Diffusion-weighted magnetic resonance imaging in evaluation of primary solid and cystic renal masses using the Bosniak classification

Purpose

Our purpose was to determine whether quantitative diffusion-weighted MR imaging (DWI) could be used in discrimination of benign and malignant primary solid and cystic renal tumors.

Materials and methods

A total of 105 consecutive patients with renal masses and 30 healthy controls were enrolled in this prospective study. Dynamic contrast enhanced routin renal images and DWI (with b factors of 0, 500 and 1000 s/mm²) was performed at 1.5 T unit. Renal masses were divided into two groups as cystic or solid and all cystic lesions were prospectively assigned to a Bosniak classification number. The median apparent diffusion coefficient (ADC) values along with b 500 and 1000 signal intensities of normal kidneys, solid components of mixed renal masses and total of cystic lesions were calculated.

Results

The mean ADC value of normal renal parenchyma in control group was 2.18 ± 0.13 × 10⁻³ mm²/s. Solid renal tumors had significant lower ADC values (median: 1.16 ± 0.27 × 10⁻³ mm²/s), in contrast to cystic tumors (median: 2.73 ± 0.44 × 10⁻³ mm²/s). The mean ADC value of the Bosniak Category I cysts was significantly higher (3.09 ± 0.14 × 10⁻³ mm²/s) than normal renal parenchyma (p < 0.01). A statistical significance was achieved between the signal intensity of Bosniak Category I and Category II–III cysts with b 1000 (p < 0.05). Among the different histologic subtypes of renal cell carcinoma, the mean ADC value of chromophobe cell carcinoma (1.41 ± 0.09 × 10⁻³ mm²/s) was significantly higher than that of papillary cell carcinoma (0.90 ± 0.16 × 10⁻³ mm²/s) and clear cell carcinoma (1.23 ± 0.13 × 10⁻³ mm²/s).

Conclusion

Accurate assessment of renal masses is important for establishing whether tumors require surgical intervention or not. While MRI is a useful modality as an investigative tool for diagnosing, characterizing and staging renal masses, DWI contributes additional value by promising differentiation benign from malignant renal tumors, even histologically subtyping of renal cell cancer.     

Tissue characterization of head and neck lesions using diffusion-weighted MR imaging with SPLICE

Purpose

The purpose of this study was to evaluate the usefulness of diffusion-weighted (DW) MR imaging with split acquisition of fast spin-echo signals (SPLICE) in the tissue characterization of head and neck mass lesions.

Patients and methods

DW MR images of 67 head and neck mass lesions were obtained using SPLICE with b-factors of 0 and 771 s/mm². The lesions were classified into three categories: 16 cysts, 32 benign tumors, and 19 malignant tumors. After ADC maps were constructed for all lesions, ADC values were calculated and compared among the three categories.

Results

No case showed severe image distortion on DW MR imaging with SPLICE, and reliable ADC maps and ADC values were obtained in all cases. The mean ADC value of cysts was 2.41 ± 0.48 × 10⁻³ mm²/s, which was significantly higher than that of benign (1.48 ± 0.62 × 10⁻³ mm²/s) and malignant (1.23 ± 0.45 × 10⁻³ mm²/s) tumors (P < 0.001). However, there was no significant difference between the ADC values of benign and malignant tumors (P = 0.246). When an ADC value of 2.10 × 10⁻³ mm²/s or higher was used as the diagnostic criterion for cysts, the sensitivity, specificity, and accuracy were 94%, 88%, and 90%, respectively.

Conclusion

SPLICE was considered a recommended DW MR imaging technique for the head and neck. Although ADC values were useful in differentiating cysts from tumors, they contributed little in predicting malignancy.     

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

Aim

The aim of this study is to evaluate the value of the apparent diffusion coefficient (ADC) obtained in diffusion-weighted (DW) MR sequences for the differentiation between malignant and benign bone marrow lesions.

Method

Forty-five patients with altered signal intensity vertebral bodies on conventional MR sequences were included. The cause of altered signal intensity was benign osteoporotic collapse in 16, acute neoplastic infiltration in 15, and infectious processes in 14; based on plain-film, CT, bone scintigraphy, conventional MR studies, biopsy or follow-up. All patients underwent isotropic DW MR images (multi-shot EPI, b values of 0 and 500 s/mm²). Signal intensity at DW MR images was evaluated and ADC values were calculated and compared between malignancy, benign edema and infectious spondylitis.

