Comparison of acquired diffusion weighted imaging and computed diffusion weighted imaging for detection of hepatic metastases

Objective

To compare the accuracy of acquired diffusion weighted imaging (DWI) (b = 1000 s/mm²) with that of computed DWI (b = 1000 s/mm²) for the detection of hepatic metastases.

Methods

Two hundred and sixty patients underwent abdominal magnetic resonance imaging (MRI) at 3.0 T for the evaluation of hepatic metastasis, including T1-weighted imaging (T1WI), T2-weighted imaging (T2WI), heavily T2WI, DWI with b-values of 0, 500, 1000 s/mm², and three-dimensional dynamic contrast-enhanced MRI with gadolinium-ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA), and 190 patients were included in the final study. Computed DWI (=1000 s/mm²) was synthesized from lower b-values (b = 0 and 500 s/mm²). Two groups were assigned and compared: group A (acquired DWI) and group B (computed DWI). Diagnostic performance using each imaging set was evaluated by receiver operating characteristic (ROC) curve analysis.

Results

A total of 76 hepatic metastases were confirmed. The area under the ROC curve (Az) of group A was larger than that of group B (Observer 1; 0.919–0.915, Observer 2; 0.926–0.901), but there were no significant differences (observer 1, P = 0.500; observer 2, P = 0.190). There were 5 metastases visualized in group A, but these were difficult to detect in group B. However, there were 2 metastases that were better visualized in group B than in group A.

Conclusion

There were no significant differences between acquired DWI and computed DWI in the detection of hepatic metastasis.     

Role of diffusion-weighted imaging as an adjunct to contrast-enhanced breast MRI in evaluating residual breast cancer following neoadjuvant chemotherapy

Objective

To investigate whether the addition of diffusion-weighted imaging (DWI) to dynamic contrast-enhanced MRI (DCE-MRI) improves diagnostic performance in predicting pathologic response and residual breast cancer size following neoadjuvant chemotherapy.

Materials and methods

A total of 78 consecutive patients who underwent preoperative breast MRI with DWI following neoadjuvant chemotherapy were enrolled. DWI was performed on a 1.5 T system with b values of 0 and 750 s/mm. or on a 3 T system with b values of 0 and 800 or 0 and 1000 s/mm. The images on DCE-MRI alone, DWI alone, and DCE-MRI plus DWI were retrospectively reviewed. We evaluated the diagnostic performances of the three MRI protocols for the detection of residual cancer. The tumor size as predicted by MRI was compared with histopathologic findings. Apparent diffusion coefficient (ADC) values were also compared between the groups with and without residual cancer.

Results

Of the 78 patients, 59 (75.6%) had residual cancer. For detection of residual cancer, DCE-MRI plus DWI had higher specificity (80.0%), accuracy (91.0%), and PPV (93.2%) than DCE-MRI or DWI alone (P = 0.004, P = 0.007, and P = 0.034, respectively). The ICC values for residual cancer size between MRI and histopathology were 0.891 for DCE-MRI plus DWI, 0.792 for DCE-MRI, and 0.773 for DWI. ADC values showed no significant differences between residual cancer and chemotherapeutic changes (P = 0.130).

Conclusions

The addition of DWI to DCE-MRI significantly improved diagnostic performance in predicting pathologic response and residual breast cancer size after neoadjuvant chemotherapy.     

The added value of diffusion-weighted MR imaging to MR cholangiopancreatography in differentiating malignant from benign extrahepatic biliary strictures

Purpose

To investigate the added value of diffusion-weighted imaging (DWI) to magnetic resonance cholangiopancreatography (MRCP) in differentiating benign from malignant extrahepatic biliary strictures.

Methods

Magnetic resonance examination including, T2-weighted imaging, MRCP and DWI using different b-values (0,500,800 s/mm²) were performed in 38 patients with suspicious extrahepatic biliary strictures. Apparent diffusion coefficient (ADC) value was calculated. The signal intensity of the lesions on DWI using b = 500 and 800 s/mm² was examined. Analysis of the DWI and MRCP images for the cause of the extrahepatic biliary stricutre was performed. Patients were further confirmed by histopathological diagnosis and follow up. Sensitivity, specificity, accuracy, positive predictive and negative predictive values were calculated for both the MRCP images and DWI.

