Correlating apparent diffusion coefficients with histopathologic findings on meningiomas

Purpose

To determine whether the apparent diffusion coefficient (ADC) correlates with histopathologic findings and whether ADC values can be used to differentiate benign from atypical/malignant meningiomas.

Materials and methods

MR images were reviewed retrospectively in 138 patients with meningiomas treated between September 1997 and July 2003. The ADC values were measured in the lesions and peritumoral edema, and the normalized ADC (NADC) ratios were calculated using the formula NADC = ADC of the tumor/ADC of the normal white matter. The ADC findings were compared with the histopathologic findings after resection using the World Health Organization criteria (2007).

Results

Meningiomas were histologically graded as malignant (9%), atypical (14%) and benign (77%). Of the 138 meningiomas, 32 (23%) were atypical (n = 19) or malignant (n = 13), whereas 106 (77%) were typical. The mean ADC values were statistically different between typical and atypical/malignant meningiomas (0.97 ± 0.21 × 10⁻³ mm²/s vs 0.85 ± 0.17 × 10⁻³ mm²/s). The mean NADC ratios were also significantly lower in the atypical/malignant group (1.09 ± 0.23) than in the benign group (1.24 ± 0.25; P = 0.002 < 0.05). The mean ADC values and NADC ratios did not differ significantly among fibrous, meningothelial, transitional and atypical tumors (P > 0.05). The mean ADC values and NADC ratios were higher in the angiomatous and secretory subgroups than in the fibrous, meningothelial, transitional, atypical and malignant subgroups (P < 0.05). The ADC values and NADC ratios were the lowest in the malignant subgroup, and the difference between atypical and malignant meningiomas was statistically significant (P < 0.05).

Conclusions

Meningioma subgroups displayed different ADC values from each other. Thus, ADC values may provide a useful supplement to the information obtained from conventional contrast-enhanced MR imaging, enhancing the ability of medical professionals to differentiate among the subgroups of meningiomas.     

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.     

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.     

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.     

Diagnostic performance of breast MRI with and without the addition of quantitative diffusion weighted imaging

Objective

The purpose of our study was to investigate whether adding diffusion weighted imaging to dynamic contrast-enhanced MRI could improve the diagnostic performance of breast MRI.

Materials and methods

This retrospective study included 86 women with 93 primary and postoperative breast lesions detected on DCE-MRI who underwent subsequent biopsy. The diagnostic performance was calculated for DCE-MRI alone, combined DCE-MRI and quantitative DWI, and for quantitative DWI alone.

Results

Of the 93 lesions, 42 were benign and 51 malignant (5 DCIS, 41 IDC, 2 ILC, 3 NOS). Both DCIS (mean ADC = 1.17 ± 0.12 × 10⁻³ mm²/s) and IDC (mean ADC, 0.98 ± 0.14) exhibited lower mean ADC values than benign lesions (ADC value = 1.72 ± 0.36). Applying an ADC cutoff value of 1.33 increased the specificity and PPV of DCE-breast MRI from 59.5% and 75% to 78.5% and 83.3%, respectively. The specificity and PPV for quantitative DW-MRI alone (73.5% and 83.3%) were close to those broken out from the combined use of DCE and quantitative DW-MRI. However, the sensitivity and NPV of DWI remains lower than that of DCE-MRI.

Conclusion

DWI shows potential for improving the diagnostic performance of breast MRI and may reduce the number of unnecessary biopsies.     

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.     

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.     

Dynamic contrast enhanced MRI in correlation with diffusion weighted (DWI) MR for characterization of ovarian masses

Introduction

Ovarian tumors; are the second most common gynecological tumor and are the fifth commonest tumor in women. It is desirable to preoperatively differentiate benign from malignant tumor to decide whether surgery is required, and which type of surgery is appropriate avoiding unnecessary surgery, adding dynamic contrast and diffusion weighted to conventional images can help in differentiation of benign ovarian tumor from malignant. DWI depends on the fact that water molecules can diffuse freely in low cellular environment, while tissue hyper cellularity causes its restriction. As a result, malignant ovarian tumors due to its hypercellular nature show restriction of diffusion, unlike most benign tumors. This study aims at reviewing and emphasizing the role of dynamic contrast enhanced MRI and diffusion-weighted MR in characterization of ovarian lesions.

Patients and methods

This study was performed on 30 patients referred to the radiology department from surgical department by ovarian masses. Pelvic MR with DWI was done for all patients, DCE-MR was done for 29 out of 30 patients. Twenty-five patients underwent surgery with pathologic correlation. Five patients were put under regular follow up US for 3 months.

