Assessment of the Added Value of Intravoxel Incoherent Motion Diffusion-Weighted MR Imaging in Identifying Non-Diabetic Renal Disease in Patients With Type 2 Diabetes Mellitus.

BACKGROUND: Identification of non-diabetic renal disease (NDRD) in patients with type 2 diabetes mellitus (T2DM) may help tailor treatment. Intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) is a promising tool to evaluate renal function but its potential role in the clinical differentiation between diabetic nephropathy (DN) and NDRD remains unclear. PURPOSE: To investigate the added role of IVIM-DWI in the differential diagnosis between DN and NDRD in patients with T2DM. STUDY TYPE: Prospective. POPULATION: Sixty-three patients with T2DM (ages: 22-69 years, 17 females) confirmed by renal biopsy divided into two subgroups (28 DN and 35 NDRD). FIELD STRENGTH/SEQUENCE: 3 T/ T2 weighted imaging (T2WI), and intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI). ASSESSMENT: The parameters derived from IVIM-DWI (true diffusion coefficient [D], pseudo-diffusion coefficient [D*], and pseudo-diffusion fraction [f]) were calculated for the cortex and medulla, respectively. The clinical indexes related to renal function (eg cystatin C, etc.) and diabetes (eg diabetic retinopathy [DR], fasting blood glucose, etc.) were measured and calculated within 1 week before MRI scanning. The clinical model based on clinical indexes and the IVIM-based model based on IVIM parameters and clinical indexes were established and evaluated, respectively. STATISTICAL TESTS: Student's t-test; Mann-Whitney U test; Fisher's exact test; Chi-squared test; Intraclass correlation coefficient; Receiver operating characteristic analysis; Hosmer-Lemeshow test; DeLong's test. P < 0.05 was considered statistically significant. RESULTS: The cortex D*, DR, and cystatin C values were identified as independent predictors of NDRD in multivariable analysis. The IVIM-based model, comprising DR, cystatin C, and cortex D*, significantly outperformed the clinical model containing only DR, and cystatin C (AUC = 0.934, 0.845, respectively). DATA CONCLUSION: The IVIM parameters, especially the renal cortex D* value, might serve as novel indicators in the differential diagnosis between DN and NDRD in patients with T2DM. EVIDENCE LEVEL: 2 TECHNICAL EFFICACY: Stage 2.

Intravoxel Incoherent Motion Diffusion-Weighted MR Imaging and Venous Tumor Thrombus Consistency in Renal Cell Carcinoma.

BACKGROUND: Venous tumor thrombus (VTT) consistency of renal cell carcinoma (RCC) is an important consideration in nephrectomy plus thrombectomy. However, evaluation of VTT consistency through preoperative MR imaging is lacking. PURPOSE: To evaluate VTT consistency of RCC through intravoxel incoherent motion-diffusion weighted imaging (IVIM-DWI) derived parameters (Dt , Dp , f, and ADC) and the apparent diffusion coefficient (ADC) value. STUDY TYPE: Retrospective. POPULATION: One hundred and nineteen patients (aged 55.8 ± 11.5 years, 85 male) with histologically-proven RCC and VTT who underwent radical resection. FIELD STRENGTH/SEQUENCES: 3.0-T; two-dimensional single-shot diffusion-weighted echo planar imaging sequence at 9 b-values (0-800 s/mm2 ). ASSESSMENT: IVIM parameters and ADC values of the primary tumor and the VTT were calculated. The VTT consistency (friable vs. solid) was determined through intraoperative findings of two urologists. The accuracy of VTT consistency classification based on the individual IVIM parameters of primary tumors and of VTT, and based on models combining parameters, was assessed. Type of operation, intra-operative blood loss, and operation length were recorded. STATISTICAL TESTS: Shapiro-Wilk test; Mann-Whitney U test; Student's t-test; Chi-square test; Receiver operating characteristic (ROC) analysis. Statistical significance level was P < 0.05. RESULTS: Of the enrolled 119 patients, 33 patients (27.7%) had friable VTT. Patients with friable VTT were significantly more likely to experience open surgery, have significantly more intraoperative blood loss, and significantly longer operative duration. The area under the ROC curve (AUC) values of Dt of the primary tumor and VTT in classifying VTT consistency were 0.758 (95% CI 0.671-0.832) and 0.712 (95% CI 0.622-0.792), respectively. The AUC value of the model combining Dp and Dt of VTT was 0.800 (95% CI 0.717-0.868). Furthermore, the AUC of the model combining Dp and Dt of VTT and Dt of the primary tumor was 0.886 (95% CI 0.814-0.937). CONCLUSION: IVIM-derived parameters had the potential to predict VTT consistency of RCC. EVIDENCE LEVEL: 3 Technical Efficacy: Stage 2.