Results

Acute malignant fractures were hyperintense compared to normal vertebral bodies on the diffusion-weighted sequence, except in one patient with sclerotic metastases. Mean ADC value from benign edema (1.9 ± 0.39 × 10⁻³ mm²/s) was significantly (p < 0.0001) higher than untreated metastasic lesions (0.9 ± 1.3 × 10⁻³ mm²/s). Mean ADC value of infectious spondilytis (0.96 ± 0.49 × 10⁻³ mm²/s) was not statistically (p > 0.05) different from untreated metastasic lesions. ADC value was low (0.75 × 10⁻³ mm²/s) in one case of subacute benign fracture.

Conclusions

ADC values are a useful complementary tool to characterize bone marrow lesions, in order to distinguish acute benign fractures from malignant or infectious bone lesions. However, ADC values are not valuable in order to differentiate malignancy from infection.     

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.     

Apparent diffusion coefficient values of mediastinal masses in children

Objective

Compare apparent diffusion coefficient (ADC) values between benign and malignant mass lesions in a cohort of children referred for imaging of a mediastinal mass.

Material and methods

Prospective study including 24 consecutive children (11 boys, 13 girls aged 5 months to 16 years). All underwent echo planar diffusion weighted MR imaging of the mediastinum with b-factors of 0 and 600 s/mm². Apparent diffusion coefficient (ADC) values were calculated and correlated with the surgical finding or biopsy.

Results

The mean ADC value of malignant mediastinal tumors was 0.91 (S.D., 0.17) ×10⁻³ mm²/s and of benign lesions 1.8 (S.D., 0.33) ×10⁻³ mm²/s. There was significant different in the ADC value between malignant tumors and benign mediastinal tumors (P < 0.001). Selection of 1.2 × 10⁻³ mm²/s as a threshold value for differentiating malignant from benign mediastinal masses has an accuracy of 93%, sensitivity of 92%, specificity of 94%, positive predictive value of 94%, negative predictive value of 92% and area under the curve of 0.962.

Conclusion

Apparent diffusion coefficient value is a promising non-invasive parameter for assessment of mediastinal mass in children.     

Utility of chemical shift and diffusion-weighted imaging in characterization of hyperattenuating adrenal lesions at 3.0T

Objective

The purpose of our study was to evaluate the value of chemical shift imaging (CSI) and diffusion weighted imaging (DWI) at 3.0 T MRI in adrenal hyperattenuating lesions.

Methods

Fifty-one hyperattenuating adrenal lesions in 40 patients were evaluated. Signal intensity index (SII), adrenal to spleen ratio (ASR) and apparent diffusion coefficient (ADC) were used as quantitative analysis parameters.

Results

The mean SII, ASR and ADC values were: benign pheochromocytomas (n = 22), 7.04%; 0.96, 1.15 × 10⁻³ mm²/s; lipid-poor adenomas (n = 18), 33.77%, 0.71, 1.07 × 10⁻³ mm²/s; malignant tumors (n = 7), 11.24%; 1.00; 0.92 × 10⁻³mm²/s. There were significant differences between the lipid-poor adenomas and nonadenomas for SII and ASR, and there were significant differences between the benign and the malignant tumor ADC values. The optimal diagnostic threshold point of SII and ASR for lipid-poor adenomas was 11.96%, 0.83, the sensitivity and specificity were 88.9%, 97.5% and 97%, 83.3%. The optimal diagnostic threshold point of ADC value for benign lesions and malignant tumors was 1.04 × 10⁻³ mm²/s, the sensitivity and specificity were 61.4% and 85.7%.

Conclusion

Quantitative analysis of chemical shift MRI and DWI can help to characterize the hyperattenuating adrenal lesions, especially in differentiatiation between the lipid-poor adenomas, the benign pheochromocytomas, and the malignant tumors.     

