Optimal Apparent Diffusion Coefficient Threshold Research Articles

Tumor Apparent Diffusion Coefficient is Associated with Early Recurrence of Intrahepatic Cholangiocarcinoma

Tumor Apparent Diffusion Coefficient is Associated with Early Recurrence of Intrahepatic Cholangiocarcinoma

Evaluation of Large Ischemic Cores to Predict Outcomes of Thrombectomy: A Proposal of a Novel Treatment Phase

Background Endovascular treatment of large ischemic cores is challenging. The severity of ischemic stress is assessed using the apparent diffusion coefficient (ADC). We aimed to evaluate the ADC in patients with a low Alberta Stroke Program Early CT [Computed Tomography] Score using diffusion‐weighted imaging and whether it correlates with clinical outcomes. Methods This study included consecutive patients with acute large ischemic stroke (Alberta Stroke Program Early CT Score‐diffusion‐weighted imaging ≤5) who underwent endovascular treatment with successful recanalization between April 2014 and March 2023. The most frequent ADC (peak ADC) and diffusion‐weighted imaging lesion volumes were assessed. The primary outcome was the 3‐month modified Rankin Scale (mRS) score. Good (mRS score, 0–3) and poor clinical outcomes (mRS score, 4–6) were compared to confirm whether ADC was associated with clinical outcomes. Results In total, 78 patients were enrolled in this study; 30 had an mRS score of 0 to 3 at 3 months. The peak ADC in these patients was significantly higher than that in patients with mRS scores of 4 to 6 ( P = 0.0002). In multivariate analysis, peak ADC was strongly associated with good clinical outcomes (odds ratio, 1.231; P = 0.0135) rather than onset‐to‐recanalization time and ischemic core volume. The optimal peak ADC threshold for discriminating between the mRS groups was 520×10 −6 mm 2 /s with a sensitivity of 75% and a specificity of 73%. Good clinical outcomes were more frequently observed in patients with peak ADC ≥520×10 −6 mm 2 /s ( P <0.0001). Conclusion In large ischemic cores, diffusion‐weighted imaging lesions with peak ADCs ≥520×10 −6 mm 2 /s are associated with favorable outcomes. Evaluation of the ischemic core is necessary to confirm endovascular treatment.

Predictive accuracy of an ADC map for hemorrhagic transformation in acute ischemic stroke patients after successful recanalization with endovascular therapy.

BackgroundHemorrhagic transformation (HT) of acute ischemic stroke (AIS) is associated with poor outcome. Previous studies only reported the association of mean ischemic severity or total infarct volume with HT after endovascular therapy (EVT). We aimed to investigate the predictive value of preoperative apparent diffusion coefficient (ADC) map for HT by combinated ischemic severity and corresponding volume in AIS after successful recanalization with EVT.MethodsWe retrospectively analyzed 119 consecutive cases of AIS with large vessel occlusion of anterior circulation within 24 hours after symptom onset and successful recanalization after EVT. All cases had baseline magnetic resonance imaging (MRI), follow-up computed tomography (CT), and magnetic resonance angiography (MRA) or computed tomography angiography (CTA). Volumes of ADC <0.6×10−3, 0.5×10−3, 0.4×10−3, and 0.3×10−3 mm2/s, baseline characteristics and outcomes of patients with and without HT identified by European Collaborative Acute Stroke Study (ECASS) were compared. The optimal ADC and volume threshold for predicting HT were analyzed using receiver operating characteristic (ROC) curve, and multivariate logistic regression analysis were performed with clinical characteristics and volumes of optimal ADC threshold to determine risk factors for HT.ResultsAmong 119 patients, 42 patients had HT on follow-up CT, including 24 hemorrhagic infarct (HI) cases and 18 parenchymal hematoma (PH) cases. The optimal volumes were 6.46 mL with ADC <0.4×10−3 mm2/s for predicting both HT and PH, with a larger area under curve (AUC) of 83.3% for HT than that for PH of 80%. In logistic regression analysis, intravenous tissue plasminogen activator (IV tPA) treatment, atrial fibrillation, and volume of ADC <0.4×10−3 mm2/s were identified as independent predictors for HT and volume of ADC <0.4×10−3 mm2/s had the highest odds ratio (OR) value.ConclusionsThe combination of ischemic severity and corresponding volume in ADC map may predict HT after thrombectomy. In addition to the total infarct volume, volume with severe ischemia should be taken into consideration in preoperative patient selection.

Role of Quantitative Diffusion-Weighted Imaging in Differentiating Benign and Malignant Orbital Masses.

