Role of diffusion weighted MRI in differentiating typical from atypical meningiomas at 1.5 and 3T MRI

Purpose

Atypical and malignant meningiomas are considered to have a higher rate of recurrence and show aggressive behavior compared to benign variety. The purpose of our study was to study the role of diffusion weighted imaging and determination of apparent diffusion coefficient (ADC) values and ADC ratios to differentiate typical meningiomas from atypical/malignant variety at 1.5 and 3T MRI.

Materials and methods

A total of 94 adult patients (48 patients at 3T and 46 patients at 1.5T) with pathologically proven meningiomas were retrospectively evaluated on conventional and diffusion weighted MRI. The signal intensity of the lesions on DW imaging was evaluated. ADC values and ADC ratios were calculated from lesion and contralateral normal white matter.

Results

94 lesions comprising of 66 benign and 28 atypical meningiomas were evaluated. The mean ADC values at 3T MRI were 0.82 ± 0.12 × 10⁻³ in benign (typical) meningiomas and 0.68 ± 0.10 × 10⁻³ in atypical meningiomas. At 1.5T, the mean ADC values of benign meningiomas were 0.83 ± 0.11 × 10⁻³ and 0.70 ± 0.09 × 10⁻³ in atypical meningiomas. The mean ADC ratios were 1.08 ± 0.17 and 0.85 ± 0.15 for benign and atypical meningiomas respectively. There was a statistically significant difference between the mean ADC ratios and the mean ADC values of typical and atypical meningiomas (P < 0.001) at both 1.5T and 3T MRI.

Conclusion

DWI with calculation of apparent diffusion coefficient (ADC) values and ADC ratios has a potential role in differentiating benign from atypical meningiomas at both 1.5 and 3T MRI. The differences in mean ADC values between benign and atypical meningiomas were similar at both 1.5 and 3T MRI.     

The diagnostic value of diffusion weighted imaging in patients with meningioma

Purpose

This study aims to determine the use of diffusion-weighted (DW) magnetic resonance imaging (MRI) in differentiating typical and atypical meningiomas.

Patients and methods

In total, 31 patients aged 37–77 years with meningiomas were included in this study. Using routine MRI sequences, the meningiomas were diagnosed and DW images were performed using factor of b-0 and b-1000. Apparent diffusion coefficient (ADC) values were measured in the lesion, in the normal area of brain parenchyma. Student t-test was used for statistical analysis. P < 0.05 was considered significant.

Results

Showed that the mean ADC of atypical/malignant meningiomas (0.42–0.69 × 10⁻³ mm²/s; P < .0001) was significantly lower compared with benign meningiomas (0.72–1.5 × 10⁻³ mm²/s). Mean NADC ratio in the atypical/malignant group (0.61) was also significantly lower than the benign group (1.21; P < .0001), without overlap between groups. The difference between the ADC values of the subtypes of typical meningiomas was insignificant.

In conclusion

Typical meningiomas have higher ADC values than atypical cases. DW MRI may be of help in differentiating typical and atypical meningiomas.     

Is diffusion-weighted imaging useful in grading and differentiating histopathological subtypes of meningiomas?

Purpose

Meningiomas are mostly benign, however atypical or malignant subtypes with more aggressive clinical course and higher recurrence rates can also be seen. The purpose of this study was to determine whether histopathological subtypes of meningiomas could be assessed preoperatively using apparent diffusion coefficient (ADC) values.

Materials and methods

Conventional magnetic resonance (MR) and diffusion-weighted (DW) imaging of 177 adult patients with pathologically proven meningiomas were retrospectively evaluated. Tumor size and the degree of associated edema were noted. The signal intensity of the lesions on DW imaging was evaluated and graded. Mean ADC values were obtained as the mean of measurements from three regions of interests within the mass. ADC ratios of meningioma/contralateral normal appearing subcortical parietal white matter were also calculated.

