and apparent diffusion coefficient (ADC) value was calculated. Chemical shift images were obtained by gradient echo sequence (TR = 161, TE = 2.38 [out‐of‐phase, OP] and 4.76 [in‐phase, IP], FA = 60), and the signal intensity index (SII; [IP‐OP]/IP *100%) was calculated.

Results

There was no difference in ADC values between adenomas (1.09 ± 0.29*10^?3 mm²/s; range, 0.52–1.64) and metastatic tumors (0.85 ± 0.26*10^?3; 0.51–1.23; p = 0.14). Pheochromocytomas showed the higher mean ADC value (1.59 ± 0.34*10^?3; 1.04–1.96) compared with those of adenomas or metastatic tumors (P < 0.05 and P < 0.005, respectively). The mean SII of adenomas (62.1 ± 17.9%; 14.5–88.4) was significantly higher than those of pheochromocytomas (4.0 ± 10.0%; ?19.6–3.3; P < 0.005) or metastatic tumors (?1.5 ± 11.7%; ?18.3–8.2; P < 0.01). There was no correlation between ADC values and SII.

Conclusion

Although pheochromocytomas showed higher ADC values, we did not find that ADC value had diagnostic utility for differentiating adenomas and metastatic tumors. J. Magn. Reson. Imaging 2009;29:112–117. © 2008 Wiley‐Liss, Inc.

     

Solitary fibrous tumor of the pleura: apparent diffusion coefficient (ADC) value and ADC map to predict malignant transformation

Solitary fibrous tumors (SFTs) of the pleura are rare soft-tissue tumors that are presumed to be of mesenchymal origin. Most SFTs are histologically benign, but up to 20% of SFTs may be malignant. In addition, malignant transformation may occur within histologically benign SFTs, though it is rare. However, it is difficult to diagnose malignant SFTs of the pleura by means of conventional computed tomography and magnetic resonance imaging (MRI). In this article we present the first case of malignant SFT of the pleura in an 81-year-old man in which the apparent diffusion coefficient (ADC) value and ADC map based on diffusion-weighted MRI were very useful for identifying malignant transformation.     

Analysis of MTR histograms in multiple sclerosis using principal components and multiple discriminant analysis.

Magnetization transfer ratio (MTR) histograms have the potential to characterize subtle diffuse changes in multiple sclerosis (MS) and other white matter disease. A new method is described which gives improved correlation with the Expanded Disability Status Scale (EDSS). Classification of individual subjects into normal and MS subgroups is shown. Principal component analysis (PCA) and multiple discriminant analysis (MDA) are shown to give results superior to methods of MTR histogram analysis using traditional features such as peak height and peak location. Scatterplots confirm the improved separation between groups achieved using the MDA score. The histogram analysis provides a comparison of two classification approaches, based on PCA and MDA, to recognize differences between normal controls and the four different subgroups of MS disease (and all MS patients). Multiple linear regression of these PCs vs. EDSS established an MR-based measure of disease. Using a central 60-mm slab of brain tissue, the success rate of binary classification between control and MS subgroups using MDA was 75-95%, depending on which two groups were being compared. Multiple regression analysis of EDSS with the first three PCs as independent variables was significant (r = 0.83 for secondary progressive MS, and r = 0.80 for all MS patients).     

Predictive value of pre-treatment apparent diffusion coefficient (ADC) in radio-chemiotherapy treated head and neck squamous cell carcinoma

Objective

This study aimed at evaluating the role of “baseline” apparent diffusion coefficent (ADC), in patients affected by head and neck cancer treated with radio-chemotherapy, as a potential marker of response to therapy.

Methods

Fifty-seven patients underwent pretreatment ADC maps. Minimum, maximum, and medium ADC were computed. Age, dose, treatment time, and ADC values were compared between the two groups (Group 1: local control; Group 2: relapse/persistence of disease) using the Student t test two-tailed unpaired. Two-tailed Fischer exact test was used to compare T stage, N stage, grading and type of treatment between two groups. We have analyzed the receiver operating characteristic (ROC) of statistically significant variables.

Results

In patients with local control, values of pre-treatment medium and minimum ADC were lower than ADC values of patients with persistent or recurrent disease, with values, respectively, of 0.83 ± 0.02 × 10^–3 mm²/s and 0.59 ± 0.02 × 10^–3 mm²/s (vs 0.94 ± 0.05 × 10^–3 mm²/s and 0.70 ± 0.05 × 10^–3 mm²/s). ROC curve analysis displayed statistical significance as regarding the medium ADC value, showing a sensitivity of 50% and a specificity of 84.8%. ROC analysis of the values minimum ADC showed a sensitivity of 42.9% and specificity of 87.9%.