Aim To determine the role of diffusion-weighted imaging (DWI) with apparent diffusion coefficient (ADC) values in differentiating benign and malignant orbital masses. Materials and Methods After obtaining institutional ethical board approval and informed consent from all patients, an observational study was done for a period of 24 months in the radiology department of a tertiary care hospital in South India. Conventional magnetic resonance imaging and DWI using a 3T scanner was done for all patients with suspected orbital mass lesion. ADC value and clinicohistopathological correlation were studied for every patient. Chi-square test was used to compare the signal characteristics of DWI and ADC maps between benign and malignant lesions. A comparison of mean ADC values for benign and malignant masses was performed using Student’s t -test for independent samples. The cut-off value for ADC was obtained using the receiver operating characteristic (ROC) curve. Results Of 44 patients with orbital lesions, 70% were benign and 30% were malignant. There was a significant difference in the mean ADC values of benign and malignant orbital masses. Using ROC curve analysis, an optimal ADC threshold of 1.26 × 10 −3 mm 2 /s was calculated for the prediction of malignancy with 100% sensitivity, 80.65% specificity, and 86.36% accuracy (95% confidence interval: 0.872, 1.00, p < 0.0001). Two ADC thresholds were used to characterize the orbital masses with more than 90% confidence. Conclusion Quantitative assessment of ADC is a useful noninvasive diagnostic tool for differentiating benign and malignant orbital masses. Malignant orbital lesions demonstrate significantly lower ADC values as compared with benign lesions.

Value of apparent diffusion coefficient for differentiating peripancreatic tuberculous lymphadenopathy from metastatic lymphadenopathy.

To evaluate effectiveness of the apparent diffusion coefficient (ADC) values of the peripancreatic lymphadenopathy to differentiate tuberculous lymphadenopathy from metastatic lymphadenopathy. Twenty-nine patients with 65 peripancreatic necrotic tuberculous lymphadenopathy and 31 patients with 47 peripancreatic necrotic metastatic lymphadenopathy from pancreatic ductal adenocarcinoma, who underwent magnetic resonance imaging (MRI), were included in this study. MRI features in the T1-weighted image (WI), T2WI, and diffusion-weighted image were analyzed. The ADC values of necrotic and non-necrotic portions of the lymphnodes were measured and compared using t test. Receiver operating characteristic analysis was performed to obtain the optimal ADC threshold value and diagnostic accuracy for differentiating tuberculous lymphadenopathy from metastatic lymphadenopathy. On T2WI, the signal intensity of necrotic portions was variable in tuberculous lymphadenopathy, but was mostly high in metastatic lymphadenopathy. The mean ADCs of necrotic portions of tuberculous lymphadenopathy were significantly lower than those of metastatic lymphadenopathy ([0.919 ± 0.272] × 10-3 mm2/s vs. [1.553 ± 0.406] × 10-3mm2/s, p < 0.001). Receiver operating characteristic analysis for differentiating tuberculous from metastatic lymphadenopathy demonstrated an area under the curve for the ADC values of necrotic portions of 0.929 (95% CI, 0.865-0.969) with an ADC threshold of 1.022. The sensitivity and specificity for the differentiation of tuberculous from metastatic lymphadenopathy were 80.0% and 97.8%, respectively. The ADC values of necrotic portions of peripancreatic lymphadenopathy may be useful for differentiating tuberculous from metastatic lymphadenopathy.

Diffusion-Weighted Imaging of Breast Cancer: Correlation of the Apparent Diffusion Coefficient Value with Pathologic Prognostic Factors.

The aim was to evaluate relationship between apparent diffusion coefficient (ADC) values with pathologic prognostic factors in breast carcinoma (BC). 83 patients were enrolled in this study. Prognostic factors included age, tumor size, expression of estrogen receptor (ER) and progesterone receptor (PR), human epidermal growth factor receptor 2 (HER2), nuclear grade (NG), lymph node involvement and histologic type. The relationship between ADC and prognostic factors was determined using Independent sample t-test, ANOVA, Pearson correlation and relative operating characteristics (ROC) analysis. There was no significant difference between ADC and prognostic factors, including age, tumor size, ER, HER2 and histologic type. The PR-positive tumors (p=0.03) and axillary lymph node involvement (p=0.000) showed a significant association with lower ADC values. The ADC values were significantly lower in high-grade tumors than low-grade tumors (p=0.000). ROC analysis showed an optimal ADC threshold of 0.66 (×10-3 mm2/s) for differentiating low-grade tumors from high-grade tumors (sensitivity, 85.5%; specificity, 81%; area under curve, 0.90). The lower ADC values of BC were significantly associated with positive expression of PR, LN positivity and high-grade tumor. Especially, ADC values were valuable in predicting NG subgroups.

