Can diffusion weighted imaging distinguish between benign and malignant solid or predominantly solid gynecological adnexal masses?

Objective

To determine the benefit of DWI in diagnosis of benign and malignant solid or predominantly solid gynecological adnexal or ovarian masses.

Material and Methods

This study is carried out on 23 patients with histologically proven solid or predominantly solid adnexal or ovarian masses out of which 5 cases (21.8%) have benign and 18 cases (78.2%) have malignant neoplasms. Among these 19 cases (82.6%) have unilateral disease and 4 cases (17.4%) have bilateral disease which was metastatic ovarian carcinoma.

Result

On DWI, high signal intensity is noted in malignant lesion more frequently than in benign lesion. (P < 0.001) in adnexal lesions, while in ovarian lesions (P = 0.001).The differentiation between benign and malignant adnexal lesions revealed no significant difference in the apparent diffusion coefficient (ADC) value (P = 0.22).

Conclusion

DWI is a helpful tool in differentiation between predominantly solid and solid benign and malignant adnexal lesions because there is an increased frequency of higher signal intensity (diffusion restriction) in malignant lesions.     

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 measurements in the differentiation between benign and malignant neck masses

Aim

Evaluate the role of ADC value measurements in the differentiation between benign and malignant neck masses.

Methods

From April 2011 to February 2013, prospective study was conducted on 30 patients (17 male and 13 female), with the mean age 43.3 ± 6 years. Collected from wards and clinics of General Surgery and Otolaryngology Departments complaining from neck masses. MRI, Diffusion-Weighted Imaging (b value 0, 100, 500 and 1000 s/mm) and ADC value calculation were performed and the results were correlated with histopathological results and/or follow up.

Results

The present study include 30 patients (Lymphadenopathy {(n = 15) (11 as single entity), (4 associated with other entities)}, Focal thyroid swelling (n = 5), Salivary gland masses (n = 3) {Parotitis (1 case), Parotid carcinoma (2 cases)}, Nasopharyngeal masses (n = 5), Oropharyngeal masses (n = 2), Ludwig angina (n = 2) and Laryngeal masses (n = 2).The mean ADC of the malignant neck masses was (0.699 + 0.267 × 10^-3 mm²/s) while that of the benign masses was (1.879 + 0.751 × 10^-3 mm²/s).The results confirmed by biopsy in 23 cases and follow up (7 cases).The sensitivity, specificity, PPV, NPV and overall accuracy of quantitative diffusion WI in differentiating benign from malignant neck masses were 95.4%, 83.3%, 95.4%, 83%, and 92%.

Conclusion

ADC value calculation are promising noninvasive imaging approach that can be used in distinguishing between benign and malignant neck masses. Benign lesions have higher mean ADC values than malignant lesions, the cutoff value was 1.25 × 10^-3 mm²/s while 0.8 × 10^-3 mm²/s in thyroid lesions.     

Utility and limitations of 3-Tesla diffusion-weighted magnetic resonance imaging for differentiation of renal tumors

Objective

To investigate utility and limitations of 3-Tesla diffusion-weighted (DW) magnetic resonance imaging (MRI) for differentiation of benign versus malignant renal lesions and renal cell carcinoma (RCC) subtypes.

Materials and methods

Sixty patients with 71 renal lesions underwent 3 Tesla DW-MRI of the kidney before diagnostic tissue confirmation. The images were retrospectively evaluated blinded to histology. Single-shot echo-planar imaging was used as the DW imaging technique. Apparent diffusion coefficient (ADC) values were measured and compared with histopathological characteristics.

Results

There were 54 malignant and 17 benign lesions, 46 lesions being small renal masses ≤4 cm. Papillary RCC lesions had lower ADC values (p = 0.029) than other RCC subtypes (clear cell or chromophobe). Diagnostic accuracy of DW-MRI for differentiation of papillary from non-papillary RCC was 70.3% resulting in a sensitivity and specificity of 64.3% (95% CI, 35.1–87.2) and 77.1 (95% CI, 59.9–89.6%). Accuracy increased to 83.7% in small renal masses (≤4 cm diameter) and sensitivity and specificity were 75.0% and 88.5%, respectively. The ADC values did not differ significantly between benign and malignant renal lesions (p = 0.45).