Conclusion

The value of the ADC pre-treatment of patients with local control of the disease is lower than that of patients with persistent disease or recurrence.

     

Added value of double inversion recovery magnetic resonance sequence in detection of cortical and white matter brain lesions in multiple sclerosis

Objective

The aim of this study was to evaluate the value of double inversion recovery (DIR) magnetic resonance (MR) sequence in the detection of brain cortical and white matter lesions in multiple sclerosis (MS).

Patients and methods

Fifteen patients with remitting relapsing MS were included in this study. Imaging was performed on a 1.T MR system using DIR, fluid-attenuated inversion-recovery (FLAIR), and T2-weighted image (T2WI) sequences. The sensitivity of DIR was compared with the corresponding sensitivity of FLAIR and T2WI sequences. The contrast between lesions and normal-appearing gray matter (NAGM), normal-appearing white matter (NAWM), and cerebrospinal fluid (CSF) was determined for all sequences.

Results

DIR showed significantly more MS lesion load overall when compared to T2WI or FLAIR. Significantly higher number of lesions was seen in the supra- and infratentorial locations. DIR detected higher periventricular white matter lesions when compared to FLAIR, but did not detect significantly higher lesions when compared to T2WI. Significantly higher deep white matter, juxtacortical, and intracortical lesions were seen on DIR when compared to both T2WI and FLAIR. The image contrast measurements between the MS lesions and the NAWM in all anatomical locations were significantly higher in DIR sequence compared to both T2WI and FLAIR sequences. However, there was no significant statistical difference between the DIR and both T2WI and FLAIR sequences regarding the contrast of intracortical lesions compared to NAGM.

Conclusion

DIR sequence is valuable in the imaging workup of MS as it can detect more MS lesions compared to the T2W and FLAIR sequences in all anatomical locations. DIR showed better delineation between the white matter, gray matter, and the MS lesions due to its high image contrast. DIR sequence should be included in the routine MR protocol of MS patients especially to answer the question about intra-cortical and juxta-cortical MS lesions.     

Health technology assessment on the use of magnetic resonance imaging (MRI) and computed tomography (CT) in the diagnosis of multiple sclerosis (MS) and clinically isolated syndromes (CIS)

This work is the result of a health technology assessment for the Flemish regional government, Belgium, performed in 2006. A search of the available literature in the databases Medline and EMBASE was performed to find evidence for a rational choice between CT and MRI techniques in the work-up of patients with clinically isolated syndrome (CIS) with a suspicion for multiple sclerosis (MS), and in follow-up exams performed in such patients. From the presented evidence, in patients referred for CIS or MS, MR is superior to CT for detection and characterization of brain and spine lesions.     

Relationships between brain water content and diffusion tensor imaging parameters (apparent diffusion coefficient and fractional anisotropy) in multiple sclerosis

Fifteen multiple sclerosis patients were examined by diffusion tensor imaging (DTI) to determine fractional anisotropy (FA) and apparent diffusion coefficient (ADC) in a superventricular volume of interest of 8×8×2 cm³ containing gray matter (GM) and white matter (WM) tissue. Point resolved spectroscopy 2D-chemical shift imaging of the same volume was performed without water suppression. The water contents and DTI parameters in 64 voxels of 2 cm³ were compared. The water content was increased in patients compared with controls (GM: 244±21 vs. 194±10 a.u.; WM: 245±32 vs. 190±11 a.u.), FA decreased (GM: 0.226±0.038 vs. 0.270±0.020; WM: 0.337±0.044 vs. 0.402±0.011) and ADC increased [GM: 1134±203 vs. 899±28 (×10⁻⁶ mm²/s); WM: 901±138 vs. 751±17 (×10⁻⁶ mm²/s)]. Correlations of water content with FA and ADC in WM were strong (r=−0.68, P<0.02; r=0.75; P<0.01, respectively); those in GM were weaker (r=−0.50, P<0.05; r=0.45, P<0.1, respectively). Likewise, FA and ADC were more strongly correlated in WM (r=−0.88; P<0.00001) than in GM (r=−0.69, P<0.01). The demonstrated relationship between DTI parameters and water content in multiple sclerosis patients suggests a potential for therapy monitoring in normal-appearing brain tissue.     