Results

The histopathological analysis revealed 135 benign, 37 atypical and 5 malignant lesions. With classification according to the subtype, the mean ADC values and ratios of benign meningiomas were as 0.99 ± 0.12 × 10⁻³ mm²/s and 1.22 ± 0.07, respectively. ADC values for atypical and malignant groups were both 0.84 ± 0.1 × 10⁻³ mm²/s. The ADC ratios were 1.05 ± 0.1 and 0.96 ± 0.2 for atypical and malignant subtypes, respectively. There was no statistically significant difference between the mean ADC ratios of the three subtypes (ANOVA test; P ≥ 0.05). Gender, age of the patients and tumor size showed no statistically significant difference between the different histological groups.

Conclusion

DW MR imaging was not found to have any additional value in determining histological behaviour nor in differentiating histopathological subtypes of meningiomas.     

Role of diffusion-weighted imaging with ADC mapping and in vivo H-MR spectroscopy in thyroid nodules

Purpose

To evaluate the role of the combined techniques of apparent diffusion coefficient (ADC) generated from diffusion-weighted magnetic resonance (MR) imaging (DWI) and metabolite spectrum acquired by magnetic resonance spectroscopy (MRS) in differentiating benign from malignant thyroid nodules.

Materials and methods

Thirty-seven patients with 56 thyroid nodules were evaluated with conventional MRI (T1- & T2-WI), DWI (b value 0.500 s/mm²; ADC values were calculated for the thyroid nodules), and MRS (for the presence or absence of choline peak). The ADC values and MRS findings were correlated with the histopathological results.

Results

The mean ADC of the malignant thyroid nodules (0.89 ± 0.27 × 10⁻³ mm²/s) was significantly lower than that of the mean ADC of the benign thyroid nodules (1.85 ± 0.24 × 10⁻³ mm²/s) (p value <0.0001). ADC value of 1.5 × 10⁻³ mm²/s was used as a cut-off value for differentiation benign from malignant thyroid nodules. The sensitivity, specificity, PPV&NPV of DWI in differentiating benign from malignant thyroid nodules were 94%, 95%, 94% & 95%, respectively (Kappa test 0.84, p value <0.0001), whereas they were 94.7%, 89.2%, 81.8% & 97.1% (Kappa test 0.8, p value <0.0001) with MRS, and 96%, 100%, 100% & 97% (Kappa test 0.96, p value <0.0001) with both DWI and MRS.

Conclusion

Both DWI and MRS are useful diagnostic modalities for characterization and differentiation between benign and malignant thyroid nodules. Our preliminary results showed that combination of DWI with calculated ADC values and metabolite spectrum acquired by MRS add more information to MRI and should be considered as an additional and complementary tool to conventional MRI for differentiating benign from malignant thyroid nodules.     

Apparent diffusion coefficient values as an adjunct to dynamic contrast enhanced MRI for discriminating benign and malignant breast lesions presenting as mass and non-mass like enhancement

Purpose

The purpose of our study was to evaluate the diagnostic value of an imaging protocol that combines dynamic contrast-enhanced MRI (DCE-MRI) and apparent diffusion coefficient (ADC), measured by diffusion weighted MRI, in discriminating benign and malignant breast lesions presenting as mass and non mass like enhancement (NMLE).

Methods and materials

80 patients with 110 breast lesions identified with dynamic contrast MRI. Diffusion-weighted images were obtained at b values of 0 and 750 S/mm², differences in the apparent diffusion coefficients (ADCs) are included in the study and malignant lesions were compared by lesion type (mass or NMLE), and the analysis was performed to evaluate diagnostic performance based on ADC thresholds. All lesions have pathological results. The study has been done retrospectively 50 patients underwent surgical excision with preoperative localization, while the 30 cases underwent stereotactic biopsies either US or mammographically guided techniques specially if associated with micro calcifications.

Results

The mean ADC value of all benign lesions is 1.41 ± 0.36 × 10⁻³ mm²/s, which is higher than the mean ADC of all malignant lesions (1.05 ± 0.30 × 10⁻³ mm²/s, p < 0.05). In the MASS type, the mean ADC is higher in the benign group (1.34 ± 0.30 × 10⁻³ mm²/s) than in the malignant group (1.02 ± 0.29 × 10⁻³ mm²/s, p < 0.01). In the NMLE type, the mean ADC is also higher in the benign group (1.54 ± 0.45 × 10⁻³ mm²/s) than in the malignant group (1.11 ± 0.32 × 10⁻³ mm²/s, p < 0.01). Therefore, benign lesions have higher ADC values than malignant lesions, regardless of the lesion morphology.