Assessment of apparent diffusion coefficient value as prognostic factor for renal cell carcinoma aggressiveness

BackgroundAssurance of prognostic elements is important for the management of renal cell carcinoma (RCC). Our goal was to check the relation between apparent diffusion coefficient (ADC) values and parameters predicting prognosis of RCC. Fifty pathologically confirmed RCC underwent diffusion-weighted (DW) MRI. ADC values were calculated using b factor (800 s/mm2). The correlation between ADC values and tumor size, cystic/necrotic feature, growth pattern, unenhanced T1, histological grade, clinical stage, and distant metastasis were analyzed.ResultsThe optimal ADC threshold for prognosis of RCC appeared to be 1.4 × 10−3 mm2/s. There was a significant inverse correlation between ADC values and growth pattern (R = − 0, P = 0.05), unenhanced T1(R = − 0.41, P = 0.01), cystic/necrotic feature (R = − 0.4, P = 0.01), histological grade (R = − 0.37, P = 0.02), clinical stage (r = − 0.4, P = 0.01), and distant metastasis (R = − 0.33, P = 0.04), and significant linear correlation with tumor size (R = 0.39, P < 0.02).ConclusionThe performance of ADC value as a newly proposed prognostic parameter follows with the degree of tumor differentiation and that may recognize extremely aggressive RCC. RCC with low ADC values should be inspected extensively for the risk of high pathological grade, high clinical stage, and distant metastasis.

Correlation Between Semen Analysis Parameters and Diffusion-Weighted Magnetic Resonance Imaging of the Testicles in Patients With Varicocele: A Pilot Study.

The aims of this study were to evaluate using testicle apparent diffusion coefficient (ADC) values in patients with varicocele and compare them with those of healthy individuals, to identify an optimal ADC threshold level to predict abnormal semen analysis using diffusion-weighted imaging. Thirty-one patients with the diagnosis of varicocele and 20 healthy controls were enrolled in the study. All subjects underwent testicle diffusion-weighted imaging at b values of 0, 400, and 800 s/mm and semen analysis. Student t tests were used to compare continuous variables between 2 groups. Testicle ADC values were correlated with semen analysis parameters. The relationship between ADC values and impaired semen analysis parameters was evaluated using Pearson correlation coefficient analysis. Receiver operating characteristic curves were formed. Cut-off values for ADC, sensitivity, and specificity values were measured. There was a negative correlation between mean ADC values and plexus pampiniformis vein diameter (r = -0.467, P < 0.001) and a positive correlation between mean ADC values and sperm count (r = 0.838, P < 0.001) as well as sperm morphology (r = 0.548, P < 0.05). Sensitivity values of 94.3% and 86.6% and specificity values of 87.5% and 43.8% were determined for the best cut-off ADC values in diagnosing the sperm count and morphology, respectively (area under the curve, 0.961 and 0.781). Decreased testicular ADC values in patients with varicocele are significantly correlated with semen parameters. This method may be used to determine the degree of testicular parenchymal destruction. In addition, testicular ADC cut-off values might be useful in dyspermia patients for the management of patients with varicocele.

Grading System to Categorize Breast MRI in BI-RADS 5th Edition: A Multivariate Study of Breast Mass Descriptors in Terms of Probability of Malignancy.

The purpose of this study is to analyze the association between the probability of malignancy and breast mass descriptors in the BI-RADS 5th edition and to devise criteria for grading mass lesions, including subcategorization of category 4 lesions with or without apparent diffusion coefficient (ADC) values. A total of 519 breast masses in 499 patients were selected. Breast MRI was performed with a 1.5-T MRI scanner using a 16-channel dedicated breast radiofrequency coil. Two radiologists determined the morphologic and kinetic features of the breast masses. Mean ADC values were measured on ADC maps by placing round ROIs that encircled the largest possible solid mass portions. An optimal ADC threshold was chosen to maximize the Youden index. Corresponding pathologic diagnoses were obtained by either biopsy or surgery. A total of 472 masses were malignant. Multivariate model analysis showed that shape (irregular, p < 0.001), margin type (not circumscribed, p < 0.001), internal enhancement (rim enhancement and heterogeneous enhancement, p = 0.0001), and delayed phase (washout, p = 0.0003) were the significant explanatory variables. The 3-point scoring system for findings suspicious for malignancy and the proposed classification system for breast mass descriptors (with points for category designation ranging from 0 to > 4) were significant with respect to malignancy (p < 0.01). The inclusion of ADC values improved the positive predictive values for categories 3, 4A, and 4B. The 3-point scoring system for findings suspicious for malignancy and the proposed classification system for breast mass descriptors would be valid as a categorization system. ADC values may be used to downgrade benign lesions in categories 3, 4A, and 4B.