Apparent diffusion coefficient of diffusion weighted MRI in endometrial carcinoma-Relationship with local invasiveness

Objective

To evaluate the relationship between apparent diffusion coefficient (ADC) value and the local invasiveness of endometrial carcinoma.

Methods and materials

The MR imaging of seventy-three patients with endometrial carcinoma proved by post-operative pathology and sixty-four patients with healthy uteri were retrospectively reviewed. All MR examinations included axial T2WI and T1WI, sagittal T2WI and diffusion-weighted sequences (b = 0 and b = 1000 s/mm²). Tumor size, mean ADC value (ADCm) and quartile ADC (ADCq) were acquired on post-processing workstation using voxel-analysis software. Differences between the ADC values among three layers of normal uterine body and endometrial carcinomas were compared by ANOVA test. Groups were divided according to pathologic type, histologic grade, depth of myometrial infiltration, presence of cervical invasion and lymphovascular space invasion, and lymph node metastasis. Tumor size and ADC values were compared and analyzed.

Results

ADC values were different in three zones of uterine body (P < 0.001), with the lowest in junctional zone [(1.126 ± 0.190) × 10⁻³ mm²/s] and highest in outer myometrium [(1.496 ± 0.196) × 10⁻³ mm²/s]. Mean ADC value of endometrial carcinomas [(1.011 ± 0.121) × 10⁻³ mm²/s] was lower than the normal uterine body. Quartile ADC and tumor size were greater in groups with more invasive pathologic factors (P < 0.05). Deep myometrial infiltration, cervical invasion, lymphovascular space invasion and lymph node metastasis were more common as quartile ADC values and tumor sizes increased.

Conclusion

Mean ADC value was lower in endometrial carcinoma was lower than the normal uterus. Quartile ADC, representing the intra-tumor heterogeneity of water movement, had a profound relationship with invasiveness of endometrial carcinomas, while mean ADC value did not. ADC values may serve as a quantitative indicator to complement routine sequences.     

Evaluation of MR diffusion-weighted imaging in differentiating endometriosis infiltrating the bowel from colorectal carcinoma

Objective

Endometriosis infiltrating the bowel may be difficult to differentiate from colorectal carcinoma in cases that present with non-specific clinical and imaging features. The aim of this study is to assess the value of MR diffusion-weighted imaging (DWI) in differentiating endometriosis infiltrating the bowel from colorectal carcinoma.

Methods

In 66 patients, MR DWI was added to the standard imaging protocol in patients visiting our outdoor MR clinic for the analysis of suspected or known deep infiltrating endometriosis (DIE). In patients diagnosed with DIE infiltrating the bowel on MR imaging, high b-value diffusion-weighted images were qualitatively assessed by two readers in consensus and compared to high b-value diffusion weighted images in 15 patients evaluated for colorectal carcinoma. In addition, ADC values of lesions were calculated, using b-values of 50, 400 and 800 s/mm².

Results

A total of 15 patients were diagnosed with DIE infiltrating the bowel on MR imaging. Endometriosis infiltrating the bowel showed low signal intensity on high b-value diffusion-weighted images in all patients, whereas colorectal carcinoma showed high signal intensity on high b-value diffusion-weighted images in all patients. Mean ADC value in endometriosis infiltrating the bowel (0.80 ± 0.06 × 10⁻³ mm²/s) was significantly lower compared to mean ADC value in colorectal carcinoma (0.86 ± 0.06 × 10⁻³ mm²/s), but with considerable overlap between ADC values.

Conclusion

Only qualitative assessment of MR DWI may be valuable to facilitate differentiation between endometriosis infiltrating the bowel and colorectal carcinoma.     

Application of ADC measurement in characterization of renal cell carcinomas with different pathological types and grades by 3.0T diffusion-weighted MRI

Purpose

To test the feasibility of apparent diffusion coefficient (ADC) value obtained with 3.0 T diffusion-weighted imaging (DWI) in the characterization of renal cell carcinomas (RCC) with different pathological subtypes and grades.

Materials and methods

A total of 137 patients who were diagnosed with RCC and underwent DWI were included in this study. The diagnosis was confirmed by pathological examination of surgical specimens. Images of DWI were obtained with b values of 0 and 800 s/mm². The ADC values in the solid area of tumors and in the corresponding regions of contralateral normal renal parenchyma were measured and analyzed statistically.