Conclusion

Diffusion-weighted MRI shows adequate help in differentiation of benign and malignant masses and lesions with non-mass like enhancement found at breast MRI.     

Diffusion-weighted MR imaging: diagnosing atypical or malignant meningiomas and detecting tumor dedifferentiation

BACKGROUND AND PURPOSE: Atypical and malignant meningiomas are uncommon tumors with aggressive behavior and higher mortality, morbidity, and recurrence compared with benign tumors. We investigated the utility of diffusion-weighted (DW) MR imaging to differentiate atypical/malignant from benign meningiomas and to detect histologic dedifferentiation to higher tumor grade.MATERIALS AND METHODS: We retrospectively compared conventional and DW MR images (b-value 1000 s/mm²) acquired on a 1.5T clinical scanner between 25 atypical/malignant and 23 benign meningiomas. The optimal cutoff for the absolute apparent diffusion coefficient (ADC) and normalized ADC (NADC) ratio to differentiate between the groups was determined by using receiver operating characteristic (ROC) analysis.RESULTS: Irregular tumor margins, peritumoral edema, and adjacent bone destruction occurred significantly more often in atypical/malignant than in benign meningiomas. The mean ADC of atypical/malignant meningiomas (0.66 ± 0.13 × 10⁻³ mm²/s) was significantly lower compared with benign meningiomas (0.88 ± 0.08 × 10⁻³ mm²/s; P < .0001). Mean NADC ratio in the atypical/malignant group (0.91 ± 0.18) was also significantly lower than the benign group (1.28 ± 0.11; P < .0001), without overlap between groups. ROC analysis showed that ADC and NADC thresholds of 0.80 × 10⁻³ mm²/s and 0.99, respectively, had the best accuracy: at the NADC threshold of 0.99, the sensitivity and specificity were 96% and 100%, respectively. Two patients had isointense benign tumors on initial DW MR imaging, and these became hyperintense with the decrease in ADC and NADC below these thresholds when they progressed to atypical and malignant meningiomas on recurrence.CONCLUSIONS: ADC and NADC ratios in atypical/malignant meningiomas are significantly lower than in benign tumors. Decrease in ADC and NADC on follow-up imaging may suggest dedifferentiation to higher tumor grade.

Meningiomas comprise 14%–20% of all intracranial tumors, with a higher incidence of up to 35.2% among Asians and Africans.¹ Although they are generally benign tumors, up to 10% of meningiomas are atypical or malignant, characterized by nuclear disorganization, necrosis, prominent nucleoli, and increased mitoses on histology. Because of their aggressive behavior, atypical/malignant meningiomas are associated with high morbidity and mortality and may invade the adjacent bone and brain parenchyma. They are also more prone to recur in 29%–41% of patients than typical meningiomas, where the recurrence rate is between 7%–20%.² Although typical extra-axial benign meningiomas are easily diagnosed, distinction from more malignant histologic grades by CT or conventional MR imaging is difficult.³ Neuroimaging features, such as heterogeneous appearance, heterogeneous enhancement, marked perilesional edema, irregular cerebral surface, mushrooming on the outer edge of the lesion, and bone destruction, are not unique or reliable for diagnosing atypical/malignant meningiomas.^4–8 A diagnostic method that can differentiate between benign and atypical/ malignant meningiomas would, therefore, be desirable for surgical planning.Diffusion-weighted (DW) MR imaging has been used to study primary brain tumors, including histologic grading of gliomas and response to treatment.^9–16 Only a few studies have evaluated DW MR imaging for grading meningiomas, and although some have found that apparent diffusion coefficient (ADC) of atypical/malignant meningiomas was significantly lower than benign meningiomas,^2,17 others have not duplicated these results.¹⁶ Furthermore, the accuracy and threshold ADC to distinguish between benign and atypical/malignant meningiomas has not been established. There is also a paucity of literature on the DW MR imaging appearance of malignant transformation of benign meningiomas to higher grade tumors. In this study, we compared DW MR imaging between benign and atypical/malignant groups of meningiomas to estimate the cutoff ADC value for optimal tumor grading and describe imaging features of dedifferentiation of benign meningiomas.     