Assessment of prostate cancer aggressiveness using apparent diffusion coefficient values: impact of patient race and age.

To assess the impact of patient race and age on the performance of apparent diffusion coefficient (ADC) values for assessment of prostate cancer aggressiveness. 457 prostate cancer patients who underwent 3T phased-array coil prostate MRI including diffusion-weighted imaging (DWI; maximal b-value 1000s/mm2) before prostatectomy were included. Mean ADC of a single dominant lesion was measured in each patient, using histopathologic findings from the prostatectomy specimen as reference. In subsets defined by race and age, ADC values were compared between Gleason score (GS)≤3+4 and GS≥4+3 tumors. 81% of patients were Caucasian, 12% African-American, 7% Asian-American. 13% were <55years, 42% 55-64years, 41% 65-74years, and 4% ≥75years. 63% were GS≤3+4, 37% GS≥4+3. ADC was significantly lower in GS≥4+3 tumors than in GS≤3+4 tumors in the entire cohort, as well as in Caucasian, African-American, and all four age groups (P≤0.015). AUC for differentiation of GS≤3+4 and GS≥4+3 as well as optimal ADC threshold was Caucasian: 0.73/≤848; African-American: 0.76/≤780; Asian-American: 0.66/≤839: <55years, 0.73/≤830; 55-64years, 0.71/≤800; 65-74years, 0.74/≤872; ≥75years, 0.79/≤880. A race-optimized ADC threshold resulted in higher specificity in African-American than Caucasian men (84.9% vs. 67.1%, P=0.045); age-optimized ADC threshold resulted in higher sensitivity in patients aged ≥75years than <55years or 55-64years (100.0% vs. 53.6%-73.3%; P<0.001). Patients' race and age may impact the diagnostic performance and optimal threshold when applying ADC values for evaluation of prostate cancer aggressiveness.

Diffusion-weighted magnetic resonance imaging without bowel preparation for detection of ulcerative colitis.

To evaluate the accuracy of diffusion-weighted imaging (DWI) without bowel preparation, the optimal b value and the changes in apparent diffusion coefficient (ADC) in detecting ulcerative colitis (UC). A total of 20 patients who underwent 3T magnetic resonance imaging (MRI) without bowel preparation and colonoscopy within 24 h were recruited. Biochemical indexes, including C-reactive protein (CRP), erythrocyte sedimentation rate, hemoglobin, leucocytes, platelets, serum iron and albumin, were determined. Biochemical examinations were then performed within 24 h before or after MR colonography was conducted. DWI was performed at various b values (b = 0, 400, 600, 800, and 1000 s/mm(2)). Two radiologists independently and blindly reviewed conventional- and contrast-enhanced MR images, DWI and ADC maps; these radiologists also determined ADC in each intestinal segment (rectum, sigmoid, left colon, transverse colon, and right colon). Receiver operating characteristic (ROC) analysis was performed to assess the diagnostic performance of DWI hyperintensity from various b factors, ADC values and different radiological signs to detect endoscopic inflammation in the corresponding bowel segment. Optimal ADC threshold was estimated by maximizing the combination of sensitivity and specificity. MR findings were correlated with endoscopic results and clinical markers; these findings were then estimated by ROC analysis. A total of 100 segments (71 with endoscopic colonic inflammation; 29 normal) were included. The proposed total magnetic resonance score (MR-score-T) was correlated with the total modified Baron score (Baron-T; r = 0.875, P < 0.0001); the segmental MR score (MR-score-S) was correlated with the segmental modified Baron score (Baron-S; r = 0.761, P < 0.0001). MR-score-T was correlated with clinical and biological markers of disease activity (r = 0.445 to 0.831, P < 0.05). MR-score-S > 1 corresponded to endoscopic colonic inflammation with a sensitivity of 85.9%, a specificity of 82.8% and an area under the curve (AUC) of 0.929 (P < 0.0001). The accuracy of DWI hyperintensity was significantly greater at b = 800 than at b = 400, 600, or 1000 s/mm(2) (P < 0.05) when endoscopic colonic inflammation was detected. DWI hyperintensity at b = 800 s/mm(2) indicated endoscopic colonic inflammation with a sensitivity of 93.0%, a specificity of 79.3% and an AUC of 0.867 (P < 0.0001). Quantitative analysis results revealed that ADC values at b = 800 s/mm(2) differed significantly between endoscopic inflamed segment and normal intestinal segment (1.56 ± 0.58 mm(2)/s vs 2.63 ± 0.46 mm(2)/s, P < 0.001). The AUC of ADC values was 0.932 (95% confidence interval: 0.881-0.983) when endoscopic inflammation was detected. The threshold ADC value of 2.18 × 10(-3) mm(2)/s indicated that endoscopic inflammation differed from normal intestinal segment with a sensitivity of 89.7% and a specificity of 80.3%. DWI combined with conventional MRI without bowel preparation provides a quantitative strategy to differentiate actively inflamed intestinal segments from the normal mucosa to detect UC.

