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

Introduction  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. Methods  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/mm²). 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. Results  The optimal ADC threshold was 1.0 × 10⁻³ mm²/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 × 10⁻³ mm²/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). Conclusion  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.     

Respiratory gated diffusion-weighted imaging of the liver: value of apparent diffusion coefficient measurements in the differentiation between most commonly encountered benign and malignant focal liver lesions

The purpose of this study was to measure apparent diffusion coefficient values of normal liver parenchyma and focal liver lesions utilizing a respiratory gated diffusion sequence with multiple b-values and to investigate whether apparent diffusion coefficient (ADC) measurements may be utilized to characterize and differentiate between malignant and benign focal hepatic lesions. Thirty-eight consecutive patients underwent MRI of the liver including diffusion-weighted imaging (DWI). A single-shot echo planar imaging sequence was applied in coronal orientation with multiple b-values (0, 50, 500, 1,000 s/mm²) and respiratory gating. ADC values were recorded on corresponding maps utilizing region of interest measurements in patients with benign (group A), malignant (group B) focal lesions and liver parenchyma (group C). Statistical analysis was applied to check whether differences in mean ADC values were significant (p<0.05). No focal lesions were detected in 11 patients, with a mean ADC value (CI 95%) of liver parenchyma 1.25×10⁻³ mm²/s (1.21×10⁻³ mm²/s−1.29×10⁻³ mm²/s). Differences in mean ADC of liver parenchyma between group A and B were not significant (p=0.054, 1.30×10⁻³ mm²/s and 1.31×10⁻³ mm²/s, respectively). Mean ADC value (95% CI) of 22 benign lesions found in 18 patients was 2.55×10⁻³ mm²/s (2.35×10⁻³ mm²/s−2.74×10⁻³ mm²/s), while the mean ADC value (95% CI) of 16 malignant lesions recorded in 9 patients was 1.04×10⁻³ mm²/s (0.9×10⁻³ mm²/s−1.17×10⁻³ mm²/s). The difference between mean ADC values of benign and malignant focal lesions was statistically significant (p<0.0001). Respiratory gated diffusion-weighted imaging in the liver is technically feasible. Apparent diffusion coefficient measurements can be useful in differentiating malignant from benign focal liver lesions.     

Value of diffusion-weighted MR imaging in the differentiation between benign and malignant cervical lymph nodes

Purpose

To evaluate echo-planar diffusion-weighted MR imaging (DWI) in the differentiation between benign and malignant cervical lymph nodes.

Materials and methods

35 consecutive patients with 55 enlarged (>10 mm) cervical lymph nodes underwent MR imaging at 1.5-T. DWI was performed using a single-shot echo-planar (SSEPI) MR imaging sequence with b values (b: diffusion factor) of 0, 500 and 1000 s/mm². Apparent diffusion coefficient (ADC) maps were reconstructed for all patients and ADC values were calculated for each lymph node. Imaging results were correlated with histopathologic findings after neck dissection or surgical biopsy, findings in PET/CT or imaging follow-up. Mann-Whitney test was used for statistical analysis and a receiver operating characteristic (ROC) curve analysis was performed.

Results

Cervical lymph node enlargement was secondary to metastases from squamous cell carcinomas [n = 25], non-Hodgkin’s lymphoma [n = 6], reactive lymphadenitis [n = 20], cat scratch lymphadenitis [n = 2] and sarcoidosis [n = 2]. The mean ADC values (×10⁻³ mm²/s) were 0.78 ± 0.09 for metastatic lymph nodes, 0.64 ± 0.09 for lymphomatous nodes and 1.24 ± 0.16 for benign cervical lymph nodes. ADC values of malignant lymph nodes were significantly lower than ADC values of benign lymph nodes. 94.3% of lesions were correctly classified as benign or malignant using a threshold ADC value of 1.02 × 10⁻³ mm²/s.

Conclusion

According to our first experience, DWI using a SSEPI sequence allows reliable differentiation between benign and malignant cervical lymph nodes.     