Diagnostic Value of Clear Cell Likelihood Score v1.0 and v2.0 for Common Subtypes of Small Renal Masses: A Multicenter Comparative Study.

BACKGROUND: Clear cell likelihood score (ccLS) is reliable for diagnosing small renal masses (SRMs). However, the diagnostic value of Clear cell likelihood score version 1.0 (ccLS v1.0) and v2.0 for common subtypes of SRMs might be a potential score extension. PURPOSE: To compare the diagnostic performance and interobserver agreement of ccLS v1.0 and v2.0 for characterizing five common subtypes of SRMs. STUDY TYPE: Retrospective. POPULATION: 797 patients (563 males, 234 females; mean age, 53 ± 12 years) with 867 histologically proven renal masses. FIELD STRENGTH/SEQUENCES: 3.0 and 1.5 T/T2 weighted imaging, T1 weighted imaging, diffusion-weighted imaging, a dual-echo chemical shift (in- and opposed-phase) T1 weighted imaging, multiphase dynamic contrast-enhanced imaging. ASSESSMENT: Six abdominal radiologists were trained in the ccLS algorithm and independently scored each SRM using ccLS v1.0 and v2.0, respectively. All SRMs had definite pathological results. The pooled area under curve (AUC), accuracy, sensitivity, and specificity were calculated to evaluate the diagnostic performance of ccLS v1.0 and v2.0 for characterizing common subtypes of SRMs. The average κ values were calculated to evaluate the interobserver agreement of the two scoring versions. STATISTICAL TESTS: Random-effects logistic regression; Receiver operating characteristic analysis; DeLong test; Weighted Kappa test; Z test. The statistical significance level was P < 0.05. RESULTS: The pooled AUCs of clear cell likelihood score version 2.0 (ccLS v2.0) were statistically superior to those of ccLS v1.0 for diagnosing clear cell renal cell carcinoma (ccRCC) (0.907 vs. 0.851), papillary renal cell carcinoma (pRCC) (0.926 vs. 0.888), renal oncocytoma (RO) (0.745 vs. 0.679), and angiomyolipoma without visible fat (AMLwvf) (0.826 vs. 0.766). Interobserver agreement for SRMs between ccLS v1.0 and v2.0 is comparable and was not statistically significant (P = 0.993). CONCLUSION: The diagnostic performance of ccLS v2.0 surpasses that of ccLS v1.0 for characterizing ccRCC, pRCC, RO, and AMLwvf. Especially, the standardized algorithm has optimal performance for ccRCC and pRCC. ccLS has potential as a supportive clinical tool. EVIDENCE LEVEL: 4. TECHNICAL EFFICACY: Stage 2.

Effects of axial loading and positions on lumbar spinal stenosis: an MRI study using a new axial loading device.

OBJECTIVE: A new axial loading device was used to investigate the effects of axial loading and positions on lumbar structure and lumbar spinal stenosis. METHODS: A total of 40 patients sequentially underwent 4 examinations: (1) the psoas-relaxed position MRI, (2) the extended position MRI, (3) the psoas-relaxed position axial loading MRI, (4) the extended position axial loading MRI. The dural sac cross-sectional area, sagittal vertebral canal diameter, disc height and ligamentum flavum thickness of L3-4, L4-5, L5-S1 and lumbar lordosis angle were measured and compared. A new device with pneumatic shoulder-hip compression mode was used for axial loading. RESULTS: In the absence of axial loading, there was a significant reduction in dural sac cross-sectional area with extension only seen at the L3-4 (p = 0.033) relative to the dural sac area in the psoas-relaxed position. However, with axial loading, there was a significant reduction in dural sac cross-sectional area at all levels in both psoas-relaxed (L3-4, p = 0.041; L5-S1, p = 0.005; L4-5, p = 0.002) and extension (p < 0.001) positions. The sagittal vertebral canal diameter and disc height were significantly reduced at all lumbar levels with axial loading and extension (p < 0.001); however, in psoas-relaxed position, the sagittal vertebral canal diameter was only reduced with axial loading at L3-4 (p = 0.018) and L4-5 (p = 0.011), and the disc height was reduced with axial-loading at all levels (L3-4, p = 0.027; L5-S1, p = 0.001; L4-5, p < 0.001). The ligamentum flavum thickness and lumbar lordosis in extension position had a statistically significant increase compared to psoas-relaxed position with or without axial loading (p < 0.001). CONCLUSION: Both axial loading and extension of lumbar may exacerbate lumbar spinal stenosis. Axial loading in extension position could maximally aggravate lumbar spinal stenosis, but may cause some patients intolerable. For those patients, axial loading MRI in psoas-relaxed position may be a good choice.

