Background Diffusion MR imaging (DWI) is a widely available non-invasive non-contrast functional MR imaging technique with short acquisition time. It helps in the analysis of tissue characteristics based on the diffusion of water protons within the tissue. Quantitative assessment of a mass is possible by calculating its apparent diffusion coefficient (ADC) value which is inversely correlated with tissue cellularity. So, DWI has diagnostic potential to distinguish benign from malignant tumors because of the tendency of the latter to show lower ADC values and more restricted diffusion. The aim of our work is to evaluate the use of DWI and ADC value measurement in differentiation between benign and malignant mediastinal tumors. Results This study included 44 cases of mediastinal masses: 27 males and 17 females. The mean ADC value of malignant mediastinal lesions was significantly lower than the mean ADC value of benign mediastinal lesions, with mean ADC 1.39 ± 0.26 in benign mediastinal lesions and mean ADC 0.86 ± 0.35 in malignant mediastinal lesions. This study also revealed that the cut-off threshold of ADC value for the differentiation between malignant and benign lesions was 1.11 × 10-3 mm2/s, with an area under ROC curve of 0.93. The sensitivity and specificity of our cutoff ADC values were 90.9% and 100%, with 100% positive predictive value and 76.9% negative predictive value. Conclusion DWI with calculation of ADC value is functional MR imaging technique used in the analysis of tissue characteristics and quantitative assessment of a mediastinal mass. So, it can distinguish benign from malignant tumors because of the tendency of the malignant lesions to show more restricted diffusion and lower ADC values.

Background Hepatocellular carcinoma (HCC) is one of the most prevalent cancers worldwide, and if left untreated, one of the most lethal. Ablative therapies including radiofrequency ablation (RFA) play increasingly important role for patients with liver tumors who are not surgical candidates. Monitoring treatment response following ablation is crucial in oncologic imaging. Dynamic contrast-enhanced MRI can assess changes in tumor vascularity and perfusion while subtraction imaging is useful in differentiating residual tumor from post-ablation parenchymal changes. The aim of this study is to compare the role of subtraction MRI and conventional dynamic MRI in assessing treatment response following RFA in patients with HCC. Results The study included 48 patients with 62 HCC lesions who underwent RFA from May to October 2020, followed by MRI evaluation with 1-month interval. Two readers with experience in hepatic imaging interpreted the dynamic and subtraction dynamic MRI. The hepatic focal lesions were classified into “well-ablated” and “residual” groups according to MRI findings, and the agreement between the two readers was evaluated. Using dynamic MRI, the first reader reported 38 well-ablated lesions, and the second reader agreed in 34 of them (89.5%). Residual disease was reported by the first reader in 22 lesions and the second reader disagreed in 10 of them (45.5%) where complete ablation was reported. Thirty-eight out 44 well-ablated lesions (86.4%) showed high signal intensity on non-enhanced T1 images, and 28 lesion (63.6%) showed intermediate T2 signal. All the mis-matched readings occurred in lesions with a high signal intensity in pre-contrast T1 images. Moderate agreement between the two readers was found with Kappa value of 0.467. Significant additive value of subtraction technique to dynamic MRI was detected with a P value of 0.009. No major complications recorded except for a single case of major portal vein branch occlusion. Conclusion MRI is a powerful imaging tool in assessing tumor viability and complications after RFA in patients with HCC. Dynamic MRI study is the gold standard in detecting recurrent lesions while subtraction technique is crucial in differentiating between arterial enhancement due to residual disease and normal hyperintense T1 signal of the ablation zone.

No abstract

Background Breast cancer is the leading cause of cancer-related mortality in women. Human epidermal growth factor receptor 2 (HER2) overexpression is seen in 20 out of 100 invasive breast cancers. Among HER2+ patients, two distinct hormone receptor (HR) subtypes can be defined: HR-positive (HR+) and HR-negative (HR−) each of which with unique therapeutic response and survival pattern. Contrast-enhanced spectral mammography (CESM) is an emerging novel imaging modality that offers diagnostic performance comparable to contrast-enhanced MRI. The purpose of this retrospective study was to describe the CESM features of HER2+ breast cancers according to hormone receptor status and to assess whether specific mammographic and CESM imaging features can differentiate between HER2+/HR+ and HER2+/HR− breast cancers potentially aiding treatment planning in HER2+ breast cancer patients. Results A total of 61 patients were included. Twenty-nine cases (47.5%) were HER2+/HR+ and 32 cases (52.5%) were HER2+/HR−. No statistically significant difference was found between mammographic imaging presentations and hormonal status. HR- were more likely to be multifocal (P 0.018), rounded or oval (P 0.008), circumscribed (P 0.004), and with associated non-mass enhancement (NME) (P < 0.001). HR+ cancers showed a tendency for irregular shape (P 0.008), spiculated outline (P 0.004), and heterogeneous (P 0.021) or ring (P 0.046) enhancement. Conclusions HER2+ tumors have different demographic, pathologic and imaging features according to the hormone receptor status. Because the two subtypes of HER2 breast cancer have different clinical outcomes, CESM imaging features can potentially enhance patient outcome by accelerating the diagnosis and treatment.

Background Magnetic resonance imaging (MRI) plays an important role in the differentiation of hepatic focal lesions and diagnosis of hepatic malignancy, especially hepatocellular carcinoma which is a major health problem worldwide. Diffusion imaging is a functional MRI technique that became an essential part of MRI study of the liver. Recently, diffusion tensor imaging (DTI) is diffusion variant that can provide more information than conventional diffusion imaging based on the tissue anisotropy. The aim of this study was to present the role of DTI in the assessment and differentiation between hepatic focal lesions. Results Fifty-one patients having 95 hepatic focal lesions who underwent dynamic MRI with conventional diffusion imaging and DTI acquisition were included in the study. A positive moderate significant correlation was found between Fractional anisotropy (FA) values and Liver Imaging Reporting and Data System (LI-RADS) category while substantial negative significant correlation and moderate negative significant correlation were found between DTI-ADC and DWI-ADC values, respectively, with the LI-RADS category. There was a significant negative correlation between DTI-ADC and FA values. DTI-ADC showed a significant role in differentiation of benign from malignant lesions with cut-off value 0.905 × 10−3 having 88.7% sensitivity and 88.3% specificity compared to 78.5% and 68.7% for DWI-ADC, respectively. Also, it was found that FA value had a significant role in differentiation between benign and malignant lesions with cut-off value 0.34 having 87.1% sensitivity and 73.9% specificity. Conclusions DTI can be included in liver MRI studies for better tissue characterization as it may perform better than conventional DWI with higher sensitivity and specificity of DTI-ADC and FA values than conventional DWI-ADC.