Results

The mean ADC value was significantly lower in RCC (1.381 ± 0.444 × 10⁻³ mm²/s) than in normal renal parenchyma (2.232 ± 0.221 × 10⁻³ mm²/s) (P < 0.001). The ADC value was also statistically different between clear cell RCC (CCRCC) and non-CCRCC, and between different grades of CCRCC except grade I vs II and grade III vs IV.

Conclusion

ADC measurement on 3.0 T DWI provides useful information in diagnostic work-up of RCC in terms of differentiation of RCC and normal renal parenchyma, and characterization of RCC with different pathological subtypes and grades.     

Relationship of apparent diffusion coefficient to survival for patients with unresectable primary hepatocellular carcinoma after chemoembolization

Objectives

to evaluate the prognostic value of apparent diffusion coefficient (ADC) values from MR diffusion-weighted imaging of unresectable hepatocellular carcinoma after chemoembolization.

Methods

our study was proved by our institute and informed consent was obtained from all patients before commencement of the study. Twenty-three patients with unresectable hepatocellular carcinoma were scanned immediately before and after chemoembolization within 24 h using conventional anatomical MR imaging and diffusion-weighted imaging, from which ADC values in the lesions were measured. The changes in ADC values after chemoembolization were calculated. The relationship between the lesion ADC and the survival time was analyzed by correlation analysis. The overall cumulative survival was analyzed by the Kaplan–Meier method, and survival curves were compared by the log-rank test.

Results

the mean overall survival period was (25.0 ± 8.7) months. The pre-chemoembolization lesion ADC value was (1.36 ± 0.249) ×10⁻³ mm²/s; the change in ADC values post-chemoembolization was (0.377 ± 0.332) ×10⁻³ mm²/s. There were significant linear regression relation between the survival time and pre-chemoembolization lesion ADC values (r = −0.698, P < 0.001) or the changes in ADC value post-chemoembolization (r = 0.702, P < 0.001). And Log-rank test showed that pre-chemoembolization ADC values (χ² = 7.339, P = 0.007) or the changes in ADC value post-chemoembolization (χ² = 9.820, P = 0.002) significantly influenced the overall cumulative survival.

Conclusion

Pre-treatment ADC values as well as changes in ADC values after treatment may provide useful information for predicting survival for patients with unresectable hepatocellular carcinoma.     

A preliminary study of apparent diffusion coefficient in chemotherapy-induced liver damage

Objectives

To investigate changes in the hepatic apparent diffusion coefficient (ADC) in patients undergoing chemotherapy.

Methods

We enrolled 54 patients (25 women; mean age 57.0 ± 13.1 years, range 29–89 years) undergoing chemotherapy for tumor and 10 controls (7 women; mean age 55.1 ± 17.5 years, range 23–81 years). The patients were tested for serum alanine aminotransferase (ALT) activity (abnormal, normal) and fatty liver. Hepatic ADC values were compared among controls, patients and subgroups. Pearson correlation coefficient was used to assess the correlation between ADC and ALT activity.

Results

Hepatic ADC0,850 (×10⁻³ mm²/s) was lower for patients than controls (1.14 ± 0.18 vs. 1.28 ± 0.12, P = 0.02) and was lower for patients with than without fatty liver and controls (1.01 ± 0.06 vs. 1.18 ± 0.18 and 1.28 ± 0.12, respectively, all P < 0.01), with no significant difference between patients without fatty liver and controls (P = 0.07). ADC0,850 was lower for patients with abnormal ALT than normal ALT activity and controls (0.99 ± 0.06 vs. 1.17 ± 0.18 and 1.28 ± 0.12, respectively, all P < 0.05), with a significant difference also being seen between patients with normal ALT activity and controls (P = 0.04). Hepatic ADC0,850 was not correlated with ALT activity in patients (r = -0.24, P = 0.08).

Conclusions

Although ADC did not correlate with ALT values, it did distinguish patient likely to have chemotherapy-induced liver damage as indicated by abnormal ALT values or fatty liver. These mechanisms need to be disentangled.     