Differentiating active from Inactive Sacroiliitis in ankylosing spondylitis by combination of DWI and Magnetization Transfer Imaging.

Objectives: To evaluate lesions of sacroiliac joint (SIJ) by combination of diffusion-weighted imaging (DWI) and magnetization transfer (MT). Methods: A retrospective study was used in this study. Forty-nine ankylosing spondylitis (AS) patients admitted to The China Academy of Chinese Medical Sciences Xiyuan Hospital from May 2020 to October 2020 were collected into active and inactive groups. Twenty-two healthy volunteers were recruited. Apparent diffusion coefficient (ADC) values for bone marrow edema (BME), sclerosis area, fat deposit area, and normal-appearing bone marrow (NABM) (both patients and healthy volunteers) and the magnetization transfer (MT) rate of the cartilage (MTRc) were analyzed in the groups. The above five parameters (ADC (NABM), ADC (BME) and ADC (fat deposit) and MTRc) between the active group and the inactive group were compared. The effectiveness of each parameter in diagnosing sacroiliac arthritis of ankylosing spondylitis were analyzed, and the predictive value of the parameters was compared. Result: ADC(BME), ADC(NABM) and MTRc showed statistically significant differences between the active and inactive groups (P <0.05). ADC (BME) and ADC (NABM) could predict the activity of AS sacroiliac arthritis (P <0.01). ADC (NABM) and MTRc were significantly different between healthy volunteers and the active group (P <0.01). The areas under the ROC curve (AUCs) of ADC (BME)_ADC(NABM), ADC(NABM)_MTR, and ADC(BME)_MTRc were 0.885 (cut-off value=0.69), 0.849 (cut-off value=0.56) and 0.864 (cut-off value=0.60), respectively. The predictive ability of the combined index ADC (BME)_MTRc and ADC(NABM)_MTRc was increased. Conclusion: The ability to diagnose and predict AS might be improved by the combination of diffusion-weighted imaging (DWI) and magnetization transfer (MT).

MRI radiomics-based nomogram for individualised prediction of synchronous distant metastasis in patients with clear cell renal cell carcinoma.

OBJECTIVE: To evaluate the performance of a multiparametric MRI radiomics-based nomogram for the individualised prediction of synchronous distant metastasis (SDM) in patients with clear cell renal cell carcinoma (ccRCC). METHODS: Two-hundred and one patients (training cohort: n = 126; internal validation cohort: n = 39; external validation cohort: n = 36) with ccRCC were retrospectively enrolled between January 2013 and June 2019. In the training cohort, the optimal MRI radiomics features were selected and combined to calculate the radiomics score (Rad-score). Incorporating Rad-score and SDM-related clinicoradiologic characteristics, the radiomics-based nomogram was established by multivariable logistic regression analysis, then the performance of the nomogram (discrimination and clinical usefulness) was evaluated and validated subsequently. Moreover, the prediction efficacy for SDM in ccRCC subgroups of different sizes was also assessed. RESULTS: Incorporating Rad-score derived from 9 optimal MR radiomics features (age, pseudocapsule and regional lymph node), the radiomics-based nomogram was capable of predicting SDM in the training cohort (area under the ROC curve (AUC) = 0.914) and validated in both the internal and external cohorts (AUC = 0.854 and 0.816, respectively) and also showed a convincing predictive power in ccRCC subgroups of different sizes (≤ 4 cm, AUC = 0.875; 4-7 cm, AUC = 0.891; 7-10 cm, 0.908; > 10 cm, AUC = 0.881). Decision curve analysis indicated that the radiomics-based nomogram is of clinical usefulness. CONCLUSIONS: The multiparametric MRI radiomics-based nomogram could achieve precise individualised prediction of SDM in patients with ccRCC, potentially improving the management of ccRCC. KEY POINTS: • Radiomics features derived from multiparametric magnetic resonance images showed relevant association with synchronous distant metastasis in clear cell renal cell carcinoma. • MRI radiomics-based nomogram may serve as a potential tool for the risk prediction of synchronous distant metastasis in clear cell renal cell carcinoma.

MRI-based Bosniak Classification of Cystic Renal Masses, Version 2019: Interobserver Agreement, Impact of Readers' Experience, and Diagnostic Performance.