Investigation of apparent diffusion coefficient and diffusion tensor anisotrophy in acute and chronic multiple sclerosis lesions.

BACKGROUND AND PURPOSE: The various stages of multiple sclerosis (MS) are characterized by de- and remyelination as well as by inflammation. Diffusion MR imaging is sensitive to tissue water motion, which might correspond to these pathologic processes. Our purpose was to demonstrate differences in apparent diffusion coefficient (ADC) and diffusion tensor anisotropy in acute and chronic MS plaques and in normal-appearing brain. METHODS: Twelve MS patients underwent conventional and full-tensor diffusion MR imaging with B = 1221 s/mm2. Derivation of trace ADC and calculation of anisotropic scalars, including eccentricity, relative anisotropy (RA), and fractional anisotropy (FA) was performed on a per-pixel basis. Regions of interest of plaques and normal structures were determined on coregistered maps. MS lesions were classified as acute, subacute, or chronic on the basis of their appearance on conventional images and in relation to clinical findings. RESULTS: Seven patients had acute plaques with a concentric arrangement of alternating high and low signal intensity on diffusion-weighted images. In nine acute lesions, plaque centers had high ADC with reduced anisotropy compared with rim, normal-appearing white matter (NAWM), and chronic lesions. The thin rim of diffusion-weighted hyperintensity surrounding the center showed variable ADC and anisotropic values, which were not statistically different from NAWM. Subacute and chronic MS lesions had intermediate ADC elevations/anisotropic reductions. Calculated FA pixel maps were superior to eccentricity or RA maps; however, quality was limited by signal-to-noise constraints. CONCLUSION: ADC and diffusion anisotropic scalars reflect biophysical changes in the underlying pathology of the demyelinating process.     

Combined apparent diffusion coefficient value (ADC) and 1H magnetic resonance spectroscopy (MRS) in breast lesions: Benefits and limitations

Objective

This study aimed to assess the diagnostic value of a combined imaging protocol of diffusion-weighted MRI, apparent diffusion coefficient (ADC) values, and MR spectroscopy(MRS) in discriminating benign and malignant breast lesions.

The role of apparent diffusion coefficient (ADC) value in the differentiation between the most common pediatric posterior fossa tumors

Background

Diffusion weighted imaging (DWI) and apparent diffusion coefficient (ADC) map provide information on MRI about the cellularity of the tumor and have an important role in the pre-operative differentiation of different tumor types.

Aim

Is to evaluate the role of ADC value measurement in the differentiation between the most common pediatric posterior fossa tumors which include juvenile pilocytic astrocytoma, ependymoma and medulloblastoma.

Patients & methods

Thirty patients were retrospectively included in this study. They were referred from the Neurosurgery Department and all of them suspected to have posterior fossa SOL according to the contrast enhanced CT. All patients were subjected to conventional MRI followed by diffusion MR imaging and calculation of the ADC values.

Results

In JPA (group 1, n = 14), ADC values ranged between 2.4 and 1.3 × 10⁻³ mm²/s, ependymoma (group 2, n = 9), ADC values ranged between 1 and 1.3 × 10⁻³ mm²/s and medulloblastoma (group 3, n = 7), ADC values ranged between 0.5 and 0.9 × 10⁻³ mm²/s. Statistically significant difference in ADC value was detected between group1, group 2 and group 3, while no statistically significant difference was detected between group 1 and group 2.

Conclusion

The calculation of ADC value in the solid enhancing portion of a tumor is a simple and reliable technique for preoperative differentiation of the most common posterior fossa.     

