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Objectives: To assess the utility of magnetic resonance texture analysis (MRTA) in differentiating renal cell carcinoma (RCC) from lipid-poor angiomyolipoma (lpAML) and oncocytoma., Methods: After ethical approval, 42 patients with 54 masses (34 RCC, 14 lpAML and six oncocytomas) who underwent MRI on a 1.5 T scanner (Avanto, Siemens, Erlangen, Germany) between January 2011 and December 2012 were retrospectively included in the study. MRTA was performed on the TexRAD research software (Feedback Plc., Cambridge, UK) using free-hand polygonal region of interest (ROI) drawn on the maximum cross-sectional area of the tumor to generate six first-order statistical parameters. The Mann-Whitney U test was used to look for any statically significant difference. The receiver operating characteristic (ROC) curve analysis was done to select the parameter with the highest class separation capacity [area under the curve (AUC)] for each MRI sequence., Results: Several texture parameters on MRI showed high-class separation capacity (AUC > 0.8) in differentiating RCC from lpAML and oncocytoma. The best performing parameter in differentiating RCC from lpAML was mean of positive pixels (MPP) at SSF 2 (AUC: 0.891) on DWI b500. In differentiating RCC from oncocytoma, the best parameter was mean at SSF 0 (AUC: 0.935) on DWI b1000., Conclusions: MRTA could potentially serve as a useful non-invasive tool for differentiating RCC from lpAML and oncocytoma., Advances in Knowledge: There is limited literature addressing the role of MRTA in differentiating RCC from lpAML and oncocytoma. Our study demonstrated several texture parameters which were useful in this regard.

Purpose: The study evaluated the usefulness of magnetic resonance imaging (MRI) texture parameters in differentiating clear cell renal carcinoma (CC-RCC) from non-clear cell carcinoma (NC-RCC) and in the histological grading of CC-RCC., Materials and Methods: After institutional ethical approval, this retrospective study analyzed 33 patients with 34 RCC masses (29 CC-RCC and five NC-RCC; 19 low-grade and 10 high-grade CC-RCC), who underwent MRI between January 2011 and December 2012 on a 1.5-T scanner (Avanto, Siemens, Erlangen, Germany). The MRI protocol included T2-weighted imaging (T2WI), diffusion-weighted imaging [DWI; at b 0, 500 and 1000 s/mm 2 with apparent diffusion coefficient (ADC) maps] and T1-weighted pre and postcontrast [corticomedullary (CM) and nephrographic (NG) phase] acquisition. MR texture analysis (MRTA) was performed using the TexRAD research software (Feedback Medical Ltd., Cambridge, UK) by a single reader who placed free-hand polygonal region of interest (ROI) on the slice showing the maximum viable tumor. Filtration histogram-based texture analysis was used to generate six first-order statistical parameters [mean intensity, standard deviation (SD), mean of positive pixels (MPP), entropy, skewness and kurtosis] at five spatial scaling factors (SSF) as well as on the unfiltered image. Mann-Whitney test was used to compare the texture parameters of CC-RCC versus NC-RCC, and high-grade versus low-grade CC-RCC. P value < 0.05 was considered significant. A 3-step feature selection was used to obtain the best texture metrics for each MRI sequence and included the receiver-operating characteristic (ROC) curve analysis and Pearson's correlation test., Results: The best performing texture parameters in differentiating CC-RCC from NC-RCC for each sequence included (area under the curve in parentheses): entropy at SSF 4 (0.807) on T2WI, SD at SSF 4 (0.814) on DWI b500, SD at SSF 6 (0.879) on DWI b1000, mean at SSF 0 (0.848) on ADC, skewness at SSF 2 (0.854) on T1WI and skewness at SSF 3 (0.908) on CM phase. In differentiating high from low-grade CC-RCC, the best parameters were: entropy at SSF 6 (0.823) on DWI b1000, mean at SSF 3 (0.889) on CM phase and MPP at SSF 5 (0.870) on NG phase., Conclusion: Several MR texture parameters showed excellent diagnostic performance (AUC > 0.8) in differentiating CC-RCC from NC-RCC, and high-grade from low-grade CC-RCC. MRTA could serve as a useful non-invasive tool for this purpose.