Background The 2019 Bosniak classification (version 2019) of cystic renal masses (CRMs) provides a systematic update to the currently used 2005 Bosniak classification (version 2005). Further validation is required before widespread application. Purpose To evaluate the interobserver agreement of MRI criteria, the impact of readers' experience, and the diagnostic performance between version 2019 and version 2005. Materials and Methods From January 2009 to December 2018, consecutive patients with CRM who had undergone renal MRI and surgical-pathologic examination were included in this retrospective study. On the basis of version 2019 and version 2005, all CRMs were independently classified by eight radiologists with different levels of experience. By using multirater κ statistics, interobserver agreement was evaluated with comparisons between classifications and between senior and junior radiologists. Diagnostic performance between classifications by dichotomizing classes I-IV into lower (I-IIF) and higher (III-IV) classes was compared by using the McNemar test. P < .05 was considered to indicate a statistically significant difference. Results A total of 207 patients (mean age ± standard deviation, 49 years ± 12; 139 male and 68 female patients) with CRMs were included. Overall, interobserver agreement was higher with version 2019 than version 2005 (weighted κ = 0.64 vs 0.50, respectively; P < .001). Interobserver agreement between senior and junior radiologists did not differ between version 2019 (weighted κ = 0.65 vs 0.64, respectively; P = .71) and version 2005 (weighted κ = 0.54 vs 0.46; P < .001). Diagnostic specificity for malignancy was higher with version 2019 than with version 2005 (83% [92 of 111] vs 68% [75 of 111], respectively; P < .001), without any difference in sensitivity (89% [85 of 96] vs 84% [81 of 96]; P = .34). Conclusion In the updated Bosniak classification, interobserver agreement improved and was unaffected by observers' experience. The diagnostic performance with version 2019 was superior to that with version 2005, with higher specificity. Published under a CC BY 4.0 license. Online supplemental material is available for this article. See also the editorial by Choyke in this issue.

Multiparametric MRI Radiomic Model for Preoperative Predicting WHO/ISUP Nuclear Grade of Clear Cell Renal Cell Carcinoma.

BACKGROUND: Nuclear grade is of importance for treatment selection and prognosis in patients with clear cell renal cell carcinoma (ccRCC). PURPOSE: To develop and validate an MRI-based radiomic model for preoperative predicting WHO/ISUP nuclear grade in ccRCC. STUDY TYPE: Retrospective. POPULATION: In all, 379 patients with histologically confirmed ccRCC. Training cohort (n = 252) and validation cohort (n = 127) were randomly assigned. FIELD STRENGTH/SEQUENCE: Pretreatment 3.0T renal MRI. Imaging sequences were fat-suppressed T2 WI, contrast-enhanced T1 WI, and diffusion weighted imaging. ASSESSMENT: Three prediction models were developed using selected radiomic features, radiomic and clinicoradiologic characteristics, and a model containing only clinicoradiologic characteristics. Receiver operating characteristic (ROC) curves and area under the curve (AUC) were used to assess the predictive performance of these models in predicting high-grade ccRCC. STATISTICAL TESTS: The least absolute shrinkage and selection operator (LASSO) and minimum redundancy maximum relevance (mRMR) method were used for the selection of radiomic features and clinicoradiologic characteristics, respectively. Multivariable logistic regression analysis was used to develop the radiomic signature of radiomic features and clinicoradiologic model of clinicoradiologic characteristics. RESULTS: The radiomic signature showed good performance in discriminating high-grade (grades 3 and 4) from low-grade (grades 1 and 2) ccRCC, with sensitivity, specificity, and AUC of 77.3%, 80.0%, and 0.842, respectively, in the validation cohort. The radiomic model, combining radiomic signature and clinicoradiologic characteristics, displayed good predictive ability for high-grade with sensitivity, specificity, and accuracy of 63.6%, 93.3%, and 88.2%, respectively, in the validation cohort. The radiomic model showed a significantly better performance than the clinicoradiologic model (P < 0.05). DATA CONCLUSION: Multiparametric MRI-based radiomic model can predict WHO/ISUP grade in patients with ccRCC with satisfying performance, and thus could help the physician to improve treatment decisions. LEVEL OF EVIDENCE: 3 TECHNICAL EFFICACY STAGE: 2.

Controlled attenuation parameter by vibration-controlled transient elastography for steatosis assessment in members of the public undergoing regular health checkups with reference to magnetic resonance imaging-based proton density fat fraction.