年龄与月经周期对乳腺表观扩散系数差异影响的研究

目的 研究不同年龄段月经周期不同时期乳腺ADC的差异,探讨乳腺实质ADC值与年龄及月经周期之间的关系,以指导乳腺MR DWI检查时间的选择.方法 采用单次激发平面回波(EPI)技术,b值分别为0、1000 s/mm2,65名健康志愿者按年龄段分成3组:20～29岁21名;30～39岁21名;40～49岁23名.双侧130个乳房分别在月经期、增殖期及分泌期行常规MR平扫及MR DWI检查,测量各期乳头层面乳腺实质平均ADC值,用重复测量资料方差分析比较不同年龄段及月经周期不同时期ADC值之间差异.结果 月经期、增殖期及分泌期20～29岁乳腺实质的ADC值[左乳(2.14±0.14)×10-3、(2.03±0.18)×10-3、(2.10±0.19)×10-3 mm2/s;右乳(2.08±0.17)×10-3、(2.02±0.16)×10-3、(2.09±0.17)×10-3 mm2/s] 略高于40～49岁 [左乳(2.02±0.27)×10-3、(1.97±0.25)×10-3、(2.03±0.22)×10-3mm2/s;右乳(1.99±0.29)×10-3、(1.93±0.26)×10-3、(2.03±0.28)×10-3 mm2/s],30～39岁ADC值[左乳(1.94±0.25)×10-3、(1.91±0.21)×10-3、(1.97±0.21)×10-3 mm2/s;右乳(1.97±0.26)×10-3、(1.89±0.25)×10-3、(1.96±0.22)×10-3 mm2/s]最低;月经周期不同时期ADC值差异有统计学意义(F=23.600;P＜0.01);不同年龄段及左右乳ADC值差异无统计学意义(F值分别为1.683、2.248,P值均＞0.05).结论 乳腺实质ADC值增殖期下降明显,对各年龄段妇女行乳腺DWI检查应考虑月经周期因素的影响,以减少对乳腺疾病DWI诊断的干扰.

Abstract：

Objective To analyze the differences of ADC values in breasts of women of different ages and different menstrual phases, so as to direct the choice of the examination time of MR DWI. MethodsThe breasts of 65 healthy volunteers were scanned with the routine MRI plain scan and DWI in the menstrual, proliferative and secretary phases. DWI was conducted with single shot echo planar imaging technique and b value were 0, 1000 s/mm2. The women were divided into three groups: Group 1(aged 20 to 29 years, 21 cases), Group 2 (aged 30 to 39, 21cases), and Group 3 (aged 40 to 49, 23 cases). The ADC values of all 130 breasts at nipple level in the different phases were measured. The ADC values in the three age groups and in the different menstrual phases were compared using ANOVA. Results The mean ADC values of Group 1 were (2.14±0.14) ×10-3, (2.03±0.18) ×10-3and (2.10±0.19)×10-3mm2/s for left breast, and (2.08±0.17) ×10-3, (2.02±0.16) ×10-3and (2.09±0.17) ×10-3mm2/s for right breast in the menstrual, proliferative and secretary phases. They were slightly higher than Group 3, which were (2.02±0.27) ×10-3, (1.97±0.25) ×10-3and (2.03±0.22)×10-3 mm2/s for left breast and (1.99±0.29) ×10-3, (1.93±0.26) ×10-3and (2.03±0.28)×10-3 mm2/s for right breast. The mean ADC values of Group 2 [left breast: (1.94±0.25) ×10-3, (1.91±0.21) ×10-3and (1.97±0.21)×10-3 mm2/s ; right breast: (1.97±0.26)×10-3, (1.89±0.25)×10-3and (1.96±0.22)×10-3 mm2/s) were the lowest among the three age groups. There were significant differences in different menstrual phases (F= 23.600, P＜0.01), but no statistical difference was found among the three age groups or between left breasts and right breasts (F= 1.683, 2.248;P＞0.05).Conclusions The mean ADC values of breasts decrease markedly in the proliferative phase.The effects of the menstrual cycle on the breast ADC values should be considered in the evaluation of breast diseases with DWI.     

Value of apparent diffusion coefficient calculation in the differential diagnosis of parotid gland tumors

Background: The differential diagnosis of parotid gland tumors is often difficult with conventional magnetic resonance imaging.

Purpose: To determine whether the calculation of the apparent diffusion coefficient (ADC) is valuable for making the differential diagnosis of parotid tumors.

Material and Methods: Thirty parotid masses in 28 patients and 24 healthy parotid glands in 12 controls were examined in this prospective study. Diffusion-weighted magnetic resonance imaging with echo-planar spin-echo sequences was used to evaluate each subject. The ADC of each tumor and each healthy parotid gland was calculated. Tumor diagnoses were confirmed by the results of histopathologic analysis.

Results: The following types of masses were identified: 11 Warthin tumors, nine pleomorphic adenomas, seven malignant tumors, one basal cell adenoma, and two benign cysts. The mean ADC value for the Warthin tumors was 0.97±0.16×10^-3 mm²/s, for the pleomorphic adenomas was 1.74±0.37×10^-3 mm²/s, for the malignant tumors was 1.04±0.35×10^-3 mm²/s, and for the normal parotid glands was 0.34±0.20×10^-3 mm²/s. The respective ADC value for the single basal cell adenoma was 1.40×10^-3 mm²/s. Statistically significant differences were identified between the subjects with pleomorphic adenoma and those with another type of parotid tumor, and between subjects with healthy parotid glands and those with a tumor.