Conclusions

DW-MRI seems to distinguish between papillary and other subtypes of RCCs especially in small renal masses but could not differentiate between benign and malignant renal lesions. Therefore, the use of DW-MRI for preoperative differentiation of renal lesions is limited.     

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.     

Can diffusion weighted image and apparent diffusion coefficient (ADC) differentiate benign from malignant cervical adenopathy?

Background

Cervical adenopathy is a common problem and the differentiation of benign and malignant node is of crucial importance for therapy management.

Objective

This prospective study aimed to know if Diffusion weighted images (DWI) and apparent diffusion coefficient (ADC) can differentiate benign from malignant cervical lymphadenopathy.

Patients and methods

Thirty patients with cervical adenopathy were included in this study. Doppler ultrasound, DWI and ADC maps were automatically reconstructed and used for the measurement of ADC values.

Results

The sensitivity and specificity of the RI cut-off value <0.69 in differentiation between benign and malignant cervical L.Ns was 88.8% and 71.4%, respectively. The optimal ADC cut off value for differentiation between benign and malignant lymph nodes was ?1.0 × 10⁻³ mm²/s with an accuracy 96.7%, a sensitivity 100%, a specificity 88.9%, PPV 95.4% and NPV 100% and statistically significant P-value = 0.000.

Conclusion

DWI and ADC were useful for differentiation between benign and malignant cervical lymphadenopathy and recommended to decrease the need of invasive biopsies. However, CDUS techniques can be used as preliminary technique but, they had potential pitfalls in diagnosis of malignant cervical lymphadenopathy cases.     

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 accuracy of apparent diffusion coefficient value in differentiating metastatic form benign axillary lymph nodes in cancer breast

Purpose

To detect axillary lymph node metastasis based on diffusion Weighted MR and apparent diffusion coefficient (ADC) in the known breast cancer cases.

Patient and methods

Forty-four patients were included in this study for preoperative MRI staging of the breast cancer and axillary lymph node assessment. The lymph node criteria (long/short-axis ratio, T2WI, DWI and ADC value) were included in the analysis. Images were obtained with diffusion sensitizing gradients of 0 and 750 mm²/s. The ADC was calculated.

Results

Thirty-two patients had metastatic axillary lymph nodes and 12 cases had no malignant LN involvement. There was no significant difference between both in S/L ratio, T2WISI (p < 0.140 & p = 0.079, respectively), while statistically significant difference between benign and malignant lymph nodes in both DWI and ADC mean values (p < 0.0001 & p < 0.007, respectively). The optimal ADC cut off value was ?.8 × 10⁻³ mm²/s for differentiation between benign and malignant lymph nodes with accuracy 96.7%, sensitivity 100%, specificity 87%, PPV 95.4% and NPV 100%.

Conclusion

Compared with lymph node size or routine magnetic resonance sequences, DWI and ADC are promising techniques for differentiating metastatic and non metastatic axillary lymph nodes in known breast cancer patients.     

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.     

The significance of added ADC value to conventional MR imaging in differentiation between benign and malignant ovarian neoplasms

Purpose

To highlight the role of ADC value measurement in differentiating benign from malignant ovarian tumors.

Materials and methods

Twenty patients with ovarian neoplasms underwent conventional MRI including ADC value calculation before surgery. Retrospective analysis of the pathological specimen with lesion morphology, signal characteristics, enhancement criteria and correlation with the appearance at DWI followed by ADC value measurement were obtained.

Results

Twenty patients with ovarian mass lesions were included. They were divided into purely solid, purely cystic and complex solid/cystic lesions. All solid malignant lesions showed diffusion restriction as well as the wall and septations of most malignant cystic lesion however, except one case. All benign lesions did not display diffusion restriction in DWI. The best cut off value of ADC to discriminate between benign and malignant lesions was 0.9 with specificity of 100%, sensitivity of 88.9%, NPV of 75%, PPV of 100% and accuracy of 91.7%.

Conclusion

Addition of ADC value measurement to conventional MRI increases its specificity from 78.6% to 85.7% which could be useful in differentiating benign from malignant lesions.     