Results

The sensitivity of MRI was 99.9% while that of DWI was 100%. The specificity was higher for DWI (75%) compared to conventional MRI (58.3%), as well as the accuracy which was 73.9% for MRI while that of DWI was 86.9%. The mean ADC values for malignant lesions were (0.84 × 10⁻³ ± 0.1 SD mm²/s), while that for benign lesions were (1.8 × 10⁻³ ± 0.5 SD mm²/s), with cut off 1.2 × 10⁻³ and p value = 0.005. Mature teratomas showed restricted diffusion with ADC values 0.8 × 10⁻³ mm²/s (false positive), due to mixed cellularity of the teratoma. Hemorrhagic cysts and endometriomas showed high signal not only on diffusion images but also on corresponding ADC map and ADC values 1.3–1.4 × 10⁻³ (T2 Shine-through). Sensitivity of MRI was 99.9% while that of DCE-MRI was 60%. The specificity was higher for DCE 91% compared to conventional MRI sequences 58.3%, as well as the accuracy which was 73.9% for MRI while that of DCE was 77% and so addition of DCE to the MRI is expected to increase the specificity and the accuracy of examination.

Conclusion

Combination of DWI and DCE to conventional MRI improves the specificity of MRI and thus increasing radiologist’s confidence in image interpretation which will finally reflect on patients’ outcome and prognosis.     

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.     

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.     

Diffusion-weighted MR imaging and ADC measurement in normal prostate,benign prostatic hyperplasia and prostate carcinoma

Purpose

Our aim was to investigate the diffusion-weighted Imaging (DWI) appearance and apparent diffusion coefficient (ADC) values of normal prostatic gland, prostate carcinoma (PCa) and benign prostate hyperplasia (BPH) and to determine the utility of DWI in their characterization.

Materials and methods

During a period of 16 months, 40 consecutive patients, with elevated PSA level and 12 healthy volunteers with no clinical symptoms or history of prostate disease were prospectively evaluated with DWI of the prostate. MRI was performed using a 1.5T MR scanner equipped with a pelvic phased array coil. For anatomical imaging, T2W FSE in the three orthogonal planes, and T1WI in axial plane were obtained. DWI with b values of 0, 300, 500 and 800 s/mm² were performed in axial plane. The results were confirmed by TRUS-guided biopsy or prostatectomy.

Results

Patients ranged in age from 45 to 85 years (mean 66.6 ± 7.9 year). Twenty patients were confirmed to have BPH, whereas 20 patients had PCa. The mean and SD of ADC values for the peripheral zone (PZ), central gland (CG), BPH nodules and PCa were 1.839 ± 0.233, 1.469 ± 0.239, 1.359 ± 0.201 and 0.87 ± 0.13 respectively. The mean ADC value of PCa was significantly lower than that of CG, PZ, and BPH nodule, with p value <0.05.

Conclusion

DW MR imaging characteristics and ADC values can differentiate PCa and BPH. DWI with ADC may be used as a complementary method to conventional MRI in diagnosis of PCa and BPH.     

Diagnostic value of diffusion weighted magnetic resonance image in early ankylosing spondylitis

Background

Diffusion-weighted MRI (DW-MRI) shows the early changes in microscopical movement of water molecules, hence diagnosis of early sacroiliitis which is one of the diagnostic criteria of seronegative spondyloarthropathies.

Objective

To determine the value of DW-MRI in detection of signal characteristics of the sacroiliac joints in patients with early ankylosing spondylitis (AS).

Patients and methods

Fifteen patients with clinically suspected AS, 20 patients with mechanical low back pain and 20 healthy controls underwent conventional MRI and DWI. Apparent diffusion coefficient (ADC) was measured. In addition ten clinically confirmed AS patients underwent whole body-DWI.

Results

Mean ADC values of both sacroiliac joints in AS patients were (0.523 ± 0.15) × 10⁻³ mm²/s in the ilium and (0.502 ± 0.15) × 10⁻³ mm²/s in the sacrum. There was no significant difference between mechanical LBP and healthy controls. But there was a significant difference between AS and LBP patients. Mean ADC value of focal lesions of clinically confirmed AS was 0.965 ± 0.25 × 10⁻³ mm²/s in the sacrum and 0.932 ± 0.31 × 10⁻³ mm²/s in the ilium.

Conclusion

Subchondral bone marrow ADC values of sacroiliac joints allow differentiation between inflammatory and mechanical LBP. Furthermore, it may be helpful in evaluating the efficacy of the treatment and determine disease prognosis.     

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.     

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.     

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.     

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     

Role of quantitative diffusion-weighted MRI and H MR spectroscopy in distinguishing between benign and malignant thyroid nodules

Background and purpose

The imaging characterization of thyroid nodules is mandatory to exclude malignancy. The purpose of this study is to evaluate the role of quantitative diffusion MRI and ¹H MR spectroscopy in differentiation between benign and malignant Thyroid nodules.