AIM: Controlled attenuation parameter (CAP) measured by vibration-controlled transient elastography (FibroScan) allows repeatable and reliable assessment of liver steatosis for screening of patients at risk of non-alcoholic steatohepatitis development among asymptomatic individuals at a community level. However, this has never been compared with another quantitative method, such as magnetic resonance imaging-based proton density fat fraction, among the Chinese health checkup population. METHODS: A multicenter prospective study was conducted with Chinese individuals undergoing regular health checkups. Steatosis grading by magnetic resonance imaging-based proton density fat fraction was used as the reference to evaluate the diagnostic performance of CAP. RESULTS: A total of 173 individuals were included with mean age of 45 ± 11 years and body mass index of 25.8 ± 4.0 kg/m2 . A linear correlation was found between CAP and log10 -transformed magnetic resonance imaging-based proton density fat fraction results (Pearson's coefficient 0.772, P < 0.001). The areas under the receiver operating characteristic curve for distinguishing ≥S1 and ≥S2 steatosis were 0.88 (95% confidence interval 0.83-0.93) and 0.89 (95% confidence interval 0.83-0.95), respectively. When optimized for ≥90% sensitivity, the CAP cut-off for staging ≥S1 steatosis was 244 dB/m. CAP could classify patients with ≥S1 steatosis with similar performance as an ultrasound examination. CONCLUSIONS: As a non-invasive and quantitative method, CAP is highly adapted for population screening at a community level. With the integration of liver stiffness and CAP results in risk stratification scores for non-alcoholic steatohepatitis, vibration-controlled transient elastography can be useful in regular health checkups.

Value of Texture Analysis of Intravoxel Incoherent Motion Parameters in Differential Diagnosis of Pancreatic Neuroendocrine Tumor and Pancreatic Adenocarcinoma.

Objective To evaluate the value of texture features derived from intravoxel incoherent motion (IVIM) parameters for differentiating pancreatic neuroendocrine tumor (pNET) from pancreatic adenocarcinoma (PAC).Methods Eighteen patients with pNET and 32 patients with PAC were retrospectively enrolled in this study. All patients underwent diffusion-weighted imaging with 10 b values used (from 0 to 800 s/mm 2). Based on IVIM model, perfusion-related parameters including perfusion fraction (f), fast component of diffusion (Dfast) and true diffusion parameter slow component of diffusion (Dslow) were calculated on a voxel-by-voxel basis and reorganized into gray-encoded parametric maps. The mean value of each IVIM parameter and texture features [Angular Second Moment (ASM), Inverse Difference Moment (IDM), Correlation, Contrast and Entropy] values of IVIM parameters were measured. Independent sample t-test or Mann-Whitney U test were performed for the between-group comparison of quantitative data. Regression model was established by using binary logistic regression analysis, and receiver operating characteristic (ROC) curve was plotted to evaluate the diagnostic efficiency.Results The mean f value of the pNET group were significantly higher than that of the PAC group (27.0% vs. 19.0%, P = 0.001), while the mean values of Dfast and Dslow showed no significant differences between the two groups. All texture features (ASM, IDM, Correlation, Contrast and Entropy) of each IVIM parameter showed significant differences between the pNET and PAC groups (P=0.000-0.043). Binary logistic regression analysis showed that texture ASM of Dfast and texture Correlation of Dslow were considered as the specific imaging variables for the differential diagnosis of pNET and PAC. ROC analysis revealed that multiple texture features presented better diagnostic performance than IVIM parameters (AUC 0.849-0.899 vs. 0.526-0.776), and texture ASM of Dfast combined with Correlation of Dslow in the model of logistic regression had largest area under ROC curve for distinguishing pNET from PAC (AUC 0.934, cutoff 0.378, sensitivity 0.889, specificity 0.854).Conclusions Texture analysis of IVIM parameters could be an effective and noninvasive tool to differentiate pNET from PAC.

Nuclear magnetic resonance evaluation of inflammatory activity from chronic viral Hepatitis B.

OBJECTIVES: To discuss the value of applying magnetic resonance diffusion-weighted imaging (DWI) to evaluate inflammatory activity from chronic viral hepatitis B. METHODS: One hundred forty-two patients with chronic viral hepatitis B who received treatment at The Fifth Medical Center of Chinese PLA General Hospital from January 2014 to December 2015 and 20 healthy persons in the control group who were scheduled to undergo nuclear magnetic resonance scanning and DWI examinations (b value = 0, 800 s/mm2), and the apparent diffusion coefficients (ADCs) were measured and compared with the biopsy results of hepatic tissue. RESULTS: The ADC value of the group with hepatitis B was lower than that of the healthy group (P<0.05), and the ADC value of the group with mild inflammation (G1) significantly differed from that of the group with moderate inflammation (G2) and that of the group with severe inflammation (G3-G4) (P<0.05). CONCLUSIONS: Magnetic resonance diffusion-weighted imaging technology has high clinical value for evaluating the inflammatory activity from chronic hepatitis B, and the measured ADC value corresponds to the pathological grade well, so this method is worth clinical promotion and application.