Diagnostic performance of diffusion-weighted magnetic resonance imaging in esophageal cancer

The purpose of this study was to assess the value of diffusion-weighted magnetic resonance imaging (DWI) in detecting esophageal cancer and assessing lymph-node status, compared with histopathological results. DWI was prospectively performed in 24 consecutive patients with esophageal cancer, using the diffusion-weighted whole-body imaging with background body signal suppression (DWIBS) sequence. DWIBS images were fused with T2-weighted images, and independently and blindly evaluated by three board-certified radiologists, regarding primary tumor detectability and lymph-node status. Apparent diffusion coefficients (ADCs) of the primary tumor and lymph nodes were also measured. Average primary tumor detection rate was 49.4%, average patient-based sensitivity and specificity for the detection of lymph-node metastasis were 77.8 and 55.6%, and average lymph-node group-based sensitivity and specificity were 39.4 and 92.6%. There were no interobserver differences among the three readers (P < 0.0001). Mean ADC of detected primary tumors was 1.26 ± 0.29×10⁻³ mm²/s. Mean ADC of metastatic lymph nodes (1.46 ± 0.35×10⁻³ mm²/s) was significantly higher (P < 0.0001) than that of nonmetastatic lymph nodes (1.15 ± 0.24 mm²/s), but ADCs of both groups overlapped. In conclusion, this study suggests that DWI only has a limited role in detecting esophageal cancer and nodal staging.     

Is Diffusion-Weighted MRI Useful for Differentiation of Small Non-Necrotic Cervical Lymph Nodes in Patients with Head and Neck Malignancies?

Objective

To evaluate the usefulness of measuring the apparent diffusion coefficient (ADC) in diffusion-weighted magnetic resonance imaging to distinguish benign from small, non-necrotic metastatic cervical lymph nodes in patients with head and neck cancers.

Materials and Methods

Twenty-six consecutive patients with head and neck cancer underwent diffusion-weighted imaging (b value, 0 and 800 s/mm²) preoperatively between January 2009 and December 2010. Two readers independently measured the ADC values of each cervical lymph node with a minimum-axial diameter of ≥ 5 mm but < 11 mm using manually drawn regions of interest. Necrotic lymph nodes were excluded. Mean ADC values were compared between benign and metastatic lymph nodes after correlating the pathology.

Results

A total of 116 lymph nodes (91 benign and 25 metastatic) from 25 patients were included. Metastatic lymph nodes (mean ± standard deviation [SD], 7.4 ± 1.6 mm) were larger than benign lymph nodes (mean ± SD, 6.6 ± 1.4 mm) (p = 0.018). Mean ADC values for reader 1 were 1.17 ± 0.31 × 10^-3 mm²/s for benign and 1.25 ± 0.76 × 10^-3 mm²/s for metastatic lymph nodes. Mean ADC values for reader 2 were 1.21 ± 0.46 × 10^-3 mm²/s for benign and 1.14 ± 0.34 × 10^-3 mm²/s for metastatic lymph nodes. Mean ADC values between benign and metastatic lymph nodes were not significantly different (p = 0.594 for reader 1, 0.463 for reader 2).

Conclusion

Measuring mean ADC does not allow differentiating benign from metastatic cervical lymph nodes in patients with head and neck cancer and non-necrotic, small lymph nodes.     

Characterization of pediatric head and neck masses with diffusion-weighted MR imaging

We aimed to assess the clinical usefulness of the ADCs calculated from diffusion-weighted echo-planar MR images in the characterization of pediatric head and neck masses. This study included 78 pediatric patients (46 boys and 32 girls aged 3 months–15 years, mean 6 years) with head and neck mass. Routine MR imaging and diffusion-weighted MR imaging were done on a 1.5-T MR unit using a single-shot echo-planar imaging (EPI) with a b factor of 0.500 and 1,000 s mm⁻². The ADC value was calculated. The mean ADC values of the malignant tumours, benign solid masses and cystic lesions were (0.93 ± 0.18) × 10⁻³, (1.57 ± 0.26) × 10^–3 and (2.01 ± 0.21 )× 10^–3 mm² s⁻¹, respectively. The difference in ADC value between the malignant tumours and benign lesions was statistically significant (p < 0.001). When an apparent diffusion coefficient value of 1.25 × 10^–3 mm² s⁻¹ was used as a threshold value for differentiating malignant from benign head and neck mass, the best results were obtained with an accuracy of 92.8%, sensitivity of 94.4%, specificity of 91.2%, positive predictive value of 91% and negative predictive value of 94.2%. Diffusion-weighted MR imaging is a new promising imaging approach that can be used for characterization of pediatric head and neck mass.     