Imaging of Ovarian Teratomas in Children: A 9-Year Review

Objective

Germ cell tumours are the most common ovarian neoplasms in childhood and, of these, teratomas, whether mature or immature, are the most frequently found. Mature teratoma is a benign tumour, whereas the immature type, although also benign, has a more aggressive course, with a propensity to recurrence. A review of the literature revealed that there are some imaging features that may help to differentiate between these 2 types of teratoma, although no systematic comparison has been made. The objective of this study was to review imaging features of ovarian teratomas in children and to assess differentiating imaging features between the mature and immature types of ovarian teratoma.

Methods

Retrospective analysis of all patients who presented to our institution during a 9-year period (September 1999 to August 2008) with ovarian teratoma as confirmed on histology.

Results

Forty-one patients with pathologically proven ovarian teratoma were found. The patient ages ranged from 4–18 years at presentation (mean [standard deviation] age, 12.4 ± 3.4 years; median age, 13 years). Thirty patients (73.2%) were found to have mature ovarian teratoma, and 11 (26.8%) had immature teratoma. A component of endodermal sinus tumour was found in one of the immature teratomas. On ultrasonography, the appearance of the immature teratomas was purely solid in 3 (27.3%), mixed solid and cystic in 6 (54.5%), and predominantly cystic in 2 (18%). The mature ovarian teratomas demonstrated a predominantly cystic appearance in 22 (73.3%) and a mixed solid and cystic appearance in 8 (26.6%); there were no cases with a pure solid appearance. The prevalence of the more cystic appearance of the mature type showed significant statistical difference when compared with its prevalence in the immature type (P = .0008, χ² test). Other imaging features, such as size, presence of fat, or calcifications, did not show a significant difference between the 2 types of teratoma.

Conclusions

The predominance of a cystic component and a pure solid component in ovarian teratoma are significant differentiating factors between the mature type and the more aggressive immature type of teratoma.     

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.     

Role of diffusion-weighted MR imaging in discrimination between the intracranial cystic masses

Objective

Discriminating pyogenic brain abscesses from cystic or necrotic tumors is sometimes difficult with CT or conventional MR imaging. Diffusion MR imaging is a valuable diagnostic test in cases of intracranial cystic masses.

Methods

This work was conducted from July 2008 to June 2013 on 90 patients; 43 males and 47 females. Their ages range from 5 to 70 years. All patients were subjected to routine MRI examination and diffusion weighted imaging using 1.5 T MRI scanner. Gadolinium was given to some cases on routine MRI. Diffusion weighted imaging was performed with a single-shot spin-echo echo-planar pulse sequence (b = 0–1000 s/mm²). The apparent diffusion coefficient values and ratio were measured.

Results and conclusions

Patients in this study were categorized into three main groups; first group is brain abscesses (36 cases), 91.6% of them showed restricted diffusion, second group is malignant cystic or necrotic brain tumors, 28 cases of high grade necrotic glioma, 60.7% of them are free diffusion, and third group is benign cystic masses, arachnoid and epidermiod cysts (11 cases); all arachnoid cysts are free diffusion. From these results diffusion-weighted imaging is playing an important role in discrimination of cystic intracranial masses.     

Renal masses measuring under 2 cm: Pathologic outcomes and associations with MRI features

Purpose

To evaluate pathologic outcomes and associations with MRI features in small renal masses measuring up to 20 mm

Methods

86 patients (61 ± 13 years; 45 M/41F) with 92 renal masses measuring up to 20 mm that underwent MRI prior to tissue diagnosis were included. Two radiologists independently evaluated all masses for microscopic lipid, hemorrhage, T2-hyperintensity, T2-homogeneity, cystic/necrotic areas, hypervascularity, enhancement homogeneity, circumscribed margins, and predominantly exophytic location. These MRI features, as well as patient age, gender, and history of RCC, were compared with pathologic findings using Fisher's exact test, unpaired t-test, and multivariate logistic regression.

Results

26.1% (24/92) of masses under 2 cm were benign, only 32.6% (30/92) were clear-cell RCC, and only 7.6% (7/92) were high-grade. Among 16 masses measuring up to 1 cm, only 12.5% (2/16) were clear-cell RCC, and none was high-grade. Within the entire cohort, no MRI or clinical feature showed a significant difference between benign and malignant lesions (p ≥ 0.053). However, for both readers, clear-cell RCC exhibited a significantly higher frequency of T2-hyperintensity, cystic/necrotic areas, and hypervascularity, and a significantly lower frequency of hemorrhage, T2-homogeneity, and enhancement homogeneity (p < 0.001–0.036). Hypervascularity was a significant independent predictor of clear-cell RCC for both readers (p = 0.002–0.007), as was T2-hyperintensity for reader 2 (p = 0.007).