MR imaging features of benign retroperitoneal paragangliomas and schwannomas.

BACKGROUND: To determine whether MRI feature analysis can differentiate benign retroperitoneal extra-adrenal paragangliomas and schwannomas. METHODS: The MRI features of 50 patients with confirmed benign retroperitoneal extra-adrenal paragangliomas and schwannomas were retrospectively reviewed by two radiologists blinded to the histopathologic diagnosis. These features were compared between two types of tumours by use of the Mann-Whitney test and binary logistic regression. The patients' clinical characteristics were reviewed. RESULTS: Analysis of MRI images from 50 patients revealed no significant differences in the quantitative MRI features of lesion size, ratio of diameter and apparent diffusion coefficient. There were significant differences in the qualitative MRI features of location, necrosis, cysts and degree of tumour enhancement for two readers, with no significant differences in the other qualitative MRI features between these tumours. The combination of necrosis with degree of tumour enhancement during the arterial phase increased the probability that a retroperitoneal mass would represent retroperitoneal extra-adrenal paraganglioma as opposed to schwannoma. CONCLUSION: We have presented the largest series of MRI features of both benign retroperitoneal extra-adrenal paragangliomas and schwannomas. Some MRI features assist in the differentiation between these tumours, with imaging features consisting of necrosis and avid enhancement during the arterial phase, suggestive of retroperitoneal extra-adrenal paragangliomas.

MRI features after prostatic artery embolization for the treatment of medium- and large-volume benign hyperplasia.

PURPOSE: To assess magnetic resonance imaging (MRI) features after prostatic artery embolization (PAE) for the treatment of medium- and large-volume benign prostatic hyperplasia and to correlate prostate volume with clinical indexes. METHODS: We retrospectively evaluated 28 patients who underwent PAE. MRI examinations of the prostate were performed to evaluate signal intensity changes and the characteristics of infarcted areas. Prostate volume and the apparent diffusion coefficient (ADC) were measured at an average of 10 days post-PAE and at 1, 3, 6, and 12 months post-PAE. Some clinical indexes were evaluated before and 12 months after PAE. The paired t test, ANOVA, and multiple linear correlation analyses were performed by using the statistical software, SPSS. RESULTS: All patients experienced prostatic infarction. The prostate volume decreased continuously (p < 0.05). The ADC values before and after 1, 3, 6, or 12 months of embolization (b = 1000 and 2000 s/mm2) were statistically significantly different. The ADC values (b = 3000 s/mm2) were also statistically significantly different before and at each interval time after embolization (p < 0.05). Prostate volume changes correlated significantly with patient age and post-void residual urine volume (p < 0.05). CONCLUSIONS: MRI can be used for assessing changes in signal intensity and ADC values of infarction as well as the volume of the prostate after PAE. After PAE, ultrahigh b value diffusion-weighted imaging (DWI) can show early infarction better than lower b value DWI.

Diffusion-weighted imaging versus contrast-enhanced MR imaging for the differentiation of renal oncocytomas and chromophobe renal cell carcinomas.

OBJECTIVES: To compare the performance of diffusion-weighted imaging (DWI) with that of contrast-enhanced MRI in differentiating renal oncocytomas from chromophobe renal cell carcinomas (RCCs). METHODS: We recruited 48 patients with histopathologically confirmed renal oncocytomas (n=16) and chromophobe RCCs (n=32). All patients underwent preoperative DWI and contrast-enhanced MRI. Apparent diffusion coefficient (ADC) and signal intensity were measured in each patient. ADC ratio and percentage of signal intensity change were calculated. RESULTS: Mean ADC values for renal oncoctytomas were significantly higher than those for chromophobe RCCs (1.59±0.21 vs. 1.09±0.29× 10-3 mm2/s, p < 0.001). Area under the ROC curve, sensitivity and specificity were 0.931, 87.5% and 84.4%, respectively, for ADC measurement of DW imaging; 0.825, 87.5% and 75%, respectively, for enhancement ratio (p > 0.05). Adding ADC values to the enhancement ratios in the ROC, analysis to differentiate renal oncocytoma from chromophobe RCCs increased specificity from 75 to 87.5% at 87.5% sensitivity without significantly increasing the AUC (0.930). CONCLUSIONS: Both DWI and contrast-enhanced MRI may assist in differentiating renal oncocytomas from chromophobe RCCs, with DWI showing higher diagnostic value. The combination of the two parameters could potentially provide better performance in distinguishing these two tumours. KEY POINTS: • ADC values can assist in differentiating renal oncocytomas from chromophobe RCCs. • DW imaging possesses better specificity than does contrast-enhanced MR imaging. • Combining the two parameters provides higher specificity regarding the differential diagnosis.