Diagnostic impact of echo planar diffusion-weighted magnetic resonance imaging (DWI) in musculoskeletal neoplastic masses using apparent diffusion coefficient (ADC) mapping as a quantitative assessment tool

Purpose

To evaluate the diagnostic impact of echo planar DW imaging in distinguishing benign from malignant musculoskeletal soft-tissue masses using ADC mapping as a quantitative assessment tool.

Patients and methods

We evaluated 73 tumors (21 bone tumors and 52 soft-tissue tumors). MR examinations were performed with a 1.5-T system. Diffusion-weighted single-shot EPI images were obtained in all patients. Apparent diffusion coefficients (ADCs) were calculated by using b factors of 0 and 1000 s/mm². ADC value measurements were compared with the histopathological findings.

Results

The average ADC of benign tumors was 1.86 ± 0.67 × 10⁻³ mm²/s, and that of malignant soft-tissue tumors was 0.97 ± 0.35 × 10⁻³ mm²/s. ADC value of malignant tumors was significantly lower than that of the benign tumor group (p < 0.0001). The highest ADC value was seen in the case of ganglion cyst (2.8 ± 0.23 × 10⁻³ mm²/s) and cystic neurofibroma (2.5 ± 0.04 × 10⁻³ mm²/s), and juxta cortical enchondroma (2.65 ± 0.36 × 10⁻³ mm²/s) while the lowest one was seen in aggressive fibromatosis (0.37 ± 0.05 × 10⁻³ mm²/s). For malignant soft-tissue masses, the highest ADC value was seen in mesenchymal chondrosarcoma (2.1 ± 0.32) liposarcoma (intermediate grade) (1.4 ± 0.21) while the lowest ADC value was seen in fibrosarcoma (high grade) (0.78 ± 0.14).

Conclusion

MR diffusion provides additional information to the routine MRI sequences rendering it an effective non-invasive tool in differentiating between benign and malignant soft-tissue tumors.     

Characterization of head and neck lesions with diffusion-weighted MR imaging and the apparent diffusion coefficient values

Purpose

The aim of this study was to determine the role of diffusion-weighted MR imaging (DWI) and the apparent diffusion coefficient (ADC) in characterization of head and neck lesions.

Patients and methods

MR imaging including diffusion-weighted sequences was performed on 43 patients presented with head and neck lesions. Images were obtained with a diffusion-weighted factor (b factor) of 100, 500, and 1000 s/mm². ADC maps were reconstructed, and the ADC value of the lesions was calculated.

Results

The mean ADC value of malignant tumors was (1.02 ± 0.22) × 10⁻³ mm²/s (n = 31). The mean ADC value of benign tumors was (1.62 ± 0.27) × 10⁻³ mm²/s (n = 12). The mean ADC of lymphomas was significantly lower than that of carcinomas. The difference in the ADC value between the malignant tumors and benign lesions was statistically significant (p < 0.001). Selection of (1.2) × 10⁻³ mm²/s as a threshold value of ADC for differentiating benign from malignant tumors yielded the best result, with an accuracy of 94%, sensitivity of 95%, specificity of 92%, positive predictive value of 92% and negative predictive value of 94%.

Conclusion

DWI and the ADC measurement are promising, non-invasive imaging approach that can be used for characterization of head and neck lesions. It can help differentiate malignant tumors from benign lesions.     

The role of MR diffusion in differentiation of malignant and benign hepatic focal lesions

Aim

To determine if focal liver masses could be differentiated as benign or malignant by DWI and ADC maps.

Methods and materials

Sixty focal liver lesions were scanned using 1.5 T MRI. DWI was performed with b 0, b 500 and b 1000 gradients with ADC measurements. Comparison of mean ADC values between each benign and malignant lesion was done. Reference standard of diagnosis was obtained by correlating DWI with histopathologic findings and imaging follow-up. The accuracies of DWI and ADC values were assessed with the Student’s t test, and cut-off values were determined with receiver operating characteristic curve analysis.