Diagnostic accuracy of the apparent diffusion coefficient in differentiating benign from malignant uterine endometrial cavity lesions: initial results

Our purpose is to evaluate the diagnostic accuracy of apparent diffusion coefficient (ADC) measurement in differentiating malignant from benign uterine endometrial cavity lesions. We retrospectively evaluated 25 uterine endometrial cavity lesions in 25 female patients: endometrial carcinoma (n = 11), carcinosarcoma (n = 2), submucosal leiomyoma (n = 8), and endometrial polyp (n = 4). Diffusion-weighted images were performed at 1.5 T with b factors of 0–1,000/mm². The region of interest was defined within the tumor on T2-weighted EPI image and then manually copied to an ADC map. Thereby, the ADC value was obtained. We compared ADC values between malignant and benign lesions using Student’s t-test. The mean and standard deviation of ADC values (×10⁻³ mm²/s) were as follows: endometrial carcinoma, 0.98±0.21; carcinosarcoma, 0.97±0.02; submucosal leiomyoma, 1.37±0.28; and endometrial polyp, 1.58±0.45. The ADC values differed significantly between malignant (0.98±0.19) and benign lesions (1.44±0.34) (P < 0.01). We defined malignant tumors as cases with an ADC value less than 1.15 × 10⁻³ mm²/s for obtaining the highest accuracy. Sensitivity, specificity, and accuracy were 84.6%, 100%, and 92%, respectively. ADC measurement can provide useful information in differentiating malignant from benign uterine endometrial cavity lesions.     

Node-by-node correlation between MR and PET/CT in patients with uterine cervical cancer: diffusion-weighted imaging versus size-based criteria on T2WI

The purpose of the study was to perform a node-by-node comparison of an ADC-based diagnosis and various size-based criteria on T2-weighted imaging (T2WI) with regard to their correlation with PET/CT findings in patients with uterine cervical cancer. In 163 patients with 339 pelvic lymph nodes (LNs) with short-axis diameter >5 mm, the minimum apparent diffusion coefficient (ADC), mean ADC, short- and long-axis diameters, and ratio of long- to short-axis diameters (L/S ratio) were compared in PET/CT-positive and -negative LNs. On PET/CT, 118 (35%) LNs in 58 patients were positive. The mean value of minimum and mean ADCs, short- and long-axis diameters, and L/S ratio were different in PET/CT-positive (0.6436 × 10⁻³ mm²/s, 0.756 × 10⁻³ mm²/s, 10.3 mm, 13.2 mm, 1.32, respectively) and PET/CT-negative LNs (0.8893 × 10⁻³ mm²/s, 1.019 × 10⁻³ mm²/s, 7.4 mm, 11.0 mm, 1.49, respectively) (P < 0.05). The Az value of the minimum ADC (0.864) was greater than those of mean ADC (0.836), short-axis diameter (0.764), long-axis diameter (0.640) and L/S ratio (0.652) (P < 0.05). The sensitivity and accuracy of the minimum ADC (86%, 82%) were greater than those of the short-axis diameter (55%, 74%), long-axis diameter (73%, 58%) and L/S ratio (52%, 66%) (P < 0.05). ADC showed superior correlation with PET/CT compared with conventional size-based criteria on T2WI.     

Diffusion-weighted MRI in cervical cancer

The purpose was to investigate the potential value of apparent diffusion coefficient (ADC) measurement with MRI in the assessment of cervix cancer. Diffusion-weighted MRI was performed in 47 patients with cervical carcinoma undergoing chemoradiation therapy and 26 normal controls on a 1.5-T system with a b-value of 600 s/mm². FIGO stage, tumor volume, nodal status, interstitial fluid pressure (IFP) and oxygen measurements were recorded. Response was defined as no visible tumor 3–6 months following completion of therapy. The average median ADC (mADC) of cervical carcinomas (1.09±0.20×10⁻³ mm²/s) was significantly lower than normal cervix (2.09±0.46×10⁻³ mm²/s) (P<0.001). There was no correlation between mADC, nodal status, tumor volume, IFP or oxygen measurements. mADC was significantly lower in FIGO stages T1b/T2a (0.986 × 10⁻³ mm²/s) compared to T2b (1.21×10⁻³ mm²/s) and T3/T4 (1.10×10⁻³ mm²/s) (P<0.001). In patients with squamous carcinomas the 90th percentile of ADC values was lower in responders than non-responders (P<0.05). Median ADC in cervix carcinoma is significantly lower compared to normal cervix. ADC may have predictive value in squamous tumors, but further long-term study will determine the ultimate clinical utility.     