Introduction: We carried out this study to compare Glu-NH-CO-NH-Lys-(Ahx) [Ga(HBED-CC)] [Ga prostate-specific membrane antigen-11 (PSMA-11)] PET with multiparametric MRI (mpMRI) for the staging of high-risk prostate cancer., Patients and Methods: This was a prospective study in which 36 patients with high-risk prostate cancer were included. The criteria for inclusion were biopsy-proven prostate cancer with a serum prostate specific antigen of at least 20 and/or Gleason's score of at least 8. Each patient then underwent both gallium-68 (Ga)-PSMA PET/computed tomography (CT) and mpMRI including diffusion-weighted whole-body imaging with background body signal suppression within an interval of 1 week and both modalities were compared for staging of primary disease, lymph node, and distant metastasis., Results: The median age of the 36 patients included was 65 years (range: 44-80 years) and the median prostate specific antigen was 94.3 ng/ml (range: 20-19005  ng/ml). Concordance for localization of primary on Ga-PSMA PET/CT and MRI was observed in 19/36 (52.7%) patients. Concurrence for T staging on Ga-PSMA and MRI was observed in 58.3% of patients. Ga-PSMA PET/CT detected higher numbers of patients with regional (29) and nonregional (15) lymph nodes in comparison with MRI (20 and 5, respectively). Concurrence for regional and nonregional lymph node staging was observed in 72.2% of patients. Additional sites of metastatic disease reported on Ga-PSMA PET/CT were to the skeleton in one patient, the lung in two patients, and the liver in one patient., Conclusion: This study suggests that Ga-PSMA PET/CT is useful for lymph node and metastases staging in high-risk prostate cancers, whereas its utility for staging of disease in the prostate is limited.

Focal renal lesions in the background of chronic kidney disease (CKD) present a diagnostic challenge. Contrast administration is usually avoided in such a setting, undermining the usefulness of computed tomography and magnetic resonance imaging. Focal regenerating nodules may occur in the background of CKD and closely mimic renal neoplasms. The aim of the present article was to highlight the salient manifestations of such CKD pseudotumors on different imaging modalities and also to depict the differentiating features from malignancy. Radiologists must be aware of the imaging appearance of this uncommonly talked about entity so as to avoid inadvertent surgery or cause undue anxiety to the patient. [ABSTRACT FROM AUTHOR]

Objectives: The objective of this study was to evaluate the diagnostic accuracy of multiparametric magnetic resonance imaging (mpMRI) and 68Ga prostate-specific membrane antigen positron emission tomography-computed tomography (PSMA PET-CT) and respective quantitative parameters (Ktrans - influx rate contrast, Kep - efflux rate constant, ADC - apparent diffusion coefficient, and SUVmax ratio - prostate SUVmax to background SUVmax ratio) in detection and localization of clinically significant prostate cancer (CSPCa) in D'Amico intermediate- and high-risk group patients (prostate-specific antigen [PSA] >10 ng/ml). Methodology: The study included thirty-three consecutive adult men with serum prostate specific antigen >10ng/ml, and systematic 12 core prostate biopsy proven prostate cancer. All the 33 patients, were evaluated with mpMRI, and 68Ga PSMA PET-CT. The biopsy specimens and imaging were evaluated for 12 sectors per prostate by a predetermined scheme. Results: MpMRI Prostate Imaging Reporting and Data System version 2 (PI-RADS v2) score =3 showed higher sensitivity than 68Ga PSMA PET-CT (96.3% vs. 82.4%), with similar specificity (54.5% vs. 54.5%) (n = 33 patients, 396 sectors). Combined use of MRI and 68Ga PSMA PET-CT in parallel increased sensitivity (99.5%) and NPV (98.7%) for detection of CSPCa and combined use of MRI and 68Ga PSMA PET-CT in series increased specificity (71.8%) and PPV (71.5%) (n = 33 patients, 396 sectors). ADC showed a strong negative correlation with Gleason score (r = -0.77), and the highest discriminative ability for detection and localization of CSPCa (area under curve [AUC]: 0.91), followed by Ktrans (r = 0.74; AUC: 0.89), PI-RADS (0.73; 0.86), SUVmax ratio (0.49; 0.74), and Kep (0.24; 0.66). Conclusion: MpMRI PI-RADS v2 score and 68Ga PSMA PET-CT (individually as well as in combination) are reliable tool for detection and localization of CSPCa. Quantitative MRI and 68Ga PSMA PET-CT parameters have potential to predict Gleason score and detect CSPCa. [ABSTRACT FROM AUTHOR]