Results

When ADC value of 1.0 × 10⁻³ mm²/s was used as a threshold value for differentiation of malignant tumors from benign lesions, sensitivity was 90.3%, specificity 78.57% and accuracy 86.7%. The best result was obtained with the use of ADC cut off value (at b 500) of 1.5 × 10⁻³ mm²/s and ADC cut off value (at b 1000) of 1.0 × 10⁻³ mm²/s, with 90.3% sensitivity, 92.86% specificity, 91.1% accuracy, 96.6% positive predictive value and 81.3% negative predictive value.

Conclusion

DWI and ADC map is a useful tool in differential diagnosis of malignant from benign liver lesions.     

Serial diffusion-weighted MRI in patients with hepatocellular carcinoma: Prediction and assessment of response to transarterial chemoembolization. Preliminary experience

Objective

To assess the role of apparent diffusion coefficient (ADC) measured with diffusion-weighted imaging (DWI) in predicting and assessing response of hepatocellular carcinoma (HCC) to transarterial chemoembolization (TACE).

Methods

Thirty-six patients with cirrhosis and untreated HCC who underwent TACE and MRI within 3 months before and after TACE were assessed. MRI included DWI and contrast-enhanced T1-weighted imaging. Two observers measured ADC of HCCs and liver parenchyma on pre- and post-TACE MRIs and measured degree of tumor necrosis on subtracted post-contrast images on post-TACE MRI. Pre-, post-TACE tumor ADC, and changes in tumor ADC (ΔADC) were compared between lesions stratified by degree of tumor necrosis (measured on post-TACE MRI).

Results

Forty seven HCCs were evaluated (mean size 4.4 cm, range 1.0–14.1 cm). HCCs with poor and incomplete response to TACE (<50% necrosis on post-TACE MRI) had significantly lower pre-treatment ADC and lower post TACE ADC compared to HCCs with good/complete response (≥50% necrosis): ADC pre-TACE 1.35 ± 0.42 vs. 1.64 ± 0.39 × 10⁻³ mm²/s (p = 0.042); post-TACE ADC 1.34 ± 0.36 vs. 1.92 ± 0.47 (p = 0.0008). There was no difference in ΔADC values.

Conclusion

This preliminary data suggests that pre-TACE tumor ADC can be used to predict HCC response to TACE.     

Diffusion weighted magnetic resonance imaging of kidneys in children with vesicoureteral reflux

Purpose

The apparent diffusion coefficient (ADC) which obtain from diffusion-weighted magnetic resonance imaging (DWI), is a quantitative parameter representing the renal function and parenchymal damage in some renal disorders. The primary aim of this study was to investigate whether renal tissue alterations associated with vesicoureteral reflux (VUR) can be displayed by DWI. The secondary aim was to assess how ADC values change with age in kidneys with and without VUR.

Materials and methods

This prospective study included 46 patients (8 boys, 38 girls; mean age 7.3 ± 4.2; range 1–15 years) with VUR and 54 control subjects (21 boys, 33 girls; mean age 7.7 ± 5.2; range 1–17 years). All subjects underwent DWI of the kidneys using b value of 600 s/mm² in addition to MR urography. The ADC values of 71 kidneys with VUR were compared with those of 81 kidneys without VUR.

Results

The mean ADC values were (1.93 ± 0.36) × 10⁻³ mm²/s, (1.97 ± 0.24) × 10⁻³ mm²/s, (1.83 ± 0.37) × 10⁻³ mm²/s, (1.98 ± 0.20) × 10⁻³ mm²/s and (2.08 ± 0.42) × 10⁻³ mm²/s in normal kidneys, and in those with grade 1, grade 2, grade 3 and grade 4 VUR, respectively. There was no significant difference in ADC values between kidneys with and without VUR. There was a significant positive correlation between the age and ADC values both in kidneys with and without VUR (r = 0.79, p < 0.001 and r = 0.82; p < 0.001, respectively).

Conclusion

DWI does not reveal probable parenchymal alterations in reflux nephropathy. ADC values increase with age during childhood not only in normal kidneys but also in kidneys with VUR.     

Value of diffusion weighted MRI in differentiating benign from malignant bony tumors and tumor like lesions

Aim of the work

To assess the value of diffusion weighted MRI in the differentiation of benign and malignant bony tumors and tumor like lesions.