Conclusion

A substantial fraction of small renal masses were benign, and when malignant, largely exhibited indolent pathologic characteristics, particularly when measuring under 1 cm Although small benign and malignant masses could not be differentiated on MRI, hypervascularity showed a significant independent association with clear-cell RCC in comparison with other lesions.     

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.     

Lacrimal gland lesions: Can addition of diffusion-weighted MR imaging improve diagnostic accuracy in characterization?

The aim of the work

To evaluate the diagnostic value of apparent diffusion coefficient (ADC) maps in the characterization of lacrimal gland lesions.

Material and methods

A retrospective study was conducted on 40 patients (26 female and 14 male subjects aged 13–74 years) with lacrimal gland mass. They underwent echo-planar diffusion-weighted magnetic resonance imaging (MRI) of the orbit with a b-factor of 0500 and 1000 s/mm² at 3-Tesla magnetic resonance (MR) unit. ADC maps were reconstructed and the ADC of each mass lesion was calculated. Lesion diagnosis was confirmed by the clinical follow-up or the results of histopathology analysis depending on the specific disease to identify the specificity, sensitivity and accuracy of diffusion-weighted imaging (DWI) in the differentiation between benign and malignant lacrimal lesions.

Results

Forty-two lesions were detected in the examined 40 patients included in this study. Thirty-one were benign and 11 were malignant. The mean ADC value of the malignant lacrimal tumors (0.76 ± 0.14 × 10⁻³ mm²/s) was significantly (P = 0.001) lower than that of the benign lacrimal lesions (1.17 ± 0.22 × 10⁻³ mm²/s). A statistically significant (P = 0.001) difference is identified between the subjects with lacrimal adenitis and those with idiopathic orbital inflammatory syndrome (orbital pseudotumor). Lacrimal lymphoma has the lowest ADCs among a wide range of lacrimal masses. The selection of an ADC value of 0.90 × 10⁻³ mm²/s as a threshold value for differentiating malignant tumors from benign lacrimal lesions has an accuracy of 90%, a sensitivity of 90%, and specificity of 89%.

Conclusion

ADC offers a useful reliable safe non-invasive imaging parameter that can be used for the differentiation of malignant tumors from benign lacrimal lesions with high sensitivity and specificity. The absence of contrast media in DWI reduces the cost of the examination and leads to an increase in the overall accuracy of MRI, hence reducing the number of false positive results and consequently reducing the number of unnecessary biopsies.     

DWI in characterization of complex ovarian masses,would it help?

Objective

To define the role of diffusion-weighted imaging & apparent diffusion coefficient (ADC) in characterizing complex ovarian masses, with particular concern to differentiating benign versus malignant masses.

Diagnostic yield of combined magnetic resonance spectroscopy and diffusion weighted imaging in intracranial neoplasms

Purpose

Our intention was to evaluate the role of combined diffusion magnetic resonance imaging and spectroscopy in diagnosis and grading of brain tumors.

Materials and methods

Ninety-three included cases underwent magnetic resonance imaging (MRI) and magnetic resonance spectroscopy (MRS) of the brain lesion, stereotactic or open biopsies and histopathological examination. MRI protocol included DWI and calculated ADC values. Multivoxel MRS spectroscopic technique (MVS) was used and all MRS metabolic parameters were obtained.

Results

High grade tumors had significantly lower ADC values than low grade tumors (P < 0.001). ADC values were the lowest in lymphoma (0.54 × 10⁻³ mm²/s) and the highest in craniopharyngioma (1.9 × 10⁻³ mm²/s). MRS revealed a statistically significant difference in CHO/NAA and CHO/Cr ratios between low and high grade tumors with P < 0.01 and P < 0.001, respectively. The mI/Cr ratio and presence of lactate, lipid and taurine also aided in differentiation and grading of brain tumors. The overall MRI/MRS sensitivity and specificity were 91%, 90.5%, respectively.

Conclusion

MRS has a robust diagnostic accuracy in cases of well defined high or low grade brain neoplasms. ADC value had the ability to confirm and differentiate low from high grade tumors in many situations where there were diagnostic confusions with MRS due to borderline values.     

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.     

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.