Purpose: To compare the diagnostic performance of multidetector computed tomography (MDCT), magnetic resonance imaging (MRI), and MRI with diffusion-weighted imaging (DWI) in the characterization of focal renal lesions. We also compared MDCT and MRI in the staging of renal cell carcinoma (RCC). Materials and Methods: One hundred and twenty adult patients underwent MDCT (40-row and 128-row scanners), MRI (at 1.5 T), and DWI (at b-values of 0 and 500 s/mm2) for characterization of 225 renal lesions. There were 65 malignant neoplasms (44 RCCs), 25 benign neoplasms, 25 abscesses, 45 pseudotumors, 15 hemorrhagic cysts, and 50 benign cysts. A composite gold standard including histology, typical imaging criteria, and follow-up imaging was employed. To determine the diagnostic performance of imaging modalities, area-under-curve (AUC) was calculated by receiver-operating-characteristic analysis and compared. Fisher's exact test was used to compare the diagnostic accuracies and confidence levels with MDCT, MRI, and MRI + DWI. Cross-tabulation was used to assess the precision of MDCT and MRI in RCC staging. Results: AUC for MDCT (0.834) and MRI (0.841) in the classification of benign and malignant lesions were within corresponding 95% confidence interval (CI) (P = 0.88) whereas MRI + DWI had significantly better performance (AUC 0.968, P = 0.0002 and 0.0004, respectively). Both CT and MRI had low specificity (66.9% and 68.8%, respectively), which increased substantially with DWI (93.8%) owing to correct diagnosis of pseudotumors. MRI was superior to CT in diagnosing necrotic RCC and hemorrhagic cysts. MRI + DWI had the highest accuracy (94.2%) in assigning the definitive diagnosis and 97.6% lesions were diagnosed with very high confidence, significantly better than CT and MRI. Both CT and MRI had the same accuracy (86.1%) in RCC staging and evaluation of intravascular thrombi. Conclusions: Characterization of renal lesions was most accurate with MRI + DWI. The latter is also the most suitable modality in diagnosing pseudotumors and evaluating patients with renal dysfunction. CT and MRI were equivalent in RCC staging. [ABSTRACT FROM AUTHOR]

Background: Diffusion.weighted magnetic resonance imaging (DW-MRI) in renal diseases is an evolving field and its potential is yet to be fully realized. Purpose: To study the relationship between apparent diffusion coefficient (ADC) values of renal parenchyma and serum markers of renal function and stage of chronic kidney disease (CKD). Materials and Methods: A retrospective review was performed of all adult patients who underwent DW.MRI (at b.values of 0 and 500 s/mm2) for renal lesions from January 2009 to September 2010 and revealed 88 patients, of which 22 patients had renal dysfunction and 66 had normal renal function. Of these 22, 15 patients were known cases of CKD and were staged depending on disease severity. ADC values were determined for renal parenchyma and compared. Receiver operating characteristic (ROC) curves were drawn to establish cut.off ADC values. Pearson's correlation coefficient (R) was calculated between ADC and renal function parameters. Results: ADC values in patients with renal dysfunction were significantly lower than in patients with normal renal function (2.1133 ± 0.2851 vs. 2.3198 ± 0.1246 (x10-3 mm2/s)). ADC values lower than 2.0354 (x10-3 mm2/s) were seen only with renal dysfunction and higher than 2.4516 (x10-3 mm2/s) were seen only with normal function. There was significant inverse correlation between ADC and serum creatinine (R = -0.530), blood urea (R= -0.502), and significant linear correlation (R = 0.784) with estimated glomerular filtration rate (eGFR). ADC values showed a statistically significant decreasing trend with increasing stage of CKD. Conclusion: ADC values may serve as an additional marker for the presence and degree of renal dysfunction. [ABSTRACT FROM AUTHOR]

Background: Though previous investigators have attempted to evaluate its utility in characterization of focal renal lesions, diffusion-weighted MR imaging (DW MRI) in renal diseases is still an evolving field and its role in predicting the aggressiveness of renal cell carcinoma (RCC) is yet to be established. Purpose: To assess whether apparent diffusion coefficient (ADC) values can be used to determine the nuclear grade and histological subtype of RCCs and to identify the tumor attributes contributing to variation in ADC values. Material and Methods: The institutional ethics committee waived the requirement of informed consent for this retrospective study. The study cohort consisted of 33 patients who underwent MRI (with diffusionweighted imaging at b values of 0 and 500 s/mm2) and were found to have 36 pathologically-proven RCCs. ADC values were determined for solid portions of RCC, cystic/hemorrhagic areas, and normal renal parenchyma. Histological subtype, nuclear grade, and cell count were determined for each lesion. ADC values were compared between different grades and subtypes and correlation with cell count was investigated. Receiver operating characteristic curves were drawn to establish cut-off ADC values. Results: There were 23 low grade (grades I and II) and 13 high grade tumors (grades III and IV). There were 32 clear-cell and four non-clear-cell RCCs. A decreasing trend of ADC values was seen with increasing grade and mean ADC of high grade RCC was significantly lower than low grade (1.3145 vs 1.6982 × 10-3 mm2/s) (P = 0.005). Mean ADC for clear-cell RCC was significantly higher than non-clear-cell RCC (1.6245 vs. 1.0412 × 10-3 mm2/s) (P = 0.005). ADC values higher than 1.7960 × 10-3 mm2/s were seen only with low grade and values greater than 1.4904 × 10-3 mm2/s were seen only with clear-cell RCC. Conclusion: ADC values provide a non-invasive means to predict the nuclear grade and histological subtype of RCC. Cellularity and morphology are other tumor attributes contributing to the variation in ADC values of RCCs. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article "Diffusion-Weighted MRI in Assessment of Renal Dysfunction" by Goya et al., published in the August 2012 issue.