Diagnostic ability of apparent diffusion coefficients for lymphomas and carcinomas in the pharynx

We evaluated the diagnostic ability of diffusion-weighted imaging for the differentiation between lymphomas and carcinomas in the pharynx and between carcinomas with different histological types in the pharynx. T1-weighted, fat-suppressed T2-weighted, and diffusion-weighted MR imaging was performed on 14 patients with pharyngeal lymphomas, 26 patients with carcinomas of the pharynx, 5 patients with adenoidal hypertrophy, and 22 patients with normal tonsils. Apparent diffusion coefficients (ADCs) were determined by using two b factors (500 and 1,000 s/mm²). The ADCs of lymphomas were significantly smaller (0.454 ± 0.075 × 10⁻³ mm²/s) than those of carcinomas (0.863 ± 0.238 × 10⁻³ mm²/s). The ADCs of poorly differentiated and undifferentiated carcinomas (0.691 ± 0.149 × 10⁻³ mm²/s) were significantly smaller than those of moderately differentiated and well-differentiated carcinomas (0.971 ± 0.221 × 10⁻³ mm²/s), but were significantly larger than those of lymphomas. When an ADC smaller than 0.560 × 10⁻³ mm²/s was used for predicting lymphomas, we obtained the highest accuracy of 96%, with 100% sensitivity and 94% specificity, 86% positive predictive value, and 100% negative predictive value. Therefore, ADC measurements effectively differentiate lymphomas from carcinomas in the pharynx and could be a useful adjunct to biopsy-based development of treatment planning.     

Diffusion-weighted MRI in cystic or necrotic intracranial lesions

Our purpose was to investigate the signal intensities of cystic or necrotic intracranial lesions on diffusion-weighted MRI (DWI) and measure their apparent diffusion coefficients (ADC). We examined 39 cystic or necrotic intracranial lesions in 33 consecutive patients: five malignant gliomas, seven metastases, two other necrotic tumours, a haemangioblastoma, three epidermoids, an arachnoid cyst, seven pyogenic abscesses, 12 cases of cysticercosis and one of radiation necrosis. DWI was performed on a 1.5 T unit using a single-shot echo-planar spin-echo pulse sequence with b 1000 s/mm². The signal intensity of the cystic or necrotic portion on DWI was classified by visual assessment as markedly low (as low as cerebrospinal fluid), slightly lower than, isointense with, and slightly or markedly higher than normal brain parenchyma. ADC were calculated in 31 lesions using a linear estimation method with measurements from b of 0 and 1000 s/mm². The cystic or necrotic portions of all neoplasms (other than two metastases) gave slightly or markedly low signal, with ADC of more than 2.60 × 10⁻³ mm²/s. Two metastases in two patients showed marked high signal, with ADC of 0.50 × 10⁻³ mm²/s and 1.23 × 10⁻³ mm²/s, respectively. Epidermoids showed slight or marked high signal, with ADC of less than 1.03 × 10⁻³ mm²/s. The arachnoid cyst gave markedly low signal, with ADC of 3.00 × 10⁻³ mm²/s. All abscesses showed marked high signal, with ADC below 0.95 × 10⁻³ mm²/s. The cases of cysticercosis showed variable signal intensity; markedly low in five, slightly low in three and markedly high in four. Received: 17 November 1999/Accepted: 3 February 2000     

Optimization of b value in diffusion-weighted MRI for the differential diagnosis of benign and malignant vertebral fractures

