Yanguang Shen

Predicting Prostate Biopsy Outcomes: A Preliminary Investigation on Screening with Ultrahigh B-Value Diffusion-Weighted Imaging as an Innovative Diagnostic Biomarker

Background Routine screening of prostate specific antigen (PSA) is no longer recommended because of a high rate of over-diagnosis of prostate cancer (PCa). Objective To evaluate the efficacy of diffusion-weighted magnetic resonance imaging (DW-MRI) for PCa detection, and to explore the clinical utility of ultrahigh b-value DW-MRI in predicting prostate biopsy outcomes. Methodology 73 male patients were selected for the study. They underwent 3T MRI using T2WI conventional DW-MRI with b-value 1000 s/mm2, and ultrahigh b-value DW-MRI with b-values of 2000 s/mm2 and 3000 s/mm2. Two radiologists evaluated individual prostate gland images on a 5-point rating scale using PI-RADS, for the purpose of region-specific comparisons among modalities. Sensitivity, specificity, accuracy, positive predictive value (PPV), negative predictive value (NPV) and likelihood ratios (LR) were investigated for each MRI modality. The area under the receiver operating characteristic (ROC) curve (AUC) was also calculated. Results Results showed the improved diagnostic value of ultrahigh b-value DWI-MRI for detection of PCa when compared to other b values and conventional MRI protocols. Sensitivity values for 3000 s/mm2 in both peripheral zone (PZ) and transition zone (TZ) were significantly higher than those observed with conventional DW-MRI—Specificity values for 3000 s/mm2 in the TZ were significantly higher than other b-value images, whereas specificity values using 3000 s/mm2 in the PZ were not significantly higher than 2000 s/mm2 images. PPV and NPV between 3000 s/mm2 and the other three modalities were significantly higher for both PZ and TZ images. The PLRs and NLRs of b-value 3000 s/mm2 DW-MRI in the PZ and TZ were also recorded. ROC analysis showed greater AUCs for the b value 3000 s/mm2 DWI than for the other three modalities. Conclusions DW-MRI with a b-value of 3000 s/mm2 was found to be the most accurate and reliable MRI modality for PCa tumor detection and localization, particularly for TZ lesion discrimination. It may be stated that the b-value of 3000 s/mm2 is a novel, improved diagnostic biomarker with greater predictive accuracy for PCa prior to biopsy.

Renal epithelioid angiomyolipoma: MRI findings

PurposeTo retrospectively analyze the MR imaging presentation of renal epithelioid angiomyolipoma (EAML).MethodsRetrospective 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.ResultsNine women and three men were included. The average maximum tumor diameter was 7.1xa0cm. 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.ConclusionAlthough MRI appearances of renal EAML were various, some MRI characteristics may contribute to suggest the possibility of renal EAML.

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

ObjectivesTo compare the performance of diffusion-weighted imaging (DWI) with that of contrast-enhanced MRI in differentiating renal oncocytomas from chromophobe renal cell carcinomas (RCCs).MethodsWe 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.ResultsMean 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).ConclusionsBoth 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.

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

PurposeTo 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.MethodsWe 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 10xa0days post-PAE and at 1, 3, 6, and 12xa0months post-PAE. Some clinical indexes were evaluated before and 12xa0months after PAE. The paired t test, ANOVA, and multiple linear correlation analyses were performed by using the statistical software, SPSS.ResultsAll patients experienced prostatic infarction. The prostate volume decreased continuously (pu2009<u20090.05). The ADC values before and after 1, 3, 6, or 12xa0months of embolization (bu2009=u20091000 and 2000xa0s/mm2) were statistically significantly different. The ADC values (bu2009=u20093000xa0s/mm2) were also statistically significantly different before and at each interval time after embolization (pu2009<u20090.05). Prostate volume changes correlated significantly with patient age and post-void residual urine volume (pu2009<u20090.05).ConclusionsMRI 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.

MR imaging features of benign retroperitoneal paragangliomas and schwannomas

BackgroundTo determine whether MRI feature analysis can differentiate benign retroperitoneal extra-adrenal paragangliomas and schwannomas.MethodsThe 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.ResultsAnalysis 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.ConclusionWe 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.