MP65-20 UTILITY OF APPARENT DIFFUSION COEFFICIENT VALUES FOR CHARACTERIZATION OF METASTATIC LYMPH NODES IN BLADDER CANCER

You have accessJournal of UrologyBladder Cancer: Staging1 Apr 2014MP65-20 UTILITY OF APPARENT DIFFUSION COEFFICIENT VALUES FOR CHARACTERIZATION OF METASTATIC LYMPH NODES IN BLADDER CANCER Ahmed M. Mansour, Mohamed E. Abou-El-Ghar, Huda F. Refaie, Ahmed El-Assmy, Ahmed Mosbah, Hassan abol-Enein, and Tarek El-Diasty Ahmed M. MansourAhmed M. Mansour More articles by this author , Mohamed E. Abou-El-GharMohamed E. Abou-El-Ghar More articles by this author , Huda F. RefaieHuda F. Refaie More articles by this author , Ahmed El-AssmyAhmed El-Assmy More articles by this author , Ahmed MosbahAhmed Mosbah More articles by this author , Hassan abol-EneinHassan abol-Enein More articles by this author , and Tarek El-DiastyTarek El-Diasty More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2014.02.1917AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES Diffusion-weighted MR imaging (DW-MRI) has been recently utilized for characterization of bladder cancer phenotypes and clinical aggressiveness. The purpose of our study is to assess the utility of apparent diffusion coefficient (ADC) for distinguishing lymph nodes harboring metastatic disease in bladder cancer patients with enlarged pelvic lymph nodes. METHODS The study cohort included 138 patients who underwent MRI with diffusion weighted imaging prior to radical cystectomy between April 2012 and May 2013. ADC values were measured in a circular region of interest where lymph node enlargement was found. Two radiologists blinded to the pathologic outcome interpreted the DW images. All patients underwent radical cystectomy with bilateral extended lymphadenectomy extending above the bifurcation of the common iliac vessels. Anatomical mapping of the removed lymph nodes was performed intraoperatively and the nodes were sent in separate packages for pathological assessment. ADC values obtained from areas of lymph node enlargement were then correlated with the final pathological assessment of the resected lymph nodes. RESULTS One hundred and thirty eight patients were evaluated by DW-MRI. Patients with radiological lymph node enlargement were identified (n=88, 63%) ADC values were calculated in areas of lymph node enlargement in four anatomical regions on each side, namely, common iliac, external iliac, internal iliac and obturator regions. Mean(SD) ADC value was 1.06 (0.2) *103 mm2/s. There was a significant difference in ADC values of areas of metastatic lymph nodes and areas of negative node involvement (p=0.0012). ROC analysis identified an optimal ADC threshold of 1.25 *103 mm2/s for identifying the presence or absence of metastatic disease. CONCLUSIONS Our results suggests that DW-MRI ADC values correlate with the presence of metastatic disease in patients with bladder cancer and radiologically enlarged lymph nodes. © 2014FiguresReferencesRelatedDetails Volume 191Issue 4SApril 2014Page: e699 Advertisement Copyright & Permissions© 2014MetricsAuthor Information Ahmed M. Mansour More articles by this author Mohamed E. Abou-El-Ghar More articles by this author Huda F. Refaie More articles by this author Ahmed El-Assmy More articles by this author Ahmed Mosbah More articles by this author Hassan abol-Enein More articles by this author Tarek El-Diasty More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

Usefulness of 3T diffusion-weighted MRI for discrimination of reactive and metastatic cervical lymph nodes in patients with oral squamous cell carcinoma: a pilot study