Ultra-high b-value diffusion-weighted imaging features of the prostatic leiomyoma-case report.

BACKGROUND: Leiomyoma of the prostate is a rare benign tumor arising from smooth muscle fibers. Most cases are incidental findings observed during pathological examinations after resection of the prostate. To the best of our knowledge, only few studies have reported the conventional magnetic resonance imaging (MRI) findings of such tumors; however, no reports have described the ultra-high b-value diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) findings of prostatic leiomyomas. CASE PRESENTATION: We report MR imaging characteristics and surgical pathologic findings of a case of prostatic leiomyoma treated by robot-assisted transperitoneal laparoscopic approach. Typical MR features showed a homogeneous lesion with slightly hypointense signal compared to the skeletal muscle on T2-weighted images, and isointense signal relative to the muscle on T1-weighted images with fat suppression, which collectively demonstrate apparent homogeneous enhancement with a non-enhanced envelope. A slightly hyperintense signal compared to the skeletal muscle was observed on ultra-high b-value DWI, and higher ADC values were observed as compared to the prostate cancer. CONCLUSIONS: Prostatic leiomyoma is a benign tumor. This case indicates that MRI features of prostatic leiomyoma are helpful for the differential diagnosis of prostate cancer.

Renal epithelioid angiomyolipoma: MRI findings.

PURPOSE: To retrospectively analyze the MR imaging presentation of renal epithelioid angiomyolipoma (EAML). METHODS: Retrospective analysis revealed 12 subjects with histologically proven renal EAML who underwent preoperative MRI at our institution between January 2009 and June 2016. Two radiologists reviewed the images in consensus, describing MR imaging features including size, location, growth pattern, signal intensity of tumor, and dynamic enhancement pattern. RESULTS: Nine women and three men were included. The average maximum tumor diameter was 7.1 cm. Exophytic growth was present in 9/12 cases, mesophytic growth in 2/12, and endophytic growth in 1/12. On T1-weighted images, 2/12 displayed homogeneous isointensity, 1/12 homogeneous hyperintensity, 5/12 heterogeneous hypointensity, and 4/12 heterogeneous hyperintensity. Macroscopic fat was detected in 5/12 cases and microscopic fat in 6/12 cases. On T2-weighted images, 5/12 showed heterogeneous hypointensity, 4/12 heterogeneous hyperintensity, and 3/12 homogeneous hypointensity. On dynamic contrast-enhanced MR images, 7/12 showed a slow washout enhancement pattern, 2/12 a rapid washout pattern, 2/12 progressive enhancement, and 1/12 persistent enhancement. Imaging findings were suggestive of hemorrhage (50%), necrosis (25%), or cystic change (50%) within the tumors. Enlarged vessels were detected in 5/12 cases. One tumor extended into the renal sinus. No metastases were found on the preoperative MR imaging. CONCLUSION: Although MRI appearances of renal EAML were various, some MRI characteristics may contribute to suggest the possibility of renal EAML.

Clinical and Magnetic Resonance Imaging Features of Solid Pseudopapillary Tumor of the Pancreas in Male Patients.

Objective To analyze the clinical and magnetic resonance imaging(MRI)findings of solid pseudopapillary tumor(SPT)of the pancreas in male patients. Methods Clinical and MRI features of 51 patients with pathologically-proved SPT were retrospectively analyzed.The following MRI features of the lesions were analyzed:location,maximal diameter,shape,margin,capsule,solid and cystic components,signal intensity characteristics,and enhancement patterns.Results The average maximal diameter of the SPT in male patients was significantly smaller [(3.9±1.6)cm vs.(6.3±3.9)cm,P=0.035]than that of SPT in female patients.Pure solid tumors were signiciantly more common in male patients(8/14)than in female patients(9/37)(P=0.037).T1-weighted images of SPT showed mainly homogenous hypo-intensity in male patients(11/14)and heterogeneous hypo-intensity in female patients(23/37)(P=0.001).Hemorrhage was more prevalent in female patients(22/37)than in male patients(2/14)(P=0.005).There were no significant differences between male and female patients regarding clinical features and other magnetic resonance features(P>0.05).Conclusions On MRI,SPT in male patients is small and shows mainly pure solid component with rare hemorrhage.The clinical and other MRI features of SPT are not different between males and females.

Quantitative comparison of MR diffusion-weighted imaging for liver focal lesions between 3.0T and 1.5T: Regions of interest of the minimum-spot ADC, the largest possible solid part, and the maximum diameter in lesions.