Results

Of the 38 cases, 23 cases had malignant extrahepatic biliary strictures and 15 had benign strictures. DWI detected 21 out of the 23 malignant biliary strictures and 14 out of 15 benign biliary strictures. Malignant strictures more frequently appeared hyperintense than benign strictures on DWI using b-values of 500 and 800 s/mm². There was a significant difference in sensitivity (91.3% vs. 73%), specificity (93.3% vs. 64.7%), accuracy (92.1% vs. 73.6%), positive predictive value (95.4% vs. 81%), and negative predictive value (87.5% vs. 64.7%) between DWI and MRCP in differentiating biliary strictures.

Conclusion

Combined evaluation using DWI added to MRCP improves the differentiation of malignant from benign extrahepatic biliary strictures.     

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.     

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.     

Correlation study of 3T-MR-DTI measurements and clinical symptoms of cervical spondylotic myelopathy

Objective

To discuss the correlation between diffusion tensor imaging (DTI) measurements, diffusion tensor tractography and the clinical symptoms of cervical spondylotic myelopathy.

Methods

Based on the Japanese Orthopedics Association (JOA) score, 104 cervical spondylotic myelopathy cases were first divided into four groups: mild, moderate, severe and serious groups. According to lesion signal characteristics, all cases were again divided into three groups: A(N/N): normal signal in both T1WI and T2WI; B (N/H): normal signal in T1WI but high signal in T2WI; and C (L/H): low signal in T1WI and high signal in T2WI. The apparent diffusion coefficient (ADC), fractional anisotropy (FA), λ1, λ2, and λ3 were measured and diffusion tensor tractography was performed in the seriously compressed section of the spinal cord.

Results

The FA values were positively correlated with JOA scores (r = 0.883, P < 0.05), and significantly different among four JOA groups (P < 0.05). The ADC, λ2, and λ3 were significantly different among the moderate, severe and serious groups as well as among the A, B, and C groups (P < 0.05). Declining FA values were found associated with increasing fiber bundle damage.

Conclusions

The FA values and the change patterns of fiber bundle were more sensitive than T2WI for spinal cord lesion, and were positively correlated with clinical symptoms.     

Effect of breast cancer phenotype on diagnostic performance of MRI in the prediction to response to neoadjuvant treatment

Aim

The estimation of response to neoadjuvant chemotherapy (NAC) is useful in the surgical decision in breast cancer. We addressed the diagnostic reliability of conventional MRI, of diffusion weighted imaging (DWI) and of a merged criterion coupling morphological MRI and DWI. Diagnostic performance was analysed separately in different tumor subtypes, including HER2+ (human epidermal growth factor receptor 2)/HR+ (hormone receptor) (hybrid phenotype).

Materials and methods

Two-hundred and twenty-five patients underwent MRI before and after NAC. The response to treatment was defined according to the RECIST classification and the evaluation of DWI with apparent diffusion coefficient (ADC). The complete pathological response – pCR was assessed (Mandard classification).

Results

Tumor phenotypes were Luminal (63.6%), Triple Negative (16.4%), HER2+ (7.6%) or Hybrid (12.4%). After NAC, pCR was observed in 17.3% of cases. Average ADC was statistically higher after NAC (p < 0.001) among patients showing pCR vs. those who had not pCR. The RECIST classification showed adequate performance in predicting the pCR in Triple Negative (area under the receiver operating characteristic curve, ROC AUC = 0.9) and in the HER2+ subgroup (AUC = 0.826). Lower performance was found in the Luminal and Hybrid subgroups (AUC 0.693 and 0.611, respectively), where the ADC criterion yielded an improved performance (AUC = 0.787 and 0.722). The coupling of morphological and DWI criteria yielded maximally improved performance in the Luminal and Hybrid subgroups (AUC = 0.797 and 0.761).

Conclusion

The diagnostic reliability of MRI in predicting the pCR to NAC depends on the tumor phenotype, particularly in the Luminal and Hybrid subgroups. In these cases, the coupling of morphological MRI evaluation and DWI assessment may facilitate the diagnosis.     