To study the diagnostic accuracy of 3T diffusion-weighted MRI (DW-MRI) for the discrimination of reactive and metastatic cervical lymph nodes in patients with oral squamous cell carcinoma. DW T1 and T2 weighted MRI was performed in 25 patients with biopsy-proved primary oral squamous cell carcinoma. The mean apparent diffusion coefficient (ADC) values of 30 histopathologically proved reactive lymph nodes and 21 histopathologically proved metastatic lymph nodes were compared using an unpaired t-test. A cut-off ADC value with optimal diagnostic sensitivity, specificity and area under the curve in discrimination of the two groups was determined using a receiver operating characteristic curve analysis. The mean ADC values of reactive lymph node and metastatic lymph node groups were (1.037 ± 0.149) × 10(-3) and (0.702 ± 0.197) × 10(-3) mm(2) s(-1), respectively. A statistically significant difference in ADC values of the two groups was certified (p < 0.0001). An optimal ADC threshold value of 0.887 × 10(-3) mm(2) s(-1) was suggested as the cut-off point, which resulted in 93.33% sensitivity, 80.95% specificity, 88.20% accuracy and area under curve of 0.887. Our preliminary study indicates that the addition of 3T DW-MRI may be useful for discriminating between reactive lymph nodes and metastatic lymph nodes in patients with oral squamous cell carcinoma. However, larger studies are still required to validate our results and to standardize this imaging technique for daily clinical practice.

Apparent Diffusion Coefficient Threshold for Delineation of Ischemic Core

MRI-based selection of patients for acute stroke interventions requires rapid accurate estimation of the infarct core on diffusion-weighted MRI. Typically used manual methods to delineate restricted diffusion lesions are subjective and time consuming. These limitations would be overcome by a fully automated method that can rapidly and objectively delineate the ischemic core. An automated method would require predefined criteria to identify the ischemic core. The aim of this study is to determine apparent diffusion coefficient-based criteria that can be implemented in a fully automated software solution for identification of the ischemic core. Imaging data from patients enrolled in the Diffusion and Perfusion Imaging Evaluation for Understanding Stroke Evolution (DEFUSE) study who had early revascularization following intravenous thrombolysis were included. The patients' baseline restricted diffusion and 30-day T2 -weighted fluid-attenuated inversion recovery lesions were manually delineated after coregistration. Parts of the restricted diffusion lesion that corresponded with 30-day infarct were considered ischemic core, whereas parts that corresponded with normal brain parenchyma at 30 days were considered noncore. The optimal apparent diffusion coefficient threshold to discriminate core from noncore voxels was determined by voxel-based receiver operating characteristics analysis using the Youden index. 51,045 diffusion positive voxels from 14 patients who met eligibility criteria were analyzed. The mean DWI lesion volume was 24 (± 23) ml. Of this, 18 (± 22) ml was ischemic core and 3 (± 5) ml was noncore. The remainder corresponded to preexisting gliosis, cerebrospinal fluid, or was lost to postinfarct atrophy. The apparent diffusion coefficient of core was lower than that of noncore voxels (P < 0.0001). The optimal threshold for identification of ischemic core was an apparent diffusion coefficient ≤ 620 × 10(-6) mm(2) /s (sensitivity 69% and specificity 78%). Our data suggest that the ischemic core can be identified with an absolute apparent diffusion coefficient threshold. This threshold can be implemented in image analysis software for fully automated segmentation of the ischemic core.

Malignant Pleural Disease: Diagnosis by Using Diffusion-weighted and Dynamic Contrast-enhanced MR Imaging—Initial Experience

To investigate the use of diffusion-weighted (DW) imaging for differentiating benign lesions from malignant pleural disease (MPD) and to retrospectively assess dynamic contrast material-enhanced (DCE) magnetic resonance (MR) imaging acquisitions to find out whether combining these measurements with DW imaging could improve the diagnostic value of DW imaging. This study was approved by the local ethics committee, and all patients provided written informed consent. Thirty-one consecutive patients with pleural abnormalities suspicious for MPD underwent whole-body positron emission tomography (PET)/computed tomography (CT) and thorax MR examinations. Diagnostic thoracoscopy with histopathologic analysis of pleural biopsies served as the reference standard. First-line evaluation of each suspicious lesion was performed by using the apparent diffusion coefficient (ADC) calculated from the DW image, and the optimal cutoff value was found by using receiver operating characteristic curve analysis. Afterward, DCE MR imaging data were used to improve the diagnosis in the range of ADCs where DW imaging results were equivocal. Sensitivity, specificity, and accuracy of PET/CT for diagnosis of MPD were 100%, 35.3%, and 64.5%. The optimal ADC threshold to differentiate benign lesions from MPD with DW MR imaging was 1.52 × 10(-3) mm(2)/sec, with sensitivity, specificity, and accuracy of 71.4%, 100%, and 87.1%, respectively. This result could be improved to 92.8%, 94.1%, and 93.5%, respectively, when DCE MR imaging data were included in those cases where ADC was between 1.52 and 2.00 × 10(-3) mm(2)/sec. A total of 20 patients had disease diagnosed correctly, nine had disease diagnosed incorrectly, and two cases were undetermined with PET/CT. DW imaging helped stage disease correctly in 27 patients and incorrectly in four. The undetermined cases at PET/CT were correctly diagnosed at MR imaging. DW imaging is a promising tool for differentiating MPD from benign lesions, with high accuracy, and supplementation with DCE MR imaging seems to further improve sensitivity.