PURPOSE: To quantitatively compare the apparent diffusion coefficient (ADC) values of 3.0T and 1.5T magnetic resonance (MR) diffusion-weighted imaging (DWI) protocols using regions of interest (ROIs) for the minimum ADC, largest solid part, and maximum diameter of lesions, for the detection of liver focal lesions. MATERIALS AND METHODS: In total, 26 patients with 28 liver focal lesions prospectively underwent both 1.5T and 3.0T DWI of the liver. The protocols included respiratory-triggered (RT), breath-holding (BH), and free-breathing (FB) acquisitions. The ADC values were measured at both field strengths using three methods: ROIs with the minimum ADC, the largest solid part, and the maximum diameter of lesions. Bland-Altman tests and paired t-tests were used to compare ADC values in the liver focal lesions obtained at 1.5T and 3.0T. RESULTS: The 3.0T and 1.5T protocols differed significantly with regard to the ADC values of the RT, BH, and FB acquisitions, for ROIs of both the largest solid part (P = 0.005, P = 0.014, and P = 0.022, respectively) and maximum diameter of lesions (P < 0.001, P = 0.001, and P = 0.001, respectively). CONCLUSION: When using DWI for quantitative analysis of liver focal lesions, field strength could exert a negative effect depending on the ROI. The ADC values from ROIs of both the largest solid part and maximum diameter of lesions may differ between 1.5T and 3.0T protocols.J. Magn. Reson. Imaging 2016;44:1320-1329.

[Intravoxel incoherent motion dwi in renal tumors: differentiation between benign and malignant masses].

OBJECTIVE: To evaluate the performance of intravoxel incoherent motion (IVIM) diffusion-weighted MR imaging in the differential diagnosis of Angiomyolipoma (AML), clear cell renal cell carcinoma (clear cell RCC) and non-clear cell renal cell carcinoma (non-clear cell RCC). METHOD: Forty-five patients were enrolled and classified into three groups according to the surgical pathology results. There were even amount of subjects (15) in each group of AML group, clear cell RCC group and non-clear cell RCC group (including 6 Papillary RCC and 9 Chromophobe RCC). ALL the patients underwent respiratory-triggered DWI on 3.0T MR system using multi b-values of 0, 20, 50, 100, 150, 200, 400, 600, 800 sec/mm2. Pure molecular-based (D), perfusion-related (D*) and vascular fraction (f) were calculated using a bi-exponential model. Comparisons of derived parameters derived by IVIM-DWI among three groups were performed using One-way ANOVA. RESULTS: D in clear cell RCC (1.8±1.5)×10(-3) mm2/s was significantly higher than that in AML (0.7±0.3)×10(-3) mm2/s or non-clear cell RCC (0.9±0.3)×10(-3) mm2/s (P<0.05), while no statistical difference was observed between AML and non-clear cell RCC (P=0.807). D* demonstrated significant difference between AML (33.3±18.2)×10(-3) mm2/s and non-clear cell RCC (17.8±17.3)×10(-3) mm2/s, (P<0.05). No observed significant difference in f was revealed between any two groups. CONCLUSION: Pure water molecules (true diffusion) and capillary microcirculation (pseudo-diffusion) may result in the observed difference of parameters in these three types of renal tumors. D value can contribute to differentiate the clear cell RCC from AML, and between clear cell and non-clear cell RCC as well. D* value may be applied to differentiate AML from non-clear cell RCC.

[Study of ADC value in healthy adults kidney of different age groups].

OBJECTIVE: To evaluate the changes of ADC value on renal parenchyma at different age groups in healthy adults. METHODS: One hundred healthy adults were divided into five groups based on age:namely 18-29 years, 30-39 years, 40-49 years, 50-59 years and 60-69 years. All adults underwent diffusion-weighted magnetic resonance(MR) imaging of the kidneys with b values of 800 s/mm(2). ADC values of renal parenchyma were measured by the manufacturer's software. RESULTS: With the increasing of age , the renal parenchyma ADCs decrease. The ADCs of renal parenchyma in five age groups were (2.07 ± 0.10) ×10(-3)mm(2)/s, (2.06 ± 0.12) ×10(-3)mm(2)/s, (2.03 ± 0.10) ×10(-3)mm(2)/s, (1.98 ± 0.17) ×10(-3)mm(2)/s and (1.94 ± 0.12) ×10(-3)mm(2)/s, which had statistically significant different (F = 3.375, P < 0.05). CONCLUSION: (1)The ADCs of renal parenchyma may be influenced by age , with the increasing of age, ADCs of normal kidney presented tenuous decreasing tendency especially the people aged ≥ 40 years; (2)in clinical application, we ought to pay attention to the influence of age factor. Income data of this study can be took as normal reference value in other more study.