Methods

From February 2012 to May 2013, prospective study was conducted on 25 patients with 41 thyroid nodules (11 males, 14 females, age range, 16–74 years with mean 45.3 years) collected from wards and clinics of Internal Medicine and General Surgery Departments, 20 healthy individuals as control cases were included in the study. 1.5-T ¹H-MR spectroscopy (at echo-times (TE) 144 and 35 ms) and diffusion-weighted imaging (b value 0, 250 and 1000 s/mm²) were performed and the results were correlated with histopathological results.

Results

The mean ADC of the malignant thyroid nodules (13 nodules) was 0.59 ± 0.24 × 10⁻³ mm²/s while that of the benign thyroid nodules (28 nodules) was 1.78 ± 0.21 × 10⁻³ mm²/s (p value <0.0001).Choline is present in all malignant nodules (13 nodules) and two benign nodules (mild elevation) while absent in 26 other benign nodules. Choline/creatine ratio in malignant nodules ranged from 1.3 to 5.4, while in two benign nodules it was 0.9 and 1.1.The sensitivity, specificity, PPV, NPV and overall accuracy of diffusion and MRS in differentiating benign from malignant thyroid nodules were 100%, 93%, 96%, 100% and 79%, respectively.

Conclusion

MRS and diffusion WI are useful noninvasive diagnostic modalities in differentiation between benign and malignant thyroid nodules.     

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.     

Atypical idiopathic inflammatory demyelinating lesions (IIDL): Conventional and diffusion-weighted MR imaging (DWI) findings in 42 cases

Introduction

The purpose of this study was to evaluate MR imaging characteristics with conventional and advanced MR imaging techniques in patients with IIDL.

Methods

MR images of the brain in 42 patients (20 male, 22 female) with suspected or known multiple sclerosis (MS) from four institutions were retrospectively analyzed. Lesions were classified into five different subtypes: (1) ring-like lesions; (2) Balo-like lesions; (3) diffuse infiltrating lesions; (4) megacystic lesions; and (5) unclassified lesions.The location, size, margins, and signal intensities on T1WI, T2WI, and diffusion-weighted images (DWI), and the ADC values/ratios for all lesions, as well as the contrast enhancement pattern, and the presence of edema, were recorded.

Results

There were 30 ring-like, 10 Balo-like, 3 megacystic-like and 16 diffuse infiltrating-like lesions were detected. Three lesions were categorized as unclassified lesions.Of the 30 ring-like lesions, 23 were hypointense centrally with a hyperintense rim. The mean ADC, measured centrally, was 1.50 ± 0.41 × 10⁻³ mm²/s. The mean ADC in the non-enhancing layers of the Balo-like lesions was 2.29 ± 0.17 × 10⁻³ mm²/s, and the mean ADC in enhancing layers was 1.03 ± 0.30 × 10⁻³ mm²/s. Megacystic lesions had a mean ADC of 2.14 ± 0.26 × 10⁻³ mm²/s. Peripheral strong enhancement with high signal on DWI was present in all diffuse infiltrating lesions. Unclassified lesions showed a mean ADC of 1.43 ± 0.13 mm²/s.

Conclusion

Restriction of diffusion will be seen in the outer layers of active inflammation/demyelination in Balo-like lesions, in the enhancing part of ring-like lesions, and at the periphery of infiltrative-type lesions.     

Apparent diffusion coefficient for discriminating metastatic from non-metastatic lymph nodes in primary rectal cancer

Objective

To investigate whether the apparent diffusion coefficient (ADC) could be used to discriminate metastatic from non-metastatic lymph nodes (LNs) in patients with primary rectal cancer.

Methods

This study investigated 34 patients (male: 12, female: 22, mean: 62.7, range: 37–82) who underwent 1.5-T MRI with diffusion-weighted imaging (DWI) and subsequent surgical resection. A blinded radiologist measured the ADC value in each regional LN after referring to the T2-weighted images and DWI. The t-test was used to compare the mean ADC values of the metastatic and non-metastatic LNs. A ROC analysis was performed to calculate the diagnostic performance and obtain the optimal cut-off. The histopathological results were used as the reference standard.

Results

114 LNs (46 metastatic and 68 non-metastatic) were matched and analyzed. The mean ADC of the metastatic LNs was significantly lower than that of the non-metastatic LNs (0.9 ± 0.15 × 10⁻³ mm²/s; 1.1 ± 0.22 × 10⁻³ mm²/s, P < 0.0001). The area under the ROC curve was 0.734 (95% confidence interval, 0.644–0.812). When an ADC value of 1.0 × 10⁻³ mm²/s was used as the cut-off, a maximum accuracy of 72% was calculated (sensitivity, 78%; specificity, 67%).

Conclusions

Although ADC could be used to discriminate metastatic from non-metastatic LNs, the diagnostic accuracy is approximately 70%.