Sandwich sign of Borrmann type 4 gastric cancer on diffusion-weighted magnetic resonance imaging

Objective

To assess the appearance of Borrmann type 4 (BT-4) gastric cancer on diffusion-weighted magnetic resonance imaging (DWI) and to investigate the potential of qualitative and quantitative DW images analysis to differentiate BT-4 gastric cancer from poorly distended normal stomach wall.

Materials and methods

DWI was performed on 23 patients with BT-4 gastric cancer and 23 healthy volunteers. The signal characteristics and correlated histopathological basis of the cancers on DWI were investigated. The contrast-to-noise ratios (CNR) of cancer were compared between DWI and T1WI/T2WI_. The thickness and apparent diffusion coefficient (ADC) of cancer and normal stomach wall were compared.

Results

All of the gastric cancers displayed hyperintensity compared to the nearby normal gastric wall on DWI. A three-layer sandwich sign that demonstrated high signal intensity in the inner and outer layer, and low signal intensity in the intermediate layer was observed in 69.6% of cancers on DWI. The low signal intensity represents the muscularis propria through the comparison with pathology, and it is postulated that scattering distribution of the cancer cells in this layer causes less damage and subsequently less restriction of water movement, which causes the low signal intensity on DWI. The CNR obtained with DWI was higher than that with T1WI and T2WI (P < 0.001). The mean ADC value of BT-4 gastric cancer was significantly lower than the poorly distended normal stomach wall (1.12 ± 0.23 × 10⁻³ mm²/s vs. 1.93 ± 0.22 × 10⁻³ mm²/s, P < 0.01).

Conclusion

DWI can highlight the signals of BT-4 gastric cancer which may present a characteristic three-layer sandwich sign, and ADC values are helpful in the discrimination of gastric cancer from poorly distended stomach wall.     

Diffusion-weighted MRI versus transient elastography in quantification of liver fibrosis in patients with chronic cholestatic liver diseases

Purpose

To evaluate the diagnostic value of diffusion-weighted magnetic resonance imaging (DWMRI) and transient elastography (TE) in quantification of liver fibrosis in patients with chronic cholestatic liver diseases.

Materials and methods

Forty-five patients underwent DWMRI, TE, and liver biopsy for staging of liver fibrosis. Apparent diffusion coefficient (ADC) was calculated for six locations in the liver for combination of five diffusion sensitivity values b = 0, 50, 200, 400 and 800 s/mm². A receiver operating characteristic (ROC) analysis was performed to determine the diagnostic performance of DWMRI and TE. Segmental ADC variations were evaluated by means of coefficient of variation.

Results

The mean ADCs (×10⁻³ mm²/s; b = 0–800 s/mm²) were significantly different at stage F1 versus F ≥ 2 (p < 0.05) and F2 versus F4. However, no significant difference was found between F2 and F3. For prediction of F ≥ 2 and F ≥ 3 areas under the ROC curves were 0.868 and 0.906 for DWMRI, and 0.966 and 0.960 for TE, respectively. The sensitivity and specificity were 90.9% and 89.3% for F ≥ 2 (ADC ≤ 1.65), and 92.3% and 92.1% for F ≥ 3 (ADC ≤ 1.63). Segmental ADC variation was lowest for F4 (CV = 9.54 ± 6.3%).

Conclusion

DWMRI and TE could be used for assessment of liver fibrosis with TE having higher diagnostic accuracy and DWMRI providing insight into liver fibrosis distribution.     

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.     

Diffusion weighted imaging of liver lesions suspect for metastases: Apparent diffusion coefficient (ADC) values and lesion contrast are independent from Gd-EOB-DTPA administration

Purpose

Gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA) enhanced liver MRI is widely used for detection and differentiation of focal liver lesions. Diffusion weighted imaging (DWI) including apparent diffusion coefficient (ADC) measurements is increasingly utilised as a fast and, with limitations, quantitative method for liver lesion detection and characterisation. Herein we investigate whether the administration of Gd-EOB-DTPA affects DWI.