IgG4-related kidney disease: MRI findings with emphasis on the usefulness of diffusion-weighted imaging

Objectives

To investigate the imaging findings of immunoglobulin G4 (IgG4)-related kidney disease (IgG4-KD) on magnetic resonance imaging (MRI) including diffusion-weighted imaging (DWI) and to evaluate the usefulness of DWI in lesion detection.

Methods

This retrospective cohort study included 31 patients with IgG4-KD who underwent MRI covering both kidneys. Two radiologists reviewed in consensus the MR images to determine the distribution pattern (location, laterality, and multiplicity) and the visually assessed signal intensity (hypointense, isointense or hyperintense) of the renal lesions compared to the normal renal parenchyma on each sequence. Per-patient sensitivity for detecting IgG4-KD and the number of detectable lesions were compared in T2-weighted images, DWI, and dynamic contrast-enhanced images.

Results

IgG4-KD typically manifested as bilateral (83.9%), multiple (93.5%), and renal parenchymal (87.1%) nodules appearing isointense (93.5%) on T1-weighted images, hypointense (77.4%) on T2-weighted images, hyperintense (100%) on DWI (b = 1000), and hypointense (83.3%) in the arterial phase and with a progressive enhancement pattern on dynamic contrast-enhanced images. The sensitivity of DWI for detecting IgG4-KD was significantly higher than that of T2-weighted images (100% vs. 77.4%, P = 0.034). The median number of detectable lesions was significantly greater in DWI (n = 9) than in T2-weighted images (n = 2) and dynamic contrast-enhanced images (n = 5) (P ≤ 0.008).

Conclusions

The characteristic MRI findings of IgG4-KD were bilateral, multiple, renal parenchymal nodules with T2 hypointensity, diffusion restriction, and a progressive enhancement pattern. As DWI was useful in the detection of IgG4-KD, adding DWI to conventional MRI for patients suspected of having IgG4-KD may enhance the diagnosis.     

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.     

Comparison of computed tomographic urography,magnetic resonance urography and the combination of diffusion weighted imaging in diagnosis of upper urinary tract cancer

Purpose

To evaluate the performance of computed tomographic urography (CTU), static-fluid magnetic resonance urography (static-fluid MRU) and combinations of CTU, static-fluid MRU and diffusion weighted imaging (DWI) in the diagnosis of upper urinary tract cancer.

Material and Methods

Between January 2010 and June 2011, patients with suspected UUT cancer underwent CTU, static-fluid MRU and DWI (b = 1000 s/mm ²) within a 1-week period. The diagnostic performances of CTU, static-fluid MRU and combinations of CTU, static-fluid MRU and DWI for upper urinary tract cancer were prospectively evaluated. The ureteroscopic and histopathologic findings were compared with the imaging findings.

Results

Compared to static-fluid MRU alone (sensitivity: 76/75%, reader 1/reader 2), combining DWI with MRI can increase the sensitivity (sensitivity: 84/84%, p = 0.031/p = 0.016) of upper urinary tract cancer diagnosis. CTU had greater sensitivity (95/94%) and accuracy (92/91%) than both static-fluid MRU (sensitivity: p < 0.001/p < 0.001 and accuracy: 83/81%, p = 0.001/p < 0.001) and static-fluid MRU with DWI (sensitivity: p = 0.023/p = 0.039 and accuracy: 87/85%, p = 0.042/p = 0.049) for the diagnosis of upper urinary tract cancers. Compared with CTU alone, CTU with DWI did not significantly increase sensitivity, specificity or accuracy. However, the diagnostic confidence was improved when the combined technique was used (p = 0.031/p = 0.024). Moreover, there was no significant change in sensitivity, specificity, accuracy or diagnostic confidence when static-fluid MRU was used in combination with CTU and DWI.

Conclusion

Although there is a potential role for static-fluid MRU and static-fluid MRU with DWI in urinary tract imaging, CTU is still the better choice for the diagnosis of upper urinary tract cancer. Combining DWI with CTU can help improve confidence in upper urinary tract cancer diagnoses.     

Gadoxetic acid-enhanced 3.0 T MRI for the evaluation of hepatic metastasis from colorectal cancer: Metastasis is not always seen as a “defect” on the hepatobiliary phase

Purpose

To determine specific imaging features of hepatic metastasis from colorectal cancer, focusing on the hepatobiliary phase (HBP) of gadoxetic acid-enhanced MRI.