Conclusion: Calculating the ADC appears to be useful in differentiating pleomorphic adenomas from other types of parotid gland tumors.     

Evaluation and evolution of apparent diffusion coefficient (ADC) in image-guided adaptive brachytherapy (IGABT) for cervical cancer

PURPOSEImage-guided adaptive brachytherapy (IGABT) recently has shown excellent clinical outcomes with superior local control and less toxicity. For IGABT, T2W (T2-weighted) MRI is the gold standard. However, studies have shown that target delineation with the same results in uncertainties, poor interobserver variabilities, and low conformity indices for high-risk clinical target volume contours. In this study, we investigate the role of diffusion-weighted imaging–derived apparent diffusion coefficient (ADC) maps to aid in IGABT. We also evaluated ADC from the baseline to brachytherapy.Methods and MaterialsThirty selected patients were enrolled for this study, and two MRIs were taken at diagnosis and before brachytherapy. Patients were divided into two groups, Group 1 being patients with parametrial involvement before external beam radiotherapy and no parametrial involvement before brachytherapy. Group 2 included patients with parametrial involvement before external beam radiotherapy and persistent parametrial involvement before brachytherapy. ADC was measured at the center, edge, and 1 cm from the edge.ResultsThe measured ADC increased from diagnosis to brachytherapy, and this increase was more for the patients in Group 1 than in Group 2. The mean TDadc (diagnosis ADC, center), TEadc (tumor edge ADC diagnosis), and T1cmDadc (1 cm from edge at diagnosis) were 0.884, 1.45, and 1.9 × 10^?3 mm²/s, respectively. The TBadc (ADC at brachytherapy, center), TEBadc (tumor edge ADC at brachytherapy), and TE1cmBadc (1 cm from edge brachytherapy) were 1.2, 1.8, and 2.3 × 10^?3 mm²/s, respectively, p-value <0.00001. No abnormal ADC was present outside the high-risk clinical target volume contours.ConclusionMRI-based IGABT using T2W imaging essentially covers all functionally abnormal zones at brachytherapy. Diffusion-weighted imaging, along with ADC maps, should only be used as a supplement for target delineation.     

Correlation of apparent diffusion coefficient values measured by diffusion MRI and MGMT promoter methylation semiquantitatively analyzed with MS‐MLPA in patients with glioblastoma multiforme

Purpose:

To retrospectively determine whether the apparent diffusion coefficient (ADC) values correlate with O⁶‐methylguanine DNA methyltransferase (MGMT) promoter methylation semiquantitatively analyzed by methylation‐specific multiplex ligation‐dependent probe amplification (MS‐MLPA) in patients with glioblastoma.

Materials and Methods:

The study was approved by the Institutional Review Board and was Health Insurance Portability and Accountability Act (HIPAA) compliant. Newly diagnosed patients with glioblastoma (n = 26) were analyzed with an ADC histogram approach based on enhancing solid portion. The methylation status of MGMT promoter was assessed by methylation‐specific polymerase chain reaction (MSP) and by MS‐MLPA. MS‐MLPA is a semiquantitative method that determines the methylation ratio. The Ki‐67 labeling index was also analyzed. The mean and 5th percentile ADC values were correlated with MGMT promoter methylation status and Ki‐67 labeling index using a linear regression model. Progression‐free survival (PFS) was also correlated with the ADC values using Kaplan–Meier survival analysis.

Results:

The mean methylation ratio was 0.21 ± 0.20. By MSP, there were 5 methylated and 21 unmethylated tumors. The mean ADC revealed a positive relationship with MGMT promoter methylation ratio (P = 0.015) and was also significantly different according to MSP‐determined methylation status (P = 0.011). Median PFS was significantly related with methylation ratio (P = 0.017) and MSP‐derived methylation status (P = 0.025). A positive relationship was demonstrated between PFS and the mean ADC value (P = 0.001). The 5th percentile ADC values showed a significant negative relationship with Ki‐67 labeling index (P = 0.036).

Conclusion:

We found that ADC values were significantly correlated with PFS as well as with MGMT promoter methylation status. We believe that ADC values may merit further investigation as a noninvasive biomarker for predicting treatment response. J. Magn. Reson. Imaging 2013;37:351–358. © 2012 Wiley Periodicals, Inc.