Patients and methods

This study included 100 patients (66 males and 34 females). Their ages ranged between 4 and 65 years and the mean age was 31.3 years. The patients were referred to MRI unit from orthopedic surgery and radiotherapy departments and oncology center in Mansoura University hospital. These patients were selected on clinical bases indicating or suggesting presence of bony tumors or tumor-like lesions as a primary diagnosis (e.g. swelling or signs of inflammation). The commonest clinical presentations were pain (n = 71) and swelling (n = 61). Other presentations included limitation of movement (n = 20), back pain (n = 21) and fever (n = 20). More than one symptom may be present in one patient. Patients included in our study were classified according to the pathological and radiological criteria into three groups: Benign bone tumors (14 patients); malignant bone tumors (51 patients); tumor-like lesions (35 patients).

Results

DWI with measurement of ADC values helped in the differentiation of benign and malignant bone tumors, as malignant bone tumors have mean ADC values less than (1.31 × 10⁻³) mm²/s; while benign bone tumors have mean ADC values 1.43 × 10⁻³ mm²/s. Also, mean ADC values helped in differentiating malignant from inflammatory bony lesions as well as cystic from solid bony lesions.

Conclusion

DWI has been proven to be highly useful in the differentiation of benign, malignant bone tumors and tumor like bony lesions. Measurement of ADC values improves the accuracy of the diagnosis of bone tumors and tumor like lesions. Moreover, measurement of ADC values can be used in the follow up of tumors and their response to therapy.     

Comparison of the diagnostic performances of diffusion parameters in diffusion weighted imaging and diffusion tensor imaging of breast lesions

Purpose

To evaluate the diagnostic efficiency of the diffusion parameters measured by conventional diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI) for discrimination of malignant breast lesions from benign lesions and the normal breast.

Materials and methods

The study included 52 women with 55 breast lesions (30 malignant, 25 benign). DTI and DWI were performed complementary to dynamic contrast MRI at 3T. Apparent diffusion coefficient (ADC) of DWI, mean diffusivity (MD) and fractional anisotropy (FA) values of DTI were measured for lesions and contralateral breast parenchyma in each patient. We used b factors of 0, 50, 850, 1000 and 1500 s/mm² for DWI and b 0 and 1000 s/mm² for DTI. ADC, MD and FA values were compared between malignant and benign lesions, and the normal parenchyma by univariate and multivariate analyses.

Results

Diffusion parameters showed no difference according to menopausal status in the normal breast. ADC and MD values of the malignant lesions were significantly lower than benign lesions and normal parenchyma (p = 0.001). The FA showed no statistical significance. With the cut-off values of ≤1.23 × 10⁻³ mm²/s (b 0–1000 s/mm²) and ≤1.12 × 10⁻³ mm²/s (b 0–1500 s/mm²), ADC showed 92.85% and 96.15% sensitivity; 72.22% and 73.52% PPV, respectively. With a cut-off value of ≤1.27 × 10⁻³ mm²/s (b 1000 s/mm²), MD was 100% sensitive with a PPV of 65.90%. Comparing the diagnostic performance of the parameters in DTI with DWI, we obtained similar efficiency of ADC with b values of 0,1000 and 0,1500 s/mm² and MD with a b value of 0, 1000 s/mm² (AUC = 0.82 ± 0.07).

Conclusion

ADC of DWI and MD of DTI values provide significant discriminative factors for benign and malignant breast lesions. FA measurement was not discriminative. Supported with clinical and dynamic contrast MRI findings, DWI and DTI findings provide significant contribution to the final radiologic decision.     

Value of combined real time sonoelastography and apparent diffusion coefficient value measurement in differentiation of enlarged neck lymph nodes

Purpose

To evaluate the role of real-time sonoelastography (UE) and apparent diffusion coefficient (ADC) value measurement in differentiating benign versus malignant enlarged neck lymph nodes.

Materials and methods

This study included 26 patients presented with 32 enlarged neck lymph nodes (LNs), underwent real-time UE and diffusion weighted MRI (DWI). ADC maps are generated from DWI and ADC values were calculated. Both UE and ADC findings were compared with histopathological results.