Apparent diffusion coefficient values of necrotic and solid portion of lymph nodes: Differential diagnostic value in cervical lymphadenopathy

To evaluate whether the analysis of the apparent diffusion coefficient (ADC) values of the necrotic and solid portions of lymph nodes aids differentiation between the causes of cervical lymphadenopathy. Thirty-six patients with cervical lymph node metastasis from head and neck squamous cell carcinomas (SCC), 19 patients with lymphoma, and 23 patients with tuberculous lymphadenitis underwent conventional magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI). The ADC values of necrotic and solid portions of lymph nodes were measured and compared. Receiver operating characteristic (ROC) analysis was employed to investigate whether ADC values could help to discriminate between the causes of cervical lymphadenopathy, and to obtain the optimal ADC threshold values. The mean ADC values of the solid portions of metastatic nodes, lymphomatous nodes, and tuberculous nodes were (0.93±0.16)×10(-3)mm(2)/s, (0.64±0.13)×10(-3)mm(2)/s and (1.01±0.11)×10(-3)mm(2)/s, respectively (p<0.01). The mean ADC values of necrosis of metastatic and tuberculous nodes were (2.02±0.36)×10(-3)mm(2)/s and (1.25±0.15)×10(-3)mm(2)/s (p<0.01). By using the ADC value of the solid portion, the optimal ADC threshold values for distinguishing between metastasis and lymphoma, between metastasis and tuberculosis, and between lymphoma and tuberculosis were 0.77×10(-3), 0.98×10(-3) and 0.81×10(-3)mm(2)/s, respectively, and the sensitivities and specificities were 83 and 89%, 70 and 68%, 93 and 100%, respectively. By using ADC values of necrosis, the optimal ADC threshold value for distinguishing between metastasis and tuberculosis was 1.59×10(-3)mm(2)/s, and the sensitivity and specificity were 88 and 100%, respectively. The ADC values both of the necrotic and solid portions of the lymph nodes are useful in differentiation between the causes of cervical lymphadenopathy. The ADC value of necrosis is especially helpful in discriminating metastasis from tuberculosis.

Is it possible to differentiate between hydatid and simple cysts in the liver by means of diffusion-weighted magnetic resonance imaging?

Our aim was to evaluate the contribution of diffusion-weighted imaging to the differentiation of hydatid cysts (HCs) from the simple cysts and to the identification of the HC subtypes. A total of 37 patients were included in this retrospective study. Fifty of these patients had diagnosed liver cysts (28 HCs and 22 simple cysts) of at least 1 cm in size. All of the cysts were examined with sonography and magnetic resonance imaging, and the HCs were classified according to the World Health Organization criteria. Twenty-eight of the total 50 cysts were HCs, and 22 were simple cysts. When the apparent diffusion coefficient (ADC) values of all HCs were compared with the ADC values of the simple cysts, a statistically significant relationship was found (P=.001). The optimal ADC threshold value was established as 2.5 s/mm(2). The sensitivity, specificity, positive predictive value, negative predictive value and accuracy rates were 60%, 95%, 94%, 65% and 76%, respectively. Diffusion-weighted imaging-magnetic resonance imaging is a considerably helpful technique for differentiating between HCs and simple cysts and for differentiating between HC subtypes.

Water Diffusivity: Comparison of Primary CNS Lymphoma and Astrocytic Tumor Infiltrating the Corpus Callosum

The purpose of this study was to determine whether lymphoma and astrocytic tumor infiltrating the corpus callosum can be reliably differentiated with measurement of water diffusivity. Echo-planar diffusion-weighted MR images of 27 patients with glioblastoma multiforme, five patients with low-grade astrocytoma, five patients with gliomatosis cerebri, and nine patients with primary lymphoma infiltrating the corpus callosum were reviewed retrospectively. Regions of interest were drawn on apparent diffusion coefficient (ADC) maps inside the callosal tumor. ADCs were normalized by calculation of the ratio between the ADC of the tumor and the ADC of an uninvolved region of corpus callosum. The mean ADC of glioblastoma multiforme was 1.13 +/- 0.31 (SD) x 10(-3) mm(2)/s, and the mean tumor to corpus callosum ADC ratio was 1.51 +/- 0.46; of low-grade astrocytoma, 1.14 +/- 0.23 x 10(-3) mm(2)/s and 1.54 +/- 0.28; gliomatosis cerebri, 1.01 +/- 0.20 x 10(-3) mm(2)/s and 1.31 +/- 0.36; and lymphoma, 0.71 +/- 0.13 x 10(-3) mm(2)/s and 0.93 +/- 0.19. The difference between the mean tumor to corpus callosum ADC ratio of lymphoma and that of all grades of astrocytoma (1.48 +/- 0.43) was statistically significant (p < 0.001). The optimal ADC threshold for discriminating astrocytic tumor and lymphoma was 0.90 x 10(-3) mm(2)/s (sensitivity, 84%; specificity, 89%). The optimal threshold for tumor to corpus callosum ADC ratio was 1.22 (sensitivity, 73%; specificity, 100%). The water diffusivity and the ADC ratio of the tumor to normal-appearing corpus callosum of astrocytic tumor differ significantly from those of lymphoma infiltrating the corpus callosum, allowing reliable differentiation of the two types of tumor.