Materials and methods

Over a 2-year period, 79 hepatic metastatic lesions were identified from 32 patients (22 men and 10 women) who proven colorectal cancer and underwent gadoxetic acid-enhanced 3.0 T MRI. Hepatic metastases were proven pathologically in 16 patients: by surgical liver resection (n = 14) and by US-guided biopsy (n = 2). The remaining 16 patients were considered to have hepatic metastasis based on imaging studies and clinical information. Two radiologists evaluated the imaging features of each MRI sequence, including high resolution T2WI, dynamic contrast enhancement study with hepatobiliary phase, and diffusion weighted image. We also compared SI of the lesions on T2WI and HBP.

Results

T2WI showed homogeneous high SI (n = 25; 31.7%), target appearance (n = 3; 3.8%), reversed target appearance (n = 2; 2.6%), and heterogeneously high SI (n = 49; 62%). On HBP, homogeneous defect were seen in 22 lesions (27.9%), target appearance in five lesions (6.4%), reversed target appearance in two lesions (2.5%), and heterogeneous defect in 50 lesions (63.3%); including reticular (70%), partially globular (26%), and diffuse GGO-like (4%) patterns. According to the imaging features on HBP, the homogeneous defect and heterogeneous defect groups had a mean ADC value of 0.99 × 10⁻³ and 1.07 × 10⁻³ mm²/s, respectively, without statistically significant difference.

Conclusion

Hepatic metastasis from colorectal cancer usually showed as a heterogeneous defect on HBP and a heterogeneous high SI on T2WI. The generally accepted “true defect” was not a common finding in hepatic metastasis from colorectal cancer.     

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.     

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.     

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.     

Differentiation between benign phyllodes tumors and fibroadenomas of the breast on MR imaging

Purpose

The purpose of this study was to determine the factors that contribute to the differentiation between phyllodes tumors (PTs) and fibroadenomas (FAs) on MR imaging.

Materials and methods

This retrospective study included 19 PTs and 18 FAs with ≥2 cm diameter. The presence or absence of a capsule and internal septum, the extent of lobulation, and the apparent diffusion coefficient (ADC) values were determined. The presence or absence of a cystic component, the time–intensity curve, and the signal intensity on delayed-phase contrast-enhanced T1WI were also evaluated in 31 patients (16 PTs and 17 FAs) who underwent a contrast-enhanced study.

Results

Cystic components were seen in 10 of the 16 PTs (63%) and in 4 of the 17 FAs (24%; P = 0.03). The PTs showed strong lobulation more frequently compared to the FAs (14/19 [74%] vs. 7/18 [39%], respectively; P = 0.04). Though there was no significant difference, PT tended to be heterogeneous more frequently on the delayed phase of the contrast-enhanced T1WI compared to the FA (11/16 [69%] vs. 7/17 [41%], respectively). No significant difference was found in the other findings.

Conclusions

Although PTs and FAs show similar MR findings, the presence of a cystic component, strong lobulation, and heterogeneity on delayed-phase contrast-enhanced T1WI suggests a PT.     

MRI signal changes in the skull base bone after endoscopic nasopharyngectomy for recurrent NPC: A serial study of 9 patients

Purpose

This study was focused on the serial changes in magnetic resonance images (MRI) of the skull-base bone that occur after endoscopic nasopharyngectomy in patients with local recurrent nasopharyngeal carcinoma (rNPC).

Materials and methods

Nine patients with histologically proven rNPC were enrolled in this study. Two experienced radiologists independently reviewed all presurgical and postsurgical MR images for each patient.

Results

At 36 sites on the skull base, the MRI signal underwent a change after surgery, which took the form of a heterogeneous pattern of hypointense regions with moderate contrast enhancement on T1WI. The onset of changes ranged between 2 weeks and 3 months after surgery. For 21 of the sites, the changes subsided over the course of follow-up, while in 6 they remained stable. At 9 sites, the alteration MRI signal became more pronounced with time. Changes were more common on the homolateral side of the skull base with respect to the recurrent tumor (P < 0.05). The skull-base bone adjacent to the resection boundary had a higher incidence of signal change than nonadjacent areas (P < 0.05).