Materials and methods

31 consecutive patients referred to standardised liver MRI (1.5 T, Gd-EOB-DTPA, 0.025 mmol/kg) were retrospectively reviewed. All underwent a breathhold DWI sequence before and after contrast agent administration (EPI-DWI, TR/TE (effective): 2100/62 ms, b-values: 0 and 800 s/mm²). Patients with previously treated liver lesions were excluded. Signal intensity of lesion, parenchyma and noise on DWI images as well as the ADC value were measured after identification by two observers in consensus using manually placed regions of interest. The reference standard was imaging follow-up determined separately by two radiologists. Data analysis included signal-to-noise (SNR) ratio and contrast-to-noise ratio (CNR) calculations, comparisons were drawn by employing multiple Bonferroni corrected Wilcoxon signed-rank tests.

Results

50 malignant and 39 benign lesions were identified. Neither SNR, CNR nor ADC values showed significant differences between pre- and postcontrast DWI. Both pre- and postcontrast ADC values differed significantly between benign and malignant lesions (P < 0.001).

Conclusion

We did not identify a significant influence of Gd-EOB-DTPA on DWI of liver lesions. This allows for individual tailoring of imaging protocols according to clinical needs.     

Lymphomas and glioblastomas: differences in the apparent diffusion coefficient evaluated with high b-value diffusion-weighted magnetic resonance imaging at 3T

Background and purpose

As the usefulness of the apparent diffusion coefficient (ADC) obtained from diffusion-weighted images (DWI) for the differential diagnosis between glioblastoma and primary central nervous system lymphoma is controversial, we assessed whether high b-value DWI at b 4000 s/mm² could discriminate between glioblastoma and lymphoma. We also compared the power of high- and standard b-value (b-4000, b-1000) imaging on a 3-Tesla (3 T) magnetic resonance (MR) instrument.

Materials and methods

This study was approved by our Institutional Review Board. We acquired DWI at 3 T with b = 1000 and b = 4000 s/mm² in 10 patients with lymphoma and 14 patients with glioblastoma. The ADC was measured by placing multiple regions of interest (ROI) on ADC maps of the site of enhanced lesions on contrast-enhanced T1-weighted MR images. We avoided hemorrhagic and cystic lesions by using T1-, T2-, FLAIR-, and T2* MR images. The ADC values of each tumor were determined preoperatively from several ROI and expressed as the minimum-, mean-, and maximum ADC value (ADC_MIN, ADC_MEAN, ADC_MAX). We evaluated the relationship between ADCs and histological information including tumor cellularity.

Results

All ADC values were statistically associated with tumor cellularity. ADC_MIN at b-4000 was associated with tumor cellularity more significantly than ADC_MIN at b-1000. All ADC values were lower for lymphoma than glioblastoma and the statistical difference was larger at b = 4000- than b = 1000 s/mm². According to the results of discriminant analysis, the log likelihood was greatest for ADC_MIN at b = 4000. At a cut-off value of ADC_MIN = 0.500 × 10⁻³ mm²/s at b-4000 it was possible to differentiate between lymphoma and glioblastoma (sensitivity 90.9%, specificity 91.7%).

Conclusions

Calculating the ADC value is useful for distinguishing lymphoma from glioblastoma. The lowest degree of overlapping and a better inverse correspondence with tumor cellularity were obtained with ADC_MIN at b-4000 s/mm² at 3 T MRI.     

Apparent diffusion coefficient values of the normal uterus: Interindividual variations during menstrual cycle

Objectives

To assess the apparent diffusion coefficient (ADC) changes of the normal uterine zones among reproductive women during the menstrual cycle.

Methods

The study included 101 women of reproductive age, each with regular cycle and normal endometrium/myometrium, as proved on histopathology or MR imaging examination. Diffusion-weighted (DW) imaging was performed along the axial plane, using a single shot, multi-slice spin-echo planar diffusion pulse sequence and b-values of 0 and 800 s/mm². The mean and standard deviation of the ADC values of normal endometrium/myometrium were calculated for menstrual, proliferative and secretory phase. Analysis of variance followed by the least significant difference test was used for statistical analysis.