Objective The objective was to explore the optimal b value in diffusion-weighted imaging (DWI) of MRI for differential diagnosis of benign and malignant vertebral fractures. Materials and Methods Thirty-four consecutive patients with vertebral compression fractures underwent sagittal diffusion-weighted imaging (DWI) with different b values. The group included 14 patients with 18 benign vertebral fractures due to osteoporosis and/or trauma and 20 patients with 27 malignant vertebral fractures due to malignancy. The quality of the images was analyzed qualitatively on a three-point scale and quantitatively by measurement of the signal-to-noise ratio (SNR). Apparent diffusion coefficient (ADC) values were also calculated. Results Smaller b values correlated with better DW image quality. We found significant differences in the qualitative points values among the DW images with different b values (F = 302.18, p < 0.001). The mean SNR of the images ranged from 21.75 ± 3.64 at a b value of 0 s/mm² to 5.31 ± 3.17 at a b value of 800 s/mm². The SNR of DWI with a b value of 300 s/mm² (18.62 ± 2.47) was significantly different from that with other b values (p < 0.01). The mean combined ADC values of malignant fractures were significantly lower than those of benign ones on DWI with a b value of 300 s/mm² (t = 9.097, p < 0.01). Four cases of benign vertebral fractures were misdiagnosed as being malignant when b values of 0 s/mm² and 100 s/mm² were used. Conclusions When DWI with multiple b values is used to differentiate benign from malignant vertebral compression fractures, b values within the range of around 300 s/mm² are recommended, taking into account both SNR and diffusion weighting of water molecules.     

Combined use of T2-weighted and diffusion-weighted 3-T MR imaging for differentiating uterine sarcomas from benign leiomyomas

The objective of our study was to compare diffusion-weighted imaging (DWI) alone and DWI combined with T2-weighted MRI for the differentiation of uterine sarcomas from benign leiomyomas. T2-weighted imaging and DWI were performed in 103 patients with 103 myometrial tumours, including 8 uterine sarcomas and 95 benign leiomyomas on 3-T MR imaging. The signal intensity (SI) of the tumour on T2-weighted images was quantified as the tumour–myometrium contrast ratio (TCR) by using the following formula: (SI_tumour − SI_myometrium)/SI_myometrium. The TCR or apparent diffusion coefficient (ADC) value alone and then the ADC value combined with T2-weighted imaging were evaluated for differentiation between sarcomas and leiomyomas. The mean ADC value of sarcomas was 0.86 ± 0.11 × 10⁻³ m²/s, which was significantly lower than that of leiomyomas 1.18 ± 0.24 × 10⁻³ m²/s; however, there was a substantial overlap. The mean TCR of sarcomas was 0.66 ± 0.71, which was significantly higher than that of the leiomyomas, –0.37 ± 0.34; however, again, there was a considerable overlap. When ADC was less than 1.05 × 10⁻³ mm²/s and TCR was greater than 0 this condition was considered to confirm a sarcoma; a combination of ADC and TCR achieved a significant improvement without any overlap between sarcomas and leiomyomas (sensitivity 100%, specificity 100%). Our preliminary results indicate that combined DWI and T2-weighted MR imaging is better than DWI alone in the differentiation of uterine sarcomas from benign leiomyomas.     

Quantitative diffusion-weighted magnetic resonance imaging in the evaluation of parotid gland masses: a study with histopathological correlation

We evaluated the quantitative diffusion-weighted magnetic resonance imaging (DW-MRI) for parotid masses. Seventy-five patients with 81 focal parotid masses were included. Following DW-MRI, 73 masses underwent surgical biopsy/resection, 6 underwent ultrasonography-guided fine-needle aspiration, and 2 underwent both procedures. The mean apparent diffusion coefficient (ADC) of benign tumors (n= 49, 1.72×10^? 3 mm²/s) was higher than that of malignant tumors (n= 32, 1.05×10^? 3 mm²/s) (P<.001). ADC was 2.15×10^? 3 mm²/s for pleomorphic adenomas, which was higher than that for other tumors (P<.001 for all). ADC cutoff was 1.315 for distinguishing between pleomorphic adenomas and others including malignant tumors. Therefore, DW-MRI may be useful for distinguishing between pleomorphic adenomas and other parotid masses.     

2-[Fluorine-18]-fluoro-2-deoxy-<Emphasis Type="SmallCaps">d</Emphasis>-glucose positron emission tomography/computed tomography versus whole-body diffusion-weighted MRI for detection of malignant lesions: initial experience

Objectives The new magnetic resonance whole body diffusion-weighted imaging with background body signal suppression (DWIBS) uses short tau inversion recovery-echo planar imaging sequence under normal respiration. DWIBS is different from 2-[fluorine-18]-fluoro-2-deoxy-d-glucose positron emission tomography (¹⁸F-FDG PET) imaging in technology, but their images are similar. We compared the two modalities regarding the detection and characterization of malignant tumors. Methods DWIBS and ¹⁸F-FDG PET/computed tomography (CT) were performed on 16 cancer patients on the same day. The diagnoses were the following: lung cancer (n = 12), colon cancer (n = 2), breast cancer (n = 1), and pulmonary metastasis (n = 1). A total of 27 malignant tumors (15 lung cancer, 5 pulmonary metastases of parathyroid cancer, 3 pulmonary metastases of lung cancer, 3 colon cancer, 1 breast cancer) and seven reference organs around malignant lesions (two liver regions, four normal lymph nodes, one muscle region) were evaluated visually and quantitatively using the apparent diffusion coefficient (ADC) (×10⁻³ mm²/s) and standardized uptake value (SUV). Results Twenty-five (92.6%) of the 27 malignant lesions were detected visually with DWIBS imaging in contrast to 22 malignant tumors (81.5%) with ¹⁸F-FDG PET/CT imaging. The quantitative evaluation showed that there was a significant difference between the mean SUVs of the reference organs (n = 7, 1.48 ± 0.62) and the malignant (n = 22, 5.36 ± 2.80) lesions (P < 0.01). However, there was no significant difference between the mean ADCs of the reference organs (n = 7, 1.54 ± 0.24) and the malignant (n = 25, 1.18 ± 0.70) lesions. Conclusions DWIBS can be used for the detection of malignant tumors or benign tumors; however, it may be difficult to differentiate between benign and malignant lesions by ADC.     

Diffusion-weighted MR imaging (DWI) in the evaluation of epidural spinal lesions

Introduction Epidural spinal cord compression is one of the most critical emergency conditions requiring medical attention and requires prompt and adequate treatment. The aim of our study was to assess the role of diffusion-weighted magnetic resonance (MR) imaging (DWI) in the diagnosis and differentiation of epidural spinal lesions. Methods Three patients with epidural lymphoma, two with sarcoma and three with epidural metastatic disease were imaged on a 1.5T MRI unit. DWI was performed using navigated, interleaved, multi-shot echo planar imaging (IEPI). Three region of interest (ROI)-measurements were obtained on corresponding apparent diffusion coefficient (ADC) maps, and the mean ADC value was used for further analysis. The cellularity of tumors was determined as the N/C ratio (nucleus/cytoplasma ratio) from histological samples. The ADC values and N/C ratios of lesions were compared using a Kruskal-Wallis test. Results The mean ADC of the lymphomas was 0.66 × 10⁻³ mm²/s, that of the sarcomas was 0.85 × 10⁻³ mm²/s and the ADC of the metastatic lesions was 1.05 × 10⁻³ mm²/s; however, the differences were not statistically significant. Mean N/C ratios in the lymphoma, sarcomas and metastases were 4:1, 2:1, and 2.6:1, respectively, with a statistically significant difference between the groups (p < 0.025). Conclusion Although not statistically significant due to the small patient sample, our results clearly show a tendency toward decreased diffusivity in neoplastic lesions with higher cellularity. The data from our study suggest that DWI is a feasible and potentially useful technique for the evaluation of epidural lesions that cause spinal cord compression on a per-patient basis.     

Role of diffusion-weighted MR imaging in assessing malignant versus benign skull-base lesions

Purpose

This study was done to assess the role of diffusion-weighted magnetic resonance (MR) imaging in assessing malignant versus benign skull lesions.

Materials and methods

A retrospective analysis was undertaken of 45 patients (26 male, 19 female; age range 14?C68 years, mean age 39 years) with skull-base lesions. Diffusion-weighted MR images were acquired with a bfactor of 500 and 1,000 s/mm² using single-shot echoplanar imaging. Apparent diffusion coefficient (ADC) maps were reconstructed, and the ADC value of the lesion was calculated.

Results

The mean ADC value of malignant tumours was (1.002±0.21)×10^?3 mm²/s and that of benign tumours was (1.63±0.29)×10^?3 mm²/s. There was a statistically significant difference (p=0.001) in the ADC value of malignant skull-base tumours versus benign lesions. Selection of (1.3)×10^?3mm²/s as a threshold value of ADC for differentiating benign from malignant tumours yielded the best result, with an accuracy of 94%, sensitivity of 94%, specificity of 93%, positive predictive value of 93%, negative predictive value of 94% and area under the curve of 0.932.

Conclusions

We conclude that diffusion-weighted MR imaging is a promising, noninvasive approach that can be used to characterise skull-base lesions in that it can help differentiate malignant tumours from benign lesions and evaluate the pathological grading of malignant tumours.     

High b-value diffusion-weighted MRI for detecting gallbladder carcinoma: preliminary study and results

The aim of this preliminary study was to retrospectively evaluate the usefulness of high b-value diffusion-weighted MR imaging (DWI) in the detection of gallbladder carcinoma. Fifteen patients with gallbladder carcinoma and 14 other patients were included in this study. All patients and subjects underwent DWI, and images were evaluated by two radiologists. The area under the receiver operating characteristic curve (AUC), apparent diffusion coefficient (ADC) measurement, sensitivity and specificity were calculated. An AUC yielded 0.980 (95% CI, 0.850–0.999) and 0.941 (95% CI, 0.791–0.990) for the two radiologists. The mean sensitivity and specificity were 83.3% and 100%, respectively. The mean ADC value of gallbladder carcinoma was (1.28 ± 0.41)×10⁻³ mm²/s and that of control gallbladder lesions was (1.92 ± 0.21)×10⁻³ mm²/s (P < 0.01). According to the results of our preliminary study, high b-value DWI might be a useful tool for detecting gallbladder carcinoma by measuring the ADC value and direct visual assessment.     

Quantitative diffusion-weighted MR imaging in the differential diagnosis of breast lesion

The role of diffusion-weighted magnetic resonance imaging (DWI) to differentiate breast lesions in vivo was evaluated. Sixty women (mean age, 53 years) with 81 breast lesions were enrolled. A coronal echo planar imaging (EPI) sequence sensitised to diffusion (b value=1,000 s/mm²) was added to standard MR. The mean diffusivity (MD) was calculated. Differences in MD among cysts, benign lesions and malignant lesions were evaluated, and the sensitivity and specificity of DWI to diagnose malignant and benign lesions were calculated. The diagnosis was 18 cysts, 21 benign and 42 malignant nodules. MD values (mean±SD ×10⁻³ mm²/s) were (1.48±0.37) for benign lesions, (0.95±0.18) for malignant lesions and (2.25±0.26) for cysts. Different MD values characterized different malignant breast lesion types. A MD threshold value of 1.1×10⁻³ mm²/s discriminated malignant breast lesions from benign lesions with a specificity of 81% and sensitivity of 80%. Choosing a cut-off of 1.31×10⁻³ mm²/s (MD of malignant lesions -2 SD), the specificity would be 67% with a sensitivity of 100%. Thus, MD values, related to tumor cellularity, provide reliable information to differentiate malignant breast lesions from benign ones. Quantitative DWI is not time-consuming and can be easily inserted into standard clinical breast MR imaging protocols.     

Apparent diffusion coefficient in vasogenic edema and reactive astrogliosis

Introduction Distinguishing between vasogenic edema and reactive astrogliosis may be difficult in some instances. This study was performed to test the hypothesis that diffusion-weighted (DW) imaging with apparent diffusion coefficient (ADC) maps can be used to differentiate these two types of changes. Methods The study population included 11 patients with perilesional vasogenic edema and 11 patients with gliosis examined with conventional MR imaging and DW imaging. The signal intensities of conventional pulse sequences and ADC values were calculated in regions of interest placed in the hyperintense edematous or gliotic regions and compared with those of normal-appearing white matter. Signal intensity ratios and ADC values in gliosis were compared with those in vasogenic edema using the Mann-Whitney U-test. Results While considerable overlap was present for signal intensity ratios on conventional MR images, areas of gliosis demonstrated significantly higher ADC values (1.76 ± 0.09 × 10⁻³ mm²/s) than areas of vasogenic edema (1.35 ± 0.06 × 10⁻³ mm²/s; P < 0.0001) without overlap. Conclusion ADC values are helpful in differentiating reactive gliosis from vasogenic edema.