The utility of diffusion-weighted MR imaging in cervical cancer

To investigate the value of diffusion-weighted MR imaging (DWI) in detection of cervical cancer, and to determine the diagnostic accuracy of apparent diffusion coefficient (ADC) values for evaluating cervical cancer before and after chemoradiotherapy. Thirty-three patients with cervical squamous carcinoma and 20 patients with other pelvic abnormalities underwent diffusion-weighted imaging (DWI) in addition to routine MR imaging. The ADC values of normal cervical tissue, cervical area before and after chemoradiotherapy were measured and compared. Receiver operating characteristic (ROC) analysis was employed to investigate whether ADC values could help in discrimination among normal cervical tissue, cervical cancer before and after therapy, and to obtain the optimal ADC threshold value. Cervical cancer lesion demonstrated obviously hyperintensity on DWI images. The mean ADC value of cervical carcinoma (1.110+/-0.175 x 10(-3)mm(2)/s) was significantly lower than that of normal cervical tissue (1.593+/-0.151 x 10(-3)mm(2)/s) (P<0.001). The mean ADC value of the cervical area in 22 patients treated by chemoradiotherapy (1.436+/-0.129 x 10(-3)mm(2)/s) was significantly higher than that before therapy (1.013+/-0.094 x 10(-3)mm(2)/s) (P<0.001). The difference of ADC values between normal cervical tissue and cervical area after therapy was statistically significant (P<0.01). The optimal ADC threshold values for distinguishing between normal cervical tissue and cervical carcinoma was 1.359 x 10(-3)mm(2)/s, between cervical area before and after therapy was 1.255 x 10(-3)mm(2)/s, between normal cervical tissue and cervical area after therapy was 1.525 x 10(-3)mm(2)/s. The sensitivity and specificity were 100% and 84.8%, 95.5% and 100%, 70% and 81.8%, respectively. DWI can be applied for the detection of cervical cancer because of its superior disease contrast with normal tissue. The measurement of the ADC values can be a useful tool to monitor the response to therapy for cervical carcinoma.

Diagnostic accuracy and additional value of diffusion-weighted imaging for discrimination of malignant cervical lymph nodes in head and neck squamous cell carcinoma

The aim was to determine the diagnostic accuracy and additional value of diffusion-weighted imaging for detection of malignant lymph nodes in head and neck squamous cell carcinoma. Two hundred nineteen lymph nodes, predominantly smaller than 10 mm (95.4%), in 16 consecutive patients were evaluated at 1.5 T. Lymph nodes were evaluated for maximum short axial diameter, morphological criteria, and apparent diffusion coefficient (ADC) values (b = 0 and b = 1,000 s/mm(2)). Sensitivity, specificity, positive and negative predictive values as well as diagnostic odds ratios (DORs) and areas under the curves (AUCs) of ROC curves were calculated for the various magnetic resonance imaging (MRI) criteria individually and in combination. Histological examination of lymph nodes in the neck dissection specimen was the gold standard to determine malignant involvement. The optimal ADC threshold was 1.0 x 10(-3) mm(2)/s. Using this cutoff point, sensitivity and specificity were 92.3% and 83.9%, respectively. When used in combination with size and morphological criteria, ADC value <1.0 x 10(-3) mm(2)/s was the strongest predictor of presence of metastasis (DOR = 97.6). A model which added ADC values to the other MRI criteria performed significantly better than a model without ADC values: AUC = 0.98 versus AUC = 0.91 (p = 0.036). In this study, with predominantly small lymph nodes, the ADC criterion is the strongest independent predictor of presence of metastasis. The use of ADC values in combination with the other MRI criteria significantly improves the discrimination between malignant and benign lymph nodes.