Results

The ADC values of the endometrium were different in the three phases of the menstrual cycle (menstrual phase: 1.25 ± 0.27; proliferative phase: 1.39 ± 0.20; secretory phase: 1.50 ± 0.18) (F: 9.64, p: 0.00). Statistical significant difference was observed among all groups (p < 0.05). The ADC values of the normal myometrium were different in the three phases of the menstrual cycle (menstrual phase: 1.91 ± 0.35; proliferative phase: 1.72 ± 0.27; secretory phase: 1.87 ± 0.28) (F: 3.60, p: 0.03). Statistical significant difference was observed between menstrual and proliferative phase and between proliferative and secretory phase (p < 0.05). No significant difference was noted between menstrual and secretory phase (p > 0.05).

Conclusions

A wide variation of ADC values of normal endometrium and myometrium is observed during different phases of the menstrual cycle.     

Validity of apparent diffusion coefficient hyperpolarized 3He-MRI using MSCT and pulmonary function tests as references

Purpose

To compare apparent diffusion coefficient (ADC) measurements from hyperpolarized (HP) helium (³He)-magnetic resonance imaging (MRI) with quantitative data from multislice Computed Tomography (CT) (MSCT) of the whole lungs and pulmonary function tests (PFT).

Materials and methods

Twenty-seven subjects, 22 with established emphysema and 5 with preclinical emphysema defined by PFT criteria, were examined with HP ³He-MRI and MSCT. Mean age was 55 (±12) years, 18 female and 9 male. Mean ADC from ³He-MRI was compared with emphysema index (EI), 15th percentile and mean lung density (MLD) values from MSCT. Both mean ADC and MSCT data were compared to PFT, especially percent of predicted diffusing capacity of carbon monoxide (%predicted DLCO), using Pearson's correlation test.

Results

Mean ADC and standard deviation values were 0.392 ± 0.119 cm²/s for the established emphysema group and 0.216 ± 0.046 for the pre-clinical emphysema group. MSCT values for the established emphysema group and pre-clinical emphysema group were: EI (%) 11 ± 12 and 0.4 ± 0.6, respectively; 15th percentile (Hounsfield Units (HU)), −956 ± 25 and −933 ± 13, respectively and MLD (HU) −877 ± 20 and −863 ± 15, respectively. Correlations between mean ADC and EI and 15th percentile were both r = 0.90 and for MLD r = 0.59. There was higher correlation between mean ADC and %predicted DLCO (r = 0.90) than between EI and %predicted DLCO (r = 0.76).

Conclusion

HP ³He-MRI correlates well with density measurements from MSCT and agrees better than MSCT with %predicted DLCO which is the PFT most related to emphysema.     

Diffusion weighted MR imaging in patients with HCC and liver cirrhosis after administration of different gadolinium contrast agents: Is it still reliable?

Purpose

Diffusion weighted imaging (DWI) is an emerging technique for abdominal MR and usually performed before intravenous contrast injection. Recent studies performed in patients with normal liver function have shown that DWI can be performed after gadolinium administration. Aim of this study was to compare DWI before and after administration of different gadolinium compounds in patients with HCC and liver cirrhosis.

Materials and methods

15 patients with known HCC and liver cirrhosis underwent liver MRI at 1.5 T (Magnetom Avanto, Siemens) including DWI on day 1 before and after administration of gadobutrol (Gadovist^®) and on day 2 after administration of EOB-Gadolinium-DTPA (Primovist^®). Signal to noise ratios (SNR) and contrast to noise ratios (CNR) of HCC lesions were determined for all DWI data sets. Furthermore, ADC values were compared using a Wilcoxon test. A p-value <0.05 indicated statistically significant differences.

Results

There were no statistically significant differences regarding SNR pre-contrast (mean: 48.1), after gadobutrol (mean: 47.7) or after EOB-Gadolinium-DTPA (mean: 50.0; values for b = 50 s/mm²). Similarly, no significant differences were found for CNR (average values:34.4 vs. 32.3 vs. 30.7; b = 50 s/mm²) nor for ADC-values (mean: 1.5 vs. 1.4 vs. 1.5 × 10⁻³ mm²/s) of HCC.

Conclusion

There is no significant difference regarding DWI in patients with cirrhosis before and after contrast injection. Hence, it is reliable to run DWI after gadolinium either as an alternative for unsuccessful pre-contrast DWI or as a gap filler to spare time in EOB-Gadolinium-DTPA imaging.     

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.