Measurement and scan reproducibility of parameters of intravoxel incoherent motion in renal tumor and normal renal parenchyma: a preliminary research at 3.0 T MR

PurposeTo prospectively estimate measurement and scan reproducibility of parameters of intravoxel incoherent motion (IVIM) in renal tumors, normal renal cortex, and medulla.MethodsTwenty-four consecutive patients (twelve males and twelve females; median age 56.7xa0years, range 32–71xa0years) with 25 renal tumors (20 renal cell carcinomas, one urothelium carcinoma, three angiomyolipomas, and one oncocytoma) were examined twice using IVIM1 and IVIM2 with 9 and 16 b values, respectively, at 3.0xa0T. All the patients were re-scanned in 24–48xa0h. Regions of interest (ROIs) were placed in solid part of tumor, normal cortex, and medulla to derive IVIM parameters D (true diffusion coefficient), D* (pseudodiffusion coefficient), and f (perfusion fraction of pseudodiffusion). Differences in parameters between two IVIM sets and intra-observer, inter-observer, and scan–rescan differences were assessed using paired t tests. Intra-observer, inter-observer, and scan–rescan reproducibility were assessed by measuring coefficient of variation and Bland–Altman limits of agreements.ResultsIntra-observer reproducibility of renal tumors, normal renal cortex, and medulla was excellent for apparent diffusion coefficient (ADC; CV: 3.45%–5.34%, BA-LA: −14% to 18%) and D (CV: 3.65% to 6.04%, BA-LA: −18% to 19%), good for f (CV: 11.96%–16.08%, BA-LA: −76.4% to 92.1% except f of medulla with CV of 32.59% and BA-LA of −76.4% to 92.1% in IVIM1), and poor for D* (CV: 25.0% to 75.4%, BA-LA: −111% to 150%). The same order was in inter-observer reproducibility analysis. Scan–rescan reproducibility was the worst of the three parameters. Renal medulla showed worse reproducibility than renal tumors and the normal cortex. The metrics of IVIM2 had better reproducibility than IVIM1.ConclusionExcellent reproducibility evaluation for ADC and D, good for f, and poor for D* derived from IVIM was performed in renal tumors, normal renal cortex, and medulla. D* has limited reliability and scan–rescan reproducibility should be improved.

High signal renal tumors on DWI: the diagnostic value of morphological characteristics

PurposeTo assess the usefulness of morphological characteristics of diffusion-weighted imaging (DWI) for differentiating malignant renal tumors from benign renal tumors, and clear cell renal cell carcinoma (RCC) from non-clear cell RCC at 3.0xa0T.MethodsThe study included 249 patients with 251 histopathologically confirmed renal tumors that showed high signal on DWI. For each tumor, two radiologists independently evaluated apparent diffusion coefficient (ADC) values and morphological characteristics of DWI. The differences in the quantitative and qualitative magnetic resonance imaging (MRI) features determined by the readers were assessed. The ADC values between malignant and benign renal tumors and between clear cell and non-clear cell RCC were compared using Mann–Whitney tests. The proportional differences of morphological characteristics of DWI between malignant and benign renal tumors and between clear cell and non-clear cell RCC were compared using Chi-square tests.ResultsThere were no significant differences in the quantitative and qualitative MRI features determined by the readers. The ADC values for malignant renal tumors were statistically significantly higher than those for benign renal tumors (pu2009<u20090.05), and the ADC values for clear cell RCC were statistically significantly higher than those for non-clear cell RCC (pu2009<u20090.05). The proportion of morphological characteristics of DWI between malignant and benign renal tumors was statistically significantly different at ring, nodular, flaky high signal. The proportion of morphological characteristics of DWI between clear cell and non-clear cell RCC was statistically significantly different at uniform high signal.ConclusionsThe morphological characteristics of DWI are useful in differentiating renal tumors.

MR imaging features of benign retroperitoneal extra-adrenal paragangliomas

The goal of this study was to retrospectively review the magnetic resonance imaging (MRI) features of retroperitoneal extra-adrenal paragangliomas and to evaluate the diagnostic capabilities of MRI. Twenty-four patients with confirmed benign retroperitoneal extra-adrenal paragangliomas who underwent preoperative MRI and surgical resection were enrolled. The patients’ clinical characteristics and MRI features were reviewed by two radiologists. There were no significant differences in the qualitative and quantitative MRI features were determined by the reviewers. High signal intensity in T2-weighted imaging (T2WI) and diffusion-weighted imaging (DWI) was observed in all tumors. In contrast T1-weighted imaging (T1WI) in the arterial phase, 83.33% of the tumors were clearly enhanced. In 87.5% of cases, a persistent enhancement pattern was observed in the venous and delayed phases, and 12.5% of tumors showed a “washout” pattern. The tumor capsule, intratumoral septum and degenerations were visualized in the tumors and may be helpful in the qualitative diagnosis of extra-adrenal paragangliomas in MRI. MRI was useful in locating the position, determining the tumor ranges and visualizing the relationship between the tumors and adjacent structures. The presence of typical clinical symptoms and positivity of biochemical tests are also important factors in making an accurate preoperative diagnosis.

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

BackgroundLeiomyoma 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 presentationWe 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.ConclusionsProstatic leiomyoma is a benign tumor. This case indicates that MRI features of prostatic leiomyoma are helpful for the differential diagnosis of prostate cancer.