Conclusions

MRI changes in the skull base bone, having a number of distinguishing characteristics, appear to be a common sequel to endoscopic nasopharyngectomy for rNPC.     

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.     

Diagnostic accuracy of diffusion weighted MRI in cervical lymphadenopathy cases correlated with pathology results

Introduction

Diffusion weighted magnetic resonance imaging (DW MRI) is an imaging technique showing molecular diffusion. Cell size, density and integrity influence the signal intensity seen on diffusion-weighted images. This technique is a helpful complementary tool to distinguish tumoral from non tumoral tissue.The aim of this prospective study is to define the diagnostic accuracy of DWI to differentiate benign from malignant cervical lymph nodes.

Patients and methods

Twenty six patients who presented with 32 nodes were included in this study, 9 males (35.6%) and 17 females (65.4%). Their age ranged from: 6 to 76 years, mean age 45 ± 18.8 years referred to the radiology department of NCI, complaining of neck swelling, ultrasound showed cervical nodes.

Results

According to histopathological analysis we divided the examined lymph nodes (n = 32) into 2 categories: malignant lymph nodes 75% (n = 24) benign lymph nodes 25% (n = 8). DWI and ADC (apparent diffusion coefficient) values revealed 27 malignant lesions (84%), 5 benign (16%). The accuracy of the DWMRI was 89%. A significant difference between benign and malignant cervical nodes on DWI and on ADC maps is reported.The results obtained were 24 true positive, 3 false positive, 5 true negative. No false negative cases were identified, yielding a sensitivity of 100%, specificity of 62.5%, NPV = 100% and PPV = 89%. The difference between the mean ADC values between benign and malignant lesions was statistically significant (P < 0.0001).

Conclusion

MR diffusion imaging could be an important supportive tool in differentiation between benign and malignant lymph nodes, can to a lesser extent differentiate between the types of malignant lymphadenopathy and can be used as an indicator for improvement and recurrence post chemo and radiotherapy.     

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.     

Contrast-enhanced dynamic and diffusion-weighted MR imaging at 3.0 T to assess aggressiveness of bladder cancer

Background

Diffusion weighted magnetic resonance imaging (DWI) and dynamic contrast-enhanced (DCE) MRI have been considered useful for pathological staging and histological grading in bladder cancer. To our knowledge, no study has combined the two imaging modalities together to assess aggressiveness of bladder cancer.

Objective

To assess the clinical aggressiveness of bladder cancer with DCE MRI and DWI at 3.0 T.

Materials and methods

A total of 59 patients with 69 pathologically confirmed tumor lesions were included in this study. All patients underwent MR examination at 3.0 T basing on DWI and DCE imaging. Tumor staging and histological grade were evaluated. The aggressiveness of bladder cancer was classified as low-, intermediate-, or high-aggressiveness according to its pathological phenotype. Apparent diffusion coefficient (ADC) value and semi-quantitative parameters (wash-in rate and wash-out rate) were determined. The correlation between clinical aggressiveness and ADC value, wash-in rate and wash-out rate were analyzed. In addition, the diagnostic accuracy of the diffusion and semi-quantitative parameters were estimated using receiver operating characteristic curve (ROC).

Results

Aggressiveness of bladder cancer is negatively correlated with ADC value (r = −0.705, p < 0.0001) and wash-out rate (r = −0.719, p < 0.0001). The tumor ADC value is positively correlated with wash-out rate (r = 0.555, p < 0.0001). The diagnostic specificity and accuracy using tumor ADC value and wash-out for the tumor with size <24 mm were better than that tumors with size ≥24 mm. The sensitivity, specificity and accuracy of ADC and wash-out rate in combination in diagnosis of bladder cancer aggressiveness were 96.7%, 94.9% and 95.7%, respectively. ROC curve revealed the diagnostic performance of aggressiveness of bladder cancer using ADC value and wash-out rate were 0.928 (cut-off value: 0.905 × 10⁻³ mm²/s) and 0.891 (cut-off value: 0.685 min⁻¹), respectively.

Conclusion

ADC and wash-out rate derived from DWI and DCE-MRI at 3.0 T have good potential to assess the aggressiveness of bladder cancer and the accuracy was greater for ADC than for semi-quantitative parameters.