Results

The LNs were 12 benign lymphadenopathy (37.5%, seen in 10 patients), 10 metastatic (31.25% seen in 8 patients) and 10 lymphoma (31.25%, seen in 8 patients) including 4 LNs with Hodgkin’s lymphoma (HL, seen in 3 patients) and 6 LNs with non Hodgkin’s lymphoma (NHL, seen in 5 patients). On UE 10 of the 12 benign LNs had pattern of 1–2 (83.3%) and 18 of 20 neoplastic LNs (90%) had pattern of 4–5. The mean ADC values of the benign, metastases and lymphoma groups were 1.52 ± 0.37, 0.90 ± 0.15 and 0.72 ± 0.12 × 10⁻³ (mm²/s), respectively.

Conclusion

Combined real-time UE and ADC value measurement are non invasive techniques useful for differentiation of enlarged neck lymph. The combination potentially could reduce unnecessary biopsy especially for elasticity pattern 1–2.     

Diagnostic value of apparent diffusion coefficient to differentiate benign from malignant vertebral bone marrow lesions

Background

Vertebral collapse is a common problem due to benign bone marrow lesions, trauma or malignant process. The diagnosis is often correctly predicted from characteristic imaging appearance. Some vertebral collapses have atypical imaging appearance that may cause diagnostic confusion.

Aim

To evaluate the value of the ADC obtained in DW-MR sequences for the differentiation between benign and malignant bone marrow lesions.

Patients

Sixty patients were included in this study, referred from Neurosurgery and Radiotherapy Departments and proved to have vertebral compression based on conventional MR imaging.

Results

The ADC value resulted in statistically significant characterization between (osteoporotic and post-traumatic collapse) and (malignant vertebral collapse) (P < 0.0001) while there was no statistically significant findings between infective spondylodiscitis and malignant vertebral collapse (P > 0.05). The sensitivity, specificity, PPV, NPD of DWI and ADC values in differentiating benign from malignant vertebral collapse were 100%, 83.3%, 60% and 100% respectively.

Conclusions

ADC values are a useful complementary MRI tool to characterize bone marrow lesions, in order to distinguish acute benign fractures from malignant or infectious bone marrow lesions. However, ADC values are not valuable in order to differentiate malignancy from infection with diagnostic overlap in the subacute traumatic vertebral collapse.     

ADC measurements in diffuse large B-cell lymphoma and follicular lymphoma: a DWI and cellularity study

Purpose

Diffusion-weighted magnetic resonance imaging (DW-MRI) allows quantifying the random motion of water molecules in tissue by means of apparent diffusion coefficient (ADC) measurements. The aim of the study was to determine whether ADC measurements allow discrimination of diffuse large B-cell lymphoma (DLBCL) from follicular lymphoma (FL), and to examine the relationship between cellularity and ADC value of the tumor using DWI.

Materials and methods

Thirty-two patients with histologically proven non-Hodgkin lymphoma (21 with DLBCL and 11 with FL, 17 males and 15 females, mean age 62 ± 13 years) underwent conventional MRI and DWI examination before treatment. The ADC values of DLBCL were compared to those of FL. The ADC value of the tumor was also correlated with the tumor tissue cellularity.

Results

The mean ADC value of DLBCL was not significantly different from that of FL (0.70 ± 0.16 × 10⁻³ mm²/s vs. 0.76 ± 0.12 × 10⁻³ mm²/s, P = 0.21). The cellularity of DLBCL was significantly lower than that of FL (2991 ± 351 cells/view vs. 4412 ± 767 cells/view, P < 0.001). There was no correlation between the ADC value and the tissue cellularity of the tumor in patients with DLBCL and FL.

Conclusion

ADC measurements could not differentiate between DLBCL and FL, and there was no correlation between the ADC value and cellularity of the tumor in patients with DLBCL and FL.     

Diffusion tensor imaging of the median nerve at 3.0 T using different MR scanners: Agreement of FA and ADC measurements

Objective

To assess the agreement of fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values of the median nerve on 3.0 T MR scanners from different vendors.

Materials and methods

IRB approved study including 16 healthy volunteers (9 women; mean age 30.6 ± 5.3 years). Diffusion tensor imaging (DTI) of the dominant wrist was performed on three 3.0 T MR scanners (GE, Siemens, Philips) using similar imaging protocols and vendor-proprietary hard- and software. Intra-, inter-reader and inter-vendor agreements were assessed.

Results

ICCs for intra-/inter-reader agreements ranged from 0.843–0.970/0.846–0.956 for FA, and 0.840–0.940/0.726–0.929 for ADC, respectively.ANOVA analysis identified significant differences for FA/ADC measurements among vendors (p < 0.001/p < 0.01, respectively). Overall mean values for FA were 0.63 (SD ± 0.1) and 0.999 × 10⁻³ mm²/s (SD ± 0.134 × 10⁻³) for ADC. A significant negative measurement bias was found for FA values from the GE scanner (−0.05 and −0.07) and for ADC values from the Siemens scanner (−0.053 and −0.063 × 10⁻³ mm²/s) as compared to the remainder vendors

Conclusion

FA and ADC values of the median nerve obtained on different 3.0 T MR scanners differ significantly, but are in comparison to the standard deviation of absolute values small enough to not have an impact on larger group studies or when substantial diffusion changes can be expected. However, caution is warranted in an individual patient when interpreting diffusion values from different scanner acquisitions     

Neck lymph nodes: Characterization with diffusion-weighted MRI

Purpose

To evaluate the role of diffusion-weighted imaging (DWI) in differentiating the various causes of enlarged neck lymph nodes.

Materials and methods

Thirty-four patients with enlarged neck lymph nodes clinically suggestive of malignancy underwent DWI with b values (0 and 1000). Apparent diffusion coefficient (ADC) maps are generated from DWI and ADC values were calculated for the enlarged lymph nodes and compared with histopathological results.

Results

The patients were divided into nine patients with benign neck lymphadenopathy, 14 patients with metastasis from head and neck cancer and 11 patients with nodal lymphoma. The mean ADC of the benign neck lymph nodes (1.51 ± 0.36 × 10⁻³ mm²/s) was significantly higher than those of the metastatic (0.92 ± 0.13 × 10⁻³ mm²/s) and lymphomatous (0.74 ± 0.14 × 10⁻³ mm²/s) lymph nodes (p < 0.0001) and the mean ADC of the metastatic nodes was significantly higher than that of nodal lymphoma (p = 0.04). The mean ADC of well- and moderately differentiated metastasis (0.98 ± 0.14 × 10⁻³ mm²/s) was significantly higher than that of poorly differentiated metastasis (0.83 ± 0.06 × 10⁻³ mm²/s) (p = 0.03). The mean ADC of non-Hodgkin lymphoma (0.65 ± 0.06 × 10⁻³ mm²/s) was significantly lower than that of Hodgkin lymphoma (0.86 ± 0.11 × 10⁻³ mm²/s) (p = 0.004). The best threshold for differentiating malignant from benign lymph nodes was 1.15 × 10⁻³ mm²/s.

Conclusion

DWI is a non-invasive technique that can help in the identification of the cause of enlarged neck lymph nodes.     

Age-related distribution of vertebral bone-marrow diffusivity

Purpose

To determine age-related diffusivity changes of the lumbar bone marrow by measurement of apparent diffusion coefficient (ADC) values.

Materials and methods

The local ethics committee approved this study and written informed consent was obtained. The study group comprised 88 individuals including 75 healthy volunteers and 13 patients (48 female, 40 male; mean age 36 years, range 0–84 years). The pediatric cases were recruited from patients. Echo-planar diffusion weighted imaging (DWI) was performed with b-values of 50, 400 and 800 s/mm². ADC-values were calculated and measured in the 1st and 2nd vertebral body of the lumbar spine. Correlation between age and ADC-values was analyzed with Spearman's rho test.

Results

The ADC values of the vertebral bone marrow of the lumbar spine showed a significant negative correlation with age (rho = −0.398, p = 0.001). The mean ADC values (×10⁻³ mm²/s) in the age groups 0–29 years (mean age 18.0 years, n = 42) and 30–88 years (mean age 51.6 years, n = 46) were 0.54 ± 0.07 and 0.47 ± 0.08, respectively (p < 0.001, T-test). No significant differences were found between children and young adults.

Conclusion

Bone marrow ADC values of the lumbar spine show a linear decrease with growing age and thereby reflect the gradual changes of cell composition occurring during